Researchers are calling for it to be banned.
Octocrylene, an ingredient found in many cosmetics (moisturizers, self-tanners, shampoos, etc.), turns into benzophenone, which accumulates rapidly with the product's aging, according to a Franco-American team.
It analyzed around fifteen sunscreen and anti-aging creams purchased in France and the United States.
Their work appears Monday in a trade journal of the American Society of Chemistry, Chemical Research in Toxicology.
Octocrylene is accused of being harmful to marine life, especially corals.
"Some manufacturers have withdrawn it from their sunscreens for environmental reasons", notes Philippe Lebaron, biologist of the biodiversity and microbial biotechnology laboratory of the Banyuls-sur-Mer Observatory (Sorbonne University / CNRS, France) co-author of the study.
Territories with coral reefs, such as the US Virgin Islands or the Republic of the Marshall Islands, have also banned octocrylene in sun protection products, the researchers note.
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Benzophenone is classified as "possibly carcinogenic to humans (Group 2B)" by the International Agency for Research on Cancer (IARC / Iarc) of the WHO.
And according to this health agency, there is sufficient evidence in laboratory animals of the risk of cancers due to benzophenone.
In animals, exposure to benzophenone induces liver cancer and lymphomas, note the researchers who also point to dermatological problems.
Increases in benzophenone sometimes reaching 200%
The products purchased have undergone an accelerated aging process validated in the United States, and equivalent to one year spent at room temperature.
Then they were analyzed using a high performance mass spectrometer, says Professor Lebaron.
“Initially, there is very little benzophenone in the products.
But gradually as the product ages, there is more and more benzophenone ”.
"Increases in benzophenone exceeding 100% and even reaching 200% have thus been observed", adds the biologist.
"This is the first time that this degradation of octocrylene into benzophenone has been shown".
One more argument, according to him, to ban it in personal care products.
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Stressing that this substance is easily absorbed through the skin, the researchers believe that products based on octocrylene, and therefore contaminated with benzophenone, can pose a threat to health as well as to the environment.