A study reveals that a popular ingredient in the manufacture of sunscreen and anti-aging creams as a UV filter, octocrylene, degrades into a toxic chemical known as a carcinogen and endocrine disruptor. The concentration of this product called benzophenone increases rapidly as the cream ages.

filter, present, in, sunscreens, turns, into, carcinogenic, compound, as, it, ages

As with most skin care products, sun creams should preferably be used within 12 months of opening. And even though there are a few tricks to keep them as long as possible, it is more than recommended to respect the shelf life indicated by the jar symbol on the back of the package.

 Octocrylene is degraded to benzophenone

A team of French-American researchers, including the CNRS, warns that an organic sun protection filter frequently used in the development of sunscreens and anti-aging creams, octocrylene, degrades within the bottles into a carcinogenic and endocrine disrupting compound: benzophenone.

Researchers point out that the industries that produce octocrylene know that this molecule is contaminated by benzophenone, and that the latter cannot be eliminated in its entirety during the production of octocrylene. In addition, the concentration of benzophenone in octocrylene based manufactured products is considered "negligible" by the cosmetics industry. "However, octocrylene degrades naturally into benzophenone within the packaging," they note. During its study published in the journal Chemical Research in Toxicology, the team discovered that this substance was present in the fifteen or so commercial products tested.

Dangerous for health and the environment

In addition, scientists have shown that the benzophenone concentration in these cosmetics increases rapidly with the aging of the product. According to them, "the scientific community and the cosmetics industry admit that octocrylene and benzophenone are easily absorbed by the skin. "A previous study showed that the cutaneous absorption of benzophenone in the body can exceed 70%, a strong argument for the regulatory ban of this product and octocrylene in perfumes and other topical products. As such, octocrylene no longer meets the safety criteria of the U.S. Food and Drugs Administration (USA).

This is especially so since "accumulated scientific data indicates that it may be toxic to reproduction, and may be a metabolic and endocrine disruptor," the researchers added. Finally, another French research published in 2018 in the journal Analytical Chemistry concluded that octocrylene is described as toxic to the environment: it affects corals in swimming areas in particular and potentially decreases the resilience of coral reefs to climate change. The fact that octocrylene products are contaminated with significant amounts of benzophenone therefore calls into question the safety of these products for public use. 

The precautionary principle must apply

To date, octocrylene has already been banned in sunscreen products in some jurisdictions such as the U.S. Virgin Islands or the Republic of the Marshall Islands. Cosmetic products containing octocrylene have also been banned in the Republic of Palau (Micronesia) since January 1, 2020. As explained by Le Monde, which relayed the study, sun creams and anti-aging products purchased (from brands such as Garnier, Bioderma, Uriage, La Roche-Posay or L'Oréal) have undergone an accelerated aging process validated in the United States, and equivalent to one year at room temperature. They were then analyzed using a high-performance mass spectrometer.

"Initially, there is very little benzophenone in the products. But gradually, as the product ages, there is more and more. Increases in benzophenone in excess of 100% and even up to 200% have been observed. This is the first time that this degradation of octocrylene into benzophenone has been shown," says Philippe Lebaron, from the laboratory of biodiversity and microbial biotechnology at the Observatory of Banyuls-sur-Mer, co-author of the study. The IARC* has classified benzophenone as a "possible human carcinogen", while in the United States it is on the lists of carcinogens and developmental disruptors. 

According to the researchers, this new study is important because it provides new scientific evidence to show that octocrylene products, and therefore contaminated with benzophenone, may pose a threat to public health as well as the environment. "Our results argue in favor of precautionary regulations to protect public health and the environment," they concluded. They thus advocate their prohibition in cosmetics knowing that octocrylene can also be found in self-tanning creams or shampoos.