Environmental exposure to manganese in air: Associations with cognitive functions

Manganese (Mn), an essential element, can be neurotoxic in high doses. This cross-sectional study explored the cognitive function of adults residing in two towns (Marietta and East Liverpool, Ohio, USA) identified as having high levels of environmental airborne Mn from industrial sources.Air-Mn site surface emissions method modeling for total suspended particulate (TSP) ranged from 0.03 to 1.61μg/m³ in Marietta and 0.01-6.32μg/m³ in East Liverpool. A comprehensive screening test battery of cognitive function, including the domains of abstract thinking, attention/concentration, executive function and memory was administered. The mean age of the participants was 56 years (±10.8 years). Participants were mostly female (59.1) and primarily white (94.6%). Significant relationships (p<0.05) were found between Mn exposure and performance on working and visuospatial memory (e.g., Rey-O Immediate β=-0.19, Rey-O Delayed β=-0.16) and verbal skills (e.g., Similarities β=-0.19).Using extensive cognitive testing and computer modeling of 10-plus years of measured air monitoring data, this study suggests that long-term environmental exposure to high levels of air-Mn, the exposure metric of this paper, may result in mild deficits of cognitive function in adult populations.