Be careful when using highly concentrated fruit acid preparations yourself. Possible consequences could include skin irritation, severe sunburn and eye damage.
Exfoliation is a cosmetic or dermatological procedure that removes the dead cells of the outermost layers of the epidermis, depending on the form used and its concentration. This should stimulate the building of new cells and make the skin look younger and smoother. We differentiate between mechanical and chemical peels, as well as between how deep the exfoliation penetrates: superficial, mid-level or deep.
Mechanical exfoliation is the removal of skin cells of the outermost epidermis using abrasives. This leads to a light reddening and irritation of the skin, which usually disappears very soon afterwards. Abrasives used include fine quartz sand, ground fruit stones (apricot) and even solid plastics (polyurethan) or water-soluble salts (NaCl).
Chemical peels use chemical stimuli to remove the outermost skin layer. Various chemical acids, such as Vitamin A acid, trichloroacetic acid, phenolic compounds and fruit acids, are used, depending on how deep the exfoliation should go. Fruit acids are mainly hydroxycarbon acids found in fruit, mostly α-hydroxy acids (AHA) such as malic acid, citric acid, fumaric acid, gluconic acid, glycolic acid, mandelic acid, lactic acid, oxalic acid, salicylic acid, α-hydroxycaprylic acid and tartaric acid.
Recommendations on the Use of Fruit Acids
Vitamin A acid (retinoic acid) is used as pharmaceutical agent in the treatment of acne and hyperkeratosis and is forbidden for use in cosmetic products.
The Cosmetic Ingredients Review (CIR) evaluated the safety of lactic acid and glycolic acid in 1997. The panel concluded that products for general use containing up to 10 % fruit acid (lactic or glycolic acid) at a pH value higher than 3.5 can be considered as safe. However, it must be ensured that the level of sun sensitivity may not be increased. Alternatively, instructions should be added that include information on daily sun protection. The panel concluded that professionals can use products with a threshold of 30 % at a pH value higher than 3.0
The former EU scientific committee (SCCNFP) evaluated α-hydroxy acids and, thus, glycolic and lactic acids in its position paper. It states that the content of lactic acid in cosmetic products should not exceed 2.5 % and no more than 4 % for glycolic acid at a pH value of 5 and pH value of 3.8 respectively, taking all precautions into account. Additionally, warnings should ensure the avoidance of direct contact with the eyes and that UV exposure is kept at a minimum during the treatment (until the skin layers have regenerated).
In essence, the safety of these products depends on their pH value and fruit acid levels. Highly concentrated fruit acid preparations could have pH values below 1, which would explain their strong skin irritating and corrosive properties. Moreover, it is essential whether trained professionals, such as beauticians or dermatologists, apply these products or not. Professionals are aware of the dangers and will keep an eye on the time and area of exposure, in particular. However, exfoliation treatments carried out by professionals tend to be more expensive, making self-application at home ever more popular. As a result, more and more products that could pose a health risk due to their ingredients and inadequate labelling are sold by dubious sources over the internet.
Attention: α-hydroxy acids may increase sensitivity to UV light and cause skin irritation. Both lactic and glycolic acid have a highly skin irritating and even corrosive effect at high concentration levels (ca. 70 %). If such products get in contact with the eyes, serious eye damage may occur.
Highly concentrated fruit acid peels should stay in the hands of trained professionals, given the potential dangers. Low-dosage fruit acid preparations should provide at least some information on the dangers, using the appropriate warnings and instructions.