Excretion of polybrominated biphenyls into the milk of cows.

Four cows each were fed 10 mg/day polybrominated biphenyl for 60 days. Concentration in milk fat reached a steady state at 3.07 ppm within 30 days. When feeding polybrominated biphenyl was stopped, the concentration declined 71% in the first 15 days. The decline was slower thereafter, with a half-life of 58 days. Effects on health and production of the cows were not adverse for as long as 1 yr after the compound was fed.