Exposure Assessment of Polybrominated Diphenyl Ethers in Dust – A Study of Potential Exposure and Examination of Concentration Distribution Sieved to Particle Sizes between 500 and 38 µm

Background: Polybrominated diphenyl ethers (PBDEs) are additive flame retardants which are found in household and commercial products. These chemicals have the potential to leach from the product into the environment. Human health effects include neurodevelopmental changes, low birth weight and thyroid hormone changes have also been reported, although continued research in this field is needed. Humans are exposed to PBDEs through various exposure pathways and recent studies have determined that exposure to household dust is also a significant route of exposure for humans. The purpose of this study was to access the risk for PBDE intake through an exposure assessment. Also, a laboratory protocol for the fractionation and determination of PBDEs in household dust was developed and evaluated. Methods: PBDE concentrations in indoor dust were measured and compared to previously published data on the topic. A laboratory protocol for fractionation of indoor dust and determination of PBDEs in indoor dust was developed. The new laboratory method was compared to a previously published lab procedure to determine its effectiveness. A p-value of \u3c0.01 and 95% confidence intervals were used to determine statistical significance. Intake estimates were also determined for adults and children exposed at different rates. Results: PBDEs were detected in all the house dust samples with total concentrations (sum of 12 congeners) ranging from 2,870 to 50,642 ng/g dry mass. The averaged concentrations from the six replicate sieve fractions ranged from 106 to 5,697 ng/g dry weight. Daily dust intake rates, based on previously published estimates, range from 20 to 200 mg/day for children and 0.56 to 50 mg/day for adults. Low and high estimates of the daily intake of PBDEs in children and adults were calculated using the average concentration of total PBDEs found in house dust in this study. The exposure estimates for children were approximately 371 to 3,709 ng PBDEs daily based on a mean value of 18,546 ng/g dry weight. The estimate for adults was approximately 10.4 to 927 ng/g dry weight. Conclusions: The new laboratory protocol produces comparable results for QA/QC materials compared to a previously published protocol. Particulate size does not appear to be a significant factor in PBDE concentration and future analysis may only need dust particles to be sieved to one or two sizes (i.e. 500 um and 125 um). Based on the potential intake calculations for children and adults, dust appears to be a significant route of exposure for PBDEs and analysis of additional dust samples will broaden the scope of available data for this method