Dear student,
Yes, plastic is harmful because of the following reasons:
1)Plastic is not a biodegradable substance, hence will not be decomposed by the microbes in the atmosphere.Thus, will accumulate in the environment and cause pollution.
2)Various toxic chemicals are released from the plastics and the exposure of these chemicals in humans may lead to cancers, birth defects, and other diseases.
3)These toxic chemicals can also drain out from the plastic into the groundwater and flow downstream into lakes and rivers. Thus, affect the aquatic life.
4)Various animals and other organisms eat it by considering as food and thus it leads to the death of animals like cow due to the choking of plastic in their food pipe.
5)The poison released by plastic can also enter the food chain and affect the stability of the ecosystem.
Regards