Glossary / Identifiers
Substance
A substance is a chemical element or compound, either natural or manufactured, including any additives needed to preserve its stability and any impurities that result from the process. Unlike a mixture, a substance is treated as one material with its own identifier.
Explanation
In regulation, the word substance has a narrower meaning than in everyday speech. Pure water, sodium chloride, and acetone are substances. A can of paint is not, because it contains several ingredients.
Substances can usually be identified by a single CAS number and, in the EU, an EC number. That makes them easier to track across databases and exposure-limit lists than mixtures, which have no single number.
The definition allows small amounts of other material. A substance as sold may contain stabilizers, which keep it from degrading, and impurities from manufacture, which cannot practically be removed. These count as part of the substance as long as they do not change its composition in a significant way.
On the SDS, a substance entry in Section 3 may show the chemical name and number and the impurities that matter for hazards. For regulatory programs such as REACH and TSCA, the substance is the unit that is registered or listed, which is why identity matters so much.
The distinction affects how you read a sheet: a substance sheet describes one material, while a mixture sheet describes a blend whose hazards come from several parts.
What to do and watch for
- Use the CAS number to confirm which substance a sheet covers.
- Check Section 3 for impurities or stabilizers flagged as hazardous.
- Do not assume a trade-name product is a single substance.
Where it appears on an SDS
- Section 3: Composition / information on ingredients. For a substance, this section gives the chemical name, CAS number, and any impurities or additives that contribute to the hazard.
- Section 1: Identification. The product identifier may be the chemical name itself when the product is a single substance.
SDS content and wording vary by supplier. This page is general reference and does not replace the current SDS for your product.