Chem-ch16_pg527-558.pdf

Decontamination of Chemical Casualties

Chapter 16

DECONTAMINATION OF CHEMICAL

CASUALTIES

ERNEST H. BRAUE, JR, P h D*; CHARLES H. BOARDMAN, MS, ORR/L † ; a n D CHARLES G. HURST, MD ‡

INTRODUCTION

MILITARY AND CIVILIAN DECONTAMINATION PROCEDURES

ACTION OF CHEMICAL AgENTS ON THE SkIN

BARRIER SkIN CREAMS

METHODS OF DECONTAMINATION

WOUND DECONTAMINATION

PATIENT THOROUgH DECONTAMINATION

EQUIPMENT FOR PATIENT THOROUgH DECONTAMINATION

ESTABLISHINg A PATIENT THOROUgH DECONTAMINATION AREA

DECONTAMINATION IN COLD WEATHER

SPECIAL POPULATIONS

SUMMARY

* 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

527

Medical Aspects of Chemical Warfare

INTRODUCTION

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.

MILITARY AND CIVILIAN DECONTAMINATION PROCEDURES

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

them.

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

worn.

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

528

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.

ACTION OF CHEMICAL AgENTS ON THE SkIN

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)

bloodstream.

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

529

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).

BARRIER SkIN CREAMS

History

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-

EXHIBIT 16-1

VX STUDIES

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.

530

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.

Function

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

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).

Effectiveness

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.

Application

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

531

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