As part of his pledge to “Make America Healthy Again,” Robert F. Kennedy Jr. has said he wants to build an “off-ramp” from the country’s reliance on insecticides and herbicides to grow food.

“The chemicals pollute our bodies the same way that they pollute the soil,” Mr. Kennedy said in 2024. This week, Mr. Kennedy, now the federal health secretary, said that a commission established by President Trump to examine chronic disease rates would look into the use of pesticides, as well as childhood vaccines, microplastics and more.

Mr. Kennedy’s opposition to herbicides, particularly a widely used chemical called glyphosate, has earned support from some environmental advocates, so-called “MAHA moms” and wellness influencers. But some of the claims he and others have made about glyphosate — including that it is potentially linked to cancer, gluten allergies and a variety of other health issues — are based on science that is still not settled.

Prominent organizations have come to markedly different judgments on glyphosate after reviewing the research. In 2015, the International Agency for Research on Cancer classified glyphosate as “probably carcinogenic to humans.” Two years later, the Environmental Protection Agency concluded that glyphosate was “not likely to be carcinogenic to humans” and that it posed “no other meaningful risks to human health when the product is used according to the pesticide label.”

So should you be trying to avoid it? Here’s what the science shows.

How is glyphosate used?

Glyphosate, first sold by Monsanto in 1974 under the brand name Roundup, kills weeds by inhibiting an enzyme that is essential for plant growth. It became the most used weedkiller nationwide after Monsanto introduced genetically modified crops that were resistant to glyphosate’s effects, said Marty Williams, an ecologist with the United States Department of Agriculture’s research service.

Nearly half of all planted acres of corn and soybeans in the United States are treated with glyphosate-based herbicides, as are some crops like tree nuts and grapes. Glyphosate is also sometimes used to dry out or kill wheat, barley, oats and beans, so farmers can harvest them sooner — a process that environmental groups argue is why the herbicide’s residue ends up in pasta, cereals and other processed foods.