CPSI released the results of the study earlier this week, saying that Coke, Pepsi and the diet versions of each contain high levels of a chemical that is known to cause cancer in lab rats. The ingredient is in the caramel colouring that gives cola its signature brown hue.
The state of California added the compound in question, called 4-methylimidazole or 4-MI, to its list of known carcinogens in 2011.
However, the U.S. Food and Drug Administration said in a statement that drinking cola poses no immediate risk to consumers — in fact, a person would have to drink more than a thousand cans of soda daily to match the amount of the substance given to rats in lab studies.
The good news is Canadian women drink a whole lot less than that. On average, Canadian women under age 30 drink 186 grams of pop per day, or about a half a can, according to a 2008 report by Statistics Canada. Women aged 31 to 50 consume even less, about 166 grams per day.
Health Canada considers caramel colouring to be safe, and 4-MI is an ingredient in several Canadian soft drinks, including Coke.
Despite the health authorities' skepticism that the ingredient is harmful to consumers, Coca-Cola is tweaking its recipe to lower its cola's 4-MI content in order to avoid being forced, under California law, to include a cancer warning label on cans.
"The company did make the decision to ask its caramel suppliers to make the necessary manufacturing process modifications to meet the requirement of the State of California," Diana Garza Ciarlante, a Coca-Cola spokeswoman, wrote in an email to NPR. The company has also said there is no timetable for the changes to make their way to products in Canada.
The Vancouver Sun reports that Pepsi will also be changing its recipe as a result of the findings.
That's a step in the right direction, according to CSPI executive director Michael F. Jacobson.
"The coloring is completely cosmetic, adding nothing to the flavor of the product," he said in a statement, adding, "If companies can make brown food coloring that is carcinogen-free, the industry should use that."