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CHEMINFO Record Number: 604
CCOHS Chemical Name: Citric acid

beta-Hydroxy-tricarboxylic acid
beta-Hydroxytricarballylic acid
2-Hydroxy-1,2,3-propanetricarboxylic acid
Acide citrique

Chemical Name French: Acide citrique
Chemical Name Spanish: Acido cítrico
CAS Registry Number: 77-92-9
Other CAS Registry Number(s): 5949-29-1
RTECS Number(s): GE7350000
EU EINECS/ELINCS Number: 201-069-1
Chemical Family: Saturated aliphatic carboxylic acid / saturated aliphatic tricarboxylic acid / saturated aliphatic hydroxycarboxylic acid / hydroxyalkanoic acid
Molecular Formula: C6-H8-O7
Structural Formula: HOOC-CH2-C(OH)(COOH)-CH2-COOH


Appearance and Odour:
Colourless crystals, or white, granular to fine crystalline powder (2,10); deliquescent (absorbs moisture from the air and forms wet solid or solution) in moist air.(2)

Odour Threshold:
Odourless (11)

Warning Properties:
Insufficient information available for evaluation.

Citric acid exists and is available commercially as the anhydrous form (CAS 77-92-9) and as the monohydrate (CAS 5949-29-1). It is also available as an aqueous solution, mainly as a 50% w/w solution.

Uses and Occurrences:
Used widely as an acidulant, pH regulator, flavour enhancer, preservative and antioxidant synergist in many food and beverage products; in pharmaceutical preparations; in metal cleaning, polishing and finishing; as a scale remover in boiler and heat exchanger cleaning; as a hard surface cleaner; as a builder in both liquid and powder laundry detergents; in shampoos and cosmetics; as mordant to brighten colours; as a chelating agent in liquid fertilizers; in animal feeds; in enhanced oil recovery; in removal of hydrogen sulfide from natural and refinery gas; in flue gas desulfurization; as a dispersing agent in mineral and pigment slurries; in electroplating; in concrete, mortar and plaster formulations; in textile manufacturing; in the manufacture of alkyd resins and plastics; as a chemical intermediate for esters used as plasticizers in PVC film; in effervescent type denture cleansers; in shampoos and cosmetics; chemical cleaning; in refractories and moulds; and in analytical chemistry.(2,10,11)
Citric acid is found naturally in plants and animals. It is found in greatest amounts in many citrus fruits, but is also present as the free acid or as a salt in the fruit, seeds or juices of a wide variety of flowers and plants. In the body, citric acid is an essential component of the citric acid cycle which releases energy for physiological functions.(2)


Colourless crystals, or white, granular to fine crystalline powder. Deliquescent. May burn if strongly heated. POTENTIAL COMBUSTIBLE DUST HAZARD. Dry powdered material may form explosive dust-air mixtures. CORROSIVE to the eyes and skin. Can cause permanent eye damage, including blindness, or permanent scarring of the skin.


Effects of Short-Term (Acute) Exposure

Dusts and mists from solutions can probably cause temporary irritation of the nose and throat, based on acidity. The severity of these effects would depend on the airborne concentration, concentration of the solution and the duration of exposure. There is no human or animal information available.

Skin Contact:
Dusts probably cause mild to severe irritation depending upon the duration of exposure. Concentrated solutions are probably corrosive, based on their acidity. Corrosive materials can cause severe skin damage, possibly with permanent scarring. There is no human information and only unconfirmed animal information available.

Eye Contact:
Dusts and solutions can cause severe irritation and corrosive injury (destruction of eye tissue), based on animal information. Depending on the concentration of the solution and the degree of exposure, corrosive materials can cause permanent eye damage, including blindness.
A severe reaction and injury to the cornea (dense white opacity) was reported following an incident in which a large quantity of saturated citric acid solution was splashed into the eyes of one individual.(1)

Citric acid is present in citrus fruits (lemons contain 4-8% citric acid) and is present in many other foods at lower concentrations.(2) It is also used as a food additive.(3) Ingestion of large amounts may cause stomach pain and vomiting. Ingestion is not a typical route of occupational exposure.

Effects of Long-Term (Chronic) Exposure

INGESTION: Ingestion of citric acid continuously and in large amounts can cause tooth erosion, based on animal information. There is no human information available.


Citric acid is probably not carcinogenic. There is no specific information available, but citric acid is a normal part of body metabolism and of the human diet.

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:
Citric acid was not harmful to reproduction in two animal studies. There is no human information available.

Negative results were obtained in three in vitro tests, one using mammalian cells. There is no human or animal in vivo information available.

Toxicologically Synergistic Materials:
There is no information available.

Potential for Accumulation:
Citric acid does not accumulate in the body. It is an essential component of the body's processes for producing energy. It is continually produced and broken down. Even high doses would be rapidly cleared from the body.


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

Skin Contact:
Quickly and gently blot or brush away excess chemical. Remove contaminated clothing, shoes and leather goods (e.g. watchbands, belts). Flush contaminated area with lukewarm, gently flowing water for at least 20-30 minutes, by the clock. If irritation persists, repeat flushing. DO NOT INTERRUPT FLUSHING. If necessary, keep emergency vehicle waiting. Transport victim to an emergency care facility immediately. Completely decontaminate clothing, shoes and leather goods before re-use.

Eye Contact:
Quickly and gently blot or brush away excess chemical. Immediately flush the contaminated eye(s) with lukewarm, gently flowing water for at least 20-30 minutes, by the clock, while holding the eyelid(s) open. Neutral saline solution may be used as soon as it is available. DO NOT INTERRUPT FLUSHING. If necessary, keep emergency vehicle waiting. Take care not to rinse contaminated water into the non-affected eye or onto the face. If irritation persists, repeat flushing. Quickly transport victim to an emergency care facility.

NEVER give anything by mouth if victim is rapidly losing consciousness, is unconscious or is convulsing. Have victim rinse mouth thoroughly with water. DO NOT INDUCE VOMITING. Have victim drink 240-300 mL (8 to 10 oz.) of water to dilute material in stomach. If milk is available, it may be administered AFTER the water has been given. If vomiting occurs naturally, repeat administration of water. Quickly transport victim to an emergency care facility.

First Aid Comments:
Provide general supportive measures (comfort, warmth, rest).
Consult a doctor and/or the nearest Poison Control Centre for all exposures except minor instances of inhalation or skin contact.
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:
Not applicable.

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

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

Autoignition (Ignition) Temperature:
1010 deg C (1850 deg F) (10)

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

Combustion and Thermal Decomposition Products:
Carbon monoxide and carbon dioxide are normal products of combustion.(12) Incomplete combustion may produce irritating fumes 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.(12)

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. If a leak or spill has not ignited, use water spray to disperse the vapours and protect personnel attempting to stop a leak. 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 citric acid may be hazardous to health.
Do not enter without wearing specialized protective equipment suitable for the situation. Firefighter's normal protective clothing (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 - Comments:
NFPA has no listing for this chemical in Codes 49 or 325.


Molecular Weight: 192.13 (anhydrous); 210.14 (monohydrate)

Conversion Factor:
Not applicable

Physical State: Solid
Melting Point: 153-154 deg C (307.4-309.5 deg F) (anhydrous) (2,16,17)
Boiling Point: Decomposes at 175 deg C (347 deg F) (2)
Relative Density (Specific Gravity): 1.665 at 20 deg C (anhydrous) (water = 1) (17)
Solubility in Water: Very soluble (59.2 g/100 g at 20 deg C) (2,16)
Solubility in Other Liquids: Anhydrous citric acid is very soluble in absolute ethanol and moderately soluble in amyl acetate and diethyl ether at 25 deg C.(2,11) The monohydrate is very soluble in methanol and propanol, soluble in amyl alcohol, moderately soluble in amyl acetate, ethyl acetate and diethyl ether and practically insoluble in chloroform at 25 deg C.(10,11)
Coefficient of Oil/Water Distribution (Partition Coefficient): Log P(oct) = -1.72 (measured); -1.25 to -1.80 (calculated) (18)
pH Value: 2.2 (1% solution); 1.7 (10%); 1.2 (30%); 0.8 (50%) (2)
Vapour Density: Not applicable
Vapour Pressure: Practically zero at normal temperatures.
Saturation Vapour Concentration: Not applicable
Evaporation Rate: Probably very low at normal temperatures.
Critical Temperature: Not available

Other Physical Properties:
ACIDITY: Moderately strong acid: pKa1 = 3.14; pKa2 = 4.77; pKa3 = 6.39 at 20 deg C.(2)
VISCOSITY-DYNAMIC: 6.5 mPa.s (6.5 centipoises) at 25 deg C (50% aqueous solution) (10)
NOTE: When gently heated, the monohydrate loses water of hydration at 70-75 deg C (158-167 deg F) and melts in the range 135-152 deg C (275-306 deg F).
Rapid heating causes dehydration at 100 deg C (212 deg F) to form crystals that melt at 153-154 deg C.(2)


Normally stable. Decomposes (loses carbon dioxide and water) at 175 deg C.(2,11)

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. perchloric acid, peroxides, chromates, nitric acid) - mixtures may react violently if heated. Increased risk of fire.(12)
STRONG REDUCING AGENTS (e.g. phosphorus, tin (II) chloride, metal hydrides) - may react vigorously or violently.(12)
STRONG BASES (including alkalis such as sodium hydroxide) - mixtures may generate heat and pressure. Increased risk of fire.(12)
METAL NITRATES - a mixture exploded during a vacuum evaporation procedure.(19)

Hazardous Decomposition Products:
Not available

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

Corrosivity to Metals:
Mildly corrosive to carbon steel, gray and nickel cast iron, copper, brass, aluminum and lead.(2,20) Not corrosive to type 316 stainless steel, copper- nickel, nickel-molybdenum, nickel-chromium-molybdenum and nickel-chromium-iron- molybdenum alloys.(20,21) High acid concentrations may severely corrode 304 stainless steels, which are also not recommended for use at elevated temperatures. 316 stainless steel is the recommended material for handling citric acid.(2,21)

Stability and Reactivity Comments:
Citric acid is corrosive to normal concrete and should not be used with nylon, polycarbonates, polyamides, polyimides and acrylics. It may be used with fibre glass-reinforced polyester, polyethylene, polypropylene and polyvinyl chloride.(2O)


LD50 (oral, rat): 3000 mg/kg (4, unconfirmed); 11700 mg/kg (5, unconfirmed)
LD50 (oral, mouse): 5000 mg/kg (3, unconfirmed); 5040 mg/kg (5, unconfirmed)

Eye Irritation:

Little or no injury was observed in rabbits following application of a single drop of 2-5% citric acid solution in water. However, irreversible injury (permanent cloudiness of the cornea to severe dense opacification) was observed following 30-minute continuous contact with 0.5-2% solutions.(1) Severe irritation was observed in rabbits following application of citric acid in another study (details not available in English).(4, unconfirmed)

Skin Irritation:

Mild irritation was observed in rabbits following application of citric acid in one study (details not available in English).(4, unconfirmed) Irritation (degree unspecified), but not corrosive effects, were observed in other animal studies. Details of the procedures used and citric acid concentrations tested are not available.(2, unconfirmed)

Effects of Short-Term (Acute) Exposure:

No symptoms of kidney damage or other toxic effects were observed in dogs fed a daily dose of 1380 mg/kg for 112 to 120 days.(5)

Effects of Long-Term (Chronic) Exposure:

No harmful effects except a slight increase in wearing away of the teeth were observed in rats fed 1.2% citric acid for 90 weeks.(5) A loss in body weight gain and reduced survival time were observed in mice fed a high concentration (5%) in the diet for an unspecified period of time.(6) Blood in the urine was observed in 4/5 rats fed a high concentration (4.8%) in the diet for 6 weeks. Decreased food intake and body weight gain was observed in animals fed 1.2-4.8%. No other harmful effects were observed.(7)

An increased rate of bladder cancer was observed in rats given citric acid (route of administration unspecified) following pre-treatment with oral doses of known bladder carcinogens (compared to those receiving only the known bladder carcinogens). However, these effects were judged to be a secondary effect of increased water consumption and not a direct effect of citric acid exposure.(5)

Reproductive Toxicity:
No harmful effects on reproduction were observed in rats fed 1.2% citric acid over 2 successive generations (90 weeks).(5) No effect on reproduction (litter size, still births, survival of young) was observed following feeding of female rats or mice with 5% citric acid in the diet prior to, during and subsequent to mating (duration unspecified).(8)


Selected Bibliography:
(1) Grant, W.M., et al. Toxicology of the eye. 4th edition. Charles C. Thomas, 1993. p. 411
(2) Blair, G., et al. Citric acid. In: Kirk-Othmer encyclopedia of chemical technology. 4th edition. Volume 6. John Wiley and Sons, 1993. p. 354-380
(3) Gosselin, R.E., et al. Clinical toxicology of commercial products. 5th edition. Williams and Wilkins, 1984. p. II-225
(4) RTECS record for citric acid. Last updated: 9704
(5) Katz, G.V., et al. Aliphatic carboxylic acids. In: Patty's industrial hygiene and toxicology. 4th edition. Edited by G.D. Clayton et al. Volume II. Toxicology. Part E. John Wiley and Sons, 1994. p. 3572, 3574, 3587-3589
(6) Wright, E., et al. Some effects of dietary citric acid in small animals. Food and Cosmetics Toxicology. Vol. 14 (1976). p. 561-564
(7) Yokotani, H., et al. Acute and subacute toxicological studies of TAKEDA- citric acid in mice and rats. Journal of the Takeda Research Laboratories. Vol. 30, no. 1 (1971). p. 25-31
(8) Wright, E., et al. The influence of a dietary citric acid supplement on the reproduction and survival time of mice and rats. Nutrition Reports International. Vol. 13, no. 6 (June, 1976). p. 563-566
(9) Ishidate, Jr., 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
(10) HSDB record for citric acid. Last revision date: 97/04/07
(11) Verhoff, F.H. Citric acid. In: Ullmann's encyclopedia of industrial chemistry. 5th revised edition. Vol. A 7. VCH Verlagsgesellschaft, 1985. p. 103-108
(12) The Sigma-Aldrich library of chemical safety data. Edition II. Volume 1. Sigma-Aldrich Corporation, 1988. p. 892B,D
(13) Her Majesty's Factory Inspectorate. Dust explosions in factories. Her Majesty's Stationary Office, [nd]
(14) Grossel, S.S. Safety considerations in conveying of bulk solids and powders. Journal of Loss Prevention in the Process Industries. Vol. 1 (April, 1988). p. 62-74
(15) Schwab, R.F. Dusts. In: Fire protection handbook. Edited by A.E. Cote. 18th edition. National Fire Protection Association, 1997. p. 4-174 to 4-181
(16) Dean, J.A. Lange's handbook of chemistry. 14th edition. McGraw-Hill, Inc., 1992. p. 1.146, 8.32
(17) Weast, R.C., ed. Handbook of chemistry and physics. 66th edition. CRC Press, 1985-1986. p. C-213, D-146, D-161
(18) Leo, A., et al. Partition coefficients and their uses. Chemical Reviews. Vol. 71, no. 6 (December, 1971). p. 573
(19) Urben, P.G., ed. Bretherick's handbook of reactive chemical hazards. 5th edition. Volume 2. Butterworth-Heinemann Ltd., 1995. p. 210-211
(20) Corrosion data survey: metals section. 6th edition. National Association of Corrosion Engineers, 1985. p. 40-9 to 41-9
(21) 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
(22) Forsberg, K., et al. Quick selection guide to chemical protective clothing. 4th ed. Van Nostrand Reinhold, 2002
(23) Schliemann-Willers, S., et al. Fruit acids do not enhance sodium lauryl sulphate-induced cumulative irritant contact dermatitis in vivo. Acta Dermato-Venereologica. Vol. 85 (2005). p. 206-210
(24) European Commission. Citric acid. IUCLID Dataset. European Chemicals Bureau, Feb. 2000. Available at: <>

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: 1997-12-24

Revision Indicators:
Resistance of materials for PPE 2004-04-06
Bibliography 2006-04-05
LFL/LEL 2006-10-05
UFL/UEL 2006-10-05

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