Association of suicide rates and coal-fired electricity plants by county in North Carolina

Abstract

Suicide, strongly associated with psychiatric conditions, also correlates with environmental pollution, likely due to quality of life factors which impact mood disorders. This ecological study evaluated the effect of the presence of a coal-fired electricity plant in a county on county suicide rates in North Carolina. Data from the 2000 US Census, 2001-2005 mortality rates from the North Carolina State Center for Health Statistics and the US Environmental Protection Agency were used in multivariable linear regression. Twenty coal plants existed in North Carolina during this study’s period. Only about one third of the population of North Carolina lived in urban areas. Seventy four percent of the population was white, and the mean population per county was nearly 48,000. About 13% of the population lived at or below the poverty level. The median household income of counties was approximately $34,000. County-level suicide rates were higher in North Carolina (12.4/100,000 population) compared to the US population (10.8/100,000). The linear regression model indicated that percent white race, median age of county population and number of coal plants per county explained 25.8% of the variance of county suicide rates. For coal plants, the linear regression model suggests that for each additional coal plant in a given county, there would be an additional 1.96 suicide per 100,000 population. The presence of a coal plant correlated with airborne levels of nickel, mercury, lead, chromium, cadmium, beryllium and arsenic. This is the first study to show that the existence of coal electricity plants is related to population-level suicide rates. Because suicide might be associated with environmental pollution, this study may help inform regulations not only of air pollutants, but also of coal electrical power plant emissions.