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 Itapuã (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 (150 μg) than in infants from either village (41.67 μg, Itapuã; 42.39 μg, 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 Itapuã (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.

Thimerosal Exposure and the Role of Sulfation Chemistry and Thiol Availability in Autism

“…These findings are in accordance with findings by Dórea et al [101,102]. Dórea et al [101] examined Et- and Me-Hg in hair samples of breastfed infants who had received the recommended schedule of TM-containing vaccines.…”

“…They found a statistically significant inverse association between hair-Et-Hg concentrations and the time elapsed since the administration of the last TM-containing vaccine. Then, in 2012, they found that neurological development at six months was negatively associated with exposure to additional TM [102]. However, there were no developmental differences noted at 36 months.…”

Methylmercury exposure increases lipocalin related (lpr) and decreases activated in blocked unfolded protein response (abu) genes and specific miRNAs in Caenorhabditis elegans

“…While the developing fetus is highly sensitive, in adult humans, MeHg poisoning can cause loss of physical coordination, abnormal speech, neuropathology, and death (Harada, 1968; Harada, 1978; Eto, 1997). Despite over 50 years of experience with human disasters, MeHg exposure remains a serious human health threat and its consequences continue to be intensely studied (Dórea et al, 2012; Aslan et al, 2013). …”

Cross-sectional assessment of infants’ exposure to toxic metals through breast milk in a prospective cohort study of mining communities in Ghana

“…The exposures to toxic metals have significant public health implication, even at small concentrations and acute exposures, these metals remain toxic to humans. For infants in particular, these exposures may have adverse effect on the developing central nervous system [5–8], leaving a life-long defect on their cognitive abilities.…”