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UBC Theses and Dissertations

Methylmercury exposure in British Columbian anglers who consume both recreationally caught and commercially bought fish Kodama, David Michael Yuko


Methylmercury is a common contaminant found in fish. Chronic exposure can have detrimental effects on the nervous, cardiovascular and immune systems. Since mercury exposure can come from consuming fish that is caught as well as fish that is purchased, recreational anglers are a group that may have higher exposure than non-anglers. It was the primary goal of this study to determine whether exposure to methylmercury in Vancouver Island recreational anglers was greater from the consumption of sport-fish or from commercial fish. Study participants were recruited from the BC Ministry of Environment freshwater fishing license list. A comprehensive questionnaire was administered over the telephone to enumerate potential sources of exposure to methylmercury. While the questionnaire primarily focused on the frequency, mass and species of fish consumed, other exposure sources were also examined. Following the questionnaire, a blood sample was collected and analyzed for mercury. A total of 195 anglers between the ages of 21 and 85 participated in the study. 80% of the subjects were male and approximately 90% were born in Canada. The geometric mean blood-mercury concentration was 2.33 ± 2.16 μg/L. In multiple regression analysis, the consumption of caught rockfish, shellfish and cutthroat trout as well as bought fresh/frozen albacore tuna, fresh/frozen ‘other’ tuna, i.e. ahi, skipjack or yellowfin, and snapper were found to be the greatest predictors of exposure. The results of this study demonstrated that exposure to methylmercury in Vancouver Island anglers was equally distributed between recreational and commercial fish species. The observed blood-mercury concentrations were consistent with similar studies, as was the discovery that it was primarily the frequent consumption of fish species containing low to moderate amounts of mercury that drove exposure. While this study determined that three recreational and three commercial fish species were predictors of exposure, five of these six were saltwater species while the sixth, cutthroat trout, was anadromous. Future studies should therefore focus on evaluating the differences in exposure between fresh and saltwater fish consumption. In addition, conducting a comprehensive survey of tissue-mercury levels in Vancouver Island fish would provide valuable region-specific data, leading to better exposure estimates in anglers.

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