factors in environment affecting health

1. 7
CHAPTER II
ENVIRONMENT AND HEALTH
Objectives:
 Identify the sources and health effects of environmental risks in air,
water, housing, food and wastes.
 Define health related activities relevant to prevention and controlof
environmental risks
The environment is any thing surrounding us and can affect health. Man is
in continuous interaction with the environment. He affects and is affected
by the environment through exposure to natural or man made hazards. In
this chapter we will study the relationship between the environment and the
human health.
Environmental sanitation means properties and requisites of clean
environment, while environmental health means protection of human health
from the hazards of unsanitary environment.
Environmental health hazards:
1. Chemical: heavy metals, pesticides, solvents, chlorinated
hydrocarbons.
2. Physical: radiation, noise, vibration, temperature and pressure.
3. Biological: bacteria, viruses, fungi, toxins.
4. Psychological: problems with family, friends, co-workers.
5. Accidents: floods, volcanoes, earthquakes, recreational activities.
Components of environmental sanitation:
1. Town planning 2- Housing conditions
3- Ventilation and air sanitation 4- Water sanitation
5- Waste disposal 6- Vector and rodent control
7- Food sanitation
To achieve a sanitary and healthy environment we must consider all health
related activities relevant to prevention and control of hazards beginning
from town (or village) planning and construction of houses& work places
that ensure sanitary living conditions as good ventilation, safe water
supply, safe waste disposal and control of vectors.
(I) TOWN PLANNING
It means proper planning of a new district or city or village before
construction.
Basic requirements of planning are:
1- The area of the new city must be classified into industrial,
commercial and residential zones. The inhabitant area must be far from
industrial areas to prevent health hazards of industrial gases and fumes.

2. 8
2- There must be wide streets, parks, gardens or green areas in between
houses.
3- Available, attainable, and convincing health services that cover all
districts equally. Other municipal services that affect health must be
available as fire extinguishing center, transportation methods and
markets.
(II) SANITARY HOUSING
Man spends most of his life inside houses either at home or school or
factory or job. So we mean by sanitary housing the healthy conditions that
must be fulfilled in any building.
Basic requirements of sanitary building:
1- At site far from industrial areas or volcanoes or river floods. At quiet
place (not noisy) and clean surroundings (free of insects and rats,
fumes and gases).
2- Made of safe, strong materials and proper foundations to overcome
rains, dampness, destruction by storms and earthquakes.
3- Privacy i.e. a separate house for each family and separate room for
one or two individuals (adequate number of rooms in relation to
number of individuals).
4- Adequate ventilation (adequate number of windows in cross-sites to
ensure adequate airflow especially in hospitals, factories and schools).
5- Adequate lighting either naturally or artificially to prevent vision
troubles and accidents.
6- Sanitary water supply from water project or deep wells.
7- Sanitary waste disposal through sewerage system or cesspits.
Collection of refuse and sanitary disposal.
8- Safety measures for prevention of accidents: good construction, good
lighting, safe furniture and safe electrical appliances.
SLUMS : are narrow courts or streets, densely populated with poor
housing and unsanitary environment. They are found in big towns due to:
1)overpopulation problem and b)high house renting c)migration from rural
areas to town and d)the illegal construction of houses without sanitary
water supply or sewage disposal.
Hazards of slum areas and unsanitary housing:
1- Increased rate of infection and deaths from communicable diseases.
2- Increased accidents as fire, falls and destruction.
3- Increased social problems as delinquency and addiction and crimes
4- Psychological problems due to lack of privacy and crowdedness.

3. 9
(III) VENTILATION & AIR SANITATION
Ventilation means providing and /or removing air from a confined
place by natural or artificial means. Natural ventilation by windows or
other openings must be of adequate area and distribution to introduce fresh
air. Proper town planning that consider the heights and spacing of
buildings, wide streets, gardens are all needed for proper natural
ventilation. Artificial means of ventilation are air condition and fans. Air
sanitation means the quality and quantity of components of air that can
affect health.
Sanitary requirements of air:
1- Air must be of optimum cooling power: means that the readiness of
air to accept the continuous flow of heat loss from the body. This is
governed by the temperature of air (cool air can accept more heat from
bodies than hot air), humidity of air (air of low humidity is of good
cooling power) and movement (presence of air currents or winds
increases the cooling power than stagnant air).
2- Air must be of good quality i.e. free of pollution.
Causes ofunsanitary air
Any change in the optimal conditions (physical, or biological or
chemical components) of air can affect health, for example:
Physical change as temperature, humidity, pressure: if increased or
decreased causes hazards. Radiation: ultraviolet (UV) and infrared (IR)
rays if increased cause hazards. Noise: If increased causes hazards
Biological change as: * fungi , moulds and pollen : cause allergy.
* Microorganisms as bacteria, viruses, parasites, rickettsia: cause different
diseases.
Chemical change: as * gases and fumes : will be discussed in air pollution
* Metal dust: very small particles of different metals suspended in air can
cause eye injuries, chest and skin diseases.
Natural correction of unsanitary air:
1- Wind and air movements cause dilution of substances.
2- Plants and trees give O2 and absorb CO2 through photosynthesis.
3- Rain dissolves gases and fumes and settles down suspended dust.

4. 10
HAZARDS OF PHYSICAL CHANGES IN AIR
1- TEMPERATURE
Exposure to high temperature: As in very hot climate or in some
industries as glass and steel industries.
1- Heat cramps: when man is exposed to excessive heat, physiological
processes to loose heat occur as vasodilatation of peripheral blood vessels
and sweating. A large amount of fluids and salts are lost in sweat specially
sodium chloride leading to severe muscle cramps in limbs and abdomen.
Body temperature is normal or slightly increased.
2- Heat stroke: exposure to high temperature (45-50ºc) leading to
disturbance of heat regulating center in brain which causes heat retention.
There is hyperpyrexia (increased body temperature to 40 or 43ºc) hot dry
red skin, delirium, convulsions and may be death.
3- Heat rash: due to blocking of sweat gland ducts leading to raised red
vesicles on skin and itching.
4- Picture of ill ventilation: occurred in confined crowded places (as
classrooms) poorly ventilated. Physical changes of air occurred as
increased temperature, humidity and sluggish movement (poor cooling
power of air) which leads to heat retention, headache, discomfort, lack of
concentration, lassitude and hot sensation. There is no role of increased
CO2 or decreased O2 in manifestations of ill ventilation.
Exposureto low temperature:
Causes chilling either general or local: Body temperature decreases,
vasoconstriction of peripheral vessels to decrease heat loss from skin and
shivering in order to increase heat production. If chilling is prolonged,
frost bite, gangrene of fingers or tip of nose, even death occurred.
2- HUMIDITY
Increased humidity causes manifestations of ill ventilation or heat
stroke as mentioned before. Decreased humidity causes dryness of mucous
membranes of nose and mouth leading to increased liability of infection.
3- PRESSURE
Exposure to high pressure :
Sea divers and workers in construction of bridges are exposed to
high pressure under water, when they return back to surface rapidly they
suffer from Caisson disease. Oxygen and nitrogen gases are dissolved in

5. 11
blood under high pressure, on rapid decompression oxygen is utilized by
tissues while nitrogen bubbles in blood and these bubbles may close
arterioles in different body systems the most dangerous is the brain.
Exposure to low pressure:
Occurs at high altitude and high flight. There is decreased oxygen
pressure leading to hypoxia. Prolonged exposure (as inhabitants of high
mountains) causes acclimatization by increased hemoglobin and red
blood corpuscles to accommodate low oxygen.
4- RADIATION
Ultraviolet rays UV:
Due to exposure to sunrays or in industry or in physiotherapy. The rays
affect eyes and skin and may lead to burns, eczema and allergy. Frequent
exposure to UV rays in blond (light skin) individuals causes cancer skin.
Infrared rays IR :
In furnaces and in glass blowing industry. IR rays affect eye lens causing
cataract.
5-NOISE
In certain works or factories, in streets or at homes. The effect of noise
depends on the intensity and frequency of sounds and the duration of
exposure and the susceptibility of persons.
Excessive noise leads to:
- Impaired hearing and deafness.
- Irritability, increased blood pressure and psychological disturbance
- Decreased alertness and performance of work.
HAZARDS OF CHEMICAL CHANGES IN AIR
AIR POLLUTION
Means the introduction of one or more pollutants in the atmosphere, which
may be harmful to health. Or it is the presence of unwanted materials in air,
in sufficient amount and for sufficient time to interfere with comfort of
man or to affect his health.

6. 12
Sources of air pollution:
1- Respiration of man, animals and plants (oxygen decreases, carbon
dioxide temperature and humidity increase, expired air may
contain microorganisms also).
2- Combustion of fuel by transportation vehicles or machines (O2
decreases and CO2 increases, CO increased).
3- Fermentation of organic materials in refuse (CO2 increases and foul
smell is produced).
4- Volcanoes and forest fires (fumes and different gases of melted
metals, CO2, CO, ashes and smog after burn of trees).
5- Dust from streets, homes, and agriculture wastes.
6- Electromagnetic waves from television and mobile telephones.
7- Excessive noise from construction of building, transportation, horns,
machines, radio and TV especially in cities.
8- Industrial wastes as dust, gases, fumes, and vapors
The following are the most serious air pollutants to human health:
1-Total Suspended particulate:
They are present in the form of aerosols (solid particles or liquid droplets
suspended in a gaseous medium) such as dust, pollens, smoke.
Sources: Combustion, industry.
Hazards: Reduce visibility and cause respiratory problems such as
pneumoconiosis (particles less than 2.5 μm).
2- Sulfur Dioxide:
It is a colorless and corrosive. It dissolves in water present in the air to
form sulfuric acid.
Sources: Volcanic eruption, fuel combustion in industry.
Hazards: Damaging to lungs (aggravation of chronic lung diseases), plants
and animals.
3- Nitrogen dioxides:
It combines with water to form nitric acid, which is responsible for
atmospheric acidification.
Sources: High temperature combustion and action of bacteria on nitrogen
containing compounds in the soil.
Hazards: Acute and chronic respiratory diseases and property destruction.
4- Carbon oxides:
- Carbon monoxide: It is highly toxic and results from incomplete
combustion. It has great affinity for hemoglobin.
Source: Internal combustion engines.

7. 13
Hazard: Combine irreversibly with hemoglobin leading to asphyxia.
- Carbon Dioxide: It is non-toxic in low concentration. Its increase in
concentration contributes to the problem of global warming.
Source: Mainly respiration but it is balanced by photosynthesis (bad effect
of deforestation) and from fossil fuel combustion.
Hazards: Increases earth temperature thus producing undesirable climatic
changes.
5- Lead :
It is responsible for two thirds of all metallic air pollution.
Sources: Leaded gasoline, lead processing, smelters, paints and burning
materials containing lead.
Hazards: Neurotoxin that causes mental retardation especially in children.
6- Ozone:
It is formed by a secondary atmospheric reaction driven by solar energy in
the form of ultraviolet rays (photochemical reaction).
Source: It is formed in the atmosphere.
Hazard: Eye irritation and respiratory impairment.
7- Hydrocarbons:
They are volatile organic compounds that exist as gases in the air.
Source: transportation and petroleum refineries.
Hazards: Some are carcinogens.
There are also minor industrial pollutants either because they are present in
minor amounts or they have minor health hazards. Examples: asbestos,
benzene, mercury, noise, odors, radiation etc.
Other classification of air pollution according to its site:
I) Out door pollution:
This is usually called atmospheric pollution, it is the wider type of
pollution. It deals with an open and unlimited environment, it affects more
population, living things and property.
II) Indoor pollution:
It deals with limited and mostly closed environments e.g. houses and
work environments. Indoor air pollution is more hazardous than outdoor air
pollution because we spent more time inside our houses and the
concentration of pollutants are much higher (much tightly closed) than in
ambient air.
Harmful Effects of Air Pollution
1- Damage to health:
Air pollution is associated with a higher level of morbidity and

8. 14
mortality. Pollutants in air can affect mostly the respiratory system, the skin
and the gastrointestinal tract.
1- Exposure to air pollutants can cause or exacerbate chronic
obstructive pulmonary disease, bronchial asthma, acute
respiratory diseases.
2- It exacerbates cardiovascular problems and may even cause death
in individuals with impaired coronary circulation.
3- Carcinogenic and mutagenic agents cause various hazards to
human health e.g. malignancy and birth defects.
2- Annoyance to senses:
Eye, nose and throat irritation, bad odor and limited visibility are all related
to increase of some pollutants such as sulfur compounds, dust etc. Sky or
overhead darkening is the result of either heavy smoke or a mixture of
smoke and fog in most urban areas.
3- Interference with production:
Increased temperature, heavy smog cause automobile and traffic delays,
poor visibility, lethargy, poor concentration and absenteeism from various
establishments.
4- Property Damage:
Metal parts of building, roofs and other metal equipments are usually
damaged chiefly by corrosion from acidic compounds in polluted
atmosphere (SO2 forms with water vapor H2 SO4 also hydrogen chloride
reacts with water vapor to form highly corrosive droplets of Fog). Cracking
of rubber and various forms of electrical insulation are thought to be caused
by ozone (O3). Deterioration of painted surface is caused by a variety of air
contaminants.
5- Damage to vegetations:
The injury to vegetations varies from invisible injury to growth retardation
of various plants, which depend on the concentration and duration of
exposure to the toxic substance present in air as Sulfur compounds and
ozone.
6- Global Pollution Problems:
6-1 Global Warming:
Small amounts of carbon dioxide, water vapor, trace amounts of ozone,
nitrous oxide, chlorofluorocarbons (CFCs) and others play a key role in
determining the earth average temperature. These gases known as
greenhouse gases, act like the glass pan of a greenhouse i.e. allowing light,
infrared radiation and some ultraviolet rays to pass through the troposphere.

9. 15
The earth surface absorbs much of this solar energy and degraded it to
infrared radiation (heat). Some of this heat escapes into space and some
will be absorbed and trapped by the greenhouse gases and so increase the
earth’s temperature. This trapping of heat is called the greenhouse effect
and leads to global warming.
6-2 Ozone layer perforation:
The ozone layer, the global sunscreen, is formed by the interaction of
oxygen with light and solar energy. Its presence in the stratosphere keeps
about 99% of harmful ultraviolet rays (UV), thus protecting man against
sunburn, eye cataract, cancers and damage to immune system. Furthermore
by keeping UV from reaching the earth’s surface, it prevents much of the
conversion of oxygen in the troposphere to ozone which is harmful to
humans and other creatures. The elevation of temperature due to the
greenhouse gases lead to the formation of ozone in the troposphere with all
its bad effects.
6-3 Smog formation:
Smog is a mixture of primary and secondary pollutants that forms when
some of the primary pollutants interact under the influence of sunlight.
Normally, during the day, the sun warms the air which rises up carrying
pollutants away from the surface leaving a cooler layer with less
concentration of pollutants. Sometimes, weather conditions trap a layer of
dense cool air beneath a layer of less dense warm air, a phenomenon called
thermal inversion and thus prevents ascending of pollutants away from
earth. These air pollutants at the ground level build up to harmful and even
lethal concentrations.
6-4 Acid Rain:
Due to increased emissions of sulfur and nitrogen oxides from fuel
combustion, acids form from their reaction with water leading to formation
of acid rain. This acid rain leads to damage of plants, soil, buildings etc.
AIR POLLUTION CONTROL:
1-Outdoor Air Pollution:
A-Industrial control:
A1- Adequate zoning of industries in special areas where climatic and other
factors are taking into consideration.
A2- Control at source level:
a- Substitute highly toxic substance by less toxic one, e.g. use of fuel
with lower sulfur content.
b- Modification or change of industrial process e.g. closed system

10. 16
c- Adequate housekeeping and disposal of wastes.
A3- Particulate removal technique:
- Filters remove particles physically by trapping them in a porous mesh
of cotton cloth, spun glass fibers or asbestos- cellulose, which allows
air pass through but holds back solids.
- Electrostatic precipitators are the most common particulate control in
power plants. Ash picks up an electrostatic surface charge as they
pass between large electrodes. These charged particles accumulate on
a collecting plate (oppositely charged electrode).
B- Transport Control:
Control of pollutants emission from car by using modern techniques, use of
lead free fuel, also minimize traffic load inside cities by construction of
new system of out cities road.
C- Legislation:
- Determine the tolerated degree of pollution ambient air quality.
- Continuous monitoring of air pollutant.
- Preservation of natural air purification methods such as keeping forest,
no cutting of trees
- Obligatory laws for industries that omit pollutants in environment
2- Indoor Air Pollution:
1- Regularly ventilate the house.
2-Grow plants inside the house.
3-Avoid storing gasoline and solvents inside the house.
4-Do not use aerosols spray products.
5- Avoid smoking inside the house.
6- Make sure that heaters, stoves are properly installed and maintained.
7- In factories : workers must use masks and regularly checked for chest
and lung function.
3-The ozone layer:
1- Avoid using products containing chloro fluro carbons CFCs.
2-Do not use aerosol spray.
3-Check house appliances that contain ferion such as
refrigerators, freezers, air conditioner etc

11. 17
UNSANITARY AIR
(IV) WATER SANITATION
Water is a vital necessity of life without which, man can live only for
few days. About two thirds of our body weight is formed of water.
Natural water Supplies:
Surface water : River and lacks, but can be easily polluted and therefore
needs to be purified before use.
Underground water: in two layers  shallow and deep. They are
bacteriologicaly sterile if sanitary precautions are followed.
Rain water : can pick impurities.
Spring: is pure if protected.
Sea water: desalination is expensive.
Purification of water
Largescale purification: used in cities, towns. River water passes through
number of steps:
1- Water intake:
It is the place selected in the course of river or (canal) to draw water for
purification, it must be protected and away from any source of pollution
especially fecal materials.
2- Coagulation-sedimentation:
Water is pumped from intake to sedimentation tanks to be left for some
hours so that the greater part of suspended matter settles down. For
Physical Chemical Biological
Temp.↑↓
Humidity
Pressure ↓↑
UV,IR
radiation
Noise
Microwave
↑ CO,CO2,O3
↓ O2
SO2
NO
Lead, mercury
Hydrocarbons
Benzene
Asbestos
Bacteria
Viruses
Fungi
Moulds
Pollen

12. 18
better sedimentation in a shorter period of time, a coagulant (commonly
alum) is added.
3- Filtration:
By mechanical sand filter made of layers of sand on top of gravel.
Alum and rest of impurities form a surface film, which is responsible
for the filtration process. Water gets filtered on passing through the
surface film. The process of filtration removes all bacteria, cysts and
suspended matter but virus can pass through the filter. Frequent
washing of the filter is needed by passing a reverse current of water
under high velocity.
4-Disinfection:
The maximum efficiency of filtration for micro-organism removal is
95%. So water disinfection is necessary to destroy the remaining 5%
pathogenic organisms that may be found in filtered water. Chlorine is
the gas commonly used in disinfection.
Chlorination of water:
Chlorine is added to filtered water in a proper dose and left for half an
hour so that it disinfects water and also a residual part is left. Dose of
chlorine in routine water purification is 0.6 ppm (part per million), it
leaves a residual part of 0.2 ppm. Value of residual chlorine is to safe
guard against pollution during distribution of water to final consumers.
5-Distribution:
Through a network of pipes, water is distributed to the different parts of
the areas to be supplied. Presence of residual chlorine in water is a
safeguard against contamination from breaking or leaking through
pipes.
Small Scale purification: used in villages, small confined areas
It is used for water supply at the individual levels in case of absence of
large-scale purification. Some of these methods are:
1- Boiling: It is a reliable method. It kills all pathogens and is specially
needed for preparing bottle feeding of young infants.
2- Filtration: The domestic filter is the simplest. Water passes through a
candle, which is made of clay, porcelain. It requires regular cleaning
and if not properly cared for, it may become a source of infection itself.
3- Disinfection: Chlorine of lime (bleaching powder). It contains 20-35
percent of its weight available chlorine. It destroys most of micro-
organisms if proper dose and contact time are allowed.

13. 19
Rural water supply:
1- River water:
A popular source where people go to the canal to fill utensils. They used
for domestic purposes without purification and may be kept in porous
containers (e.g. zeer, kolla) for cooling purpose not for purification. Water
is unsafe and thus can expose consumers to infection.
2-Shallow wells:
Used by some houses for private water supply. Shallow underground water,
which is located in the superficial layers of the soil, is raised to the surface
by a pump.
Advantages:
Water of sanitary shallow well can be considered bacteriologicaly safe if
sanitary measures preventing pollution are taken.
Disadvantages:
Shallow underground water is exposed to pollution, from the surface and
nearby sources (latrines, cesspits and refuse heaps) with the risk of
spreading water-borne infection. Therefore, potential sources of pollution
must be eliminated with an area of 20 meters radius all around the well. A
shallow well is first licensed after sending water sample for laboratory
analysis and should be continuously licensed to ensure safety.
3- Deep wells:
Underground water in the deep layers is obtained by constructing a deep
well at a depth of more than 20 meters to reach the deep underground water
layer. Pumped water is raised up to fill a high tank reservoir of suitable
size. Water is distributed from the tank to a number of public taps located
at different spots of the village.
Advantages:
Deep water is clear, but not tasty, it is hard (not forming foam with soap). It
is bacteriologicaly sterile but pollution is possible through cracks or
leakage through pipes.
Disadvantages:
In certain localities, deep underground water contains excess chemicals,
from strata of earth, which may cause:
Dental florosis: Excess fluorine of more than 1.5 ppm causes mottling
of the enamel of teeth.
Methahemaglobinaemia: Excess nitrates of more than 20 ppm lead to
the formation of nitrites which is absorbed, and affects hemoglobin
leading to a serious and fatal disease in infants.

14. 20
Standards of potable water
For human consumption potable water must fulfill certain physical,
chemical and bacteriological standards.
1- Physical standards:
Must be odorless, colorless, agreeable taste and clear. Presence of
organic matter, algae, silt and mud can alter water’s physical
characteristics (becomes turbid, changes odor) but not necessarily cause
harm.
2- Chemical standards:
The pH must be neutral or slightly alkaline and with a moderate degree
of hardness. Hardness is the presence of insoluble salts of calcium and
magnesium in water which alter its chemical properties and affect its
quality. It can cause gastro-intestinal disturbance, waste of soap and
explosion of boilers. It is removed by boiling, addition of lime or
precipitation.
Safety limits for some chemical are determined such as nitrate 1.0 ppm
(part per million), fluoride 1.5 ppm, iron 0.3 ppm, arsenic and lead must
be almost nil.
3- Bacteriological standards:
It concentrates on evidence of faecal pollution. Water is inoculated on
agar and other special media. Coliform organisms are used as the
indicators for presence of bacteria. A high coliform count of ≥ 10 /100
ml is regarded as being suspicious of fecal pollution. E. coli must be
totally absent.
Water examination for physical, chemical and bacteriological standards is
carried out at each step of water purification.
WATER POLLUTION
Definition:
Water pollution is any physical, biological, chemical, changes in water
quality that adversely affects living organisms (man, animal and fish) or
make water unsuitable for desired uses.
The most important sources of water pollution are:
- Biological: (a) Bacteria : enterica, cholera, dysentries
(b) Viruses : hepatitis, poliomyelitis. (C) Parasites : Gardia L.and
schistosomiasis and entameba histolytica.
- Water soluble inorganic chemicals: acids, salts, mercury and
lead they make water not suitable for human and animal life and

15. 21
can cause diseases (e.g. Manamata disease caused by mercury
intoxication).
- Oxygen demanding wastes: they are organic wastes decomposed
by bacteria which deplete water from its oxygen thus causing
death of fish and aquatic plants.
- Organic chemicals : Such as pesticides and oils.
- Sediment or suspended matter: insoluble particles that are
suspended and thus cloud water and reduce photosynthesis of
aquatic plants.
- Radioactive isotopes: they can cause birth defect, cancer, genetic
damages.
One of the most important health hazards related to water supply is the
occurrence of water borne epidemic with the following criteria :
- Sudden or explosive onset.
- Large number of cases is reported in few days.
- All cases having common water supply.
- All ages, both sexes and different social groups are affected.
- More than one case may be simultaneously found in the same family.
- May occur in any season.
- Cases of diarrhea and others gastrointestinal manifestation may
appear before epidemic wave due to associated infection with
other pathogenic organisms of shorter incubation period.
- When water supply is controlled cases drop suddenly but take
time to return to the pre-epidemic level due to occurrence of
secondary cases.
Control of water borne epidemic is by control of the water source that
caused the epidemic. Increase the amount of chlorine added to the
water and then neutralize the excess.
(V) SANITARY WASTE DISPOSAL
The accumulation of various waste products and their indiscriminate
disposal represents a grave hazard to health. Systems of waste disposal are
designed to eliminate these hazards.
Types of wastes:
Solid: as paper, plastics, glass, garbage (from houses), dead animals,
metals (from industry), cotton and dressings(from hospitals).
Liquid: as sewage, wastewater from houses, rain water from streets,
irrigation wastes and chemicals from factories.

16. 22
Hazards of waste:
1- Breeding of insects and rodents:
Flies, cockroaches, mosquitoes and rats use collection of human excreta,
garbage, agriculture waste and manure as a breeding place for survival and
multiplication.
2- Spread of infection:
- As it is suitable place of breeding of flies and mosquitoes which are
vector of diseases.
-Contamination of freshly eaten vegetables by human wastes used as
fertilizers.
- Pollution of the sea water by sewage disposal at sea. The risk of
polluting shell fish and beaches.
-Exposure of scavengers to occupational infection during collection
and handling of refuse and sewage.
3- Physical and chemical hazards:
- Nuisance  offensive odor of gases resulting from purification of
animals, organic matter and also it is a bad sight to be seen.
- Injuries by broken glass or empty cans.
- Radiation hazards: potential risk from radiation wastes of industry or
hospitals when polluting water channels.
- Chemical and metal poisoning on disposal of trade effluents and
industrial wastes in water channels.
Therefore it is very important to properly disposethe different types of
wastes. The following will be considered:
A- Solid waste disposal
B- Liquid Waste disposal
C- Special methods for hazardous waste disposal.
A-Solid Waste Disposal
The waste stream is a term that describes the steady flow of varied wastes
that we all produce, from domestic garbage to industrial agricultural,
commercial, construction refuse. Many of the materials in our waste stream
would be valuable if they were not mixed with other garbage.
Wastes are disposed by several ways, some are old while others are new,
both types will be discussed but we are going to stress on the three (R’s) of
reduction, reuse and recycling.
1- Open dump:
Many people dispose wastes by simply dropping it to some place. Open
unregulated dumps are still the predominant method of waste disposal in
most developing countries. Open dump in rivers, canals, sea and oceans

17. 23
expose people, animals, and plants to many hazards and make water not
suitable for drinking or use in irrigation.
2- Landfills:
Also called controlled dumping where solid waste disposal is
regulated and controlled. To decrease smells and to discourage insect and
rodent breading landfill operators are required to compress the refuse and
cover it every day with a layer of earth. This method helps control
pollution, but dirt fill takes nearly 20% of the space. Oils, chemical
compounds and toxic metals seep to the underground surrounding areas.
Land fills are chosen to be high away from rivers and other water sources.
It was inexpensive but with the increase in the cost of lands, construction
and maintenance it became costly.
3- Incineration:
It is simply burning of waste. Another name is (energy recovery or waste-
to-energy) because the energy that is generated is a useful resource.
Two approaches are used. Refuse-derived fuel where refuse is sorted to
remove unburnable materials and mass burn where everything is burned as
much as possible. Residual ash and unburnable materials representing 20%
of original size are taken to landfill for disposal. They are however, costly
and flying ash contains dioxins of lead and cadmium which are hazardous
materials. To decrease the emissions of these hazards, removal of batteries
containing heavy metals, plastics containing chlorine before wastes are
burned .Closed incineration is very sanitary and healthy method if done at
small scale as in hospitals and big buildings.
4- Recycling:
It is the reprocessing of discarded materials into useful products. Some
reuse materials for the same purpose and other turn old materials into
entirely new products. Recycling saves money, energy, raw materials and
land spaces while also reducing pollution. Also recycling lowers demands
of raw resources.
5- Reuse:
It aims at shrinking of the waste stream. It is the reuse of disposed materials
after cleaning them in the same forms e.g. bottles and food containers.
6- Reduction:
It means produce less waste. It is much better than reusing. What is a waste
to one process may be a resource to another. Industry can produce less
waste by changing their manufacturing processes.

18. 24
7- Fermentation:
To manure in rural areas by forming heaps of refuse covered by layer of
earth and left for few days, decompositionof organic materials occurand
they are changed to useful manure.
B-Liquid Waste Disposal
As we mentioned before it is formed of:
- Domestic : excreta and waste water of kitchen.
- Municipal: waste water of streets (washing, rain).
- Industrial trade effluents.
Human excreta are an important source of pathogenic organisms.
Fecal matter is also attractive to flies and supports the development of the
larval stages of some parasites.
Urban Liquid Waste Disposal:
In urban areas liquid waste is disposed of through water carried system.
After collecting liquid waste from houses, it reaches the final disposal
where it will be disposed of by either dilution or treatment.
1- Liquid Waste disposal by dilution:
Crude sewage and waste water may be taken as such, or partially treated
and disposes in coastal countries, or rarely in rivers and streams. Sanitary
precautions have to be taken to prevent pollution of beaches and shell fish:
- Pipes must be carried to sufficient distance into the water stream.
- It must be below the surface by a sufficient distance.
- Currents must be studied to prevent return of sewage to the shore.
- Fishing must be prohibited at that area.
However, sewage and waste liquid disposal at sea is considered a potential
risk to health due to the possibility of back flow to shore, causing its
pollution and causing hazards to swimmers and fishing. Wind may carry
smell back to city.
2- Liquid Waste disposal by treatment:
It is the method used in most cities of Egypt. Its principle depends on
separation of suspended matter (sludge) from liquid part (effluent) and
destruction of all micro-organisms in order to end with a safe material that
can be used for economic values: sludge as fertilizers and effluent for
irrigation of farm. Steps :
1- Screening: which allows removal of large objects through passage of
liquid waste across screens formed of tilted bars.
2- Sedimentation: velocity of the flow of waste liquid will be reduced and
about two hours is allowed for it to stay in the sedimentation tank. It will

19. 25
thus be separated into three layers:
a- Sludge: about 60% of suspended solid will be settled down and form
the sludge. The removed sludge can be disposed by:
- Lagooning, which is spreading of sludge over specially prepared land and
is left to dry and then took to be used as fertilizer.
- Sludge digestion, which is an anaerobic process where sludge is digested
in special tanks, certain gases are liberated such as methane and the
treated sludge is disposed of.
- Sludge pressing: which is compressed into cakes and used as fertilizer.
b- Scum: Light substance like oil, grease and floating matter will rise to the
surface and form the scum.
c- Effluent: It is the liquid that is present between the scum and the sludge.
It is a turbid liquid and is called the tank effluent. It is used for irrigation
of farms. Ideally it should be used for plantation of wood trees and not
edible plants. Careful observation of workers in these farms is important.
Rural Liquid Waste Disposal:
There is no sewerage system in all villages so latrines and cesspits are used.
A latrine is a pit in the ground (better made impermeable to avoid
pollution of shallow underground water)and is covered by a slab to receive
and collect human excreta. Contents are emptied periodically and taken to a
suitable place for sanitary disposal. Latrines must be present inside houses
to ensure the following: no handling of fresh stool, no contamination of
surface soil, no unpleasant smell, simple, not expensive and acceptable
from the community.
Cesspits: the commonest way to dispose the collected sewage and waste
waters in mosques, schools, big houses. Sewage is collected by pipes and
disposed in cesspit (it is a large pit 3 to 4 meters deep may be permeable or
impermeable to be evacuated periodically. In impermeable tanks, under
anaerobic conditions, feces will be decomposed by the action of bacteria.
This breakdown of the complex organic matter will reduce its volume, kill
pathogenic organisms and convert it into soluble material which is
odorless, safe and stable product that can be reused as manure.
C-Hazardous and toxic waste disposal:
The most dangerous aspect of the waste stream is that it can contain
highly toxic and hazardous materials that can be injurious to human health.
So hazardous waste is any discarded material, liquid or solid that contains
substances known to be:
(1) Fatal to human or animals in small dose
(2) Toxic, carcinogenic, mutagenic or teratogenic to human or

20. 26
other forms of life
(3) Inflammable
(4) Corrosive
(5) Explosive.
Controlling and managing hazardous wastes :
(a)Produce less: It is the safest and least expensive way to avoid hazardous
waste problems. Manufacturing processescan be modified to eliminate or
reduce waste production.
(b)Convert to less hazardous substances:
a- Physical treatment:
- Charcoal or resins filters absorb toxins.
- Distillation separates hazardous components from aqueous
solution.
- Precipitation and immobilization in ceramics, glass, cement so
that isolation of the toxins is ensured.
b- Incineration:
It is quick, easy, clean (if correctly done) but not necessary cheap. It has to
be heated to over 1000 degree centigrade for a sufficient time for complete
destruction. The ash resulting is disposed of by landfill after its size is
reduced by about 90%.
c- Chemical processing: by neutralizing or oxidation of toxins to become
non toxics.
d- Biological treatment: some organisms can digest and detoxify a variety
of toxic compounds.
(C) permanent storage.
a-Retrievable storage in a secure place and periodically inspected for
possible leakage. It is expensive and need continuous guarding.
b- Secure landfills:
It is one of the most popular solutions for hazardous waste disposal. The
land of a pit is covered by an impermeable ground. The wastes are placed
in drums placed in the pit separated by soil or pack-in materials. Drain
pipes reach to the gravel layer to collect any leakage from stored materials.
When the pit is full it is covered by a cover similar to that of the bottom.
Precaution must be taken to safeguard against pollution of underground
water and accidents during transport of waste materials.
Radioactive waste management:
Radioactive wastes are produced in different forms: high, low level and
also solid, liquid and gaseous with various half-lives. Low level must be

21. 27
stored for several decades, while high level must be stored for thousands of
years. Most low level comes from nuclear power plants, hospital
universities, industries and others. The proposed methods for their
disposal are:
1- Bury it in deep underground: This is the favorable method by most
countries, they are reprocessed to remove very long active isotopes and
then fused with glass or ceramic materials and buried in deep underground.
2- Dump it into the deep oceans: it may leak and contaminates the oceans
or may be moved by volcanic activity.
3- Change it into harmless or less harmful isotopes: This is not done
because the costs are very high.
WASTE DISPOSAL
Less hazardous
wastes:home,street
Hazardous
wastes:
radiation,
corrosive
Explosive
toxic
Solid Liquid
Open dump
Landfill
Incineration
Recycling
Reuse
Reduction
fermentation
Urban Rural
-dilution in
sea
-treatment:
sludge,
scum,
effluent
Latrine
cesspit
Produce less
Conversion
Permanent store

22. 28
(VI) INSECT AND RODENT CONTROL
There are some insects in the environment that can transmit diseases to
man or cause discomfort and hypersensitivity from their bites. e.g.
mosquito, fleas, house fly, ticks and mites.
CONTROL OF INSECTS:
1-Eradication of breeding places through clean environmental conditions.
(remove collections of refuse or sewage in streets).
2-Application of insecticides to prevent completion of life cycle at any
stage. These insecticides must be safe for man, not exceed the
international allowed doses.
3-Personal cleaning and bathing to get rid of louse.
4-Screening of windows, paints on walls that contain insecticides, stickers,
electric shock lamps, mechanical killing, repelling creams used on skin to
get insects away.
CONTROL OF RODENT:
Rodents include rats which have health hazards to man. They transmit
infections. Also they have economic loss of stored food and crops.
Rat control :
Elimination of breeding places through :
 Modern town planning demolishes slums. Buildings made of concrete.
 Nile banks covered with stones or cement.
 Sanitary disposal of refuse, garbage and food wastes. Sanitary sewage
drainage system.
 Depriving rats of food by : rat proof food and grain stores.
 Destruction of rats through : trapping, poisoning, fumigation of cargo
ships to prevent entrance of rats to sea ports.
(VII) FOOD SANITATION
Food sanitation aims at providing the community with sound food
that is safe and is retaining its natural properties.
Requirements (criteria) of sound food:
(A) Safe food: pollution-free food, i.e. free of :
1- Pathogenic organisms and parasites.
2- Bacterial exotoxins.
3- Poisonous metals e.g. lead, arsenic and mercury.
4- Toxic chemicals e.g. insecticides.
5- Natural poisons e.g. some types of mushrooms, fish and shellfish,
and plants with poisonous alkaloids.

23. 29
6- Radioactive contamination.
(B) Retains its natural quality:
Normal physical and chemical properties, not spoiled nor adulterated.
Acceptable odor and shape.
Measures of food sanitation:
(1) Sanitary public food establishments:
Restaurants, canteens, food shops, stores, and other public places for
preparation, serving, selling or storing food should fulfill sanitary
requirements to be licensed by the local municipal or health authorities.
They must be periodically inspected.
(2) Food articles and utensils:
Used for processing, cooking, serving, storing and canning of food.
- They must be made of safe material (porcelain, stainless steel) not
including toxic metals.
- Kept always clean and protected from pollution or insects.
(3)Foodstuffs and food products:
Food in the markets must fulfill requirements of sanitary regulations
(physical, chemical and biological) and regularly inspected and sampled for
quality.
(4) Food handlers:
Who are responsible for preparation, transport, selling or serving food to
the public e.g. in schools, camps, factories, institutions, hotels, restaurants
and other public food establishments.
Measures for food handlers (sanitary regulations of food handlers):
These measures are the responsibility of the local health authority (health
bureau) when an individual applies for a license of food handler:
1- Pre-employment examination (clinical and laboratory):
Clinical examination for:
- Skin lesions e.g. staphylococcal lesions, scabies, etc.
- Suspected cases of pulmonary tuberculosis.
Laboratory examination:
- Urine: Culture for typhoid and paratyphoid.
- Stool: Culture for salmonellae (typhoid & paratyphoid) & Shigella.
- Smear for parasites: Eggs of Enterobius, Hymenolopis nana and T.solium.
- Cysts of intestinal protozoa: E. histolytica, B.coli and gardia lamblia.
- Swabbing throat and nose for Strept.haemolyticus, Staph.aureus,
corynebact.diphtheriae and virulence testing of diphtheria-positive cases.

24. 30
If the culture or swab is positive for a bacterial disease e.g. enterica,
bacillary dysentery and diphtheria, or parasitic disease e.g. amebiasis,
the individual is considered a carrier and is treated, re-examined after at
least, one month. On re-examination, 3 successive samples at 3 days
intervals for bacterial diseases, and 2 successive samples one week apart
for parasitic diseases, should be negative to consider the individual
healthy.
Those free of infections are given TAB vaccine (for typhoid) and
licensed.
2- Health education for personal cleanliness and good habits, especially
clean hands.
3- Supervision at work for following clean habits and screening
suspected cases of diseases and recording attendance to investigate
the cause of absenteeism.
4- Periodic examination and booster TAB vaccination: the given license
is valid for two years and so must be renewed so long the food
handler still work in food handling.
Diseasestransmitted by food:
Bacterial Viral Parasitic
- Enterica
- Bacillary dysentery
- Gastroenteritis.
- Food poisoning
- Cholera
- Brucellosis
- Tuberculosis
- Diphtheria
- Intestinal anthrax
- Poliomyelitis
- Infective hepatitis.
- Amoebic dysentery
- Ascariasis.
- T. saginata.&T. solium.
- Trichnella Spiralis
- H. heterophis
- Hydatid disease
- Fasciola hepatica
- Entrobius (ocxyuris)
- Giardia lamblia
MILK SANITATION
Objective:
To supply the public with sound milk which is clean, safe and not
adulterated? The law in Egypt allows marketing of buffalo, cow, sheep and
goat milk only.
Particular importance of milk sanitation:
Milk is particularly important vehicle of infection due to:
1- Milk is a popular food which is regularly consumed by many people
especially children, patients and the elderly.
2- Milk is a ready-made food that needs no cooking and so may be
consumed without heating.

25. 31
3- Milk used in preparation of many widely used dairy products is not
necessarily boiled or pasteurized before hand, but may be raw or just
warmed.
4- Milk is exposed to contamination from two sources: animal and man.
5- Milk takes a long way from farm to consumer, with many handling
and exposure to contamination.
6- Milk is easily adulterated, being a non-clear fluid.
7- Milk is a good medium for growth of organisms, especially in hot
weather, without cooling.
8- Milk from many herds is usually pooled for distribution, thus
increasing the risk of infection as one herd only may contaminate the
whole batch.
9- Supervision and control of milk sanitation are practically difficult.
Adulteration of milk:
Definition:
Change of the normal composition and constitutes of milk through
extraction and /or addition. It affects the nutritive value of milk and may
cause health hazards including infection.
Examples of adulteration:
1- Addition of water to increase the volume.
2- Skimming: extraction of fat, completely or in part.
3- Addition of preservatives e.g. formalin, boric acid, benzoic acid, etc.,
to prevent souring.
4- Addition of sodium bicarbonate to mask souring.
5- Addition of starch, sugar and or coloring matter to thicken, sweeten
and color watered milk.
6- Mixing milk of different animal species together.
How to produce safe milk?
Sanitary measures are taken at the farm, dairy, on distribution and at home.
(I) At the farm:
1- Dairy animals:
- Must be healthy, adequately fed, no overwork in the farm. They must
be of special herds (for milking) to produce large amounts of milk.
- Veterinary care: immunization, early spotting and management of
disease.
- No milking of diseased animals.
2- Animal shed must fulfil sanitary requirements. Good ventilation,
safe water supply, sanitary disposal of wastes etc..
3- Milking : in special room, better by mechanical means:
Personnel must be licensed as food handlers. Clean hands, cloths,

26. 32
and habits. Utensils must be properly cleansed and disinfected.
Milking room: clean, with safe water supply.
After milking: Keeping milk in a clean room in clean firmly
covered cans to be transported to the dairy in cooled cars.
(II) The diary:
1- Sanitary clean place and licensed.
2- Personnel licensed as food handlers.
3- Clarification of milk to remove foreign matters, then pasteurized.
4- Mechanical filling in sterile sealed bottles or sacs.
(III) Distribution of milk:
By sanitary retail shops where milk must be kept refrigerated.
(IV) At home:
- Pasteurized milk: must be kept cool, in refrigerator, until consumed.
- Raw milk: should be boiled and then cooled and protected in a clean
place if not consumed shortly thereafter.
Pasteurization of milk:
It is the process of heating milk for a certain temperature and time, then
rapid cooling, this is enough to destroy all pathogens which may be present
Pasteurization does not change taste and nutritive value of milk.
Methods:
1- The high temperature (Short time method) : used for large-scale
pasteurization. Milk is heated to 75°C for 15-20 seconds, then rapidly
cooled to 4°C and kept at this temperature until consumed.
2- Holding method: milk is heated to a temperature of 62°C for 30
minutes, then cooled rapidly to below 10°C and kept so till
consumed.
Boiling of milk:
Raw milk is heated to boiling point which destroys all pathogens and
saprophytes. It is a simple domestic method but affects nutritive value and
taste.
1- Precipitates some proteins, calcium and phosphorus.
2- Forms big, less digestible fat globules.
3- Destroys vitamin C and most of vitamin B1.
4- May cause caramelization (burnt lactose) and change of taste.
Milk-borne diseases
A) From animal source
1- Directsecretionin milk
1- Brucellosis

27. 33
2- Tuberculosis.
3- Footand mouth disease.
2- Contamination from animal environment
1- Salmonellosis
2- Tuberculosis.
3- Q-fever
4- Intestinal anthrax.
3- Contamination from udder and teats
- Strept. Infections e.g. tonsilitis and scarlet fever.
- Staph. Food poisoning
- Diphtheria.
II) From human source
* Contamination by droplet of handlers
1- Strept. Infection
2- Diphtheria.
3- T.B.
* Contamination Through handling
- Strept. Infections - Staph.food poisoning - Intestinal infections:
- Enterica - G.E. - Salmonellosis
- Infective Hepatitis - Shigellosis - Poliomyelitis.
- Cholera - ascaris - Intestinal protozoa.
III) Contamination by water and flies
- Intestinal infections
VI) Contamination with dust
1- Strept.infections.
2- Staph. Poisoning. 3- Intestinal infections. 4- Tuberculosis
MEAT SANITATION
Diseases transmitted by meat
Bacterial diseases Parasitic diseases
1- Typhoid and paratyphoid
2- Food poisoning
3- Brucellosis
4- T.B
5- Anthrax (intestinal and cutanous).
1- Taenia saginata (cattle)
2- Taenia solium (swine)
3- Trichinella spiralis(swine).
Principles of meat sanitation:
1- Raising of healthy slaughter animals and sanitary conditions.
2- Slaughtering is allowed only in abattoirs or special centers in rural
areas.

28. 34
3- In the abattoir:
- Ante-mortem inspection of animals to segregate the diseased.
- Postmortem inspection of carcasses to detect and condemn affected
parts or the whole carcass.
- Stamping fit meat with special official stamps of varied color and
shape.
4- Transport of meat to butchers’ shops under clean sanitary condition.
5- Proper storage and cooking at home.
FISH SANITATION
Diseases transmitted by fish:
1- Parasitic: H. heterophyes (brackish-water fish). & D. latum
(fresh-water lakes).
2- Infectious: intestinal infections.
3- Poisoning : due to consumption of certain naturally poisonous
species of fish.
Principles of fish sanitation:
1- Fishing: prohibited in areas of potential pollution e.g. sewage
disposal at sea. Fishermen are licensed as food handlers.
2- Ice-packing of fish on transport and storage.
3- Sanitation of fish markets: clean, proper waste disposal, availability
of cold storage.
4- Health education of the public for:
-Features of fish and spoiled fish.
-Proper cooking and grilling.
-Getting salted raw fish from sanitary sources and not to be
consumed before 10 days of salting.
SANITATION OF EGGS
Diseases transmitted by eggs:
1- Salmonella food poisoning:
- From infected poultry or:
- From contaminated environment through cracked shell.
2- Avian T.B.  extra pulmonary T.B.
Factors favoring infection:
1- Consumption of raw eggs.
2- Insufficient boiling or frying of eggs.
3- Using cracked shell eggs where organisms find entry through the shell.
How to detect healthy eggs:
1- Putting eggs in 10% saline solution: decomposed eggs float while
the sound sink down.
2- When examined against strong light: decomposed egg shows dark
spot within yolk shadow, while fresh egg is translucent.