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Hmm...

http://archive.greenpeace.org/~usa/r...sity/glyp.html


Glyphosate Fact Sheet

This fact sheet describes the basic properties of glyphosate and the
issues surrounding glyphosate resistance and weed control. Glyphosate
is a broad spectrum herbicide used to kill crop weeds. Monsanto’s
trade name for this is Roundup. Roundup Ready crops are engineered to
withstand exposure to glyphosate. This allows applications of the
herbicide after crop emergence, killing weeds but not Roundup
resistant crop plants such as RRS (Roundup Ready Soybeans).

Description

Chemically, glyphosate is an organophosphate like many other
pesticides but it does not affect the nervous system as other
organophosphates do. It is a broad spectrum, non-selective herbicide
which kills all plants, including grasses, broad leaf and woody
plants. It is absorbed mainly through the leaves and is transported
around the whole plant, killing all parts of it. It acts by inhibiting
a biochemical pathway, the shikimic acid pathway. At low levels of
application it acts as a growth regulator.

There are three forms of glyphosate used as weed killers;
glyphosate-isopropylammonium and glyphosate-sesquiodium patented by
Monsanto and glyphosate-trimesium, patented by ICI (now Zeneca). Other
common brand names are Rodeo, Accord and Vision.

Glyphosate is technically extremely difficult to measure in
environmental samples. Only a few laboratories have the sophisticated
equipment and techniques necessary. This means that data is often
lacking on residue levels in food and the environment and existing
data may not be reliable.

Use In Weed Control

Glyphosate product sales are worth $1,200 million a year. In the US,
glyphosate was used on about 12-25 million acres annually in the
1980s. In the UK it was used on almost 800,000 acres in 1994. Because
it is broad spectrum in action it is used to control a great variety
of annual, biennial, and perennial grasses, sedges, broad leafed weeds
and woody shrubs. It is used in fruit orchards, vineyards, conifer
plantations and many plantation crops (e.g. coffee, tea, bananas); in
pre-crop, post-weed emergence in a wide range of crops (including
soybean, cereals, vegetables and cotton); on non-crop areas (e.g. road
shoulders and rights of way); in cereal stubble; forestry; gardening
and horticulture. Other uses of salts of glyphosate are in growth
regulation in peanuts and in sugarcane to regulate growth and speed
fruit ripening.

Human Toxicity

Because the shikimic acid pathway does not exist in animals, the acute
toxicity of glyphosate is very low. Glyphosate can interfere with some
enzyme functions in animals but symptoms of poisoning are only seen at
very high doses. However, products containing glyphosate also contain
other compounds which can be toxic. In particular most contain
surfactants known as polyoxyethyleneamines (POEA). Some of these are
much more toxic than glyphosate. These account for problems associated
with worker exposure. They are serious irritants of the respiratory
tract, eyes and skin and are contaminated with dioxane (not dioxin)
which is a suspected carcinogen. Some are toxic to fish.

In California, glyphosate is the third most commonly-reported cause of
pesticide related illness among agricultural workers. Glyphosate is
the most frequent cause of complaints to the UK’s Health and Safety
Executive’s Pesticides Incident Appraisal Panel. New formulations,
with less irritating surfactants, have been developed by Monsanto
(e.g. Roundup Biactive), but cheaper, older preparations are still
available.

Environmental Toxicity

Glyphosate is one of the most toxic herbicides, with many species of
wild plants being damaged or killed by applications of less than 10
micrograms per plant. Glyphosate can be more damaging to wild flora
than many other herbicides, as aerial spraying with glyphosate can
give average drifts of 1200 to 2500 feet and ground spraying with
glyphosate may cause damage to sensitive plants up to 300 feet from
the field sprayed. Glyphosate use is thought to affect hedgerow trees,
causing die-back, and may reduce trees' winter hardiness and
resistance to fungal disease

The direct toxicity of glyphosate to mammals and birds is low.
However, its effect on flora can have a damaging effect on mammals and
birds through habitat destruction. The US EPA concluded that many
endangered species of plants, as well as the Houston toad, may be at
risk from glyphosate use.

Fish and invertebrates are more sensitive to formulations of
glyphosate. As with humans, the surfactants are responsible for much
of the harm . Toxicity is increased with higher water temperatures,
and pH. In Australia, guidelines state that most formulations of
glyphosate should not be used in or near water because of their toxic
effects on tadpoles and adult frogs. The newer, non-irritant
formulations such as Roundup Biactive are not included in this advice.

Of nine herbicides tested for their toxicity to soil microorganisms,
glyphosate was found to be the second most toxic to a range of
bacteria, fungi, actinomycetes and yeasts. However, when glyphosate
comes into contact with the soil it rapidly binds to soil particles
and is inactivated. Unbound glyphosate is degraded by bacteria. Low
activity because of binding to soil particles suggests that
glyphosate's effects on soil flora will be limited. However, some
recent work shows that glyphosate can be readily released from certain
types of soil particles, and therefore may leach into water or be
taken up by plants.

Impact Of Genetically Engineered Herbicide Resistant Crops

The introduction of crops engineered to be resistant to glyphosate
could have two particularly damaging effects. Firstly, it will
increase the use of the herbicide, and secondly, it may encourage the
emergence of herbicide resistant weeds.

Monsanto claim that the introduction of herbicide resistant crops will
reduce the overall amount of herbicide used. They argue that
glyphosate will replace other, more environmentally damaging
herbicides, because only glyphosate need be used rather than several
different compounds. They also argue that weed killer will be used
less frequently on resistant crops. Importantly they also consider
glyphosate to be 'environmentally friendly' and a 'safe' herbicide,
basing this claim on its reduced soil particle binding and low
toxicity to humans.

Other herbicides used on soybeans and other crops are unquestionably
harmful to the environment and human health. The question is whether
glyphosate is really any less harmful and whether herbicide resistant
plants will reduce the amount of potentially damaging chemical to the
environment. Evaluating overall amount of use on a weight or volume
basis does not allow for the differences in toxicity between
chemicals. Weight or volume of total herbicide may decrease simply
because glyphosate is more effective at killing plants than many other
chemicals. Glyphosate is already the eleventh most widely used
pesticide in the US on a volume basis. Its damaging impacts on the
environment have already been described.

Whether there will be a reduction in the number of times herbicide is
used is also questionable. In their documents prepared for the US
authorities, Monsanto say that under current regimes, between one and
five applications of different herbicides or herbicide mixtures are
needed to control weeds in soybean crops, while with Roundup Ready
soybeans only "one or possibly two" applications of Roundup will be
needed. Yet in their information for farmers in Argentina, Monsanto
recommends Roundup be used with Roundup Ready soybeans before sowing,
when the young plant has three to four leaves and then whenever the
farmers find weeds. This is "at least twice and probably more
frequently".

Herbicide Resistance In Weeds

One of the major concerns of weed scientists is that the emergence of
herbicide resistant weeds may be encouraged by the use of herbicide
resistant plants. Herbicide resistance arises in an analogous fashion
to the emergence of antibiotic resistance in bacteria. Mutations occur
in plants and when one arises which makes it resistant to the
herbicide, it will have an advantage and grow and flourish when other
plants are killed Resistance to glyphosate is easy to induce in plants
in the laboratory. Monsanto claims resistance to glyphosate is
unlikely to emerge in the field because it does not persist in soil.
However, weed resistance to paraquat, an herbicide which has a shorter
soil persistence than glyphosate, is already a serious problem. One
weed specialist concluded, by comparison to paraquat, that "Presumably
glyphosate resistance can also be obtained with multi-annual
treatments" (Gressel, in Cassley et al, 1991). Roundup Ready soybeans
are intended to be used with "multi-annual treatments" and so the
emergence of resistance will be encouraged. Even before the increased
use of glyphosate expected with the introduction of resistant crops,
there has already been a report of glyphosate resistance in a weed
which occurred in ryegrass in Australia.

Glyphosate resistant weeds could also arise if there is gene flow
between the soybean and a related wild plant or if the soybean
survives to emerge as a weed ("a volunteer") in the subsequent crop.
Gene flow is possible in the Far East where soybean originated and
wild related plants exist. Herbicide resistant volunteers may be a
problem where mild climates occur and overwintering of soybean is
possible.

Herbicide resistant crops are an expensive problem for farmers. Having
weeds resistant to another herbicide, triazine, have been estimated to
cost farmers up to $10 an acre in extra weed control expenditure.
There would be an extra penalty for farmers growing glyphosate
resistant crops if glyphosate resistant weeds evolved, because not
only would they have to change their weed control practices but they
would have paid a premium for the herbicide resistant seed in the
first place.

Thus herbicide resistant soybeans promise increased herbicide use and
associated damage to the environment, together with an increased risk
of weed resistance, which would be a costly problem for farmers.

Sources:

Active Ingredient Fact Sheet: Glyphosate. Pesticide News 33 pp28-29,
September 1996.

Breeze, V, Thomas, G & Butler, R (1992) Use of a model and toxicity
data to predict risks to some wild plant species from drift of four
herbicides. Annals of Allied Biology 121: 669-677

Carlisle S.M. & Trevors, J.T. (1988) Glyphosate in the environment.
Water Soil and Air Pollution. 39: 409-420

Casley J C., Cussans G W & Atkin R K (eds) (1991) Herbicide resistance
in weeds and crops. Oxford: Butterworth-Heinmann

Marrs, R H, Williams, C T, Frost, A J & Plant, R A (1989) Assessment
of the effects of herbicide spray drift on a range of plants of
conservation interest. Environmental Pollution 59: 71- 86

New Scientist, 6 July 1996, p6

Petition for determination of nonregulated status of soybeans with a
Roundup Ready gene. Agricultural Group of Monsanto to APHIS, USDA,
1993.

US-EPA RED Facts: Glyphosate, September 1993

Yates W E., Akesson N B & Bayer D E (1978) Drift of glyphosate sprays
applied with aerial and ground equipment. Weed Science 26 (6): 597-604

GREENPEACE, April 1997

1436 U St. NW, Washington DC 20009

This report © Greenpeace 1997

Original Article:
http://www.greenpeaceusa.org/media/f...lyphosatetext.



"Nature, left alone, is in perfect balance.
Harmful insects and plant diseases are always present,
but do not occur in nature to an extent which requires the use of poisonous chemicals.
The sensible approach to disease and insect control is to grow sturdy crops in a healthy environment."

Masanobu Fukuoka, One Straw Revolution--1978