Stories tagged atrazine

Feb
23
2011

We've written about freaky frogs on the Buzz Blog before, but some recent news may shed new light on our abnormal amphibians. Until recently, researchers thought that atrazine, an agricultural pesticide, was the sole cause of sexual deformities in frogs. Unfortunately, it's not so simple.
UT OH: What lurks in me waters?
UT OH: What lurks in me waters?Courtesy Mike Ostrowski

An ecologist at Yale University, David Skelly, sought to test assumptions about atrazine by studying the frequencies of frog deformity in different land types--agricultural, suburban, urban, and forested. Skelly expected to find the highest rates of deformities in agricultural areas, which would be consistent with atrazine being the main cause. Curiously, he found the highest rates of deformity in urban and suburban areas--places we wouldn't expect to find much atrazine. So what's going on?

It turns out that what makes atrazine so dangerous is that it mimics estrogen and binds to estrogen receptors in frog cells. Because estrogen impacts sexual development and function, so too does atrazine. But atrazine isn't the only estrogen-mimicking compound out there--there's a whole class of chemicals that mimic estrogens, including those found in birth control pills and plastics (BPA). And these chemicals are found in droves in cities and surburban areas--they're flushed into the sewage, but aren't filtered out during water treatment.
Birth control pills: Estradiol, a synthetic estrogen, helps prevent pregnancy in women. But much of it is excreted in urine and eventually makes its way into various water sources.
Birth control pills: Estradiol, a synthetic estrogen, helps prevent pregnancy in women. But much of it is excreted in urine and eventually makes its way into various water sources.Courtesy Ceridwen

So why do we care? Besides the fact that frogs are just awesome little creatures and important parts of their food webs, they have something in common with humans--estrogen receptors. The same chemicals that impact frogs can impact us. So how do we humans keep our sexual development and functioning intact?
BPA-free: This Sigg bottle is made from enameled aluminum, and it's an example of a BPA-free bottle.
BPA-free: This Sigg bottle is made from enameled aluminum, and it's an example of a BPA-free bottle.Courtesy Bucklesman

Skelly had a great idea to filter this stuff out of the water at the treatment plant, so that it won't get into our bodies from drinking water. He also suggested that regulatory changes would help so that when new chemicals are developed, they're scrutinized for unintended side effects. And of course, we can make choices that reduce our exposure, such as by buying BPA-free plastics, or using stainless steel and glass containers. And of course, increased awareness is always a good idea.

Do you take extra steps to avoid things like BPA? What are they?

Dec
14
2008

Note: original title using the term fertilizer was corrected to read atrazine
Leopard frog
Leopard frogCourtesy Heather Dietz

What is happening to our frogs?

A recent study showed that atrazine in pond water could lead to a higher population of snails, which harbor parasites that also infect frogs. For the study, Lucinda Johnson and her colleagues at UMD collected leopard frogs from 18 wetlands near St. Cloud, Minnesota. The researchers found a positive correlation between the amount of atrazine in a wetland and the number of parasites in that wetland's frogs. The parasite in question is a tiny worm called a trematode. They can have a negative effect on frog populations.

How atrazine effects frogs

More fertilizer = more pond scum (periphyton)
More periphyton (snail food) = more snails
More snails = more snail parasites (trematodes)
More trematodes = more trematode larva attacking tadpoles
Larva infested tadpoles and frogs have lower survival rates when atrazine is present

The trematode worm that infects the frogs gets passed to frog-eating birds like herons and egrets. Inside the birds, the worms develop to adulthood. The adults produce eggs that are released into water with the birds' feces. The eggs hatch, develop into larvae, and burrow into snails. After further development, they burrow their way out again and swim in search of tadpoles. They infect them, the tadpoles turn into frogs, and the cycle continues.

Learn more about atrazine and frogs

Source articleUMNews: The tadpoles tale .
Article in Nature: Agrochemicals increase trematode infections in a declining amphibian species