Time trends and occupational risk factors for pleural mesothelioma in Sweden

Our plain-English summary of Time trends and occupational risk factors for pleural mesothelioma in Sweden, by K. Hemminki, X. Li (Journal of Occupational and Environmental Medicine, 2003).

The study

• Authors: K. Hemminki, X. Li
• Journal: Journal of Occupational and Environmental Medicine
• Published: 2003;45(4):456-61
• Cited by: 30 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Epidemiologic data on pleural mesothelioma are scarce on regional and occupational time trends, which would monitor the effects of changes in exposure to asbestos. We aim to characterize time trends, regional, socioeconomic, and occupational risk factors for pleural mesothelioma in Sweden in the years from 1961 to 1998. The Swedish Family-Cancer Database was used to identify patients with pleural mesothelioma. Age-standardized incidence rates and standardized incidence ratio (SIR) were calculated for the population in the Database. A total of 1298 male and 233 female pleural mesotheliomas were retrieved. Age-standardized incidence of the disease was highest, and the trend increased in residents of large industrial and shipbuilding cities. In the last follow-up period, the male rate exceeded the female rate about 10-fold. Among male socioeconomic groups, manual workers showed the highest and ever-increasing SIR. No female socioeconomic group was at risk. For men, plumbers and seamen had the highest risk of 4.56 and 2.83, respectively, but the risks appeared to be decreasing for plumbers, whereas no clear trend was noted for seamen, probably because of indirect expose in ships. Farmers showed an SIR of 0.28, indicating that the population at large was at four times higher risk than farmers. The SIRs of many academic/college-educated groups were two to six times higher than those of farmers, suggesting indirect exposure to asbestos in these groups.

In plain English

This study used the Swedish Family-Cancer Database to examine pleural mesothelioma in Sweden from 1961 to 1998, finding 1298 cases in men and 233 in women. Asbestos exposure was not measured; the authors compared occupations, socioeconomic groups and regions recorded in the 1960 census. Among men, incidence rose in all regions, most steeply in the shipbuilding cities of Malmo and Gothenburg. In 1996 to 1998, women's rates were about one tenth of men's. Compared with all men, plumbers had a standardized incidence ratio (SIR) of 4.56 (95% confidence interval 3.42 to 5.95) and seamen 2.83 (1.41 to 5.09), while farmers had 0.28 (0.19 to 0.39). Seamen from the Gothenburg area recorded in 1960 had an SIR of 7.43 (10 cases, 3.54 to 13.72). Among women, textile workers and building caretakers and cleaners had SIRs of 2.41 (1.24 to 4.22) and 2.32 (1.19 to 4.06), each based on 12 cases. Incidence rose over time for mechanics and electrical workers but fell for bricklayers and plumbers. The authors suggested an environmental, particularly urban, source of exposure. They noted that they could not assess past underreporting.

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: Registry-based follow-up study using the Swedish Family-Cancer Database, calculating age-standardized incidence rates and standardized incidence ratios (SIRs) by region, socioeconomic group and occupation
• Who was studied: 1298 men and 233 women with pleural mesothelioma recorded in the Swedish Family-Cancer Database (cancer data from the Swedish Cancer Registry), Sweden, 1961 to 1998
• Exposure: Asbestos exposure was not measured directly. Occupation, socioeconomic group and region of residence were taken from the 1960 national census, with occupation also from the 1970 census for some analyses.
• Main results:
  • Among men, incidence increased in all regions. The steepest increase was in residents of Malmo and Gothenburg, the two shipbuilding centers.
  • In the last period, 1996 to 1998, female rates were about one tenth of male rates.
  • Among male socioeconomic groups in the last period, incidence was 0.59 per 100,000 in agriculture and 2.96 per 100,000 in manual workers, a 5-fold difference.
  • No female socioeconomic group differed in risk from all women.
  • Among men followed 1961 to 1998, plumbers had the highest SIR, 4.56 (54 cases, 95% CI 3.42 to 5.95). Other significant increases were seamen 2.83 (11 cases, 95% CI 1.41 to 5.09), bricklayers 2.23, mechanics 1.95, electrical workers 1.92, welders 1.86, chemical process workers 1.57, construction workers 1.48, woodworkers 1.34, and academic occupations in natural sciences 1.22.
  • Among men followed 1961 to 1998, farmers had an SIR of 0.28 (35 cases, 95% CI 0.19 to 0.39). Gardeners had 0.33, religious occupations 0.33, forestry workers 0.34, and food-manufacturing workers 0.45.
  • Among men with the same occupation in 1960 and 1970 (follow-up 1970 to 1998), the SIR for seamen was no longer significant (1.98, 95% CI 0.51 to 5.12). Building caretakers and cleaners showed an increased SIR of 2.41 (95% CI 1.15 to 4.44).
  • Seamen from the Gothenburg area recorded in 1960 had an SIR of 7.43 (10 cases, 95% CI 3.54 to 13.72), the highest in the study. Ten of the 11 mesothelioma cases among all Swedish seamen came from the Gothenburg area.
  • Among women with occupations recorded in 1960, the only significant SIRs were increases: textile workers 2.41 (12 cases, 95% CI 1.24 to 4.22) and building caretakers and cleaners 2.32 (12 cases, 95% CI 1.19 to 4.06).
  • Over time, incidence rose steadily for mechanics and electrical workers and fell for bricklayers and plumbers.
• The authors' conclusion: The authors concluded that the low risk among farmers, compared with academic and college-educated groups unlikely to have occupational exposure, suggests an environmental, particularly urban, source of exposure.
• Limitations the authors state:
  • The authors could not assess whether mesothelioma was underreported in the past. Underreporting may have affected regions and occupations differently.
  • Time trends differ slightly between the Family-Cancer Database and the Swedish Cancer Registry.
  • The seamen result could be confounded if unskilled dockyard workers were later recruited to ships.

Topics

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

Medical terms in this study, explained in our Lexicon: Pleural Mesothelioma, Incidence, Standardized Incidence Ratio (SIR).

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