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CHEMINFO Record Number: 544
CCOHS Chemical Name: Stearic acid

Cetylacetic acid
1-Heptadecanecarboxylic acid
n-Octadecanoic acid
Octadecanoic acid
Acide octadécylique

Chemical Name French: Acide stéarique
CAS Registry Number: 57-11-4
RTECS Number(s): WI2800000
EU EINECS/ELINCS Number: 200-313-4
Chemical Family: Saturated aliphatic carboxylic acid / saturated aliphatic monocarboxylic acid / alkanoic acid
Molecular Formula: C18-H36-O2
Structural Formula: CH3-(CH2)16-C(=O)-OH


Appearance and Odour:
White or slightly yellow, crystals or powder, with a slight tallow-like odour.(17)

Odour Threshold:
Not available

Warning Properties:
Insufficient information for evaluation

Commercially available as a product containing 90% stearic acid with 7% palmitic acid (C16) and traces of other acids; mixtures containing larger amounts of palmitic acid are also available.

Uses and Occurrences:
Major use as ingredient of pharmaceuticals and cosmetics; in production of lubricants (e.g. metal stearates), soaps, plastics and coatings; rubber softeners; dispersing agent; stabilizer. Stearate esters are natural components of many animal and vegetable fats.


White or slightly yellow crystals or powder, with a slight tallow-like odour. COMBUSTIBLE DUST. Can form explosive dust-air mixtures. Essentially non-toxic.


Effects of Short-Term (Acute) Exposure

Stearic acid is low in toxicity. No reports are available on the effects of inhalation of stearic acid dust. However, it would probably cause little adverse effect on the lungs, and would probably not produce disease or toxic effects elsewhere in the body. High concentrations of dust may cause coughing and mild temporary irritation.

Skin Contact:
Stearic acid will probably not cause skin irritation. Daily application of 0.1 mL of a 25% solution in ethanol for 3 days (7), or 0.04 mL of a 1M in propanol solution for 10 days (8) did not produce irritation on any of 10 human subjects.

Eye Contact:
Dust or mist (solution) may be slightly irritating to the eyes. Some tearing, blinking and mild temporary pain may occur as material is rinsed from the eye by tears.

Stearic acid is a normal component of many foods and is very low in toxicity. Ingestion of very large doses may produce nausea and laxative effects. Animal data indicates that the oral toxicity is very low.

Effects of Long-Term (Chronic) Exposure

INGESTION: Substantial amounts of stearates are consumed as a normal part of the diet. There is no indication that this adversely affects health. In animal studies, high levels of stearic acid had only slight effects.

SKIN: Repeated or prolonged skin contact with dusts or concentrated solutions may cause dermatitis (drying, cracking and itching of skin).

SKIN SENSITIZATION: Application of 7% stearic acid in petrolatum to 26 human subjects did not cause any allergic reactions.(1)


No human information available. Stearic acid did not cause tumours in 2 animal studies (1), and reduced the incidence of chemically-induced tumours in 2 other animal studies.(1,3,4)

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:
No specific information available. Probably not teratogenic or embryotoxic.

Reproductive Toxicity:
No specific information available. Probably not a reproductive hazard.

No specific information available. No human or animal in vivo tests are available. It is probably not a mutagen.

Toxicologically Synergistic Materials:
No information available

Potential for Accumulation:
Stearic acid is a normal component of the body. It is stored in fatty tissues of the body, or broken down and excreted.


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

Skin Contact:
No health effects expected. Quickly and gently blot or brush away excess chemical. Wash gently and thoroughly with water and non-abrasive soap for 5 minutes or until chemical is removed.

Eye Contact:
Do not allow victim to rub eye(s). Let the eye(s) water naturally for a few minutes. Have victim look right and left, and then up and down. If particle/dust does not dislodge, flush with lukewarm, gently flowing water for 5 minutes or until particle/dust is removed, while holding eyelid(s) open. If irritation persists, obtain medical attention. DO NOT attempt to manually remove anything stuck to eye(s).

If irritation or discomfort occur, obtain medical advice immediately.

First Aid Comments:
Consult a doctor and/or the nearest Poison Control Centre for all exposures except under 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:
196 deg C (385 deg F) (10)

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

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

Autoignition (Ignition) Temperature:
395 deg C (743 deg F) (11)

Sensitivity to Mechanical Impact:
Not sensitive. Stable material.

Combustion and Thermal Decomposition Products:
Incomplete combustion may also produce irritating fumes and acrid smoke.

Flammable Properties:

Extinguishing Media:
Carbon dioxide, dry chemical powder, alcohol foam, polymer foam, water fog or mist; Water or foam may cause frothing.(11)

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.
Avoid generating dust to minimize risk of explosion. Water spray, fog or foam can be used to extinguish fires involving stearic acid. Water or foam may cause frothing. However, a water spray or fog that is gently applied to the surface of the liquid, preferably with a fine spray or fog nozzle, will cause frothing that will blanket and extinguish the fire. In addition, water can be used in the form of spray or fog to prevent dust formation, absorb heat, keep containers cool and protect fire-exposed material. Solid streams of water may be ineffective and spread material.
As in any fire, wear self-contained breathing apparatus (SCBA), pressure-demand, (MSHA/NIOSH approved or equivalent) and full protective equipment (Bunker Gear).


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: 284.50

Conversion Factor:
Not applicable

Physical State: Solid
Melting Point: 69.6 deg C (157 deg F) (10)
Boiling Point: 376.1 deg C (709 deg F) (10); 383 deg C (721 deg F) (decomposes)
Relative Density (Specific Gravity): 0.847 at 70 deg C (water = 1) (liquid) (10)
Solubility in Water: Practically insoluble (0.3 mg/100 mL at 20 deg C) (6,10)
Solubility in Other Liquids: Very soluble in ether; soluble in acetone, chloroform, carbon tetrachloride, toluene, amyl acetate, carbon disulfide; hot ethanol; slightly soluble in benzene.(17)
Coefficient of Oil/Water Distribution (Partition Coefficient): Not available
pH Value: Not available
Vapour Density: Not applicable
Vapour Pressure: Very low at 25 deg C; 1 mm Hg at 173.7 deg C (17)
Saturation Vapour Concentration: Very low at 25 deg C
Evaporation Rate: Negligible
Critical Temperature: Not available

Other Physical Properties:
Weak acid. pKa = 5 (Ka = approximately 1X10(-5) (17)
VISCOSITY-DYANMIC: 9.87 centipoises (9.87 mPa.s) at 70 deg C (10)
SURFACE TENSION: 28.9 dynes/cm at 70 deg C (10)


Moderately stable. Exposure to light or air may cause a very slow breakdown forming low levels of hydroperoxides, which decompose to oxygen-containing products such as short chain (C1-C10) aldehydes and ketones (which produce a pungent, rancid odour) and hydroxy compounds.(15)

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.

REACTIVE METALS (e.g. aluminum) - The presence of contaminating peroxides in stearic acid may cause a violent or explosive reaction.
STRONG BASES (e.g. sodium hydroxide) - May generate heat. Increased risk of fire.
REDUCING AGENTS - May generate heat. Increased risk of fire.

Hazardous Decomposition Products:
Hydroperoxides, short chain (C1-C10) aldehydes and ketones, and hydroxy compounds may form during the slow breakdown of stearic acid in the presence of light or air.(15)

Conditions to Avoid:
Static charge, sparks, heat and other ignition sources, generation of dust.

Corrosivity to Metals:
Stearic acid is corrosive to brass.(16)


LD50 (oral, rat): greater than 5000 mg/kg (1, unconfirmed)
LD50 (oral, rat): greater than 10000 mg/kg (2)

LD50 (dermal, rabbit): greater than 5000 g/kg (1, unconfirmed)

Eye Irritation:

Application of 0.1 mg did not produce irritation in rabbits.(2)

Skin Irritation:

Application of 0.5 g did not produce irritation in rabbits in a standard Draize test.(2) Application of full strength acid to intact or abraded skin in a 24-hour closed-patch test produced moderate irritation in rabbits.(1)

Effects of Short-Term (Acute) Exposure:

A number of animal studies with high levels of saturated fat in the diet (containing 5-6% stearic acid) for 6 to 9 weeks showed changes to the blood system, such as decreased clotting time, increased cholesterol levels and increased risk of blood clots (thrombosis).(1)

Stearic acid was not tumourigenic in two studies.(1) Studies of the ability of stearic acid to increase or promote chemically-induced tumours showed negative or inconclusive results.(1) Other studies showed a decrease in chemically-induced tumours if stearic acid was injected or fed to animals.(3,4)


Selected Bibliography:
(1) Opdyke, D.L.J. Stearic acid. Foods and Cosmetics Toxicology. Special issue V : monographs on fragrance raw materials. Vol. 17, suppl. (Dec. 1979). p. 383-388
(2) Briggs, G.B., et al. Safety studies on a series of fatty acids. American Industrial Hygiene Association Journal. Apr. 1976. p. 251-253
(3) Habib, N.A., et al. Stearic acid and carcinogenesis. British Journal of Cancer. Vol. 56 (1987). p. 455-458
(4) Sakaguchi, M., et al. Effect of dietary unsaturated and saturated fats on azoxymethane-induced colon carcinogenesis in rats. Cancer Research. Vol. 44 (Apr. 1984). p. 1472-1477
(5) Blevins, R.D., et al. Mutagenicity studies of twenty-five ingredients with the Salmonella/microsome test. Journal of Environmental Science and Health. Part A. Vol. 7, no. 2 (1982). p. 217-239
(6) Katz, G.V., et al. Aliphatic carboxylic acids. In: Patty's industrial hygiene and toxicology. 4th ed. Vol. II, Part E: Toxicology. John Wiley and Sons, Inc., 1994. p. 3526, 3530, 3567-3570
(7) Drill, V.A., et al. editors. Cutaneous toxicity. Academic Press Inc., (1977). p. 136
(8) Stillman, M.A., et al. Relative irritancy of free fatty acids of different chain length. Contact Dermatitis. Vol. 1 (1975). p. 65-69
(10) Kirk-Othmer encyclopedia of chemical technology. 4th ed. Vol. 5. John Wiley & Sons, 1993. p. 147-168
(11) Fire protection guide to hazardous materials. 13th ed. Edited by A.B. Spencer, et al. National Fire Protection Association, 2002. NFPA 325
(12) 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
(13) Field, P. Explosibility assessment of industrial powders and dusts. Building Research Establishment, 1983
(15) Kirk-Othmer encyclopedia of chemical technology. 3rd ed. Vol. 4. John Wiley & Sons, 1978. p. 845-853
(14) Schwab, R.F. Dusts. In: Fire protection handbook. Edited by A.E. Cote. 18th ed. National Fire Protection Association, 1991. p. 4-174 to 4-181
(15) Kirk-Othmer encyclopedia of chemical technology. 3rd ed. Vol. 4. John Wiley & Sons, 1978. p. 845-853
(16) Corrosion data survey. 6th ed. NACE, 1985. p. 122-123
(17) HSDB record for stearic acid. Date of last update: 9010
(18) National Institute for Occupational Safety and Health (NIOSH). Particulates Not Otherwise Regulated, Total. In: NIOSH Manual of Analytical Methods (NMAM(R)). 4th ed. Edited by M.E. Cassinelli, et al. DHHS (NIOSH) Publication 94-113. Aug. 1994. Available at: <>
(19) National Institute for Occupational Safety and Health (NIOSH). Particulates Not Otherwise Regulated, Respirable. In: NIOSH Manual of Analytical Methods (NMAM(R)). 4th ed. Edited by M.E. Cassinelli, et al. DHHS (NIOSH) Publication 94-113. Aug. 1994. 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: 1995-01-05

Revision Indicators:
TLV comments 1995-10-01
EEC classification 1996-05-01
US transport 1996-05-01
EEC number 1996-05-01
Resistance of materials 1996-05-01
TDG 1996-05-01
Bibliography 2005-03-14
Sampling/analysis 2005-03-14
Passive Sampling Devices 2005-03-14
LFL/LEL 2006-10-04
UFL/UEL 2006-10-04
Stability 2006-11-28
Hazardous decomposition products 2006-11-28

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