In 1987, the CDC halted the evaluation of veteran exposure to Agent Orange, stating records were insufficient to determine the troops that had been exposed to the chemical. In the CDC’s own words: “It is unlikely, therefore, that military records can be used to identify a large number of US Army veterans who might have been exposed to [Agent Orange] in Vietnam.”

Instead, the CDC looked to the then-current levels of dioxin as an “indicator to exposure” – and concluded “that few Army ground troops had been heavily exposed to herbicides in Vietnam or elsewhere.” From this result the CDC decided against probing the study further.