They are the subtle killer of animals even though their main target is bugs.
They are also almost single handedly responsible for the near extinction of the Perigrin falcon in the 1980's.
They are pesticides.
Although rules and regulations have been improved they are still casuing particular damage in other countries who have no alternative to it. Not only are they killing birds but also fish and other marine life when they get sprayed on crops near the ocean. Then marine plants get infected with it which goes onto the fish up the food chain eventually to us. Efforts in other countries are being made to stop this.