2, Yes, they do.
1, Overpopulation can lead to:
-Overcrowding and poor quality housing in many large city.
-Because of the poverty, many people have to live in slums, so they get a lot of disease.
-There are many crimes in slums.
-Too many vehicles cause air pollution and noise.
-Overpopulation can create the homless and hunger.
-There is not always enough food, not enough clean and fresh water, not enough school for children.