Exposure Standard for Silica Dust Halved

By on January 28, 2020

Respirable dust particles are small enough (0.2 – 7 Microns) to penetrate past the upper respiratory tract and deep into the lungs.

Potential health effects associated with exposure to respirable quartz dust, known as Respirable Crystalline Silica Dust (RCSD) are inclusive of but not limited to eye, skin and respiratory system irritation, dermatitis, bronchitis, scleroderma and silicosis.

Silicosis is a lung disease typically caused by inhaling excessive amounts of fine particles of RCSD over a long period of time. The RCSD causes scarring of the lower lung i.e. the alveoli.

This permanently reduces a person’s ability to inhale oxygen and exhale carbon dioxide, leading to breathing impairment and a loss of fitness. If untreated this may lead to significant illness that is potentially fatal.

  • Chronic silicosis may take 15 or more years of low to moderate exposure to develop.
  • Accelerated silicosis appears after 5-10 years of intense exposure.
  • Acute silicosis develops within 6 months to 2 years of intense exposure.

Silicosis is not a new industrial disease.

According to Wikipedia the name silicosis comes from the Latin term silex, or flint. The recognition of respiratory problems from breathing in dust dates to ancient Greeks and Roman mining. In 1713 it was noted that asthmatic symptoms and sand-like substances were found in the lungs of stone cutters.

With industrialization came increased production of dust. The pneumatic hammer drill was introduced in 1897 and sandblasting was introduced in about 1904, both significantly contributing to the increased prevalence of silicosis.

Below is a table of data received from Safe Work Australia which demonstrates that the number of claims has shown an apparent decrease for silicosis over ~20 years (note across all industries).

However, the figure for 2016-17 is expected to rise steeply once the data for the manufactured stone bench cutting industry has been collated by Safe Work Australia.

All accepted workers’ compensation claims1 for Silicosis in Australia between 2000-01 and 2016-17

Explanatory notes:

The number of claims shown in the previous table have been rounded to the nearest 5 to maintain confidentiality, therefore the sum of claims may not equal the total.

p Data for 2016-17 is preliminary and subject to change when new data is available.
1 All accepted workers’ compensation claims excluding journey claims.
n.p. Data suppressed due to confidentiality restrictions.

Source: Safe Work Australia’s National Data-Set for Compensation based Statistics

Outbreak of Silicosis

An outbreak of silicosis has sadly once again occurred, initially overseas and more recently in Australia. The outbreak aligns with the current international and local boom of imported manufactured stone, being used mostly for bench tops and other surfaces utilised in kitchens, laundries and bathrooms, in both the domestic and commercial construction industry.

Workers in these industries, known as stone masons, have been in some cases exposed to extreme levels of RCSD and other chemicals utilised to artificially manufacture stone.

It appears that these stone masons have incurred either accelerated silicosis or acute silicosis, which in basic terms means intense or excessive exposure.

WorkSafe Victoria has recently undertaken an industry wide audit of bench top manufacturers and found relatively high levels of non-compliance with 340 improvement notices issues from October 2018 to September 2019.

Key areas of non-compliance identified were:

  • Dry cutting / polishing of engineered stone – visible airborne dust
  • Poor housekeeping – dust on floor and surfaces
  • Use of compressed air for cleaning
  • Inadequate recycle water system in place
  • No respirator training / maintenance
  • Dry grinding – off-site installation
  • No health surveillance program in place

The Medical Journal of Australia published an article in 2019 by Johnson and five colleagues from Sydney hospitals on a serious silicosis case from workplace dust exposure.

The article said, “new outbreaks of silicosis have recently been reported, with life-threatening silicosis occurring after exposure to a relatively new type of engineered stone product used for kitchen and bathroom benchtops”.

“In almost all reported cases, there was little adherence to basic protection measures, such as provision of appropriate ventilation systems and use of personal protective equipment,” the article said.

“Our case reaffirms the need for vigorous enforcement of dust reduction regulations, particularly in the growing industry of engineered stone products”. Source – www.TheStuff.CO.NZ

A written and oral submission was made by CMPA to the Senate Community Affairs References Committee “Workplace Exposure to Toxic Dust” 29th September 2005. The CMPA submission highlighted the need for consistent and systematic enforcement of Workplace Exposure Standards (WES) for Respirable Crystalline Silica (RCS). This was supported by submissions from other organisations. A recommendation from the Senate
Committee was as follows:

“Recommendation 7 5.87 That the Minister for Employment and Workplace Relations raise with the Workplace Relations Ministers Council the need to ensure enforcement of hazardous substance regulation and the need to enact nationally consistent standards in a timelier manner.”

Tragically for stone masons working in the manufactured stone industry it would appear this recommended enforcement of hazardous substances regulations never occurred until the horse had bolted, i.e. the out break of silicosis.

Unfortunately for the extractive industry we are now faced with even more costly and stringent burdensome challenges.

New Workplace Exposure Standard

On the 16th of December 2019 WorkSafe Victoria adopted a workplace exposure standard of 0.05mg/m3, reduced form 0.1 mg/m3, the standard that was adopted in 2005 (before this date it was 0.2 mg/m3).

However, the Government is urging employers to take a precautionary approach and only expose their workers to levels below 0.02mg/m3, to protect them from developing silicosis or lung cancer.

It is reasonable to assume that this recent reduction would not have occurred if the manufactured stone industry had been effectively regulated, which it was clearly not.

Quarry operators shall have to demonstrate that they are controlling the risks associated with RCSD as far as is reasonably practicable in alignment with the hierarchy of controls, e.g. prove they have identified, assessed and adopted where reasonably practicable, higher order controls such as elimination, substitution, isolation and engineering prior to relying on PPE to ensure workers are not exposed to levels of RCSD equal to or greater than 0.05 mg/m3.

What is reasonably practicable?

Section 20(2) of the Act provides that regard must be had to the following matters in determining what is (or was at a particular time) reasonably practicable in relation to ensuring health and safety:

(a) The likelihood of the hazard or risk concerned eventuating;

(b) The degree of harm that would result if the hazard or risk eventuated;

(c) What the person concerned knows, or ought reasonably to know, about the hazard or risk and any ways of eliminating or reducing the hazard or risk;

(d) The availability and suitability of ways to eliminate or reduce the hazard or risk;

(e) The cost of eliminating or reducing the hazard or risk.

Most quarry operators have informally adopted the hierarchy of controls in their approach to dust management.

Hierarchy of Controls

Obviously, we cannot eliminate, or substitute quartz based rock sources that produce RCSD, but considerable effort has been undertaken throughout the extractive industry using isolation and engineering controls to reduce dust generation or carriage.

The utilisation of administrative controls such as safe work procedures, dust management plans, audits and inspections, worker training and awareness and health surveillance are necessary and beneficial.

Worker knowledge, e.g. training is an essential administrative control, without such, other controls are easily discounted or devalued.

PPE will always be a vital control. Even in an extremely well managed quarry, maintenance workers and workers inspecting operating plant will potentially be exposed to levels of RCSD up to and over the new exposure standard.

In summary and in practical terms, a range of controls selected from the Hierarchy of Controls inclusive of PPE will always be necessary to ensure worker exposure is reduced as far as is reasonably practicable.

The issue of concern is proving what is reasonably practicable, as the definition is subjective and open to interpretation and the process can be extremely costly.

Moving Forwards

The CMPA’s Dust Management Guideline 2016 is currently being updated, however, it is still an excellent resource to support members in controlling the risks associated with RCSD in the interim. Attachment E – Dust Control Self-Assessment Checklist is a good starting point to identify the requirements of your Dust Control Plan.

Written by David McKelvie, Director of Safe Mix, a WHS consultancy specialising in the Construction Materials Industry.

Safe Mix can assist members in controlling the risks associated with RCSD.

Safe Mix offers worker/management training, dust control plans, the coordination and assessment of dust monitoring and general advice.

If you require support, you can contact David on 0407 022 117 or email david@safemix.com.au

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