Sensitization properties of acetophenone azine, a new skin sensitizer identified in textile

Background Acetophenone azine (CAS no. 729-43-1) present in sports equipment (shoes, socks and shin pads) has been suspected to induce skin allergies. Twelve case reports of allergy in children and adults from Europe and North America were published between 2016 and 2021. Objectives The objective of this study was to confirm that acetophenone azine is indeed a skin sensitizer based on in vitro/ in vivo testings derived from the Adverse Outcome Pathway (AOP) built for skin sensitization by OECD in 2012. Methods Acetophenone azine was tested in vitro according to the human cell line activation test (h-CLAT) and the ARE-Nrf2 Luciferase Test (KeratinoSens) and in vivo using the Local Lymph Nodes Assay (LLNA). Results Both the h-CLAT and the KeratinoSens were positive whereas the LLNA performed at 5, 2.5 and 1% (wt/vol) of acetophenone azine, was negative. Conclusion Based on these results, acetophenone azine was considered as a skin sensitizer. This was recently confirmed by its classification under the CLP regulation.

Automated summary

Twelve case reports from Europe and North America confirmed that acetophenone azine, found in sports equipment, is suspected to cause skin allergies. In vitro and in vivo tests based on the Adverse Outcome Pathway (AOP) built for skin sensitization by OECD in 2012 were conducted to confirm its skin sensitization properties. The results showed positive reactions in the in vitro tests and negative reactions in the in vivo test. As a result, acetophenone azine was classified as a skin sensitizer under the CLP regulation.