• Occupational Lung Disease

Silicosis is the most ancient form of occupational lung disease, being known to have caused disability and the premature death of workers for many millennia.1 Despite this, silicosis continues to be a global health problem,2 accounting for almost 13 000 deaths worldwide in 2019.3 Those at risk of this disease commonly work in industries that involve either cutting through silica-containing material (eg, in construction, quarrying, mining, tunnelling and stone masonry) or using sand/clay for manufacturing (eg, in the production of building materials, ceramics and metal objects).2 4

Over the past four decades, outbreaks of silicosis have also been reported in novel workplace settings, affecting individuals working with slate pencils (1980s), denim jeans (2000s), dental supplies (2004) and jewellery/precious stones (2010s).5 The article by Feary et al provides a detailed account of the first cases of artificial stone (AS) silicosis in the UK,6 an epidemic already affecting hundreds of workers around the world.2 5 7–9 Many of the issues raised by Feary et al are common to other silicosis outbreaks, having been repeatedly documented throughout history.

In 1843, Dr Calvert Holland, a hospital physician in my home town of Sheffield, investigated the health of the local cutlery workers,10 11 writing: “It is perhaps more destructive to human life than any pursuit in the United Empire”. Holland found that those employed shaping metal forks using a rotating grindstone had markedly increased mortality, with almost half dead before the age of 30 and none surviving past 50. He realised that the increased mortality related to exposure to the very high levels of dust generated by ‘dry grinding’ forks (without water), which was less of a problem for those ‘wet grinding’ knives. He noted that there was no cure for ‘grinders’ asthma’, recognising the tragic impact that this had on both the individuals and their families. He also highlighted that it was the vulnerability of the workforce—in this case due to poverty and illiteracy—that led workers to continue in the trade, accepting the known health risks.

Observations made by Holland over 180 years ago unfortunately remain very pertinent to the more recent outbreaks of silicosis. The first of these is the very high level of exposure that must occur to result in the death and severe disability of young workers. In the UK there is a legal requirement for employers to conduct a suitable and sufficient risk assessment,12 which for AS work, should have recognised the toxicity of respirable crystalline silica, the very low workplace exposure limit, and the need to adequately control exposure. By design, AS worktops (like grindstones) have a very high silica content to make them more hard wearing and durable. Dry processing of AS with powered tools without the use of water suppression, local exhaust ventilation and respiratory protective equipment exposes workers to very high levels of airborne silica dust, in many cases two orders of magnitude greater than legal exposure limits.9 13

The second relevant factor noted by Holland relates to the vulnerability of the workforce affected by the outbreaks. Many of those at risk of AS silicosis in the UK, Australia and USA are migrant workers whose first language is not English, who may have poor understanding of health risks and limited access to healthcare.9 13 The AS workers in the UK case series were not under annual health surveillance, another legal requirement for those exposed to silica in the workplace.12 Although surveillance was not designed for situations resulting in acute or accelerated silicosis, it would have offered an opportunity for symptomatic workers to be identified at an earlier stage.14

The final factor common to many silicosis outbreaks is the limited socioeconomic options available to affected workers, often with precarious employment circumstances, leaving some individuals with little option but to continue harmful exposures against medical advice.

Considering the availability of AS kitchen worktops, the arrival of AS silicosis in the UK is one which has been feared by clinicians for some time.4 15 While the magnitude of cases remains to be determined, the rapidly progressive forms of silicosis are likely to offer a significant challenge for respiratory physicians who may not recognise the CT changes occurring in young workers with short exposure histories.16 As highlighted by the UK case series and others,15–18 the differential diagnosis of sarcoid is a particular problem, as patients with silicosis may also have lymphopenia, elevated serum angiotensin converting enzyme, bronchoalveolar lavage lymphocytosis and lymph node granulomas on endobronchial ultrasound guided biopsy. Greater awareness of AS silicosis is also required among a wider range of healthcare professionals due to the increased risk of mycobacterial, renal and autoimmune connective disease.6 9 19

The outbreak of AS silicosis in Australia has been of such magnitude and impact that it has resulted in the government providing open access health screening for AS workers8 and taking the decision to ban the importation and use of the material from July 2024.20 The article by Feary et al calls for the UK to consider similar measures to those already taken in Australia. Historically, legislative change in the 1920s was successful in protecting the Sheffield cutlery workers, leading to the industry switching to silica-free grinding wheels.11 Now that the first cases due to AS have been reported, the world watches with interest to see how the UK will react.