Fly ash residues from several sites in which solid municipal refuse is being incinerated for energy production were found to contain excessive amounts of cadmium and/or lead according to an empirical extraction test (0.5 N acetic acid) developed by the Environmental Protection Agency. Samples of associated bottom ashes contained acceptable levels of Cd and Pb, but several were marginal with respect to Pb content. Leaching tests clearly demonstrated that Cd and, to a lesser extent, Pb were mobile in soil when applied in a fly ash matrix. The high chloride content (10-12%), which is characteristic of these ashes, resulted in metal complexation and enhanced Cd and Pb mobility in soil. Normally these elements are relatively immobile in soils when applied as inorganic salts or contained in municipal sewage sludge. Plant uptake of Cd and Pb in a greenhouse test was marked when fly or finely ground bottom ashes were soil applied. Phytotoxicity of fly ash appeared to be associated with the high salt content rather than with a specific metal.

Although plastics wastes form only a very small portion of the total wastes generated in the United States, considerable concern has been expressed over the environmental damage and nonrecyclability attributed to plastics. The plastics industry has made a careful study of the existing and potential recycle opportunities for plastics, both within the industry and from solid waste material. The conclusion that is rapidly taking shape as a result of these studies is that the use of waste plastics in an unsorted form for the recovery of energy by either pyrolysis or incineration will probably be the most successful plastics recycling program in the context of present day technology and economics. However, the technology and economic evaluation of these opportunities is still in a development phase. Therefore, until energy recovery is clearly shown to be the optimum reuse of plastics, the plastics industry will continue to support other short-term activities. These activities include programs for sorting plastics from mixed solid waste and economic research for markets for products from such materials. The plastics industry continues to encourage programs that demonstrate that plastics can be recycled if the circumstances are such that clean material of one kind can be obtained in volume quantities. Since the majority of our collected municipal waste is now going to landfills, it is important to recognize that plastics contribute no particular problems to landfill in that they are nonbiodegradable and compact readily to provide good solid fill in this kind of disposal system.