Single Pollutant Versus Surrogate Measure Approaches: Do Single Pollutant Risk Assessments Underestimate the Impact of Air Pollution on Lung Cancer Risk?

Abstract

Cancer risk as a result of air pollution may be quantified by different approaches. We compared the sum of unit risk based effects of single pollutants with an epidemiology-based method by using PM(10) as a surrogate of the total air pollution. The excess rate for lung cancer cases attributable to an increase of 10 microg/m3 in average PM(10) exposure was estimated from available cohort studies. Applying the epidemiology-based risk method to the air pollution situation in the Basel area (Switzerland) resulted in 13.3 (95% CI = 6.9-19.8) excess lung cancer cases per 100,000 person years. This estimate was considerably higher than the unit risk-based estimate yielding 1.1 (range, 0.45-2.8) cancer cases per 100,000 person years. We discuss these discrepancies in light of inherent differences between approaches in toxicology and epidemiology.

What is responsible for the carcinogenicity of PM2.5?

“…Using a broadly similar approach to our own, Röösli and colleagues 42 have compared estimates of lung cancer risk derived from coefficients based on particulate matter mass concentration from the American cohort studies, including the ACS study, 1 and the summed application of unit risk factors for a range of chemical carcinogens. The risk estimate derived from the former approach far exceeds that resulting from the application of unit risk factors.…”

“…In both cases, however, contemporary air quality data were used, and no account was taken of cancer latency periods and changing levels of air pollution. 42 …”

Comparing the lung cancer burden of ambient particulate matter using scenarios of air quality standards versus acceptable risk levels

“…For the epidemiological approach, we estimated the number of premature lung cancer deaths, which are attributable to PM 10 exposure based on the excess rate (Röösli et al 2003) according to Eq. 1.…”

“…In the fourth exposure scenario (11 lg/m 3 ), we assumed compliance of ambient PM 2.5 annual mean concentrations with the newly adopted OPAC air quality standard of PM 2.5 -which corresponds to the WHO guideline value of 10 lg/m 3 -throughout the whole country. Assuming compliance with the limit value at 99% of all residential sites, the population-weighted mean concentration was 17% below the limit value, namely 8.3 lg/m 3 of PM 2.5 (Röösli 2014). The mean value assuming 100% compliance was not provided.…”

“…Second, epidemiology-based risk assessments of PM now use various counterfactual concentrations. A range of previous studies (e.g., Röösli et al 2003;Künzli et al 1997Künzli et al , 2000 used a counterfactual concentration of 7.5 lg/ m 3 of PM smaller than 10 lm in aerodynamic diameter (PM 10 ), reflecting the mean value of the-at that time lowest-exposure category ''5-10 lg/m 3 .'' Meanwhile, many epidemiological studies include participants exposed to very low outdoor concentrations of PM (Beelen et al 2014), possibly as low as the concentrations measured at alpine monitoring stations (e.g., 2.2 lg/m 3 for PM 10 at Jungfraujoch in 2010).…”