Rotenone is also widely used in liquid form by fishery managers to destroy pest species. The chemical is added to lakes and reservoirs, where it kills all the fish by inhibiting their ability to use oxygen. Once it has degraded, the water is restocked with the desired fish species. Parkinson's disease is one of the most common neurodegenerative diseases, affecting nearly one million Americans over the age of 50. The disease is caused by the steady loss of cells, in a tiny region of the brain called the substantia nigra, that produce a chemical, dopamine, which is crucial for movement and cognition.
Patients develop jerky, tremulous movements that get worse with time.
Eventually they become entirely rigid. A hallmark of the disease is that dopamine cells in the substantia nigra become clogged with tiny, gunky clumps of abnormal protein called Lewy bodies. Scientists have suspected since the middle of the 19th century that an environmental toxin might be involved in Parkinson's disease, Dr. Tanner said. Moreover, people who work on farms or live in the countryside have as much as seven times as much risk of developing the disease as other people. The first real clues to understanding the disease were found in 1983 when a number of young addicts using contaminated heroin developed severe Parkinson's-like symptoms.