The World Health Organisation (WHO) has described stress as the “health epidemic of the 21st Century” and we know that stress puts our inflammatory responses on alert, lowering the threshold to elicit a reaction. When you take into account other contributory factors such as air pollution, chemical or occupational exposure and in the post-Covid era, more frequent washing, it’s no wonder that consumer demand for ever milder products is increasing.
Naldi et al (JAMA Dermatol (2014) 150(2): 154-162) completed a study of 12,377 individuals in Europe and found that 51.7% had experienced a skin reaction that lasted more than 3 days at some point in their lifetime and 37% avoided skincare products as a result. This indicates that failing to ensure a product is mild can influence buying decisions, now and into the future.
This creates a competitive environment for chemical manufacturers aiming to provide the very gentlest personal care ingredients, so it’s critical to have a sensitive and reproducible lab-based test, capable of picking up subtle differences. Regulations in Europe and beyond, as well as consumer expectations for cruelty-free approaches, create an additional basic expectation that such a test should be animal-free.
A test to assess performance in comparison to established alternatives
Within this context, in 2019, surfactant specialists Lankem approached XCellR8 to help assess the relative mildness of their exciting new range of BioLoop surfactants.
Their aim was to bring to market a range of sustainable, bio-based products with comparable performance to existing synthetic equivalents. They needed a sensitive and reproducible lab-based test which was capable of detecting subtle differences in the formulations in order to make strong, evidence based marketing claims. And in line with their company policy, there was an expectation that the test should be animal-free.
Lankem became one of the first companies in the world to use the new XtraMild test, developed by XCellR8 with funding from Innovate UK. As well as providing a mildness classification for each of the BioLoop surfactants, the project benchmarked them against widely available non ionic surfactants to give that all-important comparison data.
The ET50 test method
The in vitro test was successfully adapted from the widely used ET50 method using human reconstructed skin models. Formulations are applied to the skin model surface for defined time points, followed by determination of any damage to the skin cells, using an indicator of intracellular metabolism. Test results are expressed as the ET50 value – the time taken for viability to drop to 50% of the untreated control.
The standard ET50 method was validated against historical animal data (Draize test). In this project, we chose instead to validate the approach directly against human patch test data generated using the same batch of blind-coded test material.
ResultsDownload pdf for full results
The results uncovered differences in the ET50 value over time that allowed even the three formulations classified as Non-irritating (the best score available) to be ranked in terms of mildness. They also showed that the BioLoop surfactants were milder than the established synthetic. Finally, the in vitro and in vivo methods produced closely comparable results with an identical rank order prediction of mildness, providing robust validation of the in vitro method.
The results have enabled Lankem to back up their performance claims for the BioLoop range with credible lab data, helping to reassure their clients that the surfactants are a green alternative to conventional synthetic non ionics such as alcohol ethoxylates.
Sean Hodgkinson, Sales Director, Lankem commented:
“Before XtraMild became available, we were limited in our abilities to demonstrate the mildness of our novel ingredients but the results provide a trustworthy dataset to take to market, meeting demand for ultra-mild surfactants that have been tested in animal-free conditions.”
Dr Carol Treasure, Founder and CEO of XCellR8 added:
“For innovative companies like Lankem, being able to prove the performance of new, sustainable technologies like BioLoop is a significant factor in achieving commercial targets. We were delighted that the XtraMild test turned out to be so highly sensitive, and comparable in its results to human patch tests.”