In summertime, cows wait under a canopy to be milked at Mark McAfee’s farm in Fresno. From his Cessna 210 Centurion propeller plane, the 63-year-old can view grazing lands of the dairy company he runs that produces products such as unpasteurized milk and cheese for almost 2,000 stores.

Federal regulators say it’s risky business. Samples of raw milk can contain bird flu virus and other pathogens linked to kidney disease, miscarriages, and death.

McAfee, founder and CEO of the Raw Farm, who also leads the Raw Milk Institute, says he plans to soon be in a position to change that message.

Robert F. Kennedy Jr., the anti-vaccine activist President Donald Trump has tapped to run the Department of Health and Human Services, recruited McAfee to apply for a job as the FDA’s raw milk standards and policy adviser, McAfee said. McAfee has already written draft proposals for possible federal certification of raw dairy farms, he said.

Virologists are alarmed. The Centers for Disease Control and Prevention recommends against unpasteurized dairy that hasn’t been heated to kill pathogens such as bird flu. Interstate raw milk sales for human consumption are banned by the FDA. A Trump administration that weakens the ban or extols raw milk, the scientists say, could lead to more foodborne illness. It could also, they say, raise the risk of the highly pathogenic H5N1 bird flu virus evolving to spread more efficiently, including between people, possibly fueling a pandemic.

“If the FDA says raw milk is now legal and the CDC comes through and says it advises drinking raw milk, that’s a recipe for mass infection,” said Angela Rasmussen, a virologist and co-editor-in-chief of the medical journal Vaccine and an adjunct professor at Stony Brook University in New York.

The raw milk controversy reflects the broader tensions President Donald Trump will confront when pursuing his second-administration agenda of rolling back regulations and injecting more consumer choice into health care.

Many policies Kennedy has said he wants to revisit — from the fluoridation of tap water to nutrition guidance to childhood vaccine requirements — are backed by scientific research and were established to protect public health. Some physician groups and Democrats are gearing up to fight initiatives they say would put people at risk.

Raw milk has gained a following among anti-regulatory conservatives who are part of a burgeoning health freedom movement.

“The health freedom movement was adopted by the tea party, and conspiracy websites gave it momentum,” said Paul Offit, director of the Vaccine Education Center at Children’s Hospital of Philadelphia, who has studied the history of the anti-vaccine movement.

Once-fringe ideas are edging into the mainstream. Vaccine hesitancy is growing.

Arkansas, Utah, and Kentucky are weighing legislation that would relax or end requirements for fluoride in public water. And 30 states now allow for the sale of raw milk in some form.

While only an estimated 3% of the U.S. population consumes raw milk or cheese, efforts to try to restrict its sales have riled Republicans and provided grist for conservative podcasts.