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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. [ABSTRACT FROM AUTHOR]

Recreational water use is an important source of human enteric illness. Enhanced (episodic) surveillance of natural recreational waters as a supplement to beach monitoring can enrich our understanding of human health risks. From 2011 to 2013, water sampling was undertaken at recreational sites on a watershed in eastern Canada. This study compared the prevalence and associations of human enteric pathogens and fecal indicator organisms. Beach water samples had lower pathogen presence than those along the main river, due to different pollution sources and the hydrological disposition. Pathogen profiles identified from the beach sites suggested a more narrow range of sources, including birds, indicating that wild bird management could help reduce public health risks at these sites. The presence and concentration of indicator organisms did not differ significantly between beaches and the river. However, higher concentrations of generic Escherichia coli were observed when Salmonella and Cryptosporidium were present at beach sites, when Salmonella was present at the river recreational site, and when verotoxigenic E. coli were present among all sites sampled. In this watershed, generic E. coli concentrations were good indicators of potential contamination, pathogen load, and elevated human health risk, supporting their use for routine monitoring where enhanced pathogen testing is not possible. [ABSTRACT FROM AUTHOR]

Woodchips in stand-off pads for wintering cows have been applied in countries like Ireland and New Zealand. Their primary role is to protect soils by effectively filtering nutrients during wet conditions, while ensuring a healthy and comfortable environment for the cows. The stand-off pad concept has the potential to be adopted in Canada to provide year-long outdoor access to tie-stall dairy cows. The objective of this study was to evaluate the effect of alternative filtering materials and bed aeration under controlled laboratory conditions. Twelve biofilter columns (0.3 m in diameter and 1-m high) were installed in 12 environmentally-controlled chambers (1.2-m wide by 2.4-m long), and divided into four treatments: a bed of conventional woodchips or an alternative mix of organic materials (sphagnum peat moss, woodchips and biochar) with and without aeration (flux rate set at 0.6 m3/min/m2). Approximately 0.6 L of semi-synthetic dairy manure and 1 L of tap water were poured on the biofilters during two experimental periods of 4 weeks, simulating the effect of either winter or summer conditions (room temperature below or over 10 °C) on the retention of nutrients and fecal bacteria. Results showed that the alternative biofilters under both summer and winter conditions were more efficient in removing COD, SS, TN, and NO 3 –N than conventional biofilters (maximum efficiencies of 97.6%, 99.7%, 96.4%, and 98.4%, respectively). Similarly for E. coli , they achieved a minimum concentration of 1.8 Log 10 CFU/100 ml. Conventional biofilters were more efficient for PO 4 –P removal with a maximum efficiency of 88.2%. Aeration did not have any significant effect under the tested temperature conditions. Additional factors such as media adaptation time as well as aeration flow during this period should be considered. • Stand-off pads have the potential to be adopted in Canada to provide year-long outdoor access to tie-stall dairy cows. • A filtering mixture of sphagnum peat moss, woodchips and biochar was more efficient in filtration capacities. • Woodchip filters showed to have greater phosphorus removal. • Aeration did not improve filtration capacities of filters. [ABSTRACT FROM AUTHOR]

Microbial source tracking (MST) technology represents an innovative approach employed to trace fecal contamination in environmental water systems. The performance of primers may be affected by amplification techniques, target primer categories, and regional differences. To investigate the influence of these factors on primer recognition performance, a meta-analysis was conducted on the application of MST in water environments using three databases: Web of Science, Scopus, and PubMed (n = 2291). After data screening, 46 studies were included in the final analysis. The investigation encompassed Polymerase Chain Reaction (PCR)/quantitative PCR (qPCR) methodologies, dye-based (SYBR)/probe-based (TaqMan) techniques, and geographical differences of a human host-specific (HF183) primer and other 21 additional primers. The results indicated that the primers analyzed were capable of differentiating host specificity to a certain degree. Nonetheless, by comparing sensitivity and specificity outcomes, it was observed that virus-based primers exhibited superior specificity and recognition capacity, as well as a stronger correlation with human pathogenicity in water environments compared to bacteria-based primers. This finding highlights an important direction for future advancements. Moreover, within the same category, qPCR did not demonstrate significant benefits over conventional PCR amplification methods. In comparing dye-based and probe-based techniques, it was revealed that the probe-based method's advantage lay primarily in specificity, which may be associated with the increased propensity of dye-based methods to produce false positives. Furthermore, the heterogeneity of the HF183 primer was not detected in China, Canada, and Singapore respectively, indicating a low likelihood of regional differences. The variation among the 21 other primers may be attributable to regional differences, sample sources, detection techniques, or alternative factors. Finally, we identified that economic factors, climatic conditions, and geographical distribution significantly influence primer performance. [Display omitted] • Meta-analysis for primers and impact factors to their recognition performance. • Viruses-based primers showed a better specificity and recognition ability. • Regional differences of HF183 was not observed in China, Canada, and Singapore. • The influence factors from sample to environment of 21 primers had been listed. • Meta-analysis of economy, climate, and geographic zone on the primers. [ABSTRACT FROM AUTHOR]

A 2016/2017 outbreak of Shiga toxin-producing Escherichia coli (STEC) O121 in Canada, was linked to wheat flour, milled at a single facility on three consecutive days in October 2016. Most Probable Number (MPN) estimates of the concentration of STEC O121 in the recalled flour were made using the results of qualitative testing conducted during the outbreak investigation and from analysis of 5 × 2.5 g, 5 × 25 g and 5 × 100 g analytical units of the recalled flour. The STEC O121 levels were estimated at 0.15 to 0.43 MPN/100 g, with no significant difference between production days and the two MPN estimates. The microbiota of the recalled flour, and eight retail flour samples, was enumerated by aerobic colony count, MacConkey agar and E. coli /Coliform petrifilm. The composition of the microbiota to a genus level was determined by identifying individual colonies with a Bruker Biotyper. All retail flour samples were negative for STEC in 5 × 100 g analytical units. There was no evidence of higher levels of organisms associated with fecal contamination in the recalled flour. The low levels of STEC O121 in the recalled flour indicate that a robust sampling plan, with multiple analytical units for a total of several hundred grams, may be required to reliably detect STEC in flour at levels observed in this outbreak. • Wheat flour was implicated in an outbreak of Shiga toxin-producing E. coli O121. • STEC O121 levels in the flour were estimated at 0.15 to 0.43 MPN/100 g. • The composition of the microbiota with STEC negative retail samples was compared. • No evidence of increased contamination with fecal associated organisms was found. [ABSTRACT FROM AUTHOR]

• High resolution imagery are used to link landscape indicators with water quality. • Imagery at 5 m resolution was optimal for assessing impervious surfaces. • Dissolved oxygen and fecal coliform were well explained by indicators. • Configurational indicators at riparian zone level were important. Urban streams are subject to a myriad of complex stressors associated with impervious surfaces, which impact delivery of pollutants. Landscape indicators (e.g. the amount and arrangement of land cover) are widely used to help monitor water quality, yet their application in highly urbanized settings remains poorly understood. Here, we explored the utility of landscape indicators for explaining water chemistry and bacterial concentrations in streams throughout the Greater Vancouver Regional District, British Columbia, Canada. First, we compared high and moderate spatial resolution imagery to evaluate their relative efficacy in characterizing impervious surfaces. Second, we linked a suite of landscape indicators to major chemical properties and pollutants (e.g. dissolved oxygen, nitrate, turbidity, fecal coliform, E. Coli.) using a series of comparative statistical models. Land cover at 30-m resolution often over-estimated the proportional area of impervious surface by 0.10–0.30, sometimes doubling the amount detected using finer resolution imagery. Finer 5- and 2-m resolution imagery demonstrated little difference in estimating impervious cover. Therefore, 5-m resolution imagery was adopted for spatial analysis in the study region. Watershed-level landscape indicators explained nearly 50% of the variability in wet season concentrations of dissolved oxygen and fecal coliform. When considering the spatial configuration of impervious areas, edge density within the riparian zone explained more than 30% of the variability in fecal coliform and E. Coli. Our approach is potentially transferable to many cities worldwide facing similar challenges in monitoring urban streams. [ABSTRACT FROM AUTHOR]

Wastewater treatment plant (WWTP) discharge is often considered a principal source of surface water contamination. In this study, a three-dimensional fully-integrated groundwater–surface water model was used to simulate the transport characteristics and cumulative loading of an artificial sweetener (acesulfame) and fecal indicator bacteria (Escherichia coli) from WWTPs within a 6800 km2 mixed-use, highly impacted watershed in Ontario, Canada. The model, which employed 3.5 × 106 computational nodes and 15 layers, facilitated a comprehensive assessment of groundwater–surface water interactions under high and low flow conditions; processes typically not accounted for in WWTP cumulative effects models. Simulations demonstrate that the model had significant capacity in reproducing the average and transient multi-year groundwater and surface water flow conditions in the watershed. As a proxy human-specific conservative tracer, acesulfame was useful for model validation and to help inform the representation of watershed-scale transport processes. Using a uniform WWTP acesulfame loading rate of 7.14 mg person−1 day−1, the general spatial trends and magnitudes of the acesulfame concentration profile along the main river reach within the watershed were reproduced; however, model performance was improved by tuning individual WWTP loading rates. Although instream dilution and groundwater–surface water interactions were strongly dependent on flow conditions, the main reach primarily consisted of groundwater discharge zones. For this reason, hydrodynamic dispersion in the hyporheic zone is shown as the predominant mechanism driving acesulfame into near-stream shallow groundwater, while under high flow conditions, the simulations demonstrate the potential for advective flushing of the shallow groundwater. Regarding the cumulative impact of the WWTPs on E. coli concentrations in the surface flow system, simulated transient E. coli levels downstream of WWTPs in the watershed were significantly lower than observed values, thus highlighting the potential importance of other sources of E. coli in the watershed. Image 100146 • Integrated hydrologic models are effective for characterizing point source pollution impacts. • Acesulfame is an effective chemical tracer for validating watershed-scale models. • Groundwater – surface water interactions impart a dynamic influence on water quality. • With only point source WWTP emitters considered, instream FIB levels were underestimated. [ABSTRACT FROM AUTHOR]

Residents in rural communities across Canada collect potable water from aquifers. Fecal contaminants from sewage and agricultural runoffs can penetrate aquifers, posing a public health risk. Standard methods for detecting fecal contamination test for fecal indicator bacteria (FIB), but the presence of these do not identify sources of contamination. In contrast, DNA-based diagnostic tools can achieve this important objective. We employed quantitative polymerase chain reaction (qPCR) and high-throughput DNA sequencing to trace fecal contamination sources in Wainfleet, a rural Ontario township that has been under the longest active boil water advisory in Canada due to FIB contamination in groundwater wells. Using traditional methods, we identified FIBs indicating persistent fecal pollution in well waters. We used 16S rRNA sequencing to profile groundwater microbial communities and identified Campylobacteraceae as a fecal contamination DNA marker in septic tank effluents (STEs). We also identified Turicibacter and Gallicola as a potential cow and chicken fecal contamination marker, respectively. Using human specific Bacteroidales markers, we identified leaking septic tanks as the likely primary fecal contamination source in some of Wainfleet's groundwater. Overall, the results support the use of sequencing-based methods to augment traditional water quality testing methods and help end-users assess fecal contamination levels and identify point and non-point pollution sources. [ABSTRACT FROM AUTHOR]

• Parametric models were developed to assess source water E. coli to protozoa ratios. • Ratios were 1.0 to 2.0-log lower in small rural rivers than in large urban rivers. • Low E. coli concentrations in small rivers during winter drove these differences. • There were no proportionalities between mean E. coli and mean protozoa concentrations. • An E. coli trigger level would have limited value for defining treatment requirements. Minimum treatment requirements are set in response to established or anticipated levels of enteric pathogens in the source water of drinking water treatment plants (DWTPs). For surface water, contamination can be determined directly by monitoring reference pathogens or indirectly by measuring fecal indicators such as Escherichia coli (E. coli). In the latter case, a quantitative interpretation of E. coli for estimating reference pathogen concentrations could be used to define treatment requirements. This study presents the statistical analysis of paired E. coli and reference protozoa (Cryptosporidium, Giardia) data collected monthly for two years in source water from 27 DWTPs supplied by rivers in Canada. E. coli / Cryptosporidium and E. coli / Giardia ratios in source water were modeled as the ratio of two correlated lognormal variables. To evaluate the potential of E. coli for defining protozoa treatment requirements, risk-based critical mean protozoa concentrations in source water were determined with a reverse quantitative microbial risk assessment (QMRA) model. Model assumptions were selected to be consistent with the World Health Organization (WHO) Guidelines for drinking-water quality. The sensitivity of mean E. coli concentration trigger levels to identify these critical concentrations in source water was then evaluated. Results showed no proportionalities between the log of mean E. coli concentrations and the log of mean protozoa concentrations. E. coli /protozoa ratios at DWTPs supplied by small rivers in agricultural and forested areas were typically 1.0 to 2.0-log lower than at DWTPs supplied by large rivers in urban areas. The seasonal variations analysis revealed that these differences were related to low mean E. coli concentrations during winter in small rivers. To achieve the WHO target of 10−6 disability-adjusted life year (DALY) per person per year, a minimum reduction of 4.0-log of Cryptosporidium would be required for 20 DWTPs, and a minimum reduction of 4.0-log of Giardia would be needed for all DWTPs. A mean E. coli trigger level of 50 CFU 100 mL−1 would be a sensitive threshold to identify critical mean concentrations for Cryptosporidium but not for Giardia. Treatment requirements higher than 3.0-log would be needed at DWTPs with mean E. coli concentrations as low as 30 CFU 100 mL−1 for Cryptosporidium and 3 CFU 100 mL−1 for Giardia. Therefore, an E. coli trigger level would have limited value for defining health-based treatment requirements for protozoa at DWTPs supplied by small rivers in rural areas. [Display omitted] [ABSTRACT FROM AUTHOR]