The purpose of stability testing or cosmetics regulatory tests is to make sure that a modified or new cosmetic product meets the required chemical, physical and microbiological quality standards along with the aesthetics and functionality when the products are stored under appropriate conditions. Since the development process of cosmetic products is short, it is the duty of each manufacturer to design their own stability testing program. Because of the broad variety of product standard, cosmetics regulatory tests are not prescribed. Manufacturers need flexibility to modify their testing protocols and to build a strong scientific base for cosmetic regulation of their own products. That is why, specific tests have to be developed to address either unusual or new technologies, or to adapt to products that have extended shelf lives. These cosmetics regulatory tests can either be done in real time or on under accelerated conditions and these tests must check the stability of a product that is under appropriate conditions for transport, storage, and for use.
There are basically, three types of stability tests namely;
- Chemical or physical stability tests (evaluates color, fragrance, viscosity, pH value, flow, texture, and emulsion stability of the product)
- Microbiological stability tests (evaluates the degree of contamination in the products with pathogens like, bacteria, yeast and mold)
- Packaging stability tests (accesses the impact of packaging on the contained cosmetic products)
Chemical or physical stability tests
This kind of stability testing, describes and predicts how well cosmetics will be able withstand common stresses like, extreme temperature and light. Normally, manufacturers determine whether to conduct such type of specialized testing based on the vulnerabilities of a particular product and its anticipated storage, shipping, display and use conditions.
Microbiological stability tests
Microbiological contamination, normally occurs during manufacturing and filling, and also during the use of the product by a consumer. From the moment the cosmetic is opened by a consumer, there is a permanent microbial contamination of the cosmetic which is usually caused by contact with the consumer’s body (hands). Microbial preservation of cosmetics products is important as it ensures the microbial safety of the product for the consumer, and it confirms the hygienic quality. Though there has only been a small number of reported cases of microbial infections by consumers, but microbial contamination of cosmetics can spoil them or significantly reduce the intended quality of the product. Therefore, it is essential that manufacturers carry out a microbiological analysis of each batch of their finished cosmetic products coming on the market. The potential contaminants include, Staphylococcus Aureus, Pseudomonas aeruginosa and Candida Alibcans. These pathogens must not be detected in 0.1 ml or 0.1 g of a cosmetic product. All parameters examined, methods and criteria used, obtained results per batch should be recorded.
Packaging stability tests
This kind of cosmetics regulatory test can directly affect a finished product’s stability because of certain interactions that can occur between the cosmetic product, the external environment and the package. For example, a product’s constituents can be absorbed into a container or can react chemically with the container. Additionally, the container might not fully protect the product from the effects of water vapor and atmospheric oxygen, or volatile product constituents.