Forshufvud, S., Smith, H. & Wassén, A. Arch. Toxikol. (1964) 20: 210. doi:10.1007/BF00577893
The arsenic content has been analysed in millimeter sections of hairs shaved from Napoleon's scalp May 6th, 1821, the day after his death. It appeared that Napoleon was exposed to arsenic on at least 40 occasions between the summer of 1820 and April 1821. So were hairs cut in each of the years 1818, 1817 and 1816 analyzed in centimeter sections. The 1818 hairs disclosed that Napoleon was exposed to arsenic during some three months sometime between January, 1817, and March, 1818. The 1816 hairs showed particularly high concentrations of arsenic which must have been deposited before Napoleon was exiled to St. Helena.