Role of poison control centers in a public water contamination warning and response system

Background: In 2007, the Cincinnati Drug and Poison Information Center (DPIC) was invited to participate in the public health component of the Environmental Protection Agency's Water Security Initiative. One component of this partnership involved methodology for real time surveillance of poison center (PC) calls to identify possible water contamination (WC) events.

Method: We sought to evaluate surveillance of PC calls for WC by incorporating both machine analysis and 'astute clinician' models for anomaly detection. Three primary alerting mechanisms specific to the geographical boundaries of the water utility were developed, 1. National Poison Data System (NPDS) human exposure and clinical effect count definitions are used to identify unusual deviations from expected baseline case counts, 2. Single cases involving environmental or malicious intent and substances of interest trigger NPDS case-based alerts, and 3. PC specialists are trained to use clinical judgment to identify cases possibly related to a WC threat.

Results: Our design is associated with an average of 1.4 notifications per 100 human exposure cases (range 0.5-2.5). Although no confirmed WC events have been reported during the study period (June 2007-present), 32 cases of interest have been identified. The only event associated with a trigger from all three alerting mechanisms involved a gastrointestinal syndrome impacting numerous students sharing a single drinking fountain. Ongoing analysis indicates that PCs are more sensitive to detecting acute chemical threats than biological threats.

Conclusions: Poison centers play an important role in the early detection of potential public drinking water contamination events.