The USDA perspective on dioxin concentrations in dairy and beef

The major dioxin-related research activities in the United States Department of Agriculture are 1) a survey of dioxin levels in beef samples collected at 13 experiment stations throughout the United States, 2) a feeding study of eight dioxins, four furans, and three PCB at levels equal to or above levels expected at highly industrialized locations, and 3) metabolism studies of 14C-labeled dioxin congeners. Preliminary results indicate that geographical location may influence dioxin concentrations in beef and that bulls may have concentrations higher than those in other slaughter animals. Metabolism of nontoxic congeners seems to be rather complex, involving the arene oxide pathway, NIH type shifting of chlorine, and conjugation with sulfuric acid and glucuronic acids.