Published in Regulatory Toxicology and Pharmacology, scientists from Beiersdorf, Chanel, Estée Lauder, Henkel, Kao, L’Oréal, LVMH, Pierre Fabre, Procter & Gamble, Shiseido, Unilever, along with members of two consulting services and the trade association Cosmetics Europe that funded the research, explored six skin sensitisation new approach methodologies (NAMs) on a set of 41 relevant cosmetic ingredients, including dyes, UV-filters, surfactants, fragrances and actives. The NAMs used in the study were: DPRA, KeratinoSens, h-CLAT, U-SENS, SENS-IS and PPRA.
The work conducted in this research saw these substances and all data added to Cosmetic Europe’s existing skin sensitisation database, providing a “valuable resource to better understand the advantages and limitations of the individual NAMs”.
Skin sensitisation ‘generally overpredicted’ by NAMs
Findings showed that all additional substances could be tested successfully for skin sensitisation using these NAMs, for the most part “without technical limitations”. But overall, results showed skin sensitisation was “generally overpredicted when compared to reference results”.
“In conclusion, the testing of non-standard substances revealed that the predictive value of skin sensitisation NAMs associated with standard prediction models was limited,” the team wrote.
“This supports the call for a more detailed understanding of how NAMs apply to a wider range of substances. Flexible and informed use of the NAMs is needed, including adjustment of current protocols,” they said.
Optimal choice of NAMs – either for use within a defined approach or to inform other steps in a next-generation risk assessment framework – would be critical moving forward, they said, particularly when used to conduct skin sensitisation risk assessments.
‘In-depth and harmonised understanding of NAMs is fundamental’
And this was especially relevant given the current European regulatory context for cosmetics, according to the team of scientists.
“The assessment of skin sensitisation is a key requirement in all regulated sectors, with the European Union’s regulation of cosmetic ingredients being most challenging, since it requires quantitative skin sensitisation assessment based on new approach methodologies (NAMs),” they wrote.
“To address this challenge, an in-depth and harmonised understanding of NAMs is fundamental to inform the assessment,” they said.
Deepening understanding, the scientists said, would ultimately support a “flexible and informed choice of NAMs to be optimally applied in the context of a next-generation risk assessment framework, ultimately contributing to the characterisation and reduction of uncertainty”.
And flexibility was essential when using NAMs for skin sensitisation testing, they said, “to be able to account for substance- and exposure-specific needs”.
Next-generation risk assessment – 10-step framework established
Earlier this year, a different team of scientists from several major beauty brands, alongside Cosmetics Europe, outlined a new approach for cosmetic toxicology assessment. The 10-step framework combined read-across (RAX) assessment approaches and new approach methodologies (NAMs) in biology and kinetics, such as in vitro assays, toxicogenomics and metabolomics. It had been designed for use in cases where a threshold of toxicological concern (TTC) approach was not possible for cosmetics safety assessment.
In this instance, the team upheld that NAMs, in combination with RAX assessment approaches, were adequate to conduct these assessments.
According to toxicology experts, there was also great potential to expand use of NAMs to test worker safety and environmental impact too.
Source: Regulatory Toxicology and Pharmacology
Published online ahead of print, doi: 10.1016/j.yrtph.2022.105169
Title: “Expansion of the Cosmetics Europe skin sensitisation database with new substances and PPRA data”
Authors: S. Hoffmann et al.
