NCJ Number
190894
Date Published
1999
Length
10 pages
Annotation
This document provides a health risk assessment for the chemical warfare agent lewisite.
Abstract
Lewisite is an organic, trivalent arsenic compound. It is classified as a vesicating agent because of its ability to cause blisters on exposed skin. Lewisite is present at several stockpile and nonstockpile munitions sites in the United States. At the request of the Army, Oak Ridge National Laboratory (ORNL) conducted a health risk assessment of lewisite. The assessment included a detailed analysis of lewisite’s physical and chemical properties, environmental fate, toxicokinetics, mechanism of action, and animal and human toxicity data. On the basis of that assessment, ORNL proposed a reference dose (RfD) of a number of milligrams/kilograms of body weight per day for noncancer health effects of lewisite. Because there was no evidence that lewisite is carcinogenic, a slope factor was not derived. The Army’s Surgeon General accepted ORNL’s proposed RfD as an interim exposure value until an independent evaluation of the proposed RfD was conducted by the National Research Council. It was concluded that the approach used by ORNL to calculate the RfD for lewisite was consistent with the guidelines of the Environmental Protection Agency. However, the ORNL’s proposed RfD per day, which is based on studies in a rat, was not accepted. Deriving the RfD on the basis of a rabbit study, the figure was more conservative than the Army’s interim RfD. The major gaps in the available information on lewisite were the lack of information on the implications of administering lewisite directly to the stomach over a short time and the absence of chronic oral toxicity data from which to derive an RfD. It was believed that the potential environmental and metabolic breakdown products of lewisite were not well identified. 1 table and 14 references