To Örebro University

Background: The incidence rate risk of testicular cancer has increased over the last four decades, and the most significant increase has been among Caucasian men in Nordic countries. Second-generation immigrant studies indicate a significant role of environmental exposure in testicular cancer.

Methods: We conducted a nationwide register-based case- control study including 6,390 testicular cancer cases registered in the Danish Cancer Registry between 1989 and 2014. Up to four age-matched controls for each case (n 18,997) were randomly selected fromthe Civil Registration System. Ambient air pollution levels were estimated at addresses of cases and controls with a state-of-the-art air pollution modeling system.

Results: We mostly found ORs close to 1.00 and with 95% confidence intervals (CI) spanning 1.00. Exposure during the year preceding birth was associated with ORs for nitrogen dioxide (NO2) of 0.87 (95% CI, 0.77-0.97) per 10 mg/m3 and for organic carbon of 0.84 (95% CI, 0.72-0.98) per 1 mg/m3. Exposure during the first 10 years of life was associated with ORs for organic carbon of 0.79 (95% CI, 0.67-0.93) per 1 mg/m3, for ozone (O3) of 1.20 (95% CI, 1.07-1.34) per 10 mg/m3, and for secondary inorganic aerosols of 1.07 (95% CI, 1.00-1.15) per 1 mg/m3.

Conclusions: Early-life exposure to NO2 and organic carbon (OC) was associated with lower risk for testicular cancer whereas early-life exposure to O3 and secondary inorganic aerosols (SIA) was associated with higher risk.