Control of the Protective Effectiveness
All cosmetic products are prone to be contaminated by the microorganisms. The growth of bacteria, yeast and fungi is dependent on the constituents of the formulation which provides a feeding environment for those organisms, storage temperature and the used protectors. Products which do not include any water such as mineral oils, eye shadows and powders might contaminate in re-uses.

However, since there is no water, they do not show an increasing effect in terms of the organism growth. The protectors used in the cosmetic preparations are added to the formulation to prevent the growth in the aqueous environment and to decrease the resistance of the organism in the dry environment.

Cosmetic products are not generally sterile preparations. They are prepared from non-sterile raw materials and they are not sterilized during the production. Also, those preparation are presented in packages which are suitable for reuse and easy for the microorganisms to penetrate.

Contamination might be seen with the pathogenic and non-pathogenic bacteria. While pathogen bacteria such as Pseudomonas aeruginosa and Staphyloccocus aureus cause harm in the consumer health, the non-pathogenic bacteria lead to significant degradation in the preparation quality.

Protective effectiveness tests reserves an important place in the safety and acceptance of the cosmetic products by the consumer. Those tests are made to find the right protective type and its effective concentration necessary to be used in the product. When very little amount of protector is used, microorganism growth can be seen leading to differences in the features (color, fragrance, viscosity and so on) of the preparation or harm in the user. When it is used too much, irritation (redness, burning, itching and so on) on the skin disturbing the user might occur and the price of the product increases. Due to all those reasons, the protector effectiveness tests are necessary for the fact that price of the product should not be more than necessary, besides the determination of the concentration which the product can be safely used.