To demonstrate the feasibility of the method to determine chronic low-dose co-exposure in breast milk, the method was applied to 86 breast milk samples collected from a mother during the first 211 days post-partum. Individual daily results are reported in Supplementary Table (without enzymatic hydrolysis) and S10 (after enzymatic hydrolysis). A direct comparison of the two data sets is given in Supplementary Table . Chromatograms of the mass transition used for quantitation of selected compounds detected in the breast milk samples are plotted in Figure f. Unexpectedly, 29 xenobiotics were detected in at least one sample (Table ; Figure ).