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 This information may be superseded by new developments in the field of industrial hygiene.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

INTRODUCTION

This guideline summarizes pertinent information about hexachloroethane 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 Recommendations may be superseded by new developments in these fields; readers are therefore advised to regard these recommendations as general guidelines and to determine whether new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(2)Cl(6)

* Structure

(For Structure, see paper copy)

* Synonyms

Perchloroethane, carbon hexachloride, carbon trichloride, HCE, Avlotane, ethane hexachloride, ethylene hexachloride, hexachloroethylene, Distopan, Egitol, Falkitol

* Identifiers

1. CAS No.: 67-72-1

2. RTECS No.: KI4025000

3. DOT NA: 9037 53

4. Specific DOT label: None

* Appearance and odor

Hexachloroethane takes the form of rhombic, triclinic, or cubic crystals that are colorless and have a camphor-like odor.

CHEMICAL AND PHYSICAL PROPERTIES

* Physical data

1. Molecular weight: 236.7

2. Boiling point (at 760 mm Hg): 186.8 degrees C (336.2 degrees F) (triple point; sublimes simultaneously)

3. Specific gravity (water = 1): 2.09 at 20 degrees C (68 degrees F)

4. Vapor density: 8.2

5 Melting point: 186.8 degrees C (336.2 degrees F) (triple point; sublimes simultaneously)

6. Vapor pressure at 20 degrees C (68 degrees F): 0.22 mm Hg

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

8. Evaporation rate: Not applicable.

* Reactivity

1. Conditions contributing to instability: None reported.

2. Incompatibilities: Contact between hexachloroethane and hot iron, zinc, or aluminum, strong oxidizers, or strong alkalies should be avoided. Dehalogenation reactions can produce spontaneously explosive chloroacetylene.

3. Hazardous decomposition products: Toxic gases and vapors (such as phosgene, chlorine, carbon tetrachloride, and tetrachloroethylene) may be released in a fire involving hexachloroethane.

4. Special precautions: None reported.

* Flammability

Hexachloroethane is a noncombustible solid.

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 hexachloroethane should be fought upwind from the maximum distance possible. Isolate the hazard area and deny access to unnecessary personnel. Firefighters should wear a full set of protective clothing and self-contained breathing apparatus when fighting fires involving hexachloroethane.

EXPOSURE LIMITS

* OSHA PEL

The current Occupational Safety and Health Administration (OSHA) permissible exposure limit (PEL) for hexachloroethane is 1 part per million (ppm) parts of air (10 milligrams per cubic meter (mg/m(3))) as an 8-hour time-weighted average (TWA) concentration. The OSHA PEL also bears a "Skin" notation, which indicates that the cutaneous route of exposure (including mucous membranes and eyes) contributes to overall exposure [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 hexachloroethane of 1 ppm (10 mg/m(3)) as a TWA for up to a 8-hour workday and a 40-hour workweek. NIOSH also assigns a "Skin" notation to hexachloroethane. NIOSH considers hexachloroethane a potential occupational carcinogen [NIOSH 1992].

* ACGIH TLV

The American Conference of Governmental Industrial Hygienists (ACGIH) has assigned hexachloroethane a threshold limit value (TLV) of 1 ppm (9.7 mg/m(3)) as a TWA for a normal 8-hour workday and a 40-hour workweek. The ACGIH also assigns a "Skin" notation to hexachloroethane. The ACGIH considers hexachloroethane a suspected human carcinogen [ACGIH 1994, p. 23].

* Rationale for Limits

The NIOSH limit is based on the risk of potential for cancer; liver tumors in animals [NIOSH 1992].

The ACGIH limit is based on the risk of liver and kidney injury [ACGIH 1991, p. 743].

HEALTH HAZARD INFORMATION

* Routes of Exposure

Exposure to hexachloroethane can occur through inhalation, ingestion, eye or skin contact, and absorption through the skin, eyes, and mucous membranes [Sittig 1991, p. 879].

* Summary of toxicology

1. Effects on Animals: Hexachloroethane is an eye irritant, a kidney toxin, and a central nervous system depressant and stimulant; it is also a liver carcinogen in mice [Hathaway et al. 1991]. The oral LD(50) in rats is 6,000 mg/kg and the 24-hour dermal LD(50) in rabbits is greater than 32,000 mg/kg [ACGIH 1991]. Rats exposed to 260 ppm of hexachloroethane for 8 hours did not demonstrate any ill effects, but rats exposed to 59,000 ppm for 8 hours developed toxic neurological symptoms and some died [Hathaway et al. 1991]. Rabbits that ingested 12 daily oral doses of 1,000 mg/kg had reduced body weights and showed damage to the liver and kidneys at autopsy. Rabbits fed 320 mg/kg for 12 daily oral doses also developed liver damage [Clayton and Clayton 1982]. Oral doses of 1 to 1.4 grams/kg in dogs produced weakness, staggering gait, and muscle twitching [ACGIH 1986]. Rats and dogs exposed to 260 ppm of hexachloroethane for 6 hours a day, 5 days a week for 6 weeks, developed serious neurological effects, and mortality was increased; no toxic effects occurred in rats, dogs, or guinea pigs exposed to 15 ppm on a similar schedule. Rats, dogs, and guinea pigs exposed to 48 ppm for the same length of time had irritation of the eyes and the respiratory tract, but did not show liver or kidney damage [Hathaway et al. 1991]. Male rats developed kidney and liver damage after being fed 20 to 80 mg/kg per day for 110 days, and female rats had evidence of mild liver damage after being fed 80 mg/kg per day for 110 days [Clayton and Clayton 1982]. Rats fed 423 or 212 mg/kg/day and mice fed 1,179 or 590 mg/kg/day for 5 days a week for 44 week developed kidney damage [ACGIH 1991]. No teratogenic effects were noted in the offspring of rats that were fed 50, 100, or 500 mg/kg hexachloroethane while pregnant, or in rats that were exposed to 15, 48, or 260 ppm of the vapor for 6 hours a day on days 6 through 16 of gestation [NLM 1992; Clayton and Clayton 1982]. Hexachloroethane instilled into the eyes of rabbits causes corneal injury, iritis, severe swelling, and discharge [Hathaway et al. 1991]. Mice that were gavaged with hexachloroethane in corn oil 5 days a week or 78 weeks showed a significant increase in hepatocellular carcinomas. Rats that were similarly gavaged for 5 days a week for 11 cycles, each consisting of 4 weeks of treatment and 1 week off, did not have a significant increase in tumors compared with controls but did show a few renal tumors of a type rarely seen [ACGIH 1991]. The International Agency for Research on Cancer has concluded that there is limited evidence the carcinogenicity of hexachloroethane in experimental animals [IARC 1987].

2. Effects on Humans: Few data are available on the effects of exposure to hexachloroethane in humans. No adverse effects were reported in workers who handled hexachloroethane during World War II. Workers exposed to the vapors of hot hexachloroethane have experienced excessive blinking, photophobia, tearing, and reddened eyes, but did not develop corneal injuries or permanent damage to their eyes [Grant 1986]. There have not been reports of chronic effects of industrial exposure to hexachloroethane [Hathaway et al. 1991].

* Signs and symptoms of exposure

1. Acute exposure: Exposure to hexachloroethane dust or vapors may cause blinking, tearing, reddening of the eyes, and photophobia. Exposure to the hot vapors or the dust of hexachloroethane may cause irritation of the skin and mucous membranes.

2. Chronic exposure: No signs or symptoms of chronic exposure to hexachloroethane 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 hexachloroethane and lead to worker exposures to this substance:

* The manufacture and transportation of hexachloroethane

* Use in the manufacture of pyrotechnics and smoke devices, to reduce ignitability of combustibles, and as an additive to fire extinguishers

* Use as a fumigant, insecticide, and fungicide and formerly used as an animal anthelmintic. Used as a moth repellant

* Use as a degassing agent in production of metals and alloys, principally aluminum and magnesium; used to remove impurities from molten metals and to recover metals from ores and smelting products

* Use in the production of polymers, for flameproofing, and to increase sensitivity to radiation crosslinking

* Use as a plasticizer for cellulose esters (as a camphor substitute); as a retarding agent in fermentation; as a solvent; and in submarine paint to prevent corrosion

Methods that are effective in controlling worker exposures to hexachloroethane, 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 hexachloroethane 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 hexachloroethane, 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 liver and kidneys.

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 hexachloroethane 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 liver and kidneys.

* 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 hexachloroethane exposure. The interviews, examinations, and medical screening tests should focus on identifying the adverse effects of hexachloroethane on the liver or kidneys. 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 hexachloroethane 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. No biological monitoring test acceptable for routine use has yet been developed for hexachloroethane.

WORKPLACE MONITORING AND MEASUREMENT

Determination of a worker's exposure to airborne hexachloroethane 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 until a maximum collection volume of 70 liters is reached. The sample is then treated with carbon disulfide. 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. 1003 [NIOSH 1994b].

PERSONAL HYGIENE PROCEDURES

If hexachloroethane contacts the skin, workers should immediately wash the affected areas with soap and water.

Clothing contaminated with hexachloroethane 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 hexachloroethane.

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

STORAGE

Hexachloroethane 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 hexachloroethane should be protected from physical damage and contact with hot metals, and should be stored separately from strong oxidizers, or strong alkalies.

SPILLS AND LEAKS

In the event of a spill or leak involving hexachloroethane, 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. Ventilate the area of spill or leak.

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

4. For small dry spills, use a clean shovel and place the material into a clean, dry container; cover and remove the container from the spill area.

5. For large liquid spills, build dikes far ahead of the spill to contain the hexachloroethane 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

Hexachloroethane 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

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 hexachloroethane is 100 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].

* 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 hexachloroethane per calendar year or otherwise use 10,000 pounds or more of hexachloroethane 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 hexachloroethane 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. Hexachloroethane is listed as a hazardous waste under RCRA and has been assigned EPA Hazardous Waste No. U131. It is approved for land disposal after treatment and only if the concentration of hexachloroethane in the waste or treatment residual does not exceed 28 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 hexachloroethane 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 hexachloroethane. 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 hexachloroethane. There are no published reports on the resistance of various materials to permeation by hexachloroethane.

To evaluate the use of PPE materials with hexachloroethane, 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 hexachloroethane.

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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