| Safety Profile |
A poison gas. A severe
eye, skin, and mucous membrane irritant. A
systemic irritant by inhalation. Mutation data
reported. Exposure may occur whenever
nitric acid acts upon organic material, such
as wood, sawdust, and refuse; it occurs
when nitric acid is heated, and when organic
nitro compounds are burned, for example,
celluloid, cellulose nitrate (guncotton), and
dynamite. The action of nitric acid upon
metals, as in metal etchng and pickling, also
liberates the fumes. In hgh-temperature
weldmg, as with the oxyacetylene or electric
torch, the nitrogen and oxygen of the air
unite to form oxides of nitrogen.
Automobile exhaust and power plant
emissions are also sources of NOx.
Exposure occurs in many manufacturing nitric and nitrous acids. This is the action
that takes place deep in the respiratory
system. The acids formed are irritating and
can cause congestion in the throat and
bronchi and edema of the lungs. The acids
are neutralized by the alkalies present in the
tissues, with the formation of nitrates and
nitrites. The latter may cause some arterial
ddation, fall in blood pressure, headache,
and dizziness, and there may be some
formation of methemoglobin. However, the
nitrite effect is of secondary importance.
Because of their relatively low solubllity in
water, the nitrogen oxides are initially only
slightly irritating to the mucous membranes
of the upper respiratory tract. Their warning
power is therefore low, and dangerous
amounts of the fumes may be breathed
before the worker notices any real
discomfort. Higher concentrations (60-150
ppm) cause immediate irritation of the nose
and throat, with coughing and burning in
the throat and chest. These symptoms often
clear upon breathing fresh air, and the
worker may feel well for several hours.
Some 6-24 hours after exposure, a sensation
of tightness and burning in the chest
develops, followed by shortness of breath,
sleeplessness, and restlessness. Dyspnea and
air hunger may increase rapidly with
development of cyanosis and loss of
consciousness followed by death. In cases
that recover from the pulmonary edema,
there is usually no permanent disabiltty, but
pneumonia may develop later.
Concentrations of 100-150 ppm are
dangerous for short exposures of 30-60
minutes. Concentrations of 200-700 ppm
may be fatal after even very short exposures.
Continued exposure to low concentrations
of the fumes, insufficient to cause
pulmonary edema, is said to result in chronic
irritation of the respiratory tract, with cough,
headache, loss of appetite, dyspepsia,
corrosion of the teeth, and gradual loss of
strength.
Exposure to NOx is always potentially
serious, and persons so exposed should be hours.
An oxidizer. The liquid is a sensitive
explosive. Explosive reaction with carbon
disulfide (when ignited), methanol (when
ignited), pentacarbonyl iron (at 50℃),
phosphine + oxygen, sodium diphenylketyl,
dichlorine oxide, fluorine, nitrogen
trichloride, ozone, perchloryl fluoride (at
100-300°C), vinyl chloride. Reacts to form
explosive products with dienes (e.g., 1,3-
butadiene, cyclopentadiene, propadiene).
Can react violently with acetic anhydride,
Al, amorphous boron, BaO, BCl3, CsHC2,
calcium, carbon + potassium hydrogen
tartrate, charcoal, Cl0, pyrophoric
chromium, 1,2-dichloroethane,
dichloroethylene, ethylene, fuels,
hydrocarbons, hydrogen + oxygen, NasO,
uns-dimethyl hydrazine, NH3, CHCl3, Fe,
Mg, Mn, CH2Cl2, olefins, phosphorus,
PNH2, PH3, potassium, potassium sulfide,
propylene, rubidum acetylide, Na, S,
tungsten carbide, trichloroethylene, 1,1,1-
trichloroethane, uns-tetrachloroethane,
uranium, uranium dicarbide. Wdl react with
water or steam to produce heat and
corrosive fumes; can react vigorously with
reducing materials.
processes when nitric acid is made or used.
Oxides of nitrogen have been implicated as
a cause of acid rain.
The oxides of nitrogen are somewhat
soluble in water, reacting with it to form
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