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Thread: Atrazine and the Ecosystem

  1. #1

    Default Atrazine and the Ecosystem

    TED Speakers: Tyrone Hayes + Penelope Jagessar Chafer: The toxic baby?

    Pesticide Atrazine Can Turn Male Frogs Into Females

    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 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.
    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. Atrazine induces complete feminization and chemical castration in male African clawed frogs (Xenopus laevis)

    Study's Abstract:
    The herbicide atrazine is one of the most commonly applied pesticides in the world. As a result, atrazine is the most commonly detected pesticide contaminant of ground, surface, and drinking water. Atrazine is also a potent endocrine disruptor that is active at low, ecologically relevant concentrations. Previous studies showed that atrazine adversely affects amphibian larval development. The present study demonstrates the reproductive consequences of atrazine exposure in adult amphibians. Atrazine-exposed males were both demasculinized (chemically castrated) and completely feminized as adults. Ten percent of the exposed genetic males developed into functional females that copulated with unexposed males and produced viable eggs. Atrazine-exposed males suffered from depressed testosterone, decreased breeding gland size, demasculinized/feminized laryngeal development, suppressed mating behavior, reduced spermatogenesis, and decreased fertility. These data are consistent with effects of atrazine observed in other vertebrate classes. The present findings exemplify the role that atrazine and other endocrine-disrupting pesticides likely play in global amphibian declines.
    I've also seen many related articles on CCD that mention atrazine as a suspected cause of shrinking bee populations.

    So is the scientific jury still out on the harmful effects of atrazine? Or is the verdict in, but the political jury is still out to lunch because it will effect the agricultural industry and their voter turnout? I haven't heard about this enough to understand why this is still being widely used in light of all of this scientific research.
    "There is no god; there is only us. Savage and fragile."

  2. #2
    Senior Member Array Lateralus's Avatar
    Join Date
    May 2007


    1. The average person doesn't understand how this can have an indirect, long-term impact on their lives.
    2. Corporations don't care about anything but profit. It's cheaper to lobby against change, and this is viewed as something they can get others to pay for.
    "We grow up thinking that beliefs are something to be proud of, but they're really nothing but opinions one refuses to reconsider. Beliefs are easy. The stronger your beliefs are, the less open you are to growth and wisdom, because "strength of belief" is only the intensity with which you resist questioning yourself. As soon as you are proud of a belief, as soon as you think it adds something to who you are, then you've made it a part of your ego."

  3. #3
    insert random title here Array Randomnity's Avatar
    Join Date
    May 2007
    6w5 sp/sx


    I knew someone IRL who was working on this for her grad studies a few years back. From what I understood there is controversy because some studies show an effect on frogs/wildlife but other studies don't; significantly, many/most/all? of the studies that show no harmful effect were funded directly by the company or companies involved. So there's some suspicion about whether those studies are truly legit or not. My info is at least 4 years out of date though. Not sure what's changed since then. The info about frogs in the OP has been known for at least several years though (unfortunately).

    edit: LOTS of other chemicals can have similar effects, too. I did my undergrad research project with frogs and endocrine disrupting chemicals. It's kinda scary how tiny levels of chemicals can have dramatic effects on development and reproduction.
    -end of thread-

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