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CHEMINFO Record Number: 374
CCOHS Chemical Name: Benzoic acid

Benzenecarboxylic acid
Benzeneformic acid
Benzenemethanoic acid
Dracylic acid
Phenylcarboxylic acid
Phenylformic acid
Flowers of benjamin
Flowers of benzoin

Chemical Name French: Acide benzoïque
Chemical Name Spanish: Acido benzoico
CAS Registry Number: 65-85-0
RTECS Number(s): DG0875000
EU EINECS/ELINCS Number: 200-618-2
Chemical Family: Aromatic carboxylic acid / aromatic monocarboxylic acid / benzenecarboxylic acid / benzoic acid
Molecular Formula: C7-H6-O2
Structural Formula: C6H5-C(=O)-OH


Appearance and Odour:
White powder or crystals; faint, pleasant, slightly aromatic odour.(6,15)

Odour Threshold:
No information was located

Warning Properties:
Information not available for evaluation.

Benzoic acid is available in industrial (97.5% minimum) and technical (99.0% minimum) grades and in grades meeting specifications of the United States Pharmacopoeia (USP) and the Food Chemicals Codex (FCC) for pharmaceutical and food additive uses respectively (99.5% and greater). Trace impurities present in commercial benzoic acid include methyl diphenyls and phthalic acids. Industrial and technical grades are available in both molten and solid forms, while USP and FCC grades are available in solid forms (crystals or powder).(16)

Uses and Occurrences:
The largest use for benzoic acid is as a chemical raw material in the production of phenol, caprolactam, glycol dibenzoates used as plasticizers, sodium and potassium benzoates and other benzoic acid derivatives such as benzoyl chloride and benzoic acid esters. It is also used as a preservative in foods, juices, fats and oils; in alkyd resins; as a down-hole drilling mud additive; for pharmaceutical and medicinal uses; in the synthesis of dyestuffs, pharmaceuticals, perfumes and herbicides; in flavours and cosmetic preparations; as a corrosion inhibitor; as a laboratory reagent; as a standard in analytical chemistry; and an ingredient of antiseptic ointments for the treatment of fungal infections of the skin.(7,16-19)
Benzoic acid in the free state and in the form of simple derivatives is widely distributed in nature. Appreciable amounts are found in gum benzoin and in most berries, such as cranberries. The free acid is found in natural products such as prunes, ripe cloves and oil of anise seeds.(16,18,19)


White powder or crystals with a faint, pleasant, slightly aromatic odour. Can burn if strongly heated. COMBUSTIBLE DUST. Can form explosive dust-air mixtures. EYE IRRITANT. Causes severe eye irritation. Can cause redness, swelling and itching (hives) at the point of skin contact.


Effects of Short-Term (Acute) Exposure

In general, high concentrations of dust may cause coughing and mild, temporary irritation. Very high concentrations of benzoic acid dust have caused irritation of the nose, throat and upper respiratory passages in animals. There is no human information available.

Skin Contact:
Benzoic acid is a very mild to mild irritant based on unconfirmed animal information. However, benzoic acid can cause redness and swelling with itching (non-immunological contact urticaria or hives) in most people at the site of application. Individuals can react without having been previously exposed to benzoic acid. The strength of the reaction is dose dependent, ranging from slight redness to extensive redness and swelling with tingling, burning or itching.(1)
A non-allergic hive reaction (reddening, patchy swelling, "burning" sensation and itching) was observed in humans within 30 minutes following application of 0.25% benzoic acid in water or 5% benzoic acid in petrolatum.(2) An immediate non-allergic skin reaction (redness or swelling) was observed in 12 volunteers following application of 15-250 millimolar solutions of benzoic acid in water. Washing the skin twice a day with soap and water intensified the reaction.(3)

Eye Contact:
Benzoic acid dust or solutions can cause serious eye injury, based on animal information. Permanent injury, including blindness, could result. No human information was located.

Benzoic acid is used, in low concentrations, as a preservative in foods. It is low in acute oral toxicity, based on animal and human information. No harmful effects were observed in one reported case in which an individual ingested about 50 grams (about 750 mg/kg).(4) In another case, death reportedly followed ingestion of about 500 mg/kg.(5) Ingestion is not a typical route of occupational exposure.

Effects of Long-Term (Chronic) Exposure

Skin Sensitization:
There is insufficient information available to evaluate one case report of a chemical worker who developed an allergic reaction while being exposed to benzoic acid at work.(6, unconfirmed) Another historical case report describes a baker who developed contact dermatitis following exposure to certain types of flour. Patch testing revealed allergies to several different compounds, one of which was benzoic acid. It is not clear if the reaction being described was contact urticaria or a true allergic response.(7)

INGESTION: Benzoic acid is low in chronic oral toxicity, based on human and animal information. No harmful effects were observed in 6 volunteers fed 300-400 mg benzoic acid in the diet for up to 62 days.(8) Ingestion is not a typical route of occupational exposure.


There is no human or animal information available.

The International Agency for Research on Cancer (IARC) has not evaluated the carcinogenicity of this chemical.

The American Conference of Governmental Industrial Hygienists (ACGIH) has no listing for this chemical.

The US National Toxicology Program (NTP) has not listed this chemical in its report on carcinogens.

Teratogenicity and Embryotoxicity:
There is no human or animal information available.

Reproductive Toxicity:
No harmful effects were observed in one animal study. There is no human information available.

There is no human information available. Positive, negative and inconclusive results have been obtained in tests using bacteria or cultured mammalian cells.

Toxicologically Synergistic Materials:
No synergism was found between benzoic acid and any of a number of food additives following short-term oral administration.(5)

Potential for Accumulation:
Benzoic acid does not accumulate in the body. It is rapidly absorbed following ingestion from the gastrointestinal tract and metabolized in the liver to form hippuric acid, which is rapidly and almost completely excreted in the urine within 10 to 14 hours. Up to 97% may be excreted in the first 4 hours. When taken in large doses some benzoic acid may be excreted as benzoylglucuronic acid. Very small amounts are excreted as expired carbon dioxide and in the feces.(6,8,9)


If symptoms are experienced, remove source of contamination or have victim move to fresh air. If symptoms persist, obtain medical advice immediately.

Skin Contact:
Remove contaminated clothing, shoes and leather goods (e.g. watchbands, belts). Gently blot or brush away excess chemical quickly. As quickly as possible, flush contaminated area with lukewarm, gently running water for at least 20 minutes, or until the chemical is removed. Obtain medical attention immediately. Completely decontaminate clothing, shoes and leather goods before reuse, or discard.

Eye Contact:
Quickly and gently blot or brush away excess chemical. Immediately flush the contaminated eye(s) with lukewarm, gently flowing water for 20 minutes, or until the chemical is removed while holding the eyelid(s) open. Take care not to rinse contaminated water into the non-affected eye or onto the face. Obtain medical attention immediately.

If irritation or discomfort occur, obtain medical advice immediately.

First Aid Comments:
Provide general supportive measures (comfort, warmth, rest).
All first aid procedures should be periodically reviewed by a doctor familiar with the material and its conditions of use in the workplace.


Flash Point:
121 deg C (250 deg F) (closed cup) (15)

Lower Flammable (Explosive) Limit (LFL/LEL):
Not available

Upper Flammable (Explosive) Limit (UFL/UEL):
Not available

Autoignition (Ignition) Temperature:
570-573 deg C (1058-1063.4 deg F) (16,17,20)

Sensitivity to Mechanical Impact:
Probably not sensitive. Stable material.

Combustion and Thermal Decomposition Products:
Incomplete combustion may also produce irritating fumes, such as benzene and phenol, and acrid smoke.

Flammable Properties:

Specific Hazards Arising from the Chemical:
During a fire, irritating/toxic gases and fumes may be generated.

Extinguishing Media:
Carbon dioxide, dry chemical powder, alcohol foam, polymer foam, water spray or fog.(15)

Fire Fighting Instructions:
Evacuate area and fight fire from a safe distance or a protected location. Approach fire from upwind to avoid toxic decomposition products.
Water or foam may cause frothing. The frothing may be violent and could endanger personnel close to the fire. However, a water spray or fog that is carefully applied to the surface of the burning material, preferably with a fine spray or fog nozzle, will cause frothing that will blanket and extinguish the fire. In addition, water spray or fog can be used to prevent dust formation, absorb heat, keep containers cool and protect exposed material. Water spray may be used to flush spills away from ignition sources. Solid streams of water may be ineffective and spread material.
The decomposition products of benzoic acid may be hazardous to health. Do not enter without wearing specialized protective equipment suitable for the situation. Firefighter's normal protective equipment (Bunker Gear) will not provide adequate protection. Chemical resistant clothing (e.g. chemical splash suit and positive pressure self-contained breathing apparatus (MSHA/NIOSH approved or equivalent) may be necessary.


NFPA - Health: 1 - Exposure would cause significant irritation, but only minor residual injury.
NFPA - Flammability: 1 - Must be preheated before ignition can occur.
NFPA - Instability: 0 - Normally stable, even under fire conditions, and not reactive with water.


Molecular Weight: 122.12

Conversion Factor:
Not applicable

Physical State: Solid
Melting Point: 122-123 deg C (251.6-253.4 deg F) (15); begins to sublime at about 100 deg C (212 deg F) (17,19)
Boiling Point: 249 deg C (480.2 deg F) (15,16,19); begins to sublime at about 100 deg C (212 deg F) (17,19)
Relative Density (Specific Gravity): 1.321 at 20 deg C (water = 1) (17). Also reported as 1.266 at 15 deg C (water = 1) (24)
Solubility in Water: Slightly soluble in water (290 mg/100 g at 20 deg C) (16,17)
Solubility in Other Liquids: Very soluble in absolute ethanol, acetone, diethyl ether and methanol; soluble in benzene, chloroform, toluene and volatile and fixed oils; slightly soluble in hexane and petroleum ether (16,17,19)
Coefficient of Oil/Water Distribution (Partition Coefficient): Log P(oct) = 1.87 at 20 deg C (18,25)
pH Value: 2.8 (saturated solution (0.34%) in water at 25 deg C) (16,17,19); 3.1 (0.01 N (0.12%)) (24)
Acidity: Weak acid; pKa = 4.19 at 25 deg C (Ka = 6.46 x 10(-5)) (24)
Viscosity-Dynamic: 1.26 mPa.s (1.26 centipoises) at 130 deg C (molten liquid) (16)
Surface Tension: 31 mN/m (31 dynes/cm) at 130 deg C (molten liquid) (17)
Vapour Density: Not applicable
Vapour Pressure: Very low at 25 deg C; 0.133 kPa (1 mm Hg) at 96 deg C (16,17,24)
Saturation Vapour Concentration: Not available at 25 deg C
Evaporation Rate: Very low at normal temperatures.
Critical Temperature: 479 deg C (894 deg F) (6)
Critical Pressure: 4560 kPa (45 atm.) (6)

Other Physical Properties:
Note: Volatile with steam.(17,19)


Normally stable. Decarboxylation (loss of the carboxyl group) occurs when benzoic acid is heated above 370 deg C. Copper and cadmium accelerate this reaction.(17)

Hazardous Polymerization:
Does not occur

Incompatibility - Materials to Avoid:

NOTE: Chemical reactions that could result in a hazardous situation (e.g. generation of flammable or toxic chemicals, fire or detonation) are listed here. Many of these reactions can be done safely if specific control measures (e.g. cooling of the reaction) are in place. Although not intended to be complete, an overview of important reactions involving common chemicals is provided to assist in the development of safe work practices.

STRONG OXIDIZING AGENTS (e.g. perchlorates, peroxides, chlorine) - may react vigorously or violently. Risk of fire and explosion.(15) One source reports that benzoic acid is stable to the usual oxidizing agents including potassium permanganate, chromic acid, hypochlorite and dilute nitric acid.(17)
NITRITES - mixtures with nitrites, such as sodium nitrite, may explode violently on heating.(26)
STRONG REDUCING AGENTS (e.g. phosphorus, tin (II) chloride, metal hydrides) - may react vigorously or violently.(15)
STRONG BASES (including alkalis such as sodium hydroxide) - react vigorously.(15)

Hazardous Decomposition Products:
None reported

Conditions to Avoid:
Generation of dust, heat, flames, sparks, build-up of static electricity and other ignition sources

Corrosivity to Metals:
Benzoic acid solutions are corrosive to steel, gray cast iron and lead.(27) Not corrosive to types 304 and 316 stainless steels or to nickel-molybdenum and nickel-chromium-molybdenum alloys.(27,28) Type 316 stainless steel is resistant to corrosion at high temperatures and is used to ship molten benzoic acid.(16) Aluminum is generally resistant to acids at room temperature.(27,28)


LC50 (rat): greater than 6.5 mg/m3 (4-hour exposure); cited as greater than 26 mg/m3 (1-hour exposure) (10, unconfirmed)

LD50 (oral, rat): 1700 mg/kg (10, unconfirmed)
LD50 (oral, mouse): 1950 mg/kg (11)

LD50 (dermal, rabbit): greater than 5000 mg/kg (5)

Eye Irritation:

Benzoic acid can cause serious eye injury.

In a standard Draize test, application of 0.1 mL benzoic acid produced severe irritation in rabbits (maximum average score: 41.3/110 at 24 hours). The corneas of 3/6 animals had not healed by day 35 following exposure.(29)

Skin Irritation:

Benzoic acid is a very mild to mild irritant.

Application of 500 mg benzoic acid moistened with water, under a patch for 4 hours, caused very mild irritation in rabbits (score 0.5/8).(30, unconfirmed) Mild irritation was observed in rabbits in a standard Draize test.(10, unconfirmed) Scoring information was not provided.

Effects of Short-Term (Acute) Exposure:

Upper respiratory tract irritation and other toxic effects were observed in rats following inhalation of very high airborne concentrations (250 or 1200 mg/m3 dust with equivalent aerodynamic diameter 4.7 micrometres (um)) of benzoic acid for 4 weeks. No harmful effects were observed following inhalation of 25 mg/m3.(6, unconfirmed)

Skin Contact:
In a test designed to evaluate the potential of chemicals to cause hives (non-immunological contact urticaria), immediate redness and swelling was observed following application of 0.2-20% benzoic acid to guinea pig ear lobes. However, no irritation was observed following similar application to the back, abdomen or flank.(1)

Convulsions and death were observed following single oral doses of greater than 450 mg/kg benzoic acid to cats. Similar effects were observed following daily doses of greater than 200 mg/kg. The authors conclude that these effects are likely specific to cats.(12)

Effects of Long-Term (Chronic) Exposure:

No toxic effects were observed in rats fed a diet containing 1% benzoic acid (equivalent to 500 mg/kg daily) in short- and long-term feeding studies.(5)

Reproductive Toxicity:
No harmful effects on reproduction were observed in rats following ingestion of up to 1% benzoic acid in a multi-generational study.(8)

There is insufficient information available to evaluate the mutagenic potential of benzoic acid. No studies using live animals were located.
Three negative and one positive result have been obtained in tests using bacteria (both with and without metabolic activation).(10,13,14) Inconclusive results were obtained in a test (chromosome test) using cultured mammalian cells.(14)


Selected Bibliography:
(1) Lahti, A., et al. An animal model for nonimmunologic contact urticaria. Toxicology and Applied Pharmacology. Vol. 76, no. 2 (Nov. 1984). p. 219-224
(2) Nethercott, J.R., et al. Airborne contact urticaria due to sodium benzoate in a pharmaceutical manufacturing plant. Journal of Occupational Medicine. Vol. 26, no. 10 (Oct. 1984). p. 734-736
(3) Lahti, A., et al. Immediate irritant reactions to benzoic acid are enhanced in washed skin areas. Contact Dermatitis. Vol. 33, no. 3 (Sept. 1995). p. 177-182
(4) Gosselin, R.E., et al. Clinical toxicology of commercial products. 5th ed. Williams and Wilkins, 1984. p. II-203
(5) Opdyke, D.L.J. Fragrance raw materials monographs. Food and Cosmetics Toxicology. Vol. 17 (1979). p. 715-722
(6) HSDB record for benzoic acid. Last revision date: 97/04/01
(7) Baird, K.A. Allergy to chemicals in flour: a case of dermatitis due to benzoic acid. Journal of Allergy. Vol. 16 (July 1945). p. 195-198
(8) Benzoic acid and its potassium and sodium salts. In: Joint FAO/WHO Expert Committee on Food Additives. Toxicological evaluation of some food additives, including anticaking agents, antimicrobials, antioxidants, emulsifiers and thickening agents. WHO Food Additive Series, 1974, no. 5. World Health Organization, 1974. p. 34-42
(9) Reynolds. J.E.F., ed. Martindale: the extra pharmacopoeia. 29th ed. The Pharmaceutical Press, 1989. p. 1355-1356
(10) RTECS record for benzoic acid. Last updated: 9704
(11) Anonymous. Acute toxicity data. Shell Chemical Company, New York, April, 1961
(12) Bedford, P.G.C., et al. Experimental benzoic acid poisoning in the cat. The Veterinary Record. Vol. 90, no. 3 (Jan. 15, 1972). p. 53-58
(13) Zeiger, E., et al. Salmonella mutagenicity tests: IV. Results from the testing of 300 chemicals. Environmental and Molecular Mutagenesis. Vol. 11, suppl. 12 (1988). p. 1-158
(14) Ishidate, M., et al. Primary mutagenicity screening of food additives currently used in Japan. Food and Chemical Toxicology. Vol. 22, no. 8 (1984). p. 623-636
(15) The Sigma-Aldrich library of chemical safety data. Ed. II. Vol. 1. Sigma-Aldrich Corporation, 1988. p. 360A
(16) Opgrande, J.L., et al. Benzoic acid. In: Kirk-Othmer encyclopedia of chemical technology. 4th ed. Vol. 4. John Wiley and Sons, 1992. p. 103-115
(17) Maki, T, et al. Benzoic acid and derivatives. In: Ullmann's encyclopedia of industrial chemistry. 5th completely revised ed. Vol. A 3. VCH Verlagsgesellschaft, 1985. p. 555-569
(18) Verschueren, K. Handbook of environmental data on organic chemicals. 3rd ed. Van Nostrand Reinhold, 1996. p. 283-285
(19) Budavari, S, ed. The Merck index: an encyclopedia of chemicals, drugs, and biologicals. 12th ed. Merck and Co. Inc., 1996. p. 183
(20) Fire protection guide to hazardous materials. 13th ed. Edited by A.B. Spencer, et al. National Fire Protection Association, 2002. NFPA 325
(21) Field, P. Explosibility assessment of industrial powders and dusts. Building Research Establishment, 1983
(22) Grossel, S.S. Safety considerations in conveying of bulk solids and powders. Journal of Loss Prevention in the Process Industries. Vol. 1 (Apr. 1988). p. 62-74
(23) Schwab, R.F. Dusts. In: Fire protection handbook. Edited by G.P. McKinnon. 15th ed. National Fire Protection Association, 1981. p. 4-84 to 4-97
(24) Handbook of chemistry and physics. 66th ed. Edited by R.C. Weast. CRC Press, 1985-1986. p. C-126, D-146, D-161, D-203
(25) Leo, A., et al. Partition coefficients and their uses. Chemical Reviews. Vol. 71, no. 6 (Dec. 1971). p. 576
(26) Urben, P.G., ed. Bretherick's handbook of reactive chemical hazards. 5th ed. Vol. 1. Butterworth-Heinemann Ltd., 1995. p. 944-945, 1672
(27) Corrosion data survey: metals section. 6th ed. National Association of Corrosion Engineers, 1985. p. 20-1 to 21-1
(28) Elder, G.B. Materials of construction for organic acids. In: Process industries corrosion: the theory and practice. Edited by B.J. Moniz, et al. National Association of Corrosion Engineers, 1986. p. 287-296
(29) Initial submission: primary eye irritation of benzoic acid to rabbits with cover letter dated 082892. Produced by: Monsanto Co. Date produced: Jan. 17, 1983. EPA/OTS 88-920008107. NTIS/OTS0546102.
(30) Benzoic acid. IUCLID data set. European Commission. Feb. 2000

Information on chemicals reviewed in the CHEMINFO database is drawn from a number of publicly available sources. A list of general references used to compile CHEMINFO records is available in the database Help.

Review/Preparation Date: 1998-01-27

Revision Indicators:
TDG 2002-06-11
NFPA (health) 2003-04-18
NFPA (reactivity) 2003-04-18
Resistance of materials for PPE 2004-04-08
Bibliography 2006-01-18
Toxicological info 2006-02-21
Short-term skin contact 2006-02-21
Short-term eye contact 2006-02-21
Conversion factor 2006-10-05
Vapour density 2006-10-05
LFL/LEL 2006-10-05
UFL/UEL 2006-10-05

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