Mtbe & the environment

MTBE Frequently Asked Questions
What is MTBE ?
MTBE (methyl tertiary butyl ether) is a chemical compound that is manufactured by the
chemical reaction of methanol and isobutylene. MTBE is an "oxygenate", i.e. a component
that contains oxygen. Oxygenates are used widely as a component of unleaded gasoline.
MTBE is the most commonly used fuel oxygenate. It can be blended with petrol in any
proportion up to 15%.
Thanks to its adequate properties, MTBE is used as an "octane enhancer" to achieve the
required octane level of gasoline. MTBE is a good alternative to other typical gasoline
components.
Why use MTBE ?
MTBE has many properties that make it a good gasoline component for technical and
environmental reasons:
• MTBE can be used as fuel that can supplement the supply of gasoline components. • Its high octane rating makes it an ideal substitute for other octane components, e.g. • It is an oxygenate, which can be used in the formulation of cleaner-burning gasoline.
Lead has traditionally been added to gasoline due to its high octane rating, which prevents
engine "knock". Lead is, however, a toxic compound, and leaded gasoline has been phased
out in most areas of the world, including Europe. MTBE, which has a very high octane
number but is not toxic, is ideally suited to produce high octane, unleaded gasoline.
Adding oxygen to gasoline allows more complete combustion of the fuel, and this reduces
exhaust emissions of CO (carbon monoxide). Furthermore, when used as part of the gasoline
formulation, MTBE leads to a reduction in emissions of exhaust pollutants such as VOCs
(volatile organic compounds), NOx (nitrogen oxides) and PM (particulates). Reducing these
pollutants improves air quality.
By reducing the Ozone Forming Potential (OFP) of volatile organic compounds, MTBE
performs significantly better than other octane blending components. It generates about half
of the ozone when compared to iso/alkylates and one-tenth that of aromatics.
For all these reasons MTBE has been widely used all over the world
for the last 20 years.

Is MTBE used in Europe ?
MTBE was invented in Europe, and has been widely used for over 20 years as a safe and
clean octane enhancer, substituting lead.
Because of its properties, MTBE is a good alternative to other typical gasoline components,
leading to a reduction in the emissions of regulated as well as unregulated pollutants. In the
1990's some European countries - e.g. Finland - found these properties beneficial for the
environment and decided to add up to 9-13 % of MTBE in gasoline. CO emissions were
reduced by 10-20% and hydrocarbons by 5-10%.
As air quality became a real issue in Europe, the EU adopted a directive setting new
specifications for gasoline (EC Directive 98/70/EC). Oxygenated compounds such as MTBE
will help the refining industry reach these new, stringent standards, so that Europe can enjoy
better air quality.
Is MTBE used in the USA ?
In the USA, MTBE is used as an octane-enhancer and as the oxygenate of choice of the
refining industry, following the implementation of the federal Clean Air Act and other state
regulations.
In 1990 the United States adopted the Clean Air Act Amendments (CAAA). These require the
use of oxygen in gasoline in areas with unhealthy levels of air pollution. The CAA does not
specifically require MTBE, just oxygen. Although refiners may choose to use other oxygen-
containing components, such as ethanol, MTBE is the most widely used oxygenate.

The Clean Air Act sets out two types of gasoline specifications:
Winter Oxyfuel Programme: Implemented since 1992, this requires the se of oxygenated fuel
(gasoline containing 2.7 percent oxygen by weight) during the cold months in cities that have
elevated levels of carbon monoxide. Ethanol is primarily used as an oxygenate for this type of
gasoline, as the cold weather compensates for the usual drawback presented by its high
volatility.
Year-round Reformulated Gasoline Programme: Since 1995, the CAA requires reformulated
gasoline (RFG) year-round in cities with the worst ground-level ozone (smog). RFG is
gasoline with very tight environmental specifications, which must among other ingredients
contain a minimum of 2 percent oxygen by weight, and which is specially blended to have
fewer polluting compounds than conventional gasoline. Today, about 30 percent of US
gasoline is reformulated, of which about 87 percent contains MTBE. Refiners have chosen
MTBE as the main oxygenate in RFG in cities outside of the Midwest primarily for economic
reasons and because of its blending characteristics. Unlike ethanol, MTBE can be shipped
through existing pipelines, and its volatility is lower, making it easier to meet the emission
standards.
Further to the federal Clean Air Act, and to address its unique air pollution problems,
California has adopted similar, but more stringent requirements for its gasoline (California
RFG). In view of widely-publicised, although limited, occurrences of groundwater
contamination, California has decided to phase out MTBE from gasoline from 2004.
Implementation of this proposed legislation is uncertain and in fact California still relies on
MTBE as its source of oxygen in gasoline, given the economic and environmental advantages
that it brings.

Are there any alternatives to MTBE ?
Potential alternatives to MTBE include oxygenates such as alcohols or other ethers,
aromatics and fuel components such as alkylates and isomerates. Oxygenates are produced
from a variety of feedstocks. Methanol, derived primarily from natural gas, is one feedstock
used in the production of MTBE. Ethanol, another oxygenate, is derived primarily by a
fermenting process from corn and other agricultural products and is used directly as an
additive or as a feedstock for the production of ETBE.
When Europe started to phase down lead octane additives in petrol in the 1980s, many
refiners usually replaced them with aromatics, which represented the lowest-cost alternative
at the time.
Towards the end of the 1990s, new environmental regulations started to limit the aromatic
content of gasoline. A convenient replacement for aromatics is MTBE, a high octane, easy-to-
blend, reasonable cost oxygenate, which is essentially a drop-in blending component for the
refiner.
There are a few other non-aromatic octane options such as alkylates, isomerates and
ethanol, but they are very limited in terms of both octane contribution and supply availability.
In addition, they provide fewer air quality benefits. Each of the various octane alternatives has
advantages and disadvantages in numerous related aspects, which need to be considered in
an objective comparison. These include octane contribution, supply availability, cost, and
environmental impact.
Of all the options for replacing lead and aromatics in petrol, MTBE is the most effective from
both octane supply and air quality perspectives.

What about ethanol ?
The car industry and the oil industry do not want to use ethanol for technical reasons. It is a
fact that they consider MTBE to be a far better compound than ethanol: this is documented for
instance in the World Wide Fuel Charter developed by all the world car maker associations.
Concerning the environmental impact of ethanol, the Danish EPA recently mentioned that use
of ethanol could cause a remarkable increase (50-70%) in the release of acetaldehyde, which
is classified as a respiratory irritant in the EU and is categorised as a possible human
carcinogen by WHO (IARC Group 2B). Adding ethanol to gasoline will also increase the
volatility of the gasoline and thereby cause an increase in the emission of volatile organic
compounds (VOCs). Technically and environmentally, MTBE is a far better compound than
ethanol.
What are the air quality benefits of using MTBE in gasoline ?

Adding MTBE to gasoline allows a more complete combustion of the fuel, reducing the
exhaust emissions of toxic compounds:
• Carbon monoxide emission is reduced on average by at least the same percentage • Unburned hydrocarbons: for each 1 or 2 % of MTBE, there is a 1 % reduction in total • Particulate matter: it is estimated that each 1 % of MTBE results in a 2 to 3 % PM • Ozone: MTBE generates about half the ozone compared with iso/alkylates and one- • Benzene: it is estimated that for each 1 % of MTBE there is an equivalent percentage reduction in benzene emission, both evaporative and exhaust. • Olefins: MTBE displays low vapour pressure and low volatility compared to olefins. • Lead: MTBE is an effective substitute for lead, a toxic compound that has been
What are the results in the USA of reformulated gasoline (RFG) that contains
oxygenates ?

RFG has been helping improve the air for millions of Americans since 1995. The use of RFG
compared to conventional gasoline has resulted in annual reductions of smog-forming
pollutants (volatile organic compounds and nitrogen oxides) and toxics (such as benzene).
With the second phase of the RFG programme, which began in January 2000, the US
Environmental Protection Agency estimates that smog-forming pollutants are being reduced
annually by at least 105,000 tonnes, and toxics by at least 24,000 tonnes. Refiners are
required to reduce the emissions of volatile organic compounds, toxics, and nitrogen oxides
by 27, 22, and 7 percent, respectively, compared to the conventional gasoline they produced
in 1990.
An independent study by the University of California at Berkeley found a decrease in motor
vehicle emissions following cleaner-burning gasoline's introduction in the spring of 1996.
Analyses of weather data and air pollution levels also indicate that the use of cleaner-burning
gasoline has reduced peak smog levels. Benzene levels in California's air decreased by
approximately 50 percent in 1996 following the gasoline's introduction.
What would be the consequences for air quality if MTBE were not used any more ?

Without MTBE, real world air quality could easily worsen. High olefins concentration is just
one example. To produce MTBE, refiners convert C4 olefins, making good environmental use
of that reactive components, which would otherwise have to be converted to isomerates or
alkylates before being blended in the gasoline pool.
Both in the USA and in Europe, MTBE has been found in a number of groundwater areas and
in the soil under several gasoline stations. What is happening ?
Gasoline does not belong in the soil or in the groundwater: it belongs in storage tanks, or in
the tanks of cars. If gasoline is found in the soil or groundwater, it is because tanks, pipelines
or equipment are leaking. The oxygenated fuel industry is very much concerned about leaks
and spills, and recognises the need for dealing with this matter.
How real is the contamination of groundwater ?

It is very important to put matters in perspective. Despite media and political hype, the real
extent of groundwater contamination with gasoline containing MTBE is very limited, even in
California, where the authorities have nevertheless proposed to phase out MTBE.
In California, the most recent data published (May 2000) by the Department of Health
Services show that of all public drinking water systems sampled (1763), which serve 29.9
million people, or 88 % of the population, only 1.9 % had detectable levels of MTBE over the
taste and odour threshold . Even as the absolute number of water wells sampled increased,
the MTBE concentrations detected were fairly low (less than 10 ppb on average), and the
percentage of systems impacted remained remarkably stable over the last five years.
Contrary to popular perception, the situation is not getting worse: MTBE was for instance
generally detected in only one or two consecutive years, in drinking water sources sampled
for three to five consecutive years.
In Denmark, the only European country claiming to be impacted by groundwater
contamination, the level of occurrence of MTBE contamination is more comparable with other
European countries (e.g. the UK, Germany, Finland, the Netherlands) than with the United
States. The remediation sites identified by the Danish authorities are by definition old retail
sites, equipped with traditional equipment and technology.
How does Europe compare to the USA ?

The American situation is unique and it cannot be assumed that groundwater problems
experienced in the United States will automatically be repeated in Europe. A direct
comparison between the US and EU situations is not justified because of essential
differences in economic structure, technical equipment and aquifers. Specifically, the major
differences are:
• In the USA, detection tolerances mean that a spill of up to 5 gallons of gasoline per tank, per day (18.9 litres/tank/day) is possible at service stations. A leak of that amount would not be tolerated in Europe. • In the USA, high volume delivery is achieved by pumping gasoline under pressure from the storage tank to the dispenser unit. In the EU, gasoline is usually "sucked" from the storage tank. The whole of the dispensing system is not pressurised, making extensive leaks much less likely. • Gasoline is considerably cheaper in the USA, essentially because of the very low level of taxation. In addition to environmental concerns, Europeans have a strong economic incentive to prevent leakage, because of higher taxes on gasoline in the EU. • In the USA, important economic interests in favour of alternative octane enhancers, such as ethanol, are driving the campaign against MTBE.
Some people are saying that MTBE moves fast in soil and degrades very slowly in
natural conditions. Are they right ?

In certain hydrogeological conditions, MTBE moves faster through the soil than other gasoline
components. However, every compound in gasoline can end up in drinking water supplies, if
tanks leak. Not using MTBE does not solve the problem of leaking tanks, and of other
compounds that also risk ending up in drinking water supplies.
In some ways, the mobility of MTBE can be seen as an advantage. MTBE's strong taste and
odour are easily detectable. Even in minute quantities, its presence will deter people from
drinking water contaminated with gasoline, thus acting as an early warning signal. When
MTBE is not used, gasoline could enter the drinking water system unnoticed for some time.
MTBE does degrade slowly in natural conditions, eventually forming carbon dioxide and
water. The process can be speeded up by oxygen feed, nutrients and microbe augmentation.
Would it not be safer just to phase out MTBE ?

Phasing out MTBE would not solve the problem of leaking tanks. There is no justification for
attributing the issue of leakage solely to MTBE, while ignoring other gasoline components.
Besides, phasing out MTBE is not that easy. The situation in California shows how difficult it
is. Although California has decided to phase out the use of MTBE by 2003, the state actually
uses more MTBE now than when it decided on the ban. This is because MTBE is a
compound with a lot of technical advantages, which helps produce a cleaner-burning
gasoline.
How easily biodegradable is MTBE ?

It is often alleged that MTBE is a persistent substance in soil and groundwater, yet research
has demonstrated that aerobic decomposition occurs in natural conditions. Anaerobic
decomposition of MTBE is slower, but in many cases the situation can be readily improved by
oxygen feed, nutrients and microbe augmentation.
Can releases of MTBE in soil and water be cleaned up ?

Yes, MTBE contamination can be cleaned up in the soil and water by using a large array of
well-proven remediation technologies such as air stripping, granular activated carbon (GAC),
advanced oxidation, and soil vapour extraction (SVE).
Traditional "pump and treat" technologies available for water plants have been proven
effective in remediation of gasoline-contaminated water, even if it contains MTBE. In the
event of a contamination incident, activated carbon cartridges installed at the tap could be
utilised as a temporary solution. These household filters have been commonly used for many
years by private consumers to remove off-taste and odour from drinking water, and the
devices work well for gasoline components, including MTBE. No matter what method is used,
the key issue in groundwater remediation is immediate action to eliminate the contamination
source, usually a piece of leaking equipment or contaminated soil.
Nevertheless, gasoline does not belong in soil or groundwater, with or without MTBE. The
problem must - and can - be solved by cool-headed and sensible co-operation between the oil
companies and the authorities. The steps that need to be taken include:
• eliminating past contamination on a risk-based assessment basis, using proven • upgrading retail sites to high environmental standards; • developing responsible attitudes and practices to prevent further contamination due to technical systems and operational failures; • minimising the impact of accidental releases by immediate intervention.
Again, the problem of MTBE in groundwater is not inherent to the product itself, but has
arisen from the way the product has been handled.
What are the consequences of car pollution on human health ?

Numerous studies and reports have been undertaken in Europe and in the USA to determine
the impact of car emissions on human health. The results are alarming. In Europe, the 1999
WHO report on Health costs due to road traffic-related air pollution revealed that car-related
pollution kills more people than car accidents in the three European countries where the study
took place (Austria, France, Switzerland). The main findings of this report were:
• long-term exposure to air pollution from cars in adults over 30 years of age caused an extra 21,000 premature deaths per year from respiratory or heart disease. This is more than the total annual deaths from road traffic accidents in the countries studied (9,900) • each year air pollution from cars causes 300,000 extra cases of bronchitis in children, plus 15,000 hospital admissions for heart disease, 395,000 asthma attacks in adults and 162,000 attacks in children
To address this issue, further improvements in vehicle technology, traffic management
schemes, better public transportation and vehicle inspection programmes are all possible
long-term solutions. One of the simplest, quickest and most cost-effective ways to produce
cleaner air is to use cleaner fuel, as has been demonstrated by the experience of clean-air
programmes in North America and Europe.
Is MTBE safe ?

The human health impact of MTBE has been extensively studied, with the first tests screening
health risk conducted over 30 years ago. Based on all the available evidence, MTBE has
never been classified as carcinogenic by any regulatory body anywhere in the world.
In addition to research on the possible carcinogenicity of MTBE, there have been numerous
toxicological studies. 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. 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."
Does MTBE cause cancer ?

No. In 1998 the International Association of Research on Cancer (IARC), which is a part of
the World Health Organisation, classified MTBE in category 3. The scale is from 1 to 4. A
substance in Group 3 is "not classifiable as to its carcinogenicity to humans". This means that
there is not sufficient data to claim a possible cancer risk to man from exposure to MTBE.
N.B : IARC classifies all substances it examines in four different categories:
Group 1: Substances that are human carcinogens (e.g. asbestos, benzene, and alcoholic
beverages)
Groups 2A/2B: Products in these groups are probably/possibly carcinogenic to humans (e.g.
PCBs, hypochlorite salts)
Group 3: A substance in this group is "not classifiable as to its carcinogenicity to humans".
MTBE belongs to this group, as well as caffeine, nylon and talcum powder, for instance.
Group 4: This category groups products that are 'probably not' carcinogenic to humans.
Today there is only one substance belonging to this group, caprolactam.
A number of other well-respected organisations have reached a similar conclusion. The US
National Toxicology Program does not include MTBE as a material "reasonably anticipated to
be a human carcinogen." According to California Proposition 65, MTBE is not considered as a
carcinogenic or reproductive hazard. The European Centre for Eco Toxicology and
Toxicology of Chemicals (ECETOC) says that MTBE is not carcinogenic according to criteria
in the EU Dangerous Substances Directive 67/548/EC.
Very recently, in November 2000, 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
What happens if someone drinks water containing MTBE ?

Drinking water containing small quantities of MTBE does not cause any adverse health
effects. In any case, should it reach drinking water, MTBE would quickly attract public
attention to a gasoline leak because, like all ethers, it has a strong taste and odour, and is
detectable at very low levels of concentration. In view of this, the US EPA has recommended
an MTBE concentration in drinking water within the range of 20 to 40 ppb or below. These
quantities are 20,000 to 100,000 times lower than the lowest concentration that has caused
observable health effects in animals, thus ensuring not only consumer acceptance, but also
an exceptionally large margin of safety from any possible toxic effects.
Still, should the precautionary principle not dictate that MTBE be phased out from gasoline?
The Precautionary Principle is a cornerstone for the development of environmental policies in
the European Union. EFOA recognises the Principle as an excellent framework for decision-
making on solid scientific grounds.
The Precautionary Principle should be applied when there is "sufficient likelihood" that serious
or irreversible damage to health or the environment would occur. This is completely in line
with the Principle as stated in the Rio Declaration, which calls for a science-based approach
with control measures that are commensurate with the defined risk.
A prerequisite for the application of the Precautionary Principle is a scientific risk assessment,
identifying the degree of scientific knowledge on the issue in question, possible uncertainties,
risk acceptability and risk reduction measures. In the EU, this is a strictly defined and
comprehensive process, which will result in regulations that are proportionate to the
environmental objectives to be achieved, and will provide a balanced approach to regulation.
The Risk Assessment Report is finalised and was published in the Official Journal of the
European Union on 4th December 2001. It is the most appropriate instrument that will enable
the European Union to determine the best course of action concerning the continued usage of
MTBE in the EU.
To this end, EFOA concurs with the European Commission and other authorities that the Risk
Assessment Report constitutes the objective and scientific basis on which any further
regulation on MTBE might be considered.

Source: http://www.acfa.org.sg/pdf/MTBE%20FAQs.pdf