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What You Need to Know About Patch Testing

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CPT Labs

People choose skincare products trusting that the products will perform as promised and that the products will not harm their skin. To merit this trust, and to comply with government regulations and professional quality standards, manufacturers thoroughly test their skincare products before introducing them to the marketplace.

Many products that come into contact with the skin are not cosmetics, however, such as latex products, adhesives, shower gels and soaps, as well as the basic ingredients that go into making these products, such as preservatives, fragrances, herbal extracts and their synthetic counterparts, or surfactants.

Patch testing is required for any product or ingredient that will contact human skin. As its name implies, patch testing essentially involves applying patches to the skin. As a patch tester, you will be paid to do one of the easiest jobs in consumer product testing.

What is Patch Testing?

Patch testing helps manufacturers measure how skin responds to a product, most often predicting the likelihood of irritation or sensitization. While skin irritation describes a response to one or more encounters with a product or ingredient, skin sensitization is a term that describes an allergic reaction.

In the most basic terms, patch testing is conducted by applying a test product or ingredient to a small patch, securing that patch to the skin, and then examining the skin for its response to the patch after a prescribed time. In some patch tests, subjects merely wear their patches for 48 hours while going about their normal activities. In others, the patches may be reapplied or the subjects may have patches applied to different areas of skin at different times.

If you apply to participate in a patch test study, you will get all the information about your responsibilities as a subject, including the timeline for the study, before testing begins.

What Does the Process Involve?

Typically, a patch test study will be developed according to one of three models:

  • The Primary Irritation Test (also known as the 48-hour patch test): In this model, a series of patches containing test products are applied to the subject’s skin. The subject wears the patch for 48 hours while going about normal activities. At the end of 48 hours, the patches are removed and the skin evaluated for any irritation or other response.
  • The Cumulative Irritation Test: Similar to the 48-hour test described above, this is a longer clinical trial that identifies possible changes in irritation levels over time. Depending on the products and study design, Cumulative Irritation Testing usually spans four to 21 days and requires multiple visits to the testing facility for evaluation.
  • The Repeated-Insult Patch Test (or RIPT): This two-phase process involves the repeated application of a patch during Phase 1, followed by a rest period, and then application of a patch to a different area of skin during Phase 2. The RIPT is designed to predict the likelihood of skin sensitization (allergic reaction) to the product.

Why is Patch Testing Important?

Put simply, patch testing is a critical step for both manufacturers and the public. By effectively evaluating the irritation or sensitization potential of a product that contacts human skin, a company not only protects its brand but also – and more importantly – ensures that consumers can use the product safely.

The patch test can inform product developers whether a product is safe to use as directed. The patch test can also alert the team to the need for specialized use instructions or label warnings, such as those related to prolonged exposure or reactions with other substances, for example.

Safety guidelines and standards are in place around the world for different product categories. For sales of cosmetics and skincare products in Europe, for example, guidelines are recommended by the Scientific Committee on Cosmetic Products and Non-Food Products Intended for Consumers. For sales of cosmetics and skin care products in the US, the US Food & Drug Administration (FDA) provides a range of resources to help manufactures understand and follow consumer safety regulations. Other standards are also in place to ensure user safety, including the professional principles of Good Clinical Practice (GCP), Good Manufacturing Practice (GMP), and Good Laboratory Practice (GLP).

How Can I Get Involved?

It’s easy to get paid to participate in a patch test or other clinical study opportunity, and it’s even easier to sign up for one! Simply find a professional clinical testing facility nearby, check out the upcoming studies, and apply to be a panelist for the ones that interest you. Even if you are not selected for a current study, the facility will keep your information on file and contact you for later studies when you meet the demographic qualifications.