Friends of the Richelieu. A river. A passion.

"Tout cedit pays est fort uny, remply de forests, vignes & noyers. Aucuns Chrestiens n'estoient encores parvenus jusques en cedit lieu, que nous, qui eusmes assez de peine à monter le riviere à la rame. " Samuel de Champlain

"All this region is very level and full of forests, vines and butternut trees. No Christian has ever visited this land and we had all the misery of the world trying to paddle the river upstream." Samuel de Champlain

Tuesday, April 6, 2010

Le chlordane: un pesticide qui dure, et qui dure...

Sources probables du chlordane (en rouge) selon l'université de l'Indiana

Bien que banni depuis plus de 2 décennies en Amérique du Nord, le chlordane a été trouvé en hautes concentrations dans des sédiments de deux ruisseaux urbains en Virginie: Meadow Creek et Schenk's Branch. Certains prélèvements contenaient des niveaux de chlordane de 40 @ 1,000 fois plus élevés que la norme fixée par l'EPA, cette norme déclarant un niveau de concentration qui serait probablement dangereux pour les plantes et les animaux en contact direct avec le produit. L'article n'ose pas pointer le coupable de cette contamination et suggère un déversement possible qui se serait produit dans le passé. On hésite à afficher ces deux ruisseaux en pleine ville, supposant que les humains ne seront pas tentés de s'y baigner, mais leurs chiens? Tout brassage de sédiments dans ces 2 ruisseaux remet en circulation dans l'environnement le poison insecticide.

Tous les humains ont été exposés au chlordane durant leur vie, car il se lie avec les cellules de graisse des animaux, et migrent ainsi d'un continent à l'autre. Ce qui est surprenant d'apprendre dans cet article, c'est que bien que l'usage du chlordane est interdit en Amérique du Nord, il s'en fabrique toujours pour l'exportation. C'est complètement insensé, quand on sait que ce produit ne connaît pas de frontières et se concentre ultimement dans les graisses des animaux aux pôles de notre planète, humains inclus. Les effets connus du chlordane sur la santé humaine sont des problèmes du système nerveux, du système digestif, et possiblement le chlordane pourrait être un imitateur endocrinien (visitez le site de Sabotage Hormonal pour en savoir plus sur les perturbateurs endocriniens).

Au Québec, bien que l'usage du chlordane soit interdit en Amérique du Nord, on en trouve toujours dans la pluie, et dans le lait maternel des mères Inuits. Non seulement utilisé pour traiter les maisons contre les termites aux É.-U., il était aussi utilisé sur le maïs (encore!) et dans les jardins. Pour un rapport sur le chlordane présenté par Le Centre international de Recherche sur le Cancer, qui fournit ces renseignements pour l'OMS, télécharger ce pdf de 82 pages (en anglais): Photo:

"Harmful pesticide found in city creeks

Abnormally high levels of a pesticide that was banned more than two decades ago because of its potential to harm plants, animals and people have been found in two Charlottesville creeks.

After the Virginia Department of Environmental Quality completed biological water sampling, state workers found high concentrations of chlordane, the pesticide, in the sediment of Meadow Creek and Schenk’s Branch. The two samples showed levels of chlordane that were 40 and 1,000 times higher, respectively, than the U.S. Environmental Protection Agency’s probable effects concentration benchmark — the concentration at which a chemical is likely to be harmful to plants or animals after direct exposure.

All humans have been exposed to some chlordane because of how it was used decades ago. But of the especially high levels found in the two Charlottesville creeks. The DEQ deems chlordane “moderately to highly toxic through all routes of exposure to humans, causing headaches, dizziness, vision problems, irritability, weakness, muscle twitching, and occasionally, convulsions.” Humans can be exposed to chlordane though ingestion, inhalation or by skin contact. The chemical is also highly toxic to birds, fish, macroinvertebrates and other insects.

Chlordane was used as a pesticide in the U.S. beginning in the late 1940s until 1988. According to the Agency for Toxic Substances and Disease Registry, a federal public health agency of the U.S. Department of Health and Human Services, the chemical was used as a fumigating agent and pesticide on agricultural crops, lawns and gardens before 1978. Those uses were banned over the subsequent five years because of concerns about cancer risk, evidence of human exposure and buildup in body fat, persistence in the environment and danger to wildlife. Most health effects in humans that may be linked to chlordane exposure are on the nervous system, the digestive system and the liver, mostly seen when the pesticide was ingested. From 1983 to 1988, chlordane’s only approved use was to control termites in homes, but that was banned in 1988. Manufacture for export continues, according to the agency.

The study is testing multiple locations in both streams to see if that will help pinpoint the source, and the work is being coordinated with the city government. “We may not be dealing with an active source,” Kain said. “What we could be looking at is sort of a legacy from historic use or historic spill that was never reported. But we just don’t know that yet.”A public health statement from the toxic substances agency said chlordane is unlikely to enter groundwater, but in water, some chlordane will strongly attach to sediment. John Murphy, the director of StreamWatch, a local organization that monitors water quality and stream health in the Rivanna River basin, said it may be difficult to evaluate the risk of endocrine disruption from this spill, but some endocrine disruptors can be dangerous even at very low exposure levels.

“Government agencies may not have adequate resources for such a risk analysis, and the body of scientific information about chlordane’s endocrine effects is not large. But given the magnitude of this spill, an analysis of the risk of endocrine effects should be considered,” Murphy said. “Another alternative would be for the authorities to apply a precautionary policy and warn folks to stay out of these streams, even if the risk can’t be concretely defined.”"

Excerpts from article written by Rachana Dixit for the Daily Progress of Charlottesville, Virginia, on line here:

For a more complete picture of chlordane in our lives, download this 82 pages pdf. It is a report made by The International Agency for Research on Cancer, advisors of the WHO:

No comments:

Post a Comment