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NIOSH Respiratory Diseases Research Program

Evidence Package for the National Academies' Review 2006-2007

6.2 Anthrax

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The use of naturally occurring infectious agents to inflict deliberate harm has become a major concern following the anthrax attacks of 2001. Anthrax is a potentially deadly disease caused by Bacillus anthracis, a bacterium that forms spores. Inhalational anthrax can result from spore inhalation. It causes severe illness with a mortality rate exceeding 50 percent. In 2001, seven anthrax- contaminated letters (investigators recovered four and presumed three others) sent through the U.S. Postal Service (USPS) killed five people and infected at least 17 others with inhalational or cutaneous anthrax (A6-45).166 In part due to lack of information about the most cost effective approaches to decontamination, the anthrax attacks also led to huge expenditures for decontamination. It is estimated that $42 million was spent decontaminating the Hart Senate Office Building and other Capitol Hill offices (A6-46).167 Decontaminating the Brentwood postal facilities in Washington, D.C. and Hamilton Township, New Jersey, cost in excess of another $100 million (A6-47).168 Implementation of additional preventive strategies to protect USPS workers, the general population, and decontamination workers added substantially to these costs. Significant questions remain about exposure assessment and disease prevention in the face of an attack.


RDRP contributed to the national effort to protect workers from the threat of anthrax-contaminated mail by sending personnel to staff the CDC and DHHS Emergency Operations Centers and to the six locations where workers were at risk: Florida, New York, New Jersey, Connecticut, and the Washington, D.C. regional area, which includes Maryland and Virginia.

RDRP developed sampling procedures, recommended effective interim protective measures, safeguarded workers who decontaminated affected workplaces, assessed the effectiveness of decontamination, and disseminated protection information. Sampling technologies were used in innovative ways, such as adapting a vacuuming technique using an "allergy sock," a method originally developed to measure allergens, to provide a more sensitive, comprehensive way to collect anthrax samples at large postal facilities.

RDRP and partner agencies provided information to USPS managers, workers, and unions to help assess exposures at postal facilities and on Capitol Hill. We conducted sampling in the following areas: 1) seven locations in Florida for the AMI Non-postal worker cases; 2) 10 locations in New York City for the media and hospital employee non-postal worker cases; 3) 54 locations in New Jersey to investigate the Hamilton/Trenton postal worker cases; 4) the six Congressional office buildings; 5) 55 locations in the Washington, DC metro area for the Brentwood postal worker cases and 6) two locations in Connecticut for the Wallingford non-postal worker case.  We also conducted sampling at the Kansas City Stamp Fulfillment Center in Missouri to determine if there was cross-contamination from the Brentwood Post Office. We provided technical assistance on workplace sampling procedures and personal protective equipment for decontamination workers to aid in EPA’s clean-up of contaminated government buildings. We worked with the EPA and others to determine when remediated Congressional buildings were ready for re-occupancy by performing surface sampling after the clean-up and decontamination was completed. 

Outputs and Transfer

Since the anthrax attacks of 2001, RDRP scientists have produced 33 technical journal articles, six books or book chapters, four NIOSH numbered publications, 12 abstracts and presentations at professional conferences and meetings, 10 control technology reports, and four HHE reports (A6-48).

Along with partner agencies, RDRP scientists provided information on-site to employers, workers, facility managers, and a labor-management task force (postal worker unions and the USPS) in efforts to assess exposures at postal facilities, on Capitol Hill, and at affected news media facilities (A6-49). RDRP, in collaboration with other CDC centers, OSHA, the USPS, postal worker unions, and other stakeholders, developed and disseminated recommendations for personal protective equipment and engineering controls for protecting mail handlers, first responders, investigators, and remediation workers. Many of these recommendations and Fact Sheets were rapidly posted to the CDC Anthrax Emergency Preparedness and Response Web site (A6-50). Immediately following the discovery of anthrax spores in the USPS system, RDRP staff helped develop the “CDC Interim Recommendations for Protecting Workers from Exposure to Bacillus anthracis in Work Sites Where Mail Is Handled or Processed” (A6-51). RDRP also released an interim notice to responders and investigators describing appropriate Personal Protective Equipment (PPE), including respiratory devices, protective clothing, and gloves (A6-52). This was followed by a more detailed notice on appropriate PPE for investigators collecting B. anthracis sampling (A6-53). These guidelines were eventually combined in “Notice to Readers: Occupational Health Guidelines for Remediation Workers at Bacillus anthracis-Contaminated Sites—U.S., 2001-2002” released on September 6, 2002 (A6-54).

NIOSH released RDRP-generated document entitled “Procedures for Collecting Surface Environmental Samples for Culturing Bacillus anthracis,” which described methods for environmental sampling to detect the presence of anthrax spores in indoor environments (in subsequent revisions, the title was modified to “Comprehensive Procedures for Collecting Environmental Samples for Culturing Bacillus anthracis”) (A6-55). To deal with the need for quick and sensitive approach for sampling anthrax at large postal facilities and other sites, the recommended sampling technologies represented innovative adaptation and application of existing methods (e.g. a method originally developed to measure allergens in settled dust).

As the anthrax remediation efforts continued at USPS facilities and at government facilities on Capitol Hill, RDRP provided technical assistance on workplace sampling procedures for decontamination workers (A6-49, A6-55). RDRP scientists, along with other CDC researchers and outside contractors published “Environmental sampling for spores of Bacillus anthracis” and “Surface Sampling Methods for Bacillus anthracis Spore Contamination,” describing sampling results from RDRP field sampling at the USPS Brentwood facility (A6-56, A6-57). RDRP staff helped to train Federal Bureau of Investigation (FBI), U.S. Coast Guard, independent contractors, and other personnel in appropriate anthrax decontamination procedures, and RDRP staff worked with the EPA and others to determine when decontaminated congressional buildings were ready for re-occupancy (A6-49).

After the anthrax attacks, the USPS began irradiating mail pieces to destroy pathogenic bacteria and viruses that could be present in the mail. Shortly thereafter, federal workers began reporting health symptoms they believed were related to handling irradiated mail. These reports came to RDRP attention by way of HHE requests from the USPS, the U.S. Office of Personnel Management, the Sergeant at Arms of the U.S. Senate, and the Chief Administrative Officer of the U.S. House of Representatives. In response to these requests, RDRP conducted three HHEs on handling of irradiated mail by postal employees, federal workers, and Congressional employees. Teams of RDRP investigators, including industrial hygienists and occupational medical physicians surveyed employees about their symptoms and monitored the air for chemical by-products that could be released from the mail. Final reports were issued for each of these HHE investigations (A6-58, A6-59, A6-60). 

In response to the anthrax attacks, the USPS developed an emergency preparedness plan to protect postal employees and customers from future exposures to biohazardous agents and to ensure mail security from future bioterror attacks (A6-61).169 RDRP researchers worked with the USPS to develop a testing methodology for new Biological Detection Systems (BDS) to rapidly detect anthrax during mail sorting operations. An overview of the BDS is on the Web site ( [External link]). RDRP also worked with USPS to develop new ventilation and filtration systems (VFS) to capture any releases of bioterror agents during mail processing. Studies were conducted on prototype BDS and VFS systems installed at various USPS Processing and Distribution Centers, including those in Baltimore, Maryland; Merrifield, Virginia; Dulles, Virginia; and Cleveland, Ohio. A total of 10 control technology reports were released outlining results from these studies (A6-48). Additionally, two papers were published in the Journal of Occupational and Environmental Hygiene, entitled “Development of Evaluation Procedures for Local Exhaust Ventilation for USPS Mail-Processing Equipment” and “Evaluation of a High-Efficiency Filter Bank System” (11, 12, A6-62, A6-63). 

Other RDRP outputs and dissemination efforts included developing a widely distributed CDC educational video to promote protection of workers who process, sort, and deliver mail (A6-64); working around the clock responding to requests for help and information; and posting documents pertaining to anthrax and worker health and safety on the NIOSH Web page (A6-65). RDRP engineers developed extensive guidance to protect buildings and building occupants from future terrorist attacks, released in 2002 as “Guidance for Protecting Building Environments from Airborne Chemical, Biological, or Radiological Attacks” (A6-66). This was followed in 2003 by a closely related guidance document, “Guidance for Filtration and Air-Cleaning Systems to Protect Building Environments from Airborne Chemical, Biological, or Radiological Attacks” (A6-67). These guidance documents have been widely disseminated to building managers for use in making decisions on appropriate actions to protect their facilities from possible attacks.

 In addition to producing guidance documents, NIOSH/RDRP personnel helped train FBI, Coast Guard, private contractors, and other personnel in appropriate anthrax decontamination procedures.

 Intermediate Outcomes

 RDRP helped the USPS to decontaminate its facilities and install and operate equipment for future routine processing of mail. Based on RDRP testing results, the USPS awarded approximately $125 million in contracts for 280 VFS to be installed at mail processing and distribution centers throughout the country (A6-68).170 The installation of new VFS and BDS systems, which improve local exhaust ventilation and offer biological agent detection capabilities to reduce the vulnerability of postal workers to bioterrorism agents, while ensuring safe mail to all postal customers, is scheduled for completion by the end of 2006 (A6-69).171 RDRP scientists continue to address issues related to irradiated mail through participation in the Legislative Mail Task Force, convened by the Sergeant at Arms of the U.S. Senate and the Chief Administrative Officer of the U.S. House of Representatives (A6-70).

RDRP efforts in clean-up and sampling to ensure that the risk had been mitigated are documented by the testimony of Dr. James L. Hadler of the Connecticut State Health Department to the Subcommittee for national security, emerging threats and international relations (External link) (A6-71).

The documents, “Guidance for Protecting Building Environments from Airborne Chemical, Biological, or Radiological Attacks” (A6-66) and “Guidance for Filtration and Air-Cleaning Systems to Protect Building Environments from Airborne Chemical, Biological, or Radiological Attacks” (A6-67) have been very influential. A Google search shows them to have been cited by a variety of governmental and non-governmental organizations, including the White House (A6-72).


Five people died as a result of the anthrax attacks of 2001. RDRP, together with many other groups, likely played an important role in preventing additional morbidity and mortality.

What’s Ahead

 NIOSH and RDRP will maintain a state of readiness to respond within the context of CDC and PHS actions in the event of future attacks.

RDRP has developed methods and is in the process of doing studies using anthrax simulants to better understand how mail becomes cross-contaminated. This project will use letters from the original attacks obtained from the FBI to confirm that results obtained using simulants will parallel that of anthrax itself. Work with anthrax will be accomplished at the Edgewood Chemical and Biological Center, Aberdeen Proving Ground, MD.

Another study in progress is characterizing spore migration patterns in building ventilation systems.

Another project underway through a contract with Battelle is to develop a publicly-available database of methods for anthrax sampling. It will address both sample collection methods and analytical methods. Methods are being developed to categorize the level of validation of these methods, which will be included in the database.

See also “What’s Ahead” in chapter 6.3b, which addresses RDRP’s role in the CDC initiative in environmental microbiology. This initiative is relevant to all occupational infectious diseases that can be transmitted via the airborne route.

166. Johnston WR [2006]. Review of Fall 2001 Anthrax Bioattacks.
External link: Accessed September 5, 2006.

167. Office of Senator Charles E. Grassley [2002]. Press Release. Grassley: Latest Cost Estimate of Capitol Hill Anthrax Clean-Up Is $41.7 Million.
External link: Accessed September 5, 2006.

168. Shane S [2002]. Cleanup of anthrax will cost hundreds of millions of dollars. Baltimore Sun. December 18, 2002.

170. United States Postal Service [2003]. Press Release. Air System will Protect Postal Employees, Mail. November 17, 2003.
External link: Accessed September 7, 2006.

171. United States Postal Service [2005]. 2005 Comprehensive Statement on Postal Operations. Washington, D.C., United States Postal Service.
External link: Accessed September 7, 2006.