When the CNF Asks for a CAS Number and Where to Find It

You're halfway through filing a Cosmetic Notification Form and you hit a field asking for a CAS number on your shea butter, and suddenly the whole thing stalls. It happens constantly. Makers know their formula cold, they know their suppliers, but CAS numbers live in a different world of paperwork that most small-batch producers never had to touch before they started filing with Health Canada.

Here's the short version of what a CAS number actually is and how to track one down without guessing.

What a CAS number is doing on the form

A CAS number is a Chemical Abstracts Service registry number. It's not a regulatory approval code and it's not unique to Canada. It's simply a unique identifier assigned to a specific substance so that everyone in the world, from a supplier in Germany to a regulator in Ottawa, is talking about the exact same chemical. Two suppliers can call their raw material something different, but if it's the same substance it carries the same CAS number.

On the CNF, the CAS number sits alongside the INCI name for each ingredient. The INCI name tells Health Canada what the ingredient is in standardized cosmetic nomenclature. The CAS number backs that up with an unambiguous chemical identity. You're not choosing one or the other. The system wants both where a CAS number exists.

Where CAS numbers actually come from

You almost never need to look this up cold. The information is already sitting in documents you should have anyway.

• The supplier's safety data sheet. Section 3 of an SDS is Composition and Information on Ingredients, and this is where CAS numbers for the substance and any listed components live.
• The supplier's technical data sheet or spec sheet. Many suppliers put the CAS number right next to the INCI name on the product spec.
• Direct request to the supplier. If neither document has it, ask. A supplier selling into the cosmetic trade should be able to hand you a CAS number for anything with one, and this is a completely normal ask.
• INCI dictionaries and ingredient databases, useful for cross-checking what a supplier gives you, though the SDS is still your primary source of record.

If you're using a supplier blend, like an emulsifying wax or a preservative system sold under a trade name, remember the CAS number field applies to each individual component after you've expanded the blend, not to the trade name itself. Trade names never appear on the filing. You map the blend to its component INCI names, and each of those components may carry its own CAS number.

When there genuinely isn't one

Some ingredients don't have a CAS number, and that's fine, it's not a mistake on your part. Many botanical extracts, especially complex ones like an infusion or a whole-plant extract, are variable natural mixtures rather than single defined substances, so no single CAS number applies. Some ingredients also carry more than one CAS number historically, because they were registered more than once under slightly different descriptions before the nomenclature caught up.

In practice this means:

Situation	What to do
Ingredient has one CAS number	Enter it exactly as the supplier lists it
Ingredient has multiple CAS numbers	Use the one from your specific supplier's documentation for that lot
Botanical extract with no CAS number	Leave the field blank or note "not applicable," this is expected for many extracts
Supplier blend	Expand to components first, then find CAS numbers for each component individually

A quick sanity check before you submit

Before you file, do a fast cross-reference: does the INCI name on your ingredient list match the substance the CAS number actually points to? Mismatches happen when a spec sheet gets copied from an old formulation or when a supplier updates a blend's ratio without updating the paperwork. If a supplier's CAS number looks off, generic solvent numbers on a specialty extract, for instance, it's worth a quick email before you build it into your filing.

It's also worth remembering that concentration matters just as much as identity here. The CNF wants the INCI name, the CAS number where one exists, and the concentration or concentration range in the finished product. Getting the identity right and the percentage wrong is still an incomplete filing.

This is exactly the kind of detail that eats time when you're doing it by hand for a full formula, especially once you're expanding two or three supplier blends into their real components. Cosmetic Comply automates that matching step, pulling INCI names and CAS numbers from your ingredient list and supplier documentation, expanding blends into their real component percentages, and flagging anything that needs a human look before the notification goes in.