Power
First of all, we need to introduce an important distinction: Scientists at the EPA don't make the laws and policies about environmental conduct, like putting limits on what types of pesticides can be used on strawberries. Lawyers and other policy staff handle that stuff at the EPA.
Scientists are more concerned with conducting good science that will inform those lawmakers and support other agency decisions—think of them as the field scouts who figure out exactly what's over that hill over yonder so the lieutenant back at base can figure out what to do next.
Does producing good science translate into wielding power? Um...
An EPA scientist may be a thousand percent sure that global warming will turn Earth into a cosmic crispy critter in a couple of lifetimes. But politicians, who have all they power, can just say no. These may be the same politicians who mutter constantly about voting the EPA out of existence.
Now, who has the power?
Certainly not the EPA science minions.