Abstract
Di-(2-propylheptyl) phthalate (DPHP) is used as a plasticizer for polyvinyl chloride products. A tolerable daily intake of DPHP of 0.2 mg/kg body weight has been derived from rat data. Because toxicokinetic data of DPHP in humans were not available, it was the aim of the present work to monitor DPHP and selected metabolites in blood and urine of 6 male volunteers over time following ingestion of a single DPHP dose (0.7 mg/kg body weight). Concentration-time courses in blood were obtained up to 24 h for DPHP, mono-(2-propylheptyl) phthalate (MPHP), mono-(2-propyl-6-hydroxyheptyl) phthalate (OH-MPHP), and mono-(2-propyl-6-oxoheptyl) phthalate (oxo-MPHP); amounts excreted in urine were determined up to 46 h for MPHP, OH-MPHP, oxo-MPHP, and mono-(2-propyl-6-carboxyhexyl) phthalate (cx-MPHP). All curves were characterized by an invasion and an elimination phase the kinetic parameters of which were determined together with the areas under the concentration-time curves in blood (AUCs). AUCs were: DPHP > MPHP > oxo-MPHP > OH-MPHP. The amounts excreted in urine were: oxo-MPHP > OH-MPHP> > cx-MPHP > MPHP. The AUCs of MPHP, oxo-MPHP, or OH-MPHP could be estimated well from the cumulative amounts of urinary OH-MPHP or oxo-MPHP excreted within 22 h after DPHP intake. Not considering possible differences in species-sensitivity towards unconjugated DPHP metabolites, it was concluded from a comparison of their AUCs in DPHP-exposed humans with corresponding earlier data in rats that there is no increased risk of adverse effects associated with the internal exposure of unconjugated DPHP metabolites in humans as compared to rats when receiving the same dose of DPHP per kg body weight.
Highlights
Di-(2-propylheptyl)phthalate (DPHP), CAS No 53306-54-0, marketed under the trade name “Palatinol®10-P“ among others, is a high molecular weight branched phthalate ester which is used as a plasticizer for polyvinyl chloride (PVC) products
From a comparison of the Areas under the concentration-time curves (AUC) of free metabolites of DPHP in DPHP-exposed humans with corresponding data in DPHP-exposed rats, it was concluded that there is no increased risk of adverse effects associated with DPHP metabolites in humans as compared to rats
Large interindividual differences in the AUC0-24 were found for all substances; they were most pronounced for the diester with a factor of 32
Summary
Di-(2-propylheptyl)phthalate (DPHP), CAS No 53306-54-0, marketed under the trade name “Palatinol®10-P“ among others, is a high molecular weight branched phthalate ester which is used as a plasticizer for polyvinyl chloride (PVC) products. Typical contents of DPHP in end-use products vary between 30 and 60% (w/w) (BfR, 2011; NICNAS, 2003). DPHP, like other plasticizers, is not chemically bound in PVC products so it can be released into the environment. The relationship between an excreted oxidized metabolite (oxo-MPHP) and the oral dose ingested (Leng et al, 2014) was used when estimating from urinary excretion data a maximum daily intake of 0.32 μg DPHP/kg body weight (bw) for the general German population (Schütze et al, 2015)
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