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CHEMINFO Record Number: 156
CCOHS Chemical Name: Aluminum hydroxide

Alumina hydrate
Alumina trihydrate
Aluminium hydroxide
Aluminum trihydroxide
Hydrated alumina
Trihydrated alumina

Chemical Name French: Hydroxyde d'aluminium
Chemical Name Spanish: Hidroxido de aluminio
CAS Registry Number: 21645-51-2
RTECS Number(s): BD0940000
EU EINECS/ELINCS Number: 244-492-7
Chemical Family: Aluminum and compounds / inorganic aluminum compound / hydroxide
Molecular Formula: Al-H3-O3
Structural Formula: Al(OH)3


Appearance and Odour:
Odourless, white crystals, powder or granules.(17,23)

Odour Threshold:

Warning Properties:
NONE - odourless and essentially non-irritating.

Aluminum hydroxide can exist and is commercially available in crystalline and gelatinous forms. Several crystalline forms are known including trihydroxides, gibbsite, bayerite and nordstrandite. The crystalline form is available as granules and powder in different particle sizes including coarse to ground to extra-fine precipitated grades. Common impurities include soda (sodium oxide), ferric oxide, silica and small amounts of titanium dioxide.(23,24) Aluminum hydroxide gels contain considerable amounts of water.(23)

Uses and Occurrences:
Used in the manufacture of iron-free aluminum, activated alumina, calcined alumina and aluminum salts, glass, fire clay, pottery and printing inks, waterproofing fabrics; antiperspirants, dentifrices, detergents, lubricants and packaging materials; as a filler for paper, plastics, rubber and cosmetics; in the preparation of alumina ceramics, refractories, polishing products, catalysts and catalyst supports; as an adsorbent, dessicant, flame retardant, and ion-exchanger; in chromatography; as an emulsifier, mordant in dyeing, and filtering medium; and as a soft abrasive for brass and plastics. Used as the gel or dried gel in pharmaceutical preparations, for example, as an antacid and antihyperphosphatemic.(17,23)


Odourless, white crystals, powder or granules. Will not burn. Essentially non-toxic following short-term exposure.


Effects of Short-Term (Acute) Exposure

Dusts are probably not irritating at low airborne concentrations. In general, high concentrations of dust may cause coughing and mild, temporary irritation.

Skin Contact:
Aluminum hydroxide dust is probably not irritating to the skin, based on limited animal information. There is no human information available.
It has been assumed that aluminum is very poorly absorbed through the skin, however, one recent report indicates that aluminum can be absorbed through the skin of mice following application of a water solution of one salt (aluminum chloride hexahydrate).(1,2)

Eye Contact:
Aluminum hydroxide dust is probably not irritating to the eye, except as a "foreign object". Some tearing, blinking and mild temporary pain may occur as the solid material is rinsed from the eye by tears. There is no human or animal information available.

Short-term oral toxicity is expected to be low.(3) Aluminum is a normal component of the human diet and the normal daily intake of various aluminum compounds is significant. In adults, daily aluminum intake has been estimated at about 9 to 14 mg (4) in one reference and 1 to 100 mg (mean 5 mg) (5) in another. It can be much higher (1000 mg or more (6)) in individuals taking antacids containing aluminum hydroxide. Animal toxicity values are not available since death occurs from intestinal blockage rather than systemic toxicity.(5) Ingestion is not a typical route of occupational exposure.

Effects of Long-Term (Chronic) Exposure

NEUROLOGICAL EFFECTS: 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.(1,4,5,7,8,9) 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.(10)

INGESTION: Ingestion of large amounts of aluminum salts over a prolonged period may cause phosphate deficiency, based on animal and human information.(11) This effect may eventually cause softening and bending of the bones (osteomalacia).(12) There are no reports of these effects from occupational exposures to aluminum salts.


Aluminum hydroxide was not carcinogenic in animal tests. There is no human 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:
Aluminum hydroxide has not produced harmful effects when administered orally to animals. However, when administered with common dietary constituents, such as citric acid, lactic acid and ascorbic acid, fetotoxicity was observed, in the presence of maternal toxicity. These studies indicate that aluminum absorption may be significantly enhanced by certain dietary constituents. There is no human information available.

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

There is no specific information available. In general, aluminum compounds have been found to be non-mutagenic in in vitro tests with both mammalian and non-mammalian cells.(11,13,14)

Toxicologically Synergistic Materials:
There is no information available.

Potential for Accumulation:
Aluminum hydroxide 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.(3) Ingestion of aluminum hydroxide has resulted in the accumulation of aluminum in the bones (femur and tibia) and brain (cerebral cortex) in rats and dogs.(28)


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

Skin Contact:
No health effects expected. If irritation occurs, gently blot or brush away excess chemical quickly. Wash gently and thoroughly with water and non-abrasive soap. If irritation persists, obtain medical advice.

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 the eyelid(s) open. If irritation persists, obtain medical attention. DO NOT attempt to manually remove anything stuck to the 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 condition of use in the workplace.


Flash Point:
Not applicable (non-combustible solid)

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:
Aluminum oxide

Fire Hazard Summary:
Aluminum hydroxide does not burn or support combustion.

Extinguishing Media:
Does not burn. Use extinguishing media appropriate for the surrounding fire.

Fire Fighting Instructions:
Not a fire hazard. Does not burn or support combustion.
No special firefighting procedures required.


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


Molecular Weight: 77.99

Conversion Factor:
Not applicable

Physical State: Solid
Melting Point: Loses water at 300 deg C (572 deg F) (25,26)
Boiling Point: Loses water at 300 deg C (25,26)
Relative Density (Specific Gravity): 2.42 (water = 1) (23,25,26)
Solubility in Water: Virtually insoluble (0.01 g/100 mL at 18 deg C). Forms gels on prolonged contact with water.
Solubility in Other Liquids: Insoluble in ethanol; soluble in acidic and alkaline aqueous solutions.(25,26)
Coefficient of Oil/Water Distribution (Partition Coefficient): Not applicable
pH Value: Approximately 4-10.5.*(23)
Vapour Density: Not applicable
Vapour Pressure: Essentially zero at room temperature
Saturation Vapour Concentration: Not applicable
Evaporation Rate: Not applicable
Critical Temperature: Not available

Other Physical Properties:
*Aluminum hydroxide is amphoteric, that is, it has the capacity to act either as an acid or a base.(23)


Normally stable. Absorbs carbon dioxide from the air.(24) Loses water at 300 deg C.(25,26)

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 ACIDS (e.g. sulfuric acid or hydrochloric acid) - vigorous or violent reaction.(24)
STRONG BASES (e.g. sodium hydroxide) - vigorous or violent reaction.
CHLORINATED RUBBER - react violently or explosively when heated, with or without hydrocarbon or chlorinated solvents.(24,27)

Hazardous Decomposition Products:
None reported

Corrosivity to Metals:
Not corrosive

Stability and Reactivity Comments:
Aluminum hydroxide has catalytic activity. Violent reactions may occur when it is combined with some materials such as chlorinated rubber at elevated temperatures.(24,27)


There are no standard animal toxicity values available.

Skin Irritation:

No evidence of irritation was observed following application of a 10% suspension of aluminum hydroxide in a non-irritating solution (0.2% Tween-80) (pH 7.2) to mice, rabbits and guinea pigs for 5 days.(18)

Effects of Short-Term (Acute) Exposure:

No harmful effects and no significant accumulation of aluminum in the bone were observed in rats fed 14470 ppm aluminum hydroxide (873 mg/kg/day) for 28 days.(19)

Effects of Long-Term (Chronic) Exposure:

In general, no adverse effects have been observed in experimental animals following ingestion of 1-2% aluminum hydroxide in the diet (duration of studies unspecified). Decreased growth, disturbances of calcium and phosphorus metabolism, muscle weakness and death have been observed following ingestion of higher dietary concentrations (greater than 2%).(20) No significant effects were observed in rats fed 156 mg/kg/day (reported as 40.2 umol/g aluminum, as aluminum hydroxide) for 178 or 208 days. When approximately the same dose was administered with sodium citrate dihydrate, temporary kidney effects were observed. Thus, indicated that the citrate increased absorption of the aluminum.(21) Subtle effects on metabolism (decreased serum triglyceride and increased phosphorus in the blood) were observed in rats fed 289 mg/kg/day (2000 ppm aluminum, as aluminum sulphate) for 67 days.(22) These high doses are not relevant to occupational exposures. NEUROLOGICAL EFFECTS: Decreased body weight and increased aluminum accumulation in the brain, but no neurological impairment, were observed in rat pups fed 41 mg/kg/day (reported as 14 mg Al/kg/day) for 60 days.(1)

No carcinogenic effects attributable to aluminum hydroxide have been observed following administration to experimental animals by various routes of exposure.(13)

Teratogenicity, Embryotoxicity and/or Fetotoxicity:
Aluminum hydroxide produced no evidence of embryotoxicity or fetotoxicity when administered orally to rats and mice. However, when it was administered with common dietary constituents, such as citric acid, lactic acid and ascorbic acid, fetotoxicity was observed, in the presence of maternal toxicity. These studies indicate that aluminum absorption may be significantly enhanced by certain dietary constituents. Other reports have indicated that very high oral exposure of rats to soluble aluminum compounds during pregnancy or lactation have caused fetotoxicity, in the absence of maternal toxicity.(15) It is not known if similar effects would be expected from aluminum or its insoluble compounds.


Selected Bibliography:
(1) Agency for Toxic Substances and Disease Registry (ATSDR). Toxicological profile for aluminum. TP-91/01. US Department of Health and Human Services, July 1992
(2) Anane, R., et al. Bioaccumulation of water soluble aluminium chloride in the hippocampus after transdermal uptake in mice. Archives of Toxicology. Vol. 69, no. 8 (1995). p. 568-571
(3) 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. p. 1880-1900
(4) Industrial Disease Standards Panel. Interim Report to the Workers' Compensation Board on Aluminum. IDSP report of findings No. 9. Toronto, Ontario, May 1992
(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) Kilburn, K.H. Pulmonary and neurologic effects of aluminum. In: Environmental and occupational medicine. Edited by W.N. Rom. Little, Brown and Company, 1992. p. 465-473
(7) Wennberg, A. Neurotoxic effects of selected metals. Scandinavian Journal of Work, Environment and Health. Vol. 20, Special Issue (1994). p. 65-71
(8) 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
(9) 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)
(10) Doll, R. Review: Alzheimer's disease and environmental aluminium. Age and Aging. Vol. 22, no. 2 (Mar. 1993). p. 138-153
(11) Krueger, G.L., et al. The health effects of aluminum compounds in mammals. Critical Reviews in Toxicology. Vol. 13, issue 1 (1984). p. 1-24
(12) 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
(13) Leonard, A., et al. Mutagenicity, carcinogenicity and teratogenicity of aluminium. Mutation Research. Vol. 196, no. 3 (Nov. 1988). p. 247-257
(14) 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
(15) Domingo, J.L. Reproductive and developmental toxicity of aluminum: a review. Neurotoxicology and Teratology. Vol. 17, no. 4 (July 1995). p. 515- 521
(16) 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
(17) HSDB record for aluminum hydroxide. Last revision date: 96/06/06
(18) 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
(19) Hicks, J.S., et al. Toxicity and aluminium concentration in bone following dietary administration of two sodium aluminium phosphate formulations in rats. Food and Chemical Toxicology. Vol. 25, no.7 (1987). p. 533-538
(20) Sorenson, J.R.L., et al. Environmental Health Perspectives. Vol. 8 (Aug. 1974). p. 3-95
(21) Ecelbarger, C.A., et al. Tissue aluminum accumulation and toxic consequences in rats chronically fed aluminum with and without citrate. Journal of Agricultural and Food Chemistry. Vol. 42, no. 10 (Oct. 1994). p. 2220-2224
(22) Sugawara, C., et al. Decrease of serum triglyceride in normal rat fed with 2000 ppm aluminum diet for 67 days. II. Feeding young and adult rats a sucrose diet with addition of aluminum hydroxide and aluminum potassium sulfate. Fundamental and Applied Toxicology. Vol. 10, no. 4 (1988). p. 616- 623
(23) Misra, C. Aluminum oxide (hydrated). In: Kirk-Othmer encyclopedia of chemical technology. 4th ed. Vol. 2. John Wiley and Sons, 1992. p. 317-330
(24) The Sigma-Aldrich library of chemical safety data. Ed. II. Vol. 1. Sigma-Aldrich Corporation, 1988. p. 113C
(25) James, A.M., et al. Macmillan's chemical and physical data. The Macmillan Press Ltd, 1992. p. 285
(26) Weast, R.C., ed. Handbook of chemistry and physics. 66th ed. CRC Press, 1985-1986. p. B-68
(27) Urben, P.G., ed. Bretherick's handbook of reactive chemical hazards. 5th ed. Vol. 2. Butterworth-Heinemann Ltd., 1995. p. 67
(28) International Programme on Chemical Safety. Aluminum. Environmental Health Criteria 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: 1997-10-29

Revision Indicators:
Potential for accumulation 2005-01-18

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