MTBE: WHO Guidelines and Taste and Odour Issues for Drinking Water

Abstract

The World Health Organization (WHO) Guidelines for drinking water quality are one of the most important sources of advice on the safety and acceptability of drinking water around the world. They are used as the basis for standards in a substantial part of the world and are respected for their independence and transparency. WHO bases its evaluations on international peer-reviewed evaluations where possible, but will also use peer-reviewed documents prepared by member states. In the case of methyl tert-butyl ether (MTBE), several such documents exist that provide the basis for an international consensus on the science surrounding water contamination by MTBE. The toxicology of MTBE indicates that while it induces tumours in rodents, there is doubt as to the significance to humans and the mechanism appears to be a high-dose, non-genotoxic phenomenon. MTBE can be detected in water by taste and odour at low concentrations. WHO considered that it was unnecessary to set a health-based guideline value, since any such value would be substantially above the concentration at which MTBE could be detected by taste and odour.