Manganese exposure: cognitive, motor and behavioral effects on children: a review of recent findings

Manganese (Mn) is an essential element, but can be neurotoxic when exceeding the homeostatic range. We reviewed the most recent human studies (from January 2011 to July 2012) regarding the association between Mn exposure and cognitive, motor and behavioral effects on children.

A total of 10 articles were located; data were collected from five different countries. Six studies showed adverse effect of Mn on cognitive function. The most adopted cognitive test was the Wechsler Intelligence Scale for Children (WISC) or some subtests from it and results suggest an inverse association of higher Mn exposure with lower intellligence quotient. Three studies focused on motor effects of Mn; two of them found a direct association of higher Mn exposure with increased motor impairment. Two studies assessed Mn impact on behavior; one of them showed a correlation between higher Mn in water and both internalizing and externalizing behavioral scores. Potential limitations of these studies included the lack of validated biomarkers and the lack of consideration of mixed co-exposure with other neurotoxic agents.

Despite some potential limitations of the reviewed studies, the adverse effects of manganese exposure on the developing brain is well demonstrated and preventive strategies should be promoted.