Health Effects of Occupational and Environmental Exposures to Nuclear Power Plants: A Meta-Analysis and Meta-Regression

Our plain-English summary of Health Effects of Occupational and Environmental Exposures to Nuclear Power Plants: A Meta-Analysis and Meta-Regression, by R.T. Lin, H. Boonhat, Y.Y. Lin, et al (Current Environmental Health Reports, 2024).

The study

• Authors: R.T. Lin, H. Boonhat, Y.Y. Lin, S. Klebe, K. Takahashi
• Journal: Current Environmental Health Reports
• Published: 2024;11(3):329-339
• Type of article: Meta-analysis, Review
• Cited by: 8 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Purpose Of Review: Numerous epidemiological studies have shown increased health risks among workers and residents living near nuclear power plants exposed to radiation levels meeting regulatory dose limits. This study aimed to evaluate the association between radiation exposure and disease risks among these populations exposed to radiation levels meeting the current regulatory dose limits.

Recent Findings: We searched four databases (Cochrane Library, PubMed, ScienceDirect, and Web of Science) for studies published before August 2023, screened eligible studies (inclusion and exclusion criteria based on population, exposure, comparator, and outcome framework), and collected data on exposure indicators and disease risks. We applied random-effects models of meta-analysis to estimate the pooled effects and meta-regression to assess the dose-response relationship (radiation dose rate for workers and distance for residents). We identified 47 studies, 13 with worker and 34 with resident samples, covering 175 nuclear power plants from 17 countries, encompassing samples of 480,623 workers and 7,530,886 residents. Workers had a significantly lower risk for all-cancer and a significantly higher risk for mesothelioma. Residents had significantly higher risks for all-cancer, thyroid cancer, and leukemia. Notably, children under 5 years old showed the highest risk for all-cancer. Our meta-regression showed a significantly positive dose-response relationship between cumulative dose of radiation exposure and risk for circulatory disease among workers. Our findings demonstrated higher risks for mesothelioma for workers and all-cancer, thyroid cancer, and leukemia for residents exposed to low-dose radiation from nuclear power plants. Some included studies did not adjust for cancer risk confounders, which could overestimate the association between radiation exposure and cancer risk and increase the risk of bias.

© 2024. The Author(s).

In plain English

This meta-analysis pooled studies of nuclear power plant workers and nearby residents. It included 47 studies of 480,623 workers and 7,530,886 residents in 17 countries. Workers' exposure was radiation dose; for residents, lacking exposure data, distance served instead: within 30 km versus farther away. Exposed workers had lower all-cancer risk (RR 0.85, 95% CI 0.75 to 0.97) than comparators, both national populations and unexposed or least-exposed workers. Their mesothelioma death risk was higher (RR 5.53, 95% CI 4.05 to 7.54; two study groups). Higher cumulative dose was linked to more circulatory disease in workers. Residents within 30 km had higher risks of all cancers (RR 1.05, 95% CI 1.00 to 1.09), thyroid cancer (RR 1.17, 95% CI 1.04 to 1.32) and leukemia (RR 1.09, 95% CI 1.03 to 1.16). The authors rated certainty of the all-cancer evidence as very low. They concluded that, although asbestos is the major mesothelioma risk factor, their study pointed to a probable association with low-dose workplace radiation. They noted that 43% of included studies did not adjust for confounders such as smoking and asbestos exposure.

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: Systematic review with random-effects meta-analysis and meta-regression of published epidemiological studies
• Who was studied: Workers in nuclear power plants and residents living near them, drawn from 47 studies. These covered 480,623 workers and 7,530,886 residents, from 175 nuclear power plants in 17 countries: Belgium, Canada, Finland, France, Germany, Hungary, Japan, Korea, Lithuania, the Slovak Republic, Slovenia, Spain, Switzerland, Taiwan, Ukraine, the United Kingdom and the United States.
• Exposure: Low-dose radiation from nuclear power plants in normal operation. For workers, this was occupational radiation dose, covering cumulative doses between 5 and 200 mSv (0.4 to 20 mSv per year). For residents, the authors had no actual exposure data, so they used distance of the home from the plant as an indicator instead, comparing living within 30 km with living farther away. Asbestos exposure was not studied as an exposure.
• Main results:
  • 47 studies were included in the final analysis: 13 of workers and 34 of residents.
  • Workers exposed to radiation from nuclear power plants had a lower pooled all-cancer risk: RR 0.85, 95% CI 0.75 to 0.97, p = 0.013. The pooled comparison groups included the national population as well as workers without or with the lowest occupational exposure.
  • By comparison group, the pooled all-cancer RR for exposed workers was 0.87 against the national population and 0.81 against workers with no or the lowest occupational exposure.
  • Exposed workers had a higher pooled risk of mesothelioma mortality: RR 5.53, 95% CI 4.05 to 7.54, p less than 0.001. This was based on 2 study groups (Table 1).
  • Among workers, meta-regression found a significant dose-response relationship between cumulative radiation dose and circulatory disease risk: coefficient 0.005, 95% CI 0.001 to 0.009, p = 0.029.
  • Residents living within 30 km of the plants had a 5% higher all-cancer risk than those living farther than 30 km: RR 1.05, 95% CI 1.00 to 1.09, p = 0.045.
  • Residents within 30 km had higher risks of thyroid cancer (RR 1.17, 95% CI 1.04 to 1.32, p = 0.011) and leukemia (RR 1.09, 95% CI 1.03 to 1.16, p = 0.004).
  • In subgroup analysis, residents aged under 5 years had a higher all-cancer risk: RR 1.09, 95% CI 1.00 to 1.17, p = 0.050.
  • Among residents, meta-regression showed no significant dose-response relationship between distance from the plant and cancer risk.
  • The authors rated the certainty of evidence for all-cancer as "very low" among both workers and residents.
• The authors' conclusion: The authors concluded that, although asbestos is the major risk factor for mesothelioma, their study underscores a probable association between mesothelioma and occupational low-dose radiation among workers. They also reported higher risks of all-cancer, thyroid cancer and leukemia among residents within 30 km, especially children under 5.
• Limitations the authors state:
  • 43% of the included studies did not adjust for cancer risk confounders such as smoking and asbestos exposure. The authors said this may have caused a serious risk of bias, especially in the resident studies, and may have led to overestimation of the effect.
  • For residents, distance was used instead of actual exposure. Results could therefore over- or underestimate risk, because exposure varies with time spent outdoors, diet and wind direction.
  • Most countries covered were high-income, so the findings may not apply to low-income countries.
  • There was high heterogeneity between studies for some diseases, particularly among residents.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Power plants and utilities.

Medical terms in this study, explained in our Lexicon: Environmental Exposure, Meta-Analysis, Dose-response relationship, Mesothelioma, Cumulative Dose.

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• Mesothelioma mortality within two radiation monitored occupational cohorts — M.T. Mumma, J.L. Sirko, et al. (2022)
• Mortality of older construction and craft workers employed at department of energy (DOE) nuclear sites: follow-up through 2011 — K. Ringen, J. Dement, et al. (2015)
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• Children's health in Latin America: the influence of environmental exposures — A. Laborde, F. Tomasina, et al. (2015)

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