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Frequently Asked Questions

Which skin irritation test do I need?

This depends on whether you need the test for EU regulatory purposes, in which case Skin Irritation OECD TG 439 might be right for you, providing a binary answer as to whether your item is an Irritant or Non Irritant, or for product development. Our non regulatory test uses the ET50 method and is used to place your item into a rank order of irritation potential or compare it against industry benchmarks. We’re more than happy to chat through the different test methods, or can introduce you to one of our regulatory consultancy partners who can help you make the decision.

What happens if I can’t provide a molecular weight for my test item?

This request only applies to the DPRA test. If you aren’t able to provide the molecular weight, you can detail the list of constituents with percentage compositions and we can approximate it using the guidance in the Test Guideline. As a last resort, the test item may be run neat (liquids) or dissolved at the highest soluble concentration (solids) then combined at a 1:10 or 1:50 ratio using the Cysteine and Lysine containing peptides respectively.

How much of my product or material will you need to start a study?

10 ml if it’s a liquid or 10g if it’s a solid. This makes sure we’ve got enough of the item if you order more than one test. Please ensure your samples are clearly labelled, and match any documentation you send with them. If you don’t have this amount of your test item available, please call us to discuss your options.

What units is antioxidant activity measured in for this assay?

XCellR8’s antioxidant test uses the OxiSelect™ method. The test is based on the intracellular conversion of DCFH to its fluorescentmetabolite (DCF). The reaction is inhibited by anti-oxidants, reducing the amount of fluorescence observed and so the test measures fluorescent intensity. You can read more information about OxiSelect™ here.

Does XCellR8 offer human patch testing?

No, we don’t but many clients use our in vitro tests as an early screen in product development before they get to more expensive human trials. They can also be used to generate supporting information in a weight-of-evidence approach to safety assessment. XCellR8’s tests may give you a binary classification on the effect of an ingredient, for example, Irritant or Non Irritant, or a more detailed classification to help you rank irritation potential. Please get in touch if you’d like to find out more.

Which skin sensitisation test do I need?

Current regulatory guidance for in vitro skin sensitisation testing is to adopt the “2 out of 3” approach, whereby 2 positive results out of the 3 tests (OECD TGs 442c, 442d and 442e) results in classification as a Skin Sensitiser. If you perform two of the tests and get matching results, this strategy states you can have confidence in the result without the third test. If they have different results, proceed to the third method to find a definitive result. Each of the three methods has different requirements regarding the solubility of your test item, so contact us to find out which will be best for you. You can also read more about the test methods here.