Dermal Knowledge:  ORISE Participant Researches Effects of Skin Exposure to Chemicals

by Priscilla Campbell

ORISE participant Nicole Allen is having “the best and most rewarding experience” of her career with the U.S. Army Center for Health Promotion and Preventive Medicine (USACHPPM) Health Effects Research Program.  Nicole and her research mentor, Dr. Gunda Reddy, are conducting skin absorption and penetration studies using military unique compounds.  Using the Bronaugh flow-through diffusion cell system they have been able to estimate the percutaneous absorption of 14C-Cyclotrimethylenetrinitramine (RDX) through human skin in vitro.  Dermal exposure to explosive chemicals can occur during several manufacturing and occupational operations.  Currently there is no information available on dermal absorption of RDX in humans for risk assessment. 


Nicole setting up fraction retriever cells for 24-hour collection.

Human abdominal skin obtained from surgery or autopsy is radio labeled with 14C-RDX and applied to the skin surface for 24-hour collections. The RDX absorbed or penetrated through the skin was determined by separating stratum corneum, epidermis and dermis and at the end of the experiments.  Receptor fluid and wash fractions were also collected and counted using Beckman Liquid Scintillation Counter.  The use of the in vitro model to examine skin permeability has been more efficient because it eliminates the toxicity constraints of a clinical study.  The estimated levels of RDX absorbed through the skin can be used to evaluate health risks associated with dermal exposure. 

Penetration of RDX and other nitroaromatic compounds through the skin is a major concern for the military.  An important characteristic of nitroaromatic compounds is their ability to rapidly penetrate the skin.  They can cause the formation of methemeglobin on acute exposures and anemia on chronic exposures.  Additionally, local irritation, liver damage and bladder tumors have also been identified.  The primary benefit of determining the relative penetration of RDX and other military unique compounds through human skin is to improve the accuracy of the risk assessment and to determine the extent to which each compound may be absorbed.  For more information about this research contact Nicole directly via e-mail at Nicole.Allen@APG.AMEDD.ARMY.MIL.
.64µm skin disc sample used for sample collection

Nicole holds a bachelor’s degree in biology from Tougaloo College and a master’s degree in environmental health from Mississippi Valley State University.  No stranger to ORISE, Nicole participated in a Department of Energy- sponsored/ORISE-managed internship at Lawrence Livermore National Laboratory in the summer of 1998.  In spring 1999, Nicole visited the ORISE home campus in Oak Ridge, Tennessee for the annual Women in Science and Technology (WIST) Conference.  At WIST, Nicole learned of the postgraduate internship program at USACHPPM.  She began her research at USACHPPM in October 1999. 

Nicole is in the process of applying to graduate school to pursue a Doctoral Degree in Toxicology at the Johns Hopkins University, Baltimore Maryland.  Her research will seek to apply biomarkers of exposure, susceptibility, and disease in the identification and prevention of environmental pollutants on human health. Having experience with munition compounds, her research will focus on other toxic compounds, including lead and arsenic.  Studies to examine the environmental causes of disease, disease prevention, environment-susceptibility interactions in cancer and developmental damage, molecular epidemiology, cancer prevention, and risk assessment will be investigated in her research.    She hopes to increase our understanding of the environmental etiology of disease so that prevention programs may be initiated.


Nicole's mentor Dr. Gunda Reddy washing a dermatomed 
skin sample before cutting into desired size

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