response relationship had not been demonstrated in any of the case-control studies
performed. Years later and after a laborious and careful selection of oils, a case-control
study was developed which resulted in a step forward in the knowledge of the real
etiology. An oil container with a characteristic shape and linked to a specific company
demonstrated a relationship between the concentration of chemical compounds in the
oleyl-anilide and the log of Odds Ratio. This study was known as “Toxi-Epi study”.
EM, Bernert T, Posada de la Paz M, et al. Chemical correlates of pathogenicity of oils
related to the toxic oil syndrome epidemic in Spain. Am J Epidemiol