Organic Consumers Association

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Monsanto's Toxic Herbicide Glyphosate: A Review of its Health and Environmental Effects

Glyphosate is the active ingredient of some of the most common herbicides used in farming and gardening. These products have been promoted as quickly biodegradable and non toxic. People believe that they are so safe that you can drink a cup of these herbicides without any ill effect.

Consequently, it is sprayed on roadsides while people are driving, on footpaths when people are shopping and in schoolyards and sports fields, exposing children to drift and residues. People buy it from supermarkets or garden shops and use it without any protective clothing because it is deemed 'safe'. It is sprayed in national parks and other environmentally sensitive areas in the belief that it is not toxic and or residual.

I continuously hear Primary Industries officers and other agricultural specialists telling farmers that it is not necessary to wear any protective clothing because it is harmless.

Unfortunately, the facts show that this is not the case. While pure Glyphosate has a low acute toxicity (the amount needed to cause death), when it is sold as a commercial herbicide it is combined with surfactants and other ingredients to make it more effective at killing plants. Studies show that the commercial products, such as Round Up, can be three times more toxic than pure glyphosate.

Health Problems - so safe that you can drink it.

Japanese researchers analysing suicides have found that drinking 3/4 of a cup (200 millilitres) of commercial glyphosate products is fatal.

Survivors (those who consumed less than 3/4 of a cup) suffered a range of severe health problems. These problems included intestinal pain, vomiting, erosion of the gastrointestinal tract, excess fluid in the lungs, pneumonia, lung dysfunction, clouding of consciousness, destruction of red blood cells, abnormal electrocardiograms, low blood pressure, kidney damage and damage to the larynx. It is important to note that damage to the kidneys and the lungs is usually permanent. These body tissues do not repair themselves, instead forming scar tissue that does not function to help filter toxins from the blood or breathe oxygen.

In California, where there is a mandatory system of reporting pesticide poisoning, Glyphosate is the third most common cause of pesticide illness in farm workers. It is the most common form of reported pesticide poisoning in landscape gardeners.

Two separate studies in Sweden have linked exposure to Glyphosate to Hairy Cell Leukemia and Non Hodgkins Lymphoma. These types of cancers were extremely rare, however non-Hodgkins lymphoma is the most rapidly increasing cancer in the Western world. It has risen by 73% in the USA since 1973. Another study has found a higher incidence of Parkinson disease amongst farmers who used herbicides, including glyphosate.

Other studies show that Glyphosate and commercial herbicides containing Glyphosate cause a range of cell mutations and damage to cell DNA. These types of changes are usually regarded as precursors to cancer and birth defects.

Reproductive Effects

Studies show that exposure to Glyphosate is associated with a range of reproductive effects in humans and other species. Research from Ontario, Canada found that a father's exposure to Glyphosate was linked to an increase in miscarriages and premature births in farm families.

Glyphosate caused a decrease in the sperm count of rats and an increase in abnormal and dead sperms in rabbits. Pregnant rabbits exposed to Glyphosate had a decrease in the weight of their babies.


The proponents of Glyphosate herbicides promote them as environment friendly or benign. They say that they breakdown very quickly in the environment.

The facts show otherwise. A report from The United States Environmental Protection Agency states that Glyphosate is 'extremely persistent under typical application conditions'. It is one of the most residual herbicides, with studies in Sweden showing that one application can last up to 3 years.

In warmer climates, it can take less than a year per application for Glyphosate to degrade. However, when it breaks down it does not disappear into harmless basic elements. It degrades into an even more residual compound called aminomethylphosphonic acid (AMPA). While AMPA has a low acute toxicity, the studies conducted on this compound show that it damages the livers and bladders of rats. Unfortunately, very few long-term health and environmental studies are conducted on the breakdown products of synthetic chemicals.

Residues of Glyphosate have been found in a variety of fruits and vegetables. This is because it readily moves into all parts of a plant. As it is inside the plant tissues, it cannot be washed off.

Residues can be detected long after glyphosate treatments have been made. One study showed that lettuces contained residues five months after the field was treated with glyphosate. The disturbing thing about this research is that the lettuce seedlings were planted four months after the field was sprayed for weeds. The seedlings absorbed the glyphosate from the soil residues.

A World Health Organisation study revealed significant Glyphosate residues in wheat after harvest. Milling did not remove it, as it moves into the plant and the wheat seed. The study showed that cooking does not break down Glyphosate.

Environmental Effects

Glyphosate based herbicides have been shown to cause a significant decline of beneficial insect species in farms. Studies by the International Organization for Biological Control and other researchers have found that between 50 to 80 percent of beneficial insects are killed from exposure to residues of a Glyphosate herbicide.

Glyphosate is very toxic to fish and other aquatic organisms. Concentrations as low as 10 parts per million can kill fish. Daphnia, a very important part of the aquatic food chain, especially for fish, can be killed by as little as three parts per million. This is an important reason why it should not be used near waterways or in drains.

Glyphosate is extremely toxic to the soil life. One application can cause a dramatic plunge in the number of beneficial soil micro-organisms and arthropods. Studies show a reduction in the species that build humus, thus it contributes to the decline in soil organic matter.

Glyphosate significantly reduces the activity of nitrogen-fixing bacteria. These bacteria transform soil nitrogen into forms that plants can use. Studies of Soybeans grown for nitrogen fixation showed a reduction in the number of rhizobium bacteria and the nitrogen they produce when Glyphosate was used for weed control.

Other studies show that Glyphosate herbicides increase the susceptibility of plants to diseases. This is partly because it reduces the growth of mycorrhizal fungi and other beneficial fungi that help plants absorb nutrients and help fight disease. However, plants suffer more disease, as there is an increase in the soil pathogens and a decrease beneficial species that control diseases after an application of Glyphosate.

Glyphosate exposure damages or reduces the populations of earthworms. A New Zealand study showed that 5% of the usual application rate caused delayed development and increased death in earthworms.

Glyphosate reduces populations of small mammals and birds by damaging the vegetation that provides food and shelter for these animals. The populations of all of these living organisms can take years to recover due to Glyphosate's persistence in the soil.

Spray Drift

Glyphosate spray drift from both ground and aerial applications has been measured from 400 to 800 meters from the target site. Studies have shown that Glyphosate drift will cause more severe and extensive damage than many other herbicides. This is because it is a broad spectrum, non-selective herbicide and it is transported throughout the plant causing damage to the unexposed parts. This damage, when it does not kill the plants, can last for many years.

Drift that is one thousand times less than the usual application rates has been shown to damage surrounding vegetation, including the killing of wild plants. This is an important reason why it should not be used in national parks and environmentally sensitive areas for weed control.

Genetic Engineering

The use of glyphosate is expected to increase substantially in the next few years because several genetically engineered crops are "Roundup Ready" and will be grown by many farmers.

This expected increase in use has resulted in an application for the MRL (residue level) for glyphosate to be increased by 200 percent. This need to increase the permitted residue levels is due to genetically engineered herbicide tolerant crops using more chemicals, not less as the proponents of GMO's claim. These crops cannot be legally sold in Australia under the present residue levels, as the increased number of sprays will mean higher residue levels.

This need for a dramatic increase in residues demonstrates that this herbicide is residual. If it is rapidly degraded and leaves no residues as is commonly claimed, why is there a need for such a large increase on residues on the crop?

The persistent nature of these residues in genetically engineered food crops such as Soybeans, Corn and Canola is another reason why we need mandatory labelling of all GMO's. We need to have the freedom of choice to avoid foods that we believe will contain residues of toxic chemicals.

This is a very good reason for eating organic foods.


Glyphosate is widely used in the mistaken belief that it is harmless, safe and readily breaks down leaving no residues. Consequently, it is sprayed in public areas while people are present and by operators without protective clothing. These people are exposed to the drift of this herbicide. The facts show that Glyphosate causes a range of health problems to humans, plants and animals, it causes environmental problems and that it is highly persistent. It is time that the widespread use of this toxic chemical on roadsides, footpaths, parks, gardens, schools, farms, forestry, national parks etc was stopped or highly restricted.

Acknowledgments and References

Most of the information for this article came from an excellent paper authored by Caroline Cox in the JOURNAL OF PESTICIDE REFORM, Fall 1998, Vol.18, No. 3.

Updated 01-02, Northwest Coalition Against Pesticides, Eugene, Oregon.

Lehmann V. and Pengue W. (2000), Herbicide Tolerant Soybean: Just another step in a technology treadmill? Biotechnology and Development Monitor. September 2000.

Nordstrom M. et al, (1998), "Occupational exposures, animal exposure, and smoking as risk factors for hairy cell leukaemia evaluated in a case-control study," BRITISH JOURNAL OF CANCER Vol. 77 (1998), pp 2048-2052.

Hardell L. and Eriksson M. (1999), "A Case-Control Study of Non-Hodgkin Lymphoma and exposure to Pesticides," CANCER Vol.85, No. 6 (March 15, 1999).

Organic Producers Association of Queensland

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