Toxic truth: Concerns raised by CSIRO in 1992

Macquarie University researcher Anthony Morrison preparing black slag leachate samples for chemical analysis in the laboratory.
Macquarie University researcher Anthony Morrison preparing black slag leachate samples for chemical analysis in the laboratory.

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PASMINCO knew as far back as 1992 that black slag was leaching into the environment and could be absorbed by humans, but it kept the information secret, documents obtained by the Newcastle Herald reveal.

A June 1992 CSIRO report prepared for Pasminco says  “most of the heavy metals present in the slag are in readily bioavailable forms’’.

‘‘It is likely that ingested slag reaching the gut would readily release lead, zinc, cadmium and copper, and this could have toxic consequences,’’ the report says.

The CSIRO tested slag and found heavy metals ‘‘well above the values considered high and requiring possible remediation’’.

‘‘Disposal of this by landfill would therefore require the permission of the NSW EPA [Environment Protection Authority],’’ its report says.

Pasminco gave away slag for free for decades, with much of it used in public parks, foreshores, playgrounds and sporting fields, as well as in people’s yards for landscaping.

Macquarie University researcher Anthony Morrison said Pasminco had failed to make the CSIRO report public.

‘‘As a result of this, slag continued to be distributed and utilised in the community,’’ Mr Morrison said.

Mr Morrison’s research showed that slag was given away until about the year 2000.

A Newcastle Herald investigation recently found high levels of lead in exposed slag at a Speers Point playground and sportsfield and on the Eleebana shore, where children wade.

The 1992 CSIRO report found slag could leach into the environment and be absorbed into the body.

Despite this, a Pasminco community newsletter – cited in a July 1992 council report,  said: ‘‘The lead is bound up in a glass-like structure and does not readily leach out.’’

The EPA recently told the Herald that slag was ‘‘bound up in a glassy matrix’’.

Mr Morrison said he could not believe this comment.

‘‘Are you kidding that they’re still going on with that?’’ Mr Morrison said.

‘‘That is complete rubbish and they know it because they’ve been to a whole lot of the talks I’ve given at various stages.’’

The EPA did concede that slag could leach, but said lead dust posed a greater risk.

Mr Morrison has researched slag for almost 15 years and reached the same conclusions as the CSIRO report, which Pasminco buried. That is, he found heavy metals in the slag – including lead – could leach into the environment and be absorbed into the body, exposing people to health problems.

Exposure to lead can cause sickness, brain damage, behavioural problems and retardation in children.

‘‘If the slag is exposed at the surface and handled by children, for example, we have previously shown that the heavy metals in the finest particles are highly bioavailable,’’ he said.

Lake Macquarie City Council used slag for decades as fill in parks and other public areas.

It did not stop using it until August 1994, citing concerns that heavy metals could leach into surrounding soil.

When the council announced it was going to stop using slag, Pasminco management defended the waste product and described council’s decision as an ‘‘overreaction’’.

A senior Pasminco manager had argued she did not see any need to examine further restrictions on the production or use of slag.

The smelter produced about 80,000 tonnes of slag each year,  with most of it   used on site after it was mixed with dried sewage sludge and coke fines to produce artificial soil.

‘‘We have had worthwhile discussions with council officers and I think it is a pity that the councillors themselves, if they had concerns, didn’t approach us about them,’’ the Pasminco manager said at the time.

In more recent times, the council had insisted it was ‘‘unaware of any research or data on the human or environmental health impacts of Pasminco slag’’ until 2003. 

However, documents show the council engaged private consultants to test slag samples in 1992.

A council report on this matter in July 1992 said ‘‘there would appear to be a likely risk, if young children were permitted to play regularly in the slag’’.

A council document from 2012, obtained by the Herald under freedom of information laws, revealed the council referred the black slag problem to the EPA in 1994. 

A decade went by, but the problem remained in the council’s hands.

From 2004 to 2010, the council ‘‘advocated for the black slag legacy to be managed by the EPA’’, the document said.

The EPA has played down the slag problem as a low priority, despite scientists saying it poses a significant risk of harm.

However, the EPA did say it would reconsider how to deal with slag in an expert working group set up in response to the Herald’s Toxic Truth series.

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