The researchers at the U.S Department of Energy's Argonne National Laboratory examined bone fragments owned by Paul Kaufman, a California businessman, using a X-rays from the lab's high-output Advanced Photon Source. In addition, they examined a section of another skull dating from the same period in order to establish a baseline. They concluded that there were elevated amounts of lead in Beethoven's bones.

Meanwhile, the scientists confirmed the origin of the skull fragments by comparing their DNA with samples of the composer's hair.

"The finding of elevated lead in Beethoven's skull, along with DNA results indicating authenticity of the bone/hair relics, provides solid evidence that Beethoven suffered from a toxic overload of lead," said Bill Walsh, director of the Beethoven Research Project, in a statement. "In addition, the presence of lead in the skull suggests that his exposure to lead was not a recent event, but may have been present for many years."

Walsh added that Beethoven's known chronic symptoms, including difficulties with digestion, abdominal pain, irritability, and depression, are typical symptoms of lead poisoning. The composer's deafness is less likely to be related to lead exposure.