In May 1981, a new disease called Toxic Oil Syndrome (TOS) appeared in Spain, eventually affecting over 20,000 people and killing about 350. The cause was traced to adulterated rapeseed oil that had been denatured with aniline for industrial use but was illegally refined and sold as olive oil. The epidemic was a national catastrophe and a major challenge to the Spanish healthcare system.

The Toxic Oil Syndrome was a defining event in modern Spanish history, and it was the subject of numerous literary works, including poetry, novels, and investigative journalism. Writers explored the human tragedy, the failure of regulation, and the social inequalities that the epidemic exposed. The incident also inspired a wave of food safety activism and literature in Spain and beyond.