[Federal Register Volume 68, Number 140 (Tuesday, July 22, 2003)]
[Notices]
[Pages 43356-43358]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 03-18601]


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DEPARTMENT OF HEALTH AND HUMAN SERVICES

Centers for Disease Control and Prevention


Proposed Airborne Exposure Limits for Chemical Warfare Agents H, 
HD, and HT (Sulfur Mustard)

AGENCY: Centers for Disease Control and Prevention (CDC), Department of 
Health and Human Services (HHS).

ACTION: Notice of proposed worker and general population airborne 
exposure limits (AELs) for chemical warfare agents H, HD, and HT 
(sulfur mustard) to protect the health and safety of workers and the 
public during treatment, transport, or disposal of these agents.

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    Purpose: CDC presents results of its review of AELs for the 
chemical warfare agents H, HD and HT (collectively referred to as 
sulfur mustard, bis(2-chloroethyl)sulfide, CAS 505-60-2).\1\ All three 
compounds are chemically and toxicologically related and therefore will 
be treated here as a single compound represented by HD. Before 
finalizing these proposals, CDC requests comments from the public, all 
interested parties, environmental and health regulators, the Department 
of Defense (DOD), and other organizations involved in handling or 
demilitarizing chemical warfare agents. More specifically, CDC seeks 
scientifically and professionally defensible data or information that 
would be helpful in this evaluation of the AELs for sulfur mustard.
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    \1\ HD is distilled sulfur mustard that has been purified by 
washing and vacuum distillation, whereas Levinstein mustard (H) 
contains about 30 percent sulfur impurities and has stronger 
vesicant action. HT consists of 60 percent HD and 40 percent T 
(related vesicant with lower freezing point and much lower 
volatility), with reportedly similar characteristics to HD. T is not 
expected to constitute an airborne vapor hazard.
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    Preamble: This proposal updates the sulfur mustard AELs recommended 
by CDC in 1988. In preparing this proposal, CDC found some evolution of 
the methods used to derive AELs and some additional toxicity data 
available for consideration. Even though no empirical evidence 
indicated that the existing AELs for mustard are not protective of 
health, CDC believed the new methods and information should be examined 
for potential impacts on the exposure criteria. Considerations and 
logic used to arrive at the proposed AELs may be requested from the 
contact listed at the end of this announcement.
    When reviewing the methods used to derive AELs, CDC found that the 
Environmental Protection Agency's (EPA's) traditional ``reference 
concentration'' (RfC) method (based on no observed adverse effect 
level/lowest observed adverse effect level [NOEL/LOAEL] values) and the 
newer categorical regression, or ``CatReg'' method, are both undergoing 
internal review that could result in future variation in the way they 
are applied and the numeric values ultimately derived. Accordingly, CDC 
decided that both methods should be examined to help define a range of 
potential values for the proposed AELs. This announcement summarizes 
CDC's

[[Page 43357]]

findings and the resultant AELs being proposed. The proposed values 
were developed in the context of applying professional judgment and did 
not rely exclusively on any one method. Accordingly, the proposed AELs 
reflect realistic risk management provisions associated with chemical 
demilitarization and do not necessarily apply to other purposes.
    CDC believes that incorporating risk management into the risk 
assessment process is necessary and beneficial for the following 
reasons: Extensive experience has shown that any exposure would be 
expected to be episodic and acute; extensive air monitoring, 
engineering, and procedural safeguards have effectively limited 
exposures; and competing risks would be introduced if existing 
requirements were significantly changed. Consequently, this proposal is 
predicated on CDC's understanding of existing demilitarization 
safeguards and procedures.
    Rather than specify an 8-hour time-weighted average, CDC proposes 
to designate a 5-minute ceiling level that reflects the extensive near-
real-time monitoring systems associated with chemical demilitarization 
activities. Additionally, CDC proposes to recommend a 12-hour general 
population limit (GPL-12), applicable to both the general population 
and workers, to confirm that low-level exposure is not occurring. The 
time duration of the GPL-12 is consistent with the sampling period for 
existing air monitoring methods and the long work shifts in many 
demilitarization operations.
    CDC recommends a GPL value to allow facility perimeter monitoring 
levels to be set at a concentration that ensures that carcinogenicity 
protection goals are met. CDC proposes to change the definition of the 
GPL to reflect the probable short duration of potential exposures to 
the general public. Further discussion of this redefinition appears in 
the available support documentation.
    CDC believes this proposal meets the goals of protecting workers 
and the public at potential airborne concentration levels below those 
which would result in adverse health effects or irritation for acute 
exposures, and further protects against risk of cancer from long-term 
exposure. The criteria proposed in this announcement protect at a risk 
level below one in one million excess cancers, which is considered to 
be insignificant.

SUMMARY: CDC's proposals are based on comments by individual scientific 
experts and interested participants at a public meeting convened by CDC 
on September 11-12, 2001, in Atlanta, GA; the latest available 
scientific data and technical reviews; exposure and risk assessment 
approaches (e.g. CatReg and RfC methods); and CDC's understanding of 
current risk management practices associated with the U.S. Army's 
chemical agent demilitarization program. As a result of this re-
evaluation of the data and the continuing evolution of AEL derivation 
methods, CDC proposes that the 1988 worker population limit (WPL) of 
0.003 mg/m\3\, currently an 8-hour time-weighted average (TWA), becomes 
a 5-minute Ceiling limit value (CEILING-5M); and the GPL of 0.0001 mg/
m\3\, currently a 72-hour time-weighted average (GPL-72), becomes a 12-
hour TWA (GPL-12) and it is adjusted to 0.00002 mg/m\3\ to meet 
carcinogenicity protection levels below thresholds of significant risk 
(Table 1). CDC also proposes that historical monitoring at the new GPL-
12 be implemented where workers are assigned, if reasonable potential 
exists for mustard exposure. This is to ensure that undetected low-
level exposure is not occurring. The proposed Immediately Dangerous to 
Life or Health (IDLH) value of 0.7 mg/m\3\ was derived by CDC/National 
Institute for Occupational Safety and Health (CDC/NIOSH) in accordance 
with standard NIOSH protocol.

                                                 Table 1.--CDC Proposed Mustard Airborne Exposure Limits
                                                        [All values expressed as mg/m\3\ in air]
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                                                                                                            Proposed general
                                       Existing worker     Proposed worker daily    Existing general        population limit       Proposed immediately
   Mustard (H, HD, HT) criteria     population limit (WPL-     ceiling limit        population limit    (includes workers) (GPL-   dangerous to life or
                                              8)               (CEILING-5M*)            (GPL-72)                  12*)                health (IDLH)
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Exposure Level....................  0.003................  **0.003..............  0.0001..............  0.00002................  0.7[Dagger]
Averaging Time....................  8 hours (TWA)........  <=5 minutes..........  72 hours (TWA)......  <=12 hours[dagger]       <=30 minutes
                                                                                                         (TWA).
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* Administrative or appropriate personal protective equipment is required if mustard vapor exposure exceeds criteria.
** To be evaluated with a near real-time instrument with a cycle time of not more than 5 minutes.
[dagger] To be evaluated with historical air monitoring method with analysis within 72 hours of sampling (applicable to worker and general population to
  detect low-level excursions of agent). The action level is recommended to be set at the GPL for this criterion.
[Dagger] The 30-minute period is not meant to imply that workers should stay in the work environment any longer than necessary; in fact, they should
  make every effort should be made to exit immediately. IDLH condition requires highly reliable dermal and respiratory protection providing maximum
  worker protection.

    Although the proposed CEILING-5M is numerically identical to the 
existing 1988 CDC criteria, the averaging time has been changed to 
reflect actual operating conditions associated with ongoing 
demilitarization activities. The averaging time for the GPL similarly 
has been changed to reflect actual practice. As discussed in the 
supporting documentation, these changes reduce the potential dose 
associated with an exposure at each limit.
    CDC believes that the proposed limits will protect workers and the 
public from potential acute and long-term (e.g., carcinogenic) adverse 
health effects from exposure to H, HD, and HT. Comments are hereby 
sought to help CDC refine their evaluation prior to issuing final 
recommended AELs.

DATES: Submit comments on or before October 1, 2003.

ADDRESSES: Comments may be submitted several ways:
    1. By mail. Submit your comments to Dr. Paul Joe, Centers for 
Disease Control and Prevention, 4770 Buford Highway, Mail Stop F-16, 
Atlanta, Georgia 30341.
    2. In person or by courier. Deliver your comments to the address 
listed above.
    3. Electronically. Submit your comments by e-mail to [email protected], 
or submit a computer disk to the address indicated above. Electronic 
documents will be accepted in Corel WordPerfect[reg] or Microsoft 
Word[reg] formats.
    For a Copy of CDC's Detailed Proposal: Dr. Paul Joe, Centers for 
Disease Control and Prevention, 4770 Buford Highway, Mail Stop F-16, 
Atlanta, GA 30341, Telephone number:

[[Page 43358]]

770-488-7091, E-mail address: [email protected].

    Dated: July 16, 2003.
Joseph R. Carter,
Associate Director for Management and Operations, Centers for Disease 
Control and Prevention.
[FR Doc. 03-18601 Filed 7-21-03; 8:45 am]
BILLING CODE 4163-18-P