Mutagenicity and neoplasia

There is overwhelming evidence that certain PAHs are well-known mutagens that can cause genetic damage, toxi-copathic lesions, and tumor formation. Most of the studies describe the mutagenic properties of PAHs in mammals, which has been directed at human health. Several review articles describe many of the relevant studies for ecotoxi-cologists concerning PAH-induced abnormalities.

Potential mutagens are those PAHs containing four to six rings (HPAHs). Additionally, the alkyl moiety often increases the mutagenic potential. Based on the diverse sources of PAHs in the environment and urban areas, there is ample opportunity for both humans and other species to be exposed. Much of the mammalian literature is directly applicable to wildlife, including most vertebrates. Because metabolic activation of PAHs is necessary for the expression of mutagenic properties, well-developed biotransformation capabilities are needed. For that reason, many invertebrate species do not exhibit alterations to DNA from exposure to PAHs.

Several field studies have observed histopathological changes and tumor formation in fish associated with sites contaminated with PAHs. Also, one recent study examined cancer in beluga whales and concluded that PAHs were the likely cause. As noted by one author, several factors relating to PAH exposure and toxicity, such as specificity of response, dose-response relationships, experimental evidence, and others, strongly support the conclusion of PAH-induced neoplasia for fish from contaminated sites. This is one of the few examples where a specific (or group of) contaminant(s) can be associated with adverse effects in organisms collected in the field, which is likely applicable for other species.

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