Counterintuitively, chemicals with high reactivity and high acute toxicity like HF are usually not the cause of semiconductor Superfund sites. The most common p

Counterintuitively, chemicals with high reactivity and high acute toxicity like HF are usually not the cause of semiconductor Superfund sites. The most common problem is chlorinated solvents used for cleaning. Trichloroethylene is a lot safer to spill on yourself than HF, but the hazards of TCE endure much longer than those of HF when it gets down into the water table. I don't know if modern fabs have mostly switched to less environmentally persistent solvents or if they're just a lot more careful about not discharging solvents to the environment.