Emissions from Industrial Sources

Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F) are persistent organic pollutants primarily emitted from industrial combustion facilities such as incinerators and coal-fired power plants and are also by-products of the manufacture and use of polychlorinated biphenyls, paper pulp bleaching, and chlorophenols and chlorophenoxy herbicides. Several PCDD/F congeners are classified by IARC as human carcinogens. However, much of the evidence in human populations, including increased risks of non-Hodgkin lymphoma and breast cancer, is derived from occupational settings and studies of accidental industrial releases. General population exposures to PCDD/F from non-dietary sources are not well characterized.

Exposure studies in the NCI SEER Non-Hodgkin lymphoma (NHL) Study have shown that emissions of certain PCDD/F are dispersed, transported, and distributed in a distance-dependent manner and that the facility type influences residential exposures. Many other known and suspected carcinogens emitted from industrial sources are similarly understudied as exposures in the ambient environment. Epidemiologic studies are often difficult to conduct given limited measurement data for these pollutants and the challenge in estimating exposures over long periods of time.

Investigators in the Occupational and Environmental Epidemiology Branch (OEEB) have ongoing efforts to verify the geographic location of industrial emissions sources in the U.S., improve the characterization of exposure determinants, construct Geographic Information Systems (GIS)-based exposure metrics, and validate exposure estimates with biological or environmental measurements. For example, investigators leverage GIS methodology, regulatory data, and other information to construct exposure indices that account for the distance between an exposure point source and the participant’s home, historical emissions from the facility, prevailing wind direction over time, and other factors. These exposure assessment enhancements support multiple current and future studies of industrial exposures and cancer risk, including a re-analysis of PCDD/F emissions and NHL risk in the NCI SEER-NHL Study, which found an increased risk of NHL with residential proximity to cement kilns. In collaboration with the National Institute of Environmental Health Sciences, OEEB investigators also identified an increased risk of breast cancer associated with residential PCDD/F exposures in the Sister Study. In the first study of its kind, OEEB scientists found that higher residential exposure to ethylene oxide, a carcinogenic sterilization agent, was associated with an increased risk of developing intraductal breast cancer. Work to investigate other chemical emissions from industrial point sources and their putative associations with cancer risk is ongoing.  

In addition to the limited studies of cancer etiology, whether observed cancer disparities in racial and ethnic minoritized communities and those of low socioeconomic status are driven in part by differential exposure to industrial carcinogenic emissions is unclear. OEEB investigators have been working to describe population burdens of exposure to these emissions across population characteristics to help elucidate patterns that might be informative.

For more information, contact Dr. Rena Jones.

Occupational and Environmental Epidemiology Branch - Research Areas