Table 1.

EPA and GHS Ocular Irritation Classification Systems

EPA Classification			GHS Classification
Category	Positive Response	Classification	Category	Positive Response	Classification
I	● Corneal opacity or iritis ≥1 ● Conjunctival redness or chemosis ≥2 in a single animal at any observed time point up to 21 days after substance administration	Corrosive (irreversible destruction of ocular tissue), or corneal involvement or irritation lasting for more than 21 days after administration of substance	1	At least 2 animals with mean response (over Days 1, 2, and 3) of ● Comeal opacity ≥3 ● Iritis ≥1.5 OR At least 1 animal with a score >0 on observation day 21	Effects on the cornea, iris, or conjunctiva that are not expected to reverse or do not fully reverse within 21 days
II		Comeal involvement or irritation clearing in 8 to 21 days after administration of substance	2A	At least 2 animals with mean response (over Days 1, 2, and 3) of ● Corneal opacity or iritis ≥1 ● Conjunctival redness or opacity ≥1	Effects on the cornea, iris, or conjunctiva that fully reverse within 21 days
III		Corneal involvement or irritation clearing in ≤7 days after administration of substance	2B		Effects on the cornea, iris, or conjunctiva that fully reverse within 7 days
IV		Irritation clearing in <24 hours after administration of substance	NC		No effects are produced, or minimal effects observed that do not lead to classification

Abbreviations: NC = not classified.