An increased risk of Parkinson's disease could be caused by raised levels of a pesticide in the blood, US research suggests.
The link between Parkinson's and pesticide exposure has been strengthened by what is said to be the strongest evidence yet pointing to a connection.
Higher than normal levels of organochlorine pesticides such as DDT have been found in the brains of Parkinson's patients during previous studies. However, the highlighting of a specific pesticide chemical in the blood is a research first.
The new findings could lead to a blood test that would identify potentially susceptible individuals, according to scientists at the University of Texas Southwestern Medical Center in Dallas.
Protective treatments and a monitoring service would then be provided to look for early signs of the disease, the scientists say.
Of the 113 people aged 50 to 89 studied by scientists for traces of 15 organochlorine pesticides: 50 had Parkinson's; 43 were healthy; and 20 had Alzheimer's disease.
More than 70% of those tested with Parkinson's had an unusual chemical in their blood - beta-HCH (hexachlorocyclohexane).
This was compared to 40% of the healthy volunteers and 30% of Alzheimer's sufferers having the chemical in their blood.