Elevated Rates of Neuroblastoma Associated with Exposure to Coal Tar from a Former Manufactured Gas Plant (MGP) Site

Purpose Extensive coal tar-related contamination from a former MGP site occurred in Taylorville, Illinois, including extremely high levels of polynuclear aromatic hydrocarbons, volatile organic compounds, and inorganic compounds in multiple on- and off-site environmental media. Coal tar has been classified as a known human carcinogen by numerous scientific and governmental panels of experts. Community concerns were raised regarding neuroblastoma risk given the proximity of a large, open pit with coal tar to the town playground, and known heightened fetal nervous system sensitivity to carcinogens. Methods A Standardized Incidence Ratio (SIR) analysis for the period 1986-1991 was conducted, comparing Taylorville and Christian County, IL with four comparison groups: 1) demographically-similar zip codes and counties; 2) demographically-similar zip codes without MGP sites; 3) the state of Illinois; and 4) the entire U.S. Confounding variables were accounted for by stratification or indirect adjustment. Disturbance and remediation of the site exacerbated the release of contaminants. Incident case data for the state of Illinois was obtained from the Illinois State Cancer Registry; population data was obtained from the 1990 U.S Census; and national reference rates were obtained from SEER. Results In all comparison groups, the SIR for neuroblastoma ranged from 9.9 to 24.3, with a lower-bounded 95% confidence interval (CI) that did not include 1. Comparisons using the four control groups provided comparable results, with higher SIRs generally seen in the comparison to the demographically similar, non-MGP site zip codes, which may imply an effect of the MGP sites on cancer incidence. Conclusion There was a significantly elevated incidence rate of neuroblastoma in children during a time period of heightened ambient exposure to coal tar-related contaminants relative to all comparison populations. There are 52,000 former MGP sites in the U.S. alone; thus, environmental exposure to coal tar is a continuing public health concern.