S,S'-Ethylenebis(glutathione)-d4 is labelled Labelled S,S'-Ethylenebis(glutathione), a haloethane-glutathione conjugate formed via GSH transferases. S,S'-Ethylenebis(glutathione) formation is used to study the polymorphism in glutathione conjugation activity of human erythrocytes towards ethylene dibromide.