The development and testing of a dermal exposure system for pharmacokinetic studies of administered and ambient water contaminants

Abstract

Introduction: In order to investigate the pharmacokinetics of water-borne chemicals while eliminating exposures by other routes, a dermal exposure system was developed to expose the hand and forearm of human subjects. Methods: The goal was, primarily, to study the dermal pharmacokinetics of methyl tertiary butyl ether (MTBE), a water contaminant, and, secondarily, the ambient disinfection byproducts (DBPs). MTBE is used as a fuel oxygenate and DBPs result from chlorination of drinking water. The DBPs measured in the water and blood of the subjects were chloroform, bromodichloromethane, and dibromochloromethane. The dermal exposure system was constructed of inert and impervious materials. The interface between the glass and Teflon exposure tank and the subject was custom-made of clear Tedlar (polyvinylfluoride) so that the depth of the arm in the media could be monitored. Results: Sampling of the water concentration of the test chemical, MTBE, demonstrated stability over the duration of the exposure. A temperature loss of about 1.5 °C occurred over the course of the 1-h exposure. Blood concentrations taken from 14 human subjects before, during, and after the 1-h exposure demonstrated that measurable MTBE and DBPs were absorbed. Discussion: This system has the advantages of maintaining contaminant concentration and exposing an anatomically distinct body region, and the convenience of blood sampling.