It will be more than three years for some of more than 600 residents who offered their blood to see what impact PFAS chemicals were having, or likely to have, on their health.

The town-wide response is believed to one of the biggest ever in Australia to screen for PFAS.

The Federal Government in 2018 gave the Australian National University $2 million to study the health risks of living with PFAS, with free blood checks in Katherine, Oakey and Williamtown.

The health ramifications of the chemical contamination still seeping off the Tindal RAAF Base is the next stage in the PFAS nightmare for Katherine after the Defence Department agreed to pay thousands of property owners for the lost value of their land.

That successful class action is expected to pave the way for a future claim on health impacts, particularly when the science from studies like that being conducted by the ANU is known.

Defence has also agreed to pay for a new treatment plant to remove PFAS from the town's drinking water, construction of the plant is expected to begin next week.

Initial results of blood testing done by Dr P.J. Spafford for the government found at least some Katherine residents with high concentrations of PFAS in their blood.

Test results have been provided to individuals but whether the town is in the grip of a community-wide crisis won't be known for years.

It is the ANU's job to collate all that information from the testing.

The NT Health Department has already released the results of a desktop cancer check for Katherine.

NT chief medical officer Dr Hugh Heggie said the research showed no evidence of cancer clusters in the Katherine region.

Dr Heggie said Katherine's cancer statistics were even lower on average than the rest of the NT.

Australia's chief medical officer, Professor Brendan Murphy, last year said a positive blood test for PFAS contaminants would not indicate, by itself, any harm to a person's health.

"Blood levels are not predictive of health problems in individuals. There is no consistent evidence of PFAS resulting in specific health impacts therefore levels considered higher than the Australian general population may have no impact on the individual," the federal Health Department said.

There is no practical treatment available to lower levels of PFAS in people, the department advises.

The chemicals last for a long time in the human body.

Despite this advice, the ANU says Katherine residents have been potentially exposed to PFAS through the use of contaminated water including bore water on their properties, and eating locally grown foods.

ANU principal investigator Professor Martyn Kirk told Katherine Times this week the study was expected to be finished and released by the end of this year, now it will be next year.

Professor Kirk said COVID-19 lockdowns had delayed the gathering of all the information needed.

For one, Katherine needs a "comparison community" to gauge not only its PFAS exposure but its health against.

He said ANU wants to find about 500 willing volunteers in Alice Springs to provide blood so it could be Katherine's "comparison".

He said talks were ongoing about using Alice Springs as the Katherine health comparison.

Professor Kirk said he understood the delay could cause further anxiety among those who provided the blood in Katherine.

"These are circumstances beyond our control," he said.

He said the ANU was confident would be complete by the middle of 2021.

While you're with us, you can now receive updates straight to your inbox each Friday at 6am from the Katherine Times. To make sure you're up to date with all the news, sign up here.