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 deve loped for the implementation of the Minnesota Children's Pesticide Exposure Study (MNCPES), which is one of the first probability-based samples of mul ti-pathway and multi-pesticide exposures in children. The primary objective of MNCPES was to characterize children's exposure to selected pesticides t hrough a combination of questionnaires, personal exposure measurements (i.e ., air, duplicate diet, hand rinse), and complementary monitoring of biolog ical samples ( i.e., pesticide metabolites in urine), environmental samples ( i.e., residential indoor/outdoor air, drinking water, dust on residentia l surfaces, soil), and children's activity patterns. A cross-sectional desi gn employing a stratified random sample was used to identify homes with age -eligible children and screen residences to facilitate oversampling of hous eholds with higher potential exposures. Numerous techniques were employed i n the study, including in-person contact by locally based interviewers, bri ef and highly focused home visits, graduated subject incentives, and traini ng of parents and children to assist in sample collection. It is not feasib le to quantify increases in rates of subject recruitment, retention, or com pliance that resulted from the techniques employed in this study. Neverthel ess, results indicate that the total package of implemented procedures was instrumental in obtaining a high percentage of valid samples for targeted h ouseholds and environmental media.