PCBs and Fungicides May Increase Vulnerability to Parkinson's Disease

Scientists at the University of Rochester believe they have demonstrated a link between exposure to PCBs and other chemicals disrupt key neurons in the brain, making them more vulnerable to the course of Parkinson's disease.

Parkinson's currently affects as many as 1 million Americans, and studies have shown that Parkinson's patients' brains contain elevated levels of PCBs and certain pesticides.

University of Rochester scientists investigating the link between PCBs, pesticides and Parkinson's disease demonstrated new and intricate reactions that occur in certain brain cells, making them more vulnerable to injury after exposures.

In two papers published in the journal NeuroToxicology (Dec. 2004 and Feb. 2005), 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 UR investigation is part of a nationwide race to better understand every aspect of Parkinson's disease, which affects up to 1 million Americans.

A lack of dopamine is what causes patients to experience tremors, stiffness in the limbs and trunk, and impaired movement or balance.

"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 create havoc in the body's cellular system by producing free radicals, which leads to a process known as oxidative stress (OS).

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

PCBs, used as industrial coolants and lubricants, were banned in 1977 but remain widespread in the environment due to their improper disposal.

Pesticides such as maneb remain in farmed soil for 20-75 days following application and can be found on produce for more than three weeks, even after washing, according to researchers.