Biomedical Engineering Reference
In-Depth Information
expedient. If available, military M291 Resin is
an effective alternative. This material consists
of activated charcoal, polystyrene polymer, and
ion-exchange resins. This is a single-step, non-
toxic, non-irritating decontamination—safe for the
skin—including the face and around wounds.
“Each packet contains a nonwoven, fiberfill lami-
nated pad impregnated with the decontamination
compounds.” [1]. Standard soap or detergent and
warm water will easily remove the majority of
non-persistent contaminants. Both seawater and
fresh water are equally suitable. Eyes and hair
can be cleaned with non-tearing baby shampoo.
Radiological contamination is also effectively
reduced through simple washing. Surface contam-
ination with biologicals is equally well-managed.
Most biologicals are not surface active, espe-
cially if rapidly removed. Deep wound cavities
should be lavaged only; thorough debridement
should be delayed until proper surgical conditions
can be instituted.
In general, timely, copious flushing with water
produces better results than high concentrations of
hypochlorite solutions. However, gross contami-
nation with persistent military agents of a sticky
or oily nature (VX, thickened Soman, mustard)
is a more difficult situation. These substances are
designed to be retained on the skin, potentiating
their toxic action. They may require chemical
inactivation to be effectively removed. Chemical
detoxification is not an instantaneous process—
the larger the quantity of contaminant, the longer
the time necessary for the chemical reaction to
occur. Dilute (0.5%) sodium or calcium hypochlo-
rite solution (bleach) is considered the “universal
decontaminant” by most authorities. It can be
made by adding 6 ounces of calcium hypochlo-
rite to 5 gallons of water [1]. Hypochlorite acts
by alkaline hydrolysis, breaking chemical bonds
and converting the offending substance into a less
toxic byproduct. It is equally effective against
organophosphates and vesicants. The reaction rate
is dependent on the chemical structure, pH, temper-
ature, solvent (usually water), and presence of
catalytic reagents. The reaction half-time for VX at
pH 10 is 1.5 minutes. The reaction rate for “other
agents, such as mustard, are much longer” [1].
Agent
0.5% Bleach
2.5% Bleach
5% Bleach
GB
85%
99%
99%
GF
69%
70%
91%
HD
67%
78%
79%
Percent Agent Detoxified in 15 Minutes.
Figure 7.2
Hypochlorite reaction rates for chemical agents.
(USAMRICD, 1998)
Hypochlorite is also is an extremely effective
biocide, killing the vast majority of organisms
quickly (see Figure 7.2).
Reactive Skin Decontamination Lotion (RSDL)
[2] was FDA approved in 2003. It is easy to
apply lotion (containing DeKon139) which will
decontaminate a broad range of agents. RSDL
has “ no significant effect on the normal
response of epidermal tissue with respect to the
processes leading to repair of skin defects and the
process of re-epithelialization” [3]. Thus, RDSL is
presumably safe to use in the presence of open
wounds.
Alternative chemical detoxificants, effective on
equipment but
not for use on skin
, include
strongly basic solutions of sodium and potassium
hydroxide and DS-2 (diethylenetriamine, ethylene
glycol monomethyl ether, and sodium hydroxide
mixture). There are also recently marketed decon-
taminating agents developed at Sandia National
Laboratories [4] such as EasyDECON™ [5],
MDF-200
™
[6], and ALL-CLEAR
™
[7]. These
foams consist of a complex mixture of quar-
ternary ammonium salts with surfactant prop-
erties, a water soluble polymer, a corrosion
inhibitor, a fatty alcohol, and a reactive peroxide
compound at an alkaline pH. They are capable
of rapidly hydrolyzing chemical agents and
reducing spores by up to 7 logs in 15 minutes (see
Figure 7.3).
This formulation is both non-toxic to animals,
including humans, generally non-corrosive and can be
used for neutralization of many toxants, both chemical
and biological. The formulation allows decontamina-
tion of areas populated with both people and sensi-
tive equipment; [it] works on all currently anticipated
material surfaces and can be incorporated into a wide
