A Predictive Model for Survival of Escherichia coli O157:H7 and Generic E. coli in Soil Amended with Untreated Animal Manure

This study aimed at developing a predictive model that captures the influences of a variety of agricultural and environmental variables and is able to predict the concentrations of enteric bacteria in soil amended with untreated Biological Soil Amendments of Animal Origin (BSAAO) under dynamic conditions. We developed and validated a Random Forest model using data from a longitudinal field study conducted in mid-Atlantic United States investigating the survival of Escherichia coli O157:H7 and generic E. coli in soils amended with untreated dairy manure, horse manure, or poultry litter. Amendment type, days of rain since the previous sampling day, and soil moisture content were identified as the most influential agricultural and environmental variables impacting concentrations of viable E. coli O157:H7 and generic E. coli recovered from amended soils. Our model results also indicated that E. coli O157:H7 and generic E. coli declined at similar rates in amended soils under dynamic field conditions.The Random Forest model accurately predicted changes in viable E. coli concentrations over time under different agricultural and environmental conditions. Our model also accurately characterized the variability of E. coli concentration in amended soil over time by providing upper and lower prediction bound estimates. Cross-validation results indicated that our model can be potentially generalized to other geographic regions and incorporated into a risk assessment for evaluating the risks associated with application of untreated BSAAO. Our model can be validated for other regions and predictive performance also can be enhanced when data sets from additional geographic regions become available.     

Exploring the dynamics of racial food security gaps in the United States

Review of Economics of the Household - Household-level food insecurity is one of the largest public health concerns facing millions of people in the United States today. Although recent work has...     

DOES THE WOMEN,INFANTS, AND CHILDREN PROGRAM IMPROVE INFANT HEALTH OUTCOMES?

We reevaluate the causal impacts of prenatal participation in the Women, Infants, and Children (WIC) supplemental nutrition program on birth outcomes by simultaneously accounting for self-selection into WIC and systematic underreporting of program participation. Combining survey data from the Early Childhood Longitudinal Study-Birth Cohort with administrative data from the USDA, we extend partial identification methods to reflect institutional details of the WIC program and validate WIC program participation for a mixture of positive and negative responses. Our preferred estimates imply that WIC increases the prevalence of normal birth weight by at least 4.8% and normal gestation duration by at least 3.7%. (JEL C14, C21, I12, I31, I38)     

Federal nutrition programs and childhood obesity: inside the black box

In response to the dramatic rise in childhood obesity, particularly among low income individuals, federal nutrition assistance programs have come under scrutiny. However, the vast majority of this research focuses on the direct relationship between these programs and child health, while little is known about the mechanisms by which such relationships arise. Using the 2007 American Time Use Survey and the Eating and Health Module, we explore differences in time use—albeit in a non-causal framework—across families that participate in the Supplemental Nutrition Assistance Program, the School Breakfast Program, and the National School Lunch Program to better understand behavioral differences across participants and non-participants. These differences have important implications for future research and policy.