Tests sur les pesticides en labo sont imparfaits

Photo: PlanetSave.com

Une biologiste en Colombie Britannique affirme que les standards fédéraux qui évaluent les concentrations acceptables des pesticides fixés en laboratoire ne reflètent pas les effets observés sur le terrain, dans ce cas-ci la Okanagan Valley. Il en résulte que les amphibiens en souffrent. Elle affirme que toutes les lois actuelles au Canada sont basées sur des tests en laboratoire, ce qui serait un défaut fondamental.

Ses résultats sont basés sur 2 années en études en laboratoire et 4 années de travail sur le terrain: elle étudiait les concentrations de pesticides dans des étangs d'irrigation agricoles à risque de recevoir du ruissellement de pesticides dont la quantité variait selon la saison, la plante ou l'insecte visé et la récolte. Quand elle reproduisait les concentrations les plus élevées observées en laboratoire, un seul pesticide dans de l'eau purifiée à température stable sans prédateurs ni éclairage à l'ultra-violet, elle constatait des effets toxiques sur les amphibiens bien au-dessous des limites fédérales.

Elle dit que les lois fédérales pour les pesticides sont basées sur des résultats en laboratoire à court terme, et non des résultats sur le terrain où la toxicité peut être beaucoup plus élevée à cause de l'exposition à long terme et la possibilité que plus d'un pesticide ou contaminant augmente la toxicité.

Par exemple, elle a testé les effets du pesticide endosulfan, dont les limites fédérales acceptables sont 7,74 milligrammes par litre, mais qui est banni en Europe et dans certains états des USA, mais pas au Canada. C'est un perturbateur endocrinien qui provoque des changements morphologiques et physiologiques. À seulement 0,06 milligrammes par litre dans son expérience de 8 jours, les tétards avaient la queue crochue et des changements dans leur pigmentation, ce qui les rendaient plus vulnérable à la prédation dans un étang de la mauvaise couleur. Même des traces d'endosulfan provoquait de la réactivité chez les tétards et leur hyperactivité augmentait avec la concentration du pesticide dans l'eau.

Selon elle, nous ne pouvons pas gérer une espèce ou un habitat en se fiant sur des tests en laboratoire quand il se passe plus de choses sur le terrain, ce qui fait que les standards permis sont très toxiques. Les rayons ultraviolets sur le terrain augmentent aussi les effets toxiques des pesticides comme l'endosulfan, ajoute-t-elle. De plus, le sort de nos grenouilles et des autres amphibiens est d'autant plus en péril qu'ils doivent aussi faire face à d'autres menaces, comme la perte et la fragmentation de leur habitat, les espèces invasives, l'augmentation de leur exposition aux rayons ultraviolets (trou dans la couche d'ozone?) et la prédation.

Bonne nouvelle: le 9 juin 2010, l'EPA annonce qu'elle s'apprête à bannir l'endosulfan, son usage trop dangereux pour les travailleurs à la ferme et la vie sauvage: http://www.environmentalhealthnews.org/ehs/news/endosulfan-ban
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"Lab pesticide tests 'fundamentally flawed': biologist

Okanagan Valley amphibians suffer toxic effects of pesticides at levels considered safe by federal standards

Pesticides are having a toxic effect on amphibians even at concentrations substantially lower than federal allowable levels, a study in the southern Okanagan Valley has found. Alexandra de Jong Westman, a biologist with Vernon-based Summit Environmental Consultants Ltd., said the results emphasize the inadequacies of current regulations, including accepted standards for lab testing that fall short of field conditions. "All the pesticide regulations in Canada are based on lab results," she said in an interview. "There is a fundamental flaw in that."

Her findings are based on two years of lab studies and four years of field work involving the Pacific tree or chorus frog and great basin spadefoot in the southern Okanagan between Penticton and Osoyoos, on the Canada-U.S. border. It is one of Canada's most endangered landscapes for wildlife due to habitat loss from human development, including agriculture and vineyards. With funding from the Canadian Wildlife Service, de Jong Westman studied pesticide levels in agriculture irrigation ponds susceptible to pesticide run-off, the amount varying based on the season, the pest and the crop.

When she duplicated the highest levels under ideal lab conditions -- only one pesticide in purified water, stable temperature, no predators and no ultraviolet light -- she found toxic effects on amphibians well below federal limits. She said pesticide regulations are based on short-term lab results, not those in the field where toxicity can be much higher due to long-term exposure and the potential for more than one pesticide or contaminant to increase toxicity.

De Jong Westman said that based on LC50 tests she performed in 2007 on American bullfrogs -- an introduced species that tends to be found in ponds less polluted than those of native species -- the allowable limit for amphibians for the pesticide endosulfan is about 7.74 milligrams per litre. An LC50 test determines the amount of pesticide required to kill 50 per cent of test animals over four days. During the eight-day period of growth from egg to tadpole in her latest work, she found that endosulfan -- a controversial organochlorine and endocrine disrupter that's banned in Europe and some U.S. states, but not in Canada -- caused morphological and physiological changes. At 60,000 nanograms per litre, or just 0.06 milligrams, it caused kinking in the tail and loss of pigmentation in tadpoles. The latter would make them more vulnerable to predation in a brown pond environment. Even trace amounts of endosulfan caused excitability in tadpoles, the condition worsening with the amount of pesticide added to the water.

"We cannot expect to manage a species or habitat from lab results when there is more going on in the field, making the allowable standard highly toxic," she said. Exposure to ultraviolet light in the field can also worsen the toxic effects of pesticides like endosulfan, she said. Frogs and other amphibians face a host of threats beyond pesticides that include habitat loss and fragmentation, invasive species, increased ultraviolet radiation and predation. "

Excerpts from article written by Larry Pynn from The Vancouver Sun published here: http://www.vancouversun.com/technology/pesticide%20tests%20fundamentally%20flawed%20biologist/2993186/story.html

"Declaring that endosulfan is unsafe, the Environmental Protection Agency announced Wednesday (June 9th, 2010) that it is about to ban one of the last organochlorine pesticides still used in the United States." Source: http://www.environmentalhealthnews.org/ehs/news/endosulfan-ban

More and more studies are coming out and revealing the toxicity of our pesticides and their effects on the fauna around us. Amphibians are more vulnerable because they breathe through their skin and live where all our drainage water ends up, along with our toxins and our pollution. They are the canaries in the coal mine of the aquatic world.

L'Ontario misera sur l'eau

Le discours du trône du Premier Minstre de l'Ontario sera demain, lundi, et si on se fie sur son site Web, il fera la promotion des connaissances de sa province dans le domaine de l'eau: le traitement des eaux usées et la conservation. Il pense qu'il y a un marché global de l'eau et qu'il faut s'y plonger.

Les compagnies de l'Ontario sont reconnues pour leurs méthodes de désinfection à l'ultraviolet, d'installations de traitements d'eaux usées compactes, d'information et systèmes informatiques sur l'eau, de conception et d'opération d'usines de traitement.

Un des points forts du discours demain sera une stratégie pour protéger, conserver et gérer les eaux douces de la province. Elle sera appuyée par une loi de viabilité de l'eau qui sera dévoilée au printemps. En plus de créér des emplois, la province veut améliorer la qualité de l'eau et des infrastructures et créer une "culture de conservation de l'eau".

Une autre priorité sera de réparer les vieux tuyaux d'aqueduc et colmater les fuites dans le système d'infrastructures aquatiques vieillissant de la province. Les taxes d'eau vont probablement monter, mais serviront à payer pour les travaux. Leur intention est de faire comprendre le prix réel de traiter l'eau potable et de disposer des boues.
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"Premier hopes to turn water into gold
Plans afoot to capitalize on province's treatment, conservation know-how

The Liberal government wants to capitalize on Ontario's technological know-how in water treatment and conservation to become a player in the multi-billion-dollar global water market. The Liberals hope a water strategy will lead to job growth, much like their expectations for the Green Energy Act – legislation passed recently which they say will yield 50,000 jobs in the next few years. Ontario firms are recognized leaders in ultraviolet disinfection, compact sewage treatment, water information and systems software and in plant design and operation, Premier Dalton McGuinty's website notes.

The adoption of a strategy to protect, conserve and manage the province's vast fresh water supply will be a key component of the government's throne speech on Monday, the Star has learned. The strategy will be supported by a new water sustainability act, which the government expects to unveil this spring. In addition to creating jobs, a government insider said the province also wants to improve water quality and infrastructure and create a "culture of water conservation."

Another top priority will be to repair old water pipes and stop leaks in the province's aging water infrastructure system. Discovering new ways to reuse water that from household washing machines and sinks, innovative water treatment services and improvements on the collection of storm water runoff are all areas that could yield jobs, the source said. McGuinty hinted last week at a fundraising dinner the government will soon unveil an "Open Ontario" plan that looks at ways to build on the province's clean water strength.

"Open Ontario" is a new Liberal agenda that will target promising areas of the economy – from water to the mining of chromite in the north – to help lift the province out of its $24.7 billion deficit. McGuinty noted that in the next 20 years, worldwide demand for water will be 40 per cent greater than supply, forcing people to find new ways to use less water and purify polluted water.

"Ontario has been quietly growing one of the biggest clean water industries in North America," he said. "Our services and technologies are being sold here at home and around the world. And that means great Ontario jobs." The Conference Board of Canada estimates the global market for water technology at over $450 billion with annual growth of up to 15 per cent, he added. "So, why wouldn't we organize ourselves to grab an even bigger share of that market for Ontario?" McGuinty asked. "We're doing exactly that for clean energy so, why not for clean water?"McGuinty led a trade mission to India last December, accompanied by 25 Ontario representatives from the green energy and water sectors with the goal of promoting the province's businesses.

Liberal MPP David Caplan (Don Valley East) last month introduced a private member's bill that proposed a major revamping of the province's water system – one that would see residents pay the full cost of water use. Caplan, a former infrastructure minister, says the monthly cost of his plan for an average family would be about $50. His aim is to make people aware of how much water they use by metering usage in homes and charging the actual cost of producing clean water and treating the waste. The proceeds would be put into fixing the province's water infrastructure.

Earlier this week, Brad Duguid, minister of energy and infrastructure, wrote a letter to an Ottawa newspaper confirming the Liberals are developing a strategy that will make Ontario a "global leader" in the water and waste water sectors."In the weeks to come, an ambitious path forward will be outlined for this important sector which will not only seek to achieve our long-term goals of water sustainability, but will also use Ontario's advantages to create jobs," Duguid wrote.

Excerpts from article written by Tanya Talaga published in thestar.com here: http://www.thestar.com/news/ontario/article/775957--premier-hopes-to-turn-water-into-gold

L'heureuse transformation de la rivière Grand Calumet

Il y a de cela 35 ans, l'usine de traitement des eaux usées East Chicago Sanitary District Wastewater Treatment Plant a changé ses méthodes d'assainissement: le traitement final ne se ferait plus par l'ajout de chlore. À la place, des lumières UV suspendues au-dessus de bassins finissent de tuer les bactéries dans l'eau à la sortie de l'usine. On a pu observer des changements au fil des années: le dernier bassin a vu une colonie d'éponges coloniser les herbes aquatiques qui y poussaient. Parmis les éponges et les herbes, des bancs de petits poissons se sont mis à y nager: le bassin se transformait en récif corallien! Les alevins se sont révélés être des saumons Chinook! L'effluent de l'usine, 40 pieds de large et 700 pieds de long, ressemble plus à un petit ruisseau qu'à un canal de béton: 95 espèces d'oiseaux le visitent; on y trouve des tortues, des chevreuils, une colonie de castors et l'occasionel coyote!

La rivière Grand Calumet en a aussi profité: à part la migration annuelle du saumon, on y retrouve le meunier noir, l'achigan à petite bouche et le crapet soleil. On a même aperçu le Chevalier de rivière la considerer comme frayère. On a constaté la présence de daphnies, des petits crustacés, dans les filtres 7 mois de suite!

Un article en anglais sur le sujet se trouve au lien suivant: http://www.chicagowildernessmag.org/issues/fall2007/sponges.html


Il y a 2 ans, Montréal a choisi l'ozone plutôt que les rayons ultraviolets. Selon les essais à Montréal, les rayons UV auraient tué des poissons, alors que l'ozone pas. Dans Le Devoir:
http://www.ledevoir.com/politique/villes-et-regions/173936/montreal-veut-desinfecter-ses-eaux-usees

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"(...)The water district had invested $19 million to overhaul the plant, to comply with federal Clean Water Act standards. Instead of adding chlorine to kill bacteria, which it had done for years, the plant started using long racks of powerful ultraviolet lights.(...)Some 18 years since the switch to UV, the now annual salmon run is only part of the story. Perhaps a more important sign of the river’s road to recovery is the appearance, according to surveys by the Aquatic Resource Center and Klocek, of white sucker, smallmouth bass, pumpkinseed, and rock bass, all native Illinois fish. Especially promising is the spawning of state-threatened river redhorse, which requires clear, clean water for survival. Recent surveys have also found daphnia, a small, shrimplike crustacean dependent on good water quality, in the water filters for seven months in a row. It isn’t known whether the daphnia’s presence is the result of the sponge colonies.(...)"

Read the complete article here: http://www.chicagowildernessmag.org/issues/fall2007/sponges.html

Two years ago, Montreal tried UV rays and ozone treatment. They chose ozone because trials with UV caused fish kill. Article here: http://dcnonl.com/article/id30360