Standard preservative challenge test methods used for determining the preservative effectiveness of water-based products are not suitable for certain product formulations such as wax or oil based products, powders, lip balms, etc. For these types of products it is important to use methods that do not change the physical dynamics of the formula in order to accurately predict their microbial stability.
It is important in preservative challenge testing to consider the typical use of the finished product and to test them in their finished state. For example, nonwoven substrates such as presaturated wipes or towelettes, should be tested in the wipe form and not on just the add-on solution. The CTFA M-5 guidelines are designed for personal care products such as wipes or towelettes that contain aqueous-based add-on solutions.
A summary of the CTFA M-5 method is described below:
Preservative challenge testing for eye area cosmetics is extremely important to ensure the safety of your consumers. The eyes are a common area for infection by microorganisms such as Pseudomonas species that can be found in cosmetics that are not properly preserved. CTFA M-4 is a guideline for preservative challenge testing of eye area cosmetics.
A summary of the CTFA M-4 method is described below:
Once it has been determined that products are free from harmful microorganisms, it is important to ensure that they remain free from contamination during manufacturing consumer use. That is accomplished through challenge testing the formula with known microorganisms to verify that if the products become contaminated, the preservative system is sufficient to inhibit the growth of the microorganisms and spoilage.
The next step in determining the safety of cosmetic and personal care products is to determine if any microorganisms that may be present are "objectionable" microorganisms that may be harmful to the consumer.
It is every cosmetic manufacturers' responsibility to ensure the microbiological safety of their products. The first step in microbiological safety testing is to verify that each cosmetic product is free from contamination that could affect the quality of the product or consumer health.
A summary of the CTFA M-6 method is described below:
Yeast and molds are types of fungal cells that can cause various degrees of deterioration and decomposition of cosmetics and personal care products. Since yeast and molds are ubiquitous (occuring everywhere) in nature just as bacteria are, cosmetics and personal care products are just as susceptible to fungal contamination as they are to bacterial contamination.
The Ocular Irritation Test, much like the Dermal Irritation Test, uses a 3-dimensional model of eye tissue to determine the potential of a cosmetic product or ingredient to cause eye irritation when used by the consumer. Just as some cosmetic products can cause irritation to the skin, they can cause similar effects to the eye area.