Impact of Revised Airborne Exposure Limits on Non-Stockpile Chemical Materiel Program Activities (2005)

This report assesses the impact of newly promulgated airborne exposure limits (AELs) for nerve agents and mustard on the program of the U.S. Army Non-Stockpile Chemical Materiel Product (NSCMP). This program, informally referred to as the non-stockpile program, consists of agent and munition disposal operations and the dismantlement and destruction of former production facilities. Operations range in scope from destruction of a single recovered chemical weapon or a few chemical agent identification sets (CAIS) to destruction of more than 1,200 recovered chemical weapons at the Pine Buff Arsenal (PBA) and dismantlement and destruction of the former VX production facility at the Newport Chemical Depot (NECD), near Newport, Indiana.¹

A much larger program is in place for the destruction of the Army’s stockpiled chemical weapons (the stockpile program). The stockpile originally consisted of chemical weapons and storage containers holding over 30,000 tons of agent in eight states and on Johnston Island in the Pacific Ocean (U.S. Army, 2004a). Non-stockpile operations are in general smaller and shorter in duration than stockpile operations. Both programs fall under the direction of the U.S. Army Chemical Materials Agency (CMA), and technical oversight is provided to both programs by the NRC.

For both the stockpile and non-stockpile programs, the operations workforce and the populations in the neighborhood of these operations must be protected against the risks of exposure to hazardous materials. To accomplish this, a program must be in place to monitor hazardous materials in and near the workplace and to monitor workers’ activities and health. A previous NRC stockpile report examined the programs in place for monitoring hazardous materials at two stockpile facilities, the Johnston Atoll Chemical Agent Disposal System (JACADS) and the Tooele Chemical Agent Disposal Facility (TOCDF) (NRC, 2001c).

The Department of Health and Human Services is required by law to review Department of Defense plans for disposing of chemical munitions and to make recommendations to protect public health. Its activities include the establishment of recommended values for AELs, which are the allowable concentrations in the air for occupational and general population exposures to airborne chemical agents. Table 1-1 defines four types of AELs.

In response to a request from the U.S. Army’s Office of the Surgeon General in June 2000,² the Centers for Disease Control and Prevention (CDC), in October 2003 and May 2004, recommended new AELs for certain chemical agents (Federal Register, 2003a, 2004). Their implementation by the non-stockpile program is the focus of this report.

Agent can be present in workplace air in vapor or aerosol form or both, but the AELs are independent of agent form. The committee notes that the CDC did not specify an agent’s physical state in its Federal Register notices or its background materials. Similarly, Army documentation developed to implement the new AELs for workplace air monitoring did not differentiate between vapor and aerosol exposure.

The new AELs apply to all CMA activities, both stockpile and non-stockpile. However, the committee’s focus was limited by the statement of task to certain non-stockpile activities: the demolition of the Army’s former VX production facility at NECD and two mobile systems for the destruction

of recovered chemical weapons—the explosive destruction system (EDS) and the rapid response system (RRS). The committee reviewed and assessed the new recommended AELs, the techniques employed for their revision, the monitoring technologies used for determining compliance with the AELs, the demolition of the former production facility at NECD, and the operation of the two mobile destruction systems. Its assessments of and recommendations on implementing the new AELs are presented in this report.

Because the charge to the committee was narrow, the committee accepted the new CDC-derived AELs as a starting point for its evaluation of the monitoring program. That is, the committee did not evaluate the process used by the CDC in revising the 1988 limits or the end points it selected, nor did it take a position on the appropriateness of the 2003/2004 CDC-recommended AELs. Nevertheless, the committee does point out in Chapter 3 that there is no risk benefit to be gained with the new AELs. It discusses the 2003/2004 AELs at some length, along with how they differ from the prior limits, because understanding the degree of uncertainty in these just-released 2003/2004 AELs was necessary to understand the role of monitoring in implementing the AELs.

The Chemical Weapons Convention (CWC), the non-stockpile program, the NECD demolition project, the EDS, the RRS, and the assessment approach of the committee are described next.

For several decades, the United States maintained an extensive inventory of weapons containing chemical agents and chemical agent in bulk storage containers. Details of this inventory were provided in previous NRC reports (NRC, 2002, 2004a). In 1985, on its own initiative, the United States instituted a program to destroy its inventory (NRC, 2004b). Then, in 1993, as a result of the United States’ decision to sign and ratify the Chemical Weapons Convention (CWC),³ deadlines were established for the destruction of the entire inventory. The United States and other signatories of the CWC are now in the process of destroying all declared⁴ chemical warfare materiel (CWM) by the treaty deadlines.⁵

U.S. law and international treaties have divided CWM into two categories: stockpile and non-stockpile. Stockpile materiel includes all chemical weapons available for use in combat, plus agent stored in bulk containers. Stockpile materiel was stored at eight locations in the continental

United States and on Johnston Island, southwest of Hawaii. Destruction of the materiel stored at Johnston Island has been completed, and destruction of the materiel stored at the eight continental locations is either under way or planned.

Non-stockpile materiel is all other chemical weapon-related items. It comprises buried CWM, recovered CWM, binary chemical weapons, former production facilities, and miscellaneous CWM. Much of this non-stockpile materiel was buried on current and former military sites but is now being recovered as the land is remediated. Some CWM also is recovered from current and former test and firing ranges. Non-stockpile items that were in storage at the time of the CWC treaty ratification in April 1997 were to be destroyed within 2, 5, or 10 years, depending on the type of chemical weapon and the type of agent. Non-stockpile CWM recovered after treaty ratification must be destroyed “as soon as possible” (U.S. Army, 2001a). In the past, recovered chemical weapons materiel (RCWM) was transported to the nearest stockpile site for safe storage. While such transportation is still an option for the NSCMP program, concerns about the safety of transporting recovered non-stockpile materiel that may be in various states of deterioration across the nation’s highways, waterways, and air routes have led to decisions to treat these RCWM at or close to the site where they were discovered. The development of mobile treatment systems such as the EDS and the RRS has made this possible.

Before 1991, the CWM disposal effort was limited to stockpile materiel. The Defense Appropriations Act of 1991 directed the Secretary of Defense to appoint a Product Manager for Non-Stockpile Chemical Materiel (PMNSCM) with responsibility for the destruction of non-stockpile CWM.

The most current detailed information available to the committee regarding the numbers, types of agent fills, and explosive configurations of recovered munitions currently stored at the four military sites in the United States that have the largest inventories of non-stockpile materiel is found in Appendix B. According to the CWC, these recovered items must be destroyed by April 29, 2007. About 85 percent of all RCWM in the United States is stored at PBA, in Arkansas (Table B-1, in Appendix B); smaller quantities are stored at Dugway Proving Ground, in Utah (Table B-2), Aberdeen Proving Ground, in Maryland (Table B-3), and Anniston Army Depot, in Alabama (Table B-4). Other sites have smaller quantities (NRC, 2002). Many more chemical munitions will be recovered at burial sites as current and former artillery ranges around the country are remediated; 96 suspect burial locations in 38 states, the U.S. Virgin Islands, and the District of Columbia have been identified.⁶ Whether the munitions recovered to date are representative of those that will be recovered in the future is an open question.

The CWC requires that all former CWM production facilities constructed or used after January 1, 1946, be destroyed. The United States has declared 13 former production facilities in seven states under the CWC. NSCMP was given responsibility for destroying 8 of these facilities, one of which is the former VX production and fill facility (U.S. Army, 1996).

NSCMP has made substantial progress in destroying the facilities for which it is responsible. Demolition of the former VX production facility at NECD was begun in 1998 and was 80 percent complete in January 2004.⁷ Demolition is scheduled to be complete by the CWC deadline of April 29, 2007. Since the CWC does not include a provision for extending this deadline, solving any implementation issues at NECD is urgent. Work done prior to January 2004 showed that the nitrogen piping unexpectedly contained small amounts of VX. Also, the facility was found to be contaminated with organic compounds, probably VX precursors or degradation products having analytical signals similar to the signal of VX. Both factors resulted in a higher-than-expected frequency of alarms from the ambient air monitoring system. This situation and the impact on it of the new AELs are an important focus of this report.

The Army has developed mobile treatment systems to destroy the chemical weapons and chemical samples discovered at scattered sites throughout the United States and to neutralize the contained agent. Sometimes it is not practical for safety or legal reasons to move RCWM from the discovery site to a stationary non-stockpile treatment facility such as the one at Aberdeen or Pine Bluff. In such instances, it is necessary to bring mobile treatment equipment to the place where the recovered chemical item is found or stored.

The recovered chemical munitions and samples fall in two categories, each of which has characteristics that motivated the development of a specialized mobile treatment/disposal system. The categories are these:

• Chemical weapons ranging from small bomblets to 8-inch artillery projectiles. As detailed in Tables B-1

through B-4, many items contain explosive or energetic materials in addition to a chemical agent such as mustard blister agent or a nerve agent—for example, sarin (GB) or VX.

• CAIS, which contain small (up to 110 g per item) samples of chemical agent but no energetic component. These sets were used in the World War II era for training purposes. Over 110,000 sets were produced, but there has been no satisfactory accounting for their fate. It is believed that no sets containing nerve agents exist, but a complete set may contain up to six different agents, mainly blister agents—sulfur mustard (H), nitrogen mustard (HN), and lewisite (L)—and industrial chemicals such as phosgene (CG) and adamsite (DM). The toxic component may be present as an undiluted liquid, in a chloroform solution, or as an adsorbate on charcoal (NRC, 1999).

To deal with these two categories of recovered munitions and samples, two families of transportable treatment systems were developed (NRC, 2002).

The explosive destruction system (EDS), which is described in more detail in Chapter 2, is a versatile device that opens a munition by means of an explosive charge within a closed chamber. The explosion detonates any energetic materials in the weapon and provides access to the chemical fill, which is then destroyed by a neutralizing reagent injected into the EDS chamber. The EDS was originally developed to destroy dangerously unstable munitions that could not be transported.⁸ In practice, however, it has been so successful that it is also being used to destroy stable chemical weapons, whether or not they contain energetics. The Army plans to use multiple EDS units to destroy a large stockpile of recovered chemical munitions stored at PBA (NRC, 2004a).⁹ The original version of the EDS (EDS-1) is being supplemented by a larger version (EDS-2) that can destroy large munitions like an 8-inch projectile or multiple smaller munitions in a single operation.

The rapid response system (RRS) is a transportable system in which CAIS packages are opened in a glove box. Individual vials and bottles in the package are characterized visually and spectroscopically. Those containing industrial chemicals (e.g., CG) are repackaged and shipped to a treatment, storage, and disposal facility (TSDF) for destruction. Vessels containing blister agents—H, sulfur mustard (distilled) (HD), HN, L—are crushed in a small reactor containing a neutralizing reagent. The neutralent and associated solid materials are packaged and shipped to a TSDF for ultimate disposal. The RRS is described in more detail in Chapter 2 and in previous NRC reports (NRC, 1999, 2001b, 2002). The RRS can be either driven or flown to locations where CAIS have been recovered. The RRS is intended to be used at sites where many CAIS vials and/or PIGs—containers for shipping CAIS—containing CAIS sets are found. If only a few CAIS vials are found at a site, PMNSCM deploys a single CAIS accessing and neutralization system (SCANS).¹⁰

In contrast to fixed facilities such as the NSCMP munitions assessment and processing system at Aberdeen Proving Ground, the mobile treatment systems are used in widely varying environments that may dictate different air monitoring requirements, especially for the protection of the general population.¹¹ The types of locations vary, from isolated military reservations, such as Dugway Proving Ground in Utah, to densely populated urban settings, such as the Spring Valley development in Washington, D.C. The need to protect workers at the site is a constant, but protective measures for the general population, such as perimeter monitoring, may vary widely. The current and projected use settings for the EDS and RRS are described below. The operational procedures and activities of the workforce are discussed in Chapter 2. Current air monitoring equipment and procedures are described in Chapter 3 in terms of both protecting workers and ensuring the health and safety of the general population.

In the course of qualifying tests and initial operations at Deseret Chemical Depot in Utah, the first RRS unit (the only one constructed to date) successfully destroyed 1,226 individual CAIS items. In its first field deployment, the RRS was used at Fort Richardson, Alaska, to destroy eight RCWM CAIS PIGs, five RCWM CAIS laboratory packs, and one 85-gallon drum of gear suspected to be contaminated.¹²

A RCRA permit application for operation of the RRS at PBA was submitted to the state of Arkansas in July 2003. The Pine Bluff site will be home base for the RRS and its operating team. When it is not deployed to field sites, it will be used to destroy the inventory of CAIS at Pine Bluff.

One feature of the CWM destruction program is that the Secretary of the Department of Health and Human Services is required to recommend measures as needed to protect the public health (Federal Register, 2004). In practice, these recommended precautionary measures are determined by the CDC, an agency of the Department of Health and Human Services, and include development of AELs for the general public, demilitarization workers, and emergency responders.

Specifically, AELs are issued for tabun (GA, or ethyl N,N-dimethyl-phosphoramidocyanidate, CAS 77-81-6); sarin (GB, or O-isopropyl-methylphosphonofluoridate, CAS 107-44-8); VX (O-ethyl-S-(2-diisopropylaminoethyl)-methylphosphonothiolate, CAS 50782-69-9); and sulfur mustard (H, HT, and HD, or bis(2-chloroethyl) sulfide, CAS 505-60-2). Table 1-2 presents the old (1988) and revised (2003/2004) airborne exposure limits.

In June 2000, the Army asked the CDC to review a proposal by the U.S. Army Center for Health Promotion and Preventive Medicine to reevaluate the existing 1988 AELs for chemical warfare agents and to develop new ones.¹³ Following a period of public review, the CDC issued new values for TWAs and GPLs. The TWAs for GA and GB were reduced to 1/3 of their 1988 values, the TWA for VX was reduced to 1/10 of its 1988 value, and the TWA for HD was reduced to 1/8 of its 1988 value. The GPLs for GA and GB were reduced to 1/3 of their 1988 values, the GPL for VX was reduced to 1/5 of its 1988 value, and the GPL for HD was reduced to 1/5 of its 1988 value. For H and HD, the CDC recommended “retaining the proposed GPL for perimeter monitoring stations at demilitarization facilities and evaluation of the allowable stack concentrations” (Federal Register, 2004, p. 24165). For GA, GB, and VX, the CDC recommended that the GPL “not [be] exceeded at the installation boundary as a consequence of a release …” (Federal Register, 2003a, p. 58351). In addition, the CDC issued revised values for the immediately dangerous to life or health (IDLH) limit and for the short-term exposure limit (STEL). The IDLHs for GA/GB, VX, and HD were set at 0.10, 0.003, and 0.70 mg/m³, respectively. The STELs for GA/GB, VX, and HD were set at 1 × 10⁻⁴, 1 × 10⁻⁵, and 3 × 10⁻³ mg/m³, respectively.

Implementation of the new AEL values for the nerve agents GA, GB, and VX is required by January 1, 2005; for the blister agents H and HD it is required by July 1, 2005 (Federal Register, 2003a, 2004). See Chapter 3 for a more complete discussion of the issuance of the new AELs.

Airborne concentrations for chemical agents have been reported using a variety of numerical conventions. While an individual organization tends to be more or less consistent in the manner in which it reports airborne concentrations, different organizations have used different units (milligrams, micrograms, or nanograms) and different means of expression (decimal values or exponential values). Table 1-3 shows equivalent expressions (across each row) for airborne concentrations. Each row shows a concentration 10 times less than the row above it. The first column shows decimal units in milligrams per cubic meter (mg/m³). The second column shows the equivalent concentration using an exponential expression. The third column shows the equivalent value in micrograms per cubic meter (μg/m³), and the fourth column in nanograms per cubic meter (ng/m³). Historically, the Army has most often used the unit milligrams per cubic meter (mg/m³), expressed as a decimal (see Column 1 in Table 1-3). This report gives concentration values in milligrams per cubic meter but expresses them in exponential form.

This report addresses the measurement of airborne concentrations of VX during the dismantlement of the Army’s former VX production facility at NECD and of nerve agent and the blister agents H and HD during the operation of two mobile chemical weapon destruction systems. The workplace monitoring technologies currently in use are reviewed to determine whether they are capable of (1) reliably indicating that workers involved in these operations are not exposed to dangerous levels of airborne nerve or mustard agent, through either short-term or long-term exposure, (2) reliably indicating that the general public in the vicinity of these operations is not exposed to dangerous levels of airborne nerve or mustard agent, through either short-term or long-term exposure, and (3) verifying compliance with applicable permits and regulations. The report also addresses the adequacy of current engineering controls and personal protective equipment (PPE) to protect workers from exposure to agent in excess of allowable limits. Based on the results of these reviews, appropriate follow-on actions are recommended.

This report specifically addresses the impact of the new AELs on (1) the demolition of the former VX production facility at NECD, (2) operation of the RRS for the destruction of CAIS, and (3) operation of the EDS for the destruction of recovered chemical weapons. For the RRS, the location of interest is the Pine Bluff Arsenal. For the EDS, the locations of interest are Aberdeen Proving Ground, in Maryland; Dugway Proving Ground, in Utah; and the Pine Bluff Arsenal, in Arkansas.

The following statement of task was prepared for the National Research Council by the Army:

• Review and understand the basis for the Centers for Disease Control and Prevention’s (CDC’s) newly promulgated airborne exposure limits (AELs) for GA (tabun), GB (sarin), and VX and proposed CDC AELs for mustard agent and assess the safety and process implications of these standards.

• Review and become familiar with facility designs and operational procedures:

  • For destruction of the former production facility at Newport, Indiana, and

  • For the use of the mobile explosive destruction system and the rapid response system.

• Assess monitoring technologies in use at the existing non-stockpile sites to determine if they are capable of measuring compliance with short- and long-term AELs and determine the degree to which these technologies can be incorporated into overall program monitoring strategies, particularly for the purposes of

process verification and environmental permit compliance.

• If existing monitoring methods are not capable of determining compliance with short- and long-term AELs, evaluate the capability of other monitoring that may achieve the same goal.

• Make recommendations on

  • Application of currently used monitoring methodologies to facilitate non-stockpile activities,

  • Capability of currently used measurement technologies to meet future monitoring requirements,

  • Assessing impacts of newly promulgated AELs on worker and public safety aspects,

  • Alternative measures (e.g., increased personal protective equipment and worker safety training requirements) that may be required to compensate for inabilities to meet standards with existing equipment,

  • Impact of relevant monitoring technologies (for new AELs) and effect on ability to implement in time to meet the CWC treaty deadline, and

  • The critical path regulatory approval and public involvement issues that may arise in developing such a monitoring program.

At its meetings, the committee received a number of briefings (see Appendix C) and held subsequent deliberations. The committee is grateful to the many individuals, particularly LTC Paul Fletcher, the Product Manager for Non-Stockpile Chemical Materiel at the time the committee was formed; William R. Brankowitz, Deputy Product Manager, and, from June 2004, Acting Product Manager, Non-Stockpile Chemical Materiel; and the NSCMP program and CMA staff members, who provided technical information and insights during these briefings. The committee received valuable briefings from Cheryl Maggio of the CMA on the rationale for the establishment of the new AELs and on various aspects of their implementation. Terry Frederick, the Tennessee Valley Authority manager for non-stockpile projects, was very helpful in developing the committee’s understanding of the operations at NECD. Committee members and staff visited the former VX production facility at NECD and the Dugway Proving Ground, Utah, to observe monitoring operations during use of the EDS. Valuable information was also obtained from recent reports prepared by other organizations. These included the following:

• Evaluation of Monitoring Technologies, Phases 1 and 2–Final Report, prepared for the U.S. Army Chemical Materials Agency, Aberdeen Proving Ground, Md., FOCIS Associates Inc., October 14, 2003.

• Implementation Guidance Policy for Revised Airborne Exposures Limits for GB, GA, GD, GF, VX, H, HD, and HT, Department of the Army, Office of the Assistant Secretary of the Army, Installations and Environment, June 18, 2004.

• Final Recommendations for Protecting Human Health from Potential Adverse Effects of Exposure to Agents GA (Tabun), GB (Sarin), and VX, Federal Register, Vol. 68., No. 196, pp. 58348−58351, October 9, 2003.

• Interim Recommendations for Airborne Exposure Limits for Chemical Warfare Agents H and HD (Sulfur Mustard), Federal Register, Vol. 69, No. 85, pp. 24164−24168, May 3, 2004.

• Programmatic Monitoring Concept Plan–Final, U.S. Army Chemical Materials Agency, June 2004.

• Programmatic Laboratory and Monitoring Quality Assurance Program–Final, U.S. Army Chemical Materials Agency, June 2004.

• Acute Exposure Guideline Levels for Selected Airborne Chemicals: Volume 3, National Research Council, 2003.

• Occupational Health and Workplace Monitoring at Chemical Agent Disposal Facilities, National Research Council, 1994.

This information provided a sound foundation for the committee’s deliberations.

Chapter 2 describes the former VX production site at NECD and the mobile destruction systems (the EDS and the RRS). It gives the history of the former VX production site, the main features of the facility, and the procedures being used for its demolition. It also gives more detailed descriptions of the RRS and EDS, focusing on the operational protocols for these systems and reviewing their operational history. Chapter 2 also provides information on current airborne monitoring protocols for the NECD demolition project and for operation of the EDS and the RRS. Chapter 3 addresses the reasons for establishing new AELs and their impacts on worker and public safety and health. The airborne exposure monitoring systems currently in use, including DAAMS and MINICAMS, are reviewed in Chapter 4, which also assesses the ability of the current monitoring technologies and systems to satisfy the new AELs and discusses anticipated needs for monitoring technology upgrades. The process implications of the new AELs are assessed in Chapter 5. Chapter 6 comments on regulatory approval, permitting, and public involvement issues.