Glyphosate: Difference between revisions
what exactly are you doing beetstra? it looks a little confusing, anyways I am restoring to y'alls version, but I have placed the true source of that claim about conservation groups, read that 1st PDF |
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== Toxicity== |
== Toxicity== |
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Glyphosate is less toxic than a number of other herbicides and pesticides, such as those from the [[organochlorine]] family [http://whatcom.wsu.edu/ag/comhort/nooksack/ipmweb/Pesticideselection.html]. Conservation groups have chosen glyphosate formulations because of their effectiveness against most weeds, and the fact that glyphosate has very low toxicity to wildlife. |
Glyphosate is less toxic than a number of other herbicides and pesticides, such as those from the [[organochlorine]] family [http://whatcom.wsu.edu/ag/comhort/nooksack/ipmweb/Pesticideselection.html]. Conservation groups have chosen glyphosate formulations because of their effectiveness against most weeds, and the fact that glyphosate has very low toxicity to wildlife.[http://www.monsanto.com/monsanto/layout/VSearchResults.asp?queryText=conservation+groups+glyphosate] |
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===Humans=== |
===Humans=== |
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Glyphosate (N-(phosphonomethyl) glycine is a non-selective systemic herbicide, absorbed through the leaves, used to kill weeds, especially perennials. Some crops having been genetically engineered to be resistant to it. Glyphosate was first sold by Monsanto under the tradename Roundup, but is no longer under patent.
Chemistry
Glyphosate is an aminophosphonic analogue of the natural amino acid glycine and the name is a contraction of glycine, phospho-, and -ate. Glyphosate was first discovered to have herbicidal activity in 1970 by John Franz, while working for Monsanto[16]. In 1987 Franz received the National Medal of Technology for his discoveries [17], and in 1990 he received the Perkin Medal for Applied Chemistry [18].
Biochemistry
Glyphosate kills plants by inhibiting the enzyme 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS), which catalyzes the reaction of shikimate-3-phosphate (S3P) and phosphoenolpyruvate to form 5-enolpyruvyl-shikimate-3-phosphate (ESP). ESP is subsequently dephosphorylated to chorismate an essential precursor in plants for the aromatic amino acids: phenylalanine, tyrosine and tryptophan [19], [20]. These amino acids are used as building blocks in peptides and to produce secondary metabolites such as folates, ubiquinones and naphthoquinone. The shikimate pathway is not present in animals, which obtain aromatic amino acids from their diet.
Use
Glyphosate is effective in killing a wide variety of plants, including grasses, broadleaf, and woody plants[1]. It has a relatively small effect on clover[citation needed]. By volume, it is one of the most widely used herbicides [2]. It is commonly used for agriculture, horticulture, and silviculture purposes, as well as garden maintenance (including home use)[2].
Genetically modified crops
Some microorganisms have a version of 5-enolpyruvoyl-shikimate-3-phosphate synthetase (EPSPS) that is resistant to glyphosate inhibition. The version used in genetically modified crops was isolated from Agrobacterium strain CP4 (CP4 EPSPS) that was resistant to glyphosate[3] [4]. This CP4 EPSPS gene was cloned and transfected into soybeans, and in 1996, such genetically modified soybeans were made commercially available [5]. This greatly improved the ability to control weeds in soybean fields since glyphosate could be sprayed on fields without hurting the crop. As of 2005, 87% of U.S. soybean fields were planted with glyphosate resistant varieties [6] [7].
Other uses
Glyphosate is one of a number of herbicides used by the United States government to spray Colombian coca fields through Plan Colombia. Its health effects, effects on legal crops, and effectiveness in fighting the war on drugs have been widely disputed [8].
Toxicity
Glyphosate is less toxic than a number of other herbicides and pesticides, such as those from the organochlorine family [21]. Conservation groups have chosen glyphosate formulations because of their effectiveness against most weeds, and the fact that glyphosate has very low toxicity to wildlife.[22]
Humans
A review of the literature in 2000 concluded that "under present and expected conditions of new use, there is no potential for Roundup herbicide to pose a health risk to humans"[9]. This review considered the likely effects experienced by the two groups most likely to have high exposures, herbicide applicators and children aged 1-6, noting the exposure in those subpopulations was not a health concern [9]. Glyphosate has an EPA Toxicity Class of III in 1993 [10], but more recent studies suggest that IV is appropriate for oral, dermal, and inhalation exposure[9]. It has been rated as class I (Severe) for eye irritation, however [9].
Outside its intended use, glysophate can be lethal. For example, with intentional poisonings (e.g. suicide), there is approximately a 10% mortality for those ingesting glysophate, compared to 70% for those ingesting paraquat [11].
Laboratory toxicology studies suggest that other ingredients combined with glyphosate may have greater toxicity than glyphosate alone. For example, a study comparing glyphosate and Roundup found that Roundup had a greater effect on aromatase than glyphosate alone [12].
Statistics from the Californian Environmental Protection Agencies Pesticide Illness Surveillance Program program indicate that glyphosate related incidents are one of the highest reported of all pesticides [13]. However, incident count does not take into account the number of people exposed and the severity of symptoms associated with each incident [14]. For example if hospitalization is used as a measure of the severity of pesticide related incidents, then Glyphosate would be considered relatively safe, since over a 13 year period in California none of the 515 pesticide related hospitalizations recorded were attributed to glyphosate [14].
Greenpeace states that "the acute toxicity of glyphosate is very low", but note that, as mentioned above, other chemicals (particularly surfactants, e.g., POEA) can be more toxic than glyphosate itself[1].
Other species
The direct toxicity of pure glyphosate to mammals and birds is low [23]. In vitro studies indicate Glyphosate formulations could negatively impact earthworms [15] and beneficial insects. [16] However these results conflict with results from field studies where no effects were noted for the number of nematodes, mites, or springtails after treatment with Roundup at 2 kg active ingredient per ha. [17]
Certain surfactants used in some glyphosate formulations have have higher toxicity to Fish and invertebrates resulting in some formulations of glyphosate not being registered for use in aquatic applications. [18] Monsanto produces Glyphosate products with alternative surfactants that are specifically formulate for aquatic use - eg "Biactive" and "AquaMaster".[19]
When glyphosate comes into contact with the soil, it rapidly binds to soil particles and is inactivated[20] [21]. Unbound glyphosate is degraded by bacteria. Low activity because of binding to soil particles suggests that glyphosate's effects on soil flora will be limited. However, some recent work shows that glyphosate can be readily released from certain types of soil particles, and therefore may leach into water or be taken up by plants [citation needed]. Low glyphosate concentrations can be found in many creeks and rivers in U.S. and Europe[citation needed].
Mammalian research indicates oral intake of 1% glyphosate induces changes in liver enzyme activities in pregnant rats and their fetuses.[24][25]
Health concerns
There are concerns about the effects of glyphosate (and Roundup) on non-plant species even including on possible human reproductive dysfunction. For more information, see the Roundup article.
Endocrine disruptor debate
In vitro studies have shown glyphosate effects progesterone production in mammalian cells [22] and can increase the mortality of placental cells [12]. Whether these studies classify glyphosate as an endocrine disruptor is a matter of debate.
Some feel that in vitro studies are insufficient, and are waiting to see if animal studies show a change in endocrine activity, since a change in a single cell line may not occur in an entire organism. Additionally, current in vitro studies expose cell lines to concentrations orders of magnitude greater than would be found in real conditions, and through pathways that would not be experienced in real organism.
Others feel that in vitro studies, particularly ones identifying not only an effect, but a chemical pathway, are sufficient evidence to classify glyphosate as an endocrine disruptor, on the basis that even small changes in endocrine activity can have lasting effects on an entire organism that may be difficult to detect through whole organism studies alone. Further research on the topic has been planned, and should shed more light on the debate.
References
- ^ a b Greenpeace. (1997). Weed Killing Crops: Glyphosate and Your Food.[1]
- ^ a b U.S. Environmental Protection Agency. (2006). Technical Factsheet on: GLYPHOSATE [2]
- ^ Development and Characterization of a CP4 EPSPS-Based, Glyphosate-Tolerant Corn Event,G. R. Heck et al Crop Sci. 45:329-339 (2005).[3]
- ^ Molecular basis for the herbicide resistance of Roundup Ready crops, T. Funke et al, PNAS 2006 103:13010-13015 [4]
- ^ Monsanto Company History - Monsanto Web Site - monsanto.com[5]
- ^ USDA/APHIS Environmental Assessment - In response to Monsanto Petition 06-178-01p seeking a Determination of Non-regulated Status for Roundup RReady2Yield Soybean MON 89788, OECD Unique Identifier MON-89788-1, U.S. Department of Agriculture Animal and Plant Health Inspection Service Biotechnology Regulatory Services, page 13[6]
- ^ National Agriculture Statistics Service (2005) in Acreage eds. Johanns, M. & Wiyatt, S. D. 6 30, (U.S. Dept. of Agriculture, Washington, DC).
- ^ IRC Americas Program Commentary (2005): Plan Colombia’s Drug Eradication Program Misses the Mark
- ^ a b c d GM Williams, R Kroes, JC Munro (2000). "Safety evaluation and risk assessment of the herbicide Roundup and its active ingredient, glyphosate, for humans". Regulatory Toxicology and Pharmacology. 31-N2: 117–165.
{{cite journal}}: CS1 maint: multiple names: authors list (link) PMID 10854122. - ^ U.S. EPA ReRegistration Decision Fact Sheet for Glyphosate (EPA-738-F-93-011) 1993. [7]
- ^ Nagami et al. (2005). Hospital-based survey of pesticide poisoning in Japan, 1998--2002. Int J Occup Environ Health, 11(2):180-4.PMID 15875894
- ^ a b Richard S, Moslemi S, Sipahutar H, Benachour N, Seralini GE. (2005) Differential effects of glyphosate and roundup on human placental cells and aromatase, Environmental Health Perspectives, 113 (6): 716-720. PMID 15929894 Full Text
- ^ Goldstein DA et al An analysis of glyphosate data from the California Environmental Protection Agency Pesticide Illness Surveillance Program J Toxicol Clin Toxicol. 2002 40:885-92 [8]
- ^ a b California EPA 1996, California Pesticide Illness Serveillance Program Report HS-1733 [9]
- ^ JA Springett and RAJ Gray, Effect of repeated low doses of biocides on the earthworm Aporrectodea caliginosa in laboratory culture. Soil Biol and Biochem. Vol. 24, no. 12, pp. 1739-1744. 1992.[10]
- ^ Hassan, S.A., F. Bigler, H. Bogenschutz, E. Boller, J. Brun, P. Chiverton, P. Edwards, F. Mansour, E. Naton, P.A. Oomen, W.P.J. Overmeer, L. Polgar, W. Rieckman, L. Samsoe-Petersen, A. Staubli, G. Sterk, K. Tavares, J.J. Tuset, G. Viggiani, and A.G. Vivas. 1988. Results of the fourth joint pesticide testing programme carried out by the IOBC/WPRS-Working Group
- ^ CM Preston and J.A. Trofymow. 1989. Effects of glyphosate (Roundup) on biological activity of forest soils. In: Proceedings of Carnation Creek Workshop, ed. P. Reynolds. Namaimo 7-10 December 1987. Forest Canada/British Columbia ministry of forests, 122-140.
- ^ Response to "The impact of insecticides and herbicides on the biodiversity and productivity of aquatic communities", Monsanto Corporation Backgrounder [11]
- ^ Aquatic Use of Glyphosate Herbicides in Australia, Monsanto Corporation Backgrounder[12]
- ^ US EPA Reregistration Eligibility Decision - Glyphosate[13]
- ^ M.M. de Andréa et al, Influence of repeated applications of glyphosate on its persistence and soil bioactivity Pesq. agropec. bras., Brasília, v. 38, n. 11, p. 1329-1335, nov. 2003[14]
- ^ Walsh LP, et al (2000). "Roundup inhibits steroidogenesis by disrupting steroidogenic acute regulatory (stAR) protein expression.". Environmental Health Perspectives 108-N8: 769-776.[15]
- EU (2002). Review report for the active substance glyphosate. Retrieved October 28, 2005.
- JP Giesy, KR Solomon, S Dobson (2000). "Ecotoxicological Risk Assessment for Roundup Herbicide". Reviews of Environmental Contamination and Toxicology. 167: 35–120.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - KR Solomon, DG Thompson (2003). "Ecological risk assessment for aquatic organisms from over-water uses of glyphosate". Journal of Toxicology and Environmental Health. 6: 289–324.
- World Health Organization. (1994) Environmental Health Criteria 159: Glyphosate. [26]
- Monsanto History of Glyphosate.[27]