Evaluating Microbial Indicators and Health Risks Associated with Bank FiltrationEPA Grant Number: R829785
Title: Evaluating Microbial Indicators and Health Risks Associated with Bank Filtration
Investigators: Frost, Floyd , Kunde, Twila
Current 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 , Water , Health Effects
Description:The study design will be a prospective two-year study during which sera and water quality data will be collected from several sites in the Midwest where drinking water is derived from three types of sources. Site A is a city of 225,000 with an economy based on agriculture, education, and government employment. Site A uses bank-filtered drinking water obtained from a surface source. The water is directly filtered, chlorinated, and ozonated. Site B is a city of 25,000 that uses bank-filtered water from the same surface source that is chlorinated, and receives no additional water treatment. Site Bs economy is based primarily on agriculture. The city is located approximately 80 miles west of Site A. A series of small towns around Site A will be used as ground water cities. Each community obtains ground water from wells that are sufficiently distant from a surface water body that it is deemed not to be under the direct influence of surface water. There are two communities that comprise Site C are located east of Site A.
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) will be collected at baseline and at 5 follow-up blood draws. A questionnaire on risk factors will be collected at each blood draw. Sera will be 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 will be compared for each population (50 baseline and 250 periods for estimating rates of seroconversion) for each population. Comparisons will adjust for collected risk factor data from each individual. For purposes of extrapolating these results to other locations, a series of source and finished water quality indicators will be measured for each water source.
Although the absence of oocysts in the finished water might be considered an indicator of safe water, oocyst detection methods are unreliable. This study will compare rates of infection in the user populations for three source/treatment groups. This approach can more accurately identify increased risks of waterborne Cryptosporidium transmission than oocyst detection. Source water will be characterized for indicators of microbial organisms and removal of pathogens. Particle sizes distributions before and after bank filtration will also be characterized. In prior studies, increased risks of infection have not been related to increased risk of illness; however, the increased risks of infection indicate that viable oocysts have passed through the treatment plant. This study will have the power to detect a difference in the seroconversion between bank filtered and other water systems of 10%, less than differences in serconversion rates seen in earlier studies of surface versus ground water users.