The safety of butylphenyl methylpropional has been evaluated by the Research Institute for Fragrance Materials Expert Panel (REXPAN). Based on this evaluation, an International Fragrance Association (IFRA) Standard has been established. The IFRA Standard restricts the use of butylphenyl methylpropional in fragrances because of potential dermal sensitization.
A research article published in the Flavour and Fragrance Journal assessed the risk of sensitization for 26 fragrances in 5451 products from 2007 to 2009. As an estimate of sensitization risk, the sensitization exposure quotient (SEQ), was calculated as the quotient of the relative frequency of sensitization and the relative frequency of use/labelling. The SEQs (the risk) varied greatly, with butylphenyl methylpropional at the bottom of the list, indicating a very low risk of sensitization.
Since there is risk for sensitization with butylphenyl methylpropional, its presence must be indicated in the list of ingredients if the product contains more than 0.001% and is meant to be left on skin. It also must be listed if the product contains more than 0.01% and is meant to be rinsed, such as with cleansers and shampoos.
Due to the possibility of an allergic reaction, those with sensitive skin should try to butylphenyl methylpropional or perform a patch test with any product containing this ingredient.
References: Wikipedia, “Lillial”, Flavour Fragr. J., 2015, 30: 208–217, Cosmetics Info, “Butylphenyl methylpropional”, European Commission Scientific Committee on Consumer Safety “OPINION ON Butylphenyl methylpropional (BMHCA)”, 2016.