C(6)H(14)

(For Structure, see paper copy)

Hexane, hexyl hydride, normal hexane, dipropyl, Gettysolve-B

1. CAS No.: 110-54-3

2. RTECS No.: MN9275000

3. DOT UN: 1208 27

4. DOT label: Flammable Liquid

N-hexane is a colorless, volatile liquid with a mild, gasoline-like odor. Commercial n-hexane is a mixture of n-hexane isomers with a small amount of cyclopentane, pentane, and heptane isomers. Benzene may be present in concentrations ranging from one to six percent. (Note: The preceding sentence was reviewed by OSHA for data quality purposes in 2008. (Reference Table) Benzene contamination existed in the past at the percentage levels previously stated in many petroleum distillates but has now generally been reduced to less than 0.1%. The manufacturers' MSDS prepared according the requirements of the Hazard Communication Standard should be consulted for specific product and�mixture hazard information.) Air odor threshold concentrations for n-hexane ranging from 65 to 130 parts per million (ppm) parts of air have been reported.

1. Molecular weight: 86.1

2. Boiling point (at 760 mm Hg): 68.9 degrees C (156 degrees F)

3. Specific gravity (water = 1): 0.66 at 20 degrees C (68 degrees F)

4. Vapor density: 2.97

5. Freezing point: -95 degrees C (-139 degrees F)

6. Vapor pressure at 20 degrees C (68 degrees F): 124 mm Hg

7. Solubility: Slightly solubility in water; soluble in alcohol, acetone, ether, and chloroform.

8. Evaporation rate: Data not available.

1. Conditions contributing to instability: Heat, sparks, or flame.

2. Incompatibilities: Contact of n-hexane with strong oxidizing agents should be avoided. Mixtures with dinitrogen tetraoxide may explode at 28 degrees C (82.4 degrees F).

3. Hazardous decomposition products: None reported.

4. Special precautions: None reported.

The National Fire Protection Association has assigned a flammability rating of 3 (severe fire hazard) to n-hexane.

Fires involving n-hexane should be fought upwind from the maximum distance possible. Keep unnecessary people away; isolate the hazard area and deny entry. Isolate the area for 1/2 mile in all directions if a tank, rail car, or tank truck is involved in the fire. For a massive fire in a cargo area, use unmanned hose holders or monitor nozzles; if this is impossible, withdraw from the area and let the fire burn. Emergency personnel should stay out of low areas and ventilate closed spaces before entering. Vapors may travel to a source of ignition and flash back. Vapors are an explosion and poison hazard indoors, outdoors, or in sewers. Containers of n-hexane may explode in the heat of the fire and should be moved from the fire area if it is possible to do so safely. If this is not possible, cool fire exposed containers from the sides with water until well after the fire is out. Do not get water inside the containers. Stay away from the ends of containers. Personnel should withdraw immediately if a rising sound from a venting safety device is heard or if there is discoloration of a container due to fire. Firefighters should wear a full set of protective clothing and self-contained breathing apparatus when fighting fires involving n-hexane.

The current Occupational Safety and Health Administration (OSHA) permissible exposure limit (PEL) for n-hexane is 500 ppm (1800 milligrams per cubic meter (mg/m(3))) as an 8-hour time-weighted average (TWA) concentration [29 CFR 1910.1000, Table Z-1].

The National Institute for Occupational Safety and Health (NIOSH) has established a recommended exposure limit (REL) for n-hexane of 50 ppm (180 mg/m(3)) as a TWA for up to a 10-hour workday and a 40-hour workweek [NIOSH 1992].

The American Conference of Governmental Industrial Hygienists (ACGIH) has assigned n-hexane a threshold limit value (TLV) of 50 ppm (176 mg/m(3)) as a TWA for a normal 8-hour workday and a 40-hour workweek [ACGIH 1994, p. 23].

The NIOSH limit is based on the risk of skin and nervous system effects [NIOSH 1992].

The ACGIH limit is based on the risk of nervous system effects [ACGIH 1991, p. 754].

Exposure to n-hexane can occur through inhalation, ingestion, and eye or skin contact [Sittig 1991, p. 889].

1. Effects on Animals: n-Hexane is a neurotoxin, a narcotic, and an irritant of the eyes, skin, and mucous membranes [Hathaway et al. 1991]. n-Hexane also causes productive and embryotoxic effects and is cytotoxic in mammalian and human test systems [NIOSH 1991]. The oral LD(50) in rats is 28,710 mg/kg, and the lowest lethal concentration in mice is 120 g/m(3) [NIOSH 1991]. Mice exposed to concentrations ranging from 1,000 to 2,000 ppm 24 hours/day for 6 days/week for 1 year developed atrophy and degeneration of hind leg muscle fibers [NLM 1992]. Mice exposed to 2,500 to 3,000 ppm n-hexane for 4 days developed liver enlargement within 24 hours of exposure onset [NLM 1992]. Rabbits exposed by inhalation to 3,000 ppm 8 hours/day for 8 days showed changes in the lungs, emphysema, necrosis of the bronchial epithelium, and atelectasis [NLM 1992]. Rats continuously exposed to 400 ppm developed anoxapathy, although intermittent exposure to 10,000 ppm 6 hours/day, 5 days/week for 13 weeks caused only mild paranodol axonal swelling [Hathaway et al. 1991]. The offspring of rats and mice exposed orally or by inhalation to n-hexane during gestation showed depressed weight gain after birth [Hathaway et al. 1991]. This agent also affects male and female reproductive capacity [Amdur 1991].

2. Effects on Humans: n-Hexane is a narcotic agent; an irritant to the eyes, upper respiratory tract, and skin; and a neurotoxin. Exposure of humans to 5,000 ppm n-hexane for 10 minutes causes marked vertigo; exposure to 1,500 ppm results in headache and slight nausea [Hathaway et al. 1991; Clayton and Clayton 1982]. In industrial settings, exposure to levels exceeding 1,000 ppm have been reported to cause mild symptoms of narcosis [Hathaway et al. 1991]. Eye and upper respiratory tract irritation has been reported to occur in humans exposed to 880 ppm n-hexane for 15 minutes [Clayton and Clayton 1982]. Dermal contact with n-hexane results in immediate irritation characterized by erythema and hyperemia; exposed subjects developed blisters 5 hours following dermal exposure to n-hexane [Hathaway et al. 1991]. The neuropathic toxicity of n-n-hexane in humans is well documented; cases of polyneuropathy have typically occurred in humans chronically exposed to levels of n-hexane ranging from 400 to 600 ppm, with occasional exposures up to 2,500 ppm [Hathaway et al. 1991]. Distal symmetrical motor weakness is common in most cases; however, in severely affected individuals, motor weakness may extend to the pelvic and high musculature [Rom 1992]. Nerve biopsies in affected individuals show swelling of the nerve and thinning of the myelin sheath. Functional neurological disturbances usually progress for a few months after termination of exposure. Although recovery is expected to occur within a year, clinical polyneuropathy has been reported in some cases to remain after 2 years [Hathaway et al. 1991]. Blurred vision, restricted visual field, and optic nerve atrophy has been reported to occur in association with n-hexane-induced polyneuropathy. Twelve of 15 individuals working with hexane for 12 years were found to have abnormal color discrimination [Grant 1986].

1. Acute exposure: Acute exposure to n-hexane may cause dizziness, confusion, nausea, headache, and irritation of the eyes, nose, throat, and skin [Hathaway et al. 1991].

2. Chronic exposure: Long-term exposure to n-hexane may cause disturbances in sensation, muscle weakness, and distal symmetric pain in the legs. Clinical changes include muscle atrophy, decreased muscle strength, footdrop, numbness, prickling, and a tingling sensation in the arms and legs. Neurological investigations reveal decreased motor nerve conduction, neurogenic damage and swelling of peripheral nerves with thinning of the myelin sheath. These symptoms may get worse for 2 to 3 months after cessation of exposure. Changes in vision may also be a symptom of chronic exposure to n-hexane [Hathaway et al. 1991].

5. Rescue: Remove an incapacitated worker from further exposure and implement appropriate emergency procedures (e.g., those listed on the Material Safety Data Sheet required by OSHA's Hazard Communication Standard [29 CFR 1910.1200]). All workers should be familiar with emergency procedures, the location and proper use of emergency equipment, and methods of protecting themselves during rescue operations.

* The manufacture and transportation of n-hexane

* Use as an extractant of agricultural products

* Use in manufacture of polyolefins and certain elastomers as a catalyst carrier and assist in controlling molecular weight by dropping polymer out of solution when a certain molecular weight is reached

* Use in motor fuel

* Use as an extractant of fatty acids and edible oils and fats

* Use as a solvent in glues, cements, and adhesives

* Use in determining the refractive index of materials

* Process enclosure

* Local exhaust ventilation

* General dilution ventilation

* Personal protective equipment

Workers who may be exposed to chemical hazards should be monitored in a systematic program of medical surveillance that is intended to prevent occupational injury and disease. The program should include education of employers and workers about work-related hazards, early detection of adverse health effects, and referral of workers for diagnosis and treatment. The occurrence of disease or other work-related adverse health effects should prompt immediate evaluation of primary preventive measures (e.g., industrial hygiene monitoring, engineering controls, and personal protective equipment). A medical surveillance program is intended to supplement, not replace, such measures. To detect and control work-related health effects, medical evaluations should be performed (1) before job placement, (2) periodically during the term of employment, and (3) at the time of job transfer or termination.

Before a worker is placed in a job with a potential for exposure to n-hexane, a licensed health care professional should evaluate and document the worker's baseline health status with thorough medical, environmental, and occupational histories, a physical examination, and physiologic and laboratory tests appropriate for the anticipated occupational risks. These should concentrate on the function and integrity of the skin, respiratory system, central nervous system, and peripheral nervous system. Medical surveillance for respiratory disease should be conducted using the principles and methods recommended by the American Thoracic Society.

A preplacement medical evaluation is recommended to assess medical conditions that may be aggravated or may result in increased risk when a worker is exposed to n-hexane at or below the prescribed exposure limit. The health care professional should consider the probable frequency, intensity, and duration of exposure as well as the nature and degree of any applicable medical condition. Such conditions (which should not be regarded as absolute contraindications to job placement) include a history and other findings consistent with diseases of the skin, respiratory system, central nervous system, and peripheral nervous system.

Occupational health interviews and physical examinations should be performed at regular intervals during the employment period, as mandated by any applicable Federal, State, or local standard. Where no standard exists and the hazard is minimal, evaluations should be conducted every 3 to 5 years or as frequently as recommended by an experienced occupational health physician. Additional examinations may be necessary if a worker develops symptoms attributable to n-hexane exposure. The interviews, examinations, and medical screening tests should focus on identifying the adverse effects of n-hexane on the skin, respiratory system, central nervous system, or peripheral nervous system. Current health status should be compared with the baseline health status of the individual worker or with expected values for a suitable reference population.

The medical, environmental, and occupational history interviews, the physical examination, and selected physiologic or laboratory tests that were conducted at the time of placement should be repeated at the time of job transfer or termination to determine the worker's medical status at the end of his or her employment. Any changes in the worker's health status should be compared with those expected for a suitable reference population.

Biological monitoring involves sampling and analyzing body tissues or fluids to provide an index of exposure to a toxic substance or metabolite. Exposure to n-hexane can be measured in the exhaled air (as n-hexane) or in urine as the 2,5-hexanedione. The biological exposure index for n-hexane in urine is 5 grams 2,5-hexanedione/gram creatinine.

n-Hexane is not subject to EPA emergency planning requirements under the Superfund Amendments and Reauthorization Act (SARA) (Title III) in 42 USC 11022.

A hazardous substance release is defined by EPA as any spilling, leaking, pumping, pouring, emitting, emptying, discharging, injecting, escaping, leaching, dumping, or disposing into the environment (including the abandonment or discarding of contaminated containers) of hazardous substances. In the event of a release that is above the reportable quantity for that chemical, employers are required to notify the proper Federal, State, and local authorities [40 CFR 355.40].

The reportable quantity of n-hexane is 1 pound. If an amount equal to or greater than this quantity is released within a 24-hour period in a manner that will expose persons outside the facility, employers are required to do the following:

- Notify the National Response Center immediately at (800) 424-8802 or at (202) 426-2675 in Washington, D.C. [40 CFR 302.6].

Employers are not required by EPA in 40 CFR Part 372.30 to submit a Toxic Chemical Release Inventory form (Form R) to EPA reporting the amount of n-hexane emitted or released from their facility annually.

EPA considers a waste to be hazardous if it exhibits any of the following characteristics: ignitability, corrosivity, reactivity, or toxicity as defined in 40 CFR 261.21-261.24. Under the Resource Conservation and Recovery Act (RCRA) [40 USC 6901 et seq.], EPA has specifically listed many chemical wastes as hazardous. Although n-hexane is not specifically listed as a hazardous waste under RCRA, EPA requires employers to treat waste as hazardous if it exhibits any of the characteristics discussed above.

Providing detailed information about the removal and disposal of specific chemicals is beyond the scope of this guideline. The U.S. Department of Transportation, EPA, and State and local regulations should be followed to ensure that removal, transport, and disposal of this substance are conducted in accordance with existing regulations. To be certain that chemical waste disposal meets EPA regulatory requirements, employers should address any questions to the RCRA hotline at (703) 412-9810 (in the Washington, D.C. area) or toll-free at (800) 424-9346 (outside Washington, D.C.). In addition, relevant State and local authorities should be contacted for information on any requirements they may have for the waste removal and disposal of this substance.

Good industrial hygiene practice requires that engineering controls be used where feasible to reduce workplace concentrations of hazardous materials to the prescribed exposure limit. However, some situations may require the use of respirators to control exposure. Respirators must be worn if the ambient concentration of n-hexane exceeds prescribed exposure limits. Respirators may be used (1) before engineering controls have been installed, (2) during work operations such as maintenance or repair activities that involve unknown exposures, (3) during operations that require entry into tanks or closed vessels, and (4) during emergencies. Workers should only use respirators that have been approved by NIOSH and the Mine Safety and Health Administration (MSHA).

Employers should institute a complete respiratory protection program that, at a minimum, complies with the requirements of OSHA's Respiratory Protection Standard [29 CFR 1910.134]. Such a program must include respirator selection, an evaluation of the worker's ability to perform the work while wearing a respirator, the regular training of personnel, respirator fit testing, periodic workplace monitoring, and regular respirator maintenance, inspection, and cleaning. The implementation of an adequate respiratory protection program (including selection of the correct respirator) requires that a knowledgeable person be in charge of the program and that the program be evaluated regularly. For additional information on the selection and use of respirators and on the medical screening of respirator users, consult the latest edition of the NIOSH Respirator Decision Logic [NIOSH 1987b] and the NIOSH Guide to Industrial Respiratory Protection [NIOSH 1987a].