Pollutants such as pesticides and toxins damage the ecosystem and cause a variety of damaging ailments in humans. One particular herbicide, Atrazine, has now been found to turn male frogs into hermaphrodites, rendering them impotent by causing their gonads to produce eggs.
A subject of great scientific and political controversy, Atrazine was first introduced in 1958 and today is one of the most widely used herbicides in the world. It is a potential carcinogen and has a half-life in soil of anywhere from 15 to 100 days. This time allows for
Atrazine biodegration, during which the chemical is dechlorinated until it produces a an end product of cyanuric acid, a
toxic compound.
Atrazine is also used throughout the world in the production of maize, sorghum, sugar cane, pineapples, chemical fallows, grassland, macadamia nuts, conifers forestry, roses and grassland. Its most common application is for use in conservation tillage systems to prevent
soil erosion and runoff, and to prevent weeds from growing in major
crops. As a result, a good deal of the Atrazine applied to crops is washed into rivers, streams, lakes and municipal drinking
water supplies.
A scientific study revealed the truth
In 2002, a breakthrough study on the
environmental effects of Atrazine was led by Dr. Tyrone B. Hayes, an associate professor of integrative biology at the University of California at Berkeley. The
research revealed that Atrazine not only contaminates ground and surface water, but also is an endocrine disruptor -- chemically castrating all male
amphibians by stripping them of a key hormone. This appears to have had a major impact on wild amphibians and is likely to be an important contributor to this species' global decline.
"What struck us as unbelievable was that Atrazine could cause such dramatic effects at such low levels," said Hayes. "If you take five grains of salt, divide this weight by five thousand, that is the amount of Atrazine that causes these abnormalities. Atrazine-exposed
frogs don't have normal reproductive systems. The males have
ovaries in their testes and much smaller vocal
organs.
"The use of Atrazine in
the environment is basically an uncontrolled experiment -- there seems to be no Atrazine-free
environment. Because it is so widespread, aquatic environments are at
risk. It is obviously affecting frogs. We have shown serious effects on their sexual development. Some had three ovaries and three testes, some had ovaries on one side and testes on the other, one animal even had six testes…We need to ask the questions, 'What are the environmental costs of using Atrazine? What diversity have we lost?'"
Evidently, however, hermaphroditism in frogs is a well-known phenomenon that has been monitored and studied for decades all over the world. The study claims that even at low concentrations (1/30th the dose deemed safe by
the EPA), Atrazine may cause hermaphroditism in North American frogs. It has also been shown to lower hormone and testosterone levels in sexually mature male frogs to much lower than normal female frogs. At this point, it is still unclear whether Atrazine leads to reduced fertility, but the likelihood seems to be that this would impair a frog's ability to breed and produce offspring.
The study research was done without any
industry financing provided to Dr. Hayes and his coauthors. Hayes originally had been hired as a consultant by Ecorisk (now Syngenta) in order to conduct research on Atrazine and its effects on the environment. The
results of the study were later published in April 2002 in
Proceedings of the National Academy of Science, and in
October 2002 in
Nature magazine.
"This is very important and elegant work," said Theo Colborn, Ph.D.,a senior scientist at the World Wildlife Fund. Colborn is recognized worldwide for his expertise with endocrine disrupting
chemicals. "Tyrone's work demonstrates the need to do research on the safety of chemicals in the field where the animals live and at the levels to which they are exposed. The changes he found in the gonads were not discovered with the traditional high-dose Atrazine experiments used in the past. In addition, microscopic examination of the internal organs of the frogs is required to detect the hidden effects from low-dose
exposure."
Results of the EPA investigation
Atrazine has been widely used by approximately 80 countries over the last 40 years. However, it has been recently banned in several countries, including France,
Germany, Italy, Sweden and Norway. The weed killer is still on sale in the UK, as well as in the U.S.
The EPA and its independent Scientific Advisory Panel (SAP) scrutinized this study in 2003, concluding there was not enough information or data to determine if amphibian development was affected by Atrazine. They classified this
herbicide as "not likely" to be carcinogenic in 2003, even recommending that the chemical's registration be renewed. According to the EPA, they did "not find any results among the available
studies that would lead us to conclude that a potential cancer risk is likely from exposure to Atrazine."
However, the EPA also claimed in 2003, based on Hayes' research, that there was "sufficient
evidence" to conclude there is a definite chance that Atrazine does affect amphibian reproduction and reproductive organs. The EPA was unwilling to concede --stating that these results were not consistent enough to justify a national
ban on the chemical.
In August of that year, The Natural Resources Defense Council (NRDC) brought forth a lawsuit against EPA. The council charged that the EPA had failed to protect
endangered species and the environment from the toxic effects of Atrazine. This was due to statements made by the EPA that this chemical has the potential to cause harm to endangered species, even though it was allowed to remain on the market.
In October 2007, the EPA will release their evaluation on the validity of Atrazine research and the effects this chemical has on amphibian gonadal development. These
findings will be presented to the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) Scientific Advisory Panel (SAP). These findings will include newer scientific research that was conducted in 2005/2006 by Syngenta Crop Protection, Inc. and any open literature studies that were evaluated by the EPA.
"Atrazine is just one of a long list of
pesticides thought to have hormone disrupting effects and many of these turn up in our
food as residues," said Sandra Bell, a pesticides campaigner with the Friends of the Earth environmental organization. "In fact, we've seen recent evidence that
farmers are finding that the pesticides that the bio-tech
companies sell to them to go with the GM crops are just not effective -- they're not working -- and therefore the farmers are actually resorting to older very toxic chemicals. Gender bending effects on fish and frogs raise serious concerns about the impact such chemicals are having on our wildlife, especially as the effects were found at such low levels. But even more alarming is the potential for these
products to affect human
health.
"I think it's clear that people don't want pesticides in their food but also that it's not just a simple issue of banning all pesticides overnight. Clearly that would be very difficult for our farmers and farmers in other countries. So what we need is a process of phasing out these chemicals and replacing them with safer alternatives and replacing them with different methods of
farming. For that we do need a commitment of resources from the Government and from the retailers to carry out research and development into different ways of farming, but also into safer products that don't leave residues in our food."
In addition to the work conducted by Professor Hayes, similar research conducted by Warren P. Porter of the University of Wisconsin at Madison claims that Atrazine may also disrupt other hormonal systems in amphibious creatures.
Denying the problems with Atrazine
There are still those, however, who refuse to take these findings as fact. According to Alex Avery, Director of Research and Education at the Center for Global Food Issues (CGFI), there are many other variables that could easily be responsible for and explain amphibious hermaphroditism, such as parasites, viruses, temperature and any number of other
natural factors. "Hayes's latest study is reminiscent of recent peer-reviewed studies that tried to link pesticides to frog limb abnormalities, but were debunked after further studies found natural parasitic flatworms to be the cause. Until this work has been corroborated by other labs, it must be considered preliminary and inconclusive," said Avery
Amid recent concerns about human and ecological health, environmental campaigners are calling for a ban on Atrazine. Due to the research done on this chemical by Hayes and others in the field, Atrazine now has been banned or restricted in Austria, Slovenia, Germany, Denmark, Italy, France and the UK.
The effects of Atrazine on frogs were examined prior to Hayes' work, but similar abnormalities had not been reported. This is what is primarily fueling the debate over these findings -- that Hayes and his colleagues are the only ones so far willing to state these findings as fact. So far, no other independent studies have found anything similar.
The reason, according to Hayes, is that "they were looking for the wrong things. Most people were looking for external deformities, mortality or cancer. Atrazine-induced abnormalities are subtler -- it took a year of experimentation before even we noticed the consequences." Since then, more independent and industry research has been conducted on Atrazine; many of the current conclusions are very similar to those previously made by Hayes.
Other names used by chemical companies and
pesticide manufacturers to designate the herbicide "Atrazine" include: 2-chloro-4-(2-propylamino)-6-ethylamino-s-triazine, 2-chloro-4-ethylamino-6-isopropylamino-s-triazine, 2-chloro-4-ethylamino-6-isopropylamino-s-triazine, 2-chloro-4-(isopropylamino)-6-ethylamino-s-triazine, Ortho St. Augustine Weed and Feed, 6-chloro-N-ethyl-N-isopropyl-s-triazine-2,4-diamine, A 361, AAtrex, AAtrex 4L, AAtrex 80W, AAtrex Nine-O, Actinite PK, Akticon, Aktikon, Aktikon PK, Aktinit A, Aktinit PK, Argezin, Atrazinax, Atranex, Atrasine, Atrataf, Atratol, Atratol A, Atrazine, Atrazine 4L, Atrazine 80W, Atrazines, Atred, Atrex, Attrex, ATZ, Azinotox 500, Candex, Cekuzina-T, Chromozin, Crisamina, Crisatrina, Crisazine, Crisazina, Cyazine, Extrazine II, Farmco, Fenamine, Fenatrol, Fogard, G30027, Geigy 30027, Gesaprim, Gesaprim 50, Gesaprim 500, Gesoprim, Griffex, Griffex 4L, Hungazin, Hungazin PK, Inakor, Laddock, Maizina, Mebazine, Oleogesaprim, Oleogesaprim 200, Pitezin, Primatol, Primatol A, Primaze, Radizine, Radazine, Scotts Bonus Type S, Strazine, Triazine A 1294, Vectal, Vectal SC, Vectral SC, Weedex, Weedex A, Wonuk, Zeaphos, Zeapos, and Zeazin.
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