Rory Coffey

Microbial Exposure Assessment of Waterborne Pathogens

ABSTRACT The large number of waterborne illnesses in Ireland and worldwide has highlighted the need to enhance strategies that minimize human exposure to pathogens in drinking water supplies. Waterborne pathogens of public concern together with relevant national and international legislation are reviewed in this study. Cryptosporidium species and pathogenic Escherichia coli are among pathogens of primary concern. The organisms originate from the gastrointestinal tract of animals and humans. They may be associated with persistent contamination of water sources, survive for long periods in the environment, and, in particular in the case of Cryptosporidium species, may survive in chlorinated water supplies. Prevention of waterborne infection should emphasize source protection in addition to water treatment. Risk assessment models can play an important role in protecting natural water systems from contamination with these pathogens. Qualitative approaches can provide an effective means of assessing risks with minimum resources and limited data; however, they lack the precision and predictive ability of fully quantitative approaches. Thirteen quantitative simulation models that could potentially be used for modeling bacterial pollutants in agricultural watersheds have been assessed in this study. No one model suits all modeling criteria. Pathogen predictions have proved variable and no model was capable of accounting for all geological and hydrological factors in addition to modeling the physical transport of bacteria in surface runoff. This assessment summarizes commonly used models and their capacity to model water pollution while also providing a good reference point for the microbial risk assessment of waterborne pathogens.

Modeling of Pathogen Indicator Organisms in a Small-Scale Agricultural Catchment Using SWAT

ABSTRACT Degradation of water quality from microbial contaminants associated with agricultural activities has significant implications for source protection of potable water. Novel environmental approaches must be adopted to assess risks from waterborne pathogenic microbes. The objective of this study was to evaluate applicability of the Soil and Water Assessment Tool (SWAT) to predict daily concentrations of E. coli in a small-scale agricultural catchment in Ireland. The study area is based on the Kilshanvey catchment located in the west of Ireland. E. coli data (n = 25) from June 2006 to June 2007 were utilized for comparison with the models predictions. Statistical analysis indicates an unsatisfactory to fair level of correlation for the models predictions (R2 = 0.03–0.35, NSE = –0.42–0.29). A sensitivity analysis identified direct stream deposition and die-off rates for E. coli as having a significant impact on the models predictions. Our results suggest that the model is adequate to assess the magnitude of various microbial sources within catchments but capability to replicate daily observations is uncertain. However, model outputs could provide adequate data to develop a human exposure assessment to pathogen indicator organisms in surface water and assist policy-makers in developing appropriate risk management strategies.

Predicting microbial water quality with models : over-arching questions for managing risk in agricultural catchments.

The application of models to predict concentrations of faecal indicator organisms (FIOs) in environmental systems plays an important role for guiding decision-making associated with the management of microbial water quality. In recent years there has been an increasing demand by policy-makers for models to help inform FIO dynamics in order to prioritise efforts for environmental and human-health protection. However, given the limited evidence-base on which FIO models are built relative to other agricultural pollutants (e.g. nutrients) it is imperative that the end-user expectations of FIO models are appropriately managed. In response, this commentary highlights four over-arching questions associated with: (i) model purpose; (ii) modelling approach; (iii) data availability; and (iv) model application, that must be considered as part of good practice prior to the deployment of any modelling approach to predict FIO behaviour in catchment systems. A series of short and longer-term research priorities are proposed in response to these questions in order to promote better model deployment in the field of catchment microbial dynamics.

Pathogen Sources Estimation and Scenario Analysis Using the Soil and Water Assessment Tool (SWAT)

ABSTRACT Concerns over water quality in Ireland have increased in recent years, in part due to the more frequent contamination of drinking water by pathogens such as Escherichia coli and Cryptosporidium. The objective of this study was to assess the use of SWAT for pathogen source estimation and to analyze the effects of various source scenarios on pathogen outputs in Irish catchments. Two agricultural catchments in Ireland susceptible to pathogen contamination of source water were the center of the SWAT model development with the primary focus on levels of E. coli in surface water. Model simulations used site and source specific information which was analyzed considering the total E. coli count for the simulation period (Fergus: January 2005–October 2006; Kilshanvey: January 2006–July 2007). Pathogen source estimation identified point sources as the most significant contributors to E. coli output with direct deposition the primary contributor (95%) in Kilshanvey and wastewater treatment plant outflow (89%) the main contributor in the Fergus catchment. A scenario analysis evaluated possible situations that may occur in study locations. The analysis indicated that restriction of livestock access to water sources and improved wastewater treatment would represent effective methods of improving water quality in both catchments.

Assessing the Effects of Climate Change on Waterborne Microorganisms: Implications for EU and U.S. Water Policy

ABSTRACT Despite advances in water treatment, outbreaks of waterborne diseases still occur in developed regions including the United States and Europe Union (EU). Water quality impairments attributable to elevated concentrations of fecal indicator bacteria, and associated with health risk, are also very common. Research suggests that the impact of such microorganisms on public health may be intensified by the effects of climate change. At present, the major regulatory frameworks in these regions (i.e., the US Clean Water Act [CWA] and the EU Water Framework Directive [WFD]), do not explicitly address risks posed by climate change. This article reviews existing U.S. and EU water quality regulatory legislation for robustness to climate change and suggests watershed modeling approaches to inform additional pollution control measures given the likely impacts on microbial fate and transport. Comprehensive analysis of future climate and water quality scenarios may only be achievable through the use of watershed-scale models. Unless adaptation measures are generated and incorporated into water policy, the potential threat posed to humans from exposure to waterborne pathogens may be amplified. Such adaptation measures will assist in achieving the aims of the EU WFD and US CWA and minimize impacts of climate change on microbial water quality.

Sensitivity of streamflow and microbial water quality to future climate and land use change in the West of Ireland

This study applied catchment modeling to examine the potential effects of climate change and future land management variations on streamflow and microbial transport sensitivities for two locations in the west of Ireland (Black River and Fergus River). Simulations focused on plausible combined scenarios of climate, population and agricultural production variations for the 2041–2060 period and compares resultant impacts to a baseline existing period (1994–2007). The variations in monthly, seasonal and annual streamflow, and the daily microbial load (for E. coli) were used to assess sensitivities. Results indicate that possible future changes in microbial load for both the Fergus and Black catchments typically follow projected seasonal fluctuations in precipitation and streamflow. Increased winter rainfall (intensity and frequency) will cause significant impacts on microbial transport, representing a period of increased risk. An increase in microbial source loads to land, concomitantly with projected changes in climate is likely to exert greater microbial pollutant pressures on surface waters. The simulated scenarios, and resultant microbial load changes, suggest that future variations in land use/management may be as important as the effects of climate change on in-stream microbial pollutant loads. Outcomes from this study can prove useful for informing water resource managers and other decision makers about potential impacts. This information can instigate the development of adaptation measures needed to alleviate increased catchment pollution from microbial contaminants (and other pollutants) in future years.

Feed to food risk assessment, with particular reference to mycotoxins in bovine feed

Recent food safety scares, in particular those relating to bovine spongiform encephalopathy and Escherichia coli, have highlighted the need to assure consumers of the quality of the food they eat. It is necessary to highlight the procedures in place for minimising potential risks to animals and subsequent risks to consumers from animal derived food products. The potential dangers of mycotoxins in bovine feed and subsequent transfer to food for human consumption have become a food safety issue. Mycotoxins are secondary metabolites produced by fungi when cereals or animal feed are colonised by moulds and can cause severe immune deficiency, kidney and liver damage, while some mycotoxins (such as aflatoxins) are also known carcinogens. This paper reviews existing scientific studies and highlights those mycotoxins likely to occur in cereals, animal feed and food products of animal origin. The effects on human and animal health and key parameters in the formation of a Feed Chain Risk Assessment are also reviewed.

Evaluation of near-infrared chemical imaging for the prediction of surface water quality parameters

Near-infrared (NIR) chemical imaging is an emerging technique with the potential for the detection of contaminants in the environmental field. In this study the potential of NIR chemical imaging (NIR-CI) to predict concentrations of nutrients (total nitrogen, total phosphorus) and indicator microorganisms (Escherichia coli) in surface water was investigated. Chemical images of multiple samples were obtained simultaneously using a pushbroom imaging system operating in the 950–1650 nm wavelength range with spectral resolution of 7 nm. Using partial least squares regression models, the relationship between these pollutants and NIR spectral data extracted from the chemical images in samples of aqueous surface water and filtered residue from surface water was assessed. When calibration models were tested on an independent data set, it was found that models developed on filtered residue spectra outperformed those developed on aqueous samples. For samples of filtered residue, the performance of the calibrations achieved for total nitrogen was reasonable (R2 > 0.75); however, performance for total phosphorus and E. coli was poor (R2 < 0.5). Lower concentrations of these parameters were detected in the surface water samples included in the study (<1 mg L−1 and <20 colony-forming units per 100 mL, respectively), a likely reason for the poor performance. The results indicate that NIR-CI has the potential for screening samples in which the contaminant concentration exceeds 1 mg L−1.

Use of Meta-Analysis to Assess the Effect of Conventional Water Treatment Methods on the Prevalence of Cryptosporidium Spp. in Drinking Water

ABSTRACT Meta-analysis is defined as the statistical analysis of a collection of analytic results for the purpose of integrating the findings. However, its use in environmental and agricultural health protection has been minor in research to date. Few meta-analysis studies have been applied to assess factors relating to Cryptosporidium but none have examined the effect of conventional water treatment on oocyst prevalence. The objective of this study was to synthesize past scientific research and analyze the effects of conventional water treatment methods on the prevalence of Cryptosporidium in drinking water using a traditional parametric approach of meta-analysis. Twenty-three different published studies featuring 27 separate water treatment surveys were identified for inclusion in the meta-analysis. The meta-analysis indicated that general conventional water treatment methods reduced Cryptosporidium occurrence in drinking water by an average factor of ∼11.82 (95% CI = 2.7–52.5). Results highlight the resistance of the pathogen to such treatment methods and emphasize the parasites standing as a waterborne pathogen of primary concern given the possibility of viable oocyst occurrence in water, post treatment. Consequently, findings accentuate the need for new approaches to the control of Cryptosporidium aimed at integrated catchment management, source protection, and also including new treatment technologies. Until such approaches are actively adopted the potential risk posed to consumers by pathogens in potable water will remain active.

Assessing the impacts of climate change on waterborne microorganisms

Scientific research suggests that the impact of pathogens, such as verotoxigenic (VTEC) Escherichia coli and Cryptosporidium, may be intensified by the potential effects of climate change. It is predicted that extremes of the hydrological cycle will accompany global warming and both are likely to affect the nature of pathogens in the environment and their fate and transport. Regulations, such as the EU Water Framework Directive and the US Clean Water Act, highlight the need for models capable of predicting fecal pathogen fluctuations from watersheds with varying land uses. Previous research work on the applicability of watershed models to simulate daily pathogen concentrations has indicated that sufficient capabilities exist to model pathogen transport; however, additional research is required to account for future climate variability and identify risk scenarios. Integration of watershed-pathogen modeling capabilities with climate change predictions can enable investigation into the potential impacts on pathogenic organisms. To date legislations, such as the Clean Water Act in the USA and the Water Framework Directive in Europe, have failed to take direct account of the risks posed by climate change. The objective of this study is to examine potential climate change impacts on pathogens and assess the use of watershed-pathogen modeling applications to prepare for future scenarios. Deriving relevant scenarios and simulation of these through watershed modeling applications can provide the basis to develop appropriate remediation measures in preparation for climate impacts on waterborne microorganisms.