The federal government has dramatically lowered the safe exposure levels of toxic firefighting chemicals, following months of controversy over contaminations detected near airports and military bases.

The new tolerable daily intake levels (TDIs) of the polyfluoroalkyl substances (PFAS) chemicals – used in firefighting foam for decades until the early 2000s but now known to be toxic – are now in line with US standards, but authorities have warned the long-term effects of exposure remain unknown.

PFAS contamination has been detected up to 300 times the safe levels near multiple Australian airports and a dozen Royal Australian Air Force bases including Townsville and Oakey in Queensland, Williamtown in New South Wales, Darwin and Katherine in the Northern Territory, and Perth.

Monday’s announcement altered the maximum TDI of perfluorooctane sulfonate (PFOS) from 150 nanograms per kilogram of body weight per day to 20 nanograms. The maximum TDI of perfluorooctanoic acid (PFOA) was revised to 160 nanograms.

The guideline for maximum TDI of PFOS in drinking water has been reduced by 7.5 times from 0.5 micrograms to 0.07 micrograms per litre, and from 5 micrograms to 0.56 for PFOA.

The new tolerable levels, recommended by Food Standards Australia New Zealand, changed interim guidelines which had been in place since June. At the time there was concern the levels had been set in line with Europe rather than the 78 times lower limits set by the US just one month prior.



The federal Department of Health said the previous levels were not wrong, and that both sets of TDIs were protective of public health. The old TDIs were always intended to be replaced and were appropriate as an interim measure, it said.

Authorities stressed the guidelines were precautionary measures while research continued, because there was no consistent evidence about the long-term effects of low-level accumulation in humans.

Most investigation into the effects of PFAS, particularly overseas, relates to exposure at high levels in places where the chemicals are produced.

Food Standards Australia New Zealand was contracted by the federal government as a consultant, and was also tasked to consider what regulatory options were available for food levels but was unable to justify any based on the lack of conclusive evidence and information.

“So it’s not a standard, and food can still be sold in the marketplace,” said the Northern Territory director of environmental health, Xavier Schobben.

Authorities and government have acknowledged that uncertainty around the contamination as well as the lack of science on the long-term effects was causing stress in affected communities.

More than 450 Oakey residents have reportedly launched a class action against the Department of Defence over the contamination, and another class action on behalf of Williamtown residents is before the federal court.

The Department of Health has funded programs including mental health, counselling services and voluntary blood testing in Williamtown and Oakey, where contamination has been the worst.

Natasha Fyles, the Northern Territory health minister, said her government was lobbying defence to provide similar support and services to Katherine residents, the worst-affected area in the NT.

Working with defence on the contamination issue had been an “ongoing issue”, she said, but was “cooperative”.

“We remind defence that they need to certainly be at the table on this issue in terms of providing information and resources to our community. I’m confident defence acknowledge their role to play,” she said.

In the Northern Territory the worst contamination has been in Katherine between the RAAF base and the edge of town, where more than 40 properties which rely solely on bore water have been supplied with bottled drinking water by defence.

Authorities said outside of those areas, the water in Katherine – which relies on river water or a mix of river and bore water – was safe to drink.

The concern for the main town was isolated to a short period of time following the end of the dry season. At that time the new rains flush the river and can bring uncontrollable levels of bacteria, forcing the town on to 100% bore water.

No details of contingency plans in the event of Katherine residents being told not to drink the water were provided, but decisions would be made on the basis of further testing and consultation, members of the joint agency taskforce said on Monday.

Last week the federal Labor opposition criticised the government for inadequate national coordination on responding to the crisis.

An Environment Protection Authority summit is under way in Melbourne to develop a national PFAS management plan.

The Department of Defence has been contacted for comment.