Neurodevelopment of Amazonian infants: Antenatal and postnatal exposure to methyl- and ethylmercury

Abstract

Neurodevelopment as Gesell development scores (GDSs) in relation to mercury exposure in infants (<6 months of age) of one urban center and two rural villages, respectively, of fisherman and cassiterite miners. Mean total hair-Hg (HHg) concentrations of infants from Itapu (3.95±1.8 ppm) were statistically (P=0.0001) different from those of infants from Porto Velho (3.84±5.5 ppm) and Bom Futuro (1.85±0.9 ppm). Differences in vaccine coverage among these populations resulted in significantly higher (P=0.0001) mean ethylmercury (EtHg) exposure in urban infants (150g) than in infants from either village (41.67g, Itapu; 42.39g, Bom Futuro). There was an inverse significant (Spearman r=-0.2300; P=0.0376) correlation between HHg and GDS for infants from Porto Velho, but not for the rural infants from Bom Futuro (Spearman r=0.1336; P=0.0862) and Itapu (Spearman r=0.1666; P=0.5182). Logistic regression applied to variables above or below the median GDS showed that EtHg exposure (estimated probability=-0.0157; P=0.0070) and breastfeeding score (estimated probability=-0.0066; P=0.0536) score were significantly associated with GDS. Conclusion. In nurslings whose mothers are exposed to different levels of fish-MeHg (HHg), a higher score of neurological development at six months was negatively associated with exposure to additional TCV-EtHg. Results should be interpreted with caution because of unaccounted variables. Copyright © 2012 José G. Drea et al.