Asbestos exposure and autoantibody titers

Our plain-English summary of Asbestos exposure and autoantibody titers, by E. Lee, Y. Kim, S.Y. Kim, et al (Annals of Occupational and Environmental Medicine, 2020).

The study

• Authors: E. Lee, Y. Kim, S.Y. Kim, D. Kang
• Journal: Annals of Occupational and Environmental Medicine
• Published: 2020;32:e32
• Cited by: 3 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Background: Asbestos is a well-known hazardous substance that causes occupational and environmental diseases including asbestosis (lung fibrosis). Silica exposure which causes silicosis (another type of lung fibrosis) has long been linked to the development of autoimmune diseases; however, there are few studies on the relationship between asbestos exposure and autoimmune diseases.

Methods: A total of 54 individuals who had worked in a former asbestos textile factory underwent autoantibody-related blood tests, chest X-ray imaging, and pulmonary function tests. Based on the job exposure matrix (JEM), the estimated asbestos exposure concentrations were determined, and the presence of asbestosis was determined by chest radiography.

Results: Scleroderma (Scl-70) and ribonucleoprotein (RNP) antibodies were significantly lowered in the pleural plaque present group than in the absent group. Additionally, Scl-70, RNP, and Sjögren's syndrome type B (SS-B) antibodies were significantly lowered in the asbestosis present group. When stratifying variables with or without asbestosis, Scl-70, Smith, SS-B, and RNP antibodies decreased in female, crocidolite handling group, and higher estimated asbestos exposure level group.

Conclusions: Contrary to our expectations that autoantibody titers would be higher in groups with high asbestos exposure or in the asbestosis group, those with asbestosis showed lower titers. But as our research has some methodological limitations, the lowered titer of autoimmune antibody in our asbestos exposed subjects could not be simply interpreted as a lowered risk of autoimmune diseases. So careful interpreting should be taken when examine autoantibodies to screening or diagnose autoimmune diseases in people with asbestos exposure. In addition, it is necessary to establish relevance of asbestosis and autoantibodies through further studies of larger scale and higher confidence levels.

Copyright © 2020 Korean Society of Occupational & Environmental Medicine.

In plain English

This cross-sectional study measured blood autoantibodies, proteins that can appear before autoimmune diseases, in 54 people who had worked at J Chemical, an asbestos textile factory in Busan, Korea. None had a diagnosed autoimmune disease. In 2010 they had blood tests, chest X-rays and lung function tests. The workers had handled chrysotile, crocidolite or both, and their exposure was estimated with a job exposure matrix. Few tested positive for autoantibodies (rheumatoid factor 11%, ANA 3.7%). Chest X-rays showed asbestosis in 37% and pleural plaques in 27.8%. Estimated exposure level, fiber type, work period and time since leaving work were not significantly linked to antibody levels. Scl-70 and RNP levels were significantly lower in people with asbestosis or pleural plaques, and SS-B was lower in those with asbestosis. The authors concluded that the results did not show a positive relationship between asbestos exposure and autoantibodies. They thought the inverse findings were likely accidental, given the study's limitations. They noted the small sample and that asbestosis was judged only from routine chest X-rays.

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: Small cross-sectional study of autoantibody levels in former asbestos textile workers
• Who was studied: 54 former workers of J Chemical, described as the largest asbestos textile factory in Korea, in Busan, Republic of Korea. They were tested from September 27 to October 2, 2010 at Pusan National University Yangsan Hospital. None had a previously diagnosed autoimmune disease. 55.6% were women, and the average age was 57.3 years.
• Exposure: Occupational asbestos exposure in textile work, including carding, twisting, weaving, spinning, gaskets, fixing, managing and packaging. Workers handled chrysotile (63.0%), crocidolite (20.4%) or both (16.7%). Exposure was estimated with a job exposure matrix and grouped as less than 1, 1 to 10, and 10 or more f-year/cc. The average was 2.3 f-year/cc.
• Main results:
  • Few participants tested positive for autoantibodies: RF 11%, ANA 3.7%, ACA and RNP 1.9%. All other autoantibodies were negative, so titers were analysed as quantities rather than as positive or negative.
  • Chest X-ray showed asbestosis in 37% (20 of 54) and pleural plaque in 27.8% (15 of 54) of participants.
  • Smoking history, work period, latent period, type of asbestos handled and estimated exposure level were not significantly associated with autoantibody titers.
  • Scl-70 and RNP were significantly lower in people with pleural plaque or asbestosis. Geometric mean Scl-70 was 0.02 with plaque vs 0.09 without (p less than 0.01), and 0.02 with asbestosis vs 0.10 without (p less than 0.01). RNP was 0.10 with plaque vs 0.18 without, and 0.10 with asbestosis vs 0.19 without (p less than 0.05).
  • SS-B was also lower in the asbestosis group: geometric mean 0.03 with asbestosis vs 0.09 without (p less than 0.05).
  • No autoantibody was significantly associated with lung function test results.
  • ANA titer was significantly higher in women than in men. Smith and SS-B titers decreased significantly with age.
  • In analyses split by subgroup, Scl-70, Smith, SS-B and RNP were significantly lower with asbestosis among women and among the crocidolite-handling group (11 people: 4 without and 7 with asbestosis).
  • By exposure level, Scl-70 was significantly lower with asbestosis in the group exposed to over 10 f-year/cc. SS-B was lower with asbestosis in the 1 to 10 and over 10 f-year/cc groups.
  • Two participants who had positive autoantibodies were diagnosed with autoimmune-related diseases years later. One had p-ACA associated rapid progressive glomerulonephritis and the other had ANA-positive undifferentiated connective tissue disease. Both were in the highest estimated exposure group.
• The authors' conclusion: The authors concluded that the results did not show that asbestos exposure and autoantibodies were positively related. They said the clinical significance of the inverse associations is uncertain, and that the lowered titers could not simply be interpreted as a lowered risk of autoimmune diseases. They called for larger, more reliable studies.
• Limitations the authors state:
  • The authors thought the inverse associations were likely an accidental finding due to the study's limitations.
  • The small, limited sample may have left out people with autoimmune disease or severe asbestosis.
  • Asbestosis was diagnosed only from routine chest X-rays, which the authors describe as having low validity and reliability; Korean criteria rely on CT.
  • Interstitial lung disease linked to autoimmune disease could not be ruled out as being misdiagnosed as asbestosis.
  • The fiber exposures differed from earlier studies (tremolite at Libby, crocidolite at Wittenoom, both mixed with other minerals). These workers handled purified chrysotile and crocidolite.
  • Most test results were at subclinical levels, so their clinical meaning is hard to judge. The study could not confirm a direct association with autoimmune diseases.
  • The proportion of women was high, unlike earlier studies that mainly involved men, which may affect the results.
  • The study is small and cross-sectional, so its results are difficult to generalize.

Topics

Medical terms in this study, explained in our Lexicon: Asbestos Exposure, Fibrosis, Silicosis, Chest X-Ray, Pulmonary Function Test (PFT), Pleural Plaques, Crocidolite.

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• Analysis of autoantibody profiles in two asbestiform fiber exposure cohorts — J.C. Pfau, C. Barbour, et al. (2018)
• Reconstruction of the Korean Asbestos Job Exposure Matrix — D. Kang, S. Jung, et al. (2021)
• Activity-Based Exposure Levels and Cancer Risk Assessment Due to Naturally Occurring Asbestos for the Residents Near Abandoned Asbestos Mines in South Korea — S. Lee, D. Kang, et al. (2021)
• Predicting the mortality from asbestos-related diseases based on the amount of asbestos used and the effects of slate buildings in Korea — S.Y. Kim, Y.C. Kim, et al. (2016)
• Monitoring and Simulating Environmental Asbestos Dispersion from a Textile Factory — D. Kang, Y. Hwang, et al. (2018)

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