A clastogen is a material that can cause breaks in chromosomes, leading to sections of the chromosome being deleted, added, or rearranged. This is a form of mutagenesis, and can lead to carcinogenesis, as cells that are not killed by the clastogenic effect may become cancerous. Known clastogens include acridine yellow, benzene, ethylene oxide, arsenic, phosphine and mimosine. Exposure to clastogens increases frequency of abnormal germ cells in paternal males, contributing to developmental effects in the fetus upon fertilization.