No Link between Gasoline Exhaust Emissions and Lung Cancer

The objective of a recent study from Quebec, Canada, was to determine whether occupational exposure to gasoline engine emissions (GEE) increased the risk of lung cancer, and whether leaded or unleaded GEE increased the risk[i].

In occupational settings, gasoline engine exhaust is produced by vehicles ranging from motorcycles to small lorries.  Exposure to emissions from road vehicles can occur in occupations such as border inspectors, car mechanics, office workers, car park attendants, professional drivers, service station attendants, shopkeepers, street workers, tollbooth workers and (traffic) police officers.  Gasoline exhaust may also be emitted by engines used in small electric power generators and in equipment such as chainsaws, leaf blowers, hedge trimmers, brush cutters and clearing saws.

In 1989, the International Agency for Research on Cancer (IARC) classified gasoline engine exhaust as possibly carcinogenic to humans, or Group 2B[ii].  In 2012, gasoline exhaust was re-evaluated and this classification was unchanged[iii].

The researchers analysed data from two studies; one from the early 1980s that included many types of cancer, and one conducted in the late 1990s that focused specifically on lung cancer.  Both studies were case-control studies, in which lung cancer cases were compared with people who did not have lung cancer.  Altogether there were 1595 cases and 1432 controls.  The participants’ exposure to 294 agents, including gasoline engine exhaust and diesel engine exhaust, was estimated.  In the analysis, the data was adjusted to take into consideration the participants’ exposure to smoking, diesel exhaust, and other factors that may influence the lung cancer risk.

Analyses were performed using various exposure variables such as ever/never exposed, duration of exposure and cumulative exposure.  Leaded and unleaded gasoline exhaust were considered, and different types of lung cancer were investigated.  None of the analyses gave an elevated risk of lung cancer among those exposed to gasoline engine emissions.

 

[i] Xu, M. et al. Occupational exposures to leaded and unleaded gasoline engine emissions and lung cancer risk. Occup Environ Med oemed-2017-104801 (2017). doi:10.1136/oemed-2017-104801  http://oem.bmj.com/content/early/2017/12/21/oemed-2017-104801 (Accessed 28 December 2017)

[ii] International Agency for Research on Cancer (IARC) - Summaries and Evaluations.  Diesel and gasoline engine exhausts.  21 January 1998  http://www.inchem.org/documents/iarc/vol46/46-01.html (Accessed 28 December 2017)

[iii] Diesel and Gasoline Engine Exhausts and some Nitroarenes.  IARC Monographs 105 (2014) http://monographs.iarc.fr/ENG/Monographs/vol105/index.php (Accessed 28 December 2017)