Smoking and roentgenographic opacities in US Navy asbestos workers

Our plain-English summary of Smoking and roentgenographic opacities in US Navy asbestos workers, by A.M. Ducatman, B.F. Withers, W.N. Yang (Chest, 1990).

The study

• Authors: A.M. Ducatman, B.F. Withers, W.N. Yang
• Journal: Chest
• Published: 1990;97(4):810-3
• Cited by: 31 articles, as counted by NIH iCite
• Read it: PubMed · Publisher
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 003650).

Abstract

The US Navy's Asbestos Medical Surveillance Program monitors civilian and military employees with current or historical exposure to asbestos. The prevalence of definite radiologic parenchymal abnormalities (ILO category greater than or equal to 1/0) was 3.10 percent for 32,233 smokers vs 1.09 percent for 13,414 nonsmokers. The age-adjusted prevalence ratio was 2.23. The difference in prevalence between smokers and nonsmokers persisted in all age groups studied and was greatest among the oldest employees. These findings in a large population suggest that parenchymal opacifications alone will not reliably differentiate between the impacts of asbestos exposure and smoking in patients who face both risks.

In plain English

This study used records from the US Navy's Asbestos Medical Surveillance Program, which follows civilian and military employees with current or past asbestos exposure. It compared 32,233 past or present cigarette smokers with 13,414 nonsmokers. Chest X-rays were scored with the ILO classification system, and the data combined the readings of 23 readers. Small lung-tissue opacities at ILO category 1/0 or higher appeared in 3.10 percent of smokers and 1.09 percent of nonsmokers. The age-adjusted prevalence ratio was 2.23. Smokers had more opacities in every age group, with no tendency for the gap to shrink with age; the authors called the ratio for workers under 30 unreliable because only nine readings were positive. The smoker-to-nonsmoker ratio stayed stable or rose at higher severity scores. The authors concluded that these opacities alone will not reliably separate the effects of asbestos and smoking in people with both exposures. They noted limits: the study could not examine smoking in people unexposed to asbestos, recall bias could not be excluded, past and current smokers were combined, and retirees were excluded.

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: Cross-sectional prevalence analysis of medical surveillance data (chest X-rays classified by the ILO method, plus a smoking questionnaire)
• Who was studied: 45,647 civilian and uniformed US Navy employees enrolled in asbestos medical surveillance: 32,233 past or present smokers and 13,414 nonsmokers. Most were federally employed civilians from industrial facilities such as shipyards. Retirees were not included, and study years are not stated.
• Exposure: Ongoing or historic occupational asbestos exposure, with fiber types and doses not specified, compared by cigarette smoking status (past and present smokers grouped together as "smokers" vs nonsmokers)
• Main results:
  • Prevalence of small parenchymal opacities at ILO category 1/0 or higher was 3.10 percent in smokers vs 1.09 percent in nonsmokers (raw prevalence ratio 2.84)
  • The age-adjusted smoker:nonsmoker prevalence ratio at ILO 1/0 or higher was 2.23
  • Prevalence of ILO 1/0 or higher rose with age: from 0.12 percent (under 25) to 3.60 percent (over 55) in nonsmokers, and from 0.14 percent to 8.79 percent in smokers
  • Smokers had increased risk in all age groups, with no tendency to diminish with age. Ratios for those under 30 were unreliable because there were only nine positive readings.
  • The age-adjusted smoker:nonsmoker ratio was stable or tended to rise with severity, reaching 3.30 at ILO 2/1 or higher
• The authors' conclusion: The authors concluded that parenchymal opacities alone will not reliably distinguish the effects of asbestos exposure from those of smoking in people who have both risks
• Limitations the authors state:
  • Because everyone studied was in asbestos surveillance, the study could not address whether smoking alone causes opacities in people not exposed to asbestos
  • Recall bias in self-reported smoking history could not be excluded; the authors thought that, if present, it would likely understate the extra risk to smokers
  • Combining past and present smokers may overstate the risk to past smokers and underestimate it for current smokers
  • X-ray readers differ in their thresholds for perceiving abnormalities; the data pool the readings of 23 observers
  • Retirees were not included, so the excess risk to smokers could theoretically diminish at older ages

Topics

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

Medical terms in this study, explained in our Lexicon: Asbestos Exposure.

Related studies

• The degree of roentgenographic parenchymal opacities attributable to smoking among asbestos-exposed subjects — S. Barnhart, M. Thornquist, et al. (1990)
• Effect of tobacco smoking on the presence of asbestosis at postmortem and on the reading of irregular opacities on roentgenograms in asbestos-exposed workers — A. Kraut, J. Godbold, et al. (1989)
• Cigarette smoking and small irregular opacities — W. Weiss (1991)
• Effect of tobacco smoking on the presence of asbestosis at postmortem and on the reading of irregular opacities on roentgenograms in asbestos-exposed workers — E. Hnizdo, G.K. Sluis-Cremer (1988)
• The relation among pulmonary function, chest roentgenographic abnormalities, and smoking status in an asbestos-exposed cohort — L. Rosenstock, S. Barnhart, et al. (1988)
• The effect of cigarette smoking on the detection of small radiographic opacities in inorganic dust diseases — P.D. Blanc, G. Gamsu (1988)

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