This guideline summarizes pertinent information about zinc chloride fume for workers and employers as well as for physicians, industrial hygienists, and other occupational safety and health professionals who may need such information to conduct effective occupational safety and health programs. Recommendations may be superseded by new developments in these fields; readers are therefore advised to regard these recommendations as general guidelines and to determine periodically whether new information is available.

SUBSTANCE IDENTIFICATION

* Formula

ZnCl(2)

* Structure

(For Structure, see paper copy)

* Synonyms

Butter of zinc fume, zinc dichloride fume, tinning flux fume3

* Identifiers

1. CAS 7646-85-7.

2. RTECS ZH1400000

3. DOT UN (for the solid): 2331 60

4. DOT label (for the solid): None

* Appearance and odor

Zinc chloride fume is a finely divided white powder; this substance is not combustible and has an acrid odor.

CHEMICAL AND PHYSICAL PROPERTIES

* Physical data

1. Molecular weight: 136.3.

2. Boiling point (760 torr): 732 degrees C (1350 degrees F) (for the solid).

3. Specific gravity (water = 1): 2.9 (for the solid) at 25 degrees C (77 degrees F).

4. Vapor density: Not applicable.

5. Melting point: 283 degrees C (541 degrees F) (for the solid).

6. Vapor pressure at 20 degrees C (68 degrees F): Not applicable.

7. Solubility: Soluble in water; very soluble in glycerol, alcohol, and ether.

8. Evaporation rate: Not applicable.

* Reactivity

1. Conditions contributing to instability: None.

2. Incompatibilities: Contact of zinc chloride fume with cyanides, sulfides, or potassium causes fires or explosions.

3. Hazardous decomposition products: Toxic gases and fumes (such as chlorine and zinc oxide) may be released in a fire involving zinc chloride fume.

4. Special precautions: Zinc chloride fume is corrosive to metals.

* Flammability

There is no National Fire Protection Association fire hazard rating for zinc chloride fume; this substance is not combustible.

1. Flash point: Not applicable.

2. Autoignition temperature: Not applicable.

3. Flammable limits in air: Not applicable.

4. Extinguishant: Zinc chloride fume is not combustible; use an extinguishant that is suitable for the material involved in the surrounding fire.

* Warning properties

No quantitative data are available on the odor threshold for zinc chloride fume. This substance is therefore considered to have inadequate odor warning properties.

* Eye irritation properties

No quantitative data are available on the eye irritation threshold for zinc chloride fume; however, this substance is known to be a severe eye irritant.

EXPOSURE LIMITS

The current Occupational Safety and Health Administration (OSHA) permissible exposure limit (PEL) for zinc chloride fume is 1 milligram per cubic meter (mg/m(3)) of air as an 8-hour time-weighted average (TWA) concentration and 2 mg/m(3) as a 15-minute TWA short-term exposure limit (STEL). A STEL is the maximum 15-minute concentration to which workers may be exposed during any 15-minute period of the working day [29 CFR 1910.1000, Table Z-1-A]. The National Institute for Occupational Safety and Health (NIOSH) has not issued a recommended exposure limit (REL) for zinc chloride fume; however, NIOSH concurs with the PEL established for this substance by OSHA [NIOSH 1988]. The American Conference of Governmental Industrial Hygienists (ACGIH) has assigned zinc chloride fume a threshold limit value (TLV) of 1 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 2 mg/m(3) for periods not to exceed 15 minutes [ACGIH 1988, p. 38]. The OSHA and ACGIH limits are based on the risk of respiratory irritation associated with exposure to zinc chloride fume.

HEALTH HAZARD INFORMATION

* Routes of Exposure

Exposure to zinc chloride fume can occur via inhalation and eye or skin contact.

* Summary of toxicology

1. Effects on Animals: No data exist on the acute or chronic toxicity of zinc chloride fume in experimental animals.

2. Effects on Humans: Zinc chloride fume is an irritant of the eyes, skin, mucous membranes, and lungs in humans. Exposure to a fume concentration of 120 mg/m(3) for 2 minutes produced irritation of the nose, throat, and chest; exposure to an 80-mg/m(3) concentration for 2 minutes caused nausea and occasional coughing [Sittig 1985, p. 939]. In a group of 70 workers exposed to an unspecified concentration of zinc chloride fume that had been accidentally released from a smoke generator, 10 developed severe pulmonary edema and died immediately or within a few hours of the exposure. Twenty-five of these workers developed bronchopneumonia, respiratory inflammation, conjunctivitis, irritation of the nose and throat, cough, shortness of breath, chest tightness and chest pain, nausea, and epigastric pain [Proctor, Hughes, and Fischman 1988, p. 514]. One fatal case of acute interstitial pulmonary fibrosis has been attributed to exposure to zinc chloride fume; this death occurred after a firefighter accidentally inhaled an unspecified amount of this substance. The patient complained of nausea, sore throat, chest tightness, and fever; within 18 days, he died of advanced pulmonary fibrosis and acute cor pulmonale [ACGIH 1986, p. 643; Proctor, Hughes, and Fischman 1988, p. 514]. In another case, a 19-year-old man complained of cough, abdominal cramps, and vomiting immediately and 24 hours after accidental exposure to zinc chloride fume. He developed shortness of breath, fever, and tachycardia and died 11 days later [ACGIH 1986, p. 643]. Contact of the skin with zinc chloride dust can cause primary dermatitis and chemical burns [Rom 1983, p. 503]. Dilute zinc chloride solutions cause no eye damage, but accidental splashes of concentrated solutions have caused permanent corneal opacities [Grant 1986, pp. 986-987].

* Signs and symptoms of exposure

1. Acute exposure: The signs and symptoms of acute exposure to zinc chloride fume include conjunctivitis, irritation of the nose and throat, hoarseness, cough, dyspnea, wheezing, rales, rhonchi, chest tightness and/or pain, nausea, vomiting, epigastric pain, listlessness, lightheadedness, and a metallic taste in the mouth.

2. Chronic exposure: No signs or symptoms of chronic exposure to zinc chloride fume have been reported.

EMERGENCY MEDICAL PROCEDURES

In the event of an emergency, remove the victim from further exposure, send for medical assistance, and initiate the following emergency procedures:

1. Eye exposure: If zinc chloride fume gets into the eyes, immediately flush the eyes with large amounts of water for a minimum of 15 minutes, lifting the lower and upper lids occasionally. Get medical attention as soon as possible.

2. Skin exposure: If zinc chloride fume contacts the skin, the contaminated skin should be flushed with water and should then be washed with soap and water. If irritation persists, get medical attention.

3. Inhalation: If zinc chloride fume is inhaled, move the victim at once to fresh air and get medical care as soon as possible. If the victim is not breathing, perform cardiopulmonary resuscitation; if breathing is difficult, give oxygen. Keep the victim warm and quiet until medical help arrives.

4. 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 and the location and proper use of emergency equipment.

EXPOSURE SOURCES AND CONTROL METHODS

The following operations may involve zinc chloride fume and lead to worker exposures to this substance:

• Etching metals and copper plating iron
• Soldering with zinc-chloride-containing fluxes
• Browning steel and galvanizing iron
• Arc welding of galvanized iron and steel pipes
• Use in vulcanizing and reclaiming processes in rubber manufacture
• Generation of smokescreens for military use

Methods that are effective in controlling worker exposures to zinc chloride fume, depending on the feasibility of implementation, are:

• Process enclosure
• Local exhaust ventilation
• General dilution ventilation
• Personal protective equipment

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

1. ACGIH [1986]. Industrial ventilation--a manual of recommended practice. 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 MONITORING

* 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, placement of workers in jobs that do not jeopardize their safety or health, 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 monitoring program is intended to supplement, not replace, such measures. To place workers effectively and to detect and control work-related health effects, medical evaluations should be performed (1) before job placement, (2) periodically during the period 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 zinc chloride fume, the examining physician should evaluate and document the worker's baseline health status with thorough medical, environmental, and occupational histories, a physical examination, and physiologic and laboratory tests appropriate for the anticipated occupational risks. These should concentrate on the function and integrity of the eyes, skin, and respiratory system. Medical monitoring for respiratory disease should be conducted using the principles and methods recommended by NIOSH and the American Thoracic Society.

A preplacement medical evaluation is recommended to assess an individual's suitability for employment at a specific job and to detect and assess medical conditions that may be aggravated or may result in increased risk when a worker is exposed to zinc chloride fume at or below the prescribed exposure limit. The examining physician should consider the probable frequency, intensity, and duration of exposure as well as the nature and degree of any applicable medical condition. Such conditions (which should not be regarded as absolute contraindications to job placement) include a history and other findings consistent with diseases of the eyes, skin, or respiratory tract.

* Periodic medical examination and biological monitoring

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 zinc chloride fume exposure. The interviews, examinations, and medical screening tests should focus on identifying the adverse effects of zinc chloride fume on the eyes, skin, or respiratory tract. Current health status should be compared with the baseline health status of the individual worker or with expected values for a suitable reference population.

Biological monitoring involves sampling and analyzing body tissues or fluids to provide an index of exposure to a toxic substance or metabolite. Zinc can be detected in the urine and blood of exposed individuals. However, no data are available to correlate airborne zinc chloride fume concentrations with blood or urinary zinc concentrations. Therefore, no biological monitoring test acceptable for routine use has yet been developed for zinc chloride fume.

* Medical examinations recommended at the time of job transfer or termination

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.

WORKPLACE MONITORING AND MEASUREMENT PROCEDURES

Determination of a worker's exposure to airborne zinc chloride fume is made using a mixed cellulose ester filter (0.8 micron). Samples are collected at a maximum flow rate of 2 liters per minute (TWA or STEL) until a maximum air volume of 960 liters (TWA) or 30 liters (STEL) is collected. The sample is then treated with deionized water to extract the zinc chloride fume. Analysis is conducted by atomic absorption spectroscopy. This method has a sampling and analytical error of 0.11 and is included in the OSHA Computerized Information System [OSHA 1987] and in Method 7030 of the NIOSH Manual of Analytical Methods, 3rd edition, Volume 2 [NIOSH 1984].

PERSONAL HYGIENE PROCEDURES

If zinc chloride fume contacts the skin, workers should flush the affected areas immediately with plenty of water for 15 minutes, followed by washing with soap and water [Genium MSDS 1986, No. 197].

Clothing contaminated with zinc chloride fume 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 zinc chloride fume, particularly its potential to be irritating to the skin and eyes.

Workers should not eat, drink, or use tobacco products in areas where zinc chloride fume is present [New Jersey Fact Sheet 1986, p. 3].

STORAGE

Not applicable.

RELEASES

In the event of a release involving zinc chloride fume, 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 release:

1. Notify safety personnel.

2. Use a vacuum or a wet method to clean up fume.

EMERGENCY PLANNING, COMMUNITY RIGHT-TO-KNOW, AND HAZARDOUS WASTE MANAGEMENT REQUIREMENTS

The Environmental Protection Agency's (EPA's) regulatory requirements for emergency planning, community right-to-know, and hazardous waste management may vary over time. Users are therefore advised to determine periodically whether new information is available. EPA has no requirements that apply specifically to the fume of zinc chloride; the information below applies to zinc chloride in solid form or in solution.

* Emergency planning requirements

Zinc chloride is not subject to EPA emergency planning requirements under the Superfund Amendments and Reauthorization Act (Title III).

* Reportable quantity requirements (releases of hazardous substances)

A hazardous substance release is defined by EPA as any spilling, pumping, pouring, emitting, emptying, discharging, injecting, escaping, leaching, dumping, or disposing into the environment (including the abandonment or discarding of containers) of hazardous substances. In the event of a release that is above the reportable quantity for that chemical, employers are required by the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) to notify the proper Federal authorities.

The reportable quantity for zinc chloride is 1,000 pounds. If an amount equal to or greater than this quantity is released within a 24-hour period, CERCLA [40 CFR Part 302.6] requires employers to notify the National Response Center IMMEDIATELY at (800) 424-8802 (in Washington, D.C. at (202) 426-2675).

* Community right-to-know requirements

Employers are not required by Section 313 of the Superfund Amendments and Reauthorization Act (SARA) to submit a Toxic Chemical Release Inventory form (Form R) to EPA reporting the amount of zinc 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), EPA has specifically listed many chemical wastes as hazardous. Although zinc chloride is not specifically listed as a hazardous waste under RCRA, EPA requires employers to treat any waste as hazardous if it exhibits any of the characteristics discussed above.

Providing more information about the removal and disposal of specific chemicals is beyond the scope of this guideline. EPA, U.S. Department of Transportation, 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 (202) 382-3000 (in Washington, D.C.) 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 zinc chloride fume 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 emergency situations. If the use of respirators is necessary, the only respirators permitted are those 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 (see Table 1), an evaluation of the worker's ability to perform the work while wearing a respirator, the regular training of personnel, 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 NIOSH Respirator Decision Logic [NIOSH 1987c] and the NIOSH Guide to Industrial Respiratory Protection [NIOSH 1987a].

Table 1 lists the respiratory protection that NIOSH recommends for workers exposed to zinc chloride fume. The recommended protection may vary over time because of changes in the exposure limit for zinc chloride fume or in respirator certification requirements. Users are therefore advised to determine periodically whether new information is available.

PERSONAL PROTECTIVE EQUIPMENT

Protective clothing should be worn to prevent skin contact with zinc chloride fume. Safety glasses, goggles, or faceshields should be worn during operations in which zinc chloride fume might contact the eyes. Eyewash fountains and emergency showers should be available within the immediate work area whenever the potential exists for eye or skin contact with zinc chloride fume. Contact lenses should not be worn if the potential exists for zinc chloride fume exposure.

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ACGIH [1988]. TLVs. Threshold limit values and biological exposure indices for 1988-1989. Cincinnati, OH: American Conference of Governmental Industrial Hygienists.

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Grant WM [1986]. Toxicology of the eye. 3rd edition. Springfield, IL: Charles C Thomas.

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