Demerits of plastic:
(i) Plastics give out harmful gases upon heating or burning. These gases may cause many health problems, including cancer in humans.
(ii) Some people often fill garbage in plastic bags and throw it away in open. When stray animals look for food in these bags, they swallow plastic bags along with food. Sometimes, they die due to this.
(iii) The plastic bags thrown away carelessly on roads and other places get into drains and the sewer system.
These plastic bags choke the drains. As a result dirty water spills on road. It causes spread of bad smell and diseases.