Report: Chemical Assay May Be Useful in Identifying Potential Skin Sensitizers

The electrophilic allergen screening assay (EASA) “may be a useful non-animal method to identify potential skin sensitizers,” according to a recent newsletter published by the NTP Interagency Center for the Evaluation of Alternative Toxicological Methods. NICEATM describes EASA as a “chemical assay that measures light absorbance or a fluorescent signal in proportion to a chemical’s tendency to bind to proteins,” and highlights a report published last month that details the results of a validation study of the assay that was conducted by four laboratories.

The report states that NIOSH nominated EASA to the Interagency Coordinating Committee on the Validation of Alternative Methods (ICCVAM) as an in chemico test method for allergic contact dermatitis hazard testing. The purposes of ICCVAM, a committee of the National Institute of Environmental Health Sciences, include ensuring that new and revised test methods are validated to meet the needs of U.S. federal agencies. The committee also seeks to reduce, refine, or replace the use of animals in testing as is feasible.

“[T]he EASA Validation Management Team found the EASA’s reproducibility, sensitivity, and accuracy acceptable for discriminating between sensitizers and nonsensitizers when combined with other information sources, such as those used in [defined approaches] or integrated approaches to testing and assessment,” the report’s abstract states.

While the EASA test method “may be able to predict skin sensitization hazard with higher throughput, greater accessibility, and lower cost than existing animal methods,” the report mentions possible limitations related to chemical interference and the use of a statistical cut-off versus a threshold cut-off to determine EASA’s sensitizing potential.

For more information or to download the report, visit the National Toxicology Program webpage on EASA.

Related: An article published in the November 2019 Synergist discusses dermal sensitizers.