i. All kinds of plastics give out harmful gases, upon heating or burning. These gases may cause many health problems, including cancer, in humans.
ii. Stray animals, while looking for food in the garbage thrown in plastic bags, end up swallowing them. 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. As a result, drains get choked and the water spills on the roads. During heavy rains, it might even create a flood like situation.
