Lead poisoning is a serious health problem affecting millions of Americans, particularly children. The EPA and HUD consider lead paint to be a primary source of the poisoning. Lead is no longer a constituent in commercially sold paint and government agencies have called for its removal in older homes. A central problem to find lead-paint surfaces is the Tack of rapid, inexpensive, reliable methods for measuring levels of lead in concentrations as low as I mg per cm2. We will create a new type of x-ray fluorescent detector that should result in a highly efficient, sensitive detector whose quantitative measurements of lead concentration are independent of the paint substratus or the detector energy resolution. The device will make use of newly available, inexpensive inorganic scintillator phosphors viewed by recently developed small photomultiplier tubes or by PIN silicon diodes. Phase I will prove the principals of the method. In Phase II, we will build and test a prototype of the lead paint detector.Awardee's statement of the potential commercial applications of the research:The long term objective is to make a sensitive, rapid and reliable lead paint detector selling for $4,000 to $5,000, which is about one-half to one-quarter the cost of present systems that are neither rapid nor reliable. We also note that the principle of using critical edge detectors can be applied to measuring lead concentrations in soil and in dust and finding trace quantities of other toxic materials in near-surface materials.National Institute of Environmental Health Sciences (NIEHS)