The cause of Parkinson’s disease is largely unknown. A small percentage of cases are caused by genetics, especially in early-onset patients.

In the 1980s, researchers began to look into the role of environmental toxins in Parkinson’s disease.

These studies show  that some pesticides (such as dieldrin, a pesticide used to control termites), herbicides (such as the widely used paraquat), and industrial toxins (such as PCBs found in electric transformer) can cause the death of dopamine-containing neurons, which results in Parkinson’s disease symptoms.

Other studies show that long-term exposure to metals such as iron, lead, copper, manganese and zinc significantly increase the risk of developing Parkinson’s disease.

Researchers also identified some “susceptibility” genes that may not directly cause Parkinson’s disease. But changes in these genes may make people more or less likely to develop the disease later in life.

More studies are being carried out to help scientists understand how genetic defects and environmental toxins interact to cause Parkinson’s disease.

For a more detailed description of the studies, click here.