Diesel Exhaust May Increase Lung Cancer Mortality
In a study released by the Journal of the National Cancer Institute, heavy diesel exhaust (DE) exposure might increase mortality rates from lung cancer. The study officially began in the 1980's, where the relationship between diesel exhaust and lung cancer was investigated. By 1989, the International Agency for Research on Cancer (IARC) classified diesel exhaust as a probable carcinogen.
Preliminary information was collected on these workers when diesel-powered equipment was introduced into each facility. The years of introduction ranged from 1947-1967, and data was collected through to the end of 1997. National Institute for Occupational Safety and Health and Dr. Debra T. Silverman, from the National Cancer Institute, named this study the "Diesel Exhaust in Miners Study." Preliminary information was collected on these workers when diesel-powered equipment was introduced into each facility. The years of introduction ranged from 1947-1967, and data was collected through to the end of 1997.
What was found at the end of the study was that there was a statistically significant increased risk of lung cancer in relation to REC exposure. REC is short for Respirable Elemental Carbon — that which can be inhaled and cause damage to lungs. In addition, the study found evidence that there was also an increased risk of lung cancer related mortality for workers above-ground who had exposure to REC. In the mining industry, there are many other pollutants that workers might inhale - such as silica, asbestos, non-diesel exhaust-related polycyclic aromatic hydrocarbons, respirable dust, and radon. The researchers did take these other pollutants into consideration, but they had very little, if any impact on the results of the study. Results were also adjusted for workers habits such as smoking, previous employment in occupations which have a high risk of lung cancer, and history of respiratory issues.
Dr. Silverman quotes, "Our findings are important not only for miners but also for the 1.4 million American workers and the 3 million European workers exposed to diesel exhaust and for urban populations worldwide." She also points out that cities like Mexico City and many urban areas in China have been reporting DE levels that are comparable to some underground levels in mining facilities which were part of this study.
Dr. Silverman goes on to say, "Because such workers had at least a 50% increased lung cancer risk, our results suggest that the high air concentrations of elemental carbon reported in some urban areas may confer increased risk of lung cancer. Thus, if the diesel exhaust/lung cancer relation is causal, the public health burden of the carcinogenicity of inhaled diesel exhaust in workers and in populations of urban areas with high levels of diesel exposure may be substantial."
As with any study, there are limitations. Dr. Silverman explains that there is uncertainty in analyzing past exposure of the workers to DE, and the fact that data on lifestyle choices like smoking, were gathered from relatives of the workers, not the workers themselves.
Dr. Lesley Rushton, of Imperial College in London, suggests that this rise in risk in relation to DE should call for, "stringent occupational and particularly environmental standards for DE exposure." Some suggestions to mitigate these risks include improving ventilation in the work area, having regular maintenance performed on vehicles, limiting workers' time in vehicle, and turning off the engines when vehicles are not in use.
Mining Image via Shutterstock