Environmental manganese exposure in residents living near a ferromanganese refinery in Southeast Ohio: A pilot study

Manganese (Mn) is an essential element, yet is neurotoxic in excess. The majority of Mn research has been conducted on occupationally exposed adults with few studies focused on an environmentally exposed population. Marietta, OH is home to one of the largest airborne Mn emission sources in the United States, a ferromanganese refinery. In preparation for a community-based participatory research study, a preliminary pilot study was initiated to characterize the community's exposure to Mn in ambient air and to evaluate the relationship between biological indices of Mn exposure and genes associated with Mn metabolism in Marietta area residents. Participants in the pilot study were recruited through newspaper advertisement, fliers and direct mailing. Exposure to ambient Mn was estimated using an air pollution dispersion model, AERMOD. A total of 141 residents participated in the pilot study ranging in age from 2 to 81 years. Estimated annual average ambient air Mn concentrations in the study area obtained from AERMOD varied from 0.02 to 2.61μg/m³. Mean blood and hair Mn values were 9.12μg/L (SD 3.90) and 5.80μg/g (SD 6.40μg/g), respectively and were significantly correlated (r=0.30, p<0.01). Blood and hair Mn was significantly associated within families (r=0.27, p=<0.02 and r=0.43, p<0.01), respectively. The relationship between hair Mn and estimated ambient air Mn became significant when genes for iron metabolism were included in linear models. The preliminary ambient air and biological concentrations of Mn found in this population demonstrate the need for further research into potential health effects.