Methyl tertiary-butyl ether exposure from gasoline in the U.S. population, NHANES 2001–2012

Abstract

BACKGROUND: Methyl tertiary-butyl ether (MTBE) was used as a gasoline additive in the United States during 1995–2006. Because of concerns about potential exposure and health effects, some U.S. states began banning MTBE use in 2002, leading to a nationwide phaseout in 2006. OBJECTIVES: We investigated the change in blood MTBE that occurred during the years in which MTBE was being phased out of gasoline. METHODS: We used data from the National Health and Nutrition Examination Survey (NHANES) from 2001–2012 to assess the change in blood MTBE over this period. We fit sample-weighted multivariate linear regression models to 12,597 human blood MTBE concentrations from the NHANES 2001–2002 to 2011–2012 survey cycles. RESULTS: The unweighted proportion of the individuals with MTBE blood levels above the limit of detection (LOD) of 1:4 ng=L was 93.9% for 2001–2002. This portion dropped to 25.4% for the period 2011–2012. Weighted blood MTBE median levels (ng/L) (25th and 75th percentiles) decreased from 25:8 ð6:08, 68:1Þ ng=L for the period from 2001–2002 to 4:57 ð1:44, 19:1Þ ng=L for the period from 2005–2006. For the entire postban period (2007–2012), MTBE median levels were below the detection limit of 1:4 ng=L. DISCUSSION: These decreases in blood MTBE coincided with multiple statewide bans that began in 2002 and a nationwide ban in 2006. The multivariate log-linear regression model for the NHANES 2003–2004 data showed significantly higher blood MTBE concentrations in the group who pumped gasoline less than 7 h before questionnaire administration compared to those who pumped gasoline more than 12 h before questionnaire administration (p = 0:032). This study is the first large-scale, national-level confirmation of substantial decrease in blood MTBE levels in the general population following the phaseout of the use of MTBE as a fuel additive. https://doi.org/10.1289/EHP5572.