1. We should think of alternatives. This is because these pesticides are toxic chemical whose usage leads to Bioaccumulation and Biomagnifications. 

2. When we use pesticides, they prevent our crop and food from pests effectively but indiscriminately destroys a vast number of other animals. 

3. This is causing unpredictable changes in food chains and upsetting the balance within the ecosystem. 

4. Most of the chemical pesticides that contain mercury, arsenic or lead are non - degradable. 

5. They enter into food chain, accumulate in the bodies of animals and pass right through food web. 

6. Being further concentrated at each step until animals at the top of the pyramid may receive enough to do considerable harm.

7. This is one of the reasons for ever decreasing number of butterflies, bees, small and large birds. 

8. Some of the pesticides are nerve poisons and might bring about changes in behaviour. 

9. As the human beings are at the end of the food chain, these pesticides may get accumulated in our bodies also. This shows some adverse effects on us, when their concentration becomes sufficiently high.