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Ammonium nitrate
Ammonium nitrate Toxic Tips INTRODUCTION Chemical Description
Ammonium nitrate (NH4NO3) (CAS Number 6484-52-2) is also known as nitram or nitric acid, ammonium salt.1 This compound is found as odorless, colorless, transparent, hygroscopic crystals or white granules.2 It is a powerful oxidizer, but a relatively stable explosive that is soluble in water.3 It has a molecular weight of 80.04.2 One method used in industry for synthesizing this compound is the neutralization of aqueous nitric acid (HNO3) with liquid ammonia (NH3).4 This is shown in the following chemical reaction:
the skin. The concentration of ammonium nitrate consumed and the time of exposure to the contaminant will determine the amount of toxicant absorbed in the body. Mechanism of Action
After a sufficient amount of ammonium nitrate is ingested and converted to nitrite by intestinal bacteria, it can then be absorbed into the blood and cause methemoglobinemia, which brings on headache, fatigue, and a blue color to the skin and lips.1,6 Signs and symptoms of ammonium nitrate toxicity are directly correlated with the percentage of total hemoglobin in the oxidized form.7
HNO3 ðaqÞ þ NH3 ! NH4 NO3 ðaqÞ CLINICAL PRESENTATION Uses and Typical Exposure Situations
About 84% of ammonium nitrate is consumed in fertilizer and about 16% in the production of explosives and blasting agents. It is widely used in disposable cold packs in medical treatment facilities. Miners can be occupationally exposed to airborne ammonium nitrate as a result of its use as a blasting agent in mines. Workers involved in producing this compound can be exposed to ammonia nitrate aerosol and nitrogenous gases. Ammonium nitrate fuel oil (ANFO) is so extensively used that it has displaced nitroglycerin based dynamites in many commercial explosives. Sadly, due to its explosive nature, it has been involved in repeated disasters, including the explosion of the ship SS Grandcamp docked in Texas City, TX, in 1947; in the bombing of the Alfred P. Murrah Federal Building in downtown Oklahoma City, in 1995, in which the ammonium nitrate was mixed with various organic compounds and diesel fuel4; and then most recently, it has been implicated in the blast that destroyed much of West, Texas, on April 17, 2013.5
PATHOPHYSIOLOGY Determinants of Toxicity
The airborne concentration of ammonium nitrate, the respiratory rate of the individual, and time of exposure to the contaminant will determine the amount of toxicant absorbed into the respiratory system. The area of the skin exposed, concentration of ammonium nitrate, and the length of time of skin contact will determine the amount absorbed through
38
ß Division of Chemical Health and Safety of the American Chemical Society Elsevier Inc. All rights reserved.
Effects Following Inhalation
Inhaling this compound can irritate the mucous membranes of the nose, throat and lungs.1 Effects Following Skin and Eye Exposure
Direct contact with this compound can irritate and burn the skin and eyes.1 Effects Following Ingestion
Unless a large amount of ammonium nitrate is ingested, severe toxicity does not develop. After ingestion, gastritis and slight methemoglobinemia can occur.4 Carcinogenicity and Reproductive Effects
Ammonium nitrate has not been tested for its ability to cause cancer in experimental animals. It has also not been tested for its ability to affect reproduction.1
FIRST AID AND CLINICAL MANAGEMENT
If inhalation exposure has occurred, move the individual to fresh air and monitor for respiratory distress, administering oxygen as required. If not breathing, give artificial respiration. Following eye exposure, irrigate the exposed eyes with large amounts of room temperature water for at least fifteen minutes. If dermal exposure has occurred, remove contaminated clothing and wash exposed area thoroughly with soap and water. Remember that contaminated clothing can be a fire risk when dry.4
1871-5532/$36.00 http://dx.doi.org/10.1016/j.jchas.2013.06.005
HANDLING AND STORAGE
EXPOSURE CONTROLS
Accidental Release Measures
Sampling and Analysis
If a spill occurs, evacuate people and then secure and control the entrance into the area. Quickly eliminate all ignition sources. Using a clean shovel, place spilled material into noncombustible containers. Ventilate and wash the area down where the spill occurred. Keep this compound from reaching the sewer, because of the possibility of explosion.1
The monitoring method for ammonium nitrate used by OSHA is to collect air on a pre-weighed 37 mm low-ash polyvinyl chloride (PVC) filter followed by the use of gravimetric determination (OSHA PV2121).9 Gravimetric analysis is non-specific and all types of airborne particulate matter is collected on the filter. The particulate matter can be further analyzed by measuring ammonia (OSHA ID-188). Although OSHA and NIOSH do not have specific sampling and analysis methods for ammonium nitrate in air, there are numerous other analytical laboratory methods published for this compound when it is in grains, food products, soil, fertilizers, water, domestic and industrial wastes. Many of these methods determine inorganic nitrogen ions using ion chromatography, which could also be employed in the analysis of air samples.
Storage Guidelines
Ammonium nitrate must be stored in tightly closed containers that are located in a cool, well ventilated area away from moisture. They must be protected from physical damage, shock, heat, and contamination. They should be stored on a clean concrete floor.1 Reactivities and Incompatibilities
Since it is a strong oxidizer, when contaminated with oil, charcoal, or other organic material, it can explode. It reacts vigorously with strong bases, such as sodium hydroxide. It is not compatible with reducing agents; combustibles; strong acids, such as hydrochloric acid; powdered metals; metal salts; and other oxidizing agents.1 In fact, it can ignite upon contact with many of these substances. If a fire occurs, use water in large amounts to flood the fire area. Fight the fire from a distance.4 The mass of materials must be kept cool during a fire, since ammonium nitrate may explode under confinement and high temperatures.3 Heating this compound may cause violent combustion or explosion. It decomposes upon heating, producing toxic nitrogen oxides.8
Exposure Guidelines
Occupational exposure limits for ammonium nitrate have not been established by the American Conference of Governmental Industrial Hygienists (ACGIH), the Occupational Safety and Health Administration (OSHA), or the National Institute for Occupational Safety and Health (NIOSH). Be that as it may, it is still a strong irritant in the workplace causing harmful effects if inhalation or skin exposure occur.1
PERSONAL PROTECTION
If a high exposure is possible, wear a NIOSH approved positive pressure self-contained breathing apparatus. Wear chemical protective clothing that
Journal of Chemical Health & Safety, July/August 2013
is recommended by the manufacturer. Wear eye protection with side shields or goggles.1
REFERENCES 1. New Jersey Department of Health and Senior Services. Hazardous Substance Fact Sheet for Ammonium Nitrate. 2013, Downloaded from http://nj.gov/ health/eoh/rtkweb/documents/fs/ 0106.pdf on 06.03.13. 2. O’Neil, M. J.; Heckelman, P. E.; Koch, C. B.; Roman, K. J. The Merck Index, 14th ed. Merck & Co., Inc.; Whitehouse Station, NJ, 2006, 87–88. 3. Lewis, R. J. Sax’s Dangerous Properties of Industrial Materials, 8th ed. Van Nostrand Reinhold; New York, NY, 1992, 229–230. 4. National Library of Medicine, Hazardous Substances Data Bank (HSDB). Ammonium Nitrate. 2013, Downloaded from http://toxnet.nlm.nih.gov/cgi-bin/ sis/search/f?./temp/v4LfTm:1:FULL on 16.05.13. 5. Hess, G.; Johnson, J. Texas explosion facts emerge. Chem Eng. News, 2013, 29(April), 5. 6. National Library of Medicine, HAZMAP. Ammonium Nitrate. 2013, Downloaded from http://hazmap.nlm.nih.gov/category-details?id=1024&table=copyblagents on 16.05.13. 7. Agency for Toxic Substances and Disease Registry (ATSDR). Nitrate/Nitrite Toxicity. Case Studies in Environmental Medicine. January, 2007, . 8. National Institute for Occupational Safety and Health (NIOSH). International Chemical Safety Cards: Ammonium Nitrate. 2013, Downloaded from http://www.cdc.gov/niosh/ipcsneng/ neng0216.html on 16.05.13. 9. Occupational Safety and Health Administration (OSHA). Chemical Sampling Information for Ammonium Nitrate. 2013, Downloaded from http://www. osha.gov/dts/chemicalsampling/data/ CH_218475.html on 16.05.13.
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Ammonium nitrate (NH4NO3) (CAS Number 6484-52-2) is also known as nitram or nitric acid, ammonium salt.1 This compound is found as odorless, colorless, transparent, hygroscopic crystals or white granules.2 It is a powerful oxidizer, but a relatively stable explosive that is soluble in water.3 It has a molecular weight of 80.04.2 One method used in industry for synthesizing this compound is the neutralization of aqueous nitric acid (HNO3) with liquid ammonia (NH3).4 This is shown in the following chemical reaction:
the skin. The concentration of ammonium nitrate consumed and the time of exposure to the contaminant will determine the amount of toxicant absorbed in the body. Mechanism of Action
After a sufficient amount of ammonium nitrate is ingested and converted to nitrite by intestinal bacteria, it can then be absorbed into the blood and cause methemoglobinemia, which brings on headache, fatigue, and a blue color to the skin and lips.1,6 Signs and symptoms of ammonium nitrate toxicity are directly correlated with the percentage of total hemoglobin in the oxidized form.7
HNO3 ðaqÞ þ NH3 ! NH4 NO3 ðaqÞ CLINICAL PRESENTATION Uses and Typical Exposure Situations
About 84% of ammonium nitrate is consumed in fertilizer and about 16% in the production of explosives and blasting agents. It is widely used in disposable cold packs in medical treatment facilities. Miners can be occupationally exposed to airborne ammonium nitrate as a result of its use as a blasting agent in mines. Workers involved in producing this compound can be exposed to ammonia nitrate aerosol and nitrogenous gases. Ammonium nitrate fuel oil (ANFO) is so extensively used that it has displaced nitroglycerin based dynamites in many commercial explosives. Sadly, due to its explosive nature, it has been involved in repeated disasters, including the explosion of the ship SS Grandcamp docked in Texas City, TX, in 1947; in the bombing of the Alfred P. Murrah Federal Building in downtown Oklahoma City, in 1995, in which the ammonium nitrate was mixed with various organic compounds and diesel fuel4; and then most recently, it has been implicated in the blast that destroyed much of West, Texas, on April 17, 2013.5
PATHOPHYSIOLOGY Determinants of Toxicity
The airborne concentration of ammonium nitrate, the respiratory rate of the individual, and time of exposure to the contaminant will determine the amount of toxicant absorbed into the respiratory system. The area of the skin exposed, concentration of ammonium nitrate, and the length of time of skin contact will determine the amount absorbed through
38
ß Division of Chemical Health and Safety of the American Chemical Society Elsevier Inc. All rights reserved.
Effects Following Inhalation
Inhaling this compound can irritate the mucous membranes of the nose, throat and lungs.1 Effects Following Skin and Eye Exposure
Direct contact with this compound can irritate and burn the skin and eyes.1 Effects Following Ingestion
Unless a large amount of ammonium nitrate is ingested, severe toxicity does not develop. After ingestion, gastritis and slight methemoglobinemia can occur.4 Carcinogenicity and Reproductive Effects
Ammonium nitrate has not been tested for its ability to cause cancer in experimental animals. It has also not been tested for its ability to affect reproduction.1
FIRST AID AND CLINICAL MANAGEMENT
If inhalation exposure has occurred, move the individual to fresh air and monitor for respiratory distress, administering oxygen as required. If not breathing, give artificial respiration. Following eye exposure, irrigate the exposed eyes with large amounts of room temperature water for at least fifteen minutes. If dermal exposure has occurred, remove contaminated clothing and wash exposed area thoroughly with soap and water. Remember that contaminated clothing can be a fire risk when dry.4
1871-5532/$36.00 http://dx.doi.org/10.1016/j.jchas.2013.06.005
HANDLING AND STORAGE
EXPOSURE CONTROLS
Accidental Release Measures
Sampling and Analysis
If a spill occurs, evacuate people and then secure and control the entrance into the area. Quickly eliminate all ignition sources. Using a clean shovel, place spilled material into noncombustible containers. Ventilate and wash the area down where the spill occurred. Keep this compound from reaching the sewer, because of the possibility of explosion.1
The monitoring method for ammonium nitrate used by OSHA is to collect air on a pre-weighed 37 mm low-ash polyvinyl chloride (PVC) filter followed by the use of gravimetric determination (OSHA PV2121).9 Gravimetric analysis is non-specific and all types of airborne particulate matter is collected on the filter. The particulate matter can be further analyzed by measuring ammonia (OSHA ID-188). Although OSHA and NIOSH do not have specific sampling and analysis methods for ammonium nitrate in air, there are numerous other analytical laboratory methods published for this compound when it is in grains, food products, soil, fertilizers, water, domestic and industrial wastes. Many of these methods determine inorganic nitrogen ions using ion chromatography, which could also be employed in the analysis of air samples.
Storage Guidelines
Ammonium nitrate must be stored in tightly closed containers that are located in a cool, well ventilated area away from moisture. They must be protected from physical damage, shock, heat, and contamination. They should be stored on a clean concrete floor.1 Reactivities and Incompatibilities
Since it is a strong oxidizer, when contaminated with oil, charcoal, or other organic material, it can explode. It reacts vigorously with strong bases, such as sodium hydroxide. It is not compatible with reducing agents; combustibles; strong acids, such as hydrochloric acid; powdered metals; metal salts; and other oxidizing agents.1 In fact, it can ignite upon contact with many of these substances. If a fire occurs, use water in large amounts to flood the fire area. Fight the fire from a distance.4 The mass of materials must be kept cool during a fire, since ammonium nitrate may explode under confinement and high temperatures.3 Heating this compound may cause violent combustion or explosion. It decomposes upon heating, producing toxic nitrogen oxides.8
Exposure Guidelines
Occupational exposure limits for ammonium nitrate have not been established by the American Conference of Governmental Industrial Hygienists (ACGIH), the Occupational Safety and Health Administration (OSHA), or the National Institute for Occupational Safety and Health (NIOSH). Be that as it may, it is still a strong irritant in the workplace causing harmful effects if inhalation or skin exposure occur.1
PERSONAL PROTECTION
If a high exposure is possible, wear a NIOSH approved positive pressure self-contained breathing apparatus. Wear chemical protective clothing that
Journal of Chemical Health & Safety, July/August 2013
is recommended by the manufacturer. Wear eye protection with side shields or goggles.1
REFERENCES 1. New Jersey Department of Health and Senior Services. Hazardous Substance Fact Sheet for Ammonium Nitrate. 2013, Downloaded from http://nj.gov/ health/eoh/rtkweb/documents/fs/ 0106.pdf on 06.03.13. 2. O’Neil, M. J.; Heckelman, P. E.; Koch, C. B.; Roman, K. J. The Merck Index, 14th ed. Merck & Co., Inc.; Whitehouse Station, NJ, 2006, 87–88. 3. Lewis, R. J. Sax’s Dangerous Properties of Industrial Materials, 8th ed. Van Nostrand Reinhold; New York, NY, 1992, 229–230. 4. National Library of Medicine, Hazardous Substances Data Bank (HSDB). Ammonium Nitrate. 2013, Downloaded from http://toxnet.nlm.nih.gov/cgi-bin/ sis/search/f?./temp/v4LfTm:1:FULL on 16.05.13. 5. Hess, G.; Johnson, J. Texas explosion facts emerge. Chem Eng. News, 2013, 29(April), 5. 6. National Library of Medicine, HAZMAP. Ammonium Nitrate. 2013, Downloaded from http://hazmap.nlm.nih.gov/category-details?id=1024&table=copyblagents on 16.05.13. 7. Agency for Toxic Substances and Disease Registry (ATSDR). Nitrate/Nitrite Toxicity. Case Studies in Environmental Medicine. January, 2007, . 8. National Institute for Occupational Safety and Health (NIOSH). International Chemical Safety Cards: Ammonium Nitrate. 2013, Downloaded from http://www.cdc.gov/niosh/ipcsneng/ neng0216.html on 16.05.13. 9. Occupational Safety and Health Administration (OSHA). Chemical Sampling Information for Ammonium Nitrate. 2013, Downloaded from http://www. osha.gov/dts/chemicalsampling/data/ CH_218475.html on 16.05.13.
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