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CHEMINFO Record Number: 20
CCOHS Chemical Name: Sodium carbonate

Bisodium carbonate
Calcined soda
Carbonic acid, disodium salt
Carbonic acid, sodium salt
Chrystol carbonate
Disodium carbonate
Soda ash
Soda monohydrate
Sodium carbonate, anhydrous
Sodium carbonate monohydrate
Sodium carbonate decahydrate
Sodium carbonate heptahydrate
Solvay soda
Washing soda

Chemical Name French: Carbonate de sodium
CAS Registry Number: 497-19-8
Other CAS Registry Number(s): 5968-11-6 6132-02-1 56399-31-6
RTECS Number(s): VZ4050000
EU EINECS/ELINCS Number: 207-838-8
Chemical Family: Sodium and compounds / inorganic sodium compound / sodium salt / inorganic carbon compound / inorganic carbonic acid salt / inorganic carbonate
Molecular Formula: C-Na2-O3
Structural Formula: Na2.CO3 (anhydrous); Na2.CO3.H20 (mono); Na2.CO3.7H20 (hepta); Na2.CO3.10H20 (deca)


Appearance and Odour:
White to greyish crystals, powders or lumps; hygroscopic (absorbs moisture from the air).(16)

Odour Threshold:

Warning Properties:
POOR - odourless

Sodium carbonate exists in the anhydrous form (CAS 497-19-8) and in three hydrated forms; the monohydrate (CAS 5968-11-6); the heptahydrate (CAS 56399- 31-6); and the decahydrate (CAS 6132-02-1).(14) Commercial sodium carbonate consists of not less than 99.5% sodium carbonate, calculated on the anhydrous basis. Small amounts of arsenic (3 ppm maximum) and lead (20 ppm maximum) may be present as impurities. Other impurities include: sodium chloride, sodium sulfate, calcium carbonate, magnesium carbonate and sodium bicarbonate.(15)

Uses and Occurrences:
The main uses are in the manufacture of glass and in the production of other sodium compounds. It is also used in soaps, detergents and strong cleaning agents; water softening and flue gas desulfurization; in pulp and paper manufacture, in textile processing (bleaching of linen, hemp, cotton), petroleum refining, photography and aluminum production; various chemical processes; catalyst in coal liquefaction; as a food processing aid; food additive; reagent in analytical chemistry; and pH control.(16,17)


White to greyish, odourless crystals, powders or lumps. Hygroscopic. Non-combustible. EYE IRRITANT. Causes severe eye irritation. Solutions are CORROSIVE to aluminum.


Effects of Short-Term (Acute) Exposure

Sodium carbonate does not form a vapour, therefore exposure would be to dust or mists (if solutions are heated). Irritation of the nose, and throat may occur due to the irritant nature of sodium carbonate. Symptoms may include coughing, sneezing and difficulty breathing. There are no documented reports of these effects in people.

Skin Contact:
Sodium carbonate is a no to mild skin irritant, based on human and animal information. Application of a 50% solution of sodium carbonate to human skin produced no irritation on unbroken skin.(1) Sodium carbonate is corrosive to aluminum, but not human tissue.

Eye Contact:
The dust and concentrated solutions can cause moderate to severe irritation, based on animal information. There is no human information available. Sodium carbonate is corrosive to aluminum but not the eyes.

Sodium carbonate is not very toxic by ingestion, based on animal evidence. Ingestion may result in irritation of the mouth, throat and stomach due to the irritating nature of sodium carbonate. There is no human information available. Ingestion is not a typical route of occupational exposure.

Effects of Long-Term (Chronic) Exposure

INHALATION: Repeated or prolonged inhalation of sodium carbonate dust may be related to perforations of the nasal septum. In a group of 63 men with continuous exposure to soda ash dust (sodium carbonate), there were 5 cases of perforation and 2 cases of thinning of the nasal septum (19% incidence). Of 156 workers with fairly continuous exposure, there were 14 perforations, 5 impending perforations and 10 cases of atrophy of the nasal mucosa (18.6% incidence). With slight exposure there were 2 perforations and 11 cases of changes in the nasal mucosa (6.5% incidence). These effects were all without symptoms, i.e. the workers were not aware of any changes.(5)

SKIN: Patch testing of 67 trona miners and millers with 10% sodium carbonate was negative.(6) Long-term or repeated contact with sodium carbonate may result in dermatitis (red, dry, scaly skin) due to its hygroscopic nature.


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:
No human information available. One series of animal studies produced negative results in 3 species.(7)

Reproductive Toxicity:
No human or animal information available.

No information available.

Toxicologically Synergistic Materials:
No information available.

Potential for Accumulation:
Does not accumulate


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

Skin Contact:
Quickly blot or brush away excess chemical. Immediately flush with lukewarm, gently flowing water for at least 5 minutes or until the chemical is removed. Under running water, remove contaminated clothing, shoes and leather goods (e.g. watchbands, belts). Obtain medical attention immediately. Decontaminate clothing shoes or leather goods before re-use.

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

NEVER give anything by mouth if victim is rapidly losing consciousness, or is unconscious or convulsing. Have victim rinse mouth thoroughly with water. DO NOT INDUCE VOMITING. Have victim drink 240 to 300 mL (8 to 10 oz.) of water to dilute material in the stomach. Obtain medical attention immediately.

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 condition of use in the workplace.


Flash Point:
Non-combustible (does not burn)

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

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

Autoignition (Ignition) Temperature:
Not applicable

Sensitivity to Mechanical Impact:
Not sensitive. Stable material.

Sensitivity to Static Charge:
Not applicable. Not combustible.

Combustion and Thermal Decomposition Products:
Sodium oxide.(16)

Fire Hazard Summary:
Sodium carbonate and its decomposition products do not burn or support combustion. Closed containers may rupture violently if heated.

Extinguishing Media:
Does not burn. Use an extinguisher appropriate for the surrounding fire.

Fire Fighting Instructions:
Does not burn or support combustion.
As in any fire, firefighters may enter the area if positive pressure self- contained breathing apparatus (MSHA/NIOSH approved or equivalent) and full Bunker gear is worn.


NFPA - Comments:
NFPA has no listing for this chemical in Codes 49 or 325.


Molecular Weight: 105.99 (anhydrous); 124.01 (monohydrate); 232.10 (heptahydrate); 286.14 (decahydrate)

Conversion Factor:
Not applicable

Physical State: Solid
Melting Point: 851 deg C (1564 deg F) (anhydrous); 100 deg C (212 deg F) (mono); 32 deg C (90 deg F) (hepta); 34 deg C (93 deg F) (deca) (16,18)
Boiling Point: Decomposes
Relative Density (Specific Gravity): 2.53 (anhydrous); 2.25 (mono); 1.51 (hepta); 1.47 (deca) at 20 deg C (water = 1) (14)
Solubility in Water: Soluble (17 to 33 g/100 mL at 20 deg C) (16,18)
Solubility in Other Liquids: Soluble in glycerol; insoluble in ethanol, acetone, and diethyl ether.(17,18)
Coefficient of Oil/Water Distribution (Partition Coefficient): Not available
pH Value: 11.4 (1%); 11.6 (5%); 11.7 (10%) at 25 deg C (19)
Vapour Density: Not applicable
Vapour Pressure: Negligible
Saturation Vapour Concentration: Not applicable
Evaporation Rate: Not applicable
Critical Temperature: Not applicable


Stable. Absorbs moisture and carbon dioxide from the air to form sodium bicarbonate.(14)

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.

ACIDS (e.g. hydrochloric acid, sulfuric acid) - reaction may be violent, generating heat and carbon dioxide gas.(16,20,21)
MAGNESIUM, PHOSPHORUS PENTOXIDE - mixture may cause explosion.(20,21)
AMMONIA and SILVER NITRATE - mixture explodes when warmed.(21)
ALUMINUM - explosion may occur, if aluminum is red hot.(20)
FLUORINE - ignites and burns fiercely.(20,21)
LITHIUM - burning lithium will liberate the more reactive sodium on contact.(21)
2,4,6-TRINITROTOLUENE - 1% sodium carbonate can reduce the explosion temperature.(21)

Hazardous Decomposition Products:
None reported

Conditions to Avoid:
Generation of dust, moisture

Corrosivity to Metals:
Sodium carbonate solutions (concentrations up to 35%) are corrosive to aluminum, lead, and zinc and zinc brasses at 21 deg C.(22,25-27) Solid sodium carbonate is corrosive to aluminum at 100% relative humidity and normal temperatures.(27) It is not clear if moisture must be present for corrosion to occur with anhydrous sodium carbonate.(16) Sodium carbonate solutions are not corrosive to other common metals, such as stainless steel (types 300 series, 400 series and Carpenter 20Cb-3) (10% to saturated solutions), carbon steel (types 1010 and 1020), nickel cast iron, nickel and nickel-base alloys, such as Monel, Hastelloy and Incoloy, copper, copper-nickel, bronze, aluminum bronze, silicon bronze, brass, Admiralty brass, titanium, tantalum and zirconium.(22,25-27)

Corrosivity to Non-Metals:
Sodium carbonate solutions attack plastics, such as acrylics; and elastomers, such as polyacrylates, and polysulfides.(26,28) These solutions do not attack most plastics, such as acrylonitrile-butadiene-styrene (ABS), chlorinated polyvinyl chloride (CPVC), nylon, polyethylene, polypropylene, polyvinyl chloride (PVC), and Teflon and other fluorocarbons; and most elastomers, such as nitrile Buna-N (NBR), ethylene-propylene (EPDM), Viton A and other fluorocarbons, butyl rubber, chloroprene, isoprene, natural rubber, neoprene and styrene-butadiene (SBR).(26,28)

Stability and Reactivity Comments:
Slowly decomposes at 400 deg C (752 deg F) producing carbon dioxide gas and sodium oxide.(16) Reacts with water vapour above 400 deg C to form sodium hydroxide and carbon dioxide.(14)


LC50 (male rat): 1150 mg/m3 (4-hour exposure); cited as 2300 mg/m3 (2-hour exposure) (91% sodium carbonate aerosol) (9)
LC50 (male guinea pig): 400 mg/m3 (4-hour exposure); cited as 800 mg/m3 (2- hour exposure) (95% sodium carbonate aerosol) (9)
NOTE: In the LC50 studies, exposure was to sodium combustion products, with concurrent exposure to up to 9% sodium hydroxide and/or up to 0.5% sodium bicarbonate. Therefore, these values do not reliably reflect the inhalation toxicity of sodium carbonate.

LD50 (oral, rat): 4090 mg/kg (8)

Eye Irritation:

Sodium carbonate is a severe eye irritant.

Application of 0.1 mL undiluted anhydrous sodium carbonate powder (pH 11.3) produced severe irritation in rabbits.(4) Application of several drops of 10% sodium carbonate (pH 10.7) followed by irrigation in 30 seconds resulted in no detectable injury in rabbits.(11) Standard Draize testing with 100 mg (for 24 hours) produced moderate irritation while 50 mg (for unspecified time) produced severe irritation in rabbits.(2; originals unavailable in English)

Skin Irritation:

Sodium carbonate is a mild skin irritant.

Application of 2 mL of a 25% solution, under cover, to intact or broken, rabbit or guinea pig skin resulted in mild irritation in all cases.(3) Application of a 50% solution, under cover, to intact or broken, rabbit or guinea pig skin resulted in no effect on intact skin. Barely noticeable (negligible) irritation developed on broken guinea pig skin. Broken rabbit skin showed slight irritation.(1) Application of 500 mg for 24 hours to rabbit skin (standard Draize test) resulted in mild irritation.(2; original unavailable in English).

Effects of Short-Term (Acute) Exposure:

In LC50 experiments with sodium combustion products, all surviving animals showed signs of respiratory impairment (difficult breathing, wheezing) following exposure. Deaths were due to respiratory distress.(9) These studies involved concurrent exposure to other chemicals generated during combustion and do not reflect the short-term inhalation toxicity of sodium carbonate. In a poorly reported study, female rats were exposed in nose only chambers to 110 mg/m3 or 300 mg/m3 sodium carbonate.(12) No conclusions can be drawn from this study.

Effects of Long-Term (Chronic) Exposure:

Male rats were exposed to a 2% sodium carbonate solution aerosol (particle size less than 5 micrometres) for 3.5 months. At 10-20 mg/m3 there were no pronounced effects. At 70 mg/m3, reduced weight gain and cellular changes in the bronchial epithelium were observed.(13)

Teratogenicity, Embryotoxicity and/or Fetotoxicity:
Daily oral administration of up to 340 mg/kg to mice, up to 245 mg/kg to rats, and up to 179 mg/kg to rabbits for 10 to 13 days during pregnancy had no effect on implantations or on fetal or maternal survival. No increase in the incidence of abnormalities in either soft or skeletal tissues were observed.(7)


Selected Bibliography:
(1) Nixon, G.A., et al. Interspecies comparisons of skin irritancy. Toxicology and Applied Pharmacology. Vol. 31 (1975). p. 481-490
(2) RTECS record for sodium carbonate. Date of last update: 9507
(3) Roudabush. R.L., et al. Comparative acute effects of some chemicals on the skin of rabbits and guinea pigs. Toxicology and Applied Pharmacology. Vol. 7 (1965). p. 559-565
(4) Murphy, J.C., et al. Ocular irritancy responses to various pHs of acids and bases with and without irrigation. Toxicology. Vol. 23, no. 4 (1982). p. 281-291
(5) Archibald, R.McL. Perforation of the nasal septum due to soda ash. British Journal of Industrial Medicine. Vol. 11 (1954). p. 31-37
(6) Rom, W.N., et al. A study of dermatitis in trona miners and millers. Journal of Occupational Medicine. Vol. 25, no. 4 (Apr. 1983). p. 295-299
(7) Morgareidge, K. Teratologic evaluation of sodium carbonate in mice, rats and rabbits. PB-234 868. National Technical Information Service, March, 1974
(8) Marhold, J.V. Sbornik Vysledku Toxixologickeho Vysetreni Latek a Pripravku (1972). p. 8
(9) Busch, R.H., et al. Pathologic effects in rodents exposed to sodium combustion products. Environmental Research. Vol. 31, no. 1 (1983). p. 138-47
(10) Zwicker, G.M., et al. Toxicity of aerosols of sodium reaction products. Journal of Environmental Pathology and Toxicology. Vol. 2 (1979). p. 1139-1150
(11) Grant, W.M., et al. Toxicology of the eye. 4th ed. Charles C. Thomas, 1993. p. 1296-1297
(12) Pagano, P., et al. Morphological injuries and kinetic clearance affectation in trachea of rats exposed to sodium combustion products. Journal of Aerosol Science. Vol. 18, no. 6 (1987). p. 729-732
(13) Reshetyuk, A.L., et al. Toxicity of aerosols of soda and "sulfonol" solutions. Gigiena i sanitarija. Vol. 33 (1968). p. 128-131. (English translation: NIOSHTIC Control Number: 00002187)
(14) Thieme, C. Sodium carbonates. In: Ullmann's encyclopedia of industrial chemistry. 5th completely revised ed. Vol. A 24. VCH Verlagsgesellschaft, 1993. p. 299-316
(15) Final report on the safety assessment of sodium sesquicarbonate, sodium bicarbonate, and sodium carbonate. Journal of the American College of Toxicology. Vol. 6, no. 1 (1987). p. 121-138
(16) Emergency Action Guide for sodium carbonate. Association of American Railroads. Oct. 1991
(17) HSDB record for sodium carbonate. Date of last update: 9501
(18) CRC Handbook of chemistry and physics. 64th ed. CRC press Inc., 1983-84. p. B-139
(19) Rauh, F. Sodium carbonate. In: Kirk-Othmer encyclopedia of chemical technology. 4th ed. Vol. 1. John Wiley and Sons, 1991. p. 1025-1039
(20) Fire protection guide to hazardous materials. 11th ed. National Fire Protection Association, 1994. NFPA 491
(21) Bretherick, L. Bretherick's handbook of reactive chemical hazards. 4th ed. Butterworths, 1990. p. 191-192
(22) Corrosion data survey: metals section. 6th ed. National Association of Corrosion Engineers, 1985. p. 114-11 to 115-11
(23) European Economic Community. Commission Directive 93/72/EEC. Sept. 1, 1993
(24) Forsberg, K., et al. Quick selection guide to chemical protective clothing. 4th ed. Van Nostrand Reinhold, 2002
(25) Pruett, K.M. Chemical resistance guide to metals and alloys: a guide to chemical resistance of metals and alloys. Compass Publications, 1995. p. 314-325
(26) Schweitzer, P.A. Corrosion resistance tables: metals, nonmetals, coatings, mortars, plastics, elastomers and linings, and fabrics. 4th ed. Part C, P-Z. Marcel Dekker, Inc., 1995. p. 2637-2640
(27) Sodium carbonate. In: Handbook of corrosion data. 2nd ed. Edited by B.D. Craig, et al. ASM International, 1995. p. 721-724
(28) Pruett, K.M. Chemical resistance guide for elastomers II: a guide to chemical resistance of rubber and elastomeric compounds. Compass Publications, 1994. p. C-332 C-337
(29) National Institute for Occupational Safety and Health (NIOSH). Alkaline Dusts. 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: <>
(30) 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: <>
(31) 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: 1996-01-30

Revision Indicators:
Resistance of materials 1998-05-01
Short-term skin contact 2003-07-09
Short-term inhalation 2003-07-09
Short-term eye contact 2003-07-09
Short-term ingestion 2003-07-09
Toxicological info 2003-07-09
WHMIS detailed classification 2003-07-09
WHMIS proposed classification 2003-07-09
WHMIS health effects 2003-07-09
Emergency overview 2003-07-09
Handling 2003-07-09
Corrosivity to metals 2003-09-11
Corrosivity to non-metals 2003-09-11
Sampling/analysis 2005-03-12
Bibliography 2005-03-12
WHMIS classification comments 2005-07-11
Corrosivity to metals 2006-06-27

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