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 This information may be superseded by new developments in the field of industrial hygiene.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

INTRODUCTION

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 Recommendations may be superseded by new developments in these fields; readers are therefore advised to regard these recommendations as general guidelines and to determine whether new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

CH(2)N(2)

* Structure

(For Structure, see paper copy)

* Synonyms

Amidocyanogen, carbamonitrile, carbimide, carbodiimide, cyanoamine, N-cyanoamine, cyanogenamide, cyanogen nitride, hydrogen cyanamide.

* Identifiers

1. CAS No.: 420-04-2.

2. RTECS No.: GS5950000.

3. Specific DOT number: None

4. Specific DOT label: None

* Appearance and odor

Cyanamide is a combustible, deliquescent, crystalline solid.

CHEMICAL AND PHYSICAL PROPERTIES

* Physical data

1. Molecular weight: 42.04

2. Boiling point (at 0.5 mm Hg): 83 degrees C (181.4 degrees F)

3. Specific gravity: 1.28 at 20 degrees C (68 degrees F)

4. Vapor density: 1.45

5. Melting point: 42 degrees C (107.6 degrees F)

6. Vapor pressure: Data not available.

7. Solubility: Very soluble in water; soluble in alcohols, phenols, amines, ethers, and ketones; slightly soluble in benzene and halogenated hydrocarbons; practically insoluble in cyclohexane.

8. Evaporation rate: Data not available.

* Reactivity

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

2. Incompatibilities: Contact of cyanamide with water, acids, or alkalies may cause a violent reaction at temperatures above 40 degrees C (104 degrees F). Mixture of cyanamide with 1,2-phenylenediamine salt may cause explosive polymerization.

3. Hazardous decomposition products: Toxic gases and vapors (such as cyanide, oxides of nitrogen, and carbon monoxide) may be released in a fire involving cyanamide.

4. Special precautions: Concentrated aqueous solutions of cyanamide may undergo explosive polymerization. Cyanamide attacks various metals.

* Flammability

The National Fire Protection Association has assigned a flammability rating of 1 (slight fire hazard) to cyanamide.

1. Flash point: 141 degrees C (285.8 degrees F)

2. Autoignition temperature: Data not available.

3. Flammable limits in air: Data not available.

4. Extinguishant: Use carbon dioxide, dry chemical, alcohol foam, or water spray to fight fires involving cyanamide.

Fires involving cyanamide should be fought upwind and from the maximum distance possible. Keep unnecessary people away; isolate hazard area ad deny entry. Emergency personnel should stay out of low areas and ventilate closed spaces before entering. Vapor explosion and poison hazards may occur indoors, outdoors, or in sewers. Vapors may travel to a source of ignition and flash back. Containers of cyanamide may explode in the heat of the fire and should be moved from the fire area if it is possible to do so safety. Firefighters should wear a full set of protective clothing, including a self-contained breathing apparatus, when fighting fires involving cyanamide.

EXPOSURE LIMITS

* OSHA PEL

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

* NIOSH REL

The National Institute for Occupational Safety and Health (NIOSH) has established a recommended exposure limit (REL) for cyanamide of 2 milligrams per cubic meter (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 cyanamide a threshold limit value (TLV) of 2 mg/m(3) as a TWA for a normal 8-hour workday and a 40-hour workweek [ACGIH 1994, p. 17].

* Rationale for Limits

The NIOSH limit is based on the risk of skin irritation [NIOSH 1992].

The ACGIH limit is based on the risk of irritation [ACGIH 1991, p. 348].

HEALTH HAZARD INFORMATION

* Routes of Exposure

Exposure to cyanamide can occur through inhalation, ingestion, and eye or skin contact [Sax and Lewis 1989].

* Summary of toxicology

1. Effects on Animals: Cyanamide causes irritation of the eyes and mucous membranes and inhibition of the enzyme aldehyde dehydrogenase. The oral LD(50) in rats is 125 mg/kg, and the dermal LD(50) in the same species is 84 mg/kg [NIOSH 1991]. The dermal LD(50) value in rabbits is 590 mg/kg [Sax and Lewis 1989]. Acutely poisoned animals show the following signs of parasympathetic overactivity: miosis, excessive salivation, tearing, and twitching [Grant 1986]. Instillation of 100 mg cyanamide into the eyes of rabbits caused severe irritation [ACGIH 1991]. Following contact with moist skin, cyanamide induced ulceration on experimental animals [Grant 1986]. In a two-generation study of reproduction-fertility in rats, oral daily doses of 2, 7, or 25 mg/kg cyanamide caused toxic effects in the dams at the highest dose level. The toxic effects reported include decreases in dam weight, number of corpora lutea, number of implantations, and number of neonates [Hathaway et al. 1991]. Cyanamide has been shown to inhibit liver aldehyde dehydrogenase in in-vivo tests in mice and rats [NLM 1990].

2. Effects on Humans: Cyanamide is caustic and irritating to the eyes, skin, and respiratory tract of humans. Systemic poisoning with cyanamide may cause parasympathetic overactivity. Effects after a single dose are usually transient (1/2 to 2 hours), and the estimated fatal dose in humans ranges from 40 to 50 gm [Gosselin 1984]. Cyanamide also inhibits the enzyme aldehyde dehydrogenase, which cause a disulfiram-like (Antabuse-like) reaction in individuals concomitantly exposed to alcohol. Calcium cyanamide has been used in aversion therapy for alcoholism [Gosselin 1984]. The accumulation of acetaldehyde in the body, which is caused by the interaction of cyanamide and alcohol, produces a syndrome of vasodilation characterized by facial flushing that spreads to the whole body, throbbing headache, nausea, vomiting, difficult breathing, sweating, thirst, chest pain, hypotension, weakness, vertigo, blurred vision, and confusion [Hathaway et al. 1991]. Contact with cyanamide in dust or liquid form causes severe irritation of the eyes and ulceration of moist skin [Grant 1986].

* Signs and symptoms of exposure

1. Acute exposure: The signs and symptoms of acute exposure to cyanamide include redness, swelling, and tearing of the eyes; a red, raised, itchy rash; skin and eye burns; constricted pupils; excessive salivation; and twitching. If cyanamide exposure is accompanied by the ingestion of alcohol, a reaction characterized by facial flushing, throbbing headache, nausea, vomiting, difficult breathing, sweating, thirst, chest pain, hypotension, weakness, vertigo, blurred vision, and confusion occurs [Parmeggiani 1983].

2. Chronic exposure: Chronic exposure to cyanamide may cause a skin allergy. Subsequent exposures to low levels of cyanamide may cause itching and a skin rash. Chronic exposure may also affect the liver and nervous system [NJDH 1986].

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 cyanamide and lead to worker exposures to this substance:

* The manufacture and transportation of cyanamide

* Use as a chemical intermediate in the manufacture of melamine

* Use in textiles as a crease-and fire-proofing agent

* Use in fumigants, metal cleaners, refining of ores, and production of synthetic rubber.

Methods that are effective in controlling worker exposures to cyanamide, 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 cyanamide 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 cyanamide, 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, and 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 cyanamide 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, and nervous system.

* Periodic medical evaluations

Occupational health interviews and physical examinations should be performed at regular intervals during the employment period, as mandated by any applicable Federal, State, or local standard. Where no standard exists and the hazard is minimal, evaluations should be conducted every 3 to 5 years or as frequently as recommended by an experienced occupational health physician. Additional examinations may be necessary if a worker develops symptoms attributable to cyanamide exposure. The interviews, examinations, and medical screening tests should focus on identifying the adverse effects of cyanamide on the skin, liver, and 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 cyanamide.

WORKPLACE MONITORING AND MEASUREMENT

Determination of a worker's exposure to airborne cyanamide is made using a coated XAD-2 tube (80/40 mg sections, 20/60 mesh), coating is 10 percent (w/w) 1-Naphthylisothiocyanate. Samples are collected at a recommended flow rate of 0.1 liter/minute until a recommended collection volume of 10 liters is reached. Analysis is conducted by high performance liquid chromatography (HPLC/UV). This method is not validated and is described in the OSHA Computerized Information System [OSHA 1994]. NIOSH recommends sampling using the total nuisance dust method (Method No. 0500) [NIOSH 1994].

PERSONAL HYGIENE PROCEDURES

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

Clothing contaminated with cyanamide 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 cyanamide, particularly its potential for causing irritation.

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

STORAGE

Cyanamide 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 cyanamide should be protected from physical damage and should be stored separately from water, acids, alkalies , or 1,2-phenylenediamine salt.

SPILLS AND LEAKS

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

1. Notify safety personnel.

2. Remove all sources of heat and ignition.

3. Ventilate potentially explosive atmospheres.

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

5. Use non-sparking tools.

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

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

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

9. For large liquid spills, build dikes far ahead of the spill to contain the cyanamide 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

Cyanamide 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].

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 cyanamide; 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 cyanamide 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 cyanamide 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 cyanamide 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 cyanamide. 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 cyanamide. There are no published reports on the resistance of various materials to permeation by cyanamide.

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

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

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

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

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

REFERENCES

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

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

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Gosselin RE, Smith RP, Hodge HC [1984]. Clinical toxicology of commercial products. 5th ed. Baltimore, MD: Williams & Wilkins.

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NIOSH [1991]. Registry of toxic effects of chemical substances: Cyanamide. Cincinnati, OH: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control, National Institute for Occupational Safety and Health, Division of Standards Development and Technology Transfer, Technical Information Branch.

NIOSH [1992]. Recommendations for occupational safety and health: Compendium of policy documents and statements. Cincinnati, OH: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control, National Institute for Occupational Safety and Health, DHHS (NIOSH) Publication No. 92-100.

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