Land application of sewage sludges: an appraisal of the US regulations

Current US federal regulations governing the land application of sewage slu dges do not appear adequately protective of human health, agricultural prod uctivity or ecological health. US standards are far less protective than th ose of many European countries and Canadian provinces. This is due to both policy choices such as a 'do no harm' philosophy applied in some northern E uropean countries and also to many gaps and non-conservative assumptions in the risk assessment performed by US Environmental Protection Agency. The p otential for widespread use of sludges on agricultural and residential land , the persistence of many of the pollutants, which may remain in soils for a very long time, and the difficulty of remediation support a cautious appr oach. Soil, water and crop characteristics in New York State and other area s of the northeastern US raise particular concerns. The authors do not sugg est a prohibition of land application but, rather, significantly more restr ictive use. Limiting cumulative additions of pollutants to prevent soils fr om exceeding recommended maximum contaminant levels can be achieved by appl ication of clean sludges or by application of lesser amounts of less high q uality sludges. Further investigation is needed to assess risks to ground a nd surface water and to establish standards for additional contaminants.