Manufacturers commonly use sodium benzoate in soft drinks and other foods as an antimicrobial agent. In 2005, the U.S. Food and Drug Administration revealed that the sodium benzoate in some soft drinks was reacting with vitamin C and similar acids to form the carcinogen benzene. It was not long after this announcement that news agencies like the BBC and internet blogs alike were filled with scathing headlines about cancerous drinks stocked on store shelves.
Though the media raised public concern about benzene in foods around 2005, researchers first discovered the reaction between sodium benzoate and vitamin C, also known as ascorbic acid, in the early 1990s. The groundbreaking research first appeared in 1993 in the "Journal of Agriculture and Food Chemistry." Researchers Lalita K. Gardner and Glen D. Lawrence outlined the exact chemical reaction that takes place between sodium benzoate and vitamin C to produce benzene, and warned that this reaction should be a concern for the food industry.
Initial FDA Findings
The safe level of benzene allowable in drinking water is less than 5 parts per billion, as established by the U.S. Environmental Protection Agency. In November 2005, the FDA examined results from its Total Diet Study --- which sampled foods between 1995 and 200. The EPA found 10 soft drinks out of nearly 200 sampled that contained more than 5 parts per billion benzene. Of these drinks, nine had added sodium benzoate and ascorbic acid, and one --- a cranberry drink --- only had ascorbic acid additives.
The FDA continued to test beverages for elevated benzene levels between 2005 and May 2007. A majority of the products examined contained less than the 5 parts per billion limit. Manufacturers either discontinued or reformulated those products that exceeded safe benzene levels. The FDA also evaluated the testing methods of the Total Diet Study in 2006 and found that some of the higher benzene numbers may have been the result of heat exposure during the testing process.
Reducing Benzene Occurrence
AIB International, an independent food-quality auditor, notes that manufacturers can take a number of precautions to prevent the formation of benzene from benzoate salts and ascorbic acid. Steps such as adding sweeteners, removing oxygen from the food, raising the pH of the food above 2 and avoiding light or heat exposure can all limit the chances of benzene formation. Manufacturers that follow safe practices can effectively prevent benzene in their food products.