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3.3.3.: Classification criteria for mixtures
The mixture shall be classified using the criteria for substances, and taking into account the tiered approach to evaluate data for this hazard class.
When considering testing of the mixture classifiers are encouraged to use a tiered weight of evidence approach as included in the criteria for classification of substances for skin corrosion and serious eye damage/eye irritation to help ensure an accurate classification, as well as to avoid unnecessary animal testing. In the absence of any other information, a mixture is considered to cause serious eye damage (Category 1) if it has a pH ≤ 2 or ≥ 11,5. However, if consideration of acid/alkali reserve suggests the mixture may not cause serious eye damage despite the low or high pH value, this needs to be confirmed by other data, preferably data from an appropriate validated in vitro test.
Where the mixture itself has not been tested to determine its skin corrosivity or potential to cause serious eye damage/eye irritation, but there are sufficient data on the individual ingredients and similar tested mixtures to adequately characterise the hazards of the mixture, these data shall be used in accordance with the bridging rules set out in Section 1.1.3.
In order to make use of all available data for purposes of classifying the serious eye damage/eye irritation properties of the mixtures, the following assumption has been made and is applied where appropriate in the tiered approach:
The ‘relevant ingredients’ of a mixture are those which are present in concentrations ≥ 1 % (w/w for solids, liquids, dusts, mists and vapours and v/v for gases), unless there is a presumption (e.g. in the case of skin corrosive ingredients) that an ingredient present at a concentration < 1 % can still be relevant for classifying the mixture for serious eye damage/eye irritation.
In general, the approach to classification of mixtures as seriously damaging to the eye/eye irritant when data are available on the ingredients, but not on the mixture as a whole, is based on the theory of additivity, such that each skin corrosive or serious eye damaging/eye irritant ingredient contributes to the overall serious eye damage/eye irritation properties of the mixture in proportion to its potency and concentration. A weighting factor of 10 is used for skin corrosive and serious eye damaging ingredients when they are present at a concentration below the generic concentration limit for classification with Category 1, but are at a concentration that will contribute to the classification of the mixture as eye irritant. The mixture is classified as seriously damaging to the eye or eye irritant when the sum of the concentrations of such ingredients exceeds a concentration limit.
Table 3.3.3 provides the generic concentration limits to be used to determine if the mixture shall be classified as seriously damaging to the eye or as eye irritant.
Particular care must be taken when classifying certain types of mixtures containing substances such as acids and bases, inorganic salts, aldehydes, phenols, and surfactants. The approach explained in Sections 3.3.3.3.1 and 3.3.3.3.2 might not work given that many such substances are seriously damaging to the eye/eye irritant at concentrations < 1 %.
For mixtures containing strong acids or bases the pH shall be used as classification criterion (see Section 3.3.3.1.2) since pH will be a better indicator of serious eye damage (subject to consideration of acid/alkali reserve) than the generic concentration limits in Table 3.3.3.
A mixture containing skin corrosive or serious eye damaging/eye irritating ingredients that cannot be classified based on the additivity approach (Table 3.3.3) due to chemical characteristics that make this approach unworkable, shall be classified as Serious Eye Damage (Category 1) if it contains ≥ 1 % of a skin corrosive or serious eye damaging ingredient and as Eye Irritation (Category 2) when it contains ≥ 3 % of an eye irritant ingredient. Classification of mixtures with ingredients for which the approach in Table 3.3.3 does not apply is summarised in Table 3.3.4.
On occasion, reliable data may show that the effects of serious eye damage/eye irritation of an ingredient will not be evident when present at a level at or above the generic concentration limits mentioned in Tables 3.3.3 and 3.3.4 in Section 3.3.3.3.6. In these cases the mixture shall be classified according to those data (see also Articles 10 and 11). On other occasions, when it is expected that the skin corrosion/irritation hazards or the effects of serious eye damage/eye irritation of an ingredient will not be evident when present at a level at or above the generic concentration limits mentioned in Tables 3.3.3 and 3.3.4, testing of the mixture shall be considered. In those cases, the tiered weight of evidence approach shall be applied.
If there are data showing that (an) ingredient(s) may be corrosive to the skin or seriously damaging to the eye/eye irritating at a concentration of < 1 % (corrosive to the skin or seriously damaging to the eye) or < 3 % (eye irritant), the mixture shall be classified accordingly.
Table 3.3.3
Generic concentration limits of ingredients classified as skin corrosion (Category 1, 1A, 1B or 1C) and/or serious eye damage (Category 1) or eye irritation (Category 2) that trigger classification of the mixture as serious eye damage/eye irritation where the additivity approach applies
|
Sum of ingredients classified as: |
Concentration triggering classification of a mixture as: |
|
|
Serious eye damage |
Eye irritation |
|
|
Category 1 |
Category 2 |
|
|
Skin corrosion Sub-Category 1A, 1B, 1C or Category 1 + Serious eye damage (Category 1) () |
≥ 3 % |
≥ 1 % but < 3 % |
|
Eye irritation (Category 2) |
|
≥ 10 % |
|
10 × (Skin corrosion Sub-Category 1A, 1B, 1C or Skin corrosion Category 1 + Serious eye damage (Category 1)) + Eye irritation (Category 2) |
|
≥ 10 % |
|
(1) If an ingredient is classified as both Skin Corrosion Sub-Category 1A, 1B, 1C or Category 1 and Serious Eye Damage (Category 1), its concentration is considered only once in the calculation. |
||
Table 3.3.4
Generic concentration limits of ingredients that trigger classification of the mixture as serious eye damage (Category 1) or eye irritation (Category 2), where the additivity approach does not apply
|
Ingredient |
Concentration |
Mixture classified as: |
|
Acid with pH ≤ 2 |
≥ 1 % |
Serious eye damage (Category 1) |
|
Base with pH ≥ 11,5 |
≥ 1 % |
Serious eye damage (Category 1) |
|
Other ingredient classified as skin corrosion (Sub-Category 1A, 1B, 1C or Category 1) or serious eye damage (Category 1) |
≥ 1 % |
Serious eye damage (Category 1) |
|
Other ingredient classified as eye irritation (Category 2) |
≥ 3 % |
Eye irritation (Category 2) |