Environmental manganese exposure and associations with memory, executive functions, and hyperactivity in Brazilian children

Abstract

Manganese (Mn) is an essential element, however high levels of Mn have been associated with lower neuropsychological performance and behavioral problems in children. We investigated the associations between hair Mn concentrations and neuropsychological and behavioral performances among children with long-term exposure to airborne Mn aged between 7 and 12 years. Neuropsychological performance included tests of: verbal memory, inhibitory control, cognitive flexibility, verbal fluency, and motor function. We used the Conners Abbreviated Rating Scale for teachers to assess students' behaviors of hyperactivity. Hair manganese (MnH) concentrations in children and exposure to airborne manganese from a ferro-manganese alloy plant were analyzed and correlated with tests scores. Multivariable linear models adjusting for potential confounders showed that elevated levels of MnH were associated with lower performance in verbal memory, as measured by the free recall after interference (β = - 1.8; 95% CI: - 3.4, - 0.2), which indicates susceptibility to interference, and Delayed Effect (β = -2.0; 95% CI: -3.7, - 0.2), representing a loss of information over time. Additionally, we found patterns of effect modification by sex in three subtests measuring verbal memory: the free recall after interference score, Interference Effect, and Delayed Effect (all at p < 0.10). Overall, the results suggest that long-term airborne Mn exposure may be associated with lower performance in verbal memory, and hyperactivity behaviors.

Evaluation of intestinal histological damage in zebrafish exposed to environmentally relevant concentrations of manganese

“…Manganese, an example of these substances, is a natural element, essential for diverse physiologic processes, including metabolism of amino acids, lipids, proteins and carbohydrates (ERIKSON et al, 2005), immunologic system, regulation of cell energy, growth of the bone and connective tissue, blood clotting (ERIKSON and ASCHNER, 2003), and for some enzymes related to the synthesis and metabolism of neurotransmitters (GOLUB et al, 2005). However, at high concentrations or prolonged exposure periods, it shows toxicity for different organs in a wide spectrum of animals (ZHANG et al, 2003;ALTENHOFEN et al, 2017;CARVALHO et al, 2018). Its occurrence in aquatic environments may be caused by anthropogenic activities as well, especially in regions near to the industries responsible for the manufacture of iron and steel, use of fertilizers, fungicides and animal supplementation (PATIL et al, 2016).…”

Blood manganese and cognitive and motor skills at age 6-7 in Canadian cohort GESTE

“…Also, at 6-7 years of age the physiological regulation of Mn in the body -reduction of absorption in the intestines and increase excretion by the liver-may be su cient to reduce blood Mn levels and its potential toxic effect (30). Another potential explanation is that our population is not exposed to any Mn-releasing industry as seen in other studies (31,32). The only Mn-releasing industry in the Eastern Townships is a small paper mill plant, that was closed approximately 2 years before our study.…”

“…Studies based on socio-economically disadvantaged populations often show a toxic effect of Mn. These are predominantly people living in poor rural areas in Mexico, Brazil (31,32), and Bangladesh (39). Low socio-economic status can lead to an increasing of malnutrition in the population.…”

Associations of a Metal Mixture Measured in Multiple Biomarkers with IQ: Evidence from Italian Adolescents Living near Ferroalloy Industry

“…Associations of (ln-transformed) Mn, measured either in hair or saliva, with VIQ were linear and negative, suggesting adverse effects on aspects of cognition that involve language comprehension, verbal expression, attention, working memory, and executive function. Although other studies of children 7-12 years of age with industrial airborne Mn exposure did not estimate the association of Mn on VIQ in the context of a metals mixture, they have similarly reported adverse, linear associations between hair Mn and VIQ (Menezes-Filho et al 2011;Riojas-Rodríguez et al 2010;Wright et al 2006) as well as with domains that are influenced by verbal abilities, including verbal learning, memory (Carvalho et al 2018;Torres-Agustín et al 2013;van Wendel de Joode et al 2016;Wright et al 2006), and verbal working memory (Carvalho et al 2014;Haynes et al 2018;van Wendel de Joode et al 2016). These findings are also consistent with some (Bouchard et al 2011;Wasserman et al 2011), but not all (Bouchard et al 2018), pediatric studies of environmental Mn exposure via drinking water and VIQ.…”