The US investigation, which for the first time compared exposure to pesticides in Parkinson’s sufferers and their unaffected relatives, enabled researchers to identify specific differences in exposures to chemicals.

It found that the strongest links were with the use of herbicides and insecticides, such as organochlorides and organophosphates.

Pesticide exposure and risk of Parkinson’s disease: a family-based case-control study, published in the journal BMC Neurology, is the latest in a string of studies to link pesticide use to Parkinson’s.

Research has found that the majority of cases are thought to be due to an interaction between genetic and environmental factors, rather than genetic defects, which account for only a small proportion of cases.

Lead author of the study Dana Hancock told edie it was too early in the research to say which might groups might be particularly at risk, or whether certain chemicals should be banned from household products.

She said: “What our study adds is that it’s the first family-based study to see how it affects individuals and their family members.

“It really adds confidence to the link between pesticides and Parkinson’s.”

Mrs Hancock added: “What we hope is that we will encourage other researchers to look at the specific classes of chemicals.

“Based on our study we can’t make any safety recommendations from this sample, but we hope other researchers will look at that.”

Most of those involved in the study only had experience of residential use of pesticides, and the study was unable to suggest any conclusive dangers for those involved in farming, which is a commonly source of pesticide exposure.

Kate Martin

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