Workers exposed to silica dust show a higher incidence of blood markers that are the hallmark of autoimmune diseases such as rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE), according to research.

The study, published in the journal, Occupational and Environmental Medicine and led by Monash University’s Professor Karen Walker-Bone, studied a cohort of over 1200 current and former stone benchtop industry workers in Victoria who were offered free screening for silicosis and related disorders between 2019 and 2021. The researchers looked for symptoms or diagnoses of autoimmune disease as well as markers in the blood that could indicate early stages of autoimmune disease.

Among the 1238 workers, 0.9 per cent were confirmed with autoimmune disease, however almost one quarter (24.6 per cent) had detectable anti-nuclear antibodies – 24.6 per cent compared to less than 6 per cent in similarly aged male controls, according to the study, Autoimmune diseases, autoantibody status and silicosis in a cohort of 1238 workers from the artificial stone benchtop industry.

Of the 24.3 per cent of the cohort diagnosed with silicosis, 6.6 per cent had very high levels of anti-nuclear antibodies. Importantly the researchers also found associations between autoantibodies and age, smoking, silicosis, and intensity of silica dust exposure.

According to Professor Walker-Bone, the proportion of workers with detectable markers for autoimmune disease was considerably higher than the 5-9 per cent expected in the general population.

“This data suggests that – as well as screening for silicosis in these workers, they should also be screened for autoimmune disease, as these individuals need specialised management and may be entitled to compensation,” Walker-Bone said.

While cases of autoimmune disease have also been reported in engineered stone benchtop industry workers, this is the first study to look at workers before they develop silicosis.

The finding of detectable markers in the blood of autoimmune disease may be an indicator of the worker developing the disease in decades to come, according to Walker-Bone. “Although having detectable autoantibodies in isolation is not diagnostic of an autoimmune disease, their presence in certain rheumatic diseases, such as SLE and RA, has been shown to predate clinical features often by many years,” she said, prompting calls for the monitoring of autoimmune diseases in this group of workers, in addition to screening for silicosis, the study authors said.

“One concern is that a number of those with detectable autoantibodies will go on to manifest clinical disease with prolonged follow-up. However, the government screening clinics for the diagnosis of silicosis are not set up to bear the costs of longer-term follow-up of workers with high exposure who do not yet have detectable silicosis, let alone those who may /may not develop autoimmune disease,” Walker-Bone said.

In June this year the manufacture, supply and installation of engineered stone benchtops was banned because of the high incidence of the deadly lung disease, silicosis.