Removing a chemical of concern is only the first test; the replacement must also perform without introducing another problem. Three lightning talks put PFAS-free materials, flame retardants, and lower-footprint chemistries under scrutiny. What evidence distinguishes a better alternative from a regrettable substitution? And when does an incremental improvement deliver meaningful progress on safety, cost, and life-cycle impact? • Which substances are hardest to replace in food and beauty packaging, sportswear, and electronics? • Can PFAS-free and other alternatives match performance, and what evidence prevents regrettable substitution? • When does an incremental improvement count as progress?