OXIDATIVE DAMAGE ON DNA INDUCED BY ASBESTOS AND MAN-MADE FIBERS INVITRO

We compared the potential of asbestos and man-made fibers to attack DNA by the determination of the yield of 8-hydroxy-2'-deoxyguanosine (8-OH-dGuo) under several in vitro conditions. Asbestos induced 6.6-99.8 of 8-OH-dGuo per 10(5) dGuo in calf thymus DNA after 20 h of incubation, while the levels of 8-OH-dGuo in man-made fibers were low (3.6-9.4). The amounts of 8-OH-dGuo were strongly stimulated by the addition of H2O2 in asbestos, but not in man-made fibers. However, the yield of 8-OH-dGuo was induced more than that with asbestos by the further addition of FeSO4 in attapulgite, fiberglass, potassium titanate whisker, and metaphosphate polymer. The addition of ethylene diamine tetraacetic acid (EDTA) promoted the induction of 8-OH-dGuo with asbestos and H2O2. The effects of mannitol (known as a hydroxy radical scavenger) were not dramatic on 8-OH-dGuo induction by all fibers except fiberglass and basic magnesium sulfate whisker, which induced higher amounts after mannitol addition than in these fibers and H2O2. Therefore, it was suggested that asbestos could damage DNA, resulting in 8-OH-dGuo as a cause of point mutation, and also several types of manmade fibers had similar effects to asbestos under certain conditions.