Grantee Research Project Results

Final Report: Evaluating Microbial Indicators and Health Risks Associated with Bank Filtration

EPA Grant Number: R829785
Title: Evaluating Microbial Indicators and Health Risks Associated with Bank Filtration
Investigators: Frost, Floyd
Institution: Lovelace Clinic Foundation
EPA Project Officer: Page, Angela
Project Period: July 1, 2002 through July 31, 2005 (Extended to June 30, 2006)
Project Amount: $524,840
RFA: Microbial Risk in Drinking Water (2001) RFA Text |  Recipients Lists
Research Category: Drinking Water , Human Health , Water

Objective:

The specific goals of the study are:

1. Identify approaches to collecting sera from similar populations in different geographic locations so rates of serological responses can be compared.
2. Pilot test the approach in three different geographical locations collecting sera from cities that use bank filtration and nearby cities that use high quality ground water for a drinking water source.
3. Analyze the sera for serological responses to Cryptosporidium and Giardia antigens and compare the frequency and intensity of responses between the bank filtration cities and the ground water cities.
4. Compare serological responses in the same cities at times when bank filtration efficacy is likely to be optimal and when it is likely to be least effective.

Summary/Accomplishments (Outputs/Outcomes):

Sera from 50 people from each of three communities (users of bank filtered and chlorinated, bank filtered plus direct filtration plus ozonation and chlorinated ground water) were collected at baseline and at 5 follow-up blood draws.  A questionnaire on risk factors was e collected at each blood draw.  Sera were tested for the presence of antibody responses to two Cryptosporidium antigens (15/17-kDa and 27-kDa) and for serological changes (seroconversion).  The baseline level of serological responses as well as the rates of seroconversion were compared for each population (50 baseline and 250 periods for estimating rates of seroconversion).  Comparisons were adjusted for risk factor data for each individual.

We found evidence that people with a strong baseline serological response at the beginning of the 4-month period to the 15/17 –kDa antigen group had approximately one-third the risk of diarrhea lasting 4 or more days during the next 4-month period.  This indicates that having a strong baseline serological response, especially to the 15/17 –kDa antigen, is related to significant protection during the next 4-month period.  If this protection resulted from a reduced risk of cryptosporidiosis, then it indicates that cryptosporidiosis is likely to be the most important single cause of prolonged diarrhea in these populations.

This study suggests that riverbank filtration may be a safe, reliable alternative to conventional filtration.  In addition to the reduced treatment cost, reliability may be an even more important public health advantage of riverbank filtration.  Rare but large-scale failures of filtration plants, as during the Milwaukee outbreak, are likely to be the greatest threat to public health.  Treatment methods that minimize the risks of large-scale failures, such as riverbank filtration, likely offer significant benefits to the consumer.  In addition to the safety of riverbank-filtered water and the reliability of the treatment processes, an added advantage is a reduced cost of operation.

The evaluation of serological response to Cryptosporidium antigens likely provides a more accurate assessment of the infection risks associated with each site.  It may, therefore, be desirable to evaluate the appropriateness of riverbank filtration using a serological assessment of the site-specific levels of endemic waterborne infection.

Supplemental Keywords:

Water, exposure assessment, Midwest, EPA Region 7;, RFA, Health, Scientific Discipline, PHYSICAL ASPECTS, Geographic Area, Water, Waste, Physical Processes, EPA Region, Risk Assessments, Environmental Chemistry, Contaminated Sediments, Environmental Microbiology, Midwest, Drinking Water, Environmental Monitoring, clostridium, microbial contamination, river water , treatment, contaminated sediment, ecological risk assessment, bank filtration, water quality, microbial risk assessment, microbiological organisms, water quality parameters, human exposure, Region 7, groundwater disinfection, pathogens, monitoring, microbial indicators, drinking water contaminants, drinking water treatment, water treatment, exposure, Giardia, waterborne disease, particle counts, disinfection byproducts, cryptosporidium , disinfection byproducts (DPBs), human health risk, aquifer characteristics, drinking water distribution system, riverbank filtration, exposure and effects

Relevant Websites:

http://www.LCFresearch.org Exit

Progress and Final Reports:

Original Abstract

2003 Progress Report

2004 Progress Report

2005 Progress Report