Measurement of multi-pollutant and multi-pathway exposures in a probability-based sample of children: practical strategies for effective field studies.

The purpose of this manuscript is to describe the practical strategies developed for the implementation of the Minnesota Children's Pesticide Exposure Study (MNCPES), which is one of the first probability-based samples of multi-pathway and multi-pesticide exposures in children. The primary objective of MNCPES was to characterize children's exposure to selected pesticides through a combination of questionnaires, personal exposure measurements (i.e., air, duplicate diet, hand rinse), and complementary monitoring of biological samples (i.e., pesticide metabolites in urine), environmental samples (i.e., residential indoor/outdoor air, drinking water, dust on residential surfaces, soil), and children's activity patterns. A cross-sectional design employing a stratified random sample was used to identify homes with age-eligible children and screen residences to facilitate oversampling of households with higher potential exposures. Numerous techniques were employed in the study, including in-person contact by locally based interviewers, brief and highly focused home visits, graduated subject incentives, and training of parents and children to assist in sample collection. It is not feasible to quantify increases in rates of subject recruitment, retention, or compliance that resulted from the techniques employed in this study. Nevertheless, results indicate that the total package of implemented procedures was instrumental in obtaining a high percentage of valid samples for targeted households and environmental media.