Santa Susana Field Laboratory (opens in new tab)

"residents living within 2 miles of the laboratory are 60% more likely to be diagnosed with certain cancers compared to residents living 5 miles from the laboratory."

This new housing development is a mere 1300 ft away:

https://www.kbhome.com/new-homes-los-angeles-and-ventura/arr...

Portions of this were burned recently in the Woolsey fire, likely leading to some release of toxic chemicals. How much is hard to say, but authorities have been doing their best to downplay risks for decades.