In March of 2010, the results of a three yearlong study was released online in the peer-reviewed American journal, PNAS (Proceedings of the National Academy of Sciences). The article, Atrazine induces complete feminization and chemical castration in male African clawed frogs, reviewed the results of a study on the effects that a popular pesticide, atrazine, had on the reproductive systems of mature male African clawed frogs. This study was conducted using concentrations of atrazine well below the standards for safe drinking water set by both Health Canada (5.Oppb) (Mittelstaedt 2010) and the US Environmental Protection Agency (3.0ppb) (Hayes et al. 2010). The frog larvae were reared in an atrazine ethanol solution (2.5ppb) from hatching, through metamorphosis and throughout their adult life until the study was completed (Hayes et al. 2010). As suggested by the title of the article many of these frogs suffered a chemically induced sex change as a result of the pesticide. Shortly after these findings were published in the PNAS journal, a writer, Martin Mittelstaedt, published a review in The Globe and Mail called Weed killer can turn male frogs into females, study finds. The following will serve as an insight into the variances between the two articles, paying particular attention to how each author uses considerable detail to emphasize what they believe are crucial components in the study. And what the authors believe are the limitations on inferences that can be taken from the results.
One of the first noted differences was the stress Hayes put on the role of atrazine in North America and the potential dangers it poses. Mittelstaedt’s article merely states that atrazine is a “weed killer widely used on corn fields in Canada” (Mittelstaedt 2010) this does not provide enough background for the reader to make an assumption as to the populations this chemical is effecting. Whereas, Hayes expresses in detail the mass scale of the population that is being effected stating that it is the most common pesticide contaminant of ground and surface water (Hayes et al. 2010). He goes on to explain that it is especially dangerous because of its ability to be transported thousands of kilometers away from its source by rainclouds. Clouds which annually precipitate more then half a million pounds of chemical in the United States alone (Hayes et al. 2010). By providing numerical data Hayes is able to strongly stress, in reality, just how widespread this chemical, as well as its harmful effects, are. Thus providing the reader with enough information to grasp the true extent of the potential problems.
Similarly, Mittelsaedt’s article lacks crucial details about the findings of the study, he merely states that atrazine induces sex changes in frogs (Mittelsaedt 2010) when in fact, the pesticide had a very wide variety of harmful effects. The primary article includes details of these effects and how they may effect the natural frog population in the future. Firstly, (Hayes et al. 2010) state that sperm counts and fertility rates were significantly reduced by the chemical. Secondly, that the atrazine-exposed frogs were unable to compete for amplexus with the unexposed frogs because of decreased testosterone levels and an apparent inability to identify the female attractant hormone (Hayes et al. 2010). Shown in the diagrams below, which were included in Hayes’ article, is a visual representation of these conclusions. It can also be seen that the frogs' body weights had no effect on the frogs’ abilities to complete amplexus. Where Mittelstaedt’s article does not seem to draw any conclusions from the findings; Hayes’ article strongly stresses the potentially devastating effects that will occur if a population is unable to reproduce properly. He claims that all of these factors will have a direct impact on exposed populations (Hayes at al. 2010). The awareness he offers to the reader plays a crucial role in solidifying the implications of his findings in the readers mind. Whereas Mittelstaedt’s article goes no further than presenting a simple result.
Between the two articles there are more limitations presented in Mittelstaedt’s article. It was stated on more than one occasion that many researchers were skeptical of the findings until the effects were confirmed by other scientists (Mittelstaedts 2010). Alternatively the original article argued that not only were these findings legitimate but that they could be produced in other species as well. Hayes’ article cites other studies, which have found that atrazine feminizes zebra fish and leopard frogs and attributes to low sperm count and poor semen quality in humans (Hayes et al. 2010). The article goes so far as to state that this is not a species-specific effect but rather one that occurs across nonamniote vertebrate classes (Hayes et al. 2010). This suggests that these results can be used to create adverse hypotheses concerning the effect of the pesticide on a number of different species, as opposed to the single species, African clawed frogs, that Mittelstaedt’s article references.
It is evident in both the articles that the results of this study have no doubt sparked concern about what we previously considered safe levels of atrazine in our environment. Hayes’ and Mittelstaedt’s articles do a good job to inform us of the devastating effects this pesticide has on the reproductive systems of African clawed frogs. However, the results of any study are perhaps futile unless the public is willing to act upon them. By using increased detail and removing the limitations on which species these findings can apply to; Hayes’ is able to go much further to convince us of the seriousness of his findings. This provides us with a fundamental difference between the two articles; Mittelstaedt intends to simply report whereas Hayes intends to convince his audience.
Works Cited
Hayes, B Tyrone. “Atrazine induces complete feminization and chemical castration in male African clawed frogs.” Proceedings of the National Academy of Sciences 107.10 (2010): 5. http://www.pnas.org/content/107/10/4612.full
Mittelstaed, Martin. “Weed killer can turn male frogs into females, study finds.” The Globe and Mail 2010 1-March: 2. http://www.theglobeandmail.com/news/technology/science/weed-killer-can-turn-male-frogs-into-females-study-finds/article1485580/
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