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Decontamination of Chemical Casualties
Chapter 16
* Scientist, US Army Medical Research Institute of Chemical Defense, 3100 Ricketts Point Road, Aberdeen Proving Ground, Maryland 21010-5425
Lieutenant Colonel, US Air Force; Instructor, Air Force Liaison, and Occupational Therapist, US Army Medical Research Institute of Chemical
Defense, 3100 Ricketts Point Road, Aberdeen Proving Ground, Maryland 21010-5425
Colonel (Retired), Medical Corps, US Army; Director, Chemical Casualty Care Division, US Army Medical Research Institute of Chemical Defense,
3100 Ricketts Point Road, Aberdeen Proving Ground, Maryland 21010-5425
Medical Aspects of Chemical Warfare
Decontamination is the process of removing or
neutralizing hazardous substances from people, equip-
ment, structures, and the environment. 1,2 This chapter
focuses on the safe decontamination of medical casual-
ties exposed to chemical agents; however, the patient
decontamination process discussed here also is appro-
priate for those exposed to biological and radiological
hazards (although procedures, operator protective
ensemble, and detectors may vary slightly).
Decontamination performed within the first few
minutes after exposure is the most effective for protect-
ing the patient, although later skin decontamination,
which can benefit the patient by reducing the agent
dose, should not be ignored. Early skin decontamina-
tion can often mean the difference between patient
survival (or minimal injury) and death (or severe
injury). Patient decontamination serves two primary
purposes: (1) protecting the casualty by removing
harmful agents from the skin, thus reducing the dose
and severity of the agent’s hazardous effects, and (2)
protecting emergency responders, transport personnel,
medical personnel, and other patients from second-
ary exposure. Cross contamination from dry or liquid
agent on the patient’s clothing or skin can sicken others
or make equipment temporarily unusable. Cloth fibers
can hold agent liquid and vapors. The off-gassing of
liquid contaminants, or vapor trapped in clothing and
hair, can cause those who work near the casualty to be-
come symptomatic if they are not wearing respiratory
protection. Often removing clothing and brushing the
hair greatly reduces the level of contaminant carried
on the patient; in some instances, these actions are the
only necessary decontamination.
Contaminated persons who present for decontami-
nation may additionally have conventional wounds,
psychological stress reactions, physiological reactions
to heat or cold, or any combination of these. Persons
wearing individual protective ensemble (IPE) are
particularly prone to heat injuries caused by extended
time in this gear.
The decontamination of chemical casualties is a
challenging task that may require large numbers of
personnel, water and equipment resources, and time.
Casualty decontamination takes place at all levels of
patient care, from the exposure site to the door of the
medical treatment facility (MTF). In the military, there
are three levels of patient decontamination (these same
processes may differ in the civilian sector) 3 :
with plastic and loaded into a transport ve-
hicle dedicated to evacuating contaminated
patients. Evacuation vehicles are kept well
ventilated, and crew members wear protec-
tive ensemble. Operational decontamination
helps to reduce the level of contamination
on the patient, thereby reducing the level of
cross contamination to the transport vehicle.
This level of decontamination allows for
large numbers of contaminated casualties to
be quickly evacuated to patient decontami-
nation facilities that are prepared to handle
3. Patient thorough decontamination is performed
outside the MTF that receives the contaminat-
ed patients. At the decontamination station
the patients’ clothing is removed and their
skin and hair are thoroughly decontaminated.
It is critical that patients are prevented from
entering a medical facility until patient thor-
ough decontamination has been conducted.
1. Immediate decontamination is conducted by the
individual exposed to the agent, or another
individual (a buddy), who comes to assist
the victim, as soon as possible after exposure.
Ideally it is performed within minutes after
exposure. The individual decontaminates
exposed skin and garments using a military
decontamination kit. If a kit is not available,
any material, dry or wet, that can be applied
or used to physically remove agent from the
skin is beneficial. This process is very effec-
tive in reducing the hazard posed by agent on
the skin, particularly if IPE is already being
2. Patient operational decontamination is carried
out by members of the individual’s unit to
prepare the individual for transport. At this
level the casualty is kept in IPE, from which
any large concentration of agent is removed.
The casualty is placed on a litter covered
In civilian industry, workers are usually trained in
self-decontamination methods pertinent to the haz-
ards for that setting. In a civilian or homeland defense
scenario, however, immediate decontamination by
the victims themselves may not be possible because
they may not have access to decontaminants or know
what to do. Immediate decontamination in a civilian
Decontamination of Chemical Casualties
setting is often referred to as emergency decontamina-
tion, self decontamination, or buddy rescue. The first
decontamination in the civilian setting may not occur
until a fire department decontamination unit arrives.
Patient operational decontamination might not readily
apply in the civilian setting because private ambulance
services may refuse to accept contaminated patients
and civilian patients do not have IPE.
Individuals who escape the scene of the release
before the arrival of the first responders may manage
to access transportation while still in contaminated
clothing. This was the case during the Tokyo subway
sarin attack, in which many victims either walked
or took taxis to hospitals. 4 Otherwise, contaminated
individuals must be moved to a decontamination
station established by the fire department or set up at
a hospital for patient thorough decontamination. De-
contamination stations near the incident site are often
referred to as mass casualty decontamination stations
or gross decontamination areas. 2,5 Victims might also
be moved to a water source, such as a hose or shower,
for buddy decontamination. Because fleeing casualties
might bypass decontamination, or responding fire
departments may fail to perform adequate decon-
tamination, it is important that every hospital has the
capability of establishing its own patient thorough
decontamination area outside its entrance.
Since the events of September 11, 2001, military and
civilian agencies have sought to improve their patient
decontamination capabilities. 6 Industry has responded
with a wide array of decontamination equipment and
materials for simplifying this process. Civilian and
military sectors are now much better prepared for the
challenges of patient decontamination.
Crone described the function of the skin as a barrier
and the possible effect of chemical agents on tissues: 7,8
cells making up the stratum corneum. 8 When trac-
ing agent progress from the surface of the skin to the
bloodstream, three skin “compartments” must be
considered: (1) the outer application layer, where the
agent lies on the skin; (2) the boundary layer, where
the agent is moving through the skin; and (3) the area
where a dermal reservoir of agent that has diffused
into the lipid area of the stratum corneum may form. 9
Rapid decontamination seeks to prevent large doses
of agent from penetrating to the lipid area of the stra-
tum corneum and subsequently into the circulation.
Later decontamination seeks to remove any agent that
remains on the surface of the skin.
A liquid chemical warfare agent (CWA) is often
thought to be accessible on the surface of the skin for up
to 3 minutes, taking approximately 30 minutes for the
agent to cross the skin barrier and enter the capillaries.
Some of the hazardous agent is likely to be temporarily
sequestered in the skin during this transit. According
to Buckley et al, 10 inappropriate skin treatments could
theoretically aid in the dermal transit of agent, and the
resulting store of hazardous agent could potentially
make the situation worse for the victim. 10
Most CWAs (particularly VX and mustard) are
moderately fat-soluble, enabling them to be absorbed
through the stratum corneum over time. Lipid-soluble
chemical agents move quickly throughthe lipids sur-
rounding the cells in the stratum corneum and then
more slowly into the hydrophilic (water-soluble)
Contact time, concentration, solubility, temperature,
hydration state, and physical condition of the skin are
all factors that affect the absorption of agent through
the skin’s epithelial layer. Vascularity of tissue plays an
The skin consists of a number of layers of living cells
of varied function bounded on the outside by a thin
layer of dead cells, the stratum corneum. This layer
is the main diffusion barrier to the entry of foreign
substances. The blood supply to the skin does not
reach directly to the epidermis. Therefore, a liquid
contacting the skin surface first has to penetrate the
stratum corneum, and then diffuse through the largely
aqueous medium of the cell layers to the nearest blood
capillaries, from whence it is carried round the body.
There is opportunity for a chemical to be bound to
the outer skin layers, so that further delay and stor-
age can occur. 7
Chemicals that act directly on the skin, such as
sulfur mustard, need little penetration for their ef-
fects to begin; they act directly on the integrity of the
skin cells. This same process occurs with other highly
reactive chemicals such as acids and alkalis. More
systemically acting chemicals, such as nerve agents,
may need to cross the skin barrier before they can affect
body systems. Generalizations about the permeability
of skin are often inadequate. 8 The skin is not a simple
system, and its permeability depends on many fac-
tors including temperature and the skin’s thickness,
integrity, and hydration.
The stratum corneum retains moisture and provides
a barrier to outside hazards. This barrier is very effec-
tive against water-soluble chemicals. However, it is
more permeable to fat-soluble (lipophilic) chemicals
because of the layers of lipids in the epidermis that
underlie and surround the keratinized dead skin
Medical Aspects of Chemical Warfare
important part in the rate at which agents access the
bloodstream and act systemically on the body. Studies
by Lundy et al 11 administering VX dermally to juvenile
male Yorkshire-Landrace cross pigs and earlier experi-
ments on dermal VX exposure on human subjects by
Sim 12 showed that skin that was highly vascularized
led to more rapid systemic agent effects as indicated by
reduced levels of acetylcholinesterase. Sim’s study also
noted that VX spread thinly over areas of the skin had
much less of an effect on acetylcholinesterase, a reduced
systemic effect, than the agent concentrated in one area,
which increased the penetration rate (see Exhibit 16-1).
plying a topical protectant to vulnerable skin surfaces
before entry into a chemical combat arena was pro-
posed as a protective measure against percutaneous
CWA toxicity soon after Germany used HD at Ypres,
Belgium, in 1917. 13 The US Army began examining
various soaps and ointments for protective capabilities
in the summer of that year. Although several simple
formulations were found to be effective in reducing
“skin redness” produced by agents such as hydrogen
sulfide, no product was available before the end of
the war. 13 Research continued but did not produce
a fielded product before World War II began. Dur-
ing World War II, a concentrated effort to develop
ointments for protection against HD took place at
the Chemical Warfare Service, Edgewood Arsenal,
Maryland. The Army produced the M-5 protective
ointment, which was manufactured in 1943 and 1944.
However, because of limited effectiveness, odor, and
other cosmetic characteristics, the M-5 ointment was
no longer issued to soldiers by the mid 1950s. 14
Improving the skin as a barrier to chemical agents
has been a concern since at least World War I, when
sulfur mustard (HD) was first used in warfare. Ap-
Lundy et al 1 conducted a study in which 31 Yorkshire-
Landrace cross pigs were exposed to pure liquid VX,
and VX in isopropyl alcohol. Both of these exposures
were at the calculated median lethal dose. In some
animals the nerve agent was placed on the ventral
surface of the ear (thin tissue with generous blood
flow), and on others the agent was placed on the
belly just above the naval (thicker tissue with a less
pervasive blood flow). Liquid agent absorption was
measured by blood cholinesterase inhibition. Those
swine with VX applied to the ear showed more
than 90% cholinesterase inhibition within 45 min-
utes, resulting in apnea (within 2 hours) requiring
ventilatory assistance thereafter and death within
45 minutes after ventilatory support was initiated.
Those animals with belly VX exposure showed only
75% cholinesterase inhibition within the 6-hour
timeframe of the experiment, but developed the
same progression of symptoms requiring venti-
latory support. In neither case were the animals
provided with antidotes within the time period
that would have slowed or ameliorated the effects.
This study demonstrates, in part, that death from
liquid VX can be delayed by up to several hours
depending on a variety of factors, one being the
specific body area exposed. Earlier human studies
by Sim 2 also show the variable and delayed effects
of exposure to liquid VX.
Skin Exposure Reduction Paste Against Chemical
Warfare Agents
Between 1950 and the early 1980s, research focus
shifted to medical countermeasures rather than pro-
tective creams. Then, a limited research effort at the
successor to the Chemical Warfare Service, the US
Army Medical Research Institute of Chemical Defense
(USAMRICD), produced two non-active barrier skin
cream formulations based on a blend of perfluorinated
polymers. The two formulations were transferred to
advanced development in October 1990. 15 The best
formulation was selected and progressed through
development as an investigational new drug filed
with the US Food and Drug Administration in 1994
and approval of a new drug application in 2000. This
new product was called skin exposure reduction
paste against chemical warfare agents (SERPACWA).
SERPACWA consisted of fine particles of polytetra-
fluoroethylene solid (Teflon; DuPont, Wilmington, Del)
dispersed in a fluorinated polyether oil. The excellent
barrier properties of this polymer blend were related to
the low solubility of most materials in it. Only highly
fluorinated solvents like Freon (DuPont, Wilmington,
Data sources: (1) Lundy PM, Hamilton MG, Hill I, Conley J,
Sawyer TW, Caneva DC. Clinical aspects of percutaneous poi-
soning by the chemical warfare agent VX: effects of applica-
tion site and decontamination. Mil Med. 2004;169:856-862. (2)
Sim VM. VX Percutaneous Studies in Man . Aberdeen Proving
Ground, Md: US Army Chemical Research and Development
Laboratories; 1960. Technical Report 301.
Decontamination of Chemical Casualties
Del) were observed to show appreciable solubility.
SERPACWA is now a standard issue item to US forces
facing a threat of CWA use.
brushing and scrubbing, but it may physically wear
off with time. Abrasion of SERPACWA by clothing or
other contacts, such as sand or dirt, will reduce the
wear time. SERPACWA must be reapplied if the coat-
ing becomes embedded with particulate matter (dirt
or sand), if the sites are decontaminated, or after 8
hours on the skin. Normally, SERPACWA is effective
for 4 hours in preventing CWAs from contacting and
penetrating the skin. Insect repellents such as DEET
(N,N-diethyl-meta-toluamide) decrease its effective-
ness. If DEET is wiped off before application using a
dry towel, gauze, or piece of cloth, SERPACWA can
still provide significant protection.
SERPACWA is an antipenetrant barrier cream for
use by service members to protect against the toxic ef-
fects of CWAs (eg, blister [vesicant] and nerve agents)
and percutaneously active biological agents. When
used in conjunction with IPE, or mission-oriented
protective posture (MOPP) gear, SERPACWA will
prevent or significantly reduce the toxicity following
percutaneous exposure to such agents. It is used as an
adjunct to IPE, not as a substitute. The effective barrier
of SERPACWA also has been found to protect against
poison ivy and poison oak.
Effects on Decontamination
The use of SERAPCWA makes decontamination
easier in areas protected by the barrier. It is easier to
physically remove CWA from a SERPACWA layer than
from the skin. Service members should still perform
skin decontamination immediately after chemical
contamination, because SERPACWA’s effectiveness
decreases with time. SERPACWA can be removed
by brushing and scrubbing the skin areas with soap
and water. SERPACWA has no vapors, so it does not
register a false alarm with automatic vapor detectors
such as the improved chemical agent monitor (ICAM),
nor does it register with systems that detect chemical
liquid such as M8 paper. M8 paper, however, detects
agent on the surface of the SERPACWA layer (however,
it has been noted that if moist SERPACWA paste coats
the surface of M8 paper, it can prevent CWA from
contacting the paper).
SERPACWA was developed to extend the protection
afforded by the current protective garments and allows
a longer window for decontamination. It provides for
excellent protection against liquid challenges of GD
(soman), VX, and HD, but its protection against HD
and GD vapor is less than optimal. It does not neutral-
ize CWAs into less toxic products.
SERPACWA is used at the direction of the com-
mander. Each service member is issued six packets of
SERPACWA, sufficient material for six applications or
for 2 days of use. Its effectiveness depends on the thick-
ness and integrity of the layer applied and the length
of time between application and agent exposure (wear
time). The cream should be applied first to skin areas
adjacent to IPE closures (such as at the neck, wrists, and
lower legs around the top of the boots). If the situation
permits, SERPACWA should also be applied to the
armpits, groin area, creases and crack of the buttocks,
and around the waist. It is not applied to open wounds.
It should never be applied to the entire body, because
its occlusiveness can interfere with the ability to dis-
sipate heat. Under normal conditions, SERPACWA is
effective when spread over the skin as a thin layer (0.1
mm thick, or 0.01 mL/cm 2 ). One packet of SERPACWA
contains 1.35 fluid ounces (about 2.7 weight ounces or
84 g) for one application. This amount of SERPACWA
is sufficient to cover the indicated skin areas with a
smooth coating that has a barely visible cream color
and is slightly detectable by touch.
SERPACWA is not water soluble, so it cannot be
washed off by water or removed by sweat without
Active Barrier Creams
In 1994, to overcome the limitations of SERPACWA,
USAMRICD began development of an improved sub-
stance that would act as both a protective barrier and
an active destructive matrix to detoxify CWAs. The
types of molecules that could potentially neutralize or
detoxify CWAs have been known for a long time. These
compounds fall into three general classes: oxidizers,
reducers, and nucleophiles. The USAMRICD research-
ers were required to find a final formulation that does
not irritate the skin, however, which eliminated many
of the most reactive species. The aprotic nonpolar
environment of SERPACWA provides a unique but
challenging medium for active moieties to neutral-
ize CWA. Reaction mechanisms that do not involve
charged transition states are favored in this medium.
The improved SERPACWA containing a reactive ma-
trix became known as active topical skin protectant
(aTSP). Four criteria were established for aTSP: (1) the
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