NCJ Number
190889
Date Published
1999
Length
12 pages
Annotation
This document provides a health risk assessment of tabun (GA).
Abstract
The chemical warfare agent tabun (GA) is an organophosphate nerve agent found at several stockpile and nonstockpile munitions sites in the United States and its territories. At the request of the Army, Oak Ridge National Laboratory (ORNL) conducted a health risk assessment of GA. The assessment included a detailed analysis of GA’s physical and chemical properties, environmental fate, 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 GA exposure. Because there was no evidence that GA is carcinogenic, a slope factor was not derived. The Army’s Surgeon General accepted ORNL’s proposed RfD as an interim exposure value until the National Research Council (NRC) conducted an independent evaluation of the proposed RfD. It was concluded that the approach used by ORNL to calculate the RfD for GA is consistent with the guidelines of the Environmental Protection Agency. On the basis of available toxicity and related data on GA, it was concluded that the Army’s interim RfD for GA is scientifically valid. The major gap in the available information on GA is the lack of subchronic or chronic oral toxicity studies from which to directly derive the RfD. If further research reveals that significant toxic effects can be induced by any of the nerve agents evaluated at doses below those that cause significant inhibition, new studies should be conducted to reassess the safety of the recommended RfD for GA. 1 table and 27 references