Almost 40 years ago, artificial food dyes had their moment in the sun.
In 1969, Soviet scientists announced that Red Dye #2 caused cancer in rats. Seven years later, the Food and Drug Administration agreed, and banned the ubiquitous coloring from U.S. food - creating a cultural icon for a generation that used "Red Dye #2" as shorthand for anything toxic.
Now, synthetic dyes are getting a second run. New research indicates the chemicals can disrupt some children's behavior, and activists and consumer groups are asking for bans or limits on the dyes. A prestigious British medical journal recommended that doctors use dye-free diets as a first-line treatment for some behavior disorders; British regulators are pressuring companies to stop using the dyes, and some are complying.
The issue has generated much less attention on this side of the Atlantic. The FDA says the dyes are safe, and has no plans to limit their use.
"At this point, there's no evidence of a connection between dyes and children's behavior," says FDA consumer safety officer Judith Kidwell. She points out that in 1982, a National Institutes of Health panel examined the safety of artificial dyes and found no evidence of risk.
That attitude frustrates activists. "They're at least 20 years behind the science," says Michael F. Jacobson, executive director of the Center for Science in the Public Interest. Last month, the group petitioned the FDA to ban use of the dyes, as well as sodium benzoate, a common preservative that critics also suspect of contributing to attention deficit hyperactivity disorder, or ADHD.
"At the very least, they ought to give some consideration to what the British government is doing," Jacobson said.
The FDA is reviewing the CSPI's petition; a spokesman said he didn't know when the agency would respond.
Scientists aren't sure how these chemicals might affect the brain. There are only eight artificial food dyes used in the U.S. To get specific colors, manufacturers mix them.
All are made from petroleum or coal tar, and most are in the "azo" family, which means they contain a specific kind of nitrogen. Some researchers have found evidence that azo dyes interfere with dopamine, a neurotransmitter that plays a key role in the ability to focus and think clearly.
Whatever the possible cause, the debate will likely heat up here, in part because ADHD has become so widely diagnosed. The U.S. Centers for Disease Control and Prevention estimates that 4.4 million American children have the disorder. People with ADHD have trouble focusing and act impulsively.
In 2003, 2.5 million children were taking medication to treat the disorder, usually powerful stimulants such as Ritalin.
Some parents aren't waiting for regulators. For years, Judy Mann and her husband, Gantt Kush- ner, tried to find help for their son, Jacob Mann Kushner. The boy, now 11, has ADHD as well as an explosive temper that produced epic - often violent - outbursts.
The couple tried various treatments, including behavioral therapies and drugs, with little success. Last year, they removed artificial dyes and some other additives from Jacob's diet. Since then, Judy Mann says, her son has improved markedly.
"We stopped, and bam, that was it. This has all but eliminated his explosive temper tantrums," she says. "The only time he has them is when he eats something he shouldn't have."
Like many parents, Mann follows a version of the Feingold Diet, which was developed in the 1960s by the late Dr. Benjamin F. Feingold, a California allergist and pediatrician. He argued that many patients with behavior problems improved after eliminating synthetic colors, flavors, sweeteners and preservatives from their diets.
Jane Hersey, director of the Feingold Association of the United States, estimates that 200,000 U.S. families follow some version of his program.
For decades, a few researchers and parents have argued that some colorings and additives can cause or exacerbate ADHD and other behavior problems. The medical establishment, regulators and industry largely dismissed or ignored these warnings.
But new work has changed the terrain. Last year, researchers at the University of Southampton in England looked at a group of almost 300 children. Half were 3-year-olds; the others were 8 or 9.
One group got a combination of food colorings, while a second group got colorings and the preservative sodium benzoate. A third group received a placebo. The quantity of chemicals was typical of a normal diet.
Scientists reported that the older children displayed a "significant adverse effect" from both chemical mixes. The 3-year-olds were affected only by the diet with dyes alone.
In 2004, a Columbia University psychiatrist, Dr. David Schwab, reviewed 30 years of rigorous scientific studies involving food dye and behavior. He concluded that the dyes likely caused "neurobehavioral toxicity."