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CHEMINFO Record Number: 315
CCOHS Chemical Name: Zinc stearate

Stearic acid, zinc salt
Zinc distearate
Dibasic zinc stearate
Octadecanoic acid, zinc salt
Zinc octadecanoate
Stearate de zinc

Chemical Name French: Stéarate de zinc
Chemical Name Spanish: Estereato de cinc
CAS Registry Number: 557-05-1
RTECS Number(s): ZH5200000
Chemical Family: Saturated aliphatic carboxylic acid salt / saturated aliphatic monocarboxylic acid salt / alkanoic acid salt / stearate / distearate / zinc salt
Molecular Formula: C36-H70-O4-Zn
Structural Formula: (CH3(CH2)16CO2--Zn++


Appearance and Odour:
Fine, soft (not gritty), white powder. Slight, characteristic, fatty acid odour; hydrophobic (repels water).

Odour Threshold:
No information available

Warning Properties:
Information not available for evaluation

Zinc stearate is one of the salts of stearic acid. It has many similarities (properties and hazards) to other stearates. This record contains the available information specific for zinc stearate, supplemented with general information on stearate salts, which is applicable to zinc stearate. Commercial zinc stearate can contain zinc palmitate, zinc oxide (13-15%) and up to 2.0% free fatty acids (predominantly C16 and C18 acids) as impurities.(1)

Uses and Occurrences:
Used as a lubricant and mold releasing agent in rubber industry. Used in cosmetic and pharmaceutical dusting powders and water repellant ointments. Used as a filler in tablets. Used as a waterproofing agent for concrete, rock wool, paper and textiles. Also used as an antifoaming agent and a heat and light stabilizer.


Fine, soft, white powder with a slight, characteristic fatty acid odour. Hydrophobic (repels water). COMBUSTIBLE DUST. Can form explosive dust-air mixtures. Essentially non-toxic.


Effects of Short-Term (Acute) Exposure

The available information indicates that stearate salts such as zinc stearate are practically non-toxic. High concentrations of dust may cause coughing and mild temporary irritation.

Skin Contact:
Probably not irritating. No irritation or sensitization was seen in volunteers patch-tested with a 10% zinc stearate eye shadow formulation.(1) No irritation seen in an animal study.(1) It is probably not absorbed through the skin. There is one report of contact dermatitis due to zinc stearate exposure.(2)

Eye Contact:
Dust or mist may be slightly irritating. Minimal to no irritation seen in an animal study.(1) Some tearing, blinking and mild temporary pain may occur as material is rinsed from the eye by tears.

Practically non-toxic by ingestion. Animal data indicates that the oral toxicity is very low.

Effects of Long-Term (Chronic) Exposure

The death of a rubber worker from extensive scarring of the lungs (fibrosis) was attributed to exposure to zinc stearate for 29 years. No other cases have been reported to date. There is insufficient information to say with certainty that exposure to zinc stearate caused lung fibrosis in the rubber worker (3).
In general, long industrial experience with this material has shown that it can cause only minor, reversible health effects on the lungs (4). Long-term exposures to high concentrations of dust may cause increased mucous flow in the nose and respiratory system airways (5). This condition usually disappears after exposure ceases.


No information available. Probably not carcinogenic.

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 designated this chemical as not classifiable as a human carcinogen (A4).

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

Teratogenicity and Embryotoxicity:
No information available. Probably not teratogenic or embryotoxic.

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

No information available. Probably not mutagenic.

Toxicologically Synergistic Materials:
Information not available

Potential for Accumulation:
No specific information is available on the absorption, metabolism, distribution or elimination of zinc stearate. It can enter the body by inhalation or ingestion. Zinc is an essential element in the body. Zinc may accumulate temporarily, but not in the long term. Excess zinc is eliminated in the feces and urine. Studies on sodium stearate show that most of the stearate entering the body was eliminated as carbon dioxide in the expired air (about 38%) and retained in the body (about 56%). Negligible amounts of sodium stearate and its metabolites were eliminated in the urine and feces.(1)


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 exfess 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:
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:
A value of 277 deg C (530 deg F) (open cup) (6) has been reported; however, this not likely correct since other metal stearates do not form vapours.

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

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

Autoignition (Ignition) Temperature:
420 deg C (788 deg F) (6)

Sensitivity to Mechanical Impact:
Stable material

Combustion and Thermal Decomposition Products:
Zinc oxide, stearic acid

Flammable Properties:

Extinguishing Media:
Carbon dioxide, dry chemical powder, alcohol foam, polymer foam, water fog or mist.

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 zinc stearate. 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, to 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: 2 - Must be moderately heated or exposed to relatively high ambient temperatures before ignition can occur.
NFPA - Instability: 0 - Normally stable, even under fire conditions, and not reactive with water.


Molecular Weight: 632.33

Conversion Factor:
Not applicable

Physical State: Solid
Melting Point: 130 deg C (266 deg F) (pure).(1) Also reported as 126 deg C (259 deg F) and 132 deg C (270 deg F).(1)
Boiling Point: Not available
Relative Density (Specific Gravity): 1.095 (water = 1) (1)
Solubility in Water: Insoluble(1,10)
Solubility in Other Liquids: Insoluble in ethanol and diethyl ether. Soluble in benzene and acids (decomposed by dilute acids).(1)
Coefficient of Oil/Water Distribution (Partition Coefficient): Not available
pH Value: Neutral to moist blue litmus paper.(1)
Vapour Density: Not applicable
Vapour Pressure: Essentially zero
Saturation Vapour Concentration: Not applicable
Evaporation Rate: Not applicable
Critical Temperature: Not applicable


Normally stable at ambient temperatures. Decomposes when heated, giving off zinc oxide and acid vapours.(10)

Hazardous Polymerization:
Will 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.

ACIDS - react vigorously
ALKALIES - react vigorously

Hazardous Decomposition Products:
None known

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

Corrosivity to Metals:
Not corrosive


LC50 (rat): Greater than 200 mg/L; 1-hour exposure (50 mg/L - equivalent 4-hour exposure) (1, unconfirmed)

LD50 (oral, rat): Greater than 5000 mg/kg body weight (1, unconfirmed)

LD50 (dermal, rabbit): Greater than 2000 mg/kg body weight (in cosmetic formulation) (1, unconfirmed)

Eye Irritation:

Minimal to no irritation in rabbits (Draize test).(1)

Skin Irritation:

No irritation to intact or broken skin of rabbits after 24 hr exposure period (Draize test).(1)


Selected Bibliography:
(1) Final report of the safety assessment of lithium stearate, aluminum distearate, aluminum stearate, aluminum tristearate, ammonium stearate, calcium stearate, magnesium stearate, potassium stearate, sodium stearate, zinc stearate. Journal of the American College of Toxicology. Vol. 1, no. 2 (1982). p. 143-177
(2) Kilpikari, I. Occupational contact dermatitis among rubber workers. Contact Dermatitis. Vol. 8 (1982). p. 359-362
(3) Harding, H.E. Some enquiries into the toxicology of zinc stearate. British Journal of Industrial Medicine. Vol. 15 (1958). p. 130-132
(4) Documentation of the threshold limit values and biological exposure indices. 5th ed. ACGIH, 1986. p. 445, 536.1(86)-536.2(86)
(5) Wright, G.W. The pulmonary effects of inhaled inorganic dust. In: Patty's industrial hygiene and toxicology. 4th ed. Vol. 1, Part A. John Wiley & Sons, 1994. p. 307-309
(6) Fire protection guide to hazardous materials. 13th ed. Edited by A.B. Spencer, et al. National Fire Protection Association, 2002. NFPA 325
(7) 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
(8) Field, P. Explosibility assessment of industrial powders and dusts. Building Research Establishment, 1983
(9) 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
(10) Chemical safety sheets: working safely with hazardous chemicals. Kluwer Academic Publishers, 1991. p. 933
(11) NIOSH pocket guide to chemical hazards. NIOSH, June 1994. p. 338-339
(12) Occupational Safety and Health Administration (OSHA). Metal and Metalloid Particulates in Workplace Atmospheres (Atomic Absorption). In: OSHA Analytical Methods Manual. Revision Date: Oct. 31, 2001. Available at:
(13) Occupational Safety and Health Administration (OSHA). Metal and Metalloid Particulates in Workplace Atmospheres (ICP Analysis). In: OSHA Analytical Methods Manual. Revision Date: Oct. 31, 2001. Available at: <>
(14) Occupational Safety and Health Administration (OSHA). Qualitative X-Ray Flourescence Analysis of Workplace Substances. In: OSHA Analytical Methods Manual. Revision Date: Oct. 31, 2001. Available at: <>
(15) 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: <>
(16) 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: 1995-03-09

Revision Indicators:
Sampling 1996-01-01
Protective equipment 1996-01-01
EU class 1996-01-01
US transport 1996-01-01
Respiratory guidelines 1996-01-01
Resistance of materials 1996-01-01
TLV-TWA 1996-09-01
TLV comments 1996-09-01
NFPA (health) 2003-04-14
NFPA (flammability) 2003-04-14
PEL transitional comments 2003-11-06
Bibliography 2005-03-28
Sampling/analysis 2005-03-28
LFL/LEL 2006-10-04
UFL/UEL 2006-10-04

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