Because congress cannot predict which new chemicals will be invited. They cannot act quickly enough to actually adapt to realities of the world today.
Is CO2 a pollutant? Who decides? Congress or scientists? Judges or scientists?
Now do that for every tiny detail of every part of every law.
It is computationally intractable to write laws specifying every possible scenario and exactly how an agency should act.
I don’t think you realize that these laws were passed with the understanding that agencies would fill in these gaps. Congress wanted these agencies to make these decisions at the time these laws creating said agencies were passed.
Is CO2 a pollutant? Who decides? Congress or scientists? Judges or scientists?
Now do that for every tiny detail of every part of every law.
It is computationally intractable to write laws specifying every possible scenario and exactly how an agency should act.
I don’t think you realize that these laws were passed with the understanding that agencies would fill in these gaps. Congress wanted these agencies to make these decisions at the time these laws creating said agencies were passed.