3.2.Skin corrosion/irritationU.K.
3.2.1.DefinitionsU.K.
3.2.1.1.Skin Corrosion means the production of irreversible damage to the skin; namely, visible necrosis through the epidermis and into the dermis, following the application of a test substance for up to 4 hours. Corrosive reactions are typified by ulcers, bleeding, bloody scabs, and, by the end of observation at 14 days, by discolouration due to blanching of the skin, complete areas of alopecia, and scars. Histopathology shall be considered to evaluate questionable lesions.U.K.
Skin Irritation means the production of reversible damage to the skin following the application of a test substance for up to 4 hours.
3.2.2.Classification criteria for substancesU.K.
3.2.2.1.Several factors need to be considered in determining the corrosion and irritation potential of substances before testing is undertaken. Solid substances (powders) may become corrosive or irritant when moistened or in contact with moist skin or mucous membranes. Existing human experience and animal data from single or repeated exposure shall be the first line of analysis, as they give information directly relevant to effects on the skin. In vitro alternatives that have been validated and accepted may also be used to help make classification decisions (see Article 5). In some cases enough information may be available from structurally related compounds to make classification decisions.U.K.
3.2.2.2.Likewise, pH extremes like ≤ 2 and ≥ 11,5 may indicate the potential to cause skin effects, especially when buffering capacity is known, although the correlation is not perfect. Generally, such substances are expected to produce significant effects on the skin. If consideration of alkali/acid reserve suggests the substance may not be corrosive despite the low or high pH value, then further testing shall be carried out to confirm this, preferably by use of an appropriate validated in vitro test.U.K.
3.2.2.3.If a substance is highly toxic by the dermal route, a skin irritation/corrosion study is not practicable since the amount of test substance to be applied considerably exceeds the toxic dose and, consequently, results in the death of the animals. When observations are made of skin irritation/corrosion in acute toxicity studies and are observed up through the limit dose, additional testing is not needed, provided that the dilutions used and species tested are equivalent.U.K.
3.2.2.4.All the above information that is available on a substance shall be used in determining the need for in vivo skin irritation testing.U.K.
Although information might be gained from the evaluation of single parameters within a tier (see paragraph 3.2.2.5), e.g. caustic alkalis with extreme pH shall be considered as skin corrosives, there is merit in considering the totality of existing information and making an overall weight of evidence determination. This is especially true when there is information available on some but not all parameters. Generally, primary emphasis shall be placed upon existing human experience and data, followed by animal experience and testing data, followed by other sources of information, but case-by-case determinations are necessary.
3.2.2.5.A tiered approach to the evaluation of initial information shall be considered, where applicable, recognising that all elements may not be relevant in certain cases.U.K.
3.2.2.6.CorrosionU.K.
3.2.2.6.1.On the basis of the results of animal testing a substance is classified as corrosive, as shown in Table 3.2.1. A corrosive substance is a substance that produces destruction of skin tissue, namely, visible necrosis through the epidermis and into the dermis, in at least 1 tested animal after exposure up to a 4 hour duration. Corrosive reactions are typified by ulcers, bleeding, bloody scabs and, by the end of observation at 14 days, by discoloration due to blanching of the skin, complete areas of alopecia and scars. Histopathology shall be considered to discern questionable lesions.U.K.
3.2.2.6.2.Three subcategories are provided within the corrosive category: subcategory 1A — where responses are noted following up to 3 minutes exposure and up to 1 hour observation; subcategory 1B — where responses are described following exposure between 3 minutes and 1 hour and observations up to 14 days; and subcategory 1C — where responses occur after exposures between 1 hour and 4 hours and observations up to 14 days.U.K.
3.2.2.6.3.The use of human data is discussed in paragraphs 3.2.2.1 and 3.2.2.4 and also in paragraphs 1.1.1.3, 1.1.1.4 and.1.1.1.5.U.K.
| Table 3.2.1 | |||
| Skin Corrosive category and subcategories | |||
| Corrosive in > 1 of 3 animals | |||
|---|---|---|---|
| Corrosive subcategories | Exposure | Observation | |
| Category 1: Corrosive | 1A | ≤ 3 minutes | ≤ 1 hour |
| 1B | > 3 minutes - ≤ 1 hour | ≤ 14 days | |
| 1C | > 1 hour - ≤ 4 hours | ≤ 14 days | |
3.2.2.7.IrritationU.K.
3.2.2.7.1.Using the results of animal testing a single irritant category (Category 2) is presented in Table 3.2.2. The use of human data is discussed in paragraphs 3.2.2.1 and 3.2.2.4 and also in paragraphs 1.1.1.3, 1.1.1.4 and.1.1.1.5. The major criterion for the irritant category is that at least 2 of 3 tested animals have a mean score of ≥ 2,3 - ≤ 4,0.U.K.
3.2.2.8.Comments on responses obtained in skin irritation tests in animalsU.K.
3.2.2.8.1.Animal irritant responses within a test can be quite variable, as they are with corrosion. The major criterion for classification of a substance as irritant to skin, as shown in paragraph 3.2.2.7.1, is the mean value of the scores for either erythema/eschar or oedema calculated in at least 2 of 3 tested animals. A separate irritant criterion accommodates cases when there is a significant irritant response but less than the mean score criterion for a positive test. For example, a test material might be designated as an irritant if at least 1 of 3 tested animals shows a very elevated mean score throughout the study, including lesions persisting at the end of an observation period of normally 14 days. Other responses could also fulfil this criterion. However, it should be ascertained that the responses are the result of chemical exposure.U.K.
3.2.2.8.2.Reversibility of skin lesions is another consideration in evaluating irritant responses. When inflammation persists to the end of the observation period in 2 or more test animals, taking into consideration alopecia (limited area), hyperkeratosis, hyperplasia and scaling, then a material shall be considered to be an irritant.U.K.
3.2.3.Classification criteria for mixturesU.K.
3.2.3.1.Classification of mixtures when data are available for the complete mixtureU.K.
3.2.3.1.1.The mixture will be classified using the criteria for substances, and taking into account the testing and evaluation strategies to develop data for these hazard classes.U.K.
3.2.3.1.2.Unlike other hazard classes, there are alternative tests available for skin corrosivity of certain types of substances and mixtures that can give an accurate result for classification purposes, as well as being simple and relatively inexpensive to perform. When considering testing of the mixture, classifiers are encouraged to use a tiered weight of evidence strategy as included in the criteria for classification of substances for skin corrosion and irritation (paragraph 3.2.2.5), to help ensure an accurate classification as well as avoid unnecessary animal testing. A mixture is considered corrosive to skin (Skin Corrosive Category 1) if it has a pH of 2 or less or a pH of 11,5 or greater. If consideration of alkali/acid reserve suggests the substance or mixture may not be corrosive despite the low or high pH value, then further testing shall be carried out to confirm this, preferably by use of an appropriate validated in vitro test.U.K.
3.2.3.2.Classification of mixtures when data are not available for the complete mixture: bridging principlesU.K.
3.2.3.2.1.Where the mixture itself has not been tested to determine its skin irritation/corrosion hazards, 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.U.K.
3.2.3.3.Classification of mixtures when data are available for all components or only for some components of the mixtureU.K.
3.2.3.3.1.In order to make use of all available data for purposes of classifying the skin irritation/corrosion hazards of mixtures, the following assumption has been made and is applied where appropriate in the tiered approach:U.K.
Assumption: the ‘relevant ingredients’ of a mixture are those which are present in concentrations of 1 % (w/w for solids, liquids, dusts, mists and vapours and v/v for gases) or greater, unless there is a presumption (e.g., in the case of corrosive ingredients) that an ingredient present at a concentration of less than 1 % can still be relevant for classifying the mixture for skin irritation/corrosion.
3.2.3.3.2.In general, the approach to classification of mixtures as irritant or corrosive to skin when data are available on the components, but not on the mixture as a whole, is based on the theory of additivity, such that each corrosive or irritant component contributes to the overall irritant or corrosive properties of the mixture in proportion to its potency and concentration. A weighting factor of 10 is used for corrosive components 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 an irritant. The mixture is classified as corrosive or irritant when the sum of the concentrations of such components exceeds a concentration limit.U.K.
3.2.3.3.3.Table 3.2.3 provides the generic concentration limits to be used to determine if the mixture is considered to be an irritant or a corrosive to the skin.U.K.
3.2.3.3.4.1.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 paragraphs 3.2.3.3.1 and 3.2.3.3.2 may not be applicable given that many of such substances are corrosive or irritant at concentrations < 1 %.U.K.
3.2.3.3.4.2.For mixtures containing strong acids or bases the pH shall be used as a classification criterion (see paragraph 3.2.3.1.2) since pH is a better indicator of corrosion than the concentration limits of Table 3.2.3.U.K.
3.2.3.3.4.3.A mixture containing ingredients that are corrosive or irritant to the skin and that cannot be classified on the basis of the additivity approach (Table 3.2.3), due to chemical characteristics that make this approach unworkable, shall be classified as Skin Corrosive Category 1A, 1B or 1C if it contains ≥ 1 % of an ingredient classified in Category 1A, 1B or 1C respectively or as Category 2 when it contains ≥ 3 % of an irritant ingredient. Classification of mixtures with ingredients for which the approach in Table 3.2.3 does not apply is summarised in Table 3.2.4.U.K.
[F13.2.3.3.5. On occasion, reliable data may show that the skin corrosion/irritation hazard of an ingredient will not be evident when present at a level at or above the generic concentration limits mentioned in Tables 3.2.3 and 3.2.4 in section 3.2.3.3.6. In these cases the mixture shall be classified according to that data (see also Articles 10 and 11). On other occasions, when it is expected that the skin corrosion/irritation hazard of an ingredient is not evident when present at a level at or above the generic concentration limits mentioned in Tables 3.2.3 and 3.2.4, testing of the mixture shall be considered. In those cases the tiered weight of evidence strategy shall be applied, as set out in section 3.2.2.5.] U.K.
Textual Amendments
F1 Substituted by Commission Regulation (EU) No 487/2013 of 8 May 2013 amending, for the purposes of its adaptation to technical and scientific progress, Regulation (EC) No 1272/2008 of the European Parliament and of the Council on classification, labelling and packaging of substances and mixtures (Text with EEA relevance).
3.2.3.3.6.If there are data showing that (an) ingredient(s) is/are corrosive or irritant at a concentration of < 1 % (corrosive) or < 3 % (irritant), the mixture shall be classified accordingly.U.K.
Table 3.2.3
Generic concentration limits of ingredients classified for skin corrosive/irritant hazard (Category 1 or 2) that trigger classification of the mixture as corrosive/irritant to skin
| Sum of ingredients classified as: | Concentration triggering classification of a mixture as: | |
|---|---|---|
| Skin Corrosive | Skin Irritant | |
| Category 1(see note below) | Category 2 | |
| Skin Corrosive Categories 1A, 1B, 1C | ≥ 5 % | ≥ 1 % but < 5 % |
| Skin irritant Category 2 | ≥ 10 % | |
| (10 × Skin Corrosive Category 1A, 1B, 1C) + Skin irritant Category 2 | ≥ 10 % | |
NoteU.K.
The sum of all ingredients of a mixture classified as Skin Corrosive Category 1A, 1B or 1C respectively, shall each be ≥ 5 % respectively in order to classify the mixture as either Skin Corrosive Category 1A, 1B or 1C. If the sum of the Skin Corrosive Category 1A ingredients is < 5 % but the sum of Category 1A+1B ingredients is ≥ 5 %, the mixture shall be classified as Skin Corrosive Category 1B. Similarly, if the sum of Skin Corrosive Category 1A+1B ingredients is < 5 % but the sum of Category 1A+1B+1C ingredients is ≥ 5 % the mixture shall be classified as Skin Corrosive Category 1C.
Table 3.2.4
Generic concentration limits of ingredients of a mixture for which the additivity approach does not apply, that trigger classification of the mixture as corrosive/irritant to skin
| Ingredient: | Concentration: | Mixture classified as: Skin |
|---|---|---|
| Acid with pH ≤ 2 | ≥ 1 % | Category 1 |
| Base with pH ≥ 11,5 | ≥ 1 % | Category 1 |
| Other corrosive (Categories 1A, 1B, 1C) ingredients for which additivity does not apply | ≥ 1 % | Category 1 |
| Other irritant (Category 2) ingredients for which additivity does not apply, including acids and bases | ≥ 3 % | Category 2 |
3.2.4.Hazard CommunicationU.K.
3.2.4.1.Label elements shall be used for substances or mixtures meeting the criteria for classification in this hazard class in accordance with Table 3.2.5.U.K.
| [F1Table 3.2.5 | ||
| Label elements for skin corrosion/irritation | ||
| Classification | Category 1 A/1 B/1 C | Category 2 |
|---|---|---|
| GHS Pictograms |  |  |
| Signal Word | Danger | Warning |
| Hazard Statement | H314: Causes severe skin burns and eye damage | H315: Causes skin irritation |
| Precautionary Statement Prevention | P260 P264 P280 | P264 P280 |
| Precautionary Statement Response | P301 + P330 + P331 P303 + P361 + P353 P363 P304 + P340 P310 P321 P305 + P351 + P338 | P302 + P352 P321 P332 + P313 P362 + P364 |
| Precautionary Statement Storage | P405 | |
| Precautionary Statement Disposal | P501 | ] |