Hydrazoic acid

Containers may explode in fire. Storage containers and parts of containers may rocket great distances, in many directions. If material or contaminated runoff enters waterways, notify downstream users or potentially contaminated waters. Notify local health and fire officials and pollution control agencies. From a secure, explosion-proof location use water spray to cool exposed containers. If cooling streams are ineffective (venting sound increases in volume and pitch, tank discolors or shows any signs of deforming), withdraw immediately to a secure position ... The only respirators recommended for fire fighting are self-contained breathing apparatuses that have full facepieces and are operated in a pressure-demand or other positive-pressure mode.

Evacuate and restrict persons not wearing protective equipment from area of spill or leak until clean-up is complete. Remove all ignition sources. Ventilate area of spill or leak. Absorb liquids in vermiculite, dry sand, earth, peat, carbon, or a similar material and deposit in sealed containers. Keep the chemical out of a confined space, such as a sewer, because of the possibility of an explosion, unless the sewer is designed to prevent the build-up of explosive concentrations. It may be necessary to contain and dispose of this chemical as a hazardous waste. If material or contaminated runoff enters waterways, notify downstream users of potentially contaminated waters. Contact your Department of Environmental Protection or your regional office of the federal EPA for specific recommendations.

SRP: The most favorable course of action is to use an alternative chemical product with less inherent propensity for occupational harm/injury/toxicity 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 and plant life; and conformance with environmental and public health regulations.

May be destroyed by converting hydrazoic acid to sodium azide and the reaction mixture decomposed with nitrous acid.

SRP: The scientific literature for the use of contact lenses by industrial workers is inconsistent. The benefits or detrimental effects of wearing contact lenses depend not only upon the substance, but also on factors including the form of the substance, characteristics and duration of the exposure, the uses of other eye protection equipment, and the hygiene of the lenses. However, there may be individual substances whose irritating or corrosive properties are such that the wearing of contact lenses would be harmful to the eye. In those specific cases, contact lenses should not be worn. In any event, the usual eye protection equipment should be worn even when contact lenses are in place.

SRP: Contaminated protective clothing should be segregated in such a manner so that there is no direct personal contact by personnel who handle, dispose, or clean the clothing. The completeness of the cleaning procedures should be considered before the decontaminated protective clothing is returned for reuse by the workers. Contaminated clothing should not be taken home at the end of shift, but should remain at employee's place of work for cleaning.

SRP: Wastewater from contaminant suppression, cleaning of protective clothing/equipment, or contaminated sites should be contained and evaluated for subject chemical or decomposition product concentrations. Concentrations shall be lower than applicable environmental discharge or disposal criteria. Alternatively, pretreatment and/or discharge to a permitted wastewater treatment facility is acceptable only after review by the governing authority and assurance that "pass through" violations will not occur. Due consideration shall be given to remediation worker exposure (inhalation, dermal and ingestion) as well as fate during treatment, transfer and disposal. If it is not practicable to manage the chemical in this fashion, it must be evaluated in accordance with EPA 40 CFR Part 261, specifically Subpart B, in order to determine the appropriate local, state and federal requirements for disposal.

Wear protective gloves and clothing to prevent any reasonable probability of skin contact ... Wear splash-proof chemical goggles and faceshield unless full facepiece respiratory protection is worn.

Where there is potential for exposure to the chemical, use a NIOSH/MSHA approved supplied-air respirator with a full facepiece operated in the positive pressure mode or with a full facepiece, hood, or helmet in the continuous flow mode, or use a NIOSH/MSHA approved self-contained breathing apparatus with a full facepiece operated in pressure-demand or other positive pressure mode.

TERRESTRIAL FATE: Based on a classification scheme(1), an estimated Koc value of 3(SRC), determined from a structure estimation method(2), indicates that hydrazoic acid is expected to have very high mobility in soil(SRC). The pKa of hydrazoic acid is 4.72(3), indicating that this compound will exist almost entirely in anion form in the environment and anions generally do not adsorb more strongly to soils containing organic carbon and clay than their neutral counterparts(4). Volatilization from moist soil is not expected because the acid exists as an anion and anions do not volatilize(SRC). Hydrazoic acid is expected to volatilize from dry soil surfaces(SRC) based upon an estimated vapor pressure of 484 mm Hg at 25 °C(SRC), determined from a fragment constant method(5). Biodegradation data in soil were not available(SRC, 2010).

AQUATIC FATE: Based on a classification scheme(1), an estimated Koc value of 3(SRC), determined from a structure estimation method(2), indicates that hydrazoic acid is not expected to adsorb to suspended solids and sediment(SRC). A pKa of 4.72(3) indicates hydrazoic acid will exist almost entirely in the anion form at pH values of 5 to 9 and therefore volatilization from water surfaces is not expected to be an important fate process(4). According to a classification scheme(5), an estimated BCF of 3(SRC), from an estimated log Kow of 1.16(6) and a regression-derived equation(7), suggests the potential for bioconcentration in aquatic organisms is low(SRC). Biodegradation data in water were not available(SRC, 2010).

ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), hydrazoic acid, which has an estimated vapor pressure of 484 mm Hg at 25 °C(SRC), determined from a fragment constant method(2), is expected to exist solely as a vapor in the ambient atmosphere. Vapor-phase hydrazoic acid is degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals(SRC); the half-life for this reaction in air is estimated to be 4 to 12 days(SRC), calculated from rate constants of 3.9X10-12(3) and 1.3X10-12(4) cu cm/molecule-sec. Direct photolysis of hydrazoic acid in the gaseous phase by sunlight has a half-life of 52 hours(4).

Using a structure estimation method based on molecular connectivity indices(1), the Koc of hydrazoic acid can be estimated to be 3(SRC). According to a classification scheme(2), this estimated Koc value suggests that hydrazoic acid is expected to have very high mobility in soil. Hydrazoic acid has been reported to be quite mobile and readily leachable in most soils(3).

/SIGNS AND SYMPTOMS/ Short Term Exposure: Irritating to skin, eyes, and respiratory tract. Continued inhalation causes cough, headache, dizziness, weakness, fall in blood pressure, chills and fever, and collapse. Prolonged exposure to high concentration can cause fatal convulstions and death. Highly toxic. Long Term Exposure: Chronic exposure can affect the central nervous system: hypotension, palpitation, ataxia, and weakness.

/CASE REPORTS/ ... This article is a case report on two young male workers, who were unloading drums of sodium azide powder when they accidentally inhaled the powder while cleaning up the material. Hypotension, nausea, vomiting and weakness were the symptoms experienced, followed by a persistent reactive airway dysfunction syndrome. It has been postulated that both sodium azide and hydrazoic acid contributed to the observed adverse effects.

/SURVEILLANCE/ ... In 1994-1995, the National Institute for Occupational Safety and Health (NIOSH) conducted a cross-sectional study of health complaints reported by sodium azide production workers at the only continuous sodium azide production facility in the United States. The NIOSH evaluation consisted of a plant industrial hygiene survey, a symptom questionnaire, ambulatory blood pressure monitoring, and blood azide analysis. Personal breathing zone air monitoring revealed exposures to sodium azide and hydrazoic acid (a reactant product) at levels greater than the NIOSH Recommended Exposure Limits (RELs). In some cases, exposures exceeded the REL despite the use of air-supplied respirators. The questionnaire revealed that most workers reported headache (10 of 11 [91%]), episodes of low blood pressure (9 of 11 [82%]), and palpitations (8 of 11 [73%]) occurring in the production areas within the 6 months preceding the study. Mild headache (4 of 11 [36%]) was the only symptom reported during our 24-hr medical survey. Ambulatory blood pressure monitoring revealed one asymptomatic employee with a drop in blood pressure (defined as a drop in systolic [at least 20 mm Hg] and diastolic [at least 10 mm Hg] blood pressure) during a period of exposure to sodium azide at a level five times the NIOSH REL. Improvements in plant engineering controls, increased attention to employee hygiene practices, and a more comprehensive respiratory protection program were recommendations made by NIOSH to reduce exposures at the plant. All facilities handling sodium azide should be aware of the potential toxicity of sodium azide and hydrazoic acid.

Hydrazoic acid's production and use as a chemical intermediate for heavy metal azides(1) may result in its release to the environment through various waste streams(SRC). It is formed upon deployment of air bags that use sodium azide as an inflating agent and sodium azide also forms hydrazoic acid rapidly in its use as a biocide(2), resulting in its direct release to the environment(SRC).

An estimated BCF of 3 was calculated in fish for hydrazoic acid(SRC), using an estimated log Kow of 1.16(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).

A pKa of 4.72(1) indicates hydrazoic acid will exist almost entirely in the anion form at pH values of 5 to 9 and therefore volatilization from water and moist soil surfaces is not expected to be an important fate process(2). Hydrazoic acid is expected to volatilize from dry soil surfaces(SRC) based upon an estimated vapor pressure of 484 mm Hg(SRC), determined from a fragment constant method(3).

/GENOTOXICITY/ Hormone-like peptides are, almost by definition, not mutagenic. It was, therefore, unusual to find that some batches of peptides synthesized by azide coupling were mutagenic in the Ames test. One of these peptides, eledoisin, showed mutagenic activity particularly in Salmonella typhimurium TA 1535 without metabolic activation. This activity was independent of the peptide purity determined by HPLC and a dose response relationship was observed at concentrations over the solubility limit of the peptide in the assay medium ... /It was/ considered that the mutagenicity detected was due to traces of hydrazoic acid salts arising during azide formation in the coupling step. In fact only the product of the coupling reaction between the pivotal intermediates was mutagenic.

/GENOTOXICITY/ In T. paludosa, pollen mother cells of each of the buds of an inflorescence are synchronized at different meiotic stages, thus facilitating the treatment of the appropriate buds containing only, the mutagen-sensitive, prophase stage. Damage to chromosomes at early prophase can be determined by scoring the frequency of micronuclei (MCN) in tetrads 24-30 hr after treatment ... Liquid ethyl methanesulfonate (EMS), at 50 and 100 mM, absorbed through the stem, induced 13.2 and 15.2 MCN/100 tetrads, respectively, while gaseous EMS (1000 ppm) induced 17.4 MCN/100 tetrads. Liquid NaN3, at 0.2 mM induced 10.1 MCN/100 tetrads, while 136 ppm of gaseous HN3, which is the fume released from NaN3 reacted with acid, induced 21.2 MCN/100 tetrads. The control of each of the experimental groups yielded around 5 MCN/100 tetrads ...

/OTHER TOXICITY INFORMATION/ The computer-optimized molecular parametric analysis of chemical toxicity (COMPACT) procedure has been used to determine the molecular conformation and electronic structure of a series of 40 chemicals (out of a total of 44). The procedure can evaluate whether they interact with the active site of cytochrome P450 I or to the binding site of the Ah receptor, and hence to manifest carcinogenicity/toxicity. ... Correlation of COMPACT with potential genotoxicity was 25/40 (63%); COMPACT also predicted toxicity/carcinogenicity in 10 chemicals (25%) considered to be potentially non-genotoxic (naphthalene, promethazine, resorcinol, p-nitrophenol, tricresyl phosphate, bis(bromoethyl) propanediol, 3,4-dihydrocoumarin, theophylline, triamterene and chloramine), and predicted the absence of toxicity in four chemicals (10%) considered to be potentially genotoxic (methyl bromide, hydrazoic acid, 2,3-dibromo-1-propanol and 1,2,3-trichloropropane).

Hydrolysis may not be an important environmental fate process since this compound lacks functional groups that hydrolyze under environmental conditions(1). The rate constant for the vapor-phase reaction of hydrazoic acid with photochemically-produced hydroxyl radicals has been measured as 1.3X10-12(2) and 3.9X10-12(3) cu cm/molecule-sec. These correspond to atmospheric half-lives of about 12 and 4 days, respectively, at an atmospheric concentration of 5X10+5 hydroxyl radicals per cu cm(4). Direct photolysis of hydrazoic acid in the gaseous phase by sunlight has a half-life of 52 hours(2).

Occupational exposure to hydrazoic acid may occur through inhalation and dermal contact with this compound at workplaces where hydrazoic acid is produced or used. Monitoring data indicate that the general population may be exposed to hydrazoic acid via inhalation of gasses upon deployment of air bags(1).

Hydrazoic acid's production and use as a chemical intermediate for heavy metal azides may result in its release to the environment through various waste streams. It is formed upon deployment of air bags that use sodium azide as an inflating agent and sodium azide also forms hydrazoic acid rapidly in its use as a biocide, resulting in its direct release to the environment. If released to air, an estimated vapor pressure of 484 mm Hg at 25 °C indicates hydrazoic acid will exist solely as a vapor in the atmosphere. Vapor-phase hydrazoic acid will be degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals; the half-life for this reaction in air is estimated to be 4-12 days. Direct photolysis of hydrazoic acid in the gaseous phase by sunlight has a half-life of 52 hours. If released to soil, hydrazoic acid is expected to have very high mobility based upon an estimated Koc of 3. The pKa of hydrazoic acid is 4.72, indicating that this compound will exist almost entirely in anion form in the environment and anions generally do not adsorb more strongly to soils containing organic carbon and clay than their neutral counterparts. Volatilization from moist soil is not expected because the acid exists as an anion and anions do not volatilize. Hydrazoic acid may volatilize from dry soil surfaces based upon its estimated vapor pressure. Biodegradation data were not available. If released into water, hydrazoic acid is not expected to adsorb to suspended solids and sediment based upon the estimated Koc. The pKa indicates hydrazoic acid will exist almost entirely in the anion form at pH values of 5 to 9 and therefore volatilization from water surfaces is not expected to be an important fate process. Hydrolysis may not be an important environmental fate process since this compound lacks functional groups that hydrolyze under environmental conditions. An estimated BCF of 3 suggests the potential for bioconcentration in aquatic organisms is low. Occupational exposure to hydrazoic acid may occur through inhalation and dermal contact with this compound at workplaces where hydrazoic acid is produced or used. Monitoring data indicate that the general population may be exposed to hydrazoic acid via inhalation of gasses upon deployment of air bags. (SRC)