for business its difficult to meet the demand of so many customers which means they have to produce products at a higher rate. in mass factories this contributes to pollution and therefore global warming. furthermore, in urban areas it's hard to build enough houses / apartments for this many people, which leads to homelessness
Overpopulation puts a tremendous strain on resources. If too many people live in a place with too few resources (food, water, etc.), there are many negative effects. ... A lack of fresh water can lead to unsanitary living conditions, which can cause disease, infection and increased child and infant mortality.
