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

Abstract

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