In 1996, at the request of the White House Office of Science and Technology Policy, the U.S. EPA, and the Centers for Disease Control, HEI published a comprehensive review of the health effects of both ethanol and MTBE. For the record I am submitting here today copies of our report - I will summarize our findings in the brief time allotted.
In assessing the health effects of using ethanol in gasoline, we must look both at the effects of likely increased exposure to ethanol itself, and to the range of other substances which are emitted from motor vehicles and whose emissions will be affected by the use of ethanol, including, the air toxics acetaldehyde and peroxyacetyl nitrate (PAN), the air pollutants carbon monoxide and ozone, and other substances.
We have substantial scientific evidence on the health effects of ingesting ethanol. Pregnant mothers ingesting relatively high volumes can see their infants suffer from Fetal Alcohol Syndrome; lower levels of maternal alcohol consumption result in Fetal Alcohol Effects. Consumption of ethanol in the form of alcoholic beverages has been shown to increase the risks of certain cancers, leading the National Toxicology Program, in its recent Report on Carcinogens, Ninth Edition (May 2000), to designate Alcoholic Beverage Consumption as a "known human carcinogen." For all of these effects, there are not firmly defined thresholds below which effects are not expected, although some investigators have identified an apparent threshold for the fetal effects of about one-half ounce of alcohol per day.
Although we know much about these effects of ethanol at high levels, it is likely that exposure of citizens to ethanol through either inhalation while refilling their fuel tanks, or through ingestion of ethanol-contaminated drinking water, will be substantially below levels at which effects have been seen. In the case of inhalation, HEI's estimate, based on limited exposure testing done to date, is that the dose of ethanol delivered to the body would be below the level of ethanol normally produced internally within the body.
The use of ethanol also results in changes in the exhaust and evaporative emissions from vehicles, in particular an increase in emissions of acetaldehyde and the chemical PAN, a decrease in emissions of carbon monoxide, and the potential for an increase in volatility of the fuel. While we have information on all of these, I will focus today on two key issues - acetaldehyde and volatility.
Acetaldehyde, which is designated as "reasonably anticipated to be a human carcinogen" by the National Toxicology Program, would, according to a recent analysis by the California Air Resources Board (February 2000), increase in the atmosphere in 2003 when compared to the use of fuel oxygenated with MTBE. However, there would be an overall decrease in acetaldehydes when compared to 1997 levels due to tightening California fuel requirements. While these results are reassuring, similar analyses have not been performed for the rest of the nation where federal RFG is in effect.
The addition of ethanol to gasoline can result in an increase in the volatility of the fuel, and in the potential for increased formation of ozone. The base fuel can be reformulated to lower its inherent RVP so as to offset this effect, although there are some continuing questions about the possible impacts of commingling ethanol-blended fuels with non-ethanol fuels.
PAN, which is an eye irritant, has been declining in the atmosphere, but is likely to continue at levels which could have significant effects with the use of both ethanol and MTBE.
There have been benefits from the use of ethanol and MTBE for the reduction of carbon monoxide emissions.
Beyond these effects, the use of ethanol as an oxygenate in RFG provides the ability, as do other oxygenates, to replace more toxic octane-providing substances (such as benzene) with cleaner octane. However, the Blue Ribbon panel identified that it is also possible to achieve these improvements using non-oxygenated reformulated fuels.
One further key question is the potential for ethanol to contaminate groundwater. Both the Blue Ribbon Panel, and more recently the Lawrence Livermore Laboratory, examined this issue. Although there are still many questions about these potential effects, two general conclusions can be drawn:
First, the high biodegradability of ethanol would suggest that the chances of an ethanol spill or leak finding its way to any significant degree into drinking water is small;
at the same time, the degradability of ethanol appears to retard the degradation of other components (e.g. benzene) resulting in the likelihood that plumes of these other substances, and the risk of water contamination, would increase somewhat. Precise estimates of the size of this risk do not exist.
In conclusion, we know much about the significant health effects of drinking ethanol, but should recognize that the likely exposure of the public to ethanol either through breathing or ingestion would be low. At the same time, there are continuing questions about the threshold below which we would not see such effects, and about the potential for ethanol in gasoline to increase the risk of water contamination from other components of the fuel. Based on these questions, the Blue Ribbon Panel recommended:
"EPA and others should accelerate ongoing research efforts into the inhalation and ingestion health effects, air emission transformation byproducts, and environmental behavior of all oxygenates and other components likely to increase in the absence of MTBE. This should include research on ethanol, alkylates, and aromatics, as well as of gasoline compositions containing those components." (Recommendation 13)
"EPA, in conjunction with USGS, the Departments of Agriculture and Energy, industry, and water suppliers, should move quickly to:
Conduct short-term modeling analyses and other research based on existing data to estimate current and likely future threats of contamination;
Establish routine systems to collect and publish, at least annually, all available monitoring data on:
use of MTBE, other ethers, and Ethanol,
levels of MTBE, Ethanol, and petroleum hydrocarbons found in ground, surface and drinking water,
trends in detections and levels of MTBE, Ethanol, and petroleum hydrocarbons in ground and drinking water;
Identify and begin to collect additional data necessary to adequately assist the current and potential future state of contamination."(Recommendation 14)
In closing, the decision to greatly increase any one component of the fuel supply is a major one, with potential widespread implications for exposure and public health. Although the current information on ethanol and its effects is somewhat reassuring, it is critical that accelerated efforts be made to fill key information gaps before widespread increases in use of any additive have been accomplished.
Thank you for the opportunity to submit this testimony. I would be pleased to answer any questions.