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CHEMINFO Record Number: 764
CCOHS Chemical Name: Aluminum sulfate octadecahydrate

Aluminium sulphate octadecahydrate
Aluminium sulfate octadecahydrate
Aluminum sulphate octadecahydrate
Cake alum
Dialuminum sulfate octadecahydrate
Papermaker's alum
Patent alum
Aluminum sulfate (non-specific name)

Chemical Name French: Sulfate d'aluminium octadécahydraté
Chemical Name Spanish: Sulfato de aluminio (no específico)
CAS Registry Number: 7784-31-8
Other CAS Registry Number(s): 10043-01-3 16828-12-9 16828-11-8
RTECS Number(s): WS5697000
Chemical Family: Aluminum and compounds / inorganic aluminum compound / aluminum salt / sulfate / alum
Molecular Formula: Al2-O12-S3.18H2O
Structural Formula: Al2(SO4)3.18H20


Appearance and Odour:
Colourless crystals (26)

Odour Threshold:
Probably odourless

Warning Properties:
NONE - aluminum sulfate octadecahydrate is probably odourless.

Technical grade aluminum sulfate octadecahydrate typically contains small amounts of impurities such as ferric oxide and an excess of aluminum oxide. Aluminum sulfate is commercially available as the anhydrous salt (Al2(SO4)3) (CAS 10043-01-3), the octadecahydrate (Al2(SO4)3.18H2O) (CAS 7784-31-8), the tetradecahydrate (Al2(SO4)3.14H2O) (CAS 16828-12-9) and the hexadecahydrate (Al2(SO4)3.16H2O) (CAS 16828-11-8). Several other hydrated forms are also commercially available, however there is very little specific information for these compounds. Aluminum sulfate octadecahydrate is available commercially as a dry ground product and as a solution in water (typically 33-50% by weight). This record presents information for solid aluminum sulfate octadecahydrate. Some information for the octadecahydrate may also be applicable to the other hydrated forms. For information on anhydrous aluminum sulfate, refer to CHEMINFO 171. For information on aluminum sulfate solutions, consult your material safety data sheet or the manufacturer/supplier of your product.

Uses and Occurrences:
It is used mainly in the pulp and paper industry and as a flocculating agent or coagulant in water and waste treatment; for clarifying and or purifying sewage and water; for clarifying fats, oils and petroleum products; as a leather tanning agent; as a pH stabilizer; applied to soils to make it less alkaline or to produce acid conditions; cement hardening accelerator; a mordant in dyeing; anticaking agent; a fire extinguisher, a flame retardant additive and a foaming agent in firefighting foams; for wood and cellulose treatment; as a chemical intermediate for aluminum compounds; in the preparation of antiperspirants, agricultural pesticides, pigments and viscose rayon; as a catalyst a fixing agent and a food additive; for pickling of seeds and waterproofing of concrete and cloth; as an absorbent for odour and gases; in the decontamination of radiocontaminated metal surfaces.(12,27-29)


Colourless, odourless crystals. Will not burn. Can decompose at high temperatures forming irritating and toxic sulfur dioxide and/or sulfur trioxide gases. Reacts with water to produce corrosive and toxic sulfuric acid. EYE IRRITANT. Causes severe eye irritation. May be irritating to the skin.


Effects of Short-Term (Acute) Exposure

Dusts or mists formed from solutions of aluminum sulfate octadecahydrate probably cause varying degrees of irritation of the nose and throat, based on pH. The dust becomes acidic following contact with moisture in the air or tissues of the respiratory tract. There is no human or animal information available.

Skin Contact:
Aluminum sulfate octadecahydrate is not a skin irritant based on animal information. The dust becomes acidic following contact with moisture on the skin and very mild irritation may result. No human information was located.
It has generally been considered that aluminum is very poorly absorbed through the skin.(1) Animal toxicity values for another water soluble aluminum salt indicates that toxic effects would not be expected following short-term skin contact.

Eye Contact:
Aluminum sulfate octadecahydrate is a severe eye irritant based on an animal study with aluminum sulfate hydrate. The dust becomes acidic following contact with moisture in the eye and moderate to severe irritation can result. One report, which provides no details about the type of exposure, indicates that a case of corneal injury has occurred following occupational exposure to aluminum sulfate (form and concentration unspecified). Healing occurred within 48 hours.(2)

Ingestion of large amounts can probably cause irritation of the lining of the stomach. There is no human or reliable animal information available for aluminum sulfate octadecahydrate. Ingestion is not a typical route of occupational exposure.

Effects of Long-Term (Chronic) Exposure

Nervous System:
A link between exposure to aluminum or aluminum compounds and Alzheimer's disease or other neurological diseases has been suggested. This link was suggested because of severe neurological effects which have been observed in patients receiving dialysis treatment (with dialysis fluids containing aluminum); effects seen in animals exposed to aluminum using non-occupational routes of exposure; case reports of neurological effects in individual workers; and findings of elevated aluminum levels in the brains of patients with neurological diseases. However, at present whether or not this association is a true effect is controversial and findings are inconsistent. Based on the available information, including studies of occupationally-exposed employees, recent reviewers have concluded that the evidence is inadequate to establish a link between occupational exposure to aluminum and specific effects on the nervous system or Alzheimer's disease, in normal, healthy workers.(1,3-7) One reviewer has concluded that there is a likely connection between long-term occupational exposure to aluminum and a specific effect, impaired co-ordination, but not other toxic effects on the nervous system or Alzheimer's disease.(8)

Prolonged or repeated contact with dust or irritating solutions may cause redness, dryness and itching of the skin (dermatitis).

Ingestion of large amounts of aluminum salts over a prolonged period may cause phosphate deficiency, based on animal and human information.(9) Prolonged ingestion of high doses (several grams per day) may result in osteomalacia (softening and bending of the bones).(10) There are no reports of these effects from occupational exposures to aluminum salts.


There is no animal or human information available for aluminum sulfate octadecahydrate. Negative results have been obtained for other aluminum salts in animal studies.(11)

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 not assigned a carcinogenicity designation to this chemical.

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

Teratogenicity and Embryotoxicity:
No conclusions can be drawn based on the limited animal information available. There is no human information available.

Reproductive Toxicity:
There is no human or animal information available.

No reliable studies using live animal and no human studies were located. A positive result was obtained in one test using cultured human cells. Negative results have been obtained in cultured mammalian cells and in bacteria.

Toxicologically Synergistic Materials:
There is no information available.

Potential for Accumulation:
Aluminum is absorbed only to a limited degree from either the gastrointestinal tract or the lungs, and is rapidly excreted in the urine. A certain amount of tissue uptake does occur and animal experiments have shown that it can accumulate in bone.(12,13) The degree of absorption of aluminum following ingestion has been shown to depend on the chemical form of the metal as well as the presence of other dietary constituents such as citrate, ascorbate and lactate.(14) Water solubility has not been found to be a good indicator of the degree of aluminum absorption for different aluminum compounds.(15)


If irritation occurs, remove source of contamination or have victim move to fresh air. If irritation persists, obtain medical attention immediately.

Skin Contact:
Immediately flush contaminated area with lukewarm, gently flowing water for at least 20 minutes, or until the chemical is removed. Under running water, remove contaminated clothing, shoes and leather goods (e.g. watchbands, belts). If irritation persists, repeat flushing and obtain medical attention. Completely decontaminate clothing, shoes and leather goods before re-use or discard.

Eye Contact:
Immediately flush the contaminated eye(s) with lukewarm, gently flowing water for 20 minutes or until the chemical is removed, holding the eyelid(s) open. Take care not to rinse contaminated water into the unaffected eye or onto the face. If irritation persists, obtain medical attention immediately.

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 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 combustible (will 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 metal.

Sensitivity to Static Charge:
Not applicable. Not combustible.

Combustion and Thermal Decomposition Products:
Forms aluminum oxide, sulfur dioxide and/or sulfur trioxide at temperatures variably reported as above 650 deg C (1200 deg F) or 760 deg C (1400 deg F).(27)

Fire Hazard Summary:
Aluminum sulfate octadecahydrate does not burn or support combustion. Heating it to high temperatures may produce corrosive and toxic sulfur dioxide and/or sulfur trioxide gases. Well-sealed containers may rupture violently when exposed to fire or excessive heat for sufficient time. Aluminum sulfate octadecahydrate dissolves in water forming sulfuric acid. Sulfuric acid is corrosive to metals and may form flammable hydrogen gas.(27)

Extinguishing Media:
Use fire extinguishing agents suitable for materials which are burning. Extinguish adjacent fires with suitable agents, such as dry chemical powder, carbon dioxide, alcohol foam polymer foam, water spray or fog.(30)

Fire Fighting Instructions:
Evacuate area and fight fire from a safe distance. Approach fire from upwind to avoid hazardous decomposition products.
Closed containers may rupture violently when exposed to the heat of the fire. If possible, isolate materials not yet involved in the fire, and move containers from the fire area if this can be done without risk, and protect personnel. Otherwise, fire-exposed containers or tanks should be cooled by application of water spray. Application should begin as soon as possible and should concentrate on any unwetted portions of the container. Take care not to get water inside container. Apply water from the side and from a safe distance until well after the fire is out. For a massive fire under these circumstances, it may be prudent to use unmanned hose holders or monitor nozzles. In any case, stay away from the ends of tanks involved in the fire.
The decomposition products of aluminum sulfate octadecahydrate are corrosive and 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: 666.45

Conversion Factor:
Not applicable

Physical State: Solid
Melting Point: 86.5 deg C (187.7 deg F) with decomposition (26)
Boiling Point: Not applicable. Decomposes.
Relative Density (Specific Gravity): 1.69 at 17 deg C (water = 1) (26,28)
Solubility in Water: Soluble (27.8 g anhydrous salt/100 g saturated solution at 25 deg C) (octadecahydrate) (28)
Solubility in Other Liquids: Insoluble in ethanol (26)
Coefficient of Oil/Water Distribution (Partition Coefficient): Not available
pH Value: Not available; 3.0-4.0 (5% in water at 25 deg C) reported for the hexadecahydrate.(31)
Vapour Density: Not applicable
Vapour Pressure: Probably practically zero
Saturation Vapour Concentration: Not applicable
Evaporation Rate: Probably zero
Critical Temperature: Not applicable


Normally stable. Aluminum sulfate reacts with water with the evolution of heat, forming sulfuric acid.(27)

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.

WATER - forms sulfuric acid.(27)
STRONG OXIDIZING AGENTS (e.g. chlorine, perchlorates, peroxides) - reaction may be violent. May give off sulfur dioxide.(30)
STRONG BASES (e.g. sodium hydroxide) - may react violently.(27)

Hazardous Decomposition Products:
Sulfuric acid.

Conditions to Avoid:
Generation of airborne dusts, moisture, high temperatures.

Corrosivity to Metals:
Dry aluminum sulfate is not corrosive to metals. In the presence of moisture, solid aluminum sulfate is corrosive to metals such as cast iron, steel and aluminum. It is not corrosive to types 304, 316 and 20-25-4.5 stainless steels and nickel-molybdenum, nickel-chromium-molybdenum and nickel- chromium-iron-molybdenum alloys.(32)


LD50 (oral, rat): greater than 9000 mg/kg (greater than 730 mg Al/kg) (16)
LD50 (oral, mouse): greater than 9000 mg/kg (greater than 730 mg Al/kg) (16); 980 mg Al/kg (cited as 0.98 g Al/kg; aluminum sulfate, form unspecified) (35)

Eye Irritation:

Application of 10 mg of aluminum sulfate hydrate produced severe eye irritation in rabbits. Corneal opacity, erythema, chemosis and discharge persisted until day 7 in some animals. Further follow-up was not reported.(36)

Skin Irritation:

No evidence of irritation was observed following application of a solution of 10% aluminum sulfate (form unspecified) in water (pH 3.0) to mice, rabbits and guinea pigs for 5 days.(17) Aluminum sulfate hydrate was applied to the skin of rabbits for 4 hours. No irritation was observed (scored 0) at 4 hours, 24 hours and 48 hours.(36)

Effects of Short-Term (Acute) Exposure:

In one study, harmful effects on the liver, kidney, bone and stomach were observed in rats following oral administration of 265-2120 mg/kg/day for up to 21 days.(18) The statistical significance of the results was not evaluated, and, therefore, no conclusions can be drawn from this study.

Teratogenicity, Embryotoxicity and/or Fetotoxicity:
No conclusions can be drawn from one mouse study with the anhydrous form of aluminum sulfate. An increase in the activity of a specific enzyme in the brain (choline aceyltransferase), but no effect on litter size, birth weight or behavioural or developmental test results, was observed in the offspring of mice fed 0.27 mg/day (approximately 13.5 mg/kg/day) anhydrous aluminum sulfate in drinking water for 8 days during pregnancy.(22) The significance of this observation is not known and no information concerning maternal toxicity was provided.

Positive results (chromosomal aberrations in bone marrow cells) were obtained in 5 male rats following oral administration of up to 2120 mg/kg/day aluminum sulfate octadecahydrate for up to 21 days.(23) However, evidence of severe toxicity was observed in the animals (a dose-related suppression of bone marrow cell division). Therefore, no conclusions can be drawn from this study.
A solution of aluminum sulfate in water produced positive results obtained in cultured human cells (leukocytes) (sister chromatid exchanges, micronuclei and chromosomal aberrations).(24) Negative results have been obtained in bacteria and cultured mammalian cells.(25)

NEUROLOGICAL EFFECTS: Positive and negative results have been obtained in behavioural tests administered to rats following ingestion of aluminum sulfate in its anhydrous or octadecahydrate form. However, a clear pattern of cause and effect has not been established and it is not possible to draw firm conclusions from the limited data available. No harmful effect on learning ability, activity level or body weight were observed in rats following inhalation of 2.04 mg/m3 anhydrous aluminum sulfate (mass median aerodynamic diameter 2.0 um) for 7 weeks.(19) Possible evidence of effects on the brain (decreased time to reach extinction criteria on a passive avoidance task) were observed in rats following ingestion of 0.3% aluminum (as aluminum sulfate octadecahydrate) in drinking water for 30 days. There were no effects on physical activity level or another measure of learning (acquisition of the passive avoidance task).(20) Impairment in one test designed to measure effects on the brain (cognitive function), but not in 3 other tests, was observed in rats following ingestion of 3.7% aluminum sulfate octadecahydrate in drinking water for 30 days.(21) Adverse effects on nerve cells in the brain (degeneration) were observed in rats following ingestion of 265-2120 mg/kg/day octadecahydrate for up to 21 days.(18) The statistical significance of these results was not evaluated and, therefore, it is not possible to draw any conclusions from this study.


Selected Bibliography:
(1) Agency for Toxic Substances and Disease Registry. Toxicological profile for aluminum. TP-91/01. US Department of Health and Human Services, July, 1992
(2) McLaughlin, R.S. Chemical burns of the human cornea. American Journal of Ophthalmology. Vol. 29, no. 11 (Nov. 1946). p. 1355-1362
(3) Industrial Disease Standards Panel. Interim Report to the Workers' Compensation Board on Aluminum. IDSP report of findings No. 9. Toronto, Ontario, May, 1992
(4) Wennberg, A. Neurotoxic effects of selected metals. Scandinavian Journal of Work, Environment and Health. Vol. 20, Special Issue (1994). p. 65-71
(5) Bertholf, R.L., et al. Aluminum. In: Handbook on toxicity of inorganic compounds. Edited by H.G. Seiler. Marcel Dekker, 1988. p. 56-64
(6) Martyn, C.N. The epidemiology of Alzheimer's disease in relation to aluminium. In: Aluminium in biology and medicine. Ciba Foundation Symposium 169. John Wiley and Sons, 1992. p. 69-86
(7) Sjogren, B., et al. Aluminium. Arbete och Halsa. Criteria documents from the nordic expert group 1992. Edited by B. Beije, et al. No.1 (1993)
(8) Doll, R. Review: Alzheimer's disease and environmental aluminium. Age and Ageing. Vol. 22, no. 2 (Mar. 1993). p. 138-153
(9) Krueger, G.L., et al. The health effects of aluminum compounds in mammals. CRC Critical Reviews in Toxicology. Vol. 13, no. 1 (1984). p. 1- 24
(10) Elinder, C.-G., et al. Aluminum. In: Handbook on the toxicology of metals. 2nd ed. Vol. II: Specific Metals. Edited by L. Friberg, et al. Elsevier, 1986. p. 2-25
(11) Leonard, A., et al. Mutagenicity, carcinogenicity and teratogenicity of aluminium. Mutation Research. Vol. 196, no. 3 (Nov. 1988). p. 247-257
(12) HSDB record for aluminum sulfate. Last revision date: 96/10/18
(13) Beliles, R.P. The metals. In: Patty's industrial hygiene and toxicology. Edited by G.D. Clayton, et al. 4th ed. Vol. II. Toxicology. Part C. John Wiley and Sons, Inc., 1994. John Wiley and Sons, 1994. p. 1880-1900
(14) Domingo, J.L. Reproductive and developmental toxicity of aluminum: a review. Neurotoxicology and Teratology. Vol. 17, no. 4 (July 1995). p. 515- 521
(15) Yokel, R.A. Benefit vs. risk of oral aluminum forms: antacid and phosphate binding vs. absorption. Drug and Chemical Toxicology. Vol. 12, nos. 3 and 4 (1989). p. 277-286
(16) Llobet, J.M., et al. Acute toxicity studies of aluminium compounds: antidotal efficacy of several chelating agents. Pharmacology and Toxicology. Vol. 60, no. 4 (Apr. 1987). p. 280-283
(17) Lansdown, A.B.G. Production of epidermal damage in mammalian skins by some simple aluminium compounds. British Journal of Dermatology. Vol. 89 (1973). p. 67-76
(18) Roy, A.K., et al. Similar effects in vivo of two aluminum salts on the liver, kidney, bone and brain of Rattus norvegicus. Bulletin of Environmental Contamination and Toxicology. Vol. 47, no. 2 (1991). p. 288-295
(19) Lewkowski, J.P., et al. Effects of chronic exposure of rats to automobile exhaust, H2SO4, SO2, Al2(SO4)3 and CO. In: Assessing toxic effects of environmental pollutants. Edited by S.D. Lee and J.B. Mudd. Ann Arbor Science, 1980. p. 187-217
(20) Connor, D.J., et al. Reversal of an aluminum-induced behavioral deficit by administration of deferoxamine. Behavioral Neuroscience. Vol. 103 (1989). p. 779-783
(21) Connor, D.J., et al. Chronic, oral aluminum administration to rats: cognition and cholinergic parameters. Pharmacology Biochemistry and Behaviour. Vol. 31, no. 2 (1988). p. 467-474
(22) Clayton, R.M., et al. Long-term effects of aluminum on the fetal mouse brain. Life Sciences. Vol. 51, no. 25 (1992). p. 1921-1928
(23) Roy, A.K., et al. Effects of aluminium salts on bone marrow chromosomes in rats in vivo. Cytobios. Vol. 66, no. 265 (1991). p. 105-111
(24) Roy, A.K., et al. Effects of aluminium sulphate on human leukocyte chromosomes in vitro. Mutation Research. Vol. 244, no. 2 (June 1990). p. 179-183
(25) Bhamra, R. K., et al. Trace elements aluminum, arsenic, cadmium, mercury and nickel. In: Environmental toxicants: human exposures and their health effects. Edited by M. Lippmann. Van Nostrand Reinhold Company, 1992. p. 575-632
(26) Weast, R.C., ed. Handbook of chemistry and physics. 66th ed. CRC Press, 1985-1986. p. B-69
(27) Emergency action guide for aluminum sulfate. Association of American Railroads, Mar. 1995
(28) Darragh, K.V.,et al. Aluminum compounds: aluminum sulfate and alums. In: Kirk-Othmer encyclopedia of chemical technology. 4th ed. Vol. 2. John Wiley and Sons, 1992. p. 330-338
(29) Helmboldt, O., et al. Aluminum compounds, inorganic: aluminum sulfate and alums. In: Ullmann's encyclopedia of industrial chemistry. 5th completely revised ed. Vol. A 1. VCH Verlagsgesellschaft, 1985. p. 527-534
(30) The Sigma-Aldrich library of chemical safety data. Ed. II. Vol. 1. Sigma-Aldrich Corporation, 1988. p. 115D
(31) Fluka chemica-biochemika 1995/96. Fluka Chemie AG, 1995. p. 76
(32) Corrosion data survey: metals section. 6th ed. National Association of Corrosion Engineers, 1985. p. 8-1 to 9-1
(33) NIOSH pocket guide to chemical hazards. NIOSH, June 1994. p.290-291, revised electronically 1996
(34) Forsberg, K., et al. Quick selection guide to chemical protective clothing. 4th ed. Van Nostrand Reinhold, 2002
(35) Ondreicka, R., et al. Chronic toxicity of aluminum in rats and mice and its effects on phosphorus metabolism. British Journal of Industrial Medicine. Vol. 23, no. 4 (1966). p. 305-312
(36) Stauffer Chemical Co. Initial submission: toxicology lab report T-4874 regarding primary dermal and eye irritation of aluminum sulfate hydrate in rabbits with cover letter dated 102392. Rhone-Poulenc Inc., 1974. EPA/OTS 88-920010792. NTIS/OTS 0571939.
(37) International Programme on Chemical Safety (IPCS). Aluminum. Environmental Health Criteria; No. 194. World Health Organization, 1997

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: 1997-11-25

Revision Indicators:
TDG 2002-06-11
Toxicological info 2003-05-13
WHMIS detailed classification 2003-05-13
WHMIS proposed classification 2003-05-13
WHMIS disclosure list 2003-05-13
WHMIS health effects 2003-05-13
OSHA hazcom 2003-05-13
Emergency overview 2003-05-13
First aid skin 2003-05-13
First aid eye 2003-05-13
Handling 2003-05-26
Resistance of materials for PPE 2004-04-06
Bibliography 2004-04-06
Short-term skin contact 2007-01-23
Short-term eye contact 2007-01-23
TLV proposed changes 2007-04-12

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