2.0 Background

• 2.1 Nature and cause of problem
• 2.2 Responses to the problem by other jurisdictions - actions to prevent contamination
• 2.3 Responses to the problem by other jurisdictions - water quality guidelines for MTBE
• 2.4 Canadian situation - what was known prior to the CEPA 1999 Information Gathering Notice

MTBE is a synthetic organic compound known as an oxygenate. It may be used in gasoline to improve gasoline octane and also because it reduces vehicle emissions. (Oxygenates are a required component in U.S. reformulated gasoline for the latter reason.) MTBE has a higher solubility in water and a slower rate of degradation than many other components of gasoline. As well, MTBE has a low taste and odour threshold. Because of its strong turpentine-like taste, MTBE can render water undrinkable at concentrations as low as 15-20 parts per billion (ppb).

Releases of gasoline containing MTBE from gasoline storage tank systems have contributed to significant drinking water contamination problems in some jurisdictions during the last decade, particularly in the U.S. In 2001, the U.S. Geological Survey (USGS) reported that MTBE was detected in approximately 5 percent of ground water samples across the U.S. However, less that one percent of the samples exceeded the EPA consumer advisory concentration of 20 micrograms per litre (approximately equal to 20 ppb). As well, MTBE was detected in nine percent of community water systems in twelve North East and mid-Atlantic states looked at by the USGS. Again, less than one percent of the samples exceeded the EPA consumer advisory concentration³. While remediation of contaminated drinking water is feasible, it is often difficult and expensive.

The health and environmental effects of MTBE were assessed by the federal government under CEPA 1999 as part of the first Priority Substance Assessment process. Based on the level of use at the time, the 1992 Assessment report on MTBE concluded that, "the predicted concentrations of MTBE in the environment in Canada do not constitute a danger to the environment orto human life or health"⁴. As a result, MTBE was found not to be "toxic" as defined in the Canadian Environmental Protection Act.

Assessments by other agencies have examined the health risk of MTBE more recently:

• In 1997, the U.S. Interagency Assessment of Oxygenated Fuels released by the White House National Science and Technology Council indicated that, "While there are no studies on the carcinogenicity of MTBE in humans, MTBE should be regarded as posing a potential carcinogenic risk to humans based on animal cancer data" ⁵.
• In 1998, the World Health Organization's International Programme on Chemical Safety published a report on MTBE which concluded that, "MTBE is not genotoxic but has induced tumours in rodents primarily at high concentrations" and that "data are considered currently inadequate for use in human carcinogenic risk assessment"⁶.
• In its March 2000 Advance Notice of Proposed Rulemaking to control MTBE in gasoline, the EPA stated, "low levels of MTBE can make drinking water supplies undrinkable due to its offensive taste and odor. At higher levels, it may also pose a risk to human health".

MTBE contamination of ground water has become an issue of serious concern in the U.S., where use of MTBE or other oxygenates has been required in reformulated gasoline since 1993. MTBE has been the refiners' oxygenate of choice in the U.S. and in 1998 was present in 87% of the U.S. reformulated gasoline pool at levels of 10% to 15% by volume, amounting to an average MTBE concentration across the U.S. gasoline pool of approximately 3%.

One of the best known examples of drinking water contamination with MTBE is in Santa Monica, California. In 1996, seven wells in Santa Monica providing 50% of the city's drinking water supply were found to be contaminated at levels up to 600 ppb⁷. Releases of gasoline from underground storage tanks were identified as the cause.

In March 1999, California Governor Gray Davis announced that MTBE would be phased out "at the earliest date, but not later than December 31, 2002". In December 1999, California approved its Phase 3 gasoline regulations banning the use of MTBE by the end of 2002. In the interim, California requires prominent labelling of pumps which dispense gasoline containing MTBE, "in order to allow consumers to make an informed choice as to the type of gasoline they purchase"⁸. On March 15, 2002, Governor Davis announced a decision to delay the ban until January 1, 2004 because of concerns that gasoline shortages could result.

Sixteen other states are also taking or have taken action to ban or limit MTBE in the 2003-2004 time frame, and several others are considering taking action. Several states require labelling of gasoline containing MTBE. Table B.1 in Appendix B summarizes actions taken or proposed by U.S. states with respect to MTBE.

In Canada, CEPA 1999 does not currently provide the authority to ban MTBE as a gasoline additive as this substance was found not to be toxic in an assessment conducted by Environment Canada in 1992 based on the levels of production prior to 1992. There is extremely limited constitutional authority for the federal government to require labelling at the pump - although limited authority exists under the CEPA 1999 to require labelling of fuels, this does not provide the power to require the labelling for MTBE at the pump.

In November 1998, the U.S. EPA administrator commissioned a Blue Ribbon Panel on Oxygenates in Gasoline to assess the water quality problems associated with oxygenates in gasoline. In July 1999, the panel recommended that the current mandate for oxygenates in reformulated gasoline "be removed while quickly reducing usage of MTBE and maintaining air quality benefits".

As follow-up to the Blue Ribbon Panel report, in March 2000 the EPA issued an Advance Notice of Proposed Rulemaking under Section 6 of the Toxic Substances Control Act to control MTBE in gasoline. The Advance Notice indicated that "the outcome of this rulemaking could be a total ban on the use of MTBE as a gasoline additive or a limitation preventing the use of MTBE in gasoline in amounts greater than those designed to provide octane enhancement."⁹

A major energy bill in the last session of the U.S. Congress would have banned MTBE within four years of the bill coming into effect. However, the bill was not passed. It is understood that a revised version of this bill (including the MTBE ban) will soon be introduced into the U.S. Senate

A March 2001 study for the European Commission, "MTBE and the Requirements for Underground Storage Tank Construction and Operation in Member States" indicated that, "contamination is unlikely if standards governing the construction and operation of underground storage tanks at service stations are robustly enforced"¹⁰. The EU Commission has not proposed any restrictions on the MTBE content of gasoline¹¹. In addition, Denmark has looked at the use of tax incentives on gasoline to speed up investment aimed at protecting soil and ground water from leaks of MTBE from underground tanks.

In Australia, legislation has been passed to limit the concentration of MTBE in gasoline to 1% by volume (approximately 0.18% oxygen by volume), beginning January 1, 2004¹².

Some jurisdictions have developed water quality guidelines for MTBE based on the threshold concentration at which MTBE can be tasted (aesthetic level). Other jurisdictions have set guidelines at which MTBE is a threat to aquatic life. California has, in addition, developed a guideline for health effects. In some jurisdictions, these guidelines are used as standards for ground water remediation.

In December 1997, the U.S. EPA issued a drinking water advisory on MTBE. The advisory recommended controlling levels for taste and odour acceptability - levels of 20-40 ppb - that would also protect against potential health effects. Other jurisdictions have also developed guidelines for acceptable levels of MTBE in water (see Table 2.1).

MTBE has been used in Canada since 1986, although use in Canada has been much less widespread than in the U.S. as the addition of oxygenates has never been required in Canadian gasoline. The U.S. Clean Air Act has required the addition of oxygenates to reformulated gasoline since 1993.

Prior to the publication of the 2001 CEPA 1999 Notice, Environment Canada was aware of three cases of ground water contamination with MTBE in Canada:

• In 1997, low levels of MTBE were detected by the U.S. Geological Survey (working with Environment Canada) in the Abbottsford-Sumas Aquifer in southern British Columbia.
• In May 2000, Chevron and the province of British Columbia indicated that MTBE had been found in ground water at Chevron's Burnaby refinery.
• In March 2001, Prince Edward Island's Department of Fisheries, Aquaculture and Environment informed Environment Canada that MTBE had been detected in monitoring wells on, and adjacent to, sites contaminated with gasoline.

The average concentration of MTBE in the Canadian gasoline pool reported by gasoline producers and importers under the Benzene in Gasoline Regulations fell from 0.33% to 0.14% between 1999 and 2000. However, since the regulations do not require reporting of oxygenate blended downstream of refineries (except for a few special incidences described in the regulations), these values underestimate MTBE usage. In comparison, the average concentration of MTBE in the U.S. gasoline pool was approximately 3% in 1998.

• ³ Clawges, Rick, Rowe, Barbara, and Zogorski, John, 2001, National Survey of MTBE and Other VOCs in Community Drinking-Water Sources: U.S. Geological Survey Fact Sheet.
• ⁴ Government of Canada, Canadian Environmental Protection Act Priority Substances List Assessment Report No. 5, Methyl tertiary-Butyl Ether, 1991, pp. v, 12-13.
• ⁵ White House Office of Science and Technology Policy, Interagency Assessment of Oxygenated Fuels, 1997.
• ⁶ World Health Organization, International Programme on Chemical Safety, Environmental Health Criteria 206, Methyl tertiary-Butyl Ether, 1998, p. 9.
• ⁷ U.S. National Groundwater Association, Position Paper on MTBE.
• ⁸ California Air Resources Board website, MTBE Labeling Requirements (http://www.arb.ca.gov/fuels/gasoline/Oxy/mtbelabl/mtbelabl.htm)
  
• ⁹ US EPA, Office of Transportation and Air Quality, Advance Notice of Proposed Rulemaking to Control MTBE in Gasoline, March 2000.
• ¹⁰ Arthur D. Little Limited, Report to the European Commission, "MTBE and the Requirements for Underground Storage Tank Construction and Operation in Member States", April 2001, p. 2.
• ¹¹ European Union, Proposal for a Directive of the European Parliament and of the Council of the Quality of petrol and diesel fuels and amending Directive 98/70/EC, Document 501PC0241, s 6.4.
• ¹² Australian 2001 Fuel Standard (Petrol) Determination, 8 October 2001.