New research reveals how the pesticides paraquat and maneb alter gene expression and may lead to Parkinson’s disease in people who are genetically predisposed to the illness.
Estimates show that around 50,000 people in the United States are diagnosed with Parkinson’s disease every year. Although it is not exactly known what causes the disease, both genetic and environmental factors are thought to play a critical role.
Senior study author Scott Ryan, a professor of molecular and cellular biology at the University of Guelph in Ontario, Canada explains the motivation behind the research. He notes, “People exposed to these chemicals are at about a 250% higher risk of developing Parkinson’s disease than the rest of the population.”
The findings were published in the journal Federation of American Societies for Experimental Biology.
The researchers used stem cells from patients with Parkinson’s disease who had a mutation in the gene responsible for encoding the a-synuclein protein. At least 30 alterations in this gene have been associated with Parkinson’s, and a-synuclein protein clumps are a well-documented, albeit poorly understood, hallmark of the disease. The scientists also worked with normal embryonic cells that they modified using genetic editing to replicate the a-synuclein genetic mutation.
Prof. Ryan explains why using human cells makes this study particularly valuable. “Until now,” he says, “the link between pesticides and Parkinson’s disease was based primarily on animal studies as well as epidemiological research that demonstrated an increased risk among farmers and others exposed to agricultural chemicals.” “We are one of the first to investigate what is happening inside human cells,” he explained.
It was found that the neurons that had been exposed to the chemical had faulty mitochondria. Mitochondria, the “powerhouses of the cell,” are the organelles inside a cell that turn sugar, fats, and proteins in to the energy our body needs to survive and function.
This study demonstrated that the mitochondria inside the dopamine neurons affected by pesticides could not move freely as they normally would. This “sucked” the energy out of the neurons.
Importantly, the levels of chemical used to impair these neurons were below the ones deemed “lowest observed adverse effect level” by the United States Environmental Protection Agency (EPA). Prof. Ryan says that this means we should re-evaluate the EPA’s guidelines for these two pesticides.
My Take - Paraquat dichloride, commonly referred to as “paraquat,” is one of the most widely used herbicides registered in the United States. Paraquat is also often referred to as Gramoxone (a popular end-use product). Paraquat is used to control weeds in many agricultural and non-agricultural use sites.
Maneb can be found in fungicide products that are used to control a wide variety of diseases, such as blight, leaf spot, rust, downy mildews, and scab in fruits, vegetables, field crops like potatoes, and ornamental plants.
Despite the known toxicity and association may other diseases in addition to Parkinson’s, these chemicals are still sprayed on much of the food consumed here in the U.S.
The Bottom Line:
Don’t count the EPA to increase regulation of these poisons as they more likely will relax current restrictions. Eat organic foods whenever possible and always wash your food thoroughly before consumption.
Source: May 26, 2018 National Institutes of Health