Incidence of Cancer and Asbestos-Related Diseases among Residents Living near Abandoned Asbestos Mines in South Korea: A Retrospective Cohort Study Using National Health Insurance Database

Our plain-English summary of Incidence of Cancer and Asbestos-Related Diseases among Residents Living near Abandoned Asbestos Mines in South Korea: A Retrospective Cohort Study Using National Health Insurance Database, by K. Kwak, K.E. Zoh, D. Paek (International Journal of Environmental Research and Public Health, 2021).

The study

• Authors: K. Kwak, K.E. Zoh, D. Paek
• Journal: International Journal of Environmental Research and Public Health
• Published: 2021;18(3)
• Cited by: 5 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

The use of asbestos has been banned since 2009 in South Korea. However, there is still a risk of exposure to environmental asbestos originating from abandoned asbestos mines. We constructed a retrospective dynamic cohort using the National Health Insurance Database of South Korea. We determined the risk of developing asbestos-related diseases (ARDs) among residents living near asbestos mines compared with those living in the control area and the general population. The risks of asbestosis (adjusted hazards ratio [HR] 65.40, 95% CI = 35.02-122.12) and pleural plaques (adjusted HR 3.55, 95% CI = 1.96-6.41) were significantly increased among residents living near the asbestos mines compared with the control area. The risk of malignant mesothelioma was increased near asbestos mines compared with the control area; however, it was not significant (adjusted HR 1.83, 95% CI = 0.61-5.47). When a separate analysis according to sex was conducted, the risk of mesothelioma among male residents was statistically significant (adjusted HR 8.30, 95% CI = 1.04-66.63), and the standardized incidence ratio (SIR) was significantly increased (SIR 3.48, 95% CI = 1.50-6.85). The risk of ARDs was increased due to environmental asbestos exposure near abandoned asbestos mines in South Korea.

In plain English

This retrospective cohort study used South Korean health insurance records from 2007 to 2018. It compared 104,198 residents of Hongseong, which has nine abandoned asbestos mines, with 90,640 residents of Buyeo, a same-province control area without asbestos mines. Everyone included had lived there at least five years. Exposure was defined by residence, and job histories were unavailable. Asbestosis was recorded in 668 exposed-area residents versus 10 control-area residents (adjusted hazard ratio 65.40, 95% CI 35.02 to 122.12). Pleural plaques were recorded in 54 versus 14 (adjusted HR 3.55, 1.96 to 6.41). Mesothelioma (9 versus 5 cases) was higher but not statistically significant (adjusted HR 1.83, 0.61 to 5.47). Among men alone (8 versus 1 cases) it was significant (adjusted HR 8.30, 1.04 to 66.63). Lung cancer did not differ significantly after adjustment (adjusted HR 1.02, 0.93 to 1.12); unadjusted, it was significantly lower in the exposed area. The authors cautioned that the men's mesothelioma may reflect past occupational exposure and that asbestosis may have been overdiagnosed in the exposed area. They concluded that environmental asbestos exposure could cause asbestos-related diseases, while noting occupational exposure could not be excluded.

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: Retrospective dynamic cohort study using South Korea's National Health Insurance Database (claims and diagnosis codes), with standardized incidence ratios calculated against national cancer registry rates
• Who was studied: 104,198 residents of Hongseong (exposed area) and 90,640 residents of Buyeo (control area, which has no asbestos mine), both in South Chungcheong Province, South Korea. All had at least five years of residence there. Follow-up ran from 2007 to 2018 (cancer comparisons with the national population ran 2007 to 2017). Person-years were 1,011,874.6 in the exposed area and 909,433.5 in the control area.
• Exposure: Living in Hongseong, an area with nine abandoned asbestos mines, where about 70% of the population lives within 5 km of a mine. The control area, Buyeo, has no asbestos mine; one asbestos mine lies within 10 km, outside its boundaries. Exposure was defined by area of residence only. Fibers were not measured in this study, and individual distance from the mines could not be analyzed.
• Main results:
  • Asbestosis: 668 cases in the exposed area versus 10 in the control area. The incidence was 66.02 versus 1.10 per 100,000 person-years. Adjusted HR 65.40 (95% CI 35.02 to 122.12).
  • Pleural plaques: 54 cases in the exposed area versus 14 in the control area. The incidence was 5.32 versus 1.54 per 100,000 person-years. Adjusted HR 3.55 (95% CI 1.96 to 6.41).
  • Mesothelioma, all residents: 9 cases in the exposed area versus 5 in the control area. The increase was not statistically significant (crude HR 1.62, 95% CI 0.54 to 4.83; adjusted HR 1.83, 95% CI 0.61 to 5.47).
  • Mesothelioma, men only: 8 cases in the exposed area versus 1 in the control area. Adjusted HR 8.30 (95% CI 1.04 to 66.63).
  • Compared with the national population, men in the exposed area had a mesothelioma SIR of 3.48 (95% CI 1.50 to 6.85), based on 8 observed versus 2.3 expected cases. Men in the exposed area also had significantly raised SIRs for stomach and lung cancer.
  • Mesothelioma, women: 1 case in the exposed area versus 4 in the control area (adjusted HR 0.25, 95% CI 0.03 to 2.23). Risk in the exposed area was lower than in both the control area and the general population.
  • Asbestosis among women, exposed versus control area: adjusted HR 89.75 (95% CI 28.77 to 280.04). For men the adjusted HR was 53.30 (95% CI 25.24 to 112.55).
  • Lung cancer did not differ significantly between the areas after adjustment (adjusted HR 1.02, 95% CI 0.93 to 1.12). Without adjustment, it was significantly lower in the exposed area than in the control area (crude HR 0.90, 95% CI 0.82 to 0.99).
  • Colon cancer was significantly higher in the exposed area after adjustment (adjusted HR 1.13, 95% CI 1.01 to 1.26). The authors noted the effect size was small.
  • Pneumoconiosis other than asbestosis, COPD and benign lung masses were significantly lower in the exposed area. The authors suggested that the larger number of past coal mines in the control area (11 in Buyeo versus 2 in Hongseong) may have affected these results.
• The authors' conclusion: The authors concluded that their study demonstrated that environmental asbestos exposure could cause asbestos-related diseases. They added that occupational exposure could not be excluded and that the results should be interpreted cautiously.
• Limitations the authors state:
  • Diagnoses came from insurance claims data and could not be validated, especially for non-cancer respiratory diseases.
  • Asbestosis in the exposed area may have been overdiagnosed, because doctors may have been more inclined to diagnose asbestosis in people living near the mines.
  • Smoking and drinking information was incomplete for about 30% of subjects.
  • Residence history before 2002 was not available, which could misclassify exposure given the long latency of these diseases.
  • Occupational histories were unknown, so occupational asbestos exposure could not be separated from environmental exposure.
  • The raised mesothelioma risk seen only in men may be due to past occupational exposure.
  • Residence within Hongseong could not be located more precisely. Some people in the exposed group may have lived more than 5 km from the mines, and the effect of distance from the mines could not be analyzed.

Topics

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

Medical terms in this study, explained in our Lexicon: Cohort Study, Pleural Plaques, Mesothelioma, Standardized Incidence Ratio (SIR), Asbestos Exposure.

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• Standardized Incidence Ratio and Standardized Mortality Ratio of Malignant Mesothelioma in a Worker Cohort Using Employment Insurance Database in Korea — E.A. Kim (2021)
• Future Incidence of Malignant Mesothelioma in South Korea: Updated Projection to 2038 — K. Kwak, S.I. Cho, et al. (2021)
• Estimated future incidence of malignant mesothelioma in South Korea: Projection from 2014 to 2033 — K.M. Kwak, D. Paek, et al. (2017)
• Cancer morbidity of residents living near an oil refinery plant in North-West Italy — C. Salerno, P. Berchialla, et al. (2013)
• Disease Latency according to Asbestos Exposure Characteristics among Malignant Mesothelioma and Asbestos-Related Lung Cancer Cases in South Korea — D.A. Huh, W.R. Chae, et al. (2022)

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