Sodium benzoate (and potassium benzoate) are preservatives that are added to various foods and beverages as well as medicines, mouthwashes and nutritional supplements. They prevent the growth of yeasts, bacteria and fungi. When products with benzoates are exposed to high temperature or light they can react with ascorbic acid or vitamin C to form the powerful carcinogen benzene. Benzene exposure has been linked with leukemia.

U.S. government testing done in 1990 showed that benzoate preservatives could break down to form benzene. Regulators encouraged the beverage industry to monitor themselves and to work to reduce use of the additives. However, nothing changed and the problem didn't come to light until a private citizen had beverage samples analyzed; he found they contained four times the permitted levels of benzene.

Sodium Benzoate imported from China

Sodium Benzoate in Britain

There is much more concern over the issue of sodium benzoate in Britain. Professor Piper of Sheffield University says that his studies of sodium benzoate in laboratory tests suggest that it can create free radicals and damage cells. While it is already linked with leukemia, new research suggests is may lead to cirrhosis of the liver and Parkinson's disease.

In 2000 the World Health Organization reported that there are many studies showing that sodium benzoate can cause hives, asthma and anaphylactic shock in sensitive people.

The Food Commission, a British activist group, has called for warning labels on foods that contain synthetic dyes and sodium benzoate. They note that medicines containing these additives carry warning labels.

"No one really knows what this chemical cocktail could be doing, particularly in the early stages of development. This cocktail (of synthetic additives) is far too complex." - Professor Vyvyan Howard

The British Food Standards Agency, which is the counterpart of the US Food and Drug Administration, defends the use of sodium benzoate and other additives, saying "all additives approved for use in this country undergo stringent tests and are safe for use."

But food additives are tested one at a time on healthy animals, a condition that does not reflect their use in the real world. Professor Howard of the university of Ulster is critical of the practice of testing a single food additive; a typical food may contain dozens of different additives. He led a study (Lau 2006) that found the combined damage from two additives can be seven times as great as when they are tested alone.