Blog: Decoding the Research

Diesel exhaust increases lung cancer risk

Published: May 7th, 2012

Miners exposed to diesel engine exhaust have a threefold increased risk for lung cancer. The story isn’t that surprising – diesel exhaust was first linked to cancer in 1955. (1) The US National Toxicology Program has classified exposure to diesel exhaust particulates as "reasonably anticipated to be a human carcinogen”, and the International Agency for Research on Cancer categorized diesel exhaust as “probably carcinogenic to humans” in 1989.

The Diesel Exhaust in Miners Study (DEMS), an $11.5 million study run by the National Cancer Institute (NCI) and the National Institute for Occupational Safety and Health (NIOSH), and the most comprehensive and largest study on the topic to date, published their findings last month. The DEMS scientists followed over 12,000 workers in eight mining facilities and controlled for confounding factors such as smoking. The study began in 1998, and since inception has faced legal opposition in a war waged by an industry coalition. (Find a more detailed accounting of the legal battle here.) The DEMS researchers at the NCI and NIOSH finally overcame legal hurdles and published their data in March, showing three to fivefold increased risk of lung cancer from exposure to diesel engine exhaust, depending upon levels of exposure. (3,4)

Diesel exhaust contains many different substances, including polycyclic aromatic hydrocarbons (PAHs), one of the most common air pollutants and linked to DNA damage, mutation, and oxidative stress – all potentially triggering cancer. Diesel fuel is fairly common in a number of industries and professions. The highest exposures are seen in underground mining and construction sites, but work-shop mechanics, dock workers, fire station workers, drivers, train crew, parking attendants, vehicle testers and utility service workers are all exposed to diesel exhaust. (2)

Aside from the legal drama, the timing of this study is especially notable as the International Agency for Research on Cancer (part of the World Health Organization) will be reevaluating the status of diesel exhaust as a carcinogen at a meeting in France this June. The National Toxicology Program is also considering reassessing its recommendations regarding diesel exhaust exposure in the 2013 report to Congress. Upgrading diesel exhaust from ‘reasonably’ and ‘suspected’ carcinogen to a confirmed risk factor for lung cancer could have major effects on regulations regarding workers in these industries – we hope, protecting thousands from lung and other cancers.


  1. Kotin et al., AMA Arch Ind Health. 1955; 11(2): 113-120.
  2. Pronk et al., J Exp Science Environ Epidem. 2009; 19(9):443-457.
  3. Silverman et al., J Natl Cancer Inst. 2012; 104; 1-14.
  4. Attfield et al., J Natl Cancer Inst. 2012; 104; 1-15.