Ensuring the microbiological safety of a cosmetic is a regulatory obligation that aims to ensure that products placed on the market meet strict standards, thus avoiding any contamination by microorganisms such as bacteria, fungi or yeasts.
In addition to modifying the sensory properties of the product (texture, smell, color), these contaminations can also be dangerous for the consumer. Indeed, microorganisms produce toxins that can then cause allergic reactions, redness or small pimples. Microorganisms can also infect small wounds on the skin.

Microorganisms grow easily in aqueous media. Most cosmetic products, especially emulsions, contain a high proportion of water and have a pH that is favorable to the growth of microorganisms.

Cosmetics can become contaminated depending on the packaging used and the use made of it. Most of the time the application with the fingers will transport many microorganisms on the opening of the tube or in the pot. Cosmetics are also stored most of the time in the bathroom, a warm and humid environment conducive to the growth of germs.

To avoid these contaminations, aqueous cosmetic products incorporate molecules called preservatives into their formulas, whose role is to prevent the colonization of the cream by microorganisms. 100% oily cosmetics are environments unfavorable to the growth of microorganisms and therefore do not require preservatives.

The antimicrobial effectiveness of preservatives in cosmetics is evaluated by a challenge test. This test consists in voluntarily introducing into the cosmetic product 5 strains of pathogenic microorganisms (3 bacteria, 1 fungus and 1 yeast). After 2, 7, 14 and 28 days, microbiological experts assess whether and in what quantity the introduced microorganisms are still present in the product. At SHIGETA, these tests are carried out by independent laboratories on each new formula during its development, which makes it possible to find the most suitable preservative system for each product.

Each batch of cosmetic product manufactured must also undergo a microbiological test before it is released for sale. This test, called total germ count, ensures that the manufactured batch does not contain any germ that could affect the quality of the product and the health of the consumer.