ZnCl(2)

(For Structure, see paper copy)

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

1. CAS 7646-85-7.

2. RTECS ZH1400000

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

4. DOT label (for the solid): None

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

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.

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.

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

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

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.

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

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].

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.

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.

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.

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.

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.

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.

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

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).

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.

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.

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).

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.