Respiratory effects from industrial talc exposure among former mining workers

Our plain-English summary of Respiratory effects from industrial talc exposure among former mining workers, by R.C. Loyola, A.P. Carneiro, A.M. Silveira, et al (Revista de Saúde Pública, 2010).

The study

• Authors: R.C. Loyola, A.P. Carneiro, A.M. Silveira, F. La Rocca Pde, M.S. Nascimento, R.H. Chaves
• Journal: Revista de Saúde Pública
• Published: 2010;44(3):541-7
• Cited by: 5 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Objective: To evaluate late respiratory effects from occupational inhalation of talc contaminated with asbestos.

Methods: This was a case series study on 29 former talc mining workers with asbestos contamination, in the municipality of Carandaí, Southeastern Brazil, who were attended at the State Workers' Health Reference Center in 2004 and 2005. Their clinical and occupational histories were obtained and they underwent spirometry and chest radiography. An exposure score was created; multiplying this by duration produced a cumulative talc exposure index. To confirm the association between the cumulative exposure index and the presence of radiological abnormalities suggestive of pneumoconiosis and/or pleural abnormalities, an exact logistic regression model was fitted to this.

Results: All the former workers were males, with an average age of 48.2 years. Chest radiographs showed pleural abnormalities in three of them; parenchymatous opacity compatible with pneumoconiosis in one; and suspected pneumoconiosis in six. Spirometric abnormalities were found in three workers. Logistic regression showed an odds ratio of 1.059 (95% CI: 1.012; 1.125) for the cumulative exposure index, i.e. each unit increase in the index resulted in an increase of 5.9% in the chance of presenting radiological abnormalities compatible with or suspicious of pneumoconiosis. With regard to the median estimated latency period between the start of exposure and the diagnosing of pleural plaque, there was a significant difference (p = 0.013) between the cases (27.0 years) and non-cases (14.3 years).

Conclusions: These findings indicate the need for clinical control among workers who have been exposed to asbestos, particularly because of the late effects from exposure to this mineral.

In plain English

This case series examined 29 former workers of a talc mining and milling company in Carandaí, Southeastern Brazil, seen at a state workers' health center in 2004 and 2005. Nineteen were among the 48 who worked there from 1994 to 1999; ten had worked there before 1994. Mineral samples showed the talc was contaminated with amphibole asbestos (actinolite-tremolite). All were men; median exposure was 3.0 years. Chest X-rays showed six with findings suspicious of pneumoconiosis, one compatible with it, and three with pleural plaque. The seven with lung opacities had a higher median cumulative exposure index (28.0) than the 22 without (4.6). Each one-unit rise in the index was associated with a 5.9% higher chance of these findings (odds ratio 1.059, 95% CI 1.012 to 1.125). Plaque was not significantly linked to the index. Workers with plaque had a significantly longer median time since first exposure (27.0 vs 14.3 years). Three of 22 tested had obstructive breathing results. The authors called for long-term clinical and radiological follow-up, and noted the small, non-representative group and lack of dust measurements as limitations.

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 based on clinical evaluations of former workers, with descriptive statistics and an exact logistic regression model
• Who was studied: 29 former workers of a talc mining and milling company in Carandaí, Southeastern Brazil, evaluated at the state workers' health reference center (CEREST-MG) in Belo Horizonte between September 2004 and April 2005. Of these, 19 were among the 48 people who worked at the company between 1994 and 1999 (40% of that group), and ten had worked there before 1994. All were male, aged 33.7 to 68.5 years (mean 48.2). Ten former workers declined the invitation.
• Exposure: Talc contaminated with amphibole asbestos (actinolite-tremolite). Exposure came from mining (extraction with explosives, manual breaking of rock) and from milling and sacking in an enclosed shed with poor dust extraction. Masks were not used. Exposure lasted 0.3 to 28.1 years (median 3.0). The authors built a cumulative exposure index by multiplying job-based dust scores (1 or 2) by the years spent in each job. Eight workers had also worked at two other companies, one of which extracted limestone.
• Main results:
  • Chest radiograph profusion of small opacities: 22 workers were 0/0 (non-cases), six were 0/1 (suspected pneumoconiosis) and one was 1/1 (pneumoconiosis). No large opacities were seen.
  • Pleural plaque was found in three former workers, bilaterally in two of them.
  • The median cumulative exposure index was 4.6 for the 22 workers classified 0/0 and 28.0 for the seven classified 0/1 or higher (p = 0.013).
  • The median cumulative exposure index was 4.8 for workers without pleural abnormalities and 19.0 for those with them (p = 0.56, not statistically significant).
  • Estimated latency time was measured from the start of exposure to the evaluation. The median was significantly longer for workers with pleural abnormalities alone (27.0 years) than for those without (14.3 years) (p = 0.013). It did not differ significantly between workers with profusion 0/1 or higher (19.0) and those at 0/0 (13.3).
  • The exact logistic regression looked at parenchymal radiological abnormalities (profusion 0/1 or higher). Each one-unit increase in the cumulative exposure index was associated with a 5.9% increase in the chance of these abnormalities (odds ratio 1.059, 95% CI 1.012 to 1.125). Estimated latency time was not significant and was dropped from the model.
  • Of the 22 workers who had spirometry, 19 (86.4%) had normal results and three (13.6%) had obstructive ventilatory disorders. Spirometry did not differ significantly between subgroups with and without pleural or parenchymal abnormalities.
• The authors' conclusion: The authors concluded that the abnormalities found emphasize the need for greater clinical and radiological follow-up of these workers, especially for changes that might occur over the long term, including malignant lesions such as lung cancer and pleural mesothelioma.
• Limitations the authors state:
  • The findings represent only the former workers who attended the clinic, not everyone who worked at the company.
  • The small sample made it difficult to estimate chronic effects and dose-response relationships.
  • Including work at two other mines (talc and limestone) may have been a confounding factor.
  • Past exposure was hard to estimate because there was no environmental surveillance and no quantitative analysis of talc dust while the company operated.
  • The small number of spirometry examinations limited interpretation and the analysis of associations with exposure, smoking or symptoms.
  • High-resolution CT was not used, although the authors describe it as superior to conventional radiography for these abnormalities.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Pleural plaques and thickening, Talc and vermiculite.

Medical terms in this study, explained in our Lexicon: Industrial Talc, Talc, Spirometry, Cumulative Exposure, Pneumoconiosis, Chest X-Ray, Odds Ratio, Latency.

Related studies

• The dust hazard in tremolite talc mining — L. Greenburg (1947)
• Commercial talc and talcosis — B. Weiss, E.A. Boettner (1967)
• Pneumoconiosis and malignant mesothelioma in a family operated metal casting business that used industrial talc from New York state — M.M. Finkelstein (2013)
• An epidemiologic study of a group of talc workers — J.F. Gamble, W. Fellner, et al. (1979)
• Exposure to asbestiform minerals and radiographic chest abnormalities in a talc mining region of upstate New York — E.F. Fitzgerald, A.D. Stark, et al. (1991)
• Evaluation of respiratory effects in miners and millers exposed to talc free of asbestos and silica — D.H. Wegman, J.M. Peters, et al. (1982)

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