Question

It is dangerous to throw harmful substances into river why?

Answer 1

because indirectly we use river water for cooking foods
how I think you are question in the mind will be have just wait
when we throw Hum dangerous Hum or harmful substances are harmful substances in the river water river water gets polluted and farmers use river water to irrigate plants crops and when we utilise your scrubs for our life daily life routine will also get me also might get might get diseases
and from that I conclude that when we throw harmful substances into the river when directly utilised as far as a food and we also get infected

Answer 2

Because fertilizers,lead , mercy,calicum, methane, Carbon monoxide, carbon dioxide , nitrogen and acidic medium of substrate and industrila wastage destroy the River aquatic life, Yamuna is the best example that you seen and that river is mostly valuable thing in country/state that development economics and cultural