A synthetic fragrance ingredient with a strong floral scent used in many types of cosmetic products. Its use in cosmetics is restricted due to concerns over irritation and allergic reactions. This ingredient is also known as p-tert-butyl-alpha-methylhydrocinnamic aldehyde. The presence of butylphenyl methylpropional must be indicated in the list of ingredients when the product contains more than 0.001% and is meant to be left on skin or no more than
0.01% in products that are rinsed (like cleansers and shampoos). Sources for the previous info: Contact Dermatitis, May 2011, pages 265-272; and CosmeticsInfo.org.