Exposure limits , chemical warfare agents

B) Low Level Exposure of Agents The Commission also requests the Committee include within its Risk Management and Safety Review the incorporation of the latest information available on the impact of low-level exposure of agents. The Commission requests this review include, but not be limited to, the issues raised in DoD Strategy to Address Low-Level Exposures to Chemical Warfare Agents (May 1999). 

Interim Recommendations for Airborne Exposure Limits for Chemical Warfare Agents H and HD (Sulfur Mustard)." Federal Register 69, No. 85 (May 3,2004) 24164-24168. 

A wide variety of commercial equipment is available for detection of hazardous chemicals, including a number of chemical warfare agents. For example, ion mobility spectroscopy is used to detect nerve, blister, and blood agents. The Chemical Agent Monitor is a portable, hand-held point detection instrument that uses ion mobility spectrometry to monitor nerve or blister agent vapors. However, minimum detection limits are approximately 100 times the acceptable exposure limit for nerve agents, and approximately 50 times the acceptable exposure limit for blister agents. 

In countries dealing with destruction of chemical warfare agents, control limits for exposure via surface contact of drinking water are needed, as are detection methods for their low levels in water, soil, or foodstuffs. Some of the toxicity parameters of RVX for humans and animals are available in the text A Book of Instructions and Technical Documentation on the Problem of Chemical Weapon Destruction (Anon, 2001), and are given in Table 7.6. 

This chapter focuses upon decontaminating skin exposed to chemical warfare agent (CWA). Although the protective equipment chapter discusses effective barriers to protect an individual, there is a high probability that the items may not be worn at the time of an attack. Consequently, the next barrier, the skin, becomes critical, but has a limited time before it allows an agent to penetrate. Rapid decontamination is of utmost importance, before the skin barrier is compromised. To best understand the process, this chapter will discuss military and civilian issues concerning skin exposure, the characteristics of the skin itself, medical protective measures, and evaluation of skin decontaminants. 

Most attempts at describing CWA PK and PD have used classical kinetic models that often fit one set of animal experimental data, at lethal doses, with extrapolation to low-dose or repeated exposure scenarios having limited confidence. This is due to the inherent nonlinearity in high-dose to low-dose extrapolations. Also, the classical approach is less adept at addressing multidose and multiroute exposure scenarios, as occurs with agents like VX, where there is pulmonary absorption of agent, as well as dermal absorption. PBPK models of chemical warfare nerve agents (CWNAs) provide an analytical approach to address many of these limitations. 

There are clear ethical constraints that prevent human research that could definitively answer the questions of concern regarding the military operational and civilian health risks of exposure to low-levels of chemical warfare nerve agents. Only three sources of relevant human data are available for analysis. These data are from either past human volunteer studies, reports based on accidental exposures, or reports of the consequences of malicious releases of the agents. While these sources are valuable, the data have some limitations for deriving dose-response relationships because of inferior analytical and clinical methods or the lack of precise estimates of exposure. 

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