Almost nine out of 10 young people tested in the Northern Territory have elevated levels of lead in their blood, with one young person clocking in at 17 times over the acceptable limit.

The NT Health Department conducted blood tests across several north-east Arnhem Land communities, targeting anyone thought to be sniffing aviation fuel, as part of an emergency health campaign that began in April.

Of the 178 young people tested, 154 were found to have elevated levels of lead in their blood.

The highest was 17 times above the acceptable levels of 5 micrograms per decilitre; the average was six times above acceptable levels.

The NT has the highest levels of lead detected in blood of anywhere in the developed world, NT Centre for Disease Control acting director Charles Douglas said.

"It's a public health emergency," he said.

"It's a serious issue because the levels are high and, particularly in children, the effects are long-term and some of them are irreversible."

In May, the ABC revealed some children on Elcho Island were climbing on to planes and siphoning Avgas from fuel tanks in the wings.

Trevor Gurruwiwi from Marthakal Group said the results were "very, very shocking".

He said the group, which runs the airport on Elcho Island is taking steps to address the problem, including seeking government funding for a security guard to patrol the airstrip and organising a community-led rehabilitative bush camp for children addicted to sniffing Avgas.

Mr Douglas said it was pleasing to note a slight reduction in levels since testing began in April, due to children being prevented from accessing the source of the fuel in those communities tested — Galiwinku, Gapuwiyak, Yirrkala, Milingimbi, and some remote homelands on Elcho Island.

There was no evidence so far of the problem having spread to other communities, he said.

Map NT Communities affected by higher blood levels for children who have sniffed Avgas

'It kind of snuck under the radar'

Authorities had believed Avgas fuel was "unsniffable" until they discovered earlier this year a patient at Royal Darwin Hospital was sick because of high blood lead levels.

"It turned out he'd been sniffing Avgas," Dr Douglas said.

They soon realised the fuel contained large amounts of lead, a toxic substance with long-term health effects if ingested.

"A long time ago, Avgas was substituted for petrol in some communities because it was unsniffable and it was very effective," Dr Douglas said.

"But the formulation has changed, and it's now classified as a sniffable substance. It kind of snuck under the radar."

The revelations prompted an urgent intervention in communities to determine the extent of the problem.

"It just took us back to those very, very bad years when people were sniffing leaded petrol and the levels are the same as that," Dr Douglas said.

"We were very alarmed that in this day and age it's happening again."

Dr Douglas said lead was a "nasty poison" that could lead to behaviour disorders, liver and kidney damage, and even death.

The process of removing it from the blood involved taking a medicine that is "not without risks" and is only used in exceptional circumstances to protect against further brain damage.

"We don't do it unless the levels are very high because the treatment we use also takes out other minerals from the body which we need," Dr Douglas said.