Sodium benzoate is a food preservative added to fruit juices, soft drinks and foods that have an acidic pH. Sodium benzoate is related to benzoic acid, and both exist in the stomach as benzoate, so they're usually combined in discussions on research. Neither appears to cause cancer in humans at amounts consumed in a standard diet; however, they can form benzene when mixed with vitamin C under certain conditions.
U.S. FDA
The U.S. Food and Drug Administration lists benzoic acid and sodium benzoate as GRAS, or generally recognized as safe. According to the information published on FDA.gov, rats fed an amount of sodium benzoate equivalent to 180 times the amount found in a typical human diet show no adverse effects. They have found no evidence to show benzoic acid and sodium benzoate are hazardous when ingested at levels normally consumed in a typical diet.
U.S. EPA
The U.S. Environmental Protection Agency says that there are no reports of toxic effects on humans at daily intakes of 34 to 328 mg sodium benzoate and 0.9 to 34 mg for benzoic acid. They also say they're not able to classify sodium benzoate and benzoic acid for human carcinogenicity because there is no human data and animal studies on cancer are inadequate.
WHO
The International Programme on Chemical Safety of the World Health Organization published a report on benzoic acid and sodium benzoate in 2000. Sodium benzoate or benzoic acid may cause allergic reactions in people who are sensitive to them; however there appear to be no reports of cancer up to that date.
Benzene Formation
Benzene is a chemical that causes cancer; however, exposure is usually from chemicals, dyes, detergents and air emissions from car exhaust and burning coal or oil. Benzenes can form when ascorbic acid, or vitamin C, and sodium benzoate combine in high heat. The U.S. FDA found 10 soft drink products that contained levels of benzene above the acceptable 5 ppb level in 2005. Soft drink manufacturers changed their formulas to avoid benzene formation.
References
- International Programme on Chemical Safety: Concise International Chemical Assessment Document No. 26 - Benzoic Acid and Sodium Benzoate
- FDA.gov: Database of Select Committee on GRAS Substances (SCOGS) Reviews - Benzoic Acid
- U.S. EPA Integrated Risk Information System: Benzoic Acid
- FDA.gov: Questions and Answers on the Occurrence of Benzene in Soft Drinks and Other Beverages
