Lab tests find carcinogen in Coke and Pepsi

New chemical analyses have found that Coca-​Cola, Pepsi-​Cola, Diet Coke, and Diet Pepsi contain high levels of 4-​methylimidazole (4-​MI), a known animal carcinogen.

The carcinogen forms when ammonia or ammonia and sulphites are used to manufacture the caramel colouring that gives those sodas their distinctive brown colours, according to the Centre for Science in the Public Interest (CSPI), the nonprofit watchdog group that commissioned the tests.

CSPI first petitioned the Food and Drug Administration (FDA) to ban ammonia-​sulphite caramel colouring in February 2011. CSPI has reiterated its call to the FDA to revoke its authorisation for caramel colourings that contain 4-​MI, and in the interim to change the name of the additive to ammonia-​sulphite process caramel colouring or chemically modified caramel colouring for labelling purposes.

CSPI executive director, Michael Jacobson, said: “Coke and Pepsi, with the acquiescence of the FDA, are needlessly exposing millions of Americans to a chemical that causes cancer. The colouring is completely cosmetic, adding nothing to the flavour of the product.

“If companies can make brown food colouring that is carcinogen-​free, the industry should use that.  And industry seems to be moving in that direction. Otherwise, the FDA needs to protect consumers from this risk by banning the colouring.”

CSPI collected samples of Coca-​Cola, Pepsi-​Cola, Diet Coke, Diet Pepsi, Dr Pepper, Diet Dr Pepper, and Whole Foods 365 Cola from Washington (US) stores. Pepsi’s products had 145–153 micrograms (mcg) of 4-​MI in two 12oz cans. Regular Coca-​Cola had 142 mcg per 12oz in one sample and 146mcg in another. Diet Coke had 103mcg per 12oz in one sample and 113mcg in another.

To put those levels into context, the state of California has a 29mcg benchmark for 4-​MI. Levels above that in a serving of food or beverage may be required to bear a warning notice. Based on California’s risk model, CSPI estimates that the 4-​MI in the Coke and Pepsi products tested is causing about 15,000 cancers in the US population.

While federal law bans food additives that cause any number of cancers, the FDA has an exception for contaminants of food additives, for which it tolerates a lifetime risk of one cancer in one million people.

Three of four samples of Dr Pepper or Diet Dr Pepper that CSPI tested had low levels of 4-​MI, with about 10mcg per 12oz. But even those levels pose a cancer risk of seven in one million-​seven times greater than what FDA allows. The lower levels in those three samples indicate that it is possible to lower, if not eliminate, the amount of 4-​MI.

Pepsi told CSPI that it has switched to a colouring in California that contains much less 4-​MI and plans to do the same in the rest of the country.

“When most people see ‘caramel colouring’ on food labels, they likely interpret that quite literally and assume the ingredient is similar to what you might get by gently melting sugar in a saucepan,” Jacobson said.

“The reality is quite different. Colourings made with the ammonia or ammonia-​sulphite process contain carcinogens and don’t belong in the food supply. In any event, they shouldn’t be obscured by such an innocuous-​sounding name as ‘caramel colouring.’”

As troubling as the new test results are, CSPI says soda drinkers should be much more concerned about the high-​fructose corn syrup or other sugars used in soft drinks. Soda drinkers are much more likely than non-​soda drinkers to develop weight gain, obesity, diabetes, and other health problems.

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