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CHEMINFO Record Number: 769
CCOHS Chemical Name: Tributyl phosphate

Phosphoric acid tributyl ester
Phosphoric acid tri-n-butyl ester
Tri-n-butyl phosphate
Phosphate de tributyle

Chemical Name French: Phosphate de tributyle
Chemical Name Spanish: Fosfato de tributilo
CAS Registry Number: 126-73-8
RTECS Number(s): TC7700000
EU EINECS/ELINCS Number: 204-800-2
Chemical Family: Organic phosphorous compound / organophosphate / phosphoric acid ester / phosphoric acid triester / trialkyl phosphate
Molecular Formula: C12-H27-O4-P
Structural Formula: H3C-(CH2)3-O-P(=O)-[0-(CH2)3-CH3]2


Appearance and Odour:
Clear, colourless, odourless liquid.(2,4,26)

Odour Threshold:

Warning Properties:
POOR - Odourless

Uses and Occurrences:
Used as a solvent and plasticizer for cellulose esters, lacquers and natural gums, plastics and vinyl resins; fire-proofing agent for nitrocellulose; an antifoam agent in ore separation processing; an extractant in nuclear fuel reprocessing; preparation of purified phosphoric acid; in the formulation of fire-resistant aircraft hydraulic fluids; solvent extraction in hydrometallurgy; extractant for metals and actinide separation; constituent of cotton defoliants; heat-exchange medium.(4,25)


Clear, colourless, odourless liquid. Can burn if strongly heated. During a fire, irritating/toxic phosphorus oxides may be generated. Exposure to mists or aerosols can probably cause irritation to the respiratory tract. Causes eye irritation.


Effects of Short-Term (Acute) Exposure

Tributyl phosphate (TBP) has a very low vapour pressure and does not easily form a vapour at room temperature. Therefore, inhalation exposures are not expected unless TBP is heated or misted. Based on animal and limited human information, exposure to mists or aerosols can probably cause irritation of the nose and throat. Severe exposures may result in signs of central nervous system (CNS) depression, such as headache, nausea, dizziness and incoordination.
An unpublished report indicates that the heated material may result in eye and respiratory irritation in humans.(1) Another report indicates that workers have complained of nausea and headaches when exposed to 15 mg/m3.(2) There are insufficient details available to evaluate these reports and it is not clear whether the reported effects were from short or long-term exposures.

Skin Contact:
TBP is expected to produce only slight or mild skin irritation, based on animal information. Animal evidence also suggests that TBP can be absorbed through the skin, but harmful effects are not expected to develop from this route of exposure. There is no human information available.

Eye Contact:
TBP is may produce moderate eye irritation, based on animal information. There is no human information available.

TBP has low oral toxicity, based on animal evidence. Ingestion of very large doses may produce signs of central nervous system (CNS) depression, as described in "Inhalation" above. There is no human information available. Ingestion is not a typical route of occupational exposure.

Effects of Long-Term (Chronic) Exposure

SKIN CONTACT: Long-term skin contact may produce dry, cracked, red skin (dermatitis), based on animal evidence.

INHALATION: There is not enough information available to evaluate one report that workers have complained of nausea and headaches when exposed to 15 mg/m3.(2) It is unclear whether the effects are from short or long-term exposure, or whether there were any other exposures which may have caused the effects described.

INGESTION: Significant harmful effects have been observed in animals studies following long-term ingestion of TBP. Ingestion is not a typical route of occupational exposure.


No human or animal information was located.

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:
There is no human information available. Teratogenicity and embryotoxicity have not been observed in animal studies, even in the presence of significant maternal toxicity.

Reproductive Toxicity:
There is no human information available. No reproductive effects were observed in a two-generation rat study, despite significant toxicity in the exposed animals.

There is no human or animal information available. Positive results were observed in one short-term test using bacteria. However, most other tests have reported negative results.

Toxicologically Synergistic Materials:
There is no information available.

Potential for Accumulation:
TBP does not accumulate in the body. It is readily absorbed from the gastrointestinal tract. Some absorption also occurs through the skin. TBP is metabolized to give phosphorus-containing products and also, oxidation of the butyl groups occurs to produce carboxylic acids and ketones. TBP metabolites are excreted predominantly in the urine, with smaller amounts in the feces and expired air (carbon dioxide). In studies with rats using labelled TBP, 50% was eliminated in the urine within 24 hours, 10% in the expired air and 6% in the feces. The total elimination after five days was 82%.(4)


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

Skin Contact:
As quickly as possible, flush with lukewarm, gently flowing water for at least 5 minutes or until the chemical is removed. If irritation persists, repeat flushing. Obtain medical advice. 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, while holding the eyelid(s) open. Take care not to rinse contaminated water into the unaffected eye. Obtain medical attention immediately.

NEVER give anything by mouth if the victim is rapidly losing consciousness, is unconscious or convulsing. Have victim rinse mouth thoroughly with water. DO NOT INDUCE VOMITING. Have victim drink 240-300 mL (8-10 oz) of water to dilute material in the stomach. If vomiting occurs naturally, have victim rinse mouth and repeat administration of water. 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 expect 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:
146 deg C (295 deg F) (open cup) (27)

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

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

Autoignition (Ignition) Temperature:
Greater than 482 deg C (Greater than 900 deg F) (17)

Sensitivity to Mechanical Impact:
Not sensitive. Stable material.

Sensitivity to Static Charge:
Information not available. Probably will not accumulate static charge. The electrical conductivity of phosphoric acid esters is probably high.

Combustion and Thermal Decomposition Products:
Phosphorus oxides

Fire Hazard Summary:
This material can burn if strongly heated. During a fire, irritating/toxic phosphorus oxides may be generated. Closed containers may explode in the heat of the fire.

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

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.
Water or foam may cause frothing. The frothing may be violent and could endanger personnel close to the fire. However, a water spray or fog that is carefully 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 spray or fog can be used to absorb heat, keep containers cool and protect exposed material. If a leak or spill has not ignited, use water spray to disperse the vapours and protect personnel attempting to stop a leak. Water spray may be used to flush spills away from ignition sources. Solid streams of water may be ineffective and spread material.
Tributyl phosphate and its decomposition products, such as phosphorous oxides, are hazardous to health. Do not enter without wearing specialized protective equipment suitable for the situation. Firefighter's normal protective equipment (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 - Health: 3 - Short exposure could cause serious temporary or 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: 266.32

Conversion Factor:
1 ppm = 10.87 mg/m3; 1 mg/m3 = 0.092 ppm at 25 deg C (calculated)

Physical State: Liquid
Melting Point: Below -80 deg C (-112 deg F) (2,26,28)
Boiling Point: 289 deg C (552.2 deg F) (decomposes) (2,4,26)
Relative Density (Specific Gravity): 0.978 at 20 deg C (4); 0.976 at 25 deg C (2,26) (water = 1)
Solubility in Water: Slightly soluble (606 mg/100 mL) (26,28)
Solubility in Other Liquids: Soluble in all proportions with most organic solvents.(4,26)
Coefficient of Oil/Water Distribution (Partition Coefficient): Log P(oct) = 3.99-4.01 (4)
pH Value: Not available
Vapour Density: 9.2 (air=1) (25,28)
Vapour Pressure: 5.3 x 10(-4) kPa (0.004 mm Hg) (29); 0.009 kPa (0.0675 mm Hg) (2,4) at 25 deg C.
Saturation Vapour Concentration: 5.3 ppm (0.0005%); 88.8 ppm (0.0089%) at 25 deg C (calculated)
Evaporation Rate: Not available
Critical Temperature: Not available

Other Physical Properties:
SAYBOLT VISCOSITY: 38.6 sec at 29.4 deg C (25)
VISCOSITY-DYNAMIC: 3.7 mPa.s (3.7 centipoises) (14,15,18)
SURFACE TENSION: 29 mN/m (29 dynes/cm) at 20 deg C (4)


Decomposes when heated above its boiling point (289 deg C) forming phosphoric acid and butene, or on contact with warm water forming phosphoric acid and butanol.(2,28)

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.

OXIDIZING AGENTS (e.g. peroxides, nitrates, permanganates) - violent reaction. Risk of fire and explosion.(28,29)
ALKALIS (e.g. sodium hydroxide) - decomposes tributyl phosphate forming phosphoric acid and butanol.(29)

Hazardous Decomposition Products:
Phosphoric acid.

Conditions to Avoid:
Temperatures above 146 deg C, contact with water.

Corrosivity to Metals:
Not corrosive to cast iron and steel and probably not corrosive to stainless steel.(30)


LC50 (rat): 7000 mg/m3 (4-hour exposure) (aerosol); cited as 28.0 mg/L (1-hour exposure) (5)

LD50 (oral, male rat): 1390 mg/kg (6)
LD50 (oral, female mouse): 900 mg/kg (6)
LD50 (oral, mouse): reported as 400-800 mg/kg (1) (Note: Deaths occurred at 800 mg/kg, but no information is provided for 400 mg/kg.)

LD50 (dermal, rabbit): greater than 3100 mg/kg (7)

Eye Irritation:

Application of 0.1 mL of undiluted tributyl phosphate (TBP) produced moderate irritation in rabbits (scored not over 5.0, where 5.0 is severe irritation; grade 3/10).(8) Two unconfirmed studies have reported slight or mild irritation in rabbits.(4,9)

Skin Irritation:

Slight irritation was observed in rabbits following testing according to OECD guidelines (4-hour exposure).(4,9) Application of 0.1 g, under cover, for 24 hours, produced mild irritation in rabbits.(10) An unconfirmed study reported severe irritation in rabbits.(4,9)

Effects of Short-Term (Acute) Exposure:

Irritation of the nose and lungs and loss of coordination have been observed in rats exposed to lethal aerosol concentrations. Autopsy has shown lung and liver injury.(5,11)

Skin Contact:
No signs of toxicity were observed in rats exposed dermally to an unspecified dose for 5 days. The skin was dead on the surface and healing was rapid.(12)

High oral doses (up to 1000 mg/kg) have produced central nervous system (CNS) effects, such as laboured breathing, hypersalivation, general weakness, tremors, reduced activity and convulsions, in rats and mice.(1,10,12,13) One study also showed evidence of liver injury in rats exposed to sublethal doses.(10) One long-term study in rats indicated that TBP may be aspirated into the lungs following ingestion.[13]

Effects of Long-Term (Chronic) Exposure:

Long-term oral exposure has produced decreased body weight, increased liver, kidney, brain and testicular weights, effects on spleen weight and nervous system (e.g. reduced nerve conduction velocity) effects, liver and kidney injury and urinary bladder hyperplasia in rats.(14-18,19,20) Hyperplasia of the epithelium of the urinary bladder was observed in rats exposed to doses as low as 50-70 mg/kg/day for 70-90 days.(19,20) Kidney and liver effects were also observed in adult rats exposed to 20 or 70 mg/kg/day in a two-generation reproductive study.(20) In one other rat study, deaths were observed at 100 and 300 mg/kg/day for 13 weeks. However, the authors believed that at least some of the deaths were associated with aspiration of TBP-contaminated saliva. No other treatment-related pathological findings were observed.(13)

Skin Sensitization:
After dermal treatment of 14 guinea pigs in a "droplet test", 6 animals showed skin sensitizing effects.(1) There are insufficient details available to evaluate this report.

Teratogenicity, Embryotoxicity and/or Fetotoxicity:
No significant embryotoxicity or teratogenicity was observed in rats following oral administration, despite maternal toxicity. A fetotoxic effect was observed in the presence of maternal toxicity.(21) A two-generation rat study showed postnatal effects (reduced pup weight), in the presence of significant adult toxicity.(20) Two other studies were not evaluated due to inadequate reporting of the results and/or a high incidence of maternal mortality.(22,23)

Reproductive Toxicity:
In a two-generation study, reproductive toxicity was not observed in rats despite consistent and persistent adult toxicity in both sexes and generations.(20)


Selected Bibliography:
(1) Laboratory of Industrial Medicine, Kodak Industrial Chemistry Laboratory. Toxicity and health hazard study for tri-n-butyl phosphate with cover letter dated 081186. Eastman Kodak Company, Aug. 1986. EPA/OTS 86860000118. NTIS/OTS 0510265.
(2) Tributyl phosphate. In: Documentation of threshold limit values and biological indices. 6th ed. American Conference of Governmental and Industrial Hygienists, 1991. p. 1600-1601
(3) Forsberg, K., et al. Quick selection guide to chemical protective clothing. 4th ed. Van Nostrand Reinhold, 2002
(4) International Programme on Chemical Safety. Tri-n-butyl phosphate. Environmental health criteria 112: World Health Organization, 1991
(5) Food and Drug Research Laboratories, Inc. Acute inhalation study in rats with Kronitex TBP with cover letter dated 080886. FMC Corporation, Aug. 1986. EPA/OTS 86860000114. NTIS/OTS 0510262.
(6) Mitomo, T., et al. Toxicological studies on tributyl phosphate. (I) Acute and subacute toxicities. Journal of Toxicological Sciences. Vol. 5 (1980). p. 270-271
(7) Johannsen, F.R., et al. Evaluation of delayed neurotoxicity and dose-response relationships of phosphate esters in the adult hen. Toxicology and Applied Pharmacology. Vol. 41, no. 2 (Aug. 1977). p. 291-304
(8) Carpenter, C.P., et al. Chemical burns of the rabbit cornea. American Journal of Ophthalmology. Vol. 29 (1946). p. 1363-1372
(9) Berufsgenossenschaft der chemischen Industrie. Tributyl phosphate. In: Toxicological evaluations. I: Potential health hazards of existing chemicals. Springer Verlag, 1990. p. 297-310
(10) Haskell Laboratory for Toxicology and Industrial Medicine. Toxicity of tributyl phosphate, "Alkaterge" C, and "Foamex" with cover letter dated 070286. E.I. Dupont Denemours and Company, July 1986. EPA/OTS 868600078. NTIS/OTS 0510228.
(11) Mellon Institute of Industrial Research, University of Pittsburgh. Range finding tests on tributyl phosphate with cover letter dated 081186. Union Carbide Corporation, Aug. 1986. EPA/OTS 86860000125. NTIS/OTS 0510270.
(12) Sabine, J.C., et al. Anticholinesterase activity of tributyl phosphate. A.M.A. Archives of Industrial Hygiene and Occupational Medicine. Vol. 6 (Aug. 1952). p. 174-177
(13) Healy, C.E., et al. Acute and subchronic neurotoxicity studies with tri-n-butyl phosphate in adult Sprague-Dawley rats. American Industrial Hygiene Association Journal. Vol. 56, no. 4 (Apr. 1995). p. 349-355
(14) Laham, S., et al. Effects of tri-n-butyl phosphate on the peripheral nervous system of the Sprague-Dawley rat. Drug and Chemical Toxicology. Vol. 6, no. 4 (1983). p. 363-377
(15) Laham, S., et al. Subacute oral toxicity of tri-n-butyl phosphate in the Sprague-Dawley rat. Journal of Applied Toxicology. Vol. 4, no. 3 (June 1984). p. 150-154
(16) Oishi, H., et al. Toxicity of tri-n-butyl phosphate with special reference to organ weights, serum components and cholinesterase activity in male rats. Toxicity Letters. Vol. 6 (1980). p. 81-85
(17) Oishi, H., et al. Toxicity of several phosphoric acid esters in rats. Toxicity Letters. Vol. 13, nos. 1 and 2 (1982). p. 29-34
(18) Laham, S., et al. Induction of urinary bladder hyperplasia in Sprague-Dawley rats orally administered tri-n-butyl phosphate. Archives of Environmental Health. Vol. 40, no. 6 (Nov./Dec. 1985). p. 301-306
(19) Cascieri, T., et al. Subchronic toxicity study with tributyl phosphate in rats. Toxicologist. Vol. 5 (1985). p. 97
(20) Gerhart, J.M., et al. Two generation study of dietary tributyl phosphate (TBP) in CD rats. Toxicologist. Vol. 13, no. 1 (Mar. 1993). p. 76
(21) Noda, T., et al. Effects of tri-n-butyl phosphate on pregnancy in rats. Food and Chemical Toxicology. Vol. 32, no. 11 (Nov. 1994). p. 1031-1036
(22) Schroeder, R.E., et al. Developmental toxicity studies of tributyl phosphate (TBP) in the rat and rabbit. Teratology Society Abstracts. Vol. 43, no. 5 (May 1991). p. 455
(23) Bio/dynamics Inc. A supplement concerning the developmental toxicity study in rats with tributyl phosphate (Vol. I-II) (Final report) with attachments and cover letter dated 040391. Synthetic Organic Chemical Manufacturers Association, Inc. (SOCMA), Apr. 1991. EPA/OTS 89-910000223. NTIS/OTS 0526409-5.
(24) Gafiyeva, Z.A., et al. Determination of the mutagenic activity of tributyl phosphate on Salmonella typhimurium. Gigiena i Sanitariya. No. 9 (1986). p. 81-82. [English translation].
(25) HSDB record for tributyl phosphate. Last revision date: 96/06/27
(26) Budavari, S., et al. The Merck index: an encyclopedia of chemicals, drugs, and biologicals. 12th ed. Merck and Co, Inc., 1996. p. 1640
(27) Fire protection guide to hazardous materials. 13th ed. Edited by A.B. Spencer, et al. National Fire Protection Association, 2002. NFPA 325
(28) Chemical safety sheets. Kluwer Academic Publishers, 1991. p. 872
(29) NIOSH pocket guide to chemical hazards. National Institute for Occupational Safety and Health, June 1994. p. 314-315
(30) Corrosion data survey: metals section. 6th ed. National Association of Corrosion Engineers, 1985. p. 128-8 to 129-8
(31) European Communities (EC). Commission Directive 2004/73/EC. Apr 29, 2004
(32) Tributyl phosphate. SIDS initial assessment report for 12th SIAM. UNEP Publications, June 2001
(33) Food and Drug Research Labs. Acute toxicity screening for Kronitex TBP with cover letter dated 080886. FMC Corporation. Date produced: Jan. 30, 1976. EPA/OTS 86860000116. NTIS/OTS0510263
(34) Smyth, H.F. Jr., et al. The place of the range finding test in the industrial toxicology laboratory. Journal of Industrial Hygiene and Toxicology. Vol. 26, no. 8 (1944). p. 269-273

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: 1997-02-25

Revision Indicators:
Acute exposure (ingestion) 2000-08-01
First aid (ingestion) 2000-08-01
NFPA (health) 2003-04-16
Autoignition temp 2003-04-16
PEL-TWA final 2003-12-04
PEL transitional comments 2003-12-04
TLV comments 2004-01-04
Resistance of materials for PPE 2004-04-05
Bibliography 2004-11-11
EU classification 2004-11-11
EU risks 2004-11-11
EU safety 2004-11-11
Bibliography 2006-03-28

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