Leaded gasoline toxicity

Eliminate Lead in Gasoline. The current trend of eliminating lead in gasoline, coupled with the possibility of a ban on leaded gasoline, will lower the toxicity of leaded gasoline tank sludges. 

Spark source (SSMS) and thermal emission (TEMS) mass spectrometry are used to determine ppb to ppm quantities of elements in energy sources such as coal, fuel oil, and gasoline. Toxic metals—cadmium, mercury, lead, and zinc— may be determined by SSMS with an estimated precision of 5%, and metals which ionize thermally may be determined by TEMS with an estimated precision of 1% using the isotope dilution technique. An environmental study of the trace element balance from a coal-fired steam plant was done by SSMS using isotope dilution to determine the toxic metals and a general scan technique for 15 other elements using chemically determined iron as an internal standard. In addition, isotope dilution procedures for the analysis of lead in gasoline and uranium in coal and fly ash by TEMS are presented. 

There is mild concern about the use of lead. Junked lead-acid batteries lying in waste dumps are occasionally said to introduce lead (a toxic metal) into the food chain.29 Ingested, lead remains in the brain. (Hence the banning of Pb-containing additives in gasoline.) However, most of the lead in lead-acid batteries is recycled. 

But leaded gasoline gives off free lead as it burns. Free lead is a very toxic element that causes damage to the nervous system. Ethylene dibromide is added to react with free lead and convert it to a safe compound. 

Development Effects. Anecdotal data have suggested a link between chronic gasoline vapor exposure of pregnant women and congenital defects of the central nervous system in their children. In utero exposure to leaded gasoline was found to cause retarded development and anomalies of head and muscles in two children (Hunter et al. 1979). Based on the limited available data, the study was considered inadequate to establish a relationship between inhalation exposure to gasoline and human development toxicity. 

In addition to the tetraethyl or tetramethyl lead, both types of antiknock fluids also contained 1,2-dichloroethane and 1,2-dibromoethane (ca. 35% by weight) to react with the lead released on combustion to form lead bromide and lead chloride. These lead halides are volatile at the cylinder combustion temperatures of 800-900°C, and leave the combustion chamber with the exhaust, which prevented the buildup of lead deposits. This was also the final step in the chain of events occurring with the alkylated lead antiknock compounds, which contributed to the widespread dispersal of lead compounds to the air and soil wherever gasoline powered vehicles operated. For this reason, and the toxic exposures during refueling, the alkylated lead addition rate was reduced to not more than 0.5 g of contained lead per U.S. gallon by 1980, even for leaded gasolines [29], and was phased out in the U.S. and Canada by 1985. 

However, despite all the progress being made, the uncontrolled production unavoidably leads to environmental problems such as climate change or emission of toxic products. For example, dioxins and furans are unintentionally formed and released from various sources like open burning of waste, thermal processes in the metallurgical industry, residential combustion sources, motor vehicles, particularly those burning leaded gasoline, fossil fuel-fired utility and industrial boilers, waste oil refineries etc... 

Specifio drugs or antidotes may be available for systemic toxicity of some hydrocarbons (eg, acetylcysteine for carbon tetrachloride and methylene blue for methemoglobin formers) or their solutes (eg, chelation therapy for leaded gasoline and antidotes for pesticides, etc). 

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