New research from Wake Forest Baptist Medical Center finds that suicide, while strongly associated with psychiatric conditions, also correlates with environmental pollution.
A new ecological study led by John G. Spangler, M.D., M.P.H., a professor of family medicine at Wake Forest Baptist Medical Center, examined the relationship between air pollution—specifically emissions from coal-fired power plants—and county-level suicide rates in North Carolina. The analysis combined U.S. Census data with mortality records and environmental emissions information to identify potential links between coal-plant presence, airborne toxic metals, and population suicide rates.
Spangler and colleagues focused on 20 North Carolina counties with operating coal-fired electricity plants. They used 2000 U.S. Census population data, mortality statistics from 2001–2005 provided by the North Carolina State Center for Health Statistics, and air contaminant measurements reported by the U.S. Environmental Protection Agency. The researchers evaluated county-level suicide mortality in the context of measured airborne contaminants and the presence of coal-fired power infrastructure.
The analysis found that county suicide rates in North Carolina were higher than the U.S. average during the study period—12.4 suicides per 100,000 population in the state versus 10.8 per 100,000 nationally—and that the presence of coal-fired electricity plants correlated with elevated levels of several airborne metals. Measured pollutants that correlated with plant presence included nickel, mercury, lead, chromium, cadmium, beryllium and arsenic.
Using a county-level statistical approach, the study estimated that each additional coal-fired plant in a county was associated with roughly two additional suicides per 100,000 people per year. When the researchers applied this association to the statewide population at the year 2000 census, the calculation produced an estimate of the number of suicides potentially associated with coal-fired plant presence at the population level. The authors emphasize that this finding is an ecological association and does not prove individual-level causation.
Spangler noted that earlier research has linked environmental contamination and exposure to heavy metals with various adverse health outcomes, including mood disorders, but that coal emissions had not previously been examined in this specific way with respect to suicide. He cautioned that ecological studies are limited by analysis at the group level; county-level results cannot account for individual risks or exposures and cannot definitively establish cause and effect.
Despite those limitations, the results raise important public health questions. If air quality and specific emissions from coal combustion contribute to mood-related disorders or increase population suicide risk, then stricter regulation of air pollutants and coal-fired power plant emissions could be a preventive consideration. The study calls for additional research to clarify which components of coal emissions, if any, are most relevant and to investigate potential biological or psychosocial mechanisms linking air pollution to mood and suicidal behavior.
The full study, “Association of Suicide Rates and Coal-Fired Electricity Plants by County in North Carolina,” by John G. Spangler, is published online in the Journal of Mood Disorders. The authors highlight the need for more detailed, individual-level studies and for continued monitoring of air quality and public health indicators in communities near coal-fired power plants.
Notes about this pollution and suicide research
Contact: Bonnie Davis – Wake Forest Baptist Medical Center
Source: Wake Forest Baptist Medical Center press release
Image Source: The coal power plant smoke emissions image is available in the public domain.
Original Research: Full open access research (PDF) for “Association of Suicide Rates and Coal-Fired Electricity Plants by County in North Carolina” by John G. Spangler in Journal of Mood Disorders. Published online May 2013 DOI: 10.5455/jmood.20121120043720