Toxic equivalent
Encyclopedia
Toxic equivalence factor (TEF) expresses the toxicity
of dioxins, furans
and PCBs
in terms of the most toxic form of dioxin, 2,3,7,8-TCDD. The toxicity of the individual congeners may vary by orders of magnitude.
With the TEFs, the toxicity of a mixture of dioxins and dioxin-like compounds can be expressed in a single number - the toxic equivalent, TEQ. It is a single figure resulting from the product of the concentration and individual TEF values of each congener.
The TEQ concept has been developed to facilitate risk assessment
and regulatory control.
There have been several systems over the years in operation, such as the International Toxic Equivalents for dioxins and furans only, represented as I-TEQDF, as well as several country-specific TEFs. The present World Health Organisation scheme, represented as WHO-TEQDFP, which includes PCBs is now universally accepted.
Toxicity
Toxicity is the degree to which a substance can damage a living or non-living organisms. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a substructure of the organism, such as a cell or an organ , such as the liver...
of dioxins, furans
Polychlorinated dibenzofurans
Polychlorinated dibenzofurans are a group of halogenated organic compounds which are toxic environmental pollutants. They are known teratogens, mutagens, and suspected human carcinogens. PCDFs tend to co-occur with polychlorinated dibenzodioxins...
and PCBs
Polychlorinated biphenyl
Polychlorinated biphenyls are a class of organic compounds with 2 to 10 chlorine atoms attached to biphenyl, which is a molecule composed of two benzene rings. The chemical formula for PCBs is C12H10-xClx...
in terms of the most toxic form of dioxin, 2,3,7,8-TCDD. The toxicity of the individual congeners may vary by orders of magnitude.
With the TEFs, the toxicity of a mixture of dioxins and dioxin-like compounds can be expressed in a single number - the toxic equivalent, TEQ. It is a single figure resulting from the product of the concentration and individual TEF values of each congener.
The TEQ concept has been developed to facilitate risk assessment
Risk assessment
Risk assessment is a step in a risk management procedure. Risk assessment is the determination of quantitative or qualitative value of risk related to a concrete situation and a recognized threat...
and regulatory control.
There have been several systems over the years in operation, such as the International Toxic Equivalents for dioxins and furans only, represented as I-TEQDF, as well as several country-specific TEFs. The present World Health Organisation scheme, represented as WHO-TEQDFP, which includes PCBs is now universally accepted.