3. Uses and Releases of 2,4,6-TTBP
The only known use of 2,4,6-TTBP in Canada is as an antioxidant in hydrocarbon fluids such as gasoline, diesel fuel and jet fuel. Antioxidants are added to stabilize fuels and prevent the formation of engine-fouling residues. 2,4,6-TTBP is not manufactured in pure form, but is a co-product formed during the process used to make other antioxidants. It is typically present at concentrations between 11 and 15 percent in these antioxidants. In general, petroleum fuel additives are used at maximum concentrations well below 1% volume in the fuel. The resulting maximum concentration of 2,4,6-TTBP found in fuels would therefore be about 0.1%.
2,4,6-TTBP is not manufactured in Canada. It is imported through Canadian distributors from a small number of U.S. manufacturers/blenders as a component of antioxidants containing 2,4,6-TTBP. The only known end-users are petroleum refineries. It is estimated that the total quantity of 2,4,6-TTBP imported into Canada in 2006 was below 20 tonnes. Based on information collected by Environment Canada between 1986 and 2007, there appears to be a decreasing trend in the quantity of this substance in commerce during this time.
U.S. production/importation volumes of 2,4,6-TTBP were estimated at between 4,500 and 22,700 tonnes in 2002. Denmark, Norway and Sweden also reported the use of this substance in annual quantities between 1 and 33 tonnes.
A few potential substitutes for 2,4,6-TTBP have been identified. However, most of them appear on the medium priority list under the Chemicals Management Plan. As such, they will be assessed to determine whether they meet the section 64 criteria under CEPA 1999.
Antioxidants containing 2,4,6-TTBP are shipped directly to refineries by distributors in 55 gallon drums or 250-300 gallon totes. Some containers are dedicated and returned to the vendor. Tanker truck transport is not expected since the additives market is relatively small in Canada. In order to prevent exposure of fuels to oxygen, antioxidants need to be added to the fuels as soon as possible after they are produced. For this reason, antioxidants are added to the fuels at petroleum refineries and not at bulk terminals or other locations.
Once at the refinery, the antioxidant container is attached to a positive displacement pump which can inject the antioxidant into the pipeline carrying the fuel from the production unit to the storage tank. As this addition is typically conducted under pressure, it is not expected that there will be any releases.
Emissions of the substance to air could occur during transport and storage of the additives. In addition, emissions could happen at refineries, bulk terminals and service stations once the additives are added to fuels due to volatilization of the liquids. It is assumed that over 99% of the substance in the fuel is destroyed during combustion, leaving a small portion of the substance which could be released to air as uncombusted tailpipe emissions. However, releases to air will be rapidly oxidized as the substance is not persistent in air.
The transport, storage and handling of gasoline and other fuels containing 2,4,6-TTBP may also result in accidental release of this substance into the Canadian environment. This is believed to be the most likely potential source of release of this substance.
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