Kermit or Kermette? Case Study1. Does atrazine appear to alter male frog development at any concentration?
Yes, atrazine appears to alter the male frog development at concentrations of .01, .05, .11, .13 and .83 micrograms per tadpole. Also at .1, .4, .8, 1 and 25 micrograms per liter.
2. If atrazine does affect male frog development, what is the lowest concentration and dose that appears to have the effect?
The lowest concentration of atrazine that affects the male frog development is .01 micrograms per tadpole.
3.The chemical DDT was banned for use in the U.S. in the 1960s. For years afterwards, however, American manufacturers of DDT continued to export it to the third world countries that had not yet banned its use. How does this observation relate to the use of atrazine in the U.S. today?
Third world countries that banned atrazine are manufacturing the chemical for other countries such as the United States
1.A Syngenta press release quotes James Carr, head of the Texas Tech team, as saying, “We have been unable to reproduce the low-concentration effects of atrazine on amphibians reported elsewhere in the scientific literature.” This statement refers to Hayes’ results (Hayes,2002, 2003). Comment on the accuracy of this statement, and explain your reasoning.
Carr is right since the water Tyrone used might already have been concentrated with atrazine. This concentration might have affected Tyrone's result. That is why higher dosages sometimes had no percent of gonadal abnormalities, because the frogs might have developed a defense from being in atrazine concentrated water for too long.
2. The Hayes study (Hayes,2003) was conducted using water samples collected from ponds and streams in agricultural and non-agricultural regions of the Midwest. The study conducted by Carr’s group added varying amounts of atrazine to de-chlorinated laboratory water. Which set of experimental conditions, if either, would be more likely to lead to valid experimental results? Explain your reasoning.
The experimental conditions of Carr's group would likely lead to valid experimental results, because the water that he uses has been de-chlorinated. The water that Tyrone uses might contain other chemicals, which affects the results.
3. Comment on the significance of the Carr data, shown above, that reports the percent of male frogs having gonadal abnormalities at a nominal atrazine concentration of zero micrograms per liter and a nominal dose of zero micrograms per liter.
The percent of male frogs having gonadal abnormalities at a normal atrazine concentration of zero and a nominal dose are the same. They are the same, because it might have been a random mutation. The nominal dose might have not affected the frogs, therefore having the same percentage.
1. What do the Hayes results indicate about the effect of atrazine on the testosterone concentration in the blood of exposed male frogs?
Hayes results indicate that atrazine raised the concentration on the testosterone in the blood of exposed male frogs.
2. What do the MSU results indicate about the effect of atrazine on the testosterone concentration in the blood of exposed male frogs?
MSU results indicate that atrazine only raised the concentration of the testosterone in the blood only by .5 or lower.
3. Consider the EPA’s observation about the presence of atrazine in the controls used in the MSU study. Could this observation explain how Hayes and Hecker could both have accurately reported their experimental observations?
Yes, because the water that Hecker used contained atrazine and the water that Tyrone used had no concentration of atrazine.
4. In 2003, the EPA recommended that Syngenta’s license to continue the use of atrazine in the United States be approved. If one assumes that the data presented here are valid, what factor or combination of factors might have led to this recommendation?
There is no direct evidence that might have led to this recommendation
5. Search for two web sites that support the continued use of atrazine and two web sites opposed to its continued use. Prepare an assessment of the validity of these web sites and be prepared to share your observations in class. Useful guidelines for the evaluation of the credibility of web postings may be found at
Against Atrazine:
http://www.randylemmon.com/misc/GardenTalk_02-28-02.htm
http://www.savethefrogs.com/threats/pesticides/atrazine/index.html
For Atrazine:
http://www.atrazinelovers.com/
http://ase.tufts.edu/gdae/Pubs/rp/EconAtrazine.pdf
Yes, atrazine appears to alter the male frog development at concentrations of .01, .05, .11, .13 and .83 micrograms per tadpole. Also at .1, .4, .8, 1 and 25 micrograms per liter.
2. If atrazine does affect male frog development, what is the lowest concentration and dose that appears to have the effect?
The lowest concentration of atrazine that affects the male frog development is .01 micrograms per tadpole.
3.The chemical DDT was banned for use in the U.S. in the 1960s. For years afterwards, however, American manufacturers of DDT continued to export it to the third world countries that had not yet banned its use. How does this observation relate to the use of atrazine in the U.S. today?
Third world countries that banned atrazine are manufacturing the chemical for other countries such as the United States
1.A Syngenta press release quotes James Carr, head of the Texas Tech team, as saying, “We have been unable to reproduce the low-concentration effects of atrazine on amphibians reported elsewhere in the scientific literature.” This statement refers to Hayes’ results (Hayes,2002, 2003). Comment on the accuracy of this statement, and explain your reasoning.
Carr is right since the water Tyrone used might already have been concentrated with atrazine. This concentration might have affected Tyrone's result. That is why higher dosages sometimes had no percent of gonadal abnormalities, because the frogs might have developed a defense from being in atrazine concentrated water for too long.
2. The Hayes study (Hayes,2003) was conducted using water samples collected from ponds and streams in agricultural and non-agricultural regions of the Midwest. The study conducted by Carr’s group added varying amounts of atrazine to de-chlorinated laboratory water. Which set of experimental conditions, if either, would be more likely to lead to valid experimental results? Explain your reasoning.
The experimental conditions of Carr's group would likely lead to valid experimental results, because the water that he uses has been de-chlorinated. The water that Tyrone uses might contain other chemicals, which affects the results.
3. Comment on the significance of the Carr data, shown above, that reports the percent of male frogs having gonadal abnormalities at a nominal atrazine concentration of zero micrograms per liter and a nominal dose of zero micrograms per liter.
The percent of male frogs having gonadal abnormalities at a normal atrazine concentration of zero and a nominal dose are the same. They are the same, because it might have been a random mutation. The nominal dose might have not affected the frogs, therefore having the same percentage.
1. What do the Hayes results indicate about the effect of atrazine on the testosterone concentration in the blood of exposed male frogs?
Hayes results indicate that atrazine raised the concentration on the testosterone in the blood of exposed male frogs.
2. What do the MSU results indicate about the effect of atrazine on the testosterone concentration in the blood of exposed male frogs?
MSU results indicate that atrazine only raised the concentration of the testosterone in the blood only by .5 or lower.
3. Consider the EPA’s observation about the presence of atrazine in the controls used in the MSU study. Could this observation explain how Hayes and Hecker could both have accurately reported their experimental observations?
Yes, because the water that Hecker used contained atrazine and the water that Tyrone used had no concentration of atrazine.
4. In 2003, the EPA recommended that Syngenta’s license to continue the use of atrazine in the United States be approved. If one assumes that the data presented here are valid, what factor or combination of factors might have led to this recommendation?
There is no direct evidence that might have led to this recommendation
5. Search for two web sites that support the continued use of atrazine and two web sites opposed to its continued use. Prepare an assessment of the validity of these web sites and be prepared to share your observations in class. Useful guidelines for the evaluation of the credibility of web postings may be found at
Against Atrazine:
http://www.randylemmon.com/misc/GardenTalk_02-28-02.htm
http://www.savethefrogs.com/threats/pesticides/atrazine/index.html
For Atrazine:
http://www.atrazinelovers.com/
http://ase.tufts.edu/gdae/Pubs/rp/EconAtrazine.pdf
