Roundup is the brand name of a family of herbicides produced by the American chemical manufacturer Monsanto. Systemic and non-selective, Roundup is the world's single most popular herbicide.
The active ingredient of Roundup is the isopropylamine salt of glyphosate. Glyphosate's mode of action is to inhibit an enzyme involved in the synthesis of the amino acids tyrosine, tryptophan, and phenylalanine. It is absorbed through foliage and translocated to growing points. Because of this mode of action it is only effective on actively growing plants; it is not effective as a pre-emergence herbicide. Due to the absorption being limited to foliage, soil-bound glyphosate is effectively inert.
Monsanto also produces seeds which grow into plants genetically engineered to be tolerant to glyphosate, known as "Roundup Ready" crops. The genes contained in these seeds, although naturally occurring in other species, are patented and protected by intellectual property laws. Such crops allow farmers to use glyphosate as a post-emergence pesticide against both broadleaf and cereal weeds.
While glyphosate itself is less toxic than table salt, as measured by standard LD50 testing, the surfactants used in the some Roundup products may cause health issues. Like all pesticides, Roundup should only be applied in accordance with all labeling and legal requirements. In repeated dose toxicity testing, Roundup Original RT was found to be mildly irritating to the eyes and not irritating dermally.
The US Environmental Protection Agency, the EC Health and Consumer Protection Directorate, and the UN World Health Organization have all independently concluded that glyphosate is not carcinogenic. Despite this, opponents of glyphosate-based pesticides frequently claim that glyphosate is linked to cancer, citing the research of Hardell and Eriksson (Cancer 85:1353-1360). Although this paper showed a link between glyphosate and lymphoma, this link was not statistically significant and was within the realm of random variation. The authors themselves concluded "definite conclusions cannot be drawn for separate chemicals, such as MCPA and glyphosate, from the multivariate analysis".
Opponents also claim that glyphosate has been found to cause genetic damage, citing the research of Peluso et al (Environ Molec Mutag 31:55-59). The authors concluded that the damage was "not related to the active ingredient, the isopropylammonium salt of glyphosate, but to another, unknown component of the herbicide mixture", so Roundup appears to cause genetic damage, while the main active ingredient doesn't.
Preliminary research indicates that glyphosate may increase the growth of the fungus fusarium solani in soils (Weed Sci 45:749-743). Because Roundup is used extensively in Colombia for coca eradication, this research has lead the director of the Institute for Policy Studies Drug Policy Project to speculate that the spread of Fusarium may upset the delicate environmental equilibrium of the Amazon river basin.[1]
Roundup is a total herbicide, whose toxicity has several times been questioned, not so much because of its active agent (glyphosate) but for the inactive ingredients, such as the surfactant agent polyoxy-ethyleneamine (POEA)]] [1]. These components are responsible for "acute" toxicity to humans such as eye irritation. This exaggeration is easily debunked--search for "silly" with your browser's find command Ingestion of Roundup has been proven to cause diarrhea in ridiculously high exposures, because any surfactant would be expected to do so. Some studies have also reported Glyphosate could be involved in some non-Hodgkin's lymphoma [1]. In California, Roundup has been identified as the third most commonly reported cause of pesticide-related illness amongst farmers exposed to bulk quantities, generally as eye irritation (Cox, 1995 b, Pease et al.1993). Glyphosate residues have been found in strawberries (Cessna & Cain, 1992), lettuce, carrots, barley (U.S. EPA, 1993), and fish (Wang et al., 1994, Folmar et al., 1979). Glyphosate residues persisted a long time after the glyphosate was used (for example, lettuce, carrots, and barley contained glyphosate residues at harvest when planted a year after treatment (U.S. EPA, 1993). Glyphosate was also reported killing fish at concentrations of 10 parts per million (WHO, UNEP & ILO, 1994), which is actually a very high concentration.
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