Mercury poisoning in two patients with tertiary syphilis from the Ca’ Granda hospital (17th‐century Milan)

Syphilis was a widespread infectious disease in 17th-century Italy, commonly treated with mercury-based ointments and fumigations. Few reports exist on the analysis of abnormally high Hg levels in bone as a result of exposure to mercury-containing anti-syphilitic medicine. In this research, two crania recovered among the 2.9 million commingled bones resting under the crypt of the former hospital of the poor of Milan were submitted to pathological, radiological and toxicological analysis. The crania showed gummatous lesions characteristic of tertiary syphilis and inductively coupled plasma mass spectrometry (ICP-MS) analysis revealed over the double values of Hg in bone relative to that of the control sample. Archival documentation confirms the presence and use of mercury-based treatments in the pharmacy of the hospitals of Milan. Consequently, the individuals probably came into contact with mercury as a treatment for syphilis, confirming its medical use in 17th-century Milan and strengthening our knowledge of the history of medicine.