Blood and hair mercury concentrations among Cree First Nations of Eeyou Istchee (Quebec, Canada): time trends, prenatal exposure and links to local fish consumption

ABSTRACT

To describe exposure to methylmercury among Cree, focusing on women of childbearing age, we used data from 2 studies. Multiple regression was employed to examine associations between blood and hair mercury concentrations and consumption of locally harvested fish.

Approximately 9.9% of non-pregnant women aged 15–44 y and 3.9% of pregnant women required follow-up according to Health Canada’s blood mercury guidance value of 40 nmol/L. 8% of hair mercury observations in the non-pregnant women and 2.5% among pregnant women exceeded the equivalent threshold of 10 nmol/g. The geometric mean blood mercury concentration was 12.7 nmol/L in 1,429 persons aged 8 and over, and 17.7 nmol/L in adults aged 18 and older. The proportion of hair mercury concentrations greater than 12.5 nmol/g decreased in all age-sex groups when comparing the 2002–2009 data to published values for 1993–1994. Among women of childbearing age, local fish consumption was associated with increased blood and hair mercury concentrations.

While over 90% of women of childbearing age in this population have acceptable levels of mercury, ongoing intake of mercury suggests that their consumption of fish with known high mercury content be minimised. Reducing consumption of fish known to be high in mercury content needs to be balanced with promoting ongoing connection to Cree culture and land-based activities that are also important determinants of health.

KEYWORDS:

• Methylmercury
• pregnant women
• women of childbearing age
• fish consumption
• exposure assessment

Acknowledgments

The authors acknowledge the key role of Dr Eric Dewailly (Université Laval; deceased, 2014) as a principal investigator in the Environment-and-Health Study. We are grateful to Alan Penn for providing helpful insights and to Jill Torrie for coordinating the research agreement on behalf of the CBHSSJB. We thank Drs Jim Hanley and Kevin Brown for advice on statistics. We also acknowledge the partnership of Leonard J.S. Tsuji (University of Toronto), Ian D. Martin (Data Analysis & Environmental Consulting, Fergus ON) and Eric N. Liberda (Ryerson University) in the Eeyou Istchee study.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplementary Material

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Additional information

Funding

This scientific communication is a report from the Nituuchischaayihtitaau Aschii: Multi-Community Environment-and-Health Study in Eeyou Istchee supported by the Cree people of northern Québec, the Cree First Nations and the Cree Board of Health and Social Services of James Bay (CBHSSJB) through financial contributions from Niskamoon Corporation, Nemaska (QC), Canada.