King George III should have sued.

The madness of King George III of England might have been the fault of his doctors as much as of substandard royal genes. An analysis of preserved locks of the king's hair shows that his body harbored high amounts of arsenic, which could have exacerbated his inherited neurological problems.

George III, who reigned from 1760 to 1820, had bouts of madness that sometimes lasted months. Scientists have proposed that the sovereign was periodically deranged by an inherited disease called porphyria, which has cropped up occasionally since then in European royalty. The disease stems from defects of metabolism that cause toxic chemicals to accumulate, damaging the nervous system.

Absorption of certain metals by the body can obstruct some of these same metabolic processes.

In an effort to determine whether such obstruction was a factor in the king's mental health, researchers at the University of Kent in England looked for lead or other metals in samples of George's hair stored at the Science Museum in London. In the July 23 Lancet, they report finding an arsenic concentration of 17 parts per million (ppm). Normally, the concentration in hair is less than 1 ppm.

Royal records show that George's physicians frequently administered emetic tartar, a potion that contained antimony. Arsenic and antimony often coexist in nature. Given the doses of emetic tartar the king was getting, the researchers estimate that he could have been ingesting between 4 and 9 milligrams of arsenic per day. The records indicate that the treatments were sometimes administered against George's will.

"The [arsenic doses] are very high, but not high enough to cause acute poisoning," says study coauthor Martin J. Warren. However, he says, since arsenic affects the same metabolic pathway as porphyria, "arsenic may have precipitated his [porphyria] attacks or made them much more severe."