Here’s a list, drawn from this list, of the 1980s UNSCRs which refer, directly or indirectly, to CW use during the Iran-Iraq war. I say “indirectly,” because at least one doesn’t mention CW by name, but does refer to UNSCR 598, which contains preambular language deploring the use of CW.
I won’t swear that this is comprehensive, but there you go.