Silica

Crystalline Silica

What is Crystalline Silica Dust?

Crystalline silica is one of the most abundant minerals in the earth's crust and is a major constituent of construction materials such as bricks, tiles and concrete, bricks, tiles, mortar. It encompasses minerals such as quartz, cristobalite, tridymite, and tripoli.

The typical crystalline silica content in common materials includes:

  • Sandstone: 70% to 90%
  • Granite: 25% to 60%
  • Ceramic tiles: 5% to 45%
  • Autoclaved aerated concrete: 20% to 40%
  • Slate: 20% to 40%
  • Concrete: Less than 30%
  • Porcelain: 14% to 18%
  • Brick: 5% to 15%
  • Marble: Less than 5%

As well as occurring naturally, stone can also be manufactured from powdered quartz bound together by resins. Known as 'engineered stone' the amount of silica can vary from under 20% to over 90%. In Victoria, with limited exceptions, activities related to the manufacturing, supply, processing, or installation of engineered stone benchtops, panels, or slabs is prohibited.

Crystalline silica consists of silicon and oxygen atoms (SiO2) arranged in a regular crystalline structure. There are different crystalline forms of silica, with the most common being quartz. In some circumstances, for example in the high temperatures of industrial furnaces and kilns, quartz may convert to another crystalline form of silica known as cristobalite. Quartz is found in varying amounts in almost all types of rock, sands, clays, shales and gravel. For example, sandstone is almost pure quartz, whereas granite might contain 15-30% quartz.

Silica dust is so fine it can enter the deepest parts of the lungs. This dust can build up in the lungs and scar them - leading to a number of diseases such a mesothelioma and lung cancer. Exposure to silica dust is prevevalnt in occupations where exposure occurssuch as miners, quarry workers and stone masons, but also workers in construction and demolition and even those exposed to clay in art rooms.

Legal Standards

Silica is classified as a hazardous substance and is therefore regulated under Chapter 4 - Hazardous Substances - of the 2017 Occupational Health and Safety Regulations.  This means that the employer has the legal duty to identify the hazard and eliminate or control any risk, provide information and training, undertake atmospheric monitoring, maintain records and, in the case of crystalline silica, carry out health surveillance.

The exposure standard for respirable crystalline silica dust is 0.05 mg/m³ as a time-weighted average (TWA) airborne concentration over an 8-hour period. An 8-hour TWA exposure standard represents the average permissible airborne concentration of a substance over an 8-hour workday and a 5-day workweek.

WorkSafe Victoria, recommends that employers take a precautionary approach and reduce employees' exposure to below 0.02 mg/m3 as an 8-hr TWA to prevent silicosis and minimise the risk of lung cancer. The Cancer Council of Australia’s view is that there is currently no conclusive evidence to support a safe level of exposure to silica dust at all. 

You can find the Victorian Trades Hall Council Standards for Silica here.

On 1 January 2002, the use of materials containing more than 1% crystalline silica for abrasive blasting was prohibited in all Victorian workplaces. The prohibition was made under the then Occupational Health and Safety (Hazardous Substances) Regulations 1999. This means materials such as silica sand, river sand, beach sand and other white sands must not be used for abrasive blasting. The WorkSafe website has more information on the ban.

Ban of engineered stone

As of July 2024 activities related to the manufacturing, supply, processing, or installation of engineered stone benchtops, panels, or slabs is prohibited. In other words, engineered stone is a prohibited product in Australia. See here for more information.

Duties of manufacturers and suppliers of crystalline silica substances

This WorkSafe guidance outlines the responsibilities of manufacturers, suppliers, and importing suppliers concerning crystalline silica substances.

Ensure that power tools are not used for cutting, grinding, or abrasive polishing of engineered stone unless equipped with on-tool water suppression or dust extraction devices, and ensure respiratory protection is worn.

Under HRCSW (High Risk Crystalline Silica Work), you must:

  1. Prepare a crystalline silica hazard control statement (hazard control statement) before commencing work.
  2. Ensure that the work is carried out in accordance with the hazard control statement.
  3. Provide employees and job applicants with detailed information, instruction, and training regarding exposure to crystalline silica dust and the associated control measures.

You can find more information about HRCSW duties here.

Action Plan for Health and Safety Reps

A strategy to prevent work related injury and illness must be aimed at modifying the workplace - controlling the hazard at source - rather than modifying, screening or excluding workers from the workplace.

As an OHS rep, you need to make your members aware of the risks of exposure to silica and ensure that the employer complies with their duties under the legislation to eliminate or reduce the risks.

  • Check that materials used for abrasive blasting DO NOT contain more than 1% silica.
  • Equipment used for cutting, grinding, etc. should be fitted with dust extraction devices.
  • Where dust extraction is not practical, wet methods should be utilised.
  • Unfortunately, for many jobs, some form of respiratory protection will be required. The type of respirator will depend on the amount of dust created by the process. Ensure the workers are thoroughly trained in the use and maintenance of respiratory protective devices. This training must be provided by an appropriately trained person before workers are required to use the PPE.
  • Where there is likely to be excessive dust, all other workers should be cleared from the area so as prevent any unnecessary exposure.
  • The removal of residual dust generated by the work process must be done in a manner that will not make the dust airborne
  • Work with your workmates and your union to implement the Engineered stone ban.

To assess whether your product contains crystalline silica or other chemical constituents like resins, consider engaging an accredited laboratory recognized by the National Association of Testing Authorities (NATA) or an equivalent laboratory participating in the International Laboratory Accreditation Cooperation (ILAC) Mutual Recognition Arrangement (MRA). They can conduct an analysis of your product to determine its composition.

It is important that there be monitoring of silica dust levels generated by the activity. The results can then be used to establish effective control methods in work practices and ensure that they remain effective. It is important that an approved workplace consultant who can also provide advice on workplace control strategies do monitoring. Contact your union for further advice.

More information on silica and its effects

The following activities create silica dust:

  • Brick cutting and chasing. 
  • Angle grinding on concrete or masonry.
  • Concrete cutting. Jack hammering, scabbling and chiselling of concrete.
  • Cleaning up of dust and debris created by the above activities.
  • Cutting and working with manufactured stone (eg Caesarstone)

Workers at risk include those involved in:

  • building, construction and demolition work
  • preparing kitchen/laundry benchtops (manufactured stone)
  • excavation work
  • abrasive blasting (but use of silica in abrasive blasting is now prohibited in Victoria - see below) 
  • mining, quarrying, crushing and tunnelling work
  • brick making and glass making 
  • road building 
  • stonework
  • foundry or casting work
  • explosives blasting work
  • art workers, including teachers and cleaners
  • jewellery workers (particularly in developing countries)

What are the health effects of exposure to silica dust?

The following diseases are caused by excessive exposure to airborne silica dust:

  • Silicosis
  • Mesothelioma 
  • Acute silicosis (rapid development after short exposure to high concentrations of silica dust). 
  • Silicotuberculosis (silicosis sufferers are at a higher risk of developing tuberculosis)
  • Lung cancer

Silica dust, along with other atmospheric contaminates, can also cause or exacerbate these diseases:

  • Simple chronic bronchitis;
  • Chronic airway obstruction;
  • kidney disease;
  • Lung cancer.

Autoimmune diseases:

Recently lawyers have successfully drawn a connection to silica exposure and a number of autoimmune conditions including lupus, scleroderma and rheumatoid arthritis. In March 2021, WorkSafe Victoria insurers accepted a compensation claim for an employee who was diagnosed with lupus after being exposed to toxic silica dust. Read more and listen to ABC radio here)

It is crucial for individuals working with crystalline silica to undergo a respiratory health assessment, you can find more information 

What is silicosis?

Silicosis is a serious disease of the lungs caused by breathing in crystalline silica dust. Crystalline silica is a basic component of soil, sand, granite, and many other minerals (a common type is quartz). It can become respirable dust when workers chip, cut, drill, or grind objects that contain crystalline silica. In addition, the practice of using sand and other materials containing silica for abrasive blasting led to the creation of high levels of crystalline silica dust.

Silicosis can be disabling or even fatal. There are three types of silicosis:

  1. Chronic/classic silicosis - this is the most common form and occurs after 15-20 years of moderate to low exposures to respirable crystalline silica.
  2. Accelerated silicosis - which can occur after 5-10 years of high exposure.
  3. Acute silicosis - which can occur after a few months or as long as 2 years after exposure to extremely high levels of crystalline silica.

To learn more about the terrible effects of the disease, see this short film from China: Dying to breathe, about workers who contract silicosis after working in gold mines.

Crystalline silica also causes cancer of the lungs.

The VTHC OHS Unit has a webinar on Silica broadcast in August 2018 and available here on our Facebook page: you should check out - and then complete the quiz.

October, 2017 Cancer Council targets Silica Dust
Cancer Council Australia called for tradies to be more aware of cancer risks on the job in the light of new estimates that over 230 lung cancer cases in Australia each year are caused by exposure to silica dust in the workplace. About 600,000 Australian workers are exposed to silica dust at work each year, including miners, construction workers, farmers, engineers, bricklayers and road construction workers, as well as those working in demolition.

Terry Slevin, Chair, Occupational and Environmental Cancer Risk Committee Cancer Council Australia, said "Silica is surprisingly common – it's found in stone, rock, sand, gravel and clay, as well as bricks, tiles, concrete and some plastic materials. When these materials are worked on or cut, silica is released as a fine dust that's 100 times smaller than a grain of sand. It's so small you can't see it – but if you breathe it in, in some cases it can lead to lung cancer."

Mr Slevin said that it was the responsibility of both employers and employees to act now to reduce the number of silica related lung cancer cases. "Employers have a legal responsibility to provide a safe place to work. Likewise, those working with silica need to take responsibility for their future health, get informed and protect themselves."
Read more:  webpage with downloadable pdf document.

Live Show

The OHS team at Victoria Trades Hall Council recently produced a webinar with industry experts on silica, where it's found, the damage it can cause and the protective actions that can be taken.

 

 

Quiz

To help test your knowledge on silica, we developed a short quiz. Go for 5/5.

See also