"I want to make sure that folks are getting the benefit from it," he said. "There needs to be a review and discussion on the issue."
The bill comes as ethanol supporters tout a study released this week that says E-10 saves Missourians about 7 cents per gallon on gas. During the hearing, supporters cited the study, which was funded by the Missouri Corn Merchandising Council.
"What you've got is a renewable fuel that is replacing energy largely brought in from abroad," said John Urbanchuk, the study's author.
The study compared Missouri's average gasoline price in 2007 to the average price of E-10. In that year, the difference was about 8 cents per gallon. The study also projects 10 years ahead, using estimates from the Energy Information Administration.
Critics say ethanol's lower fuel efficiency wipes out any price benefits.
But Dethrow isn't the only legislator re-thinking the ethanol requirement. During the hearing, Rep. Rodney Schad, R-Versailles, said he regrets his vote for the law. A livestock producer, Dethrow said increased corn demand has driven up food prices. "I'm not saying the 10 percent mandate is entirely responsible for that," he said. "But it is part of the puzzle."
Urbanchuk, part of a Pennsylvania-based consulting firm, said ethanol demand plays a role in higher food prices, but it's not "the overwhelming or primary factor."
Mike Geske, president of the Missouri Corn Growers Association, implored lawmakers to keep what he called "one of the greatest Missouri economic development bills." He said repealing the mandate would do little to lower the cost of food and would signal the state's support of oil companies.
The Legislature also is considering requiring all diesel sold in the state to contain a 5 percent blend of biodiesel. That bill, which has passed the Senate, will be heard next week by the same House panel that considered the ethanol bill.
The committee must still vote whether to send the measure to the full House.