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MEASUREMENTS OF FECAL CONTAMINATION IN RECREATIONAL WATERS BY NEW RAPID METHODS AND THEIR RELATIONSHIPS TO HEALTH ENDPOINTS
The objectives of this research are: (1) to evaluate rapid state-of-the-art measuement methods of pathogens that may indicate the presence of fecal pollution in recreational waters (beaches); (2) to obtain, jointly with a sister laboratory (NHEERL), a new set of water quality data and related health effects data at a variety of beaches across the U.S., in both marine and non-marine waters; (3) to analyze the research data set to evaluate the utility of the tested measurement methods, the new EMPACT monitoring protocol, and the health effects data / questionnaire, in order to establish a relationship between measured pathogens and observed health effects; and (4) to communicate the results to the Office of Water in support of their efforts to develop new state and/or federal guidelines and limits for water quality indicators of fecal contamination, so that beach managers and public health officials can alert the public about the potential health hazards before exposure to unsafe water can occur.
The original EPA recreational water health studies, initiated in 1972 and completed in 1982, were designed to determine the relationship between swimming-associated gastroenteritis and the quality of the bathing water. The water quality was measured using multiple microbial indicators of fecal contamination, including bacteria known to be associated with feces, the skin's surface, and nutrient pollution. Health endpoints were measured as self-reported symptoms or illness from both swimmers (defined as bathers who submersed their head beneath the water surface) and non-swimming controls. Health data were collected on weekends to maximize the swimmer population available, and the swimming-associated gastrointestinal rates for marine and fresh water were calculated by subtracting the illness rate in non-swimmers from the illness rate in swimmers for each type of water. Regression analysis was used to determine the "best" correlations between the microbial indicators and the health data (i.e., those linear relationships where gastrointestinal symptoms or illness rates increased as the water quality indicator densities increased). The data showed that enterococci were correlated with illness rates in both marine and fresh water, while Escherichia coli were correlated in fresh water only, and fecal coliforms showed no correlation with illness rates at all. The mathematical expression of the relationship of unfavorable health effects among swimmers to the quality of water was utilized by the USEPA Office of Water to develop water quality risk limits or guidelines, which were later used by the States to develop water quality standards. However, these health studies used the old water monitoring protocol, based on the geometric mean of five samples per month, and methods which required at least 24 hours for results to become available. If the water was not in compliance with the standard, the risk of exposure to enteric pathogens had potentially occurred long before the quality of the water was identified as being hazardous.
More recent legislation and Agency action plans, including the Clean Water Action Plan, the Beach Action Plan, and the Beach Act of 2000, have identified new requirements to protect recreational waters and people's health. To meet these requirements, a new exposure-health study, conducted jointly by NERL and NHEERL, is being conducted to obtain the relationships between exposures and health impact that are needed for the Office of Water to formulate new health and risk guidelines for recreational water. This task describes NERL's contribution to the exposure component of the joint research effort -- using the new monitoring protocol developed in the EMPACT study and several newly developed rapid methods or those that are currently under evaluation and/or validation. Use of the new health guidelines will allow beach managers and public health officials to alert the public about the potential health hazards before exposure to unsafe water can occur.