Determinants of human hair mercury, blood mercury, blood selenium, and plasma omega-3 fatty acid levels within northern Canada

To address community concerns within northern Canada, human biomonitoring projects measured concentrations of environmental contaminants and nutrients in human biological samples from the Dehcho and Sahtú regions of the Northwest Territories and Old Crow, Yukon. Hair and blood samples were analyzed for total mercury, blood was analyzed for selenium, and plasma was analyzed for eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Demographic and dietary characteristics associated with concentrations of these biomarkers, within and between the northern Canadian regions sampled, were assessed. Spearman correlations between biomarker concentrations were calculated, geometric mean biomarker concentrations were compared across strata of participant characteristics (stratified by region), and associations were further examined in multivariable models. Participant age and consumption of at least one species of fish and waterfowl were associated with mercury (adjusted R² = 0.26 for hair mercury) and EPA + DHA (adjusted R² = 0.33) biomarker concentrations in the final models. Region and consumption of several fish species as well as caribou livers and kidneys were associated with blood selenium concentrations in the final model (adjusted R² = 0.32). Mercury and EPA + DHA biomarker concentrations were moderately/strongly correlated across all three regions (r_s = 0.36 to 0.65) while correlations with selenium were inconsistent (r_s = 0.04 to 0.28). These findings provide information on the demographic/dietary factors that may be associated with mercury, selenium, and EPA + DHA biomarker concentrations in the northern study regions and highlight the need to consider the nutritional benefits of traditional foods while seeking to understand and reduce the risks of contaminant exposure.