Why is it essential to have proper disposal of wastes?

It is essential to have proper disposal of wastes because careless disposal can lead to following problems:

1. can cause spread of diseases
2. can aggravate problem of insects, flies and rodents
3. toxic substances in waste can cause cancer and genetic disorder
4. colour pigment of plastics contain heavy metals.
5. Some chemicals present in waste like cyanides, polyclorinated phenyls and mercury are very toxic and can lead to death.