Comparative Absorption and Bioaccumulation of Polybrominated Diphenyl Ethers following Ingestion via Dust and Oil in Male Rats

Household dust has been implicated as a major source of polybrominated diphenyl ether (PBDE) exposure in humans. This finding has important implications for young children, who tend to ingest more dust than adults and may be more susceptible to some of the putative developmental effects of PBDEs. Absorption parameters of PBDEs from ingested dust are unknown; therefore, the objectives of this study were to determine and to compare the uptake of PBDEs from either household dust (NIST Standard Reference Material 2585) or a corn oil solution. Male rats were administered dust or corn oil doses at 1 or 6 microg of PBDEs kg(-1) body wt in the diet for 21 days (n = 4 rats per group). The concentrations of 15 PBDEs were measured in adipose tissue and liver from each treatment group and showed that bioconcentration was congener dependent, but for the majority of congeners, the concentrations did not differ with either dose level or dose vehicle. Hepatic Cyp2b1 and 2b2 mRNA expression increased in rats receiving the higher PBDE doses, suggesting potential effects on metabolic activity. Retention of PBDEs in tissues ranged from5% of the dose for BDE-209 to 70% for BDEs-47, 100, and 153 but generally did not differ between the high dust and high oil treatment groups. Excretion via the feces was significantly lower in the high oil dosed rats suggesting differences in absorption, excretion, and/or metabolism. The present study shows that PBDEs in dust are readily bioavailable and are biologically active, as indicated by increased transcription of hepatic enzymes.