Photo: Des tests avec des colorants pour comprendre la migration de l'atrazine dans les cours d'eau, courtoisie USGS
Une nouvelle étude confirme le potentiel dévastateur du pesticide Atrazine sur le développement sexuel normal des rats mâles qui y sont exposés avant leur naissance, même à très basses doses. Les chercheurs du National Institute of Environmental Health Sciences des États-Unis ont démontré que même une exposition à des concentrations permises dans les sources d'eau potable provoquent des inflammations de la prostrate et atteigne leur puberté à un âge plus avancé que le groupe contrôle de rats.
L'atrazine est l'un des herbicides les plus utilisés aux États-Unis pour maîtriser les mauvaises herbes dans les champs de maïs et de canne à sucre. Il s'en répand 80 millions de livres à tous les ans. C'est l'ingrédient principal dans 40 marques d'herbicides sur le marché. Mais l'atrazine et ses sous-produits sont reconnus comme étant des perturbateurs endocriniens qui persistent dans l'environnement et aboutissent dans l'eau de surface et dans la nappe phréatique, sources d'eau potable.
La norme permise de contamination par l'atrazine dans l'eau potable est 3 parties par milliard(billion). On ne s'attendait pas à des effets décelables à de telles petites concentrations. Un autre scientifique, le professeur Tyrone Hayes de l'Université de la Californie qui se spécialise à étudier l'atrazine déclare que l'atrazine est "un perturbateur endocrinien puissant qui a des effets dangereux sur la vie sauvage, les animaux de laboratoire et les humains. L'atrazine castre chimiquement et féminise la faune et affaiblit le système immunitaire de la faune et les rongeurs de laboratoire. L'atrazine provoque des cancers du sein et de la prostate, retarde le développement des glandes mammaires et provoque des avortements chez les rongeurs de labo. Des études dans les populations humaines et sur les tissus humains suggèrent que l'atrazine pose un danger semblable aux humains."
Au mois de mars 2010, 16 communautés dans 6 états du midwest ont entamé des procédures judiciaires pour forcer le fabriquant de l'atrazine Syngenta de payer pour le retrait de l'herbicide de leur eau potable. L'atrazine est interdit en Europe, même en Suisse, où l'on fabrique le produit chimique.
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"Atrazine Threat to Male Sexual Development Revealed
Male rats exposed before birth to low doses of the weedkiller atrazine are more likely to develop prostate inflammation and to go through puberty later than non-exposed animals, finds a new study conducted by federal government scientists. One of the most common agricultural herbicides in the United States, some 80 million pounds of atrazine are applied across the country every year to control broadleaf and grassy weeds in crops such as corn and sugar cane. It is the main ingredient in about 40 name-brand herbicides.
But atrazine and its byproducts are known to be endocrine disrupters that are persistent in the environment, making their way into both surface water and groundwater supplies. This study on how atrazine affects male rats was led by Suzanne Fenton, PhD, and Jason Stanko, PhD, of the National Institute of Environmental Health Sciences, part of the National Institutes of Health. The scientists tested male rats using atrazine concentrations close to the regulated levels in drinking water sources.
The current maximum contamination level of atrazine allowed in drinking water is three parts per billion. "We didn't expect to see these kinds of effects at such low levels," Fenton said, releasing the findings Tuesday. In 2009, the EPA began a comprehensive new evaluation of atrazine to determine its effects on humans. At the end of this process, in September 2010, the agency has said it will decide whether to revise its current risk assessment of atrazine and whether new restrictions are necessary to better protect public health.
Professor Tyrone Hayes in the Department of Integrative Biology at the University of California, Berkeley, who specializes in the study of atrazine, calls the chemical, "a potent endocrine disruptor with ill effects in wildlife, laboratory animals and humans." "Atrazine chemically castrates and feminizes wildlife and reduces immune function in both wildlife and laboratory rodents," says Hayes, who has published research showing that exposure to atrazine caused male tadpoles to turn into hermaphrodites - frogs with both male and female sexual characteristics. "Atrazine induces breast and prostate cancer, retards mammary development and induces abortion in laboratory rodents," Hayes warns. "Studies in human populations and cell and tissue studies suggest that atrazine poses similar threats to humans."
In March, 16 communities in six Midwestern states filed a federal lawsuit seeking to force atrazine manufacturer, the Swiss company Syngenta, to pay for removal of the herbicide from their drinking water. The class action lawsuit was filed in U.S. District Court for the Southern District of Illinois by 16 towns and villages in Kansas, Illinois, Indiana, Ohio, Missouri, and Iowa. Atrazine has been banned in Europe, even in Switzerland, the home of manufacturer Syngenta."
Excerpts from article in Environment News Service here: http://www.ens-newswire.com/ens/aug2010/2010-08-25-02.html
Ever heard of a race that made itself sterile by the way it grew its food? I would hope this is the story line of a very bad sci-fi movie!
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