Specific Concentration Limits / M-Factor

Specific Concentration Limits / M-Factor

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Specific concentration limits (SCL) and generic concentration limits are limits assigned to a substance indicating a threshold at or above which the presence of that substance in another substance or in a mixture as an identified impurity, additive or individual constituent leads to the classification of the substance or mixture as hazardous.

The SCL concept allows a fine tuning of the contribution of certain hazardous substances to the classification of mixtures based on the potency of the substances, as well as a classification of other substances containing these substances as impurities, additives or individual constituents. The SCL concept is only applicable to health hazards. For physical hazards, classification must be established on the basis of test data for the respective mixture, where applicable.

'M-factor' means a multiplying factor. It is applied to the concentration of a substance classified as hazardous to the aquatic environment acute category 1 or chronic category 1, and is used to derive by the summation method the classification of a mixture in which the substance is present.

Where there is no harmonised M-factor listed in Annex VI to CLP for a specific substance, manufacturers, importers and downstream users should set an M-factor themselves when classifying substances for acute aquatic toxicity category 1 or chronic aquatic toxicity category 1.