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Research suggests link between pesticides and brain disease

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Alzheimer's damage
The scan on the left shows a healthy brain. The one on the right shows the damage caused by Alzheimer's disease. New research suggests exposure to pesticides may cause brain diseases such as Alzheimer's.
Image courtesy of the National Institute on Aging

Researchers at the University of North Dakota are quick to point out these are preliminary results -- covering one year of a planned four-year study. 

But Dr. Patrick Carr says there's clear evidence pesticide exposure at relatively low doses affect brain cells. 

"Some areas of the brain displayed what I would call physical changes -- in other words, a loss of neurons in particular regions of the brain," says Carr. "In other regions of the brain you wouldn't notice a change in the number of cells present there, but now the cells that are present there are expressing chemicals in different amounts, compared to normal rats."

Some areas of the brain displayed what I would call physical changes -- a loss of neurons in particular regions of the brain.

As an example, Carr found cells responsible for production of a substance called myelin were damaged or destroyed.  Myelin is a substance made up of fats and proteins that encloses nerves. It helps transmit signals along the nerves. Loss of myelin causes nerve damage in neurological diseases such as multiple sclerosis.

Researchers studied six common pesticides. Carr says some rats were given a single large dose,  while others were injected with small doses over a nine-month period. 

"It's hard to then correlate that to what the average person that's working with pesticides would be exposed to," says Carr. "We're not at that position yet, where we can say this is comparable to what these people working with pesticides, short term or long term, are exposed to."

Dr. Carr hopes to have his results completely analyzed by next spring. 

Gerald Groenwald, director of energy and environmental research, says there's clearly a need to continue and expand the research. 

"What this research says is that we have started to open some doors and shine some light in a very objective fashion, a very comprehensive fashion, on this group of questions," says Groenwald. "And it says, more than ever, that this research is extremely important not only here in the Red River Valley, but basically globally." 

Groenwald says other researchers are also looking at ways people are exposed to pesticides. He says people commonly think of being exposed to pesticides through contaminated water or food. But he believes the most  efficient means of exposure is through tiny airborne particles of pollen. 

Groenwald says some beneficial drugs are delivered as tiny particles, which are inhaled deep into the lungs. 

He says researchers found tiny bits of pollen carried on the wind carry with them a load of pesticide. 

"Frankly, if there is a link between pesticides and these diseases, I think the very fine pollen is the transport mechanism, and is in some cases you might say the smoking gun," he says. 

Groenwald says because there are relatively few competing airborne pollutants in the Red River Valley, it's a perfect place to study airborne pesticide pollution. 

Groenwald hopes to continue and expand the study over the next three years, depending on how much funding the research receives.