The 0.01 Percent Rinse-Off Allergen Trigger Explained

Somebody always asks why a shampoo gets more fragrance allergen leeway than a body lotion, as if it's an arbitrary rule. It's not. It comes down to how long the ingredient actually sits on skin, and the math behind that difference is worth understanding rather than just memorizing.

The two numbers

Canada's fragrance allergen disclosure sets two different triggers depending on product type. Above 0.001% (10 ppm) in a leave-on product means you disclose. Above 0.01% (100 ppm) in a rinse-off product is the trigger there instead. That's a tenfold difference, and it's not a rounding coincidence. It reflects a genuinely different exposure scenario.

Why rinse-off gets more room

A leave-on product, think body lotion, face cream, leave-in conditioner, stays on the skin for hours. The allergen is in continuous contact with skin the entire time the product is on you, which for a lot of products is effectively all day or all night. A rinse-off product, shampoo, body wash, bar soap, is applied, worked in for a short period, and then washed away. The actual skin contact time with the allergen is measured in minutes, not hours, and a meaningful portion of whatever's in the product gets rinsed down the drain before it has much chance to interact with skin at all.

Regulators build allergen thresholds around this kind of real-world exposure difference. Ten times more allergen in a rinse-off formula represents a comparable actual exposure risk to a tenth as much allergen in a product that stays on skin all day. The numbers aren't identical because the exposure isn't identical.

What this looks like in a real formula

Say you're formulating a body wash with a citrus-forward fragrance blend containing limonene, one of the more common allergens precisely because it occurs naturally in citrus oils. If your calculated limonene concentration in the finished body wash comes out around 0.008%, that's below the 0.01% rinse-off threshold, so no disclosure trigger there.

Take that same fragrance blend at the same use level and put it into a leave-on body lotion instead. Now you're checking against the 0.001% threshold, and 0.008% sails well past it. Disclosure is required on the lotion even though the raw fragrance blend and use level are identical to the body wash. Product type, not the fragrance itself, decides the outcome.

A common mistake: assuming one calculation covers a whole line

Brands that sell a coordinated product line, a shampoo, conditioner, and leave-in treatment in the same scent, sometimes assume that if the shampoo cleared the fragrance without needing disclosure, the whole line is fine. It isn't. The leave-in treatment in that same line needs to be checked against the leave-on threshold separately, because it's a completely different exposure category even though it shares a fragrance supplier and a marketing story with the rinse-off products next to it on shelf.

Practical steps for a rinse-off formula

1. Confirm your product genuinely qualifies as rinse-off. A "leave-in conditioning shampoo" or a wash-off mask with extended dwell time instructions can blur this line, so be honest about actual use instructions, not just the product category name.
2. Calculate each fragrance allergen's finished-product concentration the same way regardless of threshold, full precision, rounded only at the end.
3. Compare against 0.01% (100 ppm) rather than the tighter leave-on figure.
4. Remember List 1 fragrance allergens become mandatory on the CNF and label on April 12, 2026, with the expanded List 2 following on August 1, 2026, so both rinse-off and leave-on products need this worked out well before those dates, not scrambled together at the deadline.

Where this fits into your filing

Getting the rinse-off versus leave-on distinction right, and then doing the concentration math correctly against whichever threshold actually applies, is exactly the kind of detail that's easy to get subtly wrong across a multi-product line. Cosmetic Comply carries supplier blend percentages through to finished-product concentrations automatically and flags allergens against the correct threshold for the product type you're filing, with a real reviewer checking anything that lands close to the line before the CNF submission goes out.