Free Study Guide for Silent Spring by Rachel Carson - Book Summary
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STUDY GUIDE FOR SILENT SPRING BY RACHEL CARSON
What are the results of the poisoning of waters set-aside for refuges? Duck hunters will no longer find so many ducks. No one will be able to enjoy the sight of waterfowl flying overhead. These refuges are extremely important strategically for the life of birds. They are resting places for three fourths of all waterfowl that move south in the Pacific Coastal states in the autumn.
Poisoned water also effects the chains of life. Life moves from the smallest life up through larger organisms until it reaches human beings. The best example of this process is the case of Clear Lake, California. It is a lake that is used by people who love to fish and by other resort dwellers. There was one problem with the lake. There was a small gnat that lived there and bothered people by its sheer numbers. The authorities used chlorinated hydrocarbon insecticides to kill the gnats. The particular chemical was called DDD, a relative of DDT. At first the gnats were brought under control, but soon their numbers increased. So the authorities increased the dosage of pesticides. The next winter, a favorite bird of the lake, the western grebe, began to die by the hundreds. Even so, the authorities put even more pesticides into the water to kill the gnats and predictably, more grebes died. Finally, someone examined the fatty tissue of the birds and found extraordinarily high levels of DDD, much higher than was ever put into the water. The reason for the increased level is that the birds eat the fish. Researchers realized that the chemical was picked up by the smallest life form, concentrated, and then passed on the next life form until its concentrations reached the phenomenal levels found in the birds.
The case of Clear Lake taught scientists other valuable lessons about the spread of chemical pesticides. Just after the chemical was dumped into the lake, water tests couldnít pick it up. The reason was not that the chemical had disappeared, but that it had gone into "the fabric of life the lake supports." Even after 23 months, the plankton of the lake still had the chemical in it. All the birds, fish, and frogs examined also had the chemical in them. The nesting colonies of grebes dwindled from more than 100 pairs before the first poisoning to only 30 pairs years after the last poisoning. The California Department of Public Health declared that there was no problem, but nevertheless, it ceased the use of DDD on the lake. Itís useful to realize what DDD does to a body. It destroys part of the adrenal gland, the part called the adrenal cortex which produces cortin. They found that the effect of DDD on dogs was very similar to that occurring in Addisonís disease in humans. Later they found that DDD does affect the human adrenal cortex.
The problems at Clear Lake teach many important lessons. Yet, the poisons are still being dumped into reservoirs. Often authorities want to support recreational use. Fishermen want one kind of fish and so they ask authorities to kill the less desirable fish in a reservoir. The public rarely learns of this solution and doesnít realize itís paying for the later purification of the same water. The use of pesticides in water also produces cancer-causing affects. Cities that receive their drinking supply from contaminated rivers have a higher death rate from cancer.
Carson begins a systematic treatment of all the areas of earthly life that are affected by pesticides. She begins here with the water, what she calls our greatest natural resource. In the previous chapter, she provided a knowledge of the kinds of chemicals being used and how they function. Here, her purpose is to show the widespread use of pesticides and the effects of that use on the environment. Carson is skilled at using a variety of means of persuasion. If the reader doesnít care about the graceful and beautiful birds that are being killed en mass, perhaps the reader will care about the fish that she or he takes home to eat after a day of fishing. She describes the path of a chemical from the tiniest microorganism that has been contaminated to the person who eats the fish freshly killed. She describes the efforts to control agencies to discover the causes of the deaths and mutations, thus making the reader see the difficulties of cleaning up after a mass infusion of poisons into the environment.
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. 09 May 2017