Residential exposure to airborne polychlorinated biphenyls and risk of cardiovascular diseases: A register-based cohort study

Background and aim Polychlorinated biphenyls (PCBs) are biopersistent chemicals ubiquitously present in our environment. Although exposure to lower-chlorinated PCBs (LC-PCBs) evaporating from building materials to indoor air is relatively common, the long-term cardiovascular effects remain unknown. We aimed to examine the risk of cardiovascular disease (CVD) following residential exposure to PCBs in indoor air. Methods The study builds on the register-based Health Effects of PCBs in Indoor Air (HESPAIR) cohort of 51,921 residents of two residential areas near Copenhagen: Farum Midtpunkt and Brøndby Strand Parkerne. Here, indoor air was contaminated with PCB in one third of the apartments. Indoor air measurements in subsets of apartments have documented large differences in PCB-concentrations between contaminated and uncontaminated apartments, dominated by LC-PCBs. Individual PCB-exposure was based on relocation dates from nation-wide registers and indoor air PCB-measurements and calculated as PCByear. CVD Information was retrieved from the Danish National Patient Register for the follow-up period 1977–2018. We estimated hazard ratios using Cox regression analyses with time-varying exposure adjusting for a priori identified potential confounders. Results Residential exposure to airborne PCB was not associated with a higher overall risk for CVD (HR for highly exposed: 1.02, 95% CI 0.95-1.11). The same was the case for most of the specific cardiovascular diseases apart from acute myocardial infarction where a 17% higher risk was observed for residents exposed to ≥3300 ng/m3*year compared to the reference group (HR 1.17, 95% CI 1.01-1.36). Conclusions In this first study to examine CVD risk following residential exposure to PCBs in indoor air, we observed only limited support for cardiovascular effects of living in PCB-contaminated air. Considering the prevalence of exposure to airborne PCBs and lack of knowledge on their potential health effects, these findings need to be corroborated in future studies. Key words lower-chlorinated PCBs; cardiovascular toxicity; environmental epidemiology; environmental pollutants