Radionuclide injury to the lung

Our plain-English summary of Radionuclide injury to the lung, by G.E. Dagle, C.L. Sanders (Environmental Health Perspectives, 1984).

The study

• Authors: G.E. Dagle, C.L. Sanders
• Journal: Environmental Health Perspectives
• Published: 1984;55:129-37
• Type of article: Review
• Cited by: 34 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Radionuclide injury to the lung has been studied in rats, hamsters, dogs, mice and baboons. Exposure of the lung to high dose levels of radionuclides produces a spectrum of progressively more severe functional and morphological changes, ranging from radiation pneumonitis and fibrosis to lung tumors. These changes are somewhat similar for different species. Their severity can be related to the absorbed radiation dose (measured in rads) produced by alpha, beta or gamma radiation emanating from various deposited radionuclides. The chemicophysical forms of radionuclides and spatial-temporal factors are also important variables. As with other forms of injury to the lung, repair attempts are highlighted by fibrosis and proliferation of pulmonary epithelium. Lung tumors are the principal late effect observed in experimental animals following pulmonary deposition of radionuclides at dose levels that do not result in early deaths from radiation pneumonitis or fibrosis. The predominant lung tumors described have been of epithelial origin and have been classified, in decreasing frequency of occurrence, as adenocarcinoma, bronchioloalveolar carcinoma, epidermoid carcinomas and combined epidermoid and adenocarcinoma. Mesothelioma and fibrosarcoma have been observed in rats, but less commonly in other species. Hemangiosarcomas were frequency observed in dogs exposed to beta-gamma emitters, and occasionally in rats exposed to alpha emitters. These morphologic changes in the lungs of experimental animals were reviewed and issues relevant to the prediction of human hazards discussed.

In plain English

This article was a review, not a new study. The authors reviewed published animal experiments on lung damage from inhaled radioactive materials (radionuclides) such as plutonium, in rats, hamsters, dogs, mice and baboons. The reviewed studies described a range of effects. High doses caused radiation pneumonitis and fibrosis. Lung tumors were the main late effect at doses that did not cause early death. Most of these tumors were of epithelial origin, such as adenocarcinoma. Mesotheliomas were seen in rats but less commonly in other species. Asbestos appeared only in a comparison: mesotheliomas produced in rats by injecting plutonium dioxide into the abdominal cavity were described as similar to those produced by injecting chrysotile asbestos into the abdominal cavity. One cited dog study reported that 20 of 21 dogs developed lung tumors after a single inhalation of plutonium dioxide, at estimated average cumulative lung doses of 2,000 to 12,000 rad. A separate cited study reported lung tumors in 3 of 292 hamsters that inhaled plutonium-238 or -239 dioxide. The authors concluded that animal findings must be applied to people with caution.

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 published animal experiments (not a new study)
• Who was studied: Experimental animals in previously published studies: rats, hamsters, dogs, mice and baboons
• Exposure: Radionuclides deposited in the lung, mainly by inhalation. These included alpha emitters (plutonium dioxides and nitrates, americium, curium, einsteinium, polonium-210, radon and its daughters) and beta-gamma emitters (yttrium-90, yttrium-91, cerium-144, strontium-90, promethium-147). Asbestos was not an exposure in this review; chrysotile asbestos appears only in a comparison of rat mesotheliomas.
• Main results:
  • In the experimental animals reviewed, lung tumors were the principal late effect at dose levels that did not cause early deaths from radiation pneumonitis or fibrosis.
  • Across species, the predominant lung tumors were of epithelial origin. In decreasing frequency they were adenocarcinoma, bronchioloalveolar carcinoma, epidermoid carcinoma, and combined epidermoid and adenocarcinoma.
  • Mesotheliomas and fibrosarcomas were observed in rats but less commonly in other species. In rats, malignant mesotheliomas grew from the pleural surface.
  • Mesotheliomas induced in rats by plutonium dioxide given into the abdominal cavity (intraperitoneally) were described as similar in morphogenesis and origin to mesotheliomas induced by intraperitoneal injections of chrysotile asbestos. This comes from a cited earlier study (reference 36).
  • In a series of Wistar rat studies, no lung tumors were found in 230 unexposed rats. Individual exposed rats developed lung tumors at lung doses of less than 10 rad. The incidence at these low doses was not significantly different from controls, but tumors were consistently found.
  • A cited dog study reported that 20 of 21 dogs developed lung tumors after a single inhalation exposure to plutonium dioxide, with estimated average cumulative radiation doses to the lungs of 2,000 to 12,000 rad. A scanning-damaged symbol before '4.5 years' makes the exact timing unclear.
  • In hamsters, a separate cited study reported lung tumors in 3 of 292 Syrian golden hamsters that inhaled plutonium-238 or plutonium-239 dioxide.
  • Neither oat cell tumors nor any other neurosecretory cell tumor had been induced in laboratory animals by radionuclides, although small-cell carcinomas occur in uranium miners.
• The authors' conclusion: The authors concluded that, in animals, high radionuclide exposure leads to death from lesions characterized as radiation fibrosis, while lower exposures allow longer survival and the appearance of lung tumors. They stated that extrapolating animal findings to people must be done with caution.
• Limitations the authors state:
  • The authors noted that the baboon studies had not run long enough to evaluate long-term effects such as lung tumors.
  • The authors stated that the level of risk at very low exposure levels still needed better documentation from ongoing lifespan studies.

Topics

Medical terms in this study, explained in our Lexicon: Pneumonitis, Fibrosis, Epithelium, Deposition, Adenocarcinoma, Carcinoma, Mesothelioma.

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• Different imaging methods in the assessment of radiation-induced lung injury following hemithorax irradiation for pleural mesothelioma — P. Maasilta, L. Kivisaari, et al. (1990)
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