The government released documents in 1994 revealing details about the spraying. And St. Louis wasn’t alone in being subjected to secretive Cold War-era testing. Similar spraying occurred at nearly three dozen other locations.

There were other types of secret testing. In a 2017 book, St. Louis sociologist Lisa Martino-Taylor cited documents obtained through a FOIA request to detail how pregnant women in several cities were given doses of radioactive iron during prenatal visits to determine how much was absorbed into the blood of the mothers and babies. The government also created radiation fields inside buildings, including a California high school.

The area of the testing in St. Louis was described in Army documents as “a densely populated slum district.” About three-quarters of the residents were Black.

Jesus christ, there's always some new atrocity we're learning about.

In the 1950s and 1960s, the Army used blowers on top of buildings and in the backs of station wagons to spray a potential carcinogen into the air surrounding a St. Louis housing project where most residents were Black. The government contends the zinc cadmium sulfide sprayed to simulate what would happen in a biological weapons attack was harmless.