People use the open space by the river to grow vegetables, which is very common in life. Do you think vegetables can be used if rivers are polluted by industrial wastewater? Why?

Definitely can't eat, not only vegetables, but also fish and shrimp in the river. You can't feed chickens, ducks and pigs. I once saw a popular science film, saying that aquatic plants in the sea are polluted, and animals such as fish and shrimp are polluted after eating aquatic plants, and people are eating animals such as fish and shrimp. The more advanced animals, compared with the lower animals and plants, are more difficult to eliminate toxins in their bodies once they are polluted. So, don't be greedy for cheap and convenient, and eat those polluted things. It's good to say that you don't know whether the things in the market are clean or not, but you can't eat those things that you know are bad.