PCBs & Pesticides Linked to Parkinson's Disease

>From Environmental News Service
<www.ens-newswire.com>

PCBs, Fungicide Pave the Way for Parkinson's Disease

ROCHESTER, New York, February 9, 2005 (ENS) - University of Rochester
scientists investigating the link between PCBs, pesticides and Parkinson's
disease have discovered intricate reactions that occur in certain brain
cells, making them more vulnerable to injury after exposures to these
toxics.

In two papers published in the journal "NeuroToxicology" in the December
2004 and February 2005 issues, the group describes how polychlorinated
biphenyls (PCBs) disrupt dopamine neurons, which are the cells that
degenerate during the course of Parkinson's disease.

Researchers also show that low levels of maneb, a fungicide commonly used
in farming, can injure the antioxidant system in those same types of cells.

Environmental contaminants might make dopamine cells more vulnerable to
damage from normal aging, infection, or subsequent exposure to pollutants,
researchers say.

The investigation is part of a nationwide effort to better understand every
aspect of Parkinson's disease, which affects up to one million Americans.

Parkinson's is a progressive neurological disorder that occurs when certain
nerve cells die or can no longer produce the brain chemical dopamine. A lack
of dopamine is what causes patients to experience tremors, stiffness in the
limbs and trunk, and impaired movement or balance.

In the 1990s scientists reported that the brains of Parkinson's patients
contained elevated levels of PCBs and certain pesticides. While researchers
believe that genetics, the aging process and exposure to toxicants all play
a role in the development of Parkinson's, the group led by Lisa Opanashuk,
Ph.D., is focused on environmental exposures. The National Institute of
Environmental Health Sciences is funding the work.

"If we can identify the mechanisms by which PCBs or pesticides perturb
dopamine neuron function, it may lead to the development of therapies that
can prevent, slow or stop the progression of Parkinson's," says Opanashuk,
an assistant professor of environmental medicine.

PCBs trigger the body to produce free radicals, which leads to a process
known as oxidative stress - thought to be one of the main causes of cell
degeneration.

Normally, antioxidants can balance the damage done by oxidative stress. But
toxic pesticide exposure, combined with the normal aging process, shifts the
equilibrium toward oxidative stress and neurodegeneration.

The Rochester studies demonstrate, for the first time, the intricate
oxidative stress and antioxidant responses to PCBs in dopamine neurons.

PCBs, used as industrial coolants and lubricants, were banned in 1977 but
remain widespread in the environment due to their improper disposal. They
linger in the food chain, particularly in wild and farmed salmon and other
fish. PCBs accumulate in the body in fat and brain cells and other tissues.

The potential adverse health effects of PCBs are dependent on levels of
exposure, the toxicities of individual chemicals present in any given
mixture, and their interactive properties.

Pesticides such as maneb remain in farmed soil for 20 to 75 days following
application and can be found on produce for more than three weeks, even
after washing, according to researchers. Until now, the effect of maneb on
oxidative stress responses in dopamine neurons was unknown.

Opanashuk's group shows that cells treated with low levels of maneb also
undergo changes that disturb the balance in the antioxidant defense system.
Another concern is whether maneb causes more damage when people are exposed
in combination with other pesticides, which occurs in rural communities.

The University of Rochester also houses the Parkinson's Disease Data and
Organizing Center, a nationwide network of 12 institutions directed by Roger
Kurlan, M.D. and the Parkinson Study Group, a consortium of experts founded
and headed by neurologist Ira Shoulson, M.D.; as well as the Parkinson's
Disease Gene Therapy Study Group, a national effort involving researchers
from seven institutions.

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