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Tissue distribution of polybrominated diphenyl ethers in rats following oral exposure and the relationship to body burdens
Citation:
Huwe, J. K., H. Hakk, H. M. STAPLETON, AND L. S. BIRNBAUM. Tissue distribution of polybrominated diphenyl ethers in rats following oral exposure and the relationship to body burdens. Presented at 18th Annual International Society of Exposure Analysis Conference, Pasadena, CA, October 12 - 16, 2008.
Impact/Purpose:
The purpose of this study was to determine whether or not PBDEs are bioavailable from house dust and, if so, what are the congener-specific differences in their overall disposition.
Description:
Polybrominated diphenyl ethers (PBDEs) are a class of widely-used flame retardants which have been found to persist, bioaccumulate, and potentially affect development in animals. Humans are exposed to PBDEs through both their diet and indoor environment. In human exposure studies, blood, adipose tissue, and breast milk have generally been used to estimate total body burdens of PBDEs. Using rats as a model, we looked at the tissue distribution of PBDEs after oral administration and evaluated a suitable matrix for body burden estimation. Eight male Sprague-Dawley rats were fed a diet containing either PBDE-contaminated dust mixed into the feed or a PBDE formulation dissolved in oil and given with the feed for 21 days. Tissues and plasma from each rat were analyzed for PBDEs by high resolution GC/MS. PBDEs were found in all tissues including adipose, brain, kidney, liver, residual carcass, and plasma. Tri- to hexa-BDEs comprised >80% of the PBDEs in the adipose, brain, kidney, and carcass; but <40% of the total PBDEs in the liver and plasma. On a lipid weight basis, the concentrations of tri- to hexa-BDEs in adipose tissue were similar to the concentrations in the residual carcass (adipose:carcass = 0.6 – 1.5). Plasma concentrations averaged slightly higher than the concentrations in the residual carcass (plasma:carcass = 1.2 – 3.7). For the hepta- to deca-BDEs, adipose tissue concentrations were lower than the residaul carcass (adipose:carcass = 0.02 – 0.5), and plasma levels were generally higher (plasma:carcass = 0.8 – 12.9). The results show that the lower brominated congeners tend to distribute equally into lipids implying that both adipose tissue and plasma could provide adequate estimates of total body burdens. However, the higher brominated congeners (hepta- to deca-BDEs) were not as predictable; adipose tissue tended to under-estimate and plasma to over-estimate and the total body burdens.