PNAS - 2.5 ppb Atrazine Causes Frogs To Change From Male To Female; Can Then Lay Viable Eggs

[hatrack]

A new study has found that male frogs exposed to the herbicide atrazine -- one of the most common man-made chemicals found in U.S. waters -- can make a startling developmental U-turn, becoming so completely female that they can mate and lay viable eggs.

The study, published online Monday in the Proceedings of the National Academy of Sciences, seems likely to add to the attention focused on a weedkiller that is widely used on cornfields. The Environmental Protection Agency, which re-approved the use of atrazine in 2006, has already begun a new evaluation of its potential health effects.

Its manufacturer, Swiss agri-business giant Syngenta, says research has proven that the chemical is safe for animals and for people, who could be exposed to trace amounts in drinking water. But in recent years, a series of scientific studies have seemed to show atrazine interfering with the hormone systems that guide development in fish, birds, rats and frogs. In many cases, the result has been "feminized" males, with behaviors or body parts more like those of females.

The new study, led by Tyrone Hayes, a professor at the University of California at Berkeley, appeared to show an even more drastic transformation: Some male frogs became female, in everything but their genes. Hayes's study examined a group of 40 African clawed frogs, all of which carried male chromosomes. When they were tadpoles, he put them in water tainted with 2.5 parts per billion of atrazine -- still within the EPA's drinking water standards.

EDIT

http://www.washingtonpost.com/wp-dyn/content/article/2010/03/01/AR2010030102331.html?hpid=topnews

[hedgehog]

1. What about this?

Chronic Exposure to the Herbicide, Atrazine, Causes Mitochondrial Dysfunction and Insulin Resistance

There is an apparent overlap between areas in the USA where the herbicide, atrazine (ATZ), is heavily used and obesity-prevalence maps of people with a BMI over 30. Given that herbicides act on photosystem II of the thylakoid membrane of chloroplasts, which have a functional structure similar to mitochondria, we investigated whether chronic exposure to low concentrations of ATZ might cause obesity or insulin resistance by damaging mitochondrial function. Sprague-Dawley rats (n = 48) were treated for 5 months with low concentrations (30 or 300 µg kg−1 day−1) of ATZ provided in drinking water. One group of animals was fed a regular diet for the entire period, and another group of animals was fed a high-fat diet (40% fat) for 2 months after 3 months of regular diet. Various parameters of insulin resistance were measured. Morphology and functional activities of mitochondria were evaluated in tissues of ATZ-exposed animals and in isolated mitochondria. Chronic administration of ATZ decreased basal metabolic rate, and increased body weight, intra-abdominal fat and insulin resistance without changing food intake or physical activity level. A high-fat diet further exacerbated insulin resistance and obesity. Mitochondria in skeletal muscle and liver of ATZ-treated rats were swollen with disrupted cristae. ATZ blocked the activities of oxidative phosphorylation complexes I and III, resulting in decreased oxygen consumption. It also suppressed the insulin-mediated phosphorylation of Akt. These results suggest that long-term exposure to the herbicide ATZ might contribute to the development of insulin resistance and obesity, particularly where a high-fat diet is prevalent.





http://www.plosone.org/article/info:doi%2F10.1371%2Fjournal.pone.0005186

[rapturedbyrobots]

2. that sounds like a terrible outcome

holy crap. and people are insistent that its only because people drink too much coke.

[hedgehog]

3. It may be the combo - that the atrazine amplifies the effect of the poor diet.

Of course, guess what atazine is used to grow: corn.

[DCKit]

5. Even better, it's readily picked up in the transpiration and evaporation of moisture.

Just because you don't live in an area where it's used doesn't mean you're not being exposed to it.

[FSogol]

4. It is time to see what effect atrazine has on Sen. Jim Bunning.

just saying. :shrug:

[applegrove]

6. But the eggs that hatch hatch on little male tadpoles.

[pscot]

7. So a few drops of this stuff turns one into

a fat, diabetic homosexual? Wait 'til the religious right gets the news.