Disclaimer: These guidelines were developed under contract using generally accepted secondary sources. The protocol used by the contractor for surveying these data sources was developed by the National Institute for Occupational Safety and Health (NIOSH), the Occupational Safety and Health Administration (OSHA), and the Department of Energy (DOE). The information contained in these guidelines is intended for reference purposes only. None of the agencies have conducted a comprehensive check of the information and data contained in these sources. It provides a summary of information about chemicals that workers may be exposed to in their workplaces. The secondary sources used for supplements 111 and 1V were published before 1992 and 1993, respectively, and for the remainder of the guidelines the secondary sources used were published before September 1996. This information may be superseded by new developments in the field of industrial hygiene. Therefore readers are advised to determine whether new information is available.

OCCUPATIONAL SAFETY AND HEALTH GUIDELINE FOR HEPTANE

INTRODUCTION

This guideline summarizes pertinent information about heptane for workers and employers as well as for physicians, industrial hygienists, and other occupational safety and health professionals who may need such information to conduct effective occupational safety and health programs. Recommendations may be superseded by new developments in these fields; readers are therefore advised to regard these recommendations as general guidelines and to determine whether new information is available.

SUBSTANCE IDENTIFICATION

* Formula

C(7)H(16)

* Structure

For Structure, see paper copy)CH(3)-CH(2)-CH(2)-CH(2)-CH(2)-CH(2)CH(3)

* Synonyms

Normal heptane, n-Heptane, dipropylmethane, Gettysolve-C, heptyl hydride, Skellysolve C

* Identifiers

1. CAS No.: 142-82-5

2. RTECS No.: MI7700000

3. DOT UN: 1206 27

4. DOT label: Flammable liquid

* Appearance and odor

Heptane is a colorless, flammable liquid with a mild, gasoline-like odor. An air odor threshold of 150 parts per million (ppm) parts of air has been reported for heptane.

CHEMICAL AND PHYSICAL PROPERTIES

* Physical data

1. Molecular weight: 100.2

2. Boiling point (at 760 mm Hg): 98.4 degrees C (209 degrees F)

3. Specific gravity (water = 1): 0.68 at 20 degrees C (68 degrees F)

4. Vapor density: 3.5

5. Melting point: -90.6 degrees C (-132 degrees F)

6. Vapor pressure at 22 degrees C (72 degrees F): 40 mm Hg

7. Solubility: Insoluble in water; soluble in alcohol, chloroform, and ether.

8. Evaporation rate: Data not available.

* Reactivity

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

2. Incompatibilities: Contact between heptane and strong oxidizing agents should be avoided.

3. Hazardous decomposition products: Toxic gases (such as carbon monoxide) may be released in a fire involving heptane.

4. Special precautions: None reported.

* Flammability

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

1. Flash point: -4 degrees C (25 degrees F) (closed cup)

2. Autoignition temperature: 222 degrees C (433 degrees F)

3. Flammable limits in air (percent by volume): Lower, 1.15; upper, 6.7

4. Extinguishant: For small fires use dry chemical, carbon dioxide, water spray, or regular foam. Use water spray, fog, or regular foam to fight large fires involving heptane.

Fires involving heptane 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 heptane 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. 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 heptane.

EXPOSURE LIMITS

* OSHA PEL

The current Occupational Safety and Health Administration (OSHA) permissible exposure limit (PEL) for heptane is 500 ppm (2000 milligrams per cubic meter (mg/m(3))) as an 8-hour time-weighted average (TWA) concentration [29 CFR 1910.1000, Table Z-1].

* NIOSH REL

The National Institute for Occupational Safety and Health (NIOSH) has established recommended exposure limits (RELs) for heptane of 85 ppm mg/m(3)) as a TWA for up to a 10-hour workday and a 40-hour workweek and 440 ppm (1,800 mg/m(3)) as a 15-minute ceiling limit[NIOSH 1992].

* ACGIH TLV

The American Conference of Governmental Industrial Hygienists (ACGIH) has assigned heptane a threshold limit value (TLV) of 400 ppm mg/m(3)) as a TWA for a normal 8-hour workday and a 40-hour workweek and a short-term exposure limit (STEL) of 500 ppm (2050 mg/m(3)) for periods not to exceed 15 minutes. Exposures at the STEL concentration should not be repeated more than four times a day and should be separated by intervals of at least 60 minutes [ACGIH 1994, p. 22].

* Rationale for Limits

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

The ACGIH limits are based on the risk of narcosis and irritation[ACGIH 1991, p. 734].

HEALTH HAZARD INFORMATION

Routes of Exposure

Exposure to heptane can occur through inhalation, ingestion, and eye or skin contact [Sittig 1991, p. 870].

* Summary of toxicology

1. Effects on Animals: Heptane is a depressant of the central nervous system, causing narcosis in animals exposed to concentrations above ppm for brief periods. The intravenous LD(50) in mice is 222 mg/kg; exposure to 15,000 to 20,000 ppm for 30 to 60 minutes caused death in mice [NIOSH 1991; Sax and Lewis 1989]. Exposure to 10,000 to ppm for 30 to 50 minutes caused narcosis in mice, and aminutes exposure to 32,000 ppm heptane caused irregular respiratory patterns in mice [ACGIH 1991; Hathaway et al. 1991]. Three out of four mice experienced respiratory arrest within 4 minutes when the concentrations reached 48,000 ppm [Hathaway et al. 1991].

2. Effects on Humans: Heptane causes narcosis and symptoms of nervous system effects in humans exposed to concentrations of 1,000 ppm and above. Men exposed to 1,000 ppm for 6 minutes reported experiencing vertigo, and exposure to 5,000 ppm for 4 minutes caused marked vertigo, incoordination, inappropriate hilarity, and inability to walk a straight line [Parmeggiani 1983; ACGIH 1991]. Workers exposed to ppm for 4 minutes also complained of nausea, loss of appetite, and a gasoline taste in the mouth that lasted for several hours after exposure; some exposed individuals experienced stupor lasting for 30 minutes [Parmeggiani 1983; ACGIH 1991]. In contact with the skin, heptane causes erythema, hyperemia, and blistering [Hathaway et al. Contact with the eye causes irritation [Genium 1987].

* Signs and symptoms of exposure

1. Acute exposure: Short-term exposure to heptane causes vertigo, nausea, incoordination, and hilarity and may cause stupor, loss of appetite, and a gasoline taste in the mouth. Skin contact with heptane causes redness and blistering. Eye irritation occurs at high airborne concentrations of heptane.

2. Chronic exposure: Repeated contact with the skin causes drying, cracking, and dermatitis. No systemic effects of exposure to heptane have been reported.

EMERGENCY MEDICAL PROCEDURES

* Emergency medical procedures: [NIOSH to supply]

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.

EXPOSURE SOURCES AND CONTROL METHODS

The following operations may involve heptane and lead to worker exposures to this substance:

* The manufacture and transportation of heptane Use as a carrier and penetrant solvent for adhesives; in azeotropic distillations, and in rubber tire manufacture Use as a reference fuel for testing gasoline engine knock and in pollution and combustion studies Use in organic chemical synthesis of toluene, alkylbenzenes, gasoline, rubber solvent naphtha, and petroleum solvents

Methods that are effective in controlling worker exposures to heptane, depending on the feasibility of implementation, are as follows:

* Process enclosure Local exhaust ventilation General dilution ventilation Personal protective equipment

Workers responding to a release or potential release of a hazardous substance must be protected as required by paragraph (q) of OSHA's Hazardous Waste Operations and Emergency Response Standard [29 CFR

Good sources of information about control methods are as follows:

1. ACGIH [1992]. Industrial ventilation--a manual of recommended practice. 21st ed. Cincinnati, OH: American Conference of Governmental Industrial Hygienists.

2. Burton DJ [1986]. Industrial ventilation--a self study companion. Cincinnati, OH: American Conference of Governmental Industrial Hygienists.

3. Alden JL, Kane JM [1982]. Design of industrial ventilation systems. New York, NY: Industrial Press, Inc.

4. Wadden RA, Scheff PA [1987]. Engineering design for control of workplace hazards. New York, NY: McGraw-Hill.

5. Plog BA [1988]. Fundamentals of industrial hygiene. Chicago, IL:

National Safety Council.

MEDICAL SURVEILLANCE

OSHA is currently developing requirements for medical surveillance. When these requirements are promulgated, readers should refer to them for additional information and to determine whether employers whose employees are exposed to heptane are required to implement medical surveillance procedures.

* Medical Screening

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, periodically during the term of employment, and (3) at the time of job transfer or termination.

* Preplacement medical evaluation

Before a worker is placed in a job with a potential for exposure to heptane, 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, liver, kidneys, and 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 heptane 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 conditionswhich should not be regarded as absolute contraindications to job placement) include a history and other findings consistent with diseases of the skin, respiratory system, liver, kidneys, and nervous system.

Periodic medical evaluations

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 heptane exposure. The interviews, examinations, and medical screening tests should focus on identifying the adverse effects of heptane on the skin, respiratory system, liver, kidneys, or 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.

* Termination medical evaluations

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

Biological monitoring involves sampling and analyzing body tissues or fluids to provide an index of exposure to a toxic substance or metabolite. No biological monitoring test acceptable for routine use has yet been developed for heptane.

WORKPLACE MONITORING AND MEASUREMENT

Determination of a worker's exposure to airborne heptane is made using a charcoal tube (100/50 mg sections, 20/40 mesh). Samples are collected at a maximum flow rate of 0.2 liter/minute (STEL or TWA) until a maximum collection volume of 3 liters (STEL) or 4 litersTWA) is reached. The sample is then treated with 99:1 carbon disulfide:dimethyl formamide or 95:5 methylene chloride:methanol. Analysis is conducted by gas chromatography using a flame ionization detector (GC/FID). This method is fully validated and is described in the OSHA Computerized Information System [OSHA 1994] and in NIOSH Method No. 1500 [NIOSH 1994b].

PERSONAL HYGIENE PROCEDURES

If heptane contacts the skin, workers should flush the affected areas immediately with plenty of water, followed by washing with soap andwater.

Clothing contaminated with heptane should be removed immediately, and provisions should be made for the safe removal of the chemical from the clothing. Persons laundering the clothes should be informed of the hazardous properties of heptane.

A worker who handles heptane should thoroughly wash hands, forearms, and face with soap and water before eating, using tobacco products, using toilet facilities, applying cosmetics, or taking medication.

Workers should not eat, drink, use tobacco products, apply cosmetics, or take medication in areas where heptane or a solution containing heptane is handled, processed, or stored.

STORAGE

Heptane should be stored in a cool, dry, well-ventilated area in tightly sealed containers that are labeled in accordance with OSHA's Hazard Communication Standard [29 CFR 1910.1200]. Containers of heptane should be protected from physical damage and ignition sources, and should be stored separately from strong oxidizers.

SPILLS AND LEAKS

In the event of a spill or leak involving heptane, persons not wearing protective equipment and clothing should be restricted from contaminated areas until cleanup has been completed. The following steps should be undertaken following a spill or leak:

1. Notify safety personnel.

2. Remove all sources of heat and ignition.

3. Ventilate potentially explosive atmospheres.

4. Do not touch the spilled material; stop the leak if it is possible to do so without risk.

5. Use non-sparking tools.

6. Water spray may be used to reduce vapors, but the spray may not prevent ignition in closed spaces.

7. For small liquid spills, take up with sand or other noncombustible absorbent material and place into closed containers for later disposal.

8. For large liquid spills, build dikes far ahead of the spill to contain the heptane for later reclamation or disposal.

SPECIAL REQUIREMENTS

U.S. Environmental Protection Agency (EPA) requirements for emergency planning, reportable quantities of hazardous releases, community right-to-know, and hazardous waste management may change over time. Users are therefore advised to determine periodically whether new information is available.

* Emergency planning requirements

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

* Reportable quantity requirements for hazardous releases

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 environmentincluding 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

Employers are not required by the emergency release notification provisions in 40 CFR Part 355.40 to notify the National Response Center of an accidental release of heptane; there is no reportable quantity for this substance.

* Community right-to-know requirements

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 heptane emitted or released from their facility annually.

* Hazardous waste management requirements

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 heptane 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.

RESPIRATORY PROTECTION

* Conditions for respirator use

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 heptane 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).

* Respiratory protection program

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].

PERSONAL PROTECTIVE EQUIPMENT

Workers should use appropriate personal protective clothing and

equipment that must be carefully selected, used, and maintained to beeffective in preventing skin contact with heptane. The selection ofthe appropriate personal protective equipment (PPE) (e.g., gloves, sleeves, encapsulating suits) should be based on the extent of theworker's potential exposure to heptane. The resistance of variousmaterials to permeation by heptane is shown below:

MaterialBreakthrough time (hr) Nitrile Rubber VitonH (PE/EVAL) Polyvinyl Alcohol Caution 1 to 4 Butyl Rubber Natural Rubber Neoprene Polyvinyl Chloride Not recommended, degradation may occur

To evaluate the use of these PPE materials with heptane, users should consult the best available performance data and manufacturers' recommendations. Significant differences have been demonstrated in the chemical resistance of generically similar PPE materials (e.g., butyl) produced by different manufacturers. In addition, the chemical resistance of a mixture may be significantly different from that of any of its neat components.

Any chemical-resistant clothing that is used should be periodically evaluated to determine its effectiveness in preventing dermal contact. Safety showers and eye wash stations should be located close to operations that involve heptane.

Splash-proof chemical safety goggles or face shields (20 to 30 cm long, minimum) should be worn during any operation in which a solvent, caustic, or other toxic substance may be splashed into the eyes.

In addition to the possible need for wearing protective outer apparel e.g., aprons, encapsulating suits), workers should wear work uniforms, coveralls, or similar full-body coverings that are laundered each day. Employers should provide lockers or other closed areas to store work and street clothing separately. Employers should collect work clothing at the end of each work shift and provide for its laundering. Laundry personnel should be informed about the potential hazards of handling contaminated clothing and instructed about measures to minimize their health risk.

Protective clothing should be kept free of oil and grease and should be inspected and maintained regularly to preserve its effectiveness.

Protective clothing may interfere with the body's heat dissipation, especially during hot weather or during work in hot or poorly ventilated work environments.

REFERENCES

ACGIH [1991]. Documentation of the threshold limit values and biological exposure indices. 6th ed. Cincinnati, OH: American Conference of Governmental Industrial Hygienists.

ACGIH [1994]. 1994-1995 Threshold limit values for chemical substances and physical agents and biological exposure indices. Cincinnati, OH: American Conference of Governmental Industrial Hygienists.

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