The latest proposals for changes to the classification of mutagenic substances, prepared by the European Union, have received broad support from the UN Sub-Committee of Experts on the GHS. If adopted, they could significantly impact the way substances are classified and how chemical safety data sheets (SDS) are prepared.

New Approach to the Classification of Mutagens

Under the current CLP Regulation, mutagenic substances are classified into three categories:

• Category 1A – for substances that cause heritable mutations based on epidemiological evidence in humans;

• Category 1B – for substances that cause mutations in germ cells of mammals or humans in laboratory studies;

• Category 2 – for substances suspected of causing mutagenic effects, mainly based on results from tests in somatic cells. Positive evidence from in vivo tests in somatic cells is accepted if supported by in vitro mutagenicity data.

The proposed changes include:

• Expanding Category 1A to include substances that are mutagenic in human germ cells, which are currently covered under Category 1B;

• Modifying the criteria for Category 1B to also include somatic cell mutagens, provided there is evidence that the substance or its metabolites reach the gonads.

The new criteria for Category 1B would no longer require direct evidence of mutations in germ cells.

What Does This Mean for Safety Data Sheets?

A change in substance classification may result in the obligation to update many SDSs—especially those that currently include a Category 2 mutagenic classification. Once the new rules are in force, these substances may be reclassified under Category 1B, which entails more serious legal and informational consequences, as well as lower concentration limits for classifying mixtures containing these substances.

Examples of potential changes in SDSs and other documentation:

• New classification in Section 2 of the SDS;

• Required updates to labels and hazard communication;

• Need to include the new classification in exposure scenarios;

• Notification of classification changes to ECHA and/or relevant national authorities.

Classification Gap and the Need for Change

The EU proposals aim to address a gap in the current classification system. At present, mutagens acting on somatic cells are only classified as suspected (Category 2), even when there is evidence of their presence in the gonads. The new rules would make classification more accurate, and SDSs would better reflect the actual level of risk.

Next Steps

The changes were positively received at the July meeting of the GHS Sub-Committee. Before the new criteria become binding, they will undergo review by the OECD Expert Group on Genotoxicity. In parallel, discussions are ongoing about the potential creation of a new hazard class for mutagenicity in the GHS system. While the proposals are still under review, it is essential to closely monitor their progress and watch for their possible integration into EU legislation.