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Microbial Contamination of Cosmetics

According to the law, cosmetic products and ingredients do not need to be approved by the FDA prior to going to market. However, these products must be considered safe for consumer use, making manufactures legally responsible for the products they sell. This includes screening products for microbial spoilage organisms, as well as potential harmful pathogens that are known to cause eye and skin infections. Manufactures who do not comply with the law, may be subject to FDA enforcement. Click here to learn more about FDA authority over cosmetics.

How do microorganisms get into our cosmetics?


There are a variety of potential contamination points

  • Contaminated raw ingredients or water

  • Poor manufacturing processing conditions

  • Lack of effective preservative conditions and favorable environmental growth conditions

  • Ineffective packaging conditions 

  • Poor shipping or storage conditions

  • Consumer use, natural microbes from your skin getting into the product through repetitive handling and finger dipping

Cosmetic Products

Cosmetic do not have to be sterile, but they do have to be free of harmful pathogens and the number of aerobic microorganisms (bacteria and fungus) per gram must be low, as they can chemical alter the product in ways that can be harmful to the user. Here at Twin Arbor Labs we can screen your product for the FDA recommended microbial contaminates to ensure your product is safe for consumer use. Please see the list below for our microbial cosmetic test services.

Spoilage microorganism screen:

  • Total aerobic bacterial plate count (APC)

  • Total yeast and mold plate count (TYM)

  • Anaerobic plate count (ANPC) - only for talcs and powders


Pathogen screen:

  • Enterobacteriaceae 

    • Screens for Gram-negative bacteria including Escherichia coli, Klebsiella, Salmonella, Shigella and Yersinia pestis)
  • Psuedomonas aregunoisa

  • Staphylococcus aureus

  • Candida albicans

USP 51: Preservative efficacy challenge test (28 days):

To ensure the stability and effectiveness of cosmetic preservatives in inhibiting microbial contamination, the product is challenged with 5 organisms including bacteria, yeast, and mold. The product is then tested at day (0, 7, 14, and 28) to evaluate the log reduction of these microorganism. If the product fails to meet USP 51 standards, then a reformulation may be required to ensure consumer safety. 

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