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OCR for page 52
Evaluation of Alternative Technologies for Disposal of Liquid Wastes from the Explosive Destruction System Appendix D Comparison of MMD and EDS Neutralent Toxicities The neutralents produced by the EDS have not been tested in animals for toxicity, so it can only be approximated from their chemical composition, which has a much lower degree of certainty than animal testing. Because the neutralizing reagents are present in considerable excess, it can be anticipated that they will make major contributions to the toxicity of the neutralents. Thus, neutralents generated by destruction of HD, GB, and VX will probably have toxicity characteristics of MEA, which include moderate to severe irritation of the skin, eyes, and respiratory tract. This inference is supported by findings that the dermal toxicity of neutralents generated by destruction of HD, GB, and VX in the MMD could not be distinguished from that of the MEA oxidant/ solvent system (NRC, 2001a). As discussed in Chapter 2, the chemical composition of the EDS neutralents may be more complex and variable than that of the neutralents from the MMD owing to the presence of energetics, their decomposition products, metals extracted from the munitions hardware and shaped charge residues, and miscellaneous compounds that may have been present in the munitions. Some of the metals identified in EDS neutralents generated at RMA and Porton Down are quite toxic to humans and/or the environment (e.g., Pb, Hg, Cd, As, and Ag) and, depending on their concentrations, could well contribute to the toxicity of the neutralents. In general, the energetics tend to be relatively toxic (see Table D-1). The lack of information concerning the identity and concentrations of all of the decomposition products formed by reaction of energetic compounds with MEA may make it difficult to estimate the potential contribution of energetics to the overall toxicity of the neutralent. Even if all chemical components of the neutralents were identified, the toxicity of the neutralents could not be predicted with certainty because (1) toxicity data may not be available for all of the components and (2) chemicals may behave differently in mixtures. Because of this, the toxicity of a neutralent can best be determined by mammalian toxicity studies. However, since the chemical composition of the neutralents produced by the destruction of different types of munitions could vary substantially, a number of representative neutralents would have to be subjected to toxicity tests in order to accurately predict hazards to humans and the environment. Because the time and cost of such an endeavor would be prohibitive and would strongly reduce the likelihood of meeting the CWC’s 2007 deadline, toxicity tests on the neutralents generated by EDS would not be practical, and toxicity estimates should instead be based on the most complete chemical analyses possible using standard EPA risk assessment methodologies.
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Evaluation of Alternative Technologies for Disposal of Liquid Wastes from the Explosive Destruction System TABLE D-1 Toxicity Characteristics of Energetic Compounds Effects of Exposure Compound Short-Term Exposure Long-Term Exposure Oral RfD (mg/kg)a HMXb Convulsions and other CNS effects; liver injury Liver and kidney damage; changes in red blood cells; no cancer or reproductive studies available 5E-02 RDXb Irritation of eyes, skin, and lungs; CNS effects (hyperirritability, convulsions) Damage to liver, kidneys; inflammation of the prostate; testicular degeneration; toxic to fetus. Possible human carcinogen (EPA Group C) 3E-03 Tetrylb Allergic contact dermatitis Fatigue, headache, anorexia, nausea, vomiting, upper respiratory tract irritation with sore throat, nose bleeds, coughing; liver damage Insufficient data Trinitrotolueneb Inhalation causes irritation of respiratory passages; skin contact can cause dermatitis; TNT readily absorbed through the skin and all routes of exposure can cause gastrointestinal disorders (e.g., nausea, anorexia, constipation) and cyanosis Liver damage, anemia, cataracts, neurological disorders. Possible human carcinogen (EPA Group C) 5E-04 aThe oral RfD is an estimate (with uncertainty spanning as much as an order of magnitude) of a daily exposure (by ingestion) to humans (including sensitive subgroups) that is likely to be without an appreciable risk of deleterious effects during a lifetime (EPA, 2001b). For comparative purposes, the Army has proposed RfDs for HD and VX of 7E-06 and 6E-07 mg/kg/day, respectively (NRC, 1999c). The EPA RfDs for some of the chemicals identified in the neutralents produced at Porton Down and RMA are as follows: mg/kg/day mg/kg/day Benzenec,e 3E-03 Bariumd 7E-02 Chlorobenzened 2E-02 Cadmium (in food)d,e 1E-03 1,4-Dichlorobenzenec,d 3E-02 Cadmium (in water)d,e 5E-04 1,4-Dithianed 1E-02 Trivalent chromiumd 1.5E+0 Hexavalent chromiumd,e 3E-03 bEPA (2000a). cEPA (2000b). dEPA (2001a). eBenzene and hexavalent chromium are recognized as human carcinogens, and cadmium is considered to be a probable human carcinogen by the EPA (EPA, 2001a).
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