Dear Sruthi
don't know what you mean by using this sentence: "the Class a given material belongs to is changed, "
I try it the other way around: in SAP EHS you can prepare e.g. Workflows if needed. On the top you can implement MSDS regeneration if needed. There is no general best practise available to handle changes in EHS. Therefore there is no answer to your question. Any company handles it different (either using SAP standard tools or own developed one)
C.B.