Cancer risk following residential exposure to polychlorinated biphenyls in indoor air: A Danish register-based study

Laura Deen, Karin Sørig Hougaard, Alice Clark, Harald William Meyer, Marie Frederiksen, Lars Gunnarsen, Helle Vibeke Andersen, Thomas Hougaard, Niels Erik Ebbehøj, Kajsa Kirstine Ugelvig Petersen, Jens Peter Bonde, and Sandra Søgaard Tøttenborg


BACKGROUND AND AIM: Polychlorinated biphenyls (PCBs) are biopersistent chemicals classified as human carcinogens, primarily based on evidence on higher-chlorinated PCBs found in food. The carcinogenic potential of lower-chlorinated PCBs (LC-PCBs) in indoor air remains largely unexplored. We investigated overall and site-specific cancers following residential exposure to LC-PCBs in indoor air. METHODS: Cancer risk was examined in the Health Effects of Indoor Air (HESPAIR) cohort of 41,493 residents of two partly PCB contaminated estates in Greater Copenhagen, identified by nation-wide registries. PCB-exposure was defined by duration of living in a contaminated apartment and PCB measurements in indoor air in subsets of apartments [ng PCBtotal/m3*year]. Cancer diagnoses were extracted from the Danish Cancer Registry for the follow-up period of 1970–2018. We estimated adjusted hazard ratios with time-varying exposure and a 10-year lag using Cox regression. RESULTS:Living in a PCB-contaminated apartment was not associated with an elevated overall cancer risk. However, higher risks were seen for four out of 56 site-specific cancers; compared with residents exposed to 300 ng/m3*year, residents exposed to 3000 ng/m3*year had a higher risk of liver cancer (HR 2.91, 95% CI 1.33-6.38), pancreatic cancer (HR 1.59, 95% CI 0.96-2.63) and meningeal tumours (HR 3.89, 95% CI 2.07-7.30). For testis cancer, a higher risk was observed among residents exposed to 300-950 ng/m3*year relative to residents exposed to 300 ng/m3*year (HR 2.56, 95% CI 1.22-5.34), but the risk for testis cancer was not elevated for residents exposed to 950 ng/m3*year. CONCLUSIONS:In this first population-based cohort study of residential exposure to LC-PCBs in indoor air, living in a PCB-contaminated apartment was not associated with a higher overall cancer risk. However, the results indicate that residents exposed to LC-PCBs indoors in their private homes have a higher risk of cancer of the liver, pancreas, testes and meningeal tumours. KEYWORDS: Built environment, Cancer and cancer precursors, Environmental epidemiology, Chemical exposures