Background and methodology

The aim of this investigation is to 1) conduct an evaluation of the peer-reviewed literature on the human health and environmental effects of MTBE, substitutes for MTBE, combustion products of MTBE and products of biotransformation, 2) conduct a literature survey on whether the incidence of asthma has changed as a result of the introduction of MTBE in California. To date, we have assembled a team of faculty and students to carry out the studies, and we have contacted all Federal and California Agencies which may either be conducting research on MTBE and its substitutes or sponsoring research. In contacting Agencies we have sought to determine the scope of activities underway in the U.S. on MTBE. These Agencies include U.S. EPA, National Institute of Environmental Health Sciences (NIEHS), Centers for Disease Control and Prevention (CDC), including the Agency for Toxic Substances and Disease Registry (ATSDR), and the Office of Environmental Health Hazard Assessment (OEHHA) of California EPA. We have also pursued information from the Oxygenated Fuels Association, ARCO, Health Effects Institute (HEI), Chemical Industry Institute of Toxicology (CIIT), Professor Cesare Maltoni, Dr. Myron Mehlman, and Dr. Peter Joseph (University of Pennsylvania). We have begun to contact international agencies to determine regulatory and research activities relating to MTBE. The UCLA team has been in contact with Dr. Cathy Koshland and her staff. Dr. Koshland is responsible for #9, Identification and quantification of all of the combustion byproducts of MTBE in California's reformulated oxygenated fuel. Dr. Koshland's staff has provided us with a list of incomplete reaction and combustion products of MTBE, and we are currently conducting literature reviews on the health effects and toxicity of the products. We intend to carry out similar reviews on the products of combustion of the substitutes where data exist. Since ethanol is an important substitute compound being used in other states, we shall devote attention to this specific substance. We need to determine which combustion products are produced in greatest amounts since there are a large number of chemical agents. U.S. EPA has supplied UCLA with a list on ongoing research relating to oxygenates in water. This list of projects is an appendix to the U.S. EPA document entitled "Research Strategy for Oxygenates in Water" which has not been released to date. It is anticipated that it will be released for external review and comment soon. UCLA has obtained recently completed review documents on MTBE including the Interagency Assessment of Oxygenated Fuels from the National Science and Technology Council (June 1997) and an OEHHA document entitled "Public Health Goal for Methyl Tertiary Butyl Ether (MTBE) in Drinking Water" (April 1998). These reviews supplement the earlier documents from HEI, the NRC, the National Science and Technology Council, U.S. EPA and ATSDR. With respect to asthma, Drs. John Peters and Rob McConnell of the University of Southern California (USC) have been conducting a feasibility study to determine if MTBE monitoring data can be used in combination with information on asthma incidence collected in the ARB supported childrens health study being conducted in southern California by USC. It appears unlikely the two sets of data can be usefully combined at this point, but other research approaches are under discussion. This work will more likely lead to research recommendations for future research. The USC team is evaluating information obtained from Professor Peter Joseph of the University of Pennsylvania on asthma incidence in other cities to assess the validity of the studies. UCLA intends to contact Dr. Henry Anderson of the State of Wisconsin to determine if additional information on short term acute respiratory effects or asthma are available in Wisconsin. We have determined there is little research on the health effects of MTBE, its substitutes and combustion products underway in the U.S. The principal research ongoing is being conducted at CIIT and focuses on the toxicokinetics of MTBE and the male rat kidney tumors. We do not have information yet on international efforts, but we are aware that Health Canada has recently produced a document on MTBE. We have not obtained the document yet. We do not anticipate new research becoming available during the timeframe of this study which will provide significantly different information than that currently in the literature. The principal health effects issues continue to be 1) taste and odor, 2) short term acute respiratory and related effects, and 3) cancer. Our preliminary work casts some doubt on the significance of acute effects. The information on neurologic, developmental, reproductive, genotoxicity, and other organ toxicity remains limited. Data on asthma has similar limitations. The combustion byproducts may be relevant to an overall assessment of toxicity but that is dependent on the concentrations of the byproducts produced. Additional research on biotransformation products would be of use, but there is little evidence to indicate the research is being pursued. Combustion byproducts and biotransformation products will require further investigation. In the health effects area there have been a considerable number of secondary reviews on the health effects of MTBE of high quality. We think it is important to discuss the form of the final reports prepared for the Legislature at this workshop to ensure investigators provide the necessary information in a form useful for decisionmaking.