Environmental Health LECTURE NOTE PDF

**LECTURE NOTE ON** **ENVIRONMENTAL HEALTH** **LECURER: ADELANI TIJANI RN, PhD, FWACN** **NOT FOR SALE** **Preface** This booklet is an extraction from the **Environment and Health** textbook of the Nigerian Conservation Foundation published in 1995. The book, which was succinctly compiled by O...

**LECTURE NOTE ON** **ENVIRONMENTAL HEALTH** **LECURER: ADELANI TIJANI RN, PhD, FWACN** **NOT FOR SALE** **Preface** This booklet is an extraction from the **Environment and Health** textbook of the Nigerian Conservation Foundation published in 1995. The book, which was succinctly compiled by Olaniran N.S, Akpan E.A, Ikpeme E.E and Udoffa G.A, is a more or less an encyclopedia on issues of environment and health in developing nation. Most of the topics dwell extensively on how the nature of the Africa environment affects the health status of the populace and various ways to control the environment for healthy living were analyzed. The book summarily addresses the syllabus of the NSG 309 course on Environmental Health for BNSc students of LAUTECH Ogbomoso. It is based on this that the aspects that are very relevant to the course were extracted as lesson note for our students for the year 2013. The booklet is not meant for sale to the students or the general populace in or outside our campus. To this end, the lecturer quite appreciate the good work of the authors earlier mentioned not only for the thorough job done but also for the express permission granted for the reproduction of the book for academic purposes. I therefore charge the students to consult the original book - **Environment and Health** of the Nigerian Conservation Foundation whenever they need more information on the aspects extracted or on any other issues not covered in this booklet. The students should also study very well not only for passing the end of course examination but to also put into practice whatever knowledge they might gain in the book for the betterment of the Nigerian environment. **INTRODUCTION** Human environment is closely linked with the quality of life enjoys. Man's physical and biological environment play tremendous role in the quality of his social life. In many occasions too, where man lives determines his socioeconomic and health status. Tremendous successes have been achieved through the global campaign through environmental health education to create a healthier environment in many developed nations but a large proportion of the world's population in sub Sahara Africa are still ignorant of and are not sufficiently sensitized to issues relating to environmental conservation, environmental degradation (pollution) and their impact on human health, welfare, and indeed, survival of the human race. In Nigeria, haphazard development, rapid urbanization and industrialization, uncontrollable population growth rate, deforestation, poverty, soil erosion, poor municipal solid wastes management, lack of adequate potable water supply and basic sanitation, and negative socio-cultural values are few examples of human activities or conditions that degrade the environment and pose a threat to human health. The link between environment and health is fairly understood by the average person in most developed nations of the world. In Nigeria however, the level of environmental awareness is still low and the basic knowledge and understanding of the relationship between environment and health is poor. **ENVIRONMENT** A conventional definition of the term "environment" is immediate surrounding all the conditions, circumstances and influence surrounding and affecting an organisms or a group of organisms" (Mc Kechinie, 1983). To an environmentalist, environment comprises the land, water, air and other physical structures observable around an organism or a group of organisms. However from an ecological viewpoint, environment is simply an ecosystem. An ecosystem is the basic functional unit in ecology and the term refers to any natural of artificial environment where living things (i.e. biotic components) are interacting with non-living things (i.e. abiotic components). Thus, man as a unit within an ecosystem interacts with, and is dependent on other living things as well as the physical, chemical and socio-cultural factors in the ecosystem. It should be noted that the concepts of ecosystem emphasizes dynamic interactions and interdependencies between the biotic and abiotic components of an environment. Examples of ecosystem include planet Earth, a cow pasture, a lake, river or pond, a family-room aquarium, a rocky ocean shore, the uterus (womb), a factory and a school. **Nature and Types of Environment** An environment may be physical, biological or socio-cultural in nature. The physical environment comprises air, water, land and other structure observable around us (non-living things). These components of the physical environment are critical natural resources on which man's socio-economic development and health depend. As a matter of fact, sustainable development in Nigeria can only be achieved with rational management and use of these natural resources in such a manner that the needs of the current generation are satisfied while ensuring that future generations will not inherit a degraded environment with little or no natural resources. The biological environment comprises all living things including man, animal (fauna) and plant (flora) species (i.e. Biological Diversity), micro-organisms, pathogens (disease-causing organisms) and parasites. Man depends on other animals plants for his main food sources, shelter and for medicinal herbal preparations. Human activities such as hunting, fishing and farming are impossible without a high biological diversity index. Negative environmental conservation practices have the greatest impact on the biological environment; for example, desertification, deforestation, draught, flooding, farming and even extinction of endangered plant and animal species. Man, as an individual or in a family, is a social animal. The socio-cultural environment has a great impact on man's behaviour, religious beliefs, traditional beliefs and practice, and socio-cultural norms and values. Most people acquire these values during their formative years in the home, an important micro environment relative to the larger macro environment described as society. The socio-cultural environment is a major determinant of positive or negative conservation practice in a given society. Whereas the physical and biological environment may be considered as natural, the socio-cultural and occupational environments are man made. **Overview of the Nigerian Environment** The Nigeria environment poses a great danger to human health. Agricultural practice that are not environment-friendly (e.g. sole cropping and indiscriminate use of agrochemicals like insecticides, herbicides and inorganic fertilizers), nomadic pastoralism (i.e. cattle sheep and goat rearing), mining of metals and minerals (e.g. coal and tin), crude oil (petroleum) exploitation, and industrial pollution of soil, air and water are few example of current human activities in Nigeria that may adversely affect the environment and human health. Over population, negative socio-cultural values, rapid urbanization and haphazard industrialization have resulted in indiscriminate dumping of domestic and industrial hazardous solid and liquid wastes with reckless abandon in urban areas. The same socio-cultural and economic conditions above have resulted in poor sanitary conditions, including inadequate quantity and quality of drinking water. **National Policy on the Environment** The Federal Environment Protection Agency (FEPA) (1989) has published "National Policy on the Environment". The goal of the policy is to achieve sustainable development in Nigeria by ensuring proper management of the environment in order to meet the needs of the present and future generations. Specifically, the policy seeks to: \(i) Secure for all Nigerians a quality of environment adequate for their health and well-being; \(ii) Conserve and use the environment and natural resources for the benefit of present and future generations; \(iii) Restore, maintain and enhance the ecosystems and ecological process essential for the functioning of the biosphere to preserve biological diversity and the principle of optimum sustainable yield in the use of living natural resources and ecosystems; \(iv) Raise public awareness and promote understanding of essential linkages between environment and development and to encourage individual and community participation in environmental improvement efforts; and \(v) Co-operate in good faith with other countries, international organizations/agencies to achieve optimal use of trans-boundary natural resources and effective prevention or abatement of trans-boundary environmental pollution. In the same document, FEPA (1989) listed the strategies (Specifications in major sectors and problem areas of the environment) for achieving the five (5) objectives above as follows: i\) Protection and enhancement of the health and well being of the human population, the most valuable national resource because humans make significant positive or negative impact on the natural resources and non-human environment; ii\) Proper planning, improvement and management of Land Use and Soil Conservation to among other reasons, control or prevent soil erosion, deforestation, desertification, flooding and pollution; iii\) Planning, development, improvement and management Conservation and proper management of water Resources and efficient Water Usage to among other reasons, and specify water quality pollution and wastage, and specify water quality criteria for different water uses; iv\) Enhancement of conservation and environmentally sound management practice in *Forestry, Wildlife* and *Protected Areas;* v\) Environment assessment and monitoring of Marine and Coastal Area Resource to, among other reasons, sustain ecological diversity and productivity; iv\) Environmentally sound management of Domestic and industrial Wastes (solid and liquid) to ensure adequate sanitation through proper treatment and disposal of hazardous biological wastes; vii\) Environmentally sound management and control of Toxic Hazardous Substances (mainly chemicals and radiation); viii\) Evaluation and monitoring of Mining of Mineral Resources to, among other reasons, ensure the safety of miners and the ecosystem: ix\) Environmentally sound management of Agricultural Chemicals such as fertilizers and pesticides to minimize their adverse impacts on human health and the environment: x\) Rational Energy Production and Use xi\) Prevention or control (abatement) of *Air Pollution:* xii\) Prevention or control (abatement) of Noise Pollution xiii\) Protection of workers health through sound Occupational Health and Safety programmes; and xiv\) Environmentally sound management and protection of *Settlement, Recreational Space, Greenbelts, Mon*uments and *Cultural Property.* In order to achieve the goal and objectives in the policy, FEPA will among other things:. i\) ensure *Public Participation* in its environmental protection activities; ii\) Establish effective Institution and Linkages within and among the various tiers and levels of government-Federal, State and Local Government; iii\) Institute a legal Framework for promulgating appropriate environmental protection laws; iv\) Ensure effective implementation of International *Treaties and Obligations*; and v\) Monitor and evaluate the provisions of the policy by for example, issuing annual "State of the Environment" reports. **HEALTH** From time immemorial, man has always had some concern with finding solutions to health problems. There is always the concern about socio-economic effects of ill-health or disease on an individual's life; and of course, the possibility of the dreaded event know as "death" is also always on people's minds. The clichés "prevention is better that cure" and "Health is wealth" could also have arisen from this age-long concern for health. What then is this very important human attribute called "Health"? Health is indeed a relative term; it is a state of man's physical body and mind as perceived by a n independent observer or by the person himself or herself. A condition perceived as normal or healthy by someone may be abnormal in another person's view. In order to harmonise the disparate views on health, attempts have been made to offer definitions of health. The preamble to the constitution of the world health organization (WHO, 1948) describes health as "a state of complete physical, mental and social well-being, and not merely the absence of disease or infirmity". The WHO description relies mainly on phenomena that indicate levels of absence of health and most of the parameters cannot be easily measured. Another criticism of this definition is that it describes an ideal state that is rarely achieved in the real world. Last (1987) defines health as "a state of equilibrium between humans and the physical, biological and social environment, compatible with full functional activity." This is a definition of health from an ecological, holistic perspective. It recognizes the interactions and interdependencies of man and the environment in a complex ecosystem. In another definition by stokes et al, (1982) health is "a state characterized by anatomic integrity, ability to perform personally valued family work and community roles; ability to deal with physical, biological and social stress; a feeling of well-being and freedom from disease and untimely death." This description of health emphasizes aspects that can be measured but these attributes have some inherent flaws. For example, it is difficult to accurately measure "ability" to cope with various stress or "a felling" of well-being. For our purpose therefore, **the ecological definition is apt, relevant and comprehensive** in evaluating the relationship between environment and health. **National Policy on Health** The federal Ministry of Health and Social Services published the current National Policy on Health in December, 1986. The policy is based on the national philosophy of social justice and equity and its goal is to achieve health for all Nigerians by the year 2000 through the Primary Health Care (PHC) system. In article VI of Alma-Ata Declaration of September 12^th^, 1978, PHC is defined as "essential health care based on practical, scientifically sound and socially acceptable methods and technology made universally accessible to individuals and families in the community and through their full participation and at a cost that the community and country can afford to maintain at every stage of their development in the spirit of self-reliance and self-determination. (WHO, 1988). PHC includes at least health education on prevailing local health problems in a community and methods of preventing and controlling them; promotion of food supply and adequate nutrition; an adequate supply of potable, safe water and basic sanitation; maternal and child health care, including family planning; immunization against the major infectious disease; prevention and control of locally endemic disease, treatment of common disease and injuries; and provisions of essential drugs. The policy identifies three (3) levels of care and a referral system linking all the three levels. The primary health care level (first level of contact with National Health care system) which incorporates traditional medical care, provides general health services of p reventive, curative, promotive and rehabilitative nature. The provision of care at this level is mainly the responsibility of local government with technical support of state Ministries of Health. The secondary health care level provides specialized services to patients referred from the primary health care level through the general hospitals. Secondary health care is available at the district, division and zonal levels of the state. The tertiary health care level provides highly specialized services through university teaching hospital and other specialist hospitals such as orthopaedic, eye, infectious disease, maternity and pediatric hospitals which are fairly evenly geographically distributed in all the four health zones in the country (i.e zones A,B, C and D). The policy specifies the roles and functions of Federal, State, and Local Governments and outlines PHC strategies which include community mobilization, community participation and involvement, intersectoral collaboration, health man power development and development of a national health information system. **Indicators of Health Status and Environmental Quality** A rational evaluation of health in relation to the environment requires a set of indicators (pointers, parameters). Most of the physical, chemical, biological and socio-cultural factors in an environment may cause injury, ill-health, diseases, disability or death. There is an indicator for each of these likely outcomes of man-environment interactions because it is not feasible nor necessary to develop indicator for each likely event, health professionals usually use crude birth rate (CBR), crude death rate (CDR), infant mortality (death) rate (IMR) and life expectancy at birth (LEB), among others, as rough estimates of health status of a community or country in relation to environmental quality. The values for these indicators computed by Population Reference Bureau (1992) for selected countries are shown in Table 1. Technologically developed nations with stronger economies and well established public health and medical care system fare better than Nigeria, especially in levels of infant mortality (infants are a vulnerable group) and life expectancy at birth. Although the emphasis here is on how environmental factors affect human health, there are also indicators of environmental degradation. Examples are levels of air, water and soil pollution or contamination, degree or extent of desertification, deforestation, acid rain and soil erosion. Specific indicators used for assessing water pollution include fecal coliforms, Biochemical Oxygen Demand in 5 days (BOD~5~ 20^0^ C), Chemical Oxygen Demand (COD), and Biodiversity Index (BI) for an ecosystem, specific fauna (e.g. phosphates and pesticides). A polluted, degraded environment (i.e., poor environmental quality) is a threat to human health and indeed, to human survival. **TABLE 1: Indicators of Health Status** **2.4 ENVIRONMENTAL HEALTH HAZARDS** The few examples of human activities presented above (section2.3) clearly indicate that man's ability to tinker with or dominate his environment has obvious consequences is the creation of Source: Population Reference Bureau, (1992) **ENVIRNMENTAL HEALTH HAZARDS** An environmental health hazard is any substance, object, equipment, agent, condition, human behaviour or factor that is capable of causing injury, disability, disease or death in humans or has the potential for polluting or degrading the environment. However, some misconceptions about the meaning of "hazard" should be cleared. The world hazard is not synonymous with injury or disease if and only if certain environmental conditions exist. Few examples are given to illustrate this point. A parked vehicle is a hazard but will not cause harm until it is recklessly driven by a drunk driver or there is a break failure. A refuse dump is a hazard but will not cause harm or disease until infected rodents and mosquitoes that breed in the refuse transmit the diseases to humans. Human feaces, a very hazardous waste, cannot cause ill health unless a person ingests water and food contaminated by faeces. Injury from a sharp, pointed object (e.g. a kitchen knife which is a hazard) can only occur if there is an accident through misuse or carelessness. It must therefore be emphasize that a hazard is not injury or diseases although the terms are usually erroneously used interchangeably. **Classification of Environmental Health Hazards** Environmental health hazard can be classified into four broad groups depending on nature or type. The groups are physical, biological, Chemical and Sociocultural/Psychosocial. Most of the physical hazards are easily observable, detectable and measureable and are found in our immediate surroundings, but mainly in the occupational and home environments. Some of the biological hazards cannot be seen by the naked eye (e.g. pathogens) but most are present in all components of the environment. Biological hazards are detectable and measureable using microbiological or biological techniques. Chemical hazards are the most numerous and complex. Most are found in the work-place and are measurable using sophisticated laboratory techniques. Socio-cultural hazards/factors are the most difficult to detect and measure because they are usually ill-defined, amorphous attributes of man. Examples of hazards in each of the four groups are listed in Table 2. **Table 2: Classification of Environmental Health Hazards** **Physical** **Biological** **Chemical** **Socio-cultural/Psychosocial** ------------------------ ------------------------------------------------------------------------ ---------------------------------------------------------------- ------------------------------------------------------------------------ 1\. Noise 1\. Pathogens (e.g. bacteria, viruses), 1\. Pesticides (e.g. insecticides 1\. Poverty 2\. Dusts Protozoa, rickettsia and helminthes) Herbicides and fungicides 2\. Cultural Beliefs and Practices 3\. Heat 2\. Sewage 2\. Inorganic Fertilizers 3\. Religious Beliefs and Practices 4 Cold 3\. Diseases Vectors (e.g. mosquitoes, sandfly, tsetsefly and blackfly 3\. Heavy Metals (e.g. lead mercury and cadmium) 4\. Education 5\. Vibration 4\. Venomous Snakes 4\. Acids 5\. Occupation 6\. Pressure 5\. Bees 5\. Bases 6\. Lifestyle 7\. Ionizing Radiation 6\. Scorpions 6\. Asbestos 7\. Unhealthy Habits (e.g. cigratte smoking, drug addiction and sexual promiscuity) 8\. Open Refuse Dumps 7\. Man 7\. Gases (e.g. carbon monoxide, sulphur dioxide, and Aumonia) 8\. Marital/ Family Problems. 9\. Motor Vehicle 9\. Stress **ENVIRONMENTAL MEDIA** Exposure by man to environmental health hazards is normally through a medium. Exposure can be by inhalation through nose, ingestion by mouth or absorption through the skin. The pathways in the environment through which hazards must pass before impacting on human health are collectively described as environmental media. The environmental media are the air we must breathe, the food we eat, the water we drink and use for other purpose, the soil (land) which we cultivate, inanimate objects in our environment (i.e. fomites), the occupational and socio-cultural environments. **Health Impacts of Selected Environmental Hazards and Media** 1. **Air Pollution and Health** Air, specifically oxygen is required by every human being for survival since low level of oxygen in blood (i.e. hypoxia) for a few minutes rapidly leads to death. Consequently, Pollution of the air we must breathe in every minute has serious adverse impact on human health. For our purpose, air pollution is defined as the presence in air of excessive amounts of substances (pollutants) that may impair human health or the environment through human activities or from natural sources. It is important to note that although man is the major polluter of the air, nature also contributes to air pollution and because of this fact, there will always be some natural (background) levels of some air pollutants even if man has not appeared on planet Earth. Table 3 shows sources of air pollutants in Nigeria and their environmental/health impacts. 2. **Water Pollution and Health** Water pollution is the presence of excessive amounts of a hazard (pollutant) in water such that it is no longer suitable for drinking, bathing, cooking and other uses. Thus, a desired water quality depends on the intended use. Consequently, water to be used for drinking (i.e. potable water) must be of highest possible quality and must be tasteless, odourless, colourless, not salty and free of pathogens and toxic chemicals. Water is next only to air as a necessity of life. Although the southern Region of Nigeria is well-watered with numerous fresh water in streams, rivers, lagoons, etc. the quantity and quality of water required for drinking, bathing, cooking and other domestic uses are grossly inadequate. Most Nigerian women and children spend hours and trek long distance every day is search of the scarce commodity water, in rural and urban areas. Because many Nigerian spend a great proportion of their time searching for water, once they get some, they rarely pay attention to the quality of the water. Yet both the quantity (volume) and quality of water impact on human health. It is however important to note that the quality, more than quantity affects health. **Table 3. Sources of Air Pollutants in Nigeria and their Health/Environmental Impacts** +-----------------------+-----------------------+-----------------------+ | **Pollutants** | **Source (s)** | **Health/Environmenta | | | | l | | | | Impact (s)** | +=======================+=======================+=======================+ | 1\. Dust (solids) | 1\. Cement Factories | 1\. Respiratory | | | | Diseases | | | 2\. Vehicular | | | | Traffic | 2\. Irritation of | | | | Upper Respiratory | | | 3\. Harmattan | Tract | | | | | | | 4\. Windstorm | 3\. Trauma to Eyes | | | | (Foreign Bodies in | | | 5\. Bush Burning | Eyes) | | | Forest Fires | | | | | 4\. Reduces | | | 6\. Refuse Burning | Visibility | | | | | | | 7\. Firewood Burning | | | | | | | | 8\. Dusty | | | | Occupations/ other | | | | Industries | | | | | | | | 9\. Volcano | | +-----------------------+-----------------------+-----------------------+ | 2\. Total Suspended | 1\. Combustion | 1\. Respiratory | | Particulates (Solid | | Irritant | | or Liquid) | 2\. Industrial | | | | Processes | 2\. Corrodes Metals | | | | | | | | 3\. Reduces | | | | Visibility | +-----------------------+-----------------------+-----------------------+ | 3\. Sulphur Dioxide | 1\. Oil Refineries | 1\. Respiratory | | | | Irritant | | (SO~2~)-gas | 2\. Natural Gas | | | | Flaring | 2\. Corrodes Metal | | | | and stones | | | 3\. Coal Burning | | | | | 3\. Damage Textiles | | | 4\. Volcano | | | | | 4\. Toxic to Plants | | | | | | | | 5\. Precursor of | | | | Acid Rain | +-----------------------+-----------------------+-----------------------+ | 4\. Carbon Monoxide | 1\. Motor Vehicle | 1\. Aggravates | | (CO)-gas | Exhaust | Cardiovascular | | | | Diseases | | | 2\. Natural Gas | | | | Flaring | 2\. Impairs Mental | | | | Processes | | | 3\. Any Type of | | | | Incomplete | 3\. Reduces Amount | | | Combustion | of Oxygen | | | | | | | | 4\. Causes Mild | | | | Headache or | | | | Dizziness at law | | | | Concentrations | | | | | | | | 5\. Fetal at High | | | | Concentrations | +-----------------------+-----------------------+-----------------------+ | 5\. Nitrogen Dioxide | 1\. Motor Vehicle | 1\. Respiratory | | (NO~2~)- gas | Exhaust | Irritant | | | | | | | 2\. Power Plants | 2\. Reduces | | | | Visibility | | | 3\. Decomposing | | | | Animals and Plants | 3\. Toxic to Plants | | | | | | | Sources | 4\. Precursor of | | | | Ozone | | | | | | | | Health/ Environmental | | | | Impact (s) | +-----------------------+-----------------------+-----------------------+ | | 4\. Fertilizer | 5\. Pressure of Acid | | | Factory | Rain | +-----------------------+-----------------------+-----------------------+ | 6\. Hydrocarbons | 1\. Industries | 1\. Precursor of | | (HC)- gas | | Ozone | | | 2\. Motor Vehicles | | | | | 2\. Some Cause | | | 3\. Petroleum | cancer in humans | | | Refineries | | | | | Cancer in humans | | | 4\. Evaporation from | | | | petrol Stations | | +-----------------------+-----------------------+-----------------------+ | 7\. Ozone (O~3~)- | 1\. Motor Vehicles | 1. Respiratory | | gas | | Irritant | | | (Indirectly) | | | | | 2. Corrodes Rubber | | | | and Paint | | | | | | | | 3. Toxic to Plants | +-----------------------+-----------------------+-----------------------+ | 8. | 1\. Refrigerators | 1\. Ozone Depletion | | Chlorofluoro-carbons | | | | (CFC~S~) | 2\. Air Conditioners | 2\. Increased | | | | Ultraviolet | | | 3\. Industries | Radiation | | | Manufacturing | | | | | 3\. Increased | | | 4\. Aerosol | Incidence of skin | | | Propellants | Cancer resulting | | | | from 1 & 2 above | +-----------------------+-----------------------+-----------------------+ | 9 Lead (Pb)- Metal, | 1. Leaded Fuel in | 1. Damage to Nervous | | Aerosol | Motor Vehicles | System, Blood and | | | | Kidneys | | | 2. Battery | | | | Manufacturing | 2. Poisoning | | | | | | | 3. Other Industrial | 3. Mental | | | Processes | Retardation | +-----------------------+-----------------------+-----------------------+ | 10\. Smoke | 1\. Wood Burning | 1\. Respiratory | | | | Irritant | | | 2\. Bush/Forest | | | | Fires | 2\. Toxic gases | | | | | | | 3\. Refuse Burning | 3\. Carcinogens | | | | | | | 4\. Industrial | 4\. Reduces | | | Processes. | Visibility | +-----------------------+-----------------------+-----------------------+ Source: Modified from Nadakavukaren (1986) Several diseases are either directly caused by ingestion of contaminated water or are indirectly associated with water. The Bradley classification of water-related diseases (Bradley, 1974) as modified by Faechem, (1977) is presented in Table 4. **Table 4: The Bradley Classification of Water-related Diseases** +-----------------------+-----------------------+-----------------------+ | **Transmission | **Description** | **Examples** | | Route** | | | +=======================+=======================+=======================+ | 1\. Water-Borne | 1\. Transmission by | 1\. Cholera | | | consumption | | | | (ingestion) of | 2\. Typhoid | | | water contaminated | | | | by pathogen, | 3\. Amoebiasis | | | parasite (for | | | | example in sewage) | 4\. Infectious | | | or chemical | Hepatitis | | | | | | | | 5\. Poliomy elitis | +-----------------------+-----------------------+-----------------------+ | 2\. Water-washed | Person-to-person | 1. Skin Infection | | | transmission due to | (e.g. scables) | | | lack of water | | | | (inadequate quantity) | 2. Eye Infection | | | for personal, | (e.g. trachoma) | | | domestic | | | | | 3. Yaws | | | or community hygiene | | +-----------------------+-----------------------+-----------------------+ | 3\. Water-based | Transmission through | 1. Schistosomiasis | | | an intermediate host | (Bilharzia) | | | (e.g. fresh water | | | | snails and Cyclops) | 2. Drancunculiasis | | | | (Guineaworm | | | | Disease) | +-----------------------+-----------------------+-----------------------+ | 4.Water--related | Transmission through | 1\. Trypanosomiasis | | Vector borne | vectors which breed | (African Sleeping | | | in water or bite near | Sickness) | | | water | | | | | 2\. Yellow Fever | | | | | | | | 3\. Malaria | | | | | | | | 4\. Filariasis | | | | | | | | 5\. Onchocerciasis | | | | (River Blindness | | | | Diseases) | +-----------------------+-----------------------+-----------------------+ 3. **Food Quality and Health** Food contamination can occur through contaminated water soil and air or by infected humans, diseases vectors or vomites (e.g. contaminated cooking utensils). The 5 shows some epidemic food-borne diseases (food poisoning and food infection) and the types of food sources though which the illness can be contracted. **Table 5. Epidemic Food-borne Disease** +-------------+-------------+-------------+-------------+-------------+ | **Source** | **Food | **Bacteria* | **Food | **Viral** | | | Poisoning** | * | Infection | | | | | | Parasite** | | +=============+=============+=============+=============+=============+ | 1. Eggs | \- | 1. | \- | \- | | and Egg | | Salmonelios | | | | Product | | is | \- | \- | | s | | | | | | | | 2. | \- | \- | | | | Streptococa | | | | | | l | | | | | | pharmyngiti | | | | | | s | | | +-------------+-------------+-------------+-------------+-------------+ | 2. Meat | 1. Bacillu | 1. Anthrax | 1. | Hepatitis A | | and | s | | Toxoplasmos | | | Meat | cerceus | 2. | is | \- | | Product | food | Salmonelios | | | | | poisoni | is | 2. | \- | | | ng | | Trichinosis | | | | | 3. | | | | | 2. Botulis | Tularemia | \- | | | | m | | | | | | | 4. | | | | | 3. Clostri | Yersiniosis | | | | | dium | | | | | | | | | | | | Perfringes | | | | | | food | | | | | | poisoning | | | | | | (*fp*) | | | | | | | | | | | | 4. | | | | | | Staphylococ | | | | | | cal | | | | | | | | | | | | Food | | | | | | poisoning | | | | +-------------+-------------+-------------+-------------+-------------+ | 3\. Milk | 1\. B. | 1. | Giardiasis | Hepatitis A | | and Dairy | cereus fp | Diphteria | | | | products | Staph fp | | | | | | | 2. | | | | | | Brucellosis | | | | | | | | | | | | 3. | | | | | | Tuberculosi | | | | | | s | | | | | | | | | | | | 4. Typhoid | | | | | | fever | | | +-------------+-------------+-------------+-------------+-------------+ | 4. Seafood | 1. Botulism | 1. Cholera | \- | 1. | | | | | | Hepatitis A | | | 2. | 2. Typhoid | \- | | | | Shelifish | | | 2. | | | Poisoning | 3. | | Poliomyelit | | | | Shigeliosis | | is | | | 3\. Vibro | | | | | | Parahae | 4. | | | | | molyticus | Salmonelios | | | | | tp | is | | | +-------------+-------------+-------------+-------------+-------------+ | Source | Food | Bacteria | Food | Viral | | | Poisoning | | Infection | | | | | | Parasitic | | +-------------+-------------+-------------+-------------+-------------+ | 5. | 1\. B | 1. Cholera | 1. | \- | | Vegetables | cereus | | Amoebiasis | | | | food | 2. Typhoid | | \- | | | poisoning | | 1. | | | | | 3. | Giardiasis | | | | 2. | Salmonelios | | | | | Pesticide | is | | | | | Intoxicatio | | | | | | n | 4. | | | | | | Shigellosis | | | +-------------+-------------+-------------+-------------+-------------+ | 6\. Food | 1\. Staph. | 1. Cholera | \- | Hepatitis A | | Handlers | Fp | | | | | | | 2. | \- | \- | | | | Shigellosis | | | | | | | \- | \- | | | | 3. Typhoid | | | +-------------+-------------+-------------+-------------+-------------+ | **Source** | **Food | **Bacteria* | **Food | **Viral** | | | Poisoning** | * | Infection | | | | | | Parasite** | | +-------------+-------------+-------------+-------------+-------------+ | 7. Housefly | \- | 1. Cholera | Amoebiasis | \- | | | | | | | | | | 2. Typhoid | \- | \- | | | | | | | | | | 3. | \- | \- | | | | Shigellosis | | | +-------------+-------------+-------------+-------------+-------------+ | 8 Rodents | \- | 1. | \- | Lassa fever | | | | Leptospiros | | | | | | is | | | +-------------+-------------+-------------+-------------+-------------+ | 9 Mushrooms | Intoxicatio | \- | \- | \- | | | n | | | | +-------------+-------------+-------------+-------------+-------------+ | 10 | Chemical | \- | \- | Acute viral | | Unspecified | Intoxicatio | | | infection | | | n | | | | +-------------+-------------+-------------+-------------+-------------+ **PREVENTION AND CONTROL OF ENVIRONMENTAL DISEASES** " Prevention is better than cure" is a popular adage although experience has shown that most Nigerians, like other human beings elsewhere in the world, ignore this maxim and engage in behaviours and practice that suggest that "cure is better than prevention." This is one of the basic attitudinal problems militating against prevention and control of diseases associated with environmental health hazards in Nigeria. Other institutional problems/constraints include poverty, ignorance, grossly inadequate environmental health man-power, low priority, low priority accorded environmental health programmes, poor funding, inadequate scientific and technological support base and low level of environmental awareness. It is also important to note some significant differences between prevention, control and cure. Prevention is the cheapest, easiest and most sensible of the three and it involves taking appropriate actions, including positive behavioural changes, to ensure that an environmental health hazard does not cause injury, diseases, disability, or death. When injury or disease has already occurred and we want to minimize its impact, then control measures are put in place. Curative measures are undertaken to control diseases or eliminate the causative agents (where they are known) in order to provide temporary relief to the sufferer. Cure attempts to repair the damage after it has been done and it cannot offer guarantee against reoccurrence of the same disease, as long as the person continues to live in an unsafe or insanitary environment. Prevention or control of disease associated with the environment can take place at both personal and community levels. Some prevention and control measures are disease-specific (e.g. National Onchocerciasis Control Programme-NOCP, Nigerian Guinea worm Eradication programme-NIGEP, National Malaria Control Programme, Yellow Fever Control Programme, Cholera Control Programme and the National AIDS (Acquired Immuno-deficiency Disease Syndrome Control Programme while others target a group of disease (e.g. water-borne diseases, diseases caused directly or indirectly by refuse; sewage, and dusts). Table 6 gives a synopsis of preventive/control measures for selected disease associated with the environment. **Table 6: Preventive/Control Measures for Selected Environmental Diseases** +-----------------------------------------------------------------------+ | **Disease (s) Preventive/Control Measures** | +=======================================================================+ | **1**. Onchocerciasis **A.** **Personal** | | | | (River Blindness Disease) 1. Avoid fast-flowing | | | | Streams or rivers (breeding sites of blackly vector). | | | | 2\. Use protective clothing. When working near breeding sites. | | | | 3\. Use chemical repellents | | | | 4\. Use mectizan (Ivermectin) tablets to prevent blindness or to | | cure disease. | | | | **B. Community** | | | | 1\. Large-scale spraying of blackfly breeding sites with insecticide | | (abate) | | | | 2\. community-based mass treatment with mectizan tablets. | | | | 3.Community health education on the causes, prevention and control. | +-----------------------------------------------------------------------+ | **2. Diseases A. Personal** | | | | (Guinea worm Disease) 1. Boil and filter (with clean cloth) all | | drinking water. | | | | 3. Prevent infected persons from entering and contaminating | | | | Note: No Cure Community water source. | | | | **B. Community** | | | | 1\. Treat water source (e.g. ponds) infested by Cyclops (vector) | | with insecticide (abate). | | | | 2\. Construct safe water sources. | | | | 3\. Protect existing water sources by building physical barriers. | | | | 4\. Community health education | | | | **3**. Water-borne **A. Personal** | | | | Disease 1. Boil water before drinking | | | | (e.g. Cholera and Typhoid) or using for cooking food. | | | | 2\. Personal Hygiene | | | | 3\. Protect cooked or uncooked foods from files | | | | 4\. Chanstheraphy (use of drugs) to cure disease.\ | | 5. Immunization | | | | 6\. Other simple water purification methods w e.g. | | | | Alum, Chloroc, Tincture of lodine, etc. | | | | **B. Community** | | | | 1\. Purification of water sources (i.e., potable water). | | | | 2\. Sanitary disposal of excreta. | | | | 3\. Community hygiene | | | | 4\. Mass immunization | | | | 5\. Mass chemotheraphy | | | | 6\. Food hygiene | | | | 7\. Community health Education | +-----------------------------------------------------------------------+ | **Disease (s) Preventive/Control Measures** | | | | 4. Food-borne **A. Personal** | | | | | | | | 1. General environmental sanitation | | | | 2. Mass chemoprophylaxis | | | | 3. Mass chemotherapy | | | | 4. Mosquito vector control by physical, chemical and biological | | methods | | | | 5. Community health education | +-----------------------------------------------------------------------+ **REFERENCE/BIBLIOGRAPHY** Olaniran N.S, Akpan E.A, Ikpeme E.E and Udoffa G.A (1994). Environment and Health, Lagos, Macmillan Nigeria Publishers Limited, First Edition, 1-40.