Allergen Declaration vs Safety Data Sheet: The Difference

Someone forwarded me their supplier's SDS last week and asked, "Doesn't this cover my allergen disclosure requirement?" It doesn't, and the mix-up is common enough that it's worth spelling out exactly why these two documents exist for different reasons and answer different questions entirely.

What an SDS is actually for

A safety data sheet has 16 standardized sections, and it exists primarily to communicate handling, storage, and hazard information, mostly for workers, transporters, and emergency responders, not end consumers evaluating a finished cosmetic. Section 3 lists composition, which is where people usually go looking for ingredient information. But an SDS describes a raw material or a mixture from a workplace-safety and transport-safety lens. It tells you things like flammability, what to do if it's spilled, what protective equipment handling it requires, and hazard classifications under whatever chemical safety framework applies.

None of that is the same question as "does this ingredient need to be individually named on a consumer label because it's a recognized allergen above a certain concentration."

What an allergen declaration is actually for

A fragrance allergen declaration exists to inform the end consumer, specifically people with known sensitivities, that a particular allergen is present above a defined threshold, so they can make an informed choice before they put the product on their skin. The named substances tend to include common fragrance allergens like Limonene, Linalool, Citronellol, Geraniol, Eugenol, and Coumarin, which show up naturally in a wide range of essential oils. The threshold that triggers disclosure is concentration-based, and it can differ between leave-on and rinse-off product categories, and between one market's regulatory framework and another's.

That's a consumer-facing labeling question, built around a specific list of named substances and specific concentration triggers. An SDS was never designed to answer it.

Side by side

	Safety Data Sheet	Allergen Declaration
Primary audience	Workers, transporters, emergency responders	End consumers
Purpose	Handling, storage, hazard, transport safety	Informing sensitive consumers of allergen presence
Structure	16 standardized sections	Named substances above a concentration threshold
Composition detail	Section 3, often at supplier or raw-material level	Finished-product concentration of specific named allergens
Legally required for	Workplace and transport chemical safety compliance	Cosmetic label and, in some markets, product notification
Does it map trade names to INCI?	Not necessarily	Should, since disclosure has to use recognized allergen names

Where the gap actually bites

The real danger isn't confusing the documents in the abstract, it's assuming that because your supplier gave you a thorough-looking SDS for a fragrance blend, you've covered your allergen disclosure obligation for the finished product. You haven't. The SDS might mention a component in section 3 in general terms, but it won't do the work of calculating that component's actual concentration in your finished cosmetic, checking it against a consumer disclosure threshold, or telling you whether it needs to appear by name on your label or in a notification filing.

That calculation, taking a blend's use level in your formula and multiplying it by the allergen's percentage within the blend, is exactly the kind of finished-product math an SDS was never built to do for you.

What to actually pull from each document

Use the SDS for what it's good at: hazard classification, handling precautions, and workplace safety data. Use it as one input, alongside the supplier's technical data sheet, when you're trying to identify which named allergens might be present in a fragrance or essential oil blend. But do the actual disclosure calculation separately, based on the real concentration in your finished product against the relevant market's threshold, rather than treating "the SDS didn't flag it" as equivalent to "there's nothing to disclose."

If you're working through this for a Canadian filing, Cosmetic Comply's ingredient mapping carries blend components and their percentages through to the finished-product level automatically, which is the piece that neither an SDS nor a quick label glance was ever going to do for you.