Myths vs. Facts



Myth: MTBE is unsafe to use.
Fact: MTBE has been safely used across the world for more than four decades. 15 out of the 20 top gasoline-consuming countries use MTBE.  In fact, MTBE belongs to the 2% of most tested substances in the world. The human health impact of MTBE has been extensively studied for more than 30 years. Based on extensive study, MTBE has never been classified as carcinogenic by any regulatory body anywhere in the world. In addition to the extensive body of carcinogenicity research, there have been numerous toxicological studies, none of which indicates MTBE as a cause for concern. The weight of scientific evidence shows that MTBE has a low order of acute and sub‐acute toxicity; it is not teratogenic, mutagenic, neurotoxic nor is it a reproductive toxicant.

Authorities within the U.S. and the European Union (EU), as well as various international organizations such as the United Nations and the World Health Organization (WHO) have found no evidence to suggest that MTBE is harmful to health. Extensive study and deliberation have shown that under normal use conditions and with proper handling, adverse health effects are unlikely.


Myth: MTBE causes cancer.
Fact: Multiple studies have been conducted, and the result is that MTBE is not classifiable as a cancer risk to humans. The International Association of Research on Cancer (IARC), which is a part of the World Health Organization, has classified MTBE as a category 3 substance, which means that it is «not classifiable as to its carcinogenicity to humans». This means that there is not sufficient data to claim a possible cancer risk to humans from exposure to MTBE.

A number of other well‐respected organizations have reached similar conclusions.

  • The U.S. National Toxicology Program does not include MTBE as a material “reasonably anticipated to by a human carcinogen.
  • The European Centre for Eco-Toxicology and Toxicology of Chemicals (ECETOC) concluded that MTBE is not carcinogenic according to the criteria of the EU Dangerous Substances Directive 67/548/EC.
  • According to California Proposition 65, MTBE is not considered a carcinogenic or reproductive hazard.
  • The European Union «Working Group on the Classification and Labelling of Dangerous Substances» examined the status of MTBE in a meeting of the relevant Competent Authorities of the 15 Member States held in Ispra (Italy). This meeting of experts resulted in the European Union deciding that MTBE will not be classified as a carcinogen, mutagen or reproductive toxin.


Myth: Contact with MTBE should be a concern.
Fact: Even when contact with MTBE is possible through the refueling process, it does not present a health concern. Consumer contact with MTBE is possible when refueling cars with gasoline. The level of exposure is so low, however, that it does not constitute a probable health risk. The experience from more than 30 years of MTBE use demonstrates that vapor concentrations generated during car refuelling are not causing health effects and are far below the workplace threshold limits established for an eight hour working day where there is continuous handling of MTBE.


Myth:  MTBE has caused widespread contamination of groundwater.
Fact: Incidents of groundwater contamination are few and have been isolated to gasoline spills or leaks, which are preventable and not caused by the presence of MTBE in gasoline. Every country has a distinct set of geological conditions which influence the potential risk of exposure to materials that are transported underground. Gasoline , with or without MTBE, should not be allowed to contaminate groundwater or soil. Reasonable operating practices and regulation will prevent leaks and spills that could result in the contamination of soil and groundwater. In most countries, strict regulations exist to prevent gasoline leaks and spills, although these are not always properly enforced.   Importantly, no component of gasoline, including MTBE, is able to seep through properly designed, constructed, tested and maintained systems. Mexico, for example, has regulations to guarantee that gasoline is handled in double-hulled tanks. Instances of MTBE in groundwater that have occurred have been almost solely caused by inadequate requirements for underground fuel storage or inadequate monitoring and maintenance of the underground tanks.  This is an avoidable issue, which can be successfully resolved through co‐operation between the various stakeholders. Both U.S. and European experts have concluded that groundwater contamination by MTBE is not a widespread problem and that focusing on upgrading underground storage tanks is the best means of managing the issue.


Myth:  MTBE is not biodegradable?
Fact: Research has demonstrated that aerobic decomposition occurs in natural conditions. In many cases decomposition can be improved by aeration and nutrient and microbe augmentation.


Myth: Releases of MTBE in soil and water cause permanent damage.
Fact: MTBE releases can be cleaned up in the soil and water through an array of well‐proven methods such as air stripping, granular activated carbon (GAC), advanced oxidation, and soil vapor extraction (SVE). Traditional «pump and treat» technologies available for water plants have been proven effective in remediation of gasoline‐contaminated water, with or without MTBE. Activated carbon filtration can can also be used. These household filters have been commonly used for many years by consumers to remove off‐taste and odor from drinking water, and the devices work well for gasoline components, including MTBE.


Myth: MTBE leaks can go undetected and pose a threat to drinking water.
Fact: Should it reach drinking water, the presence of MTBE would quickly attract public attention to a gasoline leak because, like all ethers, it has a strong taste and odor, and is easily detectable at very low levels of concentration. Drinking water containing small quantities of MTBE does not cause any adverse health effects.

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