During World War II, both sides produced millions of tons of chemical agents and also made preparations for their use but never employed them in combat. The United States focused its research on the development of protective clothing and skin ointments that would prevent or lessen the severe blistering of mustard agents.

There were three basic types of experiments that potentially exposed Service members:

1. Patch or drop tests. These were the most common tests and the Chemical Warfare Service used them to evaluate the effectiveness of protective or decontamination ointments in protecting against or treating mustard agent burns. These tests also evaluated how multiple exposures affected an individual’s sensitivity to mustard burns and the effects of physical exercise on these burns. Additionally, a drop of mustard agent was commonly applied to the forearms of basic trainees to impress them with the toxicity of the agent and the need to take appropriate action if exposed.
2. Chamber tests. These tests evaluated the effectiveness of protective clothing against mustard agent.
3. Field tests. These tests involved the contamination of an area of land with blister agent. Human subjects traversed this terrain to test protective clothing, to monitor the effects of agent on animals in the test site, and to measure agent concentrations in soil and water samples. Table 1 below shows the location of known major test facilities during World War II.

The only combat casualties from mustard during World War II occurred as a result of a German air raid on Bari Harbor, Italy. The John Harvey, a Liberty ship carrying mustard bombs to Italy, was sunk during the air raid resulting in the release of mustard agent.

In the late 1980s and early 1990s, some of the veterans exposed to mustard agent during World War II began to seek compensation from the Department of Veterans Affairs (VA) for health problems they believed to be connected to their exposure. The VA requested that the Institute of Medicine (IOM) convene a committee to survey the scientific and medical literature to assess the association between exposure to mustard agents and specific diseases. The IOM produced a report, "Veterans at Risk", that contained a series of findings and recommendations. One of the findings linked full body exposure to mustard agents to specific diseases. The report also recommended that the Department of Defese (DoD)/VA institute a program to identify veterans exposed to chemical agents during testing in World War II.

In the mid-1990s, the DoD compiled a list of veterans exposed to mustard agents during World War II. While compiling this list, DoD also identified veterans exposed to mustard agent as a result of transportation or storage accidents/incidents. Where possible, this list associates veterans with a specific test type or exposure and whether the test involved full body exposure to the agent. DoD provided this list to the VA.