Cosmetics are non-sterile products that may include a small number of different kinds of bacteria. The microorganisms may proliferate, leading to physicochemical alterations and ultimately a decline in the stability and activity of the product. Regarding the microbiological safety and quality of their products, cosmetic manufacturers have an obligation to make sure that they are manufactured in a sanitary environment. It is not envisaged that cosmetics will be sterile. However, they shouldn’t include any microorganisms or excessive numbers of them that could compromise the safety of the product or its quality for consumers. Furthermore, producers can choose not to test if they can guarantee that their goods meet this criterion, and some cosmetics that are thought to have little microbiological risk may not require routine microbiological testing.

The manufacturer should follow the Good Manufacturing Practices described in ISO 22716 and take the necessary precautions to limit the introduction of microorganisms from raw materials, processing and packaging. When necessary, microbiological testing may be performed using ISO 21148, ISO 21149, ISO 16212, ISO 18415, ISO 18416, ISO 21150, ISO 22717, and ISO 22718.

Cosmetics, the ingredients they are made of, and the manufacturing processes they go through don’t have to be sterile. Yet, it is appropriate that the microorganisms in a product do not negatively impact on the product’s quality or consumer safety as part of its intended or predictable use. For completed cosmetic items, quantitative and/or qualitative microbiological limits are thus set.

• Microbiological requirements for cosmetics

Standard requirements of United States Pharmacopeia (USP) edition 42, ISO 17516:2014 and the Thai Herbal Pharmacopoeia (THP) 2019 for microbiological investigations in non-sterile products are quite similar in quantitative and qualitative aspects.
The determination of microbial limits in cosmetic products: ISO defines it as the total count of bacteria, yeast, and mold combined, while USP and THP separate bacteria from yeast and mold. The USP quantitative limits specify that the total count of aerobic bacteria and the total count of yeast and mold should be ≤1 x 10² and ≤1 x 10¹ cfu/g(mL), respectively. The maximum acceptable limit is twice the amount, making it equivalent to THP requirements, which states that the total count of aerobic bacteria and the total count of yeast and mold should be ≤2 x 10² cfu/g(mL) and ≤2 x 10¹ cfu/g(mL) of the product, respectively.
The requirements of USP and THP are therefore stricter than those of ISO, which specifies that the total number of microorganisms, including aerobic yeast and mold must be ≤1 x 103 cfu/g(mL) of the product. However, for cosmetics used around the eyes, mucous membranes, and for children under 3 years old, ISO has stricter requirements, which state that the total number of aerobic bacteria, yeast, and mold must be ≤1 x 102 cfu/g(mL).

• Standards by Ministry of Public Health

According to the announcement from the Ministry of Public Health B.E. 2559 Regarding the specifications of cosmetics that are prohibited from being produced, imported, or sold, there are regulations concerning microorganisms, including,
1. Pathogenic microorganisms shall not be found, including P. aeruginosa, S. aureus, C. albicans, and Clostridium spp. (specified on herbal cosmetics). According to the ISO requirements, E. coli must also be tested.
2. Cosmetics used around the eyes, cosmetics contact with mucous membranes, and cosmetics for children under 3 years old: total aerobic plate count of bacteria, yeast, and mold shall not exceed 500 cfu/g(mL). Other cosmetics: total aerobic plate count of bacteria, yeast, and mold shall not exceed 1,000 cfu/g(mL)
3. Methods for testing microorganisms according to 1. and 2. Are according to ISO or USP or methods complied with other international standards.

• ISO 17516

ISO 17516:2014 is applicable for all cosmetics, and it assists interested parties in assessing the microbiological quality of products. The standard details that cosmetic products should not contain excessive amounts of microorganisms nor specified microorganisms that have the potential to adversely affect the product quality or consumer safety. As such, every cosmetic manufacturer should have a responsibility relative to the microbiological safety and quality of its products to ensure that they have been produced under hygienic conditions. ISO 17516:2014 specifies that some cosmetic products considered to have low microbiological risk may not need to be subjected to routine microbiological testing. Manufacturers can decide not to test if they can ensure products meet this standard.

• ISO 18415

ISO 18415: 2017 standard describes a test method to identify the presence of any specified microorganisms and anaerobic mesophilic non-specified microorganisms in cosmetic products. ISO 18415 outlines guidelines for microbiological risk analysis specifically for Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, and Candida albicans. ISO 18415 test involves the detection of microbial growth in a non-selective liquid medium (enrichment broth) suitable to detect microbial contamination. This is further followed by isolation of microorganisms on non-selective agar media.
To perform the test, cosmetic product samples are diluted in enrichment broth to prepare for the initial suspension.
1. Water-miscible products – 1 mL of product sample is diluted in 9 mL of enrichment broth.
2. Water-immiscible products – Product sample is mixed with a dispersing agent (e.g. polysorbate 80) and then added to the enrichment broth.
3. Filterable products – Product sample is transferred onto the membrane in a filtration apparatus. After filtration, the membrane is washed using water or diluent. This membrane is transferred into enrichment broth to make initial suspension.

• ISO 22716 Cosmetics-Good Manufacturing Practices (GMP)

ISO 22716:2007 is a standard for Good Manufacturing Practices (GMP) guidelines in the production of cosmetics. The guidelines for this standard have been approved and accepted by international regulatory bodies such as members of the International Cooperation on Cosmetics Regulation (ICCR), the Food and Drug Administration (FDA), and the European Committee for Standardization (CEN). ISO 22716 focuses on the production, control, storage, and transportation of cosmetic products. These guidelines provide organizational and practical recommendations on managing human, technical, and administrative factors that affect product quality.
ISO 22716 provides guidelines for a management system for the documentation and oversight of production, control, storage, and transportation of cosmetic products. The standard guidelines will help organizations implement practices to manage various factors that may affect product quality.

• ASEAN Cosmetic GMP

The Thai Food and Drug Administration (FDA) announced a notification regarding compliance with the ASEAN Cosmetic Good Manufacturing Practice (ASEAN Cosmetic GMP), which came into effect on January 1, 2008. This replaces the GMP system for Thai cosmetic manufacturers. Particularly, manufacturers looking to expand their market to ASEAN must apply for certification in accordance with the legal guidelines. This is a part of the cooperation agreement between ASEAN, which establishes a uniform standard for good manufacturing practices for cosmetics.
ASEAN Cosmetic GMP aligns with the ISO 9001 quality management system. This standard continues to emphasize the structure of production buildings, facilities, raw materials, production equipment, and personnel to reduce contamination from potential sources. Another important requirement is that raw materials and production formulas must be approved before production and distribution, ensuring the safety of the raw materials.