WASHINGTON--Although the chemical MTBE, added to gasoline in the winter to reduce the emission of carbon monoxide, does not pose a substantial human health risk, more study needs to be undertaken to assess both short- and long-term health effects, a National Research Council (NRC) committee said in its review of a draft of a federal report.
The federal study assessed the effects of methyl-tertiary-butyl ether (MTBE) on air and water quality, motor vehicles (fuel economy and engine performance), and public health.
In areas that have not met air quality standards for carbon monoxide, federal law requires the use of additives that increase oxygen levels in gas during winter months when lower temperatures tend to cause vehicles to emit more carbon monoxide. However, available data indicate that oxygenated fuels reduce winter air levels of carbon monoxide by as little as 0% to about 10%, the committee said.
The NRC committee disagreed with the report's conclusion that only a small percentage of the population may be sensitive to MTBE, citing studies showing an increase in health problems among workers exposed to MTBE on the job.
In addition, the panel said, cancer estimates for MTBE were based on animal models and should not be taken as conclusive. The committee recommended that further investigations be made into MTBE as a potential carcinogen.