Occupational and environmental factors enhancing the genotoxicity of asbestos

Epidemiological and experimental studies have suggested the enhancement of asbestos-induced disease processes by simultaneous exposure to kerosene, it s soot, and cigarette smoke in asbestos-exposed animals as well as in human s. To determine the influence of these factors on the genotoxic potential o f asbestos, a micronucleus lest was performed in Syrian hamster embryo fibr oblasts (SHE) and human lymphocytes. To observe the specific chromosomal da mages, multicolor fluorescence in situ hybridization (FISH) was done in the lymphocytes from smokers and nonsmokers exposed in vitro to asbestos. Sign ificantly higher numbers of micronuclei were observed in SHE cells after co mbined treatment with chrysotile and kerosene soot (111 micronuclei/1000 ce lls) in comparison to chrysotile and kerosene soot separately. kinetochore staining revealed mainly clastogenic effects in all the cases. In human lym phocytes exposed in cultures to chrysotile and crocidolite the numbers of m icronuclei were found higher in smokers than nonsmokers. Multicolor FISH as say suggested that asbestos fibers inflict high damage within 1q12 and in t he region between 1 cen and 1q12 of chromosome 1. In the exposed population of an asbestos cenment factory: the highest generic damage was found in th e blood lymphocytes of exposed smokers. The study suggests that smokers occ upationally exposed to asbestos and domestically to kerosene soot are at hi gher risk for the early development of asbestos-induced diseases.