A new study by the National Academy of Sciences has raised questions about a common agricultural practice: applying sewage sludge from city wastewater treatment plants to farm fields. Professor Thomas Burke with Johns Hopkins University School of Public Health in Baltimore says there is a serious lack of health-related information about populations exposed to treated sludge. Burke was Chairman of the study team. He says the Environmental Protection Agency should investigate allegations of adverse health effects. Kansas City has allowed farmers to use its treated waste for years.