CSPI: Caramel Coloring in Coke, Pepsi Can Cause Cancer; Industry Disputes Claim Consumer group wants the FDA to ban two caramel colorings made with ammonia.

Feb. 16, 2011 -- A major consumer group today called for a government ban on two types of caramel coloring used in colas, warning that the ingredients could cause cancer. The soft drink industry came out swinging, strongly objecting to the claim.

"We're asking the FDA to ban the use of caramel coloring that's used in colas and certain other soft drinks and a variety of other foods," said Michael Jacobson, Executive Director of the Center for Science in the Public Interest. "The reason is that several years ago a government agency, the National Toxicology program tested a contaminant in the coloring and found that it caused cancer in mice and possibly rats."

According to the CSPI, pure caramel is made by heating sugar, while the coloring found in cola like Pepsi and Coca-Cola is made by reacting sugars with ammonia. Jacobson said the chemicals the reaction produces have been proven by federal government tests to be carcinogens, a finding that the Coca-Cola Company vehemently disputes.

"CSPI's statement irresponsibly insinuates that the caramel used in our beverages is unsafe and maliciously raises cancer concerns among consumers," the company said in a statement. "This does a disservice to the very public for which CSPI purports to serve. In fact studies show that the caramel we use does not cause cancer."

Watch "World News with Diane Sawyer" for more on this story tonight on ABC.

There are currently four types of caramel coloring approved by the Food and Drug Administration and the CSPI wants the FDA to prohibit the two made with ammonia, 4-MEI and 2-MEI. David Schmidt, president & CEO of the International Food Information Council also challenged CSPI's statement.

"Once again advocates are picking a chemical of the day to needlessly scare consumers," he wrote. "The primary studies linking MEIs to cancer showed varying effects in male and female mice and rats when each were tested at extremely high doses. In fact, further studies indicated that MEIs may offer a reduced risk of cancer."

CSPI Says Coloring in Cola Causes Cancer

Dr. Fred Guengerich, professor of biochemistry at Vanderbilt University, said there is merit on both sides of the debate.

"Is it a carcinogen? The tests have shown in mice it can increase the risk of cancer. On the other hand, there is also evidence in male rats, it prevented several kinds of cancer," said Guengerich. "Basically my advice would be just to relax ... I did some simple math. ... If you look at the study in terms of what the mice got, in terms of causing any effect, a human being would have to drink more than 1,000 sodas a day."

CSPI acknowledges that obesity is still a greater health risk from the consumption of non-diet soda than cancer, but maintains there is still a risk.

"I don't want to exaggerate the potency ... a very, very tiny percentage of the people who drink cola will get cancer because of that," said Jacobson. "You're not going to get cancer if you drink a soda, once in a while, but you know the more you drink the greater the risk and there's no reason to accept any risk from a substance that's just coloring."

At the beginning of this year California health officials added 4-MEI to the list of "chemicals known to the state to cause cancer." This could result in cola brands, including Coca-Cola and Pepsi being required to have cancer warning labels.

In 2009, cola made up approximately $40.7 billion of the $74 billion carbonated soft drink business. John Sicher, editor and publisher of Beverage Digest says he doubts CSPI's accusations will affect consumer's spending habits.

"I would tend to think that people are used to buying what they've been buying for more than a hundred years," he said. "I would predict colas will be brown in color for many decades to come."

For now, the FDA tells ABC News that it, along with the World Health Organization, has been studying these chemicals and their potential effects on humans. The FDA says it will respond to CSPI's petition in accordance with required timelines.