Long-Term Ambient Residential Traffic-Related Exposures and Measurement Error-Adjusted Risk of Incident Lung Cancer in the Netherlands Cohort Study on Diet and Cancer

BACKGROUND: The International Agency for Research on Cancer (IARC) recently declared air pollution carcinogenic to humans. However, no study of air pollution and lung cancer to date has incorporated adjustment for exposure measurement error, and few have examined specific histological subtypes.

OBJECTIVES: Assess the association of air pollution and incident lung cancer in the Netherlands Cohort Study on Diet and Cancer and the impact of measurement error on these associations.

METHODS: The cohort was followed 1986-2003 and 3,355 incident cases were identified. Cox proportional hazards models were used to estimate hazard ratios and 95% confidence intervals, for long-term exposures to NO2, black smoke (BS), PM2.5, and measures of roadway proximity and traffic volume, adjusted for potential confounders. Information from a previous validation study was used to correct the effect estimates for measurement error.

RESULTS: We observed elevated risks of incident lung cancer with exposures to BS (HR=1.16, 95% CI: 1.02, 1.32, per 10 µg/m(3)), NO2 (HR=1.29, 95% CI: 1.08, 1.54, per 30 µg/m(3)), PM2.5 (HR=1.17, 95% CI: 0.93, 1.47, per 10 µg/m(3)), and with measures of traffic at the baseline address. The exposures were positively associated with all lung cancer subtypes. After adjustment for measurement error, the HRs increased and the 95% CIs widened (HR=1.19 (95% CI: 1.02, 1.39) for BS and HR=1.37 (95% CI: 0.86, 2.17) for PM2.5).

CONCLUSIONS: These findings add support to a growing body of literature on the effects of air pollution on lung cancer. In addition, they highlight variation in measurement error by pollutant and support the implementation of measurement error corrections when possible.