1.What are preservatives for?
- We live in a world full of microorganisms. Because lots of ingredients in cosmetics are the essential nutrients for growth&reproduction of microorganisms, and under suitable environment microorganisms will grow and multiply in cosmetics, leading to their deterioration.
- In the production process, if the equipment and environment are not thoroughly disinfected and cleaned, cosmetics will be contaminated by the production of microorganisms.
- Besides, we will cause contamination to cosmetics in use of cosmetics. Based on the situation above, preservatives are vital.
Preservatives are the substances that are used to inhibit or prevent the growth and reproduction of microorganisms and to ensure that cosmetics will not deteriorate before they are expired.
2.Which are preservatives?
Preservatives commonly used in cosmetics can be divided into six categories according to their chemical structure:
1.Formaldehyde donor and Aldehyde derivative preservatives, such as: Imidazolidinyl urea, Formaldehyde type
2.Benzoic acid and its derivatives preservatives: such as: Potassium sorbate, sodium benzoate
3.Monomeric alcohol preservatives, such as: Phenoxyethanol, benzyl alcohol
4.Polyol preservatives, such as: 1,2-Pentanediol
6.Other organic compound preservatives, such as: 2-Bromo-2-nitropropane-1,3 diol
There is a variety of preservatives, for the purpose of safety, the current Safety and Technical Standards for Cosmetics(STSC) stipulates the permitted preservatives that can be used in cosmetics, and specifies the usage and application scope of each preservative in permitted preservative list. Moreover, Only preservatives in the list can be selected to be used in cosmetics.
3.How to choose preservatives?
When in selection of cosmetic preservatives, safe, effective, targeted principles and principles of compatibility with other components in the formula shall be complied with.
Safe: The selected preservatives shall at first comply with the limit requirements of STSC, and meanwhile they shall pass safety-related tests. Besides, reduce the usage of preservatives to reduce the stimulation to skin. The ideal anti-corrosion system shall not only well inhibit the growth of microorganisms but do no harm to skin cells. Excessive preservatives will do certain harm to skin, like allergies.
Effective: Comprehensively and effectively inhibit the growth of microorganisms to guarantee the products have the required shelf life.
Targeted: Establish “tailor made” anti-corrosion system targeting at formulation characteristics and application objective. There is no such thing like almighty preservative so anti-corrosion system shall be designed according to the dosage, function, target users of cosmetics.
Compatibility with other components in the formula: pay attention to the influence the other components have on preservatives and interaction effects between different preservatives. When preservatives are used with various types of surfactants and other components in cosmetics, they should have good mutual solubility and maintain their activity.
Besides, conditions of fine stability(Preservatives shall be stable to temperature, acid and soda), colorless, tasteless, odorless and low cost shall be fulfilled as much as possible.
The picture below is the procedure of a complete anti-corrosion system design:
4.Matters about cosmetic notification and registration
Technical Guidance for the Safety Evaluation of Cosmetics (2021 Edition) clearly states:
- The use ofingredients, risk substances with restricted requirements in the list of restricted components, permitted preservatives, permitted sunscreens, permitted colorants and permitted hair dyes in the “Technical Guidance” should meet the requirements of “Technical Guidance”.
- Children’s cosmetics assessment shall clarify the principles of its formula design, and shall explain the need to use ingredients for the formulation, especially fragrances, colorants, preservatives and surfactants and other ingredients.
- Cosmetic safety assessment reports (full version) require a preservative challenge report.
It’s not necessary to turn pale at the mention of “preservatives”. Cosmetics with preservatives are also very safe as long as they are used in strict compliance with regulations and reasonable use.