Manganese exposure and the neuropsychological effect on children and adolescents: a review.

OBJECTIVES

Manganese (Mn) is an essential element, but overexposure can have neurotoxic effects.

METHODS

In this article, we review and summarize studies on exposure to Mn and nervous system impairments in children.

RESULTS

We identified 12 original articles published between 1977 and 2007. Overexposure to Mn was suspected to occur through diverse sources: infant milk formula, drinking water, industrial pollution, and mining wastes. The most common bioindicator of exposure to Mn was hair Mn content, but some studies measured Mn in blood, urine, or dentin; one study on prenatal exposure measured Mn content in cord blood. Most studies indicate that higher postnatal exposure to Mn is associated with poorer cognitive functions and hyperactive behavior.

CONCLUSIONS

The limitations of the existing studies are numerous: most were cross-sectional, had a modest sample size, and lacked adjustment for important confounders. Future investigations should be performed on a larger sample size and include a more detailed exposure assessment, addressing multiple sources of exposure such as food, water, and airborne particulates.