Using multi-criteria decision analysis to assess the vulnerability of drinking water utilities.

Outbreaks of microbiological waterborne disease have increased governmental concern regarding the importance of drinking water safety. Considering the multi-barrier approach to safe drinking water may improve management decisions to reduce contamination risks. However, the application of this approach must consider numerous and diverse kinds of information simultaneously. This makes it difficult for authorities to apply the approach to decision making. For this reason, multi-criteria decision analysis can be helpful in applying the multi-barrier approach to vulnerability assessment. The goal of this study is to propose an approach based on a multi-criteria analysis method in order to rank drinking water systems (DWUs) based on their vulnerability to microbiological contamination. This approach is illustrated with an application carried out on 28 DWUs supplied by groundwater in the Province of Québec, Canada. The multi-criteria analysis method chosen is measuring attractiveness by a categorical based evaluation technique methodology allowing the assessment of a microbiological vulnerability indicator (MVI) for each DWU. Results are presented on a scale ranking DWUs from less vulnerable to most vulnerable to contamination. MVI results are tested using a sensitivity analysis on barrier weights and they are also compared with historical data on contamination at the utilities. The investigation demonstrates that MVI provides a good representation of the vulnerability of DWUs to microbiological contamination.

Risk of diarrhea with adult residents of municipalities with significant livestock production activities.

BACKGROUND: The intensification of livestock production has led to situations where the amount of manure that is produced exceeds the amounts needed in some areas. The objective of this study was to evaluate the relationship between the intensity of livestock activities and manure products, particularly in swine farms, and the prevalence of diarrhea in adults. METHODS: A survey was carried out on 8702 adults living in 161 municipalities in Quebec areas with intensive farming activities. Data were collected by a telephonic interview on diarrheal symptoms that occurred during the previous week of the interview, on water consumption and on selected risk factors. Statistical analysis was performed using a 'generalized estimating equations' model. RESULTS: Prevalence of diarrhea was found to be highest in adults aged between 25 and 34 years. No association was found between swine density or liquid manure application and diarrheal prevalence. There was also no association between cattle or total animal density and diarrheal prevalence. In the areas studied, there was no increase in risk associated with the consumption of tap water with suboptimal treatment and susceptible to microbiologic contamination. CONCLUSION: Significant livestock production and excess of manure were not associated with the risk of diarrhea in adults.