Glyphosate, commonly known as Roundup(tm), is one of the world's most widely used herbicides. Because of its low acute toxicity rating it competes with paraquat. However, the toxicty of the pesticide product depends on its formulation and several are more toxic than the glyphosate itself. There is substantial evidence of human poisonings from the use of this pesticide.

Since glyphosate is absorbed by plants it cannot be completely removed by washing or peeling produce nor by milling, baking or brewing. It can persist in food products for up to two years. Its use as a pre-harvest desiccant and growth regulator is particularly problematic with respect to residues as there is insufficient time after use for the chemical to degrade before harvest.

Crops with genetically engineered resistance to glyphosate are being developed. This will probably lead to an increased use of glyphosate and may hasten the development of resistance among weeds.

Toxicity studies of glyphosate have shown the following effects: diarrhoea, increased blood glucose, red nasal discharge, pancreatic lesions, salivary gland lesions (possible evidence of an adrenalin mimic), growth retardation, and changes in the relative weights of organs.

The use of glyphosate may result in significant population losses of a number of terrestrial species through habitat and food supply destruction and thus cause a threat to endangered species and biodiversity. It also effects beneficial insects and earthworms. Nitrogen-fixation may be reduced, lowering soil fertility. It can increase the susceptibility of some non-target plants to fungal diseases, and interferes with other metabolic processes such as ion and lignin production.

Glyphosate can be persistent for more than three years in soils, depending on soil type and climate, and has been found in surface and groundwaters. Recent research shows that glyphosate may be more mobile in the environment than previously thought, indicating a greater risk of groundwater contamination. As it is absorbed by plants, glyphosate found it the soil can be taken up by plants long after its use.

N-(phosphonomethyl)glycine

Most formulations contain the isopropylamine ammonium salt of glyphosate

1071-83-6

38641-94-0 (isopropylamine salt)

70393-85-0 (glyphosate-sesquisodium)

81591-81-3 (glyphosate-trimesium)

Roundup is the most common trade name for glyphosate. Below are some tradenames under which it has been sold. The list is not necessarily complete, and some names may now be obsolete. Also, some products may contain other active ingredients in addition to glyphosate.

One of the most widely used broad spectrum (non-selective), systemic, post-emergence herbicide. It is used to control annual and perennial plants.

Glyphosate is used to control grasses, sedges, broadleaf weeds and woody plants. It is used on various crops, orchards, plantations, pastures, lawns, gardens, forestry, roadsides, and aquatic weed control. Other uses include pre-harvest desiccation of cotton, cereals, peas, beans, etc. The sodium salt (Quotamaster) is used on peanuts and as a growth regulator on sugar cane to hasten ripening, enhance sugar content and promote earlier harvesting.

US Environmental Protection Agency Toxicity Class III -- Mild irritant.

Exposure to users can occur through skin contact and lung, and to non-users through micro-droplet inhalation and food residues. Glyphosate is poorly absorbed by the stomach and absorption through the skin is low . (IPCS 1994)

Eye and skin irriation, cardiac depression, gastro-intestinal pain vomiting and accumulation of excess fluid in the lungs are symptoms of glyphosate poisoning (Cox, 1995)

Glyphosate and formulated products can be slightly to severely irritating to eyes and skin. (Agriculture Canada 1991, IPCS 1994)

Glyphosate is the most frequent cause of complaints and poisoning incidents recorded by the Health and Safety Executive in the UK. (Pesticides Trust, 1996)

Dr Ricky Gorringe of New Zealand estimates, based on cases at his clinic, that probably 1 in 20 New Zealanders are sensitive to Roundup. The most commonly occurring symptoms are unnatural fatigue, a band-like headache, a strange "spaced-out feeling with loss of confidence", a skin rash, and an otherwise unexplainable sudden increase in blood pressure. The symptoms are the result of micro-droplet inhalation, a route of exposure which is not well understood. (Watts 1994)

In the UK, a local authority has been prosecuted after a chid accidentally sprayed with glyphosate developed allergies. In St Just, Cornwall, resiedents claim sevrere reactions following glyphosate applications. (Pesticides Trust, 1996)

A Japanese study of people poisoned from swallowing Roundup identified the following symptoms: gastrointestinal pain and vomiting; swelling of the lungs and pneumonia; reduction of blood pressure; clouding of consciousness; and red blood cell destruction. The researchers attributed the symptoms to the surfactant POEA (which is added to make glyphosate stay on the leaves longer) rather than to glyphosate.(Sawada et al 1988)

Studies of humans have shown glyphosate to cause lung congestion or dysfunction; erosion of the gastro-intestinal tract and massive gastro-intestinal fluid loss; abnormal electrocardiograms and low blood pressure; kidney failure; and through direct skin contact swelling of the eye and lid, rapid heartbeat, raised blood pressure, swollen face, tingling of the skin, and recurrent eczema. Severe poisoning following ingestion of lethal amounts involves respiratory and kidney failure, cardiac arrest, coma, seizures, and death. (Cox ,1995; IPCS , 1994)

Among 94 people exposed to glyphosate in the US the following symptoms were noted: bronchial constriction, pleuritic chest pain and nasal congestion; blurred vision, corneal erosion and conjunctivitis; contact dermatitis; headache; nausea, diarrhoea and abdominal pain; irritability; excessive sweating; vertigo; malaise; swelling of extremities; and nervous system disorders (US EPA, 1980)

Increased respiratory problems have been reported in people handling flax retted with glyphosate pre-harvest, as opposed to those handling flax that had not been so treated. The acute response to flax dust is increased by the glyphosate causing increased shortness of breath, wheezing and coughing. (Jamison et al.,1986)

Short term exposure to glyphosate can cause breathing difficulties, loss of muscle control, and convulsions. Roundup has caused cardiac depression, mainly due to the surfactant POEA. (IPCS 1994)

Short term studies have shown the following symptoms: Increased serum glucose; increased blood potassium and phosphorus levels. At high doses increased blood urea, nitrogen and serum alkaline phosphatase; red nasal discharge; pancreatic lesions; growth retardation; salivary gland lesions; diarrhoea; changes in the relative weights of kidney, liver, thymus, heart and testes; inflammation of the gastric lining; dermal exposure resulted in very slight erythema and oedema, decreased food consumption, and decreased serum dehydrogenase. The salivary gland lesions indicate that glyphosate may be weakly mimicking adrenalin. (US EPA 1993; IPCS 1994)

The acute dose or concentration that will cause death are:

Oral LD50 (Rat) >4320 mg/kg

Dermal LC 50 (Rabbit) >2000 mg/kg

Acute toxicity of other common components in formulations are:

• * POEA: Oral LD50 (Rat) +/- 1860 mg/kg
• * Isopropylamine: Oral LD50 (Rat) 820 mg/kg

Laboratory trials have shown decreased body weight gain, increased incidence of cataract and lens abnormalities, increased liver weight, and degeneration of the liver and kidney at high doses. (US EPA 1993)

No information found. However there are reports of people with allergic reactions or sensitisation.to glyphosate (Pesticides Trust, 1996, Watts 1994)

No information found.

Effects suffered by rats (at high doses only) include reduced maternal body weight; decreased total implantations and number of viable foetuses; increased number of early mis-carriages; reduced litter size; reduced foetal and pup weight; and reduced ossification of the breast bone. A recent study in rabbits showed a significant adverse effect on libido, ejaculate volume and sperm concentration, with increased abnormal or dead sperm. (IPCS 1994; US EPA 1993; Yousef 1995)

No information found.

There is still considerable controversy over the carcinogenic potential of glyphosate. The conclusion generally reached by regulators is that glyphosate, and glyphosate-containing products, are not carcinogenic to humans. IPCS has concluded that "bioassays in mice and rats did not indicate that technical glyphosate was carcinogenic". It discounted a study that it said constituted evidence of cancer because a more recent study, at higher doses, did not show the same effect. (IPCS ,1994)

The US EPA has concluded that glyphosate is probably not carcinogenic to humans. However, this was based on the results of three studies which showed a variety of carcinogenic effects, all of which were considered not statistically significant:

There is no evidence of mutagenicity in studies of technical grade glyphosate, but some formulated products have been found to have weakly genotoxic effects:

The WHO has established an Acceptable Daily Intake (ADI) of 0.3mg/kg (Codex, 1993)

Remarks:

The toxicity of glyphosate formulations depends on the ingredients in the formulation. Many products are more toxic than glyphosate alone. POEA and glyphosate appear to have synergistic effects, with the toxicity of the product much greater than that of each ingredient.

The surfactant contained in the formulated product may vastly alter its toxicity: Roundup can be 30 times more toxic to fish than the glyphosate itself. Monsanto have recently introduced in New Zealand a new formulation, Roundup GII, with a surfactant [of unrevealed chemistry] that they claim makes it 90 times less toxic to rainbow trout than the more common Roundup formulation. (Servizi et al., 1987; Willocks, 1995).

Sublethal effects in fish include erratic swimming, laboured breathing, behavioural aberrations, and altered migration and reproduction. (Monroe 1990; Holtby & Baillie 1989).

Glyphosate is slightly toxic to aquatic microorganisms, but some formulations can be slightly to highly toxic. It can affect growth, greening process, aromatic amino acid synthesis, and photosynthesis in blue-green algae. (IPCS, 1994)

Under certain [unspecified] use conditions, glyphosate is expected to cause adverse effects to non-target aquatic plants. (US EPA, 1993)

A number of species of birds, mammals and beneficial insects suffer population loses through habitat and/or food supply destruction resulting from the use of glyphosate. There are also direct lethal and sublethal effects.

Exposure to freshly applied Roundup killed more than half of three species - a parasitoid wasp, a lacewing, and a ladybug - and more than 80 percent of a predatory beetle. Carabid beetle populations have shown significant decline and slow recovery after glyphosate application (Asterarki et al., 1992; Brust, 1990; Hassan 1988)

Glyphosate adversely affects a number of soil and plant fauna, such as the beneficial predatory mites. However, it prolonged larval survival of the foliar-feeding nematode Nothanguinea by 50% thus increasing the damage done by this pest. (Carlisle & Trevore, 1987; Eijsackers 1985)

Glyphosate may inhibit a number of fungi that decompose dead plant material. Roundup applied to the soil in repeated doses had a substantial adverse effect on the growth rate of earthworms. The reproductive capacity and the total population in the soil could be expected to fall following repeated low doses of biocides. IPCS, however, classifies glyphosate as having low toxicity to earthworms with a No Observed Effects Concentration of 158mg/kg. (Grossbard 1985; IPCS, 1994; Springett and Gray, 1992)

Laboratory studies show significant effects on nitrogen fixation, denitrification and nitrification. (IPCS 1994)

Many (more than 74 species) endangered plants in the USA may be at risk from the use of glyphosate. (US EPA ,1993, 1996)

Glyphosate in sublethal doses increases susceptibility of some plants (e.g. apples, barley, soya beans, tomatoes) to fungal diseases. (Carlisle & Trevore, 1987; Levesque & Rahe, 1992; Mekwatanakarn, 1987; Rue et al., 1992; Smiley, 1992)

Glyphosate can inhibit root nodulation and nitrogen-fixation in sub-clover, the effect occurring up to four months after glyphosate application. Glyphosate also inhibits fungi which help plants absorb nutrients and water. (Eberbach & Douglas 1983, 1989; IPCS 1994; Maartenson 1992)

Glyphosate in sub-lethal doses interferes with other metabolic processes in non-target plants: potassium and phosphate ion absorption may be inhibited in beans; and the production of lignin in asparagus and flax may be reduced. (Levesque & Rahe 1992; Sandquist 1979)

The development of genetically engineered crops resistant to glyphosate will progably lead to an increase in use of glyphoase. There is concern that glyphoaste resistance could be transfered to non-crop species. Already there are reports of resistance developing among major weeds such as rye grass (Pesticides Trust, 1996)

Soil Glyphosate is regarded as being "relatively persistent" in some soils, with a half-life varying from less than a week to 174 days, depending on the extent of soil binding and microbial breakdown. The more sand in a soil the greater the persistence; cooler climates also tend to increase persistence -- in Sweden, residues have been found up to three years after application. Microbial degradation results in the metabolite AMPA -- found mainly in the top six inches of soil, with a median half-life of 240 days, ranging up to 958 days in some soils. (Carlisle & Trevore, 1987; Eberbach & Douglas, 1983; IPCS, 1994; US EPA 1993)

Glyphosate is strongly bound to soil particles, and generally regarded as having low potential to contaminate groundwater. It tends to remain in the top six inches of soil, although in some soils residues have been found down to 18-24 inches. There is recent evidence of desorption of glyphosate from the soil particles which would result in glyphosate moving through soil and in groundwater. (IPCS 1994; Piccolo et al., 1994; US EPA, 1993)

Glyphosate is moderately persistent in water and not removed by normal drinking water processing. It is more likely to occur in surface waters than groundwaters. Glyphosate is soluble in water, but resistant to hydrolysis. It moves from water into sediment or suspended particles with a half-life ranging from a few days to 91 days. After a year, 0.1ppm of glyphosate was still found in the sediment of a farm pond. Glyphosate was calculated to have a half-life of 120 days in sediment. (Agriculture Canada 1991; IPCS, 1994; US EPA, 1993)

Glyphosate has been found in surface waters in Canada and in ground waters in the Netherlands and USA. One study detected glyphosate in a watershed 4 months after application. (Edwards et al., 1980; Frank, 1990; IPCS, 1994; US EPA, 1992)

Glyphosate and its metabolite AMPA are translocated throughout plant tissue, residues are unlikely to be completely removed from produce by washing, peeling or removing the outer leaves. Minimal breakdown of glyphosate occurs in plant tissue and pre-harvest use can result in significant levels of residues; in grains they are not destroyed by milling and much of it remains in the bran. Baking does not remove these residues. Residues in malting barley are transferred to beer. Use of glyphosate on forage and animal feed can result in residues in the kidneys, meat, milk and eggs. Residues are stable for up to one year in plant materials and in water, and two years in animal products, in storage. In the wild, residues of glyphosate can persist for a long time (45mg/kg found in lichens 270 days after application). Sampling of wild berries after forest spraying operations showed that residues remained above 0.1ppm for at least 61 days. (Roy et al 1989; Agriculture Canada 1991; IPCS 1994; US EPA 1993)

Residue analysis for glyphosate and its metabolite AMPA is difficult and expensive. It is not routinely included in residue analyses.

Bioconcentration factors are low in laboratory tests and there is no evidence of bioaccumulation, but esidues of the metabolite have been found in carp 90 days after application. (IPCS 1994)

Alternatives to the use of glyphosate depend entirely on the weed problem and the situation in which it occurs. Some of the ways in which weeds can be controlled include:

* Crops - mechanical methods, cover crops, appropriate timing of sowing/planting, flame weeders.

* Orchards, Plantations - green mulches, cover crops, mowing Pastures - grazing controls, manual removal, use of appropriate pasture species.

* Lawns - manual weed removal, fertility improvement, water management, aeration, mowing management, and pH control.

* Gardens - manual removal, organic mulches such as straw and bark chips; flame weeders.

* Forestry - mechanical methods.

* Roadsides - hot water vegetation control; appropriate species planting; appropriate road design to minimise invasion.

* Aquatic weed control - mechanical control: machinery, flooding/drying out.

* Pre-harvest desiccation - use of all chemicals should be completely avoided because of problems of food residues; replace by appropriate varieties and management systems.

* Growth regulator - use should be discontinued and methods of cultivation, microhabitat manipulation and different varieties considered.

LD50 = lethal dose that kills 50% of test animals.

LC50 = lethal concentration that kills 50% of test animals.

Asteraki, E., Hanks, C., Clements, R., 1992. The impact of the chemical removal of the hedge-base flora on the community structure of carabid beetles (Col., Carabidae) and spiders (Aranae) of the field and hedge bottom. J. Appl. Ent. 113:398-406.

Brust, G., 1990. Direct and indirect effects of four herbicides on the activity of carabid beetles (Coleoptera: Carabidae). Pestic. Sci. 30:309-320.

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Codex Alimentarius Commission. 1993. Pesticide residues in food. FAO, WHO, Rome.

Cox, C., 1995. Glyphosate, part 1: toxicology. J. Pestic. Reform 15(3):14-20).

Cox, C., 1995b. Glyphosate, part 2: human exposure and ecological effects. J. Pestic. Reform. 15(4):14-19.

Eberbach, P., Douglas, L., 1983. Persistence of glyphosate in a sandy loam, Soil Biol. Biochem. 15(4):485-487.

Eberbach, P., Douglas, L., 1989. Herbicide effects on the growth and nodulation potential of Rhizobium trifolii with Trifolium subterraneum L. Plant and Soil 119:15-23.

Edwards, W., Triplett, G., Kramer, R., 1980. A watershed study of glyphosate transport in runoff. J. Environ. Qual. 9(4):661-665.

Eijsackers. H., 1985. Effects of glyphosate on the soil fauna. In Grossbard E., Atkinson, D. (eds), The Herbicide Glyphosate, Butterworths, London.

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Grossbard, E., 1985. Effects of glyphosate on the microflora: with reference to the decomposition of treated vegetation and interaction with some plant pathogens. In Grossbard, E., Atkinson, D. (eds), The Herbicide Glyphosate, Butterworths, London.

Hassan, S., 1988. Results of the fourth joint pesticide testing programme carried out by the IOBC/WPRS Working group "Pesticides and beneficial organisms". J. Appl. Ent. 105:321-329.

Holtby, B., Baillie, S., 1989. Effects of the herbicide Roundup on Coho salmon fingerlings in an over-sprayed tributary of Carnation Creek, British Columbia. In Reynolds, P., (ed), Proceedings of the Carnation Creek Herbicide Workshop, Nanaimo, B.C., Forest Pest Management Institute, Forestry Canada.

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Jayabalan, Dr. 1995. Personal communication, PAN Asia Pacific.

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Maartensson, A., 1992. Effects of agrochemicals and heavy metals on fast-growing Rhizobia and their symbiosis with small-seeded legumes. Soil Biol. Biochem. 24(5):435-445.

Mekwatanakarn, P., Sivassithamparam, K., 1987. Effect of certain herbicides on soil microbial populations and their influence on saprophytic growth in soil and pathenogenicity of take-all fungus. Biol. Fertil. Soils 5:175-180.

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Roy, D., Konar, S., Banerjee, S., Charles, D., Thompson, D., Prasad, R., 1989. Uptake and persistence of the herbicide glyphosate (Vision) in fruit of wild blueberry and red raspberry. Can. J. Forest. Res. 19.

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Smiley, R., Ogg, A., Cook, R., 1992. Influence of glyphosate on Rhizoctonia root rot, growth, and yield of barley. Plant Dis. 76(9):937-942.

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Willocks, M., 1995. Letter to Meriel Watts, November 14, 1995, Christchurch.

Prepared by:
Meriel Watts and Ronald Macfarlane,
Pesticide Action Network - Asia and the Pacific.

PAN AP, P.O. Box 1170, 10850 Penang, Malaysia.
Tel: (60-4) 657 0271, 656 0381 Fax: (60-4) 657 7445
E-mail: panap@panap.po.my