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PATHOGEN RISKS FROM APPLYING SEWAGE SLUDGE TO LAND
Citation:
Lewis, D L. AND D K. Gattie. PATHOGEN RISKS FROM APPLYING SEWAGE SLUDGE TO LAND. ENVIRONMENTAL SCIENCE & TECHNOLOGY 36(13):286A-293A, (2002).
Impact/Purpose:
In support of NERL APM "Demonstrate models to forecast the effectiveness of alternative management plans in meeting pathogen-related criteria and standards," this task will identify chemical and microbiological factors affecting risks pathogens pose to public health and assess the effectiveness of alternative management plans to reduce those risks.
Description:
Congress banned ocean dumping of municipal wastes in the late 1980s. In its place, EPA developed guidance (40 CFR Part 503) for land application of processed sewage sludge (biosolids), mainly for agricultural purposes (1). Public health and environmental concerns with processed sewage sludge have historically centered on heavy metals, pesticides, PCBs, and other chemical contaminants (2).
The 503 rule, promulgated in 1993, included no formal risk assessment for bacteria, viruses, and other disease-causing microorganisms (3). Now, amid a growing number of complaints of illnesses and sporadic deaths among residents living near land application sites, a debate rages over whether risks - especially from pathogens - should have been more carefully assessed (see Figure 1).
Illnesses reported by people exposed to dusts and water runoff from fields treated with sewage sludge indicate a pattern of chemical irritation - burning eyes, burning lungs, difficulty in breathing, and skin rashes. These symptoms are followed within days to months with complaints of gastrointestinal, skin, and respiratory infections (4).
Such reports are dismissed outright by proponents of land application practices as purely anecdotal. They argue that the only problem is public perception and point to a lack of documented cases of illnesses as proof that the practice is well managed and safe. Those impacted, however, argue that adverse effects are not monitored and proper epidemiological studies have never been done. Unfortunately, arguments on both sides are based on what science has not been done. It is not a dispute over interpretation of data, but over how to interpret the lack of data.
Unlike other public health organizations grappling with threats of infectious diseases, EPA has relatively little expertise in infection control, no system or plan for monitoring infectious diseases nationwide, and provides virtually no resources to states to carry out its regulations in this area (5). Yet, the agency has the responsibility of overseeing the processing and disposal of, collectively, what is likely to be the nation's largest repository of infectious human material.
On the other hand, unlike the federal Centers for Disease Control and Prevention (CDC), EPA is a regulatory agency. Its rules and regulations carry the force of law and violations are subject to criminal penalties. EPA is currently collaborating with the CDC to jointly assess potential land application problems. A properly managed national biosolids program that merges the expertise of the CDC with the regulatory authority of the EPA may be the best way to ensure that public health and the environment are adequately protected in this area.