Summary of when a mixture needs to be classified
Mixtures need to be classified for CLP when they are made within the EU, or imported from outside the EU. It is the responsibility of the formulator or importer to classify the mixture for CLP before placing it on the EU market.
As mixture classifications are not publicly available in the way that substance classifications are (and would be of limited value anyway), mixture classifications are mainly made from scratch, rather than using an existing classification. This means that many more new mixture classifications are made than new classifications for substances.
To classify a mixture for CLP, you need to have the full list of ingredients, including the identify and % w/w (or % v/v) of all component substances. It is helpful to have the CLP classification of all component substances as well, although if this is not available, you will have to classify the component substances for CLP first, before you can classify the mixture for CLP.
Mixtures are classified on the basis of the hazards of their component substances, together with any new hazards generated by the mixture.
Like substances, physical hazards of mixtures can be ruled in or out on the basis of the chemistry of the mixture, and where these are suspected they can be tested for.
Unlike substances, health and environmental hazards of mixtures can be calculated on the basis of the hazards of the component substances, and testing for these hazards should only be undertaken in rare circumstances, e.g. where a mixture of toxic substances is suspected of being more hazardous than the calculation method indicates. Expert help may be required to decide whether these types of test are required.