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Frequently Asked Questions

Why do I need to provide an expiry date or a retest date for my sample?

We ask for an expiry or retest date to ensure that your test item is within its established shelf life specifications when stored under defined conditions – it’s all part of our work being performed in line with GLP (Good Laboratory Practice). It’s important that this is a true expiry date or retest date as it helps us make sure your test item is behaving as it should, and the results you get from us are correct.

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.

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.

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.

Where do you get your human cell cultures from?

We have long standing relationships with global biotechnology companies who we buy our tissue models from. They source them from consenting donors, usually as a by-product of cosmetic surgery.

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.