Acronyms, Units, & Constants

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2,4,5-T – 2,4,5-triclorophenoxy-acetic acid

AAI – All Appropriate Inquiry

AAS – Atomic Absorption Spectrophotometry; Atomic Absorption Spectrometry; and Atomic Absorption Spectroscopy

ABPO – Asbestos Ban and Phase-Out Rule of 1989

ABS – Activity-Based Sampling

ACBM – Asbestos-Containing Building Material

ACC – American Chemistry Council, formerly the Chemical Manufacturers’ Association

ACGIH®-  American Conference of Governmental Industrial Hygienists

ACM – Asbestos-Containing Material

ACWP – Actual Cost of Work Performed

ADN – European Agreement concerning the International Carriage of Dangerous Goods by Inland Waterways

ADR – Alternative dispute resolution

ADR – European Agreement concerning the International Carriage of Dangerous Goods by Road

AEA – Atomic Energy Act of 1954

AEGLs – Acute Exposure Guideline Levels

AFB – Air Force Base

AHERA – Asbestos Hazard Emergency Response Act of 1986

AHU – Air Handler Unit

AIA – Asbestos Information Act of 1988

AIDS – Acquired immunodeficiency syndrome

AIHA® – American Industrial Hygiene Association

AL – Action Level

ALARA – As Low as Reasonably Achievable

AMD – Acid Mine Drainage

ANPRM – Advance Notice of Proposed Rulemaking

ANSI – American National Standards Institute

AOPC – Agents of Potential Concern

APHA – American Public Health Association

API – American Petroleum Institute

APR – Air-Purifying Respirator

ARAR – Applicable or Relevant and Appropriate Requirements

ASHARA – Asbestos School Hazard Abatement Reauthorization Act of 1990

ASHRAE – American Society of Heating, Refrigerating, and Air- Conditioning Engineers

ASTM – ASTM International

AT – Averaging Time

ATF – Bureau of Alcohol, Tobacco, Firearms and Explosives

ATSDR – Agency for Toxic Substances and Disease Registry

AVS – Acid Volatile Sulfide

BACT – Best Available Control Technology

BATEA – Best Available Technology Economically Achievable

BBP – Bloodborne Pathogen

BEI® – Biological Exposure Index

BER – Business Environmental Risk

BFI – Bona Fide Intent to Manufacture

BIDS – Biological Integrated Detection System

BLEVE – Boiling Liquid Expanding Vapor Explosion

BLL – Blood Lead Level

BLM – Bureau of Land Management

BMP – Best Management Practice

BOD – Biochemical Oxygen Demand

 BOE – Bureau of Explosives

BPT – Best Practicable Control Technology

BSEE – Bureau of Safety and Environmental Enforcement

BSI – British Standards Institute

BTEX – Benzene/Toluene/Ethylbenzene/Xylene

BW – Body Weight

C – Concentration

C – NIOSH Ceiling Limit

CAA – Clean Air Act of 1970

CAAA – Clean Air Act Amendments of 1990

CAM – Compliance Assurance Monitoring

CAM – Continuous Air Monitor

CAMEO – Computer Aided Management of Emergency Operations

CAP – Corrective Action Plan

CARB – California Air Resources Board

CAS – Chemical Abstracts Services

CBI – Confidential Business Information

CCC – Criterion Continuous Concentration

CCD – Colony Collapse Disorder

CCPS – Center for Chemical Process Safety

CDC – Centers for Disease Control and Prevention

CDL – Commercial Driver License

CEC – Chemical of Emerging Concern

CEMS – Continuous Emissions Monitoring System

CERCLA – Comprehensive Environmental Response, Compensation, and Liability Act of 1980

CERCLIS – Comprehensive Environmental Response, Compensation and Liability Information System

CESQG – Conditionally Exempt Small Quantity Generator

CFATS – Chemical Facility Anti-Terrorism Standards

CFC – Chlorofluorocarbons

CFR – Code of Federal Regulations

CFU – Colony-Forming Unit

CGP – Construction General Permit

CHEMTREC – Chemical Transportation Emergency Center

CHMM – Certified Hazardous Materials Manager

CITES – Convention on International Trade in Endangered Species of Wild Fauna and Flora

CLI – Consumer Labeling Initiative

CLP – Classification, Labelling and Packaging of Substances and Mixtures

CLP – Contract Laboratory Program

CMC – Criterion Maximum Concentration

CMI – Corrective Measures Implementation

CMS – Corrective Measures Study

CMS – Continuous Monitoring System

CNS – Central Nervous System

CO – Carbon Monoxide

CO2e – Carbon Dioxide Equivalent

COC – Chain of Custody

COD – Chemical Oxygen Demand

COI – Chemicals of Interest

COMAT – Company Materials (not manifested as freight)

COTIF – Convention concerning International Carriage by Rail

CPC – Chemical Protective Clothing

CPNTE – Cost Plus not to Exceed Contract

CREC – Controlled Recognized Environmental Conditions

CRSM – Conceptual Risk System Model

CSA – Controlled Substances Act of 1970

CSB – Chemical Safety and Hazard Investigation Board

CSE – Confined Space Entry

CSF – Cancer Slope Factor

CSIA – Chemical Safety Improvement Act of 2014

CSM – Conceptual Site Model

CST – Constituent Subject to Treatment

CV – Cost Variance

CVI – Chemical-Terrorism Vulnerability Information

CVS – Cardiovascular System

CWA – Clean Water Act of 1977

CWC – Chemical Weapons Convention

DBCP – Dibromochloropropane; 1,2-Dibromo-3- Chloropropane

DBP – Dibutyl Phthalate

DBS – Dodecylbenzene-sulfonate

DCS – Distributed Control Systems

DDT – Dichlorodiphenyl-trichloroethane

DEA – Drug Enforcement Administration

DEHP – Bis(2-ethylhexyl) Phthalate

DEP – Diethyl Phthalate

DHS – Department of Homeland Security

DMR – Discharge Monitoring Report

DOD – Department of Defense

DOE – Department of Energy

DOL – Department of Labor

DOT – Department of Transportation

DOT-E – Department of Transportation Exempt

DOT-SP – Department of Transportation Special Permit

DQAPP – Data Quality Assurance Project Plan

DQO – Data Quality Objective

EA – Environmental Assessment

EAP – Emergency Action Plan

e-CFR – Electronic Code of Federal Regulations

ED – Exposure Duration

ED – Electron Diffraction

ED5O – Median Effective Dose

EDB – Ethylene Dibromide

EDX – Energy Dispersive X-Ray Spectroscopy

EE – Estimated Exposure

EEI – Explosive, Extremely Insensitive

EF – Exposure Frequency

EHS – Environment, Health, and Safety

EHS – Extremely Hazardous Substance

EI – Environmental Illness

EIA – Energy Information Administration

EIS – Environmental Impact Statement

EL – Excursion Limit

EL – Exposure Level

EMAS – Eco-Management and Audit Scheme

EMAS-EMS – Eco-Management and Audit Scheme-Environmental Management System

EMS – Environmental Management System

EPA – Environmental Protection Agency

EPCRA – Emergency Planning and Community Right-to-Know Act of 1986

ERG – Emergency Response Guidebook

ERPG – Emergency Response Planning Guidelines

ESA – Endangered Species Act of 1973

ESA – Environmental Site Assessment

ESAP – Environmental Self-Assessment Program

EST – Eastern Standard Time

EU – European Union

EUP – Experimental Use Permit

EV – Earned Value

Ex-Im – Export-Import Bank

FAA – Federal Aviation Administration

FDA – Food and Drug Administration

FEMA – Federal Emergency Management Agency

FEPCA – Federal Environmental Pesticide Control Act of 1972

FFDCA – Federal Food, Drug, and Cosmetic Act of 1938

FFP – Firm Fixed Pricing

FI – Fraction Ingested (from a contaminated source

FIFO – First In-First Out

FIFRA – Federal Insecticide, Fungicide, and Rodenticide Act of 1947

FMCSA – Federal Motor Carrier Safety Administration

FMCSR – Federal Motor Carrier Safety Regulations

FQPA – Food Quality Protection Act of 1996

FRA – Federal Railroad Administration

FRP – Facility Response Plan

FRP – Federal Response Plan

FSP – Field Sampling Plan

FWPCA – Federal Water Pollution Control Act of 1972; Federal Water Pollution Control Amendments

FWS – Fish and Wildlife Service

GHG – Greenhouse Gas

GHGRP – Greenhouse Gas Reporting Program

GHS – Globally Harmonized System of Classification and Labelling of Chemicals

GI – Gastrointestinal

GO – Grid Opening

GPO – Government Printing Office

GWP – Global Warming Potential

HAP – Hazardous Air Pollutant

HASP – Health and Safety Plan

HAZCOM, HazComm – Hazard Communication

HAZMAT – Hazardous Material

HAZOP – Hazard and Operability Study

HAZWOPER – Hazardous Waste Operations and Emergency Response

HBV – Hepatitis B Virus

HCFC – Hydrochlorofluoro-carbon

HCN – Hydrogen Cyanide

HCS – Hazard Communication Standard

HFC – Hydrofluorocarbons

HI – Hazard Index

HIV – Human Immunodeficiency Virus

HMIS – Hazardous Materials Identification System

HMR – Hazardous Material Regulations

HMTA – Hazardous Materials Transportation Act of 1994

HMTUSA – Hazardous Materials Transportation Uniform Safety Act of 1990

HQ – Hazard Quotient

HREC – Historical Recognized Environmental Condition

HSWA – Hazardous and Solid Waste Amendments of 1984

HVAC – Heating/Ventilation/Air-conditioning

IAEA – International Atomic Energy Agency

IAQ – Indoor Air Quality

IARC – International Agency for Research on Cancer

IATA – International Air Transport Association

IATA-DGR – International Air Transport Association Dangerous Goods Regulations

IBC – Intermediate Bulk Containers

IBR – Incorporation by Reference

ICAO – International Civil Aviation Organization

ICAO-TI – International Civil Aviation Organization Technical Instructions

ICC – International Chamber of Commerce

ICP – Integrated Contingency Plan

ICP – Inductively Coupled Plasma

ICS – Industrial Control System

ICS – Incident Command System

IDHL – Immediately Dangerous to Life or Health

IH – Industrial Hygiene

IMDG – International Maritime Dangerous Goods Code

IMO – International Maritime Organization

IPM – Integrated Pest Management

IR – Ingestion Rate

IRIS – Integrated Risk Information System

ISO – International Organization for Standardization

JCAHO – Joint Commission on Accreditation of Healthcare Organizations

LAER – Lowest Achievable Emissions Rate

LBP – Lead-Based Paint

LC50 – Median Lethal Concentration

LD50 – Median Lethal Dose

LDR – Land Disposal Restriction

LEL – Lower Explosive Limit

LEPC – Local Emergency Planning Committee

LEV – Local Exhaust Ventilation

LFL – Lower Flammability Limit

LID – Low Impact Development

LIMS – Laboratory Information Management System

LISA – Low-Input Sustainable Agriculture

LLWPA – Low-Level Waste Policy Act of 1980

LNT – Linear No Threshold

LLP – Landowner Liability Protections

LOAEL – Lowest Observed Adverse Effect Level

LQG – Large Quantity Generator

LVE – Low Volume Exemption

MACT – Maximum Available Control Technology

MCE – Mixed cellulose ester

MCL – Maximum Contaminant Level

MDB – Multilateral Development Bank

MDL – Method Detection Limit

MGP – Manufactured Gas Plant

MHE – Materials Handling Equipment

MMS – Minerals Management Service

MACT – Maximum Available Control Technology

MAK – Maximum Airborne Concentration

MCHM – 4-Methylcyclohexane-methanol

MCL – Maximum Contaminant Level

MCS – Multiple Chemical Sensitivity

MEK – Methyl Ethyl Ketone

MDB – Multilateral Development Bank

MDI – Methylene Diphenyl Diisocyanate

MM – Molar Mass

MNA – Monitored Natural Attenuation

MQL – Method Quantitation Limit

MS4 – Municipal Separate Storm Sewer System

MSDS – Material Safety Data Sheet

MSGP – Multi-Sector General Permit

MSHA – Mine Safety and Health Administration

MTBE – Methyl Tertiary Butyl Ether

MVAC – Motor Vehicle Air Conditioner

MW – Molecular Weight

NAAQS – National Ambient Air Quality Standards

NAICS – North American Industrial Classification System

NARM – Naturally Occurring Radioactive Materials or Accelerator-Produced Radioactive Materials

NCEL – New Chemical Exposure Limit

NCP – National Contingency Plan

ND – Nondetect

NEPA – National Environmental Policy Act of 1969

NESHAP – National Emission Standards for Hazardous Air Pollutants

NFPA – National Fire Protection Association

NIMS – National Incident Management System

NIOSH – National Institute for Occupational Safety and Health

NIST – National Institute of Standards and Technology

NMAM – NIOSH Manual of Analytical Methods

NOA – Naturally Occurring Asbestos

NOAA – National Oceanic and Atmospheric Administration

NOAEL – No Observed Adverse Effect Level

NOC – Notice of Commencement of Manufacture

NOC – Notice of Construction

NOE – No Exposure Certification

NOI – Notice of Intent

n.o.i. – Not Otherwise Indexed

n.o.i.b.n. – Not Otherwise Indexed by Name

NORM – Naturally Occurring Radioactive Material

n.o.s. – Not Otherwise Specified

NOV – Notice of Violation

NPDES – National Pollutant Discharge Elimination System

NPL – National Priorities List

NPP – National Pretreatment Program

NQT – Not Made of Quenched and Tempered Steel

NRC – National Response Center

NRC – Nuclear Regulatory Commission

NRD – Natural Resource Damage

NRDC – Natural Resources Defense Council

NRT – National Response Team

NSPS – New Source Performance Standards

NSR – New Source Review

NSWP – National Stormwater Program

NTP – National Toxicology Program

NURP – Nationwide Urban Runoff Program

NVLAP – National Voluntary Laboratory AccreditationProgram

NWPA – Nuclear Waste Policy Act of 1982

O&M – Operations and Maintenance

OCA – Off-site Consequence Analysis

OCLA – Outer Continental Shelf Lands Act of 1953

ODC – Ozone Depleting Chemicals

ODP – Ozone-Depletion Potential

ODS – Ozone-Depleting Substances

OEL – Occupational Exposure Limit

OHSAS – Occupational Health and Safety Advisory Services

OPA – Oil Pollution Act of 1990

OPCW – Organization for the Prohibition of Chemical Weapons

OPIC – Overseas Private Investment Corporation

OPIM – Other Potentially Infectious Materials

ORM – Other Regulated Material

OSHA, OSHAct – Occupational Safety and Health Act of 1970

OSHA – Occupational Safety and Health Administration

PC – Polycarbonate

P2 – Pollution Prevention

PACM – Presumed Asbestos-Containing Materials

PAH – Polycyclic Aromatic Hydrocarbon

PAPR – Powered Air-Purifying Respirator

PBDE – Polybrominated Diphenyl Ether

PCB – Polychlorinated Biphenyl

PCDD – Polychlorinated Dibenzodioxins

PCDF – Polychlorinated Dibenzofurans Perchloroethylene; Tetrachlorethene;

PCE – Tetrachloroethylene

PCM – Phase Contrast Microscopy

PCMe – Phase Contrast Microscopy – Equivalent

PCP – Polychlorinated Phenol

PCS – Process Control Systems

PEL – Permissible Exposure Limit

PEL-EL – Permissible Exposure Limit – Excursion Limit

PEL-TWA – Permissible Exposure Limit – Time-Weighted Average

PHA – Process Hazard Analysis

PHMSA – Pipeline and Hazardous Materials Safety Administration

PLM – Polarized Light Microscopy

PM – Particulate Matter

PM2.5 – Particulate Matter less than 2.5 microns

PMtO – Particulate Matter less than 10 microns

PMI® – Project Management Institute

PMN – Pre-Manufacture Notification

PMP – Project Management Plan

PNA – Polynuclear Aromatic Compound

POC – Point of Compliance

POP – Performance Oriented Packaging

POP – Persistent Organic Pollutant

POTW – Publicly Owned Treatment Works

POU – Point of Use

PPA – Pollution Prevention Act of 1990

PPE – Personal Protective Equipment

PPOA – Pollution Prevention Opportunity Assessment

PRP – Potentially Responsible Party

PSD – Prevention of Significant Deterioration

PSM – Process Safety Management

PSN – Proper Shipping Name

PSSR – Pre-Startup Safety Review

PTFE – Polytetrafluoroethylene

PV – Planned Value

PVC – Polyvinyl chloride

QAPP – Quality Assurance Project Plan

QA – Quality Assurance

QC – Quality Control

QLFT – Qualitative Fit Test

QNFT – Quantitative Fit Test

QT – Made of Quenched and Tempered Steel

R&D – Research and Development

RACM – Reasonably Available Control Measures

RACM – Regulated Asbestos-Containing Material

RACT – Reasonably Achievable Control Technology

RAGAGEP – Recognized and Generally Accepted Good Engineering Practice

RAMQC – Radioactive Materials in Quantities of Concern

RATA – Relative Accuracy Test Audits

RBCA – Risk-Based Corrective Action

RBPS – Risk-Based Performance Standards

RCRA – Resource Conservation and Recovery Act of 1976

REC – Recognized Environmental Condition

RED – Re-registration Eligibility Document

REL – Recommended Exposure Limit

RFA – Resource Conservation and Recovery Act Facility Assessment

RfD – Reference Dose

RFI – Resource Conservation and Recovery Act Facility Investigation

RFID – Radio Frequency Identification

RFP – Request for Proposal

RFP – Reasonable Further Progress

RH – Relative Humidity

RID – Regulations Concerning the International Carriage of Dangerous Goods by Rail

RI/FS – Remedial Investigation/Feasibility Study

RME – Reasonable Maximum Exposure

RMP – Risk Management Plan

RMP – Risk Management Program

ROD – Record of Decision

RQ – Reportable Quantity

RSP – Radiation Safety Plan

RSO – Radiation Safety Officer

SAED – Selected Area Electron Diffraction

SAP – Sampling and Analytical Plan

SAR – Supplied-Air Respirator

SARA – Superfund Amendments and Reauthorization Act of 1986

SCADA – Supervisory Control and Data Acquisition

SCBA – Self-Contained Breathing Apparatus

SCHC – The Society for Chemical Hazard Communication

SCO – Surface Contaminated Object

SDS – Safety Data Sheet

SDWA – Safe Drinking Water Act of 1996

SEC – Securities and Exchange Commission

SEM – Scanning Electron Microscopy

SEM – Simultaneously Extracted Metal

SEP – Supplemental Environmental Project

SERC – State Emergency Response Commission

SG – Specific Gravity

SI – International System of Units

SIC – Standard Industrial Classification

SIP – State Implementation Plan

SIU – Significant Industrial User

SNAP – Significant New Alternatives Policy

SOC – Systems Operations Control

SODS – Stratospheric Ozone-Depleting Substances

SOP – Standard Operating Procedure

SPCC – Spill Prevention, Control, and Countermeasure

SQG – Small Quantity Generator

SSP – Site Security Plan

STEL – Short-Term Exposure Limit

STOT – Specific Target Organ Toxicity

STP – Site Treatment Plan

STP – Standard Temperature and Pressure

STQ – Screening Threshold Quantity

SUF – Site Use Factor

SV – Schedule Variance

SVA – Security Vulnerability Assessment

SWMU – Solid Waste Management Unit

SWPPP – Stormwater Pollution Prevention Plan

SWTR – Surface Water Treatment Rule

TCE – Trichloroethylene

TCDD – Tetrachlorodibenzodioxin

TCLP – Toxicity Characteristic Leaching Procedure

TEM – Transmission Electron Microscopy

TI – Transport Index

TI – Technical Impracticality

TLV® – Threshold Limit Value

TLV-C – Threshold Limit Value-Ceiling Limit

TMDL – Total Maximum Daily Load

TNT – Trinitrotoluene

TQ – Threshold Quantity

TRI – Toxic Release Inventory

TRU – Transuranic

TRV – Toxicity reference value

TSCA – Toxic Substances Control Act of 1976

TSD – Treatment, Storage, and Disposal

TSDF-  Treatment, Storage, and Disposal Facility

TSS – Total Suspended Solids

TWA – Time-Weighted Average

UCL – Upper Confidence Limit

UEL – Upper Explosive Limit

UIC – Underground Injection Control

UL – Underwriters Laboratory

UMTRCA – Uranium Mill Tailings Radiation Control Act of 1978

UN – United Nations

US – United States

USACE – United States Army Corps of Engineers

U.S.C. – United States Code

USDA – United States Department of Agriculture

USCG – United States Coast Guard

USGS – United States Geological Survey

UST – Underground Storage Tank

UTS – Universal Treatment Standard

UV – Ultraviolet

WBG – World Bank Group

WBS – Work Breakdown Structure

WCS – Worst-Case Release Scenario

WEEL – Workplace Environmental Exposure Level

WIPP – Waste Isolation Pilot Plant

WLA – Waste Load Allocation

WPS – Worker Protection Standard

WQv – Water Quality Volume

XRD – X-Ray Diffraction

XRF – X-Ray Fluorescence

ZPP – Zinc Protoporphyrin

Units & Constants

A – atomic mass number; also area

AD – dermally absorbed dose

amu – atomic mass unit

Bq – becquerel

Bq/g – becquerel per gram

cc – cubic centimeter (also cm3)

Ci – curie

Ci/g – curie per gram

cm – centimeter

cm3 – cubic centimeter (also cc)

°C – degree centigrade (also degree Celsius)

d – density; day

dps – disintegrations per second

°F – degree Fahrenheit

f/cc – fibers per cubic centimeter

ft – feet

ft3-  cubic feet

ft/s – feet per second

g – gram

gal – gallon

gpm – gallons per minute

Gy –  gray

H – Henry’sLaw constant

I – individual prey item; also ingestion intake

J/kg joules per kilogram

K – Monod constant

KO – modified Bessel Function of the second kind and zero order

kg – kilogram

Kow – octanol-water partition coefficient

LF – linear feet

L – liter

lb – pound

m – meter; mass flux

m2/d – square meters per day

m3-  cubic meter

mCi – millicurie

mg – milligram

mg/kg – milligram per kilogram

mg/m3 – milligram per cubic meter

mL or ml – milliliter

mm – millimeter

mol – mole

mppcf – million particles per cubic foot

mrem – millirem

mrem/h  – millirem per hour

mSv – milliseivert

nCi/g – nanocurie per gram

ng/cm2 – nanograms per square centimeter

nSv/h – nanosievert per hour

pCi – picocurie

ppb – parts per billion

ppm – parts per million

psig – pounds per square inch, gauge

Q – flow rate

R – ideal or universal gas constant; also shorthand notation foran alkyl radical

rad – radiation absorbed dose

rem Roentgen effective man s second

s/cc – structures per cubic centimeter s/mm2 structures per square millimeter SF square feet

Sv – sievert

T – time; or tissue concentration

tpy – tons per year

V – stream linear flow

v – volume

v/v – volume per volume ratio w/v weight per volume ratio w/w weight per weight ratio Z atomic number

a – alpha particle; also dispersivity constant beta radiation;   gamma radiation

()+, ()- symbol for dipole moment

µCi microcurie

µg microgram

µg/L microgram per liter

µg/m3 microgram per cubic meter

µL or µl – microliter

µm – micron; also micrometer


Abatement-To reduce or eliminate pollution such as lead, asbestos, or other safety hazard.

Absorption-1) In chemistry, the process by which atoms or molecules enter a liquid, gas, or solid phase. See also adsorption. 2) In biology, chemical transport across cellular membranes into the bloodstream and delivery to an organ or tissue. 3) In radiation science, the capture of neutrons by an atom’s nucleus and the capture of ionizing radiation energy by tissue or matter. 2) In emergency response, a process whereby oil or a hazardous substance penetrates into the pores of a sorbent material and is removed from the environment.

Accredited inspector-1) Under EPA’s Asbestos Model Accreditation Plan, a person who has completed at least a 3-day training course including lectures, demonstrations, hands-on training, respirator fit- testing, and a written exam. [40 CFR 763, Subpart E, Appendix C] 2) Under EPA’s Lead-Based Paint Activities, a person who has completed a minimum of 24 training hours that covers: roles and responsibilities, health effects, regulatory requirements, inspection, sampling, clearance, reporting, and recordkeeping. [40 CFR 745.225]

Accumulation-1) Under RCRA, the collection of wastes for a limited period of time (less than 90 days) provided that the waste is in containers and the generator of the wastes complies with the applicable regulations [40 CFR 262.34]

Accuracy-A data quality indicator of the level of agreement between a measured or calculated value and the true value. EPA recommends that precision and bias be used in lieu of the term accuracy. [EPA Environmental Monitoring and Assessment Program]

Action level (AL)-1) In environmental and hazardous materials management, a contaminant concentration associated with a regulatory requirement. When a measured contaminant concentration exceeds the AL, a management response is typically required. 2) An airborne chemical limit set by OSHA that initiates certain required activities such as exposure monitoring and medical surveillance, and training. ALs are also used on hazardous waste sites to determine when to upgrade to a higher respiratory protection level. [29 CFR 1910, Subpart Z]

Activity-based sampling-Under OSHA and EPA’s OSWER directive, an empirical approach used to measure airborne concentrations of asbestos using personal air monitors rather than predicting or modeling from source material concentration. [OSWER DIRECTIVE #9200.0-68]

Acute-1) A duration that is instantaneous, immediate, or short term, often associated with an event or effect relating to the chemical or physical nature of a toxic or hazardous substance; 2) in regulatory toxicology, refers to dosing that is either one time or limited to one day although the study may last longer than that; 3) in clinical medicine, sudden, severe, having a rapid onset. See also chronic.

Acute exposureExposure that occurs over a short time, usually a few minutes or hours, and no more than 14 days. See also chronic exposure.

Acute health effect-Health effects that manifest themselves over a short period of time, often from a single large dose. See also chronic health effect.

Acute toxicity-1) A measure of the poisonous effect following exposure to a chemical, physical, or biological agent over a relatively short period of time (usually 24-96 hr), generally characterized by the median Lethal Dose (LD50) value; 2) under the OSHA HCS, adverse effects that occur after oral or dermal administration of a single dose, or multiple doses given within 24 hr, or an inhalation exposure of 4 hr; [29 CFR 1910.1200, Appendix A] 3) in toxicology, adverse effects of finite duration occurring within a short time after a single or multiple doses of a test substance; 4) the ability of a substance to cause adverse effects within a short time of dosing or exposure. See also chronic toxicity.

Administrative controls-Under OSHA, changes in work practices that decrease the workplace exposure to a hazardous substance by reducing the duration, frequency, and severity of the exposure. Examples include written safety policies, rules, supervision, schedules, and training.

Adsorption-The adhesion of molecules of gas, liquid, or dissolved solids to a surface (frequently activated carbon). Adsorption increases the concentration of a substance at the interface.

Advection-A transport mechanism that carries a chemical along a flowing medium (water or air) without significant phase change. See also dispersion.

Aerosol-Particles of liquid or solid suspended in air.

Agents of potential concern (AOPC)-Chemicals that are potentially site-related and whose data are of sufficient quality for use in a quantitative risk assessment. Also known as chemicals of potential concern.

Air-purifying respirator-Under OSHA, a respirator with an air- purifying filter, cartridge, or canister that removes specific air contaminants by passing ambient air through the air-purifying element. [29 CFR 1910.134] See also powered air-purifying respirator.

Alcohol-A hydrocarbon that contains an oxygen atom bonded to a hydrogen atom, described as R-OH, where R refers to the hydrocarbon chain and-OH is the hydroxyl group.

Aldehyde-A hydrocarbon that contains a single oxygen connected to a carbon atom by a double bond, forming a carbonyl group. An aldehyde is sometimes described as RCHO where R refers to the alkyl group and C=O represents the carbonyl group.

Aliphatic compounds-Organic compounds that consist of carbons linked in straight, branched, open chain, or closed-ring nonaromatic (alicyclic) structures alkanes, alkenes, and alkynes are aliphatic hydrocarbons.

Alkali metals-Elements in Group 1 of the Periodic Table that are the most reactive metals and among the most reactive of all elements.

Hydrogen is not a metal but is included in this group based solely on atomic structure. The three most common alkali metals are lithium, sodium and potassium.

Alkaline earth metals-Elements in Group 2 of the Periodic Table. The properties of alkaline earth metals are similar to those of the alkali metals, except that they are not quite as soft or reactive. Alkaline earth metals include: beryllium, magnesium, calcium, strontium, barium, and radium.

Alkene-An aliphatic hydrocarbon that contains a carbon-carbon double bond. Also known as olefins.

Alkyne-Aliphatic hydrocarbon containing a carbon-carbon triple bond.

Alkyl group-A type of radical group consisting of an alkane with one hydrogen missing, often denoted by the letter R.

All Appropriate Inquiry (AAI)- Standards established by EPA under the Brownfields Law that define the requirements for assessing the environmental conditions of a property prior to its acquisition.

Alpha (a) particle-A form of ionizing radiation consisting of the nuclei of helium atoms: two protons and two neutrons. With a mass of 4 daltons and a +2 charge, alpha particles are the heaviest form of ionizing radiation. Also known as alpha radiation.

Alternative release scenario-Under EPA’s RMP, a reasonable release scenario that is more likely than the worst-case release scenario and reaches an off-site endpoint. [40 CFR 68.28]

Amide-A derivative of carboxylic acid that has the hydroxyl group (- OH) replaced by an amine group (-NH2).

Amine-An ammonia atom in which one or more hydrogen atoms are substituted by an alkyl group. A primary amine contains one substituted alkyl group (R-NH2); a secondary amine contains two substituted alkyl groups (R,R’-NH) and a tertiary amine contains three substituted alkyl groups (R,R’-NR”); where R, R’, and R” are the alkyl groups.

Amphoteric-A substance that acts as both an acid and a base.

Analytical sensitivity-In chemical analysis, the sample-specific lowest concentration or chemical attribute that a laboratory can detect for a given method.

Antimicrobial pesticide-Under FIFRA, a pesticide that is intended to

  1. a) disinfect, sanitize, reduce, or mitigate growth or developmentofmicrobiological organisms; or b) protect inanimate objects, industrial processes or systems, surfaces, water, or other chemical substances from contamination, fouling, or deterioration caused by bacteria, viruses, fungi, protozoa, algae, or slime; and c) is exempt from or not subject to a or a food additive regulation. Includes also other chemical sterilant, disinfectant, microbiocide, and preservative products. [FIFRA, Section 2(mm)]

Applicability determination-In environmental compliance, an evaluation of which environmental regulations apply to a particular entity or situation.

Applicable or Relevant and Appropriate Requirements (ARARs)- Under CERCLA, applicable requirements are clean-up standards of control, that specifically address a hazardous substance, pollutant, contaminant, response action, location, or other circumstance at a CERCLA site. Relevant and appropriate requirements are clean-up standards that, while not applicable at a CERCLA site, address problems or situations similar to those encountered at the CERCLA site. ARARs can be action-, location-, or chemical-specific.

Arbitration-In law, a method of alternative dispute resolution where an independent person decides on the matter under dispute; this decision may or may not be binding depending on the contract terms.

Area source-Under CAA Section 112, any stationary source of hazardous air pollutants that is not a major source and does not include motor vehicles or nonroad vehicles.

Aroclor -The trade name for PCB mixtures produced in the US from approximately 1930 to 1979. With the exception of Aroclor 1016, each Aroclor mixture has a distinguishing suffix number that indicates the degree of chlorination.

Aromatic compound-A compound characterized by one or more ring structures with alternating double bonds (resonance structures). These compounds have a greater molecular stability because the p orbitals are linked together and electrons are shared over a distance of several atoms.

As Low As Reasonably Achievable (ALARA)-In radiation protection, making every reasonable effort to maintain radiation exposures as far below the dose limits as is practical taking into account technology, economics, and other societal and socioeconomic considerations. [10 CFR 20.1003]

Asbestiform minerals-Fibrous minerals possessing the properties of commercial grade asbestos (e.g. flexibility, high tensile strength, or long, thin fibers occurring in bundles). [40 CFR 763, Subpart E, Appendix A]

Asbestos-The generic name used for a group of naturally-occurring mineral silicate fibers of the serpentine and amphibole series that are regulated under TSCA; specifically, the asbestiform varieties of: chrysotile (serpentine); crocidolite (riebeckite); amosite (cummingtonitegrunerite); anthophyllite; tremolite; and actinolite. [40 CFR 763.83]

Asbestos-Containing Material (ACM)-Under EPA’s Asbestos- Containing Materials in Schools regulations, any material or product regulated under TSCA containing more than 1% asbestos. [40 CFR 763.83]

Asbestos-Containing Building Material (ACBM)-Under EPA’s Asbestos-Containing Materials in Schools regulations, surfacing ACM, thermal system insulation ACM, or miscellaneous ACM found in or on parts of a school building. [40 CFR 763.83]

Asbestos Hazard Emergency Response Act of 1986 (AHERA)-A 1986 law under TSCA Title II that requires local educational agencies to inspect their school buildings for asbestos-containing building material, prepare asbestos management plans, and perform asbestos response actions to prevent or reduce asbestos hazards. AHERA also tasked EPA with developing a model plan for states to accredit persons inspecting and remediating schools.

Asbestos School Hazard Abatement Reauthorization Act (ASHARA)- A 1990 law that extended funding for the asbestos abatement loan and grant program for schools, increased the number of training hours required under the Asbestos Model Accreditation Plan (MAP) and expanded personnel accreditation requirements.

Asbestosis-A serious, progressive, long-term non-cancerous lung disease associated with inhaling asbestos fibers and characterized by scarring of the lung’s air-exchange regions, making it hard to breathe and difficult for oxygen and carbon dioxide pass through the lungs.

Asphyxiant-A substance that blocks the transport or use of oxygen by living organisms (i.e., nitrogen gas, a physical asphyxiant and carbon monoxide, a chemical asphyxiant).

Aspiration-The accidental inhalation of chemicals, aerosols, or food particles directly through the oral or nasal cavity, or indirectly from vomiting, into the trachea and lower respiratory system. [29 CFR 1910.1200, Appendix A]

Assessment end points-One aspect of problem formulation during ecological risk assessment: an explicit expression of the actual environmental value one is interested in protecting (species, ecological resource, or habitat type). [EPA, Ecological Risk Assessment Guidance]

Atomic mass (also called the atomic weight)-One-twelfth the ratio between the mass of a mole of a naturally occurring element and the mass of a mole of carbon-12 atoms. For an element that does not occur naturally, it is usually taken as the atomic mass number of the most stable (longest-lived) isotope.

Atomic mass number-1) In chemistry, the sum of all protons and neutrons in the nucleus. For a specific element, the number of protons is fixed, the number of neutrons can vary, as will the atomic mass number; 2) in radiation science, the sum of the neutrons and protons in a nuclide.

Atomic number (Z)-The number of protons in the nucleus that defines which element the atom represents and its chemical properties.

Attainment area-Under the CAA, a geographic area (a major intrastate or interstate air quality control region) in which levels of a criteria air pollutant meet the NAAQS. [Clean Air Act, Section 107]

Audit-1) An evaluation of the effectiveness of an organization’s business processes, procedures, and control in order to minimize financial risk; 2) an evaluation of the effectiveness of an organization’s environmental management system, including policies, procedures, and compliance activities; 3) a systematic and independent evaluation of a laboratory’s quality activities to ensure quality results.

Autoignition temperature-Under OSHA, the lowest temperature at which a flammable gas or vapor-air mixture will spontaneously ignite without heat, spark, or flame. The autoignition temperature may be influenced by temperature and the presence of catalysts. Materials should not be heated to greater than 80% of the autoignition temperature. [29 CFR 1910, Subpart H] Also called the ignition temperature.

Background radiation-1) In radiation science, radiation observed by a radiation detection system, even with no known radiation source.

Sources include: cosmic rays, naturally-occurring radioisotopes, radon, smoke detectors or x-ray machines, contamination of the detector or counting equipment, radioactive fallout, and other spurious electronic signals. 2) As defined by the NRC, radiation from cosmic sources; naturally-occurring radioactive material, including radon (except as a decay product of source or special nuclear material); and global fallout from testing nuclear explosive devices or from past nuclear accidents. Background radiation does not include radiation from source, byproduct, or special nuclear materials regulated by the NRC [10 CFR 20.1003]

Background radiation dose-The dose (about 100 to 500 mrem/yr in the US) of radiation experienced by the average person, not included in the NRC’s occupational exposure standard. [10 CFR 20.1003]

Basic description-As defined by DOT, the hazardous material shipping description that includes the material’s identification number, proper shipping name, hazard class or division number, packing group, number and type of packages, and other required information depending on the mode of transport. [49 CFR 172.202]

Best Available Control Technology (BACT)-Under the CAA, an emission limitation based on the maximum degree of criteria pollutant reduction from a major emitting facility achievable through production processes and available methods, systems, and techniques, including fuel cleaning, clean fuels, or treatment or innovative fuel combustion techniques. BACT may be a design, equipment, work practice, or operational standard if imposition of an emissions standard is infeasible. [42 U.S.C. 7479, Definitions]

Best Available Technology Economically Achievable (BAT or BATEA)-Under CWA Section 304(b) (2), the water pollution treatment technology that represents the best available economically achievable performance based on industrial wastewater discharges in the same industrial subcategory or category.

Best Conventional Pollutant Control Technology (BCT)-Under CWA Section 304(b)(2), the best technology available to reduce levels of conventional pollutants from existing point source discharges. BCT establishes NPDES effluent limitations for discharges of conventional pollutants from existing industrial point sources after consideration of a two-part cost-reasonableness test. [51 FR 24974]

Best Management Practices (BMPs)- Under EPA’s NPDES, a permit condition used in place of or in conjunction with effluent limitations to prevent or control pollutant discharge. BMPs may be structural or nonstructural such as a schedule of activities, prohibition of practices, maintenance procedures, or other management practices. [40 CFR 122.44(k)]

Best Practicable Control Technology Currently Available (BPT)- Under CWA Section 304(b)(1), the technological basis used to establish NPDES effluent limitations for conventional, toxic, and nonconventional pollutants.

Beta (J and J+) particles -A form of ionizing radiation resulting from negatively and positively charged electrons ejected from the nucleus of some atoms. Also called beta radiation. Beta (J) radiation-See beta particles.

Bias-In chemical analysis, the systematic or persistent distortion of a measurement process that causes errors in one direction (i.e., the expected sample measurement is different from the sample’s true value). Bias can contribute either positive or negative influence and can occur at any point in the testing process.

Bioaccumulation-A process by which chemicals are taken up and sequestered by an organism at a higher concentration than that in its surrounding environment or food. Bioaccumulation can occur by any route of exposure, such as through the respiratory system, by ingestion, or by direct contact with contaminated water, sediment, and pore water in the sediment. Bioaccumulation occurs because the organism’s chemical uptake exceeds its ability to remove the substance from its body. See also bioconcentration and biomagnification.

Bioaccumulation factor-As defined by EPA, the ratio of a contaminant in an organism to its concentration in the ambient environment (usually water) at a steady state where the organism can take in the contaminant through ingestion with its food as well as through direct contact.

Biochemical Oxygen Demand-In water quality, amount of oxygen consumed by organisms from breaking down organic wastes, determined by a laboratory test that determines the amount of dissolved oxygen needed by aquatic organisms in a water sample over a 5-day period (BOD5).

Bioconcentration-1) In ecological science, the process leading to a higher concentration of a substance in an organism than in environmental media to which it is exposed. 2) the ability of aquatic animals to accumulate water-borne chemicals through non-dietary routes (i.e., not through the food web) due to the organism’s ability to retain a chemical faster than it can be metabolized or otherwise excreted. See also bioaccumulation and biomagnification.

Bioconcentration factor-As defined by EPA, the measure of the tendency for a substance in water to accumulate in aquatic organism tissue;. The equilibrium concentration for a substance in fish can be estimated by multiplying the concentration of the substance in the surrounding water by the fish bioconcentration factor for that chemical. This parameter is used to estimate human intake by the aquatic food ingestion route.

Biogeochemical cycle-The more or less circular movement of key chemicals essential to life (such as, carbon, nitrogen, oxygen, and phosphorus) from an organism to the abiotic (earth, air, water) environment, through the biotic environment (living organisms), and finally back to the abiotic environment.

Biohazard-Under DOT and OSHA, a waste or reusable material derived from the medical treatment or biomedical research of an animal or human. Also known as an infectious substance or material. [49 CFR 173.134(a)(5) and 29 CFR 1910.1030(g) (1)(i)]

Biological degradation-Chemical transformation into new compounds due to the action of microorganisms which use the organic contaminant in their metabolic processes as a carbon or energy source.

Biological half-life-The length of time it takes for biological processes to eliminate one-half of a substance from the body, assuming the rate of removal is exponential.

Biomagnification-As defined by EPA, the result of bioaccumulation and biotransfer, by which tissue concentrations of chemicals in organisms at one trophic level exceed tissue concentrations in organisms at the next lower trophic level in a food chain. See also bioconcentration.

Biopesticide-As defined by EPA, pesticides derived from natural materials such as, animals, plants, bacteria, and certain minerals.

Biopesticides fall into three major classifications: Biochemical, Microbial, and Plant-Incorporated Protectants.

Blank-In chemical analysis, an artificial sample used to identify and measure the level of external contamination in the field and the laboratory.

Bloodborne pathogen-Under OSHA BPP, the pathogenic microorganisms present in human blood and can cause disease in humans, including HBV and HIV.

Boiling Liquid Expanding Vapor Explosion (BLEVE)- High vapor pressure flammable liquid that rapidly expands with high energy following the rupture of a closed vessel, resulting in an explosion, intense heat, and a fire ball.

Boiling point-The temperature at which the vapor pressure of a substance equals the atmospheric pressure at sea level, resulting in a change of state from liquid to gas.

Break-bulk-Under DOT, bulk packages designed to be handled individually, palletized, or unitized (as opposed to bulk and containerized freight). [49 CFR 171.8]

Brisance of an explosive-The rapidity with which an explosive develops its maximum pressure; an estimate of the destructive power of a given explosive. Brisance is normally compared to Trinitrotoluene (TNT=1.00).

Brownfield site-As defined by EPA in the Small Business Liability Relief and Brownfields Revitalization Act (2002), real property, the expansion, redevelopment, or reuse of which may be complicated by the presence or potential presence of a hazardous substance, pollutant, or contaminant; typically a former industrial or commercial site.

Buffer capacity-In chemistry, the ability of a weak acid or a weak base to resist changes in pH.

Bulk packaging-Under DOT, a packaging, including a transport vehicle or freight container, in which hazardous materials are loaded with no intermediate form of containment. Additionally, a bulk packaging has: a) A maximum capacity greater than 450 L (119 gal) as a receptacle for a liquid; b) A maximum net mass greater than 400 kg (882 lb) and a maximum capacity greater than 450 L (119 gal) as a receptacle for a solid; or c) A water capacity greater than 454 kg (1,000 lb) as a receptacle for a gas. [49 CFR 171.8]

Bulk sample– Under EPA’s Asbestos-Containing Materials in Schools Model Accreditation Plan, a sample of suspected media (e.g., soil or dust) that is obtained from a site in order to be analyzed microscopically for asbestos content.

Business Environmental Risks (BER)- Under the AAI standard, a risk that can have a material environmental or environmentally-driven impact on the business associated with the current or planned use of a commercial real estate parcel; not necessarily limited to those in-scope environmental issues investigated in the assessment. [ASTM]

By-product material-As defined by NRC, a) a radioactive material from the process of producing or using special nuclear material; b) with the exception of underground ore bodies, the tailings or wastes produced by the extraction or concentration of uranium or thorium and Radium- 226. [10 CFR 20.1003]

Cancer slope factor-A value, in inverse concentration of dose units, derived from the slope of a dose-response curve for carcinogenic effects.

Used, in combination with the exposure, to predict the potential number of excess cancers that will arise in response to lifetime exposure to an agent.

Carbon dioxide equivalent (CO2e)- As defined by EPA, a metric measure used to compare emissions from various greenhouse gases based upon their global warming potential (GWP), derived by multiplying the tons of the gas by the associated GWP.

Carbonyl group-A functional group that consists of an oxygen atom connected by a double bond to a carbon atom, sometimes described as C=O. If the carbon atom is bonded to one or more hydrogen atoms, the resulting molecule is an aldehyde. If the carbon atom is bonded to two alkyl groups, the resulting molecule is a ketone.

Carboxylic functional group-A carbon atom joined by a double bond to one oxygen and a single bond to another. Both carboxylic acids (RCO2H) and carboxylic esters (RCO2R’) contain the carboxylic functional group, where R and R’ refer to alkyl group.

Carcinogen-1) In environmental health and toxicology, an agent capable of increasing the incidence of malignant neoplasms, thus causing cancer; 2) Under OSHA, a list of 13 chemicals for which there are specific regulations [29 CFR 1910.1003]; 3) Under OSHA’s HCS, a chemical that has been determined by IARC to be a carcinogen, or listed by the NTP as a carcinogen or potential carcinogen [29 CFR 1910.1200]; 4) Under EPA’s RCRA Corrective Action regulations, chemicals listed in EPA’s Carcinogen Assessment Group, and included in Appendix VIII of 40 CFR 261.

CAS number-The unique number assigned by the CAS to each chemical, usually comprised of three sets of digits separated by hyphens, as in 7782-50-5 for chlorine.

Catalyst-A material that accelerates the rate at which a reaction occurs but is not consumed by the reaction.

Catalyze-To increase the rate of reaction by acting as a catalyst.

Caustic-The property of a material characterized by its ability to burn or corrode tissue, for example sodium hydroxide or potassium hydroxide.

Ceiling concentration limit, Ceiling limit– See ceiling value.

Ceiling value-Under OSHA, airborne chemical exposure limit for a toxic substance in a worker’s breathing zone that should never be exceeded, assuming an 8-hr work shift, 40 hr/week. [29 CFR 1910.1000]

Cementation-A treatment technology for liquid hazardous or radioactive wastes, involving adding a binding agent, such as portland cement, that solidifies and stabilizes the toxic components of the waste to limit its movement in the environment.

Chain of Custody (COC)-1) In environmental sampling and analysis, the documentation of responsibility for a substance from collection to analysis; 2) in hazardous materials management, the documentation of responsibility for a substance from the manufacturer to the distributor, to the user, or to the person(s) ultimately responsible for waste disposal.

Challenge agent-Under the OSHA respiratory protection program, a chemical used in a respirator qualitative fit test to determine adequacy of fit, seal, and leakage. [29 CFR 1910.134]

Change of state-In chemistry, the process that occurs when matter changes from one physical form to another such as solid to liquid (melting) or solid to gas (sublimation).

Characteristic waste (D-codes)- Under RCRA, a hazardous waste that exhibits the properties of ignitability, corrosivity, reactivity, or toxicity as defined by specific criteria listed in 40 CFR 261, Subpart C.

Chemical asphyxiant-A chemical that interferes with the body’s ability to use oxygen, such as carbon monoxide or hydrogen sulfide.

Chemical of Interest (COI)-Under CFATS, a substance or material, critical to government mission and national economy, listed in 6 CFR 27 Appendix A and, when shipped, stored, used, or received by a facility, presents one or more of four security issues: release; theft and diversion; sabotage, and contamination. [6 CFR 27.105]

Chemical Oxygen Demand (COD)-A water quality parameter based on a laboratory test that, using a chemically oxidizing agent, measures the amount of oxygen required to oxidize the organic (and inorganic) matter in wastewater; generally expressed in milligrams O2 per liter.

Chemical Protective Clothing (CPC)-Under the OSHA Personal Protective Equipment Standard, clothing and equipment used to shield or isolate a worker from the chemical, physical, and biological hazards that may be encountered during hazardous materials operations. [29 CFR 1910, Subpart I]

Chemicals of Emerging Concern (CEC)-In water quality, chemical constituents that have not been historically considered to be contaminants but are present in the environment on a global scale.

Commonly derived from municipal, agricultural, and industrial wastewater sources and pathways, these chemicals include nanoparticles, pharmaceuticals, personal care products, estrogen-like compounds, flame retardants, detergents, and industrial chemicals. Also known as contaminants of emerging concern.

Chemicals of potential concern-See agents of potential concern.

Chlorofluorohydrocarbons (CFCs)- Under the 1987 Montreal Protocol, chemicals used for refrigeration, air conditioning, packaging, insulation, solvents, or aerosol propellants that drift into the upper atmosphere where they break down ozone; also considered to be greenhouse gases.

Chronic-1) Long term, a duration that occurs over a long period of time, several weeks, months or years; 2) in experimental toxicology, studies that last more than 90 days and/or include a large part of the lifetime of an organism.

Chronic effect-A long-term consequence that develops slowly and/or has a long lasting course. See also, acute effect.

Chronic exposure– Continued exposure or exposures occurring over an extended period of time, or a significant fraction of the organism’s or population’s lifetime, also known as long-term exposure. See also, acute exposure.

Chronic health effect-A health effect that develops slowly or has a long lasting course, may be due to many small doses over a long time. See also acute health effect.

Chronic toxicity-1) adverse health effects that result from chronic exposure; 2) effects that persist over a long period of time whether or not they occur immediately upon exposure or are delayed. See also acute toxicity.

Cleavage fragment-Under EPA’s asbestos regulations, a fragment that may be formed by crushing, mining, or breaking massive asbestos materials. [40 CFR 763]

Closed loop recycling-Under RCRA, a system in which a process waste is conveyed through closed systems to a storage vessel and then recycled before returning the reprocessed material to the production system. such as the storage and distillation of a spent solvent. [40 CFR 261.4(a)(8)]

Closing the loop-Following pollution prevention principles, purchasing products manufactured with post-consumer recycled content in order to create a market for such products and reduce the amount of virgin materials used in manufacturing.

Closure-1) Under CERCLA, agency approval of post-remediation verification testing and reporting that a CERCLA site meets applicable regulatory criteria and standards; 2) under RCRA, a procedure to ensure that when a hazardous waste management facility ceases to operate, it will not pose a future threat to human health and the environment. [40 CFR 264 and 265]

Combination packaging-Under DOT, a packaging that consists of one or more inner packagings secured in a non-bulk outer packaging. It does not include a composite packaging. [49 CFR 171.8]

Combustible-Capable of burning. For hazardous materials management, the term may have different definitions depending on the nature of the substance (liquid, solid, dust) and the regulatory standard that is being applied (OSHA, DOT, and NFPA).

Combustible liquid-1) Under OSHA, a Hazard Communications Standard category for a liquid that has a flashpoint between 100° F – 200° F (37.8° C – 93.3° C; [29 CFR 1910.106] 2) under DOT, any liquid that does not meet the definition of any other hazard class and has a flashpoint in the range of 140° – 200° F. [49 CFR 173.120(b)(1)]

Commerce-Under DOT, trade, traffic, or transportation within the jurisdiction of the United States: between a place in a State and a place outside of such State, including a place outside of the United States. [49 CFR 171.8]

Common law-The body of law derived from judicial decisions, rather than from statutes or constitutions. [Black’s Law Dictionary, 2009]

Competent person-Under OSHA, a person capable of identifying existing and predictable hazards in the surroundings or working conditions which are unsanitary, hazardous, or dangerous to employees, and who has authorization to take prompt corrective measures. [29 CFR 1910.12 and 29 CFR 1926, Subpart C]

Compliance Assurance Monitoring (CAM)-Under the CAA, monitoring required by sources needing Title V operating permits that provides a reasonable assurance of compliance with the applicable requirements. [40 CFR Parts 64, 70, and 71]

Compliance-based audit-In environmental management systems, an audit focused on regulatory requirements and company policies and procedures.

Composite packaging-Under DOT, packaging that consists of an outer packaging and an inner receptacle, and constructed so that the inner receptacle and outer packaging form and remain as an integrated single unit. [49 CFR 171.8]

Composite sample-A sample consisting of multiple temporally or spatially discrete media that are combined, thoroughly homogenized, and treated as a single sample.

Compressed gas-A hazardous material exhibiting a physical hazard due to container pressurization. For hazardous materials management,

the term may have different meanings depending on the nature of the gas (liquefied, non-liquefied, dissolved; flammable or nonflammable) and the regulatory standard that is being applied.

Concentration-In chemistry, the ratio between the solvent and the various solutes, also used to express the ratio between the individual component and the complete material in a mixture. Can be expressed on a weight to volume, weight to weight, or volume to volume basis.

Conceptual Risk System Model (CRSM)-In ecological risk assessment, conceptual model for site risk assessment that provides a graphical depiction of the spatial and temporal relationships between hazardous material sources and their fate in the environment to a potentially exposed human population, biota, or critical habitat.

Conceptual Site Model (CSM)-In ecological risk assessment, conceptual model used as a primary vehicle for communicating technical data on a given site that graphically describes the site, its physical environs, and ecological features, as well as providing indications of modes of transport.

Confined Space Entry (CSE)-Under OSHA, a special process for safe entry and work in a permit-required confined space [29 CFR 1910.146]

Congener-In chemistry, one of two or more substances related to each other by origin, structure, or function.

Construction General Permit (CGP)- Under NPDES, a general permit that regulates stormwater discharges from construction activities that disturb one or more acres, or smaller sites that are part of a larger common plan of development or sale.

Contained-in policy-Under RCRA, a policy that identifies when contaminated media is considered to no longer “contain” hazardous waste. [40 CFR 260, et. al]

Container-1) Under the OSHA, any can, barrel, or drum [29 CFR 1910.106]; 2) under RCRA, any portable device in which a material is stored, transported, treated, disposed of, or otherwise handled. [40 CFR 260.10]

Contaminant-Any substance that enters a system (the environment, human body, food, etc.) where it is not normally found.

Contamination-See radioactive contamination.

Contingency plan-1) In hazardous and environmental management, plans that outline an organization’s course of action to an incident or disaster; 2) under RCRA, a document setting out an organized, planned, and coordinated course of action to be followed in case of a fire, explosion, or release of hazardous waste or hazardous waste constituents which could threaten human health or the environment. [40 CFR 260.10]

Continuity planning-1) In business, planning to ensure continued operations if a place of business is affected by different levels of disaster such as localized short term disasters, long-term facility problems, and permanent loss of a building; 2) in site remediation, a strategy to ensure that the selected remedial technology will continue to protect human health and the environment in the event of a catastrophe or business failure.

Contract-In law, an agreement between two or more parties creating obligations that are enforceable or otherwise recognizable as law. [Black’s Law Dictionary, 2009]

Controlled Recognized Environmental Conditions (CREC)- In the AAI standard, recognized environmental conditions resulting from past releases of hazardous substances or petroleum products at a site that have been addressed to the satisfaction of the applicable regulatory authority, with contaminants allowed to remain in place subject to implementing required controls (institutional or engineering). [ASTM]

Conventional pollutant-Under CWA Section 304(a)(4), water quality parameters that are required and monitored under NPDES programs: biochemical oxygen demand (BOD5), total suspended solids, fecal coliform, pH, as well as oil and grease (see 44 FR 44501).

Corrective action-Under HSWA, the response actions taken to address “all releases of hazardous waste or constituents from any solid waste management unit.” including, where necessary, releases that extend beyond the facility property boundary. [HSWA3004(u)]

Corrective action plan-Under RCRA, a framework for developing a site-specific schedule of compliance to be included in a permit or corrective action order. The four components of a corrective action plan include: interim/stabilization measures, RCRA facility investigation, corrective measures study, and corrective measures implementation.

Corrective Measures-Under RCRA, realistic remedies for removal, containment, and/or treatment of contamination at a hazardous waste site that are developed taking into consideration the extent, nature, and complexity of releases and contamination.

Corrosive-1) In chemistry, a chemical that, due to its pH, has the capacity to burn or injure skin or eyes on contact. Typically, corrosives have pHs above 7; 2) under OSHA, a chemical that causes visible destruction of, or irreversible alterations in, living tissue by chemical action at the site of contact namely, visible necrosis through the epidermis and into the dermis. [29 CFR 1910.1200, Appendix A]; 3) in toxicology, causing a surface-destructive effect on contact such as, visible destruction of the skin, eyes, or the respiratory or gastrointestinal tract lining; 4) under DOT, capable of causing full thickness destruction of human skin or causing a severe corrosion rate on steel or aluminum. [49 CFR 173.36]

Corrosivity-1) A characteristic of a corrosive material, capable of causing burns, injury to skin, or weakening metal containers or structures; 2) under RCRA, one of the properties of a characteristic waste. [40 CFR 261, Subpart C]

Covalent bond-A type of bond in which the valence electrons are shared equally between two atoms.

Covered facility-Under CFATS, a facility with a high level of security risk due to the type and quantity of the chemical substances handled that is required to follow the DHS Risk-Based Performance Standards. [6 CFR 27]

Cradle-to-grave liability-Under RCRA, a hazardous waste management strategy that requires generators to ensure that hazardous waste is properly managed from the moment it is produced, or the point of generation, through final disposal. [40 CFR 261]

Credible evidence rule-Under the CAAA, a requirement that the duration of a violation is established by “any credible evidence,” including evidence other than data from an applicable emissions test method.

Criteria air pollutant-Under the CAA, six pollutants (carbon monoxide, lead, nitrogen dioxide, ozone, particle pollution, sulfur dioxide) that are considered harmful and for which EPA has established national ambient air quality standards.

Criterion continuous concentration– Under CWA Section 304(a), an estimate of the highest concentration of a material in surface water to which an aquatic community can be exposed indefinitely without resulting in an unacceptable effect.

Criterion maximum concentration– Under CWA Section 304(a), an estimate of the highest concentration of a material in surface water to which an aquatic community can be exposed briefly without resulting in an unacceptable effect.

Cryogenic liquid-Under DOT, a refrigerated liquefied gas having a boiling point below -90 °C (-130 °F) at 101.3 kPa (14.7 psia) absolute.

Dangerous goods-Under the UN Model Regulations, substances, including mixtures and solutions, and articles that are assigned to one of nine hazard classes according to the hazard or the most predominant of the hazards they pose in transport.

Dangerous When Wet-Under DOT, a material that is likely to become spontaneously flammable or to give off flammable or toxic gas when in contact with water. [49 CFR 172.124]

Data quality objectives-The performance and acceptance criteria used to clarify chemical analysis targets and goals, define the appropriate type of data to be collected and evaluated, and specify the tolerance limits for potential data or decision errors.

Decay-In radiation science, the spontaneous process by which an unstable atomic nucleus atom gives up energy (i.e., alpha particles, beta particles, and gamma rays) and moves to a more stable state.

Decontamination-In hazardous materials management, the process of changing a potentially toxic or hazardous substance to a less hazardous state by neutralization, elimination, removal, etc.

Deflagration-In hazardous materials management, rapid combustion with an explosion front that propagates at subsonic speed. See also detonation.

Degradation-In environmental science, the loss of a chemical in the environmental medium due to transport, or due to the biotic or abiotic breakdown of the chemical into other compounds or elements.

Dense Non-Aqueous Phase Liquid (DNAPL)-A liquid that is not miscible with water and has a density greater than water.

Dermal absorption-see skin absorption.

Dermatitis-A skin inflammation that may be caused by contact with hazardous materials, irritation, allergy, or infection.

Detection limit-In chemical analysis, the minimum concentration of an analyte in a sample that can be measured with a high level of confidence.

Detonation-An explosion with a front that propagates with a velocity faster than the speed of sound. See also deflagration.

Digestion-In chemical analysis, using a corrosive or enzymatic agent to break down a complex sample matrix to release the analyte (such as treating soil samples by heating with nitric acid to dissolve metals).

Direct discharge-Under the CWA, discharge of effluent to surface waters regulated under the NPDES.

Direct effect-In ecological risk assessment, the adverse response when an environmental stressor acts directly on one or more ecosystem components. See indirect effects.

Directed sampling-In auditing, using a specified group of items to determine whether a condition exists based on specific information received.

Discharge Monitoring Report (DMR)-Under the CWA, monitoring report required pursuant to federal or state NPDES programs that provides information about the permitted discharge, measured parameters, and compliance with permit limits.

Dispersion-In environmental fate and transport, a mechanism driven by mechanical or compositional inhomogeneities in the system (diffusion or turbulence). See also advection.

Direct preparation-In asbestos analysis, a method whereby the filter is examined directly by microscopy and does not undergo a separation step. See also indirect preparation.

Disposal-Under RCRA, the destruction of a waste (for example, incineration, energy recovery, or chemical reaction) or putting it in or on the ground (for example, landfilling or land application). [RCRA Section 3004(a)]

Dioxin-like-A family of chemicals (chlorinated dioxins, furans, and polychlorinated biphenyls) that have similar toxicity and characteristics.

Dose-1) In toxicology, the amount of a substance which is taken up or absorbed by an organism, organ, or tissue over some time period; 2) in radiation science, the energy or amount of photons absorbed by an irradiated object over a specific time duration divided by area or volume.

Dosimeter-A device or instrument that measures the direct or indirect radiation dose received by a person.

Duplicate-In environmental sampling, a quality control check that involves additional aliquots or measurements of the same sample material taken under the same or comparable conditions to determine the level of precision and accuracy. Also known as a replicate sample.

Dynamic equilibrium-A state of balance that exists when the chemical of interest is able to engage in reversible reactions or move between phases.

Ecological risk assessment-Under CERCLA, a baseline risk assessment of a contaminated site that characterizes the current and potential threats to human health and the environment. [40 CFR 300.430; EPA, Ecological Risk Assessment Guidance]

Economic poison-Substances or mixtures of substances, such as insecticides, rodenticides, fungicides, or herbicides that are toxic but have and are used to control pests that have economic significance.

Ecosystem management-A process that integrates scientific knowledge of ecological and sociopolitical relationships to conserve

ecological services, restore natural resources, and protect native ecosystem integrity over the long term.

Effective dose-The amount of energy absorbed by a body tissue or organ, weighted by the biological effects.

Effluent limitations-Under NPDES, technology-based and water quality-based industry-specific standards that apply to NPDES discharge permits, constituting limitations on concentrations, rates, and other aspects of discharges.

Element-In chemistry, the purest, simplest form of a substance that is comprised of one or more like atoms and is characterized by its atomic number.

Emergency Action Plan (EAP)- Under OSHA, a, employer’s plan for their employees’ safe exit from the building in the event of an emergency. [29 CFR 1910.38 (a)]

Emergency Response Guidebook-In hazardous materials transportation, a guidebook published by DOT and international transportation agencies intended to assist first responders during the initial phase of a dangerous goods/hazardous materials transportation incident.

Emergency response incident-The actual or threatened release of a hazardous chemical or substance, extremely hazardous substance, or hazardous waste that could harm human health.

Emergency response plan-A business-wide policy setting forth the environmental goal of the business, identifying the persons responsible for management of the emergency response plan, and establishing the role of particular persons during an incident.

Emergency Response Planning Guidelines (ERPG)-AIHA’s

guidelines for responding to potential releases of airborne substances and for use in community emergency planning.

Empty container-1) Under OSHA, DOT, and RCRA regulations for acute hazardous wastes on the F and P lists, a container where the hazard is completely gone; 2) for other RCRA materials, a container is empty as long as commonly employed practices were used to empty the container and no more than one inch of the substance remains or 3% (by weight) remains in containers smaller than 110 gal; or no more than 0.3% remains in containers larger than 110 gal. [40 CFR 261.7]

Endocrine disrupter-Any exogenous substance that interferes with the normal function of hormones and causes adverse health effects in an intact organism, its progeny or (sub) populations.

Engineering controls-Under OSHA, the preferred method of hazard prevention and control that involves designing the facility or equipment to prevent exposure to hazardous chemicals or noise by removal, enclosures, or barriers and ventilation.

Engulfment-Under OSHA, the surrounding and effective capture of a person by a liquid or finely divided (flowable) solid substance that can be aspirated to cause death by filling or plugging the respiratory system or that can exert enough force on the body to cause death by strangulation, constriction, or crushing.

Environmental assessment (EA)-1) Under NEPA, an assessment of the likelihood of impacts from an action and its reasonable alternatives, whose outcome is either a Finding of No Significant Impact or a recommendation to do an Environmental Impact Statement; 2) under the AAI rule, a property evaluation for the presence of hazardous materials that may impact the property’s economic value.

Environmental impact statements (EIS)-Under NEPA, comprehensive assessment of the likelihood of impacts from an action and its reasonable

alternatives, whose outcome is a Record of Decision; with or without mitigation.

Environmental management plan-A plan that outlines the steps an organization will take to comply with environmental regulations and protect the environment that may be used to implement an environmental management system.


Environmental management system-As defined by EPA, a set of processes and practices that enable an organization to reduce its environmental impacts and increase its operating efficiency.

Environmental policy-The foundation of an environmental management system that demonstrates top management commitment.

Environmental Professional-Under the AAI rule, a professional who meets the education and experience requirements and is capable of conducting an Environmental Assessment. [ASTM]

Environmental risk assessment-As defined by EPA, a process used to characterize the nature and magnitude of health risks to humans and ecological receptors from chemical contaminants and other stressors that may be present in the environment.

Epidemiology-In public health, the study of the distribution and determinants of health-related states or events in specified populations and the application of this study to control health problems.

Ether-A hydrocarbon that contains an oxygen atom bonded to a carbon atom and is described as R-O-R, where R refers to the hydrocarbon chain.

Eutrophication-An adverse change in the chemical and biological status of a body of water following oxygen depletion caused by decay of organic matter resulting from high primary production as a result of

enhanced input of nutrients.

Exceptions-Under DOT, regulations that exempt a shipper from certain HMR requirements.

Exclusive use-Under DOT, a requirement that reserves a vehicle to only ship radioactive materials. [49 CFR 173.403]

Excursion limit-Under OSHA, a peak limit, measured as a Time Weighted Average, the length to be determined by the relevant standard.

Explosion-A chemical reaction that produces a shock wave.

Explosive-Capable of exploding. For hazardous materials management, the term may have different meanings depending on the nature of the substance (liquid, solid, dust) and the regulatory standard that is being applied (OSHA, DOT, and NFPA).

Exposure-1) Contact with a substance by swallowing, breathing, or touching the skin or eyes. Exposure may be short-term (acute), of intermediate duration, or long-term (chronic); 2) the concentration, amount or intensity of a particular agent that reaches the target population, organism, organ, tissue or cell, usually expressed in terms of concentration, duration, and frequency; or intensity; 3) the process by which a substance becomes available for absorption.

Exposure assessment-The process of estimating, either qualitatively or quantitatively, the magnitude, frequency, duration, and route of exposure. An exposure assessment also describes how often and for how long an exposure occurred, and the nature and size of a population exposed.

Externalized cost-In business, a production cost not paid for by the producer; for example, end-of-life disposal costs.


Extremely hazardous substance (EHS)-Under CERCLA, a substance listed in 40 CFR 355, Appendix A and B as capable of causing serious irreversible health effects from accidental releases.

Facility-1) under RCRA, a property or location where hazardous waste is generated, treated, stored, or disposed of that is under the control of the same owner or operator; 2) under the CWA and for the purposes of SPCC, any mobile or fixed, onshore or offshore building, structure, installation, equipment, pipe, or pipeline (other than a vessel or a public vessel) used in oil well drilling operations, oil production, oil refining, oil storage, oil gathering, oil processing, oil transfer, oil distribution, and waste treatment, or in which oil is used; 3) under the CAA, it includes any building, structure, equipment, installation, or substance-emitting stationary activity that belongs to the same industrial group, is located on one or more contiguous properties, and is under the control of the same person.

Federal nexus-Under NEPA, a project that receives funding from the federal government, or requires a permit or other federal decision

Feedstock-The material ingredients used to manufacture a product, whether virgin raw materials, preconsumer or postconsumer recycled content.

Fire-related PCB incident-Under TSCA, a situation where heat and/or pressure could result in rupture and release of PCBs.

Fit factor-Under OSHA, the numerical value that rates the degree of fit of a respirator on one’s face. It is a ratio of the concentration outside the respirator to the concentration inside as determined by QNFT. [29 CFR 1910.134]

Fit test -Under OSHA, a test to determine a respirator’s ability to adequately seal to a user’s face. It can be performed qualitatively or quantitatively. [29 CFR 1910.134]


Flammable-The property in which a material is easily ignited and burns with extreme rapidity, as indicated by one or more recognized test methods. Includes the OSHA hazard categories of flammable gas, flammable liquid, flammable solid and the DOT flammable gas, flammable liquid. [29 CFR 1910.1200; 1910.106 and 49 CFR 173.115;


Flashpoint-Under OSHA, the minimum temperature at which a liquid within a test vessel gives off vapor in sufficient concentration to form an ignitable mixture with air near the surface of the liquid; normally indicates susceptibility to ignition. [29 CFR 1910.106 and 29 CFR 1910.1200(c)]

Float-In project management, the amount of time a task can be delayed without impact to the overall schedule.

Food chain-The energy transfer pathways from producers (green plants) through a series of consumers (herbivores, carnivores) and decomposers.

Food web-All of the relationships and pathways among organisms within an ecosystem; composed of interconnected food chains.

Friable-Under EPA’s asbestos regulations, a material which, when dry, can be crumbled, pulverized, or reduced to powder by hand pressure.

Friable asbestos material-A friable material containing more than 1% asbestos when analyzed by PLM with point counting. [40 CFR 763.83]

Fugitive Dust Source-Under the CAA, particulates that are lifted into the air either by man-made or natural activities. Fugitive dust sources include roadways, dried paste, handling oxide, and paste mixing.

Fume-The condensed portion of a heated or burned metal, i.e., a welding fume; usually in the form of a solid particulate suspended in air.

Fumigant-Under FIFRA, a pesticide that is applied as a gas or aerosol.

Functional group-In organic chemistry, a compound in which an atom other than carbon or hydrogen is substituted onto (or into) the hydrocarbon skeleton. A functional group changes the physical and chemical properties of the base hydrocarbon.

Fungicide-Under FIFRA, an agent that kills mold or fungi, especially ones causing plant diseases.

Gamma (y) radiation-High-energy electromagnetic rays (light rays) emitted from the unstable nucleus of a radioactive atom with a range in air that extends up to miles.

Generator knowledge-Under RCRA, a criteria for making a hazardous waste determination and includes: facility information, chemical ingredients, constituents, SDSs, sampling and analysis, literature, and product specifications.

Genotoxic carcinogens-Carcinogens that affect a cell’s DNA, causing cell death or mutations.

Genotoxicity-Under the OSHA HCS, applies to agents or processes that alter the structure, information content, or segregation of DNA, including those which cause DNA damage by interfering with normal replication processes, or which temporarily alter its replication.

Genotoxicity test results are usually taken as indicators for mutagenic effects. [29 CFR 1910.1200, Appendix A]

Geometric isomer-A type of isomer in which the molecules have the same connectivity but different arrangements of atoms in space. Also known as a stereoisomer.


Germ cell mutagenicity-1) In toxicology, the ability of a substance to alter a person’s DNA or genetic makeup; 2) under the OSHA HCS, substances known to induce heritable mutations or to be regarded as if they induce heritable mutations in the germ cells of humans. [Appendix A TO §1910.1200]

Green infrastructure-In stormwater management, engineered systems that employ or simulate natural processes to infiltrate, evapotranspirate, or reuse stormwater or runoff on the site where it is generated.

Green roof-A vegetated roofing system designed to absorb precipitation and release it through evaporation and plant respiration, while draining excess runoff.

Greenhouse gas (GHG)-Any gas that absorbs infrared radiation in the atmosphere including carbon dioxide, methane, nitrous oxide, ozone, chlorofluorocarbons, hydrofluorocarbons, perfluorocarbon, and sulfur hexafluoride.

Groundwater recovery-A ground water remediation technique involving drilling wells in the aquifer to bring the water to the surface for treatment, followed by use or reinjection.

Half-life-1) In radiation science, the time required for one-half of the radioisotope atoms present to undergo nuclear disintegration; 2) in chemistry, the time required for the concentration of a reactant in a given reaction to reach a value that is the arithmetic mean of its initial and final (equilibrium) values.

Halogens-The elements in Group 17 of the Periodic Table. These elements are highly electronegative with important commercial and biochemical properties. The common halogens include chlorine, fluorine, bromine and iodine.

Hazard-1) The likelihood that injury will occur in a given situation or

setting. 2) A set of inherent properties of a substance, mixture of substances, or a process involving substances that make it capable of causing adverse effects to organisms or the environment, depending on the degree of exposure; in other words, it is a source of danger. See also risk


Hazard Class-Under DOT, the category of hazard assigned to a hazardous material in 49 CFR 173 and the 172.101 table. [49 CFR


Hazard identification-In risk assessment, the process of determining whether exposure to a chemical can cause an increased incidence of a particular adverse health effect, and whether the adverse health effect is likely to occur in humans or target populations.

Hazard index-In RCRA Correction Action, the level of exposure to one or more noncarcinogens from significant exposure pathways in a given medium below which it is unlikely for even sensitive populations to experience adverse health effects. [OSWER Directive 9355.072FS, Sept 30, 1999]

Hazard label-Under DOT, commonly a diamond-shaped label showing the hazard class information. [49 CFR 172, Subpart E]

Hazardous air pollutant (HAP)- Under the CAA, a list of 187 pollutants that cause or may cause serious health effects or adverse environmental and ecological effects. Also known as toxic air pollutants, or air toxics.

Hazardous chemicals-Under OSHA, very broadly defined as chemicals exhibiting a physical or health hazard.

Hazardous Material-Under DOT, a substance or material capable of posing an unreasonable risk to health, safety, and/or property when transported in commerce, and has been designated as hazardous. [49

CFR 171.8] The term includes hazardous substances, hazardous wastes, marine pollutants, elevated temperature materials, materials designated as hazardous in the Hazardous Materials Table (see 49 CFR 172.101), and materials that meet the defining criteria for hazard classes and divisions in 49 CFR 173.

Hazardous substance-1) Under OSHA, substances listed in 29 CFR 1910, Subpart Z; 2) under DOT, material, including its mixtures and solutions, that a) is listed in 49 CFR 172.101, Appendix A, or b) is in a quantity, in one package, which equals or exceeds the RQ in Appendix

  1. Special rules applying to mixtures and the term hazardous substancedoes not apply to petroleum products; [49 CFR 171.8] 3) underCERLCA, the list of substances in 40 CFR Table 302.4, that have assigned RQs.

Hazardous waste-Under RCRA, solid waste that meets certain hazard criteria (ignitability, corrosivity, reactivity toxicity, or are specifically listed in the regulation). [40 CFR 261]

Hazardous waste manifest-Under RCRA, a shipping manifest to be used transporting hazardous waste. [40 CFR 262.21]

Hazmat-A general term for hazardous material.

Hazmat employee-Under DOT, a person employed at any level by a hazmat employer or self-employed and who handles hazardous materials in any fashion, including loading, unloading, packaging, preparation for shipment, or vehicle transport. [49 CFR 171.8]

Health and Safety Plan (HASP)-Under HAZWOPER, an OSHA- required plan for working on a hazardous waste site. [29 CFR 1910.120]

Health hazard-1) Under the OSHA HCS, a chemical classified as posing one of the following hazardous effects: acute toxicity; skin corrosion or irritation; serious eye damage or eye irritation; respiratory

or skin sensitization; germ cell mutagenicity; carcinogenicity; reproductive toxicity; specific target organ toxicity (single or repeated exposure); or aspiration hazard.

Herbicide-Under FIFRA, an agent that kills undesirable plants and weeds.

High level radioactive waste-As defined by the NRC, the highly radioactive materials produced as a byproduct of the reactions that occur inside nuclear reactors. High-level wastes are either spent (used) reactor fuel when it is accepted for disposal or waste materials remaining after spent fuel is reprocessed.

Historical Recognized Environmental Conditions (HREC)-Under AAI, includes any past releases of any hazardous substances or petroleum products at a property that have been addressed to the satisfaction of the applicable regulatory authority so that the property meets an unrestricted use criteria. [ASTM]

Homolog-In chemistry a series of isomers that have the same number of substituted chlorines and therefore are the same weight.

Hydraulic conductivity-In groundwater modeling and treatment, a measure of the soil’s ability to transmit water when submitted to a hydraulic gradient.

Hydraulic gradient-The slope of the water table or potentiometric surface. It is the change in hydraulic head over the change in distance between the two monitoring wells or dh/dl.

Hydrocarbons (H-C)-Chemicals whose molecules contain both hydrogen and carbon atoms bonded together in a single, double or triple bond. They are often solvents and act on the brain or central nervous system.

Hydrocarbon-Compounds of hydrogen and carbon, such as any of those that are the chief components of petroleum and natural gas.

Hydrochlorofluorocarbosn (HCFCs)- Under the Montreal Protocol, compounds containing hydrogen, fluorine, chlorine, and carbon atoms that are less potent as ozone depleting substances and have been introduced as temporary replacements for CFCs, which are also greenhouse gases. See ozone depleting substance.

Hydrophilic-Water-loving tendency. See hydrophobic

Hydrophobic-The characteristic that confers insolubility in water, and is difficult to wet. See hydrophilic

Hypergolic mixture-A mixture of two highly incompatible components that spontaneously and violently ignite when the two materials mix.

Ideal gas law-An equation of state that describes the behavior of ideal gases. In simple terms, the volume of an ideal gas is proportional to the number of molecules, when the conditions of pressure and temperature are held constant; PV = nRT; where P = pressure of the gas, V = volume; n = number of moles of the gas; R = the ideal gas constant, and T = temperature.

Ignitable-Under the OSHA HCS, the characteristic of a solid, liquid, or compressed gas that indicates it is capable of being set afire. [29 CFR 1910.1200]

Ignitability-One of the properties of a characteristic waste, as defined in the RCRA regulations [40 CFR 261, Subpart C].

Immediately Dangerous to Life or Health (IDLH)-As defined by NIOSH, the maximum exposure concentration from which one could escape within 30 minutes without any escape-impairing symptoms or

any irreversible health effects.

Impoundment-Surface impoundments are very similar to landfills in that both units are a natural topographic depression, manmade excavation, or diked area formed primarily of earthen materials.

However, surface impoundments are generally used for temporary storage or treatment, whereas a landfill is an area designated for final waste disposal. [40 CFR 264/256]

Incident Command System-A management system designed to enable effective and efficient incident management by integrating a combination of facilities, equipment, personnel, procedures, and communications that operate within a common organizational structure. (FEMA)

Indirect discharges-Under the CWA, discharges that go to a POTW rather than directly into the waterbody.

Indirect effects-In an ecosystem, occur when the adverse response becomes a factor in another ecosystem component. See also direct effects.

Indirect preparation-In asbestos analysis, a method whereby a filter with too much material undergoes a separation step (commonly dispersion in water) to allow for analysis. See also direct preparation.

Industrial Hygiene (IH)-The practice and science devoted to the anticipation, recognition, evaluation, and control of health stressors (e.g. chemical, physical or biological) in the environment or workplace.

Infectious substances-See biohazard.

Ingestion-The process of swallowing matter into the gastrointestinal tract. This is the most significant route of entry when there is lack of proper personal hygiene and improper decontamination. See route of  exposure.

Inhalation-The process of breathing air, vapor, or gas and any suspended particulates into the lungs. This is the most common workplace route of entry into the body for most chemicals. See also route of exposure.

Inherent safety-The design approach of eliminating hazards and simplifying processes instead of adding more safeguards and controls.

Inhibitor-A catalyst that slows down a chemical reaction.

Injection-The process of a chemical transcending the skin by means of a cut or puncture. This is the most significant route of entry for BBPs.

Innocent landowner-Under AAI, entitles entities who have done their due diligence to have a defense against CERLCA costs.

Insect growth regulator-Under FIFRA, an agent that affects insect growth or metamorphosis.

Insecticide-Under FIFRA, an agent that kills insects.

Institutional controls-In environmental remediation, non-engineered instruments, such as administrative and legal controls, that help minimize the potential for exposure to contamination and/or protect the integrity of a response action.

Integrated contingency plan– Guidance prepared by the National Response Team intended to be used by facilities to prepare emergency response plans. The Integrated Contingency Plan provides a mechanism for consolidating multiple plans that facilities may have prepared to comply with various regulations into one functional emergency response plan. [61 FR 28642]

Integrated pest management-Under FIFRA, a sustainable approach to managing pests by combining biological, cultural, physical, and chemical tools in a way that minimizes economic, health, and environmental risks.

Intermediate bulk container (IBC)- Under DOT, a rigid or flexible portable packaging, other than a cylinder or portable tank, which is designed for mechanical handling (IB1-IB9 and IP1-IP20). [49 CFR 171.8]

Intermediate level radioactive waste-Waste that, because of its content, particularly of long lived radionuclides, requires a greater degree of containment and isolation than that provided by near surface disposal. [IAEA]

Intrinsically safe-A protection technique for safe operation of electrical equipment in flammable atmospheres.

Ionizing radiation-Wave or particle energy of sufficient strength to knock an electron out of orbit (i.e., to “ionize” it). Examples include alpha, beta, gamma, neutron, and x-ray radiation. See also radiation.

Irritant-A chemical that produces a temporary adverse reaction such as irritation, inflammation, or aggravation following immediate, prolonged, or repeated contact with skin, mucous membrane, or other biological material.

Irritating material-Under DOT, has properties similar to tear gas, which causes extreme irritation, especially in confined spaces. [49 CFR 173.132]

Isoamyl acetate-Under the OSHA Respiratory Protection Standard, the chemical name for banana oil, and one of four allowable challenge agents used for performing QLFTs. [29 CFR 1910.134]

Isomers-Compounds with the same formula but different structures and, therefore, different properties.

Isotope-An atom with the same atomic number but a different atomic mass number than another atom of the same element.

Joint and Several Liability-Liability that may be apportioned either among two or more parties or to only one or a few select members of the group, at the adversary’s discretion. Thus, each liable party is individually responsible for the entire obligation, but a paying party may have a right of contribution and indemnity from nonpaying parties. [Black’s Law Dictionary, 2009]

Judgmental sampling– In audits, using a sample size and stratification that, based on the auditor’s experience, should provide an adequate representation of current operation’s compliance with EHS regulations and company policies.

Ketone-A hydrocarbon that contains a single oxygen that is connected to the carbon chain by a double bond, forming a carbonyl group. In a ketone, the carbon atom is bonded to one or more alkyl groups.

Lab pack-Under DOT, a unique combination package for small quantities of diverse wastes of the same hazard class.

Labeling-Under DOT, labeling that only involves the display of a material’s hazard class.

Laboratory Information Management System (LIMS)-An integrated set of electronic databases which organizes, stores, and retrieves laboratory testing and quality control data, and that contains programs to perform quality assurance checks to ensure data validity.

Land disturbance-Under the CWA, the exposure of soil as a result of construction and earthwork activities such as clearing, grading, and

excavating, can greatly increase the potential for erosion and sedimentation until new vegetation becomes established.

Land use-As part of remediation technology, the management and modification of natural environment or wilderness into built environment.

Landowner Liability Protections-In accordance with AAI, the ability of a land owner to qualify for certain protections under CERCLA providing that all appropriate inquiries into the previous ownership, uses, and environmental conditions of a property have been made. [ASTM]

Latency period-The time between exposure and resulting disease.

Leachate-1) In landfills, the solution formed by rainwater that has traveled through the contents of a landfill disposal area; 2) in environmental chemistry, a solution that is prepared as described in the Toxicity Characteristic Leaching Procedure and used to identify if a waste is a regulated hazardous waste.

Life-cycle assessment-A technique for assembling process information to assess a product’s potential environmental impacts throughout its existence: has three interacting components: inventory survey; impact evaluation; and improvements.

Linear no threshold (LNT) dose response-The relationship between radiation dose and cancer occurrence.

Liquid– 1) In chemistry, a substance or mixture that is not a gas and has a melting point or initial melting point of 20° C or less at a standard pressure of 101.3 kPa; 2) under RCRA, a waste that does not pass Method 9095B (Paint Filter Liquids Test) as described in EPA Publication SW-846; [40 CFR 258.2] 3) under DOT, a material, other than an elevated temperature material, with a melting point or initial

melting point of 20 °C (68 °F) or lower at a standard pressure of 101.3 kPa (14.7 psia). A viscous material for which a specific melting point cannot be determined must be subjected to the procedures specified in ASTM D4359 [IBR, see 49 CFR 171.7].

Listed waste-Under RCRA, hazardous waste that is specifically listed as either process waste or chemical waste.

Long-term reliability and effectiveness-Under RCRA corrective action, the evaluation of a remedial alternative in protecting human health and the environment by reducing the toxicity, mobility, or volume of the pollutant. Long-term typically refers to the period after the remedial action is complete.

Low impact development (LID) – Under stormwater management, construction practices and systems designed to manage stormwater near its source, minimizing runoff, and enhancing groundwater recharge.

Low-level radioactive waste-As defined by the NRC, waste that has become contaminated with radioactive material or have become radioactive through exposure to neutron radiation, such as contaminated protective clothing, wiping rags, mops, filters, reactor water treatment residues, etc.

Lower explosive limit (LEL)-See Lower flammable limit (LFL)

Lower flammable limit (LFL) -Under the OSHA Flammable and Combustible Liquid Standard, the minimum concentration of vapor or gas in air below which flame propagation does not occur on contact with a source of ignition. Also known as the lower explosive limit (LEL) [29 CFR 1910.106]

Lowest Achievable Emission Rate (LAER)-Under the CAA, the most stringent emission limitation derived from either the most stringent emission limitation: a) contained in the implementation plan of any State

for such class or category of source; or b) achieved in practice by such class or category of source. The emissions rate may result from a combination of emissions-limiting measures such as (1) a change in the raw material processed, (2) a process modification, and (3) add-on controls.

Lowest observed adverse effect level (LOAEL)-The lowest concentration or amount of a substance (dose), found by experiment or observation, which causes an adverse effect on morphology, functional capacity, growth, development, or life span of an organism distinguishable.

Major source-Under the CAA, a stationary source of air pollution that emits or has the potential to emit 10 tons per year or more of a hazardous air pollutant or 25 tons per year or more of a combination of hazardous air pollutants.

Marking-Under DOT, placing important information on the outside of a package such as a descriptive name, identification number, instructions, cautions, weight, specification, and UN marks. [49 CFR 171.8]

Mass balance-The application of conservation of mass to the analysis of physical systems. Also called material balance.

Material Safety Data Sheet (MSDS)- See Safety Data Sheet.

Maximum Available Control Technology (MACT)-Under CAA Section 112, emission standards that require the maximum degree of reduction in hazardous air pollutant emissions from major sources.

Maximum Contaminant Level (MCL)-Under the SDWA, the highest level of a contaminant allowed to go uncorrected by a public water system. Corrective steps are implemented if the MCL is exceeded.

Median lethal concentration (LC50)- The inhaled dose that would kill 50% of the test population, expressed in terms of mass of material per volume of air (mg/m3 or ppm). Also called the median lethal concentration.

Median lethal dose (LD50)-The ingestion or absorption dose that would kill 50% of the test population, expressed in terms of mass per body weight (mg/kg). Also called the median lethal dose.

Mediation-In law, a method of alternative dispute resolution where an independent person (the mediator) helps the parties find their own solutions.

Medical surveillance-Under OSHA, a requirement for some hazardous substances that includes annual physicals, pulmonary function tests, and other tests.

Mesothelioma-A malignant tumor of the covering of the lung or the lining of the pleural and abdominal cavity often associated with asbestos exposure.

Metalloids-Elements that have intermediate properties between metals and nonmetals, also called semiconductors.

Metals-A group of elements that, in their pure state, have the five common properties of luster, malleability, ductility, and good conduction of both heat and electricity.

Miscibility-A measure of the ability of two liquids to combine. Two immiscible liquids will not combine and the resulting mixture with have two layers. Also referred to as mixability.

Mist-Under OSHA, liquid aerosol; suspended fine droplets in air. [29 CFR 1910.1200, Appendix A]

Mixed waste-Radioactive waste that is both RCRA hazardous wastes and NRC radioactive wastes.

Mixing zone-Under NPDES, an area associated with a point source discharge to water in which a calculated dilution occurs and which may provide the basis for a variance from a discharge standard.

Mixing zone analysis-Under NPDES, the process of estimating the degree of dilution achieved for a given discharge scenario, whose objective is to define the discharge dilution at the edge of the near-field mixing zone, but often far-field dilution is of interest as well.

Mobile source-Under the CAA, emissions sources that includes motor vehicles, airplanes, locomotives, and other engines.

Model-In fate and transport modeling, conceptual and mathematical description of environmental conditions.

Molarity-The ratio of moles per liter in a solution; this essentially represents the number of molecules per liter of solution.

Molar ratio-The ratio of the numbers of moles of any two compounds involved in a chemical reaction.

Mole-A specific number of molecules: 6.023 x 1023, also known as Avogadro’s number.

Molecular Weight (MW)-The sum of the atomic weights of the atoms in a molecule, expressed in grams per mole.

Monatomic-A molecule or ion that consists of a single atom.

Monomer-A molecule that can combine with other to form new compounds; a single unit polymer.

Monte Carlo method-An iterative method of analyzing data using random numbers to generate possible outcomes.

Multi-media-An activity that impacts more than one medium (air,

land, groundwater, surface water, or workplace); the term cross-media is also used.

Multi-Sector General Permit (MSGP)-An NPDES permitting program that categorically addresses industrial dischargers of stormwater.

Municipal Separate Storm Sewer System (MS4)-A public stormwater sewer system that functions independently of any sanitary sewer system.

Mutagenic substance-As defined by OSHA, a substance or agent capable of altering the genetic material in a living cell (mutation).

National Ambient Air Quality Standards (NAAQS)-Under the CAA, federal primary standards (to protect health) and secondary standards (to protect public welfare) that are set for the six criteria air pollutants.

National Contingency Plan-Also known as the National Oil and Hazardous Substances Pollution Contingency Plan, it is the federal government’s blueprint for responding to releases of oil and hazardous substances. [40 CFR 9 and 300]

National Emission Standards for Hazardous Air Pollutants (NESHAP)

-Emission standards for hazardous air pollutants published by EPA under CAA Section 112. [40 CFR 61]

National Pollutant Discharge Elimination System (NPDES)- Under the CWA, a federal permit system, with state analogues, that regulates point source discharges into waters of the United States.

National Pretreatment Program (NPP)-Under the CWA, an NPDES program that requires industries discharging to publicly owned treatment works (POTWs) to control pollutants that pass through the POTW and may interfere or contaminate sewage sludge. These industries must obtain a permit from the POTW and meet pretreatment water quality standards. [40 CFR 403]

National Response Team (NRT)-A federal team under EPA’s National Oil and Hazardous Substances Pollution Contingency Plan tasked with planning and coordinating responses to oil and hazardous materials releases, with EPA serving as the lead agency. [40 CFR 300]

Natural attenuation-The reduction of environmental contaminant concentrations through passive biological processes (aerobic and anaerobic biodegradation, plant and animal uptake), physical phenomena (advection, dispersion, dilution, diffusion, volatilization, adsorption/desorption), and chemical reactions (ion exchange, complexation, abiotic transformation). Also includes intrinsic remediation and bio-transformation.

Naturally Accelerator-Produced Radioactive Materials (NARM)- As defined by EPA, DOE, and DHS, radioactive materials not covered under the Atomic Energy Act (AEA) that are naturally occurring or produced by an accelerator. NARM waste is not covered under the AEA, not a form of Low Level Radioactive Waste, and is not regulated by NRC.

Naturally Occurring Radioactive Materials (NORM)-As defined by the EPA, DOE, and DHS radioactive materials that are found in nature. A subset of NARM, NORM wastes are concentrated from certain nonradioactive usable materials when they are extracted from the earth or, occasionally, from the water erosion of natural materials.

Navigable waters of the United States-1) Under the authority of the USACE, waters subject to the ebb and flow of the tide and/or are presently used, or have been used in the past, or may be susceptible for use to transport interstate or foreign commerce; [33 CFR 329.4] 2)

Under the CWA and DOT, the waters of the United States, including the territorial seas. [CWA, Section 502; 49 CFR 171.8]

Negative exposure assessment– Under the OSHA construction standard for asbestos, an employer’s demonstration, using objective data and monitoring, that employee exposure during an operation is expected to be consistently below the PELs. [29 CFR 1926.1101(f)(2)(iii)]

Negligence-The failure to exercise the standard of care that a reasonably prudent person would have exercised in a similar situation; any conduct that falls below the legal standard established to protect others against unreasonable risk of harm, except for conduct that is intentionally, wantonly, or willfully disregardful of others’ rights. [Black’s Law Dictionary, 2009]

Nematicide-Under FIFRA, an agent that kills nematodes.

New Source Performance Standards (NSPS)-1) Under the CWA, effluent pollutant reductions deemed achievable based on the best available demonstrated control technology, which are developed based on cost, energy requirements, and environmental impacts; [CWA. Section 106] 2) Under the CAA, technology based standards that apply to specific categories of stationary sources. [40 CFR 60]

New Source Review (NSR)-Under the CAA, part of the permitting process for stationary sources that include Prevention of Significant Deterioration (PSD) permits in attainment areas, NSR permits in nonattainment areas, and minor source permits.

No observed adverse effect level (NOAEL)-In toxicology, the greatest concentration or amount of a substance, found by experiment or observation, which causes no detectable adverse alteration of morphology, functional capacity, growth, development, or life span of the target organism under defined conditions of exposure.

Noble gases-The elements in Group 18 of the Periodic Table, that are virtually inert (unreactive), with only a few stable compounds known. The noble gases include: helium, neon, argon, krypton, xenon and radon.

Non-bulk packaging-Under DOT, a package or container that has a) a maximum capacity of less than 119 gal (450 L) for liquids b) maximum net mass of less than 882 lb (400 kg) for solids, or c) water capacity of 1,000 lb (454 kg) or less for gas. [49 CFR 171.8]

Non-PCB-Under TSCA, items with PCB concentrations below 50 ppm. [40 CFR 761.2]

Non-porous surface-Under TSCA, a smooth, unpainted solid surface that limits penetration of liquid containing PCBs beyond the immediate surface. [40 CFR 761.2]

Nonattainment Area-Under the CAA, any area that does not meet (or that contributes to another nonattainment area) the national primary or secondary ambient air quality standard for the pollutant.

Nonconventional pollutants-Under the CWA, all water quality pollutants other than conventional pollutants or toxic (priority) pollutants, including chlorine, ammonia, nitrogen, phosphorus, chemical oxygen demand, and whole effluent toxicity.

Nuclear fission-The splitting of an atomic nucleus into two smaller nuclides.

Nuclear fusion-The joining of two nuclides into one.

Nuclide-The nucleus of a specific isotope, characterized by the number of protons (atomic number) and number of neutrons.

Nuisance-A condition, activity, or situation (such as a loud noise or foul odor) that interferes with the use or enjoyment of property. [Black’s

Law Dictionary, 2009]

Octanol-water partition coefficient (Kow)- An indication of an organic compound’s solubility in water, soil/sediment adsorption, and bioconcentration factors and is defined as the ratio of the compound’s concentration in a known volume of n-octanol to its concentration in a known volume of water after the octanol and water have reached equilibrium.

On-site recycling-Under RCRA, reclaiming or reusing materials that are sources of pollution (such as using a solvent still to clean solvent for reuse). [40 CFR 261.2]

Organic peroxide-An organic compound that contains the bivalent -O- O- structure and which may be considered a structural derivative of hydrogen peroxide, where one or both of the hydrogen atoms has been replaced by an organic radical.

Organophosphate-Under FIFRA, any of a class of pesticidal cholinesterase inhibitors derived from phosphoric or thiophosphoric acid (such as Malathion and Parathion).

Outlier-In sampling and analysis, a sample result that lies outside the other values in a set of data.

Overpack-Under DOT, a type of non-bulk packaging that uses a larger container, such as a drum crate or pallet, to surround an inner container of hazardous materials. [49 CFR 171.8]

Oxidation-A change in a chemical characterized by the loss of electrons. In a literal sense, oxidation is a reaction in which a substance combines with oxygen.

Oxidation number-A hypothetic number that describes of the degree to which electrons have been removed (oxidized) from an element. The

oxidation number of an element is always zero. Elements in which electrons have been removed (oxidized) have positive oxidation number. Elements in which electrons have been added (reduced) have negative oxidation numbers.

Oxidation state-The degree to which electrons have been removed (oxidized) from an element. The oxidation state is denoted by its Oxidation number (II, III, etc.) and in nomenclature by adding suffixes to the proper name of the chemical (-ous, -ic, etc.).

Oxidizer-1) In chemistry, the compound with an atom going from a higher oxidation state to a lower one by accepting an electron from another atom or molecule; 2) under DOT, a material that may, generally by yielding oxygen, cause or enhance the combustion of other materials; [49 CFR 173.127] 3) under OSHA, a chemical other than a blasting agent or explosive that initiates or promotes combustion in other materials, thereby causing fire either of itself or through the release of oxygen or other gases.

Ozone-The triatomic form of oxygen (O3), that in the troposphere that is created by photochemical reactions, in high concentrations is harmful to a wide range of living organisms, and is a greenhouse gas. In the stratosphere, ozone is created by the interaction between solar ultraviolet radiation and molecular oxygen, offering protection at ground level from ultraviolet B radiation.

Ozone-depleting substance (ODS)- A family of man-made compounds including chlorofluorocarbons (CFCs), bromofluorocarbons (halons), methyl chloroform, carbon tetrachloride, methyl bromide, and hydrochlorofluorocarbons (HCFCs), that deplete stratospheric ozone.

Packing group-Under DOT, a grouping (I through III) assigned to each PSN that indicates the degree of hazard for the material. [49 CFR 172.101]


Particulate-1) In industrial hygiene, a generic term for solid matter suspended in air, including dusts, mists, fumes, aerosols, soot, smoke, and fibers; 2) under the CAA, one of the criteria pollutants and designated as PM25 or PM10 (particulate matter less than 2.5 and 10 microns, respectively).

Partitioning-In environmental fate and transport, a mechanism whereby when one or more phases are accessible, a molecule may move preferentially from one phase to another, such as water to air or water to soil. The rate and preferred direction of such partitioning are based on the molecule’s physical properties (such as volatility) and its relative affinity for the various media.

Pathogen-A microorganism (bacteria, virus, fungus) that causes or can cause disease.

PCB-See polychlorinated biphenyl.

PCB article-Under TSCA, any manufactured article, other than a PCB Container, that contains PCBs and whose surface(s) has been in direct contact with PCBs. [40 CFR 761.3]

PCB article container-Under TSCA, any package, can, bottle, bag, barrel, drum, tank, or other device used to contain PCB Articles or PCB Equipment, and whose surface(s) has not been in direct contact with PCBs. [40 CFR 761.3]

PCB bulk product waste-Under TSCA, waste derived from manufactured products containing PCBs in a non-liquid state, at any concentration where the concentration at the time of designation for disposal was > 50 ppm PCBs, excluding regulated electrical equipment. [40 CFR 761.3]

PCB container-Under TSCA, any package, can, bottle, bag, barrel, drum, tank, or other device that contains PCBs or PCB Articles and whose surface(s) has been in direct contact with PCBs.

PCB-contaminated-PCB concentration is between 50 ppm and 500 ppm. [40 CFR 761.3]

PCB remediation waste-Under TSCA, waste containing PCBs as the result of a spill, release, or other unauthorized disposal, including environmental media (soils, water, etc.), sewage and industrial sludge, and buildings and other manmade structures. [40 CFR 761.3]

Penetration-In industrial hygiene, the process of a chemical moving through seams, zippers, or other imperfections in protective clothing. See also permeation.


Performance Oriented Packaging– Under DOT, packaging based on performance standards developed in the form of Recommendations by the United Nations Committee of Experts on the Transport of Dangerous Goods (UN Recommendations). [49 CFR 178]

Permeation-1) In industrial hygiene, the process of a chemical moving through protective clothing at the molecular level; 2) in biology, the action of entering or passing through a cell membrane.

Permissible Exposure Limit (PEL)- Under OSHA, a legally enforceable occupational exposure limit established by OSHA, usually measured as an eight-hour TWA, but also may be expressed as a ceiling limit.

Persistent organic pollutant (POP)- In environmental science, an organic chemical that is stable in the environment, liable to long-range transport, may bioaccumulate in human and animal tissue, and have significant impacts on human health and the environment; for example, dioxin, PCBs, and DDT.

Personal protective equipment (PPE)-Under OSHA, any safety

equipment worn to minimize exposure to hazards, including safety glasses or goggles, ear plugs or muffs, respirators, face shields, hard hats, hard toe footwear and protective clothing, etc.

Pesticide-Under FIFRA, any substance or mixture of substances intended for preventing, destroying, repelling, or mitigating any pest (insect, fungus, or rodents), or intended for use as a plant regulator, defoliant, or desiccant. [40 CFR 152.3]

pH– A measure of the acid/basic character of a solution. pH is defined as the negative log of the concentration of the hydronium ion in aqueous solution. Acid solutions have pH values below 7 and basic solutions have pH values above 7.

Physical hazard-Under OSHA, a chemical that has one of the following hazardous effects: explosive; flammable; oxidizer self- reactive; pyrophoric; self-heating; organic peroxide; corrosive to metal; gas under pressure; or in contact with water emits flammable gas. [OSHA HCS]

Placard-Under DOT, a durable metal or plastic square diamond that provides three key pieces of hazard information: color; 4-digit ID number; and hazard class number and pictogram.

Pleural effusion-A build-up of fluid in the pleural cavity of the lungs; side effect of asbestos exposure.

Pleural fibrosis-The development of fibrous tissue in the pleura; side effect of asbestos exposure.

Pleural plaques-Deposits in the pleural cavity; side effect of asbestos exposure.

Point count-Under NESHAPS, a method of determining the percentage of asbestos in a material. A point count is performed by making multiple slide mounts of a uniform finely ground bulk sample and examining the slide mounts under polarized light microscopy. The number of points that contact asbestos fibers are divided by the total number of points examined. [40 CFR 61.141]

Point source-1) Under the CAA, a single emission source in a defined location; 2) under the CWA any discrete conveyance, including any pipe, ditch, channel, etc, from which pollutants are or may be discharged. This term does not include agricultural stormwater discharges and return flows from irrigated agriculture.

Poisonous gas-Under DOT, a gas that is known, or presumed, to pose a toxic inhalation hazard during transportation. [49 CFR 173.115]

Poisonous material-Under DOT, a material that is known, or presumed, to pose a toxic exposure hazard during transportation. [49 CFR 173.132]

Pollutant-Broadly defined as any undesirable solid, liquid, or gaseous matter in a solid, liquid, or gaseous environmental medium.

Pollution prevention (P2)-As defined by EPA, a preferred management practice that reduces, eliminates, or prevents pollution at its source. Also known as source reduction.

Pollution Prevention Opportunities Assessment (PPOA)-Process- specific evaluations aimed at determining the best economically feasible and efficient alternatives that can achieve objectives such as source reduction, re-use, and recycling; low-impact plant operations and treatment methods; and environmentally safe disposal, discharge, or emission, only in the absence of more sustainable alternatives.

Polychlorinated biphenyl (PCB)- 1) In organic chemistry, one of 209 molecules consisting of two joined benzene rings with one to ten attached chlorine atoms; 2) under TSCA, a family of organic chemicals once widely used due to their nonflammability, stability, and high boiling point. See also Aroclor®.

Polycyclic aromatic hydrocarbon (PAH)-See Polynuclear aromatic compound.

Polymerization-A chain reaction that joins monomers into long chain molecules.

Polynuclear aromatic compound (PNA)-A naturally occurring compound that can also be made through the combustion of fossil fuels or garbage; characterized by an aromatic fused-ring structures. Also known as a polycyclic aromatic hydrocarbon (PAH).

Porosity-In groundwater, the percentage of the fluid-filled soil or rock (the aquifer) that is void and permits fluid flow, not taking into consideration how this space is distributed.

Porous surface-Under TSCA, a surface that allows PCBs to penetrate or pass into itself. [40 CFR 761.3]

Postconsumer recycled content– The fraction of feedstock used in manufacturing derived from materials that have been used by the public, discarded, and collected for reprocessing.

Potential to emit-Under the CAA, the highest amounts of certain pollutants that a facility could release into the air (even if the pollutants have never actually been emitted at that amount), considering equipment design, operating controls, and limitations. [40 CFR 70.2]

Potentially responsible party-Under CERCLA Section 107, the liability for pollution released at a site that that causes imminent and substantial danger which extends broadly to all current and past owners, arrangers for disposal at a site, and transporters of the hazardous wastes to a site.

Powered air-purifying respirator (PAPR)-As defined by OSHA, a respirator that uses a blower to force the ambient air through air- purifying elements. [29 CFR 19.10.134(b)] See also air purifying respirator.

Precision-A data quality objective derived from replicate measurements of the same property, usually under prescribed similar conditions, generally expressed in terms of the standard deviation.

Preconsumer recycled content-The fraction of feedstock derived from wastes captured during or just after the manufacturing process, such as repulping scrap paper shaved from the ends of a paper roll to produce the next batch.

Presumed asbestos containing material-Under the OSHA asbestos standards, the rebuttable presumption that thermal system insulation and surfacing material found in buildings constructed no later than 1980 must be treated as if it contains asbestos. [29 CFR 1920.1101(b)]

Prevention of Significant Deterioration (PSD)-Under the CAA, the protection of public health and the environment in an attainment area through an analysis of air quality and other impacts, public involvement, and the installation of Best Available Control Technology. [40 CFR 52.21]

Primary National Ambient Air Quality Standard (NAAQS)-Under the CAA, NAAQS that protect public health, including sensitive populations such as asthmatics, children, and the elderly. [40 CFR 50]

Priority Pollutant-Under the CWA, 126 inorganic constituents (metals and cyanide) and manufactured organic compounds identified in the Priority Pollutant List (PPL) in 40 CFR 423, Appendix A. Also called toxic pollutants.

Private nuisance-A condition that interferes with a person’s

enjoyment of property; esp., a structure or other condition erected or put on nearby land, creating or continuing an invasion of the actor’s land and amounting to a trespass to it. [Black’s Law Dictionary, 2009]

Problem formulation-In ecological risk assessment, the preliminary scoping step that establishes a site risk assessment’s purpose, objectives, and goals. [EPA, Ecological Risk Assessment Guidance]

Process hazard analysis (PHA)- 1) Under OSHA and EPA, a formal, team-based approach that helps evaluate the risks associated with chemical process hazards, identify those procedures and equipment where the risks may not be adequately managed, and make recommendations to correct the deficiencies. [29 CFR 1910.119(e), 40 CFR 68.67]

Process safety management (PSM)- Under OSHA and EPA, applying management systems to identify, evaluate, and control process-related hazards with the goal of safe operation and maintenance of chemical processes. [29 CFR 1910.119, 40 CFR 68]

Promulgate-To put a law or action into force.

Proper shipping name (PSN)-Under DOT, the name of the hazardous material shown in Roman print (not italics) in Column 2 of the Hazardous Materials Table. [49 CFR 171.8]

Protection Factor-Under OSHA, the ratio of the concentration outside the respirator divided by the concentration inside; indicates the degree of fit of a respirator. [29 CFR 1910.134]

Public nuisance-An unreasonable interference with a right common to the general public, such as a condition dangerous to health, offensive to community moral standards, or unlawfully obstructing the public in the free use of public property. [Black’s Law Dictionary, 2009]


Publicly Owned Treatment Works (POTWs)-A sewage treatment authority, usually owned and operated as a public utility, that collects and transports wastewater from homes, commercial buildings, and industrial facilities to a treatment plan. POTWs are generally regulated under the CWA NPDES program.

Punch list-A list of items remaining to be done, including items that do not meet the quality standard and must be re-done.

Pyrophoric-Under OSHA and DOT, a gas, liquid, or solid with autoignition temperatures below or only slightly above room temperature that, even in small quantities and without an external ignition source, can ignite within five minutes after coming in contact with air [29 CFR 1910.1200 and 49 CFR 173.124(b)]

Qualitative Fit Test (QLFT)-Under OSHA RPP, a pass/fail fit test that assesses the adequacy of a respirator’s fit and seal that relies on the individual’s response to the test agent. [29 CFR 1910.134]

Quality assurance-An integrated system of activities involving planning, implementation, documentation, assessment, reporting, and quality improvement to ensure that a process, item, or service is of the expected quality.

Quality assurance project plan (QAPP)-A document that describes the necessary quality assurance, quality control, data quality objectives, and procedures that ensures that analytical results will meet the stated performance criteria, including how data and information will be acquired, stored, and manipulated.

Quality control-The set of activities that measures performance of a process, item, or service against defined standards and verifies that performance meets the stated requirements.

Quantitative Fit Test (QNFT)- Under OSHA RPP, an assessment of respirator fit by numerically measuring the amount of leakage of a contaminant (the fit factor) into the respirator. [29 CFR 1910.134]

Radiation protection program– Under the NRC, a program that uses, to the extent practical, procedures and engineering controls to achieve occupational doses and doses to members of the public that are as low as is reasonably achievable (ALARA). [10 CFR 20.1101]

Radical group-A term that refers to a connected group of atoms. In organic chemistry nomenclature, it refers to a functional group that is added to the skeleton of the hydrocarbon chain.

Radioactive-The property of an element that is emitting ionizing radiation in the form of energy or particles.

Radioactive contamination-The presence of radioactive material in an undesired location, such as on surfaces, within solids, liquids, gases, or the human body.

Radioactive decay-See decay.

Radioactive isotope-One of 500 isotopes with atomic numbers above 82 that are radioactive. Isotopes with atomic numbers greater than 92 are manmade and radioactive. Also known as a radioisotope.

Radioactive material-Under DOT, a material containing radionuclides where both the activity concentration and the total activity in the consignment exceed specified or derived values. [49 CFR 173.403]

Radioactivity– Spontaneous energy emission in the form of electromagnetic rays and/or particles from the nucleus of an unstable atom. Radioactive nuclei are said to decay or to disintegrate.

Radionuclide-See radioactive isotope.

Reactivity-1) In chemistry, the ability of a material to react with other materials or with its container; 2) under the OSHA HCS, a substance’s susceptibility to undergo a chemical reaction or change that may result in dangerous side effects, such as an explosion, burning, and corrosive or toxic emissions [29 CFR 1910.1200]; 3) under RCRA, one of the properties of a characteristic waste. [40 CFR 261, Subpart C]

Reasonably Achievable Control Technology (RACT)-Under the CAA, the lowest emission limitation that a particular source is capable of meeting by the application of control technology that is reasonably available considering technological and economic feasibility. [40 CFR 51.1010]

Reasonable maximum exposure (RME)-In toxicology, the highest exposure that is reasonably expected to occur.

Rebuttable presumption-A regulatory assumption considered to be true unless proved otherwise.

Receptor-An ecosystem, organism, or human that could be adversely affected by the release or migration of a hazardous substance.

Recognized environmental condition-Under the AAI standard, the presence, or likely presence, of a hazardous substance or petroleum product in, on, or at a property: due to any release to the environment; under conditions indicative of a release to the environment; or under conditions that pose a material threat of a future release to the environment. [ASTM E1527]

Recommended Exposure Limits (RELs)-Nonregulatory chemical exposure limit guidelines developed by NIOSH expressed as an airborne concentration over a work day time period.

Recovery-Under RCRA, processing a material to recover a usable product, regenerate it, or convert it to energy.

Recycling-The collection and reprocessing of a waste material, allowing the recycled material to replace virgin materials.

Redox reaction-A type of chemical reaction where the exchange of electrons causes one atom to go to a higher oxidation state (is oxidized) while the other atom goes to a lower oxidations state (is reduced). Also known as an oxidation-reduction reaction.

Reducer-In chemistry, the compound with the atom going from a lower oxidation state to a higher one by donating an electron to another atom or molecule.

Regulated ACM (RACM)- RACM includes all: friable asbestos- containing material (ACM); nonfriable ACM that has become friable; Category II materials that will be made friable by the proposed activity, and; Category I materials that will be subjected to specific operations (such as chipping, sawing, or burning).

Regulated substance-CERCLA hazardous substance, as listed at 40 CFR 302.4, and petroleum products.

Relative gas density-See Vapor density.

Remediation-Removal of pollution or contaminants from environmental media for the general protection of human health and the environment.

Replicate-See duplicate.

Reportable quantity (RQ)-The quantity of a hazardous substance which, if released, requires reporting to the spill response authorities under CERCLA, CWA, CAA, DOT, EPCRA, OPA, RCRA, and SARA regulations. [40 CFR Table 302.4]

Respiratory Protection Program (RPP)-Under OSHA, a required program involving workplace evaluations, fit testing, medical surveillance, and training if engineering and administrative controls fail to protect employees from breathing contaminated air. [29 CFR 1910.134]

Reuse-The use of a waste, without processing, in place of a commercial product; or reintroducing a waste back into the process as a feedstock. If the waste must be processed before reuse, it is considered recycling rather than reuse.

Risk-The probability that a substance will produce harm or result in a future financial liability.

Risk-based performance standards (RBPS)-Under CFATS, performance standards that must be included in the site security plan for a covered facility. [6 CFR 27.230]

Risk assessment-The identification and quantification of the risk resulting from a specific use or occurrence of a chemical or physical agent, taking into account possible harmful effects on individuals or populations exposed to the agent in the amount and manner proposed and all the possible routes of exposure.

Risk-based audit-A technique that uses risk analysis, management perception, or agency concern to select audit areas.

Risk characterization-The outcome of hazard identification and risk estimation when applied to a specific use of a substance or occurrence of an environmental health hazard.

Risk communication-The continual exchange of information about health and environmental risks among risk assessors, risk managers, the public, the media, interested groups, and others.

Risk management-The process of assessing and controlling risk through decisions, policy, plans, and actions by integrating the results of risk assessment and engineering studies with social, economic, and political concerns.

Risk monitoring-Following up the on risk management decisions and actions to identify if risks are being reduced and/or new risks created.

Risk register-A listing of potential risks their impacts, the potential mitigation or prevention alternatives, and person(s) responsible for monitoring the specific risk.

Route of entry-See route of exposure.

Route of exposure-The way a toxic chemical gains access to an organism through breathing (inhalation), eating or drinking (ingestion), contact with the skin (dermal absorption), or other routes.

Safe haven-Under DOT, an area specifically approved in writing by local, state, or federal government authorities for parking unattended vehicles containing Division 1.1, 1.2, or 1.3 (explosive) materials. [49 CFR 397.5]

Safe work practices-Under OSHA, a combination of management and worksite policies, plans, and procedures that, when used in combination, foster safe and healthy working conditions.

Safety Data Sheet (SDS)-Under OSHA’s HCS and the GHS, a unified presentation of information regarding the hazards of a chemical and other safety advice, usually associated with a particular preparation, substance, or process. [29 CFR 1910.1200]

Salvage packaging-Under DOT, a plastic or metal removable head drum, compatible with and capable of containing a leaking container that can be shipped for repacking or disposal. [49 CFR 173.3]

Sampling-The process of obtaining a representative portion of the material of concern.

Saturated hydrocarbon-An organic compound that contains the maximum number of hydrogens possible and characterized by carbon atoms connected by single bonds.

Screening Threshold Quantity– Under CFATS, the threshold amount of a Chemical of Interest that requires a facility to register online with DHS, and subsequently complete and submit a Top-Screen. [6 CFR 27, Appendix A]

Secondary National Ambient Air Quality Standard-Under the CAA, NAAQS that provide public welfare protection, including protection against decreased visibility and damage to animals, crops, vegetation, and buildings. [40 CFR 50]

Security Vulnerability Analysis (SVA)-Under CFATS, a systematic characterization of the site assets and specific materials, the potential threat events and attack scenarios (e.g. theft) that could potentially compromise the materials, and existing in-place security measures to address those threats. [6 CFR 27]

Segregation-The separation of hazardous materials during storage and transportation to prevent contact and reactions between incompatible materials.

Self-Contained Breathing Apparatus (SCBA)-Under OSHA RPP, an atmosphere-supplying respirator for which the breathing air source is designed to be carried by the user. [29 CFR 1910.134]

Sensitizer-A chemical that causes a person to be hypersensitive when exposed to that agent, thereby causing an allergic-like reaction from subsequent exposures.

Sharps-Under the OSHA BBP, objects that can penetrate the skin including needles, scalpels, broken glass, broken capillary tubes, and exposed ends of dental wires. [29 CFR 1910.1030(b)]

Shelter-in-place-As defined by DHS, a method of protection from a hazardous materials release that involves taking refuge in a small interior room with no or few windows, closing and locking windows and doors, turning off ventilation systems, closing fireplace dampers, and remaining in place until the emergency is over.

Shipper-Under DOT, a person who prepares or offers a hazardous material for shipment. [49 CFR 172, Subpart C]

Short-term effectiveness-During RCRA corrective action, the evaluation of remedial alternative effectiveness in protecting human health and the environment by reducing the pollutant’s toxicity, mobility, or volume. [CERCLA, Section 121]

Short-Term Exposure Limit (STEL)- In industrial hygiene, 15-minute chemical exposure limits set by the ACGIH® that should not be exceeded at any time during a workday.

Significant Industrial User (SIU)- Under the CWA NDPES, an industry that discharges to a POTW and is subject to the National Pretreatment Program based on a reasonable potential to adversely affect the POTW operations. [40 CFR 403]

Simple Asphyxiant-Under the OSHA Hazard Communication rule, a substance or mixture that displaces oxygen in the ambient atmosphere, and can thus cause oxygen deprivation in those who are exposed, leading to unconsciousness and death. [29 CFR 1910.1200]

Site Security Plan-Under CFATS, a plan that addresses the risks identified by a facility as a result of the Security Vulnerability Assessment. [6 CFR 27]

Skin Absorption-Chemical transport from the outer skin surface into both the skin and the body. Also known as dermal absorption.

Solid waste-As defined by EPA, any garbage, refuse, or sludge from a wastewater treatment plant, water supply treatment plant, or air pollution control facility, and other discarded material but does not include solid or dissolved materials in domestic sewage, or solid or dissolved materials in irrigation return flows or industrial discharges that are point sources subject to permit under 33 U.S.C. 1342, or source, special nuclear, or by-product material as defined by the Atomic Energy Act of 1954, as amended. [68 Stat. 923] [40 CFR 258.2]

Solubility-A substance’s ability to dissolve into a solvent at a specific temperature.

Solute-The lesser component of a solution, consisting of the dissolved material contained within a solvent.

Solution-In chemistry, a homogeneous mixture (or homogeneous phase) in which gases, liquids, or solids are uniformly distributed in one phase of a solvent.

Solvent-The most abundant component of a solution and the component that holds the dissolved materials, or solutes.

Source reduction-See pollution prevention.

Special provisions-Under DOT, codes in the Hazardous Materials Table that specify packaging provisions, prohibitions, and exceptions from DOT’s HMR. [49 CFR 172.101, 49 CFR 172.102]

Specific target organ toxins (STOT)- Under the OSHA HCS, chemicals that cause damage to body systems and to specific organs following a single exposure [29 CFR 1910.1200, Appendix A.8]

Spiked sample-In chemical analysis, the artificial addition of a known analyte concentration to a sample to determine the level of recovery, instrument detection performance, or bias.

Spill prevention, control and countermeasure plan (SPCC)-Under the CWA, a plan intended to prevent the discharge of oil to navigable waters or shorelines that is required of facilities with total aggregate aboveground storage capacity greater than 1,320 gallons of oil. [40 CFR 112]

Standard atmospheric pressure-A reference pressure exerted by the Earths’ atmosphere, commonly expressed as 760 mmHg or 14.696 psi.

Standard deviation-The measure of the variability of the samples around the mean, often represented by the Greek letter sigma (cr).

Standard Operating Procedure (SOP)- An officially approved written document that details the step-by-step method for an operation, analysis, or action for performing certain routine or repetitive tasks.

Standard temperature and pressure (STP)-The common reference condition of 1 atmosphere and 25° C, although other sets of reference conditions exist.

Standards-In chemistry, materials of known concentrations and properties used to calibrate instruments, determine method precision and bias, and instrument response (detection) for specific chemical analytes.

Stationary source-Under the CAA, a pollutant source that does not move, such as power plants, gas stations, incinerators, and houses.

Statistical sampling-Techniques used to determine the specific number of test subjects and the specific subjects to be tested so the sample population is representative of the entire population.

Steady state-A situation where the overall system condition remains the same over time, even though one or more individual parameters may be changing.

Stochastic modeling-A method of estimating ecosystem fate and transport by modeling the random perturbations of the system that arise out of chance and therefore obey the laws of probability.

Storage-Under RCRA, holding waste (in containers, tanks, containment buildings, drip pads, waste piles, or surface impoundments) for a temporary time period prior to the waste being treated, disposed, or stored elsewhere. [40 CFR 264]

Stormwater Pollution Prevention Plan (SWPPP)-Under the CWA, a written document, prescribed as part of a stormwater NPDES discharge permit, that describes the industrial activities at the site, as well as the facility procedures and structural control practices used to prevent pollutants reaching stormwater. [40 CFR 122]

Stratospheric ozone-depleting substances-See ozone-depleting substances.

Strict liability-Liability that does not depend on actual negligence or intent to harm, but that is based on the breach of an absolute duty to make something safe. Strict liability most often applies either to ultrahazardous activities or in products-liability cases. [Black’s Law Dictionary, 2009]

Strong acid-An acid that ionizes completely when added to water, releasing a hydrogen ion. Examples of strong acids include perchloric acid, sulfuric acid, hydrobromic acid, hydrochloric acid, and nitric acid.

Strong base-A base that ionizes completely when added to water, releasing a hydroxide ion. Examples of strong bases include sodium hydroxide, and potassium hydroxide.

Sublimation-In chemistry, the process of changing state from solid to gas.

Substantial harm criteria-Under EPA, criteria used to determine if an oil handling facility must submit a facility response plan due to risk of substantial harm to the environment as a result of oil discharge to navigable waters or adjoining shorelines. [40 CFR 112, Appendix C]

Supplemental environmental project (SEP)-An EPA policy that allows an alleged violator to voluntarily undertake an environmentally beneficial project in exchange for a reduced penalty.

Supplied-Air Respirator (SAR)- Under OSHA’s RPP, an atmosphere- supplying respirator for which the source of breathing air is not designed to be carried by the user. [29 CFR 1910.134]

Synergistic effect-In toxicology, a chemical interaction in which the combined effect of exposure to two or more toxic materials is different than exposure to any one of the materials individually.

Taking-Under the ESA, harassing, harming, pursuing, hunting, shooting, wounding, killing, trapping, capturing or collecting, or attempting to engage in any such conduct with regard to a protected species.

Target housing-Under HUD, housing covered under the lead-based paint rule, generally defined as housing constructed prior to 1978. [35 CFR 35.86]

Target organ-The organ or organ system affected by a given chemical.

Target organ toxin-See Specific target organ toxins.

Technical impracticality-Under RCRA Corrective Action, a determination that site restoration may not be achievable due to the

limitations of the treatment technology.

Technical name-Under DOT, a recognized chemical or microbiological name that is currently used in scientific and technical handbooks, journals, and texts. [49 CFR 171.8]

Technology enhanced naturally occurring radioactive material (TENORM)-Material produced when radionuclides that occur naturally in ore, soils, or water are concentrated or exposed to the environment by activities such as uranium mining and sewage treatment.

Teratogen-A substance that causes malformations of a fetus or birth defects.

Thermal conductivity-The ability of a material to transfer thermal energy; the rate at which heat flows through a material.

Thermal decomposition-The breakdown of a substance due to the application of heat or through combustion.

Threshold Limit Value (TLV)-An airborne exposure limit set by the ACGIH that represents a concentration to which it is believed that workers can be exposed continuously for a short period of time without suffering from irritation, chronic or irreversible tissue damage, or narcosis. See also ceiling value, short-term exposure limit, and time- weighted average.

Time Weighted Average (TWA)-The concentration of a material to which a person is exposed, averaged over the total exposure time, generally the total workday. (8 to 12 hours).

Title V Operating Permit-A permit program established under CAAA Title V, that consolidated all air pollution control requirements into a single, comprehensive operating permit intended to cover all aspects of a source’s year-to-year air pollution activities.

Tolerances-Under the FIFRA, the maximum amounts of pesticide residue that may remain on food. [40 CFR 180]

Tort– A civil wrong, other than breach of contract, for which a remedy may be obtained, usually in the form of damages; a breach of a duty that the law imposes on persons who stand in a particular relation to one another. [Black’s Law Dictionary, 2009]

Total maximum daily load (TMDL)- Under the CWA, the maximum quantity of a pollutant that a particular water body can receive from all sources including point and nonpoint sources, without exceeding the applicable water quality standard. [40 CFR 130]

Total Suspended Solids (TSS)-A water quality parameter that indicates the dry weight of solid material suspended (filterable) in a water sample.

Toxic pollutants-See priority pollutants.

Toxic tort-A civil wrong arising from exposure to a toxic substance, that can be remedied by a civil lawsuit or by administrative action. [Black’s Law Dictionary, 2009]

Toxicity-1) in toxicology, the measure of incompatibility of a substance with life; 2) in biology, the adverse effects of a substance on a living organism; 3) under the OSHA HCS, a relative property of a chemical agent that refers to a harmful effect on some biological mechanism and the conditions under which this effect occurs; 4) under RCRA, one of the properties of a characteristic waste. [40 CFR 261, Subpart C]

Toxicity assessment-The relationship between chemical dose received and the occurrence of adverse health effects in the exposed population; provides toxicity values for use in estimating risk.

Toxicity Equivalency Factor (TEF)- The ratio of the toxicity of a chemical to that of another structurally related chemical (or index compound) chosen as a reference.

Toxicity reference values (TRVs)- Species-specific and chemical- specific estimates of an exposure level that is not likely to cause unacceptable adverse effects on growth, reproduction, or survival; expressed as dose-based for ingestion pathways, concentration-based for direct contact in media, or tissue-based for a receptor.

Toxicology-The study of actual or potential danger presented by a substance’s harmful effects on living organisms and ecosystems

Tragedy of the commons-A metaphor for the global challenges associated with managing shared resources. [Garrett Hardin 1968]

Transaction screen-In brownfields investigations, a tool used to provide a preliminary non-invasive overview of a commercial property, to determine if any environmental issues are present and whether further environmental investigation is necessary.

Transition metals– the elements in Groups 3 – 12 of the Periodic Table, which are generally regulated due to their toxic impact on the environment and potential to disrupt biochemical processes in plant and animal tissues, such as chromium, copper, zinc, cadmium and mercury.

Transuranic radioactive waste (TRU)-Under the AEA, radioactive waste containing man-made elements above atomic number 92.

Treatment, Storage, and Disposal Facility-Under RCRA, a facility permitted to treat, store, and dispose of hazardous waste. [40 CFR 264 and 265]

TSCA nonlisted material-A material that is not on the US TSCA inventory.

Universal precautions-Under OSHA’s BPP, an approach to infection control that treats all human blood and certain human body fluids as if they were known to be infectious for HIV, HBV, and other bloodborne pathogens. [29 CFR 1910.1030(b)]

Underground Injection Control (UIC)-Under the SDWA, a regulatory process that manages the placement of fluids underground for storage, disposal, or other purposes, with the goal of protecting groundwater quality. [40 CFR 144]

Universal wastes-Under RCRA, a special category of hazardous waste that includes batteries, pesticides, and mercury-containing thermostats and lamps. [40 CFR 273]

Unreasonable adverse effects on the environment-Under FIFRA, 1) any unreasonable risk to man or the environment, taking into account the economic, social, and environmental costs and benefits of the use of any pesticide, or 2) a human dietary risk from residues that result from a use of a pesticide in or on any food inconsistent with the standard under FFDCA Section 408.

Upper Explosive Limit (UEL)-See Upper Flammable Limit.

Upper Flammable Limit-Under OSHA, the maximum proportion of vapor in air above which propagation of flame does not occur. Also known as the Upper Explosive Limit (UEL). [29 CFR 1910.106]

Vadose zone-In hydrogeology, the unsaturated zone, or the part of Earth between the land surface and the top of the phreatic zone i.e. the position at which the groundwater (the water in the soil’s pores) is at atmospheric pressure.

Valence electron-An electron that occupies the outermost orbitals of an atom and is available for bonding.

Vapor-Under OSHA, the gaseous portion of a chemical that is normally a liquid. [29 CFR 1910.1200, Appendix A]

Vapor density-The ratio of a gas’s molar mass (MMx) and the molar mass of dry air (MMair = 29.0). Also called relative gas density.

Vapor pressure-1) In chemistry, the pressure of a gas above the condensed phase at a particular temperature in a closed container. 2) Under OSHA, the pressure exerted by a volatile liquid as determined by a prescribed test. [29 CFR 1910.106]

Vector-In biology, an animal capable of carrying and transmitting a disease agent.

Vermiculite-A chemically inert, lightweight, fire resistant, and odorless magnesium silicate material that is generally used for its thermal and sound insulation in construction and for its absorbent properties in horticultural applications. A major source of vermiculite is the mine in Libby, Montana, which has been demonstrated to contain various amounts of amphibole minerals.

Virgin material-Feedstock that has not been used previously for manufacturing purposes.

Volatile organic compounds-Any organic compound having, at 293.15 K, a vapor pressure of 0.01 kPa or more or having a corresponding volatility under the particular condition of use.

Volatilization-The relative rate of evaporation, or releasing of vapors above a liquid or solid.

Waste (or materials) exchange-A service that attempts to connect a company seeking to sell or give away a waste with a company seeking materials to replace virgin materials or other materials in the manufacturing process.

Waste Load Allocation (WLA)- Under the CWA, the portion of a receiving water’s overall pollutant loading capacity (TMDL) that is allocated to one of its point source discharges. [40 CFR 130]

Waste minimization-The reduction, to the extent feasible, of hazardous waste that is generated or subsequently treated, stored, or disposed, including source reduction or recycling that reduces the total volume or toxicity of the hazardous waste generated, as long as it is consistent with the goal of minimizing present or future threats to human health and the environment.

Waste stream-Production of used or spent materials that are collected and managed for the purpose of disposal or recycling.

Water quality criteria-Under the CWA, maximum numeric or narrative values that describe the desired water quality condition to be achieved or maintained.

Water Quality Volume (WQV)- Under the CWA, and defined variously by stormwater management programs, a site-specific volume of stormwater that represents the first flush of runoff from a site during a precipitation event.

Waters of the United States-See Navigable waters of the United States.

Weak acid-An acid that partially dissociates in water, releasing a hydrogen ion, such as carbonic acid, hydrosulfuric acid, hydrocyanic acid, acetic acid, and phosphoric acid.

Weak base-A base that partially dissociates in water, increasing the hydroxide ion concentration, such as carbonic acid, sodium carbonate, sodium bicarbonate, calcium carbonate, sodium sulfide, sodium cyanide, potassium acetate, calcium hydroxide, and aqueous ammonia.

Whole-Effluent Toxicity-Under the NPDES program, a laboratory test that evaluates the aggregate toxic effect on aquatic organisms of all pollutants contained in a wastewater effluent sample. [40 CFR 136.3]

Wipe sample-In asbestos sampling, using a moist wipe over a specified area using a template. The settled dust that is picked up is analyzed to estimate of the number of fibers per area.

Workplace Environmental Exposure Level (WEEL)-In industrial hygiene, occupational exposure limits (OELs) developed to protect healthy workers from acute and chronic health effects; normally based on repeated workplace exposures over a working lifetime. [TERA- OARS]

Worst-case release scenario-Under EPA’s Risk Management Program, a release scenario that represents a hypothetical worst-case dispersion of toxic chemicals, or optimal vapor cloud formation and explosion of flammable chemicals. [40 CFR 68.25]

X-ray-A form of ionizing radiation similar to gamma rays but originating from outside the atom’s nucleus.