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

Figures & data

Table 1. Geometric mean and range of mercury concentrations in James Bay Cree women aged 15–44 and proportion of these women who exceeded Health Canada’s 2010 guidelines for blood and hair mercury concentrations.

	Blood sampling		Hair sampling
	E&H Study non-pregnant women 2002–2009 (N = 516)	MIHP pregnant women 2006–2011 (N = 1374)	E&H Study non-pregnant women 2002–2009 (N = 510)	MIHP pregnant women 2006–2011 (N = 913)
Mean age (y)^a	28.8	25.7	28.7	25.5
Mercury concentration range (minimum, maximum)	0.3, 170.0 nmol/L	0.2, 180.0 nmol/L	0.05, 57.7 nmol/g	0.05, 44.1 nmol/g
Mercury concentration (geomean ± 95% CI)	9.1 (8.2, 10.1) nmol/L	4.4 (4.1, 4.7) nmol/L	1.4 (1.3, 1.6) nmol/g	0.84 (0.77, 0.91) nmol/g
Proportion (% ± 95% CI)
No follow-up required^b	90.1 (87.1, 92.5)	96.1 (94.9, 97.0)	92.0 (89.2, 94.1)	97.5 (96.2, 98.4)
Concern range^c	9.9 (7.5, 12.9)	3.9 (3.0, 5.1)	7.8 (5.7, 10.6)	2.5 (1.6, 3.8)
Action range^d	0	0	0.2 (0.0, 1.2)	0

^aMean mercury concentrations and proportions presented in this table are not age-standardised. ^b<40 nmol/L in blood, <10 nmol/g in hair; ^c40–200 nmol/L in blood, 10–50 nmol/g in hair; and ^d>200 nmol/L in blood, >50 nmol/g in hair.

Table 2. Proportion of hair mercury concentrations above 12.5 nmol/g (2.5 μg/g) in the James Bay Cree of northern Quebec, comparing results from the Nituuchischaayihtitaau Aschii Environment-and-Health Study (2002–2009) and earlier estimates by Dumont et al. [1].

	1993/94^a		2002-2009^b
Sex-Age group (y)	N	Per cent above the LOD of 12.5 nmol/g	N	Per cent above 12.5 nmol/g	Difference in % above 12.5 nmol/g (Bonferroni-adjusted 95% CI) for 1993/94–2002/09
Females
4–14	582	5.3	191	1.0	4.3 (0.8, 7.6)
15–39	850	13.3	455	4.2	9.1 (5.0, 13.2)
≥40	492	66.5	228	40.8	25.7 (15.0, 36.3)
Males
4–14	503	7.6	209	1.0	6.6 (2.7, 10.5)
15–39	742	21.2	241	8.3	12.9 (6.5, 19.3)
≥40	430	71.4	176	43.2	28.2 (16.4, 40.0)

^aDumont et al. [1].

^bNituuchischaayihtitaau Aschii Environment-and-Health Study

Table 3. Fitted means (95% CI) for blood and hair mercury concentrations by categories of increasing fish consumption among non-pregnant Cree women aged 15–44 y in Eeyou Istchee (northern Quebec, Canada).

Monthly frequency of consumption	N	Blood Mercury (R^2adj = 0.34)	N	Hair Mercury (R^2adj = 0.32)
		Fitted geometric mean mercury concentration, nmol/L (95% CI)		Fitted geometric mean mercury concentration, nmol/g (95% CI)
High mercury predatory fish
0 meals per month	212	3.37 (2.86, 3.96)	212	0.53 (0.44, 0.63)
>0 and ≤1 meals	203	6.66 (5.45, 8.12)	202	1.17 (0.95, 1.48)
>1 meals	95	11.57 (8.73, 15.34)	93	2.38 (2.01, 3.66)
Lower mercury fish
0 meals per month	186	3.37 (2.86, 3.96)	187	0.53 (0.44, 0.63)
>0 and ≤1 meals	218	6.48 (5.39, 8.09)	217	0.91 (0.74, 1.17)
>1 meals	107	9.20 (7.08, 12.13)	103	1.10 (0.80, 1.48)

Dumont C, Girard M, Bellavance F, et al. Mercury levels in the Cree population of James Bay, Quebec, from 1988 to 1993/94. Can Med Assoc J. 1998;158(11):1439–9.

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