Occupation and risk of malignant pleural mesothelioma: A case-control study in Spain

Our plain-English summary of Occupation and risk of malignant pleural mesothelioma: A case-control study in Spain, by A. Agudo, C.A. González, M.J. Bleda, et al (American Journal of Industrial Medicine, 2000).

The study

• Authors: A. Agudo, C.A. González, M.J. Bleda, J. Ramírez, S. Hernández, F. López, A. Calleja, R. Panadès, D. Turuguet, A. Escolar, M. Beltrán, J.E. González-Moya
• Journal: American Journal of Industrial Medicine
• Published: 2000;37(2):159-68
• Cited by: 89 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Background: The association of mesothelioma and asbestos exposure is well known, but some data suggest that probably many people are still being exposed to asbestos without knowing it.

Methods: Between 1993 and 1996, 132 cases (77% males) of histologically confirmed malignant pleural mesothelioma and 257 controls, residents in two provinces of Spain (Barcelona and C¿adiz), were interviewed. They were classified according to their probability and intensity of occupational asbestos exposure by a panel of industrial hygienists, based on a detailed occupational history.

Results: Age and sex-adjusted odds ratio (OR) for the highest probability of exposure to asbestos was 13.2 (95% confidence interval 6.4-27.3), and 27.1 (9. 28-79.3) for high intensity. A dose-response trend was observed for both, probability and intensity. Overall, 61% of cases and 42% of controls had ever worked in an occupation with risk of asbestos exposure, with an OR of 2.59 (1.60-4.22). In our population 62% of cases could be attributed to occupational asbestos exposure.

Conclusions: A high risk of pleural mesothelioma due to occupational asbestos exposure is confirmed, but there is still a sizeable proportion for which no evidence of occupational exposure was found. Most of these cases could be due to other sources of asbestos exposure, mainly domestic or environmental.

Copyright 2000 Wiley-Liss, Inc.

In plain English

This hospital-based case-control study examined occupational asbestos exposure and malignant pleural mesothelioma in Barcelona and Cádiz, Spain. The authors interviewed 132 people diagnosed in 1993 to 1996 (77% men; relatives answered for 59) and 257 hospital patients as controls. Industrial hygienists, blind to who was a case, rated each person's jobs for probability and intensity of asbestos exposure. Against people who never worked or were rated not occupationally exposed, odds ratios adjusted for center, sex and age were 13.2 (95% confidence interval 6.44 to 27.3) for sure exposure, 27.1 (9.28 to 79.3) for high intensity, and 41.6 (12.3 to 140) for both. Risk rose with both probability and intensity. Overall, 61% of cases and 42% of controls had ever held a job judged at risk of asbestos exposure (odds ratio 2.59, 1.60 to 4.22, against people who never held such jobs). An estimated 62% (48.4 to 75.6%) of cases in this population could be attributed to occupational exposure of any probability. They concluded that most remaining cases could be due to other, mainly domestic or environmental, asbestos sources.

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: Case-control study with hospital controls frequency-matched to cases by sex and age
• Who was studied: 132 of 134 eligible residents of the provinces of Barcelona and Cádiz, Spain, newly diagnosed with histologically confirmed malignant pleural mesothelioma between 1993 and 1996 (102 men, 30 women), and 257 hospital patient controls (of 297 identified). Patients admitted with asbestos-related conditions were excluded as controls. Relatives answered for 59 cases.
• Exposure: Occupational asbestos exposure, estimated from detailed job histories and job-specific questionnaires. A panel of industrial hygienists, blinded to case or control status, rated each job by probability of exposure (none, low, possible, highly probable, sure, unknown) and by intensity (background, three increasing levels, unknown). Fiber types were not assessed.
• Main results:
  • The reference group was people who never worked or were considered never exposed. Compared with them, the center, sex and age-adjusted odds ratio was 13.2 (95% CI 6.44 to 27.3) for sure exposure (53 cases, 29 controls). It was 27.1 (95% CI 9.28 to 79.3) for the highest intensity of exposure (22 cases, 6 controls). A dose-response trend was seen for both probability and intensity.
  • For subjects with sure exposure at the highest intensity, the odds ratio was 41.6 (95% CI 12.3 to 140; 22 cases, 4 controls).
  • 61% of cases and 42% of controls had ever worked in an occupation judged at risk of asbestos exposure (81 cases, 109 controls). Compared with the 51 cases and 148 controls who never worked in such occupations, the odds ratio was 2.59 (95% CI 1.60 to 4.22).
  • In this study population, the authors estimated that 62% (95% CI 48.4 to 75.6) of cases could be attributed to occupational asbestos exposure when all probability categories were included, and 37.1% (95% CI 28.1 to 46.1) to sure exposure.
  • Twelve subjects, all male cases, had worked in asbestos cement manufacture at one large plant in Barcelona province. The occupation group 'manufacture of non-metallic products' had an odds ratio of 21.17 (95% CI 4.45 to 101; 12 cases, 2 controls).
  • 14 men (10 cases, 4 controls) had worked in companies building and repairing ships and boats. Their odds ratio was 11.9 (95% CI 3.15 to 44.8).
  • Smoking prevalence was similar in cases and controls. Relative risks for smoking and for past radiation exposure were close to 1 and were not presented.
• The authors' conclusion: The authors concluded that a high risk of pleural mesothelioma from occupational asbestos exposure was confirmed. For a sizeable share of cases no occupational exposure was found, and the authors suggested that most of those cases could be due to other asbestos sources, mainly domestic (including family contacts) or environmental.
• Limitations the authors state:
  • Information for 44% of cases came from a relative, while controls answered for themselves. The authors argued that any resulting bias would be toward underestimating risk.
  • In a check of 18 cases, agreement between exposure ratings based on the subject's own answers and on a relative's answers was moderate. It was higher for spouses than for sons or daughters.
  • The authors called the raised risk for printers surprising. It rested on very few subjects, and asbestos exposure in other jobs these subjects held could not be ruled out.
  • The authors stated that some misclassification of exposure could not be ruled out.

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, Case-Control Study, Mesothelioma, Asbestos Exposure, Occupational History, Odds Ratio, confidence interval, Dose-response relationship.

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