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A FASTER METHOD OF MEASURING RECREATIONAL WATER QUALITY FOR BETTER PROTECTION OF SWIMMER'S HEALTH
Citation:
WADE, T. J., R. L. CALDERON, E. A. SAMS, M. BEACH, K. P. BRENNER, AND A. P. DUFOUR. A FASTER METHOD OF MEASURING RECREATIONAL WATER QUALITY FOR BETTER PROTECTION OF SWIMMER'S HEALTH. Presented at International Society for Environmental Epidemiology Annual Meeting, Paris, FRANCE, September 02 - 06, 2006.
Description:
Introduction
Fecal indicator bacteria (FIB) are used to monitor recreational water quality worldwide. Current methods of measuring FIB require at least 24-hours for visible bacterial colonies to grow. We previously reported that a faster method (< 2 hours) of measuring FIB, based on Quantitative Polymerase Chain Reaction (QPCR), was associated with gastrointestinal illness among swimmers. Using data from two additional beaches studied in 2004, we examined the relationship between water quality and other illnesses (rash, earache, eye irritations, upper respiratory illness) and determined whether sensitive subgroups, such as children, were at an increased risk following exposure.
Methods
During the summers of 2003 and 2004, we enrolled and surveyed beachgoers at four Great Lakes Beaches. Ten to twelve days later, we telephoned participants to determine the incidence of new illnesses since the beach visit. We also collected 18 water samples per day at specified locations and tested them for Enterococcus sp. using QPCR. We used regression models to evaluate the relationship between Enterococcus cell equivalents (CE) and illness. Models accounted for factors such as age, sex, other swimming exposures, health status, and meteorological and environmental conditions. We conducted separate analyses by age group and beach.
Results
We completed 21,105 interviews with beachgoers. Swimmers had a higher incidence of rash (RR=1.38, 95% CI=1.12-1.72), earache (RR=1.63, 95% CI=1.23-2.17) and gastrointestinal illness (RR=1.44, 95% CI=1.27-1.64). Gastrointestinal illness was positively associated with the daily and 8:00 AM Enterococcus cell equivalent (CE) average. Each 1-log increase in the daily average Enterococcus CE, was associated with 20 excess cases of gastrointestinal illness per 1000 swimmers (95% CI=5-34/1000). Among children 10 and under, there was a stronger relationship (AR=48/1000 95%CI= 21-76/1000). The relationship between rash and Enterococcus QPCR CE was slightly elevated, but was not consistent across all four beaches.
Discussion and Conclusions
A faster method of measuring water quality will protect public health and increase the efficiency of beach monitoring programs. These studies demonstrated that one such method, Enterococcus QPCR, is related to swimming-associated gastrointestinal illness. We further demonstrated an increased sensitivity to exposure among children. Children may be more likely to swallow more water, or transfer water from their hands to their mouth, or be more sensitive to gastrointestinal pathogens. Future work will include epidemiologic studies at marine beach sites.
This is an abstract of a proposed presentation and does not necessarily reflect EPA policy.