All I know is the stealth stuff is supposedly really nasty. Lockheed had a bunch of employees at Groom Lake sue over it. They weren’t even working with it, but they worked near some pits where a bunch of the stuff had been buried. They had a variety of really strange ailments and illnesses. Lockheed argued they could not possibly been made ill by that stuff since it was buried.
We’ll never know what could have been proved because the government stepped in and made it very clear to Lockheed that none of this business was going to be discussed in open court nor allowed by the discovery process. So Lockheed settled with the workers.