Silicosis among gemstone workers in South Africa: tiger's-eye pneumoconiosis

Our plain-English summary of Silicosis among gemstone workers in South Africa: tiger's-eye pneumoconiosis, by N.W. White, R. Chetty, E.D. Bateman (American Journal of Industrial Medicine, 1991).

The study

• Authors: N.W. White, R. Chetty, E.D. Bateman
• Journal: American Journal of Industrial Medicine
• Published: 1991;19(2):205-13
• Type of article: Case report
• Cited by: 12 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Six cases of silicosis in workers involved in the processing of semiprecious gem stones have been seen in our clinic since 1976. They had been employed as stone sculptors in lapidaries where they processed tiger's-eye, rose quartz, amethyst, quartz crystal, and a variety of other locally occurring semiprecious stones. In five of the cases, exposure was in small and poorly regulated lapidaries without specific dust control measures. The sixth was detected during the course of a health and hygiene survey (including dust sampling) that was conducted in one of two lapidaries still operating in our area. Progressive massive fibrosis (PMF) or accelerated silicosis was noted in four of the six cases, three of whom had progression of their disease after cessation of exposure. With the development of PMF, the initial restrictive pulmonary function abnormalities were followed by steadily worsening airflow obstruction. Lung biopsies confirmed silicosis in three cases. Tuberculosis was confirmed in two cases and suspected and treated in a third. Workmen's Compensation was awarded in five cases. The survey confirmed that in semiprecious gem stone processing, the risk of silicosis appears to be confined to stone sculptors. Tried and proven techniques of general and local exhaust ventilation combined with water or oil to control dust at source were capable of effectively reducing dust emission to acceptable levels.

In plain English

This article reported six cases of silicosis in men who hand-sculpted semiprecious gemstones in Western Cape lapidaries, seen at a Cape Town clinic since 1976, plus a health and dust survey of one lapidary. The stones included tiger's-eye, a form of silicified crocidolite found with crocidolite asbestos deposits, and rose quartz, amethyst and quartz crystal. The authors considered whether the disease might resemble asbestosis, but lung biopsies in three men showed silicosis, and settled dust in the surveyed lapidary contained 79-81% free crystalline silica and no fibers. Four men had progressive massive fibrosis; two died of respiratory failure. Tuberculosis was confirmed in two cases and suspected and treated in a third. Among all 21 surveyed employees, only one, a sculptor, had a chest X-ray suggestive of silicosis. The authors concluded that dust control there was sufficient and that this man had likely developed silicosis in earlier employment. They noted that the respirable proportion of the dust was not analyzed.

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: Case series (six case reports) combined with a health and hygiene survey, including dust sampling, at one lapidary
• Who was studied: Six male gemstone sculptors, aged 29 to 56 at presentation, seen at the Respiratory Clinic of the University of Cape Town and Groote Schuur Hospital, South Africa, since 1976. In addition, all 21 employees of one of the two lapidaries still operating in the Western Cape were surveyed, with case 6 detected in that survey in 1989.
• Exposure: Dust from hand-sculpting semiprecious stones against a mechanical abrasive belt or disc, usually carborundum. The stones were tiger's-eye (described as silicified crocidolite, found with crocidolite asbestos deposits), rose quartz, amethyst, quartz crystal and other local stones. In five cases the lapidaries had no specific dust control.
• Main results:
  • Progressive massive fibrosis or accelerated silicosis was found in four of the six cases.
  • Lung biopsies from three cases (cases 1, 3 and 5) showed silicotic pathology rather than an asbestos-type disease.
  • Two of the six men (cases 2 and 3) progressed to respiratory failure, cor pulmonale and death.
  • Among the six cases, tuberculosis was confirmed in two and suspected and treated in a third.
  • Workmen's Compensation was awarded in five of the six cases.
  • In case 1, lung function declined after 1981, with FEV1 falling by about 100 ml per year as severe airflow obstruction developed.
  • Of the 21 surveyed employees, only one (case 6, one of the two stone sculptors) had a chest radiograph suggestive of silicosis.
  • Personal sampling of 830 liters of air over one working shift of case 6 found a respirable dust level of less than 0.0001 mg per cubic meter.
  • Settled dust from near the sculpting operations at the surveyed lapidary contained 79-81% free crystalline silica, and no fibers were present.
• The authors' conclusion: The authors concluded that sufficient dust-control measures had been taken in the surveyed lapidary, that the risk of silicosis there was low, and that case 6 was likely to have developed silicosis in previous employment. They attributed his relatively mild disease to water or oil used to dampen dust at source, combined with local and general exhaust ventilation.
• Limitations the authors state:
  • The proportion of the settled dust that was respirable was not analyzed.

Topics

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

Medical terms in this study, explained in our Lexicon: Silicosis, Pneumoconiosis, Dust Control, Fibrosis, Obstructive Lung Disease.

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