POPs Toolkit Glossary


Absorbed DoseIn exposure assessment, the amount of a substance that penetrates an exposed organism's absorption barriers (e.g. skin, lung tissue, gastrointestinal tract) through physical or biological processes.
AbsorptionThe uptake of water, other fluids, or dissolved chemicals by a cell or an organism (as tree roots absorb dissolved nutrients in soil.)
Acceptable riskProbability of suffering disease or injury which is considered to be sufficiently small to be "negligible" (tolerable risk).
Accepted riskProbability of suffering disease or injury which is accepted by an individual.
Accidental exposureUnintended contact with a substance or change in the physical environment (including for example radiation) resulting from an accident
AccumulationSuccessive additions of a substance to a target organism, or organ, or to part of the environment, resulting in an increasing amount or concentration of the substance in the organism, organ, or environment.
AcuteShort-term, in relation to exposure or effect (as opposite to “chronic”. In clinical medicine, sudden and severe, having a rapid onset..
Acute effectEffect of short duration and occurring rapidly (usually in the first 24 h or up to 14 d) following a single dose or short exposure to a substance or radiation
Acute toxicityAbility of a substance to cause adverse effects within a short time of dosing or exposure (opposite to chronic toxicity).
Adverse effectChange in morphology, physiology, growth, development or lifespan of an organism which results in impairment of functional capacity or impairment of capacity to compensate for additional stress or increase in susceptibility to the harmful effects of other environmental influences.
Adverse Health EffectA change in morphology, physiology, growth, development or life span of an organism, which results in impairment of functional capacity or which increases susceptibility to the harmful effects of other environmental influences.
Age sensitivityQuantitative and qualitative age dependence of an effect .
AmbientSurrounding (applied to environmental media such as air, water, sediment or soil)
Ambient monitoringContinuous or repeated measurement of agents in the environment to evaluate ambient exposure and health risk by comparison with appropriate reference values based on knowledge of the probable relationship between exposure and resultant adverse health effects
AnalysisThe systematic application of specific theories and methods, including those from natural science, statistics, probability theory, social science, engineering, decision science, logic, mathematics, and law, for the purpose of collecting and interpreting data and drawing conclusions about phenomena.
Analytical ResultReport of data obtained from analysis, observation, or measurement.
AssayProcess of quantitative or qualitative analysis of a component of a sample or results of a quantitative or qualitative analysis of a component of a sample.
ATSDRAgency for Toxic Substances and Disease Registry.


Background SamplesSamples that are collected and used to compare site conditions to the surrounding environment. Background samples are collected and handled in the same manner as all other samples.
Baseline ReviewStep 1 of an overall Risk Management Decision-Making Process. Its objective is to develop a detailed situation analysis/needs assessment within which the actual or potential problem posed by the chemical substance in the country can be identified; including an evaluation of risks to health and/or the environment. The suggested output is a refined situation and problem statement.
BCRBenefit Cost Ratio – the ratio of the Present Value of the Benefit to the Present Value of the Cost. BCR is a measure of relative feasibility. If BCR >1, the project is viable
Benefit TransferA practice used to estimate economic values for ecosystem services by transferring information available from studies already completed in one location or context to another. This can be done as a unit value transfer or a function transfer.
BioaccumulantsSubstances that increase in concentration in living organisms as they take in contaminated air, water, or food because the substances are very slowly metabolized or excreted
BioaccumulationProgressive increase in the amount of a substance in an organism or part of an organism which occurs because the rate of intake exceeds the organism's ability to remove the substance from the body.
Bioaccumulation potentialAbility of living organisms to concentrate a substance obtained either directly from the environment or indirectly through its food.
BioassayProcedure for estimating the concentration or biological activity of a substance (vitamin, hormone, plant growth factor, antibiotic etc.) by measuring its effect on an organism compared to an appropriate standard preparation.
BioavailabilityDegree of ability to be absorbed and ready to interact in organism metabolism.
BioconcentrationThe accumulation of a chemical in tissues of a fish or other organism to levels greater than in the surrounding medium.
BiodegradableCapable of decomposing under natural conditions.
BiomagnificationRefers to the process whereby certain substances such as pesticides or heavy metals move up the food chain, work their way into rivers or lakes, and are eaten by aquatic organisms such as fish, which in turn are eaten by large birds, animals or humans. The substances become concentrated in tissues or internal organs as they move up the chain.
BlankA sample subjected to the usual analytical or measurement process to establish a zero baseline or background value. Sometimes used to adjust or correct routine analytical results. A sample that is intended to contain none of the analytes of interest. A blank is used to detect contamination during sample handling preparation and/or analysis.
Blind SamplesA quality assurance sample in which the laboratory performing the analysis is unaware of the sample’s true location this sample is collected a duplicate.


Calibration1) A comparison of a measurement standard, instrument, or item with a standard or instrument of higher accuracy to detect and quantify inaccuracies and to report or eliminate those inaccuracies by adjustments. 2) Process of adjusting an instrument’s read out so that it corresponds to actual concentrations. It involves checking the instrument with a known concentration of a surrogate to insure that the instrument provides a proper response.
CappingThe covering of contaminated material (usually soil or sediments) with a layer of clean material (e.g., clean soils or sediments, asphalt or concrete). Capping of contaminated material reduces the probability of exposure to humans or animals.
CarcinogenAny substance that can cause or aggravate cancer.
CAS Registration NumberA number assigned by the Chemical Abstract Service to identify a chemical.
Case StudyA brief fact sheet providing risk, cost, and performance information on alternative methods and other pollution prevention ideas, compliance initiatives, voluntary efforts, etc.
CCMECanadian Council of Ministers of the Environment.
Chain of custodyA method and record used for documenting the history and sequential possession of a sample from the time of collection or generation through analysis and data reporting. This term is also used in controlled sequence of responsibility for a substance from the manufacturer to the distributor, to the user, or to the person(s) ultimately responsible for waste disposal.
Chlorinated Hydrocarbons1. Chemicals containing only chlorine, carbon, and hydrogen. These include a class of persistent, broad-spectrum insecticides that linger in the environment and accumulate in the food chain. Among them are DDT, aldrin, dieldrin, heptachlor, chlordane, lindane, endrin, Mirex, hexachloride, and toxaphene. Other examples include TCE, used as an industrial solvent. 2. Any chlorinated organic compounds including chlorinated solvents such as dichloromethane, trichloromethylene, chloroform.
Chronic EffectAn adverse effect on a human or animal in which symptoms recur frequently or develop slowly over a long period of time.
Chronic ExposureMultiple exposures occurring over an extended period of time or over a significant fraction of an animal's or human's lifetime (Usually seven years to a lifetime.)
Chronic ToxicityThe capacity of a substance to cause long-term poisonous health effects in humans, animals, fish, and other organisms.
CIDACanadian International Development Agency.
CommercialRefers to lands used for light industry, trade and business (e.g., markets, stores, offices etc.).
Comparability A measure of the confidence with which one data set or method can be compared to another.
Composite SampleA non-discrete sample composed of more than one specific aliquot collected at various sampling points or times.
Conservative assessment of riskAssessment of risk which assumes the worst possible case scenario and therefore gives the highest possible value for risk: risk management decisions based on this value will maximize safety.
ContaminantsAny physical, chemical, biological, or radiological substance or matter that has an adverse effect on air, water, or soil, and detrimental to human health.
ContaminationIntroduction into water, air, and soil of microorganisms, chemicals, toxic substances, wastes, or wastewater in a concentration that makes the medium unfit for its next intended use. Also applies to surfaces of objects, buildings, and various household and agricultural use products.
COPC (Contaminant of potential concern)Specific chemicals that are identified for evaluation in a risk assessment problem formulation.
Critical end-pointToxic effect used by the USEPA as the basis for a reference dose (Term used for an estimate (with uncertainty spanning perhaps an order of magnitude) of a daily exposure to the human population (including sensitive subgroups) that is likely to be without appreciable risk of deleterious effects during a lifetime)
Critical period (of development)Stage of development of an organism that is of particular importance in the life cycle if the normal full development of some anatomical, physiological, metabolic, or psychological structure or function is to be attained: such a period may be associated with very high susceptibility to specific potentially toxic substances..
CSF (Cancer Slope Factor)Factor multiplied to the calculated dose to estimate the incremental lifetime cancer risk. A US EPA term, similar to the Canadian slope factor for carcinogenic potency (SF).
Cultural ConsiderationsWays in which traditions, values, practices and other characteristics of groups within society may affect or be affected by health risks and approaches to risk management.
Culture of RiskSpecific values and norms that are shared by people and groups in an organization and that control the way they uphold need to make risk awareness part of the day-to-day frameworks of understanding and practice applied by policy makers.


Data Quality Objectives (DQOs)Qualitative and quantitative statements of the overall level of uncertainty that a decision-maker will accept in results or decisions based on environmental data. They provide the statistical framework for planning and managing environmental data operations consistent with user's needs.
DDTThe first chlorinated hydrocarbon insecticide chemical name: Dichloro-Diphenyl-Trichloroethane. It has a half-life of 15 years and can collect in fatty tissues of certain animals. EPA banned registration and interstate sale of DDT for virtually all but emergency uses in the United States in 1972 because of its persistence in the environment and accumulation in the food chain.
Decision-Making FrameworkA structured process for making risk management decisions. The process consists of three phases: issue identification, risk assessment, and risk management (identification and analysis of options, selection of a strategy, implementation of the strategy, and monitoring and evaluation of the strategy).
DecompositionThe breakdown of matter by bacteria and fungi, changing the chemical makeup and physical appearance of materials.
DecontaminationProcess of rendering harmless (by neutralization, elimination, removal etc.) a potentially toxic substance in the natural environment, laboratory areas, the workplace, other indoor areas, clothes, food, water, sewage etc.
DeficiencyAn unauthorized deviation from acceptable procedures or practices, or a defect in an item.
DermalPertaining to the skin.
Dermal Absorption/PenetrationProcess by which a chemical penetrates the skin and enters the body as an internal dose.
Dermal ExposureContact between a chemical and the skin.
Dermal irritationSkin reaction resulting from a single or multiple exposure to a physical or chemical entity at the same site, characterized by the presence of inflammation; it may result in cell death.
Dermal ToxicityThe ability of a pesticide or toxic chemical to poison people or animals by contact with the skin.
DesignThe specifications, drawings, design criteria, and performance requirements. Also, the result of deliberate planning, analysis, mathematical manipulations, and design processes.
Design changeAny revision or alteration of the technical requirements defined by approved and issued design output documents and by approved and issued changes thereto.
Detection LimitThe lowest concentration of a chemical that can reliably be distinguished from a zero concentration.
Determinants of HealthThe collective label given to the factors and conditions that are thought to have an influence on health, including things such as income and social status, social support networks, education, employment and working conditions, social and physical environments, personal health practices, and coping skills. Some determinants play a more prominent role than others for given health issues, and interact in complex ways to affect population health.
DioxinAny of a family of compounds known chemically as dibenzo-p-dioxins. Concern about them arises from their potential toxicity as contaminants in commercial products. Tests on laboratory animals indicate that it is one of the more toxic anthropogenic (man-made) compounds.
Direct RunoffWater that flows over the ground surface or through the ground directly into streams, rivers, and lakes.
Disability Adjusted Life Year (DALY)A health gap measure that extends the concept of potential years of life lost due to premature death (PYLL) to include equivalent years of ‘healthy’ life lost by virtue of being in states of poor health or disability. The DALY combines in one measure the time lived with disability and the time lost due to premature mortality.
DocumentAny written or pictorial information describing, defining, specifying, reporting, or certifying activities, requirements, procedures, or results.
Dose EquivalentThe product of the absorbed dose from ionizing radiation and such factors as account for biological differences due to the type of radiation and its distribution in the body in the body.
Dose ResponseShifts in toxicological responses of an individual (such as alterations in severity) or populations (such as alterations in incidence) that are related to changes in the dose of any given substance.
Dose Response CurveA graph of the relationship between the dose of a contaminant and the biological response.
Dose-Response Assessment1. Estimating the potency of a chemical. 2. In exposure assessment, the process of determining the relationship between the dose of a stressor and a specific biological response. 3. Evaluating the quantitative relationship between dose and toxicological responses.
Dose-Response RelationshipThe quantitative relationship between the amount of exposure to a substance and the extent of toxic injury or disease produced.
Duplicate samples Two samples taken from and representative of the same population and carried through all steps of the sampling and analytical procedures in an identical manner. Duplicate samples are used to assess variance of the total method, including sampling and analysis
DustFine particulate matter which is easily suspended in air and can be inhaled.
DWQGDrinking water quality guidelines.


Ecological Risk AssessmentThe application of a formal framework, analytical process, or model to estimate the effects of human actions(s) on a natural resource and to interpret the significance of those effects in light of the uncertainties identified in each component of the assessment process. Such analysis includes initial hazard identification, exposure and dose-response assessments, and risk characterization.
EcologyThe relationship of living things to one another and their environment, or the study of such relationships.
EcosystemThe interacting system of a biological community and its non-living environmental surroundings.
EDLÉlectricité du Laos.
Elasticity of Demand, PriceThe price elasticity in demand is defined as the percentage change in quantity demanded divided by the percentage change in price. Since the demand curve is normally downward sloping, the price elasticity of demand is usually a negative number … Minus one is usually taken as a critical cut-off point with lower values (that is less than one) being inelastic and higher values (that is greater than one) being elastic. If demand is inelastic a price increase will increase total revenues while if demand is elastic, a price increase will decrease revenues.
Emission and exposure controlTechnical and administrative procedures and specifications applied for the monitoring, reduction or elimination of emissions from a source or exposure to a target.
EnvironmentThe sum of all external conditions affecting the life, development and survival of an organism.
Environmental AssessmentAn environmental analysis prepared pursuant to the National Environmental Policy Act to determine whether a federal action would significantly affect the environment and thus require a more detailed environmental impact statement.
Environmental data Any parameters or pieces of information collected or produced from measurements, analyses, or models of environmental processes, conditions, and effects of pollutants on human health and the environment, including results from laboratory analyses or from experimental systems representing such processes and conditions.
Environmental FateThe destiny of a chemical or biological pollutant after release into the environment.
Environmental Fate DataData that characterize a pesticide's fate in the ecosystem, considering factors that foster its degradation (light, water, microbes), pathways and resultant products.
Environmental monitoring The process of measuring or collecting environmental data.
Environmental SamplesSamples of naturally occurring matrices such as soil, sediment, ground water, surface water and air.
Environmental Site AssessmentThe process of determining whether contamination is present on a parcel of real property.
Environmental/Ecological RiskThe potential for adverse effects on living organisms associated with pollution of the environment by effluents, emissions, wastes, or accidental chemical releases; energy use; or the depletion of natural resources.
EPAUnited States Environmental Protection Agency.
Estimated exposure concentration (EEC)Measured or calculated amount or mass concentration of a substance to which an organism is likely to be exposed, considering exposure by all sources and routes.
Estimated exposure dose (EED)Measured or calculated dose of a substance to which an organism is likely to be exposed, considering exposure by all sources and routes.
Ethical ConsiderationsFactors related to the multiple values and principles that may be of concern in decisions regarding risks to health.
EvaluationA systematic and objective assessment of the design, implementation and outcome of an on-going or completed intervention. The two main purposes of evaluation are i) to improve future aid policy and interventions through feedback of lessons learned, and ii) to provide a basis for accountability, including the provision of information to the public.
ExposureThe amount of radiation or pollutant present in a given environment that represents a potential health threat to living organisms.
Exposure AssessmentIdentifying the pathways by which toxicants may reach individuals, estimating how much of a chemical an individual is likely to be exposed to, and estimating the number likely to be exposed.
Exposure PathwayThe path from sources of pollutants via, soil, water, or food to man and other species or settings.
Exposure RouteThe way a chemical or pollutant enters an organism after contact; i.e. by ingestion, inhalation, or dermal absorption.
Exposure scenarioA set of facts assumptions, and inferences about how exposure takes place that aids the exposure assessor in evaluating, estimating, or quantifying exposures.
Exposure-Response RelationshipThe relationship between exposure level and the incidence of adverse effects.


FAOFood and Agriculture Organization of the United Nations.
Fate and Exposure ModelingThe scientific process used to predict where chemicals "end up" after being released into the environment. For example: a chemical may be emitted into the air, but most of it might end up in groundwater, because of the chemical's particular physical properties.
FertilityAbility to conceive and to produce offspring: for litter- bearing species the number of offspring per litter is used as a measure of fertility. Reduced fertility is sometimes referred to as sub-fertility.
Fertility toxicantProduces abnormalities of male or female reproductive functions or impairs reproductive capacity.
Field (matrix) spikeA sample prepared at the sampling point (i.e., in the field) by adding a known mass of the target analyte to a specified amount of the sample. Field matrix spikes are used, for example, to determine the effect of the sample preservation, shipment, storage, and preparation on analyte recovery efficiency (the analytical bias).
Field blankA QA/QC sample used to indicate potential contamination from ambient air and sampling instruments. A blank used to provide information about contaminants that may be introduced during sample collection, storage, and transport. A clean sample, carried to the sampling site, exposed to sampling conditions, returned to the laboratory, and treated as an environmental sample.
Field split samplesTwo or more representative portions taken from the same sample and submitted for analysis to different laboratories to estimate inter-laboratory precision.
File Work Instructions (WFIs)A file plan lists the records in your office, and describes how they are organized and maintained.
Food ChainA sequence of organisms, each of which uses the next, lower member of the sequence as a food source.
Food webNetwork of food chains - The feeding relationships by which energy and nutrients are transferred from one species to another.


GenotoxicDamaging to DNA; pertaining to agents known to damage DNA.
GNI/capitaGross National Income per capita - The dollar value of a country's final output of goods and services in a year (its GNP), divided by its population. It reflects the average income of a country's citizens. Knowing a country's GNP per capita is a good first step toward understanding the country's economic strengths and needs. Since 2001, the World Bank refers to the GNP per capita as the GNI per capita, gross national income per capita.
Ground WaterThe supply of fresh water found beneath the Earth's surface, usually in aquifers, which supply wells and springs. Because ground water is a major source of drinking water, there is growing concern over contamination from leaching agricultural or industrial pollutants or leaking underground storage tanks.
Ground-Water DischargeGround water entering near coastal waters which has been contaminated by landfill leachate, deep well injection of hazardous wastes, septic tanks, etc.


HabitatThe place where a population (e.g. human, animal, plant, microorganism) lives and its surroundings, both living and non-living.
Half-Life1. The time required for a pollutant to lose one-half of its original concentration, for example, the biochemical half-life of DDT in the environment is 15 years. 2. The time required for the elimination of half a total dose from the body.
HalogenA type of incandescent lamp with higher energy-efficiency that standard ones.
Handling TimeAll trip blanks, field blanks, and environmental sample containers must be received in the field within one day of preparation in the lab. They may be held on site for a maximum of two calendar days. They must then be shipped to the lab at the end of the field sampling. All samples and blanks must be maintained at 4øC while on site and during shipment.
Harmful occupational factorComponent of the work environment the effect of which on a worker under certain conditions leads to ill health or reduction of working ability.
Harmful occupational factorComponent of the work environment the effect of which on a worker under certain conditions leads to ill health or reduction of working ability.
Harmful substanceSubstance that, following contact with an organism can cause ill health or adverse effects either at the time of exposure or later in the life of the present and future generations.
Harmful substanceSubstance that, following contact with an organism can cause ill health or adverse effects either at the time of exposure or later in the life of the present and future generations.
Hazard1. Potential for radiation, a chemical or other pollutant to cause human illness or injury. 2. In the pesticide program, the inherent toxicity of a compound. Hazard identification of a given substances is an informed judgment based on verifiable toxicity data from animal models or human studies.
Hazard AssessmentEvaluating the effects of a stressor or determining a margin of safety for an organism by comparing the concentration which causes toxic effects with an estimate of exposure to the organism.
Hazard Communication StandardAn OSHA regulation that requires chemical manufacturers, suppliers, and importers to assess the hazards of the chemicals that they make, supply, or import, and to inform employers, customers, and workers of these hazards through MSDS information.
Hazard EvaluationA component of risk evaluation that involves gathering and evaluating data on the types of health injuries or diseases that may be produced by a chemical and on the conditions of exposure under which such health effects are produced.
Hazard IdentificationDetermining if a chemical or a microbe can cause adverse health effects in humans and what those effects might be.
Hazard QuotientThe ratio of estimated site-specific exposure to a single chemical from a site over a specified period to the estimated daily exposure level, at which no adverse health effects are likely to occur.
Hazard RatioA term used to compare an animal's daily dietary intake of a pesticide to its LD 50 value. A ratio greater than 1.0 indicates that the animal is likely to consume a dose amount which would kill 50 percent of animals of the same species.
Hazardous ChemicalAn EPA designation for any hazardous material requiring an MSDS under OSHA's Hazard Communication Standard. Such substances are capable of producing fires and explosions or adverse health effects like cancer and dermatitis. Hazardous chemicals are distinct from hazardous waste.
Hazardous Substance1. Any material that poses a threat to human health and/or the environment. Typical hazardous substances are toxic, corrosive, ignitable, explosive, or chemically reactive. 2. Any substance designated by EPA to be reported if a designated quantity of the substance is spilled in the waters of the United States or is otherwise released into the environment.
Hazardous WasteBy-products of society that can pose a substantial or potential hazard to human health or the environment when improperly managed. Possesses at least one of four characteristics (ignitability, corrosivity, reactivity, or toxicity), or appears on special EPA lists.
HealthState of complete physical, mental and social well-being, and not merely the absence of disease or infirmity (WHO, 1978b), or state characterized by anatomical, physiological and psychological integrity, ability to perform personally valued family, work and community roles; ability to deal with physical, biological, psychological and social stress; a feeling of wellbeing; and freedom from the risk of disease and untimely death (Last, 1988).
Health MonitoringThe repetitive and continued observation, measurement and evaluation of an activity, output or outcome to detect changes in human health or the environment over a period of time.
Health Risk CommunicationRisk communication includes all exchanges among interested parties (individuals, social groups, industry, and governments) about health and environmental concerns. Any interested party may initiate activities in this area. Engaging in such activities brings with it some corresponding responsibilities for all parties. However, it is industry and governments, which have an explicit duty to engage in good risk communication practices in a timely fashion. This duty derives from their associated responsibility to manage risks in the public interest. The ultimate goal of risk communication is to assist stakeholders (public, private or community) in understanding the rationale behind a risk-based decision, so that they may arrive at a balanced judgement that reflects the factual evidence about the matter at hand, in relation to their own interests and values.
HI (Hazard Index)The sum of more than one hazard quotient for multiple substances and/or multiple exposure pathways. The HI is calculated separately for chronic, sub chronic and acute exposures.
Holding timeThe period of time a sample may be stored prior to its required analysis. While exceeding the holding time does not necessarily negate the veracity of analytical results, it causes the qualifying or “flagging” of any data not meeting all of the specified acceptance criteria.
HomogenizationProcess whereby a sample is mixed in a stainless steel bowl or in-situ until a consistent physical appearance is achieved. This is performed for all parameters except volatiles.
HQ (Hazard Quotient)The ratio of the exposure estimate to an effects concentration considered to represent a "safe" environmental concentration or dose. In Canada HQ<0.2 represent negligible risks to humans
Human Health RiskThe likelihood that a given exposure or series of exposures may have damaged or will damage the health of individuals.
Human Health Risk Assessment (HHRA)A process intended to estimate the level of risk associated with agents (chemicals) in the human environment to provide guidance on whether the attendant risks are acceptable for the intended use HHRAs may be carried out on the basis of literature toxicity and exposure data or may utilize site-specific exposure data. In each case the steps in the process are hazard identification, hazard characterization (sometimes termed dose-response assessment), exposure assessment and risk characterization.
Hydraulic ConductivityThe rate at which water can move through a permeable medium (i.e. the coefficient of permeability).
Hydrocarbons (HC)Chemical compounds that consist entirely of carbon and hydrogen


ILCR (Incremental Lifetime Cancer Risk)The increased potential of acquiring cancer during a life time, as a result of chemical exposure. In Canada, cancer risks are considered negligible where the estimated ILCR is < 1-in-100,000 (<1x10-5).
In SituIn its original place; unmoved unexcavated; remaining at the site or in the subsurface.
IndustrialRefers to lands used for heavy industry (i.e., manufacturing, fuel refinement, heavy equipment repair or storage etc).
Infiltration RateThe quantity of water that can enter the soil in a specified time interval.
Information Programs and Other Government InitiativesGovernment sponsored programs or initiatives for reducing risk through better information, or improved communication, or incentive or certification programs or series of environmental management standards, or labeling of product.
Inhalable ParticlesAll dust capable of entering the human respiratory tract.
Inhalation exposureChemical exposure via breathing in vapors or small particles.
Inorganic ChemicalsChemical substances of mineral origin, not of basically carbon structure.
InsecticideA pesticide compound specifically used to kill or prevent the growth of insects.
Internal Rate of Return (IRR)Internal Rate of Return (IRR) is the discount rate that generates a zero net present value for a series of future cash flows. IRR is the rate of return that makes the sum of present value of future cash flows and the final market value of a project (or an investment) equal its current market value. IRR provides a simple ‘hurdle rate’, whereby any project should be avoided if the cost of capital exceeds this rate.
IRIS (Integrated Risk Information System)A risk assessment reference website hosted by the US EPA: http://cfpub.epa.gov/ncea/iris/ .




Laboratory split samples Two or more representative portions taken from the same sample and analyzed by different laboratories to estimate the inter-laboratory precision or variability and the data comparability.
Latent periodDelay between exposure to a disease-causing agent and the appearance of manifestations of the disease: also defined as the period from disease initiation to disease detection.
Lethal Concentration 50Also referred to as LC50, a concentration of a pollutant or effluent at which 50 percent of the test organisms die; a common measure of acute toxicity.
Lethal Dose 50Also referred to as LD50, the dose of a toxicant that will kill 50 percent of test organisms within a designated period of time; the lower the LD 50, the more toxic the compound.
Limit of quantitationThe minimum concentration of an analyte or category of analytes in a specific matrix that can be identified and quantified above the method detection limit and within specified limits of precision and bias during routine analytical operating conditions.
Lipid SolubilityThe maximum concentration of a chemical that will dissolve in fatty substances. Lipid soluble substances are insoluble in water. They will very selectively disperse through the environment via uptake in living tissue.
Local Standard TimeThe time used in the geographic location of the sample site that is set to standard time. Standard time is used to match continuous instruments to filter-based instruments.
Long-Term Outcomes (of risk management)Changes in the original conditions that resulted from the risk management activities on a long run.


Management OptionsMeasures, or instruments, for achieving risk reduction and, in most cases, there will be more than one way to achieve a particular risk reduction goal. The instruments/tools range from the regulatory to the voluntary. A key requirement for governments is to assess the extent to which different management options are likely to achieve risk reduction in a way that is efficient (integrated and coordinated), technically competent, accountable and transparent.
Material Safety Data Sheet (MSDS)Compilation of information required under the Hazard Communication Standard on the identity of hazardous substances, health and physical hazards, exposure limits, and precautions.
Material Safety Data Sheet (MSDS)Compilation of information required under the Hazard Communication Standard on the identity of hazardous substances, health and physical hazards, exposure limits, and precautions.
MethodA body of procedures and techniques for performing an activity (e.g., sampling, chemical analysis, quantification), systematically presented in the order in which they are to be executed.
Monitoring (Activities)Continuous assessment of the intervention and its environment with regard to the planned objectives, results, activities and means. Monitoring identifies actual or potential successes or failures as early as possible and facilitates timely adjustments to the operations. It takes place at all levels of management and uses both formal reporting and informal communications.
MorbiditySickness, illness and "morbid condition". Morbidity could be measured in terms of three units: i) Proportion of persons who were ill; ii) The illnesses (periods or spells of illnesses) that these persons experienced; and iii) The duration (days, weeks, etc.) of these illnesses.
Morbidity rateTerm used loosely to refer to incidence or prevalence rates of disease.
MortalityDeath as studied in a given population or subpopulation. The word mortality is often used incorrectly instead of mortality rate.
Mutagen/MutagenicityAn agent that causes a permanent genetic change in a cell other than that which occurs during normal growth. Mutagenicity is the capacity of a chemical or physical agent to cause such permanent changes.


Net Present Value (NPV)Valuation method to value stocks of natural resources. It is obtained discounting future flows of economic benefits to the present period.
Non-CarcinogenAn agent that does not cause cancer. Also see: Threshold Substance.
Non-Genotoxic CarcinogenAn agent that causes cancer but does not damage DNA.
Non-occupational exposureEnvironmental exposure outside the workplace to substances that are otherwise associated with particular work environments and/or activities and processes that occur there.


Occupational exposureExperience of substances, intensities of radiation etc. or other conditions while at work.
Occupational Exposure Limit (OEL)Regulatory level of exposure to substances, intensities of radiation etc. or other conditions, specified appropriately in relevant government legislation or related codes of practice.
Occupational Exposure Standard (OES)Level of exposure to substances, intensities of radiation etc. or other conditions considered to represent specified good practice and a realistic criterion for the control of exposure by appropriate plant design, engineering controls, and, if necessary, the addition and use of personal protective clothing.
Occupational hygieneIdentification, assessment and control of physicochemical and biological factors in the workplace that may affect the health or well-being of those at work and in the surrounding community.
OECDOrganization for Economic Cooperation and Development.
Off-site transfersChemicals/contaminants that are moved off the grounds of the facility, including transfers of waste sent to other facilities or other locations, such as hazardous waste treatment facilities, municipal sewage treatment or landfills, or by wind or run-off.
On-siteWithin the boundaries of the facility, including areas where contaminants may be stored, treated or disposed of that are separate from the production processes but still within the boundaries of the reporting facility.
Oral exposureChemical exposure via ingesting contaminated food or water.


Para-occupational exposureExposure of a worker's family to substances carried from the workplace to the home, and/or exposure of visitors to substances in the workplace.
ParameterA quantity, usually unknown, such as a mean or a standard deviation characterizing a population. Commonly misused for “variable,” “characteristic,” or “property.”
Particulates1. Fine liquid or solid particles such as dust, smoke, mist, fumes, or smog, found in air or emissions. 2. Very small solids suspended in water; they can vary in size, shape, density and electrical charge and can be gathered together by coagulation and flocculation.
Partition CoefficientMeasure of the sorption phenomenon, whereby a pesticide is divided between the soil and water phase; also referred to as adsorption partition coefficient.
Parts Per Billion (ppb)/Parts Per Million (ppm)Units commonly used to express contamination ratios, as in establishing the maximum permissible amount of a contaminant in water, land, or air.
PathwayThe physical course a chemical or pollutant takes from its source to the exposed organism.
PCDDPolychlorinated dibenzo-dioxin.
PCDFPolychlorinated dibenzo-furan.
PermeabilityThe rate at which liquids pass through soil or other materials in a specified direction.
PersistenceRefers to the length of time a compound stays in the environment, once introduced. A compound may persist for less than a second or indefinitely.
Persistent PesticidesPesticides that do not break down chemically or break down very slowly and remain in the environment after a growing season.
Policy making styleApproach that prescribes aspects concerning selection rules, interpretative frames, different action plans for dealing with evidence, and others in policy making. E.g. the adversarial policy making style is characterized by an open forum in which different actors compete for social and political influence in the respective policy arena.
PollutantGenerally, any substance introduced into the environment that adversely affects the usefulness of a resource or the health of humans, animals, or ecosystems.
Polluter Pays PrincipleThe principle first adopted by the OECD in 1972 and later adopted by other organizations, according to which the polluter should bear the costs of
PollutionGenerally, the presence of a substance in the environment that because of its chemical composition or quantity prevents the functioning of natural processes and produces undesirable environmental and health effects. Under the Clean Water Act, for example, the term has been defined as the man-made or man-induced alteration of the physical, biological, chemical, and radiological integrity of water and other media.
pollution prevention and control measures.
Polychlorinated Biphenyls (PCBs)A group of toxic, persistent chemicals used in electrical transformers and capacitors for insulating purposes, and in gas pipeline systems as lubricant. The sale and new use of these chemicals, also known as PCBs, were banned by law in 1979.
POPsPersistent Organic Pollutants.
PorosityDegree to which soil, gravel, sediment, or rock is permeated with pores or cavities through which water or air can move.
Potable WaterWater that is safe for drinking and cooking.
PQRAPreliminary Quantitative risk Assessment.
Present Value (PV)The discounted sum of all future debt service at a given rate of interest.
PublicA term that refers to the range of parties that may be interested in or affected by risk management decisions. It includes the general public, consumers, and special interest groups such as environmental, health and consumer groups, industry, scientists and professional associations.
Public participationA range of activities and relationships related to the interactions between the public and the decision-making body in the risk assessment and risk management process. This includes two-way communications, public education, public consultation and dialogue, advisory boards, partnerships, and joint decision-making.
Purchasing Power Parity (PPP)Purchasing power parities (PPPs) are the rates of currency conversion that equalise the purchasing power of different currencies by eliminating the differences in price levels between countries. In their simplest form, PPPs are simply price relatives which show the ratio of the prices in national currencies of the same good or service in different countries.


Quality The totality of features and characteristics of a product or service that bears on its ability to meet the stated or implied needs and expectations of the user.
Quality Assurance (QA)An integrated system of management activities involving planning, implementation, assessment, reporting, and quality improvement to ensure that a process, item, or service is of the type and quality needed and expected by the client.
Quality Control (QC)The overall system of technical activities that measures the attributes and performance of a process, item, or service against defined standards to verify that they meet the stated requirements established by the customer; operational techniques and activities that are used to fulfill requirements for quality. The system of activities and checks used to ensure that measurement systems are maintained within prescribed limits, providing protection against “out of control” conditions and ensuring the results are of acceptable quality.
Quality control (QC) sampleAn uncontaminated sample matrix spiked with known amounts of analytes from a source independent of the calibration standards. Generally used to establish intra-laboratory or analyst-specific precision and bias or to assess the performance of all or a portion of the measurement system.
Quality improvementA management program for improving the quality of operations. Such management programs generally entail a formal mechanism for encouraging worker recommendations with timely management evaluation and feedback or implementation.
Quality managementThat aspect of the overall management system of the organization that determines and implements the quality policy. Quality management includes strategic planning, allocation of resources, and other systematic activities (e.g., planning, implementation, and assessment) pertaining to the quality system.
Quality Management Plan (QMP)A formal document that describes the quality system in terms of the organization’s structure, the functional responsibilities of management and staff, the lines of authority, and the required interfaces for those planning, implementing, and assessing all activities conducted.
Quality systemA structured and documented management system describing the policies, objectives, principles, organizational authority, responsibilities, accountability, and implementation plan of an organization for ensuring quality in its work processes, products (items), and services. The quality system provides the framework for planning, implementing, and assessing work performed by the organization and for carrying out required quality assurance (QA) and quality control (QC).


RAF (Relative Absorption Factor)A variable in exposure equations which accounts for the proportion of chemical absorbed by an organism.
RAIS (Risk Assessment Information System)A risk assessment reference website hosted by the Oak Ridge National Laboratories in the United States: http://rais.ornl.gov/.
RBC (Risk Based Concentrations)Numerical guidelines for soil, drinking water, air and fish compiled by the US EPA Region III. The purpose of the RBCs are as a site screening tool. The RBCs were calculated from human TRVs (called reference doses and cancer slope factors by the US EPA).
Reference Dose (RfD)The RfD is a numerical estimate of a daily oral exposure to the human population, including sensitive subgroups such as children that are not likely to cause harmful effects during a lifetime. RfDs are generally used for health effects that are thought to have a threshold or low dose limit for producing effects.
Remedial Action (RA)The actual construction or implementation phase of a Superfund site cleanup that follows remedial design.
Remedial DesignA phase of remedial action that follows the remedial investigation/feasibility study and includes development of engineering drawings and specifications for a site cleanup.
Remediation1. Cleanup or other methods used to remove or contain a toxic spill or hazardous materials from a Superfund site; 2. for the Asbestos Hazard Emergency Response program, abatement methods including evaluation, repair, enclosure, encapsulation, or removal of greater than 3 linear feet or square feet of asbestos-containing materials from a building.
Repeatability(1) A measure of the ability of repeat the same sampling at the same location to monitor or verify the result under the same measurement conditions or (2) The degree of agreement between independent test results produced by the same analyst, using the same test method and equipment on random aliquots of the same sample within a short time period.
RepresentativenessA measure of the degree to which data accurately and precisely represent a characteristic of a population, a parameter variation at a sampling point, a process condition, or an environmental condition.
Reproductive ToxicityAdverse effects on the male and/or female reproductive systems caused by exposure to a toxic chemical. Reproductive toxicity may be expressed as alterations in sexual behavior, decreases in fertility or fetal loss during pregnancy. Some official definitions of reproductive toxicity, for example in California's Proposition 65, include developmental toxicity as part of reproductive toxicity
ResidentialRefers to lands used for housing.
Respiratory ToxicityAdverse effects on the structure or function of the respiratory system caused by exposure to a toxic chemical. Respiratory toxicants can produce a variety of acute and chronic pulmonary conditions, including local irritation, bronchitis, pulmonary edema, emphysema and cancer.
Responsibility Assignment Matrix (RAM)A table that relates the program/ project organization structure to the work breakdown structure to ensure that each element of the program/project’s scope of work is assigned to a responsible organization or individual.
RiskA measure of the probability that damage to life, health, property, and/or the environment will occur as a result of a given hazard. For health risk, it is a measure of both the harm to human health that results from being exposed to a hazardous agent, together with the likelihood that the harm will occur. In order for a health risk to exist, three things must be true: there must be exposure to a hazard; there must be a health effect (via exposure pathway and route); and there must be some likelihood (probability) that the health effect will occur.
Risk (Adverse) for Endangered SpeciesRisk to aquatic species if anticipated pesticide residue levels equal one-fifth of LD10 or one-tenth of LC50; risk to terrestrial species if anticipated pesticide residue levels equal one-fifth of LC10 or one-tenth of LC50.
Risk AssessmentQualitative and quantitative evaluation of the risk posed to human health and/or the environment by the actual or potential presence and/or use of specific pollutants.
Risk Assessment Management ProcessGlobal term for the whole process from hazard identification to risk management (See Risk Governance Framework).
Risk CharacterizationThe last phase of the risk assessment process that estimates the potential for adverse health or ecological effects to occur from exposure to a stressor and evaluates the uncertainty involved.
Risk CommunicationInterpretation and exchange of information about health or environmental risks in terms that are comprehensible among risk assessors and managers, and to the policy-makers and general public, news media, interest groups, etc without specialist knowledge (see also Health Risk communication). Effective risk communication involves determining the types of information that interested and affected parties need and want, and presenting this information to them in a useful and meaningful way.
Risk EstimateA description of the probability that organisms exposed to a specific dose of a chemical or other pollutant will develop an adverse response, e.g., cancer.
Risk FactorSomething that can increase the likelihood that adverse health effects will occur following exposure to an agent. Examples of risk factors include characteristics (e.g., race, sex, age, obesity) or behavior/variables (e.g., smoking, occupational exposure level) associated with increased probability of a toxic effect.
Risk for Non-Endangered SpeciesRisk to species if anticipated pesticide residue levels are equal to or greater than LC50.
Risk Governance FrameworkThe concept of risk governance comprises a broad picture of risk: not only does it include what has been termed risk ‘pre-assessment’, ‘appraisal’, and ‘management’, and characterization’ and ‘evaluation’ of risk, it also looks at how risk-related decision-making unfolds when a range of actors is involved, requiring co-ordination and possibly reconciliation between a profusion of roles, perspectives, goals and activities. Indeed, the limited problem-solving capacities of individual actors call for coordinated effort amongst a variety of players beyond the frontiers of countries, sectors, hierarchical levels, disciplines and risk fields. Finally, risk governance also illuminates a risk’s context by taking account of such factors as the historical and legal background, guiding principles, value systems and perceptions as well as organizational imperatives.
Risk ManagementDecision-making process involving considerations of political, social, economic, and engineering factors with relevant risk assessments relating to a potential hazard so as to develop, analyze, and compare regulatory options and to select the optimal regulatory response for safety from that hazard. Essentially risk management is the combination of three steps: risk evaluation; emission and exposure control; risk monitoring.
Risk Management GoalA set of aims and clearly defined steps to achieve intended results or outcomes of Risk Management.
Risk PerceptionThe way that individuals intuitively see and judge risks. Risk perception is influenced by many factors including age, gender, level of education, region of residence, values, social, cultural and ethical factors, and previous exposure to information on the hazard.
Risk Reduction strategyOne or more courses of action (options), intended to prevent or reduce a specific risk. A variety of different types of strategies may be used, ranging from a simple approach involving a single risk management option, to a multi-faceted approach in which a number of different options are implemented to varying degrees.
Route of ExposureThe avenue by which a chemical comes into contact with an organism, e.g., inhalation, ingestion, dermal contact, injection.
Run-OffThat part of precipitation, snow melt, or irrigation water that runs off the land into streams or other surface-water. It can carry pollutants from the air and land into receiving waters.


SampleOne or more items taken from a population (biota or non-biota) or a process and intended to provide information on the population or process.
SamplingProcedure used to obtain or constitute a sample.
Scientific methodThe principles and processes regarded as necessary for scientific investigation, including rules for concept or hypothesis formulation, conduct of experiments, and validation of hypotheses by analysis of observations.
ScreeningCarrying out of a test or tests, examination(s) or procedure(s) in order to expose undetected abnormalities, unrecognized (incipient) diseases, or defects: examples Pharmacological or toxicological screening consists of a specified set of procedures to which a series of compounds is subjected to characterize pharmacological and toxicological properties and to establish dose-effect and dose-response relationships.
Screening Risk AssessmentA risk assessment performed with few data and many assumptions to identify exposures that should be evaluated more carefully for potential risk.
SedimentTopsoil, sand, and minerals washed from the land into water, usually after rain or snow melt.
SedimentsSoil, sand, and minerals washed from land into water, usually after rain. They pile up in reservoirs, rivers and harbors, destroying fish and wildlife habitat, and clouding the water so that sunlight cannot reach aquatic plants. Careless farming, mining, and building activities will expose sediment materials, allowing them to wash off the land after rainfall.
SeepagePercolation of water through the soil from unlined canals, ditches, laterals, watercourses, or water storage facilities.
Sensitivity analysisA “what-if” type of analysis to determine the sensitivity of the outcomes to changes in parameters. If a small change in a parameter results in relatively large changes in the outcomes, the outcomes are said to be sensitive to that parameter.
SF (Slope Factor for carcinogenic potency)Factor multiplied to the calculated dose to estimate the incremental lifetime cancer risk. Usually separate SF factors are provided for oral and inhalation. A Canadian term, similar to the US EPA Cancer Slope Factor (CSF).
Short-Term Outcomes (of risk management)The impacts on those groups who are immediately affected by risk management strategies, including changes in service levels and behavior.
SiltSedimentary materials composed of fine or intermediate-sized mineral particles.
SinkPlace in the environment where a compound or material collects.
SiteAn area or place within the jurisdiction of the EPA and/or a state.
Site Assessment ProgramA means of evaluating hazardous waste sites through preliminary assessments and site inspections to develop a Hazard Ranking System score.
Site InspectionThe collection of information from a Superfund site to determine the extent and severity of hazards posed by the site. It follows and is more extensive than a preliminary assessment. The purpose is to gather information necessary to score the site, using the Hazard Ranking System, and to determine if it presents an immediate threat requiring prompt removal.
Site Safety PlanA crucial element in all removal actions, it includes information on equipment being used, precautions to be taken, and steps to take in the event of an on-site emergency.
SoilThe unconsolidated mineral and organic matter on the surface of the earth that has been subjected to and influenced by geologic and other environmental factors.
Soil TextureA measure of the percentages of various particles size groups in a volume of soil, typically sand, silt and clay.
SolubilityThe amount of mass of a compound that will dissolve in a unit volume of solution. Aqueous Solubility is the maximum concentration of a chemical that will dissolve in pure water at a reference temperature.
SorptionThe action of soaking up or attracting substances; process used in many pollution control systems.
Species1. A reproductively isolated aggregate of interbreeding organisms having common attributes and usually designated by a common name.2. An organism belonging to belonging to such a category.
SpringGround water seeping out of the earth where the water table intersects the ground surface.
SSRASite-specific risk assessment
Stabilization PondsA body of water, usually a pond, used to convert the active organic matter in sludge into inert, harmless material.
StandardThat which is established as a measure or model to which others of a similar nature should conform, or technical specification, usually in the form of a document available to the public, drawn up with the consensus or general approval of all interests affected by it, based on the consolidated results of science, technology and experience, aimed at the promotion of optimum community benefits and approved by a body recognized on the national, regional or international level.
Standard Operating Procedure (SOP) A written document that details the method for an operation, analysis, or action with thoroughly prescribed techniques and steps and that is officially approved as the method for performing certain routine or repetitive tasks.
StandardizationEstablishment of precisely defined characteristics, or precisely defined methods, for future reference, or definition of precise procedures for administering, scoring and evaluating the results of a new method that is under development.
StandardsNorms that impose limits on the amount of pollutants or emissions produced. EPA establishes minimum standards, but states are allowed to be stricter.
Stockholm Convention on Persistent Organic PollutantsInternational treaty to protect human health and the environment from persistent organic pollutants (POPs). It requires the reduction of persistent, bioaccumulating chemicals with adverse health/environmental effects. Governments implementing the Convention are required to take measures to eliminate or reduce the release of POPs into the environment and to consider these characteristics when assessing chemicals.
Sub chronic exposureMultiple or continuous exposures lasting for approximately ten percent of an experimental species lifetime, usually over a three-month period.
Sub-chronicOf intermediate duration, usually used to describe studies or periods of exposure lasting between 5 and 90 days.
Substitution Principlethat generally a hazardous substance or process should be replaced by a less hazardous substance or process where possible. Governments applying this principle often provide incentives to stimulate chemical users to continually substitute chemicals with less hazardous alternatives or non-chemical approaches.
Surface runoffPrecipitation, snow melt, or irrigation water in excess of what can infiltrate the soil surface and be stored in small surface depressions; a major transporter of non-point source pollutants in rivers, streams, and lakes.
Surface waterAny water on the surface of land (i.e., not groundwater).


TaintingRefers to food items tasting strange; possibly due to chemical contamination.
TDI (Tolerable Daily Intake)the maximum daily dose of a non-carcinogenic chemical which will usually not result in a human health impact (Canadian, similar to the US EPA, RfD).
TeratogenA substance capable of causing birth defects.
TeratogenesisThe introduction of nonhereditary birth defects in a developing fetus by exogenous factors such as physical or chemical agents acting in the womb to interfere with normal embryonic development.
Threshold1) The lowest dose of a chemical at which a specified measurable effect is observed and below which it is not observed; 2) The dose or exposure level below which a significant adverse effect is not expected.
Threshold LevelTime-weighted average pollutant concentration values, exposure beyond which is likely to adversely affect human health.
Threshold Limit Value (TLV)The concentration of an airborne substance to which an average person can be repeatedly exposed without adverse effects. TLVs may be expressed in three ways: (1) TLV-TWA--Time weighted average, based on an allowable exposure averaged over a normal 8-hour workday or 40-hour work- week; (2) TLV-STEL--Short-term exposure limit or maximum concentration for a brief specified period of time, depending on a specific chemical (TWA must still be met); and (3) TLV-C--Ceiling Exposure Limit or maximum exposure concentration not to be exceeded under any circumstances (TWA must still be met).
Thropic LevelsA functional classification of species that is based on feeding relationships (e.g. generally aquatic and terrestrial green plants comprise the first thropic level, and herbivores comprise the second).
TissueParts of a human being or animal. Tissues can include blood, liver, muscle or eggs, or can consist of a whole organism, e.g., whole snail or crab.
TopographyThe physical features of a surface area including relative elevations and the position of natural and man-made (anthropogenic) features.
Total Petroleum Hydrocarbons (TPH)Measure of the concentration or mass of petroleum hydrocarbon constituents present in a given amount of soil or water. The word "total" is a misnomer-few, if any, of the procedures for quantifying hydrocarbons can measure all of them in a given sample. Volatile ones are usually lost in the process and not quantified and non-petroleum hydrocarbons sometimes appear in the analysis.
ToxicantA harmful substance or agent that may injure an exposed organism.
ToxicityThe degree to which a substance or mixture of substances can harm humans or animals. Acute toxicity involves harmful effects in an organism through a single or short-term exposure. Chronic toxicity is the ability of a substance or mixture of substances to cause harmful effects over an extended period, usually upon repeated or continuous exposure sometimes lasting for the entire life of the exposed organism. Sub chronic toxicity is the ability of the substance to cause effects for more than one year but less than the lifetime of the exposed organism.
Toxicity AssessmentCharacterization of the toxicological properties and effects of a chemical, with special emphasis on establishment of dose-response characteristics.
Toxicity equivalency factor (TEF)Factor used in risk assessment to estimate the toxicity of a complex mixture, most commonly a mixture of chlorinated dibenzo-p-dioxins, furans and biphenyls: in this case, TEF is based on relative toxicity to 2,3,7,8 -tetrachlorodibenzo-p-dioxin (TEF = 1).
Toxicity equivalent (TEQ)Contribution of a specified component (or components) to the toxicity of a mixture of related substances.
Toxicity TestingBiological testing (usually with an invertebrate, fish, or small mammal) to determine the adverse effects of a compound or effluent.
Toxicological ProfileAn examination, summary, and interpretation of a hazardous substance to determine levels of exposure and associated health effects.
Traceability(1) The ability to trace the history, application, or location of an entity by means of recorded identifications. In a calibration sense, traceability relates measuring equipment to national or international standards, primary standards, basic physical constants or properties, or reference materials. In a data collection sense, it relates calculations and data generated throughout the project back to the requirements for the quality of the project. (2) The property of the result of a measurement or the value of a standard whereby it can be related to stated references, usually national or international standards, through an unbroken chain of comparisons, all having stated uncertainties. Many quality assurance programs demand traceability of standards to a national standard. In most cases this can be achieved through a standard traceable to the National Institute of Standards and Technology (NIST).
Trip blankA QA/QC sample whose purpose is to place a mechanism of control on sample bottle preparation, blank water quality and sample handling. A clean sample of a matrix that is taken to the sampling site and transported to the laboratory for analysis without having been exposed to sampling procedures.
TRV (Toxicological Reference Value)the maximum daily dose of either a carcinogen or non-carcinogenic chemical which will usually not result in a human health impact (Canadian).


U.S. EPAUnited States Environmental Protection Agency.
UncertaintyA deficiency in knowledge concerning parameter values and the appropriate extrapolation of the significance of adverse health effects, to a situation involving different species and exposure conditions. Uncertainty can result from lack of knowledge, inherent variability (stochasticity), confounding effects, or imprecise measurements. Also see: Safety Factor.
Uncertainty FactorOne of several factors used in calculating the reference dose from experimental data. UFs are intended to account for (1) the variation in sensitivity among humans; (2) the uncertainty in extrapolating animal data to humans; (3) the uncertainty in extrapolating data obtained in a study that covers less than the full life of the exposed animal or human; and (4) the uncertainty in using LOAEL data rather than NOAEL data.
Unconfined AquiferAn aquifer containing water that is not under pressure; the water level in a well is the same as the water table outside the well.
Upper Detection LimitThe largest concentration that an instrument can reliably detect.
UXOUnexploded Ordinance.


ValidationConfirmation by examination and provision of objective evidence that the particular requirements for a specific intended use have been fulfilled. In design and development, validation concerns the process of examining a product or result to determine conformance to user needs.
Value of a Statistical Life (VSL)The standard approach to placing a dollar value on the life-saving benefits of an action based on societal willingness to pay (WTP) for mortality risk reductions. Also a convenient way to summarize the value of small reductions in mortality risks. A statistical life is not any individual person's life; it represents the change in premature mortality across a population from any given cause.
VaporThe gas given off by substances that are solids or liquids at ordinary atmospheric pressure and temperatures.
Vapor PressureA measure of a substance's propensity to evaporate, vapor pressure is the force per unit area exerted by vapor in an equilibrium state with surroundings at a given pressure. It increases exponentially with an increase in temperature. A relative measure of chemical volatility, vapor pressure is used to calculate water partition coefficients and volatilization rate constants.
VerificationConfirmation by examination and provision of objective evidence that specified requirements have been fulfilled. In design and development, verification concerns the process of examining a result of a given activity to determine conformance to the stated requirements for that activity.
VolatileAny substance that evaporates readily.
Voluntary AgreementsVoluntary initiatives range from arrangements in which the parties (usually enterprises or their trade associations) set their own targets, on toxics-use reduction for example, and often do their own monitoring and reporting, to commitments made by an industrial sector in negotiation with public authorities, or government.


Water Quality CriteriaLevels of water quality expected to render a body of water suitable for its designated use. Criteria are based on specific levels of pollutants that would make the water harmful if used for drinking, swimming, farming, fish production, or industrial processes.
Water Quality StandardsState-adopted and EPA-approved ambient standards for water bodies. The standards prescribe the use of the water body and establish the water quality criteria that must be met to protect designated uses.
Water SolubilityThe maximum possible concentration of a chemical compound dissolved in water. If a substance is water soluble it can very readily disperse through the environment.
Weight of Scientific EvidenceConsiderations in assessing the interpretation of published information about toxicity - quality of testing methods, size and power of study design, consistency of results across studies, and biological plausibility of exposure-response relationships and statistical associations.
WHOWorld Health Organization.
Willingness-to-Pay (WTP)The stated price that an individual would accept to pay for avoiding the loss or the diminution of an environmental service.




Hatfield Consultants The World Bank funded by the Canadian POPs Trust Fund through the      
Canadian International Development Agency
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