In Chicago and Milwaukee, gasolineprices have recently topped $2 a gallon, and the industry says the reason is partly a U.S. government requirement for additives called oxygenates. Experts say these additives may be obsolete and irrelevant, and may even cause environmental damage. The call for oxygenates has always been driven as much by politics as it has been by science. Republican and Democratic administrations have pushed for the use of oxygenates even though advances in automotive technology have made them less useful.