Silica-associated systemic sclerosis in 2017: 60 years

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LETTER TO THE EDITOR. Silica-associated systemic sclerosis in 2017: 60 years after Erasmus, where do we stand? Alain Lescoat1,2. & Catherine Cavalin3,4,5 ...
Clin Rheumatol DOI 10.1007/s10067-017-3576-y

LETTER TO THE EDITOR

Silica-associated systemic sclerosis in 2017: 60 years after Erasmus, where do we stand? Alain Lescoat 1,2 & Catherine Cavalin 3,4,5 & Odile Macchi 3,6 & Patrick Jégo 1,2 & Paul-André Rosental 3,7

Received: 2 February 2017 / Accepted: 7 February 2017 # International League of Associations for Rheumatology (ILAR) 2017

Dear Editor, We read with interest the article entitled BOccupational and environmental scleroderma. Systematic review and metaanalysis^ by Rubio-Rivas et al. [1] which constitutes one of the largest meta-analysis ever done before in occupational and environmental systemic sclerosis (SSc) and concludes that crystalline silica (silicon dioxide, SiO2) and solvents are the two most likely substances related to the pathogenesis of SSc. From these results, authors hypothesize that while silica is involved in particular jobs, solvents are widespread and more people are therefore at risk of having incidental contact with them. This conclusion seems to play down SiO2 involvement in SSc. We would like to discuss this statement. Although it is well recognized that SiO2 is an ubiquitous air contaminant, occupational exposure to this chemical substance probably remains largely underestimated. Its use in many industrial fields and processes may be rather invisible which can contribute to conceal its hazard [2]. Beyond mining * Alain Lescoat [email protected]

1

UMR INSERM U1085, Research Institute in Health, Environment and Occupation / Institut de Recherche sur la Santé, l’Environnement et le Travail (IRSET), University of Rennes 1, Rennes, France

2

Department of Internal Medicine, CHU Rennes, University of Rennes 1, Rennes, France

3

Silicosis project, ERC Advanced Grant, Centre for European Studies, Sciences Po, Paris, France

4

Laboratory for Interdisciplinary Evaluation of Public Policies, Sciences Po, Paris, France

5

Centre for Employment Studies, Noisy-le-Grand, France

6

Centre for Historical Research, CNRS-EHESS, Paris, France

7

National Institute for Demographic Studies (INED), Paris, France

industries, exposure to crystalline silica appears to be significant in other sectors such as building activities, agriculture, foundries, or textile transformation (denim sandblasting) [3, 4]. The building collapses due to the attacks on the World Trade Center exposed thousands of rescue/recovery workers and residents to inorganic dusts, leading to a major occurrence of autoimmune disorders in the highly exposed groups [5]. The growing use of high-silica-content (> 90% SiO2) materials in manufacturing artificial stone products, has entailed local clusters of silicosis-associated autoimmune diseases, including silica-associated SSc [6]. Para-occupational and non-occupational exposures to crystalline silica also do exist and include daily life activities such as non-occupational use of scouring powder, handling and washing of dusty clothes, and do-it-yourself hobbies practiced repetitively without protections. These activities are almost never recorded in questionnaires used for case-control or cohort studies [1]. As SiO2 constitutes the major mineral component of earth crust, with heterogeneous silica contents in different types of soils, some authors have suggested that these geological differences could explain some spatial heterogeneity in SSc prevalence, subsequent to different passive environmental exposures by inhalation [7]. In rheumatologic and pathophysiological perspectives, recent studies have highlighted the association between exposure to SiO2 and visceral manifestations of SSc, such as pulmonary fibrosis and diffuse cutaneous involvement [8]. However, in these studies, as in all studies included in Rubio-Rivas’ meta-analysis [1], the classification criteria used to select SSc patients were the 1980 ACR or LeRoy’s classification criteria for SSc. The updated 2013 ACR/EULAR classification criteria for SSc offer higher specificity and sensitivity to select patients earlier in the disease process and with a smaller visceral involvement [9]. New cohort studies based on the 2013 criteria are needed to precise the role of SiO2 in

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the occurrence of visceral manifestations such as pulmonary fibrosis. Pulmonary fibrosis being one of the leading causes of death in SSc, such surveys would allow to question exposure to silica as a bad prognostic factor. These research questions are also supported by gender considerations among SSc patients: males, suspected to be more heavily exposed to SiO2, also have a worse prognosis in the course of the disease. The invisible and underestimated exposure to SiO 2 and its possible relationship to SSc occurrence and prognosis, highlight the need for a multidisciplinary and decompartmentalized approach, using dust-exposure questionnaires [2] and methods inherited from toxicological, epidemiological, occupational, environmental, and social sciences to better characterize the prevalence and mechanisms of silica-associated SSc, first described in 1957 by LD Erasmus [10] but still poorly considered and understood. Compliance with ethical standards Disclosures None.

References 1.

Rubio-Rivas M, Moreno R, Corbella X (2017) Occupational and environmental scleroderma. Systematic review and meta-analysis. Clin Rheumatol

2.

Vincent M, Chemarin C, Cavalin C, Catinon M, Rosental PA (2015) From the definition of silicosis at the 1930 Johannesburg conference to the blurred boundaries between pneumoconioses, sarcoidosis, and pulmonary alveolar proteinosis (PAP). Am J Ind Med 58(Suppl 1):S31–S38 3. Blanc PD, Järvholm B, Torén K (2015) Prospective risk of rheumatologic disease associated with occupational exposure in a cohort of male construction workers. Am J Med 128(10):1094–1101 4. Parks CG, Cooper GS (2005) Occupational exposures and risk of systemic lupus erythematosus. Autoimmunity 38(7):497–506 Review 5. Webber MP, Moir W, Crowson CS, Cohen HW, Zeig-Owens R, Hall CB et al (2016) Post-September 11, 2001, incidence of systemic autoimmune diseases in world trade center-exposed firefighters and emergency medical service workers. Mayo Clin Proc 91(1):23–32 6. Shtraichman O, Blanc PD, Ollech JE, Fridel L, Fuks L, Fireman E, Kramer MR (2015) Outbreak of autoimmune disease in silicosis linked to artificial stone. Occup Med (Lond) 65(6):444–450 7. Meyer A, Chifflot H, Chatelus E, Kleinmann JF, Ronde-Ousteau C, Klein D et al (2016) Brief report: spatial heterogeneity of systemic sclerosis in France: high prevalence in the northeast region. Arthritis Rheumatol 68(7):1731–1737 8. Marie I, Menard JF, Duval-Modeste AB, Joly P, Dominique S, Bravard P, Noël D, Gehanno JF, Bubenheim M, Benichou J, Levesque H (2015) Association of occupational exposure with features of systemic sclerosis. J Am Acad Dermatol 72(3):456–464 9. Jordan S, Maurer B, Toniolo M, Michel B, Distler O (2015) Performance of the new ACR/EULAR classification criteria for systemic sclerosis in clinical practice. Rheumatology (Oxford) 54(8):1454–1458 10. Erasmus LD (1957) Scleroderma in goldminers on the Witwatersrand with particular reference to pulmonary manifestations. S Afr J Lab Clin Med 3(3):209–231