Los cientificos rebeldes a las Corporaciones: glifosato Monsanto y CyT
Colegas: Hay una campaña bastante fuerte para desacreditar al Dr. Carrasco, con independencia de que lo que el dió, técnicamente, es una “Opinión experta” y no la comunicación de un trabajo científico terminado y publicado. Ambas cosas son válidas a diferente nivel. Yo creo que cualquier científico puede opinar en el área donde es experto, en base a su experiencia; y la opinión es mas fuerte si se tienen indicios observacionales o lo que se denominan “resultados preliminares”. Por supuesto que el trabajo final (que puede tardar años) determina los hechos incuestionables, pero eso no tiene nada que ver con compartir con la sociedad las señales de alerta sobre algo potencialmente tóxico, que en última instancia es lo que ha hecho Carrasco.
Si uno analiza unos pocos de los cientos (o miles) de artículos dedicados al glifosato aparecen algunos hechos:
(1) El glifosato puro en sí mismo parece de baja toxicidad, pero no deja de ser tóxico para el ambiente aunque parece poco tóxico para vertebrados.
(2) Las formulaciones son mucho mas tóxicas que el compuesto puro (porque se usan surfactantes que ayudan a penetrar).
(3) Es muy dificil y costoso dosar el glifosato, con lo cual los datos ambientales no está claro cuan confiables son.
(4) En algunas de las zonas donde se aplica el glifosato hay, aparentemente, problemas de salud que no están debidamente aclarados. Algunos sugieren que existe sinergia entre las formulaciones de glifosato (mas tóxicas que glifosato) y otros tóxicos, con potenciación de la toxicidad (aspecto poco o no estudiado).
(5) La toxicidad para organismos acuaticos, incluyendo peces y algas, es mucho mayor. Lo mas interesante es que el glifosato es ESPECIALMENTE tóxico para anfibios (ranas, sapos, etc). Justamente el tipo de tocxicidad que analizó Carrasco.
(6) Las conexiones tóxicas del glifosato-formulación, están poco probadas directamente pero al parecer son epidemiologicamente significativas. Algunas serían:
à Daño en ADN en ratones y en linfocitos humanos (en sangre).
à linfomas No-Hodgkins
à abortos humanos
à desorden de atención en humanos (familias de Minessota, 2002)
Obviamente es un tema donde no mucha gente se quiere meter….
Hay una buena review:
Glyphosate Poisoning.
Review Article
Toxicological Reviews. 23(3):159-167, 2004.
Bradberry, Sally M; Proudfoot, Alex T; Vale, J Allister
Abstract:
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(R) 1(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 >85mL 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(R) (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.
Copyright 2004 Adis Data Information BV
Y en internet hay miles de articulos de grupos ecologistas, naturistas y “organicos” como el que sigue:
http://www.safe2use.com/poisons-pesticides/pesticides/organo/glyphosate.htm
ARTICULO ORIGINAL: http://www.greenpeaceusa.org/media/factsheets/glyphosatetext.htm
Human Toxicity
Because the shikimic acid pathway does not exist in animals, the acute toxicity of glyphosate is very low. Glyphosate can interfere with some enzyme functions in animals but symptoms of poisoning are only seen at very high doses. However, products containing glyphosate also contain other compounds which can be toxic. In particular most contain surfactants known as polyoxyethyleneamines (POEA). Some of these are much more toxic than glyphosate. These account for problems associated with worker exposure. They are serious irritants of the respiratory tract, eyes and skin and are contaminated with dioxane (not dioxin) which is a suspected carcinogen. Some are toxic to fish.
In California, glyphosate is the third most commonly-reported cause of pesticide related illness among agricultural workers. Glyphosate is the most frequent cause of complaints to the UK’s Health and Safety Executive’s Pesticides Incident Appraisal Panel. New formulations, with less irritating surfactants, have been developed by Monsanto (e.g. Roundup Biactive), but cheaper, older preparations are still available.
Environmental Toxicity
Glyphosate is one of the most toxic herbicides, with many species of wild plants being damaged or killed by applications of less than 10 micrograms per plant. Glyphosate can be more damaging to wild flora than many other herbicides, as aerial spraying with glyphosate can give average drifts of 1200 to 2500 feet and ground spraying with glyphosate may cause damage to sensitive plants up to 300 feet from the field sprayed. Glyphosate use is thought to affect hedgerow trees, causing die-back, and may reduce trees' winter hardiness and resistance to fungal disease
The direct toxicity of glyphosate to mammals and birds is low. However, its effect on flora can have a damaging effect on mammals and birds through habitat destruction. The US EPA concluded that many endangered species of plants, as well as the Houston toad, may be at risk from glyphosate use.
Fish and invertebrates are more sensitive to formulations of glyphosate. As with humans, the surfactants are responsible for much of the harm . Toxicity is increased with higher water temperatures, and pH. In Australia, guidelines state that most formulations of glyphosate should not be used in or near water because of their toxic effects on tadpoles and adult frogs. The newer, non-irritant formulations such as Roundup Biactive are not included in this advice.
Of nine herbicides tested for their toxicity to soil microorganisms, glyphosate was found to be the second most toxic to a range of bacteria, fungi, actinomycetes and yeasts. However, when glyphosate comes into contact with the soil it rapidly binds to soil particles and is inactivated. 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.
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