Pesticides and Aggression

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PESTICIDES AND AGGRESSION

For the past 25 years, tens of millions of Americans in hundreds

of cities and towns have been drinking tap water that is

contaminated with low levels of insecticides, weed killers, and

artificial fertilizer. They not only drink it, they also bathe

and shower in it, thus inhaling small quantities of farm

chemicals and absorbing them through the skin. Naturally, the

problem is at its worst in agricultural areas of the country.

The most common contaminants are carbamate insecticides

(aldicarb and others), the triazine herbicides (atrazine and

others) and nitrate nitrogen.[1] For years government scientists

have tested each of these chemicals individually at low levels

in laboratory animals -- searching mainly for signs of cancer --

and have declared each of them an " acceptable risk " at the

levels typically found in groundwater.

Now a group of biologists and medical researchers at the

University of Wisconsin in Madison, led by Warren P. Porter, has

completed a 5-year experiment putting mixtures of low levels of

these chemicals into the drinking water of male mice and

carefully measuring the results. They reported recently that

combinations of these chemicals -- at levels similar to those

found in the groundwater of agricultural areas of the U.S. --

have measurable detrimental effects on the nervous, immune and

endocrine (hormone) systems.[2] Furthermore, they say their

research has direct implications for humans.

Dr. Porter and his colleagues point out that the nervous system,

the immune system, and the endocrine (hormone) system are all

closely related and in constant communication with each other.

If any one of the three systems is damaged or degraded the other

two may be adversely affected. The Wisconsin researchers

therefore designed their experiments to examine the effects of

agricultural chemicals on each of the three systems

simultaneously. To assess immune system function, they measured

the ability of mice to make antibodies in response to foreign

proteins. To assess endocrine system function, they measured

thyroid hormone levels in the blood. And to assess nervous

system function they measured aggressive behavior in the

presence of intruder mice introduced into the cages. They also

looked for effects on growth by measuring total body weight and

the weight of each animal's spleen.

The experiments were replicated many times, to make sure the

results were reproducible. They found effects on the endocrine

system (thyroid hormone levels) and the immune system, and

reduced body weight, from mixtures of low levels of aldicarb &

nitrate, atrazine & nitrate, and atrazine, aldicarb & nitrate

together. They observed increased aggression from exposure to

atrazine & nitrate, and from atrazine, aldicarb & nitrate

together.

The Wisconsin research team wrote, " Of particular signficance in

the collective work of Boyd and others,[3] Porter and others,[4]

and our current study[2] is that THYROID HORMONE CONCENTRATION

CHANGE was consistently a response due to mixtures, but NOT

usually to individual chemicals. " [Emphasis in the original].

In the five-year experiment, thyroid hormone levels rose or fell

depending upon the mixture of farm chemicals put into the

drinking water. Dr. Porter and his colleagues present evidence

from other studies showing that numerous farm chemicals can

affect the thyroid hormone levels of wildlife and humans. PCBs

and dioxins can have similar effects, they note. Proper levels of

thyroid hormone are essential for brain development of humans

prior to birth. Some, though not all, studies have shown that

attention deficit and/or hyperactivity disorders in children are

linked to changes in the levels of thyroid hormone in the blood.

Children with multiple chemical sensitivity (MCS) have abnormal

thyroid levels. Furthermore, irritability and aggressive behavior

are linked to thyroid hormone levels.

Interviewed recently by Hamm of the SANTA BARBARA [CAL.]

INDEPENDENT,[5] Dr. Porter explained, " Earlier work had shown

that thyroid hormone typically changed when exposure to these

pesticides occurred. Thyroid hormone not only affects and

controls your metabolic rate, that is, how fast you burn food,

it also controls your irritability level. For example, Type A

personalities are more assertive, more aggressive, more hyper.

These people tend to have higher levels of thyroid hormone. Type

B personalities--people that are really laid back, really take

things very easily--have lower levels of thyroid hormone. We

expected that changes in thyroid [would] change irritability

levels. This was a concern because there was information that

kids are getting more hyper and [that their] learning abilities

are going down, " Dr. Porter said.

A recent study of 4 and 5 year-old children in Mexico

specifically noted a decrease in mental ability and an increase

in aggressive behavior among children exposed to pesticides.[6]

A. Guillette and colleagues studied two groups of Yaqui

Indian children living in the Yaqui Valley in northern Sonora,

Mexico. One group of children lives in the lowlands dominated by

pesticide-intensive agriculture (45 or more sprayings each year)

and the other group lives in the nearby upland foothills where

their parents make a living by ranching without the use of

pesticides. The pesticide-exposed children had far less physical

endurance in a test to see how long they could keep jumping up

and down; they had inferior hand-eye coordination; and they

could not draw a simple stick figure of a human being, which the

upland children could readily do.

Notably, in the Guillette study we find this description of the

behavior of pesticide-exposed children: " Some valley children

were observed hitting their siblings when they passed by, and

they became easily upset or angry with a minor corrective

comment by a parent. These aggressive behaviors were not noted

in the [pesticide-free] foothills [children]. "

The human body can defend itself against poisons to some degree,

but Dr. Porter and his colleagues describe ways in which

low-level mixtures of pesticides and fertilizer might get past

the body's defenses:

The body is prepared to protect itself against poisons taken by

mouth. The liver begins to produce enzymes that try to break

down fat-soluble chemicals. However, if a poison enters through

the lungs or the skin, the body does not offer the same kind of

defenses. Furthermore, the body's ability to put up defenses may

be compromised by taking certain medications (e.g.,

antibiotics), or by receiving " pulses " of toxins rather than a

steady dose.

Receiving " pulses " of poisons would be normal in the case of

agricultural poisons which are sprayed onto crops only at

certain times of the year. During those periods, people living

near sprayed fields might get a sudden dose of poison via their

lungs, their skin and their drinking water. Dr. Porter describes

such a situation this way:

" Imagine [that] you're standing in a boxing ring and a boxer

jumps in with you, and he walks toward you smiling with his hand

outstretched. And you reach out to shake his hand and he smacks

you in the stomach as hard as he can. And when you bring your

arms up to defend yourself, he backs away. Finally you get tired

of holding your defenses up and you drop them and he rushes in

and smacks you again. That's the physical equivalent to a 'pulse

dose,' which is normally what we tend to get exposed to.

" The defenses we have take a while to induce, just like it takes

a while to bring your arms up. It takes anywhere from a half a

day to five days to induce those [defenses] to appropriate

levels. If you're in a particular stage of your hormone cycle or

you're taking some antibiotics, it can compromise your ability

to defend yourself even if you did have enough time to induce

your defenses. If you've got pulse doses coming in under your

defenses or coming in faster than you can bring your defenses up

then you've got a situation where you're totally vulnerable.

" If you've got a pregnant mom, for example, in day 20 when the

fetus's neural tube is closing and she gets an exposure, she

hasn't had enough time to induce her defenses. Her thyroid level

goes up or goes down, the hormone crosses the placenta and can

permanently alter the developmental pattern of the fetus's

brain. And then the pulse dose is gone, you have no detection,

mom doesn't even know she's pregnant, and you may have an

offspring that is neurologically compromised and wonder, 'How

did this happen?' "

In the interview with Hamm, Dr. Porter expressed concern

for the overall effect of pesticides on the nation's children:

Hamm: " Are pesticides, herbicides, and fertilizer used more or

less these days than fifty years ago and have the toxicities

changed? "

Porter: " The usage has continued to climb. There's an enormous

amount of these [chemicals being used] right now. There was a

recent study that examined the urine of people across the

country, [asking] if people are being exposed. On average,

anywhere from five to seven compounds were being excreted.

There's a great deal of expo- sure to the general populace.

" And yes, the toxicities have definitely changed. [some

toxicities are now measured] in the parts-per-trillion range. I

would point out that fetuses are sensitive to chemicals in the

parts per quadrillion range. "

Hamm: " I would assume that most people in this country are

eating conventionally grown food. If that's the case, wouldn't

the problems be more apparent? Why are there not more

hyperaggressive dim-witted people with poor immune systems? "

Porter: " If we really looked carefully at what's been happening

in this county, you might find exactly that happening. "

* * *

Because of recent violence in small cities and towns (such as

Littleton, Colorado, Laramie, Wyoming, and Jasper, Texas), this

is a time when Americans are searching for the causes of violence

in their society. Some are blaming a decline in religious

upbringing. Others are blaming households with the parents

working and no one minding the kids. Some say the cause is

violent movies, violent TV and extremist internet sites, combined

with the ready availability of cheap guns. Still others point to

a government that has often sanctioned the violence of " gunboat

diplomacy " to open foreign markets for U.S. corporations.

No one seems to be asking whether pesticides, fertilizers and

toxic metals [see REHW #529, #551] are affecting our young

people's mental capacity, emotional balance, and social

adjustment. From the work of Warren Porter, Guillette

and others, it is apparent that these are valid questions.

-- Montague

(National Writers Union, UAW Local 1981/AFL-CIO)

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[1] Jack E. Barbash and A. Resek, PESTICIDES IN GROUND

WATER (Chelsea, Michigan: Ann Arbor Press, 1996); Wiles

and others, TAP WATER BLUES (Washington, D.C.: Environmental

Working Group, 1994); A. Cohen and Wiles, TOUGH TO

SWALLOW (Washington, D.C.: Environmental Working Group, 1997);

Environmental Working Group, POURING IT ON; NITRATE

CONTAMINATION OF DRINKING WATER (Washington, D.C.: Environmental

Working Group, 1996). See www.ewg.org. And: M. Solomon and

Lawrie Mott, TROUBLE ON THE FARM; GROWING UP WITH PESTICIDES IN

AGRICULTURAL COMMUNITIES (New York: Natural Resources Defense

Council, October, 1998).

[2] Warren P. Porter, W. Jaeger and Ian H. Carlson,

" Endocrine, immune and behavioral effects of aldicarb

(carbamate), atrazine (triazine) and nitrate (fertilizer)

mixtures at groundwater concentrations, " TOXICOLOGY AND

INDUSTRIAL HEALTH Vol. 15, Nos. 1 and 2 (1999), pgs. 133-150.

[3] C.A. Boyd, M.H. Weiler and W.P. Porter, " Behavioral and

neurochemical changes associated with chronic exposure to

low-level concentration of pesticide mixtures, " JOURNAL OF

TOXICOLOGY AND ENVIRONMENTAL HEALTH Vol. 30, No. 3 (July 1990),

pgs. 209-221.

[4] W.P. Porter and others, " Groundwater pesticides: interactive

effects of low concentrations of carbamates aldicarb and

methamyl and the triazine metribuzin on thyroxine and

somatotropin levels in white rats, " JOURNAL OF TOXICOLOGY AND

ENVIRONMENTAL HEALTH Vol. 40, No. 1 (September 1993), pgs.

15-34. And see: W.P. Porter and others,

" Toxicant-disease-environment interactions associated with

suppression of immune system, growth, and reproduction, " SCIENCE

Vol. 224, No. 4652 (June 1, 1984), pgs. 1014-1017.

[5] Hamm, " What's In the Mix? " SANTA BARBARA [CALIFORNIA]

INDEPENDENT April 15, 1999, pg. 21 and following pages. See

www.independent.com/007/001/002.html. Thanks to Rauh for

alerting us to this interview.

[6] A. Guillette and others, " An Anthropological

Approach to the Evaluation of Preschool Children Exposed to

Pesticides in Mexico, " ENVIRONMENTAL HEALTH PERSPECTIVES Vol.

106, No. 6 (June 1998), pgs. 347-353.

Descriptor terms: violence; hormones; thyroid hormone;

development; aggression; chemicals and behavior; behavior and

chemicals; delinquency; studies; mexico; warren p. porter;

elizabeth guillette; adhd; attention disorders; hyperactivity;

learning disabilities; brain development; emotional stability;

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-- Montague, Editor

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