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 This information may be superseded by new developments in the field of industrial hygiene.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 NICKEL, SOLUBLE COMPOUNDS
(As Ni)

INTRODUCTION

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 Recommendations may be superseded by new developments in these fields; readers are therefore advised to regard these recommendations as general guidelines and to determine whether new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

APPLICABILITY

The general guidelines contained in this document apply to all of the soluble nickel compounds. Examples of such compounds include nickel chloride, nickel nitrate, nickel sulfate, and nickel acetate. For illustrative purposes, the physical and chemical properties of several soluble nickel compounds are presented below.

SUBSTANCE IDENTIFICATION

Nickel chloride

* Formula

NiCl(2)

* Structure

(For Structure, see paper copy)

* Synonyms

Nickelous chloride, nickel (II) chloride, nickel dichloride, nickel (2+) chloride

* Identifiers

1. CAS No.: 7718-54-9

2. RTECS No.: QR6475000

3. DOT UN: 9139

4. Specific DOT label: None

* Appearance and odor

Nickel chloride is an odorless, deliquescent, golden yellow powder or brown solid in the form of scales.

CHEMICAL AND PHYSICAL PROPERTIES

* Physical data

1. Molecular weight: 129.61

2. Boiling point: Sublimes.

3. Specific gravity (water = 1): 3.55 at 20 degrees C (68 degrees F)

4. Vapor density: Data not available.

5. Melting point: 1001degreesC (1833.8 degrees F)

6. Vapor pressure at 20degreesC (68 degrees F): Essentially zero

7. Solubility: Soluble in water, alcohol, and ammonium hydroxide; insoluble in ammonia.

8. Evaporation rate: Not applicable.

Nickel nitrate

* Formula

N(2)NiO(6)

* Structure

(For Structure, see paper copy)

* Synonyms

Nickelous nitrate, nickel (II) nitrate, nickel dinitrate, nickel (2+) nitrate

* Identifiers

1. CAS No.: 13138-45-9

2. RTECS No.: QR7200000

3. DOT UN: 2725 35

4. DOT label: Oxidizer

* Appearance and odor

Nickel nitrate is an odorless, green, deliquescent powder or crystalline substance. It is also commonly in the hexahydrate form.

CHEMICAL AND PHYSICAL PROPERTIES

* Physical data

1. Molecular weight: 182.72

2. Boiling point: 137 degrees C (278.6 degrees F)-hexahydrate form

3. Specific gravity (water = 1): 2.05 at 20 degrees C (68 degrees F) -hexahydrate form

4. Vapor density: Data not available.

5. Melting point: 56.7 degrees C (134.1 degrees F)-hexahydrate form

6. Vapor pressure: Data not available.

7. Solubility: Soluble in water, alcohol, and ammonium hydroxide.

8. Evaporation rate: Not applicable.

Nickel sulfate

* Formula

NiSO(4)

* Structure

(For Structure, see paper copy)

* Synonyms

Nickelous sulfate, nickel (II) sulfate, nickel disulfate, nickel (2+) sulfate

* Identifiers

1. CAS No.: 7786-81-4

2. RTECS No.: QR9350000

3. DOT UN: 9141

4. Specific DOT label: None

* Appearance and odor

Nickel sulfate is an odorless, crystalline substance that commonly occurs in the form of hexahydrate or heptahydrate crystals. The anhydrous material is a yellow to green color, hexahydrate appears as a blue to pale-green, and the heptahydrate is green in color.

CHEMICAL AND PHYSICAL PROPERTIES

* Physical data

1. Molecular weight: 154.77

2. Boiling point: Decomposes.

3. Specific gravity (water = 1): 3.68 at 20 degrees C (68 degrees F) -anhydrous form

4. Vapor density: Data not available.

5. Melting point: 840 degrees C (1544 degrees F) losses SO(3)

6. Vapor pressure: Data not available.

7. Solubility: All forms of nickel sulfate are soluble in water; the hexa- and heptahydrate forms are also soluble in alcohol; anhydrous nickel sulfate is insoluble in alcohol, acetone, and ether.

8. Evaporation rate: Not applicable.

* Reactivity

1. Conditions contributing to instability: Conditions contributing to instability may vary for specific soluble nickel compounds. The compounds listed as examples are considered stable. Nickel nitrate is an oxidizer and therefore, increases the flammability of other combustible materials. Mixtures of nickel chloride and potassium will explode on impact.

2. Incompatibilities: Incompatibilities may vary for specific soluble nickel compounds. Contact between nickel chloride and strong acids, potassium, or sulfur should be avoided. Contact between nickel nitrate and acids, sulfur, combustibles, organics, or other readily oxidizable materials should be avoided. Contact between nickel sulfate and strong acids, wood, or other combustible materials should be avoided.

3. Hazardous decomposition products: Toxic gases and fumes such as the oxides of nickel, sulfur, chlorine, or nitrogen may be released in a fire involving soluble nickel compounds. Thermal degradation products may vary for specific soluble nickel compounds.

4. Special precautions: Special precautions may vary for specific soluble nickel compounds. None were reported for the example soluble nickel compounds.

* Flammability

The example soluble nickel compounds are not combustible.

The National Fire Protection Association has assigned a flammability rating of 0 (minimal fire hazard) to nickel nitrate. The NFPA has not assigned the other example soluble nickel compounds flammability ratings.

1. Flash point: Not applicable.

2. Autoignition temperature: Not applicable.

3. Flammable limits in air: Not applicable.

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

Fires involving soluble nickel compounds 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 soluble nickel compounds.

EXPOSURE LIMITS

* OSHA PEL

The current Occupational Safety and Health Administration (OSHA) permissible exposure limit (PEL) for soluble nickel compounds (as Ni) is 1 milligram per cubic meter (mg/m(3)) of air as an 8-hour time-weighted average (TWA) concentration [29 CFR 1910.1000, Table Z-1].

* NIOSH REL

The National Institute for Occupational Safety and Health (NIOSH) has established a recommended exposure limit (REL) for soluble nickel compounds (as Ni) of 0.015 mg/m(3) as a TWA for up to a 10-hour workday and a 40-hour workweek. NIOSH also considers these compounds potential occupational carcinogens [NIOSH 1992].

* ACGIH TLV

The American Conference of Governmental Industrial Hygienists (ACGIH) has assigned soluble nickel compounds (as Ni) a threshold limit value (TLV) of 0.1 mg/m(3) as a TWA for a normal 8-hour workday and a 40-hour workweek and indicates that these substances have been identified as suspected or confirmed human carcinogens [ACGIH 1994, p. 27].

* Rationale for Limits

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

The ACGIH limit is based on the risk of respiratory cancer [ACGIH 1991, p. 1073].

HEALTH HAZARD INFORMATION

* Routes of Exposure

Exposure to soluble nickel compounds can occur through inhalation, ingestion, and eye or skin contact.

* Summary of toxicology

1. Effects on Animals: Nickel is toxic to the kidneys, cardiovascular system, respiratory system and reproductive system and is also a sensitizing agent in experimental animals. The oral LD(50)s for nickel salts in rats are 105, 350, and 1,620 mg/kg for nickel chloride, nickel acetate tetrahydrate, and nickel nitrate hexahydrate, respectively [NIOSH 1995; Sax and Lewis 1989]. Oral administration of nickel salts in dogs causes acute gastrointestinal tract irritation with vomiting and diarrhea [Clayton and Clayton 1982]. Rats administered nickel sulfate for 90 days had focal necrosis of the proximal convoluted tubules of the kidneys and marked necrosis of the myocardium [Clayton and Clayton 1982]. Exposure of experimental animals to soluble nickel at concentrations ranging from 0.1 and 1 mg/m(3) causes lung damage [ACGIH 1991]. Rats exposed to nickel sulfate at 1.6 mg Ni/m(3) had degenerative changes in the testes and epididymis [ACGIH 1991]. In addition, exposure of pregnant animals is associated with delayed embryonic development, increased resorptions and an increase in structural malformations [Hathaway et al 1991]. Animal studies suggest that most nickel salts are noncarcinogenic [Hathaway et al. 1991]. Nickel compounds are frequently positive in in vitro tests of mutagenicity, although the results of in vivo tests are inconsistent [ACGIH 1991].

2. Effects on Humans: Soluble nickel compounds can affect the cardiovascular system, kidneys, and central nervous system in humans [Gosselin 1984]. They are potent sensitizing agents and may also be carcinogenic in humans. Systemic poisoning is rare in humans [Gosselin 1984]. Although nickel compounds are not absorbed in sufficient concentration through the skin to cause systemic toxicity, they are capable of inducing contact dermatitis in sensitized individuals [ACGIH 1991; Hathaway et al. 1991]. Nickel is relatively non-toxic by ingestion [NLM 1995]. Positive findings in many epidemiology studies attest to the potential human carcinogenicity of nickel compounds. IARC has concluded that there is sufficient evidence that nickel and some of its compounds can cause cancer of the nasal cavity and lung, and possibly of the larynx in refinery workers [IARC 1987].

* Signs and symptoms of exposure

1. Acute exposure: Acute exposure to soluble nickel compounds by skin contact may result in an allergic rash, "nickel itch" characterized by itching and skin eruptions of the hands and arms, most frequently when the skin is moist [Hathaway et al. 1991]. Sensitized individuals may also experience asthma. Once acquired, nickel sensitivity usually persists [NLM 1995]. Acute exposure to large amounts of soluble nickel compounds by ingestion may result in nausea, vomiting, or diarrhea [Gosselin 1984].

2. Chronic exposure: Chronic exposure to soluble nickel compounds may result in severe allergic reactions of the skin, eyes, or respiratory tract. Eczema and fungal infections of the skin, loss of smell, difficult or painful breathing, cough, nasal inflammation, asthma, or bronchitis may also be evident [Rom 1992]. Skin contact may also result in pigmented or de-pigmented plaques [Hathaway et al. 1991].

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 soluble nickel compounds and lead to worker exposures to this substance:

* The manufacture and transportation of soluble nickel compounds

* Use as catalysts, in nickel plating, as mordants in dyeing and printing textiles, in coatings, in ceramics, in corrosion-resistant alloys, in batteries, and as chemical reagents

Methods that are effective in controlling worker exposures to soluble nickel compounds, 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 soluble nickel compounds 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 soluble nickel compounds, 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, kidneys, 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 soluble nickel compounds 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, kidneys, 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 soluble nickel compounds exposure. The interviews, examinations, and medical screening tests should focus on identifying the adverse effects of soluble nickel compounds on the skin, liver, kidneys, 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 soluble nickel compounds 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. Exposure to nickel can be measured in the using the NIOSH method for metals in urine (Method # 8310). This method requires analysis by inductively-coupled argon plasma, atomic emission spectroscopy (ICP-AES). However, no biological monitoring test acceptable for routine use has yet been developed for soluble nickel compounds [NIOSH 1994].

WORKPLACE MONITORING AND MEASUREMENT

Determination of a worker's exposure to airborne soluble nickel compounds (as Ni) is made using a mixed cellulose ester filter (MCEF), 0.8 microns. Samples are collected at a maximum flow rate of 2.0 liters/minute until a minimum collection volume of 480 liters (or a maximum collection volume of 960 liters) is reached. The sample is then treated with deionized water. Analysis is conducted by atomic absorption spectroscopy. This method (ID-121) is described in the OSHA Computerized Information System [OSHA 1994] and is fully validated. A second OSHA method (OSHA ID-125G) can be used for nickel. This method requires analysis by inductively coupled plasma-atomic emission spectroscopy (ICP-AES) and is also fully validated. NIOSH also has a method that can be used to determine a worker's exposure to soluble nickel compounds (as Ni). This method (Method No. 7300-elements by ICP) also uses MCE filters, but flow rates vary from 1 to 4 liters per minute and the collection volumes range from 25 to 1000 liters. Analysis is conducted by inductively-coupled argon plasma, atomic emission spectroscopy (ICP-AES) [NIOSH 1994].

PERSONAL HYGIENE PROCEDURES

If soluble nickel compounds contacts the skin, workers should immediately wash the affected areas with large amounts of soap and water.

Clothing contaminated with soluble nickel compounds 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 soluble nickel compounds, particularly their potential for causing dermal irritation and sensitization.

A worker who handles soluble nickel compounds 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 soluble nickel compounds or a solution containing soluble nickel compounds is handled, processed, or stored.

STORAGE

Soluble nickel compounds 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 soluble nickel compounds should be protected from physical damage and should be stored separately from strong acids, potassium, sulfur, combustibles, organics, or other readily oxidizable materials.

SPILLS AND LEAKS

In the event of a spill or leak involving soluble nickel compounds, 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. Absorb liquid spills in vermiculite, dry sand, earth, or a similar material and place into suitable containers for later disposal.

3. Collect powdered material in the most safe and convenient manner possible and deposit into suitable containers for later 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. The EPA requirements for specific soluble nickel compounds may vary. As an example, the requirements outlined below are for the example compounds used in this document; nickel chloride, nickel nitrate, and nickel sulfate.

* Emergency planning requirements

The example soluble nickel compounds are 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 the example soluble nickel compounds 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 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 the example soluble nickel compounds 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 the example soluble nickel compounds are 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 soluble nickel compounds 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 soluble nickel compounds. 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 soluble nickel compounds. There are no published reports on the resistance of various materials to permeation by soluble nickel compounds.

To evaluate the use of PPE materials with soluble nickel compounds, 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 soluble nickel compounds.

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.

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.

Clayton G, Clayton F [1981-1982]. Patty's industrial hygiene and toxicology. 3rd rev. ed. New York, NY: John Wiley & Sons.

DOT [1993]. 1993 Emergency response guidebook, guide 35. Washington, DC: U.S. Department of Transportation, Office of Hazardous Materials Transportation, Research and Special Programs Administration.

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

Hathaway GJ, Proctor NH, Hughes JP, and Fischman ML [1991]. Proctor and Hughes' chemical hazards of the workplace. 3rd ed. New York, NY: Van Nostrand Reinhold.

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.

Lewis RJ, ed. [1993]. Hawley's condensed chemical dictionary. 12th ed. New York, NY: Van Nostrand Reinhold Company.

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.

NFPA [1986]. Fire protection guide on hazardous materials. 9th ed. Quincy, MA: National Fire Protection Association.

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 [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.

NIOSH [1995]. Registry of toxic effects of chemical substances: Nickel chloride, nickel nitrate, nickel sulfate. 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.

NJDH [1986]. Hazardous substance fact sheet: Nickel chloride, nickel nitrate, nickel sulfate. Trenton, NJ: New Jersey Department of Health.

NLM [1995]. Hazardous substances data bank: Nickel chloride, nickel nitrate, nickel sulfate. Bethesda, MD: National Library of Medicine.

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

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.

USCG [1984]. CHRIS (chemical hazards response information system) hazardous chemical data manual: soluble nickel compounds. Washington, DC: U.S. Department of Transportation, U.S. Coast Guard, Commandant Instruction M16465.12A.

Windholz M, ed. [1983]. Merck Index 10th ed. Rahway, NJ: Merck & Company.