Dr. Jan Medema's article "The Myth of Dusty Agent" written for the ASA Newsletter 07-1 and the response written by Dr. Benjamin Garrett for ASA Newsletter 07-2, highlighted misconceptions which continue to plague users across the broad protection sphere.
          ASA intends to follow-up the preceding with a series of articles on the protection disciplines. These articles will surface, highlight and challenge "conventional wisdom" which appears to be based more on fallacy, hearsay and the not invented here (NIH) syndrome, than on science and common sense. For this article on skin decontamination and the issue of time, our panel consists of Murray Hamilton, PhD, CBW Programs, University of Denver Research Institute; Barbara Price, PhD, ASA/CBMTS/ICBPS; Nayla Feghali PE, Senior Director Healthcare Decontamination, E-Z-EM; Phillip O'Dell, original licensee RSDL and J. Garfield Purdon PhD, Decontamination Hazard Research, DRDC, Suffield.

Skin Decontamination:
A Critical Medical Countermeasure

          Historically, the focus of skin decontamination has been the immediate removal of chemical warfare agents (CWA) by adsorbent powders, such as Fuller's Earth. With the modern emphasis on antidotes and other medical treatments, does skin decontamination still have a role as a countermeasure? If the CWAs are neutralized by skin decontamination, is delayed application of neutralizing decontaminants beneficial?

          As a result of recent advances in technology at least one liquid product that can remove or neutralize a broad spectrum of CWA, e.g., RSDL from E-Z-EM, has been fielded. In vivo and in vitro studies demonstrate that both immediate and delayed skin decontamination are important medical countermeasures against nerve and blister agents, especially when the skin decontaminant can neutralize the agents.

          The following points and references are provided to encourage further study and discussion.

Nerve Agent - VX:

  1. Although VX acts quickly, there is time to use decontaminants on VX poisoning. In an in vitro study of the rate of VX penetration through skin, 1.25 mg/cm2 of VX penetrates unprotected skin in approximately three hours (a penetration rate of 2.52 µg/cm2.min.).
    • Van Hooidonk, C.; van Genderen, J.; Purdon, JG.; Barnard, RAB. The Efficacy of Barrier Creams Against VX on Skin. TNO Prins Maurits Laboratory, Diverse and Dynamic, 37 Examples of Research, pp. 52-55, 1988.
  2. RSDL limits VX poisoning. In an in vivo study, when applied on skin, VX completely inhibits whole blood cholinesterase within 45 minutes. Application of RSDL™ within 15 minutes after exposure to VX completely halts this cholinesterase inhibition and thus prevents further inhibition and death.
    • Lundy, PM.; Hamilton MG.; Hill, I.; Conley, J.; Sawyer, TW.; Caneva, CD. Clinical Aspects of Percutaneous Poisoning by the Chemical Warfare Agent VX: Effects of Application Site and Decontamination. Military Medicine. 2004, 169, 11:856.

Vesicant Agents - HD:

  1. Mustard penetrates skin quickly but symptoms take time to appear. Signs and symptoms of HD poisoning do not appear immediately, but the liquid agent absorbs into the skin quickly. The rate of HD penetration ranges from 60-290 µg/cm2.min., about 20 times faster than VX.
    • Chilcott RP, Jenner J, Carrick W, Hotchkiss SA, Rice P. Human skin absorption of Bis-2-(chloroethyl) sulphide (sulphur mustard) in vitro. J Appl Toxicol. 2000 Sep-Oct;20(5):349-55.
  2. Skin injury from HD can be minimized through rapid physical removal (decontamination) of the agent. Later removal, or "delayed decontamination", has also been shown to significantly lessen the symptoms and accelerate the healing process of an HD burn. In part, this is due to a dermal reservoir of HD in humans. This reservoir was first suggested in World War I. Field practices demonstrated that HD injuries could be prevented by washing contaminated skin with an appropriate solvent even up to 45 minutes post-exposure. Since then studies have shown that these human dermal reservoirs hold a substantial amount of the initial HD dose up to 24 hours following exposure. This reservoir implies that agent transfer (cross contamination) may produce injuries to medical personnel treating mustard victims.
    • Graham, JS.; Chilcott, RP.; Rice, P.; Milner, SM.; Hurst, CG.; Maliner, BI. Wound Healing of Cutaneous Sulfur Mustard Injuries, Strategies for the Development of Improved Therapies. J Burns Wounds. 2005; 4:el. Available at: http://www.pubmedcentral.nih.gov
  3. RSDL removes HD. In in vitro studies, RSDL removed >97% of the initial dermally applied HD dose when applied at two times, 4 and 30 minutes following initial exposure. RSDL also removed >95% of the initial dermally applied VX dose at 4 and 30 minutes following initial exposure.
    • Van Hooidonk, C.; Langenberg, JP. Comparison of the in vitro efficacy of four skin decontaminants towards three chemical warfare agents. TNO-Prins Maurits Laboratory. PML 1 994-889. January 1995.
      Note: HD does not cause the same physiological signs as the nerve agents and indications of exposure will be different; convulsions are not symptoms of HD poisoning.

Value of Immediate and Delayed Use

It is the consensus of the panel that there is time to apply skin decontaminants and in light of the newest technology, there are benefits even when application is delayed. Beyond the obvious removal or neutralization of CWA, there are additional benefits to use:

  • Agent trapped under the respirator mask or agent desorbed from powders trapped under the mask pose an inhalation threat unless dissolved or neutralized.
  • Absorption of CWA through the skin is increased when the surface area of CWA droplets is increased by smearing. Smearing can occur during mask application, rubbing, or water rinsing. Decontamination of this area is critical.
  • Agent reservoirs on and under the skin continue to be a cross-contamination threat to warfighters and care-givers until the CWA is decontaminated.
  • Decontamination provides a value even when an atropine/oxime auto-injector is used. Antidotes in an auto-injector are to be used after the nerve agent's physiological signs and symptoms appear. This particular countermeasure gives the users sufficient time (4 to 6 hours) to receive medical treatment (typically, at a field hospital). However, in the absence of decontamination, nerve agent remaining on the skin will continue to be absorbed. This is likely to overwhelm the antidotal effect of the injected atropine/oxime and cause further poisoning and deterioration of the casualty.
  • The warfighter's confidence in training and tools to defend against chemical attacks has a direct impact on combat effectiveness and morale. The use of skin decontamination provides the warfighter with an important tool, should exposure occur through breach of protective equipment by accident, trauma, or late donning. Lowered combat effectiveness can put a mission at risk.
  • First responders and medical personnel, in the capacity of care-givers, can be put at risk when exposed to CWA casualties through touch or inhalation and vapor contact with skin and eyes from off-gassing CWAs. Nurses and doctors treating victims after the Tokyo sarin (GB) attack became victims, as did the doctors and responders during mustard attacks on Kurds and Iranians, and as did nurses in the UK when treating newly arrived mustard casualties from Iran (the Iran/Iraq war). Decontamination, not just dilution or temporary adsorption, of CWA can minimize or eliminate this threat.

Editor's Note: ASA welcomes both your comments and your articles as well as your recommendations which would help shed light on some of the misconceptions that persist throughout the protection community.



For the Professional in Government and Industry with an interest in Nuclear, Biological and Chemical Defense, Disarmament and Verification; Emergency and Disaster Medical Planning; Industrial Health and Safety; and Environmental Protection


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