S ources

1- Microbes and parasites: 2- chemicals:

Effect of polluted with microbes Insecticides and herbicides pollute 1.Typhoid is transmitted to healthy fruits and vegetables and cause

people through contaminated liver disease and allergies

f ood especially milk.

2. Food poisoning result from microbial

fermentation of food or multiplication of

harmful microbes.

Example :salmonella

3. Intestinal diseases: such as

cholera, typhoid, dysentery,

intestinal worms are transmitted

through food contaminated with faeces

Controlling food pollution:

• Proper wash of vegetables and

fruits + proper cooking .

• Combating flies + covering food.

• Periodic examination of cooks and

waiters who deal with food + bacteriological analysis.

• Proper disposal of spoilt food.

S oil pollution

Sources and effects:

1. Insecticides or herbicides or industrial wastes reach the soil with irrigation water, wind, or dissolved rain fall.

2. Plants absorb them → Animal → Man

3. Arsenic, lead, sulphur dioxide, exhaust of cars remain in the soil for several years and affect productivity

& fertility of the soil and decrease % of oxygen and nitrogen in air spaces in the soil .

4. Radioactive pollutants cause blood cancer and bone cancer.

5. Cereals like rice may absorb radioactive isotope strontium Sr 90 instead of calcium from the soil. The isotope is then transmitted to man when he eats the rice. It accumulates in his bones and harms the process of formation of blood cells in the bone marrow

Controlling soil pollution:

1. Factories and laboratories are built away from farms .

2. Proper use of pesticides and fertilizers.

3. Greater care about security measures for atomic reactors.

4. Nuclear explosions should be carried out in far places.

5. Treatment of sewage water.

Give Reasons : Bone cancer spreads largely between Japanese rice farmers.

• R adioactive Sr 90 from fallout pollutes rice. Sr 90 ingested with rice replaces calcium in the bone causing bone cancer.

N oise pollution

1. Sources: aero planes

Radio & T.V.

Transport means

Factory machines

Air conditioning

2. Sound intensity: is measured by a universal unit called decible. The human ear responds to sound range within 130 decibels.

Sound intensity	Effect
More than 80 decibels for several hours daily.	-Nervous tension, complete deafness may occur.
Sudden uproar of a jet plane or great explosion	-Nervous disorder - High blood pressure
100 decibels	-Experimental rats became ill, due to the high percentage of ammonia in their blood.
175 decibels	the rats died

Thunder 120 decibel

Jet planes 110 decibel

Aero planes 100 decibel

Crowded areas 70 decibel

Quite home 15 decibel

Whispers 10 decibel

Controlling sound pollution:

1-Decrease sound intensity of the source by using quieter machines. Move airports away from inhabited places.

2-Machines are placed on rubber bases to decrease their movement or are provided by shock absorbers.

3. Factory workers should use ear protective covers.

The primitive stage	The transitional stage	The stable stage
High birth & death rates which lead to low growth rate.	Health care reduced death rate & increased birth rate. High growth rate.	Death rate is slightly higher than birth rate & therefore population is declining.
This stage occurred thousands of years ago	Egypt exists in this stage.	Europe passed the transitional stage & exists in this stage now.

Nations can be classified into two groups:

1. Developed countries: such as the European countries which have improved health care so death rate decreased. The natural rate of birth is declining which makes the population stable.

2. Developing countries such as Egypt have a high birth rate & low death rate which result in natural increase in population. In Latin America the rapid increase in population is not a problem because their natural recourses need working hands.

Solution of the population problem in Egypt :