Neuropsychological Effects of Mercury Exposure in Children and Adolescents of the Amazon Region, Brazil

An Assessment of Health Outcomes and Methylmercury Exposure in Munduruku Indigenous Women of Childbearing Age and Their Children under 2 Years Old

“…Median H-Hg levels (3.80 µg/g) found amongst Munduruku infants reflect those found in other regions of the Amazon [ 41 , 43 , 85 , 86 , 87 ]. Santos Lima et al [ 41 ] reported an association between MeHg exposure and lower performance in neuropsychological tests for children and adolescents, with each 10 μg/g increase of hair Hg corresponding to poorer performance by half a standard deviation. In this study, three infants failed the Denver II Developmental Screening Test, two on Language and one on Gross-Motor Skills, all these infants have high levels of H-Hg.…”

“…It is important to emphasize that neurotoxic effects related to methylmercury exposure are most serious during the prenatal period, since the fetal brain is particularly sensitive to the action of any neurotoxic substances [ 38 , 39 , 40 , 41 ]. When methylmercury contaminated fish is consumed, this mercurial form is almost completely absorbed by the gastrointestinal tract and rapidly circulates throughout the body, ultimately reaching its principal target, the central nervous system.…”

“…In pregnant women, this toxicokinetic pattern is repeated, with methylmercury then crossing the placental barrier and entering the fetal circulatory system [ 38 , 39 , 40 ]. Some studies indicate that cord blood corresponds to maternal blood at a ratio of 1.7, leaving the developing nervous system exposed to amplified neurotoxic effects [ 40 , 41 , 42 ]. Exposure to a neurotoxin at such a critical period of development has been shown to lead to physical and mental developmental delay, altered muscle tone and reduced neurological test scores, even after exposure to levels of methylmercury that had little effect on the mother [ 38 , 39 , 40 , 41 , 42 ].…”

“…Some studies indicate that cord blood corresponds to maternal blood at a ratio of 1.7, leaving the developing nervous system exposed to amplified neurotoxic effects [ 40 , 41 , 42 ]. Exposure to a neurotoxin at such a critical period of development has been shown to lead to physical and mental developmental delay, altered muscle tone and reduced neurological test scores, even after exposure to levels of methylmercury that had little effect on the mother [ 38 , 39 , 40 , 41 , 42 ]. Mercury exposed infants specifically have been found to have reduced cognitive abilities [ 43 ].…”

Associations of Metabolic Genes (GSTT1, GSTP1, GSTM1) and Blood Mercury Concentrations Differ in Jamaican Children with and without Autism Spectrum Disorder

“…Therefore, continuous exposure to Hg is very likely in the Jamaican community via fish consumption. On the other hand, dietary intake of seafood and fish is the main source of omega-3 polyunsaturated fatty acids (PUFA) in humans that play an important role in human health [93], brain development [94] and cognitive performance [95][96][97]. Since our study design is matched case-control and the measurement of exposure to the six metals including mercury took place at the time when the children were evaluated to confirm their ASD status at age 2-8 years, we are unable to establish temporality of the associations we reported in this study.…”