Health effects following residential exposure to polychlorinated biphenyls in indoor air

Large numbers of citizens worldwide are exposed to polychlorinated biphenyls (PCBs) evaporating from building materials in homes, schools, and workplaces, although PCBs was globally banned in 1979. While a large body of scientific research addresses health risk related to higher-chlorinated PCB (HC-PCBs) conferred by food, the evidence of risk related to lower-chlorinated PCBs (LC-PCBs) in indoor air remains largely unexplored in humans.

The overall objective of this PhD-project was to investigate the risk of cancer, cardiovascular diseases, and type 2 diabetes after residential exposure to airborne PCBs. To do so, we established the Health Effects of PCBs in Indoor Air (HESPAIR) cohort of 52,000 residents of two residential areas in Denmark where indoor air is contaminated with LC-PCBs in subsets of apartments. Individual PCB exposure was based on register-based information on relocation dates and indoor air PCB measurements from subsets of apartments. Information on outcomes and covariates was extracted from the Danish registers.
We found a higher risk of liver cancer and meningiomas among residents exposed to PCBs in indoor air, while the overall risk of cancer and the risk for most of the cancers of a priori interest were not higher. A higher risk of acute myocardial infarction and type 2 diabetes was observed among the highest exposed residents, but with no clear exposure-response relationship. In conclusion, this thesis indicates a potential health risk of living in indoor air contaminated with LC-PCBs, but robustness of results varied across the outcomes investigated. Given the scarcity of comparable literature, these findings should be interpreted and generalised cautiously until further results from observational and mechanistic studies are available.