UK regulators zero in on use of BHT and kojic acid in formulated cosmetics

09 Nov 2023 --- Two substances commonly formulated into beauty products have come under heightened focus of the UK’s Office for Product Safety and Standards (OPSS). The government agency’s Scientific Advisory Group On Chemical Safety Of Non-Food And Non-Medicinal Consumer Products (SAG-CS) has issued final opinions on kojic acid and butylated hydroxytoluene (BHT) in cosmetics. 

Kojic acid is a natural compound that is derived from the fermentation of rice or other starchy materials that has been used in traditional Japanese cosmetics for centuries to lighten skin and reduce hyperpigmentation. Kojic acid is also effective as an antioxidant and can help to protect skin from the sun’s harmful UV rays.

BHT is a commonly used preservative in a variety of personal care products and fragrances. These chemicals are linked to several health concerns including endocrine disruption and organ-system toxicity.

Set limits for BHT
UK regulators have introduced specific restrictions on the usage of BHT,  including toothpaste, in which BHT can now only be used at a maximum concentration of 0.1%.

A lower limit is set for mouthwash and leave-on oral care products with BHT permitted at a concentration of 0.001%.

Other leave-on and rinse-off products can contain BHT at a maximum concentration of 0.8%.

The proposed amendment is in accordance with the opinion of the SAG-CS. 

Kojic acid is suspected to be a non-genotoxic carcinogen in rodents, although the human relevance of this is unknown.These restrictions also align with the regulations under the EU Cosmetic Products Regulation, except for leave-on oral care products, where the UK imposes a more stringent restriction of 0.001%, compared to the EU.

The proposed placing on the market deadline is October 6, 2024, while the proposed making available (off-shelf) deadline is February 6, 2025.

To ensure a transparent and inclusive decision-making process, the notification of these regulations is open for comments from the public, industry stakeholders and relevant organizations. 

The comment period spans 60 days from the date of notification, providing an opportunity for all interested parties to express their concerns, suggestions, or questions regarding the BHT restrictions in cosmetics.

Guidance on safe kojic acid application
Commercially, kojic acid is used in Japan as a food preservative, additive and flavoring agent. Kojic acid is suspected to be a non-genotoxic carcinogen in rodents, although the human relevance of this is unknown.

As a result, kojic acid is not classified as a human carcinogen by the International Agency for Research on Cancer. Kojic acid was first reviewed by the UK’sSAG-CS in February 2022.

The SAG-CS states that there remains “several areas of uncertainty” in the risk assessment and that more time was needed to review the full data package to draw a conclusion on the risk to health of kojic acid in cosmetic products. 

In April 2022, OPSS released a call for data on the safety of cosmetic ingredients with suspected endocrine disrupting properties in which kojic acid was included.

In the initial opinion of the SCCP in 2008, it was concluded that the use of kojic acid at a maximum concentration of 1% in skin care formulations poses a risk to the health of the consumer due to an insufficiently protective margin of safety based upon a no observed adverse effect level of 6 mg per kg body weight per day from a 28-day oral toxicity study in rats.

SAG-CS members have since agreed that kojic acid is safe for use at a maximum concentration of up to 1% in face cream (including application to neck) and hand cream. 

Members did not consider kojic acid to be an endocrine disrupting chemical in vivo, according to the World Health Organization’s 2002 definition, and at the exposure levels that are likely to be experienced by the majority of the population through cosmetic use at the specified level.

By Benjamin Ferrer

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