Regionally representative hair mercury levels in Canadian First Nations adults living on reserves

The primary objective of this participatory study was to assess the current body burden of mercury among First Nations adults.

The First Nations Food, Nutrition and Environment Study (2008-2018) collected regionally representative data from First Nations adults living on reserves south of the 60^th parallel. Mercury was analyzed in hair as a preferred biomarker for prolonged exposure. Hair samples, a 5 mm bundle cut from the occipital region, were collected from the participants who gave consent and measured for total mercury concentrations using cold vapor atomic fluorescence spectrophotometry.

In total, 3404 First Nations adults living in 92 communities provided hair samples. This represents 52.5% of the respondents to the household surveys. The mean hair mercury concentrations were 0.56 μg/g among all participants and 0.34 μg/g among women of childbearing age (WCBA). There were 64 exceedances of Health Canada's mercury biomonitoring guidelines (44 WCBA, 8 women aged 51+ years, 3 men aged 19-50 years, and 9 men aged 51+ years).

Current mercury exposure no longer presents a significant clinical health risk in most of the First Nations population south of the 60^th parallel across Canada. However, mercury exposure continues to be an ongoing environmental public health concern that requires continued monitoring and assessment. Women of childbearing age (19-50 years) and older individuals living in northern ecozones and Quebec have higher mercury exposures, often exceeding Health Canada's guidelines. Careful risk communication and risk management programs need to focus on northern ecozones and Quebec.