It is not recommended to use so-called "Brazilian straightening" hair products containing glyoxylic acid, a "potentially toxic" cosmetic ingredient, because they can cause acute renal failure, the authorities warned on Wednesday, who are examining several cases.
The alert was prompted by "four cases of acute renal failure" in people aged 28 to 42, "linked to the use of various hair products containing glyoxylic acid", which were identified in France by the National Agency for Food, Environmental and Occupational Health Safety (ANSES).
Hospitalized, these four people, poisoned between January and August 2024, "recovered following treatment", specifies the agency, which launched an expertise of the renal toxicity, in capillary application, of this chemical substance. Glyoxylic acid has replaced formaldehyde, classified as carcinogenic since 2013.
These cases occurred after applying straightening products in a hair salon.
When glyoxylic acid "passes into the bloodstream through the scalp," it can "transform into calcium oxalate crystals," which will cause kidney damage, Dr. Juliette Bloch, director of health alerts and monitoring at ANSES, explained to AFP.
"It's very likely that other cases have gone under the radar: sometimes the person will go and drink and the crystals will be eliminated, so it will go unnoticed. And even if there was kidney failure diagnosed in the hours that followed, the person may not make the connection," she continued. "The point of our alert is that people think about it."
As a precaution, the General Directorate for Competition, Consumer Affairs and Fraud Control (DGCCRF) and the Ministry of Health (DGS) advise hair salons and individuals not to use these products and cosmetics stores not to sell them, pending the conclusions of the Anses expert report at the end of 2024.
In the event of signs of renal failure – abdominal or lower back pain, nausea and/or vomiting – a few hours after applying a hair product containing glyoxylic acid, you should "consult a doctor quickly or call a poison control centre" mentioning this use, warns Anses.
"About twenty cases have been reported in Israel in recent years, the same thing as what has been observed in France," said Sandrine Charles, cosmetic products project manager at ANSES, "and one in Switzerland."
In June, the Academy of Medicine recommended, in light of scientific articles, to "disseminate warning and information messages to health professionals, hair salons and cosmetic product stores". Insisting on "a health risk that could be underestimated, because it is unknown", it stressed "the importance of not performing hair straightening in the event of scalp lesions, which increases the penetration of glyoxylic acid".
On Wednesday, the trade union of cosmetics manufacturers, Febea, sought to reassure. Despite these "suspicions concerning the toxicity" of glyoxylic acid, "the current elements do not allow definitive conclusions to be drawn and lead to reminding people to follow the instructions for use and precautions for use," it stressed.
Asked by AFP, the industry giant L'Oreal stated that it does not "add glyoxylic acid as an ingredient in any of its products, on any market in the world."
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