Environ. Sci. Technol. 2002, 36, 125-129
MTBE Ambient Water Quality Criteria Development: A Public/Private Partnership E . R . M A N C I N I , * ,† A . S T E E N , ‡ G. A. RAUSINA,§ D. C. L. WONG,| W. R. ARNOLD,⊥ F. E. GOSTOMSKI,# T. DAVIES,# J. R. HOCKETT,∇ W. A. STUBBLEFIELD,∇ K. R. DROTTAR,O T. A. SPRINGER,O AND P. ERRICO4 ARCO, 333 South Hope Street, Los Angeles, California 90071, American Petroleum Institute, 1220 L Street, NW, Washington, D.C. 20005-4070, Chevron, 100 Chevron Way, Richmond, California 94802-0627, Equilon, Shell Westhollow Technology Center, P.O. Box 1380, Houston, Texas 77251, Exxon Biomedical Sciences, 1545 Route 22E, P.O. Box 971, Annandale, New Jersey 08801-0971, U.S. Environmental Protection Agency, Office of Water, 1200 Pennsylvania Avenue, Washington, D.C. 20460, ENSR Corporation, 4303 West Laporte Avenue, Ft. Collins, Colorado 80521, Wildlife International, Ltd., 8598 Commerce Drive, Easton, Maryland 21601, and Qualtech, Inc., P.O. Box 666, New Market, Maryland 21774
A public/private partnership was established in 1997, under the administrative oversight of the American Petroleum Institute (API), to develop aquatic toxicity data sufficient to calculate ambient water quality criteria for methyl tertiary-butyl ether (MTBE), a gasoline oxygenate. The MTBE Water Quality Criteria Work Group consisted of representatives from private companies, trade associations, and USEPA. Funding was provided by the private entities, while aquatic biological/toxicological expertise was provided by industry and USEPA scientists. This public/private partnership constituted a nonadversarial, cost-effective, and efficient process for generating the toxicity data necessary for deriving freshwater and marine ambient water quality criteria. Existing aquatic toxicity data were evaluated for acceptability, consistent with USEPA guidance, and nineteen freshwater and marine tests were conducted by commercial laboratories as part of this effort to satisfy the federal criteria database requirements. Definitive test data were developed and reported under the oversight of industry study monitors and Good Laboratory Practice standards auditors, and with USEPA scientists participating in advisory and critical review roles. Calculated, preliminary freshwater criteria for acute (Criterion Maximum Concentration) and chronic (Criterion Continuous Concentration) exposure effect protection are 151 and 51 mg MTBE/L, respectively. Calculated, preliminary marine criteria for acute * Corresponding author phone: 805-987-7152; fax: 805-987-6423; e-mail:
[email protected]. † ARCO, Los Angeles, CA. ‡ American Petroleum Institute, Washington, D.C. § Chevron, Richmond, CA. | Equilon, Houston, TX. ⊥ Exxon, E. Millstone, NJ. # U. S. Environmental Protection Agency, Washington, D.C. ∇ ENSR Corporation, Ft. Collins, CO. O Wildlife International, Ltd., Easton, MD. 4 Qualtech, Inc., New Market, MD. 10.1021/es002059b CCC: $22.00 Published on Web 12/14/2001
2002 American Chemical Society
and chronic exposure effect protection are 53 and 18 mg MTBE/L, respectively. These criteria values may be used for surface water quality management purposes, and they indicate that ambient MTBE concentrations documented in U. S. surface waters to date do not constitute a risk to aquatic organisms.
Introduction Methyl tertiary-butyl ether (MTBE; CAS no. 1634-04-4) is a low-molecular-weight, alkyl ether that has been used as an octane enhancer and/or oxygenate in various gasoline formulations for more than twenty years. Since 1990, when the Clean Air Act specified the use of oxygenated compounds to increase automobile combustion efficiency in certain regions of the United States, it has become one of the largest volume and most widely distributed chemicals in the country. In 1995, the U.S. Geological Survey reported that MTBE had been detected in shallow urban groundwater, generally at low concentrations (unitary to 10s µg/L) but at elevated frequencies compared to those of many other monitored analytes in the National Water-Quality Assessment (NAWQA) program (1, 2). These and subsequent findings precipitated significant debate, enhanced and new scientific and engineering research, numerous conferences and symposia, several expert panel reviews, and countless media reports, as well as state and federal political machinations. The prevailing research foci, after the USGS reports, were the determination of MTBE’s impact on human health and the quality of our Nation’s drinking water, as well as the distribution and concentration of MTBE in surface and groundwaters. Surface water and groundwater monitoring data indicated that MTBE could occur at low µg/L concentrations in areas where oxygenated gasolines were used even when such occurrences appeared to be unrelated to storage or distribution facility releases. Reports of MTBE in freshwater lakes and reservoirs indicated that detected MTBE concentrations ranged from
