PCBs are still ever present because they were banned but not removed from use. The result is over the decades since the ban, there were spills and other contamination.
Removing "flame-retardants, plasticizers, paints, caulking compounds, sealants" from buildings seems overreach, you'd probably have to raze them. They didn't even do that for asbestos or lead paint.
What exactly are you talking about?