Benzene chemical release estimation

Next, various quantitative techniques were used to estimate releases by type of use. For use of benzene as an intermediate, we relied on the "emission factor" technique, which estimates the ratio of benzene release to total derivative production and then applies this ratio to the production rate at specific locations. Emissions factors were estimated from crude engineering assessments of the chemical processes entailed (such as open versus closed systems, continuous versus batch, and so on). 

Physical and Chemical Properties. The physical and chemical properties of some fuel oils and their primary component chemicals, specifically kerosene and fuel oil no. 2, are well defined and can be used to estimate the fate of these fuel oils following release to the environment (Air Force 1989 lARC 1989). However, the physical and chemical properties of other fuel oils such as no. 1-D, no. 2-D, and no. 4, are not well defined, and data should be gathered in order to estimate the fate of these oils in the environment. Data needs associated with specific compounds that are components of fuel oils (e.g., benzene, toluene, xylene, and PAHs) are presented in the ATSDR toxicological profiles for these chemicals (ATSDR 1989, 1990a, 1991a, 1991b). 

It was estimated that the chemicals stored in the room on the mezzanine fell down and and broke, releasing strong acids which then generated heat. When ethanol, methanol, benzene, and other flammable organic liquids mixed in, they caught fire. The chemicals stored there at that time were reported and are listed in Table 2.5... 

As noted before, the most significant refinery emissions were airborne. For those options that involved a change in emissions affecting air quality, impacts were modeled using standard air dispersion techniques. Exposure estimates were developed for three classes of chemicals (1) benzene, toluene, ethylbenzene and xylene (BTEX), (2) other chemicals reported in the refinery s TRI submissions, and (3) criteria pollutants (SO2, NO2, PMjo, and CO). Similar modeling techniques were used for all three classes. The project focused on the impact of benzene emissions, since benzene turned out to be the chemical species of greatest concern relative to other releases. 

The third principal source of nitrobenzene is the atmospheric photo-chemical reaction of nitrogen oxides with benzene, which presumably is derived from automobile fuels and, to a lesser extent, solvent uses of benzene (Dorigan and Hushon 1976). As benzene releases decline, this source (not quantified) should diminish as well. The contribution of this source is difficult to estimate since most measurements of ambient atmospheric nitrobenzene have been made in urban areas near sites of nitrobenzene manufacture, use, and disposal (see Section 5.4.1). Seasonal variations and those associated with air pollution episodes suggest that this source, although limited, may form a significant proportion of nonoccupational human exposure. 

Toluene and benzene, as well as xylenes, are fairly common solvents encountered in the modem environment. These solvents are aromatic hydrocarbons frequently used as industrial chemicals. All are components of gasoline fuels, and our modern motor vehicle-based society represents one of the main emission sources. Benzene can also be released by several combustion reactions and can be found in tobacco smoke as well as in many consumer products. Benzene is a known human cancer hazard, and the hematotoxicity of benzene has been well elucidated during the past two decades. The acute internal dose of these aromatic compounds can be estimated by determining the amount of parent compound in blood, breath, or urine however, the use of sensitive HPLC-MS procedures for measuring urinary metabolites has also been commonly reported in the literature.Table 1 displays some of... 

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