Silica and asbestos exposure in ANCA-associated vasculitis with pulmonary involvement

Our plain-English summary of Silica and asbestos exposure in ANCA-associated vasculitis with pulmonary involvement, by Z. Rihova, D. Maixnerova, E. Jancova, et al (Renal Failure, 2005).

The study

• Authors: Z. Rihova, D. Maixnerova, E. Jancova, D. Pelclova, J. Bartunkova, Z. Fenclova, Z. Vankova, J. Reiterova, M. Merta, R. Rysava, V. Tesar
• Journal: Renal Failure
• Published: 2005;27(5):605-8
• Cited by: 23 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Silica and asbestos exposure are thought to belong to the triggering factors of antineutrophil cytoplasm antibodies (ANCA)-associated vasculitis. We carried out a study to find out whether patients with pulmonary involvement attributable to ANCA-associated vasculitis (AAV) have been exposed to silicon-containing materials. Thirty-one patients (12 women, 19 men, median age 51 years) were interviewed using a structured questionnaire. Occupational exposure to silicon-containing chemicals was reported by 22.6% of the patients (12.9% to SiO2, 9.7% to asbestos), compared with 0% of control subjects (p<0.05). Our findings support the pathophysiologic role of silica in AAV.

In plain English

This Czech case-control study asked whether patients with ANCA-associated vasculitis (AAV), an immune disease that inflames blood vessels, had worked with silica or asbestos. It included 31 patients with AAV affecting the lungs and kidneys, diagnosed at a Prague nephrology unit between 1993 and 2002 (12 women, 19 men, median age 51). They completed questionnaires designed by occupational health physicians and were compared with 30 healthy office employees matched for age, sex and residence. Seven of the 31 patients (22.6%) reported past occupational exposure to silicon-containing materials: 12.9% to silica and 9.7% to asbestos. None of the 30 controls did. The difference was statistically significant (p less than 0.05). The three asbestos-exposed patients were a heating engineer, a floorer (floor coverings) and a traffic policeman. All exposures were considered low, lasting almost 4 years on average, and no patient had a pneumoconiosis. The authors concluded that silica and asbestos dust exposure is likely a factor that facilitates AAV in the Czech population. They noted that case-control studies are prone to bias in selecting controls and recalling exposure.

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-control study: questionnaire-based occupational exposure histories of patients compared with matched healthy controls
• Who was studied: 31 patients with ANCA-associated vasculitis with pulmonary and renal involvement, diagnosed at the authors' center (Nephrology Unit, Charles University, Prague, Czech Republic) between 1993 and 2002. There were 12 women and 19 men, median age at diagnosis 51 years (range 18 to 75): 22 had Wegener's granulomatosis, 8 microscopic polyangiitis and 1 Churg-Strauss syndrome. They were compared with 30 age, sex and residence-matched healthy office employees.
• Exposure: Past occupational exposure to silicon-containing materials: silica (SiO2) and asbestos (fiber type not specified). It was assessed by a questionnaire designed by occupational health physicians, with extent estimated from intensity, frequency and duration.
• Main results:
  • Seven of the 31 AAV patients (22.6%) had former exposure to silicon-containing chemicals: 12.9% to SiO2 (silica) and 9.7% to asbestos.
  • None of the 30 matched controls had previous occupational exposure to silicon-containing materials. The difference from the patients was statistically significant (p less than 0.05).
  • Among the exposed patients, the mean length of exposure was almost 4 years, and in all cases the exposure was considered low.
  • The three asbestos-exposed patients were all men. One was a heating engineer (7 years of exposure), one a floorer working with floor coverings (1 year) and one a traffic policeman (2 years).
  • Exposure was not significantly associated with sex, smoking, ANCA pattern or disease category. There was a tendency towards higher exposure in the MPO (P-ANCA) group.
  • Smoking was comparable in the AAV patients and controls: 41.9% vs. 43.3% were smokers.
  • The lung involvement in all patients was attributed to AAV. None was diagnosed with any kind of pneumoconiosis.
• The authors' conclusion: The authors concluded that activities and environments with higher silica dust exposure are associated with AAV. They judged that silica and asbestos dust exposure is likely a factor that facilitates the development of AAV in the Czech population, and said causal mechanisms need study in a larger population.
• Limitations the authors state:
  • Case-control studies frequently involve biases, especially in the selection of control subjects and in the recall of exposure history.
  • The study was small; the authors state that the mechanisms of causality must be explored in a larger population of AAV patients.

Topics

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

Medical terms in this study, explained in our Lexicon: Asbestos Exposure, Occupational Exposure.

Related studies

• One agent, many diseases: exposure-response data and comparative risks of different outcomes following silica exposure — K. Steenland (2005)
• The role of metals in autoimmune vasculitis: epidemiological and pathogenic study — P. Stratta, A. Messuerotti, et al. (2001)
• Silicosis and smoking strongly increase lung cancer risk in silica-exposed workers — N. Kurihara, O. Wada (2004)
• Silica exposure and altered regulation of autoimmunity — S. Lee, H. Matsuzaki, et al. (2014)
• Misconceptions regarding the pathogenicity of silicas and silicates — D.S. Feigin (1989)
• Silica and asbestos: contrasts in tissue response — A.G. Heppleston (1979)

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