If you fill up your own gasoline tank, you've probably seen the signs on gasoline pumps that read: "This product may contain up to 10 percent ethanol."

Ethanol, which in the United States is usually derived from corn, adds octane to gasoline and is considered an excellent additive in levels of 10 percent or less. But now the Environmental Protection Agency (EPA) is mulling a plan that could permit blends of up to 15 percent ethanol, called E15.

Sounds like a simple way to put more home-grown fuel into the nation's gasoline mix, right? Not necessarily.

Ethanol is a highly corrosive material, and concerns have been raised about its effect on vehicle fuel lines, underground gasoline storage tanks and gasoline dispensers. Studies are underway to determine the safety of E15 and similar blends, as well as to examine vehicle durability, consumer satisfaction and the impact on emission control systems.

Although some the tests are still in the planning phase and aren't expected to be completed until 2011, EPA is optimistic that E15 or another mid-blend could be considered as early as mid-2010 for model-year 2001+ vehicles.

Allowing E15 for only certain vehicles could lead to customer confusion and worse. The risk of ethanol-caused leaks, spills and fires hasn't been determined. And there could be engine and emission control durability as well as vehicle performance issues that haven't been identified.

Yesterday, API was one of 40 organizations--including the American Lung Association and Friends of the Earth--that sent a letter to EPA Administrator Lisa Jackson expressing concern over the agency's apparent haste to introduce E15 to the marketplace:

"We continue to urge EPA to base any decision to permit the introduction of mid-level ethanol blends--whether a general waiver or the 'partial' waiver concept...on a complete and sound scientific record," the letter stated. It added, "[T]the public must have an opportunity to review and comment...prior to an EPA decision."

API's primary concern is the overriding need for customer safety and satisfaction. Furthermore, premature action could put the entire ethanol-blending program at risk. The scientific tests should be completed and the results studied closely before EPA moves forward with mid-level ethanol fuels.