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Information on Glyphosate/Roundup

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Glyphosate / RoundUp

New data from the scientific literature provides troubling concerns about the consequences of the use of glyphosate, the active ingredient in RoundUp. The use of glyphosate is toxic to the rhizosphere, woodland plants, amphibians, fish, aquatic environments and mammals.

1. The Rhizosphere: The soil that surrounds the roots of a plant, known as the rhizosphere, can become contaminated when glyphosate is applied to the leaves, passes through the plant to the roots, and then into the soil.

There is a common understanding that the widely used herbicide, glyphosate is easily degraded and adsorbed in soils and thus, harmless for use in agriculture. We can demonstrate, however, that this conclusion is wrong and dangerous for farmers because in former risk assessments the behavior of glyphosate in the rhizosphere was not properly considered. In… experiments we can show that foliar applied glyphosate to target plants is released in the rhizosphere after a fast translocation from shoots to roots. In the rhizosphere glyphosate can ….achieve negative results on non-target plants. Such a negative side effect is for example, inhibited acquisition of micronutrients such as Mn, Zn, Fe and B, which are involved in plant disease resistance mechanisms. … We predict an increase in disease problems, particularly on soils with low micronutrient availability as already reported in the USA. In view of plant and soil health, we urgently call for a re-assessment of glyphosate “ (Neumann, 2006)

2. Woodland Plants: Woodland under-story communities have considerable conservation significance providing food and shelter to wildlife.

Drift from ground crop sprayers can be found from 30-45 feet from the target plant. Plant sensitivity to glyphosate varies and cannot be predicted but needs to be tested. In woodland margins alongside intensively farmed fields, there was found to be lower plant diversity and a higher proportion of short-lived weedy species. (Gove et al, 2007)

3. Amphibians: Frogs and other amphibians are negatively impacted by pesticide run-off.

Experimental results suggest that low and realistic concentrations of RoundUp can have an impact on tadpoles’ performance and success, jeopardizing their survival and/or population establishment. In investigating heart function in bullfrog tadpoles, it was reported, ”the present results demonstrated that the exposure of bullfrog tadpoles to 1ppm of RoundUp for 48 h has a high potential to induce oxidative stress and affects cardiac function.” (Costa et al, 2008)

Professor Rick Relyea of the University of Pittsburgh found that at the manufacturer recommended doses, RoundUp completely eliminated Leopard frog and Gray frog tadpoles and nearly eliminated Wood frog and toad tadpoles. For another frog species, R. cascadae, exposure to RoundUp resulted in significant effect on survival, rate of metamorphosis, and weight. (Cauble, et al, 2005)

4. Fish: Fish can be exposed to herbicides through run-off and when aquatic plants are sprayed directly.

At 20 and 40 days following exposure to glyphosate fish were found to have increased cortisol a stress related response. A lower number of fry were obtained from the herbicide exposed fish. (Soso, et al, 2007)

Acetylcholinesterase levels decreased in the brains of fish exposed to glyphosate concentrations but not in the muscles. The results indicate that AchE activity as well as metabolic and hematological parameters may be good early indicators of herbicide contamination. (Glusczak, et al, 2006) Inhibition of Acetylcholinesterase is a neurotoxic effect associated with organophosphate chemicals. Glyphosate has an organophosphate structure but has always been considered not to be neurotoxic.

5. Aquatic environment:

Several studies have demonstrated that glyphosate alone or in combination with the additives used in commercial formulations may be damaging to aquatic biota. (Perez, et al, 2007)


6. Mammals: Carcinogenicity

Glyphosate was originally classified by EPA as a “C” carcinogen, indicating a possible human carcinogen. This designation was based on kidney tumors occurring in exposed mice. Later the designation was changed to a “D” based on uncertainty, conclusions of FIFFRA – SAP Meeting, 1986. Some authors have reported an association between multiple myeloma (DeRoos, 2005) and non-Hodgkin’s Lymphoma and glyphosate products. (Hardell, 1999)

In a cell culture system using sea urchin embryos, a recognized model for cell cycle studies, there was an indication that various glyphosate containing products induced cell cycle dysfunction/disregulation. Cell cycle disregulation is a hallmark of tumor cells and human cancer. (Marc, et al, 2004)

Mammals: Reproduction

RoundUp was found to induce adverse reproductive effects in male rodent offspring when the mother was exposed to it during pregnancy and lactation. The effects were present in the male rats during puberty and adulthood and included decreased sperm numbers, increased numbers of abnormal sperm and decreased serum testosterone. (Dallegrave, et al, 2007)


A 2001 research report indicated that preconception exposure to glyphosate had been associated with late term spontaneous abortions in humans. (Arbuckle, et al, 2001)

Reports of congenital malformations in children have been associated with parental exposure to glyphosate containing pesticides. (Garry, et al, 2002)

Mammals: Endocrine Disruption

The EPA has included glyphosate on its list of chemical pesticides to be tested for hormonal effects as part of the “Endocrine Disruptor Screening Program”. This does not necessarily mean that it will be found positive.

However, a study in rabbits reported that orally administered glyphosate had an adverse effect on sperm production. This may indicate that glyphosate is anti-androgenic or estrogenic. (Yousef, et al, 1995)

In a 2009 publication describing the effects on human cells of glyphosate-containing products such as Roundup, researchers found a wide array of toxic effects. Parameters included cytotoxicity (interference with normal cell function), genotoxicity (DNA effects), anti-estrogenic and anti-androgenic effects as well as effects on the rate of androgen to estrogen conversion. All these effects occurred at subagricultural dose levels with 24 hours of application (Gasnier).

In this study, the first endocrine disruptor (hormonal) effects were detected at levels 800 times lower than the level authorized as permissible residues in some food or feed. The authors suggested that classification of glyphosate as an endocrine disruptor must be carefully evaluated (Gasnier).


Prepared by Dr. Diana Post

And Staff of Rachel Carson Council

June 2010




Arbuckle, T; et al, “An exploratory analysis of the effect of pesticide exposure on the risk of spontaneous abortion in an Ontario farm population”, Environmental Health Perspectives, 109, 2001, 851-857

Cauble, K.; et al, “Sublethal effects of the herbicide glyphosate on amphibian metamorphosis and development”, Bulletin of Environmental Contamination and Toxicology, 75, 2005, 429-435

Costa, M.; et al, “Oxidative stress biomarkers and heart function in bullfrog tadpoles exposed to Roundup Original”, Ecotoxicology, 2008, 17, 153-163

Dallegrave, E.; et al, “Pre- and postnatal toxicity of the commercial glyphosate formulation in Wistar rats,” Archives of Toxicology, 81, 2007, 665-673

De Roos, A.; et al, “Cancer Incidence among Glyphosate-Exposed Pesticide Applicators in the Agricultural Health Study”, Environmental Health Perspectives, 113, 2005, 1, 49-54

Garry,V.; et al, “Birth defects, season of conception, and sex of children born to pesticide applicators living in the Red River Valley of Minnesota, USA”, Environmental Health Perspectives, 110, 2002, Suppl 9, 441-449.

Gasnier, et al, “Glyphosate-based herbicides are toxic and endocrine disruptors in human cell lines”, Toxicology, 262, # 3, 2009

Glusczak, L.; et al, “Effect of Glyphosate herbicide on acetylcholinesterase activity and metabolic and hematological parameters in piava (Leporinus obtusidens)”, Ecotoxicology and Environmental Safety, 65, 2006, 237-241

Gove, B.; et al, “Effects of herbicide spray drift and fertilizer overspread on selected species of woodland ground flora: comparison between short-term and long-term impact assessments and field surveys”, Journal of Applied Ecology, 2007, 44, 374-384

Hardell, L., “A case-control study of non-Hodgkin Lymphoma and exposure to pesticides”, Cancer, 85, 2, 1999, 1353-1360

Marc, J.; et al, “Glyphosate-based pesticides affect cell cycle regulation”, Biology of the Cell, 96, 2004, 3, 245-249

Neumann, G.; et al, “Journal of Plant Diseases and Protection”, Special Issue 20, 2006, Univ. Hohenheim, Inst. Plant Nutrit 330, D- 70593 Stuttgart, Germany, 963-969.

Perez, G., et al, “Effects of the herbicide roundup on freshwater microbial communities: a mesocosm study”, Ecological Applications, 17, 2007, 2310-2322

Soso, A.B.; et al, “Chronic exposure to sub-lethal concentrations of a glyphosate-based herbicide alters hormone profiles and affects reproduction of female Jundia (Rhamdia quelen)”, Environmental Toxicology and Pharmacology, 23, 2007, 308-313

Yousef, M.; et al, “Toxic effects of carbofuran and glyphosate on semen characteristics in rabbits”, Journal of Environmental Science Health, B30, 4, 1995, 513-534