MTBE has been extensively studied and the consensus of opinion is that, when properly handled, MTBE blended gasoline is a safe product.

• The number and extent of scientific tests places MTBE within the top 2 percent of all tested substances.
• The first tests screening health risks were conducted in 1969 and 1972.
• As part of the US EPA´s approval for blending MTBE in unleaded gasoline in 1979, additional tests were conducted. They were followed by voluntary industry groups, who sponsored more extensive health studies on metabolism, reproductive function and subchronic inhalation exposure.
• In 1986, the industry established an extensive research programme under the US EPA’s oversight and guidelines. This programme was completed in 1992. All the results and reports were submitted to the US EPA.
• The industry has continued voluntary testing to supplement available environmental and toxicological information on MTBE.

Carcinogenicity

MTBE does not accumulate in the body. It does not have pathological effects, nor does it injure the developing offspring or impede reproductive functions. Its effects occur only at high doses not encountered by humans, and, despite extensive testing, there exists no scientific consensus on whether it can cause cancer in a manner relevant to humans.

In the US, the study into the impacts on public health have been substantial since the inception of cleaner burning gasolines. According to one study that modeled the risk of cancer (Spitzer, 1997), a 13% decline in cancer incidence is attributable to the blending of MTBE in summertime gasoline. A 20% reduction in cancer incidence is attributable to the blending of MTBE in wintertime gasoline.

Several independent bodies in Europe and the United States recently concluded that MTBE is not a human carcinogen.

• Health and Environment Canada's Priority Substance Assessment Program has concluded that the predicted concentrations of MTBE in the environment in Canada do not constitute a danger to the environment, or to the environment on which human life depends, or to human life or health. MTBE is not considered as 'toxic' according to the definition in Canadian legislation.
• The European Union Risk Assessment on MTBE concluded in December 2000 that MTBE is not a human carcinogen.
• The World Health Organization, International Agency for Research on Cancer, determined in November 1998 that MTBE is not classifiable as a human carcinogen.
• The US Department of Health & Human Services, National Toxicology Program voted in December 1998 not to list MTBE in its 9th "Report on Carcinogens".
• The US National Research Council concluded in September 1998 that there was little likelihood that humans would contract kidney tumors from exposure to MTBE.
• California's Science Advisory Board for Proposition 65, determined in December 1998 that MTBE could not be considered carcinogenic or a developmental or reproductive toxicant.
• NESCAUM, The Northeast States for Coordinated Air Use Management, in October 1998, determined that RFG with MTBE reduced cancer risk by 12% over the 1995-1999 period and anticipated this reduction to grow to 20% beginning in 2000.

Acute health effects from exposure to MTBE have also been considered and addressed in a number of studies.

In 1995, the World Health Organisation concluded that it is "unlikely that MTBE alone induces adverse acute health effects in the general population under common exposure conditions." The strong taste and odour of MTBE mean that, even at very low concentrations, its presence makes drinking water unpalatable. The US EPA has recommended an MTBE concentration in drinking water of 20 to 40 ppb or below. These levels preserve the palatability of drinking water and are 20,000 to 100,000 times lower than the lowest concentration that has caused observable health effects in animals.

If the use of MTBE is such an effective tool for improving fuel emissions as a low cost fuel component, then why are there calls for MTBE removal or reduction?

The history of clean fuels has, over the last few years, been predominantly linked with the use of oxygenates as part of vehicular emissions control, of which the major two components are MTBE and ethanol.

Both are effective tools. However, because constraints exist with the use of ethanol, not least in handling and transportation, among other factors, made MTBE use a more popular choice.

In 1998, it was found that MTBE contamination of underground water due to leaking storage tanks became a concern. However, instead of solving the problem of leaking fuel storage tanks, of which the US government had allocated a fund to rectify, MTBE was unfairly identified as the target component for removal.

In November 1998, US Environmental Protection Agency Administrator appointed a Blue Ribbon Panel to investigate air quality benefits/water quality concerns for gasoline oxygenates. The Panel:

• Agreed broadly, but not unanimously, that less MTBE should be used in reformulated gasoline (RFG).
• Urged removal of legal requirement for 2wt% oxygen in RFG.

Under the 1990 Clean Air Act Amendments, refiners were allowed to choose from a variety of oxygenates in order to meet the 2.0% oxygen requirement for RFG. Currently in the US, roughly 85% of RFG contains MTBE and roughly 15% contains ethanol. Since 1990, MTBE has emerged as the refiner's oxygenate of choice because of its ability to:

1. Extend the gasoline supply,
2. Provide a lead-free high octane blend stock,
3. Provide a sulfur-free high octane blend stock for low sulfur gasoline blending,
4. Help reduce future refinery capital expenditures,
5. Make gasoline cleaner by reducing tailpipe emissions,
6. Improve engine performance,
7. Fit into the refiner's existing logistical distribution system, and
8. Be readily available worldwide.

The 1990 Clean Air Act Amendments and an apparent refiner preference for MTBE have sparked considerable market competition between ethanol and MTBE. The ethanol industry has engaged in significant efforts to promote it as a substitute for MTBE. Yet today, MTBE continues to be the primary oxygenate in US gasoline.

In 1988, federal laws were passed to require most of the nation's gasoline storage tanks to be replaced, protected from corrosion, and monitored for leaks no later than December 31, 1998. Federal and state regulators have reported that many tanks did not meet the 1998 deadline. However, since 1998, states and US EPA have intensified efforts to identify and repair or replace leaking gasoline storage tanks.

Product leaks from faulty gasoline storage tanks have resulted in detections of gasoline constituents such as benzene and MTBE in surface and groundwater. MTBE detections have been unfairly blamed on its use in gasoline rather than faulty tank systems. During the last five years, several states including California and some Northeastern states have experienced problems with gasoline leaking from noncompliant gasoline tanks and have called for phase-outs of MTBE.

State actions and efforts by EPA and other regulators to address MTBE detections from gasoline leaks have incorrectly focused Congress on phasing-out MTBE rather than on correcting the problem of leaking gasoline. An example of this is the proposed phase-out of MTBE contained in the US Senate Energy bill currently being debated.

In comparison, the US House of Representatives passed a bill, H. R. 4, last summer that did not restrict MTBE's use in gasoline. Instead the bill focused on the real problem of gasoline leaking from faulty gasoline tanks and included authorization for funds to correct faulty systems and clean up gasoline spills.

A Note by John Kneiss (OFA)

“The current situation in the US can be characterized as follows: THE U.S. HAS NOT ENACTED A BAN ON THE BLENDING OF MTBE INTO MOTOR GASOLINE.

While various states have passed individual laws that preclude or limit MTBE use, most are in corn-belt areas, or inconsequential states that essentially do not have gasolines blended with MTBE.

Only three states with such legislation are of significance - California, New York and Connecticut - and none of the effective for these laws has come due. Importantly, the laws of California and New York are under challenge (OFA has sued them), and the cases are still pending and in progress.

Price and Supply Issues

The has been considerable retail petrol cost increases being experienced in California of late - despite the loud wailing by the fuel-ethanol industry that it's "not their fault", which the media, and probably most of the public is just not buying for now.

A large portion of the California refining industry in the state is transitioning to fuel-ethanol blending in CARB spec gasoline - and experiencing difficulties in meeting supply needs. Thus the substantial run-up in pricing under basic economic principles where continued strong demand is overwhelming perceived (and in some cases real) supply limitations.

From a consumption standpoint, based on U.S. government statistics (Dept. of Energy, Energy Information Administration), the use of MTBE remained quite strong throughout 2002, and even recent use (last couple of months) has shown typical seasonal use of MTBE

At this point, clearly the momentum is AGAINST any ban language becoming enacted - unfortunately, it is far too early to handicap or predict the outcome of federal legislation.”

At the same time the US MTBE ban is facing legal challenges making its application more complicated.

• Methanex, a Canadian methanol producer, invoked the North American Free Trade Agreement (NAFTA) against the US as a legal challenge on MTBE ban. The company seeks to overturn the California MTBE ban and claims US $ 970 million for compensating the ban would cause to its business.
• The US Oxygenated Fuels Association (OFA) is suing the State of California, arguing the MTBE ban violates US law. The OFA suit is based upon the fact that the federal Clean Air Act has established uniform requirements for gasoline that contradict California's MTBE ban. OFA is asking for complete scientific review of data.