Biomarkers of poly- and perfluoroalkyl substances (PFAS) in Sub-Arctic and Arctic communities in Canada
Introduction
Polyfluoroalkyl substances and perfluoroalkyl substances (PFAS) are a family of emerging persistent organic pollutants (POPs) used in fabrics, fire extinguishers, cookware, and food packaging due to their water and oil resistant properties (Buck et al., 2011; Corsini et al., 2014). The two most-studied PFAS, perfluorooctane sulphonic acid (PFOS) and perfluorooctanoic acid (PFOA), have been phased out of production in the United States due to its persistence in the environment, ability to biomagnify in food chains, and concerns for adverse effects in human populations (Corsini et al., 2014; Webster, 2010). These issues led to the global ban of PFOS as part of the Stockholm Convention on POPs, and the consideration of PFOA and perfluorohexane sulphonic acid (PFHxS) for addition to the convention (Sunderland et al., 2019; UNEP, 2019).
The primary exposure pathways for PFAS in humans are typically through inhalation of indoor and outdoor air, ingestion of contaminated drinking water and food, and skin contact with contaminated media (Rappazzo et al., 2017; Sunderland et al., 2019). These chemicals are not easily metabolized by humans and can have elimination half-lives of three to nine years (Olsen et al., 2007; Webster, 2010). Populations highly exposed to PFAS, in particular PFOA and PFOS, have been found to have higher incidences of dyslipidemia, high cholesterol, thyroid disruption, and other health effects (Sunderland et al., 2019; Webster, 2010). Potential risks from environmental chemicals warrant precautionary environmental policy measures and particular consideration for vulnerable populations, including Indigenous populations (Buekers et al., 2018; Health Canada, 2019b).
In Canada, PFAS have been measured in the general population (via the Canadian Health Measures Survey (CHMS)) and in on-reserve First Nations communities living in more southern regions of Canada (via the First Nations Biomonitoring Initiative) (Assembly of First Nations, 2013; Health Canada, 2019a). In southern Canada, levels of PFHxS, PFOS, and PFOA appear to be declining in human plasma concentrations since monitoring began in 2007 (Health Canada, 2019a). However, PFAS concentrations have been increasing across the Canadian Arctic during this time, as demonstrated by levels in ringed seals and in the Devon Ice Cap (Butt et al., 2010; Muir et al., 2019; Zhao et al., 2012). These increases have been attributed to long-range transport of PFAS through the atmosphere and ocean, which has resulted in biomagnification of PFAS in traditional food sources (Butt et al., 2010; Muir et al., 2019; Zhao et al., 2012). It is not yet known if results from nationally-representative studies are generalizable to sub-Arctic and Arctic First Nations communities, such as those in Northwest Territories and Yukon, where traditional foods are integral for culture, nutrition, and subsistence (Dallaire et al., 2009; Donaldson et al., 2010; Kuhnlein and Chan, 2000; Tittlemier et al., 2004; Wein and Freeman, 1995). Further, prior studies of PFAS exposure in northern communities have focused predominantly on PFOS and PFOA. Relatively little is known regarding exposure levels for other PFAS, such as PFHxS and perfluorononanoic acid (PFNA) (Dallaire et al., 2009; Tittlemier et al., 2004; UNEP, 2019). Documenting PFAS levels in Arctic and sub-Arctic populations is important for informing long-term trends in these locations and for understanding how PFAS levels differ from southern populations.
This paper presents data from biomonitoring projects completed in Dene communities of the Northwest Territories and a Gwich'in community in the Yukon. The primary objective of the research presented herein was to document levels of nine PFAS among participating communities of the Northwest Territories and Yukon. Secondary objectives include comparing PFAS data to those observed from the Canadian general population and other non-northern First Nations communities, and investigating demographic determinants of PFAS exposure.
Section snippets
Study design
The design of the biomonitoring program and methods relating to sample collection have been documented elsewhere (Drysdale et al., 2020; Ratelle et al., 2018a, 2018b). The program was conducted in partnership with local governments and regional leaders, who provided guidance on how the research should best respond to community priorities and concerns. This manuscript reports results from participating communities, including Old Crow, Yukon and K'atl'odeeche, Deh Gah Gotie, Ka'a’gee Tu, Sambaa
Sample and participant characteristics
The mean age for Old Crow participants was 43.9 (95% CI: 39.9–48.3) and the median age was 42.5 (95% CI: 34.0–52.5). Similar mean ages were found in Dehcho participants of 47.3 (95% CI: 44.5–50.2) and a median age of 45.0 (95% CI: 43.0–48.0). Sex distributions from the Dehcho dataset were similar to those reported in the Dehcho census, both reporting similar proportions of males to females (Table 1 and Supplemental Table 1). Likewise, the age categories distribution of the current Dehcho sample
Conclusions
The results in this study provide baseline PFAS data for populations not previously researched in Arctic and sub-Arctic communities of Canada. However due to the cross-sectional design of the current project, more research is needed to establish temporal trends in this region. Future research should also aim to gather more data from demographics that were underrepresented in this project, such as those <20 years of age, to improve representativeness of results and generalizability to other
Declaration of competing interest
The authors report no conflict of interest.
Acknowledgements
The research team is grateful for assistance from the following organizations: the Government of Northwest Territories Department of Health and Social Services (DHSS); 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; the Vuntut Gwitchin First Nation Government (VGG); the Yukon Public Health; Old Crow
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