UDC 614.7:574.2

V. P. Padalkin, Yu. P. Pivovarov

On the Significance of the Biological Factor in Environmental Pollution

All-Union Scientific Research Institute of Biotechnology, Moscow; Second Moscow Medical Institute named after N. I. Pirogov

In recent years, many specialists have used the biological components of the environment in an effort to understand the numerous changes occurring in it and their consequences for the vital activities of organisms, including humans. However, although the biological components of the environment are more susceptible to human influence than nonbiological components, they are monitored far less extensively than the chemical and physical components (M. I. Budyko).

Considering the problems of environmental hygiene at the present stage of scientific and technological progress and in light of advances in hygiene science, G. I. Sidorenko was the first to emphasize the importance of the biological factor and to introduce it into his proposed framework for environmental quality management. He noted that, under real-world conditions, this factor may act on humans either in combination with physiological and chemical factors or in isolation, both in everyday life and in the workplace, affecting their health.

We wish to draw attention to the role of the biological factor in environmental pollution and its impact on humans, since the concept of the biological factor and the reasons for its current relevance

Diagram 1

Main components of the biological factor

• Microorganisms
• Live
  • Pathogenic
  • Opportunistic
  • Nonpathogenic
• Killed
• Vaccines
• Macroorganisms
• Humans
• Animals
• Birds
• Fish
• RES — sera
• Products of microbiological synthesis
• Toxins
• Enzymes
• Antibiotics
• Amino acids
• Protein–vitamin concentrates
• Organic substances of natural origin
• Pollen from wind-pollinated plants
• Dust of plant origin
• Blue-green algae

…the objectives and prospects for scientific research in this area have not yet been systematized and have received virtually no attention in the literature, although the issue is addressed within the all-Union research program “Scientific Foundations of Environmental Hygiene” and forms a component of the “State Program of Work on Environmental Hygiene for 1976–1990.”

Interest in the biological factor has grown considerably in recent years for a number of reasons. First, the analysis and synthesis of the results of many years of sanitary microbiological research on the effects of chemical pollution have shown that environmental contamination by various chemical substances also affects microflora, an essential component of the biological factor. It alters their properties and their potential effects on humans and disrupts the natural course of microbiological processes in the environment, including self-purification. It has also been established that an increased concentration of chemical substances in bodies of water often contributes to a more prolonged…

Diagram 2

Possible adverse consequences of exposure to the biological factor

Components of the biological factor:

• Microorganisms
• Macroorganisms
• Products of microbiological synthesis
• Organic substances

Humans

• Changes in the etiological structure of infectious diseases
• An increase in the number of diseases caused by opportunistic microorganisms
• Post-vaccination complications
• Emergence of antibiotic-resistant microorganisms that cause disease
• Sensitization of the body
• An increase in the number of allergic diseases
• An increase in the number of hospital-acquired infections
• Disruption of the ecological balance between microorganisms and macroorganisms

Environmental entities (ecological systems, water, air, soil)

• Changes in the physical and chemical constants of the atmosphere
• Changes in the microclimate
• Adverse effects on plant and animal life
• Disruption of natural self-purification processes in water and soil
• Emergence of resistant strains of microorganisms in the environment
• Disruption of the ecological balance between microorganisms and macroorganisms, as well as within microbial associations

…to the survival of microorganisms and sometimes to an increase in their numbers. Second, studies of microbial contamination of the air at a number of industrial enterprises and analyses of disease incidence among their employees indicate that microbial contamination of the air is one of the most important factors adversely affecting workers’ health (L. N. Kurilova and E. V. Garasko). Third, interest in the biological factor stems from the shift of livestock and poultry farming to an industrial basis, the rapid development of the microbiological and biological industries, and the numerous efforts to use microorganisms in various sectors of the national economy, above all to address the problem of food supply. The fourth factor is urbanization. According to D. R. Porter (O. V. Baroyan and D. R. Porter), supplying large cities with water and food, rendering enormous quantities of wastewater harmless, and developing methods and techniques to maintain the necessary balance in nature are impossible without taking into account and using the components of the biological factor.

Finally, there are the problems that have arisen in connection with the successful fight against infectious diseases. The first is the change in the etiological structure of infectious disease incidence (an increase in the frequency of diseases caused by opportunistic patho-

…pathogens, representatives of the normal human microbiota). It is generally accepted that this process is associated with the widespread and often uncontrolled use of antibiotics, especially broad-spectrum antibiotics, immunosuppressants, and other agents. The second problem is the occurrence of post-vaccination complications as a consequence of a broad immunization program using prophylactic preparations of various types and the associated increased sensitization of the body (V. D. Timakov and V. G. Petrovskaya).

What, then, is meant by the biological factor? At present, when the study of this problem is still taking shape, it is not yet possible to provide an exhaustive definition. Nevertheless, on the basis of the available evidence, we understand the biological factor to mean the totality of biological components whose effects on humans or the environment depend on their ability to reproduce under natural or artificial conditions or to produce biologically active substances. As sources of environmental pollution, these components may have adverse consequences for humans, animals, or plants, or exert a negative psychological effect.

The principal components of the biological factor that directly or indirectly affect humans are microorganisms and macroorganisms, products of the metabolic activity of microorganisms and of microbiological synthesis, and certain organic substances of natural origin (Scheme 1). Each of these components, individually or in combination, also affects various elements of the environment: ecosystems, atmospheric air, water, soil, food, dwellings, populated areas, and so on.

The biological factor is a multicomponent system that affects both the environment and humans directly. It should be noted that, compared with chemical and physical factors, the biological factor is more often characterized by a combination of beneficial and harmful effects, both on elements of the environment and on humans. Classic examples include the tremendous success in combating infectious diseases through the development and use of preparations for specific prophylaxis, alongside the resulting problem of post-vaccination complications; and the unquestionable advances in treating many noninfectious diseases and wound infections with antibiotics, alongside the increase in hospital-acquired infections caused by microorganisms that have developed resistance to these drugs. Scheme 2 shows the most characteristic adverse consequences of exposure to components of the biological factor.

Scheme 3. Structure of biological pollution

In view of these problems, it is important above all to clarify—and in some cases study in detail—the mechanisms by which biological pollution affects bodies of water and soil. Such pollution can create conditions conducive to the growth of pathogenic microorganisms in the environment. Moreover, the intensive introduction into soil and bodies of water of certain microorganisms used in microbiological synthesis or pest control can disrupt local ecosystems, potentially impairing self-purification processes, reducing soil fertility, and causing other changes.

Examination of the structure of biological pollution is an issue of great urgency. Since the biological factor encompasses a wide range of components, we believe it is reasonable to divide biological pollution into two principal groups (diagram 3). The first comprises natural processes that under certain conditions can act as sources of biological pollution; the second comprises artificial processes (the industrial group of sources of biological pollution of the environment). The relative importance of the various types of biological pollution differs. The expanding scope and scale of microorganism use, rapid advances in industrial microbiology and geomicrobiology, the industrialization of livestock and poultry production, and the consequent establishment of large pig and cattle complexes, poultry plants, and industrial dairy farms have brought these industries to the forefront of biological pollution and presented sanitary microbiology with a number of serious problems concerning protection of the human environment.

The high concentration of livestock at such complexes and new production technologies result in the generation of 3,000 to 5,000 m³ of highly concentrated effluent per day. This effluent poses a sanitary and epidemiological hazard because it contains pathogenic microorganisms, helminth eggs and larvae, as well as various preservatives, antibiotics, aldehydes, and a complex mixture of organic substances. The ventilation systems of a cattle complex housing 10,000 animals, for example, release up to 1,310 billion microorganisms into the atmosphere each day. A bacteriological study of atmospheric air in the vicinity of a pig complex showed that at distances of 100–200 m from it, the number of microbes per 1 m³ of air was 125–1,000 and 150–1,825, respectively. Bacterial contamination per 1 m³ of air inside the buildings of a cattle complex and on its grounds ranged from 50 to 20,000 microorganisms (M. A. Mironenko et al.). The release of large numbers of microorganisms into the air from both industrial livestock complexes and microbiological industry facilities may adversely affect the human body, but this question has not yet been adequately studied.

As hygienic research and practice show, the most pressing issue is the problem of environmentally hazardous waste from such operations. The number and capacity of livestock complexes are known to be growing rapidly throughout the world. Thus, whereas manure production across our country currently amounts to 200 million tonnes per year, by 1980 it will reach 400 million tonnes. The volume of livestock waste already considerably exceeds that of municipal wastewater. In the Federal Republic of Germany, for example, the amount of waste from livestock enterprises is five times greater than that of municipal wastewater; in the United States it is ten times greater, and so on. The problem of disposing of waste from livestock complexes arises because this waste has qualitatively new properties: it consists of liquid manure with a moisture content of 90% or more. M. A. Mironenko et al., in a detailed examination of environmental protection, note that such effluent contains typical and atypical cultures of salmonellae, enteropathogenic Escherichia coli, Proteus, Pseudomonas aeruginosa, and other microbes. One litre of untreated effluent may contain from several dozen to thousands of viable helminth eggs and protozoan cysts. Such effluent must be rendered harmless, but where, how, and by what method remains unknown, since the question has not been sufficiently studied and requires urgent and extensive scientific investigation.

In assessing exposure to biological pollution quantitatively, the effect of a biological agent depends to a considerable extent on many variable characteristics that are less important in exposure to a chemical or physical agent. These variables include the level of pre-existing immunity, the degree of sensitization, the state of protective mechanisms such as local inflammatory processes, the complexity of transmission, and insufficient knowledge of doses infectious to humans. The last of these deserves particular attention in scientific research aimed at developing and substantiating methods for establishing maximum permissible concentrations of biological pollutants. The difficulty lies primarily in the exceptionally complex interactions between microorganisms and the host organism and in the varying sensitivity of the organism to products of microbiological synthesis and other biologically active substances—essential components of most types of biological pollution. An analysis of the scientific literature showed, particularly with respect to microorganisms, that the number of microbes required to cause disease depends on a number of factors and is difficult to determine. The literature indicates that the doses required for disease to develop

microorganisms can vary over an extremely wide range—from single units to several million.

The present paper does not claim to provide a comprehensive treatment of the problem of the biological factor. A discussion of this subject would be valuable and would promote further work on the most important issues facing environmental health.

Conclusions

1. The biological factor is important in its own right in the system of environmental quality management.
2. Successfully resolving issues related to the biological factor requires comprehensive research involving collaboration among teams of scientists from different specialties, with a high level of organization.

References

Baroyan, O. V., and Porter, D. R. International and National Aspects of Modern Epidemiology and Microbiology. Moscow, 1975.

Budyko, M. I. Global Ecology. Moscow, 1977.

Kurilova, L. N., and Garas’ko, E. V. Gig. truda, 1978, no. 7, pp. 23–26.

Mironenko, M. A., Yarmolik, I. F., and Kovalenko, A. V. Sanitary Protection of the Environment in Areas with Industrial Livestock Complexes. Moscow, 1978.

Sidorenko, G. I. Gig. i san., 1978, no. 10, pp. 9–15.

Timakov, V. D., and Petrovskaya, V. G. Zh. mikrobiol., 1977, no. 9, pp. 3–11.

Received October 15, 1979.

Role of the Biologic Factor in Environmental Pollution

V. P. Padalkin, Yu. P. Pivovarov

Discusses the role of the biologic factor in the system of environmental quality monitoring services. Points out the main components of the biologic factor and the possible adverse effects of these on environmental objects, including man. Presents the structure and a possible classification of biologic pollution of the environment and indicates lines of research particularly relevant to environmental health.