Senator McCarthy's comments come after the Australian National University (ANU) released the findings of its PFAS Health study which has been taking place since 2016.

The study found there was "clear evidence" of elevated blood serum concentrations of PFAS in residents and workers in the three PFAS-affected communities, including Katherine.

It also found there was "increased psychological distress" in the three exposed communities.

However, the study also found the evidence linking PFAS exposure to other adverse health outcomes was limited, apart from an association with elevated serum cholesterol concentrations.

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Senator McCarthy said in a statement she believes the "poor" communication from the Federal Government and Defence Department with impacted residents has contributed to their psychological distress.

"This correlates with evidence given to the PFAS sub-committee of the Joint Standing Committee on Foreign Affairs, Defence and Trade (JSCFADT), of which I am a member," she said.

"The Committee is consistently hearing from residents in PFAS-affected areas that communication from the Commonwealth Government and the Department of Defence is poor, people feel like they are being kept in the dark and that not enough progress is being made.

"The people of Katherine deserve answers. This is dragging on too long."

She also said she was dissatisfied with the answer she got from Defence after asking about the establishment of a second water treatment plant for Katherine during a committee hearing.

In a statement, a spokesperson said Defence had provided funding to Power and Water "to deliver a long-term PFAS water treatment plant with a capacity of 10 million litres per day, sufficient for the total potable water supply for the Katherine community."

The spokesperson also defended the communication of Defence with impacted Katherine residents.

"The Department of Defence understands that communities where PFAS contamination has been detected are very concerned about how this may affect them. Defence is committed to keeping the Katherine community informed on the progress of our ongoing PFAS monitoring, remediation and management activities," they said.

"Defence is planning engagement and communication activities with PFAS-affected communities for 2022, and expects to be in Katherine in the first quarter of 2022.

"Defence will continue to work with the Northern Territory Government, to support the Katherine community."

Senator McCarthy said the Northern Territory Government had faced Federal Government roadblocks in investigating PFAS in the region.

"The Northern Territory Government has expressed difficulties in accessing Commonwealth land to conduct investigative work on contaminated sites," she said.

The Federal Health Department did not respond to a request for comment by deadline.

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