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Pesticide atrazine can turn male frogs into females

March 1, 2010
University of California - Berkeley
The herbicide atrazine, one of the world's most widely used pesticides, wreaks havoc with the sex lives of adult male frogs, emasculating three-quarters of them and turning one in 10 into females, according to a new study. These changes occur at atrazine levels below what the EPA considers safe for drinking water. The changes skew sex ratios in the frog population and could be a major cause of amphibian decline worldwide.
An atrazine-induced female frog (a genetic male) is shown (bottom) copulating with an unexposed male sibling. This union produced viable eggs and larvae that survived to metamorphosis and adulthood. Yet, because both animals were genetic males, the offspring were all males.
Credit: Tyrone Hayes photo

Atrazine, one of the world's most widely used pesticides, wreaks havoc with the sex lives of adult male frogs, emasculating three-quarters of them and turning one in 10 into females, according to a new study by University of California, Berkeley, biologists.


The 75 percent that are chemically castrated are essentially "dead" because of their inability to reproduce in the wild, reports UC Berkeley's Tyrone B. Hayes, professor of integrative biology.

"These male frogs are missing testosterone and all the things that testosterone controls, including sperm. So their fertility is as low as 10 percent in some cases, and that is only if we isolate those animals and pair them with females," he said. "In an environment where they are competing with unexposed animals, they have zero chance of reproducing."

The 10 percent or more that turn from males into females ‑ something not known to occur under natural conditions in amphibians ‑ can successfully mate with male frogs but, because they are genetically male, all their offspring are male.

"When we grow these guys up, depending on the family, we will get anywhere from 10 to 50 percent females," Hayes said. "In a population, the genetically male females can decrease or wipe out a population just because they skew sex ratios so badly."

Though the experiments were performed on a common laboratory frog, the African clawed frog (Xenopus laevis), field studies indicate that atrazine, a potent endocrine disruptor, similarly affects frogs in the wild, and could possibly be one of the causes of amphibian declines around the globe, Hayes said.

Hayes and his UC Berkeley colleagues report their results in this week's online early edition of the journal Proceedings of the National Academy of Sciences. Last week, Hayes and colleagues published a review of pesticide's effects on amphibians in theJournal of Experimental Biology, concluding that atrazine is a likely contributor to worldwide amphibian declines.

"These kinds of problems, like sex-reversing animals skewing sex ratios, are much more dangerous than any chemical that would kill off a population of frogs," he said. "In exposed populations, it looks like there are frogs breeding but, in fact, the population is being very slowly degraded by the introduction of these altered animals."

Some 80 million pounds of the herbicide atrazine are applied annually in the United States on corn and sorghum to control weeds and increase crop yield, but such widespread use also makes atrazine the most common pesticide contaminant of ground and surface water, according to various studies.

More and more research, however, is showing that atrazine interferes with endocrine hormones, such as estrogen and testosterone -- in fish, amphibians, birds, reptiles, laboratory rodents and even human cell lines at levels of parts per billion. Recent studies also found a possible link between human birth defects and low birth weight and atrazine exposure in the womb.

As a result of these studies, the Environmental Protection Agency (EPA) is reviewing its regulations on use of the pesticide. Several states are considering banning atrazine, and six class action lawsuits have been filed seeking to eliminate its use. The European Union already bars the use of atrazine.

Hayes's studies in the early 2000s were the first to show that the hormonal effects of atrazine disrupt sexual development in amphibians. Working with the African clawed frog, Hayes and his colleagues showed in 2002 that tadpoles raised in atrazine-contaminated water become hermaphrodites -- they develop both female (ovaries) and male (testes) gonads. This occurred at atrazine levels as low as 0.1 parts per billion (ppb), 30 times lower than levels allowed in drinking water by the EPA (3 ppb).

Subsequent studies showed that native leopard frogs (Rana pipiens) collected from atrazine-contaminated streams in the Midwest, including from areas up to 1,000 miles from where atrazine is applied, often had eggs in their testes. And many males had lower testosterone levels than normal females and smaller than normal voice boxes, presumably limiting their ability to call mates.

Hayes' research also established that many frogs in Midwestern streams contaminated by atrazine and other pesticides have compromised immune systems, leading to increased mortality from bacterial disease.

Those early studies were hampered by the inability to easily distinguish genetically male from genetically female frogs. Male frogs have two identical sex chromosomes (ZZ) while females have both a Z and a W -- the opposite of XX female and XY male humans. But because all frog chromosomes look the same under a light microscope, it's not simple to distinguish male from female.

To overcome this, Hayes' colleague Roger Liu developed a line of all-male frogs so that the genetics would be unequivocal.

"Before, we knew we got fewer males than we should have, and we got hermaphrodites. Now, we have clearly shown that many of these animals are sex-reversed males," Hayes said. "We have animals that are females, in the sense that they behave like females: They have estrogen, lay eggs, they mate with other males. Atrazine has caused a hormonal imbalance that has made them develop into the wrong sex, in terms of their genetic constitution."

Coincidentally, another lab in 2008 discovered a sex-linked genetic marker in Xenopus, which has allowed Hayes to confirm the genetic sex of his frogs.

In Hayes' study, where 40 frogs lived for about three years after hatching in water with 2.5 ppb atrazine, about 10 percent of the frogs appeared to be resistant to the effects of the pesticide. In ongoing studies, Hayes is investigating whether this apparent resistance is inherited, as well as whether the sex-reversed males have more susceptible offspring.

Syngenta, which manufactures atrazine, disputes many of these studies, including Hayes', that show adverse effects of the presticide. But Hayes said that "when you have studies all over the world showing problems with atrazine in every vertebrate that has been looked at -- fish, frogs, reptiles, birds, mammals -- all of them can't be wrong."

"What people have to realize is that, just as with taking pharmaceuticals, they have to decide whether the benefits outweigh the costs," he said. "Not every frog or every human will be affected by atrazine, but do you want to take a chance, what with all the other things that we know atrazine does, not just to humans but to rodents and frogs and fish?"

Hayes' long-term studies of the effects of atrazine on frogs have been assisted by many UC Berkeley undergraduate students, including co-authors on the current paper: Vicky Khoury, Anne Narayan, Mariam Nazir, Andrew Park, Lillian Adame, Elton Chan, and graduate students Travis Brown, Daniel Buchholz, Sherrie Gallipeau and Theresa Stueve.

The work was funded by the Park Water Co., Mitch Kapor, Freada Klein, the Mitch Kapor Foundation, the David Foundation, the Cornell-Douglas Foundation, the Wallace Foundation, the UC Berkeley Class of '43 endowed chair and the Howard Hughes Biology Fellows Program.


Story Source:

The above story is based on materials provided by University of California - BerkeleyNote: Materials may be edited for content and length.

Journal References:

  1. Tyrone B. Hayes, Vicky Khoury, Anne Narayan, Mariam Nazir, Andrew Park, Travis Brown, Lillian Adame, Elton Chan, Daniel Buchholz, Theresa Stueve, and Sherrie Gallipeau. Atrazine induces complete feminization and chemical castration in male African clawed frogs (Xenopus laevis)PNAS, March 1, 2010 DOI: 10.1073/pnas.0909519107
  2. Hayes et al. The cause of global amphibian declines: a developmental endocrinologist's perspectiveJournal of Experimental Biology, 2010; 213 (6): 921 DOI: 10.1242/jeb.040865









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Nothin' to worry about.  The pale geniuses of life just being pale geniuses.  One day, fornication will just be something alive things used to do before they all just dropped the fuck dead!!!!!


White people do you ever just go to damn sleep??  Try it please, so the rest of can get a few seconds peace.  Sleep cures wrinkles, frowns, creases and age spots; might even keep ya from losing ya hair.  Again, Rest your demented mind, Please!!!!!!


There’s a much bigger issue here:

Humans (peasants, citizens, slaves & servants) are factory-farmed.


Before getting to that, all berries, for one example only, in the US are sprayed with extremely poisonouspesticides. Once you, as a conditioned factory farm animal,  have the knowledge, you have to be (and everyone is) like a lab-conditioned animal, to eat that poison. We are conditioned like that.


Same example, when Kellogg’s wants some strawberries or other berries for their GMO crap shit, no fooling, sugar cereals, they sent that out to bid and buy mega-pesticide dried berries from South America, worse than the US.  


Genocidal fast food, and even Presidents Obama and Clinton have eaten that garbage, uses prepped chicken, etc. sent to China and then sent back to the US for factory-farmed US slave-citizens to eat. China’s  standards are much lower than the US.  People in China are even alarmed about poisonous fast food chains like McDonald’s, KFC, Papa John’s etc.:

Poisoned meat from China has shown up in fast food in the US but you barely hear about it.  It’s so bad that  Dr. Mohamet Oz touched on the general problem

and you can find it in the news but . . .

Governments do not care what factory-farmed (Matrix) humans  eat.  We have legalized bribery (lobbying) for “elected representatives” to ignore  health.   It is more important to the “government” for companies to make a profit  and sell toxic, GMO-tainted, experimental food not fit for living beings than to provide healthy food for children. That tells you everything.


We sow what we reap. It is  illegal to takes photos of  nightmare hell-camp factory cattle farms in several states. Human beings are likewise factory-farmed and milked for their energy and money by the machine. This is the ignored reality


You can eat organic foods. Even if it means eating cutting back and eating meat once a week and replacing it with good grains, vegetables and so on. If you look at yourself, and this applies to everyone, none excepted, how hard is it to stop eating shit food? Right! We are conditioned to eat shit and we’re “lovin’ it”.  We eat shit food just like hell-camp farm animals do. It’s taken me years and years to mainly pull out of the crap food eating trough.


This puts new meaning into the phrase: EAT SHIT!

Eating well is a political act. No shit.

SCIENCE viewed in a vacuum is noble that works to make the World better in every aspect of life. BUT in the hands of corporations, Science has ONE function, MAXIMIZE CORPORATE PROFITS. If those profits can be maximized without offering any benefit to the consumer, that's perfectly fine.


If the product actually HARMS people or the environment, it's hard to prove, those companies have lawyers, PR people, lobbyists and bought politicians like all other big corporation do, lie, cheat, steal and kill to protect their profits. Corporations like any other for-profit company does pours money into marketing and to control the government that might force them to take their products off the market.


This isn't limited to the food industry:



Remember MTBE in the gasoline the run off from the streets were mass killing the fish!

Cigarettes killing millions but it so profitable its protected with billions of dollars.

BPA in plastics creates estrogen and it linked to all kinds of hormonal related problems in humans especially in men

Lead in paint it took a tremendous effort to remove lead from paint from being used on homes and anything that come in contact with humans particularly children. Cosmos with Dr Neil deGrasse Tyson had a episode on lead a scientist name Patterson had to go through all kinds of effort to get lead removed from paint and gasoline ect.. But lead poisoning has been known for 1000s of years in Rome only slaves handled lead,


Hexovalent chromium in ground water manufacturing steel, paints, leather tanning, ect causes cancer. The list is endless the products that have been protected that harm us. 


How about Hydraulic fracturing, or FRACKING, its being protected by law if someone tries to find out what is in fracking fluid its against the law and in some states its against the law to file lawsuits to ban fracking!!!! 


All kinds of harmful and dangerous products corporations tried to PROTECT through their PR, lawyers and lobby efforts to the government to preserve their PROFITS and to ensure their PROFITS rather than acknowledging the truth and doing right in regards those products were harming people and the environment.


Its a TRADITION in America of big corporations lobbying to protect their profits over quality of life or life itself.

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