An expert advisory panel to the Food and Drug Administration said Thursday that there was not enough scientific evidence linking artificial colors with hyperactivity to warrant a warning label or new restrictions on thousands of processed foods colored by chemicals.

The 14-member panel struggled with the question, rejecting the idea of warning labels by a margin of 8 to 6.

“If we put a label that long on every chemical and ingredient that hasn’t been adequately studied . . . you wouldn’t see the package anymore,” said Tim Jones, Tennessee’s deputy state epidemiologist and a member of the panel. “It’s a question of relative concern and severity, and that’s a hard one.”

The panel recommendation makes it less likely that the FDA will place restrictions on food dyes. The agency is not obligated to follow the guidance of its advisory panels but often does.

On a separate question — whether there is enough scientific data to conclude that artificial coloring causes hyperactivity among the general population — a majority of the panel said there was not such evidence. The panel advised the FDA to pursue additional studies.

The recommendations came after a two-day discussion of the science behind artificial food dyes and hyperactivity, which has been a matter of debate since the 1970s.

The United States allows food makers to use nine dyes, most of which were approved 80 years ago. The FDA has long maintained that the dyes are safe.

But new research and a petition from the Center for Science in the Public Interest, an advocacy group, prompted the FDA to reassess whether color additives might be linked to hyperactivity in children and other health effects.

For the first time, FDA staff said Thursday that studies suggest artificial dyes may exacerbate problems for some children who already have attention deficit and hyperactivity disorder. About 5 percent of U.S. children suffer from the disorder, according to federal estimates.

Lisa Lefferts, a panel member and an environmental health consultant, acknowledged the lack of strong data but argued that federal regulators ought to do something more to protect public health. “We’re seeing something here with color additives, there’s something going on,” she said. “Are we going to wait for another 50 studies to be done before we reach any conclusions?”

Still, Barbara Blakistone, a food scientist who represented the food industry on the panel, said there was not enough evidence to justify restrictions.

Those restrictions would require “all the stops [to be] pulled, massive reformulation, massive changes in re-labeling,” she said. “We want to feel that the general public would benefit from this, and I’m not seeing that right now.”

The use of artificial food dyes has increased 50 percent since 1990, and the bright hues are found in everything from pickles to bread. Once made from coal tar but now derived from petroleum, artificial dyes are brighter, more stable and cheaper than natural colors derived from fruits and vegetables.

Food dyes serve no functional purpose and, if they carry any health risk, should be eliminated, Michael Jacobsen, executive director of the Center for Science in the Public Interest, told the panel. “Dyes would not be missed in the food supply except by the dye manufacturers,” he said.

Jacobsen said his organization might pursue legal action to try to force the FDA to require warning labels.

Two recent studies sponsored by the British government found that children given foods made with some artificial dyes and a food preservative, sodium benzoate, showed an increase in hyperactivity. The study sampled children in the general population, not just those known to be hyperactive.

The British government urged food makers to stop using six dyes, and the European Parliament required foods with those dyes to carry a label warning.

To avoid warning labels on their products in Europe, many food makers — including U.S.-based companies such as Kellogg and Mars International — found substitutes for the six dyes, including natural dyes made from fruits and vegetables.

Food coloring was first linked to hyperactivity in the 1970s by Ben Feingold, a California pediatrician who pioneered the elimination of dyes as a treatment for behavior problems in children. His 1975 book, “Why Your Child is Hyperactive,” spawned the Feingold Association, a support group and resource for people who want to follow Feingold’s elimination diet. Feingold died in 1982.

Independent reviews of Feingold’s data found the correlation between dyes and hyperactivity was inconsistent.

Food manufacturers note that the dyes are heavily regulated by the FDA, which requires approval before they can be used commercially, unlike many other ingredients used in foods.

“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,” said a statement issued by the Grocery Manufacturers Association, which represents food makers, retailers and packagers.

The FDA requires artificial color additives to be listed by name on the ingredient panel of all foods.

Get the latest political news from PostPolitics. Follow us on Twitter and Facebook.