Table 1:

Blood mercury concentrations in select Canadian surveys of women of child-bearing age and children

Study	Design	Sampling period	Population	% with blood Hg concentration above guidance value (8 μg/L)
Nunavik Health Survey16	Representative survey	2004	Inuit women aged 18–39 yr in Nunavik (northern Quebec)	53.3
NCDS8	Birth cohort	2005–10	Inuit school-aged children in Nunavik	16.9*
Canadian Health Measures Survey17	Representative survey†	2007–09	Women aged 16–49 yr; Canada-wide study	2.2
				Geometric mean‡ ± SD or (95% CI) for blood Hg concentration, μg/L
NCDS8	Birth cohort	1995–01	Pregnant Inuit women from Hudson Bay, Nunavik§	10.4 ± 0.4
Maternal biomonitoring study18	Convenience sample	2005–07	Pregnant Inuit women in Baffin region	4.0 (3.4–4.7)
			Pregnant Inuit women in Inuvik	1.1 (0.85–1.5)
			Pregnant Dene and Metis women in Inuvik	0.70 (0.45–1.1)
Canadian Health Measures Survey17	Representative survey	2007–09	Women aged 16–49 yr; Canada-wide study	0.72 (0.50–0.94)
MIREC study19	Birth cohort	2008–11	Pregnant women in 10 Canadian urban regions	0.86 ± 2.84

Note: CI = confidence interval, Hg = mercury, MIREC = Maternal–Infant Research on Environmental Chemicals study, NCDS = Nunavik Child Development Study, SD = standard deviation.

^*Not published; proportion calculated directly from the NCDS mercury results.

^†The study does not obtain samples from Canadians residing on Crown land, in Indian reserves or in remote regions, such as northern Quebec.

^‡Distributions of environmental concentrations are often skewed to the right and log-normally distributed. Consequently, many studies use geometric means to estimate central tendency, although this measure may be biased low.

^§The contemporary NCDS contains more than 1 birth cohort. These estimates come from one of the cohorts, and the sample comprises pregnant women recruited from the 3 largest communities in the Hudson Bay region of Nunavik.