65 FR 58 pgs. 16094-16109 - Methyl Tertiary Butyl Ether (MTBE); Advance Notice of Intent to InitiateRulemaking Under the Toxic Substances Control Act to Eliminate or Limit the Use ofMTBE as a Fuel Additive in Gasoline

Type: PRORULEVolume: 65Number: 58Pages: 16094 - 16109
Docket number: [OPPT-62164; FRL-6496-1]
FR document: [FR Doc. 00-7323 Filed 3-21-00; 2:11 pm]
Agency: Environmental Protection Agency
Official PDF Version:  PDF Version


40 CFR Part 755

[OPPT-62164; FRL-6496-1]

Methyl Tertiary Butyl Ether (MTBE); Advance Notice of Intent to InitiateRulemaking Under the Toxic Substances Control Act to Eliminate or Limit the Use ofMTBE as a Fuel Additive in Gasoline


Environmental Protection Agency (EPA).


Advance Notice of Proposed Rulemaking.


Methyl Tertiary Butyl Ether (MTBE) is a chemical compound that isused as a fuel additive in gasoline. Refiners have primarily added MTBE to gasoline to meet theClean Air Act (CAA) requirement that areas with severe problems in attaining the National Ambient AirQuality Standard (NAAQS) for ozone use Reformulated Gasoline (RFG) containing 2% oxygen byweight. Many States have also voluntarily chosen to use RFG as a means of addressing marginal,moderate, or serious ozone nonattainment, and some refiners use MTBE to boost the octane ofgasoline. In addition to the RFG program, the CAA also required the establishment of a Wintertime Oxygenated Fuel (Wintertime Oxyfuel) program. Under this program, gasoline must contain 2.7% oxygen by weightduring the wintertime in areas that are not in attainment for the NAAQS for carbon monoxide (CO). Insome cases this requirement is met through the use of MTBE. While the use of MTBE as a fueladditive in gasoline has helped to reduce harmful air emissions, it has also caused widespread andserious contamination of the nation's drinking water supplies. Unlike other components ofgasoline, MTBE dissolves and spreads readily in the groundwater underlying a spill site, resistsbiodegradation, and is difficult and costly to remove from groundwater. Low levels of MTBE canrender drinking water supplies unpotable due to its offensive taste and odor. At higher levels, itmay also pose a risk to human health. The United States Geological Survey (USGS) has found that theoccurrence of MTBE in groundwater is strongly related to its use as a fuel additive in the area,finding detections of MTBE in 21% of ambient groundwater tested in areas where MTBE is usedin RFG compared with 2% of ambient groundwater in areas using conventional gasoline. EPAis today providing an advance notice of its intent to initiate a rulemaking pursuant to section 6 ofthe Toxic Substances Control Act (TSCA) to eliminate or limit the use of MTBE as a fuel additive. EPAseeks public comment on a number of aspects of this anticipated regulatory action, includingwhether the Agency should take action to address any fuel additives other than MTBE.


Comments, identified by docket control number OPPTS-62164,must be received on or before May 8, 2000.


Comments may be submitted by mail, electronically, or in person.Please follow the detailed instructions for each method as provided in Unit I. of the SUPPLEMENTARY INFORMATION . To ensure proper receipt byEPA, it is imperative that you identify docket control number OPPTS-62164 onthe first page of your response.


For general informationcontact: Barbara Cunningham, Director, Office of Program Management and Evaluation, Office of Pollution Prevention and Toxics (7401), Environmental Protection Agency, Ariel Rios Bldg., 1200 Pennsylvania Ave., NW., Washington, DC 20460; telephone number: (202) 554-1404; e-mail address: TSCA-Hotline@epa.gov.

For technical information contact: Karen Smith, Office of Transportationand Air Quality, Fuels and Energy Division (6406J), Environmental Protection Agency, Ariel RiosBldg., 1200 Pennsylvania Ave., NW., Washington, DC 20460; telephone number: (202) 564-9674; e-mail address: smith.karen@epa.gov.


I. General Information

A. Does this Action Apply to Me?

Entities potentially regulated by a limit or ban on the use of MTBE as a fuel additive ingasoline are those entities that refine, import, or blend gasoline with additives, or that transport,store, or sell gasoline, or otherwise introduce gasoline into commerce. Potentially regulatedcategories include:

Categories NAICS codes SIC codes Examples of regulated entities
Industry 324110 2911 Petroleum refiners, blenders, and importers
Industry 422710 422720 5171 5172 Gasoline marketers and distributors

This listing is not intended to be exhaustive, but rather provides a guide for readersregarding entities likely to be regulated by an action resulting from this ANPRM. Other types ofentities not listed in this table could also be directly affected, particularly if future action includeslimits directed at gasoline release prevention or water remediation, rather than the MTBE contentof gasoline. The North American Industrial Classification System (NAICS) and StandardIndustrial Classification (SIC) codes have been provided to assist you and others in determiningwhether or not this action applies to certain entities. To determine whether you or your businessis affected by this action, you should carefully examine this ANPRM. If you have any questionsregarding the applicability of this action to a particular entity, consult the technical person listedunder FOR FURTHER INFORMATION CONTACT.

B. How Can I Get Additional Information, Including Copies of this Document or OtherRelated Documents?

1. Electronically . You may obtain electronic copies of this document, andcertain other related documents that might be available electronically, from the EPA InternetHome Page at http://www.epa.gov/. To access this document, on the Home Page select "Lawsand Regulations" and then look up the entry for this document under the " FederalRegister -Environmental Documents." You can also go directly to the FederalRegister listings at http://www.epa.gov/fedrgstr/.

2. In person . The Agency has established an official record for this actionunder docket control number OPPTS-62164. The official record consists of the documentsspecifically referenced in this ANPRM, any public comments received during an applicable commentperiod, and other information related to this action, including any information claimed asConfidential Business Information (CBI). This official record includes the documents that arephysically located in the docket, as well as the documents that are referenced in those documentsand in this ANPRM. The public version of the official record does not include any informationclaimed as CBI. The public version of the official record, which includes printed, paper versions ofany electronic comments submitted during an applicable comment period, is available forinspection in the TSCA Nonconfidential Information Center, North East Mall, Rm. B-607,Waterside Mall, 401 M St., SW., Washington, DC. The Center is open from noon to 4 p.m.,Monday through Friday, excluding legal holidays. The telephone number for the Center is (202)260-7099. For additional information related to this ANPRM, see the Office of Air and Radiation(OAR) Docket, A-99-01, The Blue Ribbon Panel to Review the Use of Oxygenates inGasoline. The index for OAR docket A-99-01 can be found athttp://www.epa.gov/oms/consumer/fuels/oxypanel/blueribb.htm.

3. Fax-on-Demand . Using a faxphone call (202) 401-0527 and select item 4005 for an index of items in this category.

C. How and to Whom Do I Submit Comments?

You may submit comments through the mail, in person, or electronically. To ensureproper receipt by EPA, it is imperative that you identify docket control number OPPTS-62164 on the first page of your response. Commenters should be aware that their comments may be placed on an Internet docket web site. This information may include the commenters name and address.

1. By mail . Submit your comments to: Document Control Office (7407),Office of Pollution Prevention and Toxics (OPPT), Environmental Protection Agency, Ariel Rios Bldg., 1200 Pennsylvania Ave., NW., Washington, DC 20460.

2. In person or by courier . Deliver your comments to: OPPT DocumentControl Office (DCO) in East Tower Rm. G-099, Waterside Mall, 401 M St., SW.,Washington, DC. The DCO is open from 8 a.m. to 4 p.m., Monday through Friday, excluding legalholidays. The telephone number for the DCO is (202) 260-7093. If your comments arereceived after 3 p.m., they will be dated as received the next business day.

3. Electronically . You may submit your comments electronically by e-mailto: "oppt.ncic@epa.gov," or mail your computer disk to the address identified above. Do notsubmit any information electronically that you consider to be CBI. Electronic comments must besubmitted as an ASCII file avoiding the use of special characters and any form of encryption.Comments and data will also be accepted on standard disks in WordPerfect 6.1/8.0 or ASCII fileformat. All comments in electronic form must be identified by docket control number OPPTS-62164. Electronic comments may also be filed online at many Federal Depository Libraries.

D. How Should I Handle CBI Information That I Want to Submit to the Agency?

Do not submit any information electronically that you consider to be CBI. You mayclaim information that you submit to EPA in response to this document as CBI by marking anypart or all of that information as CBI. Information so marked will not be disclosed except inaccordance with procedures set forth in 40 CFR part 2. In addition to one complete version of thecomment that includes any information claimed as CBI, a copy of the comment that does notcontain the information claimed as CBI must be submitted for inclusion in the public version of theofficial record. Information not marked confidential will be included in the public version of theofficial record without prior notice. If you have any questions about CBI or the procedures forclaiming CBI, please consult the technical person identified under FOR FURTHER INFORMATION CONTACT.

E. What Should I Consider as I Prepare My Comments for EPA?

EPA invites you to provide your views on any issue relevant to this ANPRM. EPA hasidentified particular subjects in Unit VI. regarding which comment would beparticularly appreciated. You may find the following suggestions helpful for preparing yourcomments:

1. Explain your views as clearly as possible.

2. Describe any assumptions that you used.

3. Provide copies of any technical information and/or data you used thatsupport your views.

4. If you estimate potential burden or costs, explain how you arrived at theestimate that you provide.

5. Provide specific examples to illustrate your concerns.

6. Offer alternative ways to address the concerns identified by EPA.

7. Make sure to submit your comments by the deadline in this ANPRM.

8. To ensure proper receipt by EPA, be sure to identify the docketcontrol number assigned to this action on the first page of your response. You may also provide the name, date, and Federal Register citation.

II. Introduction

This ANPRM initiates an Agency rulemaking to address the threat to the nation's drinking water resources from contamination by MTBE, a widely used additive in gasoline. This rulemaking will be conducted under TSCA section 6, 15 U.S.C. 2605. It is EPA's intent to conduct this rulemaking as quickly as reasonably practicable. EPA's review of existing information on contamination of drinking water resources by MTBE indicates substantial evidence of a significant risk to the nation's drinking water supply. A comprehensive approach to such risk must include consideration of either reducing or eliminating the use of MTBE as a gasoline additive. As a result, EPA is initiating this process pursuant to the unreasonable risk provision under TSCA section 6 to eliminate or greatly reduce the use of MTBE as a gasoline additive. EPA is interested in comments on both the risk and these possible responses to it.

MTBE is a common and widely used additive in gasoline. It is an oxygenate,meaning it increases the oxygen content of the gasoline. It is also a source of octane in gasoline.It is widely used in those parts of the country where oxygenated gasoline is required, either byFederal or State law. For example, the 1990 amendments to the CAA require that Federal RFGmeet a 2.0% oxygen content requirement by weight. MTBE is the primary oxygenate used byrefiners to meet this requirement, which applies to over 30% of the country's gasoline. WhenMTBE is used to meet this requirement, the gasoline is blended so it contains about 11% MTBEby volume. In other parts of the country, MTBE is sometimes used in conventional or non-RFG as a source of octane. Significantly more MTBE is used in RFG and otheroxygenated gasoline programs than is used in conventional gasoline.

Current data on MTBE levels in ground and surface waters indicate widespread andnumerous detections at low levels of MTBE, with a more limited number of detections at higherlevels. Given MTBE's widespread use as a gasoline additive and the large volumes of gasolinethat are stored, transported, and used in all areas of the country, releases of MTBE to the nation'sground and surface waters occur in a number of ways. Leakage from the gasoline storage anddistribution system is a major source of contamination, but the contamination can also come fromspills, emissions from marine engines into lakes and reservoirs, and to some extent from airdeposition. MTBE is highly soluble in water, resists biodegradation, and moves rapidly withgroundwater. It may end up in drinking water supplies even when there are no indications ofother gasoline components. MTBE is detected in water much more often and at higherconcentrations in areas of the country where Federal RFG is sold, given its dominant use byrefiners as an oxygenate to meet the statutory RFG oxygen content requirement. The USGS hasfound detections of MTBE in 21% of ambient groundwater tested in areas where MTBE is usedin RFG as compared with 2% of ambient groundwater in areas using conventional gasoline. (Ref. 1)

The presence of MTBE in drinking water sources presents two major problems. The first concern is that MTBE contamination may render water supplies unuseable as drinking water. MTBE has an offensive taste and odor which can be detected in water even at low levels. Because of the taste and odor problem, MTBE contamination has resulted in the loss of certain drinking water sources. For example, high levels of MTBE found in groundwater wells that supply Santa Monica's drinking water led that city to close its wells, forcing it to purchase drinking water from another public water supplier. In addition, MTBE detections found in groundwater wells that supply South Lake Tahoe forced the South Tahoe Public Utility District to close 8 of its 34 wells despite detections below EPA's advisory levels. An additional four wells were closed as a precautionary measure due to their proximity to the existing MTBE plumes.

The second major concern involves uncertainty regarding the level of risk to public health from the chronic exposure of large numbers of people to low levels of MTBE in drinking water. While inhalation of MTBE in high concentrations has been shown to cause cancer in laboratory animals, the Agency concluded in 1997 that there is little likelihood that MTBE in drinking water would cause adverse health effects at levels that cause taste and odor problems. (Ref. 2) There is still much uncertainty about the extent of the health risks associated with chronic, low-level exposures to MTBE in drinking water. The Agency is continuing to review and update its analysis of the potential health risks posed by MTBE.

Once MTBE contaminates a drinking water source, its chemical nature makes itdifficult, expensive, and time-consuming to remediate. For example, it is much harder and moreexpensive to remove MTBE from drinking water than it is to remove other organic componentsof gasoline. Furthermore, MTBE does not biodegrade as readily as other components ofgasoline. Given the numerous and diverse sources of potential release into the environment andthe problems associated with cleaning it up once it is released, EPA believes a comprehensive approach to such risk must include consideration of either reducing or eliminating the use of MTBE as a gasoline additive.

As discussed earlier, in ground water MTBE is more soluble, does not adsorb as readily to soil particles, biodegrades less rapidly and moves more quickly than other components of gasoline. By comparison, unless frozen, MTBE in surface water will volatalize and find its way into the atmosphere. This accounts for the less frequent and generally lower concentrations of MTBE found in surface water.

Since the available information shows that there are numerous and widespread instances of groundwater contamination, EPA is considering the substitutes that would likely be used to replace MTBE. In oxygenated gasoline programs such as Federal RFG, the most likely substitute based on current usage is ethanol. Other ether compounds are currently used as oxygenates in relatively small quantities. MTBE does not occupy as dominant a position as an octane enhancer for conventional gasoline as it does as an oxygenate in RFG. Ethanol, alkylates, and aromatics are all widely-used as octane enhancers in conventional gasoline. Although EPA is seeking more information on alternatives to MTBE, EPA does not expect the use of ethanol, alkylates, or aromatics as fuel additives to present the same magnitude of risk to drinking water supplies as MTBE. Ethanol biodegrades more quickly than MTBE, and therefore seems less likely to contaminate drinking water as often as MTBE, or at the concentrations of MTBE. First order degradation constants for MTBE in ambient ground water have been reported by Schirmer and others (1998) and Borden and others (1997). The rate constants, k , from these studies are 0.0012 day(-1) (Schirmer and others, 1998) and 0.0010 +- 0.0007 day(-1) (Borden and others, 1997). (Refs. 3,4) These reaction rates for MTBE correspond to a half-life of about 1.6 and 1.9 years, respectively. By comparison, in a December 1999 report to the California Environmental Policy Council the authors report that under aerobic conditions, the reported half-lives of ethanol in surface waters are short. Half-lives span 6.5 to 26 hours for ethanol. Anaerobic biodegradation in oxygen-limited environments is also expected to proceed at rapid rates. Reported half-lives for ethanol biodegradation under anaerobic conditions range from 1 to 4.3 days. (Ref. 5) Unlike MTBE, alkylates and aromatics are expected to behave in soil and water more like other components typically found in gasoline; as a result, they too would be unlikely to contaminate drinking water as often as MTBE or at the concentrations of MTBE. Ethers other than MTBE, and alcohols other than ethanol, are not currently used widely as oxygenates; the Agency does not have much data to characterize the risks they might pose to drinking water supplies. However, the other ethers are chemically similar or related to MTBE, and they may well move through soil and water in ways and amounts similar to MTBE. EPA will closely evaluate whether compounds not currently used in significant quantities as oxygenates in RFG might be widely used as alternatives to MTBE, if MTBE use in gasoline is banned or limited, whether additional information on these compounds is necessary, and whether other measures are appropriate to assure that an elimination or limitation of MTBE in gasoline does not result in the use of alternatives that might cause a similar or greater level of risk.

The remainder of this ANPRM outlines the major elements of the problem and itspotential solution. EPA invites comment from all interested parties on these and any othermatters relevant to addressing the risk of MTBE to the nation's drinking water resources.

III. Background

A. What is MTBE and Why is it Used as a Fuel Additive?

MTBE is an ether compound made by combining methanol and isobutylene. Themethanol is typically derived from natural gas; isobutylene can be derived as a byproduct of thepetroleum refinery process. Since the 1970's, MTBE has been used in the United States as anoctane-enhancing replacement for lead, primarily in mid- and high-grade gasoline atconcentrations as high as 7% (by volume). Now, however, MTBE is mainly used as a fueloxygenate at higher concentrations (11% to 15% by volume) as part of the Federal RFG and Wintertime Oxyfuel programs. These programs were initiated byEPA in 1995 and 1992, respectively.

The CAA mandates that RFG be sold in the 10 largest metropolitan areas with themost severe summertime ozone levels, including Baltimore, Chicago, Hartford, Houston, Los Angeles, Milwaukee, New York, Philadelphia, Sacramento, and San Diego. The CAA alsoallows any other area classified as a marginal, moderate, or serious ozone nonattainment area toopt into the RFG program. Currently, 17 States and the District of Columbia voluntarilyparticipate in the RFG program. These areas are located in California, Connecticut, Delaware,District of Columbia, Illinois, Indiana, Kentucky, Maryland, Massachusetts, Missouri, NewHampshire, New Jersey, New York, Pennsylvania, Rhode Island, Texas, Virginia, and Wisconsin.The total number of areas participating in the RFG program may change from year to year,depending on potential opt-ins.

EPA regulations adopted pursuant to the CAA require that RFG achieve reductionsin mass emissions of volatile organic compounds (VOCs) and toxic air emissions of at least 15%during Phase I of the RFG program (1995 through 1999), and reductions in such emissions of27% and 22%, respectively, during Phase II of the RFG program (2000 and on). Phase II RFGalso requires a 6.8% reduction in oxides of nitrogen (NO X ). RFG must also meet certainmandatory content standards, including limitations on benzene and a restriction of heavy metalcontent. To address its unique air pollution challenges, California has adopted similar, but morestringent requirements for California RFG.

The CAA specifies that RFG must contain 2% oxygen by weight. Although anumber of oxygenates could be used to meet this requirement, in practice over 87% of RFGcontains MTBE as the primary oxygenate; approximately 12% of RFG contains ethanol. Twopercent oxygen by weight is equivalent to approximately 11% MTBE by volume. When ethanolis used as an oxygenate, it is usually blended at 10% by volume, which is equivalent to 3.5%oxygen by weight. A small percentage of refiners use tertiary amyl methyl ether (TAME) as theprimary oxygenate in RFG; more frequently TAME is present in RFG as a secondary oxygenatetogether with MTBE. Other oxygenates are available to refiners, such as ethyl tertiary butyl ether(ETBE), tertiary butyl alcohol (TBA), and diisopropyl ether (DIPE), but are not being used insignificant quantities (or at all) at this time.

Reformulated gasoline represents over 30% of the total retail gasoline sold in theUnited States. According to the Department of Energy (DOE), over 126 billion gallons of gasoline weresupplied for U.S. markets in 1998, with 41.5 billion gallons of that volume being reformulatedgasoline. (Ref. 6) In addition to the RFG program, certain areas in California and elsewherein the nation that have not attained the NAAQS forCO are required under the CAA to implement the Wintertime Oxyfuelprogram. The CAA requires Wintertime Oxyfuel to contain no less than 2.7% oxygen (byweight) during the winter, when CO levels are highest. There are 17 areas across thecountry that currently implement the Wintertime Oxyfuel program. Ethanol is the primaryoxygenate used to meet this oxygen requirement. Currently, Los Angeles is the only areaimplementing the Wintertime Oxyfuel program with MTBE. When MTBE is used to meet theWintertime Oxyfuel requirements, it is added to gasoline at a concentration of approximately 15% by volume.

MTBE is also used in conventional gasoline to boost the octane of gasoline. Octaneis a measure of a fuel's resistance to uncontrolled combustion (engine knock). The DOE estimates that approximately 12,000 barrels of MTBE are used per day as an octaneenhancer in conventional gasoline. (Ref. 7) This is less than 5% of the total MTBE use in gasoline.MTBE is typically present in gasoline as an octane enhancer at 3-7% by volume. Alternativeoctane enhancers are also used, including ethanol, alkylates, and aromatic compounds.

A number of States have taken actions designed to limit the use of MTBE ingasoline. In March 1999, Governor Gray Davis of California issued an executive order requiringthe California Air Resources Board to develop a timetable for the removal of MTBE fromgasoline sold in California as soon as possible, but by no later than December 31, 2002. Maineopted out of the RFG program in March 1999. In July of 1999, New Hampshire enacted a lawdirected at reducing the use of MTBE in gasoline, including a requirement that the State request awaiver from EPA of RFG oxygen content requirements until 2002. Five other States haveinitiated proposed limited use, bans or phase-outs of MTBE, including Arizona, Kansas, Missouri,New York, and South Dakota.

B. What Risks Does MTBE Pose to Drinking Water Supplies?

1. Chemical properties . In comparison to other components of concern ingasoline, including benzene, toluene, ethylbenzene, and xylenes (collectively referred to as"BTEX"), the available information shows MTBE may pose additional problems when it escapesinto the environment through gasoline releases. MTBE is capable of traveling through soilrapidly, is very soluble in water (much more so than BTEX), and is highly resistant tobiodegradation (much more so than BTEX). MTBE that enters groundwater moves at nearly thesame velocity as the groundwater itself. As a result, it often travels farther than other gasolineconstituents, making it more likely to impact public and private drinking water wells. Due to itsaffinity for water and its tendency to form large contamination plumes in groundwater, andbecause MTBE is highly resistant to biodegradation and remediation, gasoline releases withMTBE can be substantially more difficult and costly to remediate than gasoline releases that donot contain MTBE (Unit III.E.). This is a substantial concern in the United States, whereapproximately 40-46% of the population uses groundwater as a source of drinking water.

2. Taste and odor . MTBE has a very unpleasant turpentine-like taste andodor that at low levels of contamination can render drinking water unacceptable for consumption.A number of studies have been conducted on the concentrations of MTBE in drinking water atwhich individuals can detect the taste and odor of the chemical. (Refs. 8,9,10) Human sensitivity to tasteand odor varies widely. In controlled studies, some individuals were able to detect very lowconcentrations of MTBE, while others do not taste or smell the chemical even at much higherconcentrations. In controlled studies individuals have detected odor and taste at concentrations of MTBE as low as 2.5 parts per billion (ppb) for odor and 2 ppb for taste.1


1 Throughout this ANPRM, various studies are cited which may refer to the presence of MTBE in water in either micrograms per liter (µg/L) or ppb. These units are approximately interchangeable assuming the density of the water is constant. In reality, to the extent that the water density may vary from study to study, equivalence of these units may not be exact.

In December 1997, EPA's Office of Water released a non-regulatory advisory forMTBE in drinking water. The EPA advisory is not a mandatory standard for action and is notFederally enforceable, but provides guidance for communities that may be exposed to drinkingwater contaminated with MTBE. According to the advisory, keeping MTBE concentrations in the rangeof 20-40 µg/L or below would likely avert unpleasant taste and odoreffects, recognizing that some people may detect the chemical below this concentration range.

The State of California has chosen to establish a secondary drinking water standardof 5 µg/L to ensure the potability of drinking water for more sensitive individuals. EPA isplanning to upgrade its MTBE advisory to a national secondary drinking water standard and willreview its 1997 advisory levels at that time. Secondary drinking water standards address theaesthetic qualities that relate to public acceptance of drinking water and are provided as non-enforceable guidance to the States.

3. Human health effects. The majority of the human health-related researchconducted to date on MTBE has focused on adverse effects that may result through inhalation ofthe chemical. At high doses by the inhalation route, MTBE has caused non-cancer health effectsas well as tumors in two strains of rat and one strain of mouse in a variety of organs. However,there have been no human or animal health effects studies concerning the ingestion of MTBE indrinking water. In one study, animals were given a daily (all at once) dose of MTBE in olive oil.There were carcinogenic effects at a high level of exposure. Because the animals were notexposed through drinking water, uncertainties remain concerning the degree of risk associatedwith typical human exposure.

EPA classified MTBE as a "possible" human carcinogen under its 1986 cancer riskassessment guidelines on the basis of results of inhalation cancer tests and has suggested that it beregarded as posing a potential carcinogenic hazard and risk to humans, although no quantitativeestimate of the cancer potency of MTBE has been established by EPA because of limitations inthe available data. (Refs. 11,12) While MTBE has been characterized as an animal carcinogen, both theInternational Agency for Research on Cancer and the Department of Health and HumanServices have indicated that there are not enough data to classify MTBE with regard to humancarcinogenicity under their classification schemes. (Refs. 13,14) It should be noted that conclusions in theOffice of Science and Technology Policy's 1997 Interagency Assessment of Oxygenated Fuelsand in a 1996 report by the Health Effects Institute generally support EPA's view on potentialcarcinogenic hazard. (Ref. 15) The Interagency Assessment stated, in regard to inhalation risks, that "it is not known whether the cancer risk of oxygenated gasoline containing MTBE is significantly different from the cancer risk of conventional gasoline." The estimated upper bound cancer units risks of MTBE are similar to or slightly lower than those of fully vaporized conventional gasoline, which has been listed by EPA as a probable human carcinogen based on animal carcinogenicity data. However, because of lack of health data on the nonoxygenated gasoline vapors to which humans are actually exposed, it is not possible to have a reasonably good estimate of population cancer risk to conventional gasoline.

As a result of substantial scientific uncertainties, a review committee of the NationalAcademy of Sciences (NAS) recommended that additional studies be conducted on MTBE andthat questions about the bolus dosing study be resolved before the study is used for riskassessment purposes. (Ref. 16) A number of ongoing studies by EPA, the Chemical Industry Instituteof Toxicology (CIIT) and other organizations should provide EPA with information to assesshealth risks via different routes of MTBE exposure. These studies should allow for extrapolationfrom the inhalation studies to an assessment of risks associated with ingestion of drinking water.In addition, further study of potential health effects of MTBE and other fuel additives areunderway by the petroleum industry as required under CAA section 211.

EPA reviewed available health effects information on MTBE in its 1997 drinkingwater advisory guidance and determined that there was insufficient information available onMTBE health effects and exposure to allow EPA to establish a national primary drinking waterregulation. The drinking water advisory document indicated there is little likelihood that MTBEconcentrations between 20 and 40 µg/L would cause adverse health effects. Nevertheless,California and New Hampshire have proposed health-based primary drinking water standards of13 µg/L for MTBE.

C. How Widespread is the MTBE Contamination?

Each year approximately 9 million gallons of gasoline (the equivalent of a fullsupertanker) are released to the environment in the United States from leaks and spills, accordingto an estimate by the Alliance for Proper Gasoline Handling. (Ref. 17) MTBE may be present in a substantial portion of these releases. Because of MTBE's solubility in water and resistance to degradation, it is being detected with increasing frequency in both groundwater and surface water. The potential for harm posed by MTBE releases can perhapsbest be understood by reviewing some well-documented case studies. The releases of MTBE thatoccurred in these situations could have occurred, and could be repeated, virtually anywhere in theUnited States. Larger-scale studies document the widespread detection of MTBE in the nation'swater supplies.

1. Examples of MTBE contamination . The City of Santa Monica,California, has historically relied on seven wells from the Arcadia and Charnock well fields toprovide approximately 50% of the drinking water to the town's 87,000 residents. In August of1995, the City found MTBE in water derived from the Charnock Wellfield. By April of 1996,MTBE levels had risen dramatically in all wells, with concentrations reaching up to 610 ppb. Allfive of the city's Charnock wells were shut down in 1996. The Southern California WaterCompany (SCWC), which had withdrawn drinking water from the Charnock well field, alsoclosed its two production wells to avoid drawing contamination into the wells. The SCWCCharnock wells had provided a portion of the drinking water for 10,000 residences in Culver City,California. After completion of screening level investigations at 28 underground storage tanks (USTs) locations and twogasoline product pipelines, the EPA and the Los Angeles Regional Water Quality Control Board(RWQCB) identified 25 USTs as contributing contamination to the Charnock Sub-Basin, thegroundwater basin which supplies water to the Charnock Wellfields. From 1997-1999, threecompanies potentially responsible for the contamination voluntarily conducted testing ofwellhead drinking water treatment technologies, performed regional groundwater investigationactivities, and reimbursed the City of Santa Monica and Southern California Water Company forwater replacement costs. These companies claim to have spent over $50 million on responseactivities to date. Since 1996, the city and SCWC have met their municipal water demand byutilizing water purchased from the Metropolitan Water District, at a cost of over $3 million peryear. Together with the Agencies' oversight cost and the costs of investigation and cleanup at allthe UST locations and gasoline product pipelines, it is estimated that over $60 million in responsecosts have been expended in addressing the Charnock Wellfield problem to date. In September1999, EPA and RWQCB issued orders to potentially responsible parties that require them to payfor replacement water for the affected homeowners from January 2000 until January 2005. Afinal cleanup is expected to cost more than $160 million.

Contamination of the Arcadia field was traced to a single gas station. The gas stationwas demolished, underground tanks and lines were removed, and approximately 2,000 cubic yardsof gasoline-containing soils were excavated. Cleanup crews are now working to control andremove additional sources of contamination from the area. In addition, a shallow groundwaterpump and treat system was installed in October 1997 to control further migration of thecontaminated groundwater. The extracted water is filtered through three carbon beds to remove the bulk of MTBE before the water is discharged into the sanitary sewer. Actions are currently underway to begin additional treatment of water from the Arcadia wells with carbon and eventually obtain a permit to serve the water as drinking water.

In Glennville, California, residential drinking wells were contaminated with MTBE atlevels up to 20,000 ppb. The likely source of the contamination was an USTand associated piping at the town's only gas station. The town was forced to start using analternative drinking water source in 1997, and still relies on alternative sources of water.

In Whitefield, Maine, an automobile gasoline leak of 20 gallons or less contaminateda bedrock drinking water well for an elementary school with MTBE to a level of 900 µg/L.According to a report by the the Northeast States for Coordinated Air Use Management(NESCAUM), the State of Maine traced the source of the spill to an area about 120 feet from thewell where cars were parked on the grass. (Ref. 18)

In December 1997, a car accident in Standish, Maine, led to the release of 8 to 10gallons of gasoline that contaminated 24 nearby private wells. Eleven wells were contaminatedwith MTBE to a level above 35 µg/L; two were contaminated at over 1,000 µg/L; and the wellnearest the accident site contained the highest concentration of 6,500 µg/L. When the Statediscovered the contaminated wells in May 1998, it removed 79 cubic yards of contaminated soil.The contamination extended to the top of the underlying bedrock at a depth of 9 feet below thesurface. (Ref. 19)

In the town of Windham, Maine, two public water supply wells 900 to 1,100 feetfrom underground gasoline tanks were contaminated to levels of 1 to 6 µg/L MTBE. Accordingto a NESCAUM report, the tanks were state-of-the-art technology, double walled and only 10months old when the MTBE contamination was discovered. (Ref. 20) Extensive testing showed thatthe tanks did not leak directly to the ground, nor were any vapor leaks found after extensivetesting. NESCAUM stated that the only plausible cause of the contamination was gasolineoverfills. The amount spilled was estimated to be 10 to 40 gallons.

MTBE has also been detected in surface waters of lakes and reservoirs. AUniversity of California, Davis, study was conducted at Donner Lake, California. (Ref. 21) The lake isa source of drinking water for lakeside residents and contributes to the drinking water supply ofdownstream communities, such as Reno, Nevada. MTBE levels were low during winter months,at just above the 0.1 µg/L level of detection. Levels increased dramatically during the summerboating season to a high of 12.1 µg/L. Following Labor Day, boat use declined dramatically, asdid MTBE levels. Volatilization between the air/water interface appeared to be the major avenuefor loss of MTBE.

In Shasta Lake, a large recreational-use reservoir in northern California, MTBEconcentrations were reported to range from 9-88 µg/L over the Labor Day 1996 weekend.Maximum values were associated with large boats entering a docking area or with engine exhaustfrom those boats. MTBE was also measured in a temporary lake constructed in southernCalifornia for a jetski event in the summer of 1996. After the 3-day event, concentrationsreportedly ranged from 50-60 µg/L.

On January 28, 2000, a tanker truck rolled over on Route 110 in Lowell,Massachusetts, releasing approximately 11,000 gallons of gasoline. Most of the gasoline enteredthe Merrimack River. The cities of Tewksbury, Methuen, and Lawrence each have drinking waterintakes on the River downstream of the spill site. Although contaminants were not detected at thedrinking water treatment plants the night of the spill, later samples indicated elevated levels ofMTBE. The cities of Tewksbury and Lawrence temporarily closed their drinking water treatmentfacilities and purchased water from alternative sources; the treatment facility in Methuen remainedopen. MTBE levels dropped significantly after a few days, and the facilities were advised thatthey could safely use their intakes.

2. Large-scale studies . Although scattered incidents of localized watercontamination by MTBE have been reported since the early 1980s, the first report to suggest thatMTBE contamination of water might be occurring on a widespread basis came as a result of thesampling of ambient groundwater conducted by the USGS National Water Quality AssessmentProgram (NAWQA). Ambient groundwater is groundwater where there are no known pointsources of contamination prior to sampling in drinking water and non-drinking water wells. In aninitial report of sampling conducted in shallow groundwater in 1993 and 1994, USGS reportedthat of 210 sampled wells and springs in 8 urban areas, 56 (27%) contained MTBE at a minimumreporting level of 0.2 µ>g/L, and 3% of the wells and springs had MTBE concentrations exceeding20 µg/L. (Ref. 22) The maximum concentration of MTBE detected in these urban areas was over 100 µg/L.

The USGS collected data in 1995 from additional wells in urban areas and combinedthem with data from 1993-1994 to provide specific information on drinking water aquifers.This analysis showed MTBE detections in 12 (14%) of 83 shallow urban wells located in aquiferssupplying drinking water and in 19 (2%) of 949 rural wells in aquifers used for drinking water,with a median concentration of approximately 0.50 µg/L. (Ref. 23)

Finally, in a 1999 publication in the Proceedings of the 1999 Water ResourcesConference of the American Water Works Association, USGS assembled its early ambientgroundwater data with additional data from urban and rural wells. (Ref. 24) For urban areas, thefrequency of detection of MTBE in groundwater in areas of substantial MTBE use was about27% (49 of 184 wells), whereas frequency of detection in non-substantial use areas was about5%. In rural areas, the frequency of detection of MTBE in areas of substantial MTBE use wasabout 17% (50 of 298 wells), whereas the frequency of detection in non-substantial use areas wasabout 2%. Overall,USGS found detections of MTBE in 21% of ambient groundwater tested in areas where MTBE is used in RFG compared with 2% of ambient groundwater in areas using conventional gasoline. In contrast, BTEX was found in only 4% of areas where RFG or winter oxyfuels were used. (Ref. 25)

Preliminary results from a joint USGS/EPA study of 12 northeastern States (with adetection limit of 1.0 µg/L) show that MTBE was detected in 7% of drinking water supplies,with 0.8% of these detections above 20 µg/L. (Ref. 26) The study also concluded that MTBE isdetected five times more frequently in drinking water from community water systems in RFG or Winter Oxyfuel areas than in non-RFG or non-Winter Oxyfuel areas. The study showed BTEX detections in 8.3% of the systems analyzed (2,097 systems). Although collectively BTEX was found at approximately the same frequency as MTBE, there is very little co-occurrence of the BTEX compounds with MTBE (less than 1% of the systems). This may indicate that MTBE separated from the rest of the contaminants in the original gasoline plumes, but it also indicates that the increased use of MTBE since 1995 may have created a new universe of contaminated water supplies.

In 1998, the State of Maine reported on sampling conducted on 951 householddrinking water wells and 793 public water supplies. (Ref. 27) The study was designed to be statisticallyrepresentative of the entire State. MTBE was detected in 150 (15.8%) of the sampled householdwells at a minimum reporting level of 0.1 µg/L, and 1.1% of the wells contained MTBE levelsexceeding 35 µg/L. The Maine report projected that approximately 1,400-5,200 private wellsacross the State could be contaminated at levels exceeding 35 µg/L. For public water systemssampled, 125 (16%) showed detectable levels of MTBE, 48 (6.1%) between 1 µg/L and 35 µg/L,and no samples above 35 µg/L.

In another study reported in 1998, the American Water Works Service Companycollected data from drinking water wells in 16 States. (Ref. 28) Forty-four (2%) of 2,120 samplesfrom 17 (4%) of 450 wells tested positive for MTBE at a minimum reporting level of 0.2 µg/L,with the highest concentration at 8 µg/L.

In a 1998 industry study of 700 service stations known to have released gasoline,MTBE was detected at 83% of the sites, with about 43% of the sites having MTBEconcentrations greater than 1,000 µg/L. (Ref. 29) A large percentage (76%) of station sites sampled inFlorida showed MTBE contamination, even though Florida does not participate in the RFG or winter oxyfuel programs. It is assumed that MTBE was used as an octane enhancer in gasoline releasedfrom Florida service stations.

An EPA-supported survey of the 50 States and District of Columbia in 1998 foundthat, of the 34 States that acquire MTBE data from leaking underground storage tank (LUST) sites, 27(79%) indicated that MTBE was present at more than 20% of their sites, and 10 (29%) reportedMTBE at more than 80% of their sites. (Ref. 30) The survey also asked about contamination ofdrinking water wells. Of the 40 State programs that responded, 25 (51%) had received reports ofprivate wells contaminated with MTBE. In addition, 19 (39%) of the programs reported publicdrinking water wells contaminated with MTBE. Five of the States responding to the surveyreported that MTBE was detected in groundwater at LUST sites where the product released wasnot gasoline. MTBE concentrations of greater than 20 µg/L in groundwater had occurred as the result of releasesof diesel fuel, jet fuel, heating oil, aviation fuel, and waste oil. Apparently, MTBE cross-contaminated other petroleum products during transport and distribution. A study of fuel releasesin Connecticut (Ref. 31) provides further evidence of MTBE contamination of heating oil. In thisstudy, 27 heating oil release sites resulted in MTBE contamination of groundwater withconcentrations ranging from 1 to 4,100 µg/L. At the site with the highest concentration of MTBEin groundwater, MTBE was measured in the heating oil at a concentration of 14 milligram/Liter (mg/L).

Individual case studies suggest that, depending on the hydrogeology of the site,significant MTBE contamination of water supplies could occur and is costly and time-consumingto remedy. The large-scale studies indicate that MTBE releases have occurred in many places,with documented detections in public and private drinking water sources.

D. What are the Major Sources of MTBE Contamination and How are They CurrentlyRegulated?

As a large industrialized nation, the United States produces, distributes, andconsumes extensive quantities of gasoline, and much of that gasoline contains MTBE. The DOE estimates that in 1998, over 126 billion gallons of gasoline were sold in theUnited States (Ref. 32) RFG represented 41.5 billion gallons of that total, with the vast majoritycontaining MTBE as the primary oxygenate. After production in the United States or import,gasoline may travel through thousands of miles of pipelines, or be transported by truck, to any ofroughly 10,000 terminals and bulk stations. From there it may be distributed to one of 180,000retail outlets and fleet storage facilities, or to any of hundreds of thousands of above-ground orunderground tanks at farms, industrial facilities, businesses, and homes. Finally, gasoline isremoved from bulk storage into individualized storage units associated with such products as cars,trucks, boats, planes, lawn mowers, brush cutters, and chain saws. Residual gasoline in transportconduits may contaminate different types of fuels (e.g., home heating oil) that is transportedthrough the same conduits at different times. Although this does not normally cause problems, itmay explain why MTBE has been found in releases of home heating oil and other fuels. Thereare opportunities for leaks wherever gasoline (or a product containing gasoline) is stored, and there are opportunities for spills whenever fuel is transported or transferred from one container to another. Although many Federal and State programs have been developed to minimize the potential for leaks and spills from the vast array of units and individuals handling gasoline, no system involving so much product and so many individual handlers can be foolproof. Gasoline is released to the environment every day; these releases can be expected to continue and MTBE, being more soluble and less biodegradable than BTEX, will move more quickly and at higher concentrations than the other components of gasoline, making its way to surface water and groundwater resources. This unit describes the major sources of gasoline leaks, and summarizes regulatory programs applicable to them.

1. Underground storage tanks . There are an estimated 760,000 USTs currently inuse for petroleum storage in the United States that are subject to regulation under Subtitle I ofthe Resource Conservation and Recovery Act (RCRA), 42 U.S.C . 6991a-i. These tanks have astorage capacity of approximately 6 billion gallons. In addition, there are approximately 3 to 4million USTs storing fuel that are exempt from RCRA Subtitle I regulation including:

a. Farm and residential tanks of 1,100 gallons or less capacity holding motor fuel fornoncommercial purposes.

b. Tanks storing heating oil used on the premises where it is stored.

c. Tanks on or above the floor of underground areas, such as basements or tunnels.

d. Septic tanks and systems for collecting storm water and wastewater.

e. Flow-through process tanks.

f. Tanks of 110 gallons or less capacity.

g. Emergency spill and overfill tanks.

Leaking USTs have been identified as the likely sources of a number of the moreproblematic releases of MTBE to the environment, including releases that have closed watersupplies in Santa Monica and Glennville, California. In California alone, the minimum numberof MTBE point sources from leaking UST sites is estimated at greater than 10,000.

In 1988, EPA issued regulations setting minimum standards for RCRA Subtitle I-regulated UST systems. Existing UST systems, those installed on or before December 22, 1988,had until December 22, 1998, to upgrade with spill, overfill, and corrosion protection, properlyclose, or meet new tank performance standards. Any UST system installed after December 22,1988, had to meet new tank performance standards for spill, overfill, and corrosion protection atthe time of installation. Based on reports received as of the end of September 1999, EPAestimates that approximately 85% of the RCRA-regulated universe of UST systems currentlymeet EPA's upgrade or new tank requirements. By the end of 2000, EPA expects thatapproximately 90% of RCRA-regulated USTs will be in compliance, leaving approximately70,000 substandard USTs.

The Federal regulations also require that UST systems have release detectionequipment to identify releases to the environment. The regulations required that all owners andoperators install and properly operate a method of release detection no later than 1993 based onthe age of the UST system. While virtually all UST systems are equipped with leak detectionequipment, they are not necessarily installed or operated properly. Largely as a result ofproblems with proper operation of leak detection equipment, EPA estimates that approximately60% of UST systems are in compliance with the leak detection requirements. By the end of2005, EPA expects compliance with the leak detection requirements will be 90%.

EPA provides funding (through the Leaking Underground Storage Tank Trust Fund)to States to oversee the cleanup of releases from USTs. Since the UST program began,approximately 400,000 releases from USTs have been confirmed; of that number, approximately230,000 cleanups have been completed. While not every State is testing for MTBE at UST releasesites, those that do have found MTBE at most, if not all, release sites. In response to arecommendation by the Blue Ribbon Panel (the Panel), EPA recently sent a memo to all State UST programsrecommending that they monitor for and report MTBE in groundwater at all leaking UST sites.

Those facilities that have a total underground oil storage capacity of more than 42,000gallons, and which are located such that they could reasonably be expected to discharge oil intonavigable waters or adjoining shorelines, are subject to EPA requirements for the development ofSpill Prevention, Control and Countermeasure (SPCC) Plans pursuant to Clean Water Act (CWA) section 311(j)(1)(C). An SPCC plan is a detailed, facility-specific description of how the facilitywill comply with EPA regulatory requirements for secondary containment, facility drainage, dikesor barriers, sump and collection systems, retention ponds, curbing, tank corrosion protectionsystems, and liquid level devices (40 CFR 112.1-112.7). To avoid duplicative regulationunder the RCRA and CWA section 311 programs, EPA proposed in 1991 to exempt from SPCCrequirements those completely buried tanks that are subject to RCRA Subtitle I requirements.EPA expects to issue a final rule dealing with this and other modifications to the SPCC programlater in 2000.

It is important to understand that even after USTs are in full compliance with theRCRA and CWA section 311 requirements, some releases are expected to occur as a result ofimproper installation or upgrading, improper operation and maintenance, and accidents.

2. Above-ground storage tanks . EPA regulates under the CWA section 311SPCC program approximately 440,000 facilities with above-ground storage tanks (ASTs) that arelocated so as to be reasonably expected to discharge oil to surface waters or adjoining shorelines.A facility is regulated if it has an AST with a capacity of more than 660 gallons, or multiple ASTswith a combined capacity of more than 1,320 gallons. ASTs are also subject to EPA's moregeneral requirements for the reporting of oil spills to navigable waters, 40 CFR part 110, andEPA's prohibition on the discharge to navigable waters of oil in quantities that will:

a. Violate applicable water quality standards.

b. Cause a sheen on the waters.

c. Cause a sludge or emulsion to be deposited beneath the surface of the water or adjoiningshoreline (40 CFR 110.3).

Despite EPA's regulatory programs, almost 20,000 oil spills to navigable water (from all sources, including tank trucks, barges, etc.) are reported each year. About half, or 10,000 spills, occur annually to the inland zoneover which EPA has jurisdiction, while the other half occurs in the coastal zone over which theCoast Guard exercises jurisdiction.

3. Pipelines . Excluding intrastate pipelines and small gathering linesassociated with crude oil production fields, there are approximately 160,000 miles of liquidspipelines in the United States. These pipelines transport approximately 525 billion gallons ofcrude oil and refined products annually. The Department of Transportation (DOT) estimates that, over arecent 5-year period (1994-1998), an average of 29 gasoline spills occurred annually frompipelines, with the total volume of gasoline released from pipelines averaging 1.03 million gallonsper year. While there are little or no data on the extent of MTBE releases from pipelines, MTBEis expected to be present in some portion of the refined product in the pipelines.

In California, pipeline release data are currently being compiled by the Office of theState Fire Marshal, which regulates approximately 8,500 miles of pipelines. Since 1981, therehave been approximately 300 pipeline releases within the State Fire Marshal's Jurisdiction. (Ref. 33)

Pipelines are regulated by the DOT, Research and Special Programs Administration (RSPA). Under authority of the Pipeline Safety Act of 1992, 49 U.S.C. 60101 et seq ., DOT has established minimum safety standards for pipelines carryinghazardous liquids, including petroleum and petroleum products (49 CFR part 195). Underauthority of CWA section 311, DOT also requires response planning for pipelines that, because oftheir location, could reasonably be expected to cause substantial harm to the environment bydischarging oil into or on the navigable water, adjoining shorelines, or the exclusive economiczones (49 CFR part 194).

4. Other releases . Releases from automobile accidents, tank truck spills,consumer disposal of "old" gasoline, and spills during fueling operations have been identified assources of contamination of drinking water wells. The incidents in Maine, described in Unit III.C.1. are examples of how relatively small spills can result in contamination of nearby drinkingwater supplies. Home heating oil storage tanks have also been identified as potential sources ofMTBE contamination, as MTBE might be present from mixing the heating oil with small volumesof gasoline in the bulk fuel distribution or tank truck delivery systems. Other data on releases ofthis type are not available, and EPA is not aware of any efforts currently underway to furthercharacterize these sources of MTBE contamination.

EPA regulatory programs do not address small episodic releases of gasoline unlessthey result in a discharge to surface waters. For those releases, the spill must be reported, and theresponsible party may be penalized for any violation of EPA's oil discharge prohibition. In themany cases involving accidental spills, however, these requirements are not effective in preventingreleases.

5. Watercraft . Gasoline-powered watercraft have contributed to thecontamination of lakes and reservoirs with MTBE. The two-stroke engines commonly used forcertain watercraft can discharge up to 30% of each gallon of gasoline as unburned hydrocarbons. (EPA issued a final rule to reduce the amount of air emissions from new gasoline-powered watercraft and outboard motors which will be phased-in beginning in 1998, and completed in the 2006 model year. This rule is also expected to reduce the release of unburned hydrocarbons from new engines into surface waters. This rulemaking published in the Federal Register of October 4, 1996 (61 FR 52088) (FRL-5548-8), which applies only to new engines, will reduce hydrocarbon emissions by 75%. The State of California requires that EPA's new standards be fully implemented by 2001). Asdescribed in Unit III.C.1., concentrations of MTBE in lakes with significant recreational boatingtend to peak in the boating season at levels that can be a concern for taste and odor, and possiblyhuman health, and decrease fairly rapidly after the boating season has ended. Volatilization at theair/water surface is considered the dominant mechanism for this removal process.

Although most discharges of pollutants from point sources (e.g., pipes and otherdiscrete conveyances) to surface waters must be authorized under CWA section 402 by aNational Pollutant Discharge Elimination System (NPDES) permit, discharges from properlyfunctioning marine engines are currently subject to a regulatory exemption from this requirement (40 CFR 122.3 (a)).

6. Storm water runoff. Storm water runoff becomes contaminated withMTBE from the dissolution of residual MTBE from parking lots and roadways, as well as fromatmospheric washout during precipitation events. The USGS has characterized MTBEconcentrations in runoff in many areas and has found such contamination typically to be lowerthan 2 ppb. (Ref. 34) The National Science and Technology Council's 1997 Interagency Assessment ofOxygenated Fuels Report describes storm water runoff as exhibiting concentrations of 0.2-8.7ppb in 7% of the samples tested in 16 cities from 1991 to 1995. (Ref. 35) Most detections in thisstudy were in the Denver area, where implementation of the Wintertime Oxyfuel program beganin 1988. Based on predictive modeling, concentrations in rainwater (in µg/L) are expected to beequivalent to the surrounding air concentrations (in ppb, volume). MTBE air concentrations tendto be less than 1 ppb in urban areas, leading to predicted rainwater levels of 1 µg/L or less.However, rainwater around localized areas of high MTBE air concentrations (e.g., parkinggarages) could contain correspondingly higher levels of MTBE. Storm water may be dischargedto surface water or percolate to groundwater, and thus serves as a continuing source of low-levelMTBE contamination of these potential drinking water sources.

Clean Water Act NPDES permit requirements apply to certain discharges of stormwater which may contain MTBE. Though many discharges of storm water are not subject topermit requirements, NPDES permits are required for industrial storm water discharges,discharges from municipal separate storm sewer systems, and storm water discharges specificallydesignated by EPA or authorized NPDES States. Although MTBE is not typically targeted inthese permits, the best management practices and planning requirements usually specified arelikely to reduce MTBE discharges through storm water.

As this summary demonstrates, there are a number of programs in place to minimizeor mitigate the effects of gasoline releases. However, in light of the volume of gasoline used andthe myriad opportunities for leaks, spills, and accidents, substantial releases of gasoline are likelyto continue to occur in the future.

E. How Practical is it to Cleanup Drinking Water Supplies to Remove MTBE?

Because spills of conventional gasoline typically move slowly through groundwater,and are biodegraded over time, many are left in place to undergo bioremediation at no cost otherthan temporarily replacing the water supply. However, MTBE moves rapidly with groundwater,is not readily degraded in the groundwater environment, and can render groundwater unpotable atlow levels. Therefore, spills involving MTBE require much more aggressive management andremediation than do spills of conventional gasoline.

MTBE's chemical properties also make it difficult or costly to remediate usingconventional "active" processes. Two common treatment techniques are air stripping and use ofgranular activated carbon (GAC). In air stripping, contaminated groundwater is passed throughan aeration tower that effectively removes the chemicals from the water and releases it into the air.Where necessary, the chemical is then removed from the air into a solid medium that can bedisposed of. MTBE does not readily partition from water to the vapor phase. Air stripping ofMTBE is most effective when higher air to water ratios, or higher temperatures are used thanwould be required for other more volatile compounds. In a GAC system, water is passed throughone or more beds of carbon; contaminants in the water are sorbed onto the carbon, which caneither be disposed of or "refreshed" by driving out the contaminants (usually by heating).However, the relatively low sorption of MTBE to solid particles means that the GAC must be usedin greater quantities, driving up treatment costs. As a practical matter, therefore, MTBE-contaminated groundwater is difficult and costly to remediate.

F. What Action did EPA's Blue Ribbon Panel Recommend?

In November 1998, EPA established a the Panel to investigateair quality benefits and water quality concerns associated with the use of oxygenates, includingMTBE, in gasoline. The Panel was established under EPA's Clean Air Act Advisory Committee,a policy committee established to advise EPA on issues related to implementing the CAAAmendments of 1990.

The Panel members consisted of leading experts from the public health,environmental and scientific communities, automotive and fuels industry, water utilities, and localand State governments. The Panel met six times from January to June 1999, with the charge to:

1. Examine the role of oxygenates in meeting the nation's goal of clean air.

2. Evaluate each product's efficiency in providing clean air benefits and the existence ofalternatives.

3. Assess the behavior of oxygenates in the environment.

4. Review any known health effects.

5. Compare the cost of production and use and each product's availability-both at presentand in the future.

Further, the Panel studied the causes of groundwater and drinking water contaminationfrom motor vehicle fuels, and explored prevention and cleanup technologies for water and soil. InSeptember 1999, the Panel released its report, entitled Achieving Clean Air and Clean Water , The Report of the Blue Ribbon Panel on Oxygenates in Gasoline . TheReport is available in the docket to this ANPRM, and is also available onhttp://www.epa.gov/oms/consumer/fuels/oxypanel.blueribb.htm.

The Panel recommended a package of reforms to ensure that water supplies are better protected while the substantial reductions in air pollution that have resulted from RFG are maintained. The Panel enumerated 16 suggestions for Federal, State, and Congressional action, including the following:

• Recommended a comprehensive set of improvements to the nation's waterprotection programs, including over 20 specific actions to enhance UST, safe drinking water, and private-well protection programs.

• Agreed broadly that use of MTBE should be reduced substantially (with some members supporting its complete phase out), and recommended action by Congress to clarifyFederal and State authority to regulate and/or eliminate the use of MTBE and other gasoline additives that threaten drinking water supplies.

• Recommended that Congress act to remove the current CAA requirement that 2% of RFG, by weight, consist of oxygen, to ensure that adequate fuel supplies can be blended in a cost-effective manner while quickly reducing usage of MTBE.

• Recommended that EPA take action to ensure that there is no loss of current air quality benefits associated with the use of MTBE.

While the Panel indicated that its recommendations should be implemented as a complete package, it also stated that "the majority of these recommendations could be implemented by Federal and State environmental agencies without further legislative action, andwe would urge their rapid implementation."

Although the Panel agreed broadly on its recommendations, two members, while ingeneral agreement with the Panel, had concerns with specific provisions: The MTBE industryrepresentative disagreed with the recommendation to limit the use of MTBE, and the ethanolindustry representative disagreed with the recommendation that the CAA requirement thatoxygenates be used in RFG be eliminated. Some Panel members believed that MTBE useshould be banned altogether.

EPA agrees with the concerns raised in the report of the Panelregarding the continued use of MTBE as a fuel additive, and will consider its recommendationsfurther as it proceeds through a TSCA section 6 rulemaking to limit or ban MTBE's use ingasoline.

IV. Section 6 of the Toxic Substances Control Act

A. What is the Scope of TSCA Section 6 Authority?

Section 6 of TSCA, 15 U.S.C. 2605, provides EPA with broad authority to issuerules to regulate the manufacture, processing, distribution in commerce, use, and/or disposal ofchemical substances in the United States where such regulation is necessary to preventunreasonable risks to health or the environment. The Agency and courts have interpreted the"unreasonable risk" standard to be a risk-benefit standard, allowing regulation where risks tohealth or the environment posed by a particular activity or activities involving a chemicaloutweigh the benefits associated with such activity or activities. TSCA section 6 lists a numberof possible forms that such regulation may take, including:

1. Regulating the manufacturing, processing, or distribution in commerce of a chemicalsubstance, including a complete ban of any such activity or limiting the amounts of the chemicalsubstances that may be manufactured, processed, or distributed in commerce.

2. Regulating the manufacturing, processing, or distribution in commerce of a chemicalsubstance for a particular use or uses, including banning any such activity for a particular use oruses of the chemical substance; limiting the concentration of the chemical substance that may beused in any such activity; or limiting the amounts of the chemical substance that may bemanufactured, processed, or distributed in commerce for such particular use or uses.

3. Requiring that the chemical substance be accompanied by such warning statementsand/or instructions for use with respect to its use, distribution in commerce, and/or disposal asthe Administrator finds necessary.

4. Requiring manufacturers and/or processors of a chemical substance to make and retainsuch records of the manufacturing process as the Administrator finds necessary and/or tomonitor or conduct tests which are reasonable and necessary to assure compliance with a ruleunder TSCA section 6.

5. Prohibiting or regulating any manner or method of commercial use of a chemicalsubstance.

6. Prohibiting or regulating the disposal of a chemical substance.

7. Requiring manufacturers or processors of a chemical substance to provide warnings todistributors or users of the substance and to replace or repurchase such substance.

TSCA section 6(a) directs the Agency to apply the least burdensome of theidentified regulatory options to the extent necessary to mitigate the unreasonable risk. Thestatute also makes clear that the Agency may select a combination of the options, and may limitthe geographic application of a rule under TSCA section 6(a).

In promulgating any rule under TSCA section 6(a), TSCA section 6(c) requires theAgency to publish a statement addressing:

1. The effect of the chemical substance being regulated on health and the magnitude ofexposure of humans to the substance.

2. The effects of such substance on the environment and the magnitude of exposure of theenvironment to the substance.

3. The benefits of such substance for various uses and the availability of substitutes for suchuses.

4. The reasonably ascertainable economic consequences of the rule, after consideration ofthe effect on the national economy, small business, technological innovation, the environment,and public health.

TSCA section 6(c) also provides that if the Administrator determines that the risk ofinjury to health or the environment could be eliminated or reduced to a sufficient extent throughactions taken under another statute administered by EPA, she may not promulgate a rule underTSCA section 6 unless the Administrator finds, in her discretion, that it is in the publicinterest to protect against such risk under TSCA. In making this finding, the Administrator mustconsider all relevant aspects of the risk; a comparison of the estimated costs of complying withactions taken under TSCA and any other statute that adequately addresses the risk; and therelative efficiency of actions under TSCA and such other statute to address the risk.

Any rulemaking under TSCA section 6 includes the opportunity for any interestedperson to request an informal hearing. Such hearings could be limited to the right to present anoral statement, or could include the right to present and cross-examine witnesses if theAdministrator determines that there are disputed issues of material fact necessary to be resolvedand that cross-examination of witnesses is both appropriate and required for full and truedisclosure with respect to such issues.

B. How Would EPA Apply TSCA Section 6 to Risks Associated with MTBE?

As discussed earlier, the use of MTBE as an additive in gasoline has resulted, and if unchanged is likely to continue to result, in the widespread release of MTBE into the environment; MTBE is difficult to contain and prevent from reaching sources of drinking water once it is released into the environment; and it has the potential to render drinking water unpotable at low levels and unsafe at higher levels. EPA's review of existing information on contamination of drinking water resources by MTBE indicates substantial evidence of a significant risk to the nation's drinking water supply. A comprehensive approach to such risk must include consideration of either reducing or eliminating the use of MTBE as a gasoline additive. As a result, EPA is initiating this process pursuant to the unreasonable risk provision under TSCA section 6 to eliminate or greatly reduce the use of MTBE as a gasoline additive. EPA is interested in comments on both the risk and these possible responses to it. In accordance with the requirements of TSCA section 6, EPA will consider whether there are other appropriate mechanisms to address the problems presented by the use of MTBE as a gasoline additive. Thus, the outcome of this rulemaking could be a total ban on the use of MTBE as a gasoline additive. Consistent with TSCA section 6, EPA will carefully consider regulatory alternatives to a ban. These could include limiting the amount of MTBE that could be used in gasoline, limiting use of MTBE in particular geographic areas or during particular times of year; limiting the types of facilities in which MTBE can be stored; limiting the manner in which MTBE is transported; etc. Any final outcome must, however, provide adequate protection against any unreasonable risk associated with MTBE.

As part of a rulemaking under TSCA section 6, the Agency must also considerwhether action under another statute administered by EPA, such as the CAA, RCRA, CWA, orSDWA, could effectively address the risks posed by MTBE and, if so, whether it is in the publicinterest to regulate the risk under TSCA instead of such other statute. It is worth noting in thisregard that although a number of Agency programs could address some of the risks posed byMTBE (such as, for example, the regulation of USTs under RCRA), TSCA appears to provide the best tool for assessing and addressing the risks posed by MTBE.

As part of the consideration of other programs and identification of the leastburdensome mechanism to provide adequate protection against the risks of MTBE, the Agencyexpects to consider a number of possible strategies for mitigating those risks, including preventingMTBE in gasoline from getting into groundwater, cleaning up water contaminated with MTBE,and removing MTBE from gasoline in whole or in part. While the Agency's assessment in thisregard is preliminary at this point, the available evidence suggests that dealing with the problembefore MTBE is added to gasoline may be the best solution for mitigating any unreasonable risks associatedwith MTBE. Given the large quantities of gasoline that are used and transported in the UnitedStates, and the number of different possible avenues for release into the environment (includingleaks from storage tanks and pipelines; spills resulting from loading/unloading gasoline at tanks,gasoline pumps, or pipelines; spills resulting from transportation accidents; un-combusted gasolinefrom boat engines; emissions from automobile exhaust), it may not be practicable to preventsignificant quantities of MTBE from getting into surface water or groundwater once the chemicalis added to gasoline. Similarly, given the importance of groundwater as a drinking water sourcein the United States and the large number of wells and groundwater sources that have been andcould be contaminated with MTBE and the costs and difficulties of cleaning contaminateddrinking water sources, a risk-mitigation strategy centering on cleaning up water may not be thepreferred strategy under TSCA section 6 for mitigating any unreasonable risks associated with MTBE. Consequently, EPA believes that a comprehensive approach must include consideration of either reducing or eliminating the use of MTBE as a gasoline additive.

In conducting this rulemaking under TSCA section 6, the Agency will also consider the costs and impacts of alternatives to MTBE.In oxygenated gasoline programs like Federal RFG, the most likely substitute based on currentusage is ethanol. Other ether compounds are currently used as oxygenates in small quantities.MTBE does not occupy as dominant a position as an octane enhancer for conventional gasoline asit does as an oxygenate in RFG. Ethanol, alkylates, and aromatics are alternative octaneenhancers in conventional gasoline. Although EPA is seeking more information on alternatives to MTBE, EPA does not expectethanol, alkylates, or aromatics to present the same magnitude of risk to drinking water suppliesas MTBE. Ethanol biodegrades more quickly than MTBE, and therefore is less likely tocontaminate drinking water as often as MTBE, or at the levels of MTBE. Alkylates andaromatics are expected to behave in soil and water more like other components typically found ingasoline than MTBE; they too would be unlikely to contaminate drinking water as often asMTBE or at the levels of MTBE. Other ether compounds are not currently used widely asoxygenates, and the Agency does not have much data to characterize the risks they might pose todrinking water supplies. However, they are chemically similar to MTBE, and they may well movethrough soil and water in ways and amounts similar to MTBE. EPA will closely evaluate the likelihood that compounds not currently used in significant quantities as oxygenates in RFG might be widely used as alternatives to MTBE, whether additional information on these compounds is necessary, and whether other measures are appropriate to assure that an elimination or limitation of MTBE in gasoline does not result in the use of alternatives that might cause similar risks to drinking water. It appears that eliminating or limiting the use of MTBE as a fuel additive will result in increased costs in producing gasoline of approximately $1.9 billion per year if the oxygen mandate remains in place.

V. Alternative Gasoline Additives to MTBE

In conducting a rulemaking under TSCA section 6, EPA must consider thealternatives to MTBE. If the use of MTBE as a fuel additive is limited or banned by EPA,refiners will have to look to other chemicals as substitutes. To meet the oxygenate requirementsof RFG, ethanol and other ethers are the most likely alternatives, while ethanol, alkylates, andaromatics will most likely replace MTBE as an octane enhancer. This unit assesses thesechemicals and their potential to replace MTBE in gasoline.

A. What Oxygenates Other Than MTBE Could be Used to Meet RFG Requirements?

If the use of MTBE is limited or banned and the CAA oxygenate requirementremains in place, refiners will have to use a substitute oxygenate to meet the RFG requirements.Ethanol and other ethers are the most likely oxygenate alternatives.

1. Ethanol . Ethanol is an oxygenate that is produced from agriculturalproducts such as corn. Ethanol and MTBE have been the primary oxygenates used to meet theRFG oxygen content requirements because of their availability, blendability, and ability to deliverair quality benefits. Ethanol is currently the primary oxygenate in about 12.5% of RFG, and it isthe main oxygenate in the Midwest RFG areas.

Despite its current use in RFG, ethanol is not yet manufactured in sufficientvolume to meet total current national oxygenate demands. Current U.S. ethanol productioncapacity is estimated at 120,000 b/d (barrels per day), which is equivalent in oxygen content toapproximately 230,000 b/d of MTBE. In order for ethanol alone to fulfill the nationwide oxygenrequirement in all RFG and oxygenated fuels areas, the Panel estimated that at leastan additional 67,000 b/d of ethanol would be needed. Because of the higher oxygen content ofethanol, a smaller volume of ethanol (5.7%) needs to be added to a gallon of RFG to satisfy theCAA oxygen content requirement than MTBE (11% by volume).

This shortfall in ethanol supply could be fulfilled by a combination of increasingproduction capacity at existing facilities and by building new facilities. The ethanol industryestimates that the current expansion of existing ethanol-from-corn production facilities mayincrease production capacity by as much as 40,000 b/d. (Ref. 36) Additionally, the industry estimatesthat new ethanol production facilities currently being planned could provide another 25,000 b/d.Ethanol production from biomass processing is currently approximately 4,000 b/d. Thus, whilethere is an insufficient supply of ethanol to meet current oxygenate demand, the ethanol industryprojects that future ethanol production should be able to adequately meet the oxygenate demandand replace MTBE given appropriate time. The Department of Agriculture (USDA) hasconcluded that ethanol can fully meet all oxygenate requirements within 4 years. (Ref. 37)

Refiners that currently use MTBE in meeting the oxygenate requirement wouldneed to modify their operations to produce an appropriate blendstock to which ethanol can beadded. Terminals, responsible for actually adding the ethanol to the gasoline, would also have tomodify their facilities. For example, terminals would have to add storage facilities for ethanol.Due to these initial logistical concerns, refiners have stated that an immediate ban on MTBE couldhave a negative impact on the nation's fuel supply.

In addition to initial capital costs, use of ethanol as a replacement for MTBEwould have several long term impacts on the price of gasoline. When added to gasoline, ethanolincreases the Reid Vapor Pressure (RVP) of the gasoline by about 1.0 pound per square inch.RVP is a measure of the gasoline's volatility. An RVP increase results in an increase in emissionsof VOCs from motor vehicles. To compensate for this increase, and to reduce the risk of VOCsevaporating into the air, refiners must blend ethanol gasoline with a low-RVP blendstock. Thislow-RVP blendstock is more expensive to produce or purchase.

In order to make RFG with MTBE, refiners blend MTBE into gasoline. Aftermixture, the RFG is transported to distribution terminals by pipeline. Since ethanol is soluble inwater, which is commonly found in pipelines, and will separate from gasoline, ethanol is usuallyblended at the distribution terminal. Because ethanol is produced primarily in the Midwest,though, it must be transported to terminals by either an ethanol-only pipeline, rail, marine or truckshipping or some combination of these options. It is possible that greater transportationconnections between ethanol producers and terminals will have to be developed. The USDAstudy indicates that given a 3 to 5 year transition period, there does not appear to be atransportation impediment to the use of ethanol as a substitute for MTBE. (Ref. 38)

Economic impacts are not likely to be shared equally among petroleumrefiners/marketers. Each refinery processes different types of crude, supplies different mixes ofproducts (e.g., some refineries do not manufacture any RFG), and use widely varyingtechnologies. Areas of the country that rely heavily on MTBE as an oxygenate will experience amore pronounced economic effect in the event of an oxygenate replacement or removal (e.g.,Texas, California, and Northeast RFG markets use MTBE, whereas the Chicago and MilwaukeeRFG markets use ethanol). In addition, markets farthest from the Midwest may experience agreater effect due to increased transportation costs.

The economic impact of using ethanol as an alternative to MTBE will be reflectedprimarily in the price of gasoline. A 1999 study by the DOE concluded that aphased elimination of MTBE as an additive for oxygenation in RFG in 4 years would result inan increase in the price of RFG of between 2.4 cents per gallon and 3.9 cents per gallon. (Ref. 39) ACalifornia Energy Commission (CEC) study estimated that the price of gasoline in Californiawould increase anywhere from 1.9 cents per gallon to 2.5 cents per gallon in the long term (6years) if ethanol was substituted for MTBE. (Ref. 40) A Chevron/Tosco analysis estimated thatgasoline prices in California would increase 1.9 cents per gallon in the long term (6 years) ifethanol was substituted for MTBE. (Ref. 41)

Pure ethanol is highly soluble in water, and hypothetically should travel ingroundwater at about the same rate as MTBE. Ethanol is not expected to persist in groundwater,though, because it biodegrades easily. Thus, ethanol itself does not appear to pose as great adanger to groundwater supplies as MTBE.

Ethanol's ability to biodegrade does present another potential issue of concern.Laboratory data and hypothetical modeling indicate that based on physical, chemical, and biological properties, ethanol will likely preferentially biodegrade in groundwater compared withother gasoline components. As a result, the levels of BTEX in water may decline more slowly,and BTEX plumes may extend further than they would without ethanol present. However,BTEX does not migrate as quickly as MTBE. Thus, even with the presence of ethanol, BTEXplumes would not be expected to travel as far as MTBE plumes. Although there are limited data regarding the movement of ethanol and BTEX, a recent USGS report cites several examples of MTBE plumes migrating further than BTEX plumes. (Ref. 42) At some sites, MTBE has migrated much further than other common gasoline components and those long travel distances increase the probability that MTBE will be detected in a drinking water well and that treatment may be required.

The health effects of ingested ethanol have been extensively investigated. Given that ethanol is formed naturally in the body at low levels, inhalation exposure to ethanol at the low levels that human are likely to be exposed are generally not expected to result in adverse health effects. (Ref. 43) Ingestion of ethanol in relatively large quantities, increases the risks for several forms of human cancer. (Ref. 44) However, it is highly unlikely that the public will be exposed to large quantities of ethanol from drinking water contamination.

When used as an oxygenate, ethanol blends of RFG achieve all Phase I goals of theRFG program. Ethanol is the primary oxygenate in Chicago and Milwaukee, and those areas haveeasily exceeded all Phase I performance requirements for VOCs, NO X and airtoxics. Thus, use of ethanol as an oxygenate nationwide would not appear to compromisecompliance with air quality requirements; refiners seem able to produce RFG using ethanol thatcomplies with RFG emissions standards. The Panel did note, however, that Chicagoand Milwaukee, while exceeding the Phase I requirements, do not appear to achieve as great areduction in air toxics as do other RFG areas. It is unclear whether MTBE is responsible for thisgreater reduction in air toxics or other aspects of the formulation. Starting in the year 2000, allRFG areas will be subject to more stringent standards for VOC, NO X and toxicsreductions, regardless of which oxygenate is used.

2. Other ethers . A variety of other ethers (ETBE, DIPE, TAME)are currently used in gasoline, though in limited quantities; these ethers provide approximately 5%of the oxygenate used in RFG. These other ethers have found only limited use because they aremore expensive than MTBE. For example, greater volumes of ETBE and TAME are necessaryto achieve the 2.0% weight standard compared to MTBE. Use of ETBE also requires largequantities of ethanol as feedstock. Production supplies of other ethers are also limited. Thecurrent production capacity in this country of TAME is approximately 23,000 b/d. IncreasingETBE production would require refitting MTBE plants, primarily in the Gulf South.Transportation issues could be similar to those involving increased use of ethanol. CEC estimatesthat gasoline prices will increase 2.4 cents per gallon if ETBE is used to replace MTBE. (Ref. 45) This estimate is specific to California.

Given their similarity to MTBE, other ethers are likely to display similar chemicalproperties-high solubility in groundwater, poor sorption in soil, and slower biodegradationcompared to BTEX. MTBE has become a concern in large part because of its chemicalproperties. MTBE can travel farther than other gasoline constituents and can create largercontamination plumes, making it more likely to impact drinking water supplies. Other ethers arelikely to demonstrate the same properties and thus could well raise similar water contaminationconcerns as MTBE. No studies have been reported on the carcinogenicity of ETBE, TAME, or TBA.

B. What Compounds Other Than MTBE Could be Added to Gasoline to Boost Octane?

In addition to its use as an oxygenate, MTBE is also used as an octane enhancer inconventional gasoline. However, while MTBE is the dominant oxygenate additive in RFG, it isnot the predominant octane enhancing additive in conventional gasoline. More conventionalgasoline contains ethanol as an octane enhancer than contains MTBE for that purpose. In 1997,approximately 12,000 b/d of MTBE were used for octane enhancement purposes. If MTBE isbanned or its use as an octane enhancer is limited, refineries will have to look to other alternativesto replace this source of octane. There are a limited number of octane-rich components thatrefiners can choose to produce needed octane. Ethanol, alkylates, and aromatics are the threemost likely available alternatives to MTBE for use as an octane enhancer in conventional gasoline.Ethanol as an additive is discussed in Unit V.A.1.

1. Alkylates . Alkylates are a mix of high octane, low vapor pressurecompounds that are produced from crude oil through a catalytic cracking process. Because oftheir desirable properties, alkylates are popular components for use in gasoline.

In order for a refiner to use alkylates as an octane enhancer, the refiner mustpossess an alkylation unit. According to an industry estimate, an alkylation unit can cost up to$80 million for a refinery that produces 10,000 b/d of alkylate. (Ref. 46) Refiners that donot currently use alkylates would have to make a substantial initial capital investment in order todo so. In addition, refiners would need to adjust other component streams to accommodate thechange in vapor pressure characteristics associated with a fuel containing high alkylate content.

Supply of alkylates could be a key economic consideration. There are currentlynot enough domestic alkylates available to make up for the loss in MTBE volume. Whileincreasing alkylate production is possible, it appears that refiners in California have limitedpossibilities for such an increase. Alkylate production on the East Coast and Gulf Coast alsoappears to be close to capacity. Given this situation, it may take refiners some number of years tomodify facilities to produce enough alkylates to replace the octane enhancement currentlyprovided by MTBE.

It is unclear, however, how much alkylate is needed to replace MTBE as an octaneenhancer. Only 12,000 b/d of MTBE are currently used for octane enhancement in conventionalgasoline. MTBE has a higher octane value than alkylates, and a simple linear comparison of thesevalues would conclude that 14,350 b/d of alkylates would be necessary to replace MTBE. Thislinear comparison would not take into account several factors important in determining theamount of alkylates used, such as the blend of gasoline. Refineries can be expected to react indifferent ways to these factors to maximize production and economic feasibility and to meetperformance standards.

Alkylates are less soluble in water, and they will not likely pose the same degree ofrisks to water resources as MTBE. Alkylates would be expected to behave more like othercomponents of gasoline (BTEX) than like MTBE if released into the environment. Alkylates thusdo not appear to pose a significant threat to drinking water resources.

According to NESCAUM, increased use of alkylates in gasoline blends will notincrease toxic emissions. (Ref. 47) However, the available human and aquatic toxicity data onalkylates are limited.

2. Aromatics . Aromatics are hydrocarbons which can includebenzene, toluene, and xylene. Toluene is the primary aromatic used for octane enhancing.NESCAUM estimates that current toluene production capacity may be sufficient to produceenough toluene to replace MTBE by volume. (Ref. 48) The aromatics are significantly less likely toend up in drinking water sources in significant quantities after release to the environment than isMTBE.

Aromatics contain compounds that are known to have a range of potential humanhealth effects. Benzene is a known human carcinogen, and xylene is a major contributor to smog.Toluene is associated with some toxic by-products, though it is less toxic than benzene.

VI. Specific Requests for Comment, Data, and Information

Interested persons are invited to comment on any issue raised in this ANPRM.The Agency is particularly interested in receiving additional information and/or commentsaddressing the following issues:

A. EPA Action

As explained in this ANPRM, EPA is initiating this process pursuant to TSCA section 6 to consider eliminating or limiting the use of MTBE in gasoline. EPA requests comment (including comments addressing the health, environmental, and/or cost implications) on:

1. Whether some use of MTBE as a gasoline additive should be allowed to continueand, if so, the level or type of use that should be allowed to continue?

2. How much lead time, if any, would be necessary to enable refiners to eliminateMTBE from RFG while continuing to meet the current levels of compliance withRFG standards for VOC, NO X , and toxic emissions withoutunacceptable impacts on the price or supply of fuel?

3. How much lead time, if any, would be necessary to enable refiners to eliminate MTBEas an octane enhancer in conventional gasoline without unacceptable impacts on the price or supplyof fuel?

4. Whether EPA should obtain additional information on, or reduce, eliminate, or capthe use of any other gasoline additives in addition to MTBE?

5. Whether MTBE presents significantly greater risk to public health and/or water quality than alternative gasoline additives.

B. Releases of Gasoline Containing MTBE, Contamination of Water Resource by MTBE, and Remediation Technologies

1. As explained in this ANPRM, the Agency identified numerous andwidespread instances of MTBE contamination of groundwater. In order to ensurethat EPA has the most recent and accurate data available, EPA requestsinformation regarding incidents of both releases of gasoline containing MTBEand the detection of MTBE in groundwater, surface waters, or drinking watersupplies. Comments should include, to the extent possible, the amounts,locations, sources, and types of MTBE releases, and the levels and sources ofwater resource contamination from MTBE.

2. EPA is interested in additional information concerning the toxicity of MTBE, the levelsat which its taste or odor can be detected in water, the levels at which its taste or odormakes water unacceptable to consumers, and any other properties of MTBE that may berelevant to a rulemaking under TSCA section 6.

3. EPA's summary of current MTBE contamination problems suggests that there is significant risk of additional future contamination of water resources by MTBEfrom gasoline. In order to more comprehensively characterize this risk EPA isrequesting comment regarding the likely future occurrence of MTBEcontamination in groundwater, surface water, and/or drinking water.

4. EPA is requesting information regarding the relative contribution of different sources(such as USTs, spills, storm water runoff, air deposition, and marineengines) to present and future MTBE contamination of groundwater, surface water, and drinking water.

5. EPA is requesting information regarding the cost and efficacy of technologies forremediating soil and drinking water sources that have been contaminated with MTBE.EPA is particularly interested in examples of remediation efforts that have addressedMTBE contamination, and cost and efficacy comparisons with remediation efforts forother components of gasoline (such as BTEX).

C. Alternatives to MTBE

1. EPA is requesting information on potential substitutes, including those not identified inthis ANPRM, that might replace MTBE either as an oxygenate in RFG or an octaneenhancer in conventional gasoline. In addition to identifying a potential substitute, anyinformation addressing the following would be helpful:

a. The basis for the belief that the substitute might replace MTBE insignificant quantities.

b. The behavior of the substitute in soil and water, with an emphasis on thequantities of the substitute that might find their way into drinking watersources if the substitute is added to gasoline.

c. Toxicity, taste or odor properties, current exposure levels, or any otherproperties or considerations of the substitute that may be relevant to arulemaking under TSCA section 6.

2. EPA is interested in information based on actual releases of oxygenates and othergasoline additives other than MTBE to the environment; including degree ofcontamination, the spread of any contaminant plumes, and the cost and efficacy of thetechnologies available to remediate such contamination. Comments should include, tothe extent possible, the amounts, locations, sources and types of releases, and the levelsand sources of water resource contamination from these oxygenates and additives, aswell as from other gasoline constitutents.

3. EPA is interested in information regarding any possible impacts on health or theenvironment that might result from the elimination or limitation of use of MTBE as agasoline additive and the use of alternative compounds in MTBE's place, including notonly whether alternative additives may have a greater or lesser impact than MTBE ondrinking water sources, but also whether increased use of such alternatives might haveother beneficial or negative consequences on human health or the environment (such asair quality or water quality impacts).

D. Economic Considerations

1. EPA is requesting comment on the cost impacts of an elimination or limitation ofMTBE in gasoline, in the absence of a change in the RFG requirements. EPA isparticularly interested in comments that address:

a. The cost implications of an immediate elimination of MTBE from gasolinenationwide.

b. The cost implications of an immediate nationwide limit on MTBE contentin gasoline to pre-RFG levels or levels generally associated with the use ofMTBE for purposes of octane enhancement.

c. The cost implications of a phase out of MTBE from gasolinenationwide, resulting in complete elimination in a period of 3 to 4 years or5 to 6 years.

d. The cost implications of a nationwide phase down of MTBEcontent in gasoline, over 3 to 4 years, resulting in a limit on MTBEcontent equivalent to pre-RFG levels or levels generally associated withthe use of MTBE for purposes of octane enhancement.

2. EPA is requesting comment regarding any information that was not considered bythe Blue Ribbon Panel on the availability of alternative oxygenates and octane enhancers, thetime it would take for production of alternatives to meet national demand, and thepotential impacts on fuel supply and price.

VII. References

1. Moran, Michael J., Zogorski, John S., and Squillance, Paul J. USGS. MTBE in Ground Water of the United States-Occurrence, Potential Sources, and Long Range Transport. Published in Proceedings of the 1999 Water ResourcesConference. American Water Works Association.

2. USEPA, Office of Water. Drinking Water Advisory: Consumer Acceptability Advice and Health Effects Analysis on Methyl Tertiary-Butyl Ether (MTBE). December 1997.

3. Schirmer, Barker, J.F., Butler, B.J., Church, C.D., and Schirmer, K., 1998, Natural Attenuation of MTBE at the Bordon field site: in Wickramanayake, G.B., and Hinchee, R.E., Eds. Natural Attenuation: Chlorinated and Recalcitrant Compounds: The First International Conference on Remediation of Chlorinated and Recalcitrant Compounds. Monterey, California. May 18-21, Battelle Press. Columbus, OH. pp. 327-331.

4. Borden, R.C., Daniel, R.A., LeBrun, L.E. IV, and Davis, C.W. Intrinsic biodegradation of MTBE and BTEX in a gasoline-contaminated aquifer: Water Resources Research. Vol. 33. No. 5. pp. 1105-1115. 1997.

5. Alvarez, Pedro, et al. Health and Environmental Assessment of the Use of Ethanolas a Fuel Oxygenate. Potential Ground and Surface Water Impacts, The Effect ofEthanol on BTEX Biodegradation and Natural Attentuation. Vol. 4. pp. 3-12.December 1999.

6. U.S. Energy Information Administration. Petroleum Supply Annual 1998.Vol. 1. Table S4. p. 17. June 1999.

7. U.S. Energy Information Administration (T. Litterdale and A. Bohn).Demand and Price Outlook for Phase 2 Reformulated Gasoline, 2000. pp.7-8. April 1999.

8. Prah, J.D., et al. Sensory, Symptomatic, Inflammatory, and OcularResponses to and the Metabolism of Methyl Tertiary Butyl Ether in aControlled Human Exposure Experiment. Inhalation Toxicology .6:521-528.

9. API. Odor Threshold Studies Performed with Gasoline and Gasoline combinedwith MTBE, ETBE, and TAME. Washington DC. API #4592. 1993.

10. Oxygenated Fuels Association. Technical Memorandum: Taste and OdorProperties of Methyl Tertiary Butyl Ether and Implications for Setting a SecondaryMaximum Contaminant Level. Prepared by Malcolm Pirnie. 1998.

11. CENR. 1997 Interagency Assessment of Oxygenated Fuels. Committee on the Environment and Natural Resources (CENR), Office of Science and TechnologyPolicy (OSTP), National Science and Technology Center, (NSTC). June 1997.

12. USEPA, Office of Research and Development. 1994 Health Risk Perspectives onFuel Oxygenates. Report EPA/600R-94/217.

13. International Agency for Research on Cancer Monographs.Evaluation of MethylTertiary Butyl Ether. Vol. 73. p. 339. 1999

14. National Institute of Environmental Health Sciences, National ToxicologyProgram. Summary of RG1, RG2, and NTP Board SubcommitteeRecommendations for the Report on Carcinogens. Ninth Edition.1998.

15. Office of Science and Technology Policy, National Science andTechnology Council. Interagency Assessment of Oxygenated Fuels. June1997.

16. National Research Council (NRC). Toxicological and Performance Aspectsof Oxygenated Motor Vehicle Fuels. June 1996.

17. The Alliance for Proper Gasoline Handling. http://www.gas-care.org. NewAlliance Launches Consumer "Gas Care" Campaign to Prevent SmallGasoline Spills. Press Release dated, July 27, 1999.

18. Hunter, B., et al. Impact of Small Gasoline Spills on Groundwater, preliminary report abstract presented at the Maine Water Conference Meeting, April 1999, and NESCAUM, RFG/MTBE Findings and Recommendations. Boston, MA. August 1999.

19. NESCAUM, RFG/MTBE Findings and Recommendations. Boston, MA. p. 4.August 1999.

20. NESCAUM, RFG/MTBE Findings and Recommendations. Boston, MA. August1999.

21. Reuter, J. E., et al. Concentrations, Sources and Fate of the Gasoline OxygenateMethyl Ter-Butyl Ether (MTBE) in a Multiple-Use Lake. EnvironmentalScience and Technology . 32, 3666-3672. 1998.

22. Squillance, Paul, et al. A Preliminary Assessment of the Occurrence and PossibleSources of MTBE in Ground Water of the United States, 1993-1994. Environmental Science and Technology . Vol. 30. No. 5. pp. 1721-1730. 1996.

23. Zogorski, John, et al. MTBE Summary of Findings and Research by the U.S.Geological Survey. Proceedings of the 1998 Annual Conference of the AmericanWater Works Association.

24. Moran, Michael J., Zogorski, John S., and Squillance, Paul J. USGS. MTBE inGround Water of the United States-Occurrence, Potential Sources, and LongRange Transport. Published in Proceedings of the 1999 Water ResourcesConference. American Water Works Association.

25. Squillace, Paul, USGS. MTBE in the Nation's Ground Water, National Water-Quality Assessment (NAWQA) Program Results, Presentation Before the Blue Ribbon Panel on Oxygenates in Gasoline. April 29, 1999.

26. USGS/USEPA Joint Study. Preliminary Findings of the 12-State MTBE DrinkingWater Retrospective.

27. State of Maine Bureau of Health, Department of Human Services, Bureau ofWaste Management Remediation, Department of Environmental Protection,Maine Geological Survey, and the Department of Conservation. Maine MTBEDrinking Water Study, The Presence of MTBE and other Gasoline Compounds inMaine's Drinking Water-Preliminary Report. 1998.

28. Siddiqui, Mohamed, et al. Occurrence of Perchlorate and Methyl Tertiary ButylEther (MTBE) in Ground Water of the American Water System. AmericanWater Works Service Company Inc. September 30, 1998.

29. Buscheck, T. E., Gallagher, D. J., Kuehne, D. L., Zuspan, C. R. Occurrence andBehavior of MTBE in Groundwater. Presented at: Underground Storage TankConference: '98 Beyond. Los Angeles, CA. Sacramento, CA. State of CaliforniaWater Resources Control Board. April 1998.

30. Hitzig, Robert, et al. Study Reports LUST Programs Are Feeling Effects ofMTBE Releases. Soil and Ground Water Clean-Up . pp. 15-19.August-September 1998.

31. Robbins, G.A., Henebry, B.J., Schmitt, B.M., Bartolomeo, F.B., Green, A., andZack, P. Evidence for MTBE in Heating Oil. Groundwater Monitoring andRemediation . Vol. 19. No.2. pp.65-69. 1999.

32. U.S. Energy Information Administration. Petroleum Supply Annual 1998 . Vol. 1. Table S4. p. 17. June 1999.

33. The Report of the Blue Ribbon Panel on Oxygenates in Gasoline. Achieving CleanAir and Clean Water.

34. Delzer, G.C., Zogorski, J.S., Lopes, T.J., and Bosshart, R.L. Occurrence ofGasoline Oxygenate MTBE and BTEX Compounds in Urban Stormwater in theUnited States, 1991-1995. USGS Water-Resources Investigations Report.96-4145. 1996.

35. Office of Science and Technology Policy, National Science and TechnologyCouncil. Interagency Assessment of Oxygenated Fuels. June 1997.

36. Huggins, Jack. Submitted written comments on behalf of the Renewable FuelsAssociation at the April 1999 Meeting of the Blue Ribbon Panel on Oxygenates inGasoline.

37. Letter from Agriculture Secretary Dan Glickman to Senator Tom Harkin, dated November 15, 1999. Attached Analysis entitled "Economic Analysis of Replacing MTBE with Ethanol in the United States."

38. USDA. Economic Analysis of Replacing MTBE with Ethanol in the United States.November 1999.

39. DOE. Estimating the Refining Impacts of Revised Oxygenate Requirements forGasoline: Follow-up Findings. May 1999.

40. California Energy Commission. Supply and Cost Alternatives to MTBE inGasoline. October 1998.

41. MathPro. Potential Economic Benefits of the Feinstein-Bilbray Bill. March 18, 1999.

42. Moran, Michael J., Zogorski, John S., and Squillance, Paul J. USGS.MTBE in Ground Water of the United States Occurrence, Potential Sources, and Long Range Transport, Published in Proceedings of the 1999 Water Resources Conference. American Water Works Association.

43. Blue Ribbon Panel. Achieving Clean Air and Clean Water. The Report of the Blue Ribbon Panel on Oxygenates in Gasoline. p. 85. September 1999.

44. Office of Science and Technology Policy, National Science and Technology Council. Interagency Assessment of Oxygenated Fuels. June 1997.

45. California Energy Commission. Supply and Cost Alternatives to MTBE inGasoline. October 1998.

46. Estimate provided by industry representative via personal communication Sheldon Thompson, Senior Vice President and Chief Administrative Officer, Sunoco, Inc. via telephone communication and inquiry. February 2000.

47. NESCAUM, RFG/MTBE Findings and Recommendations. Boston, MA. August1999.

48. NESCAUM, RFG/MTBE Findings and Recommendations. Boston, MA. August1999.

VIII. Regulatory Assessment Requirements

A. Executive Order 12866

Under Executive Order 12866 (58 FR 51735, October 4, 1993), the EPA mustdetermine whether a regulatory action is "significant" and therefore subject to Office ofManagement and Budget (OMB) review and the requirements of the Executive Order. The Executive Orderdefines "significant regulatory action" as one that is likely to result in a rule that may:

1. Have an annual effect on the economy of $100 million or more, or adverselyaffects in a material way the economy, a sector of the economy, productivity, competition, jobs,the environment, public health or safety, or State, local, or tribal governments or communities;

2. Creates a serious inconsistency or otherwise interferes with an action taken orplanned by another agency;

3. Materially alters the budgetary impact of entitlements, grants, user fees, or loanprograms or the rights and obligations of recipients thereof; or

4. Raises novel legal or policy issues arising out of legal mandates, the President'spriorities, or the principles set forth in the Executive Order.

A draft of this ANPRM was reviewed by OMB prior to publication, as required byE.O. 12866. Any changes made in response to OMB suggestions or recommendations will bedocumented in the public record.

B. Federalism

Executive Order 13132, entitled " Federalism " (64 FR 43255, August 10, 1999),requires EPA to develop an accountable process to ensure "meaningful and timely input by Stateand local officials in the development of regulatory policies that have federalism implications.""Policies that have federalism implications" is defined in the Executive Order to includeregulations that have "substantial direct effects on the States, on the relationship between thenational government and the States, or on the distribution of power and responsibilities among thevarious levels of government." Under Executive Order 13132, EPA may not issue a regulationthat has federalism implications, that imposes substantial direct compliance costs, and that is notrequired by statute, unless the Federal government provides the funds necessary to pay the directcompliance costs incurred by State and local governments, or EPA consults with State and localofficials early in the process of developing the proposed regulation. The EPA also may not issuea regulation that has federalism implications and that preempts State law unless the EPA consultswith State and local officials early in the process of developing the proposed regulation.

If EPA complies by consulting, Executive Order 13132 requires EPA to provide toOMB, in a separately identified unit of the preamble to the rule, a federalism summary impactstatement. The federalism summary impact statement must include a description of the extent ofEPA's prior consultation with State and local officials, a summary of the nature of their concernsand the EPA's position supporting the need to issue the regulation, and a statement of the extentto which the concerns of State and local officials have been met. Also, when EPA transmits adraft final rule with federalism implications to OMB for review pursuant to Executive Order12866, EPA must include a certification from the agency's Federalism Official stating that EPAhas met the requirements of Executive Order 13132 in a meaningful and timely manner.

EPA has determined that the requirements of Executive Order 13132 do not apply to this ANPRM, and therefore the Executive Order does not apply to thisANPRM.

C. Small Business Concerns

Section 603 of the Regulatory Flexibility Act (RFA), 5 U.S.C. 601 et seq ., as amended bythe Small Business Regulatory Enforcement Fairness Act (SBREFA) of 1996, Public Law 104-121,requires the Administrator to assess the economic impact of proposed rules on small entities,including small businesses. The Agency accordingly requests comment on the potential economicimpact on small business of the limitation or elimination of MTBE as an oxygenate or octaneenhancer in gasoline. EPA does not anticipate, at this point, that the potential action discussed inthis ANPRM will have a significant economic impact on small business. Comments on the potentialeconomic impact of such an action on small businesses will help the Agency meet its obligationsunder the RFA, as amended by SBREFA, and will provide information to assist the Agency in itsefforts to minimize any significant economic impact of such an action for potentially affected smallbusinesses.

D. Children's Health Protection

Executive Order 13045, entitled " Protection of Children from Environmental Health Risks and Safety Risks " (62 FR 19885, April 23, 1997) applies to any rule that:

1. Is determined to be "economically significant" as defined under E.O. 12866.

2. Concerns an environmental health or safety risk that EPA has reason to believe may have a disproportionate effect on children.

If the regulatory action meets both criteria, the Agency must evaluate the environmental health or safety effects of the planned rule on children, and explain why the planned regulation is preferable to other potentially effective and reasonably feasible alternatives considered by the Agency.

While E.O. 13045 does not require EPA to evaluate the health or safety risks of actions discussed in an ANPRM, the Agency is, nonetheless,soliciting comment on such risks. The potential action discussed in this ANPRM might involve issues related to health or safety risks. To the extent that this is the case, the potential action would be intended to minimize or eliminate any such risks for all people who utilize groundwater resources, including children. We request comment on whether there are health or safety considerations related to the potential action discussed in this ANPRM that may disproportionately affect children.

List of Subjects in 40 CFR Part 755

Environmental protection, Air pollution, Fuel additives, Hazardous substances, Water resources.

Dated: March 20, 2000.

Carol M. Browner,


[FR Doc. 00-7323 Filed 3-21-00; 2:11 pm]