Correspondence on ‘Demographic, exposure and clinical characteristics in a multinational registry of engineered stone workers with silicosis’ by Hua et al

In 2018, we reported in this journal seven cases of artificial (engineered) stone silicosis in Australia and described it as a ‘rapidly emerging’ occupational lung disease. Last year, also in OEM, we reported a further 86 workers with silicosis identified during the first year of a targeted health assessment programme for stone benchtop industry workers in Victoria, Australia. There is now ample evidence that an epidemic of silicosis in the stone benchtop industry is no longer ‘emerging’, but has now occurred Australia, and is highly likely to be replicated in all countries where artificial stone has become popular. We read with great interest the paper by Hua et al, detailing the initial findings of the Engineered Stone Silicosis Investigators (ESSI) Global Silicosis Registry. The authors report 169 cases of artificial stone silicosis from Israel (125), Spain (20), Australia (14) and the USA (10). This collaboration further increases our understanding of artificial stone silicosis, which is occurring in a relatively young worker population, almost onethird of whom have the more severe form of progressive massive fibrosis (PMF). The authors acknowledge that workers enrolled in the registry are a small subset of those currently diagnosed with artificial stone silicosis worldwide. It is important however for readers to understand how small this subset is, to have a better understanding of the extent of the occupational disease epidemic that is occurring in the stone benchtop industry. The 14 Australian cases reported in the paper are all from Queensland, only one of Australia’s eight states and territories. In order to gain a better estimate of the number of workers that have been diagnosed with artificial stone silicosis throughout Australia, we undertook a review of all publicly available data published by Australian work, health and safety agencies (table 1). We identified 579 cases of artificial silicosis, more than 40 times the number recorded from Australia in this paper. The 579 cases we have identified are still likely to be a significant underestimation of the actual number of affected workers. Case identification in Australia has however improved through active screening programmes, as reflected in the shorter work tenure at the time of diagnosis of ESSI participants from Queensland, 10.6 years, compared with 19.9 years for the whole registry. The Queensland Government has operated a very large screening programme open to stonemasons exposed to crystalline silica dust from artificial stone. This extensive programme is highly valuable because it provides the first credible insight into the prevalence of disease in this industry. As of March 2022, the programme has completed assessments of 1053 workers and identified 238 with silicosis, including 35 with PMF. This indicates a 23% prevalence of silicosis of those screened from this industry. In the USA, artificial stone benchtop (also known as ‘countertops’) popularity has grown at an exceedingly fast rate. Imports of the material increased by approximately 800% during 2010– 2018 and there are an estimated 100 000 workers in the US stone fabrication industry. If the prevalence of silicosis in the USA is anywhere near the 23% identified in Queensland, the number of affected workers would dwarf the number who contracted silicosis from the Hawks Nest Tunnel Disaster, which is still considered to be one of the worst industrial disaster in the history of the USA. There are many other countries where outbreaks of artificial stone silicosis have been reported which are not yet included in the ESSI registry. Data from China are particularly concerning. Quan et al recently described 80 patients from Shanghai with artificial stone silicosis and a median duration of exposure of 7 years. Similarly, Wu et al reported a cohort of 18 workers with artificial stone silicosis from Beijing and mean time from initial exposure to development of silicosis of 6.1±2.9 years. These durations of exposure are far shorter than the 19.9 (±9.8) years reported by ESSI and considering the severity of disease in their cohorts, likely to be due to extremely high levels of silica exposure. Rapid disease progression was reported in both studies from China, Wu reporting 28% mortality within the 12month followup period. We applaud the development of the ESSI Global Silicosis Registry. International collaboration will be a necessity to protect increasing numbers of workers around the world who are exposed to highly hazardous silica exposures caused by work with artificial stone. We, however, disagree with Hua et al that there is an ‘emerging’ population of affected workers which they based on the very incomplete numbers recorded in their paper. Active screening of worker from the stone benchtop industry has demonstrated that the epidemic of artificial stone silicosis is well and truly here. The time for preventive action is now.