# Fuels and Fuel Additives; Waiver Decision/Circuit Court Remand > Briefs, arguments, decisions, and more. URL: https://www.frixlaw.com/law-library/documents/fr%3A94-18941 ## Record - **Collection:** Federal Register - **Document type:** Uncategorized Document - **Published:** August 17, 1994 ## Text ENVIRONMENTAL PROTECTION AGENCY [FRL-5027-1] Fuels and Fuel Additives; Waiver Decision/Circuit Court Remand AGENCY: Environmental Protection Agency (EPA). ACTION: Notice ----------------------------------------------------------------------- SUMMARY: On July 12, 1991, under section 211(f)(4) of the Clean Air Act (Act), the Ethyl Corporation (Ethyl) requested a waiver to permit the sale of its gasoline additive, methylcyclopentadienyl manganese tricarbonyl (MMT), an octane enhancer commercially labeled by Ethyl as HiTEC 3000, for use in unleaded gasoline. The Administrator of EPA denied Ethyl's application for a waiver on January 8, 1992, based primarily on concerns regarding the potential for increases in hydrocarbon emissions resulting from MMT use. Ethyl subsequently sought judicial review of that decision in the U.S. Court of Appeals for the District of Columbia Circuit. Based on new emissions data developed and submitted to EPA by Ethyl, EPA requested that the Court of Appeals remand Ethyl's application to the Agency for further action. On November 30, 1993, the Administrator of EPA found that Ethyl had met its burden to demonstrate under section 211(f)(4) that approval of its remanded application would not cause or contribute to a failure to meet emission standards. Ethyl agreed to resubmit its application at that time, thereby affording further time for the Agency to consider the issue of potential health effects associated with use of MMT in unleaded gasoline. Ethyl and EPA later agreed to further extend the deadline for final action on Ethyl's application to July 13, 1994. The Agency is today denying Ethyl's request for a waiver for HiTEC 3000 based on unresolved concerns regarding the potential impact of manganese emissions resulting from MMT use on public health. ADDRESSES: Copies of the information relative to this application are available for inspection in public docket A-93-26, A-91-46 and A-90-16 at the Air Docket (LE-131) of the EPA, Room M-1500, 401 M Street, S.W., Washington, D.C. 20460, (202) 260-7548, between the hours of 8:30 a.m. to noon and 1:30 p.m. to 3:30 p.m. weekdays. As provided in 40 CFR Part 2, a reasonable fee may be charged for copying services. FOR FURTHER INFORMATION CONTACT: Joseph R. Sopata, Chemist, or James W. Caldwell, Chief, Fuels Section, Field Operations Support Division (6406J), U.S. Environmental Protection Agency, 401 M Street, S.W., Washington, D.C. 20460, (202) 260-2635. SUPPLEMENTARY INFORMATION: Index I. Background II. Statutory Framework A. History of Statute B. Two Stage Process C. Consideration of Potential Health Effects III. Method of Review A. ``Causes or Contributes'' to Emission Standard Failure B. Discretionary Review IV. Analysis of Emissions Data A. Description of Previous Test Programs B. Comments on Vehicle Emissions Issues C. Available Data Meet Previously Utilized Criteria D. Data on Newer-Technology Vehicles Meet More Stringent Criteria E. Finding V. The Onboard Diagnostics Issue VI. Manganese Health Assessment A. Introduction B. Health Effects Assessment 1. Background 2. Earlier Assessments 3. 1993 Revised RfC 4. Alternative Approaches to Deriving RfCs a. Conventional NOAEL- or LOAEL-Based Approach b. NOSTASOT Approach c. Benchmark Analyses d. Bayesian Analyses e. Summary of RfC Estimates C. Exposure Assessment 1. Background 2. Additional Canadian Studies 3. The PTEAM Study 4. Estimated Mn Exposure Levels Associated with MMT D. Risk Characterization E. References F. Comments on Health Assessment and EPA Response VII. Fuel and Fuel Additive Registration and Research Needs VIII. Other Issues IX. Decision I. Background Section 211(f)(1)(A) of the Act makes it unlawful, effective March 31, 1977, for any manufacturer of a fuel or fuel additive to first introduce into commerce, or to increase the concentration in use of, any fuel or fuel additive for use in light-duty motor vehicles manufactured after model year 1974 which is not substantially similar to any fuel or fuel additive utilized in the certification of any model year 1975, or subsequent model year, vehicle or engine under section 206 of the Act. An interpretive rule defining the term ``substantially similar'' under section 211(f)(1)(A) was promulgated for unleaded gasoline at 46 FR 38582 (July 28, 1981), and revised at 56 FR 5352 (February 11, 1991). Section 211(f)(1)(B) of the Act makes it unlawful, effective November 15, 1990, for any manufacturer of a fuel or fuel additive to first introduce into commerce, or to increase the concentration in use of, any fuel or fuel additive for use by any person in motor vehicles manufactured after model-year 1974 which is not substantially similar to any fuel or fuel additive utilized in the certification of any model year 1975, or subsequent model year, vehicle or engine under section 206 of the Act. Thus, section 211(f)(1)(B) expands the prohibitions of 211(f)(1)(A), which apply only to light- duty vehicles. Section 211(f)(4) of the Act provides that upon application by any fuel or fuel additive manufacturer, the Administrator of EPA may waive the prohibitions of section 211(f)(1) if the Administrator determines that the applicant has established that such fuel or fuel additive will not cause or contribute to a failure of any emission control device or system (over the useful life of any vehicle in which such device or system is used) to achieve compliance by the vehicle with the emissions standards to which it has been certified pursuant to section 206 of the Act. If the Administrator does not act to grant or deny a waiver within 180 days of receipt of the application, the statute provides that the waiver shall be treated as granted. The subject of this notice is an application by Ethyl under section 211(f)(4) of the Act for a waiver for the fuel additive methylcyclopentadienyl manganese tricarbonyl (MMT), commercially labeled by Ethyl as HiTEC 3000, to be blended in unleaded gasoline resulting in a level of 0.03125 (1/32) gram per gallon manganese (gpg Mn). This Agency action is a reconsideration of Ethyl's fourth application for a waiver for MMT. Ethyl's first application was submitted on March 17, 1978 for concentrations of MMT resulting in 1/16 and 1/32 gpg Mn in unleaded gasoline. Ethyl's second application was submitted on May 26, 1981 for concentrations of MMT resulting in 1/64 gpg Mn in unleaded gasoline. The Administrator denied these requests for waivers due to concerns regarding increases in exhaust hydrocarbon emissions resulting from MMT use. The decisions and justifications thereof may be found in the September 18, 1978 Federal Register, 43 FR 41424, and the December 1, 1981 Federal Register, 46 FR 58630. Ethyl's third application was submitted on May 9, 1990, for concentrations of MMT resulting in a level of 0.3125 (1/32) gpg Mn in unleaded gasoline (the same levels which are requested in the application which is the subject of today's notice). Ethyl withdrew its third application on November 1, 1990, before the deadline for the Administrator to make a determination on the application. Because no determination had been made at the time Ethyl withdrew that application, EPA accepted the withdrawal and immediately terminated the proceeding without action on the application. Ethyl's fourth application was submitted on July 12, 1991. This application was, from a practical standpoint, an extension of the third application, the entire record of which was incorporated by Ethyl into the current proceeding. On January 8, 1992, the Administrator of EPA denied Ethyl's fourth application for a waiver (57 FR 2535, January 22, 1992). The application was denied based in part upon data submitted by Ford Motor Company (Ford) which indicated that, for the model groups tested by Ford and, for the conditions under which Ford tested its vehicles, the increases in hydrocarbon exhaust emissions as a result of the use of MMT were substantially greater than those observed in the Ethyl test program. The Agency stated in its decision that a likely factor which might account for the differences observed between the Ethyl and Ford test programs was the severity of the driving cycle. However, the Agency also concluded that other factors might be responsible for the observed differences. In the denial decision, the Agency stated that it had always accepted data from test programs which ``model'' the fleet in support of waiver applications, but that if an interested party were to present data indicating that a potentially significant subset of the fleet, not tested by the applicant, was especially susceptible to the negative effects of the additive, the Agency could reasonably require specific testing on representative models of that sub-fleet. In its decision, the Agency also stated that it believes it is reasonable to consider the effect of a fuel on vehicles' ability to meet future emissions standards. (The ``Tier I'' tailpipe standards prescribed by section 202(g) of the Act began to take effect in model year 1994, which began approximately in September 1993.\1\) Therefore, regarding the Ford data mentioned above, the Agency stated in its decision that the concerns raised by that data related to both current and future standards. --------------------------------------------------------------------------- \1\56 FR 25724-25790 (June 5, 1991). --------------------------------------------------------------------------- Although not the basis of the 1992 denial, another important issue arose during the consideration of Ethyl's third and fourth applications. The Agency, as well as several commentors, expressed concerns regarding the possible adverse health effects of an increase in airborne manganese resulting from MMT use. These concerns were centered around: (1) The known severe neurotoxic effects of high-level exposure to manganese through inhalation, (2) the lack of data regarding the chronic effects of low-level inhalation exposure to manganese in humans, and (3) the lack of knowledge regarding potential exposures due to MMT use. It was repeatedly pointed out by commenters that neurotoxic damage could occur prior to the onset of overt symptoms. In those proceedings, Ethyl also submitted comments regarding manganese emissions. Ethyl indicated that the manganese emissions resulting from the use of MMT in unleaded gasoline would be so small as to not materially affect human exposure to airborne manganese. In support of its view, Ethyl submitted analyses and data on exposure modeling and monitoring in both its 1990 and 1991 applications (and in subsequent submissions associated with the remand discussed below). (The issue of manganese emissions and public health is discussed in more detail in Section VI of this document.) During EPA's consideration of the 1990 Ethyl submission, EPA's Office of Research and Development (ORD) conducted a manganese inhalation risk assessment based on the available data which found that because of ``the considerable uncertainties and data gaps in the available information * * * it is not possible * * * to conclude definitively that the increased use of MMT as a fuel additive will (or will not) increase public health risk.''\2\ (EPA also investigated potential hazards associated with water contamination resulting from accidental spills or leakages of pure MMT and concluded that spills or leaks, if they occurred, are likely to be contained and therefore would not pose a human health risk due to groundwater contamination. However, data available to EPA are insufficient to determine whether spills and leaks could affect exposure to benthic organisms.) --------------------------------------------------------------------------- \2\See ``Comments on the Use of Methylcyclopentadienyl Manganese Tricarbonyl in Unleaded Gasoline'', Docket A-90-16. --------------------------------------------------------------------------- Additionally, in order to obtain assistance in describing information needed to improve its manganese health risk assessment (and also to improve its environmental hazard identification of issues associated with MMT itself), EPA, in conjunction with the National Institute of Environmental Health Sciences, conducted a Manganese/MMT Symposium and Workshop on March 12-15, 1991. The conference allowed the Agency to solicit scientific information from invited extramural scientists reflecting a wide range of scientific disciplines. Invited participants included representatives of Ethyl Corporation, the Environmental Defense Fund, the Centers for Disease Control, the U.S. Food and Drug Administration and Environment Canada. A summary of the workshop discussions was provided to each participant and the information obtained from this meeting was also used by EPA to prepare a report on prioritized research needed for improving its manganese inhalation risk assessment.\3\ --------------------------------------------------------------------------- \3\Preuss, P.W. (1991) ORD Document on Information Needed to Improve the Risk Characterization of Manganese Tetraoxide (Mn3O4) and Methylcyclopentadienyl Manganese Tricarbonyl, December 12, 1991 (memorandum to Richard Wilson). Washington, DC: U.S. Environmental Protection Agency, Office of Research and Development; December 16, 1991. For further information the reader is referred to Air Docket A-93-26, II-A-16. --------------------------------------------------------------------------- EPA raised the issue of potential health effects associated with manganese exposure as a concern in its January 1992 denial, but did not base its decision on this concern because the Agency concluded that the uncertainties regarding hydrocarbon emissions increases prevented EPA from making the requisite ``cause or contribute'' determination concerning effects on regulated emissions. On February 13, 1992, Ethyl filed a petition for review of the January 8, 1992 waiver denial decision in the United States Court of Appeals for the District of Columbia Circuit. EPA and Ethyl subsequently entered discussions concerning a possible settlement of the court case. In the context of those discussions, Ethyl submitted to the Agency new emissions test data developed by Ethyl since the denial decision. Based on its inspection and analysis of the new Ethyl data, EPA tentatively concluded that the data indicated that driving cycle did not contribute significantly to MMT-induced increases in HC emissions. (EPA's preliminary analysis was placed in docket A-92-41.) However, in addition to addressing the issue of driving cycle, the Ethyl data appeared to confirm the finding by Ford that 1991 Escorts experienced a much higher MMT-induced HC increase than that observed in other models tested (either in Ethyl's new program or in the original Ethyl test program). The Agency remained concerned that these data might indicate that certain engine and emissions control system configurations are more vulnerable to a MMT-induced emissions increase irrespective of driving cycle. To facilitate further settlement discussions with Ethyl, EPA decided to attempt to formulate an emission testing program intended to address in a timely manner specific unresolved issues concerning the effect of MMT on emissions: (1) whether other vehicles utilizing fuels containing MMT are likely to experience increases in hydrocarbon emissions similar to those observed in 1991 Ford Escorts; and (2) whether fuels containing MMT have significant adverse effects on emissions from vehicles utilizing the technologies most likely to be employed to meet future standards. On October 28, 1992, EPA held a public workshop to assist the Agency in its attempt to formulate such an emission testing program (57 FR 44740, September 29, 1992). In particular, EPA hoped to obtain information and assistance from technical experts outside of the Agency concerning the test program and, in view of the significance of any future waiver decision concerning MMT for the auto industry and the general public, EPA was interested in obtaining comments concerning a decisional framework designed to address and resolve these issues. A proposed emission test program developed by the Agency and presented at the public workshop, was effectively adopted by Ethyl as its most recent vehicle emissions test program involving the 1993 model fleet. Although further settlement discussions between Ethyl and EPA were held subsequent to the public workshop, the parties were not successful in reaching a settlement. However, despite the failure of the parties to reach agreement, EPA concluded that the Administrator's denial decision should be reconsidered in light of the new emissions data generated by Ethyl subsequent to the decision. Accordingly, EPA requested that the United States Court of Appeals for the District of Columbia remand the denial decision to EPA for reconsideration. On April 6, 1993, the Court of Appeals issued a decision granting the Agency's motion and remanding the case to the Agency to redetermine within 180 days whether to grant or deny Ethyl's application. The mandate implementing this judgement was transmitted to the Agency on June 3, 1993. Pursuant to the court's remand decision, the Agency published a notice indicating the commencement of a comment period (58 FR 35950, July 2, 1993). The Administrator's final decision on remand was due within 180 days after the transmittal of the court's mandate, or by November 30, 1993. After the Court of Appeals granted the Agency's motion to remand the denial decision concerning Ethyl's July 12, 1991 application, Ethyl submitted to EPA a substantial amount of additional data on emission testing with fuels containing MMT. (Specific aspects of these data are discussed below in Section IV of this document). During the course of the remand of Ethyl's waiver application, the EPA Office of Research and Development (ORD) reviewed the available data concerning the health effects associated with inhalation of manganese as part of a process to revise the reference concentration (RfC) for inhaled manganese.\4\ An inhalation reference concentration is defined as an estimate (with uncertainty spanning perhaps an order of magnitude) of a continuous inhalation exposure to the human population (including sensitive subgroups) that is likely to be without appreciable risk of deleterious non-cancer health effects during a lifetime. The methodology for establishing an RfC accounts for uncertainties and gaps in the health data base through the assignment of uncertainty factors. In November, 1993, ORD completed preparation and review of, and EPA released to Ethyl, a document identifying and describing the rationale for a new inhalation RfC of 0.05 ug/m\3\ for manganese and manganese compounds. --------------------------------------------------------------------------- \4\In 1990, an inhalation reference concentration (RfC) for manganese of 0.4 ug/m\3\ was verified and placed on IRIS. The original RfC for manganese figured into a 1990 risk assessment of MMT prepared by the EPA Office of Research and Development (ORD). Subsequently, in light of new information submitted by Ethyl and new results from more recently published studies concerning manganese inhalation health effects in workers, EPA reexamined the RfC for manganese and revised it to a value of 0.05 ug/m\3\ in 1993. This revised RfC for manganese was made available to Ethyl and placed on IRIS in November 1993. --------------------------------------------------------------------------- Ethyl subsequently provided to EPA a detailed critique of the approach utilized to derive the revised manganese RfC. Among other things, Ethyl argued that EPA used an inappropriate procedure to derive the RfC from a study of occupational manganese exposures by Roels, et al. (1992). Ethyl also argued that use of MMT would not result in significant changes in background manganese exposures, and that the favorable effects on public health resulting from changes in the composition of gasoline when MMT is utilized would outweigh any potential for adverse health effects. (Copies of documents describing the revised RfC and of the Ethyl comments are available in the public docket.) As the deadline of November 30, 1993, for final action by EPA on Ethyl's waiver application approached, EPA concluded that the extensive data base on the emission effects of MMT assembled by Ethyl and others during the consideration of the application was sufficient to permit a decision concerning whether Ethyl had satisfied the statutory requirement to show that use of MMT will not cause or contribute to exceedence of emission standards. However, there had been insufficient opportunity for public comment concerning the use of a revised manganese inhalation RfC in assessing any risks that might be posed by granting Ethyl's application. Ethyl argued that it had not been afforded an adequate opportunity to study the derivation of the RfC and to comment on its implications for Ethyl's application. While EPA scientists did not necessarily agree with the specific technical arguments concerning the revised RfC and other issues pertaining to health effects made by Ethyl, EPA concluded that it might be useful to review the revised RfC in light of further analyses of the available data as well as the underlying data from occupational studies of inhaled manganese if such data could be readily obtained. EPA also concluded that it would be desirable in any case to have further dialogue with Ethyl and other interested parties on issues related to the health effects of manganese before EPA was to make a final decision concerning Ethyl's waiver application. As a result of these factors, Ethyl and EPA entered into discussions concerning a possible extension of the deadline for a decision. Ultimately, an agreement between Ethyl and EPA concerning such an extension was implemented on November 30, 1993, and notice of the agreement was published in the Federal Register on December 9, 1993 (58 FR 64761). The agreement provided for an extension of 180 days in the deadline for final action by EPA on Ethyl's waiver application for HiTEC 3000.\5\ EPA was thus required to take final action either granting or denying Ethyl's resubmitted application by May 29, 1994. For purposes of the resubmitted application, the EPA Administrator determined that Ethyl had demonstrated, as required by section 211(f)(4), that use of HiTEC 3000 at the specified concentration will not cause or contribute to a failure of any emission control device or system (over the useful life of any vehicle in which such device or system is used) to achieve compliance by the vehicle with the emission standards with respect to which it has been certified.\6\ The Agency stated clearly in the December 9, 1993 Federal Register notice that this determination would not preclude any subsequent regulatory action based on emission effects under Clean Air Act section 211(c) or any other provision of the Clean Air Act in the event that the resubmitted Ethyl waiver application were to be granted in the future. The Agency also made it clear that this determination would not apply in the context of any other new waiver application concerning HiTEC 3000 or MMT which might be submitted in the future if EPA were to deny Ethyl's resubmitted waiver application on other grounds. Further review of Ethyl's application during this 180 day period focused in particular on the issues relating to the potential health effects on public health if EPA were to permit use of MMT as a fuel additive. --------------------------------------------------------------------------- \5\To implement this agreement, Ethyl withdrew its July 12, 1991 waiver application, as remanded by the Court of Appeals, and immediately resubmitted the application. \6\As is explained in section IV of this document, this decision was based primarily upon application of the previously used statistical tests to the submitted emissions data. As is also explained in section IV, the Agency believes that these tests may be outdated and is considering a formal change in its method of analysis of such data. --------------------------------------------------------------------------- Ethyl and EPA both desired and intended to assure continuity between the proceedings concerning the July 12, 1991 waiver application, as remanded to EPA by the Court of Appeals, and Ethyl's resubmitted waiver application. The entire administrative record compiled by EPA in support of the original denial decision, as well as all submissions to the public docket concerning the remanded application, was incorporated in the record this final decision on the resubmitted application. The docket number for the resubmitted waiver application also remained the same. The additional 180 days that were provided by Ethyl's agreement to resubmit the waiver application were utilized by EPA to evaluate remaining issues that may have been relevant to today's decision. In particular, EPA continued to examine the effects on public health that might be associated with approval of Ethyl's application. EPA considered any additional underlying data concerning studies of occupational manganese exposure that were obtained by or submitted to EPA, as well as any additional data or information pertaining to the health effects of manganese submitted by Ethyl or other interested persons during the comment period. Any additional information that was submitted was also considered in exploring alternative candidate RfC estimates and their relationship to the verified revised RfC. EPA also used the additional time provided by the extension to make a decision on how the RfC should be utilized in assessing health effects that may be associated with MMT use, evaluate potential exposure to manganese compounds associated with MMT use, complete a risk assessment concerning Ethyl's application, and decide what additional data, if any, should be provided by Ethyl either before or after MMT is introduced into the market. On April 28, 1994, EPA provided Ethyl Corporation with a draft of the revised risk assessment, which updated the 1991 ORD assessment and incorporated further analyses performed during the 180-day extension period. Subsequent to providing Ethyl with this draft, Ethyl provided EPA with comments on the draft and some additional new data on ambient manganese concentrations in several Canadian cities. In order to allow the Agency time to consider this new data, Ethyl requested, and the Agency agreed to, an extension of the decision deadline until July 13, 1994. An agreement implementing this extension was executed by EPA and Ethyl counsel on May 24, 1994. II. Statutory Framework A. History of Statute Congress first added section 211(f) to the Clean Air Act in 1977 based primarily on concerns that fuels or additives might damage vehicle emission control devices. Thus, the original statute focused on vehicles designed to use unleaded gasoline, prohibiting the general use in fuels of materials not ``substantially similar'' to fuels used to certify vehicles to emissions standards. Section 211(f) also provided that the Administrator of EPA ``may waive the prohibitions * * * if he determines that the applicant has established that such fuel or fuel additive * * * will not cause or contribute to a failure of any emission control device or system * * * to achieve compliance by the vehicle with the emission standards with respect to which it has been certified pursuant to section 206.''\7\ Additionally, the statute provides that if the Administrator does not act to grant or deny the waiver request within 180 days of receipt of the application, the waiver request shall be treated as granted. --------------------------------------------------------------------------- \7\Section 206 of the Act sets forth the certification requirements with which vehicle manufacturers must comply in order to introduce into commerce new model year motor vehicles. Under Sec. 202 of the Act, standards for hydrocarbon (HC), carbon monoxide (CO), and oxides of nitrogen (NOx) emissions for gasoline, gaseous fuel, diesel and methanol-powered motor vehicles have been established. For gasoline, gaseous fuel and diesel-powered motor vehicles, standards have also been established for particulate emissions. --------------------------------------------------------------------------- Section 211(f) was initially interpreted by the Agency as applying only to unleaded gasoline. In the 1990 Amendments, section 211(f)(1) was broadly expanded to cover all other fuels and fuel additives, including leaded gasoline, diesel fuel, and consumer additives.\8\ The 1990 Amendments also apply the provisions of this subsection to vehicles other than lightduty vehicles. Section 211(f)(1)(B) of the Act makes it unlawful, effective November 15, 1990, for any manufacturer of a fuel or fuel additive to first introduce into commerce, or to increase the concentration in use of, any fuel or fuel additive for use by any person in motor vehicles manufactured after model year 1974 which is not substantially similar to any fuel or fuel additive utilized in the certification of any model year 1975, or subsequent model year, vehicle or engine under section 206 of the Act. Thus, section 211(f)(1)(B) expands to all motor vehicles the fuel prohibitions of the original section 211(f)(1) (now redesignated as section 211(f)(1)(A)), which apply only to light-duty vehicles.\9\ --------------------------------------------------------------------------- \8\H.R. Rep. No. 490, Part 1, 101st Cong., 2d Sess. 313 (1990). \9\An interpretive rule defining the term ``substantially similar'' under section 211(f)(1)(A) was promulgated for unleaded gasoline at 46 FR 38582 (July 28, 1981), and revised at 56 FR 5352 (February 11, 1991). An advance notice of proposed rulemaking (ANPRM) has been published to begin the proces of promulgating an interpretive rule to define the term ``substantially similar'' under Sec. 211(f)(1)(B) for diesel fuel and diesel fuel additives. See 56 FR 24362 (May 30, 1991). --------------------------------------------------------------------------- In adding section 211, the first focus of Congress was to prevent the introduction of new additives which may prove harmful to emission control devices but to allow for the introduction of such additives if it could be demonstrated that they would not harm emission control devices. Furthermore, in framing the statute such that the Administrator was not required to grant a waiver, Congress provided authority to the Administrator to take into account other considerations associated with introduction of the new material into commerce. B. Two Stage Process Section 211(f)(4) of the Act provides the legal authority for this waiver decision.\10\ The Agency interprets section 211(f)(4) of the Act as establishing a two stage process for the decision to grant or deny a waiver application. The first stage of the process focuses solely on whether a waiver applicant has met its burden to demonstrate that a fuel does not cause or contribute to a failure to meet emission standards. The second stage of the process reflects the discretionary authority provided to the Agency by the statute. --------------------------------------------------------------------------- \10\Section 211(f)(4) states that ``The Administrator, upon application of any manufacturer of any fuel or fuel additive, may waive the prohibitions established under paragraph (1) or (3) of this subsection, or the limitation specified in paragraph (2) of this subsection, if he determines that the applicant has established that such fuel or fuel additive or a specified concentration thereof, and the emission products of such fuel or additive or specified concentration thereof, will not cause or contribute to a failure of any emission control device or system (over the useful life of any vehicle in which such device or system is used) to achieve compliance by the vehicle with the emission standards with respect to which it has been certified pursuant to section 206. If the Administrator has not acted to grant or deny an application under this paragraph within one hundred and eighty days of receipt of such application, the waiver authorized by this paragraph shall be treated as granted.'' --------------------------------------------------------------------------- In the first stage of the waiver process, the sole issue is whether a fuel ``causes or contributes'' to an emission standard failure. The waiver applicant bears the burden of demonstrating that a fuel will neither cause nor contribute to an emission standard failure for any regulated pollutant. Balancing of the emission effects of a fuel for one pollutant against those for other pollutant(s) is not permissible under the statutory language. For example, an applicant would not meet its burden of proof if its testing of a fuel shows that it causes or contributes to an emission standard failure for CO, even though testing shows decreases in emissions of HC and NOx. If an applicant does not meet its burden of demonstrating that the ``cause or contribute'' test is met, the Agency cannot grant a waiver. If an applicant does meet its burden, the Agency may then exercise its discretion to grant or to deny a waiver in the second stage of the process.\11\ --------------------------------------------------------------------------- \11\Under the statute, if the Agency does not take action to grant or deny a waiver application within 180 days of submittal, the waiver is deemed granted. --------------------------------------------------------------------------- The statute provides that the Agency ``may'' grant a waiver application if the ``cause or contribute'' test is met, but does not require such an action. The Agency may therefore choose not to grant a waiver based on other issues (e.g., public health effects) that indicate that it would not be in the public interest to do so. In this second stage of the process, the Agency has a great deal of discretion to determine which issues should be examined and to balance the potential positive and negative impacts of a waiver. Such discretionary authority is grounded not only in Congress' use of the term ``may'' rather than the term ``shall'' in section 211(f)(4), but also in the goals and purposes of section 211 when read as a whole. The Agency does not believe that Congress intended to require EPA to grant a waiver under section 211(f)(4) when available information indicates that the fuel would be potentially subject to regulatory control under section 211(c)(1) immediately upon issuance of the waiver. Similarly, EPA believes that Congress did not intend to preclude a determination of whether issuance of a waiver is consistent with other important goals of the Act once it has been demonstrated that the mandatory ``cause or contribute'' test has been met. This does not mean that the Administrator has unfettered discretion to deny a waiver application for any reason. The grounds for any denial must not be arbitrary or capricious or constitute an abuse of discretion. Thus, in using discretion to deny an application, the Administrator must identify and explain the factors on which a discretionary denial decision is based and must assure that the policy adopted is consistent for all similarly situated waiver applicants. C. Consideration of Potential Health Effects Although the basis for a discretionary denial must be rational and non-arbitrary, nothing in the statute limits the type of factors which the Administrator may consider in deciding whether to deny an application. Section 101(b)(1) states that one of the purposes of the Act is to ``protect and enhance the quality of the Nation's air resources so as to promote the public health and welfare and the productive capacity of its population.'' Given this general goal of the Act, certainly the potential effects on public health of vehicle emissions would be a factor which the Administrator may reasonably consider when utilizing the discretion which section 211(f)(4) authorizes. Furthermore, under sections 211(b)(2) and 211(e), the Administrator must require the manufacturer of a fuel or additive to produce data concerning potential health effects as a condition of, or a prerequisite to, registration of the fuel or additive.\12\ Under section 211(c)(1), the Administrator may, based on data collected under sections 211(b) and 211(e) or otherwise available, issue regulations controlling manufacture or sale of any fuel or fuel additive which the Administrator finds ``may reasonably be anticipated to endanger the public health or welfare.'' These provisions indicate that Congress intended that the Administrator be concerned about the potential health effects of fuels and fuel additives. --------------------------------------------------------------------------- \12\Sections 211(a) and 211(b)(1) require the registration of fuels and additives designated by the Administrator as a precondition to introduction into commerce. --------------------------------------------------------------------------- The fact that the Administrator may control fuels or fuel additives which pose potential health effects under section 211(c)(1) does not mean that the Administrator may not consider health effects as a factor in deciding whether to grant a waiver under section 211(f)(4). Such a construction of the statute would lead to absurd results, precluding the Administrator from denying a waiver application and leading to potential introduction of a fuel or additive into commerce, even in the specific circumstances where the Administrator has concluded that there are grounds for issuance of a proposed regulation prohibiting the fuel or additive under section 211(c). However, although this reasoning indicates that Congress could not have reasonably intended to completely preclude the consideration of health effects under section 211(f)(4), this does not mean that section 211(c) limits the circumstances in which the Administrator may consider potential health effects as part of a waiver decision. Clearly, it was the intention of Congress to treat fuels and fuel additives already registered and being sold for a particular purpose differently than those which have not already been introduced into commerce. III. Method of Review A. ``Causes or Contributes'' to Emission Standard Failure Under section 211(f)(4) of the Act, twenty-three applications for waivers of the section 211(f)(1) prohibitions have been received. Of these, twenty-two applications have sought a waiver for additives for unleaded gasoline. One, the most recent, sought a waiver of the section 211(f)(1)(B) prohibitions for an additive to diesel fuel.\13\ Of these twenty-three applications, ten applications have been granted (some with conditions attached), ten have been denied, and three were withdrawn by the applicant prior to the Agency's decision. --------------------------------------------------------------------------- \13\57 FR 45790 (October 5, 1992). --------------------------------------------------------------------------- Section 211(f)(4) clearly places upon the waiver applicant the burden of establishing that its fuel will not cause or contribute to the failure of any vehicle to meet emission standards. Absent a sufficient showing, the Administrator cannot make the required determination and cannot grant the waiver. If interpreted literally, however, this burden of proof imposed by the Act would be virtually impossible for an applicant to meet, as it requires the proof of a negative proposition: that no vehicle will fail to meet emission standards to which it has been certified. Such a literal interpretation could be construed as requiring the testing of every vehicle. Recognizing that Congress contemplated a workable waiver provision, EPA has previously indicated that reliable statistical sampling and fleet testing protocols may be used to demonstrate that a fuel under consideration would not cause or contribute to a significant failure to meet emission standards by vehicles in the national fleet.\14\ --------------------------------------------------------------------------- \14\See Waiver Decision on Tertiary Butyl Alcohol (``TBA''), 44 FR 10530 (February 2, 1979). --------------------------------------------------------------------------- To determine whether a waiver applicant has established that the proposed fuel will not cause or contribute to vehicles failing emission standards, EPA reviews all the material in the public docket, including the data submitted with the application and public comments on the application, and analyzes the data to ascertain the fuel's emission effects. The analysis concentrates on four major areas of concern-- exhaust emissions, evaporative emissions, materials' compatibility, and driveability--and evaluates the data under statistical methods appropriate to the various types of emission effects. Emission data are analyzed according to the effects that a fuel is predicted to have on emissions over time. If the fuel is predicted to have only an instantaneous effect on emissions (that is, the emission effects of the fuel are immediate and remain constant throughout the life of the vehicle when operating on the waiver fuel), then ``back-to-back'' emissions testing will suffice.\15\ --------------------------------------------------------------------------- \15\Back-to-back emission testing involves testing a vehicle on a base fuel (i.e., a gasoline which meets specifications for certification fuel or is representative of a typically available commercial gasoline), then testing that same vehicle on the fuel for which the waiver is requested. The difference in emission levels is attributed to the waiver fuel. --------------------------------------------------------------------------- Unlike materials traditionally allowed in unleaded gasoline, metallics, such as MMT, produce non-gaseous combustion products, some of which may be deposited in the parts of the vehicle that come in contact with the combustion products of the burned fuel. These areas of the vehicle include the combustion chamber, the catalyst, the oxygen sensor, and all parts of the exhaust system.\16\ Since these materials build up over time,\17\ it has been traditionally accepted that the emissions effects of such additives occur over time as miles are accumulated, and that the method of deposition suggests that the effects are permanent. If the fuel is predicted to have such a long- term deteriorative effect, durability testing over the useful life of the vehicle,\18\ in addition to back-to-back testing, is appropriate.\19\ --------------------------------------------------------------------------- \16\Automakers and catalyst manufacturers point out that, since catalysts are designed with a honeycomb structure in order to maximize contact between engine combustion gases and catalyst materials, if channels within the honeycomb become blocked, the catalyst is less able to break down the exhaust gases. Furthermore, although the mechanisms associated with manganese deposits have not been completely described, catalyst manufacturers suggest that the mere disposition of manganese (without blockage of channels) would hinder the catalytic activity of the catalyst. Ethyl, however, believes that the manganese deposition on the catalyst does not hinder its activity. \17\Reply Comments of Ethyl Corporation in Support of the HiTEC 3000 Waiver Application, August 10, 1990, 28. \18\The ``useful life'' of a 1993 or earlier model year light- duty vehicle (LDV) (i.e., the amount of time or mileage accumulation through which the LDV must meet the standards to which it has been certified) is 50,000 miles or five years, whichever occurs first (Sec. 202(d)). The 1990 Amendments extended the useful life of LDVs to 100,000 miles or ten years, beginning with 1994 model year vehicles. The amendments also tightened emissions standards for 40 percent of a vehicle manufacturer's LDV and light-duty truck (LDT) sales in model year 1994, 80 percent in model year 1995 and for all vehicles after model year 1995 (Sec. 202(g)). The useful life for heavy-duty vehicles and engines is generally 120,000 miles or eleven years. \19\Durability testing over the useful life of the vehicle has involved testing two identical sets of vehicles for 50,000 miles (in the case of pre-1994 standards for LDVs), one set using the base fuel and the other using the waiver fuel. Each vehicle is tested for emissions at 5,000 mile intervals. This is essentially the same testing pattern which has been required for certification of a new motor vehicle under Sec. 206 of the Act. As noted above, under the 1990 Amendments, the useful life of LDVs has been extended to 100,000 miles beginning with the 1994 model year when more stringent emissions standards took effect (see Sec. 202 (d) and (g)). --------------------------------------------------------------------------- In addition to emissions data, EPA also reviews data on fuel composition and specifications, both to fully characterize a proposed fuel, and to determine whether that fuel would cause or contribute to a failure of vehicles to comply with their emission standards. Such a failure often can be predicted from characterization data. For example, volatility specifications of the fuel could demonstrate a tendency for high evaporative emissions. Similarly, data on materials compatibility could show potential failure of fuel systems, emission related parts, and/or emission control parts from use of the fuel. Such failures could result in greater emissions. Likewise, fuel characteristics that could cause significant driveability problems could result in tampering with emission controls and, thus, increased emissions. One issue raised previously in the context of Ethyl's present application was whether Ethyl was required to show that MMT will not cause or contribute to noncompliance with emission standards by vehicles certified to ``future'' emission standards (i.e., 1994 model year standards, which were not in effect at the time of the waiver application), as well as vehicles certified to ``current'' standards (i.e., standards in effect at the time of the waiver application). Ethyl believes that the statute only requires it to establish that MMT will not cause or contribute to the failure of vehicles to meet current emission standards. For the reasons outlined in the Agency's January 1992 waiver decision, EPA disagrees with this reading of the statute and continues to believe that it is appropriate to consider the effects of an additive on vehicles' ability to meet more stringent future standards under circumstances similar to these.\20\ (See 57 FR 2537-8 January 22, 1992.) --------------------------------------------------------------------------- \20\EPA also considered effects on compliance with future standards in a previous MMT decision. See 43 FR 41424 (September 18, 1978), In Re Application for MMT Waiver. --------------------------------------------------------------------------- In the past, EPA has analyzed both instantaneous emission effects and durability effects using statistical tests to determine if the fuel additive will cause a ``significant'' number of vehicles to fail emissions tests.\21\ Generally speaking, these tests have focused on the portion of the fleet that will actually fail emission standards as a result of using the fuel or additive.\22\ Thus, the tests used to date by the Agency primarily consider only the ``cause'' language in the statute and do not consider the portion of the statute which requires that the applicant must also show that the fuel or additive will not ``contribute'' to the non-compliance of vehicles with emission standards. --------------------------------------------------------------------------- \21\For a detailed description of the statistical tests which have been used in the past for instantaneous effects see ``Decision Document'', Texas Methanol Waiver Decision, U.S. EPA Air Docket Number EN-87-06, and for those used for durability effects, see 43 FR 41426. \22\In fact the primary criteria allows for the failure of some portion of the fleet as a result of use of the fuel or additive. --------------------------------------------------------------------------- The Agency believes that its present statistical tests and criteria do not give adequate weight to the requirement in Section 211(f)(4) that an applicant demonstrate that a fuel will not ``contribute'' to an emission standard failure.\23\ This is of particular significance in light of the Clean Air Amendments of 1990, which evidence a strong Congressional concern that more needs to be done to ensure that people are not exposed to unhealthy levels of airborne pollution. EPA is presently reviewing alternative criteria and statistical methodologies for determining whether use of a fuel or fuel additive will ``cause or contribute'' to emission exceedances. The Agency expects to initiate a rulemaking in the near future which will propose more appropriate criteria and statistical methodologies for reviewing waiver applications and will afford formal notice to future applicants of the Agency's intention to adopt revised criteria and methodologies. --------------------------------------------------------------------------- \23\In fact, the Agency raised questions about the appropriateness of these previously used approaches in its original decision on Ethyl's 1991 MMT waiver application. See 57 FR 2535, 2537 and 2538 (January 22, 1992). --------------------------------------------------------------------------- As explained below, the Agency has concluded that it would not be appropriate to utilize new criteria and statistical tests concerning which Ethyl received no prior notice in evaluating Ethyl's application. However, in the event that Ethyl reapplies in the future for a section 211(f)(4) waiver to allow the use of MMT or any other additive, that application will be evaluated in accordance with any new fuel waiver criteria in effect at that time. B. Discretionary Review As discussed in part II of this decision, above, the Agency believes that the use of the term ``may'' in Section 211(f)(4) of the Act affords the Administrator broad discretion to consider other factors in deciding whether to grant a waiver, once a waiver applicant has demonstrated that a fuel or fuel additive will not cause or contribute to an emission standard failure. This construction of section 211(f)(4) is also consistent with the other provisions of and the general purposes underlying the Clean Air Act. Although the Administrator has not relied on this discretionary authority to deny a waiver in the past, certain general principles should guide the Administrator's exercise of such authority. Although the discretion of the Administrator to consider other factors in making a waiver decision is broad, it is not unfettered. To assure that any decision based on factors other than emission standard failures is not arbitrary and is based on a proper record, the applicant and other interested persons should be afforded proper notice of any additional factors to be considered by the Administrator and an opportunity to comment or submit information concerning those factors. Any decision based on the discretionary authority of the Administrator to consider other factors should include an explanation of the factors which were considered and the relation of those factors to the decision. Moreover, any policy adopted as part of a decision to deny a waiver on a discretionary basis should be applied consistently to all similarly situated applicants. Protection of the public health is a major goal of both the Clean Air Act in general and the section 211 fuels provisions in particular. Accordingly, the Agency believes that when a waiver is sought for a fuel or fuel additive and there are unresolved concerns regarding the potential impact of that fuel or fuel additive on public health, potential health effects can and should be examined as part of the waiver process. As part of this examination of the potential health effects of a fuel or additive, the Agency should review any relevant studies or analyses of which it is aware or which are brought to its attention by the waiver applicant or by commenters on the waiver application. In addition to potential health effects, the Agency may consider other factors as appropriate in deciding whether it would be in the public interest to grant a waiver. In particular, the Agency may consider whether a waiver would be consistent with the objectives of the Clean Air Act. In each instance, the factors considered and relied upon should be clearly identified. IV. Analysis of Emissions Data A. Description of Previous Test Programs In support of its request, Ethyl conducted an extensive test program to determine the effect of MMT on the ability of vehicles to comply with current and future emission standards. It also considered the impact of MMT on nonregulated vehicle emissions, urban smog or ozone, refinery emissions, and crude oil use. Ethyl claimed that its test results established that MMT would not cause or contribute to exceedences of current or future emission standards. It also claimed that MMT use would result in other benefits consistent with Clean Air Act goals. In 1988, Ethyl assembled a test fleet of 48 light-duty vehicles, composed of eight different model types (six Buick Centurys (2.5 liter), six Buick Centurys (2.8 liter), six Buick Centurys (3.8 liter), six Chevrolet Cavaliers (2.0 liter), six Ford Escorts (1.9 liter), six Ford Tauruses (3.0 liter), six Ford Crown Victorias (5.0 liter) and six Dodge Dynastys (3.0 liter)) that together represented a broad spectrum of then current (1988) technology vehicles. To accumulate mileage, Ethyl utilized the ``Alternative Mileage Accumulation Cycle'' (AMA) which is a standard procedure utilized to accumulate mileage for certification purposes.\24\ It utilized two laboratories to measure each vehicle's exhaust emissions of the regulated pollutants (HC, oxides of nitrogen (NOx) and carbon monoxide (CO)) at 5,000-mile intervals up to 75,000 miles in the case of most vehicles and up to 100,000 miles in the case of several.\25\ It also tested a number of these vehicles for evaporative HC, particulate and manganese emissions, materials compatibility, driveability and catalyst durability. --------------------------------------------------------------------------- \24\A driving cycle is a description of how to drive a vehicle to accumulate mileage, including such things as a what percentage of driving should be done at what speed and what the overall average speed should be. The AMA cycle is described in EPA Mobile Source Advisory Circular 37-A, (See Docket A-91-46) and is essentially prescribed for use by manufacturers to accumulate mileage for certification of vehicles (See 40 CFR 86.092-26). A driving cycle is used so that test vehicles accumulate mileage in a manner that is supposedly representative of in-use vehicles. The emissions of a test vehicle that has accumulated mileage according to a driving cycle representative of in-use vehicles are more likely to be representative of in-use vehicles' emissions. There are actually three alternative cycles associated with the AMA; however, the average speeds of the three alternatives are very similar, ranging from 29.9 mph to 30.72 mph. \25\The ``useful life'' of model year 1993 and earlier light- duty vehicles (LDV's) is 50,000 miles or five years, whichever occurs first (section 202(d)). However, the Clean Air Act Amendments of 1990 extended the useful life of LDV's to 100,000 miles or ten years, beginning with 1994 model year vehicles. For the standards that begin to take effect in model year 1994, section 207(c) provides for intermediate in-use standards for several years. --------------------------------------------------------------------------- Ethyl analyzed the data collected using EPA's previously used statistical tests (43 FR 41424, September 18, 1978) and additional tests developed by its consultants to further characterize the data. Its analysis indicated that, on average, MMT at the requested concentration would result in a 0.018 gpm increase in HC emissions and decreases in NOx and CO emissions. The analyses further indicated that, when EPA's previously used tests are applied, the increase in HC emissions would not cause or contribute to vehicles' failure to meet the current HC emission standard. The results of Ethyl's testing for materials compatibility, driveability and catalyst durability also indicated that MMT would have no significant adverse effects on vehicles' ability to meet current emission standards under average driving conditions. On that basis, Ethyl claimed that it had made its statutorily required showing. Ethyl also submitted data on the catalyst efficiency of the vehicles which it tested. Ethyl performed back-pressure tests\26\ on all its vehicle fleet except one model group after accumulation of 75,000 miles. Back-pressure tests were also performed on a pair of Ford Crown Victorias, one operated on MMT-fuel and one on clear fuel, at speeds higher than those used in Ethyl's 48-vehicle test program.\27\ The results of these tests indicated that back-pressure was not significantly different in the MMT vehicles when compared to the clear fuel vehicles. Ethyl also operated two 5.7 liter Corvettes at extremely high speeds (100 mph) for 25,000 miles, one using MMT fuel and one using clear fuel. Although similar in magnitude, the back pressure for the MMT vehicle was slightly higher than that for the clear vehicle. Ethyl also presented catalyst efficiency\28\ data based on engine-out emissions of its fleet and based on ``slave engine'' testing\29\ for half of its fleet. Results of the slave engine testing indicated no statistically significant difference between the catalyst efficiencies for the MMT vehicle components when compared with the clear vehicle components. Finally, four Chevrolet Corsicas were operated to 100,000 miles, two utilizing MMT fuel and two with clear fuel. The purpose of this testing was to investigate MMT's effect on the catalyst for a longer mileage interval than the 75,000 miles over which most of Ethyl's fleet had been driven. Catalyst efficiencies of the MMT vehicles were not significantly different when compared to the clear fuel vehicles. --------------------------------------------------------------------------- \26\Back pressure tests are used to determine if significant plugging has occurred in a vehicle's catalyst. The total pressure ahead of the catalyst is back pressure. This pressure is a measure of constriction in flow through the exhaust system caused by flow of the exhaust through the emissions control system and the noise- reducing components of the vehicle. If plugging has occurred in a vehicle, the total pressure ahead of its catalyst, the back pressure, should be greater than expected (e.g., greater than a matching control vehicle). \27\In this program the maximum speed was 65 mph for the first 25,000 miles and 80 mph for an additional 10,000 miles. \28\Catalyst efficiency is a measure of what fraction of the emissions entering the catalyst are actually removed (or catalyzed) by the catalyst. \29\``Slave engine'' testing is the testing of vehicle components on a single engine which is not in a vehicle. In this case, catalyst efficiencies between control and MMT vehicles were investigated using exhaust gases from this single engine which were routed through the removed catalysts. This would likely result in a more accurate analysis of catalyst efficiency, since one possible confounding factor, vehicle to vehicle variability, would be eliminated. --------------------------------------------------------------------------- Ford presented original test data which Ford said supported its contention that actual in-use MMT-induced HC emissions increases are potentially far greater than those reported by Ethyl.\30\ Ford conducted testing on a more limited scale utilizing eight vehicles, representing two model groups, run for 105,000 miles. Ford chose two model groups which were representative of its newest technology vehicles at the time. One (the Explorer) represented a technology that Ford believed may be especially prone to exhibit a buildup of manganese, due to significantly higher operating temperatures and loads than those of passenger cars. The other model group, the Escorts, had close-coupled catalysts, a design which is being incorporated into many new vehicles in order to meet tighter emissions standards. Like Ethyl, Ford operated part of its test fleet on clear fuel and part on fuel containing 1/32 gpg MMT. However, Ford's test program differed from Ethyl's program in several ways. When accumulating mileage, Ford utilized a commercial gasoline which contained all of the additives (detergents, etc.) typically found in such fuels. Ethyl utilized a very high quality test fuel with tight specifications and no additives. (Although used for actual emissions testing purposes, Ethyl's fuel would not be allowed for mileage accumulation when certifying vehicles since it is not representative of in-use fuel.) When accumulating mileage, Ford utilized what it called its ``durability cycle'' which it had previously developed. Compared to the AMA cycle used by Ethyl, Ford's driving cycle had a higher average speed (54 miles per hour (mph) versus 30 mph), and a higher percentage of high speed driving.\31\ (As previously mentioned, Ethyl utilized the AMA cycle used for certification purposes.) Additionally, in the Ford program, vehicles were tested for emissions at five mileage intervals (5,000, 20,000, 55,000, 85,000\32\ and 105,000 miles) and six emissions tests were done at each testing interval. Ethyl, by comparison, conducted testing every 5,000 miles to 75,000 miles (15 intervals) and utilized two emissions tests at each interval.\33\ Ford's test vehicles showed an elevation of HC emissions with MMT that was substantially greater than the 0.018 gpm reported by Ethyl from its test program. --------------------------------------------------------------------------- \30\EPA's emissions testing lab and Ford's lab routinely undergo correlation testing and the data indicate that correlation is good between the labs. (See memorandum, with attached data, from Martin E. Reineman, EPA Manager of Correlation and Engineering Services, Office of Mobile Sources, January 3, 1992, Docket A-91-46.) \31\Ford indicated that drivers who accumulated mileage in its test program were asked to follow posted speed limits. Ford indicated that the cycle consisted of 5% city driving (25 to 45 mph), 5% gravel or off road driving (25 to 45 mph), 20% rural driving (45 to 55 mph), and 70% highway driving (65 mph). Posted speed limits are shown in parentheses. By way of comparison, the AMA cycle consists of 16.1% of driving at 30 mph, 22.6 at 35 mph, 20.9 at 40 mph, 6.4 at 45 mph, 17% at variable speed and one of the three following options: 16.7% at 50 mph or 16.5% at 55 mph or 8.6% and 7.9% at 55 mph and 70 mph, respectively. \32\In fact, only two of the four Escorts were tested at 85,000 miles. \33\Although Ethyl conducted additional emissions tests at some mileage intervals when the initial two tests showed high variation, these additional tests were not used in Ethyl's analysis of its data. --------------------------------------------------------------------------- Toyota also submitted data on a single vehicle which was operated for 30,000 miles on MMT-containing fuel after which the oxygen sensor and catalyst were replaced with new components and then driven on fuel not containing MMT for 30,000 miles. Toyota also used a driving cycle with an average speed (41.7 mph) higher than that used by Ethyl for mileage accumulation and used fuel with what Toyota believed was a relatively high trace level of lead than that usually found in unleaded gasoline (0.0045 gpg lead) and oil with a relatively high phosphorus level (0.13 weight percent). Toyota referred to this test procedure as the ``Toyota 9-Laps'' and presented evidence which it said suggested that the catalyst degradation seen by vehicles using the Toyota 9-Lap test was very similar to in-use catalysts tested by Toyota. Hence, Toyota suggested, these ``adjustments'' made in creating the Toyota 9- Lap make the testing of a vehicle more consistent with what would happen in actual in-use driving. Toyota's data indicated an HC level after the first 30,000 miles of vehicle use (on MMT fuel) about 0.1 gpm higher than the same vehicle after the vehicle was driven for a second 30,000 mile interval with a new catalyst and oxygen sensor. Toyota also submitted data indicating that the efficiency at which the catalyst was operating for the MMT-exposed components was less than that for the non-MMT exposed components. Some time after EPA's January 8, 1992 denial decision, EPA and Ethyl entered into discussions concerning a possible settlement of the court case which Ethyl had filed. In the context of these discussions, Ethyl submitted to the Agency new data it had developed since the denial decision. Ethyl tested six 1991 Escorts, using both the relatively high-speed driving pattern similar to that utilized by Ford in its testing of 1991 Escorts (the Ford cycle) and, also, after changing emissions system components (catalyst and oxygen sensor), the driving cycle used by Ethyl in the original test program (EPA's durability certification cycle also known as the AMA). Half of the vehicles utilized MMT-containing fuel and half were run on clear fuel (fuel not containing MMT). Ethyl also performed some catalyst efficiency tests on these vehicles utilizing a ``slave engine.'' Ethyl also tested six 1988 Escorts which were used in its original test program driven on the AMA cycle. In the new program, after replacing the catalyst and oxygen sensor, Ethyl continued mileage accumulation, from 75,000 to 100,000 miles, utilizing the Ford cycle. Likewise, Ethyl tested six 1988 Buicks from its original fleet accumulating mileage (100,000 to 115,000 miles) using the Ford cycle but without replacing any components. Ethyl also accumulated mileage on seven pairs of 1992 vehicles (four Crown Victorias, Six Buick Regals and four Ford Mustangs) in test programs covering from 45,000 to 100,000 miles beyond break-in with and without MMT, using the Ford cycle. Based on its inspection and analysis of the new Ethyl data, the Agency ultimately concluded that Ethyl's program had demonstrated driving cycle does not contribute significantly to MMT-induced increases in hydrocarbon emissions. However, in addition to addressing the issue of driving cycle, the Ethyl data appeared to confirm the finding by Ford that 1991 Escorts experienced a much higher MMT-induced HC increase than that observed in other models tested (either in Ethyl's 1992 fleet or in the original 1988 Ethyl fleet). The Agency was concerned that these data could indicate that certain engine and emissions control system configurations were more vulnerable to an MMT- induced emissions increase irrespective of driving cycle. To further assist the Agency in developing a test program, EPA held a workshop in October of 1992 and presented a proposed test program which could address in a timely manner specific unresolved issues concerning the effect of MMT on emissions: (1) Whether other vehicles utilizing fuels containing MMT are likely to experience increases in hydrocarbon emissions similar to those observed in 1991 Ford Escorts; and (2) whether fuels containing MMT have significant adverse effects on emissions from vehicles utilizing the technologies most likely to be employed to meet future standards. Ultimately the court case was not settled; however, the test program presented by the Agency at the workshop was largely adopted by Ethyl and is the basis of its most recent test program involving the 1993 fleet. These vehicles (with the previously mentioned 1992 vehicles) comprise Ethyl's most recent dataset.\34\ --------------------------------------------------------------------------- \34\On May 25, 1993, and on subsequent dates, Ethyl provided summaries of the 1992/93 test data to EPA staff and these have been placed in public docket A-93-26. --------------------------------------------------------------------------- Ethyl accumulated mileage on three 1992 model year vehicles (four Crown Victorias to 100,000 test miles,\35\ six Buick Regals to 65,000 test miles and four Ford Mustangs to 45,000 test miles) and six 1993 model year vehicles (six Toyota Camrys to 85,000 test miles, six Oldsmobile Achievas to 65,000 test miles, six Dodge Shadows to 55,000 test miles, six TLEV Ford Escorts to 85,000 test miles, six Honda Civics to 80,000 test miles and four 49-state Ford Escorts to 30,000 test miles) with and without MMT. The driving cycles used for these vehicles were an intermediate driving cycle of 45 mph on average for the 1993 model year vehicles, an average 55 mph driving cycle (i.e., the Ford Cycle) for all mileage accumulation on the 1992 Ford Mustangs and for the initial 45,000 miles of operation on the 1992 Crown Victorias and Buick Regals and an average driving cycle of 45 mph was utilized for these two models thereafter. --------------------------------------------------------------------------- \35\As referred to here, ``test miles'' indicates mileage accumulated after break-in (break-in mileages vary among these models) and during which some vehicles were run on fuel containing MMT while control vehicles were run on clear fuel. --------------------------------------------------------------------------- B. Comments on Vehicle Emissions Issues EPA provided an opportunity for the public to submit written comments.\36\ Many comments were received from a wide variety of interests, including refiners, automakers, emission control manufacturers, states committees, environmental and public interest groups and private citizens. Taken together, the comments touched on every aspect of Ethyl's application. The following is a summary of the comments. --------------------------------------------------------------------------- \36\As mentioned previously, the comments received concerning Ethyl's remanded waiver application are available in public docket A-93-26. --------------------------------------------------------------------------- Four automakers (Ford Motor Company (Ford), General Motors Corporation (GM), Toyota Technical Center, U.S.A., Inc. (Toyota), and Chrysler Motors Corporation (Chrysler)), the American Automobile Manufacturers Association (AAMA), and the Manufacturers of Emission Controls Association (MECA) all recommended denial of Ethyl's request and expressed several concerns with regard to the addition of MMT to unleaded gasoline. First, they noted that the use of MMT will cause an increase in HC emissions. Most indicated that the more stringent emissions standards that began taking effect in model year 1994 will make any increase in HC emissions particularly troublesome. Further, they stated that newer technology vehicles will likely be equipped with catalysts which are nearer the engine (more ``closely coupled'') and that such close coupling, they stated, results in higher catalyst temperatures that may make the catalyst more prone to the deposition of manganese. These commenters indicated that deposition of manganese compounds on the surface of the catalyst would impair the catalytic breakdown of emissions from the engine, thereby decreasing catalyst effectiveness. Additionally, they were concerned that MMT, even at the 1/32 gpg Mn concentration requested, would plug catalysts and thus reduce the surface area of the catalyst available to break down emissions from the engine, especially in the case of vehicles operated under driving conditions which result in higher temperatures such as heavy load or high speed. Under such conditions, it was pointed out, the vehicle may be more prone to deposition of manganese. Ethyl indicated that the assertions that it must ``conclusively'' demonstrate the absence of negative effects is not required by the section 211(f)(4) standard. Ethyl believes that it need only demonstrate, by a preponderance of evidence, that the additive will not cause or contribute to the failure of emission control devices to comply with applicable emission standards, and, further, it believes that it has made this showing. Ethyl also stated that the EPA test program proposed at its October 1992 workshop involving the accumulation of 65,000 test miles, would be sufficient for purposes of gauging the effect of MMT on emissions. Ethyl commented that it followed this proposal in the 1992/93 test fleet, although mileage accumulation has continued beyond 65,000 miles for three of the eight model year vehicles tested without new emission results different from the trends established through 65,000 miles. With respect to the automakers' concerns about effect of MMT on newer emission technology such as close-coupled catalysts, Ethyl indicated that the use of the 1993 Transitional Low Emission Vehicle (TLEV) Honda Civic in its most recent test program was intended so as to introduce a vehicle which has the most physically possible close- coupled emission technology (i.e., one connected directly to the exhaust manifold). Despite such close-coupling, Ethyl indicated that the differences in hydrocarbon emissions between clear and MMT-fueled 1993 TLEV Honda Civics was minimal. Ethyl also indicated that this concern about close-coupled catalysts completely ignores that Ethyl tested two 1988 models and three 1993 models equipped with close- coupled catalysts without showing any significant adverse effects on emissions. Toyota submitted data on catalysts and oxygen sensors from in-use customer vehicles from Canada where MMT is used as a fuel additive. Toyota believes that these catalysts and oxygen sensors indicate that exhaust emissions of hydrocarbons and carbon monoxide are higher from catalysts/oxygen systems collected in Canada than comparable catalyst/ oxygen systems from U.S. vehicles. Also Toyota submitted photographs of a catalyst taken from a high mileage Canadian Hilux pickup truck which showed plugging of the catalyst passages. Ethyl's response to Toyota's catalyst/oxygen system data is that it is not clear from the description of the Toyota test results precisely what can be concluded from the test program. Ethyl stated that, without a detailed vehicle history, there is no basis to conclude that MMT had an effect on the catalyst/oxygen system data. Chrysler submitted data on the analysis of four catalysts, which was completed by Johnson Matthey Incorporated (JMI) at Chrysler's request, that had various degrees of manganese deposition from Canadian vehicles exposed to MMT in the fuel. It indicated that the results of the analysis demonstrate that the washcoat of both the partially plugged catalysts and unaffected catalysts exhibit a clear layer of ``densified'' washcoat containing large quantities of manganese oxides. Chrysler believes that the JMI report supports its concern that manganese oxides can fill the catalyst pores, thereby covering precious metal sites or decreasing wash coat surface area, consequently eventually decreasing catalyst activity. Regarding the automakers' concerns about the Additive's effect on emissions system components, such as exhaust oxygen sensors, exhaust gas recirculation valves, catalysts and oxygen sensors, Ethyl stated that it has already provided extensive data showing that the Additive does not adversely effect any of these emission system components.\37\ (Ethyl's test programs are discussed in the previous section.) --------------------------------------------------------------------------- \37\Public Docket A-92-41, No. IV-D-3 (summarizing Ethyl's emission control component testing.) --------------------------------------------------------------------------- Nineteen small refiners including the National Petroleum Refiners Association all recommended approval. They concurred in Ethyl's assessment of the economic benefits and reduced refinery and vehicle emissions that would accrue from the replacement of octane obtained through higher-severity refining with octane obtained from MMT. Several emphasized that MMT would be especially helpful to small refiners since octane enhancement from MMT requires less capital investment than other means of increasing octane. Many refiners also pointed out that refinery operations at lower severity would result in decreased aromatic and benzene emissions from vehicles and increased yield for each barrel of crude oil refined. C. Available Data Meet Previously Used Criteria The criteria and statistical tests previously used by EPA to examine durability waiver applications were used only once by the Agency prior to Ethyl's 1990 application for the use of MMT.\38\ These tests include a variety of approaches to durability data designed to determine whether the additive causes increases in regulated pollutants and, if so, whether those increases bring about failure of vehicles in the fleet to meet the standards to which they were certified. While EPA has some concerns regarding the appropriateness of these criteria and tests for current conditions, the Agency does not intend in this action to hold Ethyl to any new criteria and/or tests that are not currently in place. Accordingly, the following discussion is addressed primarily to the results of applying the most critical of the previously used EPA tests.\39\ --------------------------------------------------------------------------- \38\The test were used in EPA's examination of Ethyl's 1978 application. For a description of these tests, see EPA's decision on the application at 43 FR 41424, September 18, 1978. \39\EPA has carefully reviewed Ethyl's application of the test to these data in various combinations and has concluded that the tests were conscientiously and accurately applied. This review focused particularly upon the application of the ``integrated emissions test'', the ``cause or contribute'' test, and the overall sign test. --------------------------------------------------------------------------- The earliest set of test results under consideration here (tests of 1988 vehicles submitted with Ethyl's 1990 application) exhibit the most pronounced MMT-caused emissions increases of the data generated by the applicant (about 0.02 gm/mi\40\, but these increases fall substantially short of failure on the determinative ``cause or contribute'' test\41\ (3 of 8 vehicle models tested fail for HC and 4 of 8 models fail for CO, while 7 of the 8 models tested are required to fail before the additive fails this overall test on either pollutant). --------------------------------------------------------------------------- \40\Determined by integration of emissions test results gathered over the full range of mileage supplied by the applicant. \41\Ethyl's consultant, Systems Applications, Inc., describes this test on page 19 of a report that was included as Appendix 2A in Ethyl's May 9, 1990 application for waiver. This co-called ``cause or contribute'' test, really addresses the question of whether the additive ``causes'' a failure to meet the certified standard for a regulated pollutant for each model group and then looks to see if enough model groups failed the test to warrant the conclusion with high confidence that more than half of the models are caused to fail by operation on the additive. --------------------------------------------------------------------------- When the larger body of all available and appropriate\42\ long-term emissions data on High-Tech 3000 is evaluated using these previously used EPA tests, the conclusion is that these increases (averaging 0.02 gm/mi for HC) bring about failure of the ``cause or contribute'' test in only 4 (for HC) or 5 (for CO) of the 19 model groups tested by the applicant and others. Failure of that test\43\ must occur in at least 13 of the 19 model groups examined before the additive is deemed to have failed the overall test with 90% confidence. Fourteen of 19 must fail before the test is failed at the 95% confidence level.\44\ --------------------------------------------------------------------------- \42\Appropriate data are considered to be those collected with Federal Test Procedure (FTP) testing using an experimental design with a control group and no obvious sources of bias. The data referred to here include the eight 1988 models tested by Ethyl, the two 1991 models tested by Ford, and the eight 1992 and 1993 models tested by Ethyl. \43\In order for a model to fail the test, emissions from the additive-fueled vehicles must be sufficiently high that then percent of the represented fleet of that model group using the additive is predicted to exceed the standard beofre the end of its useful life. The control vehicles must reach this failure rate at a higher mileage than the additive-fueled vehicles. \44\These ``confidence levels'' correspond, respectively, to the 0.10 and 0.05 significance levels. The significance level is the probability that a decision to reject the null hypothesis (and find an increase) will be a result of sampling error and thus be incorrect. --------------------------------------------------------------------------- If the newer technology 1992 and 1993 vehicles tested by the applicant are examined in isolation from the earlier test programs, the data (with an average HC effect of 0.002 gm/mi) pass the historical tests even more easily than is the case for the data combinations examined above. None of the nine models failed the ``cause or contribute'' test for hydrocarbons and only one failed for carbon monoxide. Seven of nine models would have to fail for the additive to fail the overall sign test at the 90 percent confidence level and eight would have to fail for 95 percent confidence. The overall conclusion from the above analysis, then, is that Ethyl's additive passes the most critical of the historical tests with a comfortable margin. D. Data on Newer-Technology Vehicles Meet More Stringent Criteria Notwithstanding the Agency's conclusion that it would not be appropriate to require Ethyl to satisfy new statistical tests concerning which it has not been given prior notice and the Agency's decision to evaluate Ethyl's application primarily according to the previously utilized statistical tests, the Agency nevertheless considers its existing tests and the criteria that they implement to be obsolete under current conditions.\45\ --------------------------------------------------------------------------- \45\The tests are extremely conservative in that they place most of the burden of proof on the Agency rather than on the applicant. The ``cause or contribute'' test is failed by an engine family only under circumstances where emissions from the family are so high that an additive--caused increase in some pollutant pushes more than ten percent of the vehicle fleet into violation of the standard. Moreover, the final sign test that is applied to the model-specific results is failed by the additive only when it may be concluded with high confidence that more than half of the models in the represented population would fail the model-specific test. In practical situations with relatively small samples, this sign test permits a high percentage of the models in the sample to fail before the additive is declared to have failed the test. These tests, then, may permit the granting of waivers in the face of substantively significant emissions increments attributable to an additive-- increments that would tend to offset the benefits from an increasingly stringent regulatory program aimed at bringing the nation's most serious air quality problems under control. Agency concerns with these tests were addressed previously in its decision on Ethyl's 1990 application (57 FR 2535, January 22, 1992) and in (58 FR 64761, December 9, 1993). --------------------------------------------------------------------------- Therefore, EPA has gone beyond the historical tests to examine Ethyl's data on the use of the additive with newer technology vehicles under more stringent criteria of the sort that seem to be warranted by current conditions. For this analysis, EPA chose to examine the additive's performance against the most stringent of the possible criteria--a requirement that the additive cause no statistically significant increase in emissions. If one uses a one-sided null hypothesis that the additive causes no increase in HC emissions, one may employ various statistical tests to examine the credibility of that hypothesis in light of the test results. One such test is the computer-intensive ``permutation test'' in a form called an ``approximate randomization'' test.\46\ Application of this test to the full mileage range of HC emissions data from Ethyl's tests of 1992 and 1993 vehicles results in a failure to discern any ``real'' emissions increase at all--that is, no increase that we may not reasonably attribute to sampling error rather than to an additive effect on HC in the sampled vehicle population.\47\ --------------------------------------------------------------------------- \46\The permutation test is built around the idea that, if the null hypothesis is correct, the increase due to the additive in the sample is only one member of a distribution of all possible such increases computed from assignments of vehicle emissions to fuel groups within models. Only if the fuel-related increase from the sample is an extremely unusual result in theis distribution of possible increases is it reasonable to reject the null hypothesis and conclude that the additive actually brought about an increase in emissions. The way that this method works in practice is that, on each iteration of the computer program, the computer randomly rearranges the fuel group assignments among the emission results within each model group separately. The emission values assigned (for that iteration) to the additive fuel group are then summed over the entire sample to form the test statistic. This process is repeated a very large number of times (one million in this case) and the resulting test statistics are tabulated. Only if the same test statistic, as computed from the empirical sample, exceeds a pre- determined percentage of the simulated test statistics may we reject the ``no-difference'' hypothesis and conclude with the necessary degree of certainty that an increase has occurred. \47\This conclusion holds even when the test is performed at the 0.10 significance level used in conducting the statistical testing on the data from Ethyl's 1978 application. It is important to note that the original Ethyl test fleet of 1988 model year vehicles that are now older than those representing the newest Ethyl data set did not fare as well and, as mentioned previously, do demonstrate statistically significant increases in HC emissions. --------------------------------------------------------------------------- E. Finding Based on all of the information then available concerning the potential effect of use of MMT in unleaded gasoline on regulated emissions, as submitted by Ethyl and others, the Administrator of EPA determined on November 30, 1994 that, ``Ethyl has satisfied its burden under Clean Air Act 211(f)(4) to establish that use of HiTEC 3000 at the specified concentration will not cause or contribute to a failure of any emission control device or system (over the useful life of any vehicle in which such device or system is used) to achieve compliance by the vehicle with the emission standards with respect to which it has been certified.'' The basis for this determination was described briefly in the Administrator's November 30, 1994 notice, and has been reviewed in detail above. The November 30, 1994 determination was specific to Ethyl's present waiver application. As the Administrator made clear in the notice announcing the determination, it does not apply to any new application concerning either HiTEC 3000 or MMT in the event that this decision to deny Ethyl's application on the basis of concerns regarding potential health effects is upheld in any subsequent judicial review. Although Ethyl may be able to sustain its burden under Section 211(f)(4) in the context of any future waiver application, any such application must include satisfactory data addressing the effect on vehicles in production at that time and will be evaluated according to the statistical methods and criteria for evaluation of waiver applications in effect at that time. V. The Onboard Diagnostics Issue Prior to the Administrator's November 30, 1994 finding concerning emission effects, three auto manufacturers, Ford, General Motors (GM), and Chrysler, and the American Automobile Manufacturers Association (AAMA), all commented on concerns about the impact of the oxidative products of MMT on onboard diagnostic (OBD II) systems employing before-catalyst and after-catalyst oxygen sensors.\48\ --------------------------------------------------------------------------- \48\An Onboard Diagnostic System, with the present generation commonly known as OBD-II, monitors the activity of an automobile's emission control system, primarily the catalytic converter, and alerts the driver via a dashboard light in the event of a malfunction. Put simply, this aspect of the OBD system functions by utilizing devices before and after the catalyst which ``sense'' the presence of oxygen. If the catalyst is functioning properly, it will absorb a certain amount of oxygen and a specified decrease in oxygen content in the exhaust gases can be determined by comparing the oxygen ``sensed'' before and after the catalyst. If the catalyst is functioning improperly, oxygen storage by the catalyst is impaired and a drop in exhaust gas oxygen after the catalyst beyond the proper range is ``sensed'' by the OBD system. --------------------------------------------------------------------------- GM concerns regarding the OBD II system were two-fold. Its first concern was that since it is known that manganese oxide has the ability to store oxygen, a potential problem could occur with dual oxygen sensor systems. GM stated that, with manganese oxide covering the catalyst and the oxygen sensors, a false oxygen storage capacity of the catalyst could be indicated by the OBD II system, which could then indicate that the catalyst was still working properly while the opposite could be true. GM's second concern was that the catalyst would act as a ``filter'' and manganese oxide from MMT combustion passing through the exhaust system would coat the before-catalyst oxygen sensor and after-catalyst oxygen sensors unevenly, thus causing the OBD II system to malfunction. GM also stated that in the 1994 model year GM planned to market two engine families equipped with OBD II systems employing before- and after-catalyst oxygen sensors. With respect to the automakers' concern that use of MMT would adversely affect operation of the OBD II system, on July 15, 1993, Ethyl submitted data which it believed demonstrated that this concern has no basis.\49\ Ethyl stated that no production vehicles were then equipped with OBD-II systems and that the primary hardware approach being considered by the automobile manufacturers involves the use of exhaust gas oxygen (EGO) sensors before and after the catalytic converter to monitor converter efficiency. Ethyl further commented that test data generated by Ethyl showed that use of the additive would have no adverse effect on either the hardware component of these planned ODB-II systems (i.e., the oxygen sensors), or on the catalytic converter itself. Ethyl noted that, ``[s]ince these future systems are currently under development, it is impossible to consider the long term effects of MMT on these systems.'' --------------------------------------------------------------------------- \49\See Public Docket A-93-26, Number II-D-8, Appendix 5. --------------------------------------------------------------------------- On November 4, 1994, only 26 days prior to the mandatory date for a decision on Ethyl's waiver application, Ford Motor Company submitted a report describing bench testing\50\ of catalysts, in which Ford measured the oxygen storage capacity of catalysts which had been deliberately degraded and then exposed to the emissions from MMT- containing fuel. Ford's conclusion based on these tests was that the exhaust gas oxygen (EGO) sensors would be affected by the deposition of manganese oxides associated with MMT use, thus sending incorrect signals to the diagnostic control system in the vehicle. --------------------------------------------------------------------------- \50\Bench testing means the testing of components during which time the components are not actually in the vehicle. The details of this testing can be found in Document II-D-56 in Docket A-93-26. (An incomplete preliminary report of this information was submitted to the Agency in Document II-D-38, Docket A-93-26.) --------------------------------------------------------------------------- Although the Agency regarded the concerns expressed by Ford in its November 4, 1994 submission regarding the effect of MMT use on OBD systems as potentially very important, based on the very limited analysis which could be undertaken prior to the November 30, 1994 deadline for a decision concerning Ethyl's application, the Agency concluded that the limited bench testing submitted by Ford did not allow a conclusion concerning the likelihood that a significant impact would actually occur during vehicle operation. In addition, the Agency had several questions regarding the procedures involved in the Ford testing which could not be resolved within the available time. The November 30, 1994 notice announcing the Administrator's determination concerning emission effects made it clear that EPA was concerned about this issue and would retain the authority to take appropriate action in the future pursuant to Clean Air Act Section 211(c). EPA met with staff of Ford in February of 1994 in order to discuss Ford's concerns raised in its November 4, 1993 submission. Ford generally expressed the same concerns as had been expressed by GM (and discussed above).\51\ According to Ford, its testing showed that combustion of gasoline containing MMT deposits a layer of manganese oxide on top of the catalyst washcoat and that this causes the EGO Sensor to measure a lower oxygen level, thereby indicating a higher oxygen storage capacity than that which would be indicated by the catalyst without MMT. As a result, a malfunctioning catalyst might not be detected. Ford expressed particular concern because it had just introduced three 1994 model year vehicle families employing OBD-II, whereas the other automakers will not have systems out until the 1996 model year. --------------------------------------------------------------------------- \51\Ford's concerns are discussed in more detail in a memo to docket A-93-26, with an attachment submitted to the Agency entitled ``Section 211(c) Impacts of MMT''. --------------------------------------------------------------------------- Recently, on May 3, 1993, Ford submitted additional information which the Agency is currently reviewing. This new information appears to provide further evidence to substantiate the concerns expressed by Ford regarding the impact of MMT use on OBD systems. Unlike the previously submitted Ford data, the new data address an actual production vehicle fitted with a failed catalyst and the effect use of MMT had on the OBD system's ability to detect failure of the catalyst. The Agency is continuing to investigate the question of the potential impact of use of MMT in unleaded gasoline on OBD systems. If after further investigation EPA concludes that the concerns expressed by the vehicle manufacturers are warranted, EPA intends to initiate an appropriate rulemaking under Section 211(c). VI. Manganese Health Assessment\52\ --------------------------------------------------------------------------- \52\The assessment presented here is taken from ``Reevaluation of Inhalation Health Risks Associated with Methylcyclopentadienyl Manganese Tricarbonyl (MMT) in Gasoline'' (United States Environmental Protection Agency, 1994b) which can be found in the docket in its entirety. --------------------------------------------------------------------------- A. Introduction In 1990, the EPA Office of Research and Development (ORD) assessed the potential health risks associated with the use of methylcyclopentadienyl manganese tricarbonyl (MMT) as an additive in unleaded gasoline (U.S. Environmental Protection Agency, 1990).\53\ Later, ORD (Preuss, 1991) reaffirmed its assessment after considering a resubmitted waiver application for MMT from Ethyl Corporation. As identified in earlier ORD evaluations (U.S. Environmental Protection Agency, 1990; Preuss, 1991), a key issue is the potential health risk associated with inhalation exposure to manganese tetroxide (Mn3O4), which is the primary by-product resulting from the combustion of MMT in gasoline. New information on manganese (Mn) health effects and exposure is incorporated in this revised risk assessment. (United States Environmental Protection Agency, 1994b) --------------------------------------------------------------------------- \53\The many references in this section of the decision dealing with manganese health effects are referred to in parentheses and listed at the end of this section in subsection E. --------------------------------------------------------------------------- This reevaluation has four components: (1) a health effects assessment, (2) an exposure assessment, (3) a risk characterization relating the first two, and (4) a summary and conclusions. This evaluation summarizes earlier ORD assessments and incorporates information from certain other major new reports and analyses.\54\ --------------------------------------------------------------------------- \54\The reader is referred to the appendices of the full EPA/ORD reevaluation for more detailed background information. This report, ``Reevaluation of Inhalation Health Risks Associated with Methylcyclopentadienyl Manganese Tricarbonyl (MMT) in Gasoline'', can be found in its entirety, including the appendices, in docket A- 91-46. Appendix A presents dose-response analyses, Appendix B presents an exposure assessment, and Appendix C contains the current verified Mn inhalation reference concentration (RfC) as it appears in the U.S. EPA Integrated Risk Information System (IRIS, 1993). --------------------------------------------------------------------------- B. Health Effects Assessment 1. Background The toxicity of Mn varies according to the route of exposure. By ingestion, Mn has relatively low toxicity at typical exposure levels due in part to a low rate of absorption from the gastrointestinal tract and in part to efficient regulation by homeostatic mechanisms. Manganese is considered a nutritionally essential trace element and is required for certain enzymes important for normal functioning of the central nervous system and other body organs. However, by inhalation, Mn has been known since the early 1800s to be toxic to workers. It should be noted that Mn occupational studies predominantly (and sometimes exclusively) involve men. Neurobehavioral, respiratory, and reproductive effects are the primary features of excessive occupational exposure to Mn. Manganism is characterized by various psychiatric and movement disorders, with some general resemblance to Parkinson's disease in terms of difficulties in the fine control of some movements, lack of facial expression, and involvement of underlying neuroanatomical and neurochemical factors. Neurobehavioral effects of Mn intoxication are generally more clinically prominent than respiratory or reproductive effects. However, respiratory effects (e.g., pneumonitis) and reproductive dysfunction (e.g., reduced libido) are also frequently reported features of occupational Mn intoxication. The available evidence is inadequate to determine whether or not Mn is carcinogenic; some reports suggest that it may even be protective against cancer. Based on this mixed but insufficient evidence, EPA has placed Mn in a Group D weight-of-evidence category, which signifies that it is not classifiable as to human carcinogenicity. Given these features of Mn toxicity, the health assessment focuses on the potential for chronic noncancer effects. Various epidemiological studies of male workers exposed to Mn at average levels below the current American Conference of Governmental Industrial Hygienists Threshold Limit Value (TLV) (5 mg/m\3\)\55\ have shown neurobehavioral, reproductive, and respiratory effects, both by objective testing methods and by workers' self-reported symptoms on questionnaires. Neurobehavioral effects generally have reflected disturbances in the control of hand movements (e.g., tremor, reduced hand steadiness) and/or the speed of movement (e.g., longer reaction time, slower finger-tapping speed). Reproductive effects have included a decrease in the number of children born to Mn-exposed workers (compared to matched controls) and various self-reported symptoms of sexual dysfunction. In recent studies at low to moderate occupational exposure levels, respiratory effects have been reflected primarily in self-reported symptoms of respiratory tract illnesses rather than in differences between objective pulmonary function measurements in Mn- exposed and control workers. However, the lack of studies using more sensitive investigational methods and the existence of some limited evidence from an epidemiological study of school children raise a degree of concern about pulmonary function effects in relation to lower level Mn exposure. --------------------------------------------------------------------------- \55\The American Conference of Governmental Industrial Hygienists (1992) has given notice of intent to lower the TLV to 0.2 mg/m\3\. --------------------------------------------------------------------------- The precise mechanisms of Mn neurotoxicity are not well understood, but it appears that Mn can affect several different aspects of central nervous system (CNS) function and structure. Some experimental evidence suggests that the mechanisms of Mn toxicity may depend on the oxidation state of Mn. However, both the trivalent form (Mn3+) and the divalent form (Mn2+) have been demonstrated to be neurotoxic.\56\ Also, both forms of Mn can cross the blood-brain barrier, although research suggests that Mn3+ is predominantly transported bound to the protein transferrin (Aschner and Gannon, 1994), whereas Mn2+ may enter the brain independently of such a transport mechanism (Murphy et al., 1991). Unlike ingested Mn, inhaled Mn is transported directly from the respiratory system to the vicinity of the brain before its first pass by the liver. Depending on the form of Mn inhaled, its conversion to other oxidation states (e.g., oxidation of Mn2+ to Mn3+ or reduction of Mn4+ to Mn3+), and its ability to enter the brain (through a protein transport mechanism or otherwise), it is quite possible that a significant fraction of even small amounts of inhaled Mn would be able to reach target sites in the CNS. Thus, the apparently greater toxicity of inhaled versus ingested Mn may reflect important pharmacodynamic and pharmacokinetic differences of Mn that enters the body by different routes. A more definitive understanding of these issues will require more empirical information. --------------------------------------------------------------------------- \56\Various elements can exist in more than one form of charged atom, depending on the number of negatively charged and positively charged particles contained in the atom. Manganese is one such element where, depending on the number of charged particles associated with the atom, the atom may have a net charge of two or three ``plus'' charges resulting in a ``divalent'' or ``trivalent'' form, respectively. --------------------------------------------------------------------------- 2. Earlier Assessments Earlier ORD health assessments have been based on the RfC, which is defined as an estimate (with uncertainty spanning about an order of magnitude) of a continuous inhalation exposure level for the human population (including sensitive subpopulations) that is likely to be without appreciable risk of deleterious noncancer effects during a lifetime. The basic procedure for derivation of an RfC entails identifying a no-observed-adverse- effect level (NOAEL) and a lowest- observed-adverse-effect level (LOAEL) from a ``principal'' study, generally defined as the available study that best defines the highest NOAEL or lowest LOAEL for the most sensitive endpoint affected by a chemical. When an investigation of occupationally exposed humans is the principal study (as in the case of the Mn RfC), the NOAEL or LOAEL is adjusted for differences in ventilation rates and exposure durations between the occupational exposure scenario (10 m\3\ air breathed per 8- h workday, 5 days/week) and the ``general public'' scenario (20 m\3\ air breathed per 24-h day, 7 days/week). The adjusted NOAEL or LOAEL is then divided by uncertainty factors and a modifying factor. In the case of the original (1990) RfC for Mn, uncertainty factors of 10 each were used for extrapolating from a healthy worker population to the general population (including sensitive subpopulations) and for extrapolating from a LOAEL to a NOAEL. Also, an uncertainty factor of 3 (approximately one-half of 10 on a log scale) was used for extrapolating from subchronic to chronic exposure. A modifying factor of 3 was used because of statements by the authors of the principal study (Roels et al., 1987) that past exposure levels of workers in the subject study were probably lower than those measured at the time the study was conducted. The resulting RfC of 0.4 g Mn/m\3\ was used for the earlier ORD risk assessment (U.S. Environmental Protection Agency, 1990) and was entered on EPA's IRIS computer database of human health risk and regulatory information in December 1990. 3. 1993 Revised RfC The original RfC for Mn was revised, in part, because newer information supplied in conjunction with the resubmittal of the MMT waiver application by Ethyl indicated that the workers' exposure levels in the principal study had probably not increased over time, and thus the modifying factor could be ``eliminated'' (i.e., set equal to 1). Another reason for revising the original RfC was that more recent studies (Roels et al., 1992; Mergler et al., 1994) provided additional evidence of health effects in workers at relatively low airborne concentrations of Mn. Independently of their earlier study of Mn-exposed workers (Roels et al., 1987), Roels et al. (1992) conducted a cross-sectional study of neurobehavioral and other endpoints in another group of workers from a different factory-namely, 92 male alkaline-battery plant workers exposed to manganese dioxide (MnO2) dust--who were compared to a matched control group of 101 male workers without industrial Mn exposure. The geometric mean occupational-lifetime integrated respirable dust concentration was 793 g Mn/m\3\ x years (range: 40 to 4,433). The equivalent value for total dust was 3,505 g Mn/m\3\ x years (range: 191 to 27,465). The authors noted that the monitored concentrations were representative of the usual exposures of the workers because work practices had not changed during the last 15 years of the plant's operation. No data on particle size or chemical purity were provided in the report by Roels et al. (1992), but based on information provided by Roels et al. (1992) and Roels (1993), the median cut point for the respirable dust fraction was 5 m aerodynamic diameter. The respirable fraction is more representative of the toxicologically significant particles (i.e., the smaller particles that are inhaled and deposit predominantly in the lower respiratory tract). Total dust measurements comprised the respirable dust as well as larger particles that deposit predominantly in the nose and throat region (via nasal breathing) and would be cleared more rapidly from the respiratory tract than the smaller particles retained in the lower regions. Therefore, the respirable dust measurements were considered to be a more accurate indicator of exposure in relation to the observed health effects. Manganese-exposed workers in the 1992 study by Roels et al. performed significantly worse than matched controls on several measures of neurobehavioral function, particularly visual reaction time, eye- hand coordination, and hand steadiness. Similar neurobehavioral impairments were also found in the earlier study by Roels et al. (1987) of a different occupational population exposed to mixed Mn oxides and salts at approximately the same levels of total dust (respirable dust was not measured). In addition, a recent study in Canada by Mergler et al. (1994) indicated that, among other effects, performance on tests of the ability to make rapid alternating hand movements, to maintain hand steadiness, and to perform other aspects of fine motor control was significantly worse, compared to matched controls, in workers who were exposed to even lower concentrations of respirable dust (35 g Mn/m\3\ at the time of the study). If Mergler et al. had included information on integrated past exposure levels (which they have since provided to ORD in a preliminary form not yet submitted for publication), their study would have provided a fivefold lower LOAEL for the derivation of the RfC. In addition, reports of a Swedish study of Mn-exposed steel workers (Iregren, 1990; Wennberg et al., 1991, 1992) provided compelling evidence of comparable neurobehavioral impairments, including slower reaction time and finger-tapping speed. The median total dust concentration in the Swedish study was 140 g Mn/m\3\, with respirable dust reported as constituting 20 to 80% of individual workers' total dust exposures. Thus, the LOAEL from this study would be somewhat lower than that from Roels et al. (1992), but the less fully characterized exposure histories in the Swedish study made it more appropriate as a supporting (rather than principal) study for deriving the Mn RfC. Taken together, the above epidemiological studies provide a consistent pattern of evidence indicating that neurotoxicity is associated with low-level occupational Mn exposure. The fact that speed and coordination of motor function are especially impaired is particularly noteworthy, given its consistency with other epidemiological, clinical, and experimental animal evidence of higher concentration Mn intoxication. Differences among these studies in the duration of workers' exposure to Mn raise another issue of relevance to this discussion. In the Roels et al. (1992) study, the mean period of exposure was 5.3 years (range: 0.2 to 17.7 years). In the other studies, the mean durations of exposure were longer: 7.1 years in Roels et al. (1987), 9.9 years in Iregren (1990), and 16.7 years in Mergler et al. (1994). The indications of lower LOAELs in the Canadian and Swedish studies suggest that neurobehavioral effects might occur at lower concentrations of Mn if the exposure periods were longer. In addition, the age of the workers may be an important factor in interpreting these findings. The oldest worker in the Roels et al. (1992) study was less than 50 years old; also, the average age in that study was only 31.3 years, versus 34.3 years in Roels et al. (1987), 43.4 years in Mergler et al. (1994), and 46.4 years in Iregren (1990). These points suggest that longer exposure and/or testing later in life might result in the detection of effects at lower concentrations than is possible after shorter periods of exposure and/or in younger workers. On the other hand, it is also evident from these studies that a much shorter period than a full lifetime of occupational Mn exposure may be sufficient to induce Mn neurotoxicity. As Roels et al. (1992) and other investigators have noted, a threshold for the neurotoxic effects of Mn has not been reported in the epidemiological literature. Therefore, instead of a NOAEL, a LOAEL was obtained from the study by Roels et al. (1992) by dividing the geometric mean integrated respirable dust concentration (793 g Mn/m3 x years) by the average period of worker exposure (5.3 years) to eliminate time (in years) from the time-weighted average, thereby yielding a LOAEL of 150 g Mn/m3. (The geometric mean concentration was used to represent the average exposure because the workers' exposure measurements were log-normally distributed, and the arithmetic mean exposure period was used because it was the only value reported by Roels et al. (1992).) The workplace-based LOAEL of 150 g Mn/m3 was then adjusted for nonoccupational lifetime exposure by multiplying it by (1) the quotient of 10 m3/ day divided by 20 m3/day (for worker versus nonworker ventilation rates) and (2) the quotient of 5 days divided by 7 days (for work week versus full week). The resulting adjusted LOAEL, labeled the human equivalent concentration (HEC), was 50 g Mn/m3, which was then divided by a total uncertainty factor of 1,000 to yield an RfC of 0.05 g/m3. The total uncertainty factor of 1,000 incorporated the following factors: 10 to protect sensitive individuals; 10 for using a LOAEL in lieu of a NOAEL; and a composite factor of 10 for database limitations reflecting the less-than-chronic periods of exposure and the lack of reproductive and developmental toxicity data, as well as potential but unquantified differences in the toxicity of different forms of Mn. A modifying factor was not used (i.e., it was set equal to 1). Each RfC is assigned an overall rating of low, medium, or high confidence level, based on two subsidiary confidence ratings reflecting the quality of the evidence from the principal studies and the quality of the overall database for the chemical in question, respectively. The revised Mn RfC was assigned a medium level of confidence. The evidence for the neurobehavioral effects of low-level Mn exposure by inhalation was compelling and consistent across several well-conducted studies. However, the limited duration of exposure and the lack of a NOAEL for neurotoxicity in any of the principal or supporting studies prevented assigning a confidence level greater than medium. Also, the lack of definitive data on the concentration-response relationship and on the potential reproductive and developmental toxicity of inhaled Mn limited the degree of confidence in the database to a medium rating. Virtually all of the human health evidence is based on healthy, adult male workers. No known studies have investigated human female reproductive function, and even though male worker reproductive function is known to be affected by Mn exposure, it has not received adequate investigation. The limited available information concerning the developmental toxicity of inhaled Mn suggests the possibility that prenatal exposure of laboratory rodents to MnO2 (via the air supplied to the pregnant mother) may depress neurobehavioral activity in neonatal rats and that continued postnatal exposure of the pups may intensify this depression. In addition, several studies have demonstrated alterations in neurochemical (dopamine) levels in young mice and rats exposed during early postnatal development to Mn via other routes. Thus, the potential for developmental toxicity due to Mn exposure exists. The concentrations and durations of exposure sufficient to induce such effects are not known. Although adequate epidemiological studies of children and the elderly have not been conducted, it is known that certain populations, such as children, pregnant women, elderly persons, iron- or calcium-deficient individuals, and individuals with liver impairment, may have an increased potential for excessive Mn body burdens due to increased absorption or altered clearance mechanisms. Another concern raised by the lack of studies involving longer periods of exposure and/or older subjects is that the compensatory or reserve capacity of certain neurological mechanisms may be stressed by Mn exposure earlier in life, with manifestations of impairments only becoming evident much later, perhaps at a geriatric stage. One reason for the latter concern is that Parkinson's disease is typically a geriatric disease in which symptoms are only seen when the loss of brain cells that produce dopamine (which is also apparently involved in Mn toxicity) reaches 80% or more. Indeed, some neurologists think that a long latency period of perhaps several decades may precede various parkinsonian syndromes. These points lead to a concern that if Mn reduces the compensatory or reserve capacity of the nervous system, parkinsonian-type effects might occur earlier in life than they would otherwise. Thus, several questions remain to be answered before higher confidence in the accuracy of the RfC can be achieved. The two studies of Roels et al. (1992, 1987) were considered coprincipal studies for the derivation of the revised RfC, with supporting evidence in the reports of Mergler et al. (1994), Iregren (1990), and Wennberg et al. (1991, 1992). Given the fact that these studies involved exposure to various oxides and salts of Mn, the RfC is designated as applying to Mn and Mn compounds (including Mn3O4). The previous RfC of 0.4 g Mn/m3 applied to Mn only, due to undifferentiated forms of Mn in the principal study. Given that different forms of metals may have different toxic properties (due to different oxidation states, different solubilities, and possibly other factors), it is likely that different compounds of Mn vary in toxicity. However, sufficient data on the comparative toxicity of various compounds of Mn are not available to judge the relative toxicity of Mn3O4 specifically. As noted above, Mn affects multiple organ systems, including the respiratory and reproductive systems as well as the CNS. However, because the only available evidence suggests that the CNS is the most sensitive target for Mn toxicity, neurobehavioral endpoints were the focus of the RfC derivation. Although other types of effects remain a concern, it is presumed, based on the limited data now available, that protecting against neurotoxicity provides protection against these other, apparently less sensitive endpoints. In revising the RfC for Mn, a draft version was subjected to peer review by external experts (from academic and non-EPA governmental institutions) as well as internal experts. Following this peer review, a further-revised version was submitted to and verified by an EPA-wide RfD/RfC work group in September 1993. The current RfC for Mn was made available through IRIS in early November 1993 through two mechanisms. A special notice beginning November 1 in the news section of EPA's internal IRIS2 database announced the availability of a hard copy of the text to EPA requesters who contacted the Risk Information Hotline; also, the text was obtainable through the National Library of Medicine's publicly accessible on-line computer database, TOXNET, beginning November 10, 1993. It [Text truncated at 120,000 characters. The full text is on the page linked above.] --- Source: Frix Law Library, https://www.frixlaw.com/law-library/documents/fr%3A94-18941. Public record. Not legal advice.