Benzoic acid acts as a preservative and pH adjuster in skin care formulations. It is known to be well tolerated and unlikely to cause sensitization in amounts commonly used. It should be combined with other preservatives to prevent wider contamination, especially in water-based formulas. Benzoic acid serves primarily to reduce the growth of fungi. It is not considered very active against bacteria.
In 2017, the Cosmetic Ingredient Review Expert Panel examined personal care products using up to 5% benzoic acid and determined that this ingredient is safe for cosmetic use. When used as a preservative in skin care products, you will find benzoic acid in much lower concentrations, usually between 0.2-0.5%. Note: Although benzoic acid may be aromatic in nature, it is not usually used in high enough strength to provide a detectable fragrance in skin care products. Fun fact: Benzoic acid is found naturally in fruit (berries), nuts, spices and vegetables. Rich sources include strawberries, cayenne pepper, mustard, prunes, cinnamon and cloves. Benzoic acid is also added to foods as a preservative. https://www.paulaschoice.com/ingredient-dictionary/ingredient-benzoic-acid.html?q=Benzoic%20Acid&fdid=ingredients