Procedures to enhance withdrawal of xenobiotics from chickens.

Egg- and meat-type chickens were fed diets containing 1 or 10 ppm of fireMaster (FF-1), a commercial mixture of polybrominated biphenyls (PBBs), predominantly 2,4,5,2',4',5'-hexabromobiphenyl (6BB-4) and 2,3,4,5,2',4',5'-heptabromobiphenyl (7BB-8). These congeners account for approximately 65 and 14%, respectively, of the total mix. In three experiments, colestipol hydrochloride, a bile acid-binding resin, and mineral oil, alone or in combination with restricted feeding, were examined as procedures to enhance the removal of the PBBs. The combination of 50% dietary restriction plus a 10% dietary concentration of colestipol or mineral oil reduced body burdens of PBBs about 70% within 21 d for chickens previously fed 10 ppm PBBs. The use of feed restriction, colestipol, or mineral oil produced only borderline effects for hastening withdrawal. Chickens not treated showed only a 3% loss of PBBs during the withdrawal period. Colestipol at 2.5% in the diet in combination with feed restriction was not consistently effective in removing body burdens of PBB from chickens previously fed 1 or 10 ppm PBBs, indicating a dose-response effect. Chickens previously fed 1 ppm eliminated up to 40% of the PBBs in 21 d without any treatment, as compared to the 3% loss occurring after feeding with 10-ppm concentrations.