Farmers use various fertilizers and pesticides (chemicals) to protect their crops and plants from diseases. These chemicals are absorbed by the plants along with water and minerals from the soil and are taken by aquatic plants and animals as well.

And since these chemicals are non-biodegradable, they will remain in the food chain. Humans are the final consumers of every food chain hence, all of this chemical gets in their body when they feed on organisms or plants of the lower trophic level. In this way, these fertilizers can cause harm to us.