The Emory University researchers said at an American Chemical Society meeting last week that past exposure to pesticides dieldrin and DDT could accelerate the illness, putting millions in the United States at risk of developing Parkinson’s earlier in life, USA Today reported Monday.

Lead researcher Gary Miller said the chemicals were banned in the 1970s, but low levels of the toxins remain in soils they were applied to.

“If you’re exposed to a pesticide like dieldrin, you might be diagnosed (with Parkinson’s) at age 70 instead of at 80,” Miller said.

Miller and his team analyzed brain tissue taken from 14 Parkinson’s patients and a control group of 12 people. Levels of dieldrin and a breakdown product of DDT were found to be three times higher in Parkinson’s patients than in those without the illness.