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 This information may be superseded by new developments in the field of industrial hygiene.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

INTRODUCTION

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 Recommendations may be superseded by new developments in these fields; readers are therefore advised to regard these recommendations as general guidelines and to determine whether new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

SUBSTANCE IDENTIFICATION

* Formula

CH(2)O(2)

* Structure

(For Structure, see paper copy)

* Synonyms

Formic acid 85%, formic acid 90%, formic acid 95%, hydrogen carboxylic acid, methanoic acid, aminic acid, formylic acid, Bilorin, Collo-didax, Formira, Formisotin

* Identifiers

1. CAS No.: 64-18-6

2. RTECS No.: LQ4900000

3. DOT UN: 1779 60

4. DOT label: Corrosive

* Appearance and odor

Formic acid is a colorless, fuming liquid with a highly pungent, penetrating odor. The usual commercial product is a solution of 90 percent formic acid in water. The air odor threshold concentration for formic acid is 49 parts per million (ppm) parts of air.

CHEMICAL AND PHYSICAL PROPERTIES

* Physical data

1. Molecular weight: 46.03

2. Boiling point (at 760 mm Hg): 101 degrees C (213.8 degrees F)

3. Specific gravity (water = 1): 1.22 at 20 degrees C (68 degrees F) (glacial)

4. Vapor density: 1.6 (glacial)

5. Melting point: 8.4 degrees C (47.1 degrees F) (glacial)

6. Vapor pressure at 20 degrees C (68 degrees F): 35 mm Hg

7. Solubility: Miscible in water in all proportions; also miscible with alcohol, ether, acetone, benzene, and glycerol.

8. Evaporation rate (butyl acetate = 1): 2.1

* Reactivity

1. Conditions contributing to instability: Heat or flame.

2. Incompatibilities: Contact between formic acid and strong oxidizers, alkaline materials, or strong caustics should be avoided. Contact with concentrated sulfuric acid causes formation of carbon monoxide. May explode when in contact with hydrogen peroxide and with furfuryl alcohol.

3. Hazardous decomposition products: None reported.

4. Special precautions: Glacial formic acid will slowly decompose at room temperatures resulting in increased pressure if containers are sealed or unvented.

* Flammability

The National Fire Protection Association has assigned a flammability rating of 2 (moderate fire hazard) to formic acid.

1. Flash point: 68.9 degrees C (156 degrees F) (open cup)

2. Autoignition temperature: 539 degrees C (1004 degrees F) (glacial)

3. Flammable limits in air (percent by volume): Lower, 18; upper, 57

4. Extinguishant: For small fires use dry chemical, carbon dioxide, water spray, or regular foam. Use water spray, fog, or regular foam to fight large fires involving formic acid.

Fires involving formic acid should be fought upwind from the maximum distance possible. Keep unnecessary people away; isolate the hazard area and deny entry. Emergency personnel should stay out of low areas and ventilate closed spaces before entering. Containers of formic acid may explode in the heat of the fire and should be moved from the fire area if it is possible to do so safely. If this is not possible, cool fire exposed containers from the sides with water until well after the fire is out. Stay away from the ends of containers. Firefighters should wear a full set of protective clothing and self-contained breathing apparatus when fighting fires involving formic acid.

EXPOSURE LIMITS

* OSHA PEL

The current Occupational Safety and Health Administration (OSHA) permissible exposure limit (PEL) for formic acid is 5 ppm parts of air (9 milligrams per cubic meter (mg/m(3))) 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 formic acid of 5 ppm (9 mg/m(3)) as a TWA for up to a 10-hour workday and a 40-hour workweek [NIOSH 1992].

* ACGIH TLV

The American Conference of Governmental Industrial Hygienists (ACGIH) has assigned formic acid a threshold limit value (TLV) of 5 ppm (9.4 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 10 ppm (19 mg/m(3)) for periods not to exceed 15 minutes. Exposures at the STEL concentration should not be repeated more than four times a day and should be separated by intervals of at least 60 minutes [ACGIH 1994, p. 22].

* Rationale for Limits

The NIOSH limit is based on the risk of severe irritation of the eyes, mucous membranes, upper respiratory tract, and skin [NIOSH 1992].

The ACGIH limits are based on the risk of irritation of the eyes, skin, and respiratory tract [ACGIH 1991, p. 692].

HEALTH HAZARD INFORMATION

* Routes of Exposure

Exposure to formic acid can occur through inhalation, ingestion, and eye or skin contact [Sittig 1991, p. 840].

* Summary of toxicology

1. Effects on Animals: Formic acid is severely irritating to the eyes, skin, and mucous membranes. The oral LD(50) in rats is 1,100 mg/kg and 700 mg/kg in mice [NIOSH 1992]. A dose of 610 mg formic acid applied to a rabbit's open skin produced mild irritation. A dose of 122 mg applied to the eye of a rabbit caused severe irritation [Sax and Lewis 1989]. Instillation of 10 percent formic acid solution in the eye of a rabbit caused an immediate dense, white, local opacification of the cornea that cleared slightly after 5 days. Application of pure liquid formic acid, however, caused immediate, local corneal opacification as well as opacification of the lens, inflammation of the iris, and damage to the anterior chamber of the eye [NLM 1992]. Administration of formic acid in a monkey's eye produced the same type of optic atrophy and blindness as that caused by exposure to methanol [Grant 1986]. Intravenous doses of formic acid of 0.46 to 1.25 g/kg given to rabbits caused central nervous system depression, vasoconstriction, and diuresis. Intravenous doses of 4 mg/kg caused convulsions and death in rabbits and methemoglobinuria in dogs [NLM 1992]. Studies of chronic exposure to formic acid have shown that young rats given 0.5 or 1 percent formic acid in their diets or drinking water for 6 weeks had reductions in their rates of body weight gain and reduced organ size when compared with controls [NLM 1992]. No histopathologic changes were noted in mice whose ears had been painted with an 8-percent formic acid solution in water for up to 50 days [Clayton and Clayton 1982]. Formic acid was not teratogenic after injection of doses as great as 20 mg into fertilized chick eggs [Clayton and Clayton 1982]. Formic acid is mutagenic in some, but not all, bacterial species and in Drosophila germ cells [Clayton and Clayton 1982].

2. Effects on Humans: Formic acid is dangerously irritating to the skin, eyes, and mucous membranes and may also be toxic to the kidneys. Workers exposed to formic acid in a textile plant complained of nausea at an average formic acid concentration of 15 ppm [NLM 1992]. Atmospheric concentrations as low as 32 mg/l may be corrosive; however, a dilute solution of 10 percent formic acid apparently is not corrosive [Clayton and Clayton 1982]. Acute, overexposure to formic acid causes corrosion of the skin, eyes, and mucous membrane of the mouth, throat, and esophagus and may be associated with complications such as cardiovascular collapse and ischemic damage to the heart, liver and kidneys, swelling of the airway, and respiratory distress. Ingesting causes ulceration of the gastrointestinal tract, which results in perforation and peritonitis and late scarring of structures of the gastrointestinal tract which, in turn, produces obstructions that require surgical repair [Gosselin 1984]. A worker splashed in the face with formic acid developed respiratory distress and difficulty in swallowing, and died within 6 hours [Hathaway et al. 1991]. Other reports indicate that splashes of formic acid in the eye have caused permanent clouding of the cornea, with loss of visual acuity. In one case, the injury required removal of the affected eye [Grant 1986]. Chronic absorption of formic acid may cause damage to the kidneys, which is indicated by albuminuria and hematuria [NLM 1992]. Chronic skin contact may cause sensitization dermatitis, particularly in workers previously sensitized to formaldehyde [NLM 1992].

* Signs and symptoms of exposure

1. Acute exposure: Symptoms of acute exposure include redness, swelling, and blistering of the skin and mucous membranes of the mouth and throat, eye irritation, nausea, vomiting, diarrhea, difficulty in swallowing, difficulty in breathing, headache, dizziness, blood in the urine, decreased or absence of urine production, and unconsciousness. Signs of shock and impending cardiovascular collapse including clammy skin, a weak and rapid pulse, shallow respirations, and scanty or absent urine production.

2. Chronic exposure: Signs and symptoms of chronic exposure may include kidney damage, dermatitis, and skin sensitization.

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 formic acid and lead to worker exposures to this substance:

* The manufacture and transportation of formic acid

* Use in natural and synthetic textile and paper dyeing and finishing, as a dye-exhausting agent, to impart finishes to cotton and wool, and as a shrink- and wrinkle-proofing compound

* Use as a chemical intermediate for formates, oxalic acid, and performic acid; as a strong reducing agent for acids, salts, dyes, fumigants, insecticides, refrigerants, and pharmaceuticals; and as a solvent for perfumes and lacquers

* Use in leather processing industry as a deliming agent and neutralizer, and to tan, dehair, and plump hides

* Use in rubber industry as a coagulant for natural rubber latex and form making, and as a preservative of latex

* Use in electroplating industry to control particle size and plating thickness, as a reducing agent in chrome dyeing and in nickel plating baths, and in silvering glass

* Use as an antiseptic in wine and beer brewing, as a flavor adjunct in perfumes, and as a preservative in animal feed additives and in cleaning solution compounds

* Use in miscellaneous operations as a wire stripping compound and to prepare bare wires for soldering; as a laundry sour; as an oil well acidifying agent; as an antiseptic in brewing; and in ore flotation

Methods that are effective in controlling worker exposures to formic acid, 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 formic acid 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 formic acid, 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 eyes, 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 formic acid 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 eyes, skin, and 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 formic acid exposure. The interviews, examinations, and medical screening tests should focus on identifying the adverse effects of formic acid on the eyes, skin, and 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.

* Biological monitoring

Biological monitoring involves sampling and analyzing body tissues or fluids to provide an index of exposure to a toxic substance or metabolite. No biological monitoring test acceptable for routine use has yet been developed for formic acid.

WORKPLACE MONITORING AND MEASUREMENT

Determination of a worker's exposure to airborne formic acid is made using a charcoal tube (100/50 mg sections, 20/40 mesh). Samples are collected at a maximum flow rate of 0.2 liter/minute until a maximum collection volume of 48 liters is reached. The sample is then treated with 0.01N NaOH. Analysis is conducted by ion chromatography. This method is partially validated and is described in the OSHA Computerized Information System [OSHA 1994] and a similar method is described in NIOSH Method No. 2011 [NIOSH 1994b].

PERSONAL HYGIENE PROCEDURES

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

Clothing contaminated with formic acid 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 formic acid, particularly its potential for causing severe irritation.

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

STORAGE

Formic acid 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 formic acid should be protected from physical damage and ignition sources, and should be stored separately from strong oxidizers, alkaline materials, strong caustics, concentrated sulfuric acid, hydrogen peroxide, and furfuryl alcohol.

SPILLS AND LEAKS

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

1. Notify safety personnel.

2. Remove all sources of heat and ignition.

3. Ventilate the area of the spill or leak.

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

5. For small liquid spills, take up with vermiculite, dry sand, earth or other noncombustible absorbent material and place into closed 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.

* Emergency planning requirements

Formic acid 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].

The reportable quantity of formic acid is 5,000 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 formic acid 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. formic acid is listed as a hazardous waste under RCRA and has been assigned EPA Hazardous Waste No. U123. This substance has been banned from land disposal until treated by fuel substitution or incineration.

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 formic acid 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 formic acid. 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 formic acid. The resistance of various materials to permeation by formic acid is shown below:

(*) Not recommended, degradation may occur

To evaluate the use of these PPE materials with formic acid, 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 formic acid.

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.

Amoore JE, Hautala E [1983]. Odor as an aid to chemical safety: odor thresholds compared with threshold limit values and volatilities for 214 industrial chemicals in air and water dilution. J of App Tox 3(6):272-290.

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 60. Washington, DC: U.S. Department of Transportation, Office of Hazardous Materials Transportation, Research and Special Programs Administration.

Forsberg K, Mansdorf SZ [1993]. Quick selection guide to chemical protective clothing. New York, NY: Van Nostrand Reinhold.

Genium [1990]. Material safety data sheet No. 416. Schenectady, NY: Genium Publishing Corporation.

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

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.

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

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 [1991]. Registry of toxic effects of chemical substances: Formic Acid. 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 [1994a]. NIOSH pocket guide to chemical hazards. 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. 94-116.

NIOSH [1994b]. 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 [1985]. Hazardous substance fact sheet: Formic Acid. Trenton, NJ: New Jersey Department of Health.

NLM [1992]. Hazardous substances data bank: Formic Acid. 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 Organization.

Patnaik P [1992]. A comprehensive guide to the hazardous properties of chemical substances. New York, NY: Van Nostrand Reinhold.

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.

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