Scientists are taking a deep look at the potential occupational and public health risk of a volcanic mineral found below Auckland and other places. Photo / Alex Burton
Scientists are taking a deep look at the potential occupational and public health risk of a volcanic mineral found below Auckland and other places. Photo / Alex Burton
Auckland scientists have launched a multi-million dollar study to gauge the potential public health threat of a mineral linked with cancer and lung diseases more commonly caused by asbestos.
A four-year project, just funded by the Ministry of Business, Innovation and Employment (MBIE), comes amid growing concern over erionite, which originates in silica-rich volcanic rock found throughout the Auckland region.
Once disturbed through activities like construction, dust containing erionite can become airborne.
If inhaled, it can potentially cause malignant mesothelioma - a disease more usually associated with exposure to asbestos.
Former Prime Minister's chief science adviser Sir Peter Gluckman reported in 2015 that erionite was also a more potent carcinogen than asbestos.
"At a global scale, erionite-induced mesothelioma is thought to be particularly prevalent in the construction and quarrying industries, or where erionite containing rock has been inadvertently used to build houses," explained project co-leader Associate Professor Jennifer Salmond, of the University's School of Environment.
"However, studies overseas have also linked population exposure to the transport of airborne dust and particulates containing erionite fibres from gravel pits, quarries, unsealed roads, building and construction sites, and recreational, agricultural or nature conservation practices which disturb soil containing fibres."
But it was still difficult to quantify the precise health risks erionite posed.
That was because it was hard to know how much a person had been exposed to in the environment - and because there was a lag time reported of between 20 to 60 years between exposure and health impact.
"This lag time makes it very difficult to link cause and effect and to do epidemiological studies relating incidence of malignant mesothelioma to exposure and place of residence, as populations are mobile," Salmond said.
"This is also an international emerging environmental risk, and although people are working on it, safe occupational and public health exposure limits have not yet to be determined anywhere."
New Zealand's rate of malignant mesothelioma, meanwhile, is high by international standards - but no one knows exactly why.
The new project, which Salmond is leading with colleague Associate Professor Martin Brook, aimed to answer three crucial questions: where erionite is found in New Zealand, how much of it there is, and what the likely degree of exposure is for construction workers and the public.
That would initially involve working with industry to find out where exactly it's found in the bedrock and how it can find its way into soil.
Along with building a 3D model of its distribution around the country, Salmond and Brook also aim to develop a "diagnostic toolkit" and air sensors to quickly identify its presence.
"As we move through the four-year period, we will use the low-cost instruments to develop a monitoring network targeted at the most at-risk sites, but also including other areas to establish background concentrations," Salmond said.
"We will also develop a model to provide an estimate of potential population exposure to erionite."
Once disturbed through activities like construction, dust containing erionite (pictured) can become airborne. Photo / Wikimedia Commons
Another part of the work was looking at how the threat might be mitigated, with new plans or strategies designed with industry partners to protect occupational and public health.
Salmond said the programme would prove particularly challenging because her team were working at the cutting edge of current scientific understanding of this emerging risk.
"Our understanding of the key processes and exposure pathways, measurement technologies available, best practice guidelines and potential occupational and public health exposure risks is changing very rapidly," she said.
"We will have to adapt our understanding and methods at the same rate – which requires us to be continually reviewing our practices.
"Currently we can also only make an educated guess about how much erionite is out there, so until we get sampling we don't really know what we are up against."
The programme, awarded $7.6m through MBIE's Endeavour Fund, comes after Salmond, Brook and others recently called for an investigation into in erionite in the New Zealand Medical Journal.
"Two million tonnes of rock was removed for City Rail Link project and potentially at least some of that rock could contain erionite," Brook said at the time.
"But currently there are no international or New Zealand occupational exposure limits or standard low-cost field sampling and analytical methods for erionite."
