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© 2007 American Public Health Association
DOI: 10.2105/AJPH.2006.099903
RESEARCH AND PRACTICE |
At the time of the study Joshua G. Schier, Manish M. Patel, Martin G. Belson, and Carol H. Rubin were with the Division of Environmental Hazards and Health Effects, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, Ga. Dan Drociuk and Nicole Fitzpatrick were with the South Carolina Department of Health and Environmental Control, Columbia. Richard Meyer was with the Bioterrorism Rapid Response and Advanced Technology Laboratory, National Center for Infectious Diseases, Centers for Disease Control and Prevention, Atlanta. Michael Schwartz was with the Office of the Director, Agency for Toxic Substances and Disease Registry, Atlanta. Toby Litovitz and William A. Watson were with the American Association of Poison Control Centers, Washington, DC. Max Kiefer, Scott Deitchman, and Amee Patel were with the National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Atlanta.
Correspondence: Requests for reprints should be sent to Joshua G. Schier, CDC/NCEH/EHHE/HSB Mail Stop F46, 4770 Buford Highway, NE, Chamblee, GA 30341 (e-mail: jschier{at}cdc.gov).
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ABSTRACT |
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 TOP ABSTRACT INTRODUCTIONMETHODSRESULTSDISCUSSIONReferences |
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Objectives. In October 2003, a package containing ricin and a note threatening to poison water supplies was discovered in a South Carolina postal facility, becoming the first potential chemical terrorism event involving ricin in the United States. We examined the comprehensive public health investigation that followed and discuss the lessons learned from it.
Methods. An investigation consisting primarily of environmental sampling for ricin contamination, performance of health assessments on affected personnel, and local, regional, and national surveillance for ricin-associated illness.
Results. Laboratory analysis of 75 environmental sampling specimens revealed no ricin contamination. Health assessments of 36 affected employees were completed. Local surveillance initially identified 3 suspected cases, and national surveillance identified 399 outliers during the 2-week period after the incident. No confirmed cases of ricin-associated illness were identified.
Conclusions. A multifaceted and multidisciplinary approach is required for an effective public health response to a chemical threat such as ricin. The results of all of the described activities were used to determine that the facility was safe to reopen and that no public health threat existed.
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INTRODUCTION |
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TOPABSTRACTINTRODUCTIONMETHODSRESULTSDISCUSSIONReferences |
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On October 15, 2003, a small, closed, metal canister within a package was found in a postal processing facility in Greenville, SC, with a note threatening to poison water supplies if certain demands were not met.1 That same day, the facility manager made a call to the Inspection Service Office in Greenville, which advised him to call emergency responders. Approximately 1 hour later, emergency responders, members of local law enforcement and the local fire department’s hazardous materials unit, arrived at the facility, and the building was evacuated. The package was isolated from postal workers and Federal Bureau of Investigation Joint Terrorism Task Force representatives coordinated transport of the package.
The South Carolina Department of Health and Environmental Control (SC DHEC) received the package at approximately 10:00 AM on October 16, 2003. Using a standard "all agents" testing approach, the South Carolina Bureau of Laboratories tested for several agents, including anthrax, but did not have the capability at that time to test for ricin. The Centers for Disease Control and Prevention (CDC) was contacted, and handling and testing of suspicious substances was discussed. Because the substance was in a well-sealed metal container, the South Carolina Bureau of Laboratories and CDC decided that the risk of exposure was low.
The CDC requested that South Carolina Bureau of Laboratories officials send the specimen via an overnight express courier on October 20, 2003, for analysis. Samples were shipped to the CDC and were confirmed to be ricin on October 21, 2003.1 A team of professionals with expertise in medical toxicology, industrial hygiene, and epidemiology traveled to the site from the CDC that same day, and the facility was closed for a detailed epidemiological and environmental sampling investigation.1 The CDC and SC DHEC conducted a case finding for potential ricin-associated illness among postal workers at the facility where the ricin was discovered and initiated state, regional, and national surveillance for potential ricin-associated illness.1
Ricin is a deadly protein toxin, or toxalbumin, derived from the castor bean plant, Ricinus communis.1–3 The clinical effects that may result from ricin exposures are primarily because of nonspecific inhibition of protein synthesis resulting in nonspecific cellular dysfunction and death.1–3 Ricin has been used as a poison in both criminal and terrorist events.4–7 A substantial lack of knowledge exists in established procedures for responding to potential environmental contamination of many poisons, including ricin. Health assessments of affected individuals and surveillance activities are also needed to assist in the evaluation of a public health threat.
The anthrax exposure events of 2001 revealed a fundamental lack of knowledge in the medical and public health communities regarding the relationships among contamination, human exposure, and disease.8 Environmental sampling is critical to identify and characterize the extent of contamination.8,9 Qualitative and quantitative assessment of the extent of contamination is necessary to control the hazard, determine human exposure, and implement appropriate interventions to avoid adverse health effects.8,9 However, the relationship between environmental contamination of ricin and subsequent health risk from exposure is unclear. Thresholds have not been established for many agents, including ricin, and often no guidelines exist for result interpretation.
To our knowledge, this study is the first explicitly detailed description of a public health and environmental sampling investigation for a possible chemical terrorism event involving ricin. Our primary objective was to describe in detail the various components of the public health investigation to assist in future responses to ricin-associated public health threats. Our secondary objective was to describe the public health consequences resulting from the lessons learned in this incident.
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METHODS |
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TOPABSTRACTINTRODUCTIONMETHODSRESULTSDISCUSSIONReferences |
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Environmental Sampling
CDC investigators conducted a detailed walk-through of the facility with postal personnel on the evening of October 21, 2003, and into the morning of October 22, 2003, noting all points that the package contacted as it was moved through the facility. Using existing floor plans, a targeted sampling plan was developed, beginning with the location of package entry and following along the anticipated path of contamination to the point of discovery. The primary objective of this approach was to maximize the possibility of finding contamination.10,11
Environmental samples were obtained at every point of contact of the package as it moved through the facility, including conveyers, loaders, material holders, and mail sorters. Multiple samples were obtained from locations where contact was uncertain. Objects where human contact with the package occurred (e.g., controls and levers) and areas such as holding rooms (after package discovery) were sampled.
Sampling Technique
Professional industrial hygienists led the environmental sampling mission. A single individual was designated as the "sampler" or as the "clean" team member: only 1 individual handled the samples or blanks (control or empty specimens) to maintain result integrity. This member changed gloves between each sampling to avoid cross-contamination. Two additional people were designated as handlers and provided swabs to the sampler and sealed the plastic bag containing the swab sample when the swab was returned. A fourth individual measured the dimensions of the sampling area, took photographs, and noted the location of the sample and sample number. The team took a total of 75 surface samples: 70 surface swabs and 5 vacuum samples. This number was determined to be sufficient based on the professional judgment of the team, size of the potentially affected area, the fact that the ricin was contained in an unopened vial, an absence of ricin-associated illness, and the overall crudeness of the preparation.
Premoistened, individually packaged Dacron (ASD Biosystems, Danville, Va) swabs were used for surface sampling. A designated sampler removed the sterile, noncotton swab from the sampling kit and wiped the sample surface (100 cm2) using S-shaped strokes horizontally and then vertically. The swab was then placed in a plastic bag, sealed, and labeled with a unique identifier. Vacuum samples were taken by pulling air through a 37-mm mixed cellulose ester, 0.8-µm pore size filter in microcassettes using a portable personal air sampling pump set at 2.5 L/min. The cassette was fitted with a nozzle and connected to the pump with Tygon tubing (Saint-Gobain Performance Plastics, Akron, Ohio). The samples were collected using the American Society for Testing and Materials microvacuuming method D 5755–95 with several modifications.12 Chain-of-custody protocols were followed for all of the samples. Samples were flown to the Bioterrorism Rapid Response and Advanced Technology Laboratory at the CDC for analysis by time-resolved fluorescence immunoassay on October 22, 2003.
During actual sampling, investigators wore N–95 filtering facepiece respirators in case sampling procedures mobilized ricin particles that, if present, possibly had settled on surfaces. They also wore nitrile gloves to prevent cross-contamination of the surface samples.
Health Assessment of Affected Personnel
CDC and SC DHEC personnel used a health assessment questionnaire to interview and examine all 36 employees working in the receiving and sorting area of the Greenville Postal Facility for signs and symptoms of possible ricin-associated illness. Information regarding demographics, specific job at the facility, exposure history, medical history, and clinical signs and symptoms was collected. Risk communication regarding ricin was provided at the time of screening. Team members provided information regarding ricin and symptoms associated with exposure. Information regarding the ongoing legal investigation was provided by the on-site Federal Bureau of Investigation agent during the interviews. The United States Postal Service (USPS) provided additional mental health and social assistance to employees who requested it.
Surveillance for Ricin-Associated Illness
The CDC and SC DHEC conducted surveillance for potential cases of ricin-associated illness at the local, regional, and national level. The CDC developed a case definition for ricin poisoning (Table 1
) and a toxic syndrome description. These were disseminated to SC DHEC, which distributed them to South Carolina’s Palmetto Poison Center, local hospitals, and health departments via the South Carolina Health Alert Network. Health care workers were requested to report all illnesses suggestive of ricin poisoning to their local public health department.
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Local and State Surveillance of Hospitals and Health Care Facilities. Enhanced surveillance at local hospitals centered on identifying patients with recent unexplained pulmonary edema, respiratory failure, or multisystem organ failure. This surveillance was designed to detect potential cases of ricin-associated illness that may have occurred in the region via other possible, but unidentified, routes of exposure.
Local public health epidemiological response staff requested infection control practitioners from 9 local hospitals in the 4 involved counties (Greenville, Pickens, Spartanburg, and Anderson) to conduct active surveillance within each of those hospital’s intensive care units using the ricin case definition. They reviewed all of the patient records daily from October 15, 2003, to October 29, 2003, in each of the intensive care units for cases of suspected ricin-associated illness. Infection-control practitioners were instructed to notify their local public health representatives for suspected or confirmed cases of ricin-associated illness. South Carolina Health Alert Network health advisories enhanced statewide surveillance in all of the participating health care facilities within South Carolina. These contained case classification criteria, clinical description, laboratory criteria for diagnosis, signs and symptoms of ricin-associated illness, and reporting requirements (Table 1
). Scientists and professional communications staff facilitated the development and distribution of informational materials on ricin made available to the public on the CDC Web site. Within 2 months of this event, an educational Webcast on ricin-associated illness was developed and accessible from the CDC Web site.
Regional and National Poison Center Surveillance. South Carolina’s Palmetto Poison Center was on heightened alert for cases suggestive of ricin-associated illness during this period. During the evening of October 21, 2003, the CDC requested that the American Association of Poison Control Centers (AAPCC) increase its routine surveillance of the Toxic Exposure Surveillance System (TESS), a database that receives poisoning data from 61 of 62 US poison centers in "real time."13 AAPCC rapidly implemented the following modifications of TESS surveillance.13,14
Human poison exposure call volume (excluding information calls) and total call volume (including information calls) from each of the reporting poison centers were compared hourly with the center’s historical baseline to identify outliers and cases suggestive hourly human exposure or total call volume exceeded the respective historical threshold, a toxicologist reviewed the case. AAPCC also modified its typical review process, implementing specific searching for cases suggestive of ricin exposure because of an "unknown substance" coding or an unexplained serious outcome.
The frequency of reporting of 131 clinical effects included in the TESS database was monitored for increased rates of individual or groups of effects suggestive of ricin exposure, using methodology described previously.14 AAPCC increased the frequency of this monitoring from once daily to every 8 hours.
Specific monitoring was implemented for exposure cases or information calls with specific substance codes of "water" or "contaminated water," because water had specifically been mentioned as a target route of dissemination. National counts were graphed daily to identify any increase in total or symptomatic cases.
Specific monitoring for the volume of cases with a substance code in the food poisoning/food product category had been implemented 1 month earlier and continued to run throughout this period, with daily alerts of increased numbers of cases by poison centers. In addition, national counts were graphed daily to identify any increase in cases.
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RESULTS |
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Environmental Sampling
All of the samples tested negative by time-resolved fluorescence immunoassay for ricin.
Postal Worker Health Assessment
Of the postal office employees who worked in the receiving and sorting area of the mail facility, 36 were interviewed. The mean age was 47 years (range 23–58 years); 22 were men. The following information was collected from workers: demographic information, a history of direct package contact, and symptoms consistent with ricin-associated illness since the discovery of the package. Four (11%) reported touching the package. Two of these workers said they were wearing gloves while handling the package; 1 reported not wearing gloves, and 1 did not respond. Seven (19%) of the workers interviewed, responded "no" to contact with the package but reported being near the package or area where it was found.
All 36 of the postal workers were asked if they had symptoms of possible ricin-associated illness. Symptoms were classified as "gastrointestinal" (abdominal pain, vomiting, and diarrhea), "respiratory" (cough, chest tightness, and dyspnea), "skin and mucous membranes" (redness and pain of eyes and skin), "general" (fever, fatigue, weakness, muscle pain, and dehydration), or "other" (blood in urine and seizures). Eight (22%) of the 36 workers reported 1 or more symptoms, including the following: cough (4), diarrhea (3), abdominal pain (3), throat irritation (2), nausea (2), fatigue (2), vomiting (1), reflux (1), fever (1), muscle pain (1), sinus pressure (1), and chest tightness (1). Only 1 worker with symptoms reported touching the package. Detailed interviews identified other etiologies for the symptoms (on the basis of clinical judgement).
Surveillance
Hospital surveillance identified a suspected case of ricin-associated illness on October 23, 2003; the person had become ill on October 20, 2003, with fever, pneumonia, and shock. However, further investigation revealed Staphylococcus aureus sepsis and acute leukemia. In a different hospital, a 51-year-old woman presented with fever, shock, multisystem organ failure, and abdominal pain and was ultimately diagnosed with ischemic bowel disease and pancreatitis. On October 30, 2003, a 45-year-old man presented at a local hospital with hypothermia, multisystem organ failure, a white blood cell count of 25 000, and a desquamating erythematous rash. His clinical diagnosis was sepsis. All 3 of the cases were determined to be unrelated to ricin exposure.
Approximately 99 000 human exposures and 50 700 information calls were reported to TESS between October 15, 2003, and October 29, 2003. No suspected or confirmed cases of ricin-associated illness were identified. On October 26, 2003, total calls regarding contaminated water were greater than expected (28). However, only 2 were symptomatic, and most were from a single event in a distant state. No changes were seen in the baseline volume of food poisoning or food product calls either nationally or in a 6-state region surrounding the incident. Over the 2-week period after the incident, 219 total call-volume outliers and 140 human exposure call-volume outliers were signaled by TESS and reviewed. Additional information from the reporting poison center was obtained for 5 of the total volume outliers and 6 of the human exposure outliers. No outliers were associated with identifiable cases of ricin-associated illness. Likewise, of the 39 clinical effect outliers reported and reviewed during the period (1 to 6 reported daily), none revealed cases of ricin-associated illness.
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DISCUSSION |
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TOPABSTRACTINTRODUCTIONMETHODSRESULTSDISCUSSIONReferences |
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Decisions regarding public health risk assessment are difficult and often rely on a variety of data sources. This is especially true in situations where environmental sampling is needed to assist in the health risk determination but sampling criteria and result interpretation are not well established. The ongoing collaboration between AAPCC and CDC using TESS as a toxicosurveillance tool enhanced the ability to conduct national surveillance for cases of ricin-associated illness.13,14 The anthrax experiences of 2001 fostered the development and maintenance of a closer relationship between public health and law enforcement officials.15 Early recognition of a need for inclusion of personnel with varied areas of expertise and use of multiple data sources for public health threat risk assessment was vital to the success of the investigation.
State and local public health surveillance can be an important key to the identification of symptoms that may be consistent with ricin-associated illness. The response to the South Carolina Health Alert Network public health advisories calling for enhanced surveillance by clinicians increased the index of suspicion for possible cases and is evidenced by the reporting of 3 potential ricin-associated illness cases. The rapid initiation of this network likely enhanced surveillance. All of these activities exemplify the need for close collaboration between health care facilities and state and local public health in reporting unusual or unexplained illnesses.
The environmental sampling strategy and methods used in this investigation were based on previous experience with anthrax, as well as specialized industrial hygiene knowledge of exposure assessments and biological sampling methods.8,9,16,17 In this and similar exposure scenarios, investigators must first define the goal of environmental sampling and ask what question or questions the data are intended to answer. Many factors need to be considered in determining an appropriate sampling strategy and are listed in the box on page S156.8,9,16,17
Factors to be Considered in Determining an Appropriate Environmental B Sampling Strategy
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A targeted sampling strategy, like the one used in this incident, is typically the most rapid, efficient, and successful manner for conducting an environmental sampling investigation when information is available on the path of the terrorism source or vehicle.10 A statistically based sampling strategy was considered undesirable and impractical, because the health risk from residual ricin exposure is currently unknown, and no validated environmental sampling methods exist for ricin. Sample numbers and surface sample sizes cannot be calculated based on known risk; therefore, they must be determined using practical experience, observation, and good industrial hygiene practices.11
Different types of environmental sampling methodologies exist; however, surface sampling with wipes or moistened swabs is usually recommended for nonporous surfaces.17 Absorbent materials and collection media are variable and agent dependent.17 Swab samples may be the best method for sampling smooth, hard surfaces not amenable to wipe or vacuum sampling, such as computer keyboards.16,17 Vacuum collection techniques offer the ability of targeting large, dusty, non-porous surfaces, such as carpeting, ceiling tiles, ventilation filters, and cloth seats.17 Other factors to consider include the number of environmental samples needed to insure that the sampling is representative of the extent of contamination and the number of field blanks (control specimens).10 Field blanks should constitute at least 10% of the total number of samples and are obtained to assess for cross-contamination during sample collection.18
Interpretation of environmental sampling results must include an industrial hygienist and potentially other professionals, such as clinicians, laboratory personnel, and public health officials; for agents such as ricin, a clinical toxicologist should be consulted. Environmental sampling results should be used in conjunction with other outbreak investigation information, such as the epidemiological investigation, personnel work practice information, and an evaluation of the facility engineering plan to properly assess the public health threat.
Identifying compatible clinical illness when positive environmental sampling results are lacking should concern health care officials. This may indicate a problem with unvalidated, environmental sampling techniques and may represent false-negative results. Care must also be used in interpreting "negative" test results with regard to uncertain limits of analytic detection. In other words, a negative test result may not be truly negative but may fall just under the current level of detection.
In response to this event and other ricin-associated events, the Office of Public Health Emergency Preparedness within the Department of Health and Human Services coordinated the development of a national ricin response plan that provides guidelines for federal, state, and local public health and medical officials to follow in the event of a ricin-associated public health threat.19 This document is currently being institutionalized and is a technical resource for the public health and medical response to a ricin-associated event. It covers areas such as response worker health and safety, sampling and laboratory analysis, medical treatment, public information, risk communication, and decontamination.
This incident further emphasized the need for both a rapid local epidemiological response to events of public health significance, as well as clarification of response protocols between nontraditional public health partners, such as the USPS. The expansion of the Biohazard Detection System (for anthrax detection) across the United States has further identified the need for public health to be involved in the response to events of this nature. Working with the USPS during the deployment of the South Carolina Biohazard Detection System has enhanced communication with these partners in South Carolina and established protocols to facilitate a more rapid response to suspected or known hazards.
The SC DHEC uses the software program ToxiTrack (Computer Automation Systems, Aurora, CO) to analyze poison center data on a daily basis. The efficacy of ToxiTrack is its compatibility with the local poison center’s data system. The SC DHEC is also currently working to incorporate this daily electronic stream of data into the CDC Early Aberration Reporting System for analysis. Although Toxi-Track had been in use at SC DHEC since 2000, the system was not used during this incident, because this was a new diagnosis, and optimal categorization of toxidromes specific enough for ricin was not available.
The occurrence of multiple ricin-associated events has contributed to continued research into the development of laboratory methodologies to assess exposure. Since this incident, methodology for the analysis of biological specimens for ricinine has been distributed to select laboratories within the Laboratory Response Network, a network of various local, state, and federal laboratories that provides a specialized testing capability for public health threats.
Limitations
Uncertain factors with respect to environmental sampling for ricin exist, such as collection efficiency, recovery efficiency, appropriate number of samples to collect, and actual sensitivity and specificity of the environmental sampling techniques described. This ultimately complicates result interpretation. The possibility of false-negatives and that true cases of ricin-associated illness were missed in all of the surveillance efforts also exists. However, the results of our investigation can be used in planning for future work to develop validated environmental sampling standards for ricin.
Conclusions
The Greenville incident effectively demonstrated the need for a systematic multiagency, multidisciplinary, and comprehensive approach toward chemical-associated public health threats, such as ricin. These responses must include environmental sampling to assess the extent of contamination, epidemiological assessment to determine exposure risk, surveillance for clinical illness, and risk communication. Careful preidentification and inclusion of personnel with appropriate subject matter expertise is vital. In this incident, professionals trained in epidemiology, medical toxicology, communication, and industrial hygiene were essential. The results of the investigation into the potential ricin contamination of a South Carolina postal facility determined that the postal facility was safe for re-entry of personnel and that no evidence for a public health threat existed.
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Acknowledgments |
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All support for this project was from internal funding from the Centers for Disease Control and Prevention. State personnel and activities were funded through the state’s internal budget.
The authors acknowledge the assistance of the following organizations and individuals in the investigation and in the preparation of this article: Jill Michels, PharmD and Brooks Metts, PharmD (South Carolina’s Palmetto Poison Center), Dan Sosin, MD (Centers for Disease Control and Prevention), and Keith Holtermann, DrPh (Office of Public Health Emergency Preparedness).
Human Participant Protection
This investigation was determined to be public health practice, and no protocol approval was required.
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Footnotes |
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Peer Reviewed
Note. The findings and conclusions in this report are those of the authors and do not necessarily represent the views of the Centers for Disease Control and Prevention/Agency for Toxic Substances and Disease Registry.
Contributors
M.M. Patel, A. Patel, S. Deitchman, M. Keifer, D. Drociuk, N. Fitzpatrick, and M. Schwartz conducted environmental sampling, patient interviews, and local surveillance. W. A. Watson and T. Litovitz conducted national and regional surveillance. R. Meyer conducted the analysis of environmental samples. J. G. Schier, M. G. Belson, and C. H. Rubin led the coordination of surveillance activities, development of the surveillance materials (e.g., case definition), development of educational and risk communication materials, and coordination of the development of the article. All of the authors helped to conceptualize ideas, interpret findings, and review drafts of the article.
Accepted for publication December 21, 2006.
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References |
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TOPABSTRACTINTRODUCTIONMETHODSRESULTSDISCUSSIONReferences |
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