Lactic acid is the most widely occurring acid in nature. In the form of lactate it is a normal constituent of the human organism and an important intermediate product of metabolism, for example as a product of the breakdown of sugar through lactic acid fermentation. Lactic acid is present in sweat, muscle blood serum, in the kidney and the gall bladder, and in saliva. It is contained in almost all shampoos, in many cosmetic products, foodstuffs (e.g. pickled cucumbers, pickled cabbage, and sour dough, …). The antiseptic effect of lactate protects the skin against disease-causing agents. The formation and subsequent breakdown of lactic acid in the body following sport is responsible for the familiar feeling of muscle soreness. The highly diluted lactic acid solution which is administered on the body in the Skinial method is broken down (synthesised) automatically and without leaving any residues within 30 minutes of it producing its effects (i.e. the repulsion of the pigment molecules).
Lactic acid is used in a concentration of up to 40 % as a “chemical exfoliating agent”, even in very large quantities of 50 ml or more, on the face and body. Doctors also use concentrations of over 70% to cure acne.
As a rule, dermatologists are barely familiar with the subject of tattoo removal and lactic acid. Unfortunately the few official statements issued by the BfR repeatedly lead to the discrediting of the method of tattoo removal using lactic acid. What even the majority of specialists are barely aware of is that the dermal assessment depends less on the degree of acidity than on the pH value. In the case of the liquid used by Skinial it is over 3, which is comparable with many cosmetic products the safety of which has already been assessed. Coca-Cola for instance has a pH value of 2.3.
The BfR report cited above also mentions a letter written by the Federal Ministry of Food, Agriculture and Consumer Protection in which lactic acid is described as follows:
“… L(+)-lactic acid is an alpha-hydroxy acid which occurs naturally in plants and animals. It arises endogenously in processes of decomposition and through the action of micro-organisms in the gastro-intestinal tract. Lactic acid is also ingested in food. …”
PharmaWIKI writes for example: skin care products are nurturing and hydrating skin care products (salves, creams, lotions), … Some contain moisturising or moisture-retaining substances, such as urea or lactic acid for example. (Source: www.pharmawiki.ch/wiki/Index.php )
The GESTIS materials database of the IFA (Institute for Occupational Safety and Health of the German Social Accident Insurance) explains how lactic acid is naturally absorbed and metabolised in the body:
“… The effectiveness of the metabolism can be explained by the fact that L(+)-M. (lactic acid) is also physiologically formed in the organism and broken down by lactate dehydrogenase. …. metabolism takes place through conversion to L(+)-M. in the liver or through conversion to glucose/glycogen (sugar) … .”
In response to an enquiry from the Skinial company as to how lactic acid should be classified, the North Rhine-Westphalia Centre of Excellence within the Ministry of Employment, Integration and Social Affairs of the federal state of North Rhine-Westphalia answered as follows on 16.11.2011:
“…The pH value of racemate (a mixture of levorotatory and dextrorotatory lactic acid) is stated as pH 2.8 at a temperature of 20° C, u 10g/l. Based on this it cannot be classified as corrosive. …”
In the “Report on the 61st meeting of the Commission / expert group for cosmetics of the Bundesinstitut für gesundheitlichen Verbraucherschutz und Veterinärmedizin (BgVV) [Federal institute for consumer health protection and veterinary medicine] on 30th November 2000 in Berlin, the institute already noted:
“… Merely limiting the concentration and the pH to certain values is consequently not sufficient to allow tolerance of a cosmetic containing AHA to be predicted. Each formulation must be individually investigated with regard to the degree to which it is able to be tolerated. …”
And further on:
“ … When the commission says that high concentrations are potentially hazardous to health and that maximum values are becoming necessary, the commission is contradicting its own assessment made in 1998. The reason for the change in the recommendation regarding alpha-hydroxy acids in cosmetics lies in more recent studies and findings which make a reassessment necessary, and according to which tolerance of the products varied under comparable conditions of use (pH, concentration) with differing reactions occurring depending on the condition of the skin in each case. This circumstance shows that there cannot be any limit value and that decisions must be made on a case by case basis.. …“
Clinical study relating to lactic acid by PRIORI® Advanced AHA Cosmeceuticals: (excerpts from the study)
“… Furthermore, research results have demonstrated that lactic acid triggers the natural healing process and therefore significantly increases the skin’s ability to bind water. The inclusion of these results relating to the Advanced AHA product range incorporating LCA Complex has led to a significant improvement in the effectiveness of the products, which is shown in the good results achieved in domestic use and use at cosmetics institutes. … The body’s own lactic acid is our skin’s natural moisturiser which leads to significantly improved results with fewer occurrences of skin irritation. Moreover, the latest research results show that compared to other fruit acids lactic acid is significantly more effective as regards its reinforcing effect on the hyaluronic acid content of the skin (70-95% more effective than glycolic acid). … In addition, it has recently been demonstrated that the fruit acids increase the moisture content of the skin via a natural wound healing response – since lactic acid constitutes the body’s own fruit acid the results are even clearer. … Hyaluronic acid continues to play an important role in cell differentiation and the migration of cells through a tissue, as happens during wound healing for example. … The natural trigger for the formation of hyaluronic acid by our skin is lactic acid, which also has the most powerful effect in this regard compared to all the other fruit acids, and therefore contributes in a natural manner to healthy and radiant skin.
Lactic acid is therefore the fruit acid of choice for increasing the natural moisture content of the skin – which is especially important in the case of older skin. Furthermore, it has recently been demonstrated that the fruit acids increase the moisture content of the skin via a natural wound healing response – as lactic acid constitutes the body’s own fruit acid, the results are even clearer.”
7. A Safety Assessment relating to the use of 30%-concentration lactic acid in cosmetic applications (CIR Compendium 2011) established among other things that the incidence of skin irritation is very low when 30% lactic acid is used, but that there may sometimes be increased UV-sensitivity (according to one of two studies).
“ … Likewise, rinse-off uses with concentrations no greater than 30% and a pH no less than 3.0 are considered to present an acceptable irritation risk if applied in a brief, discontinuous fashion followed by thorough rinsing by trained individuals. … Sun Sensitivity – Limited data assessing the effects on MED show that the MED was increased in one study and reduced in another by AHA application. … The Expert Panel expanded on the meaning of daily use of sun protection to include the American Academy of Dermatology (AAD) recommendations. The AAD recommends avoiding the sun between the peak hours of 10:00 am and 4:00 pm, using a sunscreen with an SPF of 15 or greater and wearing protective clothing and hats. …”