Monograph 027 – Aneuploidy

Mono 027 : Aneuploidy | August 1997

Aneuploidy plays a significant role in adverse human health conditions including birth defects, pregnancy wastage and cancer. Although there is clear evidence of chemically induced aneuploidy in experimental systems to date there are insufficient data to determine with certainty if chemically-induced aneuploidy contributes to human disease. However, since there is no reason to assume that chemically induced aneuploidy will not occur in human beings, it is prudent to address the aneugenic potential of chemicals in the safety assessment process. A wide range of methods has been described for the detection of chemically induced aneuploidy including subcellular systems, tests with fungi, plants and Drosophila as well as in vitro mammalian systems and in vivo mammalian somatic and germ cell assays. However none of these methods are sufficiently validated or widely used for routine screening. Underlying the efforts to develop aneuploidy specific assays is the presumption that current genetic toxicology tests do not detect chemicals that have aneuploidy-inducing potential. To address this we have critically evaluated data from standard genetic toxicology assays for 16 known or suspected aneugens. The conclusions from the review are: - At present there are only nine chemicals that can be classified as definitive aneugens as determined by positive results in in vivo rodent assays. - As expected, the majority of definitive and suspected aneugens are negative in the bacterial mutation assay. - The majority of definitive aneugens evaluated induced polyploidy in vitro. With few exceptions, they also induced structural chromosome aberrations in vitro. - All of the definitive aneugens that have been sufficiently tested induced micronuclei in rodent bone marrow cells in vivo. A number of these chemicals also induced structural chromosome aberrations in vivo. - There is no evidence for a unique germ cell aneugen, that is a chemical that induces aneuploidy in germ cells and not in somatic cells.