Bis-(2-propylheptyl)phthalate (DPHP) metabolites emerging in 24h urine samples from the German Environmental Specimen Bank (1999-2012)

Bis-(2-propylheptyl)-phthalate (DPHP) has been introduced as a substitute for other high molecular weight phthalates primarily used in high temperature applications (e.g. cable wires, roofing membranes). The aim of this study was to investigate how the increased usage of DPHP is reflected in urine samples collected over the last 14 years and to evaluate the current extent of exposure. We analyzed 300 urine samples (24h voids) from the German Environmental Specimen Bank collected in the years 1999, 2003, 2006, 2009 and 2012, 60 samples per year, from 30 male and 30 female volunteers (age: 20-30 years) for three specific, secondary oxidized DPHP metabolites (with hydroxy, oxo and carboxy modifications of the alkyl side chain). We determined DPHP metabolites with a previously developed GC-HRMS method, enabling us to unambiguously distinguish DPHP metabolites from co-eluting, structurally isomeric di-iso-decyl phthalate (DIDP) metabolites. All samples were blinded before analysis. We detected no DPHP metabolites in urine samples from the years 1999, 2003 and 2006. Thereafter, detection rates increased from 3.3% in 2009 to 21.7% in 2012. Mono-oxo-propylheptylphthalate (oxo-MPHP) was the most abundant metabolite, with concentrations between