Genotoxicity of organic extracts of house dust from Shanxi, China.

Indoor combustion of solid fuel such as coal may generate respirable particles containing polycyclic aromatic hydrocarbons (PAH) that may adhere to settled dust. Dust might therefore present a major source of PAH exposure in humans. This study evaluated the in vitro and in vivo genotoxicity of PAH mixtures extracted from house dust samples. Four dust samples (E1-4) were collected from houses in Shanxi, China, where coal is heavily used for heating and cooking. For comparison, a coal sample was also collected from one of the houses and included in the analyses. The samples were extracted with methylene chloride:acetone (95:5 v/v), dried, and redissolved in appropriate solvents for assessment in genotoxicity assays. Samples were evaluated for their ability to induce point mutations in bacteria and DNA adducts in vivo. DNA adduct levels were analyzed by nuclease P1-enhanced 32P-postlabeling. PAH were quantified using gas chromatography/mass spectrometry. Based on chemical analysis, sample E1 had the highest concentration by sampling area of benzo[a]pyrene (BaP) (181 microg/m2) and total PAH (10100 microg/m2). However, based on the microbial genotoxicity assay, sample E3, with the highest carcinogenic PAH/total PAH ratio (26%), produced the greatest number of revertants. In mice, administration of the extract of coal induced more adducts (9.81 adducts per 10(9) nucleotides) than dust extracts. The results of this study confirm the presence of genotoxic chemicals in residential dust. Inhalation of respirable particles containing similar mixtures of PAH represents a cancer risk for humans.