Comparison of 2,2',4,4',5,5'-hexachloro[14C]biphenyl levels in different adipose tissues of dogs and monkeys.

The polychlorinated biphenyl isomer, 2,2',4,4',5,5'-hexachloro[14C]biphenyl (2,4,5-HCB) was administered as a single iv dose at 0.6 mg/kg to dogs and monkeys. Adipose tissue, which included omentum, pericardial, perirenal, peritesticular, and subcutaneous fat, and blood were collected at various termination times and analyzed for total 14C and the parent hexachlorobiphenyl (HCB). Significant differences (p less than 0.0005) in the total hexachlorobiphenyl concentration as measured by total radioactivity (14C equivalents) were noted in the various adipose tissues and in the same adipose tissues with time. Peritesticular fat was consistently lower in the concentration of 14C equivalents than the other adipose tissues, which were nearly equal. The concentrations in subcutaneous fat samples were inconsistent. Total 14C equivalent concentrations in the adipose tissues either peaked or reached a maximum at Day 1 and Day 4 for dog and monkey, respectively. However, parent HCB fat/blood ratios continually increased over the time course of the experiment, because concentrations in blood decreased more rapidly than those in adipose tissue.