Navigation Links
Pitt research finds that low concentrations of pesticides can become toxic mixture
Date:11/11/2008

PITTSBURGH Ten of the world's most popular pesticides can decimate amphibian populations when mixed together even if the concentration of the individual chemicals are within limits considered safe, according to University of Pittsburgh research published Nov. 11 in the online edition of Oecologia. Such "cocktails of contaminants" are frequently detected in nature, the paper notes, and the Pitt findings offer the first illustration of how a large mixture of pesticides can adversely affect the environment.

Study author Rick Relyea, an associate professor of biological sciences in Pitt's School of Arts and Sciences, exposed gray tree frog and leopard frog tadpoles to small amounts of the 10 pesticides that are widely used throughout the world. Relyea selected five insecticidescarbaryl, chlorpyrifos, diazinon, endosulfan, and malathionand five herbicidesacetochlor, atrazine, glyphosate, metolachlor, and 2,4-D. He administered the following doses: each of the pesticides alone, the insecticides combined, a mix of the five herbicides, or all 10 of the poisons.

Relyea found that a mixture of all 10 chemicals killed 99 percent of leopard frog tadpoles as did the insecticide-only mixture; the herbicide mixture had no effect on the tadpoles. While leopard frogs perished, gray tree frogs did not succumb to the poisons and instead flourished in the absence of leopard frog competitors.

Relyea also discovered that endosulfana neurotoxin banned in several nations but still used extensively in U.S. agricultureis inordinately deadly to leopard frog tadpoles. By itself, the chemical caused 84 percent of the leopard frogs to die. This lethality was previously unknown because current regulations from the U.S. Environmental Protection Agency (EPA) do not require amphibian testing, Relyea said. His results showed that endosulfan was not only highly toxic to leopard frogs, but also that it served as the linchpin of the pesticide mixture that eliminated the bulk of leopard frog tadpoles.

"Endosulfan appears to be about 1,000-times more lethal to amphibians than other pesticides that we have examined," Relyea said. "Unfortunately, pesticide regulations do not require amphibian testing, so very little is known about endosulfan's impact on amphibians, despite being sprayed in the environment for more than five decades."

For most of the pesticides, the concentration Relyea administered (2 to 16 parts per billion) was far below the human-lifetime-exposure levels set by the EPA and also fell short of the maximum concentrations detected in natural bodies of water. But the research suggests that these low concentrationswhich can travel easily by water and, particularly, windcan combine into one toxic mixture. In the published paper, Relyea points out that declining amphibian populations have been recorded in pristine areas far downwind from areas of active pesticide use, and he suggests that the chemical cocktail he describes could be a culprit.

The results of this study build on a nine-year effort by Relyea to understand potential links between the global decline in amphibians, routine pesticide use, and the possible threat to humans in the future. Amphibians are considered an environmental indicator species because of their unique sensitivity to pollutants. Their demise from pesticide overexposure could foreshadow the fate of less sensitive animals, Relyea said. Leopard frogs, in particular, are vulnerable to contamination; once plentiful across North America, including Pennsylvania, their population has declined in recent years as pollution and deforestation have increased.

Relyea published a paper in the Oct. 1 edition of Ecological Applications reporting that gradual amounts of malathionthe most popular insecticide in the United Statesthat were too small to directly kill developing leopard frog tadpoles instead sparked a biological chain of events that deprived them of their primary food source. As a result, nearly half the tadpoles in the experiment did not reach maturity and would have died in nature. Relyea published papers in 2005 in the same journal suggesting that the popular weed-killer Roundup is "extremely lethal" to amphibians in concentrations found in the environment.


'/>"/>

Contact: Morgan Kelly
mekelly@pitt.edu
412-624-4356
University of Pittsburgh
Source:Eurekalert

Related biology news :

1. Research shows skeleton to be endocrine organ
2. Newly created cancer stem cells could aid breast cancer research
3. Dominant cholesterol-metabolism ideas challenged by new research
4. Researchers identify proteins involved in new neurodegenerative syndrome
5. Texas researchers and educators head for Antarctica
6. MGH researchers describe new way to identify, evolve novel enzymes
7. University of Pennsylvania researchers develop formula to gauge risk of disease clusters
8. University of Oregon researcher finds that on waters surface, nitric acid is not so tough
9. U of MN researchers discover noninvasive diagnostic tool for brain diseases
10. U of Minnesota researchers discover noninvasive diagnostic tool for brain diseases
11. Story ideas from the Journal of Lipid Research
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:12/15/2016)... and BADEN-BADEN, Germany , December 15, ... global financial services provider, today announced an agreement with NuData ... biometrics, to join forces. The partnership will enable clients to ... in compliance with local data protection regulation. ... In order to provide ...
(Date:12/15/2016)... ... has announced the addition of the "Global Military Biometrics Market 2016-2020" ... global military biometrics market to grow at a CAGR of 7.5% during ... on an in-depth market analysis with inputs from industry experts. The report ... The report also includes a discussion of the key vendors operating in ...
(Date:12/15/2016)... HILLS, Mich. , Dec. 15, 2016  There ... unlocking car doors or starting the engine. Continental will ... in Las Vegas . Through the ... (Passive Start and Entry) and biometric elements, the international ... field of vehicle personalization and authentication. "The ...
Breaking Biology News(10 mins):
(Date:1/18/2017)... 2017   Parent Project Muscular Dystrophy (PPMD) , ... Duchenne muscular dystrophy (Duchenne) , today announced a $600,000 ... of Technology (NJIT) and Talem Technologies (Talem) as part ... to assist people living with Duchenne. PPMD is ... an embedded computer, software, a force sensor and a ...
(Date:1/18/2017)... ... January 18, 2017 , ... Total Orthopedics and Sports Medicine ... Solofuse-P™. The operation took place on Wednesday, January 11, 2017 at Long Island ... anterior cervical discectomy and fusion on a 42 year old female who was ...
(Date:1/18/2017)... ... January 18, 2017 , ... Announced in December ... Institutes (MII). U.S. Secretary of Commerce Penny Pritzker has announced the award of ... of Defense has announced the award of a new Advanced Regenerative Manufacturing Institute ...
(Date:1/18/2017)... ... 18, 2017 , ... Researchers from a new study are stating that if levels ... prostate cancer treatment, this indicates there is still remaining prostate cancer cells that are more ... PSA test has always been an indicator of whether a man’s prostate cancer is ...
Breaking Biology Technology: