"The big concern is about new national standards for growers that are being discussed," LeJeune said. "The guidelines they're talking about are based on scientific principles but not on exact data, and they seem to be designed to work in states like California and Arizona, but they're not necessarily appropriate for other states, including Ohio."
For example, the upcoming standards will likely include guidelines to keep all livestock out of areas where produce is grown, in an effort to prevent E. coli contamination. But a previous study LeJeune conducted found that horses -- often used on Amish farms -- are unlikely sources of such contamination.
"We found only one horse that tested positive on one day of the study, and that horse happened to be stabled with a goat which also tested positive, LeJeune said. As ruminant animals, goats are more susceptible to E. coli contamination; the study's findings indicate that the potential new rule is too broad.
In the current study, LeJeune also will examine contaminated water and its effect on growing lettuce. "We'll subject lettuce plots to manure-laced water at different concentrations to see if it makes a difference," he said. Results could be different in Ohio's climate than in states such as California, "where the sun beats down all day."
Besides Ohio State and University of Maryland, scientists from Rutgers University, the University of California Davis, the University of Delaware, the University of Florida, the Food and Drug Administration, and the USDA also are participating in the study.
LeJeune is a professor with the Food Animal Health Research Program at OARDC and also has an appointment with Ohio State University Extension. OARDC and OSU Extension are the research and outreach arms, respectively, of Ohio State's College of Food, Agricultural, and Environmental Sciences.