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 This information may be superseded by new developments in the field of industrial hygiene.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 CHLOROFORM

INTRODUCTION

This guideline summarizes pertinent information about chloroform 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 Recommendations may be superseded by new developments in these fields; readers are therefore advised to regard these recommendations as general guidelines and to determine whether new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

CHCl(3)

* Structure

(For Structure, see paper copy)

* Synonyms

Trichloromethane, trichloroform, freon 20, COBEHN Spray-Cleaner solvent, formyl trichloride, methane trichloride, methenyl trichloride, methyl trichloride

* Identifiers

1. CAS No.: 67-66-3

2. RTECS No.: FS9100000

3. DOT UN: 1888 55

4. DOT label: Poison

* Appearance and odor

Chloroform is a clear, colorless, and mobile liquid with a pleasant, sweet odor. Air odor threshold concentrations ranging from 85 to 307 parts per million (ppm) parts of air have been reported for chloroform.

CHEMICAL AND PHYSICAL PROPERTIES

* Physical data

1. Molecular weight: 119.4

2. Boiling point (at 760 mm Hg): 62 degrees C (143 degrees F)

3. Specific gravity (water = 1): 1.48 at 20 degrees C (68 degrees F)

4. Vapor density: 4.1

5. Melting point: - 63.5 degrees C (- 82 degrees F)

6. Vapor pressure at 20 degrees C (68 degrees F): 160 mm Hg

7. Solubility: Slightly soluble in water; soluble in alcohol, ether, acetone, benzene, and ligroin.

8. Evaporation rate: Data not available.

* Reactivity

1. Conditions contributing to instability: Heat, air, and light.

2. Incompatibilities: Contact between chloroform and acetone, alkalis, and chemically active metals such as aluminum magnesium (in powder form), sodium, or potassium should be avoided. Chloroform is also incompatible with dinitrogen tetraoxide, fluorine, triisopropylphosphine, and solid potassium tert-butoxide.

3. Hazardous decomposition products: Toxic gases and vapors such as hydrogen chloride, chlorine, phosgene, and carbon monoxide may be released in a fire involving chloroform.

4. Special precautions: None reported.

* Flammability

The National Fire Protection Association has assigned a flammability rating of 0 (no fire hazard) to chloroform.

1. Flash point: Not applicable.

2. Autoignition temperature: Not applicable.

3. Flammable limits in air: Not applicable.

4. Extinguishant: Use an extinguishant that is suitable for the materials involved in the surrounding fire.

Fires involving chloroform should be fought upwind from the maximum distance possible. Keep unnecessary people away; isolate the hazard area and deny entry. Emergency personnel should stay out of low areas and ventilate closed spaces before entering. Containers of chloroform 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. Dike fire control water for later disposal; do not scatter this material. Firefighters should wear a full set of protective clothing and self-contained breathing apparatus when fighting fires involving chloroform.

EXPOSURE LIMITS

* OSHA PEL

The current Occupational Safety and Health Administration (OSHA) permissible exposure limit (PEL) for chloroform is 50 ppm (240 milligrams per cubic meter (mg/m(3))) as a ceiling limit. A worker's exposure to chloroform shall at no time exceed this ceiling level [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 chloroform of 2 ppm (9.78 mg/m(3)) as a 60-minute short-term exposure limit (STEL). NIOSH also considers chloroform a potential occupational carcinogen [NIOSH 1992].

* ACGIH TLV

The American Conference of Governmental Industrial Hygienists (ACGIH) has assigned chloroform a threshold limit value (TLV) of 10 ppm (49 mg/m(3)) as a TWA for a normal 8-hour workday and a 40-hour workweek. The ACGIH also considers chloroform a suspected human carcinogen (A2 substance) [ACGIH 1994, p. 16].

* Rationale for Limits

The NIOSH limit is based on the risk of central nervous system effects and potential for cancer; cancer of the liver and kidneys in animals [NIOSH 1992].

The ACGIH limit is based on the risk of cancer [ACGIH 1991, p. 290].

HEALTH HAZARD INFORMATION

* Routes of Exposure

Exposure to chloroform can occur through inhalation, ingestion, or contact with the skin or eyes [Sittig 1991].

* Summary of toxicology

1. Effects on Animals: Chloroform is a central nervous system depressant and carcinogen. Exposure of pregnant animals to chloroform increases the rate of fetal loss and malformation [Patnaik 1992]. The acute toxicity of chloroform is species-, strain-, sex-, and age-dependent. The oral LD(50) in young and older adult male Sprague-Dawley rats are 1,336 and 1,188 mg/kg; in 14-day-old rats of the same species, the oral LD(50) is 445 mg/kg [Clayton and Clayton 1982]. The dermal LD(50) in rabbits is greater than 20 gm/kg [NIOSH 1995]. Males of many mouse strains are susceptible to kidney damage, but not the females. Liver damage was the cause of death in rats and mice after acute exposures [Clayton and Clayton 1982]. Two chronic studies of rats show that chloroform-induced kidney and liver damage begins to appear at the 50 ppm exposure level and the severity of the exposure-related effects increases with dose [NLM 1995]. Chloroform was tested for carcinogenicity in three experiments in mice and one in rats. It produced liver cancer in mice, kidney tumors in male rats, and thyroid tumors in female rats [ACGIH 1991]. The International Agency for Research on Cancer (IARC) has concluded that chloroform is a carcinogen in experimental animals [IARC 1987]. Chloroform is both embryotoxic and teratogenic in experimental animals. Embryotoxic effects include decreased conception rate, fetal resorption, retarded fetal development, and small size [ACGIH 1991]. In another study, there was a significant incidence of cleft palate in the offspring of exposed pregnant mice [Clayton and Clayton 1982]. Chloroform crosses the placenta rapidly and enters the fetal circulation [NLM 1995]. Chloroform applied to rabbit skin caused redness and necrosis. Liquid chloroform instilled into rabbit eyes caused conjunctivitis and injury to the cornea [Clayton and Clayton 1982].

2. Effects on Humans: The toxicity of chloroform is well understood because of its long history of use as an anesthetic. Inhalation of 10,000 ppm of chloroform vapor produces clinical anesthesia. Inhalation of higher doses causes cardiovascular depression, with death resulting from ventricular fibrillation. Delayed death is associated with liver necrosis [ACGIH 1991]. Chronic inhalation of chloroform may cause psychiatric and neurological symptoms, including depression, hallucinations, and moodiness [NLM 1995]. In studies with human volunteers, exposure to 4,100 ppm causes serious disorientation, and 1,000 ppm caused dizziness, nausea, and after effects of fatigue and headache. Exposures of 20 to 70 ppm for undefined lengths of time caused less extreme, but still evident, effects on the central nervous system [Hathaway et al. 1991]. Liver enlargement was demonstrated in 17 of 68 workers exposed to chloroform at concentrations of 10 to 200 ppm for 1 to 4 years. Among other factors that increase the toxic effects of chloroform is ethanol [Hathaway et al. 1991]. As a result, alcoholics react more severely to exposure [Genium 1992]. Exposure to high concentrations of chloroform vapor causes redness and twitching of the eyes. Liquid chloroform splashed into the eye causes immediate burning, pain, and possible injury to the cornea. The eye returns to normal in 1 to 3 days [Grant 1986]. Application of chloroform to the skin causes burning, pain, redness, and vesiculation. Based on experimental animal studies, IARC has concluded that chloroform should be regarded as a cancer risk to humans. One study of people exposed to chloroform in their drinking water showed a correlation between chloroform concentration and rectal and bladder cancer [Hathaway et al. 1991].

* Signs and symptoms of exposure

1. Acute exposure: Inhalation of chloroform causes signs and symptoms of central nervous system depression. In the initial stages, there is a feeling of warmth of the face and body, then irritation of the mucous membranes, eyes, and skin, followed by excitation, loss of reflexes, sensation, and consciousness. The pupils dilate and have a reduced reaction to light. Prolonged inhalation causes paralysis, cardiac and respiratory failure, and death [Sax and Lewis 1989; Genium 1992]. Other symptoms may include digestive upset, mental dullness, and dizziness [Sittig 1991]. Chloroform vapors may irritate the eyes and skin. Chloroform liquid causes burning of the eye and transient corneal injury. Skin exposure results in burning and redness [NLM 1995]. Exposure of pregnant women to chloroform may result in fetal death or malformation based on animals studies [Clayton and Clayton 1982].

2. Chronic exposure: Chronic exposure to chloroform causes neurological and gastrointestinal signs and symptoms that resemble those of chronic alcoholism [Parmeggiani 1983]. These may include depression, liver enlargement, and gastrointestinal disorders [Sittig 1991]. Chronic skin exposure to chloroform may leave the skin red, dry, and cracking [Genium 1992].

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 chloroform and lead to worker exposures to this substance:

* The manufacture and transportation of chloroform

* Used in manufacture of fluorocarbons (especially chlorodifluoromethane) for refrigerants and aerosol propellants; used in fire extinguishers to lower the freezing temperature of carbon tetrachloride; used in manufacture of fluorocarbon resins, tribromomethane, plastics, and thermally stable polymers; used in the manufacture of artificial silk, floor polishes, dyes, and pesticides

* Used as an extractant solvent in manufacture of rubber, essential oils, sterols and alkaloids, guttapercha, resins, and in the recovery of fat from waste products

* Used in chemical analysis and assays; and in photographic processing

* Used as a general solvent of lacquers plastics, dyes, fats, greases, gums, oils, adhesives, and waxes, and in the rubber cleaning and dry cleaning industries

* Prior use as an anesthetic has been discontinued and uses in human drugs and cosmetics are now limited to use as a process solvent for final products that contain only residual amounts of chloroform

* Used as a fumigant for soil, a mildewicide for tobacco seedlings, a grain fumigant for various stored dry grains, and as an insecticide

Methods that are effective in controlling worker exposures to chloroform, 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 1910.120].

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 chloroform 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 chloroform, 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, liver, kidneys, heart, 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 chloroform 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, liver, kidneys, heart, 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 chloroform exposure. The interviews, examinations, and medical screening tests should focus on identifying the adverse effects of chloroform on the skin, liver, kidneys, heart, 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. Because occupational exposure to chloroform may cause diseases with prolonged latent periods, the need for medical surveillance may extend well beyond the termination of employment.

* Biological monitoring

Biological monitoring involves sampling and analyzing body tissues or fluids to provide an index of exposure to a toxic substance or metabolite. The presence of chloroform in the blood and in expired air is an indication of exposure, but data are insufficient to correlate blood or breath levels with indices of exposure. Therefore, no biological monitoring test acceptable for routine use has yet been developed for chloroform.

WORKPLACE MONITORING AND MEASUREMENT

Determination of a worker's exposure to airborne chloroform 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 (ceiling or TWA) until a maximum collection volume of 10 liters is reached (TWA) or for a minimum collection time of 15 minutes (ceiling). The sample is then treated with 99:1 carbon disulfide:dimethylformamide. Analysis is conducted by gas chromatography using a flame ionization detector (GC/FID). This method (OSHA 5) is described in the OSHA Computerized Information System [OSHA 1994] and is fully validated. NIOSH has published a similar method (Method No. 1003-for halogenated hydrocarbons) that can also be used to determine a worker's exposure to airborne chloroform [NIOSH 1994b].

PERSONAL HYGIENE PROCEDURES

If chloroform contacts the skin, workers should immediately wash the affected areas twice with soap and water and use cream or lotion to replace skin oils.

Clothing contaminated with chloroform 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 chloroform, particularly its potential for causing eye and skin irritation, and anesthesia when inhaled.

A worker who handles chloroform 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 chloroform or a solution containing chloroform is handled, processed, or stored.

STORAGE

Chloroform should be stored in a cool, dry, well-ventilated area (less than 30 degrees C (86 degrees F)) in tightly sealed containers that are labeled in accordance with OSHA's Hazard Communication Standard [29 CFR 1910.1200]. Chloroform decomposes at ordinary temperatures in sunlight in the absence of air, and in the dark in the presence of air. Containers of chloroform should be protected from physical damage, heat sources, direct sunlight, and moisture, and should be stored separately from acetone, alkalis, and chemically active metals such as aluminum magnesium (in powder form), sodium, or potassium, dinitrogen tetraoxide, fluorine, triisopropylphosphine, and solid potassium tert-butoxide. Do not use rubber or plastic hose or pipe to transfer chloroform. Empty containers of chloroform should be handled appropriately.

SPILLS AND LEAKS

In the event of a spill or leak involving chloroform, persons not wearing protective equipment and fully-encapsulating, vapor-protective 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 the area of the spill or leak.

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

5. Water spray may be used to reduce vapors.

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

7. For large liquid spills, build dikes far ahead of the spill to contain the chloroform 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

Employers owning or operating a facility at which there are 10,000 pounds or more of chloroform must comply with EPA's emergency planning requirements [40 CFR Part 355.30].

* 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 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 chloroform is 10 pounds. 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].

- Notify the emergency response commission of the State likely to be affected by the release [40 CFR 355.40].

- Notify the community emergency coordinator to the local emergency planning committee (or relevant local emergency response personnel) of any area likely to be affected by the release [40 CFR 355.40].

* Community right-to-know requirements

Employers who own or operate facilities in SIC codes 20 to 39 that employ 10 or more workers and that manufacture 25,000 pounds or more of chloroform per calendar year or otherwise use 10,000 pounds or more of chloroform per calendar year are required by EPA [40 CFR Part 372.30] to submit a Toxic Chemical Release Inventory form (Form R) to EPA reporting the amount of chloroform 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. Chloroform is listed as a hazardous waste under RCRA and has been assigned EPA Hazardous Waste No. U044. It is approved for land disposal after treatment and only if the concentration of chloroform in the waste or treatment residual does not exceed 5.6 mg/kg.

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 chloroform 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 chloroform. 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 chloroform. The resistance of various materials to permeation by chloroform is shown below:

(*) Not recommended, degradation may occur

To evaluate the use of these PPE materials with chloroform, 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 chloroform.

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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