BCOP-EIT - OECD 405 Weight of Evidence Testing

Dual Assay for Identifying Eye Irritants (GHS Category 2) Using Validated Assays

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Background Information

The Organization for Economic Co-Operation and Development (OECD) has prescribed the use of a weight-of-evidence (WoE) analysis, integrated with a sequential testing strategy, for the classification of acute eye hazards. The October 2017 revision to the Health Effects Test Guideline No. 405 outlines a stepwise strategy that includes Step 6, “Perform validated and accepted in vitro or ex vivo ocular test(s),” specifying only four possible assays: three tests designed to identify severe eye irritation/ corrosion (GHS Category 1) and one test to identify non-irritants (GHS No Category), the top-down and bottom-up approaches, respectively.

Currently, a definitive GHS Category 2 (eye irritant) classification is not achievable using any one alternative assay. Our approach utilizes the following validated alternative assays integrated to provide confident assessment of ocular irritation:

By using a dual-assay/approach system – the combination of the EIT and BCOP test – we have determined, with a high degree of accuracy, GHS Acute Eye Hazard Category 2 chemicals that cause reversible eye irritation. When a BCOP test rules out GHS Category 1 and the EIT rules out GHS No Category, analysis of these results indicates the only other possible designation – Category 2. Per GHS, Category 2 classification defaults to Category 2A, because differentiation between Category 2A and 2B cannot be made.

Spectrum of Ocular Irritancy - BCOP-EIT

BCOP-EIT GHS Irritancy Spectrum
BCOP-EIT GHS Irritancy Spectrum

Validation Studies

MB Research has conducted an Internal Validation consisting of testing of 42 chemicals. Results Correctly identified 87% of the Category 2A/B chemicals as Category 2 after testing 42 chemicals (nine, 15, and 18 in Category 1, 2A/B, and No Category, respectively).

As a result of this analysis, we are encouraged by the potential of the BCOP-EIT dual-assay system, coupled with WoE evaluation, to correctly assign unknowns into GHS Category 1, Category 2A, and No Category Acute Eye Hazards without the use of less predictive and more expensive in vitro tests as well as, greatly reducing the reliance on the Draize Rabbit Eye Test.

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