By CAROL BENFELL
THE PRESS DEMOCRAT
July 22, 2005
The plant-killer
glyphosate now being sprayed in the Laguna de Santa Rosa is one of the
herbicides least dangerous to humans, according to the federal and state
Environmental Protection Agencies and the World Health
Organization.
Glyphosate is less toxic, for example, than the caffeine in
coffee, said Joel Trumbo, an environmental scientist in the Pesticide
Investigations Unit of the state Department of Fish and Game. "A cup of coffee
is 26 times more toxic than a cup of glyphosate," he said.
That's why the
Laguna Foundation, over the objections of anti-spraying groups, picked
glyphosate to beat back an invasive water weed that is choking the Laguna and
providing refuge for West Nile-carrying mosquitoes. The environmental group is
spearheading the spraying as a first step toward restoration.
"It was one
of our big concerns," said project manager Julian Meisler. "What could we use
that was the least toxic and still be effective? This turned out to be the best
one."
Spraying opponents are not convinced. They fear the herbicide will
drift through the air or enter the ground water, harming people and other living
things.
Another concern is that the glyphosate will not break down
properly in the flood control channels, but will instead sink into the sediments
and "create a toxic ooze and dead zone," said Barbara Greene, founder of the
Rohnert Park and Cotati Creeks Council, a grass-roots group.
"Glypro," the trade name of the material being sprayed at the Laguna, is approximately 54
percent glyphosate and 46 percent water. It works by blocking an enzyme the
plant uses as a building block for amino acids. Without the amino acids, the
plant cannot make the proteins necessary for its life processes and
dies.
The material being sprayed at the Laguna also contains Cygnet Plus,
which is made from the bark of pine trees and is used to help the glyphosate
adhere to Ludwigia leaves. Another addition is Sta Put, a polyvinyl polymer
solution that makes the drops of spray big and heavy, so they don't drift easily
through the air.
Some 122 gallons of the stuff are being sprayed on 130
acres of the Laguna channel between Occidental and Guerneville roads, according
to the permit granted by the North Coast Regional Water Quality Control
Board.
The second phase of spraying will begin next week, when 24 gallons
of the Glypro mixture will be applied to 25 acres of the Wilfred/Bellevue flood
control channel near Rohnert Park.
The state Environmental Protection
Agency and the state Department of Pesticide Regulation classify glyphosate as
one of the least toxic herbicides. It is a Group E carcinogen, meaning it is
believed not to cause cancer because it did not cause cancer in laboratory
animals.
Nevertheless, the chemical can affect health. Direct contact
with glyphosate can cause eye or skin irritation or difficulty breathing.
Lifetime exposures have the potential to cause kidney damage and affect
reproduction, according to the U.S. Environmental Protection Agency.
The
health issue is determined by exposure - how toxic glyphosate is and how long a
person or animal is exposed to it, Trumbo said. "Any compound can be toxic,
including water, if you have a high enough exposure."
The spraying is
expected to affect only the Ludwigia, partly because the plant is easy to
target. It is huge, covers the waterway in many places and has choked out other
plants.
Glyphosate has a half-life - meaning 50 percent of it is gone -
of one to 174 days. Its life span depends on the amount of naturally occurring
microbes in soil and water. The fewer microbes, the longer the chemical
lasts.
"If you have glyphosate in cold, dark, biologically dead soil or
ground water, it's going to hang around longer," Trumbo said.
Trumbo said
it was difficult to imagine a scenario where enough glyphosate could accumulate
in soil or air or water to cause harm.
"It would take very, very high
concentrations of the compound to kill aquatic life - very, very much higher
than the label amounts," he said.
Some spraying opponents base their
arguments on a lengthy article in the quarterly magazine published by the
Northwest Coalition for Alternatives to Pesticides, an Oregon-based
anti-pesticide group.
The article details studies linking
glyphosate-based herbicides to increased risk of non-Hodgkins lymphoma,
attention deficit disorder, genetic changes, miscarriages and deformities in
tadpoles and insects.
Those studies, however, were done using Roundup,
not Glypro, said Caroline Cox, staff scientist with the Northwest Coalition and
the author of the article.
Roundup is a combination of glyphosate and a
surfactant (a surface-active substance), which is more toxic than glyphosate
alone, Cox and other scientists agreed.
The Northwest Coalition is
opposed to the use of glyphosate and other herbicides because it's impossible to
know if they're safe, Cox said.
"There's no way you're ever going to be
able to say something is safe. We keep discovering new problems that nobody
thought about 10 or 20 or 50 years ago," Cox said.
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