ALL THINGS NUCLEAR & RADIO-ACTIVE

http://rachels-carson-of-today.blogspot.co.nz/2009/11/silent-spring-rachel-carson-1962.html

THROUGH A NARROW WINDOW (chapter thirteen)

For mankind as a whole, a possession infinitely more valuable than individual life is our genetic heritage, our link with past and future. Shaped through long aeons of evolution, our genes not only make us what we are, but hold in their minute beings the future – be it one of promise or threat. Yet genetic deterioration through man-made agents is the menace of our time, ‘the last and greatest danger to our civilization.’

Again, the parallel between chemicals and radiation is exact and inescapable.

The living cell assaulted by radiation suffers a variety of injuries: its ability to divide normally may be destroyed, it may suffer changes in chromosomal structure, or the genes, carriers of hereditary material, may undergo those sudden changes known as mutations, which cause them to produce new characteristics in succeeding generations. If especially susceptible the cell may be killed outright, or finally, after the passage of time measured in years, it may become malignant.

All these consequences of radiation have been duplicated in laboratory studies by a large group of chemicals known as radio-mimetic or mutation-imitating. Many chemicals used in pesticides – herbicides as well as insecticides – belong to this group of substances that have the ability to damage the chromosomes, interfere with normal cell division, or cause mutations. These injuries ot the genetic material are of a kind that may lead to disease in the individual exposed or they may make their effects felt in future generations.

Only a few decades ago, no one knew these effects of either radiation or chemicals. In those days the atom had not been split and few of the chemicals that were to duplicate radiation has as yet been conceived in the test tubes of chemists. Then in 1927, a professor of zoology in a Texas university, Dr. H. J. Muller, found that by exposing an organism to x-radiation, he could produce mutations in succeeding generations. With Muller’s discovery a vast new field of scientific and medical knowledge was opened up. Muller later received the Nobel Prize in Medicine for his achievement, and in a world that soon gained familiarity with the grey rains of fall-out, even the non-scientist now knows the potential results of radiation.

Although far less noticed, a companion discovery was made by Charlotte Auerbach and William Robson at the University of Edinburgh in the early 1940’s. Working with mustard gas, they found that this chemical produced permanent chromosome abnormalities that cannot be distinguished from those induced by radiation. Tested on the fruit fly, the same organism that Muller had used in his original work with X-rays, mustard gas also produced mutations. Thus the first chemical mutagen was discovered.

Mustard gas as a mutagen has now been joined by a long list of other chemicals known to alter genetic material in plants and animals…

Dr. Peter Alexander, an outstanding British authority, has said that the radio-mimetic chemicals ‘may well represent a greater danger’ than radiation. Dr. Muller, with the perspective gained by decades of distinguished work in genetics, warns that various chemicals (including groups represented by pesticides)…can raise the mutation frequency as much as radiation…As yet far too little known of the extent to which our genes, under modern conditions of exposures to unusual chemicals, are being subjected to such mutagenic influences.

ONE IN EVERY FOUR (chapter fourteen)

The battle of living things against cancer began so long ago that its origin is lost in time. But it must have begun, in a natural environment, in which whatever life inhabited the earth, was subjected, for good or ill, to influences that had their origin in sun and storm and the ancient nature of the earth. Some of the elements of this environment created hazards to which life had to adjust or perish. The ultraviolet radiation in sunlight could cause malignancy. So could radiations from certain rocks, or arsenic washed out of soil or rocks to contaminate food or water supplies.

The environment contained these hostile elements even before there was life; yet life arose, and over the millions of years it came to exist in infinite numbers and endless variety…These natural cancer-causing agents are still a factor in producing malignancy; however, they are few in number and they belong to that ancient array of forces to which life has been accustomed, from the beginning.

With the advent of man the situation began to change, for man, alone of all forms of life, can create cancer-producing substances, which in medical terminology are called carcinogens. A few man-made carcinogens have been part of the environment for centuries. An example is soot, containing aromatic hydrocarbons. With the dawn of the industrial era, the world became a place of continuous, ever-accelerating change. Instead of the natural environments there was rapidly substituted an artificial one composed of new chemical and physical agents, many of them possessing powerful capacities for inducing biological change. Against these carcinogens which his own activities had created man had no protection, for even as his biological heritage had evolved slowly, so it adapts slowly to new conditions. As a result these powerful substances could easily penetrate the inadequate defenses of the body.

The history of cancer is long, but our recognition of the agents that produce it has been slow to mature…

One of the most impressive theories of the origin of cancer cells was developed by a German biochemist, Prof. Otto Warburg of the Max Planck Institute of Cell Physiology. Warburg has devoted a lifetime of study to the complex processes of oxidation within the cell. Out of this broad background of understanding came a fascinating and lucid explanation of the way a normal cell can become malignant.

Warburg believes that either radiation or a chemical carcinogen acts by destroying the respiration of normal cells, thus depriving them of energy. This action may result form minute doses often repeated. The effect, once achieved, is irreversible. The cells not killed outright by the impact of such a respiratory poison struggle to compensate for the loss of energy. They can no longer carry on that extraordinary and efficient cycle in which vast amounts of ATP are produced, bgut are thrown back on a primitive and far less efficient method, that of fermentation. The struggle to survive by fermentation continues for a long period of time. It continues through ensuing cell divisions, so that all the descendant cells have this abnormal method of respiration…At last they reach the point where fermentation is able to produce as much energy as respiration. At this point cancer cells may be said to have been created from normal body cells…

The Warburg theory also explains why repeated small doses of a carcinogen are more dangerous under some circumstances than a single large dose. The latter may kill the cells outright, whereas the small doses allow some to survive, though in a damaged condition. These survivors may then develop into cancer cells. This is why there is no ‘safe’ dose of a carcinogen.

In Warburg’s theory we also find explanation of an otherwise incomprehensible fact – that one and the same agent can be useful in treating cancer and can also cause it. This, as everyone knows, is true of radiation, which kills cancer cells but may also cause cancer. It is also true of many of the chemicals now used against cancer. Why? Both types of agents damage respiration. Cancer cells already have a defective respiration, so with additional damage they die. The normal cells, suffering respiratory damage for the first time, are not killed but are set on the path that may eventually lead to malignancy.

Measured by the standards established by Warburg, most pesticides meet the criterion of the perfect carcinogen too well for comfort…they may be creating sleeping cancer cells, cells in which an irreversible malignancy will slumber long and undetected – its cause long forgotten and even unsuspected – it flares into the open as recognizable cancer.

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