Methylnitrit

· CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper not available or no answer, refer to appropriate telephone number listed on the inside back cover.

· ELIMINATE all ignition sources (no smoking, flares, sparks or flames) from immediate area.

Excerpt from ERG Guide 116 [Gases - Flammable (Unstable)]:

General First Aid:

· Wear positive pressure self-contained breathing apparatus (SCBA).

Biological Exposure Indices (BEI) [ACGIH] - Methemoglobin in blood = 1.5% of hemoglobin during or at end of shift. [ACGIH]

SRP: The most favorable course of action is to use an alternative chemical product with less inherent propensity for occupational exposure or environmental contamination. Recycle any unused portion of the material for its approved use or return it to the manufacturer or supplier. Ultimate disposal of the chemical must consider: the material's impact on air quality; potential migration in soil or water; effects on animal, aquatic, and plant life; and conformance with environmental and public health regulations.

Excerpt from ERG Guide 116 [Gases - Flammable (Unstable)]:

Immediate precautionary measure

TERRESTRIAL FATE: Based on a classification scheme(1), an estimated Koc value of 44(SRC), determined from a structure estimation method(2), indicates that methyl nitrite is expected to have very high mobility in soil(SRC). Volatilization of methyl nitrite from moist soil surfaces is expected to be an important fate process(SRC) given an estimated Henry's Law constant of 6.6X10-5 atm-cu m/mole(SRC), using a fragment constant estimation method(3). The potential for volatilization of methyl nitrite from dry soil surfaces may exist (SRC) based upon an estimated vapor pressure of 1,650 mm Hg(SRC), determined from a fragment constant method(4).

AQUATIC FATE: Based on a classification scheme(1), an estimated Koc value of 44(SRC), determined from a structure estimation method(2), indicates that methyl nitrite is not expected to adsorb to suspended solids and sediment(SRC). Volatilization from water surfaces may occur(3) based upon an estimated Henry's Law constant of 6.6X10-5 atm-cu m/mole(SRC), developed using a fragment constant estimation method(4). Using this Henry's Law constant and an estimation method(3), volatilization half-lives for a model river and model lake are 8 hours and 150 hours, respectively(SRC). According to a classification scheme(5), an estimated BCF of 3(SRC), from an estimated log Kow of 0.88(6) and a regression-derived equation(7), suggests the potential for bioconcentration in aquatic organisms is low(SRC).

ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), methyl nitrite, which has an estimated vapor pressure of 1,600 mm Hg at 25 °C(SRC), determined from a fragment constant method(2), is expected to exist solely as a gas in the ambient atmosphere. Methyl nitrite absorbs light in the environmental spectrum(4), therefore the potential for direct photolysis exists.

Using a structure estimation method based on molecular connectivity indices(1), the Koc for methyl nitrite can be estimated to be 44(SRC). According to a classification scheme(2), this estimated Koc value suggests that methyl nitrite is expected to have very high mobility in soil.

/CASE REPORTS/ Two workers from the same factory presented to the same emergency department within six weeks of one another with moderate (Case 1) and severe (Case 2) methemoglobinemia. Subsequent investigation revealed that the factory produces phenylpropanolamine and that both patients, shortly before becoming ill, were inadvertently exposed to methyl nitrite, a critical reagent in this production. Although other nitrites induce methemoglobinemia, exposure to methyl nitrite during phenylpropanolamine production appears to be a new cause of occupational methemoglobinemia.

/CASE REPORTS/ ...A case of fatal /methhemoglobinemia/ (MetHb) due to occupational exposure to methyl nitrite as a result of phenylpropanolamine (PPA) production .../is reported/. Through case report and factory investigation, the causality was demonstrated. Three previous healthy pharmaceutical production workers... developed general weakness, chest tightness, dizziness, and cyanosis while working at the PPA production line. On the arrival of Emergency Department, the MetHb levels were 35.8%, 46.3%, and 68.0% respectively. The last worker died two hours later due to lack of antidote (methylene blue) during the transportation to /the/ hospital. Factory investigation revealed that these three workers were responsible for the production of PPA in the last two years. During the regular procedure, methyl nitrite was developed as an active intermediate reagent in the closed tank to produce PPA. In the morning of this accident, one of the three victims failed to /make sure the tank was empty/. The left-over sulfuric acid reacted with sodium nitrite and the disaster occurred by methyl nitrite which was leaked from the /open/ manhole. ...

/CASE REPORTS/ Methyl nitrite was found to be a potent cyanosing agent for workers synthesizing a rubber antioxidant. Six cases of methyl nitrite intoxication are described, consisting initially of dizziness and later headache and palpitation, the last more pronounced in two workers who consumed alcohol after exposure at work. All men responded satisfactorily to bed rest for 12 hr and inhaling of oxygen for about 2 hr. Atmospheric concentrations in the plants where the men had been affected, simulating the conditions at the time of intoxications, indicated that "50 ppm is the uppermost limit of safety". Another incident, when it was estimated that workers were exposed to 50-100 ppm, caused cyanosis, dizziness, and nausea but complete recovery after exposure ceased.

Methyl nitrite's production and use as a raw material for the synthesis of nitrite and nitrosos esters(1) may result in its release to the environment through various waste streams(SRC). Its former use as a rocket propellant(2) resulted in its direct relesase to the environment.

An estimated BCF of 3 was calculated for methyl nitrite(SRC), using an estimated log Kow of 0.88(1) and a regression-derived equation(2). According to a classification scheme(3), this BCF suggests the potential for bioconcentration in aquatic organisms is low(SRC).

The Henry's Law constant for methyl nitrite is estimated as 6.6X10-5 atm-cu m/mole(SRC) using a fragment constant estimation method(1). This Henry's Law constant indicates that methyl nitrite is expected to volatilize from water surfaces(2). Based on this Henry's Law constant, the volatilization half-life from a model river (1 m deep, flowing 1 m/sec, wind velocity of 3 m/sec)(2) is estimated as 7.8 hours(SRC). The volatilization half-life from a model lake (1 m deep, flowing 0.05 m/sec, wind velocity of 0.5 m/sec)(2) is estimated as 6.2 days(SRC). Methyl nitrite's Henry's Law constant indicates that volatilization from moist soil surfaces may occur(SRC). The potential for volatilization of methyl nitrite from dry soil surfaces may exist(SRC) based upon an estimated vapor pressure of 1,600 mm Hg(SRC), determined from a fragment constant method(3).

/LABORATORY ANIMALS: Acute Exposure/ Methyl nitrite is a relatively toxic compound by inhalation for both animals and humans. Rats survived thirteen 6 hr exposures at 100 ppm with methemoglobin levels of 30-40%. However, 35 ppm produced 6% methemoglobin in a cat after a 6 hr exposure.

/GENOTOXICITY/ Methy... nitrite /is/ mutagenic in the Ames test.

/GENOTOXICITY/ Methyl nitrite was tested for mutagenicity in Salmonella typhimurium TA1535. In the first set of experiments, plated bacteria were exposed to methyl nitrite in desiccators both in the absence and presence of a metabolizing system (S9 from Aroclor-pretreated Sprague-Dawley rats). Initial concentrations from 125 to 500 ppm were tested. In all experiments an increased initial concentration gave an increased mutagenic response. The mutagenic effect in the presence of S9 was similar to that in the absence of S9.

The rate constant for the gas-phase reaction of methyl nitrite with photochemically-produced hydroxyl radicals has been estimated as 2.2X10-13 cu cm/molecule-sec at 25 °C(SRC) using a structure estimation method(1). This corresponds to an atmospheric half-life of about 73 days at an atmospheric concentration of 5X10+5 hydroxyl radicals per cu cm(1). Methyl nitrite absorbs light in the environmental spectrum(2), therefore the potential for direct photolysis exists.