None of the residents, nor the authorities of St. Louis, nor those of Missouri, nor the health authorities, nor the Congress were notified of the tests. Army records data indicate that some of the substance traveled upwards of forty miles, carried by the prevailing winds.
The Army conducted their experiments a second time, from 1963 to 1965, in comparable secrecy. Army officials reiterated that the compound being sprayed, zinc cadmium sulfide, was harmless, without acknowledging the addition of FP226.
By the 1990s, evidence of abnormal incidence of several types of cancer among former residents of the areas involved, including the Pruitt-Igoe housing complex, drew the attention of researchers and forensic specialists. The Army denied that any of the materials sprayed as part of the chemical weapons research were toxic, and resisted congressional inquiries. Since the tests were conducted several links have been established, though not definitively proved, between zinc cadmium and varying forms of cancer. The distribution of potentially radioactive and carcinogenic material is only part of the troubles leftover from the Army’s testing on unknowing subjects; growing anecdotal evidence links zinc cadmium sulfide to chronic lung and respiratory ailments such as COPD.
As of 2012, the official position of the US Army remains that no harmful materials were distributed as part of the testing.
The Pruitt-Igoe Housing project was abandoned by the early 1970s and destroyed by demolition over the course of several years. By late 1976 it was gone. In April 2016 the US Army Corps of Engineers made news when it dropped the former site of Pruitt-Igoe from consideration as a home for the National Geospatial-Intelligence Agency’s (NGA) western headquarters complex. The Corps of Engineers did not cite a specific reason for dropping the site from consideration despite previously reporting on it favorably.
Local authorities claim, with some support from officials with the NGA, that the site was dropped from consideration because of the presence of toxic materials contaminating the site. While some of those toxins are undoubtedly asbestos and lead, persistent reports of radioactivity appear in local media and government discussions of the site.
Army records of the St. Louis testing, formalized as part of Operation LAC (for Large Area Coverage, the Army name for their testing) remain classified as of 2017. Whether or not the Army had knowledge – then or now – that it was spreading toxic radioactive material over a wide swath of the mid-west remains hidden behind the screen of national security, despite it taking place more than sixty years ago. What is undisputed is that the Army conducted experiments on unknowing citizens, some of whom may only recently be experiencing the effects.
Besides the zinc cadmium sulfide, recent revelations by researchers and the Army establish that other toxins were distributed as part of Operation Lac, including serratia marcescens, a bacteria linked to hospital infections; bacillus globigii, a biological warfare stimulant; bacillus subtilis, used to treat urinary tract disease; and aspergillus fumigates, which causes diseases in those with autoimmune disorders.