Research Product

There have been many suggestions that cancers in fish and other marine organisms are commonplace and are attributable to chemical pollution. There is also concern that, as a number of known carcinogens are accumulated by marine organisms that are commercially exploited for human food, they may present a risk to man. A critical review of the European and North American literature concerning cancer in fish and shellfish shows that, although there are indeed many reports of "cancers" and "precancerous" lesions in fish and shellfish, there is considerable evidence to suggest that due to improper use of terminology, some of the reports are erroneous or misleading. There is strong circumstantial evidence, especially from North America, that polycyclic aromatic hydrocarbons and a few other hydrocarbons may cause liver cancer in fish and shellfish. However, there is very little unambiguous evidence to suggest that other cancers in fish are associated with chemical contaminants. Although the adverse effect on individual fish is undisputed, the review identifies no basis for concern for the survival of marine fish populations, even at local levels, due to carcinogens in the marine environment. From a human health standpoint, at normal levels of consumption and contamination, the data on consumption of potential carcinogens via marine fish and shellfish give little reason for concern in relation to most of the substances considered. However, there may be increased risks to high seafood consumers in cases where the ingested seafood is abnormally contaminated with carcinogens, particularly PAHs. Therefore, there is a need for continued vigilance and controls over the disposal of known carcinogens into the environment. More research is necessary to establish cause and effect relationships between carcinogens and marine species. Thus far it is assumed that only chemicals which induce cancer in terrestrial mammals are likely to be the causative agent of cancers in marine organisms. This may or may not be correct. The review suggests that discharges of carcinogens into the marine environment should be kept as low as possible, taking into account technical and economic circumstances. The present risk is small but the potential one is real enough to predicate the restrictions currently applied to carcinogens in general, and to those specifically identified in this review as potential carcinogenic agents, in particular.