Leigh Dayton, Science writer

March 20, 2007

THE Mount Isa Mines company has refused to release in-house research about heavy metal contamination in the central Queensland community.

The data would fill in gaps in surveys conducted by a team of Australian and British scientists who found lead levels in residential areas of Mt Isa were up to 33 times higher than limits set by federal guidelines.

"We've asked them for the reports, but nothing is forthcoming," said Mark Taylor, an environmental scientist with Macquarie University, Sydney.

"The data would help health authorities make appropriate decisions about follow-up risk assessment on a property-by-property or area-by-area basis," Dr Taylor said.

The group sampled soil in and around Mt Isa. The most contaminated neighbourhood had levels up to 9780 parts per million of lead, 12,110ppm of copper and 11,120ppm of zinc.

Health investigations by the National Environmental Protection Council are triggered at 300ppm of lead, 1000ppm of copper and 7000ppm of zinc.

According to the Queensland Environmental Protection Agency, the mine, owned by Swiss group Xstrata, conducted soil tests in 1990. "Significant hot spots were cleaned up," a spokesperson said.

While the 1990 findings were published by the Queensland Chemical Laboratory and Division of Environmental and Occupational Health, results of sampling done in 2000 have not been released.

"We're not going to do that," a spokesperson for Mt Isa Mines said when The Australian asked for the research. No explanation was provided.

The EPA, however, said it was taking the matter seriously.

"The EPA is now in the process of reviewing and mapping the data. The agency will also compare it to historical soil sample results, areas previously cleaned up and geological maps of naturally high mineralisation areas," said the spokesperson.

Last night Dr Taylor rejected Xstrata's claim that his group's findings were "within limits" set by national guidelines.

"The facts are what they are," he said, noting that the sample analysis was conducted at two independent British laboratories in London.