In a concluding report, staff scientists from the F.D.A. wrote that while typical children might be unaffected by the dyes, those with behavioral disorders might have their conditions “exacerbated by exposure to a number of substances in food, including, but not limited to, synthetic color additives.”

Image Froot Loops cereal contains artificial dyes. Credit... Tony Cenicola/The New York Times

Renee Shutters, a mother of two from Jamestown, N.Y., said in a telephone interview on Tuesday that two years ago, her son Trenton, then 5, was having serious behavioral problems at school until she eliminated artificial food colorings from his diet. “I know for sure I found the root cause of this one because you can turn it on and off like a switch,” Ms. Shutters said.

But Dr. Lawrence Diller, a behavioral pediatrician in Walnut Creek, Calif., said evidence that diet plays a significant role in most childhood behavioral disorders was minimal to nonexistent. “These are urban legends that won’t die,” Dr. Diller said.

There is no debate about the safety of natural food colorings, and manufacturers have long defended the safety of artificial ones as well. In a statement, the Grocery Manufacturers Association said, “All of the major safety bodies globally have reviewed the available science and have determined that there is no demonstrable link between artificial food colors and hyperactivity among children.”

In a 2008 petition filed with federal food regulators, the Center for Science in the Public Interest, a consumer advocacy group, argued that some parents of susceptible children do not know that their children are at risk and so “the appropriate public health approach is to remove those dangerous and unnecessary substances from the food supply.”