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Defined Approaches to Identify Potential Eye Irritants

Prospective and Retrospective Evaluation of the Eye Irritation Potential of Agrochemical Formulations (July 2021)

This NICEATM report describes (1) evaluation of 232 retrospective paired in vitro and in vivo eye irritation and (2) generation and evaluation of data for 16 agrochemical formulations in a variety of in vitro test methods to support development of a defined approach for eye irritation testing. The report also discusses issues associated with reliance on animal data as a reference for the evaluation of new testing approaches.

Potential eye irritants can be identified without animal testing using defined approaches to testing and assessment. A defined approach consists of:

  • Input data generated from identified methods.
  • A data interpretation procedure (e.g., machine-learning model, flowchart, or decision tree through which the data are evaluated).

In June 2022, OECD issued Test Guideline No. 467, Defined Approaches for Serious Eye Damage and Eye Irritation. This guideline describes two defined approaches that can be used to test and assign eye irritation hazard classifications to non-surfactant chemicals.

More about defined approaches to testing and assessment

NICEATM is collaborating with the PETA International Science Consortium Ltd. (PETA-ISC), EPA, and member companies of the trade association CropLife America to develop an in vitro defined approach for classification of eye irritation potential of agrochemical formulations. This public-private partnership was established as a means to develop confidence in non-animal methods for identifying potential eye irritants and thus encourage adoption and use. This project is described in a poster (Choksi et al.) presented at the 11th World Congress on Alternatives and Animal Use in the Life Sciences.

Details of the Study

NICEATM initially analyzed data from four in vitro assays paired with in vivo rabbit eye test data to determine if a defined approach using a combination of these assays could assess eye irritation potential. While the results of this analysis indicated that developing such a defined approach was feasible, the data sets were limited in size and a final conclusion could not be made. Therefore, it was determined that additional prospective testing was needed.

Members of the collaboration team designed a three-phase prospective evaluation to (1) assess the applicability of seven in vitro eye irritation/corrosion methods to agrochemical formulations and (2) develop a defined approach for agrochemical formulations testing for prediction of U.S. and international irritancy classifications. The test methods used include:

  • Bovine corneal opacity and permeability
  • Bovine corneal opacity and permeability – extended incubation (evaluated in Phase 2 only)
  • Neutral red release
  • Isolated chicken eye
  • Porcine cornea reversibility
  • EpiOcular EIT
  • EpiOcular time-to-toxicity ET50-neat
  • EpiOcular time-to-toxicity ET50-dilution

In Phase 1, six formulations were tested in seven eye irritation test methods. All eight methods were used in Phase 2, which evaluated 10 formulations that represented a range of eye irritancy classifications. Phases 1 and 2 are complete, and the results from these phases will determine the next steps of the study.