Are they still using TCE[1] to manufacture semiconductors? That stuff is the major pollutant in silicon valley left over from all the early semiconductor manufacturing. There are a lot of really expensive homes and offices in Palo Alto that are built over sites where this stuff has leaked.[2]

[1] https://en.wikipedia.org/wiki/Trichloroethylene

[2] http://www.mercurynews.com/2016/07/05/palo-alto-stanford-can...