part of the earth’s surface is covered by its enveloping seas, yet in the midst of this plenty we
are in want. By a strange paradox, most of the earth’s abundant water is not usable for
agriculture, industry, or human consumption because of its heavy load of sea salts, and so most
of the world’s population is either experiencing or is threatened with critical shortages. In an
age when man has forgotten his origins and is blind even to his most essential needs for
survival, water along with other resources has become the victim of his indifference.
The problem of water pollution by pesticides can be understood only in context, as part of the
whole to which it belongs—the pollution of the total environment of mankind. The pollution
entering our waterways comes from many sources: radioactive wastes from reactors,
laboratories, and hospitals; fallout from nuclear explosions; domestic wastes from cities and
towns; chemical wastes from factories. To these is added a new kind of fallout—the chemical
sprays applied to croplands and gardens, forests and fields. Many of the chemical agents in this
alarming mélange imitate and augment the harmful effects of radiation, and within the groups
of chemicals themselves there are sinister and little understood interactions, transformations,
and summations of effect.
Ever since chemists began to manufacture substances that nature never invented, the problems
of water purification have become complex and the danger to users of water has increased. As
we have seen, the production of these synthetic chemicals in large volume began in the 1940s.
It has now reached such proportions that an appalling deluge of chemical pollution is daily
poured into the nation’s waterways. When inextricably mixed with domestic and other wastes
discharged into the same water, these chemicals sometimes defy detection by the methods in
ordinary use by purification plants. Most of them are so stable that they cannot be broken
down by ordinary processes. Often they cannot even be identified. In rivers, a really incredible
variety of pollutants combine to produce deposits that the sanitary engineers can only
despairingly refer to as ‘gunk’. Professor Rolf Eliassen of the Massachusetts Institute of
Technology testified before a congressional committee to the impossibility of predicting the
composite effect of these chemicals, or of identifying the organic matter resulting from the
mixture. ‘We don’t begin to know what that is,’ said Professor Eliassen. ‘What is the effect on
the people? We don’t know.’
To an ever-increasing degree, chemicals used for the control of insects, rodents, or unwanted
vegetation contribute to these organic pollutants. Some are deliberately applied to bodies of
water to destroy plants, insect larvae, or undesired fishes. Some come from forest spraying that
may blanket two or three million acres of a single state with spray directed against a single
insect pest—spray that falls directly into streams or that drips down through the leafy canopy
to the forest floor, there to become part of the slow movement of seeping moisture beginning
its long journey to the sea. Probably the bulk of such contaminants are the waterborne residues
of the millions of pounds of agricultural chemicals that have been applied to farmlands for
insect or rodent control and have been leached out of the ground by rains to become part of
the universal seaward movement of water.
Here and there we have dramatic evidence of the presence of these chemicals in our streams
and even in public water supplies. For example, a sample of drinking water from an orchard
area in Pennsylvania, when tested on fish in a laboratory, contained enough insecticide to kill all
of the test fish in only four hours. Water from a stream draining sprayed cotton fields remained
lethal to fishes even after it had passed through a purifying plant, and in fifteen streams
tributary to the Tennessee River in Alabama the runoff from fields treated with toxaphene, a
chlorinated hydrocarbon, killed all the fish inhabiting the streams. Two of these streams were
sources of municipal water supply. Yet for a week after the application of the insecticide the
water remained poisonous, a fact attested by the daily deaths of goldfish suspended in cages
downstream.
For the most part this pollution is unseen and invisible, making its presence known when
hundreds or thousands of fish die, but more often never detected at all. The chemist who
guards water purity has no routine tests for these organic pollutants and no way to remove
them. But whether detected or not, the pesticides are there, and as might be expected with any
materials applied to land surfaces on so vast a scale, they have now found their way into many
and perhaps all of the major river systems of the country.
If anyone doubts that our waters have become almost universally contaminated with
insecticides he should study a small report issued by the United States Fish and Wildlife Service
in 1960. The Service had carried out studies to discover whether fish, like warm-blooded
animals, store insecticides in their tissues. The first samples were taken from forest areas in the
West where there had been mass spraying of DDT for the control of the spruce budworm. As
might have been expected, all of these fish contained DDT. The really significant findings were
made when the investigators turned for comparison to a creek in a remote area about 30 miles
from the nearest spraying for budworm control. This creek was upstream from the first and
separated from it by a high waterfall. No local spraying was known to have occurred. Yet these
fish, too, contained DDT. Had the chemical reached this remote creek by hidden underground
streams? Or had it been airborne, drifting down as fallout on the surface of the creek? In still
another comparative study, DDT was found in the tissues of fish from a hatchery where the
water supply originated in a deep well. Again there was no record of local spraying. The only
possible means of contamination seemed to be by means of groundwater.
In the entire water-pollution problem, there is probably nothing more disturbing than the
threat of widespread contamination of groundwater. It is not possible to add pesticides to
water anywhere without threatening the purity of water everywhere. Seldom if ever does
Nature operate in closed and separate compartments, and she has not done so in distributing
the earth’s water supply. Rain, falling on the land, settles down through pores and cracks in soil
and rock, penetrating deeper and deeper until eventually it reaches a zone where all the pores
of the rock are filled with water, a dark, subsurface sea, rising under hills, sinking beneath
valleys. This groundwater is always on the move, sometimes at a pace so slow that it travels no
more than 50 feet a year, sometimes rapidly, by comparison, so that it moves nearly a tenth of
a mile in a day. It travels by unseen waterways until here and there it comes to the surface as a
spring, or perhaps it is tapped to feed a well. But mostly it contributes to streams and so to
rivers. Except for what enters streams directly as rain or surface runoff, all the running water of
the earth’s surface was at one time groundwater. And so, in a very real and frightening sense,
pollution of the groundwater is pollution of water everywhere. . . .
It must have been by such a dark, underground sea that poisonous chemicals traveled from a
manufacturing plant in Colorado to a farming district several miles away, there to poison wells,
sicken humans and livestock, and damage crops—an extraordinary episode that may easily be
only the first of many like it. Its history, in brief, is this. In 1943, the Rocky Mountain Arsenal of
the Army Chemical Corps, located near Denver, began to manufacture war materials. Eight
years later the facilities of the arsenal were leased to a private oil company for the production
of insecticides. Even before the change of operations, however, mysterious reports had begun
to come in. Farmers several miles from the plant began to report unexplained sickness among
livestock; they complained of extensive crop damage. Foliage turned yellow, plants failed to
mature, and many crops were killed outright. There were reports of human illness, thought by
some to be related.
The irrigation waters on these farms were derived from shallow wells. When the well waters
were examined (in a study in 1959, in which several state and federal agencies participated)
they were found to contain an assortment of chemicals. Chlorides, chlorates, salts of
phosphoric acid, fluorides, and arsenic had been discharged from the Rocky Mountain Arsenal
into holding ponds during the years of its operation. Apparently the groundwater between the
arsenal and the farms had become contaminated and it had taken 7 to 8 years for the wastes to
travel underground a distance of about 3 miles from the holding ponds to the nearest farm.
This seepage had continued to spread and had further contaminated an area of unknown
extent. The investigators knew of no way to contain the contamination or halt its advance.
All this was bad enough, but the most mysterious and probably in the long run the most
significant feature of the whole episode was the discovery of the weed killer 2,4-D in some of
the wells and in the holding ponds of the arsenal. Certainly its presence was enough to account
for the damage to crops irrigated with this water. But the mystery lay in the fact that no 2,4-D
had been manufactured at the arsenal at any stage of its operations. After long and careful
study, the chemists at the plant concluded that the 2,4-D had been formed spontaneously in
the open basins. It had been formed there from other substances discharged from the arsenal;
in the presence of air, water, and sunlight, and quite without the intervention of human
chemists, the holding ponds had become chemical laboratories for the production of a new
chemical—a chemical fatally damaging to much of the plant life it touched. And so the story of
the Colorado farms and their damaged crops assumes a significance that transcends its local
importance. What other parallels may there be, not only in Colorado but wherever chemical
pollution finds its way into public waters? In lakes and streams everywhere, in the presence of
catalyzing air and sunlight, what dangerous substances may be born of parent chemicals
labeled ‘harmless’?
Indeed one of the most alarming aspects of the chemical pollution of water is the fact that
here—in river or lake or reservoir, or for that matter in the glass of water served at your dinner
table—are mingled chemicals that no responsible chemist would think of combining in his
laboratory. The possible interactions between these freely mixed chemicals are deeply
disturbing to officials of the United States Public Health Service, who have expressed the fear
that the production of harmful substances from comparatively innocuous chemicals may be
taking place on quite a wide scale. The reactions may be between two or more chemicals, or
between chemicals and the radioactive wastes that are being discharged into our rivers in ever-
increasing volume. Under the impact of ionizing radiation some rearrangement of atoms could easily occur, changing the nature of the chemicals in a way that is not only unpredictable but
beyond control. It is, of course, not only the groundwaters that are becoming contaminated,
but surface-moving waters as well— streams, rivers, irrigation waters. A disturbing example of
the latter seems to be building up on the national wildlife refuges at Tule Lake and Lower
Klamath, both in California. These refuges are part of a chain including also the refuge on Upper
Klamath Lake just over the border in Oregon. All are linked, perhaps fatefully, by a shared water
supply, and all are affected by the fact that they lie like small islands in a great sea of
surrounding farmlands—land reclaimed by drainage and stream diversion from an original
waterfowl paradise of marshland and open water.
These farmlands around the refuges are now irrigated by water from Upper Klamath Lake. The
irrigation waters, recollected from the fields they have served, are then pumped into Tule Lake
and from there to Lower Klamath. All of the waters of the wildlife refuges established on these
two bodies of water therefore represent the drainage of agricultural lands. It is important to
remember this in connection with recent happenings. In the summer of 1960 the refuge staff
picked up hundreds of dead and dying birds at Tule Lake and Lower Klamath. Most of them
were fish-eating species—herons, pelicans, gulls. Upon analysis, they were found to contain
insecticide residues identified as toxaphene, DDD, and DDE. Fish from the lakes were also found
to contain insecticides; so did samples of plankton. The refuge manager believes that pesticide
residues are now building up in the waters of these refuges, being conveyed there by return
irrigation flow from heavily sprayed agricultural lands.
Such poisoning of waters set aside for conservation purposes could have consequences felt by
every western duck hunter and by everyone to whom the sight and sound of drifting ribbons of
waterfowl across an evening sky are precious. These particular refuges occupy critical positions
in the conservation of western waterfowl. They lie at a point corresponding to the narrow neck
of a funnel, into which all the migratory paths composing what is known as the Pacific Flyway
converge. During the fall migration they receive many millions of ducks and geese from nesting
grounds extending from the shores of Bering Sea east to Hudson Bay—fully three fourths of all
the waterfowl that move south into the Pacific Coast states in autumn. In summer they provide
nesting areas for waterfowl, especially for two endangered species, the redhead and the ruddy
duck. If the lakes and pools of these refuges become seriously contaminated the damage to the
waterfowl populations of the Far West could be irreparable. Water must also be thought of in
terms of the chains of life it supports—from the small-as-dust green cells of the drifting plant
plankton, through the minute water fleas to the fishes that strain plankton from the water and
are in turn eaten by other fishes or by birds, mink, raccoons—in an endless cyclic transfer of
materials from life to life. We know that the necessary minerals in the water are so passed from
link to link of the food chains. Can we suppose that poisons we introduce into water will not
also enter into these cycles of nature?
The answer is to be found in the amazing history of Clear Lake, California. Clear Lake lies in
mountainous country some 90 miles north of San Francisco and has long been popular with
anglers. The name is inappropriate, for actually it is a rather turbid lake because of the soft
black ooze that covers its shallow bottom. Unfortunately for the fishermen and the resort
dwellers on its shores, its waters have provided an ideal habitat for a small gnat, Chaoborus
astictopus. Although closely related to mosquitoes, the gnat is not a bloodsucker and probably
does not feed at all as an adult. However, human beings who shared its habitat found it
annoying because of its sheer numbers. Efforts were made to control it but they were largely fruitless until, in the late 1940s, the chlorinated hydrocarbon insecticides offered new weapons.
The chemical chosen for a fresh attack was DDD, a close relative of DDT but apparently offering
fewer threats to fish life. The new control measures undertaken in 1949 were carefully planned
and few people would have supposed any harm could result. The lake was surveyed, its volume
determined, and the insecticide applied in such great dilution that for every part of chemical
there would be 70 million parts of water. Control of the gnats was at first good, but by 1954 the
treatment had to be repeated, this time at the rate of 1 part of insecticide in 50 million parts of
water. The destruction of the gnats was thought to be virtually complete.
The following winter months brought the first intimation that other life was affected: the
western grebes on the lake began to die, and soon more than a hundred of them were reported
dead. At Clear Lake the western grebe is a breeding bird and also a winter visitant, attracted by
the abundant fish of the lake. It is a bird of spectacular appearance and beguiling habits,
building its floating nests in shallow lakes of western United States and Canada. It is called the
‘swan grebe’ with reason, for it glides with scarcely a ripple across the lake surface, the body
riding low, white neck and shining black head held high. The newly hatched chick is clothed in
soft gray down; in only a few hours it takes to the water and rides on the back of the father or
mother, nestled under the parental wing coverts.
Following a third assault on the ever-resilient gnat population, in 1957, more grebes died. As
had been true in 1954, no evidence of infectious disease could be discovered on examination of
the dead birds. But when someone thought to analyze the fatty tissues of the grebes, they were
found to be loaded with DDD in the extraordinary concentration of 1600 parts per million. The
maximum concentration applied to the water was part per million. How could the chemical
have built up to such prodigious levels in the grebes? These birds, of course, are fish eaters.
When the fish of Clear Lake also were analyzed the picture began to take form—the poison
being picked up by the smallest organisms, concentrated and passed on to the larger predators.
Plankton organisms were found to contain about 5 parts per million of the insecticide (about 25
times the maximum concentration ever reached in the water itself); plant-eating fishes had
built up accumulations ranging from 40 to 300 parts per million; carnivorous species had stored
the most of all. One, a brown bullhead, had the astounding concentration of 2500 parts per
million. It was a house-that-Jack-built sequence, in which the large carnivores had eaten the
smaller carnivores, that had eaten the herbivores, that had eaten the plankton, that had
absorbed the poison from the water.
Even more extraordinary discoveries were made later. No trace of DDD could be found in the
water shortly after the last application of the chemical. But the poison had not really left the
lake; it had merely gone into the fabric of the life the lake supports. Twenty-three months after
the chemical treatment had ceased, the plankton still contained as much as 5.3 parts per
million. In that interval of nearly two years, successive crops of plankton had flowered and
faded away, but the poison, although no longer present in the water, had somehow passed
from generation to generation. And it lived on in the animal life of the lake as well. All fish,
birds, and frogs examined a year after the chemical applications had ceased still contained
DDD. The amount found in the flesh always exceeded by many times the original concentration
in the water. Among these living carriers were fish that had hatched nine months after the last
DDD application, grebes, and California gulls that had built up concentrations of more than
2000 parts per million. Meanwhile, the nesting colonies of the grebes dwindled—from more
than 1000 pairs before the first insecticide treatment to about 30 pairs in 1960. And even the
thirty seem to have nested in vain, for no young grebes have been observed on the lake since
the last DDD application.
This whole chain of poisoning, then, seems to rest on a base of minute plants which must have
been the original concentrators. But what of the opposite end of the food chain—the human
being who, in probable ignorance of all this sequence of events, has rigged his fishing tackle,
caught a string of fish from the waters of Clear Lake, and taken them home to fry for his
supper? What could a heavy dose of DDD, or perhaps repeated doses, do to him? Although the
California Department of Public Health professed to see no hazard, nevertheless in 1959 it
required that the use of DDD in the lake be stopped. In view of the scientific evidence of the
vast biological potency of this chemical, the action seems a minimum safety measure. The
physiological effect of DDD is probably unique among insecticides, for it destroys part of the
adrenal gland— the cells of the outer layer known as the adrenal cortex, which secretes the
hormone cortin. This destructive effect, known since 1948, was at first believed to be confined
to dogs, because it was not revealed in such experimental animals as monkeys, rats, or rabbits.
It seemed suggestive, however, that DDD produced in dogs a condition very similar to that
occurring in man in the presence of Addison’s disease. Recent medical research has revealed
that DDD does strongly suppress the function of the human adrenal cortex. Its cell-destroying
capacity is now clinically utilized in the treatment of a rare type of cancer which develops in the
adrenal gland. . . .
The Clear Lake situation brings up a question that the public needs to face: Is it wise or
desirable to use substances with such strong effect on physiological processes for the control of
insects, especially when the control measures involve introducing the chemical directly into a
body of water? The fact that the insecticide was applied in very low concentrations is
meaningless, as its explosive progress through the natural food chain in the lake demonstrates.
Yet Clear Lake is typical of a large and growing number of situations where solution of an
obvious and often trivial problem creates a far more serious but conveniently less tangible one.
Here the problem was resolved in favor of those annoyed by gnats, and at the expense of an
unstated, and probably not even clearly understood, risk to all who took food or water from the
lake. It is an extraordinary fact that the deliberate introduction of poisons into a reservoir is
becoming a fairly common practice. The purpose is usually to promote recreational uses, even
though the water must then be treated at some expense to make it fit for its intended use as
drinking water. When sportsmen of an area want to ‘improve’ fishing in a reservoir, they prevail
on authorities to dump quantities of poison into it to kill the undesired fish, which are then
replaced with hatchery fish more suited to the sportsmen’s taste. The procedure has a strange,
Alice-in-Wonderland quality. The reservoir was created as a public water supply, yet the
community, probably unconsulted about the sportsmen’s project, is forced either to drink
water containing poisonous residues or to pay out tax money for treatment of the water to
remove the poisons—treatments that are by no means foolproof.
As ground and surface waters are contaminated with pesticides and other chemicals, there is
danger that not only poisonous but also cancer-producing substances are being introduced into
public water supplies. Dr. W. C. Hueper of the National Cancer Institute has warned that ‘the
danger of cancer hazards from the consumption of contaminated drinking water will grow
considerably within the foreseeable future.’ And indeed a study made in Holland in the early
1950s provides support for the view that polluted waterways may carry a cancer hazard. Cities
receiving their drinking water from rivers had a higher death rate from cancer than did those
whose water came from sources presumably less susceptible to pollution such as wells. Arsenic,
the environmental substance most clearly established as causing cancer in man, is involved in
two historic cases in which polluted water supplies caused widespread occurrence of cancer. In
one case the arsenic came from the slag heaps of mining operations, in the other from rock
with a high natural content of arsenic. These conditions may easily be duplicated as a result of
heavy applications of arsenical insecticides. The soil in such areas becomes poisoned. Rains
then carry part of the arsenic into streams, rivers, and reservoirs, as well as into the vast
subterranean seas of groundwater.
Here again we are reminded that in nature nothing exists alone. To understand more clearly
how the pollution of our world is happening, we must now look at another of the earth’s basic
resources, the soil.
No comments:
Post a Comment