Scientists and inspectors at the federal agencies responsible for food safety say they face political and corporate interference with their work, according to a survey released Monday by the Union of Concerned Scientists, a nonpartisan advocate for unbiased science in government.

The survey suggests a continuation of problems that government scientists had complained about during the George W. Bush administration, despite Obama administration pledges not to let politics intrude on scientific conclusions. And it comes more than a year after the administration promised to issue new rules to protect scientific integrity.

More than 1,700 scientists and inspectors at the Food and Drug Administration and the Department of Agriculture responded to the survey, which was conducted by the Center for Survey Statistics and Methodology at Iowa State University.

The survey found only a slight improvement in perception of the agencies’ approach to science under the Obama administration.

“What we found is that action is needed to curtail interference in science, both political and that driven by the private sector,” said Francesca Grifo, director of the Scientific Integrity Program at the Union of Concerned Scientists. “We have two very different agencies giving very identical responses, and this suggests the need for broad reform.”

The Department of Agriculture, while not commenting on the survey’s findings, acknowledged a need for improvement in its food safety program.

“We can and must do a better job of ensuring the safety of meat and poultry products regulated by USDA as there is no more fundamental function of government than protecting consumers from harm,” the USDA said in a statement. “Food safety is the sole function of our Food Safety Inspection Service and no other considerations should detract from carrying out their mission.”

Almost half of those surveyed said that in the last year they had experienced “situations where corporate interests have forced the withdrawal or significant modification of [an agency] policy or action designed to protect consumers or public health.”

And 45% said they had experienced similar interference by members of Congress.

Fifty-four percent said the agencies gave political interests too much weight in their decision-making.

“Typically, once a member of Congress gets involved, the agency does whatever it can to make the situation go away rather than address food safety issues,” one USDA employee wrote in an anonymous essay that accompanied the survey questionnaire.

Dean Wyatt, a supervisory public health veterinarian who has worked for nearly 20 years at the USDA’s Food Safety and Inspection Service, said the agency went out of its way to protect businesses from costly shutdowns for failing to comply with food safety standards.

Under the Bush administration, Wyatt was reprimanded, demoted and eventually transferred when he documented inhumane treatment of hogs at a slaughtering plant in Oklahoma. He was transferred to a calf slaughterhouse in Vermont, where he has worked throughout the Obama administration.

In an interview, Wyatt cited examples of food safety violations that were suppressed or ignored. He said he suspended plant operations on three occasions. Each time, his supervisors intervened to allow the plant to reopen.

It wasn’t until an undercover investigation by the Humane Society produced video evidence of more serious violations that Wyatt’s superiors became responsive to his complaints.

kim.geiger@latimes.com