Glyphosate is Not Safe, Reveals New Review by Experts


Dear Friends and Colleagues

Glyphosate is Not Safe, Reveals New Review by Experts

Pesticide Action Network (PAN) International has released a monograph presenting a large body of research documenting the adverse human health and environmental impacts of glyphosate and glyphosate-based herbicides. 

Commonly known as Roundup, glyphosate is sprayed on numerous crops and plantations, including about 80% of genetically modified (GM) crops (canola, corn, cotton, soybean, sugar beet). It is also widely used in home gardens and public places, including roadsides, and semi-natural and natural habitats. Human exposure is widespread. Because it is a systemic herbicide, it cannot be completely removed from food by washing, peeling or processing.

Aggressive marketing by its developer, Monsanto, has resulted in the widespread belief that glyphosate is ‘safe’. The monograph, written by six experts, dispels this myth. It cites the 2009 case of the Supreme Court of France, which upheld judgements by two previous courts that the claims of safety were false, and the WHO International Agency for Research on Cancer (IARC), which classified glyphosate as a probable human carcinogen in 2015. Adverse human impacts detailed in the review include acute poisoning, kidney and liver damage, imbalances in the intestinal microbiome and intestinal functioning, cancer, genotoxicity, endocrine disruption, reproductive and developmental reduction, neurological damage, and immune system dysfunction.

Glyphosate is also reported to have adverse effects on ecosystem functioning, pollination services, biological controls, soil fertility and crop health. Itis a widespread environmental contaminant found in soils and sediments, surface water bodies, groundwater and the marine environment. Resistance to glyphosate is now recorded in 35 weed species and in 27 countries, mostly caused by the repeated use of glyphosate in GM crop cultivation, no-till agriculture, and amenity use.

Glyphosate is included in PAN International’s "List of Highly Hazardous Pesticides" targeted for global phase-out. The global network is calling for the herbicide to be replaced by agro-ecological approaches to weed management in diversified cropping systems and non-crop situations, some of which are discussed in the monograph.

With best wishes

Third World Network
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by Drs. Meriel Watts, Peter Clausing, Angeliki Lyssimachou, Gesine Schutte, Rina Guadagnini and Emily Marquez
PAN International



Glyphosate, commonly known by its original trade name RoundupTM (manufactured by Monsanto), is the world’s most widely used herbicide. Glyphosate-based herbicides are manufactured by many companies in many countries.

The herbicidal action of glyphosate is primarily due to its capacity to block the production of essential amino acids in plants and some mircoorganisms through a pathway called “shikimate”, which is present only in plants. Thus, it was sold as safe for animals and humans.

Glyphosate is sprayed on numerous crops and plantations, including about 80% of genetically modified (GM) crops (canola, corn, cotton, soybean, sugar beet); with relatively high levels permitted as residues in food and animal feed. It is used as a pre-harvest desiccant, and because it is a systemic herbicide it cannot be completely be removed from food by washing, peeling or processing. It is widely used in home gardens and public places, including roadsides, and semi-natural and natural habitats. Human exposure is widespread and constantly recurring. Residues are widespread in foods, particularly those containing cereals (from pre-harvest use) or GM corn or soy-derived products. It has been detected in drinking water, wine and beer, and even in non-food products derived from GM cotton. The extent of human exposure is reflected in the widespread presence of glyphosate in human urine wherever it has been tested, principally in Europe. It has also been found in urine and breast milk in the USA.

Very aggressive public relations and marketing by its developer, Monsanto, has resulted in the widespread belief that glyphosate is ‘safe’. For example, Monsanto claimed that glyphosate is ‘biodegradable’ and that it ‘left the soil clean’. However, in 2009, France’s Supreme Court upheld judgements by two previous courts that these claims were false (Anon 2009). Registration processes continue to allow the use of the herbicide without raising concerns about safety even as new data identifying adverse effects emerges.

However, the 2015 classification by the International Agency for Research on Cancer (IARC) of glyphosate as a probable human carcinogen is resulting in massive widespread concern about its continued use, especially preharvest and in public places. Additionally, independent scientific studies and widespread poisonings in Latin America (resulting from aerial application) have begun to reveal numerous acute and chronic effects of glyphosate-based herbicides.

As a result, national bans and restrictions, and voluntary action by local authorities and retailers to curb use are rising dramatically. Sri Lanka was the first country to ban it completely, although that ban may be partially relaxed. The European Union has extended approval for glyphosate for only 18 months instead of the usual 15 years, has banned the use of the surfactant POEA in formulations, and proposed minimised preharvest use and use in public places. The European Food Safety Authority stated that there are so many data gaps for POEA that establishing acceptable exposure limits is impossible. Italy has also banned the preharvest use of glyphosate, its use in public places and those frequented by children and the elderly, and non-agricultural use on soils with high sand content to reduce the potential for contamination of groundwater.

Huge production capacity for glyphosate in China has resulted in the world being oversupplied with the herbicide. Total global production capacity is more than twice the global demand, putting pressure on the industry to decrease prices and disperse GM Roundup Ready crops.

Highly Hazardous Pesticide

IARC’s classification of glyphosate as a probable human carcinogen means that it now meets the criteria for a Highly Hazardous Pesticide as defined by PAN (PAN International 2016b) and by FAO/WHO Joint Meeting on Pesticide Management as implemented by FAO in Mozambique (Come et al 2013).


Glyphosate herbicides have been frequently used in self-poisonings and many deaths have occurred, especially in Asia, from as little as 3/4 of a cup of formulated product.

There have also been many cases of unintentional poisonings amongst users and bystanders, the former often experiencing severe chemical burns and respiratory problems.

Widespread poisonings have occurred in Latin America as a result of aerial spraying of GM soybean crops, and of coca crops in Colombia— effects being recorded as far as 10 km away from the supposed spray zone. The coca spraying (instigated by a US government-funded programme to eliminate cocaine production in Colombia) was reported to have also resulted in widespread animal deaths.

Doctors in Argentina report vomiting, diarrhoea, respiratory problems and skin rashes in association with aerial spraying of glyphosate on GM crops. Other acute symptoms of poisoning commonly reported from unintentional exposure include abdominal pain, gastrointestinal infections, itchy or burning skin, skin infections (particularly prevalent in children), blisters, burning or weeping eyes, blurred vision, conjunctivitis, headaches, fever, rapid heartbeat, palpitations, raised blood pressure, dizziness, chest pains, numbness, insomnia, depression, debilitation, difficulty in breathing, respiratory infections, dry cough, sore throat, and unpleasant taste in the mouth. Less common effects reported include balance disorder, reduced cognitive capacity, seizures, impaired vision, smell, hearing and taste, drop in blood pressure, twitches and tics, muscle paralysis, peripheral neuropathy, loss of gross and ne motor skills, excessive sweating, and severe fatigue.

Acute toxicity

Glyphosate has a low toxicity rating (WHO Table 5) despite the substantial evidence of adverse health effects. Surfactants added to formulated glyphosate products may be more toxic: the surfactant POEA present in many formulations is about 5 times more toxic than the glyphosate itself. There are a number of other chemicals added to glyphosate formulations or contaminating them; some are known to be harmful, but many are regarded as trade secrets and it is unknown which might be contributing to the health effects.

Long-term toxicity

Glyphosate-based herbicides can interfere with numerous mammalian organs and biochemical pathways, including inhibition of numerous enzymes, metabolic disturbances and oxidative stress leading to excessive membrane lipid peroxidation, and cell and tissue damage. Genotoxicity and endocrine disruption also lead to chronic health and developmental effects.

Glyphosate has long been known to have antimicrobial properties, and was patented by Monsanto as an antimicrobial in 2010, with claims to be active against a very wide range of organisms. Recent studies show it can cause imbalances in the normal gastrointestinal microbiome, increasing vulnerability to pathogenic bacteria and influencing the response to antibiotics and intestinal functioning, in humans and animals.

Scientists have also found harmful effects on human cells at levels of glyphosate too low to have a herbicidal effect, some at levels similar to those found in food. These effects are amplified by the adjuvants in the Roundup formulation, which assist penetration of the cells by glyphosate. Several researchers have reported that glyphosate appears to accumulate in human cells.

Glyphosate at low concentrations damages liver, kidney and skin cells; in the latter, it causes aging and potentially cancer. Its ability to penetrate skin increases 5-fold when skin is damaged.

Doctors in Argentina have reported a dramatic upsurge in long-term effects in areas where genetically modified soy crops are aerial- sprayed with glyphosate. They include cancer, infertility, pregnancy problems, birth defects, and respiratory diseases.


Kidney and liver are the main target organs for glyphosate, and a wide range of adverse effects are reported from laboratory studies, including cell damage and death, DNA damage and tumours. Glyphosate is implicated in an epidemic of ‘chronic kidney disease of unknown cause’ (CKDu) amongst farmers in Sri Lanka, Andhra Pradesh (India), and Central America, in part because of the herbicide’s ability to chelate nephrotoxic metals.

Cancer, genotoxicity

The IARC monograph on glyphosate, published in 2015, concludes that “there is limited evidence in humans for carcinogenicity of glyphosate” and “there is sufficient evidence in experimental animals for the carcinogenicity of glyphosate”. Besides evidence from carcinogenicity studies in rats and mice, the IARC considered as a rationale “two key characteristics of known human carcinogens” and concluded that there is strong evidence that exposure to glyphosate or glyphosate-based formulations is genotoxic and can induce oxidative stress. The latter mechanism was also ascribed to aminomethylphosphonic acid (AMPA), the major metabolite of glyphosate. As a result the IARC classified glyphosate as probably carcinogenic to humans (Group 2A).

In the same year, the European Food Safety Authority (EFSA) insisted on its evaluation that glyphosate is neither carcinogenic nor genotoxic, thereby joining similar assessments made earlier by the International Programme on Chemical Safety (IPCS) and the United States Environmental Protection Agency (US EPA). This occurs in spite of substantial laboratory and some epidemiological evidence that continues to accumulate and points to the opposite conclusion.

The evaluation of glyphosate by the European Chemicals Agency (ECHA) is still ongoing. Final results are expected by end of 2017 when the extension of the current approval for glyphosate in the European union also expires.

Studies have demonstrated that glyphosate and/ or Roundup cause genetic damage in human lymphocytes and liver cells; bovine lymphocytes; mouse bone marrow, liver, and kidney cells; fish gill cells and erythrocytes; caiman erythrocytes; tadpoles; sea urchin embryos; fruit flies; root-tip cells of onions; and in Salmonella bacteria. Other studies have shown that it causes oxidative stress, cell-cycle dysfunction, and disruption to RNA transcription, all of which can contribute to carcinogenicity.

Several epidemiological studies have linked exposure to glyphosate with non-Hodgkin’s lymphoma, hairy cell leukaemia, multiple myeloma, and DNA damage.

Glyphosate and Roundup caused DNA damage in human buccal cells, and was clastogenic in mouse bone marrow cells, adding to a number of previous studies showing it to be genotoxic.

Endocrine disruption

A number of studies have demonstrated that both glyphosate and the Roundup formulation disrupt oestrogen, androgen, and other steroidogenic pathways, and cause the growth of human breast cancer cells.

One study summarises these effects occurring at doses substantially lower than those used in agriculture, or permitted as residues: at 0.5 mg/kg (40 times lower than levels permitted in soybeans in the US) they were anti-androgenic; at 2 mg/kg they were anti-oestrogenic; at 1 mg/ kg they disrupted the enzyme aromatase; at 5 mg/kg they damaged DNA, and at 10 mg/ kg they were cytotoxic. These effects can result in adverse effects in sexual and other cell differentiation, bone metabolism, liver metabolism, reproduction, development and behaviour, and hormone-dependent diseases such as breast and prostate cancer (Gasnier et al 2009).

In vivo experiments in rats show that low levels of glyphosate-based herbicides disrupt the production of testosterone, oestradiol and other steroid hormones, down-regulate the expression of oestrogen progesterone receptors, induce the aromatase activity and protein levels in the testis and cause abnormal sperm morphology.

The implications of the endocrine-disrupting effects can be profound and far-reaching, involving a range of developmental impacts including sexual and other cell differentiation, bone metabolism, liver metabolism, lipid metabolism, reproduction, pregnancy, growth, brain and organ development, cognition, behaviour, and endocrine-related diseases such as breast, testicular and prostate cancer, neurodegenerative and metabolic disorders (diabetes, obesity).

Reproductive and developmental

Exposure to glyphosate-based herbicides, even at very low doses, may result in reproductive problems including miscarriages, pre-term deliveries, low birth weights, and birth defects. Laboratory studies have shown that very low levels of glyphosate, Roundup, POEA, and the metabolite AMPA all kill human umbilical, embryonic and placental cells. Roundup can kill testicular cells, reduce sperm numbers, increase abnormal sperm, retard skeletal development, and cause deformities in amphibian embryos.

Monsanto has known since the 1980s, and the German government since 1998, that glyphosate causes birth defects. After analysing the industry data reported in the German authorities 1998 draft assessment report, independent scientists concluded: “a substantial body of evidence demonstrates that glyphosate and Roundup cause teratogenic effects and other toxic effects on reproduction”, including heart, kidney, skeletal, lung and cranial problems (Antoniou et al 2012).

More recent studies show malformation in the heads of frogs that are similar to birth defects amongst people exposed to aerial spraying of Roundup over GM soy crops in Latin America.


Glyphosate is assumed by regulators to have no neurological effects—the US EPA did not require neurotoxicity studies to be carried out for the registration of Roundup. However, a number of studies have shown that glyphosate can adversely affect nerve cells and affect neuronal development. There is emerging evidence that glyphosate can affect areas of the brain associated with Parkinson’s disease, particularly the dopaminergic neurons. Epidemiological and case studies link glyphosate exposure with parkinsonian, Attention-Deficit/ Hyperactivity Disorder (ADHD) and autism.


Several studies indicate that glyphosate formulations may interfere with the immune system resulting in adverse respiratory effects including asthma, rheumatoid arthritis, and autoimmune skin and mucous membrane effects.

Environmental effects

Glyphosate has direct eco-toxicological effects and indirect effects. The later result from the unprecedented elimination of flora termed weeds. Direct and indirect effects have cascading impacts on the food chain and on biodiversity. Ecosystem functions of insects, such as natural pest control and pollination services, are jeopardised by the almost complete elimination of weeds because these plants are essential to most beneficial species. This may lead to huge difficulties in returning to ecologically sound agricultural systems. In aquatic ecosystems, the direct eco-toxicological effects of glyphosate of greatest concern are those that occur at a subtle level, which can result in significant disruption of the ecosystem.

Aquatic effects

Glyphosate is water soluble, and is increasingly found in the environment at levels that have caused significant effects on species that underpin the entire aquatic food chain. Glyphosate and/or Roundup can alter the composition of natural aquatic communities, potentially tipping the ecological balance and giving rise to harmful algal blooms. It can have profound impacts on microorganisms, plankton, algae and amphibia at low concentrations: one study showed a 70% reduction in tadpole species and a 40% increase in algae. Insects, crustaceans, molluscs, reptiles, and fish can also be affected, with vulnerability within each group varying dramatically between species. Effects include reproductive abnormalities, developmental abnormalities and malformations, DNA damage, immune effects, oxidative stress, modified enzyme activity, decreased capacity to cope with stress and maintain homeostasis, altered behaviour, and impaired olfaction that can threaten their survival. Amphibians are particularly vulnerable. Roundup is generally more toxic than glyphosate, especially to fish.

Terrestrial effects

Soil & plant health

As with the aquatic environment, it is the subtle effects causing disruption of the ecosystem that are of greatest concern, particularly effects on the agroecosystem. Glyphosate is toxic to some but not all soil microorganisms, altering microbial community dynamics in ways that are harmful to plants and to ecological balance. It increases microorganisms capable of metabolising the chemical. It can reduce some beneficial organisms such as saprophytic fungi that decompose dead plant material and are important for soil fertility. Numerous studies have shown that glyphosate stimulates the growth of a number of fungal pathogens that cause diseases in many crops. The upsurge in use of glyphosate in no-till agriculture has brought about a resurgence of some diseases. Glyphosate binds micronutrients in the soil and causes micronutrient deficiencies in plants that increase their susceptibility to disease, decrease their vigour, and produce micronutrient-deficient food crops. It can reduce the plant’s production of lignin and phenolic compounds, which are also important for disease resistance. It can reduce nitrogen fixation in legumes such as soybean.

Glyphosate can cause metabolic and compositional changes, including altering the nutritional composition of foods, for example the protein and fatty acid content of soybeans. It can cause iron deficiency in soybeans, which is a concern for human health as human iron deficiency is widespread.

Earthworms and beneficial insects

Glyphosate has adverse effects on some earthworms; and a number of beneficial insects useful in biological control, particularly predatory mites, carabid beetles, ladybugs, and green lacewings. It can also adversely affect other insects that play an important part in ecological balance such as springtails, wood louse, and field spiders. Glyphosate, at levels commonly found in agricultural settings, impairs honeybees’ cognitive capacities affecting their navigation with potential long-term negative consequences for colony foraging success

Birds and other animals

Glyphosate use may result in significant population losses of a number of terrestrial species through habitat and food supply destruction. There have been reports of numerous deaths of livestock and domestic animals as a result of the aerial spraying of glyphosate in Colombia.

Environmental fate

Glyphosate is a widespread environmental contaminant found in soils and sediments, a wide range of surface water bodies, groundwater and the marine environment.


The European Food Safety Authority (EFSA) describes glyphosate persistence in soil as being low to very high, and that of AMPA as being moderate to very high, with a half-life varying from less than a week to more than a year and a half, depending on the extent of soil binding and microbial breakdown (glyphosate is broken down by microbial degradation). Residues have been found up to 3 years after application in cold climates. It is less persistent in warmer climates, with a half-life between 4 and 180 days. It is bound onto soil particles, and this was once thought to mean that glyphosate is not biologically active within soil, nor will it leach to groundwater. However, it is now known that it can easily become unbound again, be taken up by plants or leach out, indicating a greater risk of groundwater contamination.

Phosphate fertilisers reduce binding of glyphosate to soil particles, and so increase the amount of unbound glyphosate remaining in the soil, which is available for root uptake, microbial metabolism, and leaching into groundwater. The risk of leaching is greater in fertilised soils. Conversely, the presence of glyphosate in some soils can reduce retention and availability of phosphate reducing soil fertility.


Glyphosate is soluble in water, and slowly dissipates from water into sediment or suspended particles. Although it does break down by photolysis and microbial degradation, it can be persistent for some time in the aquatic environment, with a half-life of up to nearly 5 months, and still be present in the sediment of a pond after 1 year.

Residues of glyphosate have been found in a wide range of ditches, drains, streams, rivers, ponds, lakes and wetlands in many countries including Argentina, Canada, China, throughout Europe, Norway, USA, and the UK; in wastewater in France and Canada, land ll leachate in the UK. Urban use on road and rail sides is contributing significantly to this contamination, with residues being found in sewage sludge and wastewater treatment plants. Contamination of ‘vernal pools’—pools that are shallow and disappear in dry weather—are a concern for amphibia, for which these water sources are critical.

Residues have also been found in groundwater in Canada, Austria, Belgium, Denmark, Germany, Ireland, Spain, Sweden, Switzerland, Netherlands, UK, Sri Lanka, and USA. They have been detected in the marine environment off the Atlantic Coast of France; and in marine sediment in New Zealand, believed to have come largely from the spraying of urban roadside vegetation.


EFSA gives a bioconcentration factor (BCF) of 1.2 (+ 0.61). However, bioaccumulation of glyphosate may be greater than predicted). The BCF for glyphosate is increased in the presence of POEA in the aquatic environment. This may be because POEA, which is known to enhance glyphosate transport into plant cells, also facilitates increased permeability in animal cells. A BCF for glyphosate varying between 1.4 and 5.9 was found in freshwater blackworm. Bioaccumulation has also been demonstrated in land snails, fish, aquatic plants. There are also suggestions of bioaccumulation in some human cell studies.

Atmospheric transport and deposition

Glyphosate is of low volatility, and residues in the air have been found in particulate matter, suggesting that airborne transport is via particles with deposition being largely in dust rather than vapour. It has been found in the rain in Belgium, Canada, France, and USA.


Weed resistance to glyphosate was first recorded in 1996, in Australia; it is now recorded in 35 species of weeds and in 27 countries, most notably the USA.

Most of this resistance has been caused by the repeated use of glyphosate in GM crops, no-till agriculture, and amenity use. Some has resulted from a gradual evolution of exposed weed species, and some from gene flow from GM crops to weed relatives. The latter has been observed with sugar beet in France, canola in Canada, creeping bentgrass in USA, and also with corn and soybean. Now even Monsanto is recommending the use of other herbicides in addition to glyphosate in Roundup Ready crops (crops genetically modified to be tolerant of Roundup), to slow the onset of resistance in weeds.

So widespread is the resistance now that Dow has developed a GM corn resistant to both 2, 4-D and glyphosate, and Monsanto to develop a soybean resistant to both dicamba and glyphosate.

Climate Change effects

A number of glyphosate’s adverse effects can be expected to increase with climate change: higher temperatures enhance glyphosate’s reduction of chlorophyll and carotenoids in freshwater green algae, increase toxicity to fish, and increase susceptibility to Fusarium head scab in cereals.

One study has shown that increased levels of carbon dioxide can result in increased tolerance of some grasses to glyphosate, indicating that as climate change progresses, grasses may become less susceptible to the herbicide.


There are numerous design, mechanical and cultivational practices, as well as some non- chemical herbicides based on plant extracts that can be used instead of glyphosate herbicides, depending on the weed species and the situation. Care must first be taken to determine whether the plant regarded as a weed is in fact really a problem to production, or should be regarded as a non-crop plant with beneficial uses or ecosystem services.

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