Sara Packull-McCormick, Alicia Cowan, Heidi Swanson, Brian Laird (2022). Mercury Bioaccessibility in Raw and Cooked Tissue from Freshwater Fish Species from the Northwest Territories, Canada. Proceedings of the GWF Annual Open Science Meeting, May 16-18, 2022.

In northern Canada, Indigenous communities rely on locally harvested traditional foods, including fish, which provides them with nutritional, cultural, and social benefits. However, mercury exposure from fish consumption can pose a health risk for populations that consume large amounts of fish or fish with elevated mercury concentrations. The bioaccessiblity of mercury in the tissue of northern Canadian freshwater fish is not yet known. To address this knowledge gap, muscle samples from four commonly consumed freshwater fish species (Lake Trout, Northern Pike, Walleye, and Lake Whitefish) caught from lakes in the Northwest Territories, Canada, were examined. Concentrations and bioaccesibility of total mercury differed significantly among fish species and lakes. Total mercury bioaccessibility for samples run through an in vitro gastro-intestinal digestion model ranged between an average of 56% to 96% for the different fish species and waterbodies. After cooking (pan frying in water), total mercury concentrations were on average 1.5 times higher in the fish muscle tissue. This increase was likely due to moisture loss during the cooking process. However, total mercury bioaccessibility was significantly lower (on average 42% lower) in the cooked samples. Although cooking increased the total mercury concentrations in fish tissue, because the bioaccessibility of total mercury was significantly lower, overall bioaccessible concentrations of total mercury were lower in the cooked samples compared to raw samples. Results from this work provide an important dataset that addresses the gap in the literature regarding total mercury bioaccessibility in northern freshwater fish species. Results also add to the growing literature indicating that mercury bioaccessibility differs by fish species, location, and cooking/preparation method.

First Author: Sara Packull-McCormick, School of Public Health Sciences, University of Waterloo
Additional Authors: Alicia Cowan, School of Public Health Sciences, University of Waterloo; Heidi Swanson, Department of Biology, University of Waterloo; Brian Laird, School of Public Health Sciences, University of Waterloo