Lourdes Salvador's Column
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Herbicide Found to Cause Coordination & Learning Difficulties
by Lourdes Salvador
Ulises Bardullas and colleagues at the National Autonomous University of Mexico have found evidence that chronic herbicide exposure is toxic to the central nervous system of Sprague-Dawley rats.
The rats were exposed to 10 milligrams of atrazine herbicide per kilogram of body weight over a one year period. The rats were monitored for central nervous system toxicity.
Atrazine exposure led to impaired motor coordination and greater spontaneous locomotor activity. This was not immediately observed; rather the effect was noted after 10 to 12 months of cumulative atrazine exposure.
"Nigrostriatal and mesolimbic systems are the two major dopaminergic pathways of the central nervous system," says Bardullas, "They play key roles mediating a wide array of critical motor and cognitive functions."
A decrease in striatal dopamine was noted and led to discrete changes in learning tasks.
"These results indicate that chronic exposure to atrazine preferentially targets the nigrostriatal dopaminergic pathway," says Bardullas, "in comparison to the other dopaminergic pathways evaluated in this study, inducing behavioral and neurochemical alterations."
Atrazine is a synthetic herbicide used to kill weeds on farm crops, and has also been used on highways.
People may be exposed to atrazine by drinking well water contaminated with atrazine or coming into contact with sprayed crops and the soil they are grown in.
Exposed animals have also shown liver, kidney, heart, and reproductive damage.
Other studies have found that pregnant women exposed to atrazine experience slower growing fetuses and tend to give birth too early.
Bardullas U, Giordano M, Rodríguez VM. Chronic atrazine exposure causes disruption of the spontaneous locomotor activity and alters the striatal dopaminergic system of the male Sprague-Dawley rat. Neurotoxicol Teratol. 2010 Sep 15. [Epub ahead of print] PMID: 20850525
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