Female mice disabled by parents’ pesticide intake

February 27, 2011

By Lynn Markham

Special Report: Pesticides in Wisconsin food and water, part 1

Mouse maze_Dan

Dan Butz, an associate scientist in Warren Porter’s UW-Madison lab, is about to lift the center hollow cylinder lid and put a mouse inside, and then release the mouse to find its breakfast. ~photo courtesy Warren Porter

A white mouse is placed in the center of a maze. She is hungry because she hasn’t eaten all night. As soon as the gate is raised she takes off in search of her breakfast, scurrying down the channels. She quickly realizes that turning left at every point in the maze gets her food.

A few minutes later, a second mouse is set down in the center of the maze. She looks the same as the first mouse, but when the gate is raised she just sits there and seems afraid to move. Slowly and hesitantly she starts moving and eventually finds a piece of food. She continues slowly down the maze but doesn’t seem to have learned or remember that taking left turns leads to food. You might call her a slow learner.

Why is it hard for the second mouse to learn? Three months earlier when she was growing in her mother’s womb, her mother was exposed to a pesticide called chlorpyrifos at levels comparable to what humans encounter in the environment. These two mice were among three groups of 64 tested in the maze at Dr. Warren Porter’s UW-Madison lab in one of a growing number of experiments considering the links between pesticide exposure and the ability to learn.

Porter and his researchers found that female mice whose mothers were exposed to chlorpyrifos during pregnancy were slow learners. Male mice from the same mothers were unaffected, possibly because they have different levels of liver-detoxifying enzymes.

“I really got into the issue of children’s pesticide exposure after reading an article in 1997 that looked at student disabilities in the Madison Metropolitan School District,” Porter explained in his 2004 article, “Do Pesticides Affect Learning and Behavior?”

“The data showed that the number of children in Madison [who] were emotionally disturbed increased 87 percent, children with learning disabilities increased 70 percent, and children with birth defects increased 83 percent [from 1990 to 1995],” Porter wrote. “This is a serious epidemic and yet no one really knows exactly how or why this is happening… It seems to be a global phenomenon and the question is why and how is this happening and what can we do about it.”

Toxins in Food and Water

If you’ve never heard of chlorpyrifos, you’re not alone. The array of synthetic pesticides is growing, making it hard to keep track of them. Pesticides include chemicals used to kill or repel weeds, insects, fungi, or rodents, respectively known as herbicides, insecticides, fungicides, and rodenticides. In 2005, Wisconsin farmers alone reported applying 90 distinct pesticides.

Chlorpyrifos is part of a family of pesticides called organophosphates, which are applied to fields to kill insects by disrupting their nerve impulses. Over 90,000 pounds of organophosphates were applied to apples, potatoes, green beans, tart cherries, soybeans, and field corn in Wisconsin in 2005. Forty foods at grocery stores were found to sometimes contain chlorpyrifos, based on occasional testing by the U.S. Department of Agriculture.

Looking beyond chlorpyrifos and considering pesticides more generally, of the 12,000 samples of fruits, vegetables, nuts, and grains that USDA analyzed in 2008, 70 percent of the samples contained at least one pesticide residue.

Given that pesticides are used extensively in Wisconsin agriculture, it’s sobering but probably not surprising that they’re also found in our state’s groundwater, lakes, and streams.

A 2007 study estimated that one out of every three private drinking water wells in Wisconsin contains detectable levels of agricultural pesticides or pesticide metabolites. Metabolites are breakdown products which may be more or less toxic than the pesticides themselves. Most frequently detected in drinking water were metabolites of pesticides used on field corn, which was planted on 40 percent of the state’s cropland in 2007. From the 398 wells sampled in this study, a pattern emerged: wells in areas with more cropland were more likely to contain pesticides.

94% of the U.S. population has measurable pesticide metabolites in their urine.

90,000+ lbs of organophosphate pesticides were applied to apples, potatoes, green beans, tart cherries, soybeans, and field corn in Wisconsin in 2005.

1 in 3 private Wisconsin wells contain detectable levels of agricultural pesticides or pesticide metabolites.

Health Impacts

A national study of 1,949 people in 1999 and 2000 underscores the scale of human exposure: 94 percent of the U.S. population has measurable organophosphate pesticide metabolites in their urine.

“EPA cannot protect you,” Porter said, adding that he and his colleagues have been attacked by the pesticide industry—to the point where he does not feel comfortable discussing his upcoming research until it’s published.

atrazine birth defects graph
U.S. birth defect rates by month of last menstrual period versus atrazine concentrations. Source: “Agrichemicals in surface water and birth defects in the United States,” by Paul D. Winchester, Jordan Huskins, and Jun Ying published 2009 in Acta Pædiatrica.

But many studies in the last few years already shed light on how pesticide exposure through food and water affects our children’s health. A national study in 2009 found that higher levels of pesticides in lakes and streams in April to July coincided with higher risk of birth defects in children conceived in April to July (see atrazine graph). Two studies published in 2010 found that children with higher levels of organophosphate metabolites were more likely to be diagnosed with ADHD, which impedes learning.

“Babies and children do not have the defensive enzymes at levels present in sexually mature adults,” Porter explained in his 2004 article. Consequently, children are less able to detoxify the pesticides to which they are exposed.

“We’re dosing our kids with neurotoxins like chlorpyrifos, and then we wonder why they’re having trouble learning and concentrating,” Porter told the Compass. “We wonder why we have to medicate them all the time.”


Above graph generated by Lynn Markham. Souce: Wisconsin Agricultural Statistics Service, 2005.

Take-Home Message

Fortunately, a recent study of 23 Seattle elementary-school-age students points the way toward solutions.

When parents in the study fed their children an organic diet—organic foods are those grown without synthetic pesticides—for as little as one week, the levels of chlorpyrifos metabolites in their urine dropped more than four-fold to undetectable levels. This study demonstrated that an organic diet provides a dramatic and immediate protection against exposures to organophosphate pesticides commonly used in agricultural production.

So what lessons do Porter’s mice teach?

Porter advises parents or parents-to-be to do the same things he has done with his own children to reduce their risks from pesticides.

“It’s very simple,” he said. “Don’t buy pesticides. Don’t buy non-organic foods. Pack organic lunches, and get a really good water filter.”

kids drawings

A 1998 study compared 4- and 5-year-old Yaqui children living in the foothills and valley near Sonora, Mexico. In the foothills pesticide use was avoided; in the valley, agricultural pesticides have been frequently used since the late 1940s on fruits and vegetables that are largely exported to the United States. No differences were found in children’s growth patterns, but the exposed valley children demonstrated decreases in stamina, gross and fine eye-hand coordination, 30-minute memory, and the ability to draw a person. Valley mothers experienced a higher overall rate of problem pregnancies, which included spontaneous abortion rates, prematurity, and birth defects. Source: “An Anthropological Approach to the Evaluation of Preschool Children Exposed to Pesticides in Mexico” originally published in Environmental Health Perspectives by Elizabeth A. Guillette, Maria Mercedes Meza, Maria Guadalupe Aquilar, Alma Delia Soto, and Idalia Enedina Garcia.

Lynn Markham focuses on how land uses affect water quality as a statewide specialist with the Center for Land Use Education at UW-Stevens Point, uwsp.edu/cnr/landcenter. This is the first of a two-part series on pesticides and Wisconsin groundwater. Next month Markham will consider which pesticides are and are not regulated in Wisconsin drinking water, how these pesticides affect farm worker health, and how organic farmers in Wisconsin manage their crops without synthetic pesticides.

% of Food Samples with Chlorpyrifos

Domestic                Imported

Apples – single servings                31%                81%

Sweet bell peppers                            2%                57%

Peaches                                               2%                51%

Almonds                                            39%                0%

Plums                                                   6%                36%

Catfish                                                 1%                31%

Nectarines                                          1%                30%

Cranberries                                      24%                0%

Grapes                                                  2%                23%

Spinach                                               3%                19%

Field corn                                          18%                no data

Soybeans                                           14%                no data

Pears                                                     1%                14%

Tomato paste                                      9%                0%

Broccoli                                                9%                0%

Green onions                                      5%                0%

Spinach, frozen                                  7%                0%

Pears – single serving                        1%                3%

Cucumbers                                           0%                5%

Cantaloupe                                          7%                1%

Oranges                                               4%                3%

Tomatoes                                            0%                3%

Lettuce                                                  3%                0%

Asparagus, canned                            2%                0%

Green beans                                        0%                4%

Winter squash                                    1%                3%

Kale                                                       2%                0%

Asparagus                                           0%                3%

Collard greens                                     4%                0%

These food sampling results reflect varying decisions by farmers and the companies that purchase their crops about whether to apply pesticides, and what types and quantities to apply. For most crops, a larger percentage of imported samples contained chlorpyrifos; the exceptions were cranberries and almonds. Source: USDA.

Learn More:
• Learning effects of chlorpyrifos on mice
Haviland JA, et al. 2009. Long-term sex selective hormonal and behavior alterations in mice exposed to low doses of chlorpyrifos in utero. Reproductive Toxicology

• Wisconsin register of water treatment devices approved to remove specific contaminants http://commerce.wi.gov/php/sb-ppalopp/contam_alpha_list.php

• Wisconsin pesticide use, National Agricultural Statistics Service, 2006. nass.usda.gov/Statistics_by_State/Wisconsin/Publications/Miscellaneous/pest_use_06.pdf

• Pesticides found by USDA on food from grocery stores, based on the U.S. Department of Agriculture’s Pesticide Data Program whatsonmyfood.org/pesticide.jsp?pesticide=160

•USDA Pesticide Data Program Progress Report 2008-2010

• Wisconsin Groundwater Quality: Agricultural Chemicals in Wisconsin Groundwater, April 2008. WI Dept of Agriculture, Trade and Consumer Protection. Not available on the web. National study of Metabolites of Organophosphorus Pesticides in the U.S. Population
Barr, Dana B et al. Concentrations of Dialkyl Phosphate Metabolites of Organophosphorus Pesticides in the U.S. Population. Environmental Health Perspectives 112:186–200 (2004). ncbi.nlm.nih.gov/pmc/articles/PMC1241828/pdf/ehp0112-000186.pdf

•  Acreage of Wisconsin crops, USDA 2007 Agricultural Census of Agriculture – Wisconsin, Tables 8 and 33.

•Agrichemicals in surface water and birth defects in the U.S.

Paul D Winchester, Jordan Huskins, and Jun Ying. Agrichemicals in surface water and birth defects in the United States, Acta Pædiatrica 2009 April; 98(4): 664–669.

• Organic diets lower children’s dietary exposure to pesticides.
Lu C, et al. 2006. Organic diets significantly lower children’s dietary exposure to organophosphorus pesticides. Environmental Health Perspectives, 114(2): 260–3. ehp03.niehs.nih.gov/article/fetchArticle.actionarticleURI=info:doi/10.1289/ehp.8418

• Drawings from children exposed and unexposed to agricultural pesticides in Mexico

Guillette, Elizabeth A., et al. 1998. An Anthropological Approach to the Evaluation of Preschool Children Exposed to Pesticides in Mexico. Environmental Health Perspectives, 106 (6): 347-353.

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4 Comments on "Female mice disabled by parents’ pesticide intake"

  1. Nancy Rutigliano on Mon, 28th Feb 2011 12:39 pm 

    Powerful article. The drawings by the preschool children look exactly like the back cover of Dr. Kaye H. Kilburn’s book on chemical brain injury. He says we will have a nation of social misfits. Some say we already do.

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