Current approaches for hazard identification and classification of substances introduced into the environment are largely based upon persistence, bioaccumulation, and toxicity (PBT) measurements. However, there are problems with the application of PBT to metals and metal substances. Persistence and bioaccumulation, as presently formulated, frequently do not adequately consider important metal physicochemical considerations such as speciation, complexation, precipitation, dissolution, transformation, and sedimentation. Further, toxicity, as presently formulated, frequently does not adequately consider bioavailability and too often uses the lowest acceptable toxicity value instead of an integrated approach such as a species sensitivity distribution.