|Abstract Title:||Mercury and arsenic in Canadian freshwater fish and the potential protection of selenium for consumers|
|Presenter Name:||Dominic Ponton|
|Company/Institution:||Universit de Montral|
|Session:||Special Session - Selenium-mercury interactions in aquatic food webs: The state of the science and future research directions|
Abstract Information :
Mercury (Hg) and arsenic (As) contamination of fish may be toxic and limit its safe human consumption, whereas selenium (Se) can potentially protect fish and consumers from Hg and As adverse effects. We assembled data from Canadian freshwater fish flesh of the above-mentioned elements to link their concentrations to anthropogenic activities and ecozones and compare them with risk assessment thresholds. Mercury concentrations exceeded the retail fish Canadian threshold (0.5 æg/g wet weight) in 31% of all Walleye; this proportion rose to 64% in reservoirs. Reservoirs and lakes impacted by logging and urbanization presented higher fish [Hg] than other impacted systems. Se and As concentrations exceeded Canadian guidelines in 5% and 0.2% of all fish, respectively. In mining areas, fish [Hg] were low and negatively correlated with [Se], and fish [Se] were positively correlated with [As]. Apart from these correlations seen in mining areas, we observed an overall important and a previously unpublished negative relationship between mean fish [As] and [Hg], suggesting an inverse consumption risk for these two elements. The ratio Se/Hg was lower than the protective value of 1 for 14% of all fish and was negatively correlated with fish length. On the other hand, using the benefit-risk value (BRV) threshold that considers the protective properties of Se intake from other food products and its potential binding to Hg, there was no limit to fish consumption. More studies are needed to assess the role of Se against Hg toxicity and adjust fish consumption guidelines accordingly.