Nitrate-Risk Assessment Using Fuzzy-Set Approach

A methodology is developed to estimate the human-health risk from ground-water contamination and evaluate possible regulatory actions. The methodology is illustrated considering the case of health risk from ground-water nitrate contamination. Generally, assessment of health risk from water contamination contains several elements of uncertainty due to a lack of available information, including that related to interspecies extrapolation, dose-response modeling, and the inherent inaccuracy of data used. In the present paper, the uncertainty associated with these elements and its impact on results are represented by using a fuzzy-set approach and incorporated into the health-risk-assessment process; therefore, a health-risk assessment and management strategy can be made that is more realistic and appropriate than the one made without taking uncertainty into account. The guidelines on risk regulation presented allow decision makers to determine, under uncertainty, whether regulatory action must be taken to reduce human-health risk from nitrate in ground-water supplies. Three factors, the level of health risk related to uncertainty, the population size exposed, and the cost required for risk reduction, are then considered in deciding whether to regulate or not.