Toxicokinetic of tris(2-butoxyethyl) phosphate (TBOEP) in humans following single oral administration.

Abstract

Tris(2-butoxyethyl) phosphate (TBOEP; 20µg/kg b.w.) was orally administered to three female and three male volunteers. In urine samples collected for 39h three metabolites of TBOEP were quantitated. bis(2-butoxyethyl) phosphate (BBOEP), tris(2-(3-hydroxy)butoxyethyl) phosphate (OH-TBOEP), bis(2-butoxyethyl)-(2-hydroxyethyl) phosphate (BBOEHEP) were observed in all urine samples within the first 7h with highest concentration for BBOEHEP. C max of OH-TBOEP was in the range of 2-4h and t 1/2 was between 1.5 and 6.1h. Similar results were obtained for BBOEHEP. In contrast BBOEP showed several maxima within 25h and, therefore, no toxicokinetic data were calculated. As proof of concept 54 urine samples of children staying at day-care centers in Germany were analysed for all 3 biomarkers. Only BBOEP and BBOEHEP were detected in about 80% of the samples with a median of 0.16µg/l for BBOEP and 0.18µg/l for BBOEHEP. A recalculation of daily intake (DI) based onBBOEHEP resulted in a clear undercut of the current reference dose of 50µg/kg per day. As observed in other studies a calculation of the DI based on the dust concentrations and oral uptake of 20mg of dust for 8h for young children results in considerably higher DI but would also not exceed the RfD.