PESTICIDES - Getting on our nerves

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Friday, January 18, 2002

Getting on our nerves

By Diane Marty, E/The Environmental Magazine

The same herbicides and pesticides many people trust enough to spray

on their gardens and crops have been increasingly linked to the onset

of Parkinson's Disease (PD), a neurodegenerative disorder that turns

the simplest movement into a battle between the brain and the nerves.

The first connection was made in the early 1980s, when young people

illegally taking an impure form of Demerol (MPTP) exhibited symptoms

of an advanced form of this progressive disease. The chemical

structure of MPTP resembles that of paraquat, an herbicide. During the

past two decades, researchers have continued to explore the

associations between pesticides and PD, and some positive correlations

have been found.

" I was surprised at how accurately rats developed the signs of

Parkinson's, " said Dr. J. Greenamyre, a researcher at Emory

University. The rats in the study had been infused with the pesticide

rotenone. Because it is often labeled as a " natural " pesticide, many

home gardeners feel safe sprinkling rotenone on their tomatoes.

Rotenone is also used to kill nuisance fish in lakes and reservoirs

and fleas and ticks on pets.

In a recent Stanford study, Parkinson's patients were twice as likely

to have been exposed to in-home insecticides than those people without

the disease. People exposed to herbicides also were more likely to

develop PD.

A large case-controlled study at the Henry Ford Health System in

Detroit, Mich., confirmed that connection. " Contact with herbicides

gave people a four times greater chance of developing Parkinson's, "

said Dr. Jay M. Gorell, head of the Movement Disorders Clinic in the

Neurology Department. And people exposed to insecticide were 3.5 times

more likely to be diagnosed with Parkinson's disease than people with

no history of pesticide exposure.

" The study also searched for a relationship between Parkinson's

disease and farming and found it, " said Gorell. " Farmers were 2.8

times as likely to have PD as the general population. "

A COMMON DISORDER

More than 1 million Americans have Parkinson's, and every nine minutes

another person is diagnosed with the disease. PD is second only to

Alzheimer's disease as the most common neurodegenerative disorder in

the United States.

First described by the English physician Parkinson in 1817, this

condition kills the nerve cells in the brain that release dopamine, a

chemical necessary for controlling movements. Normal everyday tasks,

such as buttoning a shirt, rising from a chair, or writing a letter,

become hardships and eventually impossible.

" In order to discover and define cause-and-effect relationships

between pesticides and PD, we'll need to be very clever in a couple of

ways, " said Gorell. First, coding for genetic variants, analyzing the

biochemical actions between pesticides and genes, and calculating the

ability of each person's body to metabolize various chemicals will

require much more research, innovative models, and precise

measurements. " Second, people may or may not be aware of their

lifetime history of contact with pesticides, " added Gorell. " Experts

are searching for ways to quantify past exposures. "

The weight of heredity is another factor to gauge when studying this

disease, although most experts now consider the family tree a

significant factor only when studying patients who are 50 years old or

younger at the onset of PD. Today, just 10 percent of Parkinson's

cases are attributed directly to heredity.

Most researchers agree that a sophisticated interrelationship between

genetic susceptibility and environmental exposures may hold the key to

unlocking the causes of PD. The former remains an illusive quality.

But the latter can be measured to some extent.

ENVIRONMENTAL EXPOSURE

The Centers for Disease Control and Prevention (CDC) began an ongoing

study in 1999 in an effort to calculate the public's exposures to

environmental contaminants, including mercury, tobacco smoke, and

certain pesticides. By taking blood and urine samples, scientists can

monitor the population's contact with chemicals present in the air,

water, dust, food, and soil over time.

" So far, the results of the initial CDC National Report on Human

Exposure to Environmental Chemicals confirm what many people already

suspected, " said Kegley, staff scientist at Pesticide Action

Network North America (PANNA). PANNA works to replace pesticide use

with ecologically sound and socially just alternatives. " The general

population has contaminant levels exceeding those set by the

Environmental Protection Agency (EPA) as safe, " she said.

Kegley finds the CDC data especially significant because only known

ill effects, which usually involve acute poisoning as opposed to

chronic exposures, determine EPA guidelines. The EPA also tests

chemicals separately instead of examining combinations of compounds.

" The effects of human exposure to more than a single pesticide at one

time are not apt to be less harmful, " said Kegley.

In the meantime, people concerned with limiting their exposure to

pesticides should become familiar with both the common and

not-so-common ways they come into contact with these chemicals.

" Residues on food and home-and-garden insecticides are well-known ways

for people to be exposed to pesticides, " said Jay Feldman, executive

director of Beyond Pesticides (BP), which is committed to pesticide

safety and the adoption of alternative pest-management strategies.

" But laundry and bathroom products, such as sanitizers and mildew

removers, also contain pesticides, " said Feldman. " The chemicals

commonly used to keep backyard swimming pools clean and clear are

laced with pesticides. " Institutions and businesses are consumers of

these products too. No less than 21 neurotoxins are used in schools.

When attempting to calculate their pesticide exposures, people often

neglect to consider those elements not in their direct control.

" Spraying of nearby agricultural fields or monthly applications by the

neighbor's lawn service cause drift that can be a significant source

of pesticide exposure, " said Kegley.

SIMPLE PREVENTION

The irony is that simple and inexpensive strategies can outwit

unwelcome intruders. " Sanitation, of course, is always a first course

of action, " said Feldman. " Maintenance, such as caulking regularly,

repairing screens, and eliminating damp spaces, prevents infestations.

Outside, flowerpots, leaky gutters, and birdbaths breed mosquitoes and

other insects. Removing or repairing these hot spots will reduce

resident bugs. And protective clothing circumvents the need for

insecticide sprays. "

" Soap and water discourages many plant pests, " said Steve Tvedten,

president of Get Set, a company specializing in nontoxic pest control.

A quick spray of glass cleaner sends flying insects into a nosedive.

Talcum powder obscures ant trails, and razing webs sends spiders

scattering. Vacuum cockroaches (for sneak attacks, catch the invaders

in a beam of red light) and other bugs. The dust kills them faster

than many sprays. In the garden, know your pests and cultivate their

enemies.

If those ideas fail, the next step should involve mechanical and

low-toxicity products. " Flying insect traps, roach and rodent

`motels,' even old-fashioned flypaper, can all lower pesky

populations, " said Feldman. Bait traps are the next-best method.

Diet has a huge effect on the amount of pesticides people ingest.

Researchers at the University of Washington in Seattle analyzed the

urine of 100 children. " Ninety-nine of the kids had detectable levels

of pesticides in their systems, " said Kegley. " The only participant

with no evidence of exposure ate organic food. " She added that if

organic foods are not available, take extra care washing those fruits

and vegetables known to have higher pesticide residues, including

strawberries, pears, grapes, green beans, peaches, winter squash, and

leafy green vegetables, especially spinach.

" Pesticides have become omnipresent in our rain and air, " said

Tvedten. " Chemicals used in Africa find their way to Florida in a

short amount of time. And our generation has been exposed to more than

500 toxins that our grandparents weren't. Even if pesticides were

safe, they're not always effective. If they were, we wouldn't continue

to need them. And already, more than one-half of the pests are

resistant to poisons. " The bad news is we may not be.

Diane Marty is a Colorado-based freelance writer.

Copyright 2002, E/The Environmental Magazine