Screening reveals high rates of early stage silicosis in stone workers

Lung cancer

By Mardi Chapman

3 Nov 2020

More than a third of stone workers reviewed by a respiratory physician in a Victorian program have been diagnosed with silicosis.

A study of 239 workers who had completed their two-step evaluation in the Victorian Stonemason Health Assessment and Research Programme (V-SHARP) found 86 (36%) had silicosis based on radiological features (ILO chest X-ray and HRCT chest), occupational history and the exclusion of other diagnoses.

All workers diagnosed with silicosis were men with a mean age of 41.8 years. Two-thirds ( 67%) were ever smokers. About half (52.3%) had worked in the industry for 10-20 years, 25.6% for fewer than 10 years, and 22.0% for more than 20 years.

Most of these men (75.6%) were diagnosed with simple silicosis and 24.4% with complicated silicosis.

Workers diagnosed with simple silicosis had well-preserved lung function and most (80%) reported breathlessness only with strenuous exercise.

“The identification of workers with silicosis at an early stage of disease in this programme significantly contrasts most of the reported cases of artificial stone silicosis, which have been identified with symptomatic, if not end-stage, disease,” the study said.

Yet the high number of cases “provide an insight into a systemic failure to recognise and control the risk of work with artificial stone.”

“Ninety-seven per cent of workers referred for secondary evaluation indicated that they had spent time in an environment where water dust suppression was not used when activities such as cutting and grinding of artificial stone was undertaken.”

“Forty-seven per cent of workers spent over half of their work time in an environment where dry processing of artificial stone was undertaken.”

The study authors said that of the workers referred for secondary evaluation and determined not to have silicosis, 7.8% had mediastinal and/or hilar lymphadenopathy.

“So called ‘lymph node silicosis’ has previously been reported in 20% of a cohort of 264 deceased miners; however, the long-term implications of this finding in stone benchtop workers is not known. It is concerning that it may be a precursor to development of parenchymal features of silicosis.”

The investigators also noted that antinuclear antibodies were detected in 37% of the men.

“Longitudinal assessments of stone benchtop workers will require ongoing monitoring for potential development of autoimmune disease, in addition to the respiratory effects of RCS [respirable crystalline silica] exposure,” they suggested

The authors concluded that the health effects of failure to control a clear occupational hazard will be experienced by artificial stone workers for many decades to come.

Lead author Dr Ryan Hoy, told the limbic that the study highlighted the benefits of screening current and former stonemasons.

“Through health screening we have identified a lot of workers with very early stage silicosis – simple silicosis with well preserved lung function. And this is very different from 2017 when we were seeing those people coming through with very severe symptomatic disease – complicated silicosis needing lung transplants.”

“Picking up these affected workers as early as possible, we do think is going to result in the best possible outcome for them.”

“Unfortunately for many workers, this does mean that they do need a change in occupation potentially but that is really critical in terms of reducing the risk of disease progression.”

He said the association between silica dust exposure and autoimmune disease had been well described in other occupational settings.

“And we are certainly starting to see some patients presenting with scleroderma, rheumatoid arthritis and a range of other autoimmune diseases. So we certainly think this is a really important issue that respiratory physicians but also rheumatologists need to be aware of as well.”

Dr Hoy, a respiratory physician, senior research fellow at Monash University, and member of the National Dust Disease Taskforce, said applications were currently open for $4.5 million of silicosis research funding.

As a result, he was optimistic about the development of new treatment options for people with silicosis.

“It’s not just about diagnosing then monitoring them. We are really working towards identifying meaningful treatment approaches as well.”

“Early silicosis is where patients have this ground glass opacity which we think is a more inflammatory stage. Professor Dan Chambers in Brisbane has a lot of interest in whole lung lavage at that early stage of disease.”

“And once there is established fibrosis…then that is when a trial around the role of an antifibrotic agent would be most appropriate.”

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