Industrial emissions have blown across Mount Isa for decades. Mark P. Taylor, Author provided

Mount Isa contamination ‘within guidelines’ but residents told to clean their homes

After an 11-year wait, Mount Isa Mines has released the official report into the lead contamination that has blighted the city for decades.

The report, commissioned by the mine’s owner, Glencore, and produced by researchers at the University of Queensland, says that household dust contaminated by airborne lead from the mining and smelting operations is the dominant source of the city’s exposure.

In some aspects this marks an important shift in the industry’s acceptance of the problem. Yet the report goes on to argue that Mount Isa residents are nevertheless responsible for keeping themselves, their houses and their children free from dust, thus putting the onus back on them to avoid exposure to the contamination.

A history of excuses

This is the latest iteration in the decade-long evolution of Mount Isa Mines’ arguments rebutting research that linked the contamination to its mining and smelting operations.

Back in 2007, when owned by Xstrata, Mount Isa Mines stated that the contamination was “naturally occurring”. We have previously termed this the “miner’s myth” – the idea that contamination surrounding a mine is a product of natural geology and weathering rather than the mining activity itself.

Before Mount Isa Mines was taken over by Glencore in 2013, the company admitted that Mount Isa was affected by “industrial mineralisation” (industry-speak for contamination from emissions), but also said that the contamination was partly due to natural sources in the city’s soils and rocks.

We and our colleagues have produced more than 20 studies documenting environmental contamination and its management in the Mount Isa region, dating back to 2005 when the Leichhardt River, which supplies drinking water to Mount Isa, was found to be contaminated with lead and other metals. Since then, we have detailed contamination in local sediments, water and soils, and used isotope fingerprinting to pinpoint the likely source; none of this research was mentioned in the new report.

Despite the welcome admission that the company is indeed contaminating Mount Isa, the report caveats this by saying that the risk of direct inhalation of lead emitted into the air is low. It states that exposure arises mainly when children are exposed to lead-contaminated surfaces in their homes – chiefly carpets. For Mount Isa families, these comments do not fully encapsulate the real challenges they face in protecting themselves and their families.

Passing the buck

The report offers the following advice to residents attempting to keep their exposure as low as possible:

  • keep a “clean home environment”

  • consider replacing carpets with timber or other hard floors, and clean them with phosphate-based agents

  • wash childrens’ hands frequently and before meals, and encourage very young children not to suck non-food items

  • wash all homegrown fruit and vegetables, and peel root vegetables, before cooking and/or eating.

The implied argument is essentially that, despite the contamination, if you do the right thing (such as keeping your house clean) there is no problem.

The obvious rebuttal to this is that if there were no industrial lead in the community, there would be no problem at all. The root cause of the issue is not the natural hand-to-mouth behaviours of children but the pervasive, persistent and permanent arsenic, cadmium and lead contamination that penetrates everything they touch: clothes, toys, food, floors and furnishings.

The rates of lead dust deposition are such that that people living closest to the smelters would have to wash their backyards and indoor surfaces several times a day to keep toxic dust levels within acceptable guidelines. Cleaning one’s house more than once a day, especially if working or looking after little children, is nearly impossible to maintain even over a few days, never mind a lifetime. While the advice to keep houses, hands and surfaces is not unreasonable in itself, the evidence suggests that it is little use in preventing lead exposure.

How serious is the exposure?

Mount Isa’s schoolchildren are performing well below the national average, according to standardised testing data from the first full year of school. Similar outcomes have been seen in Broken Hill, another of Australia’s major lead mining towns. Children in North Mount Isa, the area nearest the smelter, did worse than in other areas of the city.

Educational testing outcomes in children from various areas of Mount Isa, compared with the national average. Author provided

Mount Isa’s children have an average blood lead level of about 35 parts per billion – about three times higher than normal. A 2015 study of children from Broken Hill and Port Pirie showed that a increase in blood lead from 10 to 100 parts per billion can reduce IQ by 13.5 points. Relevantly, low exposures cause proportionally more harm, which is why it is important for children to be protected from any lead contamination at all.

The report is clear that exposure happens as a result of contamination released into the air, which later settles as dust:

The major source of lead exposure is via ingestion in the community and is from air particulates (<250µm diameter) that are on the ground from deposition as fallout.

However, it goes on to say that the mine cannot be directly faulted for this, because the average rate of airborne emissions is within the guidelines outlined in its environmental permit. The report suggests that its modelled blood lead values do not match the actual values on children because they may be exposing themselves to extra lead by ingesting dirt, or through other sources such as lead-based paint, leaded petrol, or lead-acid batteries.

But this rationale fails to take into account the short-term spikes in emissions, which cause depositions that accumulate in soils and dusts, which in turn cause elevated blood lead exposures in children. The question could easily be answered by comparing the isotopic composition of lead from blood samples with that from the mine’s emissions. Disappointingly, the Glencore report did not undertake this critical analytical step to link environmental sources to actual exposures in children.

Another setback

Authorities have been aware of lead emissions from the Mount Isa smelter since the early 1930s. It was always a fanciful notion to suggest that emissions were not finding their way across the city and into homes, and that the contamination was somehow natural.

Intensive air monitoring in the community has continued for at least the past 40 years. Blood lead surveys and internal memos, along with environmental assessments from various government agencies, have provided significant prior knowledge of the nature, extent and cause of the problem. In 2010, Queensland’s chief medical officer Jeanette Young told The Australian newspaper:

I do know the cause; it is emissions being released from the mine. If you think where it is coming from, it is coming from emissions from the smelter that are going up in the air and they are depositing across the town fairly evenly.

Thus, in this sense, the latest study merely represents confirmation of what many people already knew.

Yet despite this overdue acknowledgement of the problem, the report implies that Glencore is not taking full ownership of the issue. The overriding message to Mount Isa’s residents is that it falls to them to keep themselves free from dangerous contamination.

In this sense, this is yet another setback in improving the living conditions for the community of Mount Isa, particularly young children who are the most vulnerable to the adverse and life-long effects of lead exposure.

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