A study revealing high concentrations of arsenic in a sample of King George III\'s hair is published in this week\'s issue of THE LANCET. The authors believe the presence of arsenic in the King\'s hair contributed to his unusually severe and prolonged bouts of madness.

While on the throne King George III had five major episodes of prolonged and profound mental derangement. The King\'s illness was originally thought to be a psychiatric disorder but the physical manifestations of the illness revealed the monarch suffered from acute attacks of porphyria--a genetic defect leading to the faulty synthesis of a protein.

However, there is little information available to account for the unusual persistence, severity, and late onset of attacks. One possible explanation is exposure to heavy metals, including lead and mercury.

Martin Warren (University of Kent, UK) and colleagues investigated exposure to such metals in a sample of the King\'s hair. They found unexpectedly high concentration of arsenic in the hair sample. The researchers looked at the Royal physician\'s medical notes to try and identify the source of the arsenic.

They found that the principal compound administered to the King during his illness was emetic tartar. Emetic tartar contains a substance called antimony, which can be contaminated with arsenic.

The authors believe that the King\'s medication was the source of the arsenic found in the hair sample.

Professor Warren states: \"The presence of arsenic in a sample of the King\'s hair provides a plausible explanation for the length and severity of his attacks of illness; and contamination of his antimonial medications is the probable source of the arsenic. We propose that exposure to arsenic would exacerbate attacks of porphyria in a genetically predisposed individual.\"

Joe Santangelo