Stonemasons with silicosis: Preliminary findings and a warning message from Australia

The use of artificial stone products for home benchtops is becoming increasingly popular. Artificial stone products have a higher silica content (>90%) when compared to natural alternatives (2–30%). Due to the high silica content of the material, the potential exposure of respirable crystalline silica (RCS) to stonemasons has increased. The first Australian case of silicosis associated with artificial stone was reported in 2015, followed more recently in 2017 by a case series of eight patients. This case series attributed the identified disease to a failure of the industry regulators to enforce adequate dust control. In 2018, following the diagnosis of several stonemasons with silicosis in South East Queensland, WorkCover Queensland (WCQ) funded workplace visits and health screening across 10 local workplaces. By late 2018, this initial review had expanded to involve health screening for all stonemasons employed in Queensland. As of May 2019, WCQ has accepted 141 silicosis claims, amongst 659 stonemasons, with screening continuing. The authors of this letter have been involved in the care of approximately half of these cases. We aim to share our early observations and draw attention to the occupational risks within this industry. This study was a retrospective review of silicosis identified within Queensland stonemasons since December 2018. B-reader chest radiograph reports conducted to the International Labour Organization (ILO) standard were reviewed to determine disease severity. Data pertaining to occupational history were collected by review of medical charts. We focused on three high-risk occupational behaviours in particular, whether a subject: (i) worked with artificial stone products for >50% of their total tenure, (ii) used personal protective equipment (PPE) for <50% of their total tenure and (iii) performed >50% of their work using dry cutting techniques. All 78 subjects were males, with a mean age of 34.1 years (range: 23–63; median: 33). The subjects had a mean tenure in stonemasonry of 12.9 years (range: 2–45; median: 12). Complete occupational details were available for 62 subjects. All subjects reported at least one of the three high-risk work practices with the majority of subjects (68%) reporting all three. Predominant use of artificial stone products and dry cutting techniques were the most common high-risk work practices, reported by 90% and 87% of subjects, respectively. All subjects were diagnosed with either accelerated (n = 36) or chronic (n = 42) silicosis by their treating respiratory physician. ILO grades were available for 67 subjects (Table 1). A normal chest radiograph (ILO grade of 0) was observed in 43% of the subjects. On the other end of the spectrum, progressive massive fibrosis (PMF) was observed in 21% of subjects. Bilateral PMF opacities were detectable on chest radiograph in nine of these subjects (64%). Reported here are the preliminary findings of the second largest case series of silicosis attributed to stonemasonry. Occupational practices reported by the subjects are not in keeping with those advised by regulatory bodies. The hierarchy of hazard controls describes systems to minimize hazards in the workplace. Three of the components described in this hierarchy, in order of effectiveness, are the substitution of hazardous practices for those which are not, the use of engineering controls and the use of PPE. A key observation in this study was that 68% of subjects reported a failure to abide by any hazard controls regarding RCS exposure. It is in this frightening context that we have seen silicosis emerging as a health crisis amongst stonemasons. Although it is not possible to retrospectively determine RCS levels in the working environments for the subjects, recent research from the Office of Industrial Relations found that RCS levels were as high as 0.69 mg/m in shapers even when using wet cutting techniques. The use of wet cutting has been associated with a 91% reduction in exposure, suggesting that during dry cutting practices, workers are exposed to RCS levels many factors higher than the occupational exposure limit of 0.1 mg/m.9 Chest radiographs were used to quantify the severity of disease. Interestingly, 43% of reviewed ILO reports were described as normal, suggesting chest radiographs may have a low sensitivity for silicosis in these workers. In these cases, the treating respiratory physician relied on high-resolution computed tomography (HRCT) and spirometry results for diagnosis. This is not a foreign concept, as other studies have reported higher sensitivity of HRCT than chest radiograph for screening of pneumoconiosis. Further analysis comparing chest radiographs and HRCT in our subjects is underway and is expected to shed light on this observation and guide future pneumoconiosis screening programmes. An international study, which reviewed 46 stonemasons with silicosis who had worked with artificial stone, found 8.7% presented with PMF, far lower than our 21%. In support of this, PMF has been diagnosed in Received 4 June 2019; invited to revise 15 July 2019; revised 15 July 2019; accepted 23 July 2019 (Associate Editor: Ioannis Kalomenidis; Senior Editor: Phan Nguyen)