The disparity between regulatory measurements of E. coli in public bathing waters and the public expectation of bathing water quality

Animal and environmental risk factors for sporadic Shiga toxin-producing Escherichia coli (STEC) infection in England: a case control study for O157, O26 and other STEC serotypes

Most Shiga toxin-producing E. coli (STEC) infections are sporadic. Routine enhanced surveillance questionnaires of confirmed STEC cases in England contained promising data to conduct a case-control study to identify non-food exposures linked to the risk of becoming infected with different STEC serotypes, including O157, O26 and all others; this study pulled eligible cases from the recorded enhanced surveillance data. Controls were recruited from the general population and answered a comparable postal questionnaire. Logistic regression was performed to identify risk factors associated with STEC infection for O157, O26 and other serotype cases. In adjusted models, travel outside of the U.K. and childcare occupations raised the risk of infection for all serotypes. Day trips within the UK, exposure to dogs and contact with soil were linked to lower infection risk. Resident region within England was often linked to decreased risk. Summer season was linked to O157 and O26, but not other STEC. Swimming in the sea was linked to increased risk of infection by O157, but not other types of STEC. Correlations between exposures and infection were similar when the analysis was repeated excluding participants with a history of foreign travel. As the first case-control study in England to include sporadic non-O157 STEC, the varying risk factors between O157 and non-O157 cases suggest there are potentially unique reservoirs for different serotypes.

Self-reported benefits and risks of open water swimming to health, wellbeing and the environment: Cross-sectional evidence from a survey of Scottish swimmers

Engaging with natural environments benefits human health by providing opportunities for social interactions, enhancing mental wellbeing and enabling outdoor spaces for physical exercise. Open water swimming has seen a rapid increase in popularity, partly due to the physical health benefits it can provide but also with the growing interest in (re)connecting with nature for environment-health interactions. Using a national-scale online survey of 717 open water swimmers, the aim of this study was to investigate patterns and trends in the perceived benefits and risks of open water swimming to both public health and the environment; and to understand whether these perceived risks and benefits vary across different typologies of swimmers and open water, or 'blue space', environments. Strong associations were found between the most important self-reported benefit associated with open water swimming and both participant age and the categorisation of their typical swim style. All but one of the age-groups surveyed perceived mental wellbeing benefits to be the most important benefit of open water swimming; whilst those aged over 65 identified physical rather than mental wellbeing benefits to be the most important outcome. Participants who preferred lake swimming reported greater concern regarding possible environmental damage caused by the increasing popularity of open water swimming compared to those engaging in river or sea swimming. However, the majority of participants perceived the risks to the environment from open water swimming to be minimal. Our study adds to the growing evidence that open water swimming is perceived by participants as benefitting their mental and physical wellbeing. Improved understanding of the benefits and risks of engaging with blue spaces used for open water swimming can contribute to co-designed policy development to promote safer, healthier and more sustainable outdoor recreation opportunities associated with this increasingly popular outdoor pursuit.

Recreational water exposures and illness outcomes at a freshwater beach in Toronto, Canada: A prospective cohort pilot study

BACKGROUND

Swimming and other recreational water activities in surface waters are popular in Canada during the summer. However, these activities can also increase the risk of recreational water illness. While routine monitoring of beach water quality is conducted by local authorities each summer, little research is available in Canada about beach exposures and illness risks.

METHODS

We conducted a pilot of a prospective cohort study at a popular beach in Toronto, Ontario, Canada, in 2022 to determine characteristics of beachgoers, common water and sand exposures, the incidence of recreational water illness, and the feasibility for a larger, national cohort study. We enrolled beachgoers on-site and surveyed about their exposures at the beach and conducted a follow-up survey 7 days following their beach visit to ascertain acute gastrointestinal, respiratory, skin, ear, and eye illness outcomes. We descriptively tabulated and summarized the collected data.

RESULTS

We enrolled 649 households, consisting of 831 beachgoers. Water contact activities were reported by 56% of beachgoers, with swimming being the most common activity (44% of participants). Similarly, 56% of beachgoers reported digging in the sand or burying themselves in the sand. Children (≤14 years) and teenagers (15-19 years) were most likely to report engaging in water contact activities and swallowing water, while children were most likely to report sand contact activities and getting sand in their mouth. Boys and men were more likely than women and girls to report swallowing water (15.2% vs. 9.4%). Water and sand exposures also differed by household education level and participant ethno-racial identity. E. coli levels in beach water were consistently low (median = 20 CFU/100 mL, range = 10-58). The incidence of illness outcomes was very low (0.3-2.8%) among the 287 participants that completed the follow-up survey.

CONCLUSIONS

The identified beach exposure patterns can inform future risk assessments and communication strategies. Excellent water quality was observed at the studied beach, likely contributing to the low incidence of illnesses. A larger, national cohort study is needed in Canada to examine risks of illness at beaches at higher risk of fecal contamination.

Is water quality in British rivers "better than at any time since the end of the Industrial Revolution"?

We explore the oft-repeated claim that river water quality in Great Britain is "better now than at any time since the Industrial Revolution". We review available data and ancillary evidence for seven different categories of water pollutants: (i) biochemical oxygen demand (BOD) and ammonia; (ii) heavy metals; (iii) sewage-associated organic pollutants (including hormone-like substances, personal care product and pharmaceutical compounds); (iv) macronutrients (nitrogen and phosphorus); (v) pesticides; (vi) acid deposition and (vii) other variables, including natural organic matter and pathogenic micro-organisms. With a few exceptions, observed data are scarce before 1970. However, we can speculate about some of the major water quality pressures which have existed before that. Point-source pollutants are likely to have increased with population growth, increased connection rates to sewerage and industrialisation, although the increased provision of wastewater treatment during the 20th century will have mitigated this to some extent. From 1940 to the 1990s, pressures from nutrients and pesticides associated with agricultural intensification have increased in many areas. In parallel, there was an increase in synthetic organic compounds with a "down-the-drain" disposal pathway. The 1990s saw general reductions in mean concentrations of metals, BOD and ammonia (driven by the EU Urban Waste Water Treatment Directive), a levelling out of nitrate concentrations (driven by the EU Nitrate Directive), a decrease in phosphate loads from both point-and diffuse-sources and some recovery from catchment acidification. The current picture is mixed: water quality in many rivers downstream of urban centres has improved in sanitary terms but not with respect to emerging contaminants, while river quality in catchments with intensive agriculture is likely to remain worse now than before the 1960s. Water quality is still unacceptably poor in some water bodies. This is often a consequence of multiple stressors which need to be better-identified and prioritised to enable continued recovery.

Sewage-associated plastic waste washed up on beaches can act as a reservoir for faecal bacteria, potential human pathogens, and genes for antimicrobial resistance

Sewage-associated plastic wastes, such as wet wipes and cotton bud sticks, commonly wash up on beaches; however, it is unclear whether this represents a public health risk. In this study, sewage-associated plastic waste, and naturally occurring substrates (seaweed and sand), were collected from ten beaches along the Firth of Forth estuary (Scotland, UK) and analysed using selective media for the faecal indicator organisms (FIOs) E. coli and intestinal enterococci (IE), and potential human pathogens (Vibrio spp.). Minimum inhibitory concentration (MIC) analysis was used to determine antibiotic resistance in selected strains. FIOs and Vibrio were more often associated with wet wipes and cotton bud sticks than with seaweed, and there was evidence of resistance to several antibiotics. This work demonstrates that plastics associated with sewage pollution can facilitate the survival and dissemination of FIOs and Vibrio and thus, could present an as yet unquantified potential risk to human health at the beach.

A baseline study of spatial variability of bacteria (total coliform, E. coli, and Enterococcus spp.) as biomarkers of pollution in ten tropical Atlantic beaches: concern for environmental and public health

Coastal water quality in urban cities is increasingly impacted by human activities such as agricultural runoff, sewage discharges, and poor sanitation. However, environmental factors controlling bacteria abundance remain poorly understood. The study employed multiple indicators to assess ten beach water qualities in Ghana during minor wet seasons. Environmental parameters (e.g. temperature, electrical conductivity, total dissolved solids) were measured in situ using the Horiba multiple parameter probe. Surface water samples were collected to measure total suspended solids, nutrients, and chlorophyll-a via standard methods and bacteria determination through membrane filtration. Environmental parameters measured showed no significant variation for the sample period. However, bacteria loads differ significantly (p = 0.024) among the beaches and influenced significantly by nitrate (55.3%, p = 0.02) and total dissolved solids (17.1%, p = 0.017). The baseline study detected an increased amount of total coliforms and faecal indicator bacteria (Escherichia coli and Enterococcus spp.) in beach waters along the coast of Ghana, suggesting faecal contamination, which can pose health risks. The mean ± standard deviations of bacteria loads in beach water are total coliforms (4.06 × 10³ ± 4.16 × 10³ CFU/100 mL), E. coli (7.06 × 10² ± 1.72 × 10³ CFU/100 mL), and Enterococcus spp. (6.15 × 10² ± 1.75 × 10³ CFU/100 mL). Evidence of pollution calls for public awareness to prevent ecological and health-related risks and policy reforms to control coastal water pollution. Future research should focus on identifying the sources of contamination in the tropical Atlantic region.

Indexes for the assessment of bacterial pollution in bathing waters from point sources: The northern Adriatic Sea CADEAU service

This paper presents a novel set of water quality indexes to identify the area potentially affected by point sources of bacterial pollution in coastal bathing waters. The indexes, developed in the framework of the CADEAU service, are evaluated on the results of a modelling system based on the integration of a high-resolution ocean model, remote sensing observations and in situ monitoring data for the northern Adriatic Sea. In particular, the system is a downscaling of the Mediterranean Copernicus Marine Environment Monitoring Service and exploits data produced within the Bathing Waters Directive, the Water Framework Directive and the Urban Waste Water Treatment Directive to create added value products. The aim of the proposed indexes is to support the identification of areas of influence for bathing waters by identifying the potential threat from point sources of bacterial pollution, both in standard conditions and peculiar events such as a total bypass of wastewater treatment plants. The results for the Chioggia Municipality case study show the potential of the indexes to significantly improve the geographical identification and quantitative evaluation of the impacts of bacterial pollution sources on bathing waters, facilitating the design of mitigation measures. The proposed methodology represents a new management approach to support local authorities in defining the area of influence within the water bathing profile through the proper characterization of the point sources of bacterial pollution.

Bathing Water Quality Monitoring Practices in Europe and the United States

Many countries including EU Member States (EUMS) and the United States (U.S.) regularly monitor the microbial quality of bathing water to protect public health. This study comprehensively evaluates the EU bathing water directive (BWD) and the U.S. recreational water quality criteria (RWQC) as regulatory frameworks for monitoring microbial quality of bathing water. The major differences between these two regulatory frameworks are the provision of bathing water profiles, classification of bathing sites based on the pollution level, variations in the sampling frequency, accepted probable illness risk, epidemiological studies conducted during the development of guideline values, and monitoring methods. There are also similarities between the two approaches given that both enumerate viable fecal indicator bacteria (FIB) as an index of the potential risk to human health in bathing water and accept such risk up to a certain level. However, enumeration of FIB using methods outlined within these current regulatory frameworks does not consider the source of contamination nor variation in inactivation rates of enteric microbes in different ecological contexts, which is dependent on factors such as temperature, solar radiation, and salinity in various climatic regions within their geographical areas. A comprehensive "tool-box approach", i.e., coupling of FIB and viral pathogen indicators with microbial source tracking for regulatory purposes, offers potential for delivering improved understanding to better protect the health of bathers.