The mutagenic hazards of settled house dust: a review

Given the large proportion of time people spend indoors, the potential health risks posed by chemical contaminants in the indoor environment are of concern. Research suggests that settled house dust (SHD) may be a significant source for indoor exposure to hazardous substances including polycyclic aromatic hydrocarbons (PAHs). Here, we summarize the literature on the mutagenic hazards of SHD and the presence of PAHs in dust. We assess the extent to which PAHs are estimated to contribute to the mutagenicity of SHD, and evaluate the carcinogenic risks associated with exposures to PAHs in SHD. Research demonstrates that SHD has a Salmonella TA98 mutagenic potency of 1000-7000 revertants/g, and contains between 0.5 and 500 microg/g of PAHs. Although they only account for a small proportion of the variability, analyses of pooled datasets suggest that cigarette smoking and an urban location contribute to higher levels of PAHs. Despite their presence, our calculations show that PAHs likely account for less than 25% of the overall mutagenic potency of dust. Nevertheless, carcinogenic PAHs in dust can pose potential health risks, particularly for children who play and crawl on dusty floors, and exhibit hand-to-mouth behaviour. Risk assessment calculations performed in this study reveal that the excess cancer risks from non-dietary ingestion of carcinogenic PAHs in SHD by preschool aged children is generally in the range of what is considered acceptable (1 x 10(-6) to 2 x 10(-6)). Substantially elevated risk estimates in the range 1.5 x 10(-4) to 2.5 x 10(-4) correspond only to situations where the PAH content is at or beyond the 95th percentile, and the risk estimates are adjusted for enhanced susceptibility at early life stages. Analyses of SHD and its contaminants provide an indication of indoor pollution and present important information for human exposure assessments.