Using a geographic information system to assess local scale methylmercury exposure from fish in nine communities of the Eeyou Istchee territory (James Bay, Quebec, Canada)

Exposure to methylmercury is a concern for those who rely on fish as a traditional food in the Eeyou Istchee territory of James Bay, Quebec, Canada, because industrial land uses overlap with community water bodies where fish are harvested. Consequently, this study assessed if traditional practices, particularly fishing, increased the risk of exposure to methylmercury from the consumption of locally harvested fish. We designed a geographic information system (GIS) that included land use and fish methylmercury tissue concentrations to assess clustering of potential hot spots. We also used generalized linear models to assess the association of fish consumption to blood organic-mercury concentrations, and logistic regression models to assess the probability of fish exceeding the safety threshold for methylmercury tissue concentrations in areas of high intensity land use. The GIS demonstrated significant clustered hot spots around regions of hydroelectric and mining land use. Our results also revealed that adult consumption of pike, lake trout and/or walleye, and child consumption of pike or walleye were significantly associated with blood organic-mercury concentrations. Further, large fish harvested in a community with high intensity land use yielded a 77% probability that the fish exceeded the safety threshold. From a human exposure perspective, our study highlights the need for further research on children who consume fish from this region.