Abstract
The Bovine Corneal Opacity and Permeability Assay (BCOP) is an ex vivo assay, which may be used to assess the eye irritation potential of new chemicals and finished products. The BCOP assay has been accepted by several regulatory agencies for the identification of severe and corrosive ocular irritants, replacing the rabbit eye test. As per the TG OECD 437 for eye irritation (BCOP assay), non-surfactant solid materials are typically tested as 20% dilutions prepared in 0.9% sodium chloride solution or other solvent that has been demonstrated to have no adverse effects on the test system. However, the limited solubility of some chemicals adds technical challenges in finding a suitable vehicle that would ensure the material’s availability to the excised corneas without affect the test system. In this study, we evaluated three solvents in the BCOP assay: normal saline, olive oil and propylene glycol. Based on the available classification systems, our preliminary data showed that water and olive oil were predicted as non-irritants, while propylene glycol was predicted as a mild irritant. To demonstrate the influence of the type of solvent on the outcome/prediction of the BCOP assay for solid materials, we tested a 20% suspension of dicamba prepared in these solvents. Previous animal tests have reported corrosive effect of dicamba. Our results demonstrated that when mixed in normal saline and corn oil dicamba was predicted to be a corrosive, while it was predicted to be a moderate irritant when mixed in propylene glycol. These results support the need for further investigation of the solvent’s influence in the BCOP assay to allow the correct prediction of the irritation potential of solid materials.
