In this study, a lower risk for testicular cancer was noted in relation to early-life exposure to NO2 and OC whereas a higher risk was evident in relation to early-life exposure to O3 and SIA.

• In this nationwide register-based case-control study of 6,390 testicular cancer cases from the Danish Cancer Registry, up to four age-matched controls for each case (n=18,997) were randomly chosen from the Civil Registration System.

• Using a state-of-the-art air pollution modeling system, ambient air pollution levels were estimated at addresses of cases and controls.

• Experts mostly identified ORs close to 1.00 and with 95% confidence intervals (CI) spanning 1.00.

• Exposure during the year preceding birth was found to be linked with ORs for NO2 of 0.87 (95%CI: 0.77-0.97) per 10 µg/m3 and for organic carbon of 0.84 (95%CI: 0.72-0.98) per 1 µg/m3.

• Exposure during the first 10 years of life was identified to be linked with ORs for organic carbon of 0.79 (95%CI: 0.67-0.93) per 1 µg/m3, for O3 of 1.20 (95%CI: 1.07-1.34) per 10 µg/m3 and for secondary inorganic aerosols of 1.07 (95%CI: 1.00-1.15) per 1 µg/m3.