A new University of Guelph study has discovered why exposure to pesticides increases some people’s risk of developing Parkinson’s disease.
Previous studies have found an association between two commonly used agrochemicals (paraquat and maneb) and Parkinson’s disease.
Now University of Guelph professor Scott Ryan has determined that low-level exposure to the pesticides disrupts cells in a way that mimics the effects of mutations known to cause Parkinson’s disease.
Adding the effects of the chemicals to a predisposition for Parkinson’s disease drastically increases the risk of disease onset, said Ryan.
“People exposed to these chemicals are at about 250 per cent higher risk of developing Parkinson’s disease than the rest of the population,” said Ryan, a professor in the department of molecular and cellular biology.
“We wanted to investigate what is happening in this susceptible population that results in some people developing the disease.”
This study used stem cells from people with Parkinson’s disease that had a mutation in a gene called synuclein that is highly associated with increased risk of Parkinson’s disease, as well as normal embryonic stem cells in which, the risk associated mutation was introduced by gene editing.
From the two types of stem cells, Ryan and his team made dopamine-producing neurons – the specific neurons affected in Parkinson’s disease – and exposed them to the two agrochemicals.
In exposing cells to agrochemicals, energy-producing mitochondria were prevented from moving to where they were needed inside the cell, depleting the neurons of energy.
Neurons from the Parkinson’s patients and those in which the genetic risk factor was introduced were impaired at doses below the Environmental Protection Agency reported lowest observed effect level.
Higher doses are needed to impair function in normal neurons.
He said the findings indicate the need to reassess current acceptable levels for these two agrochemicals.
“This study shows that everyone is not equal, and these safety standards need to be updated in order to protect those who are more susceptible and may not even know it,” he said.
