Evaluating external contamination of polybrominated diphenyl ethers in human hair: Clinical and research implications

Background: Human hair is a well-validated matrix for detecting a variety of xenobiotics, including drugs of abuse (cocaine, tetrahydrocannabinol, and morphine) and fatty acid ethyl ethers. Recent studies have shown that hair can also be useful in determining an individual's exposure to polybrominated diphenyl ethers (PBDEs), flame retardants that contaminate the dust in our daily environment. Hair processing before assay varies with each analyte; in particular, the wash protocol must be optimized to remove external contaminants while not affecting levels of the chemical of interest. The aim of this study was to determine whether hair needs to be washed before analysis for PBDEs, and if so, which protocol is most effective to ensure that the level of PBDEs is neither overestimated nor underestimated. Method: Individual hair samples from 10 adults (5 men and 5 women) were subjected to 4 different wash protocols: (1) no wash, (2) water, (3) 10% sodium dodecyl sulfate (SDS), and (4) hexane. Both the washes and hair were analyzed for 8 PBDEs by gas chromatography/mass spectrometry. Results: The sum of PBDEs (ΣPBDEs) in the washes was (1) no wash: 0 pg/mg, (2) water: 0.39 ± 0.19 (mean ± SEM), (3) 10% SDS: 1.34 ± 0.68, and (4) hexane: 1.92 ± 0.87. The ΣPBDEs in the hair were: (1) no wash: 20.32 ± 3.05, (2) water: 20.30 ± 2.41, (3) 10% SDS: 19.27 ± 1.87, and (4) hexane: 16.91 ± 2.89. Washing with water, 10% SDS, and hexane decreased the PBDE levels by 1.9%, 7%, and 11.4%, respectively (P < 0.05). Conclusions: Thus, of the washes evaluated, water is the wash that had the least effect on total PBDE concentrations, providing the best evaluation of an individual's exposure to PBDEs.