MOCS

MOCS substances are defined in the new CLP regulation on the classification, labelling and packaging of chemical substances and mixtures. According to the definition in the legal act:

multi-constituent substance (MOCS) – is a substance containing more than one component.

Substances classified as MOCS are substances:

  • containing at least one primary component and identified impurities or additives,
  • multi-constituent substances,
  • substances of unknown or variable composition, complex reaction products or biological materials (UVCB).

Classification of MOCS

The new Article 5.3 of the CLP Regulation clarifies the rules for the classification of substances containing more than one constituent. The aim of introducing these rules is to ensure that MOCS are appropriately classified based on the seriousness of the hazards associated with the known components.

Substances containing more than one ingredient will be assessed both: on the basis of the information available for the known ingredients and on the basis of the information for the MOCS. From a toxicological point of view, MOCS are similar to mixtures of two or more chemical substances, therefore the methods for classification and labelling of MOCS will be similar to the rules for classification of chemical mixtures.

A classification for MOCS based on data of known components is adopted if the component substances demonstrate:

  • germ cell mutagenicity,
  • carcinogenicity,
  • reproductive harm,
  • endocrine disruption to human health,
  • endocrine disruption to the environment,

as well as for substances:

  • persistent, mobile and toxic (PMT),
  • persistent, bioaccumulative and toxic (PBT),
  • very persistent and very mobile (vPvM),
  • very persistent and very bioaccumulative (vPvB).

In such a situation, even if the MOCS itself does not have any of the above properties, but contains components belonging to the mentioned categories in relevant concentrations above the classification threshold, these should be taken into account to determine the overall classification of the MOCS.

Example: If the MOCS contains a carcinogenic component above a certain concentration level, the entire MOCS should be classified as a carcinogen.

The CLP Regulation does not impose any obligation to conduct new animal tests. Classification should be based on currently available data, using a weight of evidence assessment.

Exemption

A new clause worked out by industry companies allows for exemption from classification in specific cases. The clause may apply to plant extracts that are not chemically modified, including essential oils. This provision protects European producers of essential oils if scientific data shows that the classification of an essential oil based on individual components is not scientifically justified.

Substance classification: https://ekotox.eu/classification-of-dangerous-chemical-substances/