The Clinica del Lavoro of Milan provided several contributions to industrial hygiene and occupational toxicology during the twentieth century.

Describe the first years of the laboratory of industrial hygiene of Milan through three figures who played a leading role: Enrico Carlo Vigliani, Nicola Zurlo and Gianmario Cavagna.

Scientific literature of the period 1948-1970 was investigated, also interviewing first-hand witnesses of that period.

Enrico Vigliani was the first European scholar to understand the importance of a laboratory of industrial hygiene within his institution. Thanks to the support of private (Montecatini) and public (INAIL) institutions he succeeded in creating a laboratory in 1948. Nicola Zurlo, who directed this structure in the first thirty years, conducted innovative studies on chronic mercury intoxication, lead intoxication and silicosis, designing and creating instruments for capturing and analyzing atmospheric dust and protection devices. He conducted analysis of the health effects of organophosphorus insecticides and started to study the air pollution. Zurlo also provided an epistemological and methodological content to the discipline. Gianmario Cavagna, one of the first Italian toxicologists, contributed to the discovery of the origin of fevers caused by the inhalation of metal fumes and to the studies on the pathogenesis of byssinosis, hypothesizing a role of bacterial endotoxins in the genesis of this disease.

The contributions provided by these three protagonists to industrial hygiene and occupational toxicology were relevant and made in those years the Clinica del Lavoro of Milan as a landmark, not only in Italy but also abroad.