Environmental HealthDefinition of Terms
Health: State of successful adaptation between human and total environment factors; physical, chemical, biological, and social. It is characterized by anatomical integrity, ability to perform valuable roles, ability to deal with stress, feeling of wellbeing and freedom from the risk of disease and premature death.
Failure of the adaptation is a state of ill health (disease).Environment: is the totality of elements, factors, or conditions in the surrounding of man that can influence the human health and wellbeing. Environment contains elements that are essential for life and for the maintenance of good health.
Life support systems in the environment: are air, food, water, and shelter but potential hazards to life and health do exist in environment also.
Environmental health: all programmes, activities and procedures concerned with the creation and maintenance of condition in the environment that will promote health and prevent disease particularly communicable and occupational diseases.
Public health engineering: is a branch of the civil engineering mainly concerned with water supply and excreta disposal systems.
ECOLOGY OF HEALTHEcology of health is the study of all factors in the environment that affects the health of man.
Any given state of health is a product of interaction (visible and invisible) of enormous number of factors.
These are conventionally grouped into:
Factors related to host such as age, sex, occupation, education, genetics, habits, and other personal characteristics. Smoking for example is an important contributor in the aetiology of lung cancer and ischaemic heart diseases. Many diseases are genetically determined such as sickle cell disease and thalassaemia.
Factors related to disease agent like, type of agent (bacteria, viruses, parasites, fungi etc.) dose and duration of exposure, virulence, and susceptibility to damaging effects of the environment such as heat and light.
Factors related to environment in its physical, chemical, biological, and social dimensions. Environment:
1. assists the survival of disease agent
2. facilitates the transmission of disease agent from the source to a new host and
3. affects the immunity of the host. See the diagram below:
Relevance and Scope
The effects of environment on health may be through:
Decrease the resistance of host to with stand changes.
Increase the hazards or hostile elements in the environment.
Combination of both.
Host resistanceIll health Optimal health
Health hazards and hostile elements in the environmentEnvironmental health is related very closely to other disciplines:
• Public health engineering
• Public health care
• Social sciences
The main interests of environmental health are:• provision of safe domestic water
• safe disposal of wastes
• epidemiology of water and excreta related diseases
• food and milk sanitation
• provision of good housing life, healthy and secure
• control of insect and animal induced infection
• air hygiene and prevention of air pollution
• occupational health
Many of the problems in environment sanitation are dealt with via public health engineers, technicians and other non medical personnel rather than physicians.
The role of doctor is needed to understand the basic principles involved in the health related hazards and diseases in the environment.
Population, Health, and Environment RelationshipsThe fundamental relationship between people and the environment is easy to understand.
The environment responds to basic needs for human health and well-being by supplying:
How are Population, Health, and Environment Related?
Causal links between environmental change and human health are frequently indirect, and displaced in time and space.
Pressures on ecosystems could have unpredictable and potentially severe future impacts on health.
In a recent analysis for the Millennium Ecosystem Assessment, the World Health Organization (WHO) found that the regions facing the greatest present-day health risks from environmental degradation include sub-Saharan Africa, Central Asia, parts of Latin America, and certain areas in South and Southeast Asia.
Serious Problems: Nutrition, Safe Drinking Water and Sanitation, Solid Fuel DependencySome of the most serious problems identified in the WHO analysis include:
Nutrition:Degradation of fisheries and agro -ecosystems are factors in the malnutrition of approximately 800 million people around the world.
At least an additional billion people experience chronic micronutrient deficiency.
Safe Drinking Water and Sanitation:Water-associated infectious diseases claim 3.2 million lives, approximately 6% of all deaths globally.
Over 1 billion people lack access to safe water supplies, while 2.6 billion lack adequate sanitation, and related problems of water scarcity are increasing, partly due to ecosystem depletion and contamination.
Solid Fuel Dependency:About 3% of the global burden of disease has been attributed to indoor air pollution, a major cause of respiratory diseases.
Most of the world's population uses solid fuels to cook and heat, a factor in deforestation.
Examples of Environmental ElementsWater; Uses:
• Domestic uses:
• drinking and cooking
• personal hygiene for washing the bodies and cloths
• environment sanitation utensils and floors and disposal of wastes
• temperature regulation (heating and cooling)
• Industrial and agricultural purposes
• For water to be effective in meeting the requirements of human being, it must be:• equating in quantity
• safe chemically and biologically
• acceptable in taste, color and softness
• continuous supply: no long term interruption to shortage to water and make people either store water or use of unsafe source
Testing the quality of water• turbidity: there are units for turbidity and good water must be not > 5 units
• chemical quality: Cl and N2. Percentage of Cl indicates pollution and presence of N2 = decomposition of inorganic materials
• bacteriological quality: E. coli = fecal contamination (typhoid, Strept, cholera)
• level of chlorinate: 4 ppm
Water related diseases• water related infections: the transmission of infectious agent is related to water:
• water-born infections (faeco-oral infection): all infections transmitted by the faecal oral route; ex: cholera, typhoid, hepatitis, dysentery, …..etc.
• The main preventive measures are:
• improve water quality.
• prevent the use of unsafe sources.
water-washed (shortage) infections: all infections related to poor hygiene but not faeco-orally transmitted and not water-born, usually caused by scanty water supply; ex: skin and eye infections as trachoma.
Prevention by:improving water quantity
improving water accessibility
Water-based transmission diseases: all helminthes which have an aquatic intermediate host; ex: bilharziasis
Prevention by:need for water contact
improve quality of water ( sanitation of environment )
Water-related insect or arthropod vector diseases: all infections transmitted by vectors need water for breeding; ex: trypanosomiasis (Gambian only).
Prevention by:improve service water management
destroy breeding sites
• Water chemistry-related diseases: which result from either excess or shortage of chemical constituents of water; ex: fluorosis
Air pollution: is the condition where the atmosphere can be an excel line core of foreign materials with adverse effects on health and wellbeing of the deicidal and dosage to property of animal and plant life.
This is can find space, initially, to:• chemical changes; ex: CO2 and O2
• physical changes; ex: change in temperature and air movement
• bacterial pollution
• appearance of unpleasant body order
• resource of all organic materials
Sources of air pollution:• incomplete combustion of different fuels, liquid, solids, organic, ex: coal sulfur dioxide ( SO2), CO2, and remained metals
• industrial activities; ex: chemical plants, oil refineries, phosphate fertilizer plants,….etc.
• community and domestic activities and per fond hobbits: ex; smoky
• sewage system
Natural regulatory mechanisms (meteorology):• Water affects air pollution in 2 ways:
• via, precipitation by rain or snow, pollutants are permanently removed from air.
• air motion (wind) which lead to dispersion of pollution via horizontal or vertical movement of air.
Effects of air pollution1. health effects:
a) most of the harmful effects of air pollution are associated with irritant properties and most of the systems are related to the respiratory system and eyes.
b) acute episodes of illness and death result occasionally from exposure to sever air pollution associated with unusual weather conditions.
c) continuous and intermittent exposure to low concentrations of some air pollutants cause irritation and discomfort but no evidence of permanent damage has been found.
d) air pollution may contribute to or aggravate the disease and may be a factor in mortality of persons with chronic respiratory disease, cardiovascular disease and others.
e) poisoning; ex: CO.
f) tuberculosis bacteria may remain suspended in air for hours and can survive for long period in dark dusty space.
2. economic effects on:• animals; ex: milk production
• plants: death or burning
• buildings: damage and corrosion
• sickness absence, road accidents and coast of maintenance of anything
Prevention by:• avoid the production of waste materials wherever possible by change in planned process
• suppression or removal of waste material at the source of production by: absorption , filtration, collection, or complete burning
zoning of industries away from residential areas and prevent new residential ones from establishing close to the industries
control of gases produced by automobiles
Environmental Health (R C PH):Environmental determinants of disease;
Risk & hazard;
The effects of global warming & climate change;
Principles of sustainability;
The health problems associated with poor housing & home conditions, inadequate water supplies & sanitation;
Methods for monitoring & control of environmental hazards (including food & water safety, atmospheric pollution & other toxic hazards, noise & ionising & electromagnetic radiation);
The use of legislation in environmental control;
Appreciation of factors affecting health & safety at work (including the control of substances hazardous to health);
Occupation & health;