Summer Spoils Your Skincare. The Preservatives That Stop It Are Among the Most Regulated Ingredients in Cosmetics.
Summer is when your skincare is most likely to spoil. Heat and humidity accelerate the growth of bacteria, mold, and yeast in any product that contains water — a face cream opened daily in a steamy bathroom is a small ecosystem. Preservatives are what stop that. Without them, a contaminated product can cause skin or eye infections while still looking and smelling normal. So preservatives are not the villains the "preservative-free" marketing implies. They are doing necessary work, especially in the season when contamination risk peaks. But the most effective ones are also among the most regulated ingredients in cosmetics — because effectiveness against microbes and safety on human skin pull in opposite directions. We queried our database of 21,796 ingredients across 10 markets and pulled the major preservatives. The pattern is consistent: the better a preservative works, the more tightly it tends to be capped. Methylisothiazolinone: restricted in nine markets Methylisothi...