percentage of individuals. It is the judgment of this committee that the best available evidence indicates a causal relation between the experiences of the subjects in chamber and field tests of mustard agents and Lewisite and the development of adverse psychological effects. These effects may be highly individual, but diagnosable, and may include long-term mood and anxiety disorders, PTSD, or other traumatic stress disorder responses. In addition, some of the experiences of those who worked with chemical warfare agents or who were exposed to sulfur mustard at Bari harbor, such as explosions, injuries, and witnessing of injury and death, may also have resulted in development of such adverse psychological effects.

There are many aspects of the chamber and field test situations that individually may have been sufficient to produce adverse psychological effects in certain human subjects. These include (1) the number and duration of chamber trials in the presence of live agent and under hot, humid conditions; (2) the inability to escape the chamber without fear of severe reprisals; (3) the sight and/or experience of severe blistering, especially to genital areas; (4) the young age and lack of adequate preparation of the subjects; (5) the commands of secrecy and its resultant isolation of subjects; and (6) certainty that an exposure occurred (in the chamber tests, evidence of exposure was the end point of the experiments). Such conditions certainly qualify as "outside the range of normal experience" and they would be upsetting to almost anyone. For those involved with handling warfare gases, who witnessed or were injured by explosions and other types of accidents, these would also qualify as stressful experiences outside the normal range of human experiences.

The aspects above are, however, only part of the total experience of many of the human subjects. The passage of time, the imposed silence, the lack of medical follow-up, and the institutional denials have almost certainly complicated the original trauma and worsened its effects. Such effects would include hypervigilance and the establishment of long-held beliefs regarding health problems and their causes.

Despite intensive research, it is not possible to know the degree to which PTSD and other psychological disorders are accompanied or caused by physiological perturbations such as changes in hormone levels, tone of the autonomic nervous system, levels of circulating lymphocytes, and other measures of physiological function. It is not possible, therefore, to draw any conclusions about specific physiological conditions and their possible psychological concomitants or causes.