As the partial U.S. government shutdown enters its record 30th day, the U.S. Food and Drug Administration commissioner said the agency may recall more people to perform high-risk food safety inspections and other tasks.

The FDA’s Scott Gottlieb said in a series of tweets today that certain staff are still working without pay on inspections, import enforcement and other operations. “More staff could be on the way depending on needs,” he said.

The FDA has called back about 100 investigators and 35 supervisors for domestic food surveillance inspections, he said.

“Taken together, it’s smaller than our usual footprint,” he said. “But we’re targeting the riskiest products to make sure that Americans remain protected.”

In addition, the FDA’s Office of Import and Enforcement Operations, which covers international mail facilities and ports of entry, has about 450 FDA staff in the field supporting critical safety operations, Gottlieb said. He later tweeted out a note of thanks to staff members who are working without pay through the shutdown.

The FDA shares responsibility for most U.S. food inspection with the U.S. Department of Agriculture. USDA is responsible for the safety of most meat, poultry and egg products, while the FDA regulates other foods, including fruits and vegetables. USDA’s slaughterhouse inspectors remain on the job, unpaid, during the shutdown.