Chlorinated dibenzo-p-dioxin and dibenzofuran concentrations in beef animals from a feeding study

Four calves were fed polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans for 120 days at levels somewhat higher than what may be found in forage near some waste incinerators and manufacturing plants. Four calv es were fed identical diets but without the chemicals. Using bioelectrical impedance measurements of total body fat, 30-50% of the dosed 2,3,7,8-TCDD, 1,2,3,7,8-PeCDD, and 2,3,4,7,8-PeCDF was estimated to be retained by the a nimals. Although these same congeners were bioconcentrated in adipose tissu e (BCF similar to 10), consumer products such as ribeye showed concentratio ns less than what were found in the animal feed (BCF similar to 0.1). Distr ibution of the dioxins and furans into various lipid compartments appeared to be rather uniform in back fat, perirenal fat, and ribeye for tetra to he xa congeners. Ribeye, serum, and liver lipids had higher concentrations of the higher chlorinated congeners, due in part to not reaching a steady stat e. An unexpected source of dioxin and furan contamination was discovered du ring the experiment, resulting in the control animals having concentrations of some congeners that were equal to or in some cases greater than those o f the dosed animals. Pentachlorophenol-treated wood components in the pole barn where the feeding experiment was conducted were found to have contribu ted to the animals' exposure.