The human health impact of MTBE has been extensively studied, with the first tests screening health risk conducted more than 30 years ago. MTBE has never been classified as toxic or carcinogenic by any regulatory body anywhere in the world.
There have been numerous toxicological studies of MTBE, none of which indicates that MTBE is a cause for concern. For example, the WHO International Programme on Chemical Safety (IPCS) says that “based on collective evidence, it appears unlikely that MTBE alone induces adverse acute health effects in the general population under common exposure conditions” (2005 WHO Guidelines on MTBE in drinking water).
ETBE, MTBE and TAME have been subjected to the EU risk assessment process to a greater or lesser extent. The Risk Assessment Reports for MTBE and TAME were published in the Official Journal of the European Union on 4 December 2001 and 21 June 2008, respectively. Whilst ETBE has been subject to a call for a reduced data set under Article 12 (2) of the Existing Substances Regulation (EEC No 793/93; Commission Regulation 1217/2002). The completed data set was reviewed by the EU Technical Committee on New and Existing Substances in November 2005. After these comprehensive reviews, the EU concluded that fuel ethers are unlikely to present a hazard to health or the environment under normal handling and use conditions.
Further reading: Fuel Ethers Risk Assessments