The Center for Environmental Health, an environmental watchdog group, has warned that the caramel coloring in Pepsi contains a dangerous level of a cancer-causing agent.

The offending ingredient in question is 4-methylimidazole, which goes by the street name 4-Mel, and can be introduced into a product during the cooking process and can be found in many foods. The levels of 4-Mel at issue are prohibited in California, but not in other states.

The group commissioned an analysis of ten drinks by Coca-Cola and ten by Pepsi. Eurofins Analytical Laboratory in Louisiana carried out the analysis on California products in May and products from the rest of the country in June. The lab found no 4-Mel in any of the California products from either brand, and in only one of the Coca-Cola products from outside California.

But the lab also discovered levels of 4-Mel 4-to-8 times higher than the legal California limit in all 10 Pepsi products.

Be that as it may, loyal Pepsi drinkers are probably not in any danger. The California list of prohibited carcinogens is based on one study that only looked at 4-Mel’s effect on mice and rats. No study has yet connected the substance to cancer in humans, and the Food and Drug Administration has stated that a person would have to drink over 1,000 cans per day to consume the level of the substance that has been shown to cause cancer in rodents.

Pepsi has also issued a statement that it is working with suppliers to decrease the amount of 4-Mel resulting from its caramel coloring.

The Center for Environmental Health’s consumer product division seeks to “protect families from toxic chemicals to promote products that are safe for public health and the environment.” Its website currently includes an email campaign to convince Pepsi to make a “safer soda, not Pepsi with a cancer-causing chemical!” [exclamation point in original], if you’re outraged.