This month our example is Mustard
also called H, HD (distilled mustard, very pure), or
Sulfur Mustard. The chemical name is
Bis-(2-chloroethyl)sulfide. This is one of the blister
agents; it is yellow to brown oily liquids with a slight
garlic or mustard odor. Although volatility is low,
vapors can reach hazardous levels during warm weather.
Sulfur mustards are absorbed by the skin, causing
erythema and blisters. Ocular exposure to these agents
may cause incapacitating damage to the cornea and
conjunctiva. Inhalation damages the respiratory tract
epithelium and may cause death. Its chemical formula is
corresponds to a molecular weight of 159. Mustard has a
vapor density greater than air (5.5), so any vapors are
going to seek low spots. Mustard has a United Nations #
of 2810 and a Chemical Abstract Service # of 505-60-2.
At standard conditions of sea level
and 68°F, the chemical has a vapor pressure of 0.072 mm
of Mercury, which is equivalent to 0.000095 atmospheres.
With a melting point of 58°F and a boiling point of
419°F, it is typically found as a liquid. As with all
the chemical warfare agents, the material is extremely
toxic. Currently NIOSH has not established an IDLH value
but the DOD has established a 30-minute AEGL 2 (acute
exposure guideline level 2 defined as irreversible or
other serious, long-lasting effects or impaired ability
to escape) of 0.03 mg/m3, which is roughly
equivalent to 0.005 ppm. When compared to hazardous
substances such as chlorine (IDLH=10 ppm) or Phosgene
(IDLH=2 ppm), we can see that Mustard is indeed a very
dangerous material and must be handled with a great deal
of respect. AristaTek has elected to display the IDLH as
0.003 mg/m3, which is the same as the TWA in
the PEAC-WMD application.
instances where the LOC is reported as
mg/m3, to convert to ppm, the following
equation holds at low concentrations.
ppm = (LOCconcentration in mg/m3 * 24.45)/(molecular
Mustard (H) is not your everyday
typical industrial chemical; it actually has only one
purpose, to be used as a chemical warfare agent. The USA
has signed the “Convention on the Prohibition of the
Development, Production, Stockpiling and Use of Chemical
Weapons and on their Destruction” (Chemical Weapons
Convention or CWC). The treaty lists three different
schedules of chemicals, with the "recognized" chemical
warfare agents, e.g., Sarin, VX, Soman, Mustard, making
up the Schedule 1 list. It is illegal to
possess Mustard and/or manufacture the chemical. It
would therefore be expected that Mustard would be
encountered in one of two instances: (1) as a munitions
device stolen from the United States Military (highly
improbable since these materials and their associated
devices are under strict security whether in storage or
transport for destruction), or (2) in the possession of
a terrorist group that has smuggled the chemical into
the country or manufactured the material in a
People whose skin or clothing is
contaminated with sulfur mustard can contaminate
rescuers by direct contact or through off-gassing vapor.
Sulfur mustards are vesicants and alkylating agents.
They are colorless when pure but are typically a yellow
to brown oily substance with a slight garlic or mustard
odor. H contains about 20 to 30% impurities (mostly
sulfur); distilled mustard is known as HD and is nearly
pure; HT is a mixture of 60% HD and 40% agent T (a
closely related vesicant with a lower freezing point).
Sulfur mustards evaporate slowly. They are very
sparingly soluble in water but are soluble in oils,
fats, and organic solvents. They are stable at ambient
temperatures but decompose at temperatures greater than
Sulfur mustards were first developed in the
early-to-mid-1800s and were introduced as chemical
warfare agents in 1917 during World War I. They have
been used extensively in chemical warfare and remain a
major threat. More than a dozen countries have sulfur
mustard in their chemical arsenals. Destruction of U.S.
stockpiles of chemical agents, including sulfur
mustards, was mandated by the CWC to take place before
Synonyms for Mustard, H and HD are
Bis(2-chloroethyl) sulfide; bis(beta-chloroethyl)
sulfide; di-2-chloroethyl sulfide;
2,2'-dichloroethyl sulfide; sulfur mustard; Iprit;
Kampstoff “Lost”; mustard gas; senfgas, S-yperite;
yellow cross liquid; and yperite.
Routes of Exposure:
Sulfur mustards are readily absorbed from the
respiratory tract; injury develops slowly and
intensifies over several days. The pure liquid is
colorless and odorless. Agent grade material is yellow
to dark brown or black and the odor is variously
described as similar to burning garlic, horseradish, a
characteristic sweetish odor, or a weak, sweet,
agreeable odor. The odor of sulfur mustards does
not provide adequate warning for detection. The
LCt50 (the product of concentration times
time that is lethal to 50% of the exposed population by
inhalation) is approximately 1,500 mg-min/m3.
The vapors are heavier than air. When inhaled, these
agents may cause systemic effects. The estimated Ct for
airway injury is 100 to 200 mg-min/m3.
Contact Mustard vapor and liquid are absorbed
through the eyes, skin, and mucous membranes. Clinical
effects do not occur until hours after exposure. The
median incapacitating dose for the vapor is 200
mg-min/m3. A Ct of 12 to 70
mg-min/m3 produces eye lesions. Direct
contact with the liquid can cause skin and eye burns
that develop an hour or more after exposure. A 10 µg
droplet is capable of producing blisters. Skin, eye, and
airway exposure to vapor sulfur mustard and skin and eye
exposure to liquid mustard may cause systemic toxicity.
The lethal dose is about 100 mg/kg or 1 to 1.5 teaspoons
Ingestion Ingestion may cause
local effects and systemic absorption.
when pure but usually a pale yellow, dark brown or black
oily liquid. The vapor is colorless.
properties: Faint garlic or mustard odor (odor
threshold 0.6 mg/m3)
Weight: 159.08 daltons
Point: (760 mm Hg) 419°F
Gravity: 1.27 g/ml
Pressure: 0.072 mm Hg or 0.000095 atmospheres
Density: 5.4 50 5.5 (air = 1.0)
Point: 221 °F
mustards are rapidly corrosive to brass and steel at 149
°F (65 °C); they are destroyed by strong oxidizing
agents. These agents hydrolyze to form hydrochloric acid
(HCl) and thiodiglycol.
Sulfur mustards are vesicants causing
skin, eye, and respiratory tract injury. Although these
agents cause cellular changes within minutes of contact,
the onset of pain and other clinical effects are delayed
for 1 to 24 hours.
Sulfur mustards are alkylating agents
that may cause bone marrow suppression and neurologic
and gastrointestinal toxicity.
Acute Exposure: Sulfur
mustards are vesicants and alkylating agents; however,
the biochemical mechanisms of action are not clearly
understood. They are highly reactive and combine rapidly
with proteins, DNA, or other molecules. Therefore,
within minutes following exposure intact mustard or its
reactive metabolites are not found in tissue or
biological fluids. Sulfur mustards also have cholinergic
activity, stimulating both muscarinic and nicotinic
receptors. The onset of clinical symptoms and their time
of onset depend on the severity of exposure (Table 1).
The death rate from exposure to sulfur mustard is low (2
to 3% during World War I). Death usually occurs between
the 5th and 10th day due to
pulmonary insufficiency complicated by infection due to
immune system compromise.
The eye is the most sensitive tissue to sulfur
mustard effects. Sulfur mustard vapor or liquid may
cause intense conjunctival and scleral pain, swelling,
lacrimation, blepharospasm, and photophobia; however,
these effects do not appear for an hour or more. Miosis
due to cholinergic effects may occur. High
concentrations of vapor or liquid can cause corneal
edema, perforation, blindness, and later scarring.
Direct skin exposure to sulfur mustards causes
erythema and blistering. Generally, a pruritic rash will
develop within 4 to 8 hours followed by blistering 2 to
18 hours later. Contact with the vapor may result in
first and second degree burns, while contact with the
liquid typically produces second and third degree
chemical burns. An area of burn covering 25% or more of
the body surface area may be fatal.
Dose-dependent inflammatory reactions in the upper
and lower airway begin to develop several hours after
exposure and progress over several days. Burning nasal
pain, epistaxis, sinus pain, laryngitis, loss of taste
and smell, cough, wheezing, and dyspnea may occur.
Necrosis of respiratory epithelium can cause
pseudomembrane formation and local airway obstruction.
Ingestion may cause chemical burns of the GI tract
and cholinergic stimulation. Nausea and vomiting may
occur following ingestion or inhalation. Early nausea
and vomiting is usually transient and not severe.
Nausea, vomiting, and diarrhea occurring several days
after exposure indicates damage to the GI tract and thus
is a poor prognostic sign.
High doses of sulfur mustards can cause
hyperexcitability, convulsions, and insomnia.
Systemic absorption of sulfur mustard may induce
bone marrow suppression and an increased risk for fatal
complicating infections, hemorrhage, and anemia.
Effects Years after apparent healing of severe eye
lesions, relapsing keratitis or keratopathy may develop.
Sequelae Persistent eye conditions, loss of taste
and smell, and chronic respiratory illness including
asthmatic bronchitis, recurrent respiratory infections,
and lung fibrosis may persist following exposure to
Table 1. Clinical Effects and Time of
Onset by Severity of Exposure to Sulfur Mustard
Time to first
Tearing, itching, burning,
Above effects and
reddening, lid edema, moderate
Marked lid edema, possible
corneal damage, severe pain
epistaxis, hoarseness, hacking cough
Above effects and
productive cough, mild to severe dyspnea
Exposure: Prolonged or repeated acute exposure to
sulfur mustards may cause cutaneous sensitization and
chronic respiratory disease. Repeated exposures result
in cumulative effects because mustards are not naturally
detoxified by the body.
The International Agency for Research on Cancer
(IARC) has classified sulfur mustard as carcinogenic to
humans (Group 1). Epidemiological evidence indicates
that repeated exposures to sulfur mustard may lead to
cancers of the upper airways.
Reproductive and Developmental
Effects There is limited evidence that repeated
exposures to sulfur mustards may cause defective
spermatogenesis years after exposure. Sulfur mustard has
been implicated as a potential developmental toxicant
because of its similarity to nitrogen mustard; however,
data are inconclusive.
Remove clothes and place contaminated clothes and
personal belongings in a sealed double bag.
Decontamination of mustard-exposed victims by either
vapor or liquid should be performed within the first two
minutes following the exposure to prevent tissue damage.
If not accomplished within the first several minutes,
decontamination should still be performed to ensure any
residual liquid mustard is removed from the skin or
clothes or to ensure any trapped mustard vapor is
removed with the clothing. Removing trapped mustard
vapor will prevent vapor off-gassing or subsequent
cross-contamination of other emergency responders/health
care providers or the healthcare facility. Physical
removal of the mustard agent, rather than detoxification
or neutralization, is the most important principle in
patient decontamination. Mustard is not detoxified by
water alone and will remain in decontamination effluent
(in dilute concentrations) if hydrolysis has not taken
exposed to vapor should be decontaminated by removing
all clothing in a clean air environment and shampooing
or rinsing the hair to prevent vapor off‑gassing.
Patients exposed to liquid should be decontaminated by –
a. Washing in
warm or hot water at least three times. Use liquid soap
(dispose of container after use and replace), large
volumes of water, and mild to moderate friction with a
single-use sponge or washcloth in the first and second
washes. Scrubbing of exposed skin with a brush is
discouraged, because skin damage may occur which may
enhance absorption. The third wash should be to rinse
with large amounts of warm or hot water. Shampoo can be
used to wash the hair. The rapid physical removal of a
chemical agent is essential. If warm or hot water is not
available, but cold water is, use cold water. Do not
delay decontamination to obtain warm water.
b. Rinsing the
eyes, mucous membranes, or open wounds with sterile
saline or water.
healthcare provider should –
a. Check the
casualty after the three washes to verify adequate
decontamination before allowing entry to the medical
treatment facility. If the washes were inadequate,
repeat the entire process.
prepared to stabilize conventional injuries during the
decontamination process. Careful decontamination can be
a time consuming process. The health care provider may
have to enter the contaminated area to treat the
casualty during this process. Medical personnel should
wear the proper PPE and evaluate the exposed workers.
In using the PEAC application we
access information for the chemical by first locating
Mustard or H or HD in the database. The following
figures show the screens displayed for chemical
properties, Figure 1 for the PEAC-WMD for Windows
application and Figure 2-4 for the PEAC-WMD for
the Pocket PC application.
Figure 1 - Using the Lookup By:
Name for Mustard using the PEAC-WMD for Windows
Review of the information displayed
in the chemical properties screen whether in Figure 1
(above) or Figures 2-4 (below), show chemical properties
values discussed earlier at the top of this discussion.
In addition, other values are provided such as the TEELs
(Temporary Emergency Exposure Limit) published by
Department of Energy.
Figure 2 – Selecting Mustard using
the PEAC-WMD for Pocket PC application
Figure 3 – The top portion of the
Chemical Properties Data Display Screen
Figure 4 – The bottom portion of
the Chemical Properties Data Display Screen
Additional information is available
regarding how to prevent skin contact by checking the
CPC listing, i.e., Chemical Protective Clothing.
An advantage of using the PEAC tool
is assistance in the development of an evacuation zone
for those chemicals that produce a toxic vapor cloud.
Mustard has a very low vapor pressure (0.072 mm Hg), so
if a small amount is spilled and forms a puddle, the
amount of vapor released is very minimal. Why then is
there so much concern with the chemical warfare agents,
e.g., Mustard, Tabun, Soman, VX, Lewisite, and Mustard
Gas, all of which have very low vapor pressures at
standard conditions? The answer has two parts. First, as
already discussed above for Mustard, these hazardous
substances are very toxic, on the order of 100 or 1,000
times more toxic than the most toxic industrial
chemicals. Secondly, if they are released under
conditions where more than just a pool or puddle is
created, the effect of their low vapor pressure can be
overcome. When released as a weapon, e.g., using an
explosive charge or atomizer to create an aerosol or
tiny droplets, the effective liquid surface area of the
resulting released agent is increased several orders of
magnitude. This increase in effective surface area
increases not only the resulting vapor content in the
air to be inhaled by victims; it also increases the
opportunity for skin contact and the resulting exposure
As with all of our examples,
AristaTek creates a scenario for a spill or release of
the specific chemical and then we work through the
development of a PAD (Protective Action Distance) to
demonstrate how the PEAC system works. For our scenario
using Mustard as the spilled chemical we’ll use Coors
Baseball Field in Denver as the location and the time as
2:30 PM on June 18th. A small container
(estimated at 2-3 quarts in size) with Mustard is
released using an explosive charge. The temperature is
about 80°F, the winds are 2 mph, and it’s a clear day
As seen at the top of the data
display screens, there is a yellow icon displayed, this
is the PEAC icon for notifying the user that a
Protective Action Distance can be calculated. Clicking
or tapping on the PAD icon will display a screen as
shown in Figure 5. Following through the screens, we
provide information on the Meteorology, Container Size,
and Type of Release (Source). The last screen displays
the PAD based on the provided information.
It’s Denver in June and the
temperature about 80°, light wind is set for 2
mph, clear sky so we’ll set cloud cover to 0%, and
the terrain is Urban/Forest since it’s an urban
We have selected from our list
of container sizes the Small Package
selection. This provides us with a default
size that should get us pretty close to the actual
Since the scenario has Mustard
released with an explosive charge, we’ve selected
a BLEVE or Pressure Explosion as the
Source type of release.
Figure 5 – Calculating a PAD using the
After specifying the release or
source is a BLEVE or Pressure Explosion, the user taps
the right arrow at the top of the screen and the PAD
computation results are displayed, see Figure 6.
Figure 6 - The PEAC computation for PAD using
Since the IDLH and TWA are both
listed as 0.003 mg/m3, the user may also want
to calculate a PAD based on a different concentration,
e.g., the DOD AEGL 2 discussed earlier which was 0.03
mg/m3 or ~0.005 ppm. Entering the desired
value in the Level of Concern entry field does this. The
PEAC-WMD application will recalculate a PAD distance and
display the value, as shown in Figure 7.
Figure 7 – PAD recalculated using the DOD
AEGL 2 value of ~0.005 ppm
Portions of this discussion on
Mustard were adapted from the ATSDR Medical Management
Guideline document for blister agents, which can be
downloaded from the ADSTR web site at: http://www.atsdr.cdc.gov/mmg.html.
Additional information was adapted from the CDC web