Star of smoothing care since the early 2000s, Brazilian straightening has many followers with rebellious hair. If its disciplining effects are bluffing, we now know that this treatment is not completely harmless … What does it contain? What are the risks for the hair but also for the health?

Brazilian straightening is a professional hair care technique, which as its name suggests comes straight from Brazil. Also called keratin smoothing, it consists of injecting a liquid based on concentrated keratin inside the hair, after having previously opened the scales. Then, these scales are closed during the smoothing step with heating plates. The keratin used in Brazilian smoothing can be obtained from proteins of vegetable origin (soybean or wheat) or animal (from feathers, horns, hooves). , hairs of many animals). After this treatment, the hair is both smoother but also more flexible, shinier, stronger and more disciplined, hence its success.

Brazilian straightening takes place in 3 steps:

• last step: the hair is straightened strand by strand using heating plates at 230 ° C, which also makes it possible to close the scales and to coat the hair. This treatment can last between 2:30 and 5 hours depending on the thickness and length of the hair;
• first of all, the hair is carefully washed using a so-called clarifying shampoo, at basic pH, which opens the scales in order to prepare it to receive the keratin-based treatment;
• then, the smoothing product is applied to damp hair, strand by strand, without touching the root and is distributed uniformly over the entire length of the hair. The product must sit and act for ¼ of an hour under the heating cap, before drying the hair.

The product used for Brazilian straightening contains – in addition to the keratin which makes it successful – formalin, also known as formaldehyde. It is he who is responsible for the smoothing effect of the treatment but it is also he who arouses controversy. Formalin could indeed in the long term cause an alteration of the hair sheath and an increase in hair loss.

Another concern: the last step, which consists of straightening the hair with heating plates that reach a temperature of 230 degrees Celsius, can be damaging for fine, fragile, colored or bleached hair.

Moreover, depending on the hairdressing salons, the mixture used in Brazilian straightening may contain silicone and / or paraffin. These two occlusive substances give the hair a false impression of health, but in practice suffocate it and reduce its shine.

Finally, after Brazilian straightening, it is imperative to use sulfate-free shampoos in order to guarantee the longevity of the smoothing, but also and above all to preserve the quality of the hair.

Problem: if this post-treatment step is neglected – which often happens because these products are rarer but also more expensive – the risk is to further weaken the hair which risks becoming more brittle, drier and falling more.

Besides the problem of repeated Brazilian straightening on hair quality, another is much more serious: the effects of formaldehyde on health.

The formalin contained in Brazilian straightening products has been classified since 2005 by the WHO as a carcinogenic and dangerous substance. According to the Brazilian Health Security Agency (ANVISA), the risks associated with the use of formalin are very real and can range from a skin allergy, to respiratory disorders through an increased risk of throat cancer in patients. hairdressers on display. For these reasons, the keratin used for smoothing should not 0,2% formaldehyde.

In practice, this rate is often not respected and some products contain much more.

A German study carried out in 2013 notably analyzed several Brazilian straightening products, and revealed that the majority of them contained formaldehyde contents of on average 1,46% and up to 5,83%! Rates considerably higher than health recommendations.

Due to the formalin it contains, often in excess of European standards, Brazilian smoothing is strongly discouraged for pregnant women. This carcinogenic substance is indeed suspected, in high doses, of causing fetal malformations.

No Brazilian smoothing for children either, whose less mature respiratory system makes them more sensitive to toxic substances.

People with asthma and allergies should also avoid this type of care on a regular basis.