The American Chemistry Council’s Aliphatic Diisocyanates Panel prepared this guidance to provide information about important health and safety considerations when working with aliphatic diisocyanates (ADIs). This paper provides additional information to what is contained in your supplier’s Safety Data Sheets (SDS), which are a main source of information for handling ADIs. Throughout this document, the term ADI refers to aliphatic diisocyanates, specifically hexamethylene diisocyanate (HDI), methylene dicyclohexyl diisocyanate or hydrogenated MDI (HMDI) and isophorone diisocyanate (IPDI), and their polyisocyanates. The term ADI polyisocyanates is used to address partially polymerized products from ADI monomers.