Assessment of the epidemiological data relating lung cancer to air pollution

Our plain-English summary of Assessment of the epidemiological data relating lung cancer to air pollution, by F.E. Speizer (Environmental Health Perspectives, 1983).

The study

• Author: F.E. Speizer
• Journal: Environmental Health Perspectives
• Published: 1983;47:33-42
• Type of article: Review
• Cited by: 26 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

The epidemiological data linking air pollution and lung cancer are derived from statistical associations concerning rates of cancer among urban and rural residents, migrant studies and studies of occupational groups exposed to effluents from fossil fuel combinations. Few, if any of these studies, are adequately adjusted for both relatively simple measures of cigarette smoking or the potentially more subtle effects of the duration of smoking. Because urbanization and industrial sources of air pollution correspond chronologically with the major increases in cigarette smoking, it is not likely that the specific attributable risk to each component can be adequately assessed. Interactions between cigarette smoking and specific air pollutants, similar to those seen between cigarette smoking and asbestos and or radiation, may be occurring. Considering the various estimates made over the last 25 years, it is likely that the effect of air pollution on lung cancer is something greater than zero; however, it is unlikely that the estimate exceeds 2% of all lung cancers or 5/100,000 cases in urban males. Thus, the effect on all cancers is likely to be less than 1% of all cases.

In plain English

This 1983 article was a review, not a new study. The author summarized epidemiological evidence, mostly from the 1950s and 1960s, on whether air pollution from burning fossil fuels is linked to lung cancer. The evidence came from comparisons of migrants, of urban and rural residents, and of regions with different pollution levels. It also came from occupational groups such as coal gas workers, coke oven workers, roofers, and diesel-exposed transport and railroad workers. The author judged that few, if any, of these studies adequately accounted for cigarette smoking. Small differences in smoking habits could explain a 20% difference in lung cancer rates. Asbestos appeared only as an example: the author suggested that air pollutants might interact with smoking in a way similar to asbestos or radiation. Weighing estimates made over 25 years, the author judged the effect of air pollution on lung cancer likely greater than zero but unlikely to exceed 2% of all lung cancers, or 5 per 100,000 cases in urban males. The author concluded there was no reason to repeat such general-population studies.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Narrative review of published epidemiological studies and earlier risk estimates
• Who was studied: Studies reviewed: migrants and non-migrants, urban and rural residents, regions within countries with different air pollution levels, and occupational groups exposed to fossil fuel combustion products (coal gas workers, coke oven workers, roofers, railroad and London Transport workers)
• Exposure: General air pollution and occupational exposure to fossil fuel combustion products, including polycyclic hydrocarbons measured as benzo(a)pyrene and diesel exhaust. Asbestos was mentioned only as an example of a known interaction with cigarette smoking.
• Main results:
  • The author judged that few, if any, of the reviewed studies were adequately adjusted for cigarette smoking or for the duration of smoking.
  • In the occupational groups exposed to fossil fuel combustion products, relative risks of lung cancer were in the range of 2 to 3 times expected, which the author described as low compared with the risks seen in cigarette smokers.
  • The author noted that relatively minor differences in smoking rates between populations may be enough to explain a 20% difference in lung cancer rates.
  • The author suggested that interactions between cigarette smoking and specific air pollutants, similar to those seen between smoking and asbestos or radiation, may be occurring.
  • Across estimates made over 25 years, the author judged the effect of air pollution on lung cancer likely to be greater than zero but unlikely to exceed 2% of all lung cancers, or 5 per 100,000 cases in urban males. The effect on all cancers was likely less than 1% of all cases.
  • Estimates of the attributable risk percent declined as the available data were assessed more carefully over the past 25 years.
  • A railroad worker study of diesel exhaust, in which the author was involved, had no findings to report yet.
• The authors' conclusion: The author concluded that further general-population studies of air pollution and lung cancer would be unproductive, and that future epidemiology should be part of multidisciplinary collaborative studies of specific exposed groups.
• Limitations the authors state:
  • Because urbanization and industrial air pollution rose at the same time as cigarette smoking, the author stated that the attributable risk of each cannot be adequately separated.
  • The author stated that each of the earlier attributable-risk estimates was based on faulty data.
  • Occupational exposures were orders of magnitude higher than ambient levels, which limits how far the occupational studies apply to general environmental exposure.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Lung cancer.

Medical terms in this study, explained in our Lexicon: Lung Cancer, Attributable Risk.

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