Cytogenetic and pathogenic effects of long and short amosite asbestos

This study utilized two samples of amosite asbestos which differ in their length, but not in their diameter and which have been shown previously to have very different abilities to cause pathology in rats exposed by instillation or inhalation. The activity of these amosite samples in causing chromosomal aberrations in Chinese hamster ovary cells in culture was examined, along with the effect of the glutathione (GSH) synthesis-inhibiting agent buthionine sulphoximine. The incidence of chromosomal aberrations in cells treated with the short fibre sample was similar to control levels; the long amosite sample caused significantly more chromosomal aberrations than the short fibre sample. When cells were treated with buthionine sulphoximine to decrease the levels of intracellular glutathione, the incidence of chromosomal aberrations was increased in the control cells, but also on treatment with both short and long amosite, the long sample again being considerably more active than the short. The pathogenicity of the long amosite may result from the ability of the fibres to cause chromosome damage, while the enhancement of this damage caused by decreasing intracellular glutathione suggests that the asbestos fibres may impose an oxidant stress on the cells which contributes to these aberrations.