Wastewater Risk Assessment

Risk assessment takes place in three broad and overlapping steps: hazard identification, risk estimation, and social evaluation. Human pathogens are of primary concern in wastewater although focus has recently shifted to chemical hazards. The relation of dose-response between hazardous substances and exposed populations can be coupled with predictions of likely dosages resulting from human exposure to polluted water to give estimates of maximal risk. This methodology was used to show that less than 0.1 cases of hepatitis A per 100,000 persons per year can reasonably be attributed to drinking treated surface water or to swimming downstream from an unchlorinated sewage treatment plant discharge.