Challenge Test

Challenge test or Preservative Efficacy Test (PET)

According to standards, every cosmetic manufacturer has to ensure that the product, as purchased, is free from the numbers and types of microorganisms that could affect product quality and consumer health, as well as to ensure that microorganisms introduced during normal product use will not adversely affect the quality or safety of the product.

We can assess the robustness of your product against microbial contamination and prove microbiological stability by performing a cosmetic challenge test on your product.

Basically, the challenge test checks how effective the preservative system of the cosmetic product is and whether it is capable of withstanding various types of contamination during production, from the environment and from direct contact with the human body that the cosmetic product is exposed to, thereby guaranteeing the safety and efficacy of the product during its shelf life.

Applied standard:

  • ISO 11930
  • USP<51>

The test is based on the monitoring of the presence of various pathogens in the cosmetic product when it is produced, followed by the intentional inoculation of a cosmetic product with five different strains of microorganisms:

Staphylococcus aureus (gram-positive bacterium)

Pseudomonas aeruginosa (gram-negative bacterium)

Escherichia coli (gram-negative bacterium)

Candida albicans (fungus)

Aspergillus brasiliensis (fungus)

The remaining concentration of these microorganisms is then determined after 7, 14 and 28 days. The product is considered to pass the preservative efficacy test if the concentrations of the fungi do not increase over the testing period and if the concentrations of the bacteria are reduced sufficiently by day 14 and do not increase from that time until the end of the test.

Method process:

Incubation Period

Day 0

  • Inoculation of cosmetic product with the 5 different strains of microorganisms
  • Determination of the initial concentration of microorganisms in the#19346F product

Incubation Period

Day 7

• First plate count to determine the number of microorganisms present

• Calculation of the change Log value at day 7

Incubation Period

Day 14

• Second plate count to determine the number of microorganisms

present

• Calculation of the change Log value at day 14

Day 28

•Third plate count to determine the number of microorganisms present

•Calculation of the change Log value at day 28