This article describes the induction of micronuclei, hyperdiploidy and chromosome breakage in human amniotic cells in vitro by amosite, chrysotile and crocidolite asbestos, and ceramic fibers. The response of human (amniotic fluid cells) and rodent (Syrian hamster embryo fibroblasts, SHE) cells to fiber treatment was compared using the micronucleus assay. The data of the rodent studies were taken from a previous investigation (Dopp, E. et al. (1995) Environ. Health Perspect., 103, 268-271). All types of mineral fibers caused a significant increase of micronucleated cells. The kinetochore analysis revealed that an three types of asbestos and ceramic fibers yielded similar effects. Approximately 50% of the induced micronuclei were kinetochore-negative indicating formation through clastogenic events. Human amniotic cells were much less susceptible than SHE cells to the induction of micronuclei by mineral fibers. This again demonstrates that SHE cells are more susceptible to chromosomal changes than human amniotic fluid cells. The application of fluorescence in situ hybridization (FISH) with tandem DNA probes yielded more detailed information about specific structural chromosome aberrations in the 1 (cen-q12) and 9 (cen-q12) regions and about abnormal numbers of chromosomes in interphase human amniotic fluid cells, Using this FISH approach we found a statistically significant increase of chromosomal breakage in the pericentric heterochromatin regions of chromosomes 1 and 9 in interphase human amniotic cells after exposure to asbestos and ceramic fibers compared to control cells. The number of hyperdiploid cells was also significantly increased. Our results show that asbestos fibers as well as ceramic fibers are inducers of structural and numerical chromosomal aberrations in human amniotic fluid cells.
