The national chemical regulator is still significantly understaffed, despite telling Senate Estimates it recently concluded a "very successful" recruitment round.

Many staff have abandoned the Australian Pesticides and Veterinary Medicines Authority (APVMA) since the Government announced the agency would be moved from Canberra to Armidale, in the northern NSW electorate of Deputy Prime Minister Barnaby Joyce.

The agency acknowledged that staff shortages had hurt its recent performance, which slumped last quarter.

One in five APVMA jobs remain unfilled, and a push to hire new staff has not filled the gap.

While 20 regulatory scientists have joined the agency since July last year, another 20 have quit.

The new staff included five scientists who moved to APVMA from the Health Department under a Government restructure.

Only nine were employed on an ongoing basis.

One was employed on a 457 visa, a scheme that is undergoing major changes.

Regulator confident it will attract staff

Acting APVMA boss Stefanie Janiec told Estimates the recruitment effort was "in its early stages" and "is making good progress".

"We're pretty confident we'll continue to attract strong interest in our positions," she told the Senate committee.

Previous Estimates sessions heard that recruitment was a challenge because regulatory scientists were in short supply around the world.

The agency revealed it was in the process of developing a new in-house training program, to speed up the qualification process for new and less experienced staff.

Ms Janiec said it currently took two to five years to get a new recruit up to speed.

She told Estimates the new program would take between eight and 12 months, depending on the staff member's existing experience.

"New people coming into the agency can participate in our program and get up to speed more quickly on our legislative frameworks, but also decision making, to ensure increased competencies there," she said.

The APVMA has already opened a transition office in Armidale while it prepares to move the agency's functions to the regional city in 2019.

At the end of next year, agency staff will be asked to confirm whether or not they are prepared to leave Canberra.