Estimating dietary consumption patterns among children: a comparison between cross-sectional and longitudinal study designs

Estimating dietary intake for children is an essential component of conducting pesticide exposure assessments given the fact that children are predominantly exposed to certain pesticides, such as organophosphorus pesticide, through dietary intake. Different study designs and their respective sampling methodology utilized to estimate food consumption patterns can significantly alter the parameter estimates and the variability in the values obtained. This study investigated the impacts of study design on overall estimates of dietary intake by applying the temporal sampling characteristics used in cross-sectional approaches, as in The Continuing Survey of Food for Intakes by Individuals (CSFII), to food consumption data collected in a longitudinal manner via a bootstrap sampling technique. We examined the precision of time-averaged dietary intake estimates under various sampling schemes and explored the contribution of seasonality toward the dietary patterns. A comparison between the estimates of food consumption obtained from the bootstrap replicates and the longitudinal study estimates indicate that variability is significantly decreased when employing a longitudinal study design. Moreover, both between and within-subject variability decreases when individuals are followed over an increasing number of days. Finally, within the longitudinal study cohort, we observed a seasonal component to dietary intake for fruits and grains. Our findings suggest that longitudinal dietary surveys offer substantial improvements for exposure assessment compared to a standard cross-sectional design.