Alongside Section 2, Section 3 of the Safety Data Sheet (SDS) is one of the most critical parts of the document. It provides users with essential information about the composition of the product, which—when combined with the hazard data from Section 2—offers a detailed overview of the chemical substance or mixture from a risk management perspective. This data serves as the basis for assessing storage requirements, material incompatibilities, and potential hazardous reactions.

The information in Section 3 must be provided in accordance with specific legal requirements. This is particularly important for mixtures, where the selection and disclosure of individual ingredients must follow defined rules. At the same time, companies often aim to protect the proprietary composition of their products. It is therefore essential to include only the information that is legally required, without disclosing more than necessary.

Subsection 3.1 – Substances: SDS for Single Chemical Substances

This subsection is completed when the product is a chemical substance, regardless of whether it is mono- or multi-constituent, as long as it meets the definition of a substance under the REACH Regulation.

Interestingly, subsections 3.1 and 3.2 are the only parts of the SDS that may be omitted, depending on whether the product is a substance or a mixture.

If the product is a substance, the following must be provided:

• The chemical name, in line with IUPAC nomenclature,

• An appropriate identification number (CAS, EC, or index number), depending on availability.

Subsection 3.1 is usually straightforward to complete and tends to be less complex than Subsection 3.2 for mixtures.

Subsection 3.2 – Mixtures: SDS for Chemical Mixtures

If the product is a mixture (as defined by REACH), detailed information must be given for each relevant substance it contains. Choosing which ingredients to list is a key step in SDS preparation and is governed by strict regulatory rules.

For each substance that meets the criteria for disclosure, the following must be included:

• The chemical name (according to IUPAC),

• Appropriate identifiers (CAS, EC, or index number),

• Classification under the CLP Regulation,

• Concentration range (by weight),

• If applicable: specific concentration limits, ATE values, or M-factors.

Accurate preparation of Section 3 is crucial for the overall compliance of the SDS. It also has a direct impact on other key sections, including Section 2 (hazard identification), Section 6 (accidental release measures), Section 7 (handling and storage), Section 8 (exposure controls and PPE), and Section 10 (stability and reactivity).

Summary: The Role of Section 3 in SDS Compliance

Section 3 plays a foundational role in identifying the chemical composition of substances and mixtures. Providing clear, accurate, and compliant information on ingredients:

• supports safe use and handling,

• enables effective risk management,

• ensures regulatory compliance.

A well-prepared Section 3 allows users to make informed decisions regarding the safe use of chemical products and forms the basis for consistent and legally sound SDS documentation.