Kojic acid (C6H6O4; 5-hydroxy-2-(hydroxymethyl)-4-pyrone) is a mild inhibitor of the formation of pigment in plant and animal tissues, and also has also has antibacterial and antifungal properties. It is therefore used in cosmetics to preserve or change colours of substances, or as a skin lightener.
When used as a skin whitening agent, kojic acid is generally formulated at a concentration of 1% in leave-on creams. However, products containing Kojic acid can be find on the market at concentrations higher than 1%.
The safety of Kojic acid was recently investigated by theEuropean Scientific Committee on Consumer Products (SCCP) upon request of the European Commission.
After a stringent review of its toxicological profile, including mutagenicity and genotoxicity, carcinogenicity and reproductive toxicity, the substance was found to be a sensatizer, but not photosensitising. Furthermore, percutaneous absoption of the product, is relatively high, and repeated exposure in rats resulted in higher blood levels of Kojic acid than after single administration. « In humans repeated use of bleaching products may also result in higher systemic exposure than determined after single administratione, » the SCCP says.
Based on the information provided, the scientific body calculated margins of safety suggesting that the use of Kojic acid at a maximum concentration of 1.0% in skin care formulations poses a risk to the health of the consumer.
- SCCP opinion on Kojic acid (click on the image to retrieve the text):