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 Recommendations may be superseded by new developments in these fields; readers are therefore advised to regard these recommendations as general guidelines and to determine whether new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

ZnCrO(4)

* Structure

(For Structure, see paper copy)

* Synonyms

Basic zinc chromate, zinc yellow, zinc chrome yellow, zinc chromate (VI) hydroxide, citron yellow, primrose yellow, C.I. pigment yellow 36, chromium zinc oxide

* Identifiers

1. CAS No.: 13530-65-9

2. RTECS No.: GB3290000

3. Specific DOT number: None

4. Specific DOT label: None

* Appearance and odor

Zinc chromate is a yellow, crystalline, odorless powder. It is a hexavalent chromium compound.

CHEMICAL AND PHYSICAL PROPERTIES

* Physical data

1. Molecular weight: 181.36

2. Boiling point: Data not available.

3. Specific gravity: 3.4 at 20 degrees C (68 degrees F)

4. Vapor density: Data not available.

5. Melting point: Data not available.

6. Vapor pressure: Data not available.

7. Solubility: Insoluble in cold water and acetone; decomposes in hot water; soluble in acids and liquid ammonia.

8. Evaporation rate: Data not available.

* Reactivity

1. Conditions contributing to instability: None reported.

2. Incompatibilities: Contact between zinc chromate and hydrazine results in explosive decomposition. Contact between zinc chromate and combustible, organic, or other oxidizable materials (such as paper, wood, sulfur, aluminum, and plastics), or strong oxidizers should be avoided.

3. Hazardous decomposition products: None reported.

4. Special precautions: None reported.

* Flammability

Zinc chromate is not combustible.

The National Fire Protection Association has not assigned a flammability rating to zinc chromate.

1. Flash point: Not applicable.

2. Autoignition temperature: Not applicable.

3. Flammable limits: Not applicable.

4. Extinguishant: Use an extinguishant that is suitable for the materials involved in the surrounding fire.

Fires involving zinc chromate 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 zinc chromate.

EXPOSURE LIMITS

* OSHA PEL

The current Occupational Safety and Health Administration (OSHA) permissible exposure limit (PEL) for zinc chromate (as chromic acid and chromates) is 0.1 milligram per cubic meter (mg/m(3)) of air as a ceiling limit. A worker's exposure to zinc chromate shall at no time exceed this ceiling level [29 CFR 1910.1000, Table Z-2].

* NIOSH REL

The National Institute for Occupational Safety and Health (NIOSH) has established a recommended exposure limit (REL) for zinc chromate of 0.001 mg/m(3) as a TWA for up to a 10-hour workday and a 40-hour workweek. NIOSH considers zinc chromate a potential human carcinogen [NIOSH 1992].

* ACGIH TLV

The American Conference of Governmental Industrial Hygienists (ACGIH) has assigned zinc chromate a threshold limit value (TLV) of 0.01 mg/m(3) as a TWA for a normal 8-hour workday and a 40-hour workweek. The ACGIH considers zinc chromate a confirmed human carcinogen (A1-substance) [ACGIH 1994, p. 36].

* Rationale for Limits

The NIOSH limit is based on the risk of lung cancer, skin ulcers, and lung irritation [NIOSH 1992].

The ACGIH limit is based on the risk of lung cancer [ACGIH 1991, p. 1752].

HEALTH HAZARD INFORMATION

* Routes of Exposure

Exposure to zinc chromate can occur through inhalation, ingestion, and eye or skin contact.

* Summary of toxicology

1. Effects on Animals: Zinc chromate has produced cancer in experimental animals following intrapleural and intrabronchial implantation [ACGIH 1991]. Bronchial carcinomas in rats were produced by intrabronchial implantation of zinc chromate [IARC 1987]. Injection-site sarcomas were produced in both rats and mice following intramuscular, intrapleural, and subcutaneous injections of zinc chromate [IARC 1987]. Zinc chromate is mutagenic in in vitro test systems [NIOSH 1989]. The International Agency for Research on Cancer (IARC) has concluded that there is sufficient evidence for the carcinogenicity of zinc chromate in experimental animals [IARC 1990].

2. Effects on Humans: Exposure to zinc chromate can cause irritation, tissue ulceration, and cancer in humans. Inhalation of dusts containing chromates causes irritation of the mucous membranes [Rom 1992]. Gastric distress, olfactory sense impairment, and the yellowing of teeth and tongue may also result from excessive exposures to chromates. If exposures are prolonged, ulcerations of the nasal mucosae may occur as well as possible septal perforations. Prolonged dermal contact may produce ulceration of the skin. The increased exposure that results from an ulcer may result in renal chromate toxicosis, liver failure or death [Rom 1992]. Ocular effects including eye lesions, conjunctivitis, and keratitis have been associated with exposures to chromates [Rom 1992]. Prolonged exposure to chromates can cause chronic bronchitis, rhinitis, or the growth of nasal mucosal polyps [Rom 1992]. Exposures may also lead to chemical pneumonitis. Chronic exposures to hexavalent chromium compounds can cause lung and gastrointestinal tract cancer including cancer of the esophagus, stomach, intestines, and pancreas [Rom 1992]. Of six studies that examined the association between exposure to zinc chromate and lung cancer, five were cohort studies and one was a proportionate mortality study [ACGIH 1991]. In four of the five cohort studies there were also exposures to lead chromates. All of the cohort studies demonstrated an association between exposure to chromates and lung cancer. It was noted that because of the compounded exposures with lead chromate it was not possible to separate out the effects caused by each individual chromate compound [ACGIH 1991]. IARC has concluded that there is sufficient evidence for the carcinogenicity of hexavalent chromium compounds to humans [IARC 1990].

* Signs and symptoms of exposure

1. Acute exposure: Acute exposure to zinc chromate can cause irritation of the eyes and mucous membranes and also skin rash, ulceration, and allergy.

2. Chronic exposure: Chronic exposure by direct contact with zinc chromate can cause lesions of the eyes, skin, and mucous membranes, nasal septal perforations, olfactory sense impairment, and yellowing of the teeth and tongue. Prolonged inhalation exposure can cause chronic bronchitis, rhinitis, and nasal mucosal polyps, and also lead to chemical pneumonitis. Symptoms include wheezing, pain during inspiration, and coughing. Additionally, chronic exposures to hexavalent chromium compounds have been reported to be associated with fever, gastric distress, and weight loss, and such exposures may also result in lung and gastrointestinal tract cancer including cancer of the esophagus, stomach, intestines, and pancreas.

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 zinc chromate and lead to worker exposures to this substance:

• The manufacture and transportation of zinc chromate
• Use in pigments, paints, varnishes, lacquers, and linoleum
• Use as a corrosion inhibitor for priming paints for metals

Methods that are effective in controlling worker exposures to zinc chromate, 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 zinc chromate 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 zinc chromate, 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 and respiratory system. Medical surveillance for respiratory disease should be conducted using the principles and methods recommended by the American Thoracic Society.

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 zinc chromate 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 or respiratory 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 zinc chromate exposure. The interviews, examinations, and medical screening tests should focus on identifying the adverse effects of zinc chromate on the skin or respiratory 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. Because occupational exposure to zinc chromate 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. Urine tests for chromium performed shortly after exposure can help indicate the level of exposure to zinc chromate. However, no biological monitoring test acceptable for routine use has yet been developed for zinc chromate.

WORKPLACE MONITORING AND MEASUREMENT

Determination of a worker's exposure to airborne zinc chromate is made using a low ash polyvinyl chloride (LAPVC) filter (5 microns). Samples are collected at a maximum flow rate of 2.0 liters/minute (ceiling) until a maximum collection volume of 960 liters is reached. The sample is then treated with carbonate/bicarbonate buffer. Analysis is conducted by polarographic analysis using differential pulse polarography. This method (OSHA # 103 for chromic acid and chromates) is described in the OSHA Computerized Information System [OSHA 1994] and is fully validated. NIOSH has published two similar methods (Method Nos. 7600 and 7604) for the determination of a worker's exposure to hexavalent chromium. Both methods use PVC filters for sample collection. Method # 7600 requires analysis by visible absorption spectrophotometry and method # 7604 utilizes ion chromatography with conductivity detection [NIOSH 1994].

PERSONAL HYGIENE PROCEDURES

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

Clothing contaminated with zinc chromate 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 chromate, particularly its potential for causing dermal irritation and skin ulcerations.

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

STORAGE

Zinc chromate should be stored in a regulated, marked area that is kept cool, dry, and well-ventilated and in tightly sealed containers that are labeled in accordance with OSHA's Hazard Communication Standard [29 CFR 1910.1200]. Containers of zinc chromate should be protected from physical damage and should be stored separately from hydrazine, combustible, organic, and other oxidizable materials (such as paper, wood, sulfur, aluminum, and plastics), and strong oxidizers.

SPILLS AND LEAKS

In the event of a spill or leak involving zinc chromate, 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. Avoid excessive dust generation.

3. Ventilate the affected area.

4. Carefully scoop the spilled material into a suitable container or use a vacuum equipped with a high-efficiency particulate air (HEPA) filter.

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

Zinc chromate 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 zinc chromate; 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 zinc chromate 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 zinc chromate 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 zinc chromate 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 and the NIOSH Guide to Industrial Respiratory Protection.

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 zinc chromate. 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 zinc chromate. There are no published reports on the resistance of various materials to permeation by zinc chromate.

To evaluate the use of PPE materials with zinc chromate, 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 zinc chromate.

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.

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.

ATS [1987]. Standardization of spirometry -- 1987 update. American Thoracic Society. Am Rev Respir Dis 136:1285-1296.

CFR. Code of Federal regulations. Washington, DC: U.S. Government Printing Office, Office of the Federal Register.

Genium [1988]. Material safety data sheet No. 237. Schenectady, NY: Genium Publishing Corporation.

IARC [1987]. IARC monographs on the evaluation of carcinogenic risk of chemicals to man. Supplement 7. Lyon, France: World Health Organization, International Agency for Research on Cancer.

IARC [1990]. IARC monographs on the evaluation of carcinogenic risk of chemicals to man. Volume 49. Lyon, France: World Health Organization, International Agency for Research on Cancer.

Lide DR [1993]. CRC handbook of chemistry and physics. 73rd ed. Boca Raton, FL: CRC Press, Inc.

Mickelsen RL, Hall RC [1987]. A breakthrough time comparison of nitrile and neoprene glove materials produced by different glove manufacturers. Am Ind Hyg Assoc J 48(11): 941-947.

Mickelsen RL, Hall RC, Chern RT, Myers JR [1991]. Evaluation of a simple weight-loss method for determining the permeation of organic liquids through rubber films. Am Ind Hyg Assoc J 52(10): 445-447.

NIOSH [1987a]. NIOSH guide to industrial respiratory protection. 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. 87-116.

NIOSH [1987b]. NIOSH respirator decision logic. 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. 87-108.

NIOSH [1989]. Registry of toxic effects of chemical substances: Zinc chromate. 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.

NIOSH [1994]. NIOSH manual of analytical methods. 4th ed. 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. 94-113.

NJDH [1986]. Hazardous substance fact sheet: Zinc chromate. Trenton, NJ: New Jersey Department of Health.

NLM [1989]. Hazardous substances data bank: Zinc chromate. Bethesda, MD: National Library of Medicine.

OSHA [1994]. Computerized information system. Washington, DC: U.S. Department of Labor, Occupational Safety and Health Administration.

Parmeggiani L [1983]. Encyclopedia of occupational health and safety. 3rd rev. ed. Geneva, Switzerland: International Labour Organisation.

Rom WN [1992]. Environmental and occupational medicine. 2nd ed. Boston, MA: Little, Brown and Company.

Sax NI, Lewis RJ [1989]. Dangerous properties of industrial materials. 7th ed. New York, NY: Van Nostrand Reinhold Company.

Sittig M [1991]. Handbook of toxic and hazardous chemicals. 3rd ed. Park Ridge, NJ: Noyes Publications.

USC. United States code. Washington. DC: U.S. Government Printing Office.