Image of a graph which depicts lead levels in normal hair (red) and Beethoven's hair (blue).
From the University of Western Australia we learn more about this graph (and the analysis):
Researchers at the Health Research Institute in Naperville, Illinois, the McCrone Research Institute in Chicago and the Advanced Photon Source synchrotron facility at the Argonne National Laboratory in Illinois used a range of conventional and synchrotron techniques including x-ray fluorescence.
Their tests revealed that Beethoven’s hair contained about 100 times the level of lead found in human hair today.
Image online, courtesy the University of Western Australia website.