Potential Effects of Heavy Metals in Municipal Solid Waste Composts on Plants and the Environment

While considerable attention has been paid to the land application of sewage sludges and composted sewage sludges in the U.S. during the last twenty years, land application of municipal solid waste (MSW) composts has received comparatively little attention. However, there has been a recent resurgence of interest in this topic as other options for solid waste disposal such as landfilling and incineration become less publicly acceptable and increasingly costly. As interest in MSW composting increases, one of the concerns that must be addressed is the extent to which the low concentrations of heavy metals and metalloids (metal-like elements) present in MSW compost may adversely affect plant growth, soil organisms, water quality and animal and human health. This fact sheet focuses primarily on how these elements are taken up by plants growing in soil to which MSW composts have been added. A brief discussion of the effects of these elements on soil organisms and water quality is also included. The information is drawn from a review of long-term field experiments in which plants were grown in soil with high doses of MSW composts (i.e., realistic “worst case” situations). Few field studies with MSW composts have investigated the long-term cumulative effects of MSW compost application to agricultural land. To supplement the information available from MSW compost studies, studies of sewage sludge and yard waste compost have also been considered. Since MSW composts are similar to sewage sludge composts in many respects, much of what has been learned about the latter can be extrapolated to MSW composts. New regulations for sewage sludge application to land were recently established by the U.S. Environmental Protection Agency. These regulations define Alternative Pollutant Limits (APL) for metals in sewage sludge. Trace Elements and MSW Compost