Is Sodium Benzoate Safe in Cosmetics?
Sodium benzoate is a salt of benzoic acid that is found naturally in cranberries, prunes, plums, apples, and other fruits. In its solid form it is a white, granular or crystalline powder. While benzyl alcohol is an organic alcohol with a hydroxyl group (-OH), the related compound benzoic acid has a carboxyl group (-COOH). Sodium benzoate is used in a wide variety of cosmetics and personal care products where it acts as a corrosion inhibitor, fragrance ingredient, and preservative.
As a preservative, sodium benzoate is primarily an anti-fungal agent but also has some effectiveness against bacteria. It is not a broad-spectrum preservative for cosmetic use and should be combined with other preservatives. Sodium benzoate is often combined with potassium sorbate in low pH products in order to benefit from the ingredients’ synergistic effects against yeast and mold. When combined with caffeine, it can have a sunscreen effect and provide UVB protection with antioxidant activity.
While there has been some controversy over the use of sodium benzoate as a food preservative due to its potential to interact with ascorbic acid (a derivative of vitamin C) and produce benzene, the amount of sodium benzoate in foods is so low that it is FDA approved and deemed safe. Soft drinks are the main source of sodium benzoate in the diet where the ingredient is limited to a maximum of 0.1% by weight. It is absorbed, metabolized and excreted rapidly after ingestion. Sodium benzoate is not a toxin or carcinogen on its own, and large amounts of it would have to be consumed, not applied topically, for any adverse effects to be seen.
So then, is the combination of sodium benzoate and vitamin C in skin care products a potential concern? Fortunately, there are ways of formulating these products to prevent a reaction between the two ingredients from occurring. Benzene does not form at all in cosmetic products with a high concentration of vitamin C and a low concentration of sodium benzoate, because higher amounts of vitamin C cause it to act as a free radical scavenger rather than react with sodium benzoate. Products with a pH of 3 or higher are generally safer in terms of preventing benzene formation, and above a pH of 7 no benzene forms at all. Protecting products from light and heat exposure also limits the potential for benzene formation. Manufacturers that follow safe practices can effectively prevent the formation of benzene in cosmetic products that also contain vitamin C. And for the most part, sodium benzoate is only used in formulas that do not contain significant levels of vitamin C. Overall, sodium benzoate is one of the most reliable ingredients on the market and very safe for consumers.
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