Cyclic acid anhydrides are widely used in the chemical industry in the manufacture of polyester and alkyd resins and plasticizers and as epoxy resin hardeners. Acid anhydrides are irritants and are especially potent sensitizing agents. This document deals with the following anhydrides of concern: phthalic anhydride, trimellitic anhydride, maleic anhydride, hexahydrophthalic anhydride, methyl hexahydrophthalic anhydride, methyl tetrahydrophthalic anhydride, tetrahydrophthalic anhydride, tetrachlorophthalic anhydride, pyromellitic dianhydride, himic anhydride, succinic anhydride, dodecenylsuccinic anhydride, chlorendic anhydride, and tetrabromophthalic anydride.Chemical safety cards for several cyclic acid anhydrides, produced by the International Programme on Chemical Safety (IPCS) are reproduced in this document.