The following post is a Guest post by Guest blogger Benjamin Tanner, founder of Cosmetic Test Labs.
As a microbiologist, I get the many questions from people just starting out with their own cosmetic line. Everybody wants to know the same things:
• How do I meet national standards for microbiological testing?
• What specific tests is used to tell if my products contain germs?
• What test is used to tell if my cosmetic might spoil/get contaminated later on?
I like to help people understand the terminology and rules of cosmetic microbiology and conduct testing as needed. This post covers – at a basic level – the rules for cosmetic microbiological testing and the names of the tests that are frequently performed.
In the United States, cosmetics are regulated by the Food and Drug Administration (FDA). FDA prohibits sale of any cosmetic which is “adulterated,” “contains filth,” or is “injurious to users.” This means that levels of bacteria and fungi must be demonstrated to be low right after manufacturing, and must stay low throughout the life of the product. The general rule is that less than 100 bacteria or fungi should be present at any given time in a cosmetic product, or less than 10 if it is an eye-area cosmetic.
To prove a product is free from microbial contamination after manufacturing, manufacturers perform a test called an Aerobic Plate Count or APC. The APC test is like a snapshot that tells the manufacturer how many germs are present at that time. Germ levels in cosmetics can and do change over time. Most manufacturers do APC tests, separately, for bacteria and fungi on at least one sample from each batch of production.
APC tests are straightforward and relatively easy to conduct. To perform an APC test, the laboratory removes a small amount of the product from its packaging, mixes it with a solution intended to knock out the effect of the preservative, then puts it onto agar plates. The agar plates are incubated for 2-5 days, then the number of colonies are counted and reported to the cosmetic manufacturer.
Since normal manufacturing and handling introduces germs into cosmetics, every liquid cosmetic product should contain a preservative, or else it will almost certainly spoil or become contaminated with dangerous bacteria and fungi. In just 1 day, 100 bacteria can turn into 100 million! Different formulas interact differently with different preservatives, so to ensure preservative function, manufacturers perform a test called a “preservative challenge study” or “preservative effectiveness study.” This is sometimes abbreviated as PET.
The challenge test or PET requires more skill than an APC and a more specialized laboratory. Simply put, the lab grows pure cultures of 5 different germs, inoculates them into the product, then makes sure they die off – rather than grow – over time.
Whether you rely on a private label manufacturer or make your own cosmetics, it is your company’s responsibility to ensure that germ levels are low after manufacturing and that they stay low during normal use. APCs and challenge tests are the two tests used to accomplish that goal.
Most companies rely on independent testing labs for this analysis. The advantage of independent labs is that they have more incentive to be objective and, being specialized, are often the most reliable.
About the Author:
Benjamin Tanner holds a Ph.D. in Microbiology and Immunology from the University of Arizona, where he studied infectious diseases with Dr. Charles Gerba. After graduation, he worked as a microbiologist for the Clorox Company and wrote the book “Legal Aspects of Infectious Diseases.” Subsequently, in 2006, he founded Antimicrobial Test Laboratories, an EPA and FDA GLP-compliant, testing facility employing nearly 20 people. Most recently, he launched Cosmetic Test Labs, recognizing the need for fast, attentive, cost-competitive services in the cosmetic industry.