long-term effects of varying levels of exposure to these agents. For example, investigations of the systemic toxicity of short-term exposures to these agents to the gastrointestinal, immunological, and neurological systems are nonexistent. Further studies of the mechanisms of long-term damage to the respiratory system would also be useful. Despite intensive research on the mechanisms of sulfur mustard injury to the skin in animal models, little data exist regarding the long-term consequences of such injury.
In addition, the mechanisms of eye injury from sulfur mustard remain to be elucidated. For example, research on the effect of sulfur mustard on the ciliary body would disclose any changes in its vascular, nutritive, and transport functions. Research to determine the effect of sulfur mustard and Lewisite on limbal stem cells might be useful in determining whether stem cell replacement could reverse some of the adverse effects of injury. Finally, research directed at protection of the stromal component of the cornea might reduce the incidence of ulceration and perforation so common after chemical injuries to the eyes.
Although data exist on the reproductive toxicity of sulfur mustards in more than one animal species, it would be useful to have additional studies to examine the extent of the variability between species. More inhalation and cutaneous exposure studies would also be very helpful, as these exposure results would more accurately mimic human exposure. Certainly studying larger numbers of animals would provide a more sensitive measure of the possible magnitude of any reproductive risk associated with exposure to sulfur mustards. Short-term, high-dose exposures might also be helpful in attempting to examine any dose-rate effects.
The gaps in our knowledge of the toxicity and carcinogenicity of Lewisite based on animal studies are especially prominent, even in the most basic types of research. There is little information available in the literature concerning the reactions of Lewisite with biologically important molecules. Studies on the carcinogenicity or noncarcinogenicity of Lewisite need to be broadened and pursued with greater intensity. Much of the information obtained from these studies, unlike studies of sulfur mustard exposure, will have broad application in industry, farming, and medicine, because arsenic-containing chemicals are in wide use today.
There are also numerous gaps in the literature relative to the acute and long-term effects of Lewisite skin exposure. Very little is known regarding its specific effect on skin; data on such basic areas as absorption, disposition, and excretion after skin exposure are minimal. In addition, the morphological sites vulnerable to Lewisite are not known. Microscopic examination of affected skin has yet to be pursued in depth, although most studies have been impaired, as has