Elevated manganese and cognitive performance in school-aged children and their mothers

Abstract

Background Growing evidence suggests that excess manganese (Mn) in children is associated with neurobehavioral impairments. In Brazil, elevated hair Mn concentrations were reported in children living near a ferro-manganese alloy plant. Objectives We investigated these children’s and caregivers’ cognitive function in relation to bioindicators of Mn exposure. Methods In this cross-sectional study, the WISC-III was administered to 83 children aged between 6 and 12 years; the Raven Progressive Matrix was administered to the primary caregivers (94% mothers), who likewise responded to a questionnaire on socio demographics and birth history. Mn in hair (MnH) and blood (MnB) and blood lead (PbB) were measured by graphite furnace atomic absorption spectrometry (GFAAS). Results Children’s mean MnB and MnH were 8.2 µg/L (2.7 – 23.4) and 5.83 µg/g (0.1 −86.68), respectively. Mean maternal MnH was 3.50 µg/g (0.10 – 77.45) and correlated to children’s MnH (rho=0.294, p=0.010). Children’s MnH was negatively related to Full-Scale Intelligence Quotient (IQ) and Verbal IQ; β coefficients for MnH were −5.78 (95% CI −10.71 to −0.21) and −6.72 (−11.81 to −0.63), adjusted for maternal education and nutritional status. Maternal MnH was negatively associated with performance on the Raven’s (β = −2.69, 95% CI −5.43 to 0.05), adjusted for education years, family income and age. Conclusions These findings confirm that high MnH in children is associated with poorer cognitive performance, especially in the verbal domain. Primary caregiver’s IQ is likewise associated to Mn exposure, suggesting that, in this situation, children’s cognition may be affected directly and indirectly by Mn exposure.

Hair Manganese as an Exposure Biomarker among Welders

“…Hair samples were prepared similarly to our study and washed with a Triton X-100 solution. The authors reported an increase of MnH with time of mother's exposure before child birth and a decrease of MnH with increasing distance to plant (Menezes-Filho et al, 2011).…”

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.…”

The Role of Heavy Metal Pollution in Neurobehavioral Disorders: a Focus on Autism

“…Though Mn cannot be considered an environmental pollutant, numerous evidence suggests the potential association between Mn exposure and intellectual impairment in school-aged children, who showed Prenatal cadmium exposure IQ deficits (4.5 years of age) Tian et al (2009) IQ deficits (5 years of age) Kippler et al (2012a) Postnatal cadmium exposure No significant effects on neurodevelopmental scores (2, 5, and 7 years of age) Cao et al (2009) Learning impairment (6-15 years of age) Ciesielski et al (2012);Yousef et al (2011) Social problems and attention deficits (7-16 years of age) Bao et al (2009) deficits in IQ and verbal domain (Bouchard et al 2007: Claus Henn et al 2010Bouchard et al 2011;Menezes-Filho et al 2011). Manganese exposure is further associated with an increased risk of behavioral disorders, including ADHD (Farias et al 2010;Yousef et al 2011).…”