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 This information may be superseded by new developments in the field of industrial hygiene.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 METHYL ISOAMYL KETONE

INTRODUCTION

This guideline summarizes pertinent information about methyl isoamyl ketone 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 Recommendations may be superseded by new developments in these fields; readers are therefore advised to regard these recommendations as general guidelines and to determine periodically whether new information is available.

SUBSTANCE IDENTIFICATION

* Formula

C(7)H(14)O

* Structure

(For Structure, see paper copy)

* Synonyms

Isoamyl methyl ketone, 5-methyl-2-hexanone, isopentyl methyl ketone, 2-methyl-5-hexanone, MIAK

* Identifiers

1. CAS No.: 110-12-3

2. RTECS No.: MP3850000

3. DOT UN: 2302 26

4. DOT label: Flammable liquid

* Appearance and odor

Methyl isoamyl ketone is a colorless, clear liquid with a mild, pleasant ketone odor. An odor threshold of 0.012 part per million (ppm) parts of air has been reported.

CHEMICAL AND PHYSICAL PROPERTIES

* Physical data

1. Molecular weight: 114.2

2. Boiling point (at 760 mm Hg): 144 degrees C (291.2 degrees F)

3. Specific gravity (water = 1): 0.813 at 20 degrees C (68 degrees F)

4. Vapor density: 3.9

5. Melting point: -73.9 degrees C (-101 degrees F)

6. Vapor pressure at 20 degrees C (68 degrees F): 4.5 mm Hg

7. Solubility: Slightly soluble in water; miscible with most organic solvents, including alcohol and ether.

8. Evaporation rate (butyl acetate = 1): 0.5

* Reactivity

1. Conditions contributing to instability: Heat, sparks, and open flame.

2. Incompatibilities: Methyl isoamyl ketone is incompatible with oxidizing agents, reducing agents and aldehydes.

3. Hazardous decomposition products: Toxic gases (such as carbon monoxide and carbon dioxide) may be released in a fire involving methyl isoamyl ketone.

4. Special precautions: None reported.

* Flammability

The National Fire Protection Association has assigned a flammability rating of 2 (moderate fire hazard) to methyl isoamyl ketone.

1. Flash point: 43.3 degrees C (110 degrees F)

2. Autoignition temperature: 191 degrees C (375 degrees F)

3. Flammable limits in air (percent by volume, at 93 degrees C (200 degrees F)): Lower, 1.0; upper, 8.2

4. Extinguishant: For small fires use dry chemical, carbon dioxide, water spray, or alcohol-resistant foam. Use water spray, fog, or alcohol-resistant foam to fight large fires involving methyl isoamyl ketone.

Fires involving methyl isoamyl ketone should be fought upwind from the maximum distance possible. Keep unnecessary people away; isolate hazard area and deny entry. Emergency personnel should stay out of low areas. Vapors are an explosion hazard indoors, outdoors, or in sewers. Vapors may travel to a source of ignition and flash back. Containers of methyl isoamyl ketone 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 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. If a tank, rail car, or tank truck is involved in a fire, personnel should isolate an area of a half a mile in all directions. Firefighters should wear a full set of protective clothing and self-contained breathing apparatus when fighting fires involving methyl isoamyl ketone. Firefighters' protective clothing may provide limited protection against fires involving methyl isoamyl ketone.

EXPOSURE LIMITS

* OSHA PEL

The current Occupational Safety and Health Administration (OSHA) permissible exposure limit (PEL) for methyl isoamyl ketone is 100 parts per million (ppm) parts of air (475 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 a recommended exposure limit (REL) for methyl isoamyl ketone of 50 ppm (240 mg/m(3)) as a TWA for up to a 10-hour workday and a 40-hour workweek [NIOSH 1992].

* ACGIH TLV

The American Conference of Governmental Industrial Hygienists (ACGIH) has assigned methyl isoamyl ketone a threshold limit value (TLV) of 50 ppm (234 mg/m(3)) as a TWA for a normal 8-hour workday and a 40-hour workweek [ACGIH 1994, p. 26].

* Rationale for Limits

The NIOSH limit is based on the risk of irritation and liver, kidney, and nervous system effects [NIOSH 1992].

The ACGIH limit is based on analogy to the effects of exposure to methyl isobutyl ketone [ACGIH 1991, p. 1015].

HEALTH HAZARD INFORMATION

* Routes of Exposure

Exposure to methyl isoamyl ketone can occur through inhalation, ingestion, and eye or skin contact.

* Summary of toxicology

1. Effects on Animals: Methyl isoamyl ketone is an eye and upper respiratory tract irritant and has caused narcosis and renal damage in experimental animals [ACGIH 1991]. Methyl isoamyl ketone caused slight eye irritation when instilled into the eyes of rabbits [Hathaway et al. 1991]. Repeated dermal exposures to guinea pigs resulted in irritation [Hathaway et al. 1991; ACGIH 1991]. The oral LD(50) in rats is 3,200 mg/kg [NIOSH 1993]. The 6-hr LC(50) in rats is 3,813 ppm [ACGIH 1991]. Acute inhalation exposure caused narcosis, decreased respiratory rate, and signs of eye irritation in exposed animals [ACGIH 1991]. Rats exposed to 1,000 or 2,000 ppm methyl isoamyl ketone for 6 hours/day, 5 days/week for 96 days showed signs of upper respiratory and eye irritation was well as decreased response to noise; dose-dependent increased liver weight also occurred [ACGIH 1991]. No adverse effects were observed in rats exposed to 200 ppm on the same regimen [ACGIH 1991]. Rats exposed by inhalation to 2,000 ppm methyl isoamyl ketone 6 hours/day, 5 days/week for 2 weeks became lethargic and showed a decreased response to noise; increased liver and body weights were also observed. Renal hyaline degeneration and hyaline droplet formation occurred in male rats exposed to 1,000 or 2,000 ppm [ACGIH 1991].

2. Effects on Humans: No information was available on the effects of methyl isoamyl ketone on humans.

* Signs and symptoms of exposure

1. Acute exposure: No signs or symptoms of acute exposure to methyl isoamyl ketone have been reported in humans.

2. Chronic exposure: No signs or symptoms of chronic exposure to methyl isoamyl ketone have been reported in humans.

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 methyl isoamyl ketone and lead to worker exposures to this substance:

* The manufacture and transportation of methyl isoamyl ketone

* Use of methyl isoamyl ketone as a solvent for cellulose esters, acrylics, and vinyl copolymers

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

* Process enclosure

* Local exhaust ventilation

* General dilution ventilation

* Personal protective equipment

The following publications are good sources of information on control methods:

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 methyl isoamyl ketone 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, (2) 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 methyl isoamyl ketone, 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 eyes, skin, liver, kidneys, respiratory system, and central nervous system.

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

WORKPLACE MONITORING AND MEASUREMENT PROCEDURES

Determination of a worker's exposure to airborne methyl isoamyl ketone is made using a charcoal tube (100/50 mg sections, 20/40 mesh). Samples are collected at a maximum flow rate of 0.1 liter per minute until a maximum air volume of 10 liters is collected. The sample is then treated with a carbon disulfide. Analysis is conducted by gas chromatography using a flame ionization detector. This method is described in the OSHA Computerized Information System [OSHA 1994].

PERSONAL HYGIENE PROCEDURES

If methyl isoamyl ketone contacts the skin, workers should flush the affected areas immediately with plenty of water for 15 minutes, followed by washing with soap and water.

Clothing contaminated with methyl isoamyl ketone 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 methyl isoamyl ketone.

A worker who handles methyl isoamyl ketone 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 methyl isoamyl ketone or a solution containing methyl isoamyl ketone is handled, processed, or stored.

STORAGE

Methyl isoamyl ketone 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 methyl isoamyl ketone should be protected from physical damage, heat, sparks and open flames and should be stored separately from oxidizing agents, strong acids, alkalies, reducing agents, and aldehydes. Drums must be equipped with self-closing valves, pressure vacuum bungs, and flame arrestors. Only nonsparking tools may be used to handle methyl isoamyl ketone. To prevent static sparks, containers should be grounded and bonded for transfers. Because containers that formerly contained methyl isoamyl ketone may still hold product residues, they should be handled appropriately.

SPILLS AND LEAKS

In the event of a spill or leak involving methyl isoamyl ketone, 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. Do not touch the spilled material; stop the leak if it is possible to do so without risk.

2. Notify safety personnel.

3. Remove all sources of heat and ignition.

4. Ventilate the area of the spill or leak.

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

6. For large liquid spills, build dikes far ahead of the spill to contain the methyl isoamyl ketone 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

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

* Reportable quantity requirements for hazardous releases

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 methyl isoamyl ketone; 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 methyl isoamyl ketone 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 methyl isoamyl ketone 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 methyl isoamyl ketone 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 be effective in preventing skin contact with methyl isoamyl ketone. The selection of the appropriate personal protective equipment (PPE) (e.g., gloves, sleeves, encapsulating suits) should be based on the extent of the worker's potential exposure to methyl isoamyl ketone. No reports have been published on the resistance of various materials to permeation by methyl isoamyl ketone. However, one source recommends wearing rubber gloves, boots, aprons, and other protective clothing to prevent skin contact with methyl isoamyl ketone.

To evaluate the use of PPE materials with methyl isoamyl ketone, 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 methyl isoamyl ketone.

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.

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