How to advise a patient who has worked with silica dust

A practical guide to help general practitioners assess a patient for exposure to silica dust by Sydney respiratory physician Professor Deborah Yates and occupational hygienists Kate Cole and Maggie Davidson.

Many kitchen benchtop workers in Australia are developing severe silicosis, a disease that is totally preventable and essentially untreatable. Recent press coverage has placed these workers firmly in the public eye. Thus, it is likely that more workers and their families will present to primary care with questions about silica exposure, particularly from engineered stone.

The risks for patients are real but may not become apparent for many years. The stone is safe once installed, but a hazard exists when cutting, polishing or fitting it. This article aims to help with the management of patients exposed to silica and to provide practical information to guide general practitioners.

Background

Silicosis is a mineral dust-induced lung fibrosis (or pneumoconiosis) that is usually progressive but helped by removal of the worker from further dust exposure. Removing the worker from the hazardous environment slows progression and is the rationale for screening workers exposed to crystalline free silica dust — a practice required by legislation. Despite a call from the International Labour Organization and the World Health Organization in 2006 for all countries to set up national programs for elimination of silicosis, Australia is only just developing such a strategy in consultation with Lung Foundation Australia.

Silica exposure is also associated with a number of other diseases of the lungs and other organs, including lung cancer, chronic obstructive pulmonary disease, and systemic infectious and autoimmune diseases (here and here). This may not yet be widely appreciated by some health care practitioners, and there is significant underestimation of the burden of disease.

What should a practitioner do when a patient asks about silica dust exposure?

From years of experience in this field, we recommend the following steps.

The first thing to do is to assess the patient’s silica exposure. This is the best way of estimating risk of disease. Silicosis is usually a “silent” disease with a long latency period (ten to 40 years), although engineered stone silicosis may develop faster than classical silicosis, sometimes within five to ten years (here).

The Australian Government’s National Dust Disease Taskforce (NDDT) has recently published helpful guidance for doctors assessing workers exposed to respirable crystalline silica dust, which were produced in collaboration with the position paper of the Thoracic Society of Australia and New Zealand.

Patients’ history of exposure

The most important thing to do clinically is to take a thorough occupational history and record the details carefully in the notes. Enquire all the way back into the patient’s work history starting with their first job, and then go through all the jobs in chronological order. Early work is often relevant, particularly when the lungs are still growing. It is helpful to have a partner available to jog the patient’s memory, and to book a long appointment. Details needed include the name of the employer and the approximate dates when exposed.

Ask about possible sources of silica, which include artificial (or engineered) stone, natural stones (eg, sandstone), cement and concrete, bricks, tiles, ceramics, or jewellery making. Some natural stones such as marble have much lower silica levels than engineered stones, but some are comparable (eg, sandstone).

Dust levels in the past were in general higher than nowadays, except in the stone benchtop industry. In addition to silica dust, there are other things in artificial stone which can cause disease, so it is important to record all details. Another thing to remember is that silica dust itself is invisible, therefore visible dust may not reflect the true hazard.

Ventilation

It is also worthwhile asking about ventilation conditions. Ask whether work was underground or in enclosed spaces. Working outdoors is better than in an enclosed space, but is by no means safe. Grinding or drilling stone produces freshly fractured silica, which is more hazardous than exposure to weathered rock.

Although ventilation systems in mines or tunnels may exist, or someone may work in an air-conditioned cabin, these often reduce rather than prevent dust inhalation and do not preclude significant silica exposure. Workers will often describe being covered by dust at the end of the day or working in a “snowstorm”.

Ask also about the use of water to suppress dust and about the use of masks. These are required by law, but do not always happen.

Mask wearing

The right type of mask (at least a P2) is important. The minimum type of mask needed is a P2 respirator, but these need to be supplied with fit testing, replaced regularly, and workers need to be clean shaven and trained for them to be effective.

Mask wearing is uncomfortable, particularly during manual work, and it is quite common for workers to use masks occasionally rather than continuously.

Masks are meant to be provided by employers, but this may not always happen, and sometimes supplies run out.

Dust sampling and high risk industries

Ask also about dust sampling, which should have occurred if there is a significant silica risk, and whether workers have any knowledge of the results. Unfortunately, in a non-unionised workforce this is exceptional.

Silica exposure is widely encountered in a wide variety of different occupations and situations (Table 1). For example, silicosis can occur in the jewellery trade where workers polish gems, and also in dental workers who mix powders, grind and polish dental prostheses.

In general, crystalline silica dust levels are lower in natural than in engineered stones but some natural stones can have high levels (eg, sandstone) (Table 2). Hence the need for recording every job carefully.

History of the patient’s respiratory disease

Once the occupational history is recorded, the next action is to assess the patient thoroughly for respiratory disease and non-occupational contributors. This means taking a detailed respiratory history, and a history of inhaled substance use, including smoking, vaping and cannabis use. Recreational factors generally increase the risk of disease (eg, smoking and silicosis). This is a good opportunity for more antismoking advice!

Clinical examination is frequently normal in silicosis, but even a recorded normal chest examination can be a helpful baseline. Spirometry should also be performed, without post-bronchodilator readings unless there is a history of airflow obstruction (here and here). A chest x-ray is required, and noting the history of silica exposure on the form enables the radiologist to think about this possibility.

How to refer and when

Many cases of severe silicosis in young men are still being discovered in occupational surveillance programs, and the GP is the first port of call for clinical advice. Ideally, workers should be evaluated by an occupational or respiratory physician, but there are many practical hurdles to be overcome, such as finding a suitably experienced and available physician, accessing tests done using the right standards, and cost considerations.

The employer should fund such examinations but may not in practice. Unfortunately, there is no Medicare item number for an occupational physician consultation. Although in theory a worker can access a respiratory physician via the public hospital system, in practice there is a long wait. Thus, a worker may continue to be exposed to hazardous dust for too long. The costs of outpatient investigations are also a deterrent.

If the patient is referred privately, they may end up with a bill that they cannot afford, as well as a diagnosis that might make them unemployable. Not a good choice. This may be one of the reasons that workers present late and can often get “lost” in the system. In New South Wales, one way to get a free assessment is for the worker to apply for compensation to iCare Dust Diseases, and in Victoria there is a dedicated hospital occupational lung clinic funded by SafeWork. iCare assessments are funded by an employer levy, and include a respiratory assessment, an occupational history, and appropriate testing.

The results are discussed by a Medical Assessment Panel, which consists of three respiratory physicians with special expertise in occupational lung disease. Unfortunately, the Panel’s function is not to diagnose disease but to assess for compensable lung disease. If the worker is found to have early disease, then they will be eligible for future consultations and tests paid for by iCare, and will undergo regular surveillance. However, recommendations about reducing further dust exposure are not enforceable, so the patient has to go back to their GP or respiratory physician for advice.

Furthermore, workers can continue in the same employment and are not obliged to come for further testing. There is no feedback to employers, although cases are now reported to SafeWork, who have the power to inspect workplaces.

Lastly, the practitioner needs to report any case of silicosis diagnosed. Silicosis is a scheduled condition under each state’s Public Health Act and there is a form available online (albeit different for each state) that can be printed off and returned to the jurisdictional health department. Again, this is a report rather than the clinical advice that a patient may really seek.

The system relies heavily upon the employer fulfilling statutory obligations – something which has already been shown not to work – and needs to change.

Importance of data

There are still many practical difficulties preventing a worker from reducing or ceasing dust exposure. These patchy systems also result in significant underestimation of the true burden of disease. There are no national data for Australia as a whole and no way of knowing exactly how large the existing data gap is.

The NDDT recommended a National Occupational Disease Register (NODR) should be implemented by 2022 but this has been slow to eventuate. Good national data are urgently needed to measure efficacy of preventive measures. We need national data and a system that is flexible enough to detect early disease, which workers can actually use. Also, we need a system that is centred in health rather than in regulation, producing real long term health improvement.

Professor Deborah Yates is a Respiratory Physician in the Department of Thoracic Medicine at the St Vincent’s Hospital in Sydney and a Conjoint Associate Professor at the University of NSW. She is also trained in Occupational Medicine with a Masters in Occupational Medicine from the London School of Hygiene and Tropical Medicine and AFOM (UK) and a Cambridge MD. She is a Fellow of the Thoracic Society of Australia and New Zealand (TSANZ) Lead for Occupational Lung Disease and a Fellow of the TSANZ.

Kate Cole is a certified Occupational Hygienist and immediate past president of the Australian Institute of Occupational Hygienists.

Margaret Davidson PhD, MAIOH is a certified Occupational Hygienist and lecturer, Western Sydney University.

The statements or opinions expressed in this article reflect the views of the authors and do not necessarily represent the official policy of the AMA, the MJA or InSight+ unless so stated. 

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