Abstract: A novel safety device for step ladders. This safety device is fabricated and positioned so as to deter, dissuade and deny the ladder user access to the unsupported top step of a step ladder while allowing the user to an aloft tool organizer for pre-loading job materials there-by eliminating the need to repeatedly climb up and down the ladder carrying materials. More people are killed doing construction work every year than in any other occupation and falls are the biggest killer of employees in the construction industry, many of these falls involve the improper use of ladders. Falls are the leading cause of death in and around the home, according to the National Safety Council, there are thousands of people die from falls around the home each year and many suffer disabling injuries many of these also involve ladders. At work or at home, these accidents invariably occur because the victims violate the basic rules of ladder safety.

Abstract: An improved tracer particle is described comprising an ion exchange core having a polymer coating thereon, the coated ion exchange core having a reaction site capable of reacting with a compound containing an oxirane group, said coated ion exchange core having been treated with a compound containing an oxirane group to react with said coated ion exchange core causing an increase in mass of the tracer particle. Preferably, the ion exchange core is labelled with a radionuclide. These particles have improved characteristics including improved stability against leaching and improved handling properties. Such particles are useful in circulatory determinations involving the injection of the particles as a suspension in a physiologically acceptable carrier or medium into the circulatory system of animals.