| Apparent Half-Lives of Hepta- to Decabrominated Diphenyl Ethers in Human Serum as Determined in Occupationally Exposed Workers Kaj Thuresson,1 Peter Höglund,2 Lars Hagmar,3 Andreas Sjödin,1* Åke Bergman,1 and Kristina Jakobsson3 1Department of Environmental Chemistry, Stockholm University, Stockholm, Sweden; 2Competence Center for Clinical Research and 3Department of Occupational and Environmental Medicine, Lund University Hospital, Lund, Sweden Abstract
The aim of the present study was to model apparent serum half-lives of polybrominated diphenyl ethers (PBDEs) with 7-10 bromine substituents. Workers with occupational exposure to PBDEs have elevated serum levels of PBDEs, but these substances are also found in the general population and are ubiquitous environmental contaminants. The calculations were based on exposure assessments of rubber workers (manufactured flame-retarded rubber compound) and electronics dismantlers who donated blood during a period with no work-related exposures to PBDEs, and referents without any known occupational exposure (clerks, cleaners, and abattoir workers) . Theworkers had previously been found to have elevated levels of high- and medium-brominated diphenyl ethers compared with the referent populations. We performed nonlinear mixed-effects modeling of kinetics, using data from previous and present chemical analyses. The calculated apparent half-life for decabromodiphenyl ether (BDE-209) was 15 days (95% confidence interval, 11-18 days) . The three nona-BDEs and four octa-BDE congeners were found to have half-lives of 18-39 and 37-91 days, respectively. BDE-209 has a short half-life in human blood. Because BDE-209 is commonly present in humans in general, the results of this study imply that humans must be more or less continuously exposed to BDE-209 to sustain the serum concentrations observed. BDE-209 is more readily transformed and/or eliminated than are lower brominated diphenyl ether congeners, and human health risk must be assessed accordingly. Key words: BDE-209, BFR, brominated flame retardants, deca-BDE, half-life, human exposure, PBDEs, polybromodiphenyl ethers. Environ Health Perspect 114: 176-181 (2006) . doi:10.1289/ehp.8350 available via http://dx.doi.org/ [Online 21 September 2005]
Address correspondence to Å. Bergman, Department of Environmental Chemistry, Svante Arrhenius väg 12, Building C, Third Floor, Stockholm University, SE-106 91 Stockholm, Sweden. Telephone: 46-816-3997. Fax: 46-816-3979. E-mail: ake.bergman@mk.su.se *Current address: Centers for Disease Control and Prevention, NCEH/DLS/OAT, 4770 Buford Hwy., MS F-17, Atlanta, GA 30341-3724 USA. We gratefully acknowledge the cooperation of all the workers and personnel at the plants, especially those workers who willingly participated in the blood sampling during their summer vacation. We thank K. Kronholm Diab, C. Andersson, and M.-L. Hult for their valuable assistance with interviews and blood sampling and I. Athanassiadis for excellent mass spectrometry analysis. This study was financially supported by the Swedish Council for Working Life and Social Research (FAS) ; the Faculty of Science, Stockholm University ; and the Faculty of Medicine, Lund University. The authors declare they have no competing financial interests. Received 24 May 2005 ; accepted 21 September 2005.
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