Leaded-Gasoline ADDITIVES Still Contaminate Groundwater.

The article presents a discussion on two leaded-gasoline additives, ethylene dibromide and 1,2-dichloroethane. Much recent attention has focused on the gasoline additive methyl tert-butyl ether (MTBE), which is mobile and persistent in the environment. The additive contaminates public water supplies. Hundreds of millions of dollars have been spent to address the MTBE problem, but two other gasoline additives that are far more toxic have been mostly overlooked. The volatile organic chemicals 1,2-dibromoethane (ethylene dibromide; EDB) and 1,2-dichloroethane (DCA) were ubiquitous components of lead-based antiknock additive mixtures, which were used from the 1920s through the late 1980s to increase gasoline octane ratings. Today, EDB and DCA are among the most commonly detected contaminants in U.S. public drinking-water systems that rely on groundwater. Typically, groundwater contamination by these chemicals is attributed to agricultural (EDB) or industrial (DCA) releases. Both EDB and DCA tend to be mobile in ground-water because of their low octanol-water partition coefficients.