Journal
ENVIRONMENT INTERNATIONAL
Volume 149, Issue -, Pages -Publisher
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.envint.2020.106104
Keywords
Lead,Mercury; Arsenic; Cadmium; Co-exposure; Artisanal and small-scale gold mining; Neurodevelopmental impairment
Categories
Funding
- Department of Environmental and Occupation Health at the Catholic University of Health and Allied Sciences, Mwanza, Tanzania
- University of Calgary, Calgary, Canada
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The study found that prenatal exposure to mercury in women in areas with ASGM activities may lead to neurodevelopmental issues in infants, particularly language impairment. Co-exposure to high concentrations of mercury and lead, or mercury and arsenic, seemed to have negative potentiated effects on infants' neurodevelopment.
Background: Artisanal and small-scale gold mining (ASGM) is associated with release of neurotoxic metallic or metalloid chemical elements including lead (Pb), mercury (Hg), cadmium (Cd) and arsenic (As). Objective: To examine associations between prenatal exposure and co-exposure to total lead (T-Pb), total mercury (T-Hg), total cadmium (T-Cd) and total arsenic (T-As) and infant neurodevelopment at 6 to 12 months of age in areas with ASGM activities in Tanzania. Methods: Women in their second trimester of pregnancy who resided in ASGM areas were enrolled from 2015 to 2017 (n = 883). At 6 to 12 months of age, children were assessed with the Malawi Developmental Assessment Tool (MDAT) (n = 439). We measured T-Pb, T-Hg, and T-Cd in maternal dried blood spots and T-As in maternal urines. Poisson regression was used to examine associations between prenatal concentrations of these elements and neurodevelopmental outcomes. Results: Prenatal T-Hg concentration was associated with global neurodevelopment status (aPR 1.03, CI:1.01-1.04; p < 0.001) and language impairment (aPR 1.05, CI:1.03-1.07; p < 0.001) on the MDAT. When prenatal T-Hg and T-As values were at or above the human biomonitoring reference values (>= 95%) of the German Environmental Survey for Human Biomonitoring, that is 0.80 mu g/L and 15 mu g/L, respectively, the prevalence ratio of global neurodevelopmental impairment was two times higher (aPR 2.1, CI:1.0-4.3; p = 0.034). There was a 40% increase in the prevalence ratio of global neurodevelopmental impairment (aPR 1.4, CI:0.90-2.10, p = 0.027), when prenatal T-Hg was at or above the reference value of 0.80 mu g/L and T-Pb was at or above the reference value of 35 mu g/L. When prenatal T-Hg was at or above the reference value of 0.80 mu g/L and T-As was at or above the reference value of 15 mu g/L, the prevalence ratio of global neurodevelopmental impairment was two times higher (aPR 2.1, CI:1.0-4.3; p < 0.034). Discussion: Infants born to women in areas with ASGM activities are at significant risk for neurodevelopmental impairment and this is associated with exposure to higher concentrations of Hg prenatally. Co-exposure to high concentrations of Hg and Pb, or Hg and As appeared to have negative potentiated effects on infants' neurodevelopment.
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