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 esticide use and exposure in the home and garden increase
the risk of developing Parkinson's disease, according to a study
of almost 500 people newly diagnosed with the disease. Researchers
announced their findings at a presentation at the American Academy
of Neurology's 52nd annual meeting in San Diego, CA, April 29
May 6, 2000.
 "This
study is the largest yet of newly diagnosed individuals with
Parkinson's disease and it is the first study to show a significant
association between home pesticide use and the risk of developing
Parkinson's disease," said study lead author Lorene Nelson,
PhD, a neuroepidemiologist at Stanford University School of Medicine.
The preliminary results from this study mirror what is already
known about the increased risk of Parkinson's disease associated
with occupational exposure to pesticides.
The researchers
questioned 496 people who had been diagnosed with Parkinson's
disease about past use of pesticides. Each patient was asked
if they had used or been exposed to insecticides in the home
or garden, herbicides or weed killers in the garden, or fungicides
to control mold or mildew in the home or garden. Researchers
asked detailed questions about past pesticide use including first
exposures and frequency of pesticide contact.
The Parkinson's
patients' lifetime histories were then compared to 541 people
without the disease. Researchers found that people who had been
exposed to pesticides were approximately two times more likely
to develop Parkinson's disease than people not exposed to pesticides.
In-home exposure
to insecticides carried the highest risk of developing the disease.
Parkinson's patients were more than twice as likely to have been
exposed to insecticides in the home than those without the disease.
Past exposure to herbicides was also associated with the disease,
whereas exposure to insecticides in the garden and fungicides
were not found to be risk factors.
Damage to
nerve cells in a part of the brain called the substantia nigra
leads to the movement difficulties characteristic of Park-inson's
disease. Therefore, people exposed to chemicals that have a particular
affinity for this region of the brain may be at particular risk
for developing the disease.
"Certain
chemicals that an individual is exposed to in the environment
may cause selective death of brain cells or neurons," stated
Nelson. "If we could understand why these neurons are being
killed in certain circumstances, we can then try and prevent
it."
But Nelson
cautioned that more studies are needed before any conclusive
statements can be made about the causes of Parkinson's disease,
including any genetic influence on a person's probability of
developing the disease.
Nelson also
stressed that the results of the study must be interpreted with
caution. "No specific guidelines regarding avoidance of
pesticides can be given at this time but, in general, this is
an area of public health importance that needs to be pursued,"
said Nelson.
Parkinson's
disease is a slowly progressive, neurodegenerative disease that
affects more than 500,000 people in the United States. Parkinson's
causes the loss of dopamine, a chemical in the brain, which results
in muscle stiffness and rigidity, slowness in movement and tremor
of the arms and legs.
The National
Institutes of Health provided funding for the study. 
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