Research Areas > Beach Water Quality > Epidemiology Studies

Research Area: Epidemiology Studies

Epidemiology studies are used to identify if swimmers are at risk of developing illnesses based on water contact recreation. Historically, these studies have been conducted infrequently, predominantly at freshwater beaches with known sources of human fecal contamination. The largest benefit from these studies is the identification of relationships between the frequency of illness and levels of fecal indicator bacteria such as total coliforms, fecal coliforms or E. coli, and enterococcus. Such knowledge helps shoreline managers to make appropriate decisions about beach closures and other management measures based on measures of feacl indicator bacteria.
 

SCCWRP Research

Epidemiology studies conducted by SCCWRP address at least two outstanding issues. The first involves potential differences in health risk due to contamination from point source versus nonpoint source discharges. Point sources typically consist of a single predominant source of largely human-derived fecal contamination, while nonpoint sources typically consist of numerous smaller sources, sometimes entirely nonhuman and partially non-fecal in origin. The second involves the application of new water quality indicators. Recent advances in technology have improved indicator measurement methods producing new methods that are more human specific and quite rapid (< 2 hours). Before shoreline managers use any of these new methods or indicators for making decisions regarding risk to swimmers, they need to be tested in an epidemiological study to assess their correlation with actual illness rates.

SCCWRP is currently conducting epidemiological studies to assess the risk of swimming-related illnesses following exposure to nonpoint source contaminated waters at three beaches: Doheny Beach in Dana Point, Avalon Bay Beach on Santa Catalina Island and Surfrider Beach in Malibu. These studies will examine several new techniques for measuring traditional fecal indicator bacteria, new species of bacteria, and viruses to determine whether they yield a better relationship to human health outcomes than the indicators presently used in California.

Significant epidemiology projects include:

• Mission Bay Epidemiological Study
• California Epidemiological Studies