Abstract
Comparative studies on the absorption, distribution, and excretion of flame retardants, tris (2, 3-dibromopropyl) phosphate (TDBPP), bis (2, 3-dibromopropyl) phosphate (BDBPP), tris (1, 3-dichloro-2-propyl) phosphate (TDCPP), tris (1-chloro-2-propyl) phosphate (TMCPP) and tris (2-chlorethyl) phosphate (TMCEP), were carried out in rats. During 168 h after an oral administration of an equimolar dose (50 μmol/kg) of these 14C-labeled flame retardants, the decreasing order of levels of 14C-radioactivity excreted was TMCEP»TMCPP>TDBPP>BDBPP>TDCPP in urine, TDCPP>TDBPP>BDBPP>TMCPP»TMCEP in feces, and BDBPP>TDCPP>TDBPP»TMCPP>TMCEP in expired air. The amounts remaining in the carcass were in the order TDBPP=BDBPP>TDCPP>TMCEP=TMCPP. Almost 100% of the radioactivity administered was recovered, in the ranges of 43.2 to 93.4% in urine, 5.6 to 39.2% in feces, 1.7 to 19.4% in expired air (as 14CO2), and 0.7 to 3.7% in the body. Biliary excretion of the five flame retardants ranged from 24.6 to 44.9% of the dose by 48 h. The order of biliary excretion was as follows : TMCPP>TDCPP>BDBPP=TDBPP>TMCEP. Tris- or bis- (dihalogenated alkyl) phosphates were more slowly absorbed, distributed and excreted than tris (monohalogenated alkyl) phosphates. In binding studies in vitro, the order of covalent binding to S-9 of liver and kidney was as follows : TDBPP>MDBPP>BDBPP.
