In mammals 1,2-ethanediol (1) is either excreted unaltered or may be oxidized by alcohol dehydrogenase and aldehyde dehydrogenase to glycolic aldehyde (2) and glyoxylate (3). End product of this pathway is oxalate (4). The mammalian organism may be adversely affected by precipitation od calcium oxalate crystals and by cytotoxicity of glycolic aldehyde (2).