Radiation-related occupational cancer and its recognition criteria in South Korea

Our plain-English summary of Radiation-related occupational cancer and its recognition criteria in South Korea, by S. Seo, D. Lee, K.M. Seong, et al (Annals of Occupational and Environmental Medicine, 2018).

The study

• Authors: S. Seo, D. Lee, K.M. Seong, S. Park, S.G. Kim, J.U. Won, Y.W. Jin
• Journal: Annals of Occupational and Environmental Medicine
• Published: 2018;30:9
• Type of article: Review
• Cited by: 10 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Ionizing radiation is a well-known carcinogen, and is listed as one carcinogenic agent of occupational cancer. Given the increase in the number of workers exposed to radiation, as well as the increase in concern regarding occupational cancer, the number of radiation-related occupational cancer claims is expected to increase. Unlike exposure assessment of other carcinogenic agents in the workplace, such as asbestos and benzene, radiation exposure is usually assessed on an individual basis with personal dosimeters, which makes it feasible to assess whether a worker's cancer occurrence is associated with their individual exposure. However, given the absence of a threshold dose for cancer initiation, it remains difficult to identify radiation exposure as the root cause of occupational cancer. Moreover, the association between cancer and radiation exposure in the workplace has not been clearly established due to a lack of scientific evidence. Therefore, criteria for the recognition of radiation-related occupational cancer should be carefully reviewed and updated with new scientific evidence and social consensus. The current criteria in Korea are valid in terms of eligible radiogenic cancer sites, adequate latent period, assessment of radiation exposure, and probability of causation. However, reducing uncertainty with respect to the determination of causation between exposure and cancer and developing more specific criteria that considers mixed exposure to radiation and other carcinogenic agents remains an important open question.

In plain English

This was a review of how South Korea decides whether a worker's cancer was caused by ionizing radiation at work. It is not a study of asbestos, which appears only in passing. The authors contrast asbestos exposure assessment with individual radiation dosimeters. Citing another publication, they also call mesothelioma, which Korea's criteria exclude, a well-known asbestos-related cancer. National dose records showed that non-destructive testing (NDT) workers had the highest average doses of registered radiation workers, 2.37 to 3.87 mSv per year in the recent five years. The authors described 43 deliberated cases from occupational disease reports for 2000 to 2015, and about 70% involved men. Six were classified as having a strong relationship with work exposure and two as 'issues'. All eight were men, and most had leukemia. The authors concluded that Korea's criteria are valid in terms of eligible cancer sites, latent period, exposure assessment and probability of causation. Noting that doses often cannot be measured exactly, they proposed considering the upper 95% or 99% credibility limit of the probability of causation, and criteria for combined exposures.

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: Review of recognition criteria for radiation-related occupational cancer, with a description of Korean worker dose data and diagnosed cases
• Who was studied: Radiation workers in Korea's national dose registries, and cases of possibly radiation-related occupational cancer deliberated in Korea from 2000 to 2015, taken from the occupational disease annual reports of the Korea Occupational Safety and Health Agency (KOSHA)
• Exposure: Occupational ionizing radiation (x-rays and gamma rays), measured as doses in mSv. Groups included NDT workers, nuclear power plant workers, medical and diagnostic radiation workers, and semiconductor workers.
• Main results:
  • The authors contrasted workplace exposure assessment for asbestos and benzene with radiation exposure, which is usually assessed individually with personal dosimeters.
  • Among radiation workers in the registry run by the Nuclear Safety and Security Commission, NDT workers had the highest average doses, 2.37 to 3.87 mSv per year in the recent five years.
  • Among diagnostic radiation workers, radiologic technologists had the highest average doses, 0.85 to 1.21 mSv per year in the recent 5 years.
  • Of 43 deliberated cases in Korea (2000 to 2015), about 70% involved male workers. Six were classified as having a 'strong relationship' with occupational exposure.
  • Two further cases remained classified as 'issues'. All eight of these cases (six strong, two issues) were men, the youngest aged 37.
  • Most of these eight cases had leukemia.
  • Under Korea's criteria, malignant mesothelioma is not recognized as a radiation-related occupational cancer. Neither are Hodgkin's lymphoma, melanoma, or chronic lymphocytic leukemia (CLL). The authors described mesothelioma as a well-known asbestos-related cancer, citing another publication.
  • Korea's latency rules: a solid cancer must occur at least 5 years after first exposure. Leukemia other than CLL must occur at least 2 years after first exposure and within 20 years after last exposure.
  • Under current guidelines, the probability of causation must exceed 50% for solid cancer and 33% for leukemia.
• The authors' conclusion: The authors concluded that, compared with scientific evidence and other countries' guidelines, Korea's criteria are valid in terms of eligible cancer sites, latent period, exposure assessment and probability of causation. They proposed monitoring all radiation-related workers and considering more relaxed criteria that use the upper 95% or 99% credibility limit of the probability of causation. They also called for criteria covering exposure to two or more carcinogens.
• Limitations the authors state:
  • The authors stated that exposure dose often cannot be quantified exactly, so the recognition criteria involve some uncertainty. This is a limitation of the criteria they reviewed.

Topics

Medical terms in this study, explained in our Lexicon: Carcinogenic, Causation.

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