Validated Non-animal Alternatives
|
Methods |
Test Purpose |
Validation Authority |
OECD TG |
| Bovine Corneal Opacity and Permeability (BCOP) assay |
Eye corrosion |
ICCVAM; ECVAM |
|
| Isolated Chicken Eye (ICE) assay |
Eye corrosion |
ICCVAM; ECVAM |
|
| Isolated Rabbit Eye (IRE) assay |
Eye corrosion |
(a) |
|
| Hen's Egg Test - Chorio-Allantoic Membrane assay (HET-CAM) |
Eye corrosion |
(a) |
|
(a) Although not formally endorsed as valid, positive outcomes can be used for classifying and labeling substances as severe eye irritants (R41) in the European Union.
The Interagency Coordinating Committee on the Validation of Alternative Methods (ICCVAM) has made the following recommendation of four in vitro screening tests for identifying ocular corrosives and severe irritants: "In 2007, BCOP and ICE recommended as screening tests for identifying corrosives and severe irritants, with certain limitations; HET-CAM and IRE not recommended for regulatory hazard classification purposes until further developed and evaluated."
The ESAC statement on the ICCVAM retrospective study of the four in vitro screening assays for ocular corrosives/severe irritants endorsed the validity of the BCOP and ICE methods for use in a tiered strategy as part of the weight of evidence approach. The ESAC indicated further work is needed for the IRE and HET-CAM methods (ESAC Statement, April 27, 2007).
The specific limitations on the uses of these in vitro methods are described in the documents on the ECVAM and ICCVAM websites.
The BCOP assay uses cow eyes obtained from slaughterhouses. The cornea is isolated from the rest of the eye and maintained in a holder. A test substance is applied to this isolated cornea for a specified time, then removed, and the effect of the substance on the permeability of the cornea to fluorescein (a colored dye) and the increase in corneal opacity (transmission of light through the cornea) are determined. Both of these assay endpoints have been used in the in vivo Draize rabbit eye test and generally correlate well with the degree of corneal injury from a test material.
The ICE assay uses chicken eyes obtained from slaughterhouses. The eyes are placed in an apparatus where they can be kept moist and treated with the test substance. Three responses of the cornea are evaluated: corneal swelling, corneal opacity, and fluorescein retention, and the irritation potential of a substance is calculated from the mean values of these measurements.
Additional information on in vitro methods being developed for eye irritation/corrosion toxicity testing can be found in Toxicity Endpoints & Tests: Eye Irritation/Corrosion.
|
