South African Manganese EnvironmentaL NeuroToxic Effects Research (SMELTER)

Abstract Manganese (Mn) is a well-established neurotoxicant that likely induces neurodegeneration through inflammatory pathways. Millions of people worldwide experience high levels of environmental Mn from point source emissions or associated fugitive dust. In the first five years of the SMELTER (South African

Manganese EnvironmentaL NeuroToxic Effects Research) study, we assembled a cohort of >800 Black African residents, including >700 exposed to Mn emissions from one of the world’s largest Mn smelters in Meyerton, South Africa. We developed and validated study assessment tools in the appropriate South African

languages, measured environmental Mn in Meyerton and a comparable non-exposed reference community (Ethembalethu), examined participants using the Unified Parkinson Disease Rating Scale motor subsection part 3 (UPDRS3), and evaluated participants using targeted cognitive and mood assessments. We demonstrated that Meyerton residents had markedly poorer performance in these outcomes as compared to

Ethembalethu residents. These neurological health effects were associated with concentrations ~100-200 ng/m3 of Mn as particulate matter (PM)