Physical barriers and zoning restrictions appear to be mosteffective in protecting people from hazardous industrial waste sites, with approaches tailored specifically to each location, say two UC Davis geography researchers. Because public knowledge of the existence of toxic sites is often lost within 100 years, land-use decisions for such sites are critical, say Russell Jones and Jon Barbour, UC Davis doctoral students who are examining structural controls at hazardous sites in Colorado and in California. They are determining how well such barriers have served in limiting human exposures at each site. A preliminary finding is that for physical barriers such as fences and signs, ongoing maintenance is key to their effectiveness in limiting the public's access. At old landfills and former mining areas studied, signs of unauthorized intrusions were evident where barriers were maintained inadequately, say Jones and Barbour. They will present their findings at 1:30 p.m. Saturday, April 2.