Lilial has been phased out due to a link to infertility, although Michelle Wong, the science educator and cosmetic chemist behind content platform Lab Muffin, points out that the link was identified in a study of rats. “There’s no evidence lilial has ever caused infertility in humans,” she wrote in a post.

No. 3 Hair Perfector included a small amount of lilial in its formula—it accounted for .011% of the formula to be exact, according to Olaplex—and the brand stressed the product has “undergone a rigorous safety assessment” to ensure it’s safe for people. However, it revealed in a statement to Fashionista that, “Out of an abundance of caution, Olaplex proactively removed lillial from our No. 3 Hair Perfector globally.”

In light of the controversy over Olaplex, for the latest edition of our series posing questions relevant to indie beauty, we decided to ask ten beauty entrepreneurs and executives the following questions: What prompted you to reformulate products in the past, and what lessons did you learn from the process?