What is the Preservative Efficacy Test (PET) for Cosmetics

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 August 14, 2019

All personal care products containing organic or inorganic compounds require preservation against microbial contamination.  Microorganisms grow well in water, so products containing water or prone to exposure to water need robust protection to combat growth. Cosmetics are no exception. Manufacturers and brands employ a Preservative Eff time and is required before going to market.

Preservatives ensure consumer safety and increase the products shelf-life by helping inhibit the growth of microorganisms inadvertently introduced into the product during the manufacturing process or during consumer use.  Without preservation, cosmetics containing water, would only last two weeks and microorganism contamination of yeast, mold, bacteria and fungus could cause skin irritation, allergic reactions, infections and more.

During the Preservative Efficacy Test, cosmetic products are exposed to certain microorganisms and then evaluated at different time intervals, typically a minimum of 28 days. Any products that exhibit the growth of microbiological contaminants will be reformulated, usually by adjusting the pH of the product to make it unsuitable for microbes to survive.

How Does a Preservative Efficacy Test Work?

During the Preservative Efficacy Test, cosmetic products are exposed to certain microorganisms and then evaluated at different time intervals, typically a minimum of 28 days. Any products that exhibit the growth of microbiological contaminants will be reformulated, usually by adjusting the pH of the product to make it unsuitable for microbes. 

When selecting the microbes for a PET evaluation, many companies use American Type Culture Collection (ATCC) strains of bacteria and fungi. Studies have shown that the most frequent microorganisms found in cosmetics include: 

 

    • Pseudomonas aeruginosa
    • Klebsiella oxytoca
    • Burkholderia cepacia
    • Staphylococcus aureus
    • Escherichia coli
    • Candida albicans
    • Enterobacter gergoviae
    • Serratia marcescens 

 

Other bacteria, as well as fungi and yeasts, may also be found in cosmetics. 

Types of Preservative Efficacy Testing

The results of a PET challenge are crucial in determining the safety of cosmetic products and ensuring they are suitable for consumer use. All new product formulations must be tested before market launch.

The FDA requires cosmetics should be free of pathogenic microorganism contamination and have a low density of non-pathogenic organisms. However, they do not specify acceptable levels of “low”. As a result, the cosmetic industry generally follows the guidelines of the Personal Care Products Council (PCPC) (formerly the Cosmetic, Toiletry, and Fragrance Association (CTFA)) regarding the level of microbial contamination and the absence of pathogens.

Due to the unique set up and requirements of the Preservative Efficacy Test, cosmetic testing is often conducted in a dedicated laboratory. Several test methods are available to address PET criteria including:

 

  • U.S. Pharmacopeia <51> Antimicrobial Effectiveness Testing
  • European Pharmacopeia
  • International Organization for Standardization (ISO) 
  • Personal Care Products Council (PCPC)  

 

Although they are similar, each one calls out different criteria to ensure product microbiological stability, and in turn, safety. 

In the News: First-Ever Vegan Microbial Limits and Challenge Tests

UK-based microbiological testing laboratory MSL recently developed the first Vegan Society accredited in vitro efficacy test.The new testing solution, VeganSure, replaces animal-derived ingredients with plant or synthetic derivatives. 

Get Help with Preservative Efficacy Testing Needs at Kinetik

At Kinetik, we provide high-quality and natural raw ingredients for your cosmetic products, as well as guidance to help you with all your Preservative Effectiveness Testing needs. 

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Take advantage of our full range of comprehensive services; we’ll provide the education and support you need to navigate through testing, certifications and stay ahead of the competition.

Headquartered in the USA, Kinetik works with clients and represents suppliers worldwide. Contact us at (732) 335-5775 to speak with one of our sales representatives about natural ingredients you need to support your cosmetic formulations today.