Are there “toxic chemicals” in food killing Americans? That fear is getting lots of attention thanks to Robert F. Kennedy Jr., President-elect Donald Trump’s pick to head the Department of Health and Human Services. Kennedy contends that substances banned in Europe are tainting our cereals and other processed foods.

Kennedy has targeted Froot Loops as an example of the failings of the U.S. food regulation system. The U.S. version of the cereal, for example, gets its flavoring and vibrant colors from artificial food dyes. In contrast, the Canadian version’s flavors and muted colors come from ingredients like the concentrated juices of watermelon, blueberries and carrots.

But that doesn’t mean the dyes used in U.S. food are toxic or killing anyone. Other countries take a more cautious approach to food additives, sometimes banning them because they can’t be proven safe beyond a shadow of a doubt.

The European Union recently banned titanium dioxide, a coloring agent, from food products, though it’s considered safe in Canada, New Zealand, Australia, Japan, and the U.S. A toxicologist who’s done testing for the industry told me the chemical didn’t cause cancer in rats fed massive amounts. Concerns surfaced after a 1986 study in which the animals were made to inhale the additive at a concentration of 250 milligrams per cubic meter.

To put that in perspective, that amount is 50 times as dense as the dust in a typical dust storm, he said. “For a rat to live a week in that is amazing, or even a day. … They lived two years,” he said. But titanium dioxide was still banned because testing couldn’t rule out that it might damage DNA and cause cancer.

There also are some food dyes that aren’t banned but that the EU requires to have warning labels, which discourages the industry from using them.

In the U.S., the FDA sometimes requires the industry to show data from animal testing before authorizing a new additive. But feeding even large quantities of an additive to rats and mice over weeks or months can’t perfectly predict its effects on humans over the years, said Michael Jacobson, a biochemist and founder of the consumer advocacy group Center for Science in the Public Interest. Jacobson said while researchers might be able to check for things like organ damage and cancer, these studies wouldn’t be able to flag a chemical that caused ADHD or lowered IQ.

The FDA also allows some ingredients into our food without animal testing under a category known as GRAS, for Generally Recognized as Safe. The category includes some well-known ingredients such as vinegar, yeast and caffeine. But there are loopholes and errors. Jacobson said his group spent years fighting trans fats, once considered healthier than animal fats. Trans fats were finally banned in 2018 after evidence piled up that they increased the risk of dementia and heart attacks.

Despite the varying approaches to testing and deciding which additives to ban, there is one ingredient that nearly all experts agree is harmful to our health: sugar.

Obviously, sugar won’t kill you in small quantities, but as Swiss physician and chemist Paracelsus recognized 500 years ago, the dose makes the poison. Sugar is listed as the second ingredient in Froot Loops. The average American consumes more than 66 pounds of sugar a year.

That’s too much, contends Robert Lustig, a pediatrician specializing in hormonal disorders and obesity at the University of California San Francisco School of Medicine. “While all of these other things that are in processed food are bad, none of them holds a candle to the sugar,” he said.

He’s concerned with fructose, a component of sugar and other sweeteners, including high fructose corn syrup, maple syrup, honey and agave. It acts very differently in our cells from glucose, the building block of starches.

He described how fructose triggers the production of fat in the liver, leading to what he calls metabolic derangement and, eventually, Type 2 diabetes. The toxic effect was demonstrated not just in animals but in people. In one study, he and colleagues monitored children on their typical home diets, then again after replacing some of the sugar in their diets with starch. They kept the calories the same. After just a few days, the children had less fat in their livers, lower blood pressure, lower serum triglycerides, and their insulin production normalized.

Fruit contains fructose, but an apple has five grams compared to 10 grams in an 8-oz Coke. The fiber in most fruit protects the liver from the incoming assault — which is why juice can raise the risk of diabetes while fruit does not. Lustig doesn’t dismiss the harm caused by other additives, BPA, or other chemicals that sneak in from packaging — but he estimates that sugar is causing 80% of our food-related health troubles.

We can’t ban sugar, but Jacobson of the Center for Science in the Public Interest said other countries have successfully reduced sugar consumption by taxing sugary drinks. In Chile, foods high in sugar and other ingredients deemed harmful must carry a warning label — shaped like a stop sign — and can’t be marketed to children or sold in schools. Several other countries, including Israel and Mexico, have tried similar warning systems.

Taking the artificial dyes out of Froot Loops can’t hurt, but it probably won’t help much. Taking away the friendly Toucan and slapping on a stop sign — that might be a start toward making America healthier.

F.D. Flam is a Bloomberg Opinion columnist covering science. She is host of the “Follow the Science” podcast.