Carcinogenicity and regulation of caramel colorings by Michael Jacobson, (Executive Director, Center for Science in the Public Interest, USA), an article due to be published in the International Journal of Occupational and Environmental Health, states that Coca-Cola sold in California now contains little of the cancer-causing chemical 4-methylimidizole (4-MI). However, the research shows that alarming levels of the carcinogen are evident in soft drinks elsewhere around the world.
The carcinogen is formed during the production of the caramel colouring that is added to cola to give it its distinctive colour. Chemical reactions between the sugar and ammonia result in the production of 4-MI, which causes lung and liver and thyroid cancer and leukemia in laboratory animals in studies conducted by the US government. Colouring is available that does not contain 4-MI but it is four times more expensive, so is not purchased by the beverage companies.
Tests carried out by the Center for Science in the Public Interest (CSPI) will be published shortly in the International Journal of Occupational and Environmental Health (vol. 18.3). The CSPI recommends that the US Food and Drug Administration prohibit the use of ammoniated caramel colouring and provide a more accurate description of the ingredient on all product labelling nationwide.
California requires that cancer warnings be placed on any soft drinks with excessive levels of 4-MI, which could lead to a person ingesting over 30 micrograms (µg) of 4-MI in a day. It is estimated that this amount of the carcinogen would cause cancer in one in 100,000 people over their lifetime. This law has led to Californian bottlers using less of the contaminated caramel colouring, with Coca-Cola from the Golden State containing only 4 µg. Elsewhere in the world, Coca-Cola from Brazil was shown to be the most contaminated, containing 267 µg of the carcinogen per can; in Kenya, Coca-Cola contained 170 µg per can; and in the UK, Canada, United Arab Emirates and Mexico there was between 144 µg and 160 µg per can.