Health risk assessment of groundwater contaminated with methyl tertiary butyl ether (MTBE)

Methyl tertiary butyl ether (MTBE), a volatile oxygenate commonly used in f uels, is a frequent contaminant of some shallow groundwater. Based on limit ed reporting, concentrations of MTBE in drinking water were generally less than 10 mu g/L but excursions up to 770 mu g/L have been reported. Based on current MTBE toxicological data with emphasis on carcinogenic potential, a nd reproductive and developmental effects, a maximum drinking water level o f 100 mu g MTBE/L is suggested. This recommended advisory level takes into consideration the equivocal evidence of the carcinogenicity of MTBE in huma ns and low potency in an oral exposure animal study. Definitive conclusions regarding health risks to the general population from MTBE contamination o f drinking water are not possible due to a paucity of monitoring data. Ther e is increased evidence of contamination of storm water and shallow groundw ater from primarily, nonpoint sources. Considering MTBE mobility and stabil ity in water, movement to deep groundwater and drinking water supplies seem s probable. In light of projected increased MTBE use, there is a need for a more rigorous monitoring program to define the frequency of MTBE contamina tion of drinking water supplies and to develop risk management policies. (C ) 1999 IAWQ Published by Elsevier Science Ltd. All rights reserved.