Asbestos as a cofactor in carcinogenesis among nickel-processing workers

Our plain-English summary of Asbestos as a cofactor in carcinogenesis among nickel-processing workers, by A.M. Langer, A.N. Rohl, I.J. Selikoff, et al (Science, 1980).

The study

• Authors: A.M. Langer, A.N. Rohl, I.J. Selikoff, G.E. Harlow, M. Prinz
• Journal: Science
• Published: 1980;209(4454):420-2
• Cited by: 18 articles, as counted by NIH iCite
• Read it: PubMed · Publisher
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 000826).

Abstract

It has been widely assumed, especially in the absence of other explanations, that lung cancer and nasal sinus cancers observed among nickel smelter workers are the result of the carcinogenicity of nickel. Although there may be such influence, supplementary hypotheses are also possible. The nickeliferous ores from at least one major smelter in New Caledonia (excess numbers of cancers have been found in these smelter workers) are derived from serpentinized host rocks which contain large amounts of chrysotile asbestos. Analysis indicates that nickel ores from this area are heavily contaminated by these fibers. The deposits are mined for their nickel content, but workers may be exposed to the asbestos fibers contained in the deposits. Hygiene measures limited to the avoidance of nickel may be inadequate under such circumstances and should be reevaluated so as to prevent the inhalation of asbestos-containing dusts.

In plain English

This short report was a mineral analysis of nickel ore, not a study of workers. The authors examined one museum specimen of "garnierite" (a nickel ore) from Noumea, New Caledonia, held by the American Museum of Natural History, and three ore samples from pits being worked at Noumea. They used light microscopy, x-ray diffraction, transmission electron microscopy and an electron microprobe. No free fibers were seen under the light microscope, but the electron microscope showed chrysotile asbestos fibers in every specimen. The museum specimen was mostly chrysotile and sheet minerals. The ores were mixtures of clay, other sheet minerals and large amounts of chrysotile, though with less fiber than the museum specimen. The fibrils were so fine that only the electron microscope revealed them. The authors concluded that lung cancer, and possibly other tumors, among workers at this smelter might be due to this chrysotile. They noted that x-ray diffraction alone could not tell the different serpentine minerals apart, and that analysis of miners' lung tissue was still needed.

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: Laboratory mineralogical analysis of ore specimens using polarized light microscopy, continuous scan x-ray diffraction, transmission electron microscopy with selected area electron diffraction, and an electron microprobe technique; no workers were studied
• Who was studied: Ore specimens, not people: one New Caledonian "garnierite" specimen from Noumea in the American Museum of Natural History collection, and three specimens of ore being processed from worked pits on Noumea, New Caledonia (site of a large nickel-mining and smelting operation)
• Exposure: Chrysotile asbestos found within nickel ores ("garnierite") derived from serpentinized host rock in New Caledonia
• Main results:
  • Under polarized light microscopy, no free fibers were observed in any of the specimens
  • Transmission electron microscopy showed chrysotile fiber in all specimens examined (the museum "garnierite" and the three Noumea ores)
  • The Noumea "garnierite" was predominantly chrysotile fiber and sheet silicates. The Noumea ores were mixtures of clay (montmorillonite), other sheet silicates including serpentine phases, and especially large amounts of chrysotile fiber
  • The fiber content of the ore was less than in the "garnierite" standard. The fine chrysotile fibrils (about 350 angstroms in diameter) would not be seen without transmission electron microscope magnification
  • X-ray diffraction of the ores also suggested the presence of a talc-like mineral
  • The integrated peak count ratio of silicon to magnesium was 1.73 plus or minus 0.05 in non-nickeliferous chrysotile from Globe, Arizona, 5.41 plus or minus 0.05 in most Noumea chrysotile fibers, and 7.84 plus or minus 0.05 in some low-magnesium chrysotile fibers. The authors attributed the rise to magnesium depletion, accompanied by increased nickel x-ray emission
  • Geological data from several "garnierite"-bearing nickel deposits, including one in Riddle, Oregon, and preliminary analyses of other "garnierite" specimens suggested that contamination by chrysotile or amphibole asbestos may be common
• The authors' conclusion: The authors concluded that the specimens were heavily contaminated with chrysotile asbestos and that lung cancer, and possibly other tumors, among workers at this smelter might be due to exposure to it. They proposed three hypotheses: nickel as the essential factor with fibers as a vehicle, asbestos as primary, or nickel and fiber interacting. They stated that these should be tested in animal models and in re-evaluated epidemiological data
• Limitations the authors state:
  • Because of marked line-broadening in x-ray diffraction, the different serpentine minerals could not be distinguished by that method
  • The serpentine in the New Caledonian deposit had not been studied in detail
  • The authors noted that mineralogical analysis of lung tissue from miners was still needed; no worker tissue or health data were analyzed in this report

Topics

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

Medical terms in this study, explained in our Lexicon: Carcinogenesis, Lung Cancer, New Caledonia, Chrysotile.

Related studies

• Can lung cancer risk among nickel refinery workers be explained by occupational exposures other than nickel? — T.K. Grimsrud, S.R. Berge, et al. (2005)
• Length-dependent pathogenic effects of nickel nanowires in the lungs and the peritoneal cavity — C.A. Poland, F. Byrne, et al. (2012)
• Nickel-related cancer in welders — S. Langård (1994)
• Radiographic evidence of pulmonary fibrosis and possible etiologic factors at a nickel refinery in Norway — S.R. Berge, K. Skyberg (2003)
• A role for nickel in osmotic adjustment in drought-stressed plants of the nickel hyperaccumulator Stackhousia tryonii Bailey — N.P. Bhatia, A.J. Baker, et al. (2005)
• Determination of iron, chromium, cobalt, nickel, and scandium in asbestos by neutron activation analysis — A. Holmes, A. Morgan, et al. (1971)

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