The recalled dietary supplement l-tryptophan induced a peculiar acute eosinophilic lung disease with parenchymal opacities, pleural effusions and eosinophilic vasculopathy called the eosinophilia myalgia syndrome (see under X). A chronic debilitating form could ensue. An impurity formed during synthesis at one plant (peak-E or EBT) may be the cause for the syndrome. L-tryptophan is no longer generally available