FDA inspectors normally examine operations at about 160 domestic manufacturing and food processing plants each week. Nearly one-third of them are considered to be at high risk of causing food-borne illnesses. Food-borne diseases in the United States send about 128,000 people to the hospital each year, and kill 3,000, according to the Centers for Disease Control and Prevention.

Domestic meat and poultry are still being inspected by staff at the Agriculture Department, but they are going without pay. The FDA oversees about 80 percent of the nation’s food supply, as well as most overseas imports.

In a series of tweets, Gottlieb said he was taking steps to restore food safety surveillance inspections and to cover more of the high-risk sites as the shutdown continued. He said he hoped to bring back about 150 inspectors who had been furloughed during the shutdown, perhaps as early as next week.

Food safety advocates said they were worried that outbreaks would not be prevented without inspections, or would not be caught at the earliest warning signs.

The agency, part of the Department of Health and Human Services, is not dependent on federal funding for all of its activities. It receives much of its support from user fees imposed on the pharmaceutical, medical device, generic drug and other industries it regulates.

Although about 41 percent of the staff is now furloughed because the agency had not received its federal appropriations before the shutdown, those in jobs supported by user fees have remained at work. But even those departments have taken a hit, as the FDA has had to shift priorities for some duties.

In the pharmaceutical section, for example, some officials who generally consider pending drug applications are now working on post-market surveillance, checking for adverse events, like unexpected side effects of drugs or other problems.

This article originally appeared in The New York Times.