The in vitro landscape for eye safety testing has evolved greatly in recent years. Multiple tests are now available, and each has been designed for different purposes including regulatory classification, generating mildness and claims data as well as claims for baby care. This complexity can be confusing for companies to identify which test(s) they need.
Eye safety testing is one of the most common enquiries we receive at XCellR8 and we dedicate a lot of time supporting clients through their testing journey and ensuring the specific tests match their desired requirements.
Here we describe how we help to select the right test for you.
Regulatory classification
If you need a hazard classification for product registration, there are two OECD Test Guideline (TG) methods to consider.
TG 492 is the established method, using a reconstructed human cornea model it is only able to identify substances that do not require classification for eye irritation or serious eye damage (UN GHS No Category). We perform it routinely to GLP and it is globally accepted by regulators.
TG 492B is a newer method, adopted in 2022 and updated in 2024, and is a significant step forward. It can classify chemicals and mixtures into all three UN GHS eye hazard categories in a single test: Category 1 (serious eye damage), Category 2 (eye irritation) and No Category. Previous methods couldn’t do that alone. TG 492B uses a Time-to-Toxicity approach with separate protocols for liquids and solids, and it’s been recommended as a full replacement for the in vivo Draize test for classification.
When clients come to us needing regulatory data, we’ll talk through whether TG 492 or TG 492B is the better fit for their product and their regulatory submission. It depends on the endpoint they need to address and the level of classification required.
Mildness and claims data
Regulatory methods give you a hazard classification. But a lot of the companies we work with need more than that. For example, they want to know how mild their product is, how it compares to competitors, and whether they can substantiate the claims they want to make on pack.
That’s where our ET50 mildness method comes in. It measures the time taken to reduce the viability of a 3D reconstructed human cornea model to 50%, giving a continuous value rather than a binary outcome. The result is a detailed irritancy classification (Severe, Moderate, Mild or Minimal/Non-Irritant) alongside an ET50 value that can be used to rank formulations, benchmark against competitor products, and track improvements across development cycles.
It’s also commonly used as a screen prior to clinical studies, giving confidence in a formulation before committing to more expensive human volunteer work.
For brands working on sensitive skin, facial care, baby care or household products, this is usually the method we recommend. The data is richer, the story it tells is more useful for both your safety assessor and your marketing team.
Claims for baby care
We’re routinely using the ET50 method to support claims for baby bath products, shampoos and washes. We hold anonymised reference values across a wide range of similar products, and you can also build in your own choice of benchmarks for direct comparison. If your formulation performs as well as, or better than, established mild products on the market, that’s strong evidence for your claim.
One question that comes up regularly with baby care is whether to test the product neat or at in-use dilution. A baby shampoo applied directly is a very different proposition to the same product diluted in bath water. We often recommend testing both, because the comparison provides the most complete picture. It can show that while the neat product has some irritation potential, the in-use dilution is genuinely mild. That gives everyone what they need.
We’ll point you in the right direction
Every product is different and every company’s requirements are different. Some need a regulatory classification and nothing else. Some need detailed claims data but don’t need GLP. Some need both. Some aren’t sure.
That’s fine. We do this every day and we’re good at working out what’s actually needed versus what’s nice to have. If you’re not sure which route is right for your product, get in touch and we’ll talk it through. It’s one of the things we enjoy most about this work.
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