ISO 29621 Cosmetics - Microbiology - Guides for the Risk Assessment and Identification of Microbiologically Low Risk Products

The standard “ISO 29621 Cosmetics - Microbiology - Guides for risk assessment and identification of microbiologically low risk products” developed by the International Organization for Standardization (ISO) provides guidance to cosmetic manufacturers and regulatory bodies in identifying finished products that, according to risk assessment, present a low risk of microbial contamination during manufacture or intended use and therefore do not require the application of microbiological international standards for cosmetics.

For the purposes of this standard, the following terms and definitions apply:

• Risk refers to the impact of uncertainty on objectives. Microbiological risk is related to the ability of a product to support the growth of microorganisms and the probability that these microorganisms will cause harm to the user. Or it is related to the ability of a product to support the presence of certain microorganisms as defined in international cosmetic microbiological standards (e.g. ISO 18415, ISO 18416, ISO 22717, ISO 22718 and ISO 21150).
• Risk assessment refers to the overall process of risk identification, risk analysis and risk evaluation.
• Risk analysis refers to the process of understanding the nature of risk and determining the risk level.
• Risk assessment refers to the process of comparing the results of risk analysis with risk criteria to determine whether the risk or its magnitude is acceptable or tolerable.
• Risk criteria refer to the reference term against which the significance of a risk is evaluated.
• A microbiologically low risk product refers to a product whose environment does not meet the physical and chemical requirements of microorganisms for growth or survival. This low risk product category applies to microbiological contamination that may occur during production or intended use by the consumer. A product whose packaging prevents the entry of microorganisms is considered a microbiologically low risk product during use. The inclusion of preservatives or other antimicrobial compounds in a formulation does not, in itself, constitute a low risk product.

When conducting a microbial risk assessment to determine whether a product meets published microbiological standards for cosmetics or other relevant methods, a number of product characteristics need to be evaluated. These characteristics include the composition of the product, manufacturing conditions, packaging and a combination of these factors.

In terms of the composition of the product, products with certain physical and chemical properties do not allow the proliferation of microorganisms of concern for cosmetic products. Any number of physical and chemical factors or combinations of these in a product can create a hostile environment that will not support microbial growth or survival. Combinations of sub-lethal factors increase the hostility of the environment and the lag phase. If the environment is sufficiently hostile, the lag phase will extend indefinitely and therefore cause cell death. Combinations of lethal factors cause rapid cell death. The factors described here should be taken into account in determining whether cosmetic products present a hostile environment.

For example, the water activity of the formulation. Water is one of the most important factors controlling the growth rate of an organism. It is the water present in the formulation, not the total moisture content, that determines the growth potential. The metabolism and growth of microorganisms require the presence of water in some form. The most useful measure of water availability in a product formulation is water activity. Water activity is defined as the ratio of the water vapor pressure of the product to that of pure water at the same temperature.

As a solution becomes more concentrated, the vapor pressure decreases and the water activity decreases from 1,00 (the water activity for pure water). These conditions have been categorized according to their ability to grow and produce metabolites at various conditions and water activity values. The effect of reduced water activity on microorganisms is well documented. As the amount of free water in a formulation decreases (decreased water activity), the microorganism is faced with the challenge of maintaining a turgor state within the cell. Loss of turgor results in slower growth and eventually cell death. Many organisms survive but do not grow under conditions of low water activity. Reduced water activity results in an increase in the lag phase of growth, a decrease in growth, and a decrease in total cell number. At very low water activity values, the lag phase can be assumed to be infinite, i.e., no growth. In low water activity environments, cells must use energy to accumulate compatible solutes to maintain internal pressure. The growth of most bacteria is limited to a water activity above 0,90. Some yeasts and molds can grow at much lower water activity, with a limit value above 0,60. The table titled “Approximate minimum water activity required for growth of selected microorganisms” provided in the standard lists examples of minimum water activity levels required for growth of selected microorganisms.

Depending on the temperature, pH value or nutrient content differences in the product formulation, microbial growth may occur at lower values. Therefore, the water activity values ​​in the table should be taken as a reference point.

Our organization has a strong staff that closely follows the developments in the world in the field of science and technology and constantly improves itself. Among the numerous test, measurement, analysis and evaluation studies provided for businesses in various sectors, there are also testing services in accordance with the standard “ISO 29621 Cosmetics - Microbiology - Guidelines for the risk assessment and identification of microbiologically low risk products”.