It can be challenging for manufacturers and purchasers to avoid chemicals of concern. The Six Classes approach is one helpful conceptual tool that the Green Science Policy Institute developed and has been promoting for over a decade. To prevent regrettable substitutions, this approach suggests avoiding the entire classes of per- and polyfluoroalkyl substances, antimicrobials, flame retardants, bisphenols and phthalates, some solvents, and certain metals. When evaluating a chemical of concern, the Institute emphasizes the importance of asking whether it is truly necessary and worth the potential for harm. For example, given the substantial evidence that over-the-counter antibacterial soaps provide no health benefit over plain soap and water, there is no need to look for safer antibacterial active ingredients for this product category. However, in some cases a particular function is necessary. For example, solvents provide an essential function for many products and processes. But solvents vary greatly by performance, toxicity and volatility. There are several tools that offer a systematic approach.