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MtBE (Methyl Tertiary-Butyl Ether) Occurrence in Florida Drinking Water Systems

 

MTBE is a fuel additive that has been in use since 1979 and was one of the additives recommended by EPA to be used as a mechanism for air pollution control in 1992 and even more so in 1995. Primarily, the EPA requirement to use reformulated gas is limited to those states/regions where carbon monoxide emission reductions are critical (and therefore has not been required in Florida). While MTBE is found in fuels used in Florida, it is not at the concentrations (approx. 15%) where these EPA requirements are mandated.

As a result, the problems seen in other states are not readily occurring in Florida. This is due primarily to Florida's geological and hydrogeological conditions (flat and shallow aquifer) and the low concentrations of MTBE in Florida Fuels.

Florida has monitored the concentration of MTBE at petroleum contaminated sites since Feb. 1990, and has established a cleanup target level of 50 parts per billion. This level is based upon organoleptic (odor) conditions and may change if toxicological information determines the chemical to be a carcinogen. While MTBE is frequently found at petroleum contaminated sites, it poses less problems compared to other states and is not normally a significant "driver" in cleanup efforts. Benzene (a known carcinogen) is one of the more abundant chemicals found at gasoline contaminated sites and has a cleanup target level of 1 part per billion and typically controls the cleanup time/effort.

The Florida Drinking Water Program has investigated the occurrence and concerns of MtBE contamination in Florida’s public water systems (PWS). PWSs have been sampling for this contaminant as an unregulated contaminant since the early 1990’s. As an unregulated contaminant it has no established health standard, referred to as a Maximum Contaminant Level or MCL. However, EPA has established a level at which it does present a detectable taste and/or odor. This level is presented as a range of 20-40 ppb. Past EPA research indicates that this level is orders of magnitude below (more stringent) than associated health risks to humans. This is however based on mice and rat studies on MtBE noncancer, cancer, reproductive, developmental, neurotoxicity, and mutagenicity effects. In essence the taste and odor level governs a water’s acceptability to the consuming public. The PWS section of FDEP pulled all the sampling data for all systems since 1993. Of the 1000 plus samples in the database only two systems exceeded a 20 ppb level. Those two systems, Three Worlds Camp Resort (Polk County) with 228 people and Oklawaha Water Works (Marion County) with 994 people, showed results of 166 ppb (1994) and 104 ppb (1997) respectively. However, both systems have since resampled (within three months) and results indicate "no detection".

In summary, the levels found in Florida indicate that none of the Drinking Water Systems are experiencing MtBE contamination at the taste/odor thresholds; and secondly the odor/taste nature of the contaminant itself makes it unpalatable at levels that might cause a health concern based on EPA’s present knowledge of the toxicity of this contaminant.  


 

MTBE Sampling Results

 

The spreadsheets offered below contain the results of 8,739 MTBE samples taken since November 1, 1993. MTBE was detected in 428 samples and not detected in 8,311 samples. Detections are easily identified by an entry in the Result column, and with ** in the PWS ID column. 

The spreadsheets contain the following columns:

PWS ID (the ID contains the county code, see 'Information from the Drinking Water Database' for the full explanation)

NAME

TYPE (C = Community, P = Nontransient Noncommunity, N = Transient Noncommunity)

SOURCE (S = Surface, G = Ground)

SAMPLE TYPE (C = Check, D = Distribution, E = Composite, N = Entry Point, P = Plant, Q = Quarterly, R = Raw, S = Special)

CONTAM ID (= 2251 for MTBE)

SAMPLE DATE

REMARKS

 

Last updated: September 30, 2014

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