Role of Methylmercury Exposure (from Fish Consumption) on Growth and Neurodevelopment of Children Under 5 Years of Age Living in a Transitioning (Tin-Mining) Area of the Western Amazon, Brazil
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Human occupation of the Amazon region has recently increased, bringing deforestation for agriculture and open-cast mining, activities that cause environmental degradation and pollution. Families of new settlers in mining areas might have a diet less dependent on abundant fish and their children might also be impacted by exposures to mining environments. Therefore, there is compounded interest in assessing young children’s nutritional status and neurobehavioral development with regard to family fish consumption. Anthropometric (z-scores, WHO standards) and neurologic [Gesell developmental scores (GDS)] development in 688 preschool children (1–59 months of age) was studied. Overall, the prevalence of malnutrition [i.e., moderate stunting (≤2 H/A-Z), underweight (≤2 W/A-Z), and wasting (≤2 W/H-Z) were respectively 0.3% (n = 2), 1.6% (n = 11), and 2.5% (n = 17). Children’s mean hair Hg (HHg) concentration was 2.56 μg/g (SD = 1.67); only 14% of children had HHg concentrations lower than 1 μg/g and 1.7% had ≥5 μg/g. The biomarker of fish consumption was weakly but positively correlated with GDS (Spearman r = 0.080; p = 0.035). In the bivariate model, attained W/H-Z scores were not significantly correlated with GDS. A moderate level of GDS deficits (70–84%) was seen in 20% of children. There was significant correlation between family fish consumption and children’s hair Hg (HHg) (Spearman r = 0.1756; p < 0.0001) but no significant correlation between children’s HHg and W/H-Z scores. However, the multivariate model showed that breastfeeding, a fish consumption biomarker (HHg), maternal education, and child’s age were statistically significant associated with specific domains (language and personal-social) of the Gesell scale. In this mining environment, family fish-eating did not affect children’s linear growth, but it showed a positive influence (along with maternal variables) on neurodevelopment. Health hazards attendant on a high prevalence of moderate neurodevelopment delays coexisting with exposure to multiple neurotoxic substances merits further investigation in poor environmental settings of tin-mining areas.
KeywordsFish Consumption Cassiterite MeHg Exposure Vaccination Card Moderate Delay
We thank the mothers who gracefully participated in the study, the “Prefeitura Municipal de Ariquemes,” “Escola Municipal Padre Ângelo Spadari”, and “Cooperativa de Garimpeiros de Santa Cruz LTDA–COOPERSANTA”. We also thank the dedication of Elen Noujain, Rogério Monteiro, José Luiz Lazarini, Jr., and Professor Edina Miazaki for help with the statistical analysis. This work was partly supported by the National Research Council of Brazil-CNPq (CT-HIDRO, project-555516/2006-7; CT-AMAZONIA, project-575573/2008-2).
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