The IFRA Standards sets rules for the use a range of fragrance materials based on scientific assessment. These rules include:
Prohibition: a ban on the use of a material
Restriction: rules on the maximum quantity to be used and/or the products in which certain materials can be use
Specification: other conditions on the type of material (such as purity criteria).
In all cases the final responsibility for the safe use of any fragrance material put on the market rests with the company supplying the material.