Assessing Mercury Risks for the Optimization of Nutrient Benefits from Wild-harvested Fish Consumption in the Northwest Territories, Canada

• Main Author: Reyes, Ellen Stephanie
• Format: Master Thesis
• Language: English
• Published: University of Waterloo 2016
• Subjects: Mercury; Omega-3 fatty acids; Selenium; Risk assessment; Probabilistic modelling; Dose reconstruction; Biomonitoring; Aboriginal health; Canada; Dehcho Region; Namaycush Lake; Northwest Territories; Burbot; Catostomus catostomus; Longnose sucker; Lota lota; Subarctic; lota
• Online Access: http://hdl.handle.net/10012/10320

Background: Fish are often rich in essential nutrients, such as omega-3 fatty acids (n-3 FAs) and selenium (Se), and thus can promote health. However, methylmercury (MeHg), a contaminant found in many species in the Canadian subarctic, can pose potential health risks. Fish consumption is important to traditional diets because these foods have nutritional, social, and cultural benefits. Objectives: The objectives for this study are to: 1) determine the concentrations of mercury (Hg), n-3 FAs, and Se in various freshwater fish species harvested from three lakes in the Dehcho Region, Northwest Territories (NWT); 2) evaluate the correlations between nutrient and Hg concentrations; 3) identify which fish species have the highest nutrient levels relative to their Hg content; 4) utilize a probabilistic optimization software (Crystal Ball’s OptQuest) to inform dietary recommendations that mitigate risks of Hg exposure and promote human health from traditional food consumption. Methods: Samples from seven freshwater fish species [Burbot (Lota lota), Cisco (Coregonus artedi), Lake Trout (Salvelinus namaycush), Lake Whitefish (Coregonus clupeaformis), Longnose Sucker (Catostomus catostomus), Northern Pike (Esox Lucius), and Walleye samples (Sander vitreus)] were harvested in August 2013 from Ekali, Sanguez, and Trout Lakes in the NWT. The laboratory analysis for Hg involved freeze drying the tissue muscle samples prior to analysis and quantifying Hg in the samples by a direct mercury analyzer; n-3 FAs levels were determined by a lipid extraction on pulverized fish tissue and measured by a gas chromatograph with a flame ionization detector; and Se levels were determined by a tissue digestion and measured by an inductively coupled plasma mass spectrophotometer. Thereafter, a probabilistic optimization method was assessed using OptQuest, a feature in Crystal Ball (Oracle). Results: The average total Hg (HgT) concentrations varied among fish species according to their trophic guild, from 0.057 mg kg-1 for ...