Design and sampling methodology for a large study of preschool children's aggregate exposures to persistent organic pollutants in their everyday environments

Young children, because of their immaturity and their rapid development compared to adults, are considered to be more susceptible to the health effects of environmental pollutants. They are also more likely to be exposed to these pollutants, because of their continual exploration of their environments with all their senses. Although there has been increased emphasis in recent years on exposure research aimed at this specific susceptible population, there are still large gaps in the available data, especially in the area of chronic, low-level exposures of children in their home and school environments. A research program on preschool children's exposures was established in 1996 at the USEPA National Exposure Research Laboratory. The emphasis of this program is on children's aggregate exposures to common contaminants in their everyday environments, from multiple media, through all routes of exposure. The current research project, "Children's Total Exposure to Persistent Pesticides and Other Persistent Organic Pollutants," (CTEPP), is a pilot-scale study of the exposures of 257 children, ages 11/2-5 years, and their primary adult caregivers to contaminants in their everyday surroundings. The contaminants of interest include several pesticides, phenols, polychlorinated biphenyls, polycyclic aromatic hydrocarbons, and phthalate esters. Field recruitment and data collection began in February 2000 in North Carolina and were completed in November 2001 in Ohio. This paper describes the design strategy, survey sampling, recruiting, and field methods for the CTEPP study.