Toxicity gasoline components

Physical and Chemical Properties of Toxic Gasoline Components... 

In industrial practice, two liquid acids are employed as catalysts for isobutane/ butene alkylation, namely sulfuric acid and hydrofluoric acid [3, 19, 20]. Both processes deliver a high-quality gasoline component. The catalyst consumption in the H2S04 process is high, typically 70-100kg/t The spent sulfuric acid contains tarry hydrocarbons and water and has to be processed externally. On the other hand, corrosiveness and toxicity of HF are reasons of concern that require use of additives that lower the HF vapor pressure and minimize the amount of HF released in the case of an accident. However, in many industrialized countries, new HF alkylation processes are no longer approved by authorities. 

The addition of ethanol to gasoline reduces harmful vehicle emissions and facilitates the reduction or removal of toxic air components, which are commonly found additives in gasoline. Emissions of carbon dioxide (CO2), the primary greenhouse gas contributing to global warming, have increased steadily, and the transportation sector alone accounts for 33% of total emissions. It is estimated that an 85% ethanol fuel would reduce greenhouse gas emissions between 15%i and Ethanol-blended fuels would reduce... 

The toxicity characteristics associated with MTBE seem to be mild or low relative to other gasoline components. The most common toxicological findings are the general anesthetic effect often induced by this chemical. The low organoleptic property threshold provides a large margin of safety for people in exposure situations. No human deaths have been reported as a result of this chemical. 

BTX processing has come under steadily increasing pressure to reduce emissions and workplace exposures (see Industrial hygiene). Reductions in the permissible levels of both benzene and total aromatics (BTX) in gasoline have been legislated. Whereas all BTX components ate to be controUed, the main focus is on benzene because it is considerably mote toxic than the others and is classified as a known carcinogen (42). 

The most common toxic metals in industrial use are cadmium, chromium, lead, silver, and mercury less commonly used are arsenic, selenium (both metalloids), and barium. Cadmium, a metal commonly used in alloys and myriads of other industrial uses, is fairly mobile in the environment and is responsible for many maladies including renal failure and a degenerative bone disease called "ITA ITA" disease. Chromium, most often found in plating wastes, is also environmentally mobile and is most toxic in the Cr valence state. Lead has been historically used as a component of an antiknock compound in gasoline and, along with chromium (as lead chromate), in paint and pigments. 

Methanol, CH3OH, the simplest alcohol, is made by reacting CO and H2 at high pressures over a catalyst. Methanol is a liquid at room temperature and is highly toxic. It is used to make formaldehyde, acetic acid, and other chemical intermediates. It is also used as a feedstock for MTBE (methyl tertiary butyl ether), a gasoline-blending component. 

Physical Form. Liquid gasoline is a complex mixture of at least 150 hydrocarbons with about 60-70% alkanes, 25-30% aromatics, and 6-9% alkenes. The small-chain, low-carbon-numbered components are more volatile and thus in higher percentages in the vapor phase than the larger and heavier molecules. The concentrations of aromatics, the more toxic of the components, are depleted to about 2% in the vapor phase. The light alkanes, the less toxic components, are enriched to about 90%. Benzene is also present and represents a component of major concern. 

Skalko RG Reproductive and developmental toxicity of the components of gasoline. Environ Health Perspect lOlfSuppl 6) 143-149, 1993... 

Tomorrow s fuels will contain less sulfur to be compatible with the more sophisticated engine designs of new automobiles. Fuels specifications will further reduce the concentrations of gasoline compounds that are listed and/or considered to be toxic. Refiners will continue to upgrade heavier components to lighter products and refineries will continue to use innovative catalysts and processing equipment to cost-effectively manufacture fuels and petrochemical feedstocks. We have barely touched on the sophisticated engineering needed to transform a barrel of crude oil into consumable products. 

No inhalation MRLs were derived because gasoline contains many components which can vary significantly among the many compositions of gasoline. The toxicity of gasoline would depend on the specific composition. 

Gasoline vapors will also be released from soil at the site contaminated by spillage of gasoline (Kramer 1989). Gasoline is not listed on the Toxics Release Inventory however, several of the component hydrocarbons are listed. Refer to the ATSDR toxicological profiles for benzene, toluene, xylene, and ethylbenzene (ATSDR 1989, 1990, 1991) for information on these individual hydrocarbon components of gasoline. 

Particular attention has also been given to the reconstruction of recent Pb emissions into the atmosphere, as detected in Greenland and Antarctic snow and ice. Owing to its well known toxicity and wide dispersion in the environment, caused in turn by the massive use as a component in a variety of products such as batteries, pigments, rolled and extruded items, cables sheaths and above all gasoline additives in the form of highly volatile alkyl-Pb compounds, Pb is classified as one of the... 

Scope of the Problem. Petroleum hydrocarbons are the principal components in a wide variety of commercial products (e.g., gasoline, fuel oils, lubricating oils, solvents, mineral spirits, mineral oils, and crude oil). Because of widespread use, disposal, and spills, environmental contamination is relatively common. It is important to understand that petroleum products are complex mixtures, typically containing hundreds of compounds. These include various amounts of aliphatic compounds (straight-chain, branched-chain, and cyclic alkanes and alkenes) and aromatic compounds (benzene and alkyl benzenes, naphthalenes, and PAHs). In addition, many petroleum products contain nonhydrocarbon additives such as alcohols, ethers, metals, and other chemicals that may affect the toxicity of the mixture. 

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