isobutane

H220: Extremely flammable gas [Danger Flammable gases]

P203, P210, P222, P280, P377, P381, and P403 (click each P-code to see the statement)

H340: May cause genetic defects [Danger Germ cell mutagenicity]

H350: May cause cancer [Danger Carcinogenicity]

P203, P210, P222, P280, P318, P377, P381, P403, P405, and P501 (click each P-code to see the statement)

H220 (99.7%): Extremely flammable gas [Danger Flammable gases]

H280 (37.4%): Contains gas under pressure; may explode if heated [Warning Gases under pressure]

P203, P210, P222, P280, P377, P381, P403, and P410+P403 (click each P-code to see the statement)

Aggregated GHS information provided per 2477 reports by companies from 45 notifications to the ECHA C&L Inventory. Each notification may be associated with multiple companies.

Information may vary between notifications depending on impurities, additives, and other factors. The percentage value in parenthesis indicates the notified classification ratio from companies that provide hazard codes. Only hazard codes with percentage values above 10% are shown. For more detailed information, please visit ECHA C&L website.

H280: Contains gas under pressure; may explode if heated [Warning Gases under pressure]

H336: May cause drowsiness or dizziness [Warning Specific target organ toxicity, single exposure; Narcotic effects]

H370: Causes damage to organs [Danger Specific target organ toxicity, single exposure]

P203, P210, P222, P260, P261, P264, P270, P271, P280, P304+P340, P308+P316, P319, P321, P377, P381, P403, P403+P233, P405, P410+P403, and P501 (click each P-code to see the statement)

H332: Harmful if inhaled [Warning Acute toxicity, inhalation]

H371: May cause damage to organs [Warning Specific target organ toxicity, single exposure]

P203, P210, P222, P260, P261, P264, P270, P271, P280, P304+P340, P308+P316, P317, P319, P377, P381, P403, P403+P233, P405, P410+P403, and P501 (click each P-code to see the statement)

Fresh air, rest. Refer for medical attention.

ON FROSTBITE: rinse with plenty of water, do NOT remove clothes. Refer for medical attention .

First rinse with plenty of water for several minutes (remove contact lenses if easily possible), then refer for medical attention.

Excerpt from NIOSH Pocket Guide for Isobutane:

Eye: FROSTBITE - If eye tissue is frozen, seek medical attention immediately; if tissue is not frozen, immediately and thoroughly flush the eyes with large amounts of water for at least 15 minutes, occasionally lifting the lower and upper eyelids. If irritation, pain, swelling, lacrimation, or photophobia persist, get medical attention as soon as possible.

Skin: FROSTBITE - If frostbite has occurred, seek medical attention immediately; do NOT rub the affected areas or flush them with water. In order to prevent further tissue damage, do NOT attempt to remove frozen clothing from frostbitten areas. If frostbite has NOT occurred, immediately and thoroughly wash contaminated skin with soap and water.

Breathing: RESPIRATORY SUPPORT - If a person breathes large amounts of this chemical, move the exposed person to fresh air at once. If breathing has stopped, perform artificial respiration. Keep the affected person warm and at rest. Get medical attention as soon as possible. (NIOSH, 2024)

General First Aid:

· Call 911 or emergency medical service.

· Ensure that medical personnel are aware of the material(s) involved, take precautions to protect themselves and avoid contamination.

· Move victim to fresh air if it can be done safely.

· Administer oxygen if breathing is difficult.

· If victim is not breathing:

-- DO NOT perform mouth-to-mouth resuscitation; the victim may have ingested or inhaled the substance.

-- If equipped and pulse detected, wash face and mouth, then give artificial respiration using a proper respiratory medical device (bag-valve mask, pocket mask equipped with a one-way valve or other device).

-- If no pulse detected or no respiratory medical device available, provide continuous compressions. Conduct a pulse check every two minutes or monitor for any signs of spontaneous respirations.

· Remove and isolate contaminated clothing and shoes.

· For minor skin contact, avoid spreading material on unaffected skin.

· In case of contact with substance, remove immediately by flushing skin or eyes with running water for at least 20 minutes.

· For severe burns, immediate medical attention is required.

· Effects of exposure (inhalation, ingestion, or skin contact) to substance may be delayed.

· Keep victim calm and warm.

· Keep victim under observation.

· For further assistance, contact your local Poison Control Center.

· Note: Basic Life Support (BLS) and Advanced Life Support (ALS) should be done by trained professionals.

Specific First Aid:

· Clothing frozen to the skin should be thawed before being removed.

· In case of contact with liquefied gas, only medical personnel should attempt thawing frosted parts.

· In case of burns, immediately cool affected skin for as long as possible with cold water. Do not remove clothing if adhering to skin.

In Canada, an Emergency Response Assistance Plan (ERAP) may be required for this product. Please consult the shipping paper and/or the "ERAP" section.

(General first aid procedures)

Eye: Frostbite - If eye tissue is frozen, seek medical attention immediately; if tissue is not frozen, immediately and thoroughly flush the eyes with large amounts of water for at least 15 minutes, occasionally lifting the lower and upper eyelids. If irritation, pain, swelling, lacrimation, or photophobia persist, get medical attention as soon as possible.

Skin: Frostbite - Compressed gases may create low temperatures when they expand rapidly. Leaks and uses that allow rapid expansion may cause a frostbite hazard. Wear appropriate personal protective clothing to prevent the skin from becoming frozen.

Breathing: Respiratory support

Excerpt from ERG Guide 115 [Gases - Flammable (Including Refrigerated Liquids)]:

DO NOT EXTINGUISH A LEAKING GAS FIRE UNLESS LEAK CAN BE STOPPED. CAUTION: Hydrogen (UN1049), Deuterium (UN1957), Hydrogen, refrigerated liquid (UN1966) and Hydrogen and Methane mixture, compressed (UN2034) will burn with an invisible flame. Use an alternate method of detection (thermal camera, broom handle, etc.).

SMALL FIRE: Dry chemical or CO2.

LARGE FIRE: Water spray or fog. If it can be done safely, move undamaged containers away from the area around the fire. CAUTION: For LNG - Liquefied natural gas (UN1972) pool fires, DO NOT USE water. Use dry chemical or high-expansion foam.

FIRE INVOLVING TANKS: Fight fire from maximum distance or use unmanned master stream devices or monitor nozzles. Cool containers with flooding quantities of water until well after fire is out. Do not direct water at source of leak or safety devices; icing may occur. Withdraw immediately in case of rising sound from venting safety devices or discoloration of tank. ALWAYS stay away from tanks in direct contact with flames. For massive fire, use unmanned master stream devices or monitor nozzles; if this is impossible, withdraw from area and let fire burn. (ERG, 2024)

Shut off supply; if not possible and no risk to surroundings, let the fire burn itself out. In other cases extinguish with water spray. In case of fire: keep cylinder cool by spraying with water. Combat fire from a sheltered position.

Suitable extinguishing media: Use water spray, alcohol-resistant foam, dry chemical or carbon dioxide.

Advice for firefighters: Wear self-contained breathing apparatus for firefighting if necessary.

Use water spray to cool unopened containers.

To fight fire, stop flow of gas.

For more Fire Fighting Procedures (Complete) data for Isobutane (6 total), please visit the HSDB record page.

Vapors are heavier than air and will collect in low areas. Vapors may travel long distances to ignition sources and flashback. Vapors in confined areas may explode when exposed to fire. Containers may explode in fire. Storage containers and parts of containers may rocket great distances, in many directions.

· 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.

· Keep unauthorized personnel away.

· Stay upwind, uphill and/or upstream.

· Many gases are heavier than air and will spread along the ground and collect in low or confined areas (sewers, basements, tanks, etc.).

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

· All equipment used when handling the product must be grounded.

· Do not touch or walk through spilled material.

· Stop leak if you can do it without risk.

· If possible, turn leaking containers so that gas escapes rather than liquid.

· Use water spray to reduce vapors or divert vapor cloud drift. Avoid allowing water runoff to contact spilled material.

· Do not direct water at spill or source of leak.

CAUTION: For LNG - Liquefied natural gas (UN1972), DO NOT apply water, regular or alcohol-resistant foam directly on spill. Use a high-expansion foam if available to reduce vapors.

· Prevent spreading of vapors through sewers, ventilation systems and confined areas.

· Isolate area until gas has dispersed.

CAUTION: When in contact with refrigerated/cryogenic liquids, many materials become brittle and are likely to break without warning.

Excerpt from ERG Guide 115 [Gases - Flammable (Including Refrigerated Liquids)]:

IMMEDIATE PRECAUTIONARY MEASURE: Isolate spill or leak area for at least 100 meters (330 feet) in all directions.

LARGE SPILL: Consider initial downwind evacuation for at least 800 meters (1/2 mile).

FIRE: If tank, rail tank car or highway tank is involved in a fire, ISOLATE for 1600 meters (1 mile) in all directions; also, consider initial evacuation for 1600 meters (1 mile) in all directions. In fires involving Liquefied Petroleum Gases (LPG) (UN1075), Butane (UN1011), Butylene (UN1012), Isobutylene (UN1055), Propylene (UN1077), Isobutane (UN1969), and Propane (UN1978), also refer to the "BLEVE - Safety Precautions" section. (ERG, 2024)

Immediate precautionary measure

· Isolate spill or leak area for at least 100 meters (330 feet) in all directions.

Large Spill

· Consider initial downwind evacuation for at least 800 meters (1/2 mile).

· If tank, rail tank car or highway tank is involved in a fire, ISOLATE for 1600 meters (1 mile) in all directions; also, consider initial evacuation for 1600 meters (1 mile) in all directions.

· In fires involving Liquefied Petroleum Gases (LPG) (UN1075), Butane (UN1011), Butylene (UN1012), Isobutylene (UN1055), Propylene (UN1077), Isobutane (UN1969), and Propane (UN1978), also refer to the "BLEVE - Safety Precautions" section.

Evacuate danger area! Consult an expert! Ventilation. Remove all ignition sources. NEVER direct water jet on liquid. Personal protection: filter respirator for organic vapours of low boiling point adapted to the airborne concentration of the substance.

ACCIDENTAL RELEASE MEASURES: Personal precautions, protective equipment and emergency procedures: Avoid breathing vapors, mist or gas. Ensure adequate ventilation. Remove all sources of ignition. Evacuate personnel to safe areas. Beware of vapors accumulating to form explosive concentrations. Vapors can accumulate in low areas. Environmental precautions: Prevent further leakage or spillage if safe to do so. Do not let product enter drains. Methods and materials for containment and cleaning up: Clean up promptly by sweeping or vacuum.

Restrict persons not wearing protective equipment from area of leak until cleanup is complete. Remove all ignition sources. Establish forced ventilation to keep levels below explosive limit. Stop flow of gas. If source of leak is a cylinder and the leak cannot be stopped in place, remove the leaking cylinder to a safe place in the open air, and repair leak or allow cylinder to empty. Keep isobutane out of a confined space, such as a sewer, because of the possibility of an explosion, unless the sewer is designed to prevent the buildup of explosive concentrations. Collect powdered material in the most convenient and safe manner and deposit in sealed containers. Ventilate area after cleanup is complete. 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.

The efficiency of any soil venting operation will depend significantly on three factors: vapor flowrate, vapor flow path relative to the contaminant distribution, and composition of the contaminant. Simple mathematical models were developed to be used as screening tools to help determine if soil venting will be a viable remediation option at any given spill site. The models relate the applied vacuum, soil permeability, and spill composition to the vapor flowrates, velocities, mass removal rates, and residual composition changes with time. In this report the screening models and some sample calculations are presented . The results illustrate the advantages and limitations of venting as a remediation tool, under both ideal and nonideal conditions.

SRP: 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 air, soil or water; effects on animal, aquatic and plant life; and conformance with environmental and public health regulations. If it is possible or reasonable use an alternative chemical product with less inherent propensity for occupational harm/injury/toxicity or environmental contamination.

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.

Product: Burn in a chemical incinerator equipped with an afterburner and scrubber but exert extra care in igniting as this material is highly flammable. Offer surplus and non-recyclable solutions to a licensed disposal company. Contact a licensed professional waste disposal service to dispose of this material; Contaminated packaging: Dispose of as unused product.

Dissolve of mix the material with a combustible solvent and burn in a chemical incinerator equipped with an afterburner and scrubber. All federal, state, and local environmental regulations must be observed.

ACCIDENTAL RELEASE MEASURES: Personal precautions, protective equipment and emergency procedures: Avoid breathing vapors, mist or gas. Ensure adequate ventilation. Remove all sources of ignition. Evacuate personnel to safe areas. Beware of vapors accumulating to form explosive concentrations. Vapors can accumulate in low areas. Environmental precautions: Prevent further leakage or spillage if safe to do so. Do not let product enter drains.

Precautions for safe handling: Avoid inhalation of vapor or mist. Use explosion-proof equipment. Keep away from sources of ignition - No smoking. Take measures to prevent the build up of electrostatic charge.

Appropriate engineering controls: Handle in accordance with good industrial hygiene and safety practice. Wash hands before breaks and at the end of workday.

Gloves must be inspected prior to use. Use proper glove removal technique (without touching glove's outer surface) to avoid skin contact with this product. Dispose of contaminated gloves after use in accordance with applicable laws and good laboratory practices. Wash and dry hands.

For more Preventive Measures (Complete) data for Isobutane (11 total), please visit the HSDB record page.

Excerpt from ERG Guide 115 [Gases - Flammable (Including Refrigerated Liquids)]:

ELIMINATE all ignition sources (no smoking, flares, sparks or flames) from immediate area. All equipment used when handling the product must be grounded. Do not touch or walk through spilled material. Stop leak if you can do it without risk. If possible, turn leaking containers so that gas escapes rather than liquid. Use water spray to reduce vapors or divert vapor cloud drift. Avoid allowing water runoff to contact spilled material. Do not direct water at spill or source of leak. CAUTION: For LNG - Liquefied natural gas (UN1972), DO NOT apply water, regular or alcohol-resistant foam directly on spill. Use a high-expansion foam if available to reduce vapors. Prevent spreading of vapors through sewers, ventilation systems and confined areas. Isolate area until gas has dispersed. CAUTION: When in contact with refrigerated/cryogenic liquids, many materials become brittle and are likely to break without warning. (ERG, 2024)

Fireproof. Cool.

Keep container tightly closed in a dry and well-ventilated place. Contents under pressure. Storage class (TRGS 510): Gases.

Store separately from all other flammable materials. Prior to working with this chemical, you should be trained on its proper handling and storage. Before entering confined space where isobutane may be present, check to make sure that an explosive concentration odes not exist. Isobutane cylinders should be stored in a cool, well-ventilated dry area of noncombustible construction. Protect containers against physical damage. Store away from sources of heat or ignition and from oxygen, chlorine, and other oxidizers. Sources of ignition, such as smoking and open flames, are prohibited where isobutane is handled, used, or stored. Ground and bond all lines and equipment used with isobutane. Wherever isobutane is used, handled, manufactured, or stored, use explosion-proof electrical equipment and fittings. Procedures for the handling, use, and storage of cylinders should be in compliance with OSHA 1910.101 and 1910.169, as with the recommendations of the Compressed Gas Association.

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

· Structural firefighters' protective clothing provides thermal protection but only limited chemical protection.

· Always wear thermal protective clothing when handling refrigerated/cryogenic liquids.

1000.0 [ppm] (for Butane, isomers)[German Research Foundation (DFG)]

5500 [ppm]

17000 [ppm]

53000 [ppm]

800 ppm (1900 mg/m³)

TWA 800 ppm (1900 mg/m3)

none See Appendix G

See: IDLH INDEX

1000.0 [ppm]

15 min Short Term Exposure Limit (STEL): 1000 ppm. Explosion hazard: the substance is a flammable asphyxiant or excursions above the TLV could approach 10% of the lower explosive limit.

1000 ppm as STEL.

1000 ppm [2012]

2400 mg/m

· DO NOT EXTINGUISH A LEAKING GAS FIRE UNLESS LEAK CAN BE STOPPED.

CAUTION: Hydrogen (UN1049), Deuterium (UN1957), Hydrogen, refrigerated liquid (UN1966) and Hydrogen and Methane mixture, compressed (UN2034) will burn with an invisible flame. Use an alternate method of detection (thermal camera, broom handle, etc.)

Small Fire

· Dry chemical or CO2.

Large Fire

· Water spray or fog.

· If it can be done safely, move undamaged containers away from the area around the fire.

CAUTION: For LNG - Liquefied natural gas (UN1972) pool fires, DO NOT USE water. Use dry chemical or high-expansion foam.

Fire Involving Tanks

· Fight fire from maximum distance or use unmanned master stream devices or monitor nozzles.

· Cool containers with flooding quantities of water until well after fire is out.

· Do not direct water at source of leak or safety devices; icing may occur.

· Withdraw immediately in case of rising sound from venting safety devices or discoloration of tank.

· ALWAYS stay away from tanks in direct contact with flames.

· For massive fire, use unmanned master stream devices or monitor nozzles; if this is impossible, withdraw from area and let fire burn.

A harmful concentration of this gas in the air will be reached very quickly on loss of containment.

Rapid evaporation of the liquid may cause frostbite. The substance may cause effects on the cardiovascular system. This may result in impaired functions and respiratory failure. Exposure at high levels could cause death.

Residues of isobutane are exempted from the requirement of a tolerance when used in accordance with good agricultural practice as inert (or occasionally active) ingredients in pesticide formulations applied to growing crops or to raw agricultural commodities after harvest. Use: Propellant. Limit: None.

Residues of isobutane are exempted from the requirement of a tolerance when used in accordance with good agricultural practice as inert (or occasionally active) ingredients in pesticide formulations applied to animals. Use: Propellant. Limit: None.

Excerpt from NIOSH Pocket Guide for Isobutane:

Skin: FROSTBITE - Compressed gases may create low temperatures when they expand rapidly. Leaks and uses that allow rapid expansion may cause a frostbite hazard. Wear appropriate personal protective clothing to prevent the skin from becoming frozen.

Eyes: FROSTBITE - Wear appropriate eye protection to prevent eye contact with the liquid that could result in burns or tissue damage from frostbite.

Wash skin: No recommendation is made specifying the need for washing the substance from the skin (either immediately or at the end of the work shift).

Remove: WHEN WET (FLAMMABLE) - Work clothing that becomes wet should be immediately removed due to its flammability hazard (i.e., for liquids with a flash point <100 °F).

Isobutane is a colorless gas with a faint petroleum-like odor. It is shipped as a liquefied gas under its vapor pressure. Contact with the liquid can cause frostbite. It is easily ignited. The vapors are heavier than air. Any leak can either be liquid or vapor. It can asphyxiate by the displacement of air. Under prolonged exposure to fire or intense heat the containers may rupture violently and rocket.

CBI; Gas Vapor; Liquid; Gas Vapor; Liquid

Colourless gas or liquid with mild, characteristic odour

Colorless gas with a slight gasoline or natural gas odor; [HSDB]

COLOURLESS COMPRESSED LIQUEFIED GAS WITH CHARACTERISTIC ODOUR.

Colorless gas with a gasoline-like or natural gas odor.

Colorless gas with a gasoline-like or natural gas odor. [Note: Shipped as a liquefied compressed gas. A liquid below 11 °F.]

Colorless gas [Note: Shipped as a liquified compressed gas. A liquid below 11 °F]

Gasoline-like or natural gas odor.

Slight odor

10.8 °F at 760 mmHg (USCG, 1999)

-11.7 °C

-11.73 °C @760 [mm Hg]

-255 °F (NIOSH, 2024)

-138.3 °C

-216.9 °F

-159.4 °C

-117 °F (USCG, 1999)

-82.99 °C (-117.38 °F) - closed cup

Flammable gas

NA (Gas)

Slight (NIOSH, 2024)

In water, 48.9 mg/L at 25 °C

Soluble in ethanol, ether, chloroform

Solubility in water at 20 °C: none

0.557 at 68 °F (USCG, 1999) - Less dense than water; will float

0.55092 g/cu cm at 25 °C; 0.55711 g/cu cm at 20 °C; 0.61415 at -29.5 °C

Relative density (water = 1): 0.6 (liquid)

0.551 @25 °C

2.06(relative gas density)

2.06 (NIOSH, 2024) - Heavier than air; will sink (Relative to Air)

2.01 (Air = 1)

Relative vapor density (air = 1): 2

3.1 atm at 70 °F (NIOSH, 2024)

2610.0 [mmHg]

2610 mm Hg (348.1 kPa) at 25 °C; 391.02 mm Hg (52.132 kPa) at -27.57 °C

Vapor pressure, kPa at 20 °C: 304

3.1 atm at 70 °F

750 [mm Hg] @-12 °C

(70 °F): 3.1 atm

Highly flammable.

Hydrocarbons, Aliphatic Saturated

Highly Flammable

ISOBUTANE is incompatible with the following: Strong oxidizers (e.g., nitrates & perchlorates), chlorine, fluorine, (nickel carbonyl + oxygen) (NIOSH, 2024).

Incompatible materials: Strong oxidizing agents.

Forms explosive gas mixture with air. Strong oxidizers (e.g., nitrates, perchlorates, chlorine, fluorine) and nickel carbonyl + oxygen may cause fire and explosions. Reacts with acetylene, halogens, and nitrous oxides.

Reacts with strong oxidants, acetylene, halogens and nitrogen oxides. This generates fire and explosion hazard.

Strong oxidizers (eg, nitrates & perchlorates), chlorine, fluorine, (nickel carbonyl + oxygen).

Strong oxidizers (e.g., nitrates & perchlorates), chlorine, fluorine, (nickel carbonyl + oxygen)

Safe in the present practices of use and concentration. Ingredient, concentration, and use information are available in documents discoverable at https://cir-reports.cir-safety.org

IDENTIFICATION AND USE: Isobutane is a colorless gas. It is used in organic synthesis, as a refrigerant, in motor fuels, and as aerosol propellant, as well as in synthetic rubber, and in instrument calibration fluid. HUMAN STUDIES: Isobutane is a simple asphyxiant. Acute exposure may cause tachypnea and tachycardia. In severe cases, hypotension, apnea, and cardiac arrest develop. Direct contact with the liquid produces chemical burns. Toxicologically, the vapor exerts no effect on skin and eyes. A case of ventricular fibrillation due to isobutane toxicity after unintentional inhalation of air freshener has been reported. The intentional inhalation of a volatile substance ("sniffing") causing euphoria and hallucinations is a form of substance abuse in children and adolescents with a high morbidity and mortality. Sudden death can be caused by cardiac arrhythmia, asphyxia or trauma. Fatal cases of isobutane sniffing of cigarette lighter refill containing isobutane has been reported. ANIMAL STUDIES: Studies in rabbits exposed through the eyes to undiluted hairspray containing 22% isobutane showed that irritation of the eye was immediately evident with transient iritis and mild conjunctivitis. Acute exposure in dogs to 55 mg/L isobutane was fatal, and 45 mg/L caused anesthesia. Two-hour exposures of mice to 41 mg/L isobutane caused death in 60% of the exposed animals, whereas exposure to 52 mg/L was lethal to 100% of the animals within an average of 28 min. Isobutane is a CNS depressant in the mouse at 15% in 60 min, and at 23% in 26 min. Isobutane caused apnea and finally cardiac arrest in anesthetized rats. Isobutane tested negative in the Ames Salmonella mutagenicity assay.

Butane is a simple asphyxiant and causes toxicity by displacing oxygen. It also affects the central nervous system by enhancing glycine receptors and inhibiting nicotinic acetylcholine and N-methyl-d-aspartate (NMDA) receptors, resulting in anesthetic effects. (L1284, A352)

No indication of carcinogenicity to humans (not listed by IARC).

Butane targets the central nervous system and cardiovascular system. Inhalation of butane can cause frostbite which can result in death from asphyxiation and ventricular fibrillation. (L1283, L1284)

The substance can be absorbed into the body by inhalation.

inhalation, skin and/or eye contact (liquid)

Inhalation (L1283)

Shortness of breath. Suffocation.

ON CONTACT WITH LIQUID: FROSTBITE.

drowsiness, narcosis, asphyxia; liquid: frostbite

Inhalation of butane can cause euphoria, hallucinations, confusion, blurred vision, slurred speech, nausea, vomiting, coughing, sneezing, increased salivation, drowsiness, narcosis, asphyxia, cardiac arrhythmia, and frostbite. (L1283, L1284)

central nervous system

Neurotoxin - Acute solvent syndrome

Other Poison - Simple Asphyxiant

LC50 (rat) = 570,000 ppm/15 min

LC50: 52 mg/L over 1 hour (Inhalation, Mouse) (T29)

LC50 Rat inhalation 57 pph/15 min

LC50 Mouse inhalation 52 mg/L/1 hr

Treatment for butane poisoning is supportive and symptomatic. Stimulants should not be administered. Recovery normally occurs quickly once exposure has ceased but support of the cardiovascular and respiratory systems may be needed. (L1284)

Immediate first aid: Ensure that adequate decontamination has been carried out. If patient is not breathing, start artificial respiration, preferably with a demand-valve resuscitator, bag-valve-mask device, or pocket mask, as trained. Perform CPR if necessary. Immediately flush contaminated eyes with gently flowing water. Do not induce vomiting. If vomiting occurs, lean patient forward or place on left side (head-down position, if possible) to maintain an open airway and prevent aspiration. Keep patient quiet and maintain normal body temperature. Obtain medical attention. /Simple asphyxiants and related compounds/

Basic treatment: Establish a patent airway (oropharyngeal or nasopharyngeal airway, if needed). Suction if necessary. Watch for signs of respiratory insufficiency and assist ventilations if necessary. Administer oxygen by nonrebreather mask at 10 to 15 L/min. Anticipate seizures and treat if necessary ... . Use rapid rewarming techniques if frostbite occurs ... . /Simple asphyxiants and related compounds/

Advanced treatment: Consider orotracheal or nasotracheal intubation for airway control in the patient who is unconscious or is in severe respiratory distress. Monitor cardiac rhythm and treat arrhythmias if necessary ... . Start IV administration of D5W /SRP: "To keep open", minimal flow rate/. Treat seizures with diazepam (Valium) or lorazepam (Ativan) ... . /Simple asphyxiants and related compounds/

If this chemical gets into the eyes, remove any contact lenses at once and irrigate immediately for at least 15 min, occasionally lifting upper and lower lids. Seek medical attention immediately. If this chemical contacts the skin, remove contaminated clothing and wash immediately with soap and water. Seek medical attention immediately. If this chemical has been inhaled, remove from exposure, begin rescue breathing (using universal precautions, including resuscitation mask) if breathing has stopped and CPR if heart action has stopped. Transfer promptly to a medical facility. When this chemical has been swallowed, get medical attention. ... If frostbite has occurred, seek medical attention immediately. Do not rub the affected areas or flush them with water. In order to prevent further tissue damage, do not attempt to remove frozen clothing from frostbitten areas. If frostbite has not occurred, immediately and thoroughly was contaminated skin with soap and water.

/HUMAN EXPOSURE STUDIES/ Eight adult volunteers of both sexes were exposed to isobutane in a controlled-environment chamber for the purpose of monitoring their physiological responses to a series of gas concentrations ranging from 250 to 1,000 ppm. First, the response to exposure periods of 1 min, 2 min, 1 hr, 2 hr, and 8 hr were studied. There being no untoward responses to these acute exposures, the eight volunteers were exposed repetitively to isobutane at concentrations of 500 ppm, 1, 2 or 8 hr per day, five days per week for two weeks. Then exposures to two mixtures of isobutane and propane for 1, 2 or 8 hr per day for two days were studied. During the investigation all subjects were kept under comprehensive medical surveillance. No untoward subjective responses or abnormal physiological responses occurred during or following these exposures. Special emphasis was placed on evaluating the cardiac and pulmonary response to these exposures through the use of continuous ECG telemetry and serial computerized spirometric measurements. The following serial laboratory studies were unaltered by the exposures: complete blood count, urinalysis, serum alkaline phosphatase, SGOT, LDH, serum bilirubin, blood sugar, serum calcium, serum phosphorus, BUN, spontaneous electroencephalogram, visual evoked response, a battery of cognitive tests, and an adrenocorticotropic hormone (ACTH) stimulation test.

/HUMAN EXPOSURE STUDIES/ Acute exposures to isobutane, propane, F-12, and F-11 in concentrations of 250, 500, or 1000 ppm for periods of 1 min to 8 hr did not produce any untoward physiological effects as determined by the methods employed which included serial EKG's and continuous monitoring of modified V5 by telemetry during exposure. Repetitive exposures to these four propellants were also without measurable untoward physiological effect with the exception of the eight male subjects repetitively exposed to 1000 ppm, F-11, who did show minor decrements in several of the cognitive tests. Of particular importance is the observation that none of the subjects showed any decrement in pulmonary function or alteration in cardiac rhythm as the result of exposure to concentrations of the gases or vapors far greater than encountered in the normal use of aerosol products in the home.

/SIGNS AND SYMPTOMS/ Isobutane is a simple asphyxiant. Acute exposure may cause tachypnea and tachycardia. In severe cases, hypotension, apnea, and cardiac arrest develop. Direct contact with the liquid produces chemical burns. Toxicologically, the vapor exerts no effect on skin and eyes.

/CASE REPORTS/ We report three cases of sudden death due to inhalation of portable cooking stove fuel (case 1), cigarette lighter fuel (case 2), and liquefied petroleum gas (LPG) (case 3). Specimens of blood, urine, stomach contents, brain, heart, lung, liver, kidney, and fat were collected and analyzed for propylene, propane, isobutane, and n-butane by headspace gas chromatography. n-Butane was the major substance among the volatiles found in the tissues of cases 1 and 2, and propane was the major substance in case 3. A combination of the autopsy findings and the gas analysis results revealed that the cause of death was ventricular fibrillation induced by hard muscle exercise after gas inhalation in cases 1 and 2, and that the cause of death in case 3 might be hypoxia. It is possible that the victim in case 3 was under anesthetic toxicity of accumulated isobutane which is a minor component of liquefied petroleum gas.

For more Human Toxicity Excerpts (Complete) data for Isobutane (6 total), please visit the HSDB record page.

/LABORATORY ANIMALS: Acute Exposure/ Studies in rabbits exposed in the eyes to undiluted hairspray containing 22% isobutane showed that irritation of the eye was immediately evident with transient iritis and mild conjunctivitis.

/LABORATORY ANIMALS: Acute Exposure/ In dogs, 55 mg/L /isobutane/ were fatal, and 45 mg/L caused anesthesia.

/LABORATORY ANIMALS: Acute Exposure/ ... 2-hr exposures of mice to 41 mg/L /isobutane/ caused death in 60% of the exposed animals, whereas exposure to 52 mg/L was lethal to 100% of the animals within an average of 28 min.

/LABORATORY ANIMALS: Acute Exposure/ The 1-hr LC50 /of isobutane/ for the mouse is 52 mg/L. At concentrations in the range of the LC50, mice exhibit CNS depression, rapid and shallow respiration, and apnea.

For more Non-Human Toxicity Excerpts (Complete) data for Isobutane (10 total), please visit the HSDB record page.

Isobutane's production and use as a refrigerant, in motor fuels, aerosol propellants, synthetic rubbers, instrument calibration fluids, organic synthesis, and as a gasoline blending component and liquefied gas fuel, may result in its release to the environment through various waste streams. Isobutane is a component of natural gas. If released to air, a vapor pressure of 2610 mm Hg at 25 °C indicates isobutane will exist solely as a gas in the atmosphere. Gas-phase isobutane 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 7 hours. Isobutane does not contain chromophores that absorb at wavelengths >290 nm and, therefore, is not expected to be susceptible to direct photolysis by sunlight. If released to soil, isobutane is expected to have moderate mobility based upon an estimated Koc of 250. Volatilization from moist soil surfaces is expected to be an important fate process based upon an estimated Henry's Law constant of 1.19 atm-cu m/mole. Isobutane is not expected to volatilize from dry soil surfaces based upon its vapor. Isobutane reached 49% mineralization after 20 days using an activated sludge inoculum suggesting that biodegradation may be an important environmental fate process under certain conditions in soil. If released into water, isobutane is expected to adsorb to suspended solids and sediment based upon the estimated Koc. Microcosm experiments designed to simulate natural estuaries reported half-lives for isobutane ranging from 16-26 days suggesting that biodegradation may be an important environmental fate process under certain conditions in water. Volatilization from water surfaces is expected to be an important fate process based upon this compound's estimated Henry's Law constant. Estimated volatilization half-lives for a model river and model lake are 47 minutes and 3 days, respectively. An estimated BCF of 30 suggests the potential for bioconcentration in aquatic organisms is low. Hydrolysis is not expected to be an important environmental fate process since this compound lacks functional groups that hydrolyze under environmental conditions (pH 5 to 9). Occupational exposure to isobutane may occur through inhalation and dermal contact with this compound at workplaces where isobutane is produced or used. Monitoring and use data indicate the general population may be exposed to isobutane via inhalation of ambient air, particularly in areas with heavy vehicular traffic or dermal exposure to products such as gasoline and fuels, insect spray, window and glass cleaner, personal spray deodorant, and rug and upholstery cleaners containing isobutane. (SRC)

Isobutane occurs in petroleum and natural gas(1).

Isobutane's production and use as a refrigerant, in motor fuels, aerosol propellants, synthetic rubbers, instrument calibration fluids, organic synthesis(1), and as a gasoline blending component and liquefied gas fuel(2), may result in its release to the environment through various waste streams(SRC).

From its Henry's Law constant and atmospheric concentrations over the ocean, oceans appear to be supersaturated with isobutane by 2-3 orders of magnitude indicating that they are a source of isobutane(1,2). However oceans appear to be a minor source of alkanes compared with continental production(2). The flux of isobutane estimated for the mid-Atlantic between 35 deg N and 30 deg S is 0.32X10+8 molec/sq cm-sec(1).

TERRESTRIAL FATE: Based on a classification scheme(1), an estimated Koc value of 250(SRC), determined from a log Kow of 2.76(2) and a regression-derived equation(3), indicates that isobutane is expected to have moderate mobility in soil(SRC). Volatilization of isobutane from moist soil surfaces is expected to be an important fate process(SRC) given an estimated Henry's Law constant of 1.19 atm-cu m/mole(SRC), derived from its vapor pressure, 2610 mm Hg(4), and water solubility, 48.8 mg/L(5). Isobutane is expected to volatilize from dry soil surfaces(SRC) based upon its vapor pressure(4). Isobutane reached 49% mineralization after 20 days using an activated sludge inoculum(6) suggesting that biodegradation may be an important environmental fate process under certain conditions in soil(SRC).

AQUATIC FATE: Based on a classification scheme(1), an estimated Koc value of 250(SRC), determined from a log Kow of 2.76(2) and a regression-derived equation(3), indicates that isobutane is expected to adsorb to suspended solids and sediment(SRC). Volatilization from water surfaces is expected(4) based upon an estimated Henry's Law constant of 1.19 atm-cu m/mole(SRC), derived from its vapor pressure, 2610 mm Hg(5), and water solubility, 48.8 mg/L(6). Using this Henry's Law constant and an estimation method(4), volatilization half-lives for a model river and model lake are 2 hours and 3 days, respectively(SRC). According to a classification scheme(7), an estimated BCF of 30(SRC), from its log Kow(2) and a regression-derived equation(3), suggests the potential for bioconcentration in aquatic organisms is low(SRC). Microcosm experiments designed to simulate natural estuaries reported half-lives for isobutane ranging from 16-26 days(8) suggesting that biodegradation may be an important environmental fate process under certain conditions in water(SRC).

Isobutane's production and use as a refrigerant, in motor fuels, aerosol propellants, synthetic rubbers, instrument calibration fluids, organic synthesis, and as a gasoline blending component and liquefied gas fuel, may result in its release to the environment through various waste streams. Isobutane is a component of natural gas. If released to air, a vapor pressure of 2610 mm Hg at 25 °C indicates isobutane will exist solely as a gas in the atmosphere. Gas-phase isobutane 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 7 hours. Isobutane does not contain chromophores that absorb at wavelengths >290 nm and, therefore, is not expected to be susceptible to direct photolysis by sunlight. If released to soil, isobutane is expected to have moderate mobility based upon an estimated Koc of 250. Volatilization from moist soil surfaces is expected to be an important fate process based upon an estimated Henry's Law constant of 1.19 atm-cu m/mole. Isobutane is not expected to volatilize from dry soil surfaces based upon its vapor. Isobutane reached 49% mineralization after 20 days using an activated sludge inoculum suggesting that biodegradation may be an important environmental fate process under certain conditions in soil. If released into water, isobutane is expected to adsorb to suspended solids and sediment based upon the estimated Koc. Microcosm experiments designed to simulate natural estuaries reported half-lives for isobutane ranging from 16-26 days suggesting that biodegradation may be an important environmental fate process under certain conditions in water. Volatilization from water surfaces is expected to be an important fate process based upon this compound's estimated Henry's Law constant. Estimated volatilization half-lives for a model river and model lake are 47 minutes and 3 days, respectively. An estimated BCF of 30 suggests the potential for bioconcentration in aquatic organisms is low. Hydrolysis is not expected to be an important environmental fate process since this compound lacks functional groups that hydrolyze under environmental conditions (pH 5 to 9). Occupational exposure to isobutane may occur through inhalation and dermal contact with this compound at workplaces where isobutane is produced or used. Monitoring and use data indicate the general population may be exposed to isobutane via inhalation of ambient air, particularly in areas with heavy vehicular traffic or dermal exposure to products such as gasoline and fuels, insect spray, window and glass cleaner, personal spray deodorant, and rug and upholstery cleaners containing isobutane. (SRC)

Isobutane occurs in petroleum and natural gas(1).

Isobutane's production and use as a refrigerant, in motor fuels, aerosol propellants, synthetic rubbers, instrument calibration fluids, organic synthesis(1), and as a gasoline blending component and liquefied gas fuel(2), may result in its release to the environment through various waste streams(SRC).

From its Henry's Law constant and atmospheric concentrations over the ocean, oceans appear to be supersaturated with isobutane by 2-3 orders of magnitude indicating that they are a source of isobutane(1,2). However oceans appear to be a minor source of alkanes compared with continental production(2). The flux of isobutane estimated for the mid-Atlantic between 35 deg N and 30 deg S is 0.32X10+8 molec/sq cm-sec(1).

TERRESTRIAL FATE: Based on a classification scheme(1), an estimated Koc value of 250(SRC), determined from a log Kow of 2.76(2) and a regression-derived equation(3), indicates that isobutane is expected to have moderate mobility in soil(SRC). Volatilization of isobutane from moist soil surfaces is expected to be an important fate process(SRC) given an estimated Henry's Law constant of 1.19 atm-cu m/mole(SRC), derived from its vapor pressure, 2610 mm Hg(4), and water solubility, 48.8 mg/L(5). Isobutane is expected to volatilize from dry soil surfaces(SRC) based upon its vapor pressure(4). Isobutane reached 49% mineralization after 20 days using an activated sludge inoculum(6) suggesting that biodegradation may be an important environmental fate process under certain conditions in soil(SRC).

AQUATIC FATE: Based on a classification scheme(1), an estimated Koc value of 250(SRC), determined from a log Kow of 2.76(2) and a regression-derived equation(3), indicates that isobutane is expected to adsorb to suspended solids and sediment(SRC). Volatilization from water surfaces is expected(4) based upon an estimated Henry's Law constant of 1.19 atm-cu m/mole(SRC), derived from its vapor pressure, 2610 mm Hg(5), and water solubility, 48.8 mg/L(6). Using this Henry's Law constant and an estimation method(4), volatilization half-lives for a model river and model lake are 2 hours and 3 days, respectively(SRC). According to a classification scheme(7), an estimated BCF of 30(SRC), from its log Kow(2) and a regression-derived equation(3), suggests the potential for bioconcentration in aquatic organisms is low(SRC). Microcosm experiments designed to simulate natural estuaries reported half-lives for isobutane ranging from 16-26 days(8) suggesting that biodegradation may be an important environmental fate process under certain conditions in water(SRC).

AQUATIC FATE: Experiments performed with gaseous C2-C4 alkanes in a microcosm designed to replicate Narragansett Bay, RI in September (20 °C) and November (10 °C) have shown that the removal rate constant of isobutane is 0.061/day (standard deviation 0.005/day) at 20 °C and 0.030/day (standard deviation 0.006/day) at 10 °C(1). The respective half-lives are 11 days and 23 days(SRC). The results indicate that gas exchange is the dominant removal mechanism for isobutane gases from the water column following a hypothetical input. Scaling up the predicted gas exchange rate constants (0.26/day and 0.017/day at 20 and 10 °C, respectively) so they are consistent with natural estuaries, the volatilization half-lives for isobutane from the water columns in natural estuaries(1) are estimated to be 4.4 and 6.8 days at 20 and 10 °C, respectively(SRC). Isobutane also biodegrades in the microcosm at a rate that is slower than for n-butane and falls between propane and ethane in susceptibility. Biodegradation of isobutane initially occurs with a half-lives of 16-26 days at 20 °C and 33-139 days at 10 °C, significantly slower than the loss predicted by gas exchange from typical natural estuaries. However, after a lag of 2-4 weeks, the biodegradation rate increases markedly so that in the case of chronic inputs, biodegradation can become the dominant removal mechanism(1).

ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), isobutane, which has a vapor pressure of 2610 mm Hg at 25 °C(2), is expected to exist solely as a gas in the ambient atmosphere. Gas-phase isobutane 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 6.8 days(SRC), calculated from its rate constant of 2.43X10-12 cu cm/molecule-sec at 25 °C(3). Gas-phase isobutane is degraded in the atmosphere by reaction with nitrate radicals(SRC); half-life for this reaction in air is estimated to be 165 days(4). Isobutane does not contain chromophores that absorb at wavelengths >290 nm(5) and, therefore, is not expected to be susceptible to direct photolysis by sunlight(SRC).

AEROBIC: Isobutane, present at 10.1 mg/L, reached 49% mineralization after 20 days (with a 5.7 day lag period) using an activated sludge inoculum from an urban WWTP; the reported degradation rate was 67 umol/L-h(1).

AEROBIC: Biodegradation half-lives for isobutane were 16-26 days at 20 °C and 33-139 days at 10 °C, using brackish water in a gas-exchange degradation experiment simulating biological conditions and nutrient levels of Narrangansett Bay, RI. The removal rate constant of isobutane is 0.061/day (standard deviation 0.005/day) at 20 °C and 0.030/day (standard deviation 0.006/day) at 10 °C(1). The respective half-lives are 11 days and 23 days(SRC). The results indicate that gas exchange is the dominant removal mechanism for isobutane gases from the water column following a hypothetical input. Scaling up the predicted gas exchange rate constants (0.26/day and 0.017/day at 20 and 10 °C, respectively) so they are consistent with natural estuaries, the volatilization half-lives for isobutane from the water columns in natural estuaries(1) are estimated to be 4.4 and 6.8 days at 20 and 10 °C, respectively(SRC). Isobutane also biodegrades in the microcosm at a rate that is slower than for n-butane and falls between propane and ethane in susceptibility. Biodegradation of isobutane is significantly slower than the loss predicted by gas exchange from typical natural estuaries. However, after a lag of 2-4 weeks, the biodegradation rate increases markedly so that in the case of chronic inputs, biodegradation can become the dominant removal mechanism(1).

PURE CULTURE: Pure cultures of C2-C4 alkane-utilizing methylotropic bacteria isolated from soil and water were found to catalyze the oxidation of isobutane to isobutanol(1). Pure cultures of bacteria (Nocardia, Pseudomonas, Actinobacter, Micrococcus, Flavobacterium) isolated from groundwater contaminated with high-octane gasoline as a result of a pipeline break near Amber, PA did not degrade isobutane after 8 days incubation(2).

The rate constant for the vapor-phase reaction of isobutane with photochemically-produced hydroxyl radicals has been calculated as 2.34X10-12 cu cm/molecule-sec at 25 °C(1). This corresponds to an atmospheric half-life of about 7 days at an atmospheric concentration of 5X10+5 hydroxyl radicals per cu cm(SRC). The hydroxyl radical reaction product, 2-methylpropionaldehyde, may further react in the atmosphere to form peroxyacyl nitrates (PANs), phytotoxic components of photochemical smog(2,3). Gas-phase isobutane is also degraded in the atmosphere by reaction with nitrate radicals(SRC); half-life for this reaction in air is estimated to be 165 days(4). Isobutane is not expected to undergo hydrolysis in the environment due to the lack of functional groups that hydrolyze under environmental conditions(5). Isobutane does not contain chromophores that absorb at wavelengths >290 nm(5) and, therefore, is not expected to be susceptible to direct photolysis by sunlight(SRC).

An estimated BCF of 30 was calculated in fish for isobutane(SRC), using a log Kow of 2.76(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 Koc of isobutane is estimated as 250(SRC), using a log Kow of 2.76(1) and a regression-derived equation(2). According to a classification scheme(3), this estimated Koc value suggests that isobutane is expected to have moderate mobility in soil.

The Henry's Law constant for isobutane is estimated as 1.19 atm-cu m/mole(SRC) derived from its vapor pressure, 2610 mm Hg(1), and water solubility, 48.8 mg/L(2). This Henry's Law constant indicates that isobutane is expected to volatilize rapidly from water surfaces(3). 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)(3) is estimated as 47 minutes(SRC). The volatilization half-life from a model lake (1 m deep, flowing 0.05 m/sec, wind velocity of 0.5 m/sec)(3) is estimated as 3 days(SRC). Isobutane's estimated Henry's Law constant indicates that volatilization from moist soil surfaces may occur(SRC). The potential for volatilization of isobutane from dry soil surfaces may exist(SRC) based upon its vapor pressure(1).

Experiments have indicated that the rate of gas exchange in natural estuaries such as Narragansett Bay and San Francisco Bay are approximately 6 times that measured in a microcosm designed to replicate conditions in Narragansett Bay, RI(1). Scaling up the experimentally-determined gas exchange rates for isobutane, 0.026/day at 20 °C and 0.017/day at 10 °C(1), the rate constant for gas exchange from the water columns in natural estuaries would be 0.16/day and 0.10/day (half-life 4.4 and 6.8 days), respectively(SRC). For comparison, the ratio of air to water concentration of isobutane (dimensionless Henry's Law constant) determined measurements made on a cruise in the Indian Ocean varied in time and place, ranging from 0.02-1.13 (4.9X10-4 to 2.8X10-2 atm-cu m/mol(SRC)), indicating that the sea is supersaturated with isobutane and sea air exchange is the controlling factor for volatilization(2).

DRINKING WATER: Isobutane was not present in the only sample of tap water analyzed in New Jersey as part of the USEPA Total Exposure Assessment Methodology (TEAM) study(1).

SURFACE WATER: The average (standard deviation) concentration of isobutane in surface water of the mid-Atlantic (35 deg N to 30 deg S) in September/October 1988 was 2.7 (3.11) picomoles/L(1). The average isobutane concentration was lower in the southern hemisphere; the concentration between 35 deg N - 8 deg N, 8 deg N - 3 deg S, and 3 deg S and 30 deg S was 4.9, 2.9 and 1.2 picomoles/L, respectively. The concentration of dissolved gas-phase isobutane in surface water in the Indian Ocean (n = 8) ranged from 0.12 to 1.78 nanoliters (gas) per liter of water(2). While the concentration varied, the relative abundance of isobutane with respect to nonmethane hydrocarbons was practically constant(2).

SURFACE WATER: Water quality data compiled from the USGS National Water Information System (NWIS) reports surface water monitoring data for isobutane at USGS stations in CA, TX, PA, AK, ID, IL, NY, OH, and LA. Data from Jan 2015 to Jan 2018 report that isobutane was not detected at any of the monitoring sites(1).

In a comprehensive survey of wastewater from 4000 industrial and publicly owned treatment works (POTWs) sponsored by the Effluent Guidelines Division of the USEPA, isobutane was identified in discharges of the following industrial category (positive occurrences, median concentration in ppb): petroleum refining (1; 102.6), plastics and synthetics (1; 109.7), oil and gas extraction (3; 16.2)(1). The highest effluent concentration was 109.7 ppb in the plastics and synthetics industry(1).

Vehicle exhaust contained 720 ppb isobutane(2). In a 1988 study in the U.K., the 6-car average concentration of isobutane in exhaust gas was 8175 ppb(1).

Isobutane is found in gasoline and commercial natural gas(3) and may be released to the environment in evaporative losses, wastewater, and spills(SRC) as well as in combustion exhaust(3). Composition profiles for isobutane in auto emissions acquired using Federal Test Procedure tests include: USEPA 46 in-use vehicles for 1975-1982 model years, 0.92 wt%; Auto/Oil Program older (1983-1985) vehicle fleet, 0.21 wt%(3). Emissions of 25 vehicles (mostly 1986 model year) were tested under different driving conditions(1). The average emission were (type of driving (avg speed), emissions in mg/km): cold start (18.51 km/hr), 75.01; warm start (18.53 km/hr), 95.68; urban (21.38 km/hr), 65.66; suburban (41.73 km/hr), 29.64; rural (54.53 km/hr), 17.44; motorway (90.72 km/hr), 8.81; motorway (111.36 km/hr), 8.57(1,2). For suburban driving, 4 low-emission vehicles had isobutane emissions ranging from 0.8-18 mg/km at 40 km/hr(2). The emission of isobutane from a car dropped from 53 mg/km at 20 km/hr to 9 mg/hr between 90 and 110 km/hr(1). In emission tests using single component fuels, isobutane occurred in engine emissions when n-heptane, 1-hexene, and cyclohexane was burned, but not with toluene, isooctane or methyl tert-butyl ether (MTBE)(4).

Isobutane emission rates for the California South Coast Air Basin is 12.1 metric tons/day(6). A study of VOC emission in California South Coast Air Basin found that the sources of isobutane were (source, percent): gasoline exhaust, 6%; whole (liquid) gasoline, 3%; gasoline vapors, 36%; waste and natural gas, 21%; other, 34%(5). No isobutane emissions were attributed to coatings and adhesives(5). Isobutane gasoline exhaust emissions in the U.K have been estimated to be 5.29 and 14.5 kilotonnes by two investigators, constituting respectively 2% and 4% of exhaust emissions(1,3). Isobutane is found in underwater hydrocarbon vent plumes from offshore production; the concn in one plume was 560 umol/L(7). Isobutane constituted 0.004% of municipal sanitary landfill gas at Palos Verdes, CA(2). The landfill was in the anaerobic phase. Isobutane was found in emissions from the combustion of waste PVC plastics under conditions of incomplete combustion but not under conditions of complete combustion(4). Isobutane is used in consumer products such as insect spray, window and glass cleaner, personal care and pet products, arts and craft products, auto and home maintenance products and rug and upholstery cleaners(8,9) and may be released when these products are manufactured or used(SRC).

SEDIMENT: Hydrocarbon gases are present in low concentrations in the upper 2 m of sediment from the shelf, slope and basin of the Bering Sea; the concentration range of isobutane in the 19 core samples analyzed were 4 to 340 nL/L interstitial water, with a median of 9 nL/L. It is believed that these chemicals are derived from low temperature biological and chemical processes on the sea floor(1).

URBAN/SUBURBAN: The concentration of isobutane in air is largely a result of vehicle emissions and will be particularly sensitive to factors such as the sampling duration, type of location, wind direction, and time of day(2). This is exemplified by the concentration of isobutane in air at Riverside, CA (n=6, afternoon with a heavy haze), 5.2-10.4 ppb, compared with 0.2 ppb on a clear morning(3). Ambient air concentrations for isobutane in the National Ambient Volatile Organic Compounds data base (n = 887): mean 5.706 ppb, median 3.290 ppb, 25th percentile 1.728 ppb, 75th percentile 6.213 ppb(1). The median concentration by type of site were (type, number of data points, concentration): remote, 6, 0.158 ppb; rural, 36, 0.340 ppb; suburban, 223, 3.817 ppb; urban, 546, 3.275 ppb; source dominated, 56, 4.204 ppb(1). 4-Hour simultaneous air sampling on 15 days over a 3 month period in the summer of 1987 of an industrial, urban and suburban site in Chicago resulted in mean levels of 4.42, 2.16, and 2.12 ug/cu m, respectively(4). The concentration of isobutane in Japan along the direction of air mass movement was 4.4 ppb in Yokahama, 1.3 ppb in Takasaki, and 1.5 ppb in Kuruzawa(5). The decrease in concentration was attributed to photooxidation.

URBAN/SUBURBAN: Concentrations of isobutane resulting from urban (n = 34, interstate (n = 35), and rural (n = 7) driving was assessed in Raleigh, NC in the summer of 1988 using a 1983 and a 1987 model cars. The concentration was measured at: (a) the driver's breathing zone, (b) a location mid-route 100-300 ft from the roadway, (c) the car roof, (d) the breathing zone of a pedestrian along the urban route. The concentration of isobutane in ug/cu m was (location, median, mean, maximum): (a) in-vehicle, 0.5, 9.1, 281.7; (b) fixed site, 1.7, 3.9, 43.4; (c) car exterior, 0.2, 8.5, 56.0; (d) sidewalk, 6.4, 8.0, 22.0. The in-vehicle median concentration was 9.0 ug/cu m for urban driving, 2.2 ug/cu m for rural driving, and below the detection limit for interstate driving(1).

URBAN/SUBURBAN: Results of year-round sampling (24-hr samples every 6th day) of ambient air for isobutane at a representative site in Washington DC (3/90-3/91): 92.96% frequency, max 3.8 ppb, median 1.26 ppb, mean 1.4 ppb, SD 0.85 ppb(1). Concentration of isobutane in 39 U.S. cities between 1984-1986 (n = 836) in ppbC: median 14.9, 25th percentile 8.5, 75th percentile 23.5, min 1.2, max 647(5). The concentration of isobutane in marine air is 0.11 ppb(2) and in Sydney, Australia (1979-80) and Hamburg, Germany (1986-87) 4.7 ppb(3) and 3.8 ppb(2), respectively. The concentration of isobutane in Vienna, Austria (n = 5, street with heavy traffic, 1.5 m above the ground) was 7.1 ppbC with a standard deviation of 3.9 ppbC(6). The results of air monitoring for isobutane at Harwell, England between Mar 1973 and Aug 1974 (n = 63) was 0.37-3.58 ppb with a mean of 1.2 ppb(4). Levels of isobutane ranged from 3 to 10 ug/cu m in the air of Southern Taiwan, in sampling conducted in December 1998 and May 1999(7).

URBAN/SUBURBAN: The isobutane content (ppbC%) of vehicle-related air samples from the 1990 Atlanta Ozone Precursor Monitoring Study were: roadway (n = 9), 1.12; airport (n = 11), 0.96; aircraft (n = 2), 0.525(2). The roadway samples were collected along a busy interstate during morning rush hour in August. Other roadway emission profiles for isobutane in wt% are: Chicago, 1.93; Lincoln Tunnel, 1.78; Atlanta roadway, 1.26(3). The Chicago profiles were taken on a confined parkway during rush hour. The ground level emissions 1 mi downwind from a refinery contained 1.85-22.42 wt%, mean 8.02 wt% isobutane(3). An earlier study reported refinery emission profiles as 1.64-5.63 wt% isobutane with a mean of 3.97 wt%(1).

For more Atmospheric Concentrations (Complete) data for Isobutane (7 total), please visit the HSDB record page.

The isobutane content of automobile-related sources in wt% (source, content): gasoline exhaust (noncatalyzed), 0.2%; gasoline exhaust (catalyzed), 0.5%; unburned gas, 0.8%; headspace vapors, 0.5%(1). The isobutane content (ppbC%) of sources from the 1990 Atlanta Ozone Precursor Monitoring Study were (source, content): whole gas (weighted avg all octanes), 0.599; whole gas 87 octane, 0.56; whole gas 89 octane, 0.60; whole gas 92/93 octane, 0.70; headspace gas 24 °C (all octanes), 5.13; headspace gas 32 °C (all octanes), 4.63(2). A similar study in the Chicago area yielded isobutane emission profiles (wt%) as (source, content): regular gas, 6.17; mid-grade gas, 6.51; premium gas 9.53; hot soak emissions, 4.98; cold start emissions, 1.84(3). Composition profiles for isobutane acquired during the Southern California Air Quality Study in wt% include (source, content): commercial natural gas, 2.10; geogenic natural gas, 5.90; liquified petroleum gas (LPG), 0.20; diurnal evaporative emissions, 1.76; hot soak evaporative emissions, 0.60; running loss evaporative emissions, 1.69; summer gas (liquid), 0.75; winter gas (liquid), 2.10; summer gas (vapor), 11.51; winter gas (vapor), 17.40(4). Vapors from two brands of alkylate-based petroleum contained 18.9 and 44.8% isobutane, respectively(5).

Isobutane was present in 6 of 10 insect sprays analyzed for VOC content by USEPA; when present it constituted 15.01 to 15.22 wt% of the product VOC(1). Isobutane was present in 5 of 16 window and glass cleaners analyzed for VOC content by USEPA; when present it constituted 0.82 to 45.47% (vol) of the product VOC(1). Isobutane was present in 2 of 3 personal spray deodorants analyzed for VOC content by USEPA; when present it constituted 77.23 and 96.94 wt% of the product VOC(1). Isobutane was present in 1 of 12 rug and upholstery cleaners analyzed for VOC content by USEPA; when present it constituted 96.77 wt% of the product VOC(1). A composite profile for window and glass cleaners developed by USEPA from composition data for 16 products contains 8.63 wt% isobutane(1). It was assumed that all products had an equal market share.

According to the 2016 TSCA Inventory Update Reporting data, 137 reporting facilities estimate the number of persons reasonably likely to be exposed during the manufacturing, processing, or use of isobutane in the United States may be as low as fewer than 10 workers and as high as 9,999 workers per plant; the data may be greatly underestimated due to confidential business information (CBI) or unknown values(1).

NIOSH (NOES Survey 1981-1983) has statistically estimated that 1,795,168 workers (556,159 of these are female) were potentially exposed to isobutane in the US(1). Occupational exposure to isobutane may occur through inhalation and dermal contact with this compound at workplaces where isobutane is produced or used. Monitoring and use data indicate the general population may be exposed to isobutane via inhalation of ambient air, particularly in areas with heavy vehicular traffic or dermal exposure to products such as gasoline and fuels, insect spray, window and glass cleaner, personal spray deodorant, and rug and upholstery cleaners containing isobutane(SRC).

Longterm personal samples for isobutane obtained at a high volume service station in eastern Pennsylvannia (n = 18) resulted in the following distribution profile (number, concentration): 1, not detected; 14, <0.1 ppm; and 3, 0.1-0.3 ppm(1). Air exposures were obtained for 55 components of gasoline measured by 8 petroleum companies for service stations attendants (n = 49), transport drivers (n = 49), and outside operators (n = 56) during the summer of 1984(2). The results for isobutane were (job category, mean concentration (standard deviation), percent positive): outside operator, 0.817 (1.523) mg/cu m, 75%; transport drivers, 2.867 (3.438) mg/cu m, 100%; service attendant, 8.811 (9.587) mg/cu m, 100%). Isobutane respectively constituted 4.3, 6.3 and 12.6% of the total hydrocarbon exposure for these three work groups. Exposure of service station attendants was significantly reduced when vapor recovery systems were present(2).

SRP: 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 air, soil or water; effects on animal, aquatic and plant life; and conformance with environmental and public health regulations. If it is possible or reasonable use an alternative chemical product with less inherent propensity for occupational harm/injury/toxicity or environmental contamination.

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.

Product: Burn in a chemical incinerator equipped with an afterburner and scrubber but exert extra care in igniting as this material is highly flammable. Offer surplus and non-recyclable solutions to a licensed disposal company. Contact a licensed professional waste disposal service to dispose of this material; Contaminated packaging: Dispose of as unused product.

Dissolve of mix the material with a combustible solvent and burn in a chemical incinerator equipped with an afterburner and scrubber. All federal, state, and local environmental regulations must be observed.

/GUIDE 115 GASES - FLAMMABLE (Including Refrigerated Liquids)/ Fire or Explosion: EXTREMELY FLAMMABLE. Will be easily ignited by heat, sparks or flames. Will form explosive mixtures with air. Vapors from liquefied gas are initially heavier than air and spread along ground. CAUTION: Hydrogen (UN1049), Deuterium (UN1957), Hydrogen, refrigerated liquid (UN1966) and Methane (UN1971) are lighter than air and will rise. Hydrogen and Deuterium fires are difficult to detect since they burn with an invisible flame. Use an alternate method of detection (thermal camera, broom handle, etc.) Vapors may travel to source of ignition and flash back. Cylinders exposed to fire may vent and release flammable gas through pressure relief devices. Containers may explode when heated. Ruptured cylinders may rocket.

/GUIDE 115 GASES - FLAMMABLE (Including Refrigerated Liquids)/ Health: Vapors may cause dizziness or asphyxiation without warning. Some may be irritating if inhaled at high concentrations. Contact with gas or liquefied gas may cause burns, severe injury and/or frostbite. Fire may produce irritating and/or toxic gases.

/GUIDE 115 GASES - FLAMMABLE (Including Refrigerated Liquids)/ Public Safety: CALL Emergency Response Telephone Number on Shipping Paper first. If Shipping Paper not available or no answer, refer to appropriate telephone number listed on the inside back cover. As an immediate precautionary measure, isolate spill or leak area for at least 100 meters (330 feet) in all directions. Keep unauthorized personnel away. Stay upwind, uphill and/or upstream. Many gases are heavier than air and will spread along ground and collect in low or confined areas (sewers, basements, tanks).

/GUIDE 115 GASES - FLAMMABLE (Including Refrigerated Liquids)/ Protective Clothing: Wear positive pressure self-contained breathing apparatus (SCBA). Structural firefighters' protective clothing will only provide limited protection. Always wear thermal protective clothing when handling refrigerated/cryogenic liquids.

For more DOT Emergency Guidelines (Complete) data for Isobutane (8 total), please visit the HSDB record page.

UN 1969; Isobutane

IMO 2.1; Isobutane

No person may /transport,/ offer or accept a hazardous material for transportation in commerce unless that person is registered in conformance ... and the hazardous material is properly classed, described, packaged, marked, labeled, and in condition for shipment as required or authorized by ... /the hazardous materials regulations (49 CFR 171-177)./

The International Maritime Dangerous Goods Code lays down basic principles for transporting hazardous chemicals. Detailed recommendations for individual substances and a number of recommendations for good practice are included in the classes dealing with such substances. A general index of technical names has also been compiled. This index should always be consulted when attempting to locate the appropriate procedures to be used when shipping any substance or article. Isobutane is included on the dangerous goods list.

The International Air Transport Association (IATA) Dangerous Goods Regulations are published by the IATA Dangerous Goods Board pursuant to IATA Resolutions 618 and 619 and constitute a manual of industry carrier regulations to be followed by all IATA Member airlines when transporting hazardous materials. Isobutane is included on the dangerous goods list.

Flammable Gas

Symbol: F+; R: 12; S: (2)-9-16; Note: C

UN Hazard Class: 2.1