Student Research: Nancy Judd
PCBs are persistent environmental toxicants that have been associated with neurological, developmental, and immune system effects as well as carcinogenesis in animals and humans. PCBs have been detected in all species of fish monitored in the past ten years by the Puget Sound Ambient Monitoring Program. Recent surveys of Tulalip and Squaxin Island Tribe members and Asian and Pacific Islanders (API) in the Puget Sound are have demonstrated seafood consumption rates far greater than the 22 g/day default recommended in the EPA Exposure Factors Handbook. There is concern about possible health risks from PCB exposure through seafood for these groups, but estimation of exposure is difficult due to inadequacies of environmental and consumption data. This study first assesses confidence in available PCB data for each species consumed as a percent of total seafood consumption. A prioritization scheme based on species specificity, data quality, and location compatibility was developed to rate confidence in seafood PCB data. For API, 45.9% of total seafood consumed is shellfish; the geographic source of only 11% is known. Seafood PCB data applicable for chronic risk assessment could be identified for less than ten percent of total mass seafood consumed. For the Tribes, PCB data appropriate for chronic risk assessment could be identified for over half of the seafood consumed. 72-80% of anadromous fish, which dominate their seafood diets, is harvested in Puget Sound. To explore the value of specific contaminant and consumption data for human health risk assessments, hypothetical exposure and risk assessments based on consumption of Puget Sound crab and salmon were performed. These included consideration of cooking and preparation and use of Monte Carlo modeling techniques. Cancer risk estimates based on the congener specific PCB data and dioxin toxic equivalency factors were compared to risk estimates made using total PCB or Aroclor PCB data. This exercise demonstrated the importance of sufficient sensitivity in analytical methods, particularly for detection of the most toxic PCB congener. Results suggest that while PCB exposure from seafood consumed by some groups cannot be well characterized, specific consumption and environmental data may lead to more informed risk estimates.