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ICCVAM Biennial Report 2020-2021

Biennial Progress Report 2020-2021 Interagency Coordinating Committee on the Validation of Alternative Methods

Draft Risk Assessment for Isothiazolinones

In May 2020, EPA requested comment (85 FR 28944) on draft human health and ecological risk assessments for a group of antimicrobial chemicals known as isothiazolinones. EPA accepted comments on the draft risk assessments through November 2020.

Isothiazolinones are used in a variety of products including plastics, household cleaners, and laundry detergents. They frequently cause skin sensitization. EPA requested comment on the use of an in vitro and artificial neural network-based defined approach instead of using laboratory animal data to evaluate skin sensitization risks for products containing isothiazolinones. This is the first consideration of this type of defined approach in regulatory risk assessment.

The draft risk assessments rely heavily on work done by NIEHS and ICCVAM. The in vitro testing was conducted by the Toxicology Branch of the NIEHS Division of NTP (DNTP). NICEATM analyzed the in vitro data and ran the artificial neural network-based defined approach to provide quantitative potency predictions used to determine points of departure. The ICCVAM Skin Sensitization Expert Group reviewed the DNTP testing report and the NICEATM analyses before data were provided to EPA for development of the risk assessments.