An alternative approach to water regulations for public health protection at bathing beaches

New approaches should be considered as the US Environmental Protection Agency (EPA) moves rapidly to develop new beach monitoring guidelines by the end of 2012, as these guidelines serve as the basis by which states and territories with coasts along the oceans and Great Lakes can then develop and implement monitoring programs for recreational waters. We describe and illustrate one possible approach to beach regulation termed as the "Comprehensive Toolbox within an Approval Process (CTBAP). " The CTBAP consists of three components. The first is a "toolbox" consisting of an inventory of guidelines on monitoring targets, a series of measurement techniques, and guidance to improve water quality through source identification and prevention methods. The second two components are principles of implementation. These include first, "flexibility" to encourage and develop an individualized beach management plan tailored to local conditions and second, "consistency" of this management plan to ensure a consistent national level of public health protection. The results of this approach are illustrated through a case study at a wellstudied South Florida recreational marine beach. This case study explores different monitoring targets based on two different health endpoints (skin versus gastrointestinal illness) and recommends a beach regulation program for the study beach that focuses predominately on source prevention

Shedding of Staphylococcus aureus and methicillin-resistant Staphylococcus aureus from adult and pediatric bathers in marine waters

<p>Abstract</p> <p>Background</p> <p><it>Staphylococcus aureus </it>including methicillin resistant <it>S. aureus</it>, MRSA, are human colonizing bacteria that commonly cause opportunistic infections primarily involving the skin in otherwise healthy individuals. These infections have been linked to close contact and sharing of common facilities such as locker rooms, schools and prisons Waterborne exposure and transmission routes have not been traditionally associated with <it>S. aureus </it>infections. Coastal marine waters and beaches used for recreation are potential locations for the combination of high numbers of people with close contact and therefore could contribute to the exposure to and infection by these organisms. The primary aim of this study was to evaluate the amount and characteristics of the shedding of methicillin sensitive <it>S. aureus</it>, MSSA and MRSA by human bathers in marine waters.</p> <p>Results</p> <p>Nasal cultures were collected from bathers, and water samples were collected from two sets of pools designed to isolate and quantify MSSA and MRSA shed by adults and toddlers during exposure to marine water. A combination of selective growth media and biochemical and polymerase chain reaction analysis was used to identify and perform limited characterization of the <it>S. aureus </it>isolated from the water and the participants. Twelve of 15 MRSA isolates collected from the water had identical genetic characteristics as the organisms isolated from the participants exposed to that water while the remaining 3 MRSA were without matching nasal isolates from participants. The amount of <it>S. aureus </it>shed per person corresponded to 10⁵to 10⁶CFU per person per 15-minute bathing period, with 15 to 20% of this quantity testing positive for MRSA.</p> <p>Conclusions</p> <p>This is the first report of a comparison of human colonizing organisms with bacteria from human exposed marine water attempting to confirm that participants shed their own colonizing MSSA and MRSA into their bathing milieu. These findings clearly demonstrate that adults and toddlers shed their colonizing organisms into marine waters and therefore can be sources of potentially pathogenic <it>S. aureus </it>and MRSA in recreational marine waters. Additional research is needed to evaluate recreational beaches and marine waters as potential exposure and transmission pathways for MRSA.</p

Development of a water quality model which incorporates non-point microbial sources

Traditionally monitoring the sanitation of recreational coastal waters has been regulated by measuring concentrations of fecal indicator bacteria (E. coli, fecal coliforms, and enterococci). The bacteria utilized are those typically found in human feces in high concentrations. Recently the use of fecal indicator bacteria to monitor and regulate the recreational use of coastal waters has come into question, particularly in the tropical and sub-tropical marine environment (e.g., Hawaii, Guam, Puerto Rico, and South Florida) where the non-point sources (i.e. beach sand and/or sediment, animals, run-off water, and bathers) are the dominant fecal bacteria input source. In addition, little work has been done in the area of recreational water quality modeling, especially water quality models that incorporate non-point sources of fecal bacteria indicators to predict the bacterial loading in the water column.The primary objective of this dissertation was to characterize and quantify non-point sources of enterococci at a marine beach, Hobie Cat Beach, located in Miami-Dade County, Florida. This information will be incorporated into a water quality model to evaluate the relative importance of each of the non-point sources of enterococci. In order to achieve this objective, two main tasks were completed and discussed.The first task focused on estimating the concentrations of enterococci and Staphylococcus aureus shed directly off the skin of bathers and the amount of beach sand and the corresponding concentration of enterococci that can be transported by bathers into the water column. Enterococci, a common fecal indicator, and Staphylococcus aureus, a common skin pathogen, can be shed by bathers affecting the quality of recreational waters and resulting in possible human health impacts. Two sets of field studies were conducted at Hobie Cat Beach. The first study, referred to as the Large Pool study, involved 10 volunteers who immersed their bodies in a 4700 liter inflatable plastic pool filled with off-shore marine water during four 15 minute cycles with exposure to beach sand in cycles 3 and 4. The second study, referred to as the Small Pool study involved 10 volunteers who were exposed to beach sand for 30 minutes before they individually entered a small tub. After each individual was rinsed with offshore marine water, sand and rinse water were collected and analyzed for enterococci. Results from the Large Pool study showed that bathers shed concentrations of enterococci and S. aureus on the order of 6x105 and 6x106 colony forming units per person in the first 15 minute exposure period, respectively. Significant reductions in the bacteria shed per bather (50% reductions for S. aureus and 40% for enterococci) were observed in the subsequent bathing cycles. The Small Pool study results indicated that the enterococci contribution from sand adhered to skin was small (about 2% of the total) in comparison with the amount shed directly from the bodies of the volunteers.The second task focused on developing the algorithms for simulating non-point sources of enterococci specific to the study site including sand, dogs, birds, water runoff, and bathers, and the application of the developed algorithms to quantify the enterococci loads associated with each one of the sources. The five dominant non-point sources of enterococci were described and expressed as mathematical equations along with their variables. Estimates for all variables were defined and computed using the most recent literature, studies and direct field measurements values. The task showed that water runoff is the most significant non-point source contributing enterococci into the water column followed by dogs, sand, birds, and bathers respectively.Overall this dissertation suggests that non-point sources of fecal bacteria indicators contribute significant amounts of enterococci into the water column and they should thus be considered when designing water quality models. Regulatory beach monitoring programs should include site specific predictive water quality models in order to assess the sanitation of coastal recreational water bodies

Monitoring marine recreational water quality using multiple microbial indicators in an urban tropical environment

The microbial water quality at two beaches, Hobie Beach and Crandon Beach, in Miami-Dade County, Florida, USA was measured using multiple microbial indicators for the purpose of evaluating correlations between microbes and for identifying possible sources of contamination. The indicator microbes chosen for this study (enterococci, Escherichia coli, fecal coliform, total coliform and C. perfringens) were evaluated through three different sampling efforts. These efforts included daily measurements at four locations during a wet season month and a dry season month, spatially intensive water sampling during low- and high-tide periods, and a sand sampling effort. Results indicated that concentrations did not vary in a consistent fashion between one indicator microbe and another. Daily water quality frequently exceeded guideline levels at Hobie Beach for all indicator microbes except for fecal coliform, which never exceeded the guideline. Except for total coliform, the concentrations of microbes did not change significantly between seasons in spite of the fact that the physical–chemical parameters (rainfall, temperature, pH, and salinity) changed significantly between the two monitoring periods. Spatially intense water sampling showed that the concentrations of microbes were significantly different with distance from the shoreline. The highest concentrations were observed at shoreline points and decreased at offshore points. Furthermore, the highest concentrations of indicator microbe concentrations were observed at high tide, when the wash zone area of the beach was submerged. Beach sands within the wash zone tested positive for all indicator microbes, thereby suggesting that this zone may serve as the source of indicator microbes. Ultimate sources of indicator microbes to this zone may include humans, animals, and possibly the survival and regrowth of indicator microbes due to the unique environmental conditions found within this zone. Overall, the results of this study indicated that the concentrations of indicator microbes do not necessarily correlate with one another. Exceedence of water quality guidelines, and thus the frequency of beach advisories, depends upon which indicator microbe is chosen

Microbial load from animal feces at a recreational beach

The goal of this study was to quantify the microbial load (enterococci) contributed by the different animals that frequent a beach site. The highest enterococci concentrations were observed in dog feces with average levels of 3.9×107CFU/g; the next highest enterococci levels were observed in birds averaging 3.3×105CFU/g. The lowest measured levels of enterococci were observed in material collected from shrimp fecal mounds (2.0CFU/g). A comparison of the microbial loads showed that 1 dog fecal event was equivalent to 6940 bird fecal events or 3.2×108 shrimp fecal mounds. Comparing animal contributions to previously published numbers for human bather shedding indicates that one adult human swimmer contributes approximately the same microbial load as one bird fecal event. Given the abundance of animals observed on the beach, this study suggests that dogs are the largest contributing animal source of enterococci to the beach site

Trends in regional enterococci levels at marine beaches and correlations with environmental, global oceanic changes, community populations, and wastewater infrastructure

An increase in the number of advisories issued for recreational beaches across south Florida (due to the fecal indicator bacteria, enterococci) has been observed in recent years. To evaluate the possible reasons for this increase, we reviewed weekly monitoring data for 18 beaches in Miami-Dade County, Florida, for the years 2000–2019. Our objective was to evaluate this dataset for trends in enterococci levels and correlations with various factors that might have influenced enterococci levels at these beaches. For statistical analyses, we divided the 20-year period of record into 5-year increments (2000–2004, 2005–2009, 2010–2014, and 2015–2019). The Wilcoxon rank sum test was used to identify statistically significant differences between the geometric mean of different periods. When all 18 beaches were collectively considered, a significant increase (p = 0.03) in enterococci was observed during 2015–2019, compared to the prior 15-year period of record. To better understand the potential causes for this increase, correlations were evaluated with environmental parameters (rainfall, air temperature, and water temperature), global oceanic changes (sea level and Sargassum), community populations (county population estimates and beach visitation numbers), and wastewater infrastructure (sewage effluent flow rates to ocean outfalls and deep well injection). In relation to the enterococci geometric mean, the correlation with Sargassum was statistically significant at a 95% confidence interval (p = 0.035). Population (p = 0.078), air temperature (p = 0.092), and sea level (p = 0.098) were statistically significant at 90% confidence intervals. Rainfall, water temperature, beach visitation numbers, and sewage effluent flow rates via deep well injection had positive correlations but were not significant factors. Sewage effluent flow rates to ocean outfalls had a negative correlation. [Display omitted] •Enterococci bacteria were evaluated for trends over 20 years.•Levels were observed to increase systematically across 18 beaches.•The increase was observed during the last five years.•The highest correlation was with Sargassum volumes.•Significant correlations were observed with sea level, population, and air temperature

Risk Assessment for Children Exposed to Arsenic on Baseball Fields with Contaminated Fill Material

Children can be exposed to arsenic through play areas which may have contaminated fill material from historic land use. The objective of the current study was to evaluate the risk to children who play and/or spend time at baseball fields with soils shown to have arsenic above background levels. Arsenic in soils at the study sites located in Miami, FL, USA showed distinct distributions between infield, outfield, and areas adjacent to the fields. Using best estimates of exposure factors for children baseball scenarios, results show that non-cancer risks depend most heavily upon the age of the person and the arsenic exposure level. For extreme exposure scenarios evaluated in this study, children from 1 to 2 years were at highest risk for non-cancer effects (Hazard Quotient, HQ > 2.4), and risks were higher for children exhibiting pica (HQ > 9.7) which shows the importance of testing fill for land use where children may play. At the study sites, concentration levels of arsenic resulted in a range of computed cancer risks that differed by a factor of 10. In these sites, the child's play position also affected risk. Outfield players, with a lifetime exposure to these arsenic levels, could have 10 times more increased chance of experiencing cancers associated with arsenic (i.e., lung, bladder, skin) in comparison to infielders. The distinct concentration distributions observed between these portions of the baseball fields emphasize the need to delineate contaminated areas in public property where citizens may spend more free time. This study also showed a need for more tools to improve the risk estimates for child play activities. For instance, more refined measurements of exposure factors for intake (e.g., inhalation rates under rigorous play activities, hand to mouth rates), exposure frequency (i.e., time spent in various activities) and other exposure factors (e.g., soil particulate emission rates at baseball play fields) can help pinpoint risk on baseball fields where arsenic levels may be a concern

Quantitative evaluation of enterococci and Bacteroidales released by adults and toddlers in marine water

Traditionally, the use of enterococci has been recommended as the fecal indicator bacteria of choice for testing marine recreational water quality, and prior studies have shown that bathers shed large numbers of enterococci into the water. The current study expands upon prior research by evaluating shedding from both toddlers and adults, and by the expansion of measurements to include enterococci shedding via three different methods (membrane filter (MF), chromogenic substrate (CS), and quantitative polymerase chain reaction (qPCR)) and shedding of alternative fecal indicator bacteria (Bacteroidales human markers UCD and HF8 via qPCR). Two sets of experiments were conducted. The first experiment consisted of two groups of 10 adults who bathed together in a large pool. The second study consisted of 14 toddlers who bathed individually in a small pool which allowed for sand recovery. Sand recovery was used to estimate the amount of sand transported on the bodies of toddlers and to estimate the number of fecal indicator bacteria released from this sand. The numbers of estimated enterococci shed per adult ranged from 1.8×104 to 2.8×106 CFU, from 1.9×103 to 4.5×106 MPN, and from 3.8×105 to 5.5×106 GEU based on the MF, CS, and qPCR methods, respectively. The estimated numbers of Bacteroidales human markers ranged from 1.8×104 to 1.3×106 for UCD, and ranged from the below detection limit to 1.6×105 for HF8. The estimated amount of sand transported per toddler (n=14) into the water column after sand exposure was 8±6g on average. When normalizing the numbers of enterococci shed from toddlers via sand by the 3.9 body surface area ratio, the differences between toddlers and adults were insignificant. Contributions of sands to the total enterococci (MF) shed per toddler was 3.7±4.4% on average. Although shedding via beach sand may contribute a small fraction of the microbial load during initial bathing, it may have a significant role if bathers go to water repetitively after sand exposure