Disclaimer: The information contained in these guidelines is intended for reference purposes only. It provides a summary of information about chemicals that workers may be exposed to in their workplaces. The information may be superseded by new developments in the field of industrial hygiene. Readers are therefore advised to regard these recomendations as general guidelines and to determine whether new information is available.

OCCUPATIONAL SAFETY AND HEALTH GUIDELINE FOR VINYLIDENE CHLORIDE

INTRODUCTION

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 Recommendations may be superseded by new developments in these fields; readers are therefore advised to regard these recommendations as general guidelines and to determine whether new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

* Structure

(For Structure, see paper copy)

* Synonyms

1,1-Dichloroethene; 1,1-dichloroethylene; sconatex; vinylidine chloride; vinylidene dichloride; VDC

* Identifiers

1. CAS No.: 75-35-4

2. RTECS No.: KV9275000

3. DOT UN: 1303 26

4. DOT label: Flammable liquid

* Appearance and odor

Vinylidene chloride is a colorless liquid with a mild, sweet, chloroform-like odor. Odor thresholds ranging from 190 to 500 parts per million (ppm) parts of air have been reported.

CHEMICAL AND PHYSICAL PROPERTIES

* Physical data

1. Molecular weight: 96.94

2. Boiling point (at 760 mm Hg): 31.7 degrees C (89.1 degrees F)

3. Specific gravity: 1.21 at 20 degrees C (68 degrees F)

4. Vapor density: 3.4

5. Melting point: -122.5 degrees C (-188.5 degrees F)

6. Vapor pressure at 25 degrees C (77 degrees F): 591 mm Hg

7. Solubility: Practically insoluble in water; soluble in most organic solvents.

8. Evaporation rate: Data not available.

* Reactivity

1. Conditions contributing to instability: Vinylidene chloride is a self-reactive material. If stored at temperatures between -40 degrees C (-40 degrees F) and 25 degrees C (77 degrees F) in air without an inhibitor, it will absorb oxygen and form a violently explosive peroxide.

2. Incompatibilities: Contact between vinylidene chloride and aluminum, sunlight, copper, oxidizers, chlorosulfonic acid, nitric acid, or oleum should be avoided to prevent violent reactions.

3. Hazardous decomposition products: Toxic gases such as chlorine, hydrogen chloride, phosgene, and formaldehyde may be released in a fire involving vinylidene chloride.

4. Special precautions: Store in tanks with nickel, glass, or baked phenolic linings at -10 degrees C (14 degrees F) and away from all polymerization initiators or under a nitrogen blanket.

* Flammability

The National Fire Protection Association has assigned a flammability rating of 4 (severe fire hazard) to vinylidene chloride.

1. Flash point: -28 degrees C (-19 degrees F) (closed cup)

2. Autoignition temperature: 570 degrees C (1058 degrees F)

3. Flammable limits in air (percent by volume): Lower, 5.6; upper, 11.4

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 vinylidene chloride.

Fires involving vinylidene chloride 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. 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 vinylidene chloride 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 vinylidene chloride.

EXPOSURE LIMITS

* OSHA PEL

The Occupational Safety and Health Administration (OSHA) does not currently regulate vinylidene chloride.

* NIOSH REL

The National Institute for Occupational Safety and Health (NIOSH) has established a recommended exposure limit (REL) for vinylidene chloride of the lowest feasible concentration (0.4 ppm, limit of quantitation). NIOSH also considers vinylidene chloride to be a potential human carcinogen [NIOSH 1992].

* ACGIH TLV

The American Conference of Governmental Industrial Hygienists (ACGIH) has assigned vinylidene chloride a threshold limit value (TLV) of 5 ppm (20 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 20 ppm (79 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. 36].

* Rationale for Limits

The NIOSH limit is based on the risk of potential cancer (liver and kidney tumors in animals) [NIOSH 1992].

The ACGIH limits are based on the risk of renal, hepatic, or other systemic toxicity [ACGIH 1991, p. 1714].

HEALTH HAZARD INFORMATION

* Routes of Exposure

Exposure to vinylidene chloride can occur through inhalation, ingestion, and eye or skin contact.

* Summary of toxicology

1. Effects on Animals: Vinylidene chloride is hepatotoxic, nephrotoxic, and mutagenic in experimental animals. In addition, it can affect the developing embryo and there is limited evidence of carcinogenic activity in experimental animals. Liquid vinylidene chloride causes transient eye irritation, but there is little effect on the skin if it is allowed to evaporate [ACGIH 1991]. The acute toxicity of vinylidene chloride is dependent on the state of the experimental animals [IARC 1986]. Its toxicity is higher in fasted animals than in fed animals, and the hepatic glutathione levels in the animals can affect the toxicity of vinylidene chloride. The oral LD(50) in rats is 200 mg/kg [NIOSH 1991]. The 4-hour LC(50) in rats is 6,350 ppm [NIOSH 1991]. In a six month inhalation study, rats, rabbits, guinea pigs, and dogs were exposed to vinylidene chloride concentrations of 25, 50, or 100 ppm for 8 hours/day, 5 days/week [Clayton and Clayton 1981; ACGIH 1991]. Signs of hepatic and renal degeneration were observed at all doses. In a three generation reproductive toxicity study, rats were administered vinylidene chloride at concentrations of 0, 50, 100, or 200 ppm in their drinking water [ACGIH 1991]. Although mild dose related hepatotoxicity was observed, no alterations in fertility, body weight or clinical signs could be detected. In a teratogenicity study, rats and rabbits were exposed by inhalation to 10, 80 or 160 ppm vinylidene chloride for 7 hours/day on gestation days 6 to 15 (rats) or 6 to 18 (rabbits) [ACGIH 1991; IARC 1986]. Increased resorptions were observed in rabbits exposed to 160 ppm, while increased incidences of skeletal malformations were observed in rats exposed to 80 and 160 ppm and rabbits exposed to 160 ppm. These exposures were toxic to the dams [ACGIH 1991; IARC 1986]. Vinylidene chloride was mutagenic in bacterial assays in the presence of metabolic activation; it also caused DNA damage in in vitro or in vivo assays. However, vinylidene chloride did not cause mutations in mammalian cells or chromosomal effects in in vitro or in vivo assays [ACGIH 1991; IARC 1986]. Vinylidene chloride was tested for carcinogenicity in mice and rats by oral administration and inhalation exposure, in mice by topical exposure, and in hamsters by inhalation [IARC 1986]. Studies in mice and rats by oral administration gave negative results. The inhalation studies resulted in no treatment-related neoplasms in either the rats or hamsters; in mice, the treatment related increases in the incidence of kidney adenocarcinomas were observed as were increases in mammary carcinomas in females and pulmonary adenomas in both male and female mice. In skin-painting studies conducted on female mice, vinylidene chloride showed activity as an initiator, but in a study of repeated skin application, no skin tumors occurred [IARC 1986]. IARC concluded that there is limited evidence for the carcinogenicity of vinylidene chloride to experimental animals [IARC 1986].

2. Effects on Humans: Vinylidene chloride is an eye irritant and can affect the central nervous system, liver, and kidneys in humans. Contact with the eyes can cause conjunctivitis and transient corneal injury [IARC 1986]. Workers exposed to high concentrations (4,000 ppm) of vinylidene chloride may show signs of central nervous system depression with accompanying signs of intoxication that may progress to unconsciousness [ACGIH 1991]. Repeated exposures to low concentrations are associated with liver and kidney dysfunction [NLM 1992]. IARC concluded that in the absence of adequate epidemiologic data, no evaluation of the carcinogenicity of vinylidene chloride to humans could be made [IARC 1986].

* Signs and symptoms of exposure

1. Acute exposure: Acute exposures to high concentrations of vinylidene chloride may cause eye irritation and the signs and symptoms characteristic to central nervous system depression including drowsiness, nausea, headache, unsteadiness, or unconsciousness.

2. Chronic exposure: No signs or symptoms of chronic exposure to vinylidene chloride have been reported in humans. However, chronic exposure may lead to liver or kidney damage and the signs and symptoms of such damage may be apparent.

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 vinylidene chloride and lead to worker exposures to this substance:

• The manufacture and transportation of vinylidene chloride
• Use in the production of copolymers with vinyl chloride or acrylonitrile
• Use in the production of 1,1,1-trichloroethane, refrigerant 142b, and other chemicals
• Use in latexes, polymer lacquers, binders, and in fiber production

Methods that are effective in controlling worker exposures to vinylidene chloride, 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 vinylidene chloride 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 vinylidene chloride, 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 vinylidene chloride 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 or 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 vinylidene chloride exposure. The interviews, examinations, and medical screening tests should focus on identifying the adverse effects of vinylidene chloride 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.

* 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 vinylidene chloride.

WORKPLACE MONITORING AND MEASUREMENT

Determination of a worker's exposure to airborne vinylidene chloride 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 3 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 (OSHA 19) is described in the OSHA Computerized Information System [OSHA 1994] and is fully validated. NIOSH has published a similar method (Method No. 1015) for the sampling and analysis of vinylidene chloride [NIOSH 1994b].

PERSONAL HYGIENE PROCEDURES

If vinylidene chloride contacts the skin, workers should immediately wash the affected areas with large amounts of soap and water.

Clothing contaminated with vinylidene chloride 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 vinylidene chloride.

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

STORAGE

Vinylidene chloride 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]. Store in tanks with nickel, glass, or baked phenolic linings at -10 degrees C (14 degrees F) and away from all polymerization initiators or under a nitrogen blanket. Containers of vinylidene chloride should be protected from physical damage and sunlight, and should be stored separately from aluminum, copper, oxidizers, chlorosulfonic acid, nitric acid, or oleum.

SPILLS AND LEAKS

In the event of a spill or leak involving vinylidene chloride, 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. Water spray may be used to reduce vapors, but the spray may not prevent ignition in closed spaces.

6. For small 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 vinylidene chloride 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

Vinylidene chloride 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 vinylidene chloride 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 vinylidene chloride per calendar year or otherwise use 10,000 pounds or more of vinylidene chloride 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 vinylidene chloride 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. Vinylidene chloride is listed as a hazardous waste under RCRA and has been assigned EPA Hazardous Waste No. U078. It is approved for land disposal after treatment and only if the concentration of vinylidene chloride in the waste or treatment residual does not exceed 33 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 vinylidene chloride 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 vinylidene chloride. 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 vinylidene chloride. The resistance of various materials to permeation by vinylidene chloride is shown below:

Material	Breakthrough time (hr)
responder	>4(*)
polyvinyl alcohol	>4
teflon	>4
butyl rubber	<1(**)
natural rubber	<1(**)
neoprene	<1(**)
nitrile rubber	<1(**)
polyvinyl chloride	<1(**)
viton	<1(**)
(*) Material has been estimated (but not tested) to provide resistance to permeation for at least four hours. (**) Not recommended, degradation may occur.

To evaluate the use of these materials with vinylidene chloride, 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 vinylidene chloride.

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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