Overview

Toxic Oil Syndrome or simply Toxic Syndrome was the name given to an unusual disease outbreak in Spain in 1981. Its first appearance was as a lung disease, with unusual features: though the symptoms initially resembled a lung infection, antibiotics were ineffective. The disease appeared to be restricted to certain geographical localities, and several members of a family could be affected, even while their neighbours had no symptoms. Following the acute phase, a range of other chronic symptoms were apparent.

The cause was traced to the consumption of rapeseed oil that had been intended for industrial rather than food use. It had been imported as cheap industrial oil by the company RAPSA at San Sebastián, handled by RAELCA and refined by ITH in Seville. It was sold as "olive oil" by street vendors at weekly street markets and was therefore used on salads and for cooking. The commonly-accepted hypothesis states that toxic compounds, derived during the refinement process, used to remove the aniline and to denature oils, intended for industrial use was responsible.

Once the origin of the syndrome was realised, public health officials organized an exchange programme, whereby those who had bought the oil could exchange it for pure olive oil, thereby quickly ending the outbreak.

The conclusion that oil was the cause for TOS is based on strong epidemiological evidence, since up to now, experimental studies performed in a variety of laboratory animals have failed to reproduce the symptoms of human TOS. None of the in vivo or in vitro studies performed with toxic-oil-specific components, such as fatty acid anilides and esters of PAP, have provided evidence that these markers are causally involved in the pathogenesis of TOS.

The fact that the first cases of the syndrome were located in Madrid, near the U.S. military base in Torrejón de Ardoz, and the secrecy surrounding the huge investigations, spread the idea of a conspiracy. Also, several of the affected by the TOS claim they never consumed that oil. Although the oil was mainly sold on street markets, a considerable percentage of the patients were upper class. Another theory suggests the toxic reaction was triggered by organophosphate compounds used in pesticides, since it was found in almost all the patients tested for them.