Insecticide usage may lead to Parkinson’s symptoms

LOW levels of a widely used insecticide may cause changes in the brain that lead to symptoms of Parkinson’s disease.

A study of the effects of permethrin on mice found it triggered a slow process of damage to nerve pathways in the brain.

Permethrin is sold all over the world in numerous products that kill and repel insects.

It is used in fly sprays, by campers and soldiers, and to control agricultural pests and head lice.

It is also used in Ireland as a pesticide, for use on clothing as an insect repellent, and for the topical treatment of scabies and head lice.

Last July, permethrin was included in a list of substances under review by the European Union. The review is still ongoing.

The scientists at Virginia Polytechnic Institute and State University at Blacksburg, in the United States, exposed mice to levels of permethrin less than 0.001 of a lethal dose.

Dr Jeffrey Bloomquist, who led the study said: "We found low-level exposure set in motion a process with an early onset that develops slowly and is persistent.

"More surprising is that high-level exposure resulted in few immediate effects that we could observe, but in the longer term there was a delayed effect." The chemical affected neurochemical pathways in the brain known to be linked to Parkinson's disease.

An increase in uptake of the nerve transmitter chemical dopamine was observed, indicating that dopamine was in short supply.

Parkinson's symptoms such as muscle rigidity, shuffling gait, and tremors, are associated with a lack of dopamine in the brain.

Dr Bloomquist, who presented the findings yesterday at the American Chemical Society's annual meeting in New Orleans, said: "Our studies have documented low-dose effects of permethrin, doses below one-one thousandth of a lethal dose for a mouse, with effects on those brain pathways involved in Parkinson's disease.

"We have found effects consistent with a pre-Parkinsonian condition, but not yet full-blown Parkinsonism."

Permethrin exposure also resulted in an overproduction of a protein known to be a major component of the Lewy bodies fibrous tangles seen in the brains of Parkinson's patients.

The study was funded by the US Army, which is interested in permethrin because of a possible connection with Gulf War Syndrome.

Permethrin was first marketed in 1977.

It acts in a similar way to DDT by strongly exciting the nervous systems of insects.

The chemical is toxic at high levels and classified as a possible carcinogen by the US Environmental Protection Agency.