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Kermit or Kermette
CHEM 121 - Group 7
Group Members: Daniel Salas,
Nathan Dowling,
Sashni-Cole Matthews
Lashae Williams
It's Not Easy Being Green
Does the atrazine appear to alter male frog development at any concentration?
According the results of the study conducted by Hayes it would appear that the atrazine did appear to alter the male frog development at the 0.1, 0.4, 0.8, 1, and 25 micrograms per liter concentration levels. These results are very similar to the results found for the micrograms per tadpole dose levels, where there are abnormalities at the 0.01, 0.05, 0.11, 0.13, and 0.83 micrograms per tadpole doses. It does not seem likely that the changes in abnormalities were more or less frequent with the increase in the concentration level, however. There was, in fact, no abnormalities in the frogs in the 0.06, 0.6, and 1.5 micrograms per tadpole doses or the 10 micrograms per liter concentrations level. This might lead one to conclude that the results are slightly inconclusive. Without cause and effect across the board, it seems hard to infer that the atrazine has a direct connection to the abnormalities presented by the frogs.
If atrazine does affect male frog development, what is the lowest concentration and dose that appears to have the effect?
The lowest dose that appears to have an effect on the tadpoles is the sample of 0.01 microgram per tadpole dose. The lowest concentration which appears to have an effect is the 0.1 microgram per liter concentration level.
The chemical DDT was banned for use in the U.S. in the 1960s. For years afterward, however, American manufacturers of DDT continued to export it to 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?
The use, production, and sale of atrazine, like DDT, are not covered by the same laws. This is what makes it possible for the Syngenta Corporation to produce and sell atrazine to other countries even though its home country of Switzerland banned its use. In order for any environmental agency to truly effect the use of a product that potentially harms the planet, laws need to be created that would ban not only the use, but also the production and sale of the chemical.
A Different Approach
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.
The Syngenta Corporation was not pleased with the original findings of Hayes' experiments. Carr being unable to "reproduce the low-concentration effects of atrazine on amphibians" could point to the corporation discrediting Hayes and his work. However, analysis of the two experiments shows that there were many factors that contributed to Carr's inability to reah the same conclusion. Without the exact situational and experimental factors of the first experiment, future studies would be unable to achieve the original results. Things such as temperature, chemical makeup of the water, and food sources could all have played a role in how these scientists came to the results they did. In Carr's experiment, choosing to use a controlled laboratory environment changes the effects and roles of the atrazine and water. nherefore these experiments were not conducted in the same manner and ultimately could not have ever reached the same results.
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 dechlorinated laboratory water. Which set of experimental conditions, if either, would be more likely to lead to valid experimental results? Explain your reasoning.
Conducting the study in water samples collected from ponds and streams in agricultural and non-agricultural regions, as Hayes did, would be more likely to lead to valid experimental results. The collected water serves to imitate the natural habitat frogs are in when they are affected by atrazine. Some may argue that the water in this study may already have trace amounts of atrazine present. However, as we later learn, Hayes' control grup was found to have no atrazine while the de-chlorinated water in the control group from Carr's study did have atrazine in it. The results from the de-chlorinated water would only serve to show what effect atrazine in a controlled environment. With no natural environmental reactions this would not be an acurrate measure of the effects of atrazine on the frogs.
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 number of abnormalities in the frogs at the zero micrograms per liter level and nominal dose of zero micrograms per liter are both the same as the abnormalities presented at the .01 micrograms per tadpole and .1 micrograms per liter level. This indicates that either the water was contaminated with atrazine at the zero levels before the frogs were introduced to the water or that the frogs were experiencing a normal mutational abnormality at all of these levels and were completely unaffected by these levels of atrazine exposure.
Dinan, F. J. (2006). Kermit to kermette? Does the herbicide
atrazine feminize male frogs? National Center for Case Study Teaching in Science, 1-8. Retrieved from https://learn.umuc.edu/content/enforced/170104-001490-01-2168-OL1-6380/kermit.pdf?_&d2lSessionVal=nHHlCJTWSNONkhvHoP99Npz3z