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A Comparative Investigation of the Influence of Dermal Appendages (Hair Follicles) on the Percutaneous Absorption of Organophosphorus (Op) Insecticides Using QSAR and PBPK/Pd Models for Human Risk Assessment

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Abstract: The successful use of the Exposure Related Dose Estimating Model (ERDEM) for assessment of dermal exposure of humans to OP pesticides requires the input of representative and comparable input parameters. In the specific case of dermal exposure, regional anatomical variation in the rate of percutaneous absorption must be considered in order to make reasonable estimates of absorbed dose. To accomplish this assessment, estimates of hair follicle density were generated for various regions of the body including the scalp, forearms and hands. Quantitative Structure Activity Relationships (QSAR) were used to obtain Kp values (cm/h) for percutaneous absorption, skin/water and tissue/blood partition coefficients, and metabolic parameter values (Vmax and Km). Inhibition of the B-esterases (acetylcholin-, butyrylcholin- and carboxyl-) was used as the dose metric for the determination of margins of exposure (MOE) for exposure scenarios where various anatomical areas of the body may be implicated. Modeling results show the importance of considering regional variation in hair volume and density in exposure and risk assessment.

This work has been funded by the United States Environmental Protection Agency under Interagency Assistance Agreement (DW 47944301) to GSA. It has been subjected to Agency review and approved for publication.
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Citation:Tornero-Velez, R., C. C. Dary, J. B. Knaak, F. W. Power, and M. Dellarco. A Comparative Investigation of the Influence of Dermal Appendages (Hair Follicles) on the Percutaneous Absorption of Organophosphorus (Op) Insecticides Using QSAR and PBPK/Pd Models for Human Risk Assessment. Presented at International Society of Exposure Analysis, Stresa, Italy, September 21-25, 2003.
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Contact: Liz Hope - (919) 541-2785 or hope.elizabeth@epa.gov
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Division: Human Exposure & Atmospheric Sciences Division
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Branch: Exposure & Dose Research Branch
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Product Type: Abstrct/Oral
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Presented: 07/23/2003
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Related Entries:
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Bullet Item Models and Modeling Methods for Assessing Human Exposure and Dose to Toxic Chemicals and Pollutants
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Last Updated on Monday, October 22, 2007
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