Mining, People and the Environment > Enviromine > Xstrata lead study shows limited human risk

Enviromine

Xstrata plc’s Mount Isa lead and zinc mine in Queensland Australia has been one of the most public examples of the potential hazards of contamination in recent years.

Last year Australian and mining newspapers were full of reports that one in ten children in Mount Isa had unhealthy levels of lead in their blood, and a legal case was brought against Mount Isa.

Concern that the lead contamination originated from the mine was further fuelled by an independent report by a US toxicologist who asserted that the mine, and not natural background lead, was the main source of contamination in the town.

But Xstrata is also in the process of preparing an independent study to assess and reclaim historical and modern contamination from the mine.

The Lead Pathways study, lead by Barry Noller from the Centre for Mined Land Rehabilitation (CMLR) at the University of Queensland, began in 2006.

The first phase of the study, concerning land contamination, was released in July this year and found that although there was some ecological toxicity risk, the risk to human health was minimal.

“Our investigations have confirmed that the risk to human health from historical mine sediments within the Leichhardt River area is low,” Prof Noller said.

Of 16 sites tested only four exceeded the health investigation limit prescribed by the National Environmental Protection Council, the CMLR team said.

The study said that these samples indicated that over a sustained period of time, continued exposure to levels exceeding the guidelines could cause chronic lead toxicity in children, but argued that the samples were from recreational areas where prolonged direct exposure would be limited.