Human biomonitoring of metals in sub-Arctic Dene communities of the Northwest Territories, Canada
Introduction
Human biomonitoring can support human health risk assessment of contaminants through the measurement of chemicals or their metabolites in biological samples (e.g., blood, urine and/or hair (Hoet and Haufroid, 1997). Biomonitoring provides information on the exposure to a chemical from all sources and routes of exposure (CDC, 2005). Several national biomonitoring initiatives are ongoing including studies such as the National Health and Nutrition Examination Survey (NHANES) in the United States, the European Human Biomonitoring Initiative (HBM4EU), the German Environmental Survey (GerES), and Biosurveillance (HBM) in France. In Canada, several surveys have included nationally-representative human biomonitoring, including the Canadian Health Measures Survey (CHMS) and the Maternal-Infant Research on Environmental Chemicals Study (MIREC) (Ashley-Martin et al., 2019; Health Canada, 2010, 2013; 2015, 2017; 2019). These biomonitoring projects are useful to determine baseline levels of chemicals in the general population, assess temporal trends and identify priorities to protect public health.
Due to their ubiquity and potential adverse effects, several metals and trace elements (e.g., lead, mercury, arsenic, and cadmium) are generally included in population biomonitoring projects. People can be exposed to these metal (loid)s through multiple pathways, including the consumption of contaminated food or water, the ingestion of house dust, as well as the inhalation of indoor and outdoor air and cigarette smoke (Jaishankar et al., 2014). The integration of traditional foods in the diets of First Nations, Métis and Inuit populations in Canada is linked to improved food security (Rosol et al., 2016), but can also lead to higher contaminant exposure (Bordeleau et al., 2016). For example, the use of lead shot in hunting can lead to elevated lead exposures among Indigenous populations (Liberda et al., 2018), and long-range transport contributes to mercury bioaccumulation in fish consumed in Northern Canada (Chetelat et al., 2015).
In the Northwest Territories, Dene communities still rely on traditional foods (e.g., moose, caribou, fish). However, after elevated levels of mercury and cadmium were reported in some wildlife in the region, communities repeatedly expressed concerns regarding potential exposures to environmental contaminants. In the Dehcho and Sahtú regions, site-specific consumption notices were released by the Government of the Northwest Territories for predatory fish species from specific lakes due to elevated mercury levels (NWT, 2020a). Also, consumption notices were released for the liver and kidneys of moose harvested in the southern Mackenzie Mountains due to elevated cadmium levels (NWT, 2020b).
The Indigenous populations of Canada often face inequities, structural racism within political systems, and less access to the healthcare system and social services (Gee and Ford, 2011; Greenwood et al., 2018; Reading, 2015). These groups also deal with additional environmental challenges, caused partially by a closer proximity to natural resource developments which can introduce point source exposure pathways (Hoover et al., 2012). As such, Indigenous populations may be both exposed to elevated levels of contaminants (including but not limited to metals) and face structural challenges to redressing these issues.
Biomonitoring projects with Indigenous populations in Canada are essential to assess the exposure of these potentially-vulnerable populations. The ongoing nationally-representative biomonitoring studies in Canada (i.e., CHMS) (Health Canada, 2010, 2013; 2015, 2017; 2019), do not include participants from the three Canadian Territories (i.e., Nunavut, Northwest Territories, Yukon) or First Nations reserves across the ten provinces. As such, additional biomonitoring research initiatives have sought to fill this gap. These have included the Inuit Health Survey (Saudny et al., 2012) and First Nations Biomonitoring Initiative (FNBI). However, neither of these projects recruited participants from First Nations communities of the Northwest Territories. The FNBI and other human biomonitoring projects have indicated that, relative to the CHMS, First Nations and Inuit may experience higher levels of particular contaminants, including cadmium, lead, mercury, copper and polycyclic aromatic compounds (AFN, 2013; Fontaine et al., 2008; Ratelle et al., 2018b, 2020). These observations may relate to several factors, including demographic variables, genetic factors, smoking rates and the consumption of particular fish, marine mammal, and wild game species (Clarkson, 2002, Liberda et al., 2008).
To address concerns about contaminant exposure in the region, the nine communities across the Dehcho and Sahtú Regions of the Northwest Territories partnered with environmental health scientists to assess contaminant exposure through biomonitoring. This human contaminant biomonitoring study, funded by the Northern Contaminants Program (NCP), was implemented in 2016–2018 in participating Dene communities in the Mackenzie Valley, Northwest Territories (Ratelle et al., 2018a). The biomonitoring project provided additional baseline exposure data to facilitate assessment of temporal changes related to the ongoing dietary transition, global climate change, and natural resource development. This document reports the metal biomonitoring data from nine Dene communities located in the Dehcho and Sahtú regions of the Northwest Territories.
Section snippets
Design of the project
As described elsewhere (Ratelle et al., 2018a, 2018b), a series of consultations were conducted in Sahtú and Dehcho Regions to inform the creation of Community Research Agreements (CRA) for communities interested in participating in the project. Local research coordinators were hired in each community to facilitate participant recruitment and implementation of the project. In communities with more than 100 residents, a random selection was done to actively recruit potential participants. Across
Participation
Participants were recruited from 9 communities in the Dehcho and Sahtú regions for the biomonitoring project completed during winter months of 2016–2018 (i.e., January 2016, November 2016–January 2017, November 2017–March 2018). A total of 533 residents from these communities agreed to take part in the project. Among participating communities, participation rates ranged between 12% and 40%. This represents 8.9% of the residents at the Dehcho and Sahtú level (n = 6018). In total, 89 of the
Data comparison with the literature
As observed in the current study, some of the metals in blood and urine were elevated compared to levels from other representative surveys (i.e., CHMS and FBNI). With elevated levels at the GM and P95 for each of the three units of measurements of biological levels (e.g., blood, urine, and creatinine-adjusted urine levels), this was most notably the case for Pb. Moreover, for Pb biomarkers, the magnitude of these differences between Mackenzie Valley results and the CHMS and/or FNBI tended to be
Conclusion
The levels of most metals in the Sahtú and Dehcho regions of the Northwest Territories were generally similar to the levels seen in other biomonitoring studies in Canada. The key exceptions to this were: lead and, to a lesser extent, mercury (both of which appeared elevated compared to the available national data). Notably though, the majority of participants had levels that fell below the health-based guidance values established for these metals. Other metals of potential interest and priority
Sources of financial support
Funding for this work was provided by the Northern Contaminants Program (NCP) (Crown Indigenous Relations and Northern Affairs Canada). Additional support was received from the Natural Sciences and Engineering Research Council of Canada (NSERC), Global Water Futures (GWF), the Northern Scientific Training Program (NSTP), the Canada Research Chair in Nutritional Lipidomics, the University of Waterloo, and the Population Biomonitoring Section of Health Canada.
Ethics approval and consent to participate
All participants provided a free informed written consent. The work described has been carried out in accordance with The Code of Ethics of the World Medical Association (Declaration of Helsinki). The privacy rights of human participants were paramount. Ethics approval was obtained by the University of Waterloo Research Ethics Committee (#20173, #20950), the Stanton Territorial Health Authority for Human Research (29/12/2015), and the Aurora Research Institute (#15560, #15775, #15966, #15977,
Availability of data and material
The current manuscript reports aggregate data. In respect to the research and disclosure agreements with communities and to respect the anonymity of participants from small communities, the researchers will not share any individual and community-level results.
Credit author statement
M.Ratelle wrote the paper and was in charge of the project management, B. Laird designed the concept of the project and was in charge of the funding acquisition, M.Ratelle and B.Laird conceptualized and implemented the methodology of the study. M.Bouchard, S. Majowicz developed analytical methods and tools. The graduate student S.Packull-McCormick provided technical support during the project. All the authors contributed with ideas and comments, and reviewed of the paper. All authors read and
Declaration of competing interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgements
The research team is grateful for assistance from the following organizations: The Government of Northwest Territories Department of Health and Social Services; the Dehcho Aboriginal Aquatic Resources and Ocean Management (AAROM); the Dehcho First Nations (DFN), the Sahtú Renewable Resources Board (SRRB); the Sahtú Secretariat Incorporated (SSI); the Northwest Territories Regional Contaminants Committee (NT RCC); the Sahtú Health and Social Service Authority (SHSSA); the Dehcho Health and
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