Intellectual Function in Mexican Children Living in a Mining Area and Environmentally Exposed to Manganese

Abstract

BackgroundExcessive exposure to manganese (Mn), an essential trace element, has been shown to be neurotoxic, especially when inhaled. Few studies have examined potential effects of Mn on cognitive functions of environmentally exposed children.ObjectiveThis study was intended to estimate environmental exposure to Mn resulting from mining and processing and to explore its association with intellectual function of school-age children.MethodsChildren between 7 and 11 years of age from the Molango mining district in central Mexico (n = 79) and communities with similar socioeconomic conditions that were outside the mining district (n = 93) participated in the cross-sectional evaluation. The revised version of the Wechsler Intelligence Scale for Children adapted for the Mexican population was applied. Concentrations of Mn in blood (MnB) and hair (MnH) were used as biomarkers of exposure.ResultsExposed children had significantly higher median values for MnH (12.6 μg/g) and MnB (9.5 μg/L) than did nonexposed children (0.6 μg/g and 8.0 μg/L, respectively). MnH was inversely associated with Verbal IQ [β = −0.29; 95% confidence interval (CI), −0.51 to −0.08], Performance IQ (β = −0.08; 95% CI, −0.32 to 0.16), and Total Scale IQ (β = −0.20; 95% CI, −0.42 to 0.02). MnB was inversely but nonsignificantly associated with Total and Verbal IQ score. Age and sex significantly modified associations of MnH, with the strongest inverse associations in young girls and little evidence of associations in boys at any age. Associations with MnB did not appear to be modified by sex but appeared to be limited to younger study participants.ConclusionsThe findings from this study suggest that airborne Mn environmental exposure is inversely associated with intellectual function in young school-age children.

Prenatal exposure to manganese in South African coastal communities

“…Similar studies have shown that drinking water containing much lower concentrations of Mn than those found in Bangladesh also caused intellectual impairment in school children 26 . The environmental exposure to Mn from industrial and mining sources, and negative cognitive performance of children were also reported 27,28 . While these studies report deficits in children, the contribution of pre-natal exposure to excess Mn is unknown.…”

Advances in Manganese Pollution and Its Bioremediation

“…The waste batteries cause a serious concern due to their toxicity, abundance, and permanence in the environment. Inhabitants living close to mining extraction sites (Riojas-Rodríguez et al 2010) and alloy industries (Menezes-Filho et al 2009) are at threat of extreme Mn exposure. Research investigations on ecological exposure to Mn have effectively applied scalp hair Mn and air Mn as natural and ecological indicator of exposure (Viana et al 2014).…”

La salud ambiental en México: situación actual y perspectivas futuras

“…Las concentraciones más altas de manganeso, se han encontrado en la región minera de Molango en el estado de Hidalgo, con reconocidos efectos sobre la capacidad intelectual en los niños. 43 En otras zonas también se ha encontrado este mineral, incluida la Ciudad de México. 47 La exposición a metales en población infantil es, sin duda, uno de los elementos de la agenda pendiente.…”