Assessing determinants of maternal blood concentrations for persistent organic pollutants and metals in the eastern and western Canadian Arctic.

Aboriginal peoples in the Canadian Arctic are exposed to persistent organic pollutants (POPs) and metals mainly through their consumption of a traditional diet of wildlife items. Recent studies indicate that many human chemical levels have decreased in the north, likely due to a combination of reduced global chemical emissions, dietary shifts, and risk mitigation efforts by local health authorities. Body burdens for chemicals in mothers can be further offset by breastfeeding, parity, and other maternal characteristics. We have assessed the impact of several dietary and maternal covariates following a decade of awareness of the contaminant issue in northern Canada, by performing multiple stepwise linear regression analyses from blood concentrations and demographic variables for 176 mothers recruited from Nunavut and the Northwest Territories during the period 2005-2007. A significant aboriginal group effect was observed for the modeled chemicals, except for lead and cadmium, after adjusting for covariates. Further, blood concentrations for POPs and metals were significantly associated with at least one covariate of older age, fewer months spent breastfeeding, more frequent eating of traditional foods, or smoking during pregnancy. Cadmium had the highest explained variance (72.5%) from just two significant covariates (current smoking status and parity). Although Inuit participants from the Northwest Territories consumed more traditional foods in general, Inuit participants from coastal communities in Nunavut continued to demonstrate higher adjusted blood concentrations for POPs and metals examined here. While this is due in part to a higher prevalence of marine mammals in the eastern Arctic diet, it is possible that other aboriginal group effects unrelated to diet may also contribute to elevated chemical body burdens in Canadian Arctic populations.

Comparing plasma concentrations of persistent organic pollutants and metals in primiparous women from northern and southern Canada.

The exposure of Aboriginal peoples in the Canadian Arctic to persistent organic pollutants (POPs) and metals through the consumption of traditional food items is well recognized; however, less information is available for Canadian immigrants. The direct comparison of blood chemical concentrations for expectant primiparous women sampled in the Inuvik and Baffin regions of the Canadian Arctic, as well as Canadian- and foreign-born women from five southern Canadian centers (Halifax, Vancouver, Hamilton, Ottawa, and Calgary), provides relative exposure information for samples of northern and southern mothers in Canada. Based on our analyses, Canadian mothers are exposed to a similar suite of contaminants; however, Inuit first birth mothers residing in the Canadian Arctic had higher age-adjusted geometric mean concentrations for several legacy POPs regulated under the Stockholm Convention, along with lead and total mercury. Significant differences in exposure were observed for Inuit mothers from Baffin who tended to demonstrate higher blood concentrations of POPs and total mercury compared with Inuit mothers from Inuvik. Conversely, northern mothers showed a significantly lower age-adjusted geometric mean concentration for a polybrominated diphenyl ether (PBDE-153) compared to southern mothers. Furthermore, southern Canadian mothers born outside of Canada showed the highest individual concentrations measured in the study: 1700 µg/kg lipids for p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE) and 990 µg/kg lipids for ß-hexachlorocyclohexane (ß-HCH). Data from Cycle 1 (2007-2009) of the nationally-representative Canadian Health Measures Survey (CHMS) places these results in a national biomonitoring context and affirms that foreign-born women of child-bearing age experience higher exposures to many POPs and metals than their Canadian-born counterparts in the general population.