The U.S. Environmental Protection Agency on Friday approved higher levels of corn-based ethanol in gasoline for cars and light-duty trucks made in the past decade.

The agency has decided that 15% ethanol in gasoline, known as E15, is safe for such vehicles made between 2001 and 2006. In October, it approved this blend -- higher than the 10% it previously allowed -- for cars and light-duty trucks manufactured since 2007, but it postponed its use in older cars pending additional tests by the U.S. Department of Energy.

"Recently completed testing and data analysis show that E15 does not harm emissions control equipment in newer cars and light trucks," EPA Administrator Lisa Jackson said in the announcement. "Wherever sound science and the law support steps to allow more home-grown fuels in America's vehicles, this administration takes those steps."

EPA also announced that it will not decide this year whether to allow E15's use in pre-2001 cars or in any motorcycles, heavy-duty vehicles or non-road engines, saying current testing data do not support such a waiver. Because ethanol burns hotter than gasoline, it causes catalytic converters to break down faster.

The agency said it is developing requirements to ensure that E15 is properly labeled at the gas pump.

Congress, via the Energy Independence and Security Act of 2007, mandated an increase in using renewable fuels, and ethanol is considered a renewable fuel, because it comes from plant products (primarily corn) or biomass waste. It required that 36 billion more gallons of biofuels, mostly ethanol, be blended into auto fuel by 2022.

Ethanol, while popular in corn-growing regions, faces much criticism from environmentalists, cattle ranchers, food companies and a broad coalition of other groups. Opponents argue that its increased use makes animal feed more expensive and will raise prices at the grocery store.

EPA granted its E15 waiver in response to an April 2009 petition from Growth Energy and 54 ethanol manufacturers. Under the Clean Air Act, the EPA can waive the law's prohibition against selling significantly altered fuel if the petitioner shows that the new fuel will not cause the failure of engine and other emission-related parts.