Solubility measurements in pure and modified water serve as a basis for optimizing the subcritical water extraction of target analytes such as food contaminants. The solvent strength of the water is affected by both the system's temperature and the amount and type of cosolvent modifier that is added to the water, which causes a reduction in the dielectric constant of water. In the present work, the solubilities of the triazine pesticides atrazine, cyanazine, and simazine were measured in pure and modified water at temperatures ranging from 50 to 125 degrees C and at a pressure of 50 atm. The solubility data were obtained using a static solubility apparatus with on-line liquid chromatographic (LC) detection. By increasing the temperature of the water, the solubilities of the triazine pesticides increased approximately 3-fold in pure water for each 25 degrees C temperature increment. Cyanazine was 5 times more soluble than atrazine and an order of magnitude more soluble than simazine at 100 degrees C. The solubility of atrazine was also measured in ambient and hot water modified with ethanol and urea. At 100 degrees C, the solubility of atrazine is doubled when the water is modified with urea, and is increased over an order of magnitude when ethanol is used as modifier. The data, therefore, indicate that adding a cosolvent to water in addition to increasing the system temperature increases the solubilities of triazine pesticides in subcritical water. It was further determined that the solutes do not thermally degrade or hydrolyze at the temperatures reported in this study.

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Partitioning of pentachlorophenol (PCP) between water and CO 2 was investigated to determine the effects of pH and ionic strength on the value of the distribution coefficient, K. Decreasing the pH or increasing the ionic strength increased the value of K. The distribution coefficient was larger than that predicted by considering the extent of hydrolysis of the solute in the aqueous phase. However, impedance measurements suggest that negligible concentrations of ions exist in the CO 2 phase. Together, these two facts suggest that the aqueous phase hydrolysis equilibrium is shifted toward unhydrolyzed solute as PCP partitions to CO 2 . The value of K was smaller than the ratio of solubilities of the solute in the two phases, likely due to the effect of solute composition on the solute activity coefficients in each phase. Partitioning isotherms are also reported for the solutes pentachlorophenol, 2,3,4,5-tetrachlorophenol and 2,4dichlorophenoxyacetic acid at about 40 °C, between about 100 to 270 bar.

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Indigenous Arctic populations experience elevated exposures to many environmental contaminants compared with groups residing in southern Canada. This is largely due to consumption of traditional foods, some of which (ringed seals, beluga whales, narwhals, etc.) have relatively high concentrations of persistent organic pollutants. Models of contaminant fate, transport, and bioaccumulation represent powerful tools to explore this exposure issue, wherein combined models can be used to mechanistically and dynamically describe the entire sequence of events linking chemical emissions into the environment to ultimate contaminant concentrations in indigenous Arctic populations. In this review, various approaches adapted and applied to understanding indigenous Arctic contaminant exposure are explored, including early models describing body burdens in single traditional food species to more recent approaches holistically examining uptake and bioaccumulation in entire food chains. The applications of these models are also discussed, including attempts to (i) identify chemical properties favouring transport to, and bioaccumulation in, the Arctic; (ii) clarify the main determinants of temporal trends observed in indigenous Arctic biomonitoring; (iii) explore the impacts of permanent and temporary dietary transitions on current and future indigenous Arctic contaminant exposures; and (iv) correlate modeled early-life pollutant exposures with measured health impacts. The review demonstrates the effectiveness of mechanistic model approaches in investigating indigenous Arctic contaminant exposure, and confirms their utility in continued improvements to understanding associated risk in this unique population context.

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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.