Alum stone: the false good idea in terms of natural deodorant?

Ecolo from the first hour, new converts to natural cosmetics or consumers worried about the presence of industrial aluminum salts in traditional deodorants, many are turning to stone alum in a quest for more care products healthy. Yet aluminum, recognized as toxic by scientists, is naturally present. Is it harmful? How to use it? Is it suitable for all skins? The Express Styles takes stock.

What is a natural alum stone ?

Known and used since antiquity, natural alum stone is present in many parts of the world, including Asia Minor and South America. It is a double sulfate of aluminum and potassium (Potassium Alum) which is in the form of a more or less transparent ore and has astringent and haemostatic virtues.

There is also a restored version. This so-called synthetic alum stone consists of aluminum and ammonium sulphate. It comes from the chemical industry. Its label mentions Ammonium alum. In recent years, the latter is sometimes integrated into the formula of some deodorants spray, stick or ball called “alum stone”.

An effective and economical antiperspirant …

This natural stone is an antiperspirant, that is to say that it blocks the sweat glands or sweat by a mechanical effect and limits perspiration while the deodorant can only mask the odors.

After humidifying it, it is used directly on clean and dry underarms. It does not stain clothing and remains effective until 24h. Sold in drugstore and organic store, it costs between 5 and 10 euros and can last several years, depending on the frequency of use.

Basically, I did not choose it for ecological reasons. I was looking for a deodorant product that is easy to use and convenient to carry, even by plane. She is perfect for that. In addition, it avoids any smell of perspiration. I myself am surprised at its efficiency, even with high temperatures! Says Coralie, a blogger on ChokoMag.

… that is not necessarily suitable for all skin types

Relatively well tolerated in the majority of cases, it can however be the cause of redness on sensitive skin. “There are patients who consult for irritation accompanied by itching in the armpits. This results in oozing patches or not, sometimes with small scabs, “says dermatologist Dr. Nina Ross. An experience lived by Elodie, who testifies on her blog My beauty aside: “After a good month and a half of daily use, my armpits began to itch me. At first, I did not really pay attention even if it was more or less uncomfortable. Until I noticed, one evening, that the latter – as soft as sandpaper – had actually covered with thin red and rough patches. “

Regarding the appearance of symptoms, there is no rule: they can occur after several days or weeks. It is better then to stop using the stone and apply a soothing cream based on copper and zinc. The redness usually fades within two days. “Deodorants are then preferred in the form of spray or stick without aluminum salts or possibly with, for example, an important appointment. Aluminum salts are effective for excessive sweating and are not dangerous if they are used punctually, “says the professional.

Aluminum salts: the toxic alum stone?

Beyond certain intolerances, it is especially the question of aluminum, constituting the stone of alum, and its toxic potential, which makes debate.

On its website, Osma, the last French manufacturer of natural alum stones, whose activity dates back to 1957, focuses on transparency: “(…) we have never hidden the presence of aluminum sulphate in stone of natural alum “. Concerning its possible harmfulness, the manufacturer wants reassuring, study carried out internally in support:

“We are (…) assured of having an aluminum content at the time of application of the wet stone on the skin below the threshold of 0.6% recommended (note: according to the recommendations of the ANSM, according to report on the toxicity of aluminum in cosmetics dated 2011). “And adding:” The negative ionic charge of potassium alum and its particular molecular structure means that it can not be absorbed by the cells of the skin, which makes it absolutely harmless, unlike other components. of aluminum sometimes used in the usual antiperspirants. “

Allegations that fail to convince scientists even if, to date, no study devoted to the stone of alum that would assert or deny its toxic risk, has been made. However, “From a purely chemical point of view, explains Professor Roger Deloncle, chemist and pharmacologist toxicologist, when the skin is wet, aluminum chlorohydrate (found in antiperspirants from industry ), like alums, turn into aluminum hydroxide, clogging the pores to block perspiration. But lactate, one of the components of sweat, can dissolve some of the aluminum hydroxide allowing it to cross the skin barrier. In summary, if an antiperspirant is used with aluminum chlorohydrate or alum stone, the aluminum is likely to pass through the skin. “

In this regard, Professor Alain Pineau and Dr. Olivier Guillard have been working on aluminum for more than 30 years and have scientifically proven the passage through the cutaneous barrier of aluminum chlorohydrate, present in the majority of antiperspirants. As a precautionary measure, in 2011, the National Agency for the Safety of Medicines and Health Products (ANSM), for its part said that “antiperspirants or deodorants (containing aluminum) should not be used after the shaving or in case of micro-cut skin lesions. “

What health risks?

“In small quantities, aluminum is eliminated by the body but if you have kidneys that do not work properly, it can become toxic, especially in the brain,” says Dr. Olivier Guillard. There is also a risk in the mammary gland according to Professor AndrĂ©-Pascal Sappino, oncologist: “Exposed in vitro to a dose of aluminum salts corresponding to a daily application of deodorant, normal mammary cells develop abnormalities similar to those observed at the beginning of the malignancy. This is the case even with a quantity of aluminum lower than the 0.6% recommended by the ANSM. A study by two Swiss researchers confirmed doubts about the impact of aluminum salts on the body and their direct link to breast cancer. They also recalled that 80% of tumors are formed in the armpit.

For Dr. Guillard, logically “these results also apply to the alum stone that contains aluminum”. And to emphasize: “It is not because it is found in nature that it is safe. Hemlock is a pretty flower but it is no less dangerous. “

For her part, Dr. Nina Roos wants to be more measured: “The impact of alum stone on the body is still minimal compared to the aluminum that we ingest daily – aluminum is already omnipresent in our environment: cans, baby milks, food cans and many other products … – Moreover, we must be careful not to want to replace it with any other component. Parabens have been dethroned by methylisothiazolinone, which turns out to be a rather allergenic preservative and for which there is really no recoil. “

Case study: how do you know if a deodorant contains aluminum?

It is not always easy to decipher the composition of cosmetics. However, if we want to avoid aluminum, Professor Roger Deloncle indicates that products with the composition mentioning: aluminum chlorohydrate, aluminum salts, potassium alum, ammonium alum or any ingredient of which the name starts with alum. Applying one of them to the armpits, we have aluminum on our skin. The assertion that it is different types of aluminum and that one would be more harmful to the body than the other is not scientific. In any case, it is always the same chemical form: the aluminum ion. “

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