Commentary. Concluding remarks on Session I

The papers presented during the first session have provided a useful introduction and a review of several important points that have been established during the past decade. Many carefully studied near shore marine environments and freshwater lakes are polluted with chemicals as indicated primarily by measurements of certain organics and metals in sediments. Fish and shellfish, including bivalve mollusks (clams, mussels, oysters) and crustacean (crabs and shrimp) used as food resources by humans inhabit contaminated aquatic environments. Fish and shellfish, especially bivalve mollusks, concentrate many undesirable organics and metals in their tissues. Fish and shellfish suffer from cancerous diseases. For fmfish especially, there are correlations between the occurrence and/or prevalences ofcancerous diseases and the degree of chemical contamination in the environment they inhabit. Meyers (1), Wolke (2), and Black (3) all described such a relationship for fish and the aquatic systems they have studied. For bivalve mollusks, the connection between cancerous diseases and chemical contaminants is much less convincing (4). There has been little solid evidence ofa link between the two in studies conducted to date. Farley's studies on the sarcomas of softshell clams (Mya arenaria) from Maryland do not suggest a possible chemical causation (5). However, Gardner's interesting studies indicate that the germinomas ofM. arenaria from contaminated areas he has studied appear to be associated with certain chemicals in the environment (6). In addressing the central question to be considered during this conference (is there an increased risk due to the consumption of aquatic foods with measurable levels of contaminants?), the following general points and questions, related to the preceding papers, seem pertinent. Which chemicals, or classes of chemicals, are important relative to risk assessments for aquatic resources? How can this be determined? For various reasons, there has been a considerable emphasis on polycyclic aromatic hydrocarbons (PAH) in many studies conducted to date. However, given the uncertainties about oral PAH exposures causing tumors in humans (7) and the rapid metabolism ofPAH by fish, it may be more worthwhile to concentrate on other chemicals in the environment. Which compounds bioaccumulate in fish or shellfish? Which compounds bioaccumulate in edible tissues ofthese organisms? To what extent are they passed on to mammals if consumed? Which aquatic species are important food sources? Several species of fish mentioned during this session would not appear to be particularly important in assessing risk (e.g., carp, brown bullheads) while others are, at least in certain geographical areas