There is a growing global momentum towards establishing more stringent diesel engine exhaust (DEE) monitoring standards in an attempt to minimise the risk of serious illnesses among underground miners in particular.
Elemental carbon is still the surrogate referred to internationally as the benchmark for determining the quality of the atmospheres breathed by mineworkers polluted by DEE fumes. Whilst there is no universal standard, the current guideline in WA is based on maintaining EC levels below an 8 hour TWA value of 0.1 mg/m3.
The recent NHMRC sponsored research project in WA (Peters S, et al, 2017) examined the then Department of Mines and Petroleum’s CONTAM data from 2003 -2015 and medical reports and thereafter modelled the average levels of sub-micron elemental carbon (EC) exposure for a range of occupations at WA mine sites. They then estimated the number of certified lung cancer deaths caused by those levels with stark results.
For example the researchers found that if underground miners were exposed at work over a period of 45 years to 0.044 mg/m3 of EC they would have 38 extra lung cancers per 1000 workers compared to that of the general population. Bear in mind the normally accepted risk of such occupational disease is one in 1000 workers.
Not surprisingly, therefore, the researchers strongly recommended a reduction in the level quoted in DMIRS’ current guideline of TWA 8-hour limit of 0.1 mg/m3; a view shared by many others at various national jurisdictions.
Consequently, there has been a growing groundswell of opinion that urgent action is needed to better safeguard the health and welfare of underground miners, exposed on a regular basis to DEE fumes.
Recent International recommendations
Finnish Institute of Occupational Health (2015): EC 0.02 mg/m3
Ontario Occupational Cancer Research Centre (2018): EC 0.02mg/ m
Council of the European Union’s OEL limit (applicable from 2026): EC 0.05 mg/m3
In a recent letter from Paul Demers, Director, Occupational Cancer Research Centre (OCRC) to Ontario’s Hon. Minister of Labour dated, 4 May 2018, he stated:
- Based on evidence of increased lung cancer risk at very low DEE levels, OCRC recommends moving towards the limit of 20 micrograms/m3 EC for the mining industry and five micrograms/m3 for other workplaces.
- Other groups are recommending similar or even more protective limits such as the Dutch Expert Committee on Occupational Safety and Health Council recommending a health based OEL for DEE of no higher than background levels (approx.. 1 micrograms/m3).
In another recent article on “Diesel Engine Exhaust: Basis for Occupational Exposure Limit Value” published in Toxicological Sciences, June 2017, the authors state “when the pulmonary inflammation response seen in controlled human studies after one to two hours exposure at 0.1 mg DEP/m3 (approx. 0.O75 mg EC/m3) is taken into account the OEL should be well below this level.”
The international trajectory is very clear and it is undoubtedly time for WA’s DMIRS to follow suit by consulting with the WA mining industry regarding its intention to transition the current guideline downwards to a level of 0.05 mg EC/m3 over the next three to five years or so.
The other ‘elephant in the mine’
Underground miners in WA are allowed to smoke cigarettes whilst at work so that Environmental Tobacco Smoke (ETS) is added to DEE pollutants, all of which other mine workers inhale. ETS, similar to DEE fumes, is a complex mixture of over 4000 compounds, of which some 60 are known carcinogens.
It’s time to ask how does the “Smoke-Free Places Act” apply to smokers in WA’s underground metal mines. In addressing this question the default answer appears to be:
- If flow-through ventilation in the mine is efficiently diluting and removing diesel emissions to ensure safe breathable air, then any ETS generated should be diluted and removed along with diesel emissions.
However, we know, that in reality, these assumptions are false, since the current levels of recorded EC levels in WA mines vary, and can quite often be roughly equal to or, in excess of the guideline limit of 0.1 mg/m3, with the risk of ill-health to underground mine workers being far too high.
Add to this, the fact that the OSH Act (Section 19(1)) requires employers to, so far as is practicable, provide and maintain a working environment in which employees are not exposed to hazards, and since ETS is a known health hazard, it falls on the employer to reduce this risk at the workplaces so far as is practicable. That apart there is a duty of care on all employees to avoid doing anything that places work colleagues at unnecessary risk to their health or safety.
Consequently, knowing that ETS may cause increased risk of lung cancer, heart disease and stroke etc., every effort should be made to discourage smoking in all WA’s underground mines. Surely this issue is important enough to warrant a major educational program aided by, possibly, monetary and/or other incentives to eliminate this antisocial and unhealthy habit from underground mines.
Safe Work Australia – Workplace exposure standards review
The aim of this review is to develop a list of health-based recommendations for workplace exposure standards (WES) in Australia. The evaluations of individual chemicals that commenced in 2018 will continue throughout 2019 and 2020 and includes a peer review process.
The values published in the WES list are the airborne concentrations of a chemical that are not expected to cause adverse effects on the health of an exposed worker.
Primary Trusted sources include:
- American Conference of Governmental Industrial Hygienists (ACIGH)
- EU Scientific Committee on Occupational Exposure Limits (SCOEL)
- Health Council of the Netherlands
Secondary sources of data include:
- UK Health and Safety Executive
- Australian Institute of Occupational Health (AIOH)
Conclusions
The global groundswell of opinion amongst health scientists, researchers and occupational health and safety agencies for more stringent control of DEE pollutants, and air pollution in general, is becoming more vocal and strident. Indeed, recent recommendations to governmental agencies in Finland, Canada and the European Union strengthens the case for similar action in Australia.
Western Australia has been taking the lead in this matter as evidenced by the findings of the recent NHMRC sponsored research project, indicating the unacceptable risk of exposure to DEE fumes to the health of mine workers in general, and underground mine workers in particular.
Hopefully, we can continue to show leadership by adopting a strategy to reduce the current DMIRS Guideline to a more acceptable level. In doing so we would at least be “walking the talk” that the health and safety of mine workers is always our first priority.
References
Peters S, et al, ”Estimation of quantitative levels of diesel exhaust exposure and health impact in the contemporary Australian mining industry”. Environmental Medicine 74. April 2017.
Ontario Occupational Cancer Research Centre’s – Open letter to the Hon. Minster of Labour on “Proposed Changes Affecting the Protection of Workers”. 4 May, 2018.
Taxell P, and Santonen T, “Diesel Engine Exhaust: Basis for Occupational Exposure Limit Value”. Toxicological Sciences, Volume 158, August 2017.