Cognitive control dysfunction in workers exposed to manganese-containing welding fume

Background: Chronic exposure to manganese (Mn) is a health concern in occupations such as welding because of well-established motor effects due to basal ganglia dysfunction. We hypothesized that cognitive control (the ability to monitor, manipulate, and regulate ongoing cognitive demands) would also be affected by chronic Mn exposure. Methods: We examined the relationship between Mn exposure and cognitive control performance in 95 workers with varying intensity and duration (median 15.5 years) of exposure to welding fume. We performed linear regression to assess the association between exposure to Mn-containing welding fume and cognitive control tasks. Results: Overall performance was inversely related to intensity of welding exposure (P = 0.009) and was driven by the Two-Back and Letter Number Sequencing tests that assess working memory (both P = 0.02). Conclusions: Occupational exposure to Mn-containing welding fume may be associated with poorer working memory performance, and workers may benefit from practices that reduce exposure intensity. Am. J. Ind. Med. 60:181–188, 2017.