Daily News Archive
Study Links Pesticides to Parkinson's Disease
(Beyond Pesticides, November 8, 2004) Researchers at Emory
University and the University of Washington have shown for the first
time that chronic exposure to the insecticide rotenone can cause Parkinson's-like
pathology in monkeys, according to a press release from the Society
for Neuroscience.This finding builds upon their previous study in which
they demonstrated that rotenone, a commonly used agricultural pesticide
made from the extracts of tropical plants, can reproduce parkinsonian
features in rats. The researchers developed a new nonhuman primate model
of this disorder.
research also builds on epidemiologic
research that finds elevated numbers of Parkinson's cases in household
that use home and garden pesticides.Other researchers have documented
low-dose effects of the insecticide permethrin,
doses below one-one thousandth of a lethal dose for a mouse, with effects
on those brain pathways involved in Parkinson's disease. The effects
are consistent with a pre-parkinsonsian condition, but not yet full-blown
parkinsonism.See previous Daily
and other articles in the Daily
In 2000, researchers at a meeting of the American Academy of Neurology's
52nd annual meeting announced their findings that link Parkinson's disease
to pesticide use and exposure in the home and garden, based on a study
of almost 500 people newly diagnosed with the disease.
The new research into Parkinson's disease is helping scientists better
understand some of the mechanisms of this serious and disabling brain
disorder, which affects about 1 million people in the United States.
Knowledge of the environmental factors and genetics of this illness
has allowed investigators to create models of disease that are being
used to examine potential causes of neuron disease and to test experimental
therapeutics in animals. The researchers hope that their work will eventually
lead to the development of more effective treatments of this human illness.
Activists want to see the scientific knowledge support the banning of
the chemicals associated with these effects.
The second most common neurodegenerative disease (after Alzheimer's
disease), Parkinson's occurs when certain groups of nerve cells are
damaged and destroyed. For example, neurons in the substantia nigra,
an area of the brain that is important for normal voluntary movements,
are invariably damaged. These abnormalities result in a variety of signs,
including tremor, muscle stiffness, and slowness of movement. People
with Parkinson's may also experience depression, anxiety, dementia,
constipation, urinary difficulties, and sleep disturbances. Symptoms
tend to worsen over time.
"Monkeys have a brain structure that is much more similar to humans
than rats," notes J. Timothy Greenamyre, MD, PhD, of Emory University.
"These studies on monkeys, therefore, support our previous findings
that chronic pesticide exposure may be capable of causing parkinsonian
pathology in humans."
In this pilot study, two monkeys were treated with rotenone-one at Dr.
Greenamyre's laboratory at Emory University and the other at the University
of Washington laboratory of Marjorie Anderson, PhD. The rotenone was
administered subcutaneously to the animals over a period of 18 months
in one case and 19 months in the other before the Parkinson's-like pathology
developed. When the monkeys' brains were later examined, the scientists
found anatomical and biochemical changes virtually identical to the
major abnormalities seen in Parkinson's disease, including degeneration
of the nigrostriatal dopaminergic pathway and synuclein positive cytoplasmic
inclusions in nerve cells in the substantia nigra.
Although this study does not prove that rotenone causes Parkinson's
disease, it adds to previous questions about the pesticide's safety
and that of similar environmental toxins. "We think this is an
important proof of the concept that what we eat, drink, breathe, or
are otherwise exposed to can predispose us to Parkinson's disease,"
says Dr. Greenamyre.
TAKE ACTION: Write U.S.EPA Administrator
Michael Leavitt and EPA Deputy
Administrator Stephen Johnson and let them know that they have a
duty to alert the public to the scientific findings (laboratory and
epidemiologic) that link pesticides with Parkinson's disease. In addition,
urge these EPA officials to initiate an urgent and expedited review
of pesticides' link to Parkinson's.