Lewisite elimination

The foundation of the CWC s inspection activities was based around the declaration by member states of their chemical weapons capabilities and activities. Nations with chemical warfare programmes were required to declare their production, storage and destruction facilities, which would then receive top monitoring priority. Nevertheless, the CWC did allow states to maintain research programmes to ensure the integrity of defensive equipment such as gas masks and gas detectors, but these activities were also to be closely monitored since they involved work with the chemical agents listed on Schedule l.9 Otherwise, all other warfare agents, mustard gas, Lewisite, soman, sarin, tabun, VX and the capability to produce them were to be eliminated under the watchful eyes of international inspectors (Table 8.1).10 The convention thus defined chemical weapons as any toxic chemical, or its precursors, intended for purposes other than those not prohibited under this convention for... 

Regardless of the method of lewisite degradation (combustion, hydrolysis, or other environmental degradation), the arsenic component will not be eliminated and, therefore, at least some combustion product or other degradation products may be some form of arsenical. The recognized degradation products of lewisite are listed in Table 1. 

Vesicants including sulfin" mustard and lewisite are the subject of the second main part of this contribution. Coherences of invasion and distribution are presented and the major processes of metabolism and elimination caused by binding to proteins and more prominently to DNA are discussed. The part closes with comments on current bioanalytical approaches. 

Snider et al. (1990) determined the elimination of lewisite from rabbits after p.c. injection. Half-life was determined, ranging from 55 to 75 h. A clearance of 120ml/h/kg was found. However, these findings only describe the overall elimination of arsenic from the organism, following a lewisite exposure. 

Dimercaprol (British Anti-Lewisite, BAL). Arsenic and other metal ions are toxic in low concentration because they combine with the SH groups of essential enzymes, thus inactivating them. Dimercaprol provides SH groups which combine with the metal ions to form relatively harmless ring compounds which are excreted, mainly in the urine. As dimercaprol, itself, is oxidised in the body and renally excreted, repeated administration is necessary to ensure that an excess is available imtil all the metal has been eliminated. 

Analytical Methods for Urine and Blood. Specific biomarkers of lewisite exposure are currently based on a very limited number of in vitro experiments (Jakubowski et al., 1993 Wooten et al., 2002) and animal studies (Logan et al., 1999 Fidder et al., 2000). Wooten et al. (2002) developed a solid-phase microextraction (SPME) headspace sampling method for urine samples followed by GC-MS analysis. It is the most sensitive method reported to date with a lower limit of detection of 7.4 pg/mL. Animal experiments have been limited in number and in their scope. In one study of four animals, guinea pigs were given a subcutaneous dose of lewisite (0.5 mg/kg). Urine samples were analyzed for CVAA using both GC-MS and GC coupled with an atomic emission spectrometer set for elemental arsenic (Logan et al., 1999). The excretion profile indicated a very rapid elimination of CVAA in the urine. The mean concentrations detected were 3.5 pg/mL, 250 ng/mL, and 50 ng/mL for the 0-8, 8-16, and 16-24 h samples, respectively. Trace level concentrations... 

The war period naturally witnessed the accumulation of a considerable amount of excess property by the CWS. Among the causes of this development was the elimination of certain munitions such as the M54 bomb and lewisite. When these programs were discontinued the items were declared surplus, and in the case of lewisite the plants also. When a manufacturing program was eliminated the machinery in the plant gen-... 

Lewisite has extensive tissue distribution (HSDB, 2008). The highest concentrations were foimd in the liver, lungs, and kidneys in rabbits (>7 times blood concentration). Arsenic crosses the placenta and is excreted in the milk. Therefore, nursing animals may be at risk (Barlow and Sullivan, 1982). The elimination half-life of arsenic in rabbits is 55-75 h (HSDB, 2008). For further details on toxicity of arsenic and levHsite, see chapter 15. 

---