Toward Understanding of Environmental Risk Factors in Systemic Sclerosis

Our plain-English summary of Toward Understanding of Environmental Risk Factors in Systemic Sclerosis, by L. Ouchene, A. Muntyanu, J. Lavoué, et al (Journal of Cutaneous Medicine and Surgery, 2021).

The study

• Authors: L. Ouchene, A. Muntyanu, J. Lavoué, M. Baron, I.V. Litvinov, E. Netchiporouk
• Journal: Journal of Cutaneous Medicine and Surgery
• Published: 2021;25(2):188-204
• Type of article: Review
• Cited by: 25 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Importance: Systemic sclerosis (SSc) is a severe, chronic, and incurable autoimmune fibrotic skin disease with significant extracutaneous involvement. Low concordance rate in twin studies and unequal geographic distribution of SSc argues for importance of environment in disease initiation and progression.

Objective: In this manuscript we provide a summary of all investigated potential external risk factors for SSc.

Data Sources: A literature search in PubMed and EMBASE database was performed for studies published until January 1, 2020 by 2 reviewers (EN and LO) independently.

Findings: Occupational and/or environmental exposures to silica and organic solvents are associated with increased incidence and severity of SSc. Exposure to epoxy resins, asbestos, and particulate air pollution favors increased risk of SSc, but data are based on limited number of observational studies. There is insufficient evidence to conclude an association between SSc development and other occupational (eg, welding fumes) or personal exposures (eg, smoking, vitamin D deficiency). Association of SSc with silicone breast implants has been disproven. Infectious pathogens (eg, Helicobacter pylori and angiotropic viruses) and dysbiosis seem to play a role in SSc development and severity, but their role remains to be clarified.

Conclusions And Relevance: It may be prudent to counsel our patients with SSc (or those at risk of SSc) to avoid occupations with exposure to silica, organic solvents, asbestos and epoxy resins; restraint from smoking, using cocaine or drugs with pro-fibrotic potential. While the association between low vitamin D and SSc remains to be confirmed, we believe that SSc patients should be encouraged to maintain healthy vitamin D levels as benefits outweigh the risks.

In plain English

This article was a scoping review of earlier research, not a new study. The authors searched PubMed and EMBASE for studies published until January 1, 2020, in English, French, Spanish or Russian. They looked for outside factors that might trigger or worsen systemic sclerosis (scleroderma), an autoimmune disease that causes scarring of the skin with significant involvement beyond the skin. They did not use quality criteria to decide which studies to include. For asbestos, they cited a report from Libby, Montana, where asbestos-laden vermiculite was used. Of 6603 inhabitants, 13.8% had been diagnosed with an autoimmune disease, including 10 cases of systemic sclerosis, which the review described as 7-fold higher than the expected United States prevalence. Of two other studies the review cited, one reported an odds ratio of only 1.2 and the other did not reach statistical significance. The authors called the asbestos evidence limited and said more studies were needed to confirm the association and causality. They rated silica and organic solvents as having the strongest evidence. The authors concluded that epoxy resins, asbestos and particulate air pollution favor increased risk, but that further studies are 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: Scoping review of published studies (following the PRISMA Extension for Scoping Reviews)
• Who was studied: Published studies found in PubMed and EMBASE up to January 1, 2020, in English, French, Spanish or Russian, on external risk factors for systemic sclerosis; the number of included articles is given only in a figure that is not reproduced in the text
• Exposure: A range of external factors: occupational and airborne exposures (silica, organic solvents, particulate matter, epoxy resins, asbestos, hand-transmitted vibration, welding fumes, pesticides, heavy metals), personal exposures (smoking, cocaine, drugs, silicone implants, vitamin D deficiency), the microbiome and infectious agents. For asbestos, the review names chrysotile as the most common type and discusses asbestos-laden vermiculite in Libby, Montana.
• Main results:
  • Asbestos: in a report cited from Libby, Montana, 13.8% of 6603 inhabitants had been diagnosed with an autoimmune disease, including 10 cases of systemic sclerosis. The review described this as 7-fold higher than the expected United States prevalence.
  • Asbestos: of two other observational studies cited, the first reported an odds ratio the review called 'only' 1.2. The OCR text prints this as '1.269', apparently 1.2 followed by reference number 69. In the second study the odds ratio did not reach statistical significance.
  • Silica and organic solvents were the exposures with Level II evidence derived from 20 or more observational studies and meta-analyses
  • Silica: a cited meta-analysis of cohort studies (247 563 patients) found greater incidence of systemic sclerosis in silica-exposed workers (RR 17.52, 95% CI 5.98-51.37; P less than .001)
  • Organic solvents: data cited from meta-analyses suggested a 2 to 3-fold increased risk of systemic sclerosis (RR 2.91, 95% CI 1.60-5.30)
  • Epoxy resins: a cited meta-analysis of four studies found an OR of 2.97 (95% CI 2.31-3.83)
  • Welding fumes: a cited meta-analysis of 4 case-control studies found a nonsignificant association (OR 1.29, 95% CI 0.44-3.74)
  • Smoking: the review found the evidence for smoking as a trigger of the disease limited, although smoking was linked to worse morbidity and mortality in patients
• The authors' conclusion: The authors concluded that occupational and/or environmental exposure to silica and organic solvents is associated with increased incidence and severity of systemic sclerosis. They also concluded that exposure to epoxy resins, asbestos and particulate air pollution favors increased risk, but that further studies are needed.
• Limitations the authors state:
  • Quality criteria were not used to decide which studies to include
  • No Level I (randomized trial) evidence was available, because randomized trials cannot be done for environmental exposures
  • The search was limited to English, French, Spanish or Russian
  • Epidemiological evidence linking asbestos and systemic sclerosis was limited, and more studies were needed to confirm association and causality

Topics

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

Related studies

• High prevalence of occupational exposure to solvents or silica in male systemic sclerosis patients: a Belgian cohort analysis — E. De Decker, M. Vanthuyne, et al. (2018)
• Malignant pleural mesothelioma in a patient with systemic sclerosis: the first report — N. Singh, K. Madan, et al. (2013)
• Occupational and environmental risk factors for idiopathic pulmonary fibrosis in Australia: case-control study — M.J. Abramson, T. Murambadoro, et al. (2020)
• Pleural mesothelioma in New Caledonia: associations with environmental risk factors — F. Baumann, P. Maurizot, et al. (2011)
• Indigenous health and environmental risk factors: an Australian problem with global analogues? — L.D. Knibbs, P.D. Sly (2014)
• Low dose exposure to natural and man made fibres and the risk of cancer: towards a collaborative European epidemiology. Report of a workshop held in Paris , 10-12 June, 1991 — A.J. Valleron, J. Bignon, et al. (1992)

Browse return to medical research.