pollution

/peuh looh"sheuhn/, n.

1. the act of polluting or the state of being polluted.

2. the introduction of harmful substances or products into the environment: air pollution.

[1350-1400; ME pollucioun ( < OF) < LL pollution-, s. of pollutio defilement; see POLLUTE, -ION]

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▪ environment

Introduction

also called  environmental pollution 

 the addition of any substance or form of energy (e.g., heat, sound, radioactivity) to the environment at a rate faster than the environment can accommodate it by dispersion, breakdown, recycling, or storage in some harmless form.

      A pollutant need not be harmful in itself. Carbon dioxide, for example, is a normal component of the atmosphere and a by-product of respiration that is found in all animal tissues; yet in a concentrated form it can kill animals. Human sewage (sewage system) can be a useful fertilizer, but when concentrated too highly it becomes a serious pollutant, menacing health and causing the depletion of oxygen in bodies of water. By contrast, radioactivity (radiation) in any quantity is harmful to life, despite the fact that it occurs normally in the environment as so-called background radiation.

      Pollution has accompanied mankind ever since groups of people first congregated and remained for a long time in any one place. Primitive human settlements can be recognized by their pollutants—shell mounds and rubble heaps. But pollution was not a serious problem as long as there was enough space available for each individual or group. With the establishment of permanent human settlements by great numbers of people, however, pollution became a problem and has remained one ever since. Cities of ancient times were often noxious places, fouled by human wastes and debris. In the Middle Ages, unsanitary urban conditions favoured the outbreak of population-decimating epidemics. During the 19th century, water and air pollution and the accumulation of solid wastes were largely the problems of only a few large cities. But, with the rise of advanced technology and with the rapid spread of industrialization and the concomitant increase in human populations to unprecedented levels, pollution has become a universal problem.

      The various kinds of pollution are most conveniently considered under three headings: air, water, and land.

Air pollution

      Air pollution involves the release into the atmosphere of gases, finely divided solids, or finely dispersed liquid aerosols at rates that exceed the capacity of the atmosphere to dissipate them or to dispose of them through incorporation into solid or liquid layers of the biosphere. Air pollution results from a variety of causes, not all of which are within human control. Dust storms in desert areas and smoke from forest and grass fires contribute to chemical and particulate pollution of the air. Forest fires that swept the state of Victoria, in Australia, in 1939 caused observable air pollution in Queensland, more than 2,000 miles (3,000 kilometres) away. Dust blown from the Sahara has been detected in West Indian islands. The discovery of pesticides in Antarctica, where they have never been used, suggests the extent to which aerial transport can carry pollutants from one place to another. Probably the most important natural source of air pollution is volcanic activity, which at times pours great amounts of ash and toxic fumes into the atmosphere. The eruptions of such volcanoes as Krakatoa, in the East Indies, Mt. St. Helens, in Washington, and Katmai, in Alaska, have been related to measurable climatic changes.

      Air pollution may affect humans directly, causing a smarting of the eyes or coughing. More indirectly, the effects of air pollution are experienced at considerable distances from the source, as, for example, the fallout of tetraethyl lead from urban automobile exhausts, which has been observed in the oceans and on the Greenland ice sheet. Still less directly experienced are the possible effects of air pollution on global climates.

Urban (urbanization) air pollution

      It is the immediate effect of air pollution on urban atmospheres that is most noticeable and causes the strongest public reaction. The city of Los Angeles has been noted for both the extent of its air pollution and the actions undertaken for control. Los Angeles lies in a coastal plain, surrounded by mountains that restrict the inward sweep of air and that separate a desert from the coastal climate. Fog moving in from the ocean is normal to the city. Temperature inversions characterized by the establishment of a layer of warm air on top of a layer of cooler air prevent the air near the ground from rising and thus effectively trap pollutants that have accumulated in the lower layer of air. In the 1940s, the air in Los Angeles became noticeably polluted, interfering with visibility and causing human discomfort. Attempts to control pollution, initiated during the 1950s, resulted in the successful elimination of such sources of pollution as industrial effluents and the outdoor burning of trash and debris. Nevertheless, pollution continued to increase as a result of the increased number of motor vehicles. Exhaust fumes from the engines of automobiles contain a number of polluting substances, including carbon monoxide and a variety of complex hydrocarbons, nitrogen oxides, and other compounds. When acted upon by sunlight, these substances undergo a change in composition producing the brown, photochemical smog for which Los Angeles is well known. Efforts to reduce pollution from automobile engines and to develop pollution-free engines may eventually eliminate the more serious air pollution problems. In the meantime, however, air pollution has driven many forms of agriculture from the Los Angeles basin, has had a serious effect upon the pine forests in nearby mountains, and has caused respiratory distress, particularly in children, elderly people, and those suffering from respiratory diseases.

      Los Angeles is neither a unique nor the worst example of polluted air. Tokyo has such a serious air-pollution problem that oxygen is supplied to policemen who direct traffic at busy intersections. Milan, Ankara, Mexico City, and Buenos Aires face similar problems. Although New York City produces greater quantities of pollutants than Los Angeles, it has been spared from an air-pollution disaster only because of favourable climatic circumstances.

      The task of cleaning up air pollution, though difficult, is not believed to be insurmountable. Use of fuels that are low in pollutants, such as low-sulfur forms of petroleum; more complete burning of fossil fuels (fossil fuel), at best to carbon dioxide and water; the scrubbing of industrial smokestacks or precipitation of pollutants from them, often in combination with a recycling of the pollutants; and the shift to less polluting forms of power generation, such as solar energy in place of fossil fuels—all are methods that can be used for controlling pollution. The example of London, as well as of other cities, has shown that major improvements in air quality can be achieved in 10 years or less.

Climatic (climate) effects of polluted air

      Less obvious than local concentrations of pollution but potentially more important are the climatic effects of air pollutants. Thus, as a result of the growing worldwide consumption of fossil fuels, atmospheric carbon dioxide levels have increased steadily since 1900, and the rate of increase is accelerating. The output of carbon dioxide is believed by some to have reached a point such that it may exceed both the capacity of plant life to remove it from the atmosphere and the rate at which it goes into solution in the oceans. In the atmosphere carbon dioxide creates a “greenhouse effect.” Like glass in a greenhouse (greenhouse effect), it allows light rays from the Sun to pass through, but it does not allow the escape of the heat rays generated when sunlight is absorbed by the surface of the ground. An increase in carbon dioxide, therefore, can cause an increase in the temperature of the lower atmosphere. If allowed to continue, this could cause melting of the polar ice caps, raising of the sea level, and flooding of the coastal areas of the world. There is every reason to fear that such a climatic change may take place.

      Counterbalancing the effect of carbon dioxide is the increase of particulate matter in the air, a result of the output of smoke, dust, and other solids associated with human activity. Such an increase might, in turn, increase the reflectance, or albedo, of the atmosphere, causing a higher percentage of solar radiation to be reflected back into space. This, in time, could cause a lowering of the Earth's surface temperature and, potentially, a new ice age. At present, however, the greater danger appears to lie in the steady increase in carbon dioxide, with its associated atmospheric warming.

      Scientists also fear that the ozonosphere (or ozone layer of the atmosphere) is being depleted by the chemical action of chlorofluorocarbons emitted from aerosol cans and refrigerators and by pollutants from rockets and supersonic (supersonic flight) aircraft. Depletion of the ozone layer, which absorbs ultraviolet radiation from the Sun, would have serious effects on living organisms on the Earth's surface, including increasing frequency of skin cancer among humans.

      Another climatic effect of pollution is acid rain. The phenomenon occurs when sulfur dioxide and nitrogen oxides from the burning of fossil fuels combine with water vapour in the atmosphere. The resulting precipitation is damaging to water, forest, and soil resources. It is blamed for the disappearance of fish from many lakes in the Adirondacks, for the widespread death of forests in European mountains, and for damaging tree growth in the United States and Canada. Reports also indicate that it can corrode buildings and be hazardous to human health. Because the contaminants are carried long distances, the sources of acid rain are difficult to pinpoint and hence difficult to control. Acid rain has been reported in areas as far apart as Sweden and Canada, and in parts of the United States from New England to Texas. The drifting of pollutants causing acid rain across international boundaries has created disagreements between Canada and the United States and among European countries over the causes and solutions of the precipitation. The international scope of the problem has led to the signing of international agreements on the limitation of sulfur and nitrogen oxide emissions.

Radioactive (radioactivity) contamination of the atmosphere

      During the 1950s the effects of atmospheric testing of atomic and hydrogen bombs became a source of major concern. The danger of radioactive pollution of the air and the fallout of radioactive particles to the surface of the Earth stimulated serious investigation, resulting in the discovery of potentially dangerous conditions. It was observed, for example, that radioactive materials of many kinds, such as radioactive iodine and strontium, are concentrated in living tissue and can cause damage even when the general level of environmental contamination is low. Atmospheric testing of nuclear bombs was stopped in the United States and the Soviet Union, and radioactive fallout from this source has declined. Concern continues, however, over the dangers resulting from massive releases of radioactive materials from nuclear weapons, which, if used on a major scale, could seriously endanger all of humanity.

      Another concern is accidents at nuclear power plants. In 1978 the Three Mile Island nuclear power plant in Pennsylvania suffered a severe accident leading to partial meltdown of its radioactive core. Although most of the radiation was contained within the plant structure, the prospects of massive contamination of nearby cities and towns resulted in plans for the evacuation of hundreds of thousands of people. In 1986 the Chernobyl nuclear power plant near Kiev, in the Ukrainian S.S.R., suffered a fire and partial meltdown, resulting in a major release of radioactive particles. Much of northern and eastern Europe experienced heavy nuclear fallout, and the towns and farmlands around the power plant were no longer safe for human occupancy.

Water pollution

      Water pollution involves the release into lakes, streams, rivers, and oceans of substances that become dissolved or suspended in the water or deposited upon the bottom and accumulate to the extent that they interfere with the functioning of aquatic ecosystems. It may also include the release of energy in the form of radioactivity or heat, as in the case of thermal pollution. Any body of water has the capacity to absorb, break down, or recycle introduced materials. Under normal circumstances, inorganic substances are widely dispersed and have little or no effect on life within the bodies of water into which they are released; organic materials are broken down by bacteria or other organisms and converted into a form in which they are useful to aquatic life. But, if the capacity of a body of water to dissolve, disperse, or recycle is exceeded, all additional substances or forms of energy become pollutants. Thus, thermal pollution, which is usually caused by the discharge of water that has been used as a coolant in fossil-fueled or nuclear-power plants, can favour a diversity of aquatic life in waters that would otherwise be too cold. In a warmer body of water, however, the addition of heat changes its characteristics and may make it less suited to species that are considered desirable.

      Pollution may begin as water moves through the air, if the air is polluted. Soil erosion adds silt as a pollutant. The use of chemical fertilizers, pesticides, or other materials on watershed lands is an additional factor contributing to water pollution. The runoff from septic tanks and the outflow of manures from livestock feedlots along the watershed are sources of organic pollutants. Industries located along waterways downstream contribute a number of chemical pollutants, some of which are toxic if present in any concentration. Finally, cities and towns contribute their loads of sewage and other urban wastes. Thus, a community far upstream in a watershed may receive relatively clean water, whereas one farther downstream receives a partly diluted mixture of urban, industrial, and rural wastes. The cost of cleaning and purifying this water for community use may be high, and the process may be only partially effective. To add to the problem, the cities and towns in the lower, or downstream, regions of the river basin contribute additional wastes that flow into estuaries, creating new pollution problems.

      The output of industries, agriculture, and urban communities generally exceeds the biologic capacities of aquatic systems, causing waters to become choked with an excess of organic substances and organisms to be poisoned by toxic materials. When organic matter exceeds the capacity of those microorganisms in water that break it down and recycle it, the excess of nutrients in such matter encourages rapid growth, or blooms, of algae. When they die, the remains of the dead algae add further to the organic wastes already in the water; eventually, the water becomes deficient in oxygen. Anaerobic organisms (those that do not require oxygen to live) then attack the organic wastes, releasing gases such as methane and hydrogen sulfide, which are harmful to the oxygen-requiring (aerobic) forms of life. The result is a foul-smelling, waste-filled body of water, a situation that has already occurred in such places as Lake Erie and the Baltic Sea and is a growing problem in freshwater lakes of Europe and North America. The process by which a lake or any other body of water changes from a clean, clear condition—with a relatively low concentration of dissolved nutrients and a balanced aquatic community—to a nutrient-rich, algae-filled body and thence to an oxygen-deficient, waste-filled condition is known as accelerated eutrophication.

Land pollution

      Land pollution involves the deposition on land of solid wastes—e.g., used cars, cans, bottles, plastic containers, paper—that cannot be broken down quickly or, in some instances, cannot be broken down at all by the action of organic or inorganic forces. (The term biodegradable is used to describe those materials that can be decomposed and recycled by biological action.) When such materials become concentrated within any one area, they interfere with organic life and create unsightly accumulations of trash. Methods of disposal other than recycling include ocean dumping, which creates water pollution and destroys marine habitats; landfill, which often requires the availability of low-lying ground and frequently involves the destruction of marshland or swamps that have high biological value; and burning, which increases air pollution. Obviously, none of these methods is entirely satisfactory, although using landfill to create artificial landscapes, which then are covered with soil and planted with various kinds of vegetation, is a possibility that remains to be fully developed. It is the great quantity of debris produced by urban communities, more so than a shortage of raw materials, that forces the development of more effective means for recycling wastes. Land pollution also involves the accumulation on land of substances in dispersed solid or liquid form that are injurious to life. This has been particularly noticeable with those chemicals (e.g., DDT) that are spread for the purpose of exterminating pests but then accumulate to the extent that they can do damage to many other forms of life.

Noise pollution

      One form of pollution that is characteristic of industrial societies is noise. The intensity of sound is measured in logarithmic units known as decibels; a change from a level of 10 decibels to one of 20 decibels actually represents a 100-fold increase in the sound level. At a level of 80 decibels, sound is annoying; but steady exposure to noise in excess of 90 decibels—a level that is frequently exceeded by many common urban sounds, such as jackhammers, jet planes, and excessively loud music—can cause permanent loss of hearing. In addition to causing loss of hearing, there is some evidence that noise can produce other deleterious effects on human health and on work performance.

      Many large cities have taken measures to decrease the level of urban noise; the problem has received much attention with the advent of supersonic jet airplanes. These aircraft, which travel at speeds faster than the speed of sound, create sound waves (sonic booms (sonic boom)) equivalent to those of major explosions and capable of damaging structures. The extent to which continuous exposure to sonic booms affects human health and functioning has yet to be determined. Nevertheless, in 1971 the U.S. Congress voted down appropriations to support the development of supersonic transport (SST) planes; several countries, including Britain and France, however, have manufactured such aircraft.

Chemical pollutants

      Among the most serious chemical pollutants are the chlorinated hydrocarbon pesticides, such as DDT, aldrin, and dieldrin; the polychlorinated biphenyls (PCBs), which are used in a variety of industrial processes and in the manufacture of many kinds of materials; and such metals as mercury, lead, cadmium, arsenic, and beryllium. All of these substances persist in the environment, being slowly, if at all, degraded by natural processes; in addition, all are toxic to life if they accumulate in any appreciable quantity.

      The persistent pesticides have created serious ecological problems. As they move through successively higher organisms in food chains, they accumulate in increasingly concentrated forms at each level, causing damaging effects to the predators at the end of the chains—i.e., they are present in low quantities in simple organisms but become more concentrated as these organisms are consumed by more complex ones, which are themselves consumed by predators. Among the species known to be adversely affected are such meat-eating birds as falcons, hawks, and eagles and such fish-eating birds as pelicans, petrels, cormorants, and egrets. The reproduction capacity of all of these birds has been affected by an accumulation of DDT or a similar compound in their tissues. This is manifested by an impairment in the ability of the females to form eggshells properly. As a result, some species lay soft-shelled or shell-less eggs that cannot be hatched, and there has been a general decline in the numbers of these birds in Europe, Japan, and North America. Although the effects of the same chemicals on mammals is less obvious and still a matter for investigation, some studies suggest that DDT can reduce the productivity of plant plankton, upon which all other marine life depends.

      There also is substantial evidence that pesticides lose the ability to control the pests they were designed to kill. Many insect species have developed immunity to a wide range of synthetic pesticides, and the resistance is inherited by their offspring. Furthermore, it has been observed that repeated use of such chemicals creates pest populations in areas in which none previously existed. This happens because the pesticides destroy populations of carnivorous, predatory insects that had in the past kept the plant-eating insects in check.

      Among other materials that are harmful to most forms of life are such metals as mercury, lead, and arsenic. The increasing release of these substances into the biosphere by industrial processes has created conditions that are now generally viewed as harmful to human welfare. Studies have been conducted on metallic pollutants to determine the normal environmental levels, the levels that are toxic to humans, and the extent to which industrial processes are responsible for the problem.

      The ultimate control of pollution will presumably involve the decision not to allow the escape into the environment of the substances that are harmful to life, the decision to contain and recycle those substances that could be harmful if released into the environment in excessive quantities, and the decision not to release into the environment substances that persist and are toxic to living things. Essentially, therefore, pollution control does not mean an abandonment of existing productive human activities but their reordering so as to guarantee that their side effects do not outweigh their advantages.

Conservation and growth

      The Earth has supported human civilization for more than 6,000 years and agriculture for twice that period. Before that, reaching back an unmeasured number of years into the past, human or near-human groups occupied various parts of the Earth, modifying them to some degree in the course of hunting, fishing, and food gathering. Patterns of land use were determined over many centuries of trial-and-error experimentation by people equipped with primitive tools who depended on the biological communities of the Earth for their energy supplies. Today, however, with abundant fossil fuels, growing amounts of nuclear energy, and sophisticated tools and machines, it is possible to quickly modify entire landscapes, changing long-established natural patterns into new patterns with new purposes. The opportunity to enhance the material welfare and general well-being of great numbers of people is now available, as is the opportunity to cause great damage and to impair the capacity of the Earth to support life. The outcome will depend on changes in attitudes toward the use and conservation of the Earth's living and nonliving resources.

The role of population, industry, and technology

      Uses of lands and resources are being modified in the expectation of continued population growth, industrial expansion, and accelerating technological change. Yet it is possible that, in the future, uses of lands and resources will take place in times of population stability, little industrial expansion, and a technology directed toward a reorganization and a rearrangement of activities to achieve a better environmental relationship. Even though certain countries of the world have already reached some degree of population stability—e.g., Ireland, Hungary, France, Sweden, Switzerland, and Japan—industrial expansion and rapid technological change continue in these countries, in part because of the demands made by other expanding nations. The existing expansionist phase of technological civilization cannot, however, be expected to continue indefinitely. The ecological limitations on growth in a limited space with limited resources lead to predictions of an inevitable end to this expansion, even if mankind fails to voluntarily limit its own growth.

Ecological considerations and advance planning

      Current decisions about land and resource use have important consequences for the future. If extensive areas of the Earth are badly damaged or their productivity destroyed by the expansion of technological civilization, they will be difficult, if not impossible, to restore. If a species becomes extinct, for example, it cannot be brought back. It is essential, therefore, that care be exercised in further modifying the planet to suit human purposes. Yet in many developing regions of the world, those where the greatest changes may be expected, little attention is being given to planning for and carefully controlling the use of land and resources. Thus, important tropical, semiarid, and subpolar regions of the Earth—the three principal climatic belts that have not yet undergone major technological development—are now being changed drastically without much consideration for their environments. In many parts of the world, ecologically trained experts are not available; in others, because of strong economic pressures toward development, ecological advice either is not sought or is ignored.

      Comparatively speaking, the failure to apply current ecological knowledge to the changing land and resource use taking place in tropical, semiarid, and subarctic lands is equivalent to the modification of the more temperate lands that took place centuries ago, when ecological knowledge was not available. In earlier centuries, however, the capacity to do irreparable damage was restricted by the lack of machinery, industry, and fuel energy. Today, capabilities are such that major destruction can be accomplished quickly. There is, therefore, a need to call upon environmental expertise during the process of economic development in any area of the world if natural resources are to be conserved and the future welfare of humanity is to receive due consideration.

      Some ecologists now believe that, although it was once possible to allow the development of a region to proceed more or less at random, based on individual wants, aspirations, and decisions about the use of lands and resources, such a process now holds too much risk for the well-being of society as a whole and for the future of the resources on which that society depends. Planning, they argue, must precede development, and regional planning is required if the use of major areas of land and its resources is to be brought into accord with environmental necessities and with the long-term needs of society.

      In densely populated and technologically advanced nations, such as those of western and northern Europe, most of the land-use decisions that would affect large areas have already been made. Although changes do occur, mostly in relation to growing urbanization and increasing material wealth, it seems likely that the remaining woodlands and fields will continue to be devoted to their present uses. In England the interest of the central government in the planning and control of land use and population distribution was marked by the passage of the Town and Country Planning Act shortly after World War II. This legislation led to decisions to limit the growth of London and to develop a pattern of new towns outside a greenbelt of agricultural and recreational land that surrounds the metropolis. In France, where there are still large areas of open space, a system for regional planning and control of land use and development (aménagement du territoire) has been formulated. It has already resulted in the establishment of new cities and recreational sites in previously undeveloped areas along the Mediterranean coast.

      It is in the sparsely populated areas in the underdeveloped countries of Africa, Asia, and Latin America as well as in such technologically advanced countries as Canada, Australia, and Russia that the greatest range of options and choices for the future is available. Because these areas have yet to undergo drastic environmental change, the need for local and regional environmentally oriented planning for resource and land use is most urgent.

Areas of promise

      Some of the current vexing conservation problems may be solved by technological developments. A highly technological society obviously requires an abundant and reliable source of energy. Research on nuclear fusion as a source of power indicates that this process could replace nuclear fission as a power source in some areas, but it appears to be too technologically demanding for widespread application. Solar energy, in its various modified forms, may be a more universally available source of power.

      Apart from the development of major new sources of power, the greatest promise for the future of mineral resources and for the prevention of pollution of the environment lies in new technologies involving the recycling and reclamation of what are now considered waste products. Demands for new minerals will be greatly reduced when those already available in population centres can be reused more readily. Reclamation of sewage and other organic wastes and restoration of these materials to soils can help to arrest losses in soil fertility and structure and to reduce the need for new supplies of chemical nutrients for soil fertilization. If development of technologies for recycling and reutilization continues, many of the existing problems of environmental pollution will be solved.

      In addition to the breeding of new strains of crop plants, the development of agricultural disease- and pest-control techniques that do not involve the release of persistent, poisonous chemicals into the environment holds promise for the production of greatly increased quantities of food and fibre from smaller areas of the Earth's surface. Two such techniques are mixed cropping, in which different crops are planted within an area to contain the spread of pests, and integrated pest management, in which as many pest-control methods as possible are used in an ecologically harmonious manner to keep infestation within manageable limits. Much more intensive development of aquaculture (cultivation of the natural produce of water), perhaps utilizing coolant water from nuclear-power plants, can also produce much higher food yields from smaller areas than are now usually obtainable. As a result of these advances in intensive food production, agriculturally marginal lands and the wilder aquatic areas would be spared for the continued support of wild species as well as for the adventure and recreation of mankind, thus helping to solve one of the most troublesome of all conservation problems, the conservation of wild nature.

Problems

      Considering the potential of new technology and the accompanying advances in science, it is possible to foresee a world in which a relatively stable human population can live at a high level of material affluence, with wild nature continuing to exist in abundance and relatively undisturbed lands available for human enjoyment. But this scientific and technological optimism is not supported by existing world conditions. Because knowledge now available is more than adequate to solve most of the world's major environmental problems, the problems are not those of science and technology but of the arrangements and functioning of human institutions and of the attitudes of individuals. Thus, while research in forestry science continues in all the forestry schools of the world, tropical forests are being devastated in ways that suggest that forestry science is still unknown. Although the techniques for managing livestock on natural ranges and pasturelands have reached a high level of sophistication, overgrazing continues around most of the world's major deserts, and animals die of hunger, people suffer from deprivation, and the deserts spread. Obviously, the knowledge available does not reach or influence the behaviour of most of the pastoral people on Earth.

Population growth

      Demographic predictions indicate that the population of the world will not be stabilized, even under the best of conditions, before it attains much higher levels. These predictions assume, of course, that there will be no major catastrophes—outbreaks of war, famine, or disease—that would cause drastic reductions in human numbers. There is little doubt that rapid population growth interferes with orderly economic development, leads to a deterioration of the human environment, places a severe strain on human institutions, and constitutes a growing threat to the survival of wild animal and plant life.

      Although techniques for birth control are effective and well known, they are unknown, unavailable, or unacceptable to those people having the most rapid rate of population growth—the ones who also live in the most precarious balance with their environment. This does not mean that the prospects for controlling population increase are poor; actually, they are better than at any time in the past. But more education is needed to encourage people to limit the size of families, and the prospects for material and economic advancement for those who have fewer children must be made more obvious.

Pollution control

      Next to the widespread and growing loss of biological diversity through the destruction of biotic communities, the conservation problem of greatest magnitude is the control of pollution; it might even be argued that it is more urgent and important. The knowledge and technology needed to control pollution effectively are now available: pollution-free engines can be built, pollution-free factories have been put into operation, and techniques for controlling agricultural insect pests with a minimum use of persistent pesticides have been developed. For economic reasons, none of these measures, however, is being applied universally, and political and social pressures have not yet forced their application. Moreover, developing nations have expressed fear that excessive concern over pollution could impede their economic development. Indeed, some of these countries have become sanctuaries for industries that find it less expensive to operate in areas with more lax standards. It is apparent that pollution control, regardless of the state of its technology, will become a reality only when people demand it and only when nations are willing to agree on appropriate international standards.

Control over use of resources

      Important also to the future of world conservation is the failure of most societies to exercise adequate controls over land, water, and other resource use. Effective means for controlling land use do not exist in most countries; laws and regulations that permit governments to exercise such control, when existent, often cannot be enforced because of the danger of strong public resentment and resistance. Although it is essential that lands and all other resources be used with a view to preserving their future productivity, this view all too often conflicts with present needs or demands of the resource users. The solution to this conflict is not within the scope of science or technology; instead, it is a question of attitudes and values, and these are less amenable to sudden change than laws or regulations. It appears that economic security and social stability are essential for people to look beyond immediate survival to the well-being of humanity and the future of life on this planet.

Additional Reading

Rachel Carson, Silent Spring (1962, reissued 1982), a popular best-seller that first alerted the general public to the dangers inherent in the widespread use of persistent pesticides; Gino G. Marco, Robert M. Hollingworth, and William Durham (eds.), Silent Spring Revisited (1987), a collection of essays on the topics posed in Rachel Carson's book; Robert L. Rudd, Pesticides and the Living Landscape (1964, reprinted 1970), a scholarly review of the ways in which pesticides enter into the ecological networks in natural and man-made environments, with a discussion of the dangers involved in their continued use; Environmental Quality (annual), a regular report of the Council on Environmental Quality, which reviews the state of the U.S. environment with particular emphasis on problems of pollution; American Chemical Society, Cleaning Our Environment: A Chemical Perspective, 2nd ed. (1978); a report by the Council on Environmental Improvement on the technological state of the art of pollution control; Barry Commoner, Science and Survival (1966), a discussion of how science and technology can cause unanticipated changes in the environment, with particular reference to pollution from nuclear energy; Donald L. Barlett and James B. Steele, Forevermore, Nuclear Waste in America (1985), an investigative report on the environmental hazard; and Scientific Committee on Problems of the Environment (SCOPE), Environmental Consequences of Nuclear War, 2 vol. (1985–86), an international scientific review of the likely effects of nuclear war, prepared by a committee of the International Council of Scientific Unions.Raymond F. Dasmann

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