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Elizabeth Guillette's study of pesticide exposure on Mexican children

EDITOR'S NOTE: The following consists of the official 'abstract' and a Washington post article of anthropologist, Elizabeth Guillette's study of pesticide exposure on Mexican children. Ms. Guillette's work was recently documented in the CBC documetary "Toxic Legacies".

Environmental Health Perspectives Volume 106, Number 6, June 1998

An Anthropological Approach to the Evaluation of Preschool Children Exposed to Pesticides in Mexico

Elizabeth A. Guillette,1 María Mercedes Meza,2 Maria Guadalupe Aquilar,2 Alma Delia Soto,2 and Idalia Enedina Garcia2 1Bureau of Applied Research in Anthropology, University of Arizona, Tucson, AZ 85721 USA 2Direccion de Investigacion y Estudias de Postgrado, Instituto Tecnológico de Sonora, Obregón, Sonora, México

In this comparative study, we compensated for many of the known variables that influence children's growth and development by selecting two groups of 4-5-year-old Yaqui children who reside in the Yaqui Valley of northwestern Mexico. These children share similar genetic backgrounds, diets, water mineral contents, cultural patterns, and social behaviors. The major difference was their exposure to pesticides.

Pesticides have been applied to the agricultural area of the valley since the late 1940s. In 1990, high levels of multiple pesticides were found in the cord blood of newborns and in breast milk. Building on anthropological methods for rapid rural appraisal of problems within the environment, a Rapid Assessment Tool for Preschool Children (RATPC) was developed to measure growth and development. The children of the agrarian region were compared to children living in the foothills, where pesticide use is avoided. The RATPC measured varied aspects of physical growth and abilities to perform, or function in, normal childhood activities. No differences were found in growth patterns.

Functionally, the exposed children demonstrated decreases in stamina, gross and fine eye-hand coordination, 30-minute memory, and the ability to draw a person. The RATPC also pointed out areas in which more in-depth research on the toxicology of pesticides would be valuable.
Key words: children, Mexico, pesticides, Yaqui.
Environ Health Perspect 106:347-353 (1998).


Address correspondence to E.A Guillette, 32 SW 43rd Terrace, Gainesville, FL 32607 USA.

The authors would like to acknowledge Gonzalo Robles Monteverde and José Luis Navarro of the Secretaría de Salud Publica, Sonora, and Jose Manuel López and Juan Manuel Morsan of the Instituto Tecnológico de Sonora for their assistance in making this study possible. We thank Howard Bern and Theo Colborn for valuable comments on earlier drafts of this manuscript and Lou Guillette for assistance with statistics. This work was funded in part by the Bureau of Applied Research in Anthropology, University of Arizona, Direccion de Investigacion y Estudias de Postgrado, Instituto Tecnológico de Sonora and Secretaría de Salud Publica, Sonora.

Received 5 September 1997; accepted 10 March 1998.

Washington Post : Guillette Study

From today's Washington Post A Cautionary Tale About Pesticides By Judy Mann Washington Post, June 2, 2000; Page C09

Elizabeth Guillette, an anthropologist and research scientist at the University of Arizona, has been studying the effects of pesticides on the children of Yaqui Indian farmers in Mexico, and she has come up with alarming findings.

In the 1950s, the Yaqui had hit a philosophical divide: Some wanted to adopt modern farming techniques, including the use of pesticides and tractors, and others wanted to continue with traditional methods. Those wishing to use pesticides moved to the valley of their region, and those who did not occupied the foothills.

"Otherwise, genetics, cultural patterns, everything else is identical," Guillette says. When Guillette first visited the tribe, the mothers in the valley were concerned because their children were often sick. She decided to use standard developmental tests to study the neuromuscular and neuromental functioning of the children--33 from the valley and 17 from the foothills. The children were then 4 and 5 years old, and she used play behavior--such as catching a ball, jumping contests and various mental exercises--to see how they were faring.

She began by telling them that when they had finished the exercises, they would get a red balloon. She pointed out the balloon and the color red. All of the children had been exposed to some pesticides through what they ate, breathed, drank or touched, but the children in the valley had been much more exposed. Guillette found the valley children "could not perform the tasks as well."

Unlike guns or violent movies, pesticides are everywhere, and lead is present in millions of homes. It is time to include them in the national discussion about violence.

"Well over half of the lesser-exposed children could remember the color in the object, and all remembered they were getting a balloon. Close to 18 percent of the exposed children could not remember anything," and only half could remember they were getting a balloon. "It was quite a contrast," she says.

"One of the most profound differences was in their ability to draw a person, which is part of the IQ test. The foothills children at ages 4 and 5 could draw a complete person. Among the exposed children, most 4-year-olds just scribbled, and the 5-year-olds could draw a head and a line or a circle and a line.

I went back two years later. The 7-year-old exposed children were basically drawing on the 4-year-old level. The 7-year-old lesser-exposed were identifying people by gender, with a dress or pants, appropriate hair, fingers, facial features and shoes." She also found on the second trip that the exposed children continued to lag behind in their energy levels and had a much poorer sense of balance. She had both groups walk a 2-by-4 plank and turn around and walk back. "The exposed children lacked the balance to turn around and walk back. The lesser-exposed could."

On that trip, she surveyed the children for illness during the past three months and found that the valley children had been ill about six times as often as the lesser-exposed children in the foothills. Guillette published her findings two years ago in the journal Environmental Health Perspectives.

Other research is showing a strong correlation between childhood lead poisoning and poor school behavior and performance, including attention deficit, hyperactivity, impulsiveness, delinquency and violence. "The data aren't conclusive, but there's still plenty to suggest that exposure to pesticides might have the same sorts of effects on children's learning and behavior," says David Wallinga, a physician with the Natural Resources Defense Council.

Guillette says she noticed that exposed Yaqui children would walk by somebody and just hit them. They tended to just sit and do nothing in a group, whereas the foothill children were always busy with group play. "I'd throw the ball to a group of kids. In the valley, one child would get the ball and just play with it himself," she says.

The foothills children played with the ball as a group. Veteran teachers have complained that the exposed children are much more difficult to teach: They don't remember, and they are more difficult to control. Yaqui mothers from the valley also reported more problems getting pregnant and higher rates of miscarriage, stillbirth, neonatal death and premature birth.

The Environmental Protection Agency has concluded that a pesticide compound sold as Dursban may be more dangerous to people than previously thought, according to sources familiar with the decision. That determination is expected to effectively remove the product from over-the-counter products.

Farmers will still be allowed to spray it on crops, but its agricultural use will be reduced. The EPA's findings came as part of an extensive review of the safety of pesticides required under the 1996 Food Quality Protection Act, which is designed to protect children in particular from the toxic effects of pesticides.

It's impossible to tell what pesticides the Yaquis have been exposed to, Guillette says. "We know for sure there has been DDT exposure," she say. The Mexican government "does not know what's being used. The farmer does not give out the information.

Pesticides are tied to bank loans, and the banks won't reveal what is being used with certain crops. I just assume everything. The other problem is they get a little of this and a little of that and mix it up.

It is very important to remember that the situation is no different agriculturally than what you find in California, the Midwest or the East Coast in the U.S." Furthermore, she underscores the point that half the pesticides sold in the United States are used in urban areas, which means urban children are also at risk.

"Many of these contaminants have similar reactions in the body," Guillette says. "Many disrupt the endocrine system, which regulates body functions, and that's the main reason I looked at subtle changes. The shift may seem slight, but when they occur within a total society, they can have major implications.

To me, the approach should not be treatment of the disease or trying to teach compensation for the deficit but to look at the basic problem of contamination."

The differences Guillette has found in the Yaqui children and in their mothers should be an alarm bell for the rest of us. It is part of a growing body of research linking lead and pesticides to poor school performance and aggressive behavior.

Unlike guns or violent movies, pesticides are everywhere, and lead is present in millions of homes. It is time to include them in the national discussion about violence. © 2000 The Washington Post Company --