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Pesticides continue to contaminate US streams, USGS report says


(NaturalNews) A new report compiled by the U.S. Geological Survey (USGS) concludes that different types of pesticides are showing up in America's streams and rivers, threatening our planet's innate aquatic life.

New research indicates that, while the presence of some chemicals in streams and rivers has decreased over the last decade due to new regulatory restrictions, newly developed pesticides, such as neonicotinoids and glyphosate, are now the biggest polluters of water.

Researchers analyzed stream samples collected between 2002 and 2011 and compared them with previous samples taken between 1992 and 2001. Herbicide and insecticide levels were monitored for both decades, and streams were divided into agricultural, urban and mixed-use categories, according to the Bozeman Daily Chronicle.

One or more pesticides, or pesticide remnants, were detected in 90 percent of all stream categories over both decades, scientists say, with apparent differences in the type of chemicals found.

90 percent of urban streams contain pesticide concentrations that are toxic to aquatic life

The samples taken from the most recent decade show that fewer streams exceed the human health limits for pesticides, with only one stream exceeding the standard compared to 17 percent of agricultural streams in the previous decade.

However, water samples exceeded the recommended pesticide concentrations for aquatic life, causing adverse environmental impacts in birds, fish and insects. About two-thirds of agricultural streams and half of mixed-use streams contained pesticide concentrations exceeding the legal limit in both decades.

About 90 percent of urban streams contained pesticide concentrations exceeding allowable levels for aquatic life, compared to only 50 percent in the previous decade.

Herbicides such as DuPont's cyanazine, a toxicant known to cause mammary gland cancer in mice, entered the phase-out process in 1995, therefore reducing its presence in rivers and streams.

Newly developed pesticides replacing previously banned chemicals

However, newer use of chemicals like neonicotinoids and glyphosate, which is sprayed gratuitously on genetically modified (GM) crops, are beginning to appear more prevalently in nature. Between 1992 and 2001, the use of neonics was nonexistent, compared to the approximate 50 million pounds that are now being used today.

Monsanto's pride and joy, glyphosate, increased in usage from about 350 million pounds of application per year in 1992 to nearly 450 million pounds in 2011, according [PDF] to USGS statistical analysis.

"The information gained through this important research is critical to the evaluation of the risks associated with existing levels of pesticides," said William Werkheiser, USGS associate director for water.

The most common pesticides detected in the recent decade include atrazine, carbaryl, fipronil, metolachlor, prometon and simazine, all of which have been proven to disrupt aquatic life to varying extents.

The following pesticides were detected less frequently compared to the previous decade: alachlor, chlorpyrifos, cyanazine, diazinon, EPTC, Dacthal and tebuthiuron.

Due to its high toxicity in people, fish, birds and other animals, diazinon left store shelves in 2005 as part of an Environmental Protection Agency (EPA) program designed to curtail toxic pesticides.

Despite stricter legislation on pesticides, new toxicants continue to enter the market, with even less being known about their potential negative environmental impacts.

Fipronil and carbaryl were the most prevalent in samples collected from the recent decade, both of which are known to bioaccumulate in fish. Carbaryl, an insecticide used on corn, soy and citrus, poses a threat to beneficial insects such as bees.

Fipronil, a relatively new insecticide, degrades into a more toxic substance in the environment and is very persistent, according a 2003 University of Greenwich study. Fipronil is very toxic to termites, having lasting negative impacts on the insects, which is problematic, as they're considered a "key" species in terms of "nutrient cycling and soil fertility."

Two lizard species native to Madagascar were negatively impacted when fipronil killed off one of their favorite meals, termites.

Only through ongoing observation can scientists continue to unravel the destruction caused by pesticides persistent in the environment.

Additional sources:


http://bloximages.chicago2.vip.townnews.com [PDF]







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