Amphibole fibers in a taconite mine and in the lungs of the miners

Our plain-English summary of Amphibole fibers in a taconite mine and in the lungs of the miners, by B. Gylseth, T. Norseth, V. Skaug (American Journal of Industrial Medicine, 1981).

The study

• Authors: B. Gylseth, T. Norseth, V. Skaug
• Journal: American Journal of Industrial Medicine
• Published: 1981;2(2):175-84
• Type of article: Case report
• Cited by: 2 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Fibers of the amphibole mineral series have been demonstrated in the dust from an open taconite ore mine. Though the total dust levels in some places are high, exposures to fibers are below one fiber/cc. The energy dispersive X-ray spectra of the amphibole fibers correspond to those of cummingtonite-grunerite, hornblende, or actinolite. The same type and size distribution of fibers were found during post mortem analyses of lung tissue from two previously exposed miners. The pathological examination revealed an undifferentiated small cell carcinoma of left lung as well as pulmonary fibrosis in one of the cases. In the second case a poorly differentiated squamous cell carcinoma of left lung was found along with silicosis.

In plain English

This study was part of a combined epidemiological and hygienic survey of an open-pit taconite (iron ore) mine in Northern Norway. The authors measured dust and fibers in the mine and analyzed lung tissue from two former miners with lung cancer. Total dust ranged from less than 0.5 mg/m3 in control rooms to 36 mg/m3 in the crushing plant. Fiber levels ranged from the detection limit (0.01 fibers/cc) to 0.9 fibers/cc, and all other readings were below 0.3 fibers/cc. The fibers were amphiboles whose spectra matched hornblende or actinolite and cummingtonite-grunerite. The first miner, aged 55 with 27 years in the mine, had small cell carcinoma of the left lung and lung fibrosis. The second, aged 61 with 36 years in the mine and a heavy smoker, had squamous cell carcinoma of the left lung and silicosis. Their lungs held 14.0 million and 4.4 million fibers per gram of dried tissue, similar in size and composition to the mine fibers. Of 100 lung fibers analyzed, 3 had spectra corresponding to anthophyllite asbestos. The authors concluded that present exposure probably constitutes a minor carcinogenic risk. Exposure levels for these two workers were not known.

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: Industrial hygiene survey of mine dust (air and settled dust samples) combined with mineral analysis of autopsy lung tissue from two miners (case reports); part of a combined epidemiological and hygienic survey
• Who was studied: An open-pit taconite mine in Northern Norway, in operation since 1907, and paraffin-embedded lung tissue from two previously exposed miners
• Exposure: Taconite mine dust containing amphibole fibers with spectra matching hornblende or actinolite and cummingtonite-grunerite; dust before final magnetic separation also contained 23 to 32 percent quartz
• Main results:
  • Total dust concentrations in the mine ranged from less than 0.5 mg/m3 in the control rooms to 36 mg/m3 in the crushing plant
  • Airborne fiber concentrations ranged from the detection limit (0.01 fibers/cc) to 0.9 fibers/cc; the 0.9 value was in the pre-separation area, and all other measurements were less than 0.3 fibers/cc
  • Case 1: a 55-year-old man employed in the mine for 27 years had an undifferentiated small cell carcinoma of the left lung, with fibrosis in the distal peribronchial areas; there was no evidence of silicosis and his smoking history was not obtained
  • Case 2: a 61-year-old man employed in the mine for 36 years, a heavy smoker with radiological signs of silicosis, had a poorly differentiated squamous cell carcinoma of the left lung; silicotic nodules were found at autopsy
  • Lung fiber concentrations were 14.0 x 10^6 (case 1) and 4.4 x 10^6 (case 2) fibers per gram of dried lung tissue
  • Of 100 fibers analyzed by EDS in the two lung samples, 75 gave spectra corresponding to hornblende or actinolite, 10 to cummingtonite-grunerite and 3 to anthophyllite asbestos; 7 gave a pure Si, Fe or Ti peak and 5 were unidentified
  • Fibers in the miners' lungs were similar in size and composition to those in the mine today; only a few percent of fibers were longer than 8 micrometers
  • Iron-protein coated fibers (amphibole bodies) were found in the lung tissue
• The authors' conclusion: The authors concluded that, considering exposure level and fiber dimensions, the present exposure in the mine probably constitutes a minor carcinogenic risk. They added that it cannot be excluded that the fibers contributed to the cancer in the two miners.
• Limitations the authors state:
  • Dust exposures before 1970 were considerably higher, but the exposure levels for the two workers could not be given
  • Only two autopsy lung samples were available because the mine is in a remote area with no local pathology service
  • The smoking history of the first case was not obtained
  • The authors could not differentiate between hornblende and actinolite by selected area electron diffraction

Topics

Medical terms in this study, explained in our Lexicon: Amphibole Group, Taconite, Cummingtonite-Grunerite, Hornblende, Actinolite, Carcinoma, Pulmonary Fibrosis, Squamous Cell Carcinoma.

Related studies

• Respiratory effects of exposure to dust in taconite mining and processing — T.C. Clark, V.A. Harrington, et al. (1980)
• Mineralogical and microscopic evaluation of coarse taconite tailings from Minnesota taconite operations — L.M. Zanko, H.B. Niles, et al. (2008)
• The search for asbestos within the Peter Mitchell Taconite iron ore mine, near Babbitt, Minnesota — M. Ross, R.P. Nolan, et al. (2008)
• A case-control study of mesothelioma in Minnesota iron ore (taconite) miners — C.S. Lambert, B.H. Alexander, et al. (2016)
• Occupational exposures and lung cancer risk among Minnesota taconite mining workers — E.M. Allen, B.H. Alexander, et al. (2015)
• An overview of the risk of lung cancer in relation to exposure to asbestos and of taconite miners — G. Berry, G.W. Gibbs (2008)

Browse more research in American Journal of Industrial Medicine, or return to medical research.