 The (R,S) and (R,R) stereoisomers are less biodegradable, whereas the (S,S) stereoisomer has been shown to be very effectively biodegraded even in highly polluted soils.EDDS was first synthesized from maleic acid and ethylenediamine.Some microorganisms have been manipulated for industrial-scale synthesis of (S,S)-EDDS from ethylenediamine and fumaric acid or maleic acid, which proceeds as follows