Air Manganese Levels and Chronic Liver Disease Mortality in North Carolina Counties: An Ecological Study

Manganese is an essential trace element which is toxic in high doses. Over the past several decades, manganese has replaced lead as the anti-knock agent in gasoline, raising concern about air and road-side contamination with this element. In addition, manganese is absorbed by the liver, making specific populations (e.g., pregnant women, infants and children, and patients with liver disease) susceptible to its toxic effects. Using data from the US Census Bureau, the North Carolina State Center for Health Statistics, and the US Environmental Protection Agency, this ecological study evaluated chronic liver disease mortality rates in North Carolina's 100 counties. It correlated these rates with county-level demographics as well as on-road and non-road air borne manganese concentrations. Median income by county was inversely associated with chronic liver disease mortality, while the logarithmically transformed airborne concentrations of on-road manganese were positively correlated with county-level chronic liver disease mortality. Because environmental manganese near roads is likely to increase over time, these pilot findings potentially have regulatory implications and argue for further research.