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.

Future human health research directions for the Canadian Northern Contaminants Program.

Studies conducted in the mid-1980s and early 1990s demonstrated that persistent organic pollutants (POPs) and metals were reaching the Arctic ecosystem at unexpectedly high levels, many of which had no Arctic or Canadian sources. Epidemiological and toxicological studies in Canada and in other countries have found that these contaminants may pose a risk to human health. The objective of this paper is to provide the foundation for the discussion on future northern human health research under the Northern Contaminants Program (NCP) in Canada. This short discussion of human health priorities will help guide a path forward for future northern human health research in Canada to address on-going and new health concerns related to contaminants exposure in the Canadian Arctic.

Maternal and umbilical cord blood levels of mercury, lead, cadmium, and essential trace elements in Arctic Canada.

Maternal and umbilical cord blood levels of mercury (Hg), lead (Pb), cadmium (Cd), and the trace elements copper (Cu), zinc (Zn), and selenium (Se) are reported for Inuit, Dene/Métis, Caucasian, and Other nonaboriginal participants from Arctic Canada. This is the first human tissue monitoring program covering the entire Northwest Territories and Nunavut for multiple contaminants and establishes a baseline upon which future comparisons can be made. Results for chlorinated organic pesticides and PCBs for these participants have been reported elsewhere. Between May 1994 and June 1999, 523 women volunteered to participate by giving their written informed consent, resulting in the collection of 386 maternal blood samples, 407 cord samples, and 351 cord:maternal paired samples. Geometric mean (GM) maternal total mercury (THg) concentrations ranged from 0.87 microg/L (SD = 1.95) in the Caucasian group of participants (n = 134) to 3.51 microg/L (SD = 8.30) in the Inuit group (n = 146). The GM of the Inuit group was 2.6-fold higher than that of the Dene/Métis group (1.35 microg/L, SD = 1.60, n = 92) and significantly higher than those of all other groups (P<0.0001). Of Inuit women participants, 3% (n = 4) were within Health Canada's level of concern range (20-99 microg/L) for methylmercury (MeHg) exposure. Of Inuit and Dene/Métis cord samples, 56% (n = 95) and 5% (n = 4), respectively, exceeded 5.8 microg/L MeHg, the revised US Environmental Protection Agency lower benchmark dose. GM maternal Pb was significantly higher in Dene/Métis (30.9 microg/L or 3.1 microg/dL; SD = 29.1 microg/L) and Inuit (31.6 microg/L, SD = 38.3) participants compared with the Caucasian group (20.6 microg/L, SD = 17.9) (P < 0.0001). Half of all participants were smokers. GM blood Cd in moderate smokers (1-8 cigarettes/day) and in heavy smokers (> 8 cigarettes/day) was 7.4-fold higher and 12.5-fold higher, respectively, than in nonsmokers. The high percentage of smokers among Inuit (77%) and Dene/Métis (48%) participants highlights the need for ongoing public health action directed at tobacco prevention, reduction, and cessation for women of reproductive age. Pb and THg were detected in more than 95% of all cord blood samples, with GMs of 21 microg/L and 2.7 microg/L, respectively, and Cd was detected in 26% of all cord samples, with a GM of 0.08 microg/L. Cord:maternal ratios from paired samples ranged from 0.44 to 4.5 for THg, from 0.5 to 10.3 for MeHg, and 0.1 to 9.0 for Pb. On average, levels of THg, MeHg, and Zn were significantly higher in cord blood than in maternal blood (P < 0.0001), whereas maternal Cd, Pb, Se, and Cu levels were significantly higher than those in cord blood (P < 0.0001). There was no significant relationship between methylmercury and selenium for the range of MeHg exposures in this study. Ongoing monitoring of populations at risk and traditional food species, as well as continued international efforts to reduce anthropogenic sources of mercury, are recommended.

Contaminants in Canadian arctic biota and implications for human health: conclusions and knowledge gaps.

This paper summarizes the major findings of the special issue entitled "Contaminants in Canadian Arctic Biota and Implications for Human Health." The individual papers and reviews in this special issue present a large amount of new information on contaminants in biota primarily from the Canadian arctic as well as from Alaska, Greenland and the European Arctic. Temporal and spatial trends are examined and potential biological effects on wildlife are assessed. The special issue also presents new and updated data on human exposure to and possible health effects of current levels of environmental contaminants in the Canadian Arctic. As part of the assessment of the human health implications, the unique structures and processes that have developed in the Canadian Arctic under the Northern Contaminants Program (NCP) of Indian and Northern Affairs Canada to build partnerships and manage and communicate the benefits and risks associated with contaminant exposure are discussed. Application of this information in international forums to reduce anthropogenic emissions of contaminants to the environment is also discussed.