One in five regulatory scientists have now quit the national chemical regulator as the agency forges ahead with a move away from Canberra.

In Senate Estimates hearings on Tuesday, Australian Pesticides and Veterinary Medicines (APVMA) chief executive Kareena Arthy also confirmed a new facility would need to be built in northern NSW to accommodate the agency.

A private developer would build that facility and then lease it back to the APVMA, Estimates heard.

Deputy Prime Minister Barnaby Joyce has championed the relocation of APVMA to Armidale, in his electorate of New England, saying it would boost the local economy.

But fears that highly qualified staff would quit rather than move away from Canberra have been borne out, with Ms Arthy informing senators that 20 of 100 regulatory scientists had now left the agency.

The residue assessments team is operating at half strength, and the agency has started missing deadlines for short-term chemical applications by two to five weeks.

'Not a lot of success' in recruiting new staff

Ms Arthy said staff departures were "overwhelmingly" driven by the relocation.

"They either don't want to move to Armidale and they've decided to look for something more permanent now, regardless of the incentives that we're offering for people to stay," she said.

"Quite a lot of the people who have left have got young families and they want to make sure that they are able to sustain their families in Canberra, so they have decided to take jobs and move elsewhere.

"There are a couple of people who've got a better job and so they've left.

"But overwhelmingly, when we talk to people, they've made the decision they don't want to move to Armidale, they don't want to work remotely which is one of the offers that I've made for the regulator scientists, and they want to provide certainty for their families now."

She noted the agency was "not having a lot of success" in recruiting people who wanted to move to Armidale.

Ms Arthy said that added an extra level to the agency's recruitment challenge — the need to find people who could fill skills gaps right now, as well as people who were prepared to build careers in Armidale over the long term.

Incentives being offered

Incentives being considered to induce scientists to stay on include a 15 per cent salary loading over three years.

Scientists are also being offered the chance to work from home, although Ms Arthy noted that would require APVMA's IT systems to be "completely rebuilt" and it was unclear how much that project might cost.

Any IT rebuild would need to be signed off by the relevant ministers.

Ms Arthy told Estimates that she was "doing [her] very best to entice people to go to Armidale" and the APVMA was actively recruiting, including by reaching out to similar regulators in New Zealand and Canada to see if staff there would consider working in Australia.

She said those regulators told her to "go away" because regulatory scientists were in short supply in those countries too.

Farmers and the chemical industry have campaigned against the APVMA relocation and warned there would be an impact on agricultural productivity and efficiency if the assessment of new products slowed.

Previous figures have suggested it could cost taxpayers $25.6 million to relocate the agency to northern New South Wales.

A government-commissioned cost benefit analysis of the move found there would be no material advantage in moving the agency.