Phosphoric acid tributyl ester, also known as tributyl phosphate or TBP, is an industrial chemical.
TBP is used mainly in industrial settings in aviation hydraulic fluids as a flame retardant, as an extraction solvent for rare earth metals from ores, in the manufacture of uranium trioxide, as a defoaming agent, as a plasticizer and in hydraulic fluid and coatings. It is also found in some paints and brake fluids.
TBP is not manufactured in Canada, but is imported into Canada.
Prior to the assessment, TBP was identified as a potential concern to human health based on its classification by international organizations as a substance which was found to cause cancer in laboratory animals, and based on a moderate potential for exposure to Canadians.
TBP may be found in indoor air and drinking water in Canada.
Canadians may be exposed to TBP during use of certain consumer products containing TBP such as paints and brake fluid.
Exposure of the general population in Canada to TBP is expected to be low.
The Government of Canada has conducted a science-based evaluation of TBP, called a screening assessment.
The Government of Canada has concluded that TBP is not harmful to human health at current levels of exposure.
Based on the conclusion of the final screening assessment, no further action will be taken on TBP.
The final screening assessment report was published on August 22, 2009.
Because Canadians' exposure to TBP is expected to be low, the Government of Canada is not currently recommending specific actions by Canadians to reduce their exposure.
As a general precaution, Canadians are reminded to carefully follow safety warnings and directions when using products containing TBP.
Tributyl phosphate
TBP is a solvent and plasticizer for cellulose esters such as nitrocellulose and cellulose acetate. It forms stable hydrophobic complexes with some metals; these complexes are soluble in organic solvents as well as supercritical CO2. The major uses of TBP in industry are as a component of aircraft hydraulic fluid, brake fluid, and as a solvent for extraction and purification of rare-earth metals from their ores.
TBP finds its use as a solvent in inks, synthetic resins, gums, adhesives (namely for veneer plywood), and herbicide and fungicide concentrates.
As it has no odour, it is used as an anti-foaming agent in detergent solutions, and in various emulsions, paints, and adhesives. It is also found as a de-foamer in ethylene glycol-borax antifreeze solutions.[citation needed] In oil-based lubricants addition of TBP increases the oil film strength. It is used also in mercerizing liquids, where it improves their wetting properties. It can be used as a heat-exchange medium.TBP is used in some consumer products such as herbicides and water-thinned paints and tinting bases.
Nuclear chemistry[edit]
A 15–40% (usually about 30%) solution of tributyl phosphate in kerosene or dodecane is used in the liquid–liquid extraction (solvent extraction) of uranium, plutonium, and thorium from spent uranium nuclear fuel rods dissolved in nitric acid, as part of a nuclear reprocessing process known as PUREX.
The shipment of 20 tons of tributyl phosphate to North Korea from China in 2002, coinciding with the resumption of activity at Yongbyon Nuclear Scientific Research Center, was seen by the United States and the International Atomic Energy Agency as cause for concern; that amount was considered sufficient to extract enough material for perhaps three to five potential nuclear weapons.
