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3.3.2.: Classification criteria for substances

Substances are allocated to one of the categories within this hazard class, Category 1 (serious eye damage) or Category 2 (eye irritation), as follows:
(a) Category 1 (serious eye damage):

substances that have the potential to seriously damage the eyes (see Table 3.3.1).

(b) Category 2 (eye irritation):

substances that have the potential to induce reversible eye irritation (see Table 3.3.2).

3.3.2.1. Classification based on standard animal test data
3.3.2.1.1. Serious eye damage (Category 1)
3.3.2.1.1.1. A single hazard category (Category 1) is adopted for substances that have the potential to seriously damage the eyes. This hazard category includes as criteria the observations listed in Table 3.3.1. These observations include animals with grade 4 cornea lesions and other severe reactions (e.g. destruction of cornea) observed at any time during the test, as well as persistent corneal opacity, discoloration of the cornea by a dye substance, adhesion, pannus, and interference with the function of the iris or other effects that impair sight. In this context, persistent lesions are considered those which are not fully reversible within an observation period of normally 21 days. Hazard classification as Category 1 also contains substances fulfilling the criteria of corneal opacity ≥ 3 or iritis > 1,5 observed in at least 2 of 3 tested animals, because severe lesions like these usually do not reverse within a 21-day observation period.
3.3.2.1.1.2. The use of human data is discussed in Section 3.3.2.2 and also in Sections 1.1.1.3, 1.1.1.4 and 1.1.1.5.


Table 3.3.1

Serious eye damage ()

Category

Criteria

Category 1

A substance that produces:

(a)  in at least one animal effects on the cornea, iris or conjunctiva that are not expected to reverse or have not fully reversed within an observation period of normally 21 days; and/or

(b)  in at least 2 of 3 tested animals, a positive response of:

(i)  corneal opacity ≥ 3; and/or

(ii)  iritis > 1,5;

calculated as the mean scores following grading at 24, 48 and 72 hours after instillation of the test material.

(1)   Grading criteria are understood as described in Regulation (EC) No 440/2008.

3.3.2.1.2. Eye irritation (Category 2)
3.3.2.1.2.1. Substances that have the potential to induce reversible eye irritation shall be classified in Category 2 (eye irritation).
3.3.2.1.2.2. For those substances where there is pronounced variability among animal responses, this information shall be taken into account in determining the classification.
3.3.2.1.2.3. The use of human data is addressed in Sections 3.3.2.2, and also in Sections 1.1.1.3, 1.1.1.4 and 1.1.1.5.


Table 3.3.2

Eye irritation ()

Category

Criteria

Category 2

Substances that produce in at least 2 of 3 tested animals a positive response of:

(a)  corneal opacity ≥ 1; and/or

(b)  iritis ≥ 1; and/or

(c)  conjunctival redness ≥ 2; and/or

(d)  conjunctival oedema (chemosis) ≥ 2

calculated as the mean scores following grading at 24, 48 and 72 hours after instillation of the test material, and which fully reverses within an observation period of normally 21 days.

(1)   Grading criteria are understood as described in Regulation (EC) No 440/2008.

3.3.2.2. Classification in a tiered approach
3.3.2.2.1.

A tiered approach to the evaluation of initial information shall be considered where applicable, recognizing that not all elements may be relevant.

3.3.2.2.2.

Existing human and animal data shall be the first line of evaluation as they give information directly relevant to effects on the eye. Possible skin corrosion has to be evaluated prior to consideration of any testing for serious eye damage/eye irritation in order to avoid testing for local effects on eyes with skin corrosive substances. Skin corrosive substances shall be considered as leading to serious eye damage (Category 1) as well, while skin irritant substances may be considered as leading to eye irritation (Category 2).

3.3.2.2.3.

In vitro alternatives that have been validated and accepted shall be used to make classification decisions.

3.3.2.2.4.

Likewise, pH extremes like ≤ 2 and ≥ 11,5, may indicate serious eye damage, especially when associated with significant acid/alkaline reserve (buffering capacity). Generally such substances are expected to produce significant effects on the eyes. In the absence of any other information, a substance is considered to cause serious eye damage (Category 1) if it has a pH ≤ 2 or ≥ 11,5. However, if consideration of acid/alkaline reserve suggests the substance may not cause serious eye damage despite the low or high pH value, this needs to be confirmed by other data, preferably by data from an appropriate validated in vitro test.

3.3.2.2.5.

In some cases sufficient information may be available from structurally related substances to make classification decisions.

3.3.2.2.6.

The tiered approach provides guidance on how to organize existing information and to make a weight-of-evidence decision about hazard assessment and hazard classification. Animal testing with corrosive substances shall be avoided whenever possible. Although information might be gained from the evaluation of single parameters within a tier (see 3.3.2.1.1) consideration shall be given to the totality of existing information and making an overall weight of evidence determination. This is especially true when there is conflict in information available on some parameters.