Occupational and environmental asbestos exposure and the risk of lung cancer in Korea: A case-control study in South Chungcheong Province of Korea

Our plain-English summary of Occupational and environmental asbestos exposure and the risk of lung cancer in Korea: A case-control study in South Chungcheong Province of Korea, by D.A. Huh, M.S. Kang, J. Lee, et al (PloS One, 2021).

The study

• Authors: D.A. Huh, M.S. Kang, J. Lee, J.Y. Choi, K.W. Moon, Y.J. Lee
• Journal: PloS One
• Published: 2021;16(4):e0249790
• Cited by: 12 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Despite the use of large amounts of asbestos in the 1990s, few studies have been conducted in Korea on occupational and environmental asbestos exposure and lung cancer risk. The main aim of this study was to estimate the risk of lung cancer development caused by occupational and environmental asbestos exposures in residents of South Chungcheong Province, where about half of the asbestos mines in Korea operated. We conducted a case-control study, for which the information on asbestos exposure history and demographic characteristics was provided by the Environmental Health Center for asbestos of Soonchunhyang University Cheonan Hospital. After adjusting for all covariates, the odds ratios for lung cancer tended to increase with higher exposure probability for both occupational as well as environmental asbestos. The relative risk of occupational asbestos exposure was higher than that of environmental exposure; the interaction of co-exposure was not statistically significant. The estimated means of the latency period were significantly shorter in participants who were engaged in the production of asbestos-containing products and in those who lived near asbestos industries as compared to other groups.

In plain English

This case-control study examined lung cancer and asbestos exposure among residents of South Chungcheong Province, Korea. It compared 179 people newly diagnosed with primary lung cancer between 2009 and 2018 with 895 people without lung cancer, using questionnaires and records from an Environmental Health Center for Asbestos. In the fully adjusted analysis, people with occupational exposure had higher odds of lung cancer than unexposed people (odds ratio 3.08; 95% CI 1.86 to 5.11). The odds were highest among workers producing asbestos-containing products such as cements, slates and fabrics (8.70; 3.13 to 24.18). Environmental exposure overall was not significantly linked to lung cancer (1.03; 0.38 to 2.77). People living not more than 0.5 km from a source had higher odds (6.21; 1.61 to 24.02). The interaction between occupational and environmental exposure was not statistically significant. Workers producing asbestos products and people living near asbestos industries had significantly shorter times from first exposure to diagnosis. The authors concluded that lung cancer risk was positively associated with the probability of exposure. They noted they could assess only exposure probability, not intensity.

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 (cases compared with randomly selected controls, analysed with unconditional logistic regression)
• Who was studied: 179 cases and 895 controls. The cases had newly diagnosed primary lung cancer between 2009 and 2018 (184 were eligible; 5 were excluded because their exposure history was unclear). All participants were residents over 20 years of age who had lived in South Chungcheong Province, Korea, for more than 5 years and had received a chest X-ray or CT scan. Five controls per case were drawn from 21,832 people without lung cancer and were matched by 3-year age group, sex and region. About 84% of participants were male, with a mean age of about 79.
• Exposure: Occupational exposure meant contact with asbestos at work for at least one year. Jobs were grouped as extraction work (extraction, conveyance, grinding), production of asbestos-containing products (cements, slates, fabrics), or maintenance work (demolition and repair). Environmental exposure meant non-occupational contact from asbestos mines, asbestos industries and loading spaces. Exposure probability (possible, probable, likely, definite) was graded by years of work for occupational exposure and by distance of the home from the source for environmental exposure. Fiber types were not measured.
• Main results:
  • Fully adjusted odds ratio for lung cancer in people with occupational asbestos exposure, compared with the unexposed group: 3.08 (95% CI 1.86 to 5.11)
  • Workers who produced asbestos-containing products (cements, slates, fabrics) had the highest odds ratio among job types: 8.70 (95% CI 3.13 to 24.18)
  • Fully adjusted odds ratio for workers in the Definite occupational category (more than 30 years of work): 11.25 (95% CI 2.54 to 49.82). The authors reported that the odds ratio was positively associated with higher exposure probability.
  • Fully adjusted odds ratio for environmental exposure overall: 1.03 (95% CI 0.38 to 2.77). The authors stated this was not a significant increase, but that the odds ratio tended to rise with higher exposure probability.
  • Fully adjusted odds ratio for residents in the Definite environmental category (not more than 0.5 km from the exposure source), compared with unexposed participants: 6.21 (95% CI 1.61 to 24.02)
  • Fully adjusted odds ratio for environmentally exposed participants with experience of soil cultivation: 4.47 (95% CI 1.20 to 16.69)
  • Odds ratio for participants with both high occupational and high environmental exposure probability (Likely or Definite), compared with participants with neither exposure: 20.56 (95% CI 4.44 to 95.21)
  • The interaction between occupational and environmental exposure on the additive scale was not statistically significant (RERI 22.77; p = 0.374)
  • Among the lung cancer cases, workers in production of asbestos-containing products and residents who lived near asbestos industries had significantly shorter latency periods (time from first exposure to diagnosis) than other groups. The fully adjusted mean latency for production work was 33.18 (95% CI 21.32 to 45.04), compared with 45.22 for extraction work and 43.23 for maintenance work (p = 0.035).
  • The latency period for occupational exposure was shorter than for environmental exposure and co-exposure, but the difference was not statistically significant
• The authors' conclusion: The authors concluded that their results were consistent with previous studies showing that occupational and environmental asbestos exposure was related to lung cancer development, and that lung cancer risk was positively associated with the probability of asbestos exposure.
• Limitations the authors state:
  • Exposure was assessed only by probability (work duration or distance from the source), not by intensity
  • There were insufficient data on mean asbestos concentrations at each work site
  • Participants may have exaggerated their exposure because they knew the purpose of the study. The authors argued this would affect cases and controls alike and would bias the estimates toward no effect.

Topics

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

Medical terms in this study, explained in our Lexicon: Asbestos Exposure, Lung Cancer, Case-Control Study, Odds Ratio, Relative Risk, Environmental Exposure, Latency.

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