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INFECTIOUS DISEASE ISSUES RELATED TO WORKING WITH SEWAGE SLUDGES
Smith*, J E. INFECTIOUS DISEASE ISSUES RELATED TO WORKING WITH SEWAGE SLUDGES. Presented at U.S. Composting Council's 10th Annual Conf, Cleveland, OH, 11/12-15/00.
Wastewater contains the feces and urine from both humans and animals that can carry many disease-causing organisms. Disease causing organisms or pathogens from humans can enter a community's wastewater from patients at hospitals, or from any sick person or individual carrying the organisms. Carriers may not have the symptoms or even know they have a disease. Animal wastes can enter the wastewater from farms, meat packing and processing facilities and from rats and other animals and/or vectors found in or around sewage or sewers. Humans come in contact with the pathogens and thus potentially disease by direct contact with sewage, by eating food or drinking water contaminated with sewage, or through contact with human, animal, or insect carriers. During the course of typical wastewater treatment, the microorganisms in sewage are reduced in number, becoming concentrated in the sewage sludge. The infectious dose varies with the organisms and, particularly for bacteria and viruses, can vary widely. Some reported infective dose data shows values as low as 100 for Salmonella, <1PFU for Poliovirus, and 1 egg for helminths. This information coupled with what we know about the survival times of pathogens on soil and plants provided a framework or setting for 40 CFR 503, Standards for the Use or Disposal of Sewage Sludge. These standards require that sludge, before it is applied to land, be either disinfected or applied under restrictions that prevent it from being a risk to public health and the environment and have its vector attractiveness reduced. It is crucial that workers dealing with feedstocks such as sewage sludge/biosolids take proper precautions and take maximum care to provide the required levels of treatment to them. Knowing how the feedstocks may be used, the worker needs to realize the tremendous responsibility they have to produce a "minimal risk" product that may be used safely.