People who are frequently exposed to pesticides have higher risk of developing mild cognitive dysfunction

Hans Bosma, Maastricht Ageing Study

Farmers and gardeners were most at risk of developing problems.

"Our findings suggest that people who are frequently exposed to pesticides, such as arable farmers and gardeners, may have a higher risk of developing MCD," said Hans Bosma, one of the authors.

He added: "Our findings might reflect subtle changes in brain function among people exposed to pesticides."

Writing in the latest issue of the medical journal The Lancet, they said that further research was needed to back up their initial findings.

Pesticides have been associated with everything from cancer and infertility to Gulf War syndrome and eye abnormalities and, in many cases, there is solid evidence to back this up.

For this reason, some countries have banned the use of certain pesticides in food and safety levels have been set for others which are deemed to protect the public.

However, the jury is still out on the risk of consuming many pesticides on a long-term basis.