Epidemiological Approach for Determining the Significance of Pathogens in Sewage Sludge

摘要

A study of compost workers in four cities indicated only relatively minor effects in workers within 100 m of composting operations. The observed effects may have been due to irritants produced in the composting process (dust, Aspergillus) and not related to the sludge portion of the compost. A prospective epidemiological study concerning the land application of sludge indicated no significant differences in illness and infection rates of people and animals on sludge-applied farms as compared to control farms. However, the human exposure to sludge was very low. The continued use of comprehensive, agent-based prospective epidemiological studies to assess the pathogenic risk of sludge disposal options (with the possible exception of D&M) is not recommended because of design, interpretation and site-specificity problems and because of cost considerations. Disease-based surveillance systems may be of some value in identifying hazardous disposal practices and further investigation into the design and implementation of such systems is recommended. Modeling may be a viable approach for assessing the risk of sludge disposal options but much more work needs to be done to evaluate and validate existing models and to possibly develop alternate models.