How Do I Choose The Right Preservatives For My Cosmetic Formulation?

The preservation of a product is not only a chemical issue, but also a technical and user-related one.

According to the COSING (Cosmetics Ingredients) database, there are 209 preservatives under observation in the EU. I say under observation because these substances are constantly being tested for allergic reactions. Of these substances, 60 are approved and can be used in certain quantities.

To select a system that will store the product for an appropriate period of time, we need to ask ourselves the following questions:

- What type of product is it intended for,

- Who is it intended for,

- Is the formula natural?

An example of these criteria:

It depends on what form we are developing: whether the product is washable or not. Different dosages are permitted for each category.

For example, if a cosmetic product is made for babies, only small amounts of preservatives with low irritant potential should be used. There is no explicit regulation, but with responsible research it is appropriate to exclude a whole range of preservatives from use (e.g. benzyl alcohol, phenoxyethanol). Babies should not come into contact with chemicals on their skin too early.

When it comes to eye care, it also depends on which substance comes into contact with the sensitive eye area. There are exceptions here too. The substances Biphenyl-2-ol (Phenylphenol) and Thimerosal, for instance, should be specifically avoided and are no longer permitted. Thankfully, I do not observe examples of these in European products, which is fortunate.

Natural formulas

In natural formulas, it is advisable to use only certified preservatives, as well as plant substances that have an enhancing effect on preservation. It's encouraging to note that there are now many options available in this category. Substances that have been long utilized in the food industry are beginning to gain favor, including Sodium Benzoate, Potassium Sorbate, Dehydroacetic Acid, Phenethyl Alcohol. Although we are discussing substances permitted in natural products, it's important to note that they may have allergenic potential. Therefore, individuals who are sensitive to these substances should steer clear of products preserved with them.

It's crucial to remember that just because a preservative is natural does not imply it is harmless; it may still pose a risk to 1% of the population.

Among the formulation criteria, solubility plays a key role, determining whether the preservative dissolves more readily in water or in fat.

Perhaps the most critical factor to consider is the pH level, which is significant not only for the quality of the end product but also for the efficacy of the preservative. In the raw material market, there are preservatives available that are effective within various pH ranges. However, the majority of them retain their microbicidal and fungicidal, neutralizing properties within a pH range of 3.5 to 7.5.

It's important to note that the concentration of preservatives in formulas typically does not exceed 1%. This implies that a maximum of about 0.01% comes into contact with our skin with each application, and only a fraction of this amount is actually absorbed into the skin. However, to ensure that the product remains stable on the shelves and retains its original form even after purchase, the inclusion of reliably acting preservatives is crucial. Dermatological literature abounds with increasingly alarming examples of individuals coming into contact with contaminated, spoiled products. This is particularly vital for products with a higher water content, which encompasses approximately 75-80% of cosmetic products. In these cases, preventing the proliferation of microbes and molds is essential to maintain product safety and integrity.

"The active ingredients employed, particularly water-soluble plant extracts, Retinol variants, and peptides, are also preserved. This is the reason why a formula often contains more than three or four preservatives.

Although microbiological purity is rigorously monitored throughout the manufacturing process, it's important to recognize that the product can be exposed to millions of mold spores or microbes at any moment, even though a mere speck of dust. This explains the need for such stringent precautions.

As users, we can contribute to maintaining the product's cleanliness during use: ensure it is not left unsealed in a damp environment, and avoid contact with unclean hands.

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