National Chemical and Radiological Surveillance Program
The primary objective of this program is to provide CDC with a national surveillance capability to better detect and respond to chemical, environmental, drug, foodborne, biological and radiological exposures and illnesses of potential public health significance. On average, every 24 minutes, 57 regional PCs upload data collected from calls made to their organizations to the national poison center reporting database known as the National Poison Data System or NPDS. The National Poison Data System is owned and operated by the American Association of Poison Control Centers (AAPCC). Since 2001, CDC and AAPCC have developed methods to use NPDS data for near, real-time surveillance of exposures to hazardous substances of potential public health significance. CDC uses NPDS to:
- improve national surveillance for chemical, environmental, drug, foodborne, biological and radiological exposures and illness of potential public health significance
- identify early markers of chemical, environmental, drug, foodborne, biological and radiological events in order to provide an effective and rapid public heath response
- to identify and track exposures and cases of illness during an emerging or known public health threat
How information is collected using NPDS
Operational since 1985, NPDS is the only national human poisoning database in the United States. The database currently logs approximately 2.5 million calls about potential exposures (exposure calls) annually. NPDS receives approximately 1.5 million calls requesting information (information calls) on a particular substance annually. The cumulative NPDS database contains information about more than 36.2 million potential poison exposures in humans.
The data fields for NPDS include case information (center, date), call information (exposure site, reason for exposure), caller information (location by zip code, county, state), patient information (age, sex, pregnancy), exposure information (acuity, duration, number of substances, route of exposure, substance, and amount), and information about case management (management site, therapy, treatment), medical outcomes, and clinical effects (e.g., signs, symptoms, laboratory abnormalities).
How NPDS is used to detect outbreaks
Three approaches are currently used by the NCRS Team to detect exposures and illnesses of potential public health significance. These approaches use automated algorithms to detect anomalies in call volume patterns and clinical effect volume patterns to PCs. Finally, the system allows us to prospectively and retrospectively identify calls containing pre-established criteria of interest, referred to as case-based surveillance.
Call volume surveillance
This approach uses automated algorithms to monitor, analyze and compare the hourly volume of exposure calls at each PC to historical baseline information for each PC. When the call frequency for a given hour at a given PC exceeds a pre-established threshold, developed from PC-specific historical data, an anomaly is identified and an automated email is generated alerting a team of CDC and AAPCC toxicologists and epidemiologists.
Clinical effect surveillance
This approach uses automated algorithms to monitor, analyze and compare the national, daily cumulative total for each individual clinical effect contained in NPDS (the system contains 131 clinical effects which consist of specific signs, symptoms, and laboratory abnormalities) to historical, cumulative national, baseline data for each clinical effect. When the national, daily cumulative total number of any of the 131 clinical effects exceeds that pre-established threshold, an anomaly is identified and an automated email is generated alerting a team of CDC and AAPCC toxicologists and epidemiologists.
Case-based definition surveillance
This approach allows the user to create a specific case-based definition to identify calls that have certain attributes such as a specific collection of clinical effects in males under the age of 5 years exposed to substance X. Different attributes can be used (as long as they are already contained in NPDS as pre-existing choices) to create various case-based definitions depending on the exposure of interest. In a situation where identification of calls related to a specific substance or a particular event (e.g., the 2010 Deepwater Horizon incident) is desired but a pre-existing code for this is not available, a temporary NPDS event or substance-specific code can be created by AAPCC. AAPCC can then rapidly communicate with all member regional PCs to inform them of the need to label any relevant calls with this temporary code. Historical uses of case-based definitions for surveillance include the following:
Identification of calls regarding suspected exposures or illnesses caused by specific toxins or toxicants (e.g., cyanide, arsenic, pufferfish poisoning) of potential public health significance. These definitions include a specific product code for the substance of interest
Identification of calls regarding suspected exposures or illnesses that had a particular constellation of clinical effects or other attributes (specific sex, age group, etc..) coded which are suspicious for a disease of potential public health significance (e.g., botulism)
Identification of calls regarding suspected exposures or illnesses that were associated with a particular event. For instance, CDC tracked all exposure calls made to PCs associated with the 2011 Japan nuclear incident.
How the NCRS Program is used to determine whether a public health investigation is warranted.
AAPCC and CDC clinical toxicologists and epidemiologists analyze surveillance data daily to determine if further follow up activity is needed or if the call is of potential public health significance. Some of the criteria used in this process, in combination with clinical judgment, includes determining if:
- An exposure call or cluster of exposure calls is/are associated with a reportable exposure, illness or disease of obvious interest to the appropriate state or national public health entity
- An exposure call or cluster of exposure calls is/are related to an outbreak of illness of unusual severity or magnitude or involve persons from more than 1 household in which the exposure site was outside the home and clinical effects reported
- An exposure call or cluster of exposure calls is/are associated with an exposure or illness that may be involved or associated with a suspected terrorism event
- An exposure call or cluster of exposure calls regarding an exposure or illness related to a product or an event that is part of a state or national public health investigation
- A call or cluster of calls regarding an exposure is associated with a pattern of illness not normally attributable to the implicated exposure
- An obvious geographic or spatial pattern of similar anomalies exists
- A high index of suspicion, credible threat, or other rationale exists in the judgment of the NPDS Surveillance Team member
- A case-based surveillance anomaly represents a true potential exposure to the substance of interest AND meets at least one of the other criteria
After reviewing the data, AAPCC and CDC scientists determine whether the appropriate PC should be contacted to request additional information on the call(s) of interest.
If available information suggests that an event warrants further investigation, the reporting PC and/or CDC may notify the local and/or state health department as well as other appropriate federal agencies.
How a national surveillance program for chemical, environmental, drug, foodborne, biological and radiological exposures and illness will assist in preventing unintentional poisonings
Using NPDS as part of a national surveillance program will improve the ability of PCs to respond to public health emergencies related to a wide variety of agents in the environment. National surveillance information collected about contaminated or tampered water, food, medication, or other products can provide a basis for establishing historical definitions for specific events with similar patterns. The following are examples of how national surveillance has been used to assess potential threats and prevent further contamination.
First utilization of NPDS-based national surveillance for exposures and illness due to a radiological and an international event (2011): CDC tracked all calls related to the 2011 Japan nuclear incident. Between March 11 and April 18, NPDS tracked 340 information requests and 64 calls regarding potential radiation, potassium iodide and iodide product exposures to US PCs for a total of 404 calls related to the Japan incident. Call details were analyzed daily and reported to CDC leadership for situational awareness and to inform public health response efforts. In past incidents where surveillance was initiated in response to a potential public health threat, actual call volumes regarding potential exposures were reported but exposures were not confirmed. During this event, CDC and AAPCC staff performed detailed follow up and data review to confirm exposure status. Information was sent daily to CDC leadership to determine the impact of the nuclear incident on the general population in the US. Surveillance for calls related to potassium iodide (a preventive treatment for radiological-associated thyroid disease when radioactive iodine is released) exposures documented very few adverse outcomes in persons taking this product in response to a perceived risk from this event. This work reassured CDC leadership that potassium iodide abuse in response to this incident was not a substantial public health concern.
Utilization of NPDS-based surveillance for potential oil exposures and associated illness in response to the Deepwater Horizon Incident (2010): CDC tracked all calls related to the oil spill received by the 57 contributing PCs in the US. As of September 11, 2010, there had been 1838 calls related to this incident. Of these, 1160 were self-reported exposures and symptoms, which included cough, nausea, headache, ocular irritation, throat irritation, chest pain, dizziness, difficulty breathing, and rash. The data was used daily to identify trends and monitor severity of health effects due to exposure to the gulf coast oil spill. This information aided CDC leadership to determine the impact of the oil spill on health effects of the general population and was an integral part of the Gulf Coast Oil Spill Response Surveillance Activities. Information was also sent to each affected state to utilize in their surveillance activities and public health response efforts.
Utilization of NPDS-based surveillance for illness due to an infectious agent (2009): Peanut butter and peanut butter containing products were confirmed to be the source of a Salmonella outbreak in January of 2009. In response, AAPCC and CDC began monitoring calls to NPDS using daily reports of calls about peanuts/peanut products. Through NPDS-based surveillance, we identified five states reporting exposure calls that had not been previously identified by CDC. Aggregate data from NPDS were reported daily to the Division of Foodborne and Mycotic Diseases at CDC to enhance their situational awareness.
Utilization of NPDS-based surveillance for a commercial product (2008): NPDS-based surveillance was used to identify potential cases of selenium-associated illness associated with an improperly formulated health product and track the geographic extent of the outbreak. The distributor of the products reported shipping to 16 states. During case management, PC staff identified the related calls as having exposures to the particular dietary supplement, thus allowing CDC and AAPCC to track all calls related to this outbreak. As of June 4, 2008, 170 exposure calls related to this outbreak were reported in eight states. Use of NPDS enhanced situational awareness for individual PCs and state health departments, provided rapid identification of calls from newly affected states, and enabled public health officials to conduct detailed follow-up with individuals reporting exposures to these products.
Callers can contact the Poison Control Center in their area by calling 1-800-222-1222. Individual callers will automatically be connected to the center covering their calling area.