|Birnbaum, Linda - US EPA|
Submitted to: Environmental Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 18, 2008
Publication Date: August 1, 2008
Citation: Huwe, J.K., Hakk, H., Birnbaum, L.S. 2008. Tissue distribution of polybrominated diphenyl ethers in male rats and implications for biomonitoring. Environmental Science and Technology 42:7018-7024. doi:10.1021/es801344a Interpretive Summary: Polybrominated diphenyl ethers (PBDEs) are a class of flame retardant chemicals widely used in electronics and household goods and spread into the environment. Humans and wildlife are exposed to PBDEs through both their diet and their environments. Because these compounds can accumulate in the body and may have potential health effects, it is prudent to monitor them in humans and wildlife to estimate exposures. Common samples used for monitoring these chemicals in humans and wildlife are blood, fat, muscle, and breast milk. In a controlled laboratory feeding study, we used rats as a model to determine how numerous PBDEs distributed throughout the body and what a suitable matrix for estimating body burdens and, thereby, exposures to these compounds would be. The PBDEs fed to the rats distributed to all tissues in the body. Our results showed that blood samples tended to be the best matrix for measuring all of the PBDEs and gave a reasonable estimate of the total body burden. Because blood is a relatively easy sample to collect, it may be the most suitable matrix for measuring numerous PBDEs in humans and wildlife.
Technical Abstract: 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. Exposure to PBDEs can be through both diet and the environment and is generally estimated by measuring PBDEs in blood, adipose tissue, muscle, or milk samples. Using rats as a model, we investigated tissue distribution of PBDEs after oral administration and evaluated a suitable matrix for body burden estimation. Male rats were administered dust or corn oil containing 8 or 6 micrograms PBDEs kg-1 body wt, respectively, in the diet for 21 days (N = 4 rats per treatment), and the concentration of 15 PBDEs were measured in various tissues, plasma, and feces. PBDEs were found in all tissues, including the brain, and showed no difference in distribution patterns between treatments for most PBDEs. Tri- to hexa-BDEs comprised >80% of the total PBDEs in the adipose, brain, kidney, lung, and residual carcass, but <40% in the liver and plasma. The ratio of the lipid-weight concentration of tri- to hexa-BDEs in adipose tissue, residual carcass, and plasma was 1:1:2. For the hepta- to nona-BDEs, lipid-weight concentrations increased from adipose tissue to residual carcass to plasma in the ratio 0.3:1:>4. BDE-209 was the dominant congener in the liver and plasma, but was not detected in the adipose tissue or carcass. In summary, the lower brominated congeners tended to distribute equally into lipids implying both adipose tissue and plasma would be suitable matrices for biomonitoring. Plasma was the best matrix for detection of the higher brominated congeners (especially BDE-209), although on a lipid-weight basis tended to over-estimate the total body burdens.