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Ecotoxicological risk assessment of Roundup Herbicide

Rev Environ Contam Toxicol 167:35-120 (2000) Giesy, Dobson, Solomon

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Note: The primary article is available behind a paywall here:

This article is one of the few that attempts to compare the toxicity of the various components of Roundup. The so-called active ingredient is glyphosate. It is regarded as "active" because it is able to block a specific nutritional pathway in most plants. However, the other ingredients are far more toxic to various animals and when combined with glyphosate, the combination is far more toxic (55 times more) than glyphosate alone.

To make our point, we will choose one specific animal, Daphnia Magna, the water flea. Just because other animals are not studied does not mean they are not similarly endangered by these toxins.

One complication to this sort of analysis is the fact that the formulation of Roundup is not fully disclosed and can vary based on the exact manufacturing plant.

Take a look at the extraction below:

  • Excerpt to compare toxicity to representative animals:


The following is a summary of the relevant entries in the table above below for our discussion for Daphnia Magna, the "water flea".

Component EC50 or LC50 mg/L NOEC mg/L
Roundup 9.7 1.9
  24 7.8
  12.9 4.6
Glyphosate (acid) 780 560
Glyphosate (salt) 930 320
AMPA 690 320
POEA 2.0 0.32

  • LC50 is the lethal concentration required to kill 50% of the population.
  • EC50 is the (EC) when 50% of the population are affected (usually means they are killed or immobilized).
  • NOEC is the "No Observed Effect Concentration" when none of the population is affected.

Thus higher numbers means the component is less toxic. Lower number more toxic.

  • AMPA is a breakdown product of Glyphosate.
  • POEA is a adjuvant ingredient which helps transport glyphosate through the plant cellular structure.

To reduce these numbers for comparison:

Component Average LC50 or EC50
Roundup 15.5
Glyphosate (acid or salt) 855
AMPA 690
POEA 2.0


  • POEA is about 7.5x more toxic than Roundup
  • POEA is 427x more toxic than glyphosate.
  • Roundup is 55x more toxic than glyphosate alone.
  • AMPA (glyphosate breakdown product) is a little more toxic than Glyphosate.

Thus, any testing that we see that tests only glyphosate toxicity is missing the larger picture. If you wanted to test a component of Roundup and get results showing it has low toxicity, you would choose glyphosate.

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This abstract is from the paysite. Interesting that the abstract makes it sound that there is no concern while reviewing the entire article leaves one with almost no comfort.
Glyphosate-based weed control products are among the most widely used broad-spectrum herbicides in the world. The herbicidal properties of glyphosate were discovered in 1970, and commercial formulations for nonselective weed control were first introduced in 1974 (Franz et al. 1997). Formulations of glyphosate, including Roundup® Herbicide (RU)1 (Monsanto Company, St. Louis, MO), have been extensively investigated for their potential to produce adverse effects in nontarget organisms. Governmental regulatory agencies, international organizations, and others have reviewed and assessed the available scientific data for glyphosate formulations and independently judged their safety. Conclusions from three major organizations are publicly available and indicate RU can be used with minimal risk to the environment (Agriculture Canada 1991; USEPA 1993a; WHO 1994). Several review publications are available on the fate and effects of RU or glyphosate in the environment (Carlisle and Trevors 1988;Smith and Oehme 1992 ; Malik et al. 1989;Rueppel et al. 1977; Sullivan and Sullivan 1997;Forestry Canada, 1989). In addition, several books have been published about the environmental and human health considerations of glyphosate and its formulations (Grossbard and Atkinson 1985; Franz et al. 1997). In addition, RU and other glyphosate formulations have been selected for use in a number of weed control programs for state and local jurisdictions in the United States. Many of these uses require that ecological risk assessments be conducted in the form of Environmental Impact Statements or Environmental Assessments. These documents are comprehensive and specific to local use situations. Documents are available for risk assessments in Texas, Washington, Oregon, Pennsylvania, New York, Virginia, and other states (USDA 1989;USDA 1992;USDA 1996;USDA 1997;USDI 1989; Washington State DOT 1993).

Supporting Research

Research was conducted into the toxicity of Roundup and Glyphosate. These studies are oriented to determine how much of the chemical an organism can encounter in a one-time encounter and not die or suffer ill effects. It does not intended to determine if long-term exposure will result in any health effects.

Glyphosate is used extensively as a non-selective herbicide by both professional applicators and consumers and its use is likely to increase further as it is one of the first herbicides against which crops have been genetically modified to increase their tolerance. Commercial glyphosate-based formulations most commonly range from concentrates containing 41% or more glyphosate to 1% glyphosate formulations marketed for domestic use. They generally consist of an aqueous mixture of the isopropylamine (IPA) salt of glyphosate, a surfactant, and various minor components including anti-foaming and colour agents, biocides and inorganic ions to produce pH adjustment. The mechanisms of toxicity of glyphosate formulations are complicated. Not only is glyphosate used as five different salts but commercial formulations of it contain surfactants, which vary in nature and concentration. As a result, human poisoning with this herbicide is not with the active ingredient alone but with complex and variable mixtures. Therefore, It is difficult to separate the toxicity of glyphosate from that of the formulation as a whole or to determine the contribution of surfactants to overall toxicity. Experimental studies suggest that the toxicity of the surfactant, polyoxyethyleneamine (POEA), is greater than the toxicity of glyphosate alone and commercial formulations alone. There is insufficient evidence to conclude that glyphosate preparations containing POEA are more toxic than those containing alternative surfactants. Although surfactants probably contribute to the acute toxicity of glyphosate formulations, the weight of evidence is against surfactants potentiating the toxicity of glyphosate. Accidental ingestion of glyphosate formulations is generally associated with only mild, transient, gastrointestinal features. Most reported cases have followed the deliberate ingestion of the concentrated formulation of Roundup (The use of trade names is for product identification purposes only and does not imply endorsement.) (41% glyphosate as the IPA salt and 15% POEA). There is a reasonable correlation between the amount ingested and the likelihood of serious systemic sequelae or death. Advancing age is also associated with a less favourable prognosis. Ingestion of >85 mL of the concentrated formulation is likely to cause significant toxicity in adults. Gastrointestinal corrosive effects, with mouth, throat and epigastric pain and dysphagia are common. Renal and hepatic impairment are also frequent and usually reflect reduced organ perfusion. Respiratory distress, impaired consciousness, pulmonary oedema, infiltration on chest x-ray, shock, arrythmias, renal failure requiring haemodialysis, metabolic acidosis and hyperkalaemia may supervene in severe cases. Bradycardia and ventricular arrhythmias are often present pre-terminally. Dermal exposure to ready-to-use glyphosate formulations can cause irritation and photo-contact dermatitis has been reported occasionally; these effects are probably due to the preservative Proxel (benzisothiazolin-3-one). Severe skin burns are very rare. Inhalation is a minor route of exposure but spray mist may cause oral or nasal discomfort, an unpleasant taste in the mouth, tingling and throat irritation. Eye exposure may lead to mild conjunctivitis, and superficial corneal injury is possible if irrigation is delayed or inadequate. Management is symptomatic and supportive, and skin decontamination with soap and water after removal of contaminated clothing should be undertaken in cases of dermal exposure.

A typical reply

To this research, a common reply is to provide the rebuttal by Monsanto:

Their rebuttal uses a typical Monsanto sleight of hand... by talking about Glyphosate instead of Roundup. The whole point of this research was to point out that Roundup and the adjuvant ingredients are far more toxic than glyphosate alone. To study the toxicity of glyphosate is a sneaky way for Monsanto to make their product look safer than it is. How pathetic.


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Title Ecotoxicological risk assessment of Roundup Herbicide
Publisher Rev Environ Contam Toxicol 167:35-120
Author Giesy, Dobson, Solomon
Pub Date 2000
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Keywords Gmo Open Forum, March Against Monsanto
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Acute-Toxicity-Of-Roundup-Glyphosate-AMPA-POEA-to-Aquatic-Invertebrates.JPGJPG Acute-Toxicity-Of-Roundup-Glyphosate-AMPA-POEA-to-Aquatic-Invertebrates.JPG manage 77.3 K 2015-12-02 - 10:46 Raymond Lutz Excerpt to compare toxicity to representative animals
Ecotoxicological_Risk_Assessment_for_Roundup_(2000)_JA-228.pdfpdf Ecotoxicological_Risk_Assessment_for_Roundup_(2000)_JA-228.pdf manage 6086.1 K 2015-12-02 - 10:43 Raymond Lutz Toxicological Risk Assessment for Roundup Herbicide
Ecotoxicological_Risk_Assessment_for_Roundup_JA-228.pdfpdf Ecotoxicological_Risk_Assessment_for_Roundup_JA-228.pdf manage 6086.1 K 2016-04-25 - 14:47 Raymond Lutz Toxicological Risk Assessment for Roundup Herbicide
Topic revision: r6 - 2016-05-16, UnknownUser

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