Differential tissue distribution of various polybrominated biphenyls of Firemaster FF-1 in male rats.

Gas chromatography with an electron-capture detector was used to identify the major components of the polybrominated biphenyls (PBB's) in Firemaster FF-1. The distribution and clearance of the PBB's in rat whole blood, grey and white matter, cerebellum, heart, kidney, liver, spleen, lung, jejunum, testes, and subcutaneous fat from the inguinal region were determined at various times after a single dose of 10 mg/kg of Firemaster FF-1 given orally. Peak blood levels of PBB occurred within 4 hr whereas levels in inguinal subcutaneous fat peaked 7--14 days after the single oral dose. Concentrations in other tissues peaked usually within 12 hr and showed complex logarithmic decline over time. 2,2',4,5,5'-Pentabromobiphenyl (PnBBa) was cleared much more rapidly from the rat than 2,3',4,4',5-pentabromobiphenyl (PnBBb) or any of the higher molecular weight analogs. Furthermore, PnBBa penetrated the brain more rapidly. Each of the PBB analogs was found in all tissues examined but varied in both rate of absorption and clearance.