Last reviewed 22 February 2021

A study involving the entire working population of Denmark has found that exposure to respirable crystalline silica (RCS) is linked to an increased risk of developing autoimmune rheumatic disorders, including scleroderma and rheumatoid arthritis.

Silica is a natural substance found in concrete, bricks, tiles and mortar — materials commonly used in construction. When “fractured” through processes such as stonecutting, drilling and polishing, it becomes RCS.

The researchers involved in the new study used data from the total Danish workforce — a group of 3 million men and women who started jobs between 1979 and 2015. A total of 17% of men and 3% of women had at some point experienced job-related exposure to RCM.

The researchers found that men with RCS exposure were at a higher risk of developing one of the four rheumatic diseases (rheumatoid arthritis, scleroderma, systemic lupus erythematosus and small vessel vasculitis) with increased risk being based on exposure intensity and duration of exposure.

The researchers noted that many of the individuals who had developed autoimmune rheumatic diseases had been exposed to levels of crystalline silica that were far below the workplace exposure limits that are still in place today. “We observed increased risks of several of the studied autoimmune rheumatic diseases at mean exposure intensity levels well below the current European occupational exposure limit [which is the same in the UK, 0.1mg/m3 respirable dust, averaged over an 8 hour period] … indicating that this limit provides insufficient protection of workers exposed to crystalline silica,” the investigators wrote.

In the UK, the All-Party Parliamentary Group on Respiratory Health’s report Silica — The Next Asbestos?  explores the risk of silica exposure to construction workers and the implications for policy makers. The Parliamentary Group has recommended making silicosis a reportable illness for employers under the Reporting of Injuries, Diseases, and Dangerous Occurrences Regulations 2013 for those who are still at work and exposed.