Parkinson's Disease is an incurable degenerative neurological condition and researchers say they may have found a link between exposure to pesticides and an increased risk of developing the disease.
A european study, led by a University of Aberdeen expert Dr Finlay Dick, warns gardeners to wear protective clothing.
But interesting though the discovery is, the team do recognise that there are more significant Parkinson's risk factors, such as a family history of the disease or being knocked unconscious on repeated occasions.
Parkinson's Disease is an incurable degenerative neurological condition, people with the condition have increasing difficulty in moving their limbs and develop tremors and facial tics.
Previous research has already suggested that pesticides, which can be inhaled or absorbed through the skin, can affect the way the mitochondria, the "power house" of a cell, works.
The Geoparkinson study looked at almost 3,000 people in Scotland, Italy, Sweden, Romania and Sweden, including 767 with Parkinson's. Those they interviewed had an average age of 62 and all were questioned about their professional and leisure activities, and whether or not they had regularly used pesticides.
The researchers found that people with Parkinson's disease were more likely to have used pesticides regularly during their lives.
People classed as "low level" users, such as amateur gardeners, were 9% more likely than non-users to develop the disease. High level users, such as farmers, were 43% more likely to do so.
Dr Finlay Dick said other factors were also linked to a higher increased risk of developing Parkinson's but they saw a moderate increase in risk linked to exposure to pesticides. He does not wish to over-emphasise the significance of the effect, but it is important that there are things people can do to reduce that risk, whereas people cannot change their parents.
The study was unable to look at specific pesticides because people were unable to remember which they had used.
Dr Anthony Seaton, also of the University of Aberdeen, says the findings considerably strengthen the case for pesticides being relevant to the occupational risk of Parkinson's disease.
David Coggon of the University of Southampton, who is also chairman of the Advisory Committee on Pesticides, said as the study did not identify which pesticides were linked to an increased risk of Parkinson's, it is possible that just one or two are causing it, which had slipped through the regulatory net.
Coggon wants to see research looking at exposure to individual pesticides and how they are used, to gain detailed data, rather than relying on people's memories about their pesticide use.
Robert Meadowcroft, of the Parkinson's Disease Society, said that although the causes of Parkinson's are still not clearly identified in the vast majority of cases, the link between Parkinson's and pesticides had been recognised for some time.
He accepts that the research shows some evidence that head injury, pesticide exposure and family history of the disease are all risk factors in the development of Parkinson's.
A spokeswoman for the Department of the Environment, Food and Rural Affairs said the government's Advisory Committee on Pesticides had considered the evidence of a link between pesticide exposure and Parkinson's disease last year.
Its Medical and Toxicology Panel identified a "correlation between individuals' memory of exposure to pesticides and Parkinson's disease", but it did not establish a "specific link" between exposure and the development of this illness.
The report is featured in New Scientist magazine.