The Diesel Exhaust in Miners Study: A Nested Case-Control Study of Lung Cancer and Diesel Exhaust

Abstract

BackgroundMost studies of the association between diesel exhaust exposure and lung cancer suggest a modest, but consistent, increased risk. However, to our knowledge, no study to date has had quantitative data on historical diesel exposure coupled with adequate sample size to evaluate the exposure–response relationship between diesel exhaust and lung cancer. Our purpose was to evaluate the relationship between quantitative estimates of exposure to diesel exhaust and lung cancer mortality after adjustment for smoking and other potential confounders.MethodsWe conducted a nested case–control study in a cohort of 12 315 workers in eight non-metal mining facilities, which included 198 lung cancer deaths and 562 incidence density–sampled control subjects. For each case subject, we selected up to four control subjects, individually matched on mining facility, sex, race/ethnicity, and birth year (within 5 years), from all workers who were alive before the day the case subject died. We estimated diesel exhaust exposure, represented by respirable elemental carbon (REC), by job and year, for each subject, based on an extensive retrospective exposure assessment at each mining facility. We conducted both categorical and continuous regression analyses adjusted for cigarette smoking and other potential confounding variables (eg, history of employment in high-risk occupations for lung cancer and a history of respiratory disease) to estimate odds ratios (ORs) and 95% confidence intervals (CIs). Analyses were both unlagged and lagged to exclude recent exposure such as that occurring in the 15 years directly before the date of death (case subjects)/reference date (control subjects). All statistical tests were two-sided.ResultsWe observed statistically significant increasing trends in lung cancer risk with increasing cumulative REC and average REC intensity. Cumulative REC, lagged 15 years, yielded a statistically significant positive gradient in lung cancer risk overall (P trend = .001); among heavily exposed workers (ie, above the median of the top quartile [REC ≥ 1005 μg/m3-y]), risk was approximately three times greater (OR = 3.20, 95% CI = 1.33 to 7.69) than that among workers in the lowest quartile of exposure. Among never smokers, odd ratios were 1.0, 1.47 (95% CI = 0.29 to 7.50), and 7.30 (95% CI = 1.46 to 36.57) for workers with 15-year lagged cumulative REC tertiles of less than 8, 8 to less than 304, and 304 μg/m3-y or more, respectively. We also observed an interaction between smoking and 15-year lagged cumulative REC (P interaction = .086) such that the effect of each of these exposures was attenuated in the presence of high levels of the other.ConclusionOur findings provide further evidence that diesel exhaust exposure may cause lung cancer in humans and may represent a potential public health burden.

Outdoor Particulate Matter Exposure and Lung Cancer: A Systematic Review and Meta-Analysis

“…This pattern is similar to our observation of a smaller lung cancer risk associated with PM for current smokers. Silverman et al (2012) proposed a number of biological mechanisms to explain this effect, such as polycyclic aromatic hydrocarbonspresent in tobacco smoke, diesel exhaust, and PM 2.5 -competing for metabolic activation, and decreased lung deposition of diesel exhaust among smokers. However, the exact mechanism leading to this reduced risk among smokers is still unclear.…”

Fuel consumption and exhaust emissions in the process of mechanized timber extraction and transport

“…Before the announcement, diesel exhaust gas was classified as probably carcinogenic. Upon analysis of the latest environmental research, the WHO scientists clearly stated that diesel exhaust gas is a cause of cancer (Kheifets 2012;Attfield et al 2012;Silverman et al 2012;Metz 2003;Vermeulen et al 2014). White et al (2010) in Report of EPA (Environmental Protection Agency) based on decades of research on humans and animals confirms that particulate matter is carcinogenic and significantly contributes to the development of cancer, lung cancer in particular (Environmental Protection Agency 2002).…”

Micro- and Nanostructural Characteristics of Particles Before and After an Exhaust Gas Recirculation System Scrubber

“…Diesel exhaust particles are composed of soot and other components, e.g., different salts, metals, and condensable matter, resulting from the fuel composition and burning conditions. Large particle surface area and the presence of metals and organics all have the potential to produce oxidative stress (Donaldson et al 2005), and diesel exhaust has been proved to be carcinogenic Silverman et al 2012). Particle surface area, number of ultrafine particles, the presence of bioavailable transition metals, polycyclic aromatic hydrocarbons (PAHs), and other particle-bound organic compounds are suspected to be more important than particle mass in determining the effects of combustion particles on human health (Lighty et al 2000).…”