Asbestos and man-made vitreous fibers as risk factors for diffuse malignant mesothelioma: results from a German hospital-based case-control study

Our plain-English summary of Asbestos and man-made vitreous fibers as risk factors for diffuse malignant mesothelioma: results from a German hospital-based case-control study, by K. Rödelsperger, K.H. Jöckel, H. Pohlabeln, et al (American Journal of Industrial Medicine, 2001).

The study

• Authors: K. Rödelsperger, K.H. Jöckel, H. Pohlabeln, W. Römer, H.J. Woitowitz
• Journal: American Journal of Industrial Medicine
• Published: 2001;39(3):262-75
• Cited by: 47 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Background: This study examines the role of occupational factors in the development of diffuse malignant mesothelioma with special emphasis on the dose-response relationship for asbestos and on the exposure to man-made vitreous fibers (MMVFs).

Methods: One hundred and twenty-five male cases, diagnosed by a panel of pathologists, were personally interviewed concerning their occupational and smoking history. The same number of population controls (matched for sex, age and region of residence) underwent similar interviews by trained interviewers. Odds ratios (OR) were calculated for an expert-based exposure index using conditional logistic regression.

Results: Exposure to asbestos shows the expected sharp gradient with an OR of about 45 for a cumulative exposure > 1.5 fiber years (arithmetic mean 16 fiber years). A significant OR was calculated even for the lowest exposure category "> 0 - < or = 0.15 fiber years". Although the mean cumulative exposure to MMVF is roughly 10% of the exposure to asbestos, an increased OR is observed in an ever/never evaluation. This observation is heavily hampered by methodical problems. A corresponding case-control study was performed using a lung tissue fiber analysis in addition to interviews. Both interviews and the lung tissue analysis yielded similar OR levels between the reference and the maximum exposure intervals.

Conclusions: Despite a possible influence as a result of selection and information bias, our results confirm the previously reported observation of a distinct dose-response relationship even at levels of cumulative exposure below 1 fiber year. Moreover, the study confirms that asbestos is a relevant confounder for MMVF. A causal relationship between exposure to MMVF and mesothelioma could neither be detected nor excluded, as in other studies.

Copyright 2001 Wiley-Liss, Inc.

In plain English

This German case-control study compared 125 men with diffuse malignant mesothelioma, treated at two Hamburg hospitals between 1988 and 1991 and confirmed by a panel of pathologists, with 125 population controls matched for sex, age and region. Trained interviewers recorded work histories. An industrial hygienist, working blind to case status, estimated each man's cumulative exposure to asbestos and to man-made vitreous fibers (MMVF) in fiber years. The type of asbestos was unknown. The odds of mesothelioma rose with estimated asbestos exposure. Compared with unexposed men, the odds ratio was 7.9 (95% CI 2.1 to 30.0) for more than 0 up to 0.15 fiber years and 47.1 (11.5 to 193) for more than 1.5 to 15 fiber years. For ever exposure to MMVF the odds ratio was 6.12, falling to 3.08 (1.17 to 8.07) after adjustment for asbestos. The authors concluded that there was a distinct dose-response relationship for asbestos even below 1 fiber year. They concluded that a causal link between MMVF and mesothelioma could neither be proven nor excluded. They cautioned that the size of the odds ratios was uncertain.

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: mesothelioma cases from Hamburg hospitals individually matched to population controls; exposure estimated by expert assessment of interview data; conditional logistic regression
• Who was studied: 125 male cases of diffuse malignant mesothelioma (from 137 male and 37 female cases treated at two specialized Hamburg hospitals, recruited 1 January 1988 to 31 December 1991), and 125 male population controls matched for region of residence, sex and year of birth (within 5 years). Women were excluded because of small numbers.
• Exposure: Occupational exposure to asbestos (type not known) and to man-made vitreous fibers, estimated by an expert industrial hygienist from interview job histories as cumulative fiber years (fibers/ml years), blind to case or control status
• Main results:
  • Lowest cumulative asbestos category (more than 0 to 0.15 fiber years): 14 cases and 12 controls, odds ratio 7.9 (95% CI 2.1 to 30.0), compared with not exposed (11 cases, 67 controls)
  • Cumulative asbestos more than 0.15 to 1.5 fiber years: 38 cases and 25 controls, odds ratio 21.9 (95% CI 5.7 to 83.8)
  • Cumulative asbestos more than 1.5 to 15 fiber years: 46 cases and 16 controls, odds ratio 47.1 (95% CI 11.5 to 193). More than 15 fiber years: 16 cases and 5 controls, odds ratio 45.4 (95% CI 8.1 to 257)
  • More than 30 years' duration of asbestos exposure: 49 cases and 15 controls, odds ratio 43.7 (95% CI 10.8 to 177)
  • High peak intensity of asbestos exposure: 63 cases and 21 controls, odds ratio 46.3 (95% CI 12.1 to 178)
  • For time since first asbestos exposure, the odds ratio stayed roughly constant across categories. The authors attributed this to matching on year of birth.
  • Occupation of mechanics, fitters and plumbers (ever held): 62 cases and 21 controls, odds ratio 2.82, statistically significant
  • Engine and vehicle building industry (ever worked): 82 cases and 45 controls, odds ratio 3.18, statistically significant
  • Ever exposure to MMVF: 55 cases and 14 controls. The odds ratio was 6.12 (95% CI 2.90 to 12.93), and 3.08 (95% CI 1.17 to 8.07) after adjustment for asbestos.
  • After adjustment for asbestos, the odds ratios for the separate MMVF dose categories were no longer statistically significant
  • Men exposed to MMVF but not asbestos (2 cases, 2 controls, mean 0.6 fiber years) had an odds ratio of 15.1 (95% CI 1.05 to 218), compared with men exposed to neither (9 cases, 65 controls). The authors said this was severely hampered by exposure-estimation problems.
  • When a separate series of 125 hospital controls (mainly lung cancer patients) was used instead of population controls, the maximum odds ratio fell from 100 to about 10
• The authors' conclusion: The authors concluded that their results confirm a distinct dose-response relationship between asbestos and mesothelioma even at cumulative exposures below 1 fiber year
• Limitations the authors state:
  • Few pairs had an exposed control and an unexposed case, so the authors said the absolute size of the odds ratios should be regarded with caution
  • Interviewing patients versus healthy population controls likely introduced information bias that increases the risk estimate
  • The type of asbestos (chrysotile or amphibole) was unknown
  • Cumulative exposure to MMVF was likely overestimated, because one common exposure duration was used where asbestos and MMVF were used together
  • Only men from Hamburg were included, so results are not representative of the German population as a whole
  • Given problems of dose estimation and sample size, the authors stated that a causal relationship between MMVF and mesothelioma could neither be proven nor excluded

Topics

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

Medical terms in this study, explained in our Lexicon: Vitreous, Malignant Mesothelioma, Case-Control Study, Dose-response relationship, Odds Ratio, Cumulative Exposure, Fiber Year, Mesothelioma.

Related studies

• Lung cancer and exposure to man-made vitreous fibers: results from a pooled case-control study in Germany — H. Pohlabeln, K.H. Jöckel, et al. (2000)
• Occupational exposure to asbestos and man-made vitreous fibers, and risk of lung cancer: evidence from two case-control studies in Montreal, Canada — J. Pintos, M.E. Parent, et al. (2008)
• Risk of mesothelioma and occupational exposure to asbestos and man-made vitreous fibers: evidence from two case-control studies in Montreal, Canada — J. Pintos, M.E. Parent, et al. (2009)
• Laryngeal and hypopharyngeal cancer and occupational exposure to asbestos and man-made vitreous fibers: results of a case-control study — J.L. Marchand, D. Luce, et al. (2000)
• Occupational exposure to asbestos and man-made vitreous fibres and risk of lung cancer: a multicentre case-control study in Europe — R. Carel, A.C. Olsson, et al. (2007)
• Occupational risk factors for lung cancer in women: results of a case-control study in Germany — I. Jahn, W. Ahrens, et al. (1999)

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