Methyl tertiary-butyl ether (MtBE) is a volatile organic chemical that has been used as an octane enhancer in gasoline since the late 1970s. Because its use results in the more complete burning of gasoline, thereby reducing pollutant levels and significantly improving air quality, it is commonly used as a gasoline additive.
The failure to properly contain and distribute gasoline in underground storage tanks, gasoline pipelines, or powered watercraft gasoline tanks can cause MtBE and other gasoline constituents to reach groundwater and surface water.
There have been a limited number of instances of MtBE contamination of public and private wells that have occurred because of leaks from under and above ground petroleum storage tank systems and pipelines. Recreational watercraft are most likely to be the cause of small-scale contamination in a number of shallow aquifers and surface waters. Because of its small molecular size and solubility in water, MtBE moves rapidly into groundwater.
Based on the U.S. Environmental Protection Agency’s (EPA) current sampling data, most concentrations at which MtBE has been found in drinking water sources are unlikely to cause adverse health affects. In fact, there is no data about the effects of humans drinking MtBE-contaminated water. However, the EPA is continuing to evaluate the available information and is doing additional research to seek more definitive estimates of potential risks to humans drinking water with MtBE.
The EPA has initiated a Health Advisory Program that provides information and guidance to individuals or agencies concerned with the potential risk from drinking water contaminants for which no national regulations currently exist. The Advisory recommends control levels for taste and odor acceptability that will also protect against potential health effects. The EPA has concluded that keeping concentrations of MtBE in the range of 20 to 40 micrograms per liter of water or below will avert unpleasant taste and odor effects, recognizing that some people may be able to detect the chemical below this. This recommendation is approximately 20,000 to 100,000 times lower than the exposure level at which health effects were observed in animal testing.
The EPA, other federal and state agencies and private entities are conducting research and developing a strategy for future research on all health and environmental issues associated with the use of oxygenates. In addition, the EPA’s Office of Water has entered into a cooperative agreement with the U.S. Geological Survey (USGS) to conduct an assessment of the occurrence and distribution of MtBE in the 12 mid-Atlantic and Northeastern states.
The key to reducing gasoline chemicals, including MtBE, in drinking water sources is underground gasoline storage tank leak prevention and early detection. Under EPA regulations, leaks from underground storage tank systems (USTs), which may cause contamination of groundwater with MtBE or other materials, are required to be reported to the “implementing agency” which, in most cases, is a state agency. All USTs installed after December 1988 have been required to meet EPA regulations for preventing leaks and spills. In addition, all USTs that were installed prior to December 1988 must be upgraded, replaced, or closed to meet these requirements by December 1998.
IBWA members, regardless of their source type, use a variety of practices to ensure the safety and high quality of their products. Bottled water is protected by the multi-barrier approach, which may include steps such as source protection and monitoring, granulated activated carbon filtration, reverse osmosis, micron filtration, distillation, ozonation, the application of ultra violet light or other appropriate processing measures. Carbon filtration, reverse osmosis and distillation can remove MtBE from bottled water. Based on the routine use of these protective measures, it is highly unlikely that MtBE would be found in bottled water.
Bottled water is a highly regulated product, subject to federal, state and industry standards. The U.S. Food and Drug Administration (FDA), under the Federal Food, Drug and Cosmetic Act (FFDCA or the Act), regulates bottled water as a food product and the EPA regulates the quality of public water supplies (tap water) as a utility.
Bottlers are required by the FDA to monitor their water source, which involves a series of tests and procedures designed to determine whether a source is suitable for use. For example, on a weekly basis tests are conducted to evaluate the microbiological characteristics of a source. However, sources are tested on an annual basis for chemical, physical and radiological characteristics. MtBE is part of the routine annual chemical testing that is required of all bottled water products produced by IBWA members.
Once a source is selected, it is routinely monitored, ensuring bottled water manufacturers that the source of their water continues to be safe and of high quality. In addition, natural underground sources must be inspected, tested and certified by the state or country of origin to be of sanitary quality.