The toxic oil syndrome (TOS, 1981): from the disease towards a toxicological understanding of its chemical aetiology and mechanism.

In Spain early in May 1981, 20,000 people became ill with a severe acute respiratory illness. The eosinophilia and subsequent myalgia, scleroderma and muscle wasting indicated a unique disease entity. Epidemiological evidence linked the disease with the consumption of oils containing "refined" aniline denatured rape seed oil. Ten years after the explosive appearance of this disease (approximately 350 deaths and over 1000 in the chronic phase) the clinical and pathological description is now well established. The aetiological agent(s) in the food oil are unknown and the mechanism(s) of pathogenesis are uncertain. There is no experimental animal model. A new disease, Eosinophilia Myalgia Syndrome (EMS) which appeared late in 1989 in the USA, is due to the consumption of impure 1-tryptophan. There may be similarities between the diseases and the aetiological agents for TOS and EMS: possibilities for future research will be discussed. Underlying the time lag for solution of this problem is a lack of knowledge of the basic biology involved.