WASHINGTON — The U.S. Environmental Protection Agency (E.P.A.) expects to make a final determination regarding whether to increase the allowable ethanol content in fuel in mid-2010.

In a letter sent Dec. 1 to Growth Energy — a biofuels industry association that had asked E.P.A. to grant a waiver allowing for the use of up to 15% of ethanol in gasoline — the agency said while not all tests have been completed, the results of two tests indicate engines in newer cars likely can handle an ethanol blend higher than the current 10% limit. E.P.A. will decide whether to raise the blending limit when more testing data is available. The agency also announced it has begun the process to craft the labeling requirements that will be necessary if the blending limit is raised.

Growth Energy requested a waiver to allow for the use of up to 15% ethanol in gasoline, an increase of 5 percentage points, in March 2009. Under the Clean Air Act, E.P.A. was required to respond to the waiver request by Dec. 1. The agency said it has been evaluating the group’s request and has received a broad range of public comments as part of the administrative rulemaking process.

E.P.A. and the Department of Energy also launched a number of studies to determine whether cars could handle higher ethanol blends. Testing has been proceeding as quickly as possible given the available testing facilities, the agency said.