Highlights
- Diesel engine exhaust is a prevalent lung carcinogen, causing almost 200 cases of lung cancer annually in Ontario.
- Reducing exposure to diesel exhaust will lead to fewer lung cancers.
- Further regulation is needed to effectively protect workers from this exposure.
Each year in Ontario, approximately 186 cases of lung cancer are estimated[*] to be caused by exposure to diesel engine exhaust in the workplace. These are cancers that can be prevented with exposure reduction strategies and regulations to protect workers.
Occupational diesel engine exhaust exposure mostly affects males, accounting for an estimated 178 new cases (4.2%) of lung cancer among Ontario men in 2011, compared to 8 new cases (0.2%) of lung cancer among Ontario women. This reflects the historically lower number of women in jobs with diesel exhaust exposure.
| OCCUPATION | NUMBER OF LUNG CANCERS |
|---|---|
| Mining and Quarrying workers | 85 (46%) |
| Motor transport operators | 61 (33%) |
| Mechanics and repairers | 17 (9%) |
| Material handlers | 14 (8%) |
| Other occupations | 10 (5%) |
| TOTAL | 186 (100%) |
After silica, diesel engine exhaust is the most common occupational lung carcinogen, with CAREX Canada estimating that 300,000 Ontario workers are currently exposed.[1] Exposure occurs when working with or near diesel-powered engines, vehicles or equipment. Levels can be especially high in enclosed or semi-enclosed areas, such as underground mines or garages and tunnels.
The 4 occupations that contribute to the majority of lung cancer cases are mining and quarrying workers, truck drivers, diesel engine mechanics and repairers, and material handlers. Diesel exhaust exposure also occurs among protective service workers (from diesel ambulances and fire trucks), railway conductors and engineers, and forestry and logging workers.
Diesel engine exhaust is a human lung carcinogen, as classified by the International Agency for Research on Cancer.[2] It is a complex mixture of gases (including carbon dioxide, sulphur and nitrogen oxides) and particulates (including elemental carbon, and carcinogens such as polycyclic aromatic hydrocarbons and trace metals). The elemental carbon, due to its small particle size, carries carcinogenic components deep into the lungs, which is how diesel exhaust causes lung cancer.
Unlike many other carcinogens, there is no exposure limit in any Canadian jurisdiction for diesel engine exhaust in workplaces, other than mines. In a report to the Ontario Ministry of Labour, the Occupational Cancer Research Centre recommended implementing a diesel engine exhaust exposure limit for general workplaces, and lowering the exposure limit in underground mines.[3] Exposure reduction strategies that can be employed are use of fuel alternatives, use of engines with new diesel filtration technologies, regular engine maintenance, minimizing idling time, and running engines outdoors or in a well-ventilated area.[4]
An increased risk of lung cancer is present even at very low levels of exposure. For example, in non-occupational settings, diesel exhaust causes an estimated 4.8% of lung cancers simply through its presence in general air pollution.[5] The risk of lung cancer is greater for those who both smoke and are exposed to diesel exhaust than for those who are in contact with either exposure alone.[2]
As a component of air pollution, diesel exhaust has also been associated with cardiovascular disease and it is a respiratory irritant, with short-term effects including irritation of the eyes and throat, cough, phlegm, light-headedness and nausea. There is limited evidence that diesel exhaust causes bladder cancer.[2]