Almost two centuries later, a doctor has indeed discovered the cause. Analyzing a strand of Beethoven's hair that survived for many generations, Dr. William Walsh of the Health Research Institute in Naperville, Illinois, recently identified levels of lead that were 100 times what is now common in humans. Walsh determined that Beethoven had lead poisoning, which would explain the various symptoms from which the composer suffered. Walsh thinks that it is unlikely that the lead poisoning caused Beethoven's deafness, which developed gradually over a 20-year period and became total in 1819. What seems certain is that other residents of the area were not sickened by lead, at least not to the same degree that Beethoven was.
Lead poisoning continues to be a problem even today.
Identifying the Threat Lead is a heavy metal once used widely in many products, such as paint, gasoline, and food containers. As a natural element, lead does not break down in the environment. Once it has been dispersed, it remains in the environment until humans intervene to remove or at least contain it. Lead most often enters the human body by being swallowed. In cases of extreme exposure to lead-contaminated dust, the lead can enter the body through the respiratory system.