A clastogen is a material that can cause breaks in chromosome

Chromosome

A chromosome is an organized structure of DNA and protein found in cells. It is a single piece of coiled DNA containing many genes, regulatory elements and other nucleotide sequences. Chromosomes also contain DNA-bound proteins, which serve to package the DNA and control its functions.Chromosomes...

s, leading to sections of the chromosome being deleted, added, or rearranged. This is a form of mutagenesis

Mutagenesis

Mutagenesis is a process by which the genetic information of an organism is changed in a stable manner, resulting in a mutation. It may occur spontaneously in nature, or as a result of exposure to mutagens. It can also be achieved experimentally using laboratory procedures...

, and can lead to carcinogenesis

Carcinogenesis

Carcinogenesis or oncogenesis is literally the creation of cancer. It is a process by which normal cells are transformed into cancer cells...

, as cells that are not killed by the clastogenic effect may become cancerous. Known clastogens include acridine yellow

Acridine yellow

Acridine yellow, also known as acridine yellow G, acridine yellow H107, basic yellow K, and 3,6-diamino-2,7-dimethylacridine, is a yellow dye with strong bluish-violet fluorescence. It is a derivate of acridine. In histology, it is used as a fluorescent stain, and as a fluorescent probe for...

, benzene

Benzene

Benzene is an organic chemical compound. It is composed of 6 carbon atoms in a ring, with 1 hydrogen atom attached to each carbon atom, with the molecular formula C6H6....

, ethylene oxide

Ethylene oxide

Ethylene oxide, also called oxirane, is the organic compound with the formula . It is a cyclic ether. This means that it is composed of two alkyl groups attached to an oxygen atom in a cyclic shape . This colorless flammable gas with a faintly sweet odor is the simplest epoxide, a three-membered...

, arsenic

Arsenic

Arsenic is a chemical element with the symbol As, atomic number 33 and relative atomic mass 74.92. Arsenic occurs in many minerals, usually in conjunction with sulfur and metals, and also as a pure elemental crystal. It was first documented by Albertus Magnus in 1250.Arsenic is a metalloid...

, phosphine

Phosphine

Phosphine is the compound with the chemical formula PH3. It is a colorless, flammable, toxic gas. Pure phosphine is odourless, but technical grade samples have a highly unpleasant odor like garlic or rotting fish, due to the presence of substituted phosphine and diphosphine...

 and mimosine

Mimosine

Mimosine or leucenol is an alkaloid, β-3-hydroxy-4 pyridone amino acid. It is a toxic non-protein free amino acid otherwise chemically similar to tyrosine, and was first isolated from Mimosa pudica. It occurs in a few other Mimosa spp...

.
Exposure to clastogens increases frequency of abnormal germ cells in paternal males, contributing to developmental effects in the fetus upon fertilization.