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Regulatory Alert - RA 03-03 - EPA PUBLISHES SUMMARY OF EXPERTS WORKSHOP ON PUBLIC HEALTH IMPACTS OF SEWER OVERFLOWS

Member Pipeline - Regulatory - Alert (RA 03-03)

To: Members & Affiliates, Water Quality Committee, Wet Weather Committee
From: National Office
Date: January 24, 2003
Subject: EPA PUBLISHES SUMMARY OF EXPERTS WORKSHOP ON PUBLIC HEALTH IMPACTS OF SEWER OVERFLOWS
Reference: RA 03-03

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On December 26, 2002, the U.S. Environmental Protection Agency (EPA) published its Summary of the August 14 – 15, 2002, Experts Workshop on Public Health Impacts of Sewer Overflows (Summary) (67 Fed. Reg. 78802). The Summary may be found on EPA’s web site at http://www.epa.gov/npdes/pubs/expert_workshop_summary.pdf. This Experts Workshop was held to provide feedback to the Agency on the public health effects of wet weather overflows in conjunction with EPA’s Combined Sewer Overflow (CSO)/Sanitary Sewer Overflow (SSO) Report to Congress. The Summary provides minutes from the discussions among the invited experts in public health, epidemiology, and wastewater treatment. David Williams, Chair of AMSA’s Wet Weather Committee and Director of Wastewater with the East Bay Municipal Utility District and Frank Greenland, Planning Manager from the Northeast Ohio Regional Sewer District, attended the meeting as observers on behalf of AMSA.

The purpose of the meeting was to discuss fully the issues surrounding the health impacts of CSOs and SSOs, review all information and data sources available to date, and critique the methodology of analyzing the public health information existing on sewer overflows. This Regulatory Alert provides a cursory overview of key sections of the Summary, and some of the significant statements made by the participants.

Background – Wet Weather Reports to Congress
EPA conducted the Experts Workshop as a part of the public involvement process for the second of two reports to Congress required by statute under the Wet Weather Water Quality Act of 2000 (posted on AMSA’s web site at http://www.amsa-cleanwater.org/private/legreg/outreach/01-2001WWWQA-Final.pdf). The first report, Implementation and Enforcement of the Combined Sewer Overflow Control Policy, was delivered on January 29, 2002, and can be found on EPA’s web site at http://cfpub.epa.gov/npdes/cso/cpolicy_report.cfm. AMSA participated in this first report by surveying its combined system members on progress made since 1994 and remaining challenges, and issuing a companion report, Communities at Work ... The National Response to the CSOs (posted at http://www.amsa-cleanwater.org/advocacy/01-31-02csoreport.pdf).

The second report, the CSO/SSO Report to Congress, which is due to Congress on December 15, 2003, requires EPA to evaluate:

The objective of the Experts Workshop was to assist the Agency in focusing its research on human health impacts. In terms of exploring the extent of those impacts, by EPA’s own acknowledgment, initial research has revealed that relatively little data exists linking waterborne illnesses or other exposures to CSOs or SSOs, or providing an accurate accounting of the incidence of overflows.

Beyond participating in this workshop, AMSA’s Wet Weather Committee plans to provide assistance to EPA where appropriate with data from the Association’s 2002 Wet Weather Survey and to counsel the Agency in framing findings from the relevant portions of the CSO/SSO Report to Congress.

Highlights of the Experts Workshop Discussion
The experts present at the August meeting were asked to give individual opinions on the following general topics:

It should be noted from the outset that consensus opinions or policy recommendations were not an intended outcome of the meeting, and therefore the Summary did not present overall EPA findings or policies on public health impacts, nor did it endorse any of the opinions offered in the document. Rather, the Summary simply captured statements made by the individual participants. It is therefore difficult to provide more than a highlight of some of the more pertinent statements included in the Summary. These highlights, broken down by discussion topic, are provided below.

Characterizing Pathogens and Pollutants (p. 13-22)
During this portion of the Experts Workshop, participants provided feedback on a list of pathogens and pollutants expected to be present in sewer overflows (see pages 14-17) which was prepared by EPA’s contractor. The participants also were asked to provide their opinions on what pathogens and pollutants are present in overflows, what illnesses are associated with these constituents, which cause the most serious health effects, and who has data regarding these constituents. Much of the discussion centered around providing feedback on individual parameters or illnesses, and, as a result, it cannot be easily summarized in this Regulatory Alert.

Among the statements made was one by an attendee who noted that bacteria, the most commonly used indicator of sewage contamination, were initially developed to determine whether wastewater treatment technologies were functioning, not specifically to protect human health. Another participant observed that using viral indicators of sewage contamination is difficult because viral counts are typically low and samples often must be concentrated to facilitate detection.

Pathways of Exposure (p. 22-25)
The experts were also asked to provide their insight on other sources and exposure pathways of pathogens. Among the sources of pathogens listed by the experts were the following: sediments in sewer systems, on-site treatment systems (e.g., septic tanks), truck spills and crashes, background levels of contaminants, urban stormwater runoff, and other non-human sources, such as wildlife and animal feeding operations. It was noted that that because wet weather SSOs have a large stormwater component it is likely that SSOs and CSOs have largely the same constituents.

One expert recommended that EPA attempt to distinguish between human and non-human pathogen sources since the focus of the CSO/SSO Report to Congress is on human sources. Several experts commented on the overall lack of data linking pathogens to incidences of illness in different populations, such as treatment plant workers, children, and subsistence fishers. Another expert noted that basement backups are more hazardous to the occupant because the sewage contains pathogens from many sources.

Significance of the CSO and SSO Problem (p. 26-27)
During the second day of the Experts Workshop, the participants broke into discussion groups and were asked to comment on the actual significance of CSOs and SSOs in the broader public health context. One group of experts indicated that pathogens present in sewage do represent a significant public health threat which in turn supports the rationale for wastewater treatment. Another group indicated that though accurate national estimates do not exist on the relative pathogen contributions of CSOs and SSOs, limited data suggest that overflows contribute only a small portion of the total pathogen load on a national scale. Similarly, this group agreed that few outbreaks are known to have resulted from sewer overflows.

One expert commented that while the elimination of CSOs and SSOs would have a definite public health benefit, it is unlikely that this elimination would result in a measurable reduction in waterborne illnesses because of the difficulty in characterizing such impacts under current measuring and tracking systems. Another participant noted that measuring impacts from CSOs may be easier to pinpoint since most outfall locations are known, while determining impacts from SSOs is more difficult because they occur throughout the sewer system.

Options for Conducting Public Health Research to Support the Current Report to Congress (p. 28-29)
During a subsequent breakout session, the experts discussed ways to estimate the national illness burden resulting from CSOs and SSOs. One of the challenges facing the data collection efforts on health impacts is not knowing the most appropriate parties to interview to gather such information. One commenter noted that existing health-related impacts from overflows are reported to physicians or public health departments mostly as gastrointestinal (GI) illness without specific source attribution. [One estimate of the causes of national GI cases indicated that 75 percent are derived from food-borne illnesses, 10-15 percent are caused by person to person transmission, and only a fraction of a percent are caused by CSOs and SSOs.] Another challenge is that outside of a specific health study most state and local public health departments do not place a high priority on sewage-related illnesses. One expert recommended investigating communities with a history of CSOs and SSOs to determine the kinds of public health impacts reported and linked to overflows.

Assuming available data is collected, another problem EPA faces according to the experts is combining this information to create an estimate of health impacts. The concentration of individual parameters in overflows is largely unknown. One expert suggested estimating overflow constituents indirectly by using the percentage removal of typical pollutants by conventional POTWs. However, even if overflow constituents are known, exposures and dose/response relationships are not, creating difficulties in modeling for the purposes of the report. Another participant noted the significant advances that are being made in genetic fingerprinting of pathogens and the potential for using this technology to better waterborne disease surveillance.

General Discussion (p. 30-31)
In the wrap-up discussion with all participants, the experts were asked how underreporting affects our knowledge of waterborne illness and how such illnesses are tracked. Regarding underreporting, some experts estimated that only 10 percent of water-borne disease outbreaks are reported in the existing data management systems, and even this small percentage ignores the presumed widespread, non-reported illnesses that make up the majority of the national impacts.

Regarding the tracking of waterborne illnesses, no national data set exists for making the connection between sewer overflows and public health impacts because neither the overflows nor the health impacts are measured and reported consistently. Unless, this is remedied, according to several experts, controls for CSO and SSO abatement are unlikely to register reductions in cases of waterborne disease.

AMSA will continue to track the progress of the CSO/SSO Report to Congress and will alert the membership of any developments. For more information, please contact Chris Hornback at 202/833-9106 or chornback@amsa-cleanwater.org.