EWG Risk Score:
What is it:
Benzoic acid is a weak acid that's used as a preservative. It's naturally ocurring in many fruits in trace amounts. The largest natural source of benzoic acid is from the gum of the Chinese Balsam tree, called gum benzoin. Gum benzoin is typically 13-20% benzoic acid.
- Current research has not found it to act estrogenically when ingested (Source) However, see my note below.
- Some animal tests have shown it to be a developmental neurotoxin at high doses (Source)
- It is considered safe only at less than a .1% concentration in a finished product (Source)
- When benzoic acid and vitamin C (ascorbic acid) or citric acid are present, under the right conditions of heat and light, these two ingredients can combine to create the known carcinogen, benzene. (Source)
- Sodium benzoate is the sodium salt of benzoic acid, so the safety data for benzoic acid and sodium benzoate are similar.
Type of products it's in:
Toothpastes, moisturizers, sunscreen, makeup, body wash, mouthwash
Some brands that use this ingredient:
(According to EWG; please review all product labels for up-to-date information)
Kiss My Face
Tom's of Maine
I am personally still concerned about benzoic acid being a weak estrogen mimicker. Because of its benzene ring structure, it has the potential to fit in to our body's estrogen receptors. The studies that showed it wasn't estrogenic was when it was fed to rats, but not applied on their skin. Parabens aren't estrogenic when you eat them, but are problematic when applied to skin because they interfere with an enzyme called SULT that helps flush estrogen out of the body. Continued application of parabens and other estrogen mimicking chemicals on your skin can actually raise estrogen levels through this mechanism. There have been no studies on the estrogenic activity of benzoic acid when applied to skin, so I still view this ingredient with caution.
Additionally, it should not be used in a product containing ascorbic acid (vitamin C) and citric acid. Over time these ingredients can react and form traces of benzene, a known carcinogen.
NOTE: Benzoic acid is not parahydroxy benzoic acid.
Notice the parahydroxy benzoic acid contains an additional hydroxyl group (an extra OH group). Parahydroxy benzoic acid has been studied and is known to act estrogenically. (Source) For more about parahydroxy benzoic acid, read our article about Japanese Honeysuckle Extract here.