ENH 1103: ENVIRONMENTAL HEALTH
Introduction
This module is divided into three units viz. Concepts of environmental health, occupational and health safety and educational
field visits. Concepts of environmental health will cover introduction to environmental health, water and sanitation, proper methods of handling food, housing, control of vectors and pests and pollution. Occupational and health safety will cover introduction to occupational and health safety and occupational hazards. Educational field visits to water
and sewage treatment plant, refuse disposal site, slaughter house and food
processing plant will be made.
Topic 1: Introduction to Environmental Health | |
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Objectives By the end of this topic, the learner will be able to: Define the term ‘Health’ Define the term environmental health Outline the components that make up environment and how they affect our health |
Environment:
1.The circumstances, objects, or conditions by which one is surrounded.
2.All that which is external to the individual host. [It] can be divided into physical, biological, social-cultural, economic and political factors, any or all of which can influence health status in populations.
Health: WHO: …“a state of complete physical, mental, and social well-being and not merely the absence of disease or infirmity”.
Environmental Health
Since the environment comprises all things that make up our surrounding, environmental health, therefore, describes the aspects of health related or emanating from our interaction with the environment.
Components of Environment and their Effects on our Health
The following components of environment can have a positive or negative effect on our health: Biological, Physical, Socio-Cultural, Economic and Political.
Diagrammatic Illustration of Components of Environment Biological Environment:
Biological Environment
Biological Environment comprises all the living things. These may include; people, trees, crops, domestic animals, pests, insects, bacteria, viruses, fungi, parasites etc.
People and the Environment
Human beings and their activities can be a big source of infection. For example, overcrowding and slum settlements are as a result of urbanization. This may be a fertile environment for contracting diseases that are spread through droplets like tuberculosis among many other diseases. Explosions from quarries may create dust which can cause respiratory and eye problems. The artificial dams created become water collection points and breading sites for mosquitoes. these "dams" are risky places for kids.
Plants and Environment
Plants have many uses in the environment. They absorb gases that are dangerous to ozone layer. They prevent soil erosion, protects water sources, act as wind breakers and as natural beauty , influence weather patterns, provide firewood, timber, charcoal, paper etc. They provide a variety of food stuffs and herbal medicine e.g Neem tree, garlic, aloe Vera etc. Felling of trees destroys water sources. Cultivation along river beds contaminates water supply through seepage of fertilizers and pesticides used on crops. Overgrazing leads to soil erosion, water contamination and destruction of vegetation. All these human activities have a direct or indirect effect on human health. However, some plants may adversely affect our health: some people react to pollen –develop hey fever, asthma etc; Ingesting or touching some plants may have devastating effects on ones health.
Animals: Usefulness to Environment
Animals provide meat, milk, eggs, hides, wool, manure and act tourist attraction thus improving the economy. Cats and dogs are kept as pets by some people. However, some animals like snakes and insects are fatal to human beings; some insects eg mosquitoes are vectors of malaria, yellow fever, dengue fever, Chikugunya virus and filariasis. Houseflies are vectors of dysentery and other diarrheal diseases. Bacteria, Viruses and fungi are also part of the environment and are disease causing organisms to man.
Physical Environment
This can be divided into two: Geographical and Man-made environment. Some examples of geographical environment are land, type of soil, climate, altitude and rivers. Man-made environment comprises roads, houses, dams, industries, chemicals and toxic substances. All these have a direct of indirect effect on human health.
Pollution:
Pollution is the term used to describe the spoiling of natural resources such as air, food and water by harmful substances. Industrial wastes such as smoke can pollute the air and water. Similarly, poorly disposed off human waste can pollute the environment and thus cause diseases. Other industrial wastes can pollute the soil and vegetation In rural areas, pollution may result from use of insecticides, pesticides and industrial waste from coffee, sugarcane etc
Environmental health problems are usually more prevalent in towns and slums than in rural areas. Its noteworthy to point out that, as a health worker, you can make a difference in the community by assisting individuals, families and the community to make their environment healthy.
Socio-cultural Environment
Human beings are social animals. different communities have different cultures which may positively or negatively affect their health. Some cultural elements include: customs, beliefs, religion and values. Some social elements may include family, kinship, housing, leadership and power structure.
Socio-cultural Practices that Affect Health:
- Wife cleansing ceremonies after the death of a husband- Spread of STIs & HIV/AIDS
- Female Genital Mutilation (FGM)– Difficult deliveries, HIV/AIDS
- Discouraging breast-feeding after child birth - malnutrition, retarded growth
- Failure to use prenatal and delivery services - perinatal death, high mortality rate
-Pregnant women prohibited from taking certain parts of an animal meat - poor growth of the foetus
- Wife inheritance and polygamy- Spread of STIs & HIV/AIDS
Economic and Political Components of the Environment
Economic Environment
These components include work, money and government. The economic factor relates to both rural and urban economies as well as local community organizations. Rural and urban economies determine to a great extend the quality of environment. People can change their environment either positively or negatively. Some of these changes are described as development. Some development projects may make the environment healthier while others make it a suitable habitat for diseases. An example is an irrigation scheme for growing rice, which is a cash crop. It improves the peoples’ income, but at the same time, rice fields are breeding sites for mosquitoes and snails which are vectors of malaria and schistosomiasis respectively.
Political Environment
The political establishment is instrumental in many development projects. Beyond Zero Campaign is a good example. The Government develops policies which enforce environmental health. National Environment and Management Authority (NEMA) is a government entity that regulates and safeguards the environment. Political instability causes unrest, insecurity and psychological problems. When there is political instability, management of disease outbreaks may be lacking as health facilities may be destroyed
Summary
In this topic, you have learned about:
Definitions of ‘Health’, environment and environmental health
Components that make up the environment and their effects on our health
References / Recommended Reading
Blumenthal, DS & James R. (Eds). 2010. Introduction to Environmental Health, 2nd Ed. New York City: Springer publishing company
Koren H,. & Michael, SB. 2002. Handbook of Environmental Health, Volume I, 4th Ed. Philadelphia: Routledge Press.
| Topic 2: Water and Sanitation |
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Part 1: Water
Specific Objectives
By the end of the topic, the learner will be able to:
State the sources and uses of water
State the sources of water contamination 
Identify Water Related Diseases
Explain simple methods of water purification
Introduction
Water is essential for life. It is found in every cell of our body and is necessary for most basic functions. Over 50% of human body weight is made up of water. Water is thus vital to health and survival. However, water may become the source of disease and should be properly treated and made safe for domestic use
Sources of water
Th three main sources of water include: rain water, surface water and underground water
Note that, the most important water for a community is underground water. This is the water that is in the soil, by the roots of trees in the forest. The community’s long-term underground water store…educate the community on the need to preserve their forests.
Rain Water
Rain water is relatively pure and clean. The cleanliness depends on the method of harvesting. The community health nurse should assist the community to ensure collection of clean water.
Surface water: This includes shallow springs and shallow wells, streams, rivers, dams, ponds and lakes. Shallow springs and wells are liable to contamination by pit latrines and surface water after the rains.
Underground Water: Underground water lies between two impenetrable layers of rock. It finds an outlet through a fissure or a crack in the upper layer. Its obtained as a deep spring, a well or a borehole.. Its Plentiful and has less chances of contamination. It does not usually dry up during dry seasons. This type of water needs to be pumped into reservoirs before use.
Sea Water: This type of water is salty and requires expensive purification processes to make it suitable for use.
Sources of water contamination
Rain water can absorb gasses like carbon dioxide from the atmosphere and other impurities from the roofs. Surface water absorbs minerals and dangerous chemicals from industrial wastes. Water harvested from roofs is usually contaminated by leaves, dust, birds’ droppings etc. Its also contaminated by human/animal excreta, refuse, fertilizers or industrial waste. Excreta can contaminate shallow wells too.
Wells: Wells may be contaminated by dirty containers, oils, bathing, urinating, defecating in water, washing clothes and animal watering, contaminates rivers etc.
Piped water may be contaminated by leaking pipes
Water from any source may be contaminated if its drunk from dirty or communal drinking vessels.
Note that, Its safer to prevent water from contamination than to clean it.
Some ways in which water contributes to spread of disease
1. Water Washed Diseases
When water is scarce, and people cannot observe basic personal hygiene, diseases like scabies, non-specific diarrhoea, dysentery and trachoma spread. Such diseases whose spread is promoted by lack of adequate water are called water-washed (water-scarce) diseases.
By simply improving the quantity of water, these diseases can easily be prevented.
2. Water-Borne Diseases
Water can also contribute to the spread of disease when it carries specific disease - causing organism. Examples of these diseases include typhoid, cholera, amoebiasis, Hepatitis A, Poliomyelitis etc. Diseases caused by contaminated water are called water-borne diseases. The only way to prevent them is to improve the quality of water i.e. the cleanliness of water.
3. Water Related Diseases
Water can contribute to the spread of disease when it’s necessary in the life cycle of a disease vector. Some examples of these diseases include: malaria, schistosomiasis, onchocerciasis (river blindness) and drancunlosis (guinea worm).
Protection of water sources
Protecting a spring
All water sources should be protected. To protect a spring, Clear the bush or long glass around the site of the spring; Put up a fence around the spring to prevent animals from grazing and children from playing around it; dig a drain 45 meters from the spring to divert surface water; build steps to the spring as well as a platform on which to place the containers when collecting water. Design an area for washing and for watering the animals. Select a caretaker to maintain the protected spring
Protecting a well
Select the site at least 100 meters from a pit latrine or other likely sources of contamination. Wall sides of the well should be built with concrete. The top should be constructed sloping with water proof materials. Put a strong well cover in place
Purification of water sources
Safe water System
The safe water system is a household-based water quality intervention. This is an intervention that can be used by many household in the community.
The intervention has three components
- Water treatment in the home by chlorination
- Safe storage
- Behavior change technique
Safe water System
The goals of safe water systems are:
- To improve the microbial quality of water in the home by means of sustainable technology;
- To reduce morbidity and mortality from diarrhea diseases related to contaminated water;
- To improve hygienic behavior related to water use
Chlorination
Chlorine is added to water that has been filtered on a large scale for supply in cities and towns. Chlorination is the final safeguard of the quality of water. Amount of chlorine added should be proportioned to the volume of flow and to the chlorine demand of water. After chlorine is added, there should be a minimum contact of 30 minutes for it to be effective against pathogenic organisms in water.
Instructions on the amount of chlorine to be added is usually given by the manufacturer.
Part 2: Waste Disposal
Objectives
At the end of the Section, the learner will be able to:
State the two types of wastes
State the diseases spread by human excreta and explain the ‘4F' connection’
State the different sources of waste
Outline excreta disposal methods and types of latrines
Types of Waste
Man produces waste wherever he is and it is necessary to manage this waste properly to prevent diseases
There are two types of waste: Solid waste and Liquid waste. Solid waste is also known as refuse.
Liquid Waste
Liquid waste produced by human beings is called excreta i.e faeces and urine. These are a source of pathogenic organisms.
Excreta are offensive to both sight and smell and can also lead to contamination of water and food, Faecal organisms may infect people directly or indirectly through an immediate host. Human excreta may spread the following diseases: typhoid fever, cholera, intestinal worms, poliomyelitis, infective hepatitis A, bacillary and amoebic dysentery.
Urine Carries the infective ova of Schistosoma Haaematobium while faeces spread the haematobium mansoni. FAECES should not be accessible to FINGERS, FLIES and FOOD (4Fs)
Fingers and Flies transfer faeces to food through the faecal-oral- route transmission, known as the 4F connection.
Its necessary to help people understand the importance of proper excreta disposal by use of simple and cheap facilities. As a nurse, you should be able to identify possible customs and beliefs which hinder proper excreta disposal in the community and educate the people accordingly.
Solid Waste
Solid waste or refuse is defined as any unwanted discarded material, the remains, residual or by-products of human activities which are no longer required for further use by the initial producer.
This is normally in the process of preparation, manufacture, packing and other human related activities. If solid waste is not disposed off properly, it may create a number of problems. Problems caused by indiscriminate waste disposal include: offensive smell, attracting insects, vector/pests particularly flies, cockroaches and rats, spreading diseases, causing pollution of air, water or food, causing accidents.
Sources of Waste
There are various sources of waste. These include: domestic waste, street waste, industrial waste, hospital waste and garden/agricultural waste.
Domestic Waste
This usually consists of all the unwanted materials from the house e.g food left-overs, potato and banana peelings, waste paper, worn out clothes, shoes, broken utensils, bottles tins etc.
Street Waste
This type of refuse consists of paper, food and commercial refuse in public places such as markets and hotels. Scrap metals may also be included in this category.
Industrial Waste
This varies with the type of industry. Modern industries produce chemical wastes, which are hazardous to man and other living things. The waste may be toxic, caustic, acidic or inflammable. This means that it needs special disposal. If the chemical waste is to be discharged into a stream, it should be processed first. If it is solid, it should not be dumped on land as it may eventually seep underground and contaminate water sources.
Hospital Waste
This is the most familiar waste that nurses are aware of. It includes the following: sharps e.g needles, surgical blades, gauze, cotton wool swabs, vials and ampules, lotions, drugs, vaccines, tubings, gloves, papers, foetuses etc.
Health workers have the responsibility of maintaining infection prevention by proper decontamination and disposal of the above waste.
Garden/Agricultural Waste
Agricultural waste from all types of crops and fertilizers may result in pollution of natural resources such as air, food , and water.
Liquid Waste Disposal
The best method of excreta disposal in rural areas is a pit latrine, while toilets are suitable for urban areas. As a health worker, it is important for you to know how a pit latrine is constructed
General guidelines on construction of a pit latrine:
- Pit latrines and cesspools should be at least 2 -3 meters above the water table;
- Latrines should be located at least 6 meters away from the buildings;
- Wells should be located upstream to avoid contamination of water passing through the pit latrine or cesspool.
Excreta disposal is divided into two categories i.e:
a. Water carriage System b. Non water carriage system
Water carriage system
In this system, excreta are disposed off by the use of a flash toilet, which is also called a water closet. The flash toilet is the most permanent and hygienic method of excreta disposal. This system is used where there is a permanent water supply system. This is mainly in cities and towns. Water closets are reliable and convenient for any permanent building. The excreta are carried by water pressure into a septic tank or sewage pit. The clear fluid effluent needs further bacteriological treatment to become inactive. It is then led over stones and sand in underground drains for completion of biological decomposition. The solid part of the excreta (sludge) settles at the bottom. The sludge relies on natural decomposition. It is reduced in volume and is ultimately converted into inoffensive unstable product. However, the water carriage system is very expensive, technical and requires sewage treatment works
Non Water Carriage System
In this method, excreta are disposed off by deposition in a pit latrine. Pit latrine is the most important disposal method in the rural areas. In its simplest form, the pit latrine consists of the following: a hole in the ground; a squatting plate for sitting or standing; a hut or shelter for privacy.
In this way, the excreta is safe from fingers, flies and food (4Fs).
Types of Latrines
Ventilated Improved Pit (VIP): These are more user friendly and the features include a vent pipe for controlling flies.
Bore hole latrine: Its bored into the ground about 6 feet deep and 4 feet in diameter instead of digging a pit. It has a smaller volume and fills up faster than a pit. It is faster to install, and is appropriate following disasters where there is urgent need to install many latrines.
Trench Latrine: A latrine where a trench is dug and a number of holes with dividing partitions constructed over it. These type of latrines are constructed in temporary work camps.
Bucket Latrines: These are also known as pail closets and are used where the water tables are high. A squatting slab or seat is placed above the bucket which is filled within a few days. Some of the negative aspects of this type of latrine are the unpleasant job of emptying it, and the spillage, which attracts flies.
Composting pit latrine: Suitable where the water table is too high for a deep pit latrine to be dung.
Objectives of solid waste disposal
Solid waste should be disposed off properly to prevent breeding of pests and vectors, foul smells, contamination of water sources, accidents from sharp objects, overcrowding where space can be created for better utilization.
Methods of refuse disposal
Dumping: This is deposition of waste in open areas, in the sea or in the rivers.
Burning: This is done in a number of ways including simple open air burning, burning in a trench or using a simple mud-brick incinerator. Open burning of combustible refuse is frequently used but it is not very effective.
Burning by Incinerators: An incinerator is an improved way of burning combustible refuse. Incinerators can be simple and cheap, or complex and expensive. Among the cheap ones is the bin incinerator made out of drum with fire bars across it and air holes underneath. A more expensive one is built out of brick and fitted with chimneys.
Composting
Composting is “a process in which, under suitable environmental conditions aerobic micro-organisms break down organic matter to fairly suitable humus’’. The decomposition process occurs naturally on the ground when droppings from trees and animals are converted by micro-organisms to humus. Aerobic composting is usually odour free. This method is cheap, convenient and recommended especially in rural areas
Controlled Tipping
This method involves depositing refuse into depressions or large holes in the ground. These tips should be situated at least half a kilometre away from settlements, preferably out of sight and down wind. This is an effective method for hygienic disposal of refuse. It can be used where sufficient land is available.
The method consists of three steps as shown below
Step 1
| Step 2
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DEPOSIT REFUSE
| SPREAD AND COMPACT REFUSE | COVER IT WITH EARTH AND COMPACT EARTH COVER |
| Topic Three: Appropriate Methods of Handling Food | |||||||||||
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Objectives By the end of this topic, the learner should be able to: State the source of food Explain methods of food storage Explain preparation and preservation of food State Causes of Common Food Borne Diseases Introduction Food is essential for growth, development and in the provision of energy. However, food can also be responsible for the spread of some disease. The aim of food hygiene is to prevent the contamination of food at any stage. These stages are production, collection, storage, sale, preparation and consumption. Sources of Food Sources of food vary widely. They include: crop production, animals, markets etc. Foods that are of animal origin should only be derived from animals that are legally allowed for human consumption, for example, some countries ban game meat. Crop production should follow rules in agricultural practice, which involve spraying crops against pests. Farmers are advised on safe use of pesticides. During food processing, certain standards of food hygiene are applied, for example, in milk treatment, drinks and tinned foods. The chemicals used as preservatives are also regulated for safety of the consumers. The slaughter of animals is governed by several rules and Acts, for example, the Meat Control Act, the Veterinary and The Public Health Act. Food can be contaminated by excreta, dirty fingers, fries, poisonous insecticides or pesticides on vegetables or chemical preservation of food. It can also be contaminated if it is derived from infected animals, for example, animals with tapeworms or brucellosis. Recommended Conditions for Storing Different Types of Food Storage Storage depends on the type and packaging of the food. Dry foods These include foods like maize, beans, wheat (cereals). Such foods should be stored in dry, airy conditions in improved granaries. Bagged foods These foods should be stored on raised shelves at least 18 inches above the floor or ground level. This enables the store to be swept and washed easily. It also allows for ease of inspection. Perishable foods These are foods that go bad within a short time. Such foods include dairy products, meat and fish. They should be refrigerated to inhibit the multiplication of bacteria. Preservation This is defined as any method used to treat food for the purpose of prolonging its life, without appreciated loss of its quality and appeal. Most human food is of biological origin and there is continuous metabolism to produce the end product. This applies to food of both animal and plant origin, for example, meat, milk, fish, leaves, tubers and seeds. When an animal or plant dies, they lose the mechanism of protection from bacteria, fungi and moulds. We preserve food in order to: Increase the shelf life, for example, highly perishable foods like milk; Conserve the food for use during the periods of scarcity, for instance dried cereals and vegetables; Avail seasonal foods like fruits throughout the year Principles of food preservation There are two principles of food preservation. The first principle is to destroy organisms responsible for spoilage through heat treatment. The second principle is inhibiting micro-organisms through cold treatment. Organism Involved in Food Spoilage Molds, which affect the surfaces of foods containing high sugar and salt. They also affect dry foods that may become damp due to poor storage; Yeast, which affect foods that have acid or high sugar concentration, for example, dried fruits, and concentrated fruit juices. Bacteria, which affect foods under various conditions apart from dry food.
The principle of destroying organism involved in food spoilage through heat treatment. Heat Treatment of Foods To destroy microorganisms, cooking, blanching, pasteurization, sterilization and canning methods of food preservation are used. Cooking: This is heating process, which aims to produce more palatable food. Cooked food generally keeps longer than raw foods as long as re-contamination is minimized. Cooking destroys or reduces micro-organism and potential toxins in food. Cooking also inactivates undesirable enzymes in food. On the other hand, cooking may cause degradation of food nutrients, for example, over cooking vegetables destroys vitamin C. Blanching: This is the process where most vegetable foods are heat treated at 70-100˚C for 2-10 minutes. This is done by immersing food in boiling water or exposing it to steam. Blanching is used before freezing, canning or drying. This process inactivates enzymes, drives out air bubbles trapped in food, enhances retention of green colors and reduces micro-organisms. Pasteurization: This is relatively a slow method of heat treatment. Pasteurization is generally carried out at a temperature of below 100˚C. This method is used to increase the life span of the product. The method reduces organisms that cause spoilage and eliminates pathogens. Sterilization: In this method, heat is used to kill all micro-organisms and their spores at a temperature of 100˚C. The sterilized food must be stored in an airtight container to prevent the entry of, and decontamination by, micro-organisms. Canning: In this method, food is first heated at a temperature that kills all bacteria and it is then sealed up in sterile cans or bottles. This prevents bacteria from getting into it and enables it to remain safe for a long time at a room temperature. Inhibiting microorganisms’ multiplication Method A: Cold treatment- Freezing and refrigeration Method B: Others- salting, smoking, drying Freezing This is the most satisfactory method currently available for the long-term preservation of food. When properly done, freezing is effective for retaining the color, texture, flavor and nutritive value. Food must be deep-frozen at 0-4 degrees Celsius to remain palatable. This keeps food fresh for weeks or months. Salting This is saturation of food with salt or sugar, for example, ham, jam and jelly. The added solute reduces microbial activity due to its dehydrating effect; salt and sugar solutions are more concentrated than the cytoplasm inside the cell. Therefore, the water passes out of the cell into the concentrate, dehydrating the cell. Smoking and drying Drying and smoking makes food unsuitable for bacteria to grow and multiply. Fish or meat may be preserved by these methods. A wood rack is made and fish or meat is placed on it. A wood fire, which generates heat and thick smoke, is made under the rack. The heat will dry the fish or meat, and the smoke gets inside the food to act as preservative. Green vegetables, cereals and legumes can be preserved by drying them in the sun. If food is preserved by drying It must be stored in a dry place until it is used. Food Preparation Adequate personal hygiene must be observed when preparing food to prevent a number of diseases. Below are some important factors to consider. Health Individuals suffering from respiratory infections such as colds or sore throat should not work with food until they get well. This also applies to people with infected cuts, skin eruption and diarrheal diseases like dysentery and typhoid. Clothing Individuals working with food should wear clean washable outer garments. Every worker in the kitchen or washing dishes should wear a clean uniform or apron. These clothes should be worn when the worker is in the premises where food preparation is taking place.This avoids cross food contamination. Head covering To avoid hair from getting into food, hair bands, caps or nets should be used to cover the head when handling food. Personal hygiene A daily bath is necessary for every individual. Wash hands before handling the food, use clean utensils and avoid bad habits such as nose picking. Nails should be kept short and clean. Food Raw food should be separated from cooked food. All vegetables should be cleaned thoroughly before preparation for cooking. Fruits should be washed before eating. Food should be hygienically prepared and cooked adequately. All food utensils should be cleaned properly after use and left to dry before being stored in a clean place. Environment The environment pertaining to the preparation of food should be clean throughout. The area should be dust free. This includes the floors and all the surfaces used for food preparation. The facility itself should be clean and with adequate ventilation and lighting. Causes of Common Food-Borne Diseases:
Food safety regulations Introduction The safety of food is so important that our government has passed laws to protect the public. These laws cover many aspects of food handling and health officers are generally responsible for enforcing these laws. Agricultural personnel assist them, where necessary. We shall look at some of factors that should be considered when preparing or handling food and some of the food borne diseases. The public health Act Cap 242: This is an Act of Parliament to make provision for securing and maintaining health. This is divided into 15 parts. Each part deals with specific aspect of public health. Part 10 of the act deals with “ protection of foodstuffs”. This part regulates the construction of buildings used for storage of foodstuffs. Secondly, it prohibits residing or sleeping in kitchens or food stores. Part (ii) deals with “milk, meat and other articles of food.” This part prohibits the sale of unwholesome foods. It gives powers to authorized officers to inspect and examine food, seize and recommend disposal at any time. These laws aim at protecting the public and the public health officers are responsible for enforcing them. As a community health nurse, you need to work closely with public health officers to apply the food safety regulations. The following are some of the areas that need close supervision: Meat: Meat is one of the commonest foods that cause problems to the public. Therefore, it is important that inspection of slaughterhouses, cows, sheep, goats and pigs be done. The same case applies to butcheries where meat is sold. Milk: Milk is one of the foods that are easily contaminate and cause problems to the public. Inspection of shops where milk is sold is of paramount importance. Milk should be safe and clean. It should be obtained from healthy cows as it can transmit bovine tuberculosis among other diseases. The room for handling milk should be clean, dustless and separate from the barn. The pails, cans, bottles, coolers and other equipment, which comes into contact with the milk, should be thoroughly cleaned. Homes: It is the responsibility of the community health nurse to share health messages with community members on food hygiene. These include maintenance of personal hygiene as discussed earlier that is cleaning the utensils, handling them with clean hands, and storing them in clean and dry cupboards or containers. Farms: The community should follow the regulations on the use of insecticides and pesticides in form of sprays and fertilizers. This will help them to use each of them correctly depending on the age of the crop. Your role as a community health nurse is to encourage the community to adhere to the instructions from the agricultural field educators. Moreover, instructions are given on the respective containers of theses pesticides. You should teach the community about regulations of food storage and preservation of different types of food. Harvest should be carried out when the crops are completely ripe or ready to facilitate longer preservation. The cereals and legumes should be dried properly before storage to avoid spoilage. All perishable foods should be consumed at the right time. Markets: All types of foodstuffs are sold in markets. Markets should be designed in a manner that considers stations where similar types of foods should be stored sold, for example vegetables of all kinds, dry foods like cereals, fruits and cooked foods. Market should be kept clean and proper refuse disposal maintained. The food sold should be clean and fit for human consumption. This, therefore, explains the importance of inspecting markets by public health officers. These officers have the powers to close markets and condemn foods to prevent disease outbreaks. Hotels: Hotels, restaurants and food shops should also be inspected under hygiene regulations. They require inspection by the public health officers. All the food handlers should be supervised and a regular medical examination is mandatory for them to prevent spread of diseases through food handling. Licenses should only be given to hotel owners who have met the requirements. Laboratory examinations may be necessary for food such as precooked meat. The use of uniforms, aprons, head covering, as described earlier, should be observed in the hotels. Proper personnel and environment hygiene in the hotel premises should be maintained. The hotel should store, preserve, prepare, cook and serve the food according to the public health regulations. The law also empowers closure of hotels, which do not meet the regulations.
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| Topic Three: Summary | |
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In this topic, you have learned about: Source of food Methods of food storage Preparation and preservation of food Causes of Common Food Borne Diseases |
| Topic Five: Control of Vectors and Pests | |||||||||||||||||||||
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Specific Objectives By the end the topic, the student will be able to: Discuss diseases associated with vectors and pests Describe methods of control of vectors and pests Explain how you will community involvement in control of vectors and pests Ways in which a vector may transmit pathogens There are two ways in which a vector may transmit pathogens: 1. Mechanical transmission In this mode of transmission, the vector carries the infective pathogen or agent on its body or limbs. Alternatively, the inefective agent may be ingested by the vector and excreted unchanged in its faeces; 2. Biological transmission In this mode of transmission, the vector acquires the infective agent from the blood or skin tissue of the infected host and the infective organism undergoes some development in the vector. The infective vector may also inoculate the infective agent from its salivary secretion into a new host to cause disease, for example, in the transmission of malaria. The host may be infected through contamination of skin or mucous membranes by the infective faeces of the vector, for example, louse borne relapsing fever. The host may acquire infection by ingesting the vector, for example, guinea worm. Diseases associated with vectors
A pest is an organism, which in a given circumstance adversely affects human health or the economy. Rats and mice are pests and they belong to a group of animals called rodents. Insects such as white ants, weevils, aphids are also pests. Pests have to be numerous in order to cause a serious problem. Insecticides and pesticides are used to eliminate pest infestations. The safest and the most economical methods available are used.
How do Rodents Destroy Property? Rodents destroy all types of dry grains in our houses, granaries and in the fields. In food processing regulations, the evidence of rodent droppings and urine stains causes condemnation and disposal of large quantities. They can destroy buildings by gnawing wood, water pipes, electric cables and they can cause fire outbreaks. Methods of Control The following methods may be used to control pest infestations: Personal hygiene, Environmental hygiene, Improved housing and Use of pesticides and insecticides. Personal Hygiene This includes thorough hand washing, which should be practiced before preparing or eating food and after visiting the toilet. Short and clean nails should be kept and a daily bath should be taken. Wearing of shoes will prevent infestation by jiggers and hookworms. The hair should be kept short and clean. The use of shampoo, which has a suitable insecticide, is helpful for cases of head lice. Clothing should be washed at least once a week and ironed. Bedding Bedding should be cleaned thoroughly at least weekly and dried well in the sun. If infested with mites and lice, it should be boiled and ironed, in order to kill them. Food Food stores, cupboards and tables should be kept clean. All foodstuffs should be covered to prevent flies gaining access to them. All food utensils should be kept clean and dry. Make use of the improved methods of preservation of food we have previously discussed. Environmental Hygiene Drainage of water The aim of proper water drainage is to destroy all mosquito-breeding sites. Drain any stagnant water or slow-moving water around the house. All holes and ditches should be filled to avoid standing water. All receptacles likely to retain water, for example, used cans and tins, bottles, coconut husks, vehicle tyres and so on should be collected and properly disposed of. Slow moving streams should be canalized to facilitate faster water flow. Roof gutters should be cleared regularly to prevent blockage of water flow by leaves and other materials. Clearing of the vegetation around the buildings, and water banks removes damp areas where mosquitoes breed. Cleanliness The home or village environment should be kept clean. Animal shelters should be a reasonable distance away from the main house. Waste and excreta disposal This should follow the proper methods of waste disposal as described earlier Improved Housing Floors and walls These should be cemented so that they can easily be swept and washed. The floors should be cleaned after meals to clear all the food on the floor. All the crevices and cracks in the walls and floors should be plastered. Beds and Other Furniture People should not sleep on the floor but on raised beds. Beds and mattresses should be regularly taken outside in the sun to kill any lice, mites and bed bugs. Boiling water can be poured on the bed stands for the same purpose. Joineries of furniture with tracks and crevices should be filled up with plastic wood filler. Buildings and Food Stores Rat proof buildings and food stores should be constructed. In malaria areas, buildings should be mosquito proof, with wire gauze to cover all ventilation openings, doors and windows. Buildings should be inspected regularly for pests. Use of Chemical Substances such as Pesticides and Insecticides Chemicals used to kill the pests are in the form of insecticide sprays, dusting powders, miticides, rodenticides, emulsions, oils and molluscides. Remember, as earlier said, crop production should follow the rules of agricultural practice, which involves spraying crops against pests. After harvesting, the cereals and legumes are dried in the sun and then treated with pesticides in the form of dust or powder. This protects the grains against pests for at least six months. For cats, dogs and cows the appropriate insecticide is used to dust or wash them regularly to kill any fleas and ticks. Rodents are controlled by the use of rodenticides, which are available in most shops, for example, Rat & Rat, Rat Rid, Fuko Kill and so on. The floors and walls of houses may also be treated with insecticides regularly. Mattresses and bedsteads can be treated in the same way. Heavily infested buildings should be treated with residual insecticidal sprays. Kerosene is also used to kill bed bugs and white ants when worked into cracks and crevices by use of an applicator like a feather. Insecticides and larvicides in the form of oils and emulsion are sprayed on the water surface to kill insects in water. Molluscides may be applied in water to kill the snails, which spread schistosomiasis. | |||||||||||||||||||||
| Topic Five: Summary | |
|---|---|
In this topic, learned about diseases associated with vectors and pests, control of vectors/pests and community involvement in the control process. |
| Topic Five: References /Further reading | |
|---|---|
Koren H,. & Michael, SB. 2002. Handbook of Environmental Health, Volume I, 4th Ed. Philadelphia: Routledge Press. NASPHV Compendium of Animal Rabies Prevention and Control - http://www.avma.org/pubhlth/rabies_compe ndium_2005.pdf World Health Organization: Equipment for Vector Control- A Guide to Major items, Specifications, Use, Descriptions - Field Tests. WHO-Geneva 1964. |
Topic Six: Pollution
Objectives
By the end of this topic, the student will be able to:
Define pollution
Identify major types of pollution
Explain pollution prevention and control
Pollution is the term used to describe the spoiling of natural resources such as air, food and water by harmful substances. Industrial wastes such as smoke can pollute the air and water. Other industrial wastes can pollute the soil and vegetation.
Air pollution is the introduction of particulates, biological molecules, or other harmful materials into the Earth's atmosphere, causing disease, death to humans, damage to other living organisms such as food crops, or the natural or built environment
Air Pollutants: Air can be polluted by different types of pollutants. The major air pollutants include;
- Carbon Dioxide (Co2)
- Sulphur Oxides (Sox)
- Nitrogen Oxides (Nox)
- Carbon Monoxide (Co)
- Particulate Matter (Pm)
Sources of Air Pollution: These include: emissions from power stations, emissions from industrial processes, vehicular emissions, emissions from burning of solid waste, emissions from natural sources such as volcanic eruptions & forest fires.
Control of air pollution: For air to be made safe from pollutants, stringent measures must be put in place by the government to ensure that the above emissions are at the lowest tolerable levels. These measures include: setting standard for air cleanliness, laboratory equipment (ambient air monitoring station, portable gas analyser) and smoke control action plan. This would ensure that the environmental air is free from disease causing pollutants.
Water pollution refers to the contamination of water bodies. These may include lakes, rivers, oceans, aquifers and groundwater.
The major water pollutants are: organic contaminants (detergents, herbicides, etc), inorganic contaminants (heavy metals, ammonia, etc), solid waste (plastics, paper food waste) and thermal pollution (discharge of warm water into water bodies by factories).
The major sources of water pollution are: sewage, runoff of pesticides and fertilizers, solid waste disposal, untreated effluents from industrial and other activities and chemical and oil spills.
Land pollution refers to the deposition of solid or liquid waste materials on land or underground in a manner that can contaminate the soil and groundwater, threaten public health, and cause unsightly conditions and nuisances.
Major sources of Land Pollution:(see topic 2 - types of waste)
Noise Pollution
Noise is generally defined as unwanted sound. Sound affects man physically, psychologically and socially. Noise may be continuous or intermittent and may be of high frequency or a low frequency.
There are are many sources of noise pollution. The common ones include:- Industrial (power plants, stone crushing, metal workshops, cabinet making);
- Multipurpose halls including wedding halls;
- Bungalows along the coast;
- Places of entertainment, including night clubs;
- Road traffic e.g. moving trucks, automobiles, buses, especially those with modified silencer system;
- Community noise e.g. radio/TV, loudspeakers, pool houses and alarms;
- Animals e.g. dogs, cats, crows;
- Use of loud speaker, amplifier, musical instrument, electrical or mechanical device for religious activities;
- Aircrafts and speed boats;
- Neighbourhood;
- Machinery (generator sets, compressors, air conditioning units, boilers, pumps, motors);
- Others, including construction works, road infrastructural works, public gathering, vibration, ice cream sellers, vendor shouts.
Health Effects of Noise Pollution
Noise can be a source of health problems. Some may be immediate and others long term. they include:- Hearing Loss (including occupational hearing loss)
- Stress
- High Blood pressure
- Sleep Loss
- Distraction
- Productivity Loss
- Irritability,
- headache
- Annoyance and interference with communications.
Control measures should be instituted to minimize the above health effects. These include:
Mass sensitization;
Enforcement of the existing Noise Regulations;
Use of noise abatement technologies (e.g installation of noise barriers between the noise and the receiver)
Research in novel technologies;
In this topic, we have learned about:
Definition of pollution
Major types of pollution
Pollution prevention and control
References / Recommended Reading
United Nations Environment Programme (2017e). The Partnership for Clean Fuels and Vehicles (PCFV). [http://www.unep.org/ transport/pcfv.
UN-Water (2016). Water and Sanitation Interlinkages across the 2030 Agenda for Sustainable Development. http://www.unwater. org/app/uploads/2016/08/Water-andSanitation-Interlinkag United Nations Environment Programme (2017e). The Partnership for Clean Fuels and Vehicles (PCFV). [http://www.unep.org/ transport/pcfv.es.pdf
World Health Organization (2016a). Ambient Air Pollution: A Global Assessment of Exposure and Burden of Disease http://apps.who.int/iris/ bitstream/10665/250141/1/9789241511353- eng.pdf.
UNIT 2: OCCUPATIONAL HEALTH AND SAFETY
| Topic 1: Summary | |
|---|---|
In this topic, you learned about: Definition of occupational health Aims and objectives of occupational health services |
| Topic 2: Summary | |
|---|---|
In this topic, you have learned about: Health hazards and their management Function, duties and role of an occupational health nurse |
Unit 3: Educational Field Visits
Module Competency
