gaps on the toxicity of lewisite, and the usefulness of most of the studies is limited by the lack of a satisfactory animal model. Little information exists on the reaction of lewisite with biologically important molecules, although it is reasonable to assume that, as with sulfur mustard, DNA is a major target (IOM, 1993).

There are no adequate data on the acute effects of lewisite following dermal exposure. Very little is known about its specific effects on skin, and data on its absorption, disposition, and excretion following dermal exposure are minimal. Microscopic examination of affected skin has not been pursued extensively.

The proposed Army standards for exposure to lewisite in field drinking water were derived from a rabbit study, in which the NOAEL was estimated to be 0.016 mg/kg/day (Hackett et al., 1987b). Converting the arsenic fraction of 0.0058 mg/kg/day to total consumption per day for a 70-kg human consuming 5 L or 15 L of water per day gives (0.0058 × 70)/(5 or 15 L) = 0.08 and 0.027 mg/L, respectively. No additional safety factors were assumed. Whether the rabbit is the species most sensitive to lewisite is not known, and the applicability of the rabbit data to the human situation requires further evaluation. It is recommended that future consideration should include a comparative analysis of pharmaco-kinetics, metabolism, repair mechanisms, and genetic constitutions.

Neurological effects following acute exposure to lewisite have not been documented in animals. Acute exposure to high concentrations of lewisite leads to a shock syndrome that is thought to result from increased capillary permeability (Goldman and Dacre, 1989). No direct evidence exists that lewisite might cause neurological problems in humans, although arsenic is considered a neurotoxin and peripheral neuropathy has been reported in humans following a single arsenic exposure (Le Quesne and McLeod, 1977).

Given the limited data on the acute health effects associated with exposure to lewisite through ingestion of water by animals and humans, the subcommittee concludes that the Army's proposed interim standards for lewisite in military field drinking water are sufficient to reduce the risk of lewisite-induced health effects or performance degradation.

FRONT MATTER (R1-R14)

CONTENTS (R15-R18)

EXECUTIVE SUMMARY (1-10)

1 INTRODUCTION (11-14)

2 GUIDELINES FOR 3-QUINUCLIDINYL BENZILATE (15-18)

3 GUIDELINES FOR ORGANOPHOSPHORUS NERVE AGENTS (19-28)

4 GUIDELINES FOR SULFUR MUSTARD AGENTS (29-36)

5 GUIDELINES FOR T-2 TOXIN (37-42)

6 GUIDELINES FOR LEWISITE (43-48)

7 GUIDELINES FOR CYANIDE (49-54)

REFERENCES (55-66)

APPENDIX A (67-76)

APPENDIX B (77-80)