Organic Pesticide Linked
With Parkinson's Disease

PARIS (AFP) - An organic garden pesticide widely considered safe for human health and harmless for the environment may cause Parkinson's disease, scientists fear.
Lab rats intravenously injected with rotenone, a plant-based pesticide used to eliminate unwanted insects, kill ticks on household pets and cull pond fish in water management programmes, developed Parkinson's-like symptoms and brain damage, they report.
Parkinson's, which strikes about one percent of all people over the age of 65, is a notorious degenerative disease characterised by shaking, immobility and difficulty in speaking. Sufferers include Pope John Paul II, Muhammad Ali and screen actor Michael J. Fox.
Some cases of Parkinson's have been pinned to genes, but most cases remain unexplained, causing scientists to ponder whether there could be an environmental factor.
The scientists, from Emory University in Atlanta, Georgia, report their work Sunday in the December issue of Nature Neuroscience, a US specialist journal.
They say the degeneration occurred in dopamine-containing neurons in the substantia nigra, part of the brain that helps to coordinate movements.
The rats developed clumpy proteins, called Lewy bodies, in this area and also suffered some of the characteristic symptoms of Parkinson's.
"The results indicate that chronic exposure to a common pesticide can reproduce the anatomical, neurochemical, behavioural and neuropathological features" of the disease, the team say.
University of Pennsylvania researchers Benoit Giasson and Virginia Lee said many questions remain to be answered, but there were already worrying implications.
"Rotenone is a naturally occurring substance that is eventually degraded in the environment, and as such it is considered to be benign compared to many other pesticides.
"The results... are likely to raise new questions about its safety," they write.
Parkinson's disease is known to develop in mice or monkeys treated with a drug called MPTP, which disrupts enzymes in mitochondria, a component at the heart of a cell that provides the cell with energy.
Rotenone, like many other pesticides, inhibits the same enzyme, which is called Complex 1. This is what led the Emory University team to check out the pesticide's effect on the rats.
One theory, said Giasson and Lee, was that the disruption causes the mitochondria to crank out free radicals -- agents that induce cell death and mutation which have been already been implicated in numerous diseases.
Rotenone is extracted from roots, seeds and leaves from plants such as barbasco, cub, haiari, nekoe and timbo, which are members of the pea family.
US trade names for products containing rotenone include Chem-Fish, Cuberol, Fish Tox, Noxfire, Rotacide, Sinid and Tox-R, according to Emtoxnet, a Web-based data bank on pesticides run by several US universities.
It is also marketed as Curex Flea Duster, Derrin, Cenol Garden Dust, Chem-Mite, Cibe Extract and Green Cross Warble Powder.
The pesticide is classified as highly or slightly toxic for humans, according to its formulation.
It can be lethal if taken in large, concentrated doses, which is not the case for commercially-sold products. It is considered safe for the environment as it loses all its toxicity within a few days.
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