From The Chicago Tribune: For years, the U.S. Environmental Protection Agency has endorsed the recycling of ground-up tires to cushion the surfaces of children's playgrounds and sports fields. Now, the agency is having second thoughts. EPA scientists are worried that they don't have enough information about potential health risks from chemicals in the rubber, which is popular because it decreases playground injuries and is low maintenance and weatherproof. The concerns are disclosed in internal agency documents about a study the EPA is conducting of air and surface samples at four fields and playgrounds that use recycled tires. The study was prompted by other research suggesting potential hazards from repeated exposure to bits of shredded tire.