Implications of an MTBE odor study for setting drinking water standards

Abstract

In early 2001, the US Environmental Protection Agency is expected to adopt a secondary maximum contaminant level (SMCL) for methyl tertiary butyl ether (MTBE) in drinking water. This article presents the first and only consumer study to determine the odor threshold of MTBE in drinking water. A protocol, based on the American Society for Testing and Materials method E679–91, was augmented to address concerns raised by interested stakeholders. The study, which was conducted according to the final odor threshold protocol, used a panel of 57 consumers and yielded an odor threshold for MTBE in drinking water of 15 μg/L. The 15 μg/L threshold is the geometric mean of the individual thresholds for each of the 57 consumers. This consumer panel threshold is consistent with the trained panel thresholds reported from five other taste and/or odor studies, which ranged from 13.5 to 45.5 μg/L. Consequently, the authors recommend using the methodology presented in this article as the scientific basis for establishing the federal SMCL for MTBE and other organic chemicals in drinking water.

Odour and flavour thresholds of gasoline additives (MTBE, ETBE and TAME) and their occurrence in Dutch drinking water collection areas

“…For example, odour and flavour thresholds of 7 and 15 lg L À1 found in the current study for MTBE are comparable with literature values such as 34 and 48 lg L À1 for odour and flavour, respectively (Young et al, 1996), 43-71 (odour) and 24-37 (flavour) lg L À1 (Dale et al, 1997), 15 lg L À1 for both odour and flavour (Pirnie, 1998;Stocking et al, 2001), 18 lg L À1 for odour (Campden 2003, presented in Suffet, 2007) and 7.4 (odour) and 7.3 (flavour) lg L À1 (Danish EPA, 2000). Prah et al (1994) reported a much higher odour threshold value of 180 lg L À1 .…”

Determining odour detection thresholds: Incorporating a method-independent definition into the implementation of ASTM E679

“…The first judgement procedure is commonly used in experiments that involve simultaneous testing on multiple judges (Kolpin & Shellhammer, 2009;Pickering, Karthik, Inglis, Sears, & Ker, 2007;Plotto, Margaria, Goodner, Goodrich, & Baldwin, 2004;Stocking, Suffet, McGuire, & Kavanaugh, 2001). A full evaluation of all 3AFC trials is collected from each judge, and the threshold is estimated from the location in the series at which the response reversed from incorrect to correct for the last time.…”

MTBE in Drinking Water Production - Occurrence and Efficiency of Treatment Technologies

“…The taste and odour threshold of MTBE in drinking water ranges between 15 μg/L and 50 μg/L depending on the experience of the consumers [8].…”