What's more cutting is that Canberra volunteer firefighter Crombie is the world record holder for the T38 shot put class, which is for cerebral palsy athletes or those without fully- functioning limbs.

He won the T38 gold at the Dubai world titles on Monday with an effort of 15.73m - to defend the gold he won in London two years ago.

But in a bid by the International Paralympic Committee (IPC) to reduce the number of events and keep control over the integrity of their sports, disability classes with dropping participation numbers are being cut.

There were only nine competitors in the T38 class shot put in Dubai.

Gold medallist Crombie and bronze medallist Jackson (15.14m) will have to hone their javelin skills if they want to make the Australian team for next year's Paralympics in Tokyo.

As they stood beaming and joking with each other after they accepted their medals at the Dubai medal plaza, they tried not to dwell on the down side of their achievement.

"Shot put isn't an event for us in Tokyo but it will be at the next worlds in 2021 in Kobe," Crombie, who has cerebral palsy, said.

"I'll reassess after Tokyo, but for the Games I've got to go back to javelin and that means putting a lot more stress on the body.

"Two days after I get back from Dubai I'm due for (right) elbow surgery to repair some stuff there that I've been battling with the last two years.

"Hopefully that frees up a lot of energy and time to be able to chase javelin again."

Crombie continued an impressive championship for Canberra-based athletes, with Evan O'Hanlon winning bronze in the T38 100 metres final, taking his haul from the past five world championships to 12 medals.

Long-jumper Sarah Walsh also won bronze with a 5.2 metre leap in the T64 cateogry.

She had been moving around the medals - starting in fourth spot, then to third, back to fourth, up to second and finally settling on third.

"I started off a little bit choppy and then finally got into the rhythm. My coach Matt Beckenham said to me 'Just put a jump out there that's going to scare the girls and that's what I did," Walsh said.

"I knew I was capable of jumping big."

Jackson wore a brace on his left knee in Monday's final, as it is partially paralysed after a bad dislocation playing American football.

"Unfortunately our (shot put) event isn't there," he said of the Paralympic medals on offer in 2020.

"But I'll make the transition to javelin. My aim is to hopefully get to Tokyo."

"It will be a big task but at a minimum, I can push the guys in front of me.

" I see that as a part I can play in helping Australia do well in Japan."

Crombie and Jackson's success was the first time two Australians have stood on the podium together during the five days of competition in the UAE.