Manuscript title: Geospatial analysis of Cancer risk and residential proximity to coal mines in Illinois

Abstract

Background: Studies have indicated a population-level association between coal mining and cancer incidence and mortality, but few studies specifically examined residential proximity to this exposure using spatial analysis. We utilized a Geographic Information Systems (GIS) approach to perform spatial and statistical analyses to test two coal mining exposure variables and their associations with cancer incidence and mortality in Illinois--the fourth highest coal producing state in the United States.

Methods: Data included age-adjusted county-level cancer incidence and mortality for five cancers: all malignant, lung, colorectal, breast (female) and prostate. Coal mining exposure was defined by two variables: coal production group and distance-weighted exposure. Spatial analyses were performed to identify spatial clustering. Correlation and stepwise regression analyses were performed to explore the relationship between cancer incidence and mortality and coal mining exposures. Covariates considered in regression analyses included socioeconomic deprivation, former/current smoking prevalence, race, and rurality.

Results: Global spatial autocorrelation indicated significant spatial clustering of incidence, mortality and aggregated coal production. Distance-weighted exposure was significantly correlated with coal production group, age-adjusted all cancer incidence and age-adjusted all cancer mortality. Regression analyses indicated an association between recent coal production and colorectal cancer incidence (p=0.009) and mortality (p=0.035) and prostate cancer mortality (p=0.047). Distance weighted exposure was associated with lung cancer incidence (p=0.004) and mortality (p<0.001), and all cancer mortality (p<0.001).

Conclusion: Coal production, incidence and mortality are spatially clustered in Illinois. Exposures to coal mining were associated with elevated risk of multiple cancers, most notably lung and colorectal. The environmental impact of the mining industry is substantial, and exposure of individuals residing near coal mines to known carcinogens is plausible. Future studies are needed to further elucidate the population exposure dynamics of coal mining, and should be explored using individual-level exposures and cancer outcomes.

Keywords: Cancer incidence; Cancer mortality; Coal Mining; Geographic Information Systems; Spatial analysis.