Enhanced withdrawal from chickens of hexachlorobenzene (HCB) and pentachlorophenol (PCP) by colestipol, mineral oil, and/or restricted feeding.

Young chickens fed hexachlorobenzene (HCB) or pentachlorophenol (PCP) for 14 d at 10 ppm in the diet contained body burdens of 573 or 362 micrograms, respectively. These diets were withdrawn (d 0) and replaced for 21 d with diets containing 5% mineral oil (MO), or 5% colestipol (CO), a bile-acid-binding resin, or the chickens were restricted in feed intake to 50% of controls (50-RF), fed MO plus 50-RF, or CO plus 50-RF. Without any treatment during withdrawal, body burdens were reduced to 63% and 70% of the d 0 values for HCB and PCP, respectively. MO, CO, or 50-RF reduced body burdens of HCB to 37% of d 0 burdens, but the combination treatments with 50-RF reduced body burdens to 19% of d 0 values. PCP was at 35% of the d 0 burdens from 50-RF, while all other treatments had reduced body burdens to nondetectable amounts of less than 0.7 micrograms/bird by d 21 of withdrawal. Body fat was not reduced by mineral oil, but was reduced to some extent by CO, and was markedly reduced by 50-RF. 50-RF always reduced body burdens of PCP or HCB alone or in combination with MO or CO. These data are discussed in relationship to the nonbiliary excretion of xenobiotics.