Research summary

Exposure to Silica Warrants Closer Monitoring in Those With Systemic Sclerosis

According to findings from a recently published study, exposure to silica was associated with younger age at diagnosis, more severe disease, organ involvement, and increased mortality among those with systemic sclerosis (SSc).

Researchers evaluated the frequency of occupational silica exposure in 1439 patients with SSc (86.7% women) participating in the Canadian Scleroderma Research Group registry from 2004 to 2009 and evaluated potential links with demographic and clinical features.

Among the total patients, 95 patients (6.6%) reported having worked in hard rock, coal mining, or other occupations where they could have been exposed to silica dust. The percentage of men who reported silica exposure was greater than that of women (22.4% vs 4.2%, respectively).

At first evaluation, patients reporting silica exposure were considerably more likely to be men (45.3% vs 11.1%) and younger at diagnosis (44.9 vs 47.2 years) than the nonexposed group. Exposed patients also were more likely to have diffuse cutaneous SSc (dcSSc) (51.6% vs 35.3%), and had thicker, more scarred skin, more severe gastrointestinal disease, and more severe interstitial lung disease (ILD).

When factoring in multiple variables, patients exposed to silica were almost eight times more likely to be men and 58% less likely to be aged 50 years or older at diagnosis than those declaring no exposure. Silica exposure also was correlated with a twofold greater likelihood of having severe ILD and a 11% greater chance of having severe gastrointestinal disease.

Gender differences also were observed, with exposed women being 60% less likely to be aged 50 years or older at diagnosis compared with nonexposed. Men exposed to silica were 12 times more likely to be White, had a nearly six times higher probability of having more severe ILD, and were almost five times more likely to be smokers than those not exposed to silica.

When the researchers evaluated whether exposure to silica predicted a worse disease prognosis, they discovered that, after adjusting for possible influencing factors, patients with silica exposure had a 50% lower chance of experiencing, for the first time, SSc symptoms and specifically the Raynaud phenomenon at age 50 years or older.

“Our findings suggest that prior silica exposure among SSc patients in North America is common, particularly among males and younger females and these patients are at risk of worse outcomes,” the authors wrote. However, currently “there is no specific treatment available for SSc associated with silica exposure aside from discontinuing exposure, smoking cessation, and SSc management."

The researchers also noted that earlier diagnosis of SSc could result in counseling about discontinuation of silica exposure as well as encourage earlier screening for systemic involvement which, in turn, may encourage treatment initiation.

Lastly, the authors indicated that large prospective studies with comprehensive exposure/occupational questionnaires and job matrices are necessary to further investigate the correlation between silica exposure and prognosis of patients with SSc.


—Yvette C Terrie, BS. Pharm, R.Ph.



Muntyanu A, Milan R, Rahme E, et al. Exposure to silica and systemic sclerosis: A retrospective cohort study based on the Canadian Scleroderma Research Group. Front Med (Lausanne). 2022;9:984907. doi:10.3389/fmed.2022.984907.