<unk>  <unk>  expresses the<unk> ity of dioxins, furans and PCBs in terms of the most<unk>  form of dioxin, 2,3,7,8-TCDD. The<unk> ity of the individual congeners may vary by orders of magnitude. With the<unk> s, the<unk> ity of a mixture of dioxins and dioxin-like compounds can be expressed in a single number - the<unk><unk>  (TEQ). It is a single figure resulting from the product of the concentration and individual<unk>  values of each congener. The<unk> /TEQ concept has been developed to facilitate risk assessment and regulatory control. While the initial and current set of<unk> s only apply to dioxins and dioxin-like chemicals (DLCs), the concept can theoretically be applied to any group of chemicals satisfying the extensive similarity criteria used with dioxins, primarily that the main mechanism of action is shared across the group. Thus far, only the DLCs have had such a high degree of evidence of<unk> ological similarity. There have been several systems over the years in operation, such as the International<unk>  Equivalents for dioxins and furans only, represented as I-TEQDF, as well as several country-specific<unk> s. The present World Health Organization scheme, represented as WHO-TEQDFP, which includes PCBs is now universally accepted.
Toxic equivalency factor
Fractional kill
Equivalent dose
Dose area product
Median lethal dose
Maximum acceptable toxicant concentration
Therapeutic index
Dose profile