overpopulation
The fact of a country or city, etc. having too many people for the amount of food, materials, and space available there.
pollution
Damage caused to water, air, etc. by harmful substances or waste.
epidemic
The appearance of a particular disease in a large number of people at the same time.
congestion
A situation in which a place is too blocked or crowded, causing difficulties.
starvation
The state of having no food for a long period, often causing death.
poverty
The condition of being extremely poor which means that you don't have any money to use.