Recent geographic patterns of lung cancer and mesothelioma mortality rates in 49 shipyard counties in the United States, 1970-94

Our plain-English summary of Recent geographic patterns of lung cancer and mesothelioma mortality rates in 49 shipyard counties in the United States, 1970-94, by A. Jemal, D. Grauman, S. Devesa (American Journal of Industrial Medicine, 2000).

The study

• Authors: A. Jemal, D. Grauman, S. Devesa
• Journal: American Journal of Industrial Medicine
• Published: 2000;37(5):512-21
• Cited by: 21 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Background: Lung cancer mortality rates among white males in the United States were observed to be elevated during 1950-69 in counties with shipbuilding industries during World War II; risk was found to be associated with asbestos exposure. We evaluated the geographic patterns in more recent years, 1970-94, for whites and compared them with the 1950-69 patterns.

Methods: We calculated age-adjusted rates and estimated rate ratios between comparison groups.

Results: Rates generally were higher in shipyard counties than in all nonshipyard counties and in coastal nonshipyard counties for both sexes and time periods. Rates increased markedly from 1950-69 to 1970-94 in all groups, with the changes more pronounced in females than males. Pleural mesothelioma mortality rates were also significantly higher in shipyard counties than coastal nonshipyard counties in all regions among males but not among females.

Conclusions: The more pronounced changes in lung cancer mortality rates among females in shipyard counties may be attributed to the combined effects of low asbestos exposures and changes in smoking behavior. Am. J. Ind. Med. 37:512-521, 2000. Published 2000 Wiley-Liss, Inc.

In plain English

This ecological study compared death rates among whites in 49 U.S. counties with World War II shipbuilding against all other counties and 222 coastal counties without shipyards. It compared 1970-94 with 1950-69. Among white men, lung cancer rates were significantly higher in shipyard than nonshipyard counties in every region except the Midwest, in both periods. Comparing only with coastal counties generally shrank the differences. Rates rose over time; later-to-earlier rate ratios were twice as high among women as men. The proportion of the 49 shipyard counties with lung cancer rates in the top 10% of all counties rose from 22.4% to 51.0% for women but fell from 53.0% to 14.3% for men. For pleural mesothelioma in 1970-94, men in shipyard counties had significantly higher rates than men in coastal nonshipyard counties (rate ratios 1.2 in the Northeast to 2.3 in the West). Differences among women were not significant. The authors suggested the larger changes in women's lung cancer rates in shipyard counties may reflect low asbestos exposure combined with changes in smoking. County smoking data were unavailable.

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: Ecological (county-level) study of mortality rates, using national death records and census population estimates to compute age-adjusted rates and rate ratios between groups of counties
• Who was studied: Whites residing in the 49 U.S. counties where 2000-ton ships were built or repaired during World War II, compared with all other (nonshipyard) counties and with a subgroup of 222 coastal nonshipyard counties. Deaths in 1970-94 were compared with deaths in 1950-69, and results were analyzed by region (Midwest, Northeast, South, West), urban or rural status, and population size.
• Exposure: Residence in a county where 2000-ton ships were built or repaired during World War II. Asbestos exposure was not measured or linked to individuals, and no fiber types are specified.
• Main results:
  • Among white males, lung cancer mortality was significantly higher in shipyard than nonshipyard counties in all regions except the Midwest, during both time periods
  • Among white females, lung cancer rates were also elevated in shipyard counties in all regions except the Midwest, but not always significantly
  • Comparing shipyard counties only with the 222 coastal nonshipyard counties generally reduced the rate ratios, which fell below one in several instances, more so in rural than urban counties. For white males in the urban South in 1970-94, the shipyard-to-coastal-nonshipyard ratio was 1.31 (95% CI 1.29 to 1.33).
  • Lung cancer rates rose from 1950-69 to 1970-94 among both sexes. The ratios of later to earlier rates were twice as high among females as among males.
  • Of the 49 shipyard counties, the proportion whose lung cancer rates ranked in the top 10% of county rates rose from 22.4% (11 counties) in 1950-69 to 51.0% (25 counties) in 1970-94 for females. For males it dropped from 53.0% (26 counties) to 14.3% (7 counties).
  • Pleural mesothelioma mortality among white males in 1970-94 was significantly higher in shipyard than coastal nonshipyard counties in each region. Shipyard-to-coastal-nonshipyard rate ratios ranged from 1.2 in the Northeast to 2.3 in the West (table: Northeast 1.21, 95% CI 1.05 to 1.40; West 2.27, 95% CI 1.93 to 2.66).
  • Among white females, pleural mesothelioma rates were higher in shipyard counties in the South and West and lower in the Midwest and Northeast, but none of the differences was statistically significant
  • Accounting for population size had very little influence on the shipyard versus nonshipyard comparisons. Ranking shipyard counties by the share of the population employed in wartime shipbuilding showed a slight but unconvincing pattern.
• The authors' conclusion: The authors concluded that the more pronounced changes in lung cancer mortality among females in shipyard counties may be attributed to the combined effects of low asbestos exposures and changes in smoking behavior. They raised possible low-level exposure occupationally or from contaminated household environments, and a longer latent period linked to women's later adoption of smoking.
• Limitations the authors state:
  • Exposure was not linked to individuals
  • Data on cigarette smoking prevalence were unavailable at the county level, so differences in smoking could not be investigated
  • Women married to shipyard workers may have been more likely to smoke than women married to nonshipyard workers
  • The authors could not find data to separate the shipyard counties by whether shipbuilding continued after the war
  • Because data were sparse, pleural mesothelioma rates were analyzed only by region and only for 1970-94
  • Few shipyard counties in the West were urban, so most comparisons in the West were not statistically significant

Topics

The National Library of Medicine indexes this study under subjects our site covers: Lung cancer, Mesothelioma, Shipyards and maritime work.

Medical terms in this study, explained in our Lexicon: Lung Cancer, Mesothelioma, Asbestos Exposure, rate ratio, Pleural Mesothelioma.

Related studies

• Lung cancer mortality in the United States: shipyard correlations — W.J. Blot, J.F. Fraumeni (1979)
• Asbestos disease in United States shipyards — I.J. Selikoff, R. Lilis, et al. (1979)
• Cancer mortality in U.S. counties with shipyard industries during World War II — W.J. Blot, B.J. Stone, et al. (1979)
• Why are lung cancer rate trends so different in the United States and United kingdom? — P.N. Lee, B.A. Forey (2003)
• Asbestos-associated disease in United States shipyards — I.J. Selikoff, E.C. Hammond (1978)
• Changing patterns of lung cancer in the United States — W.J. Blot, J.F. Fraumeni (1982)

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