SILENT SPRING ANALYSIS

CHAPTER 13 - Through a Narrow Window

Summary

It's necessary to look at the cells of the body in order to begin to see the effects of chemical poisons. In the 1960s, medical science had only just begun studying cells and cellular oxidation. Energy is produced not by organs but by cells. Cells transform matter into energy. The changes are made in an orderly process and each step is controlled by a specific enzyme. When energy is produced, so is waste given off. Most of the work of oxidation is performed in an even smaller arena than the cell. It is done by tiny granules within cells called Mitochondria. Mitochondria are tiny packets of enzymes, the enzymes necessary for the oxidation process.

The energy produced at each stage of oxidation within the Mitochondria is called ATP (adenosine triphosphate), a molecule containing three phosphate groups. ATP furnishes energy by transferring one of its phosphate groups to other substances. Once it has given up one of its phosphate groups, it is a diphosphate molecule, ADP. Then, in the next stage, another phosphate group is coupled on and the ATP is restored. ATP is found in all living organisms. The process in which ADP and a free phosphate group are combined to make a new ATP is coupled to the oxidative process. If the combination doesn't happen or becomes uncoupled, there is lost energy. Respiration continues, but it produces nothing.

Uncoupling occurs with radiation. It can also be caused by chemical poisoning. Many chemicals discussed in the book act as uncouplers. Uncoupling is only one of the things that can go wrong. Enzymes can be destroyed, thereby brining the process of oxidation of cells to a halt. Many chemical poisons destroy enzymes. Scientists have shown that if they withhold oxygen, normal cells will transform into cancer cells. If the human embryo is deprived of oxygen, it will develop congenital deformities. There have been a rise of congenital defects, documented since the early 1960s. Scientists are also finding diminished reproduction. It has long been established that chemical poisons are present in the eggs of animals other than human beings. While it is difficult to test human eggs, it is possible to infer that the chemical poisoning is occurring there. Scientists have found also that exposure to chemical poisoning atrophies the testes of laboratory animals. Even sperm cells are affected by a loss of ATP.

One of the most important areas of human biology is its genetic heritage. We are seeing a deterioration of genetic material. Radiation on human cells changes their chromosomal structure. Similar changes occur with chemical poisoning. Some scientists working in the early 1940s discovered that exposure to mustard gas produced permanent chromosomal abnormalities that can't be distinguished from the abnormalities produced by radiation.

The cells of the body must be able to increase in number if the body is to grow. Cells divide at the nuclear level, a process called mitosis. Each new set of cells contains a complete set of chromosomes and all the genetic information encoded in them. A special kind of mitosis happens in the formation of the germ cells. The chromosomal number of every species is constant, so when male and female combine to form a new organism, they cannot give all their chromosomes or the new organism would contain twice the normal number. Therefore, they each give one whole chromosome of each cell to the daughter cell.

This process is threatened by chemical poisons. Scientists have begun to study chromosomes and have found that there are always supposed to be only 46 chromosomes. Damage from the environment has rarely gotten the kind of attention it deserves. Some research has been done, however. Mosquitoes exposed to DDT for several generations mutated into another kind of creature. Plants suffered profound destruction of chromosomes. Mutations have occurred in all the organisms tested. Scientists have been more willing to see the mutative affects of radiation on human beings than the affects of chemical poisoning. In 1959, some scientists discovered that some human problems occur because of a disturbance of the normal number of chromosomes. For instance, they discovered that people with Down's Syndrome (to which Carson refers with the old-fashioned and now-considered derogatory term Mongoloidism) had one extra chromosome. Another syndrome is Klinefelter's syndrome, which involves the duplication of one of the sex chromosomes. people end up with, for instance, an XXY instead of an XY chromosome.

While much more research needs to be done, it is clear that chemical poisoning is threatening our genetic heritage.

Notes

Chapter 13 is one of the most challenging chapters for the non-science-oriented reader. However, the difficulty is concentrated primarily in the first few pages of the chapter. Here, Carson sets up the terms and the description of process which will serve the reader well in understanding the rest of the chapter and the book. The title of the chapter alludes to a metaphor one scientific specialist used to describe the larger vision of the body which a scientist gains from studying the most minute area of the body.