Cancer Mortality Patterns Among US Uranium Miners and Millers 1950 through 1962

Our plain-English summary of Cancer Mortality Patterns Among US Uranium Miners and Millers 1950 through 1962, by J.K. Wagoner, V.E. Archer, B.E. Carroll, et al (1964).

The study

• Authors: J.K. Wagoner, V.E. Archer, B.E. Carroll, D.A. Holaday, P.A. Lawrence
• Published: Journal of the National Cancer Institute, Volume 32 No. 4. April 1964
• Type of article: Journal article
• Our copy: from Johns-Manville's own medical library. The article is still under copyright, so we describe it here rather than post it.

In plain English

This article is about uranium miners and millers, not asbestos. Asbestos is not mentioned in it. The authors followed 5,370 uranium miners and millers in the Colorado Plateau area who had volunteered for at least one physical examination between 1950 and 1960. They tracked deaths through December 31, 1962, and compared them with the deaths expected from the general male population of the same states. By that date, 317 men were known to have died. Among white uranium millers, mortality did not differ significantly from expected. Among white uranium miners, deaths were significantly higher than expected, mainly from accidents (SMR 297) and cancer (SMR 160). For respiratory cancer the SMR was 357. Among white miners with 5 or more years underground, 11 respiratory cancer deaths were observed against 1.1 expected. Nonwhite (mainly Indian) workers had fewer deaths than expected, 43 against 61.3. The authors concluded that the cumulative dose of airborne radiation in the mines was likely responsible for the excess respiratory cancer. They noted that some deaths may have been missed and that their radiation exposure figures were only approximations.

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: Cohort mortality study (modified life-table method) of examined uranium workers, compared with the general male population of the same states
• Who was studied: 5,370 uranium miners and millers in the Colorado Plateau area who volunteered for at least one physical examination between 1950 and 1960. They were followed to December 31, 1962, by which time 317 were known to have died. The cohorts were nonwhite (mainly Indian) miners and millers, white millers (611), and white miners (3,656), including 2,500 with underground uranium mining experience.
• Exposure: Uranium mining (underground, open-pit or surface) and uranium milling. The study looked at years of underground uranium mining and at airborne radiation from radon daughters, measured in working levels. Ore constituents included free silica.
• Main results:
  • Nonwhite (mainly Indian) uranium miners and millers: 43 deaths compared with 61.3 expected, a statistically significant deficit.
  • White uranium millers: mortality showed no significant deviation from expected.
  • White uranium miners: mortality significantly greater than expected (P less than 0.01), attributable to accidents (SMR 297) and malignant neoplasms (SMR 160).
  • White uranium miners: among cancers, the respiratory system excess had an SMR of 357.
  • White miners with open-pit, surface or occasional underground experience: only accidents deviated significantly from expected (SMR 361).
  • White underground uranium miners: 12 respiratory cancer deaths observed (P less than 0.01). The expected figure is unreadable in the scanned text.
  • White miners with 5 or more years of underground experience: 11 respiratory cancer deaths compared with 1.1 expected (P less than 0.01). Of the 15 deaths in the 'all other causes' category, 9 reflected silicosis and its complications.
  • White miners with less than 5 years underground: only accidents were significantly in excess of expected.
  • There was a significant excess of respiratory cancer even among uranium miners with no prior hard-rock mining experience. In Table 7, those with 5 or more years of underground uranium mining and no other underground mining had 5 deaths observed against 0.6 expected.
  • The mean cumulative radon-daughter dose of miners with respiratory cancer was significantly greater than that of miners with nonrespiratory diseases and of matched living miners.
  • Cigarette consumption did not differ among the cohorts, so the authors judged it unlikely that smoking alone accounted for the respiratory cancer excess.
• The authors' conclusion: The authors concluded that the cumulative dose of airborne radiation in these mines likely was responsible for the excess of respiratory cancer. They also concluded that it possibly contributed to the excess of nonmalignant respiratory diseases.
• Limitations the authors state:
  • Some deaths may have escaped detection. Men of unknown status were assumed to be living, which the authors said would make findings of excess mortality conservative.
  • Years of underground employment was a poor estimate of radiation exposure.
  • Radiation exposure values were only approximations, because measurements were sparse and many were estimates.
  • Because of multiple comparisons in the dose analysis, the true level of statistical significance is unknown.

Topics

Medical terms in this study, explained in our Lexicon: Cumulative Exposure.

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