Product Categories, Application Levels and Exposure
Why category matters
The same compound can be safe in a rinse-off product and unsafe in a leave-on product because exposure differs. Categories typically distinguish fine fragrance, leave-on cosmetics, rinse-off products, household products, and products exposed to sunlight. Each category has its own maximum use level in the Standards. The trap is using a single "safe" number across categories, or assuming a body lotion and a shower gel share a limit.
Application level calculations
The application level is the concentration of the fragrance compound in the finished product. The concentration of a restricted ingredient in the finished product equals the compound level multiplied by the ingredient's concentration in the compound. Candidates must be fluent in this two-step multiplication and in working backwards to find the maximum permitted compound level.
Exposure factors
Exposure depends on the amount used, the frequency, the area of skin, and whether the product is rinsed off. Sun-exposed products add a phototoxicity dimension. Questions often present a scenario and ask which category applies - for example, a scented body lotion with SPF is a sun-exposed leave-on product, not simply a cosmetic.
Worked example
A compound contains 8% of a material limited to 0.05% in leave-on products. Maximum compound level = 0.05 ÷ 0.08 = 0.625%. If the brief calls for 1% compound, the formula must be reformulated or the material reduced. For a rinse-off product with a 0.5% limit, the same compound could be used at 6.25%.
Traps
Watch for category definitions that hinge on how the product is used rather than what it is called. A "hair mist" may be leave-on; a "cleansing water" may be rinse-off. Always confirm the intended use, not the marketing name.