Truth: Roundup has never been tested or assessed for long-term safety for regulatory purposes but independent studies show it is highly toxic to animals and humans
Myth at a glance
Claims that Roundup is safe are misleading. Independent studies show that glyphosate, the presumed active ingredient of Roundup, is toxic. Commercial glyphosate herbicide formulations contain extra added ingredients (adjuvants) and are more toxic than glyphosate alone.
Toxic effects of glyphosate and Roundup include disruption of hormonal systems and beneficial gut bacteria, damage to DNA, developmental and reproductive toxicity, birth defects, cancer, and neurotoxicity.
Roundup and other glyphosate herbicide formulations have never been tested or assessed for long-term safety for regulatory purposes. Only glyphosate alone was tested. Even the industry tests on glyphosate alone revealed toxic effects, including malformations.
The endocrine disruptive effects of glyphosate and Roundup are most worrying, as they manifest at very low doses and can lead to ill health when exposure takes place over long periods of time.
The GMO industry claims that glyphosate is non-toxic to animals and humans because they lack the shikimate biochemical pathway present in plants. This is false, as glyphosate also affects other pathways that are present in animals and humans.
Claims that the Roundup used on GM Roundup Ready crops replaces more toxic herbicides are misleading. The toxicity of Roundup and glyphosate has been underestimated, and the failure of Roundup Ready technology due to resistant weeds has resulted in farmers using mixtures of herbicides to control weeds. The industry has responded by developing GM crops that tolerate other, potentially even more toxic herbicides, such as 2,4-D, an ingredient of Agent Orange.
Roundup, the herbicide used on most GM crops, is often claimed to be safe by industry-linked sources.1 But these claims are based on outdated and largely unpublished studies on the isolated ingredient glyphosate, commissioned by manufacturers in support of their application for regulatory authorization.1 The regulatory tests focus only on glyphosate because it is presumed to be the “active ingredient” in Roundup.
The problem with testing glyphosate alone is that Roundup and other commercial glyphosate herbicide formulations have been found in studies to be far more toxic than the isolated supposed “active ingredient” glyphosate. This is logical, since the added ingredients in commercial herbicide formulations, called adjuvants, are included specifically to increase the toxicity of the supposed “active ingredient” to the weeds.
Even glyphosate alone has been found to be more toxic than claimed by industry and regulators, based on data from industry’s own studies.2
Roundup and other formulations as sold and used have never been tested by industry for long-term toxicity for regulatory purposes prior to being marketed. Neither have regulators required that the formulations be tested at low, realistic doses over long periods of time to see whether they are endocrine (hormone) disruptors.
It has been left to independent scientists to carry out toxicity studies on the formulations after they were released onto the market – and after millions of people have been exposed. The results are concerning. Toxic effects found in these studies include disruption of hormonal systems, damage to DNA, developmental and reproductive toxicity, malformations, cancer, and neurotoxicity.
Key studies showing toxic effects of glyphosate and Roundup
Studies in human cell lines in vitro and in animals, as well as in human epidemiological and clinical studies, have shown that Roundup and glyphosate have serious toxic effects. In many cases effects are seen at realistic exposure levels. Below are some of the findings.
Adjuvants in Roundup are toxic and increase toxicity of glyphosate
The added ingredients (adjuvants) in Roundup are themselves toxic3 and increase the toxicity of glyphosate by enabling it to penetrate plant and animal cells more easily, making it more bioavailable.4,5,6
Adjuvants are widely found in the environment, so people and animals are likely to be exposed to them. For example, the half-life of the Roundup adjuvant POEA (21–42 days) is longer than that of glyphosate alone (7–14 days) in aquatic environments.7
Roundup more toxic than glyphosate
In an in vitro study, eight out of nine major pesticides tested in vitro in their complete formulations, including Roundup, were up to 1000 times more toxic to human cells than their isolated active ingredients. This increased toxicity of the complete formulation compared with the active ingredient alone was found to be a general principle of pesticide toxicology.8
This principle has been confirmed by experiments in living mammals. An in vivo study in pigs showed that the adjuvant POEA and commercial glyphosate herbicide formulations were toxic and lethal to the pigs, whereas glyphosate alone had no such effects.9An in vivo study in rats showed that POEA and Roundup formulations containing POEA were more toxic than glyphosate alone.10
Damage to DNA
Glyphosate herbicides altered cell cycle checkpoints in sea urchin embryos by interfering with the DNA repair machinery. Cell cycle dysfunction was seen from the first cell division in the sea urchin embryos.11,12,13,14 The failure of cell cycle checkpoints is known to lead to genomic instability and cancer in humans.
Glyphosate and its main metabolite AMPA have been found to cause irreversible damage to DNA in human cells in vitro and in mice in vivo.1516 Such damage to DNA may increase the risk of cancer and birth defects. AMPA damaged DNA in human cells in vitro at doses of 2.5-7.5mM and caused breaks in chromosomes at 1.8mM.16
An in vitro study showed that irradiation corresponding to a few minutes of sun exposure greatly amplified the DNA-damaging effects of glyphosate on mammalian cells. The glyphosate metabolite AMPA proved even more damaging, provoking cellular toxic effects from 0.5 ppb, a low environmentally relevant dose that can be found in European rivers and even in drinking water. The effects were even greater when glyphosate was mixed with other pesticides (the so-called “cocktail effect”), including atrazine. The authors concluded that “the Directive Standards for Pesticides in Drinking Water should be re-evaluated according to these underestimated factors of risk”.17
Glyphosate and Roundup caused DNA damage in human mouth cells in vitro after a single 20-minute exposure at much lower doses than those used in agriculture. Roundup was much more toxic than glyphosate alone. The study showed that in principle, people who are exposed to Roundup through inhalation (as in South American soy-producing countries) could suffer DNA damage. With both glyphosate and Roundup, DNA damage occurred at concentrations below those required to cause cell damage, suggesting that the DNA damage was caused directly by these substances instead of being an indirect result of cell toxicity.18
Glyphosate and Roundup caused damage to DNA and chromosomes in the bone marrow of mice in vivo and in human cells in vitro. Roundup was only slightly more toxic than glyphosate.19
Roundup caused mutations in the DNA of fruit flies.20 Roundup increased the frequency of DNA adducts (cancer-causing chemicals that link to DNA), which can mark the onset of cancer, in the liver and kidneys of mice.21
Genetic damage was found in soybean workers exposed to pesticides, glyphosate herbicides among them, in Brazil.22
Ecuadorian people exposed to aerial glyphosate herbicide spraying showed a higher degree of DNA damage in blood cells than a control population. The researchers ruled out tobacco, alcohol, non-prescription drugs and asbestos as causes. None of the individuals had used or been exposed to other herbicides or pesticides when the samples were taken. The study also found acute poisoning reactions to the glyphosate herbicide spraying, including intestinal pain and vomiting, diarrhoea, fever, heart palpitations, headaches, dizziness, numbness, insomnia, burning eyes, blurred vision, difficulty in breathing, and skin rash.23
Endocrine (hormone) disruption
Laboratory studies on animals and in vitro experiments on human cells indicate that glyphosate herbicides and glyphosate alone are endocrine disruptive chemicals (EDCs). Endocrine disruption can cause cancer, birth defects, and other reproductive and developmental problems.
The endocrine-disruptive effect of glyphosate and its commercial formulations is their most worrying toxic effect. This is because EDCs do not function like normal poisons, where a higher dose gives greater toxicity. Instead they exert their effects at very low doses and exposure over long periods of time can lead to severe ill health.24 Often, endocrine disruptive effects are seen at lower doses but not at higher doses.24,25
Study findings include the following:
- Glyphosate herbicide altered hormone levels in female catfish and decreased egg viability. The study concluded that the herbicide is harmful to catfish reproduction.26 Roundup disrupted production of the steroid hormone progesterone in mouse cells.27 Glyphosate herbicide was a potent EDC in rats, causing disturbances in reproductive development after exposure during puberty.28
- In an in vitro experiment in human cells, glyphosate herbicides prevented the action of androgens, the masculinizing hormones, at levels up to 800 times lower than glyphosate residue levels allowed in some GM crops used for animal feed in the USA. DNA damage was found in human cells treated with glyphosate herbicides at these levels. Glyphosate herbicides disrupted the action and formation of estrogens, the feminizing hormones. The first toxic effects were found at the low dose of 5 ppm and the first endocrine disruption at 0.5 ppm – 800 times less than the 400 ppm level authorized for some animal feeds.29
- Roundup herbicide at environmentally relevant exposure levels (down to 0.00023% glyphosate dilution of the commercial formulation) caused the dysregulation of large numbers of genes in human breast cancer cells grown in the laboratory in vitro. Of the 1,550 genes analyzed, expression of 680 was either increased or decreased. Roundup was able to replace and work synergistically with estrogen, which is required for growth of the breast cancer cells. This demonstrates the strong potential endocrine disruptive potential of glyphosate in this hormonal system. The authors commented, “There remains an unclear pattern of very complex events following exposure of human cells to low levels of glyphosate, but events surrounding the altered levels of expression of only three genes… out of the entire battery tested, are both complicated and potentially damaging to adult and fetal cells.”30
- Glyphosate alone increased the proliferation of estrogen-dependent breast cancer cells by estrogenic mechanisms in vitro.31
- An in vivo study of Roundup administered to rats in drinking water diluted to 50ng/L glyphosate equivalence – half of the level permitted in drinking water in the EU32 and 14,000 times lower than that permitted in drinking water in the USA33 – resulted in severe organ damage and a trend of increased incidence of mammary tumours in female animals over a 2-year period of exposure.34 This type of non-linear endocrine disruptive effect of glyphosate and Roundup is not taken into account in safety evaluations, resulting in exposures to the public that could lead to severe illness and reproductive and developmental problems.
Malformations and reproductive and developmental toxicity
A study on the reproductive effects of Roundup on male and female offspring of rats exposed during pregnancy and lactation found significant adverse effects at non-maternally toxic doses. Findings in male offspring included a decrease in sperm number and daily sperm production during adulthood, an increase in the percentage of abnormal sperms, a dose-related decrease in serum testosterone level at puberty, and sperm cell degeneration. The authors noted that Roundup had been found in other experiments to inhibit steroidogenesis (formation of steroid hormones) in vitro by disrupting the expression of a regulatory protein, but glyphosate did not, indicating that at least one other component of the formulation is required to disrupt steroidogenesis.35
A study of farming families in Ontario, Canada found a higher than normal rate of late miscarriages and premature births associated with male glyphosate herbicide exposure.36 Monsanto claimed in non-peer-reviewed articles that the association for glyphosate was weak and not statistically significant.37,38But in the study, the odds ratios (a statistical measure of a possible link) were 1.5 for an association between glyphosate herbicide exposure and miscarriage and 2.4 between glyphosate herbicide exposure and premature birth. 1.5 is near the lower limit but 2.4 is fairly strong. Both indicate an association.
Studies on glyphosate alone commissioned by industry in support of regulatory authorization showed that it caused malformations in rabbits and rats. These effects were not only found at high maternally toxic doses but also at lower doses. Statistical significance was not always achieved at lower doses, perhaps because too few animals were used. Germany, the “rapporteur” member state for glyphosate, responsible for liaising between industry and the EU authorities during the approval process, dismissed the findings, using unscientific reasoning and practices.2
Roundup and glyphosate tested alone caused malformations in chicken and frog embryos at doses far below those used in agricultural spraying. Malformations were of a similar type as those reported in human populations exposed to Roundup spraying in GM soy-producing regions of South America. Glyphosate itself was responsible for the malformations in the chicken and frog embryos, rather than the adjuvants in the commercial formulation.39
The study identified the mechanism of toxicity as interference with the retinoic acid signalling pathway. This pathway is present in higher animals and affects gene expression. When disrupted, it can result in the development of malformations.39 This finding countered claims or implications by industry authors that glyphosate is non-toxic to animals on the supposed grounds that its sole mechanism of toxicity is the shikimate biochemical pathway, which plants have but animals lack.40
Roundup was found to cause skeletal malformations in rat foetuses after the mothers were dosed during pregnancy. The authors observed that the findings were not due to poisoning of the mother (maternal toxicity) and concluded that Roundup had a direct toxic effect on the foetuses. They also noted that the Roundup formulation was more toxic than glyphosate alone.41
Glyphosate herbicide caused malformations in tadpoles, even at concentrations that caused low mortality.42
An epidemiological study carried out in California showed a modest association between Roundup exposure and anencephaly, a type of neural tube birth defect or malformation of the structures of the developing brain and spinal cord, in which part of the skull and brain are missing.43,44
The authors found that the association was present using one type of analytical model (a multiple pesticide model), but not with another (a single pesticide model). The authors did not show the data in which they applied either model. But Table 2 of their publication reveals modest associations between glyphosate and neural tube defects for both the single pesticide and multiple pesticide models – with an odds ratio (OR, a statistical measure of a possible link) of 1.5 for both. For the hierarchical model they found an OR of 1.4. Their criteria for significant effects were that the OR should be greater than or equal to 1.4 and the lower limit of the confidence interval (CI) should be greater than or equal to 0.9.44 The OR requirement is met for glyphosate and neural tube defects using both models, but both models deliver CIs that are just below the cut-off: 0.8.
These results could reasonably be interpreted as indicating a modest association between glyphosate herbicide exposure, neural tube defects, and anencephaly.
This finding is consistent with findings in frog and chicken embryos39 and rats,41 which also linked glyphosate/Roundup exposure to impaired development of the structures of the central nervous system. It is also consistent with findings of industry studies on the effects of glyphosate alone in rats, in which the observed malformations included “reduced ossification of one or more cranial centres”.45 These malformations involving the structures of the central nervous system are consistent with descriptions of retinoic acid-induced malformations in the literature.2,46
In a laboratory study, Roundup was found to promote cancerous tumour growth in the skin of mice.47 An epidemiological study of pesticide applicators in the USA found that exposure to glyphosate herbicide was associated with higher incidence of multiple myeloma, a type of blood cancer.48 Epidemiological studies conducted in Sweden found that exposure to glyphosate herbicide was linked with a higher incidence of non-Hodgkin’s lymphoma, another type of blood cancer.495051
The EU’s 2002 review of industry studies on glyphosate claimed “no evidence” of carcinogenicity (ability to cause cancer).1 But two long-term studies on rats indicating possible carcinogenic effects already existed at this time. These long-term studies on rats were conducted in 1979–1981 and 1988–1990.52 The rats received relatively low doses of glyphosate per day in the first study and higher doses in the second. The first study found an increase in tumours in the testes of rats fed glyphosate, but the same effect was not found in the second test using the higher doses. On this basis, glyphosate was excluded from the carcinogenic category of chemicals.52,41
However, this move was based on outdated and incorrect assumptions about toxicology. Cancers can be triggered by the endocrine disruptive effects of a chemical, which can occur at extremely low doses. As explained above, EDCs can have more potent endocrine disruptive effects at lower doses than higher doses. Sometimes a disruptive effect seen at the lower dose is not seen at all at a higher dose.24
Low-dose effects cannot be predicted by effects at higher doses, such as are tested in regulatory tests performed on pesticides, including glyphosate. Regulatory tests do not require low doses to be tested for possible endocrine disrupting effects.25 Therefore the findings of the long-term cancer studies on rats discussed above52 should be re-evaluated in light of up-to-date scientific knowledge.
A toxicological study on rats found that glyphosate depleted the neurotransmitters serotonin and dopamine.53 It is not clear from the published study whether the test substance was pure glyphosate or a complete commercial formulation. Glyphosate was also found to injure rat brain cells tested in vivo.54
An epidemiological study carried out in Minnesota, USA found that the children of pesticide applicators exposed to glyphosate herbicides had an increased incidence of neurobehavioral disorders, including ADHD (attention deficit hyperactivity disorder). The finding suggested that glyphosate herbicide impacts neurological development.55
A clinical case study described how a man56 who was exposed to glyphosate herbicide developed the neurological disorder Parkinson’s disease. A separate case study involving a woman57 found the same result, though in this case it is not clear if the exposure was to glyphosate alone or a complete formulation, as the exposure took place in a factory that manufactured herbicides.57
An in vitro study suggested a mechanism through which glyphosate could cause Parkinson’s disease: glyphosate alone was found to induce programmed cell death and degradation leading to death in PC12 cells – human cells that serve as an experimental model for nerve cells.58
Negative effects on gut bacteria
An in vitro study carried out to investigate the rise in botulism disease in cattle in the past 10–15 years found that glyphosate and Roundup were toxic to beneficial gut bacteria that inhibit the growth of the botulism-causing bacterium Clostridium botulinum, but non-toxic to the botulism-causing bacteria themselves. In short, glyphosate and Roundup favoured the growth of botulism-causing Clostridium botulinum bacteria. The authors concluded that ingestion of Roundup residues in cattle feed could predispose cattle to falling ill with botulism.59
In a separate in vitro study on strains of bacteria found in the gut of poultry, most of the pathogenic bacteria tested were highly resistant to Roundup, but most of the beneficial gut bacteria tested were found to be moderately to highly susceptible. The researchers documented the antibiotic damage done to beneficial bacteria in the gut by very low concentrations of Roundup, which allowed the overgrowth of serious pathogens such as Clostridium botulinum, Salmonella spp, and E. coli. These would otherwise be kept in check by the beneficial bacteria that were wiped out by the Roundup residues in feed.60
The authors concluded that the ingestion of Roundup-contaminated feed could be a significant factor predisposing poultry to diseases caused by Clostridium botulinum. It could also explain the now widespread contamination of poultry products with pathogenic Salmonella and E. coli strains of bacteria, which can make human consumers ill.60
Metal chelating effect
Glyphosate chelates (binds to) essential nutrient metals, including manganese, magnesium, iron, zinc, and calcium, making them unavailable to plants sprayed with the herbicide6162 and thus to the people and animals that eat the plants. A German-Egyptian team of researchers found that all cows tested from Danish dairy farms excreted glyphosate in their urine. Unexpectedly low levels of manganese and cobalt were observed in all animals, which the authors said could be explained due to the strong metal chelating effect of glyphosate. Potential signs of liver and kidney toxicity were also found in the cows, which were consistent with the findings of rodent feeding studies with GM glyphosate-tolerant plants.63
This effect could cause human and animal deficiencies in the nutrient metals affected, indirectly impacting their health.
Reviews of health effects of Roundup spraying in South America
In South America a public health crisis has emerged around the spraying of Roundup herbicide on GM Roundup Ready soy, which is often carried out from the air. The spray drifts into people’s homes, schools, food crops, and watercourses. It has been blamed for widespread serious health problems.
A report commissioned by the provincial government of Chaco, Argentina, found that the rate of birth defects increased fourfold and rates of childhood cancers tripled in only a decade in areas where rice and GM soy crops are heavily sprayed. The report noted that problems centred on “transgenic crops, which require aerial and ground spraying with agrochemicals”; glyphosate herbicides were named as chemicals of concern.64
A review of studies on the health effects of glyphosate and Roundup, as well as other pesticides used with GMOs, in human and animal model systems concluded that the precautionary principle was not being observed with regard to the GMO herbicide-tolerant agricultural model. The authors concluded, “It will not be possible to devise a sustainable agriculture thatsatisfies social needs if man does not begin to prioritize policies that enhanceenvironmental and food security over the interests of private agrochemicalindustries and markets.”65
A non-peer-reviewed report by Argentine physicians and scientists, based on clinical data, detailed acute and chronic health effects in people associated with increased cultivation of GM soy and exposure to the spraying of glyphosate herbicides. Health effects included increased incidence of birth defects (including in young mothers), miscarriages, and cancers in children and young people as well as adults. Also noted were increased incidence of difficulty conceiving, genetic damage (which can lead to cancer and birth defects); increased cases of toxic liver disease, neurological developmental problems in children, kidney failure, respiratory problems, and allergies. DNA damage was also found in people exposed to spraying.66
The physicians commented that they had been serving the same populations for over 25 years, but the recent trends were unusual and linked to a systemic increase in the spraying of pesticides.66
Roundup link with modern diseases suggested
A review published in 2013 (Samsel and Seneff, 2013) hypothesized a mechanism by which glyphosate herbicides could be contributing to modern human diseases that are on the increase worldwide. The authors focused especially on celiac disease and gluten intolerance, but also drew potential links between glyphosate toxicity and a broader range of diseases, such as ADHD (attention deficit hyperactivity disorder), autism, Alzheimer’s disease, infertility, birth defects, and cancer.67
The review cited glyphosate’s known ability to disrupt gut bacteria and to suppress the activity of the cytochrome P450 (CYP) family of enzymes, which play an important role in detoxifying harmful chemicals. The authors concluded that glyphosate enhances the damaging effects of other foodborne chemical residues and environmental toxins.67
If this potential pathway to modern diseases is confirmed by further research, it highlights the industry’s failure to consider any mechanism of glyphosate toxicity other than the shikimate pathway, which plants have but humans and animals do not.40 In a second review, Samsel and Seneff pointed out that gut bacteria have this pathway and are susceptible to glyphosate toxicity, with the resulting disruptions in gut bacteria potentially impacting human and animal health. In addition, the authors noted glyphosate’s ability to chelate essential nutrient metals, making them unavailable to human and animal consumers, thus potentially affecting their health.68
Roundup linked to chronic kidney disease
An epidemic of chronic kidney disease in farming regions of Sri Lanka and other countries has been linked in a study to exposure to Roundup. The study’s authors propose that glyphosate becomes highly toxic to the kidney when it mixes with “hard” water or heavy metals like arsenic and cadmium, either naturally present in the soil or added in the form of fertilizers. Hard water contains metals such as calcium, magnesium, strontium and iron, along with carbonate, bicarbonate, sulphate and chlorides. Glyphosate chelates or binds to these substances and carries them to the kidneys, resulting in the destruction of tissue.69
The study prompted the Sri Lankan government to order a ban on glyphosate herbicides.70 Under pressure from the plantation sector, the ban was subsequently watered down to a restriction in areas where chronic kidney disease was most serious71 and later rescinded.
It is noteworthy that kidney problems were also observed in laboratory animals that received Roundup in water over a long-term 2-year period.34
Courts rule Roundup not safe – Brazil seeks to ban it
Claims that Roundup and glyphosate are safe for human health and the environment have been overturned in courts in the US72 and France. The French court forced Monsanto to withdraw advertising claims that Roundup is biodegradable and leaves the soil clean after use.73
In 2014 in Brazil, the Federal Public Prosecutor requested the Justice Department to suspend the use of glyphosate herbicides, the most widely used herbicides in the country. The Prosecutor ordered the National Health Surveillance Agency (ANVISA) to re-evaluate the toxicity of glyphosate, along with eight other pesticide active ingredients suspected of causing damage to human health and the environment.74
Arguments that Roundup replaces more toxic herbicides are false
GMO proponents often argue that Roundup has replaced more toxic herbicides and that GM Roundup Ready (RR) crops therefore reduce the toxic burden on humans and the environment. But this is false. GM RR crops have not only increased the use of glyphosate herbicides but have also increased the use of other, potentially even more toxic herbicides, due to the spread of glyphosate-resistant weeds (see Myth 5.2). Farmers can no longer control weeds with glyphosate alone and add other herbicides to their spray mix.
Also, as we have seen, the presumed safety of Roundup is a marketing claim that does not reflect the scientific facts.
Health risks of other herbicides used with GM crops
As the spread of glyphosate-resistant weeds makes Roundup Ready GM crop technology obsolete, industry is developing crops that resist other herbicides, either in addition to, or instead of, glyphosate. The health risks of these other herbicides need to be considered in any evaluation of the relevant herbicide-tolerant GM crops.
For example, the GM seed and agrochemical company Dow is seeking USDA approval of GM corn and soybeans resistant to 2,4-D, an ingredient of Agent Orange. The USDA has given a positive opinion on the applications, though final approval of the 2,4-D crops is being strongly opposed by health professionals and groups such as the Center for Food Safety.75
Exposure to 2,4-D has been linked in studies to genetic damage,76,77,78 endocrine disruption,76,79,80 reduced sperm count,81 reproductive problems,82 birth defects,83 Parkinson’s disease,84 and harmful impacts on brain development.85,86
Scientists warn that widespread cultivation of 2,4-D resistant soybeans alone would trigger a substantial increase in the use of 2,4-D, damage to non-target crops through drift, and the inevitable spread of 2,4-D-resistant weeds.87
Claims of safety for Roundup are misleading. Many independent studies show that the complete formulations as sold and used are much more toxic than glyphosate alone, though even glyphosate alone has been found to be toxic.
Toxic effects of Roundup and glyphosate found in studies include disruption of hormonal systems and beneficial gut bacteria, damage to DNA, developmental and reproductive toxicity, malformations, cancer, and neurotoxicity.
Roundup and other glyphosate formulations have never been tested or assessed for long-term safety for regulatory purposes, as only the isolated supposed “active ingredient” glyphosate was tested by industry in long-term studies. In addition, the “cocktail” effect of increased toxicity created when glyphosate is mixed with other pesticides has never been tested for regulatory purposes. This is in spite of the fact that people and animals are exposed not to single chemicals but to chemical mixtures.
Industry claims that glyphosate is non-toxic to animals and humans because they lack the shikimate biochemical pathway present in plants. But this claim is false. There are other pathways through which glyphosate and its commercial formulations can have toxic effects on animals and humans. Glyphosate and Roundup have been found to interfere with the retinoic acid signalling pathway, which affects gene expression in animals and humans. When disrupted, it can result in the development of malformations. Glyphosate and Roundup negatively affect gut bacteria that are vital to the healthy functioning of the immune system. Glyphosate is a chelator of essential nutrient metals, making them unavailable to the plant and therefore to the consumer. Glyphosate and Roundup are endocrine disruptors, an effect that can lead to multiple health problems during development and adult life.
The endocrine disruptive effects are most worrying, as they manifest at very low doses and can lead to ill health when exposure takes place over long periods of time.
Even industry studies on glyphosate alone show ill effects on laboratory animals, including malformations (birth defects). These effects were dismissed by regulators using unscientific reasoning.
Claims that the Roundup used on GM Roundup Ready crops replaces even more toxic herbicides are misleading. First, the toxicity of Roundup has been underestimated. And second, the failure of Roundup Ready technology due to resistant weeds has resulted in the industry developing GM crops that tolerate other, potentially even more toxic herbicides, such as 2,4-D, an ingredient of Agent Orange.
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