Impact/Purpose:

This study will provide data for characterizing the risk for learning, behavioral and clinical effects in a community with a point source release of Mn to air. Effects will be assessed in children, young adults and older adults to identify potentially susceptible subpopulations. The characterization of effects in multiple organ systems provides a comprehensive assessment for identification of effects that may manifest at different ages. The results may be useful in a reassessment of the Mn RfC, the Mn residual risk assessment, and assessment of the potential risk for use of Mn as an automotive fuel additive.

Description:

Past research has tentatively associated excessive manganese (Mn) exposure with Parkinson-like effects in older adults, violent and aggressive behavior in young adults, and learning and neurobehavioral deficits in elementary school children. Our recent EPA/University of Quebec at Montreal collaborative study implicated chronic environmental airborne-Mn exposure at levels near the RfC as a causative factor for Parkinson-like signs in adults > 50 years of age. Significant associations were noted between airborne Mn levels and Mn levels in the blood of about 300 adult study participants, and between blood Mn levels and Parkinson-like motor, cognitive and affective status alterations. Studies in the US revealed statistically significant associations between increasing airborne release of Mn and lead and increasing violent crime rates. In addition, Mn body burdens in prisoners incarcerated for violent crimes were reported to be higher than in non-violent criminal and non-prisoner control populations. These observations were consistent with reports that the earliest indication of toxicity from occupational Mn exposure is locura manganica or manganese madness, characterized by aggressive and violent behavior. Chinese investigators reported scores on tests of learning and neurobehavioral functions in elementary school children with elevated Mn exposure were lower than in control children. Other studies suggested possible associations between Mn exposure and effects on pulmonary and cardiovascular functions. Some Mn-induced effects may be mediated through an inflammatory response and ensuing alterations in hypothalamic-pituitary hormone levels. The proposed study will assess total Mn exposure (through air, water and food), exposure to total airborne particulate matter, and airborne exposure to 11 other metals. Biomarkers of exposure to all targeted metals will be measured in blood or serum. Health effects will be assessed in the neurologic, cardiovascular, pulmonary and immunologic systems using biochemical, behavioral, and clinical techniques.

Record Details: