DR. Don Research Update
Study shows farm workers have reduced neurobehavioral performance from pesticide exposure

By Don Lotter

March 19, 2004: Criteria for sustainability of agricultural systems usually are things like erosion, runoff, and yield stability. Citing these, some “experts” think that current conventional agriculture is relatively sustainable. In fact, a professor of agriculture at UC Davis told me that just the other day.

The Achilles heel of the “conventional agriculture is sustainable” argument may be farm worker health (I would say it is just one of several Achilles heels, aquatic pollution is another huge one). If the levels of pesticides going into the foods we eat are too low to cause immediate measurable health problems, the experts will say that the food system is safe. And this is what they do, even though they do not know the long-term consequences of low-level exposure.

Farm workers, however, are showing up with immediate and rather alarming health problems, associated with pesticide exposure.

A team of researchers from the National Institute of Environmental Health Sciences did neurobehavioral tests on a large group of farm workers (288), mostly Latino, in Florida and compared them with an identical group from the same community who had never done farm work.

They found a significant degradation of performance on neurobehavioral tests in farm workers compared to the control group, and the more years of farm work they did, the more degraded was their performance.

The farm workers had worked in three types of agriculture: ornamental fern production, nurseries, and citrus harvest. The subjects were carefully screened for traits that could skew the results -- for instance farm workers who had experienced acute pesticide poisoning were rejected, since the objective was to determine the effects of chronic exposure.

The battery of neurobehavioral tests were all well established tests designed to evaluate a range of neurological health criteria. They have technical names like digit span, symbol digit latency, vibrotactile threshold, visual contrast sensitivity, tapping, Santa Ana pegboard test, grip strength, and postural sway.

Fern work was particularly strongly related to lessened neurobehavioral performance. Fern production is pesticide intensive and the workers handle the ferns intensively.

Poor neurobehavioral performance correlated with the number of years of farm work in both current and former farm workers.

Some tests showed no effect from farm work. The tests that were affected by farm work were digit span, tapping, Santa Ana pegboard test, and postural sway.

The fact that the researchers excluded subjects who had experienced acute pesticide poisoning in the past is important, as agrichemical industry scientists have in the past attacked studies that included acute poisoning subjects, saying that the acute poisonings cause the neurobehavioral problems and that chronic exposure is harmless.

Don Lotter has a Ph.D. in agroecology and has worked in sustainable agricultural development in North America, Latin America, and Africa over the past 25 years. He can be contacted via his website www.donlotter.com

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