In the midst of the Cold War, the Army released chemicals into the air using motorized blowers atop a low-income housing high-rise and elsewhere in predominantly black areas of St. Louis.
The secret testing was exposed in the 1990s, but new research is now raising greater concern about the implications.
St. Louis sociology professor Lisa Martino-Taylor released her research last month. It was troubling enough that both U.S. senators from Missouri wrote to the secretary of the Army demanding answers, including whether radioactive testing was performed.
Some people who grew up in the targeted area wonder if the testing caused cancer and other health problems for them and their relatives.
An Army spokesman declined an interview request, saying the Army would first respond to the senators.