Skip to Main Navigation
Skip to Page Content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it's official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you're on a federal government site.


The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Share This:

Electrophilic Allergen Screening Assay (EASA)

Binding of a chemical to skin proteins is the first step in the development of allergic contact dermatitis. The EASA is a chemical assay that measures light absorbance or a fluorescent signal in proportion to a chemical’s tendency to bind to proteins.

The EASA was nominated to ICCVAM to evaluate its usefulness in identifying potential skin sensitizers. Four ICCVAM member agencies are participating in an ongoing validation study of the EASA. Testing of 10 chemicals during 2018 showed that the method had sufficiently good reproducibility and accuracy rates to support further evaluation. Results of this testing 10 chemicals were presented (Strickland et al.) at the 2018 Annual Meeting of the American Society for Cellular and Computational Toxicology.

In 2019, the Consumer Product Safety Commission and the National Institute for Standards and Technology (NIST) modified the assay to a 96-well format to increase throughput and accessibility of the assay. Petersen et al. (2022) describes this process, including the incorporation of in-process control measurements to quantify key sources of variability each time the assay is run. Planned testing of 20 chemicals using the 96-well assay has been delayed due to lab closures during the COVID-19 pandemic, but is expected to be completed in 2022.