I thought I hadn't, but then looked it up now and remembered it when I read about Tim Robbins taking everyone hostage. But I saw only once way back, so I can't remember much.
It's the pollution. To encourage economic development, the US encouraged a lot of pharmaceutical and other chemical companies to open factories there. They were lax about pollution control, so between the fumes and dumping, lots of toxiticity - also 2nd to NJ in that respect.
In the mid 80s, one town, Barceloneta, had to be permanently evacuated because the ground was so laden with mercury, maybe lead, stuff like that. No one knew either about that till the evac because it was always denied. Tests were finally done after all the pressure from everyone getting sick.
Another town, Barcelona (minus the "-eta"), is in the mountanious area next to EL Yunque National Rainforest. Agent Orange was tested there without anyone knowing prior to using it in Viet Nam. Literally sprayed it around. My grandparents lived 2 houses away from the park entrance.