title: Application of physiologically-based toxicokinetic modelling in oral-to-dermal extrapolation of threshold doses of cosmetic ingredients.
abstract: The application of physiologically based toxicokinetic (PBTK) modelling in route-to-route (RtR) extrapolation of three cosmetic ingredients: coumarin, hydroquinone and caffeine is shown in this study. In particular, the oral no-observed-adverse-effect-level (NOAEL) doses of these chemicals are extrapolated to their corresponding dermal values by comparing the internal concentrations resulting from oral and dermal exposure scenarios. The PBTK model structure has been constructed to give a good simulation performance of biochemical processes within the human body. The model parameters are calibrated based on oral and dermal experimental data for the Caucasian population available in the literature. Particular attention is given to modelling the absorption stage (skin and gastrointestinal tract) in the form of several sub-compartments. This gives better model prediction results when compared to those of a PBTK model with a simpler structure of the absorption barrier. In addition, the role of quantitative structure-property relationships (QSPRs) in predicting skin penetration is evaluated for the three substances with a view to incorporating QSPR-predicted penetration parameters in the PBTK model when experimental values are lacking. Finally, PBTK modelling is used, first to extrapolate oral NOAEL doses derived from rat studies to humans, and then to simulate internal systemic/liver concentrations - Area Under Curve (AUC) and peak concentration - resulting from specified dermal and oral exposure conditions. Based on these simulations, AUC-based dermal thresholds for the three case study compounds are derived and compared with the experimentally obtained oral threshold (NOAEL) values.
authors.affiliation: Systems Toxicology Unit and EURL ECVAM, Institute for Health and Consumer Protection, European Commission, Joint Research Centre, 21027 Ispra, VA, Italy; University of Milano Biccoca, Department of Earth and Environmental Sciences, Piazza della Scienza 1, Milano, Italy. Electronic address: Monika.Gajewska@ec.europa.eu.
authors.forename: M
authors.initials: M
authors.lastname: Gajewska
authors.affiliation: Systems Toxicology Unit and EURL ECVAM, Institute for Health and Consumer Protection, European Commission, Joint Research Centre, 21027 Ispra, VA, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Worth
authors.affiliation: University of Milano Biccoca, Department of Earth and Environmental Sciences, Piazza della Scienza 1, Milano, Italy.
authors.forename: C
authors.initials: C
authors.lastname: Urani
authors.affiliation: TUM, Wissenschaftszentrum Weihenstephan für Ernährung und Landnutzung, Lehrstuhl für Systemverfahrenstechnik, Weihenstephaner Steig 23, 85350 Freising, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Briesen
authors.affiliation: TUM, Wissenschaftszentrum Weihenstephan für Ernährung und Landnutzung, Department für Biowissenschaften, Weihenstephaner Steig 23, 85350 Freising, Germany; Helmholtz Zentrum München - German Research Center for Environmental Health (GmbH), Molecular EXposomics (MEX), Ingolstädter Landstr.1, D-85764 Neuherberg, Germany.
authors.forename: K-W
authors.initials: KW
authors.lastname: Schramm
mesh_terms: D000279:Administration, Cutaneous; D000284:Administration, Oral; D000465:Algorithms; D000818:Animals; D000975:Antioxidants / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000633:toxicity; D002110:Caffeine / Q000493:pharmacokinetics / Q000633:toxicity; D002138:Calibration; D000697:Central Nervous System Stimulants / Q000493:pharmacokinetics / Q000633:toxicity; D003358:Cosmetics / Q000008:administration & dosage / Q000633:toxicity*; D003374:Coumarins / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000633:toxicity; D003627:Data Interpretation, Statistical; D006801:Humans; D006873:Hydroquinones / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000633:toxicity; D008099:Liver / Q000378:metabolism; D015233:Models, Statistical; D019055:No-Observed-Adverse-Effect Level; D010599:Pharmacokinetics; D021281:Quantitative Structure-Activity Relationship; D051381:Rats; D012867:Skin / Q000378:metabolism; D012869:Skin Absorption / Q000502:physiology; D013045:Species Specificity
chemical_list: D000975:Antioxidants; D000697:Central Nervous System Stimulants; D003358:Cosmetics; D003374:Coumarins; D006873:Hydroquinones; D002110:Caffeine; C030123:coumarin; C031927:hydroquinone
keywords: Caffeine; Coumarin; Hydroquinone; Physiologically based toxicokinetic (PBTK) modelling; Route-to-route extrapolation