Fragrance Allergen List 1 and the Percentages That Trigger It

The part of the List 1 fragrance allergen rule that trips people up isn't the concept, it's the arithmetic. Everyone understands "disclose allergens above a threshold." Fewer people sit down and actually calculate what percentage of, say, linalool their lavender-scented lotion contains once you trace it through the essential oil blend. That gap is where mistakes happen, and it's worth walking through slowly.

The two thresholds, and why they're different

Health Canada sets separate triggers depending on how long the product stays on skin:

• Leave-on products (lotions, creams, serums, leave-in conditioners): disclose above 0.001%, which is 10 parts per million.
• Rinse-off products (soap, shampoo, body wash, cleansers): disclose above 0.01%, which is 100 parts per million.

The leave-on threshold is ten times lower because prolonged skin contact raises the odds of a sensitization reaction. A rinse-off product with the same allergen concentration gets washed away in a minute or two, so the bar for disclosure is set higher.

Working through a real calculation

Say you make a rinse-off body wash with 1.5% of a lavender essential oil blend. Your supplier's documentation says the blend contains 30% linalool and 3% geraniol by weight, among other components. To find what actually ends up in your finished product:

Linalool contribution = 1.5% (use level) x 30% (proportion in blend) = 0.45%

Geraniol contribution = 1.5% x 3% = 0.045%

Both numbers sail past the rinse-off threshold of 0.01%. If this same fragrance blend went into a leave-on lotion at the same 1.5% use level, both allergens would still clear the leave-on threshold too, since 0.45% and 0.045% are both well above 0.001%.

Now compare a much lighter use case: a trace amount of essential oil at 0.05% in a rinse-off product, with the same 30% linalool blend. That gives you 0.05% x 30% = 0.015%, which still crosses the rinse-off trigger of 0.01%, just barely. Small changes in use level can flip an ingredient from "no disclosure needed" to "disclosure required," so the calculation is worth doing per product rather than assuming last year's answer still holds.

Where the numbers actually come from

You cannot eyeball this from an essential oil's common name. Lavender oil isn't a single chemical, it's a mixture, and different lavender varieties and sourcing can shift the linalool and linalyl acetate ratio meaningfully. The steps that actually work:

1. Get a certificate of analysis or full composition breakdown from your essential oil or fragrance supplier.
2. Identify every List 1 allergen present: Limonene, Linalool, Citronellol, Geraniol, Eugenol, and Coumarin are the ones to look for first, since they show up constantly in botanical fragrance materials.
3. Multiply each allergen's percentage in the blend by your use level of the blend in the finished formula.
4. Compare each result against the correct threshold for your product's leave-on or rinse-off classification.

A worked reference table

Product type	Use level of fragrance blend	Allergen % in blend	Allergen % in product	Threshold	Disclose?
Leave-on lotion	1.0%	2% limonene	0.02%	0.001%	Yes
Rinse-off soap	0.8%	1% eugenol	0.008%	0.01%	No, just under
Leave-on serum	0.3%	0.5% coumarin	0.0015%	0.001%	Yes
Rinse-off shampoo	2.0%	5% citronellol	0.1%	0.01%	Yes

Notice the second row. Small formulation tweaks, dropping the fragrance load from 0.8% to 1%, can push an ingredient from just under to just over the line. That's why this needs recalculating whenever a formula or fragrance supplier changes, not once and filed away.

Doing this math across a full product line by hand is tedious and error-prone, which is exactly the kind of repetitive, precise work Cosmetic Comply was built to carry for you. It takes the blend percentages you enter, runs the multiplication against the correct leave-on or rinse-off threshold, and flags what needs to go on your CNF and your label before the April deadline, rather than after a customer or regulator notices first.