Alta Valle del Tevere, in Central Italy, is one of the European areas where tobacco farming is most developed. But Alta Valle del Tevere is also one of the areas where the incidence and the death rate of stomach cancer are higher than the regional and national average rate. According to many local citizens, this double feature intersects in the supposed dangerousness of the chemical products used for tobacco farming. This article focuses on the genealogy, the political management and the effects of this “rumour”. Taking into consideration local business, political and healthcare management, this paper analyses the elements determining the moral economy of the “tolerance threshold” about the supposed link between tobacco farming and oncological incidence.