Экологическая медицина = Ecological medicine. Учебное пособие

INTRODUCTION

Modern conditions of social development are characterised by an active human interference with the environment. The advent of new technologies, industries, and intensive agriculture are associated with the increasing use of chemical compounds, physical and abiotic factors. There are currently 4 million toxic substances registered in the external environment and this number continues to increase annually by 6,000. The human body receives about 100 thousand xenobiotics, and every fourth inhabitant of the Earth is suffering from allergies and autoimmune diseases, more than 80% of diseases are caused by environmental stress. The most severe effect of biosphere pollution is the genetic consequences. Nowadays, there are more than 2,500 types of impairments or disabilities at the gene and chromosomal levels. Every year the proportion of the social component in the comprehensive assessment of the health of modern human is increasing. Stresses are regarded as the leading risk factor negatively affecting human health and contributing to the emergence of new forms of environmental illnesses. Various forms of peculiar non-specific diseases have appeared over the recent decades. Some of these diseases are manifested in the form of extreme fatigue, or “living death.” The concept of “eco fatigue” has been introduced into the scientific discourse.

Under these conditions, the importance of training doctors to carry out measures to protect and preserve the health of the population becomes all the greater. The formation of an integrated and harmonious system of knowledge and thinking in this area is a necessary component for a fullfledged medical practice. This will enable the specialist to take into account the effect of environmental factors and lifestyle on the individual’s health and adequately adjust the examination and treatment of patients. The knowledge gained when studying environmental medicine is necessary for carrying out targeted preventive measures among critical groups. Teaching Environmental Medicine makes it possible to develop an ecologically-ori- ented thinking and produce certain results while studying clinical specialties.

With the introduction of medical and environmental monitoring, there is a real opportunity to combine the results of many scientific disciplines involved in ecology and medicine, as well as to justify the overall system of knowledge about the protection of nature and human health – medical ecology or environmental medicine.

The task of environmental medicine is to identify patterns (trends) in the morbidity due to the peculiarities of complex influence of environmental factors and to develop considered recommendations and productive environmental and health measures to protect against the adverse effects and factors.

4

Chapter 1

FUNDAMENTALS OF ENVIRONMENTAL MEDICINE

Motivational characteristic of the topic. Environmental medicine, which stems from general ecology and environmental hygiene as a complex interdisciplinary direction in medicine, focuses on the interaction and interdependence of several factors (metoclimatic, geo-ecological, demographic, industrial, domestic, etc.) of the environment and public health. Therefore, it is essential to become aware of the relationship between the anthropogenic impact on the environment and human health. Knowledge of these mechanisms will allow implementing a set of measures to prevent environmentally dependent and related diseases.

With such rapid environmental pollution, the human being both as the initiator of the transformations in nature and the representative of the biosphere animal world is exposed to environmental hazards, and has to constantly mobilize their compensatory-adaptive mechanisms the reserves of which may eventually be depleted. The doctor must carry out individual and population prevention of ecologically dependent and related diseases, effectively pursue training of the population living in conditions of high environmental risk. Under these conditions only will there be the possibility of successful treatment and prevention of patients as well as the protection of the population health.

The objective:

1.  To understand the role and place of ecology in the modern knowledge system, to get acquainted with the specifics of the ecological situation in the Republic of Belarus.

2.  To get an insight into the regularities that influence the health of natural and socio-ecological factors.

Tasks:

1.  To master the theoretical framework of environmental medicine, including definitions and research vocabulary.

2.  To consider crucial risk factors to the human habitat, and their role in morbidity.

3.  To master the skills of searching the relationships between the occurrence of diseases and the effect of various environmental factors, to recognize their environmenal conditioning.

5

Requirements for students’ initial knowledge level. To fully master the topic of the chapter, a student should revise the relevant material from the following disciplines:

1.  Microbiology, Virology, Immunology: “Environmental factors as a cause of modifications and mutations, and selection factor of modified forms of microorganisms. Intraspecific, interspecific relationships”.

2.  General Chemistry: “Distribution of chemical elements in nature. Biogenic elements and their compounds as environmental factors”.

3.  Medical Biology and Genetics: “Ecology as a science, its tasks, importance for modern medicine. Genetic hazards of environmental pollution. Biological and social aspects of human adaptation to living conditions”.

4.  Medical and Biological Physics: “Characteristics of physical properties of air”.

5.  The Normal Human Physiology: “Physiological mechanisms of adaptation and their role in the life Support of the organism”.

Review questions from related disciplines:

1.  What is the importance of ecology as a science for modern medicine?

2.  V.I. Vernadsky’s theory about noogenesis and noosphere.

3.  General characteristics of chemical elements and their compounds. 4.  General characteristics of physical factors.

Questions related to the topic of the chapter:

1.  Environmental medicine, objective, tasks, subject of study, research methods.

2.  Environmental factors, classification.

3.  Types of impact and patterns of influence of environmental laws. 4.  Medical prevention and its role in maintaining human health in an

environmentally unstable world.

LEARNING MATERIAL FOR THE CHAPTER

The object under the study of Environmental Medicine is the environment, spatial and territorial anthropo-ecological system, and the research subject is their properties which are manifested in the influence on the health, environmental health prerequisites and diseases.

The objective of environmental medicine is to prevent harmful effects of the polluted environment on the body and the human population, i.e., to create favourable conditions for human life, activity, and society.

6

Environmental medicine studies the following issues:

yyIndicators (parameters) of various functions and systems of the body as criteria for assessing the quality of the environment.

yyThe role and place of environmental factors, its impact on health (pesticides, radionuclides, mineral fertilisers, other chemicals, electromagnetic fields, etc.).

yyEnvironmental aspects of the combined effect of negative and positive environmental factors on people.

yyAssessment of medico-ecological risk and medico-ecological capacity of landscapes.

yyDevelopment and justification of medical and environmental standards.

The well-known American biologist Barry Commoner explained in a very clear and simple form the basic laws of ecology that operate in the world around us:

1.  “Everything is connected with everything else”.

Changes made in one component of the ecosystem can lead to adverse consequences in the functioning of the entire ecosystem. Reasonable human activity is not always able to foresee the consequences of its activities.

2.  “Everything must go somewhere”.

Household and industrial waste, getting into the natural environment, does not disappear without a trace. Nature has fewer and fewer reserves of strength to cope with the processing of pollutants, and this fact is the main factor destroying the natural ecosystems of the biosphere and having a harmful effect on humans.

3.  “Nature knows best”.

Human society transforms nature by disrupting natural processes. The consequences of transformations designed to improve the human environment make it less and less favourable for the life of all creatures on Earth, and gradually for humans themselves.

4.  “There is no such thing as a free lunch”.

Human beings cannot endlessly waste natural resources and pollute the environment. Mankind must realise that any actions are paid for by the consumption of natural resources. Therefore, all kinds of human interaction with nature must be evaluated in terms of preservation of natural ecosystems.

Currently, one of the most accessible and widespread areas of study of various aspects of the environmental impact on public health is the factor approach, i.e., the identification of risk factors directly leading to “environmental” diseases.

7

Environmental factor is any element of the environment that can have a direct or indirect effect on a living organism at least at one of the stages of its individual development, or any environmental condition to which the organism responds with adaptive reactions.

Classification of environmental factors: 1)  abiotic:

physical

yyclimatic and meteorological (temperature, air movement, precipitation, heavy rains, hurricanes, droughts, etc.);

yyorographic (atmospheric rarefaction, avalanches, landslides, mudslides);

yygeophysical (geomagnetic storms, earthquakes, tsunamis, gravitational and thermal anomalies, electromagnetic fields, noise, vibration);

yyhydrographic (floods, swamping, drainage, sub-thawing, water supply sources, composition of surface and underground waters, their ability to self-purify and transfer pollution);

yygeological (rock composition, tectonic faults, radiation, minerals). chemical

yycomponents of water, air, soil; yyacidity;

yyimpurities, etc.;

yychemical pollution of plants, animals, food and other objects.

2)  biotic:

yyfauna (poisonous and dangerous animals; animals as reservoirs and carriers of pathogens; animals as food resources);

yyflora (poisonous and medicinal plants, plants as food resources, air purifiers and bioindicators of environmental impact);

yymicroflora (air, water, soil, animals, plants, food, objects); yybiological components (toxins, proteins, metabolic products); biocenoses (natural foci of diseases).

3)  socio-economic:

yypopulation (demography, settlement, urbanisation, migration, gender, age and professional composition, culture, lifestyle, customs, confessions, material well-being);

yyterritorial organisation of society, economic use of land; yymunicipal / utility factors;

yysanitary and hygienic condition and the epidemic status; yypsychotraumatic factors (stressors, environmental fatigue); yymedical and veterinary services, infrastructure.

8

Effects of environmental factors on organisms:

1)  stimuli – contribute to the emergence of adaptive physiological and biochemical changes;

2)  limiters – change the geographical distribution of organisms due to the impossibility of existence in these conditions;

3)  modifiers – cause morphological and anatomical changes in organisms;

4)  signals – indicate changes in other environmental factors.

General patterns of environmental factors:

1.  The law of optimum (Shelford’s law of tolerance): “Any ecological factor has limits of positive influence on living organisms. The distance between the minimum and maximum values of the factor is called the ecological valence or tolerance of the organism”.

2.  The law of ecological individuality of species, formulated in 1924 by the Russian botanist L.G. Ramensky: “The ecological characteristics of different species do not coincide; each species is specific in its ecological capabilities”.

3.  Liebig’s law of the minimum: “The most significant factor for the organism is the one that deviates most from its optimal value”.

4.  The law of ambiguous action: “The action of each environmental factor is ambiguous at different stages of the development of the organism”.

5.  The law of direct and indirect influence of factors on organisms. 6.  The law of interaction of ecological factors: “The optimal zone and

limits of endurance of organisms towards any factor may shift depending on what other factors join the overall influence” (Table 1.1).

Ecopathological conditions are understood by many authors as changes occurring in the body (from mild and not having distinct clinical symptoms to severe diseases), caused by the influence of adverse environmental factors (Table 1.2).

Today, there exist environmental diseases which are related to the impact of environmental factors which increase the risk of a disease and affect the course of an existing pathology.

Circulatory system diseases:

1)  atmospheric air pollution with sulphur oxides, carbon, sulphur compounds, fatty acids, ethylene, propylene, hydrogen sulphide, nitrogen, butylene, nitro compounds, mercury, lead, iron, cobalt, manganese, etc.;

2)  living conditions;

3)  noise level;

4)  electromagnetic fields;

9