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Journal of Water and Health Vol 07 No 4 pp 623–629 © IWA Publishing 2009 doi:10.2166/wh.2009.115

Hand–mouth transfer and potential for exposure to E. coli and F+ coliphage in beach sand, Chicago, Illinois

Richard L. Whitman, Katarzyna Przybyla-Kelly, Dawn A. Shively, Meredith B. Nevers and Muruleedhara N. Byappanahalli

United States Geological Survey, Great Lakes Science Center, Lake Michigan Ecological Research Station, 1100 N. Mineral Springs Road, Porter IN, 46304, USA Tel.: +1 219-926-8336 ext. 424 Fax: +1 219-929-5792 E-mail: rwhitman@usgs.gov


ABSTRACT

Beach sand contains fecal indicator bacteria, often in densities greatly exceeding the adjacent swimming waters. We examined the transferability of Escherichia coli and F+ coliphage (MS2) from beach sand to hands in order to estimate the potential subsequent health risk. Sand with high initial E. coli concentrations was collected from a Chicago beach. Individuals manipulated the sand for 60 seconds, and rinse water was analysed for E. coli and coliphage. E. coli densities transferred were correlated with density in sand rather than surface area of an individual's hand, and the amount of coliphage transferred from seeded sand was different among individuals. In sequential rinsing, percentage reduction was 92% for E. coli and 98% for coliphage. Using dose-response estimates developed for swimming water, it was determined that the number of individuals per thousand that would develop gastrointestinal symptoms would be 11 if all E. coli on the fingertip were ingested or 33 if all E. coli on the hand were ingested. These results suggest that beach sand may be an important medium for microbial exposure; bacteria transfer is related to initial concentration in the sand; and rinsing may be effective in limiting oral exposure to sand-borne microbes of human concern.

Keywords: beach sand; coliphage; Escherichia coli; hand to mouth transfer; recreational waters; risk assessment


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