Dermal contact with chemically contaminated water and soil may be an important route of exposure. Water and soil can be contaminated directly as a result of chemical application and spills or indirectly as a result of contaminated surface water runoff or erosion. Individuals may be exposed by playing or working in contaminated water or soil. Estimating dermal exposure entails obtaining information about the amount of skin surface exposed to the contaminated media, the duration of exposure, physical/chemical factors that influence the amount of media contact with skin, and the likelihood that the chemical contaminant can penetrate the skin. EPA sponsored studies in the 1990's demonstrated approaches to obtain this kind of information. Studies were conducted: to characterize and categorize activities that involve soil contact and to identify physical and chemical factors that enhance chemical penetration through skin under a variety of conditions. Results from these studies have been incorporated into Agency regulatory guidance documents for dermal exposure.(1,2)

Notwithstanding the success of these investigations, many issues remain. Currently, information about dermal contact with highly lipophilic chemicals in contaminated water and soil are limited; making it difficult to accurately estimate dermal exposure to these compounds. Likewise, models that attempt to predict dermal contact and penetration are based on limited data and have not been validated which limits their usefulness. Collectively, this has often resulted in debate about the magnitude of public health risks posed by hazardous wastes at Superfund sites.

To improve dermal exposure assessments and to foster development of improved dermal absorption models, we have embarked on investigations of the dermal absorption potential of highly lipophilic chemicals in soil or water, the influence of soil characteristics and loading procedures, chemical and physical properties of soil that affect chemical movement from soil to skin, and development of rapid reliable dermal absorption test methods. Additional work is being conducted to standardize dermal absorption test procedures and to validate them for chemicals of interest. We believe this approach will yield results that will improve the ability of Agency risk assessors to identify population segments potentially at risk and to estimate their exposure to chemical contaminates of concern more accurately.

The opinions expressed in this manuscript are those of the author and do not reflect opinions or policy of the Environmental Protection Agency. Mention of trade names or commercial products does not constitute an endorsement or recommendation for use.

References
1. U.S. EPA (1997) Exposure Factors Handbook Volume I – III. EPA/600/P-95/002Fa,b,c. Washington, DC: Office of Research and Development

2. U.S. EPA. (2001) The Risk Assessment Guidance for Superfund Volume I: Human Health Evaluation Manual (Part E, Supplemental Guidance for Dermal Risk Assessment) draft. Washington, DC: Office of Emergency and Remedial Response