POPs Toolkit Glossary

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