Silicosis: more science needed

A new study of silica exposure and silicosis is attempting to evaluate the risk of lung disease in mining. Story by Daniel Hall

The Queensland Government Department of Mines and Energy (DME) and the University of Western Sydney have embarked on a joint investigation into the effects of silica dust on miners.

The joint research project could lead to improvements in the lung health of miners in the State, according to Mines and Energy Minister Geoff Wilson.

To learn more about the study and Silicosis, Australian Mining editor Daniel Hall spoke with University of Western Sydney senior lecturer Dr Sue Reed.

Q. How has the understanding of dust related disease changed over the last five years?

The Australian Government released a report from the 2006 Senate enquiry into toxic dust, which highlights that we do not have enough scientific data on silicosis.

We still do not fully understand how silica dust can affect health.

One of the findings to come out of the 2006 Senate enquiry is that although silica is known to cause silicosis, we do not have a good understanding of the size of the problem.

What is known is that the silica particles that pose the greatest risk are in the respirable range.

What is not known is the specific size fraction, within this range, that poses the greatest risk.

It is suggested that the particles that pose the greatest risk are extremely fine, 2.5 µm or even less than 1 µm.

Internationally there is some concern that current exposure standards, which appear to be protecting mine workers, may not provide sufficient protection, and more data is needed to confirm what safe levels of exposure.

Current Australian exposure standards can only provide protection if research is able to support that the exposure standard is being set where the level of risk is acceptable.

Q. Are current Australian standards suitable for protecting mine workers?

While it is hard to be forward looking with a lot of research left to be done, some preliminary research shows that some people in the resources industry are not meeting the current standard, while some are well within the standard.

It is interesting that most mine workers appear to have a poor understanding about what is a dusty environment and what is not.

The particles that we should be worried about are not the particles that we can see, it is the ones we can’t see that pose a greater risk for lung disease.

Often a mine may be dirty or dusty, and workers think that the airborne dust is hazardous. However, monitoring some dusty environments may result in relatively low levels of respirable dust and, therefore, low levels of respirable Silica, as the particles that can be seen are larger, and can be removed by cilia (small hairs) in the upper airways and removed through the nose.

Q. Why has the DME become involved?

This project was identified the Queensland DME as an area of concern.

The DME contacted University of Western Sydney about combining to conduct an extensive study looking at exposure to airborne respirable silica and the potential impacts on respiratory health and other important factors.

The study also looks at which control measures mines with low silica levels have in place.

The researchers can then go back to the industry and let them know what controls result in lower exposure levels, which will then make the mines safer.

Q. How does Silica affect the health of mine workers?

Silica affects mine workers in that this hazard has the potential to cause chronic respiratory disease – silicosis, which is progressive and difficult to diagnose in the early stages of the disease.

Silicosis has been around for many years now, but the industry does not know if the current levels of exposure to respirable crystalline silica are enough to minimise the risk of silicosis completely.

Research by the DME and the University of Western Sydney aims to find out what the levels are, and relate that back to controls and respiratory health.

Q. What is the best way for workers to protect themselves?

Mine workers that are working in air conditioned cabs should work with the windows closed instead of having them open, and they should make sure that the filters in their air conditioning systems are kept clean.

If mine workers are also working in suspected hazardous environments, they should be using respiratory protection that complies with the appropriate Australian standards.

The standards depend on the area of the mine that the worker is operating in.

In all of the mine sites that I visited recently the Personal Protective Equipment (PPE) complied with the appropriate Australian Standards, however, I do know that that there is a lot of PPE for sale in Australia that does not meet the appropriate standards.

Mine managers should be reducing dust exposures as low as reasonably practicable. This means that they make sure that they use all of the controls that are available to them, for example, using air conditioned cabs, wetting processes and other dust control methods.

The DME has developed a health improvement and awareness committee with various industry partners in an attempt to educate the professionals in these industries about the sort of controls that they should have in place.

The controls that mines should have in place vary from site to site.

It is very hard to standardise the type of control needed because it depends upon the type of mine and the mining equipment being used, for instance, a smaller mine might be using some equipment that is now considered outdated, and they may need to replace it.

Q. When is the study due for release?

This comprehensive study is in the early stages and is due for completion in the next three to four years.

The study will test small mines and quarries in Queensland, as well as exploration sites.

The project will deliver the information about the amount of Silica exposure that they are facing in their work environment.

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