Background
Polychlorinated biphenyls (PCBs) are biopersistent chemicals classified as human carcinogens. This classification is primarily based on evidence on higher-chlorinated PCBs found in food. The carcinogenic potential of airborne lower-chlorinated PCBs remains largely unexplored. Objectives: We aimed to investigate cancer risk following residential exposure to airborne PCBs.
Discussion
In this, to our knowledge, first population-based cohort study of residential exposure to airborne PCBs, we found no association between exposure to PCBs in indoor air in private homes and the risk for most of the specific cancers. Higher risk of liver cancer and meningiomas were observed. https://doi.org/10.1289/EHP10605.
Methods
Cancer risk was examined in the Health Effects of PCBs in Indoor Air (HESPAIR) cohort of 38,613 residents of two partly PCB-contaminated residential areas in Greater Copenhagen, identified by nationwide registries. PCB exposure was based on relocation dates and indoor air PCB measurements in subsets of apartments. 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 cumulative exposure and a 10-y lag using Cox regression.
Results
Overall risk of cancer was not associated with <math><mrow><msub><mrow><mrow><mtext>PCB</mtext></mrow></mrow><mrow><mrow><mtext>year</mtext></mrow></mrow></msub></mrow></math>, [hazard ratio (HR) for high-exposed vs. low-exposed =0.98<math><mrow><mo>=</mo><mspace></mspace><mn>0.98</mn></mrow></math>; 95% confidence interval (CI): 0.88, 1.09], but residents exposed to ≥3,000 ng/m3<math><mrow><mo>≥</mo><mn>3,000</mn><msup><mrow><mtext> ng</mtext><mo>/</mo><mi>m</mi></mrow><mrow><mn>3</mn></mrow></msup></mrow></math> PCB×year<math><mrow><mtext>PCB</mtext><mo>×</mo><mtext>year</mtext></mrow></math> had higher risk of liver cancer (HR =2.81<math><mrow><mo>=</mo><mspace></mspace><mn>2.81</mn></mrow></math>; 95% CI: 1.28, 6.15) and meningiomas (HR =3.49<math><mrow><mo>=</mo><mspace></mspace><mn>3.49</mn></mrow></math>; 95% CI: 1.84, 6.64), with indications of exposure-response relationships. Results were suggestive of a higher risk of pancreatic cancer (HR =1.59<math><mrow><mo>=</mo><mspace></mspace><mn>1.59</mn></mrow></math>; 95% CI: 0.95, 2.64) at the highest aggregated PCB level. For testis cancer, a higher risk was observed among residents exposed to 300-949 ng/m3<math><mrow><mn>300</mn><mo>-</mo><mn>949</mn><mtext> </mtext><msup><mrow><mtext>ng</mtext><mo>/</mo><mi>m</mi></mrow><mrow><mn>3</mn></mrow></msup></mrow></math> PCB×year<math><mrow><mtext>PCB</mtext><mo>×</mo><mtext>year</mtext></mrow></math> relative to residents exposed to <300 ng/m3<math><mrow><mo><</mo><mn>300</mn><msup><mrow><mtext> ng</mtext><mo>/</mo><mi>m</mi></mrow><mrow><mn>3</mn></mrow></msup></mrow></math> PCB×year<math><mrow><mtext>PCB</mtext><mo>×</mo><mtext>year</mtext></mrow></math> (HR =2.97<math><mrow><mo>=</mo><mspace></mspace><mn>2.97</mn></mrow></math>; 95% CI: 1.41, 6.28), but the risk was not higher for residents exposed to ≥950 ng/m3<math><mrow><mo>≥</mo><mn>950</mn><msup><mrow><mtext> ng</mtext><mo>/</mo><mi>m</mi></mrow><mrow><mn>3</mn></mrow></msup></mrow></math> PCB×year<math><mrow><mtext>PCB</mtext><mo>×</mo><mtext>year</mtext></mrow></math>. Apart from this, the risk of specific cancers was similar across exposure groups.