 we developed a sensitive and accurate analytical method for quantifying methyleugenol ( me ) in human serum . 
 our method uses a simple solid - phase extraction followed by a highly specific analysis using isotope dilution gas chromatography - high resolution mass spectrometry . 
 our method is very accurate ; its limit of detection is 3.1 pg / g and its average coefficient of variation is 14% over a 200-pg / g range . 
 we applied this method to measure serum me concentrations in adults in the general u.s . 
 population . 
 me was detected in 98% of our samples , with a mean me concentration of 24 pg / g ( range < 3.1 - 390 
 pg / g ) . 
 lipid adjustment of the data did not alter the distribution . 
 bivariate and multivariate analyses using selected demographic variables showed only marginal relationships between race / ethnicity and sex / fasting status with serum me concentrations . although no demographic variable was a good predictor of me exposure or dose , 
 our data indicate prevalent exposure of u.s . 
 adults to me . 
 detailed pharmacokinetic studies are required to determine the relationship between me intake and human serum me concentrations.imagesfigure 1figure 2figure 3figure 4figure 5figure 6figure 7 
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