[GAO report GAO/NSIAD-93-89 February 1993, Results and Background] There were at least three secret chemical experiments conducted between 1942 and 1975: the Navy's and the Army's World War II mustard agent experiments and the Army's incapacitating agent tests of the Cold War era. All of these tests have been declassified by the services since at least 1975. Because of a lack of data, making decisions on the validity of veterans' disability claims associated with mustard agent experiments has proven to be difficult for VA. This has not been a problem with claims associated with incapacitating agent tests because the Army has the necessary information. Before July 1992, the VA required that veterans prove that their medical problems resulted from their participation in the mustard agent tests. Few veterans, however, could prove this relationship. Thus, until 1992, only 13 of 145 claims for benefits were approved by VA. VA has recently recognized that the veterans' problems may be attributable to the fact that the experiments were conducted secretly, with no provision for medical follow-up testing. In July 1992 VA revised its adjudicating procedures for these types of claims. To receive compensation, veterans with specific health problems known to be associated with exposure to mustard gas now need only to show that they participated in mustard agent tests. However, because there is only limited information available on test participants, VA will continue to have difficulty deciding whether veterans' claims are valid. VA, for example, has not been able to validate veterans' claims of participation in mustard agent tests because the services do not have complete information on the test sites, the dates of the tests, and the units involved. Moreover, what information is available is widely dispersed in records held at numerous military locations. No effort has been made to aggregate the existing data. VA has made other efforts to serve veterans who may not be receiving deserved compensation for their participation in the tests. For example, the agency had the National Academy of Science study the long-term effects of exposure to mustard gas to ensure VA'S list of chronic conditions resulting from mustard agent exposure is complete. VA'S only outreach effort to identify veterans involved in these tests was hampered by the limited amount of information available on the testing programs. In this 1991 outreach effort, only 128 veterans out of the thousands that participated could be identified from existing information. Future outreach efforts could be enhanced if the Army and Navy provided VA with all available information on the location of the test sites, the dates of the mustard agent tests, and the units involved. ----------------- Since at least World War I, the military has conducted medical, chemical, and biological research using military personnel who have volunteered. This research is done to maintain and protect the health of military personnel who may be exposed to a variety of diseases and combat conditions. Military procedures have long required that the volunteers be fully informed of the nature of the studies in which they participate and the foreseeable risks. However, prior to 1975, these procedures were not always followed.