This study sought to characterize the risk to human health from dietary mercury (Hg) exposure in two Inuit communities, Repulse Bay and lgloolik. Hg exposure was estimated using food frequency questionnaires. Body burden was determined by measuring Hg in hair samples. Estimated average daily Hg exposures for women of child-bearing age were 21.3 mug in Repulse Bay, and 6.0 mug in lgloolik; the general population exposures were 43.1 mug in Repulse Bay and 23.2 mug in lgloolik. Average hair concentrations were 2.1 mg/kg and 2.8 mg/kg in Repulse Bay, 2.1 mg/kg and 6.2 mg/kg in lgloolik for women of child-bearing age and the general population respectively. No participants had concentrations above the "at risk" concentration of 30 mg/kg. Significant correlations were observed between hair Hg concentration and traditional food intake. These results do not necessitate direct intervention, but validate continued monitoring of Hg exposure in Nunavut.

Thesis (Ph.D.) -- McMaster University, 1999. / Includes bibliographical references (leaves 212-219). Also available via World Wide Web.

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The threat of environmental mercury (Hg), particularly methylmercury (MeHg), exposure to the health of humans has been well documented. Thus, it is important to monitor exposure and body burden for public health protection. The first objective of this thesis was to characterize the risk of Hg exposure in two Canadian coastal communities: Grand Marian (n = 91) and St. Andrews/St. Stephen (n = 52), New Brunswick, Canada, using dietary questionnaires and hair analysis. Average Hg intakes and body burden were below the most conservative guidelines. We attributed these results to the low Hg concentrations found in the species commonly consumed: haddock, canned tuna, lobster and pollock (all below 0.2 mg/kg). The analytical method employed to determine Hg in hair, cold vapor atomic absorption (CV-AAS), required a bundle of 100-150 hair strands and involved lengthy chemical digestion procedures which reduce throughput. Direct solid introduction techniques minimize these weaknesses. Our second and third objectives were to evaluate two such methods: (1) combustion, gold amalgamation, atomic absorption spectrometry (C-GA-AAS) and (2) laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) for measuring total Hg in single hair strands. Hair samples with a wide range of Hg exposure were obtained from communities. A 1:1 relationship was observed between C-GA-AAS and the established CV-AAS for analysis of 1-cm hair segments. Additionally, the average relative standard deviation (RSD) of Hg between hair strands within an individual was 6.5 +/- 2.8%, thus justifying the use of a single hair strand for biomonitoring. With a limit of quantification of 0.10 ng of total Hg, a single hair strand with average weight of 0.5 mg and Hg concentrations of 0.2 mg/kg can be measured routinely. Using LA-ICP-MS, we showed that a single laser shot can sample hair material within 50 mum along a single hair strand which is equivalent to less than one day of

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