Liver Effects Central to Draft EPA Review of Fuel Oxygenate

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By Pat Rizzuto

Aug. 31 — The Environmental Protection Agency is scheduled to release Sept. 1 a draft assessment of a fuel oxygenate called ethyl tertiary butyl ether, according to a prepublication Federal Register notice.

Ethyl tertiary butyl ether is used as a fuel additive for gasoline to increase octane rating and has been used to meet air pollution reduction goals under the Clean Air Act, according to information from the EPA. The use of oxygenates such as ETBE in reformulated gasoline in the U.S. was effectively eliminated in 2006, but use and production has continued to increase gasoline’s octane rating, the EPA said.

The assessment, conducted under EPA’s Integrated Risk Information System (IRIS), will examine the human health hazards of ETBE and the doses at which those hazards could manifest. Final IRIS assessments, or “toxicological reviews,” are used throughout the agency, U.S. states and regulators in other parts of the world as part of the information they use to assess the risks a chemical poses at a particular site or when used in particular ways. The resulting risk assessments contribute to decisions on whether an industrial activity, hazardous waste site, or other situation needs to be regulated.

Lyondell Chemical Co. and one other company, which claimed its name to be confidential business information, were the two U.S. manufacturers of ETBE in 2011, the most recent year for which U.S. production data is available from the EPA. The agency withheld ETBE’s national production volume information to protect proprietary information.

European companies that have registered ETBE include BP p.l.c., Exxon Mobil Corp. SABIC Petrochemicals and Shell. The oxygenate is registered as having an annual European production volume of 1 million to 10 million metric tons.

2009 Draft Assessment Put on Hold

The EPA’s IRIS program has not issued a final assessment of ETBE previously, although the agency published a draft assessment in 2009. That draft assessment proposed to classify ETBE as having “suggestive evidence of carcinogenic potential.” It also proposed a reference concentration (RfC) of 0.006 milligrams per cubic meter of air. RfCs are the agency’s estimate of a continuous does that people could inhale over their lifetime without expectation of harm.

The ETBE assessment, however, was among four IRIS chemical evaluations the agency placed on hold after the U.S. National Toxicology Program and an Italian research organization called the Ramazzini Institute reached divergent opinions on cancer data the institute had generated.

In a 2013 presentation, the IRIS program said it was again reviewing ETBE. It was examining kidney, liver, reproductive, developmental and carcinogenic effects, among other potential health problems.

Following that meeting, the Petroleum Industry Technology and Research Institute Inc. of Japan sent the EPA a letter arguing that ETBE did not meet the criteria for an IRIS assessment.

“Current uses of ETBE in the United States are virtually non-existent. Manufacture of ETBE in the U.S. is predominately for export only,” the Japanese trade association wrote.

Questions about the effects ethyl tertiary butyl ether may have on the liver are among the issues the EPA also will discuss at an Oct. 26 public science meeting.

To contact the reporter on this story: Pat Rizzuto in Washington at

To contact the editor responsible for this story: Larry Pearl at

For More Information

A prepublication copy of EPA’s Federal Register notice announcing the ETBE assessment is available at

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