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Morey Trish Mć śź z Toskani
Dahlia Rose Outlaw's Delight [Amira] (pdf)
[ Pobierz całość w formacie PDF ]
When all its work is done the lie shall rot;
The truth is great, and shall prevail, When none cares whether it prevails or
not.
Coventry Patmore, from the poem "Magna est Veritas"
The DDT controversy takes us back over thirty years and might have slipped
from the memories of some. Others may never have been cognizant of it in the
first place. And that's a good reason for selecting it for inclusion, for it
constitutes the original, model environmental catastrophe scenario and protest
movement, setting the pattern for just about all of the major issues that have
become news since.
Some Background Intelligence: Malaria
The biggest single killer of human beings through history has been malaria.
Before the 1940s, 300
million new cases were contracted annually worldwide, and of those stricken, 3
million died. 6 to 7
million cases occurred every year in the United States, primarily in the South
and parts of California.
Malaria is caused by a genus of protozoan the simplest, single-cell animal
form called
Plasmodium
, which comes in four species. In the human bloodstream they take a form known
as merozoites, which burrow into the red blood cells and reproduce asexually,
each one producing 6 to 26
new individuals which burst out to infect new blood cells on a cycle that
repeats every forty-eight hours.
When the number of merozoites exceeds about 50 per cubic milliliter of blood
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(a typical drop), the victim suffers a malaria attack every forty-eight hours.
In a heavily infected person, the number of plasmodia present can be as high
as 2 million per milliliter.
The severity of the symptoms depends on the species involved, but a typical
attack consists of severe frontal headache and pain in the neck, lower back,
and limbs, dizziness and general malaise, accompanied by waves of chill and
seizures alternating with fever temperatures of up to 104 F and o profuse
sweating, acute thirst and vomiting being not uncommon. The falciparum variety
can kill up to 40
percent of those affected. Deaths occur mainly among children under five years
old. For those who survive, the pattern continues for several months, and then
gives way to symptom-free periods punctuated by relapses that occur over
anywhere from a year to ten years. The effects can be sufficiently
debilitating to incapacitate 80 percent of a workforce, with such consequences
as preventing harvesting of a food crop, thus rendering a population
vulnerable to all of the opportunistic threats that come with malnutrition and
an impaired immune system, such as hepatitis, tuberculosis, dysentery, and
typhoid fever. Transmission from person to person takes place through the
ingestion of blood by females of the
Anopheles mosquito, and re-injection of
Plasmodium into a new victim via the saliva after undergoing another part of
its life cycle within the mosquito's stomach.
Since, through most of history, eliminating the mosquito was never feasible,
attempts at checking the spread of the disease were directed at destruction of
the breeding grounds. The two main methods were draining of swamps and marshy
areas, which dates back to the Romans, and the flooding of lakes and open
areas of water with oil from early spring to fall, to prevent the mosquito
larvae from breathing.
Where irrigation channels were needed for agriculture, a common practice was
to introduce the
"mosquito fish"
Gambusia
, a typically arduous and expensive undertaking, since it was usually
necessary to first eradicate such predatory types as catfish, which were
partial to
Gambusia
. These measures were partially successful at best, and confined to the more
developed countries. Only Italy achieved what seemed to be eradication, after
a fifteen-year program of intensive effort under Mussolini, but the victory
turned out to be temporary.
Then, in 1939, Paul Mueller, a chemist working for J. R. Geigy S.S. in
Switzerland, developed a
compound, ichloro-diphenyl-trichloroethane DDT by combining chlorals with
hydrocarbons and phenols that was cheap, easy to produce and use, nontoxic to
mammals and plants, but extremely toxic on contact to insects and various
other arthropods. The Allies quickly recognized its value for wartime use and
found it 100 percent effective as a fumigant against the ticks and body lice
that transmit typhus, which in World War I had killed millions of soldiers and
civilians in Europe. In early 1944 an incipient typhus epidemic in Naples was
halted with no adverse side effects apart from a few cases of very minor skin
irritation, after efforts with more conventional agents achieved only limited
results. A plague epidemic in Dakar, West Africa, was stopped by using DDT to
eliminate the carrier fleas, and it was mobilized with great success against
malaria in the Pacific theater, Southeast Asia, and Africa. After the war, DDT
became widely available not only for the reduction of insect-transmitted human
diseases but also of a wide range of agricultural, timber, and animal pests.
The results from around the world seemed to bear out its promise as the
perfect insecticide.
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For combating malaria, it was sufficient to spray the walls and ceiling of
dwellings once or twice a year. Malaria mosquitoes rested in these places when
inactive, and the DDT penetrated via their feet.
Incidence in India in the 1940s was over 100 million cases annually, of which
2.5 million died. By 1962
these numbers were down to 5 million and 150,000, while life expectancy had
risen from thirty-two to forty-seven. A 1.5-ounce shot glass of DDT solution
covered twelve by twelve feet of wall. The cost
186
per human life saved worked out at about twenty cents per year. In the same
period, India's wheat production increased from less than 25 million tons to
over 100 million tons per year due to a combination of pest reduction and a
healthier workforce. Ceylon now Sri Lanka reduced its malaria figures from 3
million cases and 12,000 deaths per year in the early fifties to 31 cases
total in 1962, and
17 cases the year after, with zero deaths. Pakistan reported 7 million cases
of malaria in 1961, which after the introduction of an aggressive spraying
program had fallen to 9,500 by 1967.
187
In Africa, in what is considered to be its second most important medical
benefit after reducing malaria, DDT proved effective in a program to control
the bloodsucking tsetse fly, which transmits the protozoan responsible for
deadly sleeping sickness and also fatal cattle diseases. According to the
World Health Organization, 40 million square miles of land that had been
rendered uninhabitable for humans because of tsetse fly infestation became
available.
Another serious menace in parts of Africa and Central American is the blackfly
that transmits roundworms causing "river blindness" in humans. Before DDT was
introduced, more than 20,000
victims of this affliction in Africa were blind, with incidences as high as 30
percent of the populations of some villages. The larvae of the flies live in [ Pobierz całość w formacie PDF ]
