denotes the "total mass" of the 17 dioxin compounds of interest
in any given sample of dioxin. Dioxins almost always occur
as a complex mixture of individual compounds. The EPA requires
facilities to report the 2000 TRI dioxin data in units of
total grams, or grams-TM-17 (g-TM17).
"TM-17" reporting is different from "TEQ" reporting of dioxin
quantities. The TEQ method is a toxicity-weighted reporting
method whereby the masses of individual dioxin compounds are
scaled by Toxic Equivalency Factors (TEFs). Unlike the TM-17
method, the TEQ method offers meaningful information about
the total toxicity of a dioxin sample. Dioxins commonly are
reported using the TEQ method. The US EPA lists dioxin quantities
in grams-TEQ in its Inventory of Sources of Dioxin in the
United States. Click here for a
complete description of TEQ reporting.