Widely used chemical *(that was generally phased out in the 70s) linked to Parkinson's. Still important, but you don't need to start searching product labels in 2023 for it.
Some of the most populated zones of the Bay Area are built on top of superfund sites, which have high concentration of TCE underground. https://www.epa.gov/superfund-redevelopment/superfund-sites-...
Growing up I knew a lot of kids that were affected by it, they were called "fairchildren" or a "fairchild".
I was born elsewhere and my family moved to the area, the kids that were born there weren't so lucky.