Fish contamination in the Mystic River Watershed: Risk identification, assessment, and management

Fish can bioaccumulate heavy metals and chlorinated organic compounds from the aquatic environment. Many of the substances present in fish tissue, like methylmercury, polychlorinated biphenyls (PCBs), and organochlorine pesticides, have a variety of toxic effects in humans and aquatic organisms. The consumption of contaminated fish is a major cause of human exposure to persistent environmental contaminants. Fish sampling studies conducted by the Massachusetts Department of Environmental Protection (MADEP) found high levels of contamination at water bodies within the Mystic River Watershed (MRW), and have led to the issuance of several fish consumption advisories by the Massachusetts Department of Public Health (MDPH). In order to gauge the degree of hazard posed by fish consumption, I used deterministic risk assessment to characterize Hazard Index (HI) and Excess Lifetime Cancer Risk (ELCR) values for different water bodies in the MRW. I also conducted field surveys of these water bodies to check for evidence of fishing and to observe what, if any, strategies were being employed to communicate risk at fishing locations. The results of the risk assessment reveal non-cancer and cancer risk values that exceed MADEP regulatory limits at low exposure frequencies for most of the water bodies. This thesis shows that fish consumed from parts of the MRW can pose an unacceptable risk to health, and suggests that current risk communication efforts be enhanced.