The U.S. EPA is gearing up to restrict the use of chlorpyrifos, which is one of the most widely used insecticides in the U.S. and has been linked to memory loss, nervous system problems, and other health concerns. The chemical, also known by the trade name Dursban, is sprayed on a variety of crops and is used frequently around homes, schools, and businesses in products such as flea collars and bug spray. The use of chlorpyrifos is so widespread that the insecticide was found in the urine of more than 80 percent of 1,082 Americans tested. A number of enviro groups, consumer groups, and university scientists are pushing for dramatic limits on the insecticide. The EPA is expected to announce its proposed restrictions later this spring. Meanwhile, a new study by the Pesticide Action Network found that California’s overall pesticide use jumped 40 percent between 1991 and 1998.