Genetic polymorphism for glutathione-S-transferase mu in asbestos cement workers

Our plain-English summary of Genetic polymorphism for glutathione-S-transferase mu in asbestos cement workers, by K. Jakobsson, A. Rannug, A.K. Alexandrie, et al (Occupational and Environmental Medicine, 1994).

The study

• Authors: K. Jakobsson, A. Rannug, A.K. Alexandrie, L. Rylander, M. Albin, L. Hagmar
• Journal: Occupational and Environmental Medicine
• Published: 1994;51(12):812-6
• Cited by: 19 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Objective: To investigate whether a lack of glutathione-S-transferase mu (GSTM1) activity was related to an increased risk for adverse outcome after asbestos exposure.

Methods: A study was made of 78 male former asbestos cement workers, with retrospective cohort data on exposure, radiographical findings, and lung function. Venous blood samples were obtained for the analysis of GSTM1 polymorphism by the polymerase chain reaction technique. Chest x ray films were classified according to the International Labour Organisation (ILO) 1980 classification. Vital capacity (VC) and forced expiratory volume during 1 s (FEV1) were determined. Individual estimates of asbestos exposure were calculated, and expressed as duration of exposure, average exposure intensity, and cumulative dose. Data on smoking were obtained from interviews.

Results: The lung function in the study group was reduced, compared with reference equations. 23% of the workers had small opacities > or = 1/0, 29% circumscribed pleural thickenings, 14% diffuse thickenings, and 12% obliterated costophrenic angles. 54% of the workers were GSTM1 deficient. They were comparable with the other workers in age, follow up time (median 30 years), and duration of exposure (median 18 years), but had a slightly higher cumulated dose (median 18 v 10 fibre-years) than the others. Neither in radiographical changes nor lung function variables were there any differences between the different GSTM1 groups. The findings were similar when smoking habits and estimated asbestos exposure were taken into account.

Conclusions: We could not show that lack of GSTM1 activity was related to an increased risk for radiographical or lung function changes in a group of asbestos cement workers, followed up for a long period after the end of exposure.

In plain English

This study, from Lund, Sweden, examined whether men lacking the gene for the enzyme glutathione-S-transferase mu (GSTM1), which the authors suggested may help remove active oxygen species, had more lung or pleural changes after asbestos exposure. The authors genotyped 78 of 95 surviving men with more than 10 years at one asbestos cement plant, an earlier health examination and classified chest x rays. They compared genotype with chest x rays, lung function tests and individual exposure estimates. Overall, 54% lacked GSTM1. This group had a higher median cumulative dose (18 v 10 fibre-years). Small opacities, pleural thickening and costophrenic angle obliteration were similarly distributed in both groups. Lung function showed no significant differences, including after accounting for exposure. With cumulative dose taken into account, the odds ratio for small opacities of profusion 1/0 or greater in GSTM1-deficient men was 0.8 (95% CI 0.3 to 2.1). The authors concluded they could not show radiographical or lung function differences between genotypes. They noted that most men had low or moderate exposure, so differences in more severe parenchymal (lung tissue) disease could not be evaluated.

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 genetic study within a retrospective cohort of former asbestos cement workers: GSTM1 genotype (by PCR) compared with chest x ray findings and lung function
• Who was studied: Of 95 male former workers at one asbestos cement plant (operating from 1907 and closed in 1977), 78 gave blood samples. The 95 were men alive on 15 March 1993 with more than 10 years of employment, at least one earlier health examination at the Department of Occupational and Environmental Medicine in Lund, Sweden, and ILO-classified chest x rays. Of the 78, 42 were GSTM1(-) and 36 were GSTM1(+).
• Exposure: Asbestos exposure in asbestos cement manufacturing (fiber types not named in this article), estimated individually as duration of employment, average intensity (f/ml) and cumulative dose (fibre-years). Median employment was 19 years (GSTM1(-)) and 17 years (GSTM1(+)).
• Main results:
  • 54% of the 78 workers had the GSTM1(-) genotype (lacking GSTM1).
  • The GSTM1(-) group had higher exposure than the GSTM1(+) group: median cumulative dose 18 v 10 fibre-years (P = 0.02) and median average intensity 1.0 v 0.6 f/ml (P = 0.05).
  • Across all participants, 23% had small opacities of profusion 1/0 or greater, 29% circumscribed pleural thickenings, 14% diffuse thickenings and 12% obliterated costophrenic angles. Lung function in the group was reduced compared with reference equations.
  • Radiographic abnormalities, both parenchymal and pleural, were similarly distributed in the GSTM1(-) and GSTM1(+) groups.
  • Adjusted for age, smoking and cumulative dose, the odds ratio for small opacities of profusion 1/0 or greater in GSTM1(-) men compared with GSTM1(+) men was 0.8 (95% CI 0.3 to 2.1). The OCR text prints the threshold as '>1/10'; the abstract (1/0 or greater), table 2 categories and the discussion confirm 1/0.
  • FEV1 was slightly higher in the GSTM1(-) group, but not significantly (P = 0.21 uncorrected for smoking; P = 0.41 corrected). There were no consistent differences in vital capacity. After accounting for exposure, there were no significant differences between genotype groups for VC or FEV1.
  • The 17 non-participants did not have more severe radiographic or lung function changes than the participants.
• The authors' conclusion: The authors concluded that they could not show that lack of GSTM1 activity was related to an increased risk of radiographical or lung function changes in these asbestos cement workers.
• Limitations the authors state:
  • Exposure was low or moderate for most workers and few had more advanced x ray changes. The authors said true differences between genotypes for more severe parenchymal disease may exist but could not be evaluated in this group.
  • The study group was only of moderate size, although the authors judged its statistical power reasonable.
  • The men studied were survivors of a cohort with excess mortality. The authors considered whether GSTM1(-) men might be under-represented because of early deaths, but judged selective survival bias an unlikely explanation for their findings.

Topics

Medical terms in this study, explained in our Lexicon: Glutathione (GSH), Asbestos-Cement, Asbestos Exposure, FEV1, Cumulative Dose, Pleural Thickening, Costophrenic angle, Habit.

Related studies

• Radiographic changes and lung function in relation to activity of the glutathione transferases theta and mu among asbestos cement workers — K. Jakobsson, A. Rannug, et al. (1995)
• Polymorphism of glutathione S-transferase M1 and lung cancer risk among African-Americans and Caucasians in Los Angeles County, California — S.J. London, A.K. Daly, et al. (1995)
• Glutathione S-transferases GSTM1 and GSTT1 polymorphisms and asbestosis — A. Franko, M. Dodic-Fikfak, et al. (2007)
• Polymorphisms of glutathione-S-transferase M1 and manganese superoxide dismutase are associated with the risk of malignant pleural mesothelioma — S. Landi, F. Gemignani, et al. (2007)
• Glutathione S-transferase and N-acetyltransferase genotypes and asbestos-associated pulmonary disorders — A. Hirvonen, S.T. Saarikoski, et al. (1996)
• Vitamin C levels in blood are influenced by polymorphisms in glutathione S-transferases — A. Horska, C. Mislanova, et al. (2011)

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