Wollastonite exposure and lung fibrosis

Our plain-English summary of Wollastonite exposure and lung fibrosis, by M.S. Huuskonen, A. Tossavainen, H. Koskinen, et al (Environmental Research, 1983).

The study

• Authors: M.S. Huuskonen, A. Tossavainen, H. Koskinen, A. Zitting, O. Korhonen, J. Nickels, K. Korhonen, V. Vaaranen
• Journal: Environmental Research
• Published: 1983;30(2):291-304
• Cited by: 17 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. 001715).

Abstract

Wollastonite is a naturally occurring acicular or fibrous metasilicate used in ceramics and as a substitute for asbestos in some applications. Wollastonite fibers are rather similar in form, length, and diameter to amphibole asbestos fibers but mineralogically they are different. Dust measurements in both the Finnish limestone--wollastonite quarry and in the flotation plant yielded high concentrations of both total dust and respirable fibers in some operational stages. The clinical study comprised a total of 46 men who had been exposed to wollastonite at the quarry for at least 10 years. Three of the fifteen nonsmokers showed chronic bronchitis. Radiographs revealed slight lung fibrosis among fourteen men, and slight bilateral pleural thickening among thirteen men. Their sputum specimens were normal. Spirometry and nitrogen single breath tests indicated the possibility of small airways disease.

In plain English

This Finnish study examined workers at a limestone-wollastonite quarry, a site where limestone and the fibrous mineral wollastonite are mined. In February and March 1981 the authors examined 46 men (mean age 48.0) who had worked there for at least 10 years. Dust from drilling, crushing and sorting also contained calcite and quartz. The men's chest X-rays were compared with those of 46 lumberjacks, 46 peat workers and 46 tobacco workers of similar age. Slight lung fibrosis appeared in 14 of the 46 quarry workers, against 1 to 3 of 46 in each comparison group. Bilateral pleural thickening appeared in 13 of the 46, against one, two and four men in the comparison groups. Three of the 15 nonsmokers had chronic bronchitis. Nine of the 46 men showed signs of small airways disease. No sputum sample showed malignant or suspicious cells. The authors concluded that the fibrosis resembled early asbestosis. They noted that the combined effect of wollastonite and silica is unknown, that the group was small, and that further follow-up is 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: Cross-sectional clinical study (symptoms, chest X-rays, lung function tests, sputum cytology) with age-matched referent groups for the X-ray comparison
• Who was studied: 46 men (mean age 48.0, range 32 to 64) who had worked at least 10 years in the limestone-wollastonite quarry at Lappeenranta, Finland, examined in February and March 1981. Nine women were examined but left out of the analysis. The referents were 46 lumberjacks, 46 peat workers and 46 men in tobacco manufacturing, age-matched within 5 years, used for the X-ray comparison.
• Exposure: Dust in a limestone-wollastonite quarry and its wollastonite flotation plant. The respirable fraction of dust samples from drilling, crushing and sorting contained calcite plus 15% wollastonite and 3% quartz. Dust in the flotation plant was mainly wollastonite.
• Main results:
  • Pulmonary fibrosis (at least ILO 1/0) was found in 14 of 46 quarry workers, more often than in the referents (1 to 3 of 46 per referent group, 2 to 7%; P between 0.001 and 0.01)
  • Among the quarry workers the fibrosis was mild in profusion: 1/1 in eight men and 1/0 in six men
  • Fibrosis was found in 9 (38%) of the 24 quarry workers exposed for 20 to 29 years and in 3 (43%) of the 7 exposed for at least 30 years
  • Fibrosis was found in 3 (20%) of the 15 nonsmoking quarry workers and in 11 (35%) of the 31 smokers and exsmokers
  • Bilateral pleural thickening was found in 13 (28%) of the 46 quarry workers, compared with one, two and four men in the referent series (P between 0.01 and 0.05)
  • Chronic bronchitis was found in 8 (26%) of the 31 smoking and exsmoking quarry workers
  • Three of the 15 nonsmoking quarry workers had chronic bronchitis. They had been exposed for 16, 20 and 26 years.
  • Ten of the 46 quarry workers reported breathlessness
  • Among the quarry workers, maximal midexpiratory flow was decreased in four men (9%) and carbon monoxide diffusing capacity was decreased in two men
  • When quarry workers were grouped by pleural thickening and by X-ray opacities, no significant differences in lung function were found
  • 9 (20%) of the 46 quarry workers showed signs indicating small airways disease
  • No malignant or suspicious cells were found in the sputum of any quarry worker examined
  • No ferruginous bodies were found
• The authors' conclusion: The authors concluded that the lung fibrosis in the quarry workers was similar in type, location and profusion to the fibrosis seen in patients with early asbestosis
• Limitations the authors state:
  • The combined effects of wollastonite and silica in causing fibrosis are not known
  • For chronic bronchitis, any effect of wollastonite could not be separated from the total dust exposure in the quarry
  • The group was too small for definite conclusions about the lung function findings
  • Conventional lung function tests are not sensitive enough to detect mild lung fibrosis
  • The group was small, and amphibole asbestos fibers may remain uncoated, so the absence of ferruginous bodies is of limited meaning
  • Further follow-up is required before the health hazards of wollastonite can be fully evaluated. Because so few people are exposed, no answer on carcinogenicity is expected.

Topics

Medical terms in this study, explained in our Lexicon: Wollastonite, Fibrosis, Acicular, Amphibole Asbestos, Respirable Fiber, Bilateral, Pleural Thickening, Sputum.

Related studies

• Relative effects of asbestos and wollastonite on alveolar macrophages — W.H. Pailes, D.J. Judy, et al. (1984)
• The biological reactivity of calcium silicate composites: in vivo studies — R.J. Richards, T.D. Tetley, et al. (1981)
• Fibrogenic effect of wollastonite compared with asbestos dust and dusts containing quartz — E.E. McConnell (1995)
• Biological reactivity of calcium silicate composites--in vitro studies — J. Hunt, F.D. Pooley, et al. (1981)
• Mortality among a cohort of US man-made mineral fiber workers: 1985 follow-up — G.M. Marsh, P.E. Enterline, et al. (1990)
• Genotoxicity of dimethylnitrosamine in the presence of chrysotile asbestos UICC B and xonotlite — F. Denizeau, M. Marion, et al. (1985)

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