Submitted to: Environmental Science and Technology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 12/18/2007
Publication Date: 2/21/2008
Citation: Huwe, J.K., Hakk, H., Smith, D.J., Diliberto, J.J., Richardson, V., Birnbaum, L.S., Stapleton, H.M. 2008. Comparative absorption and bioaccumulation of polybrominated diphenyl ethers following ingestion via dust and oil in male rats. Environmental Science and Technology 42:2694-2700. Interpretive Summary: Polybrominated diphenyl ethers (PBDEs) are flame retardant chemicals used in many household products such as upholstery, electronic goods, and furniture. As such PBDEs are present throughout most houses and can collect in household dust. By ingesting dust, humans may be exposed to PBDEs. The extent to which PBDEs in dust can be absorbed into the body is unknown; therefore, we have conducted a study in rats to determine the absorption of PBDEs from household dust and compare this absorption to absorption that may occur from a typical dietary intake route i.e. PBDEs in a corn oil solution. After dosing rats for 21 days with PBDEs adhered to dust or dissolved in corn oil, we found that PBDEs were readily absorbed into and distributed throughout the rats from either the dust or oil. The results of the study support the hypothesis that, in addition to diet, household dust is a likely source of PBDE intake and must be taken into account when estimating human PBDE exposure because humans ingest dust on a daily basis. In addition the absorbed PBDEs showed the potential to affect metabolic activity in the rats.
Technical Abstract: Household dust has been implicated as a major source of polybrominated diphenyl ether (PBDE) exposure in humans. This finding has important implications especially 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 compare the absorption 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 microgram PBDEs kg bw-1 in the diet for 21 days (n = 4 rats per group). The concentrations of fifteen PBDEs were measured in adipose tissue and livers from each dose group and showed that the bioconcentration of individual PBDEs 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. While tissue distribution and retention of PBDEs was not different between the high dust and high oil dosed groups, excretion in the feces was significantly lower in the high oil dosed rats suggesting differences in absorption and/or metabolism. The present study shows that PBDEs in dust are readily bioavailable and biologically active as indicated by increased transcription of hepatic enzymes.