[Federal Register Volume 78, Number 84 (Wednesday, May 1, 2013)]
[Rules and Regulations]
[Pages 25377-25380]
[FR Doc No: 2013-09205]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2009-0288; Directorate Identifier 2008-NM-214-AD;
Amendment 39-17435; AD 2013-08-18]
RIN 2120-AA64

Airworthiness Directives; The Boeing Company Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: We are adopting a new airworthiness directive (AD) for certain
The Boeing Company Model 737-600, -700, -700C, -800, -900 and -900ER
series airplanes. This AD was prompted by a report of leaking fuel from
the wing leading edge area at the inboard end of the number 5 leading
edge slat. This AD requires modifying the fluid drain path in the wing
leading edge area, forward of the wing front spar, and doing all
applicable related investigative and corrective actions; and installing
new seal disks on the latches in the fuel shutoff valve access door. We
are issuing this AD to prevent flammable fluids from accumulating in
the wing leading edge, and draining inboard and onto the engine exhaust
nozzle, which could result in a fire.

DATES: This AD is effective June 5, 2013.
    The Director of the Federal Register approved the incorporation by
reference of a certain publication listed in the AD as of June 5, 2013.

ADDRESSES: For service information identified in this AD, contact
Boeing Commercial Airplanes, Attention: Data & Services Management,
P.O. Box 3707, MC 2H-65, Seattle, Washington 98124-2207; telephone 206-
544-5000, extension 1; fax<PHONE_NUMBER>; Internet https://www.myboeingfleet.com. You may review copies of the referenced service
information at the FAA, Transport Airplane Directorate, 1601 Lind
Avenue SW., Renton, Washington. For information on the availability of
this material at the FAA, call<PHONE_NUMBER>.

Examining the AD Docket

    You may examine the AD docket on the Internet at http://www.regulations.gov; or in person at the Docket Management Facility
between 9 a.m. and 5 p.m., Monday through Friday, except Federal
holidays. The AD docket contains this AD, the regulatory evaluation,
any comments received, and other information. The address for the
Docket Office (phone:<PHONE_NUMBER>) is Document Management Facility,
U.S. Department of Transportation, Docket Operations, M-30, West
Building Ground Floor, Room W12-140, 1200 New Jersey Avenue SE.,
Washington, DC 20590.

FOR FURTHER INFORMATION CONTACT: Ansel James, Aerospace Engineer,
Propulsion Branch, ANM-140S, FAA, Seattle Aircraft Certification
Office, 1601 Lind Avenue SW., Renton, Washington 98057-3356; phone:
425-917-6497; fax:<PHONE_NUMBER>; email<EMAIL_ADDRESS>
SUPPLEMENTARY INFORMATION:

Discussion

    We issued a supplemental notice of proposed rulemaking (SNPRM) to
amend 14 CFR part 39 to include an airworthiness directive (AD) that
would apply to the specified products. That SNPRM published in the
Federal Register on March 16, 2012 (77 FR 15638). The original NPRM (74
FR 15683, April 7, 2009) proposed to require modifying the fluid drain
path in the wing leading edge area, forward of the wing front spar and
doing all applicable related investigative and corrective actions. The
SNPRM proposed to revise that NPRM by including installing new seal
disks on the latches in the fuel shutoff valve access door as part of
the modification and by specifying that certain inspections are
detailed inspections. The SNPRM also proposed to revise the
applicability to include additional airplanes.

Revised Service Bulletin

    Boeing has issued Special Attention Service Bulletin 737-57-1293,
Revision 3, dated December 14, 2012. This revision includes
clarification for the re-identification of parts and assemblies. We
have revised paragraphs (c) and (g) of this AD to refer to Boeing
Special Attention Service Bulletin 737-57-1293, Revision 3, dated
December 14, 2012.

Comments

    We gave the public the opportunity to participate in developing
this AD. The following presents the comments received on the
supplemental NPRM (77 FR 15638, March 16, 2012) and the FAA's response
to each comment.

Concurrence

    Boeing concurred with the content of the SNPRM (77 FR 15638, March
16, 2012).

Request for Compliance Time Extension

    United Airlines, Tracinda Flight Department, and American Airlines
requested an extension to the 24-month compliance time specified in the
SNPRM (77 FR 15638, March 16, 2012). Tracinda Flight Department
requested a compliance time of 36 months to coincide with a heavy
maintenance check. American Airlines requested a compliance time of 60
to 72 months to coincide with its scheduled heavy maintenance check.
American Airlines stated that the actions accomplished in accordance
with AD 2011-06-05, Amendment 39-16629 (76 FR 15808, March 22, 2011),
address the safety issue identified in the SNPRM. United Airlines
recommended a compliance time of 60 months for airplanes on which
actions have been done in accordance with AD 2011-06-05, as well as
airplanes having line numbers 2700 and subsequent on which the actions
have been incorporated for the wing slat down stop hardware
modification and inspections.
    We disagree with the commenters' requests to extend the compliance
time. We have determined that the compliance time, as proposed,
represents the maximum interval of time allowable for the affected
airplanes to continue to safely operate before the modification is
done. Since maintenance schedules vary among operators, there would be
no assurance that the airplanes would be modified during that maximum
interval. However, under the provisions of paragraph (i) of the final
rule, we will consider requests for approval of an extension of the
compliance time if sufficient data are submitted to substantiate that a
new compliance time would provide an acceptable level of safety.
Additionally, the issue addressed in this AD is different from the
issue addressed in AD 2011-06-05, Amendment 39-16629 (76 FR 15808,
March 22, 2011); therefore, changing the compliance time based on the
actions done in accordance with AD 2011-06-05 is not acceptable. We
have not changed the AD in this regard.

Request for Change to Airplane Groups

    Southwest Airlines requested a change to the airplanes in Group 2,
as specified in Boeing Special Attention Service Bulletin 737-57-1293,
Revision 2, dated September 28, 2011. The commenter stated that Group 2
airplanes include line numbers 2131 through 2837--instead of 2131
through 2437, as specified in Boeing Special Attention Service Bulletin
737-57-1293, Revision 2, dated September 28, 2011. The commenter stated
that Figures 4 and 16 of that service bulletin specify a modification
of the hinge assembly having part number (P/N) 116A5522-1, which is
installed on airplanes having line numbers 1 through 2837.
    We disagree to change the airplanes in Group 2. The purpose of the
Group 2 division is to address a parting agent issue and not hinge
trimming. Although the hinge assembly part number does change at
airplane line number 2837, it is unrelated to the Group 2 division. No
change has been made to the AD in this regard.

Request for Parts Specifications

    American Airlines requested that we provide material specifications
and part dimensions to allow for manufacturing of alternatives for a
seal disk having P/N 116A8505-2. The commenter stated that the parts
are unavailable from Boeing and having an alternate part is necessary
to ensure a sufficient supply for operators.
    We cannot include proprietary information such as part dimensions
and materials in ADs; however, we are aware that seal disks having P/N
116A8505-2 are now available from the manufacturer. No change has been
made to the AD in this regard.

Request for Credit for Actions Done Previously

    Tracinda Flight Department requested that we revise the
supplemental NPRM (77 FR 15638, March 16, 2012) to provide credit for
doing the actions specified in Boeing Special Attention Service
Bulletin 737-57-1293, Revision 2, dated September 28, 2011.
    We agree to allow credit for actions done in accordance with Boeing
Special Attention Service Bulletin 737-57-1293, Revision 2, dated
September 28, 2011. We have added new paragraph (h) to this AD
accordingly.
    American Airlines requested that we revise the supplemental NPRM
(77 FR 15638, March 16, 2012) to allow credit for actions done using
Boeing Special Attention Service Bulletin 737-57-1293, Revision 1,
dated January 11, 2010. The commenter stated that the updates in Boeing
Special Attention Service Bulletin 737-57-1293, Revision 2, dated
September 28, 2011, do not address the safety issue with the exception
of the addition of the rubber seal disk.
    We disagree with the commenter's request. Boeing Special Attention
Service Bulletin 737-57-1293, Revision 2, dated September 28, 2011,
changed the inspection type for the bonding jumper countersink diameter
and clarified certain instructions specified in Boeing Special
Attention Service Bulletin 737-57-1293, Revision 1, dated January 11,
2010. However, operators may request approval of an alternative method
of compliance (AMOC), as specified in paragraph (i) of this AD. No
change has been made to the AD in this regard.

Conclusion

    We reviewed the relevant data, considered the comments received,
and determined that air safety and the public interest require adopting
the AD with the changes described previously and minor editorial
changes. We have determined that these minor changes:
     Are consistent with the intent that was proposed in the
SNPRM (77 FR 15638, March 16, 2012) for correcting the unsafe
condition; and
     Do not add any additional burden upon the public than was
already proposed in the SNPRM (77 FR 15638, March 16, 2012).
    We also determined that these changes will not increase the
economic burden on any operator or increase the scope of the AD.

Costs of Compliance

    We estimate that this AD affects 1,072 airplanes of U.S. registry.
    We estimate the following costs to comply with this AD:

                                                 Estimated Costs
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                                                                                Cost per      Cost on U.S.
                Action                         Labor cost           Parts cost        product        operators
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Modification, Group 1 (734 airplanes)  50 work-hours x $85 per            $1,262          $5,512      $4,045,808
                                        hour = $4,250.

Modification, Group 2 (58 airplanes).  27 work-hours x $85 per             1,262           3,557         206,306
                                        hour = $2,295.
Modification, Group 3 (280 airplanes)  3 work-hours x $85 per                 94             349          97,720
                                        hour = $255.
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Authority for This Rulemaking

    Title 49 of the United States Code specifies the FAA's authority to
issue rules on aviation safety. Subtitle I, section 106, describes the
authority of the FAA Administrator. Subtitle VII: Aviation Programs,
describes in more detail the scope of the Agency's authority.
    We are issuing this rulemaking under the authority described in
Subtitle VII, Part A, Subpart III, Section 44701: ``General
requirements.'' Under that section, Congress charges the FAA with
promoting safe flight of civil aircraft in air commerce by prescribing
regulations for practices, methods, and procedures the Administrator
finds necessary for safety in air commerce. This regulation is within
the scope of that authority because it addresses an unsafe condition
that is likely to exist or develop on products identified in this
rulemaking action.

Regulatory Findings

    This AD will not have federalism implications under Executive Order
13132. This AD will not have a substantial direct effect on the States,
on the relationship between the national government and the States, or
on the distribution of power and responsibilities among the various
levels of government.
    For the reasons discussed above, I certify that this AD:
    (1) Is not a ``significant regulatory action'' under Executive
Order 12866,
    (2) Is not a ``significant rule'' under DOT Regulatory Policies and
Procedures (44 FR 11034, February 26, 1979),
    (3) Will not affect intrastate aviation in Alaska, and
    (4) Will not have a significant economic impact, positive or
negative, on a substantial number of small entities under the criteria
of the Regulatory Flexibility Act.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by
reference, Safety.

Adoption of the Amendment

    Accordingly, under the authority delegated to me by the
Administrator, the FAA amends 14 CFR part 39 as follows:

PART 39--AIRWORTHINESS DIRECTIVES

0
1. The authority citation for part 39 continues to read as follows:

    Authority:  49 U.S.C. 106(g), 40113, 44701.

Sec.  39.13  [Amended]

0
2. The FAA amends Sec.  39.13 by adding the following new airworthiness
directive (AD):

2013-08-18 The Boeing Company: Amendment 39-17435; Docket No. FAA-
2009-0288; Directorate Identifier 2008-NM-214-AD.

(a) Effective Date

    This AD is effective June 5, 2013.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to The Boeing Company Model 737-600, -700, -
700C, -800, -900 and -900ER series airplanes, certificated in any
category, as identified in Boeing Special Attention Service Bulletin
737-57-1293, Revision 3, dated December 14, 2012.

(d) Subject

    Joint Aircraft System Component (JASC)/Air Transport Association
(ATA) of America Code 57, Wings.

(e) Unsafe Condition

    This AD was prompted by a report of leaking fuel from the wing
leading edge area at the inboard end of the number 5 leading edge
slat. We are issuing this AD to prevent flammable fluids from
accumulating in the wing leading edge, and draining inboard and onto
the engine exhaust nozzle, which could result in a fire.

(f) Compliance

    Comply with this AD within the compliance times specified,
unless already done.

(g) Modification

    Within 24 months after the effective date of this AD, modify the
fluid drain path in the wing leading edge area, forward of the wing
front spar, and do all applicable related investigative and
corrective actions, in accordance with the Accomplishment
Instructions of Boeing Special Attention Service Bulletin 737-57-
1293, Revision 3, dated December 14, 2012. Do all applicable related
investigative and corrective actions before further flight.

(h) Credit for Previous Actions

    This paragraph provides credit for the corresponding actions
required by paragraph (g) of this AD, if those actions were
performed before the effective date of this AD using Boeing Special
Attention Service Bulletin 737-57-1293, Revision 2, dated September
28, 2011, which is not incorporated by reference in this AD.

(i) Alternative Methods of Compliance (AMOCs)

    (1) The Manager, Seattle Aircraft Certification Office (ACO),
FAA, has the authority to approve AMOCs for this AD, if requested
using the procedures found in 14 CFR 39.19. In accordance with 14
CFR 39.19, send your request to your principal inspector or local
Flight Standards District Office, as appropriate. If sending
information directly to the manager of the ACO, send it to the
attention of the person identified in the Related Information
section of this AD. Information may be emailed to<EMAIL_ADDRESS>    (2) Before using any approved AMOC, notify your appropriate
principal inspector, or lacking a principal inspector, the manager
of the local flight standards district office/certificate holding
district office.

(j) Related Information

    For more information about this AD, contact Ansel James,
Aerospace Engineer, Propulsion Branch, ANM-140S, FAA, Seattle
Aircraft Certification Office, 1601 Lind Avenue SW., Renton,
Washington 98057-3356; phone:<PHONE_NUMBER>; fax:<PHONE_NUMBER>;
email<EMAIL_ADDRESS>
(k) Material Incorporated by Reference

    (1) The Director of the Federal Register approved the
incorporation by reference (IBR) of the service information listed
in this paragraph under 5 U.S.C. 552(a) and 1 CFR part 51.
    (2) You must use this service information as applicable to do
the actions required by this AD, unless the AD specifies otherwise.
    (i) Boeing Special Attention Service Bulletin 737-57-1293,
Revision 3, dated December 14, 2012.
    (ii) Reserved.
    (3) For service information identified in this AD, contact
Boeing Commercial Airplanes, Attention: Data & Services Management,
P.O. Box 3707, MC 2H-65, Seattle, Washington 98124-2207; telephone
206-544-5000, extension 1; fax<PHONE_NUMBER>; Internet https://www.myboeingfleet.com.
    (4) You may review copies of the referenced service information
at the FAA, Transport Airplane Directorate, 1601 Lind Avenue SW.,
Renton, Washington. For information on the availability of this
material at the FAA, call<PHONE_NUMBER>.
    (5) You may view this service information that is incorporated
by reference at the National Archives and Records

Administration (NARA). For information on the availability of this
material at NARA, call<PHONE_NUMBER>, or go to: http://www.archives.gov/federal-register/cfr/ibr-locations.html.

    Issued in Renton, Washington, on April 5, 2013.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 2013-09205 Filed 4-30-13; 8:45 am]
BILLING CODE 4910-13-P


Drinking Water Criteria Document for Cyanogen Chloride and Potential Metabolites EPA/ OW/ OST/ HECD IV 1 Final draft Chapter IV. Human Exposure Since cyanide is the primary metabolite of cyanogen chloride and the surrogate used for the dose response assessment ( see Appendix A), this section addresses both cyanogen chloride and cyanide exposure. Future work enhancing this assessment could include thiocyanate, since cyanide is metabolized to thiocyanate, and thiocyanate accounts for at least some of the toxic effects of cyanide exposure. Exposure to cyanate and cyanamide is not addressed. Exposure to these chemicals is of less concern for the cyanogen chloride assessment, since they represent a small portion of the cyanogen chloride dose, and they are not metabolized through the cyanide/ thiocyanate pathway.

A. Drinking Water Exposure Cyanogen chloride has been identified as a drinking water disinfection byproduct under the Information Collection Rule ( U. S. EPA, 1994a) and is being assessed for regulatory consideration in the Stage 2 Disinfectants/ Disinfection Byproducts Rule to be promulgated. HCN has been identified as a known metabolite of cyanogen chloride and is a known contaminant in drinking water. Therefore, this section will examine the occurrence of these compounds in drinking water.

Cyanogen chloride is formed in raw water during chlorination and increases when ammonium chloride is added prior to chlorination ( Ohya and Kanno, 1987) or if ammonia is Drinking Water Criteria Document for Cyanogen Chloride and Potential Metabolites EPA/ OW/ OST/ HECD IV 2 Final draft present in the source water ( WHO, 2000). Most cyanide in waters commonly occurs as HCN ( ATSDR, 1997).

A. 1 National Occurrence Data for Cyanogen Chloride This section presents the data collected from the Information Collection Rule ( ICR)

databases, which provide data from surface water and groundwater systems serving at least 100,000 persons. This data base includes information gathered for the 18 months from July 1997 to December 1998.

The ICR generated plant level sets of data that link water quality and treatment from source to tap, and that aid in understanding the seasonal and spatial variability in these relationships. The database contains information from 18 monthly or 6 quarterly samples from 7/ 97 to 12/ 98, from approximately 300 large systems covering approximately 500 plants.

However, because cyanogen chloride is formed when chlorine reacts with organic material in the presence of ammonia, only plants that used chloramine as a primary or secondary disinfectant were required to monitor for cyanogen chloride. Thirty five percent of the surface water plants and 23% of the groundwater plants reported cyanogen chloride observations. In addition,

analysis for cyanogen was required only for two sample locations: finished water ( at the end of the treatment plant, before water enters the distribution system) and distribution system ( DS)

maximum ( at a point in the distribution system that has the longest residence time, as designated Drinking Water Criteria Document for Cyanogen Chloride and Potential Metabolites EPA/ OW/ OST/ HECD IV 3 Final draft by the water system). For other chemicals monitored in the ICR, four distribution locations were sampled. The samples were tested for influent and finished water quality parameters ( e. g., TOC,

temperature, pH, alkalinity), disinfection byproduct ( DBP) levels, and disinfectant residuals. Over the 18 month period, 738 finished water samples were taken from 140 plants and 610 DS maximum samples were taken from 117 plants with surface water as their source. During this same period, 146 finished water samples were taken from 28 plants and 135 DS maximum samples were taken from 26 plants with groundwater as their source. For more detailed information, such as sampling frequencies, refer to the ICR Data Analysis Plan ( U. S. EPA,

2000a).

A. 1.1 Quarterly Finished Water and Distribution Maximum for Cyanogen Chloride The data in Table IV 1 were taken from the online version of the ICR database ( U. S.

EPA, 2000b), and the explanation of the methods used was taken from the Draft EPA Document on Stage 2 Occurrence and Exposure Assessment for Disinfectants and Disinfection Byproducts ( D/ DBPs) in Public Drinking Water ( U. S. EPA, 2000c). Data presented in the table have been taken from the ICR database as provided to avoid misrepresentation or misinterpretation.

Therefore, although all data in the table are presented with two decimal points ( as provided in the ICR database), this does not necessarily represent the actual precision of the data. Drinking Water Criteria Document for Cyanogen Chloride and Potential Metabolites EPA/ OW/ OST/ HECD IV 4 Final draft Table IV 1. Cyanogen Chloride Quarterly Distribution System Finish and Maximum Source Quarterly Dist. Sys. Plants N Pct ND % Mean µ g/ L Median µ g/ L STD µ g/ L Min µ g/ L Max µ g/ L p10 µ g/ L p90 µ g/ L SW Finished 140 738 16.26 3.25 2.30 3.34 0.00 20.60 0.00 7.40 DS Max 117 610 22.46 3.02 2.10 3.23 0.00 18.30 0.00 8.00 GW Finished 28 146 31.51 2.12 1.10 2.78 0.00 14.50 0.00 6.30 DS Max 26 135 38.52 1.63 0.80 2.40 0.00 16.30 0.00 4.70 Source: SW  Surface Water, GW  Groundwater Quarterly Dist. Sys.: Finished Water: Sample point at the end of the treatment plant, before water enters the distribution system DS Max ( Distribution System Maximum): Sample point in the distribution system that has the longest residence time, as designated by the water system. Plants: Number of plants sampled N: Number of samples Pct ND: Percent samples nondetect ( detection limits not provided) Mean: Arithmetic mean of all samples Median: Median value of all samples STD: Standard deviation Min: Minimum Value Max: Maximum Value p10: 10th percentile p90: 90th percentile Examination of the data using the Student's t test indicates that the mean concentrations of cyanogen chloride in the finished water were not significantly different ( at p = 0.05) from the mean cyanogen chloride concentrations at the distribution maximum in either the surface water or groundwater plants. However, the finished and DS maximum mean cyanogen chloride concentrations in surface water were significantly higher ( at p = 0.05) than their respective concentrations in groundwater. The lowest mean concentrations are associated with the highest Drinking Water Criteria Document for Cyanogen Chloride and Potential Metabolites EPA/ OW/ OST/ HECD IV 5 Final draft percentage of nondetects, which were treated as 0 in the calculation of the mean, median,

standard deviation, and p10 values ( U. S. EPA, 2000b). The median concentrations in groundwater and surface water for cyanogen chloride were lower than the means. The median concentrations of cyanogen chloride in finished and DS maximum samples in surface water were 2.3 and 2.1

g/ L, respectively. The median concentrations of cyanogen chloride in finished and DS maximum samples in groundwater were 1.1 and 0.8

g/ L, respectively. The mean concentrations of cyanogen chloride in finished and DS maximum samples in surface water were 3.25 and 3.02

g/ L, respectively. The mean concentrations of cyanogen chloride in finished and DS maximum samples in groundwater were 2.12 and 1.63

g/ L, respectively.

A. 2 National Occurrence Data for Cyanide This section summarizes information gathered from the ATSDR ( 1997) Toxicological Profile for Cyanide.

Cyanide occurs most commonly in water as HCN. Based on data obtained from the EPA STORET database from the late 1970s to the early 1980s, the mean cyanide concentration in most surface waters was no greater than 3.5

g/ L ( Fiksel et al., 1981). However, 37 of 50 states had locations where cyanide concentrations exceeded this level. Surface water in areas of southern California, North Dakota, Iowa, northwest Georgia, western New York, and western Pennsylvania exceeded 200

g/ L cyanide ( Fiksel et al., 1981). Cyanide was detected in water Drinking Water Criteria Document for Cyanogen Chloride and Potential Metabolites EPA/ OW/ OST/ HECD IV 6 Final draft from the Great Lakes at concentrations greater than 1

g/ L ( Great Lakes Water Quality Board,

1983). Concentrations of cyanide in 104 samples collected during 1980 and 1981 at various points on the Ohio River and its tributaries ranged from < 5 to 80

g/ L ( Ohio River Valley Sanitation Commission, 1982). Based on data from the Nationwide Urban Runoff Program as of 1982, cyanide was detected in 16% of the samples in 4 of 15 urban areas evaluated, with concentrations ranging from 2 to 33

g/ L. Localesevaluated included Denver, Colorado; Long Island, New York; Austin, Texas; and Bellevue, Washington ( Cole et al., 1984).

Cyanide has been detected in groundwater below landfills and disposal sites ( Anonymous,

1990; Myers, 1983). A maximum concentration of 1200

g/ L cyanide was found in shallow groundwater less than 3 meters below an inactive drum recycling facility in Miami, Florida ( Myers et al., 1983).

A. 2.1 National Drinking Water Contaminant Occurrence Database Data on Cyanide The National Drinking Water Contaminant Occurrence Database ( NCOD) was developed to satisfy the statutory requirements set by Congress in the 1996 Safe Drinking Water Act ( SDWA) amendments and supports the U. S. EPA's decisions related to identifying contaminants for regulation and subsequent regulation development ( U. S. EPA, 2001c). The NCOD contains only Public Water System ( PWS) data reported to the Safe Drinking Water Information Service and may be from several sampling points within a water system. The data were collected from Drinking Water Criteria Document for Cyanogen Chloride and Potential Metabolites EPA/ OW/ OST/ HECD IV 7 Final draft thousands of existing drinking water sources, both small and large, for surface water,

groundwater under the direct influence ( UDI) of surface water, and groundwater. The data contained in the NCOD are updated periodically from existing sources and change over time. The data presented herein are from the most recent quarter year updated on April 28, 2000 ( Table IV

2) ( U. S. EPA, 2001c). Since the NCOD is updated quarterly, data from previous quarters were not available, and a yearly average could not be calculated. However, these data are expected to represent the most recent average concentrations of cyanide across the United States. The EPA STORET data, presented in the ATSDR ( 1997) Toxicological Profile for Cyanide, is over 11 years old and presents data for a limited number of locations. Therefore, it is believed that the NCOD data is the most representative of current cyanide concentrations in drinking water across the U. S. Drinking Water Criteria Document for Cyanogen Chloride and Potential Metabolites EPA/ OW/ OST/ HECD IV 8 Final draft Table IV 2. National Drinking Water Contaminant Occurrence Database Public Water Supply  National Drinking Water Data for Cyanide PWS Category PWS Size ( population) Total Analyses # Analyses w/ Detects # PWS w/ Analyses # PWS w/ Detects Min ug/ L Max ug/ L Average ug/ L Standard Deviation ug/ L Surface Water Very Small 0  500 105 3 46 3 2 4300 1435 2481 Small 501  3,300 253 3 97 3 1 7 3.7 3.1 Medium 3,301  10,000 216 5 58 4 2 9000 1807 4020 Large 10,001  100,000 521 15 92 8 2 10,000 5340 5156 Very Large 100,000 + 187 7 16 4 20 120 57.9 38.7 All Systems 1282 33 309 22 1 10,000 2844 4446 Groundwater UDI Surface Water Very Small 0  500   *

Small 501  3,300

Medium 3,301  10,000 3 0 1 0

Large 10,001  100,000

Very Large 100,000 +

All Systems 3 0 1 0

Groundwater Very Small 0  500 1353 23 818 18 3 32,700 4498 8539 Small 501  3,300 931 18 424 14 3 10,000 2254 4261 Medium 3,301  10,000 699 10 189 6 6 380 63.6 114 Large 10,001  100,000 1030 29 128 15 2 10,000 1065 3089 Very Large 100,000 + 96 0 2 0

All Systems 4109 80 1561 53 2 32,700 2194 5494 * All cells with "" indicate values were not reported in the NCOD database. Drinking Water Criteria Document for Cyanogen Chloride and Potential Metabolites EPA/ OW/ OST/ HECD IV 9 Final draft Average cyanide concentrations in surface water and groundwater were calculated only for those samples where cyanide was detected. Non detects were not included in the calculation of average concentrations. Examination of the data using the Student's t test indicates that there were no statistically significant differences ( at p = 0.05) between the average cyanide concentrations in surface water and groundwater. The overall average concentration in treated surface water ( averaged across all size systems that detected cyanide) was 2844

g/ L and ranged from 3.7

g/ L to 5340

g/ L in different size systems ( Table IV 2). The minimum concentration was non detect and the maximum was 10,000

g/ L. Of a total of 1282 samples in 309 plants,

cyanide was detected in approximately 3% ( 33/ 1282) of the samples in 7% ( 22/ 309) of the plants treating surface water ( Table IV 2). In groundwater the overall average concentration of cyanide ( averaged across all size systems that detected cyanide) was 2194

g/ L and ranged from nondetect to 4498

g/ L in different size systems ( Table IV 2). The minimum concentration was nondetect and the maximum was 32,700

g/ L. Of a total of 4109 samples in 1561 plants, cyanide was detected in approximately 2% ( 80/ 4109) of the samples in approximately 3% ( 53/ 1561) of the plants treating groundwater ( Table IV 2). There is considerable uncertainty in the reported average concentrations, since there were several orders of magnitude separating the minimum and maximum detected levels, and only a few analyses with detects. This means that the calculated averages for these populations may be highly influenced by one or two systems with high cyanide levels, and that the calculated averages do not accurately reflect the cyanide concentrations to which these populations are exposed. Medians were not available from the NCOD survey. Drinking Water Criteria Document for Cyanogen Chloride and Potential Metabolites EPA/ OW/ OST/ HECD IV 10 Final draft In a total of three samples in one plant, cyanide was not detected in groundwater under the direct influence of surface water.

A. 3 Factors Affecting the Relative Concentrations of Cyanogen Chloride and Hydrogen Cyanide in Drinking Water Cyanogen chloride. Cyanogen chloride is formed in raw water during chlorination.

Ohya and Kanno ( 1987) found that the formation of cyanogen chloride increased when ammonium chloride is added prior to chlorination. This was presumed to be due to the reaction of humic substance with chloramine. According to the WHO Environmental Health Criteria Monograph on Disinfectants and Disinfectant Byproducts ( WHO, 2000), the presence of ammonia in source waters during disinfection can cause chlorine and ozone demand and participate in the formation of cyanogen chloride and other nitrogenous compounds. Although data on the occurrence of ammonia in source water would greatly aid the understanding of the potential for exposure to cyanogen chloride when disinfectants other than chloramine are used,

this information was not available in the ICR nor the NCOD database.

Only those plants that used chloramine as a primary or secondary disinfectant were required to monitor for cyanogen chloride for inclusion in the ICR database. Because ammonia in the source waters may also result in the formation of cyanogen chloride during disinfection with Drinking Water Criteria Document for Cyanogen Chloride and Potential Metabolites EPA/ OW/ OST/ HECD IV 11 Final draft other disinfectants, the number of plants where cyanogen chloride may be present may be underrepresented in the ICR database.

Richardson ( 1998) compared the relative concentrations of DBPs in drinking water using different treatment methods and found that cyanogen chloride is a byproduct of both chlorination and chloramination. However, in contrast to Ohya and Kanno ( 1987), Richardson ( 1998) believes that the formation of the halonitriles, including cyanogen chloride, may be caused by the low level of residual chlorine in the chloramination process and not by chloramine itself. Cyanogen chloride was not produced by chlorine dioxide or ozone in measurable quantities. The levels of DBPs, including cyanogen chloride, were lower when ozone was followed by chlorine.

Interestingly, although cyanogen chloride concentrations in water treated with ozone followed by chloramine were half the concentrations observed with chlorination alone, they were twice the level found in water treated with chloramine as the sole disinfectant.

Krasner et al. ( 1989) found that cyanogen chloride concentrations in water pretreated with chlorination and post treated with ammonia were significantly higher than in water treated with chlorine alone.

Young ( 1994) found that numerous organic byproducts are produced, including cyanogen chloride, when aqueous chlorine reacts with the amino acids, purines and pyrimidines. Drinking Water Criteria Document for Cyanogen Chloride and Potential Metabolites EPA/ OW/ OST/ HECD IV 12 Final draft Hydrogen Cyanide. This section is adapted from information gathered from the ATSDR ( 1997) Toxicological Profile for Cyanide.

The major releases of cyanide to water are a result of discharges from metal finishing industries, iron and steel mills, and organic chemical industries ( Fiksel, et al., 1981).

Although HCN and soluble metal cyanides may be removed from water by aerobic or anaerobic biodegradation, the primary mechanism is expected to be volatilization ( Callahan et al., 1979).

B. Exposure to Sources Other Than Drinking Water Cyanogen chloride. The National Occupational Exposure Survey ( NOES) conducted by the National Institute for Occupational Safety and Health ( NIOSH) from 1980 to 1983 estimated that 1393 workers are exposed to cyanogen chloride ( NIOSH, 1990). Cyanogen chloride is used as a warning agent in fumigant gases and is also used for organic synthesis.

Hydrogen cyanide. This section summarizes information gathered from the ATSDR ( 1997) Toxicological Profile for Cyanide.

Although cyanide occurs naturally in the fruits, seeds, roots, and leaves of numerous plants, and is released to the environment from natural fires and natural biogenic processes from higher plants, bacteria, and fungi ( Cicerone and Zellner, 1983; Crutzen and Carmichael 1993; Drinking Water Criteria Document for Cyanogen Chloride and Potential Metabolites EPA/ OW/ OST/ HECD IV 13 Final draft Fiksel et al., 1981; Knowles, 1988), anthropogenic sources are responsible for much of the HCN in the environment.

The primary sources of cyanide releases to soil appear to be the disposal of cyanide wastes in landfills and the use of cyanide containing road salts ( Fiksel et al., 1981). However, no information could be found on the concentration of HCN in soil or sediments. Because of its highly volatile nature, HCN is not expected to be present at the surface of soils in any appreciable amount. In subsurface soil, low concentrations of cyanide would probably biodegrade under both aerobic and anaerobic conditions.

A number of drugs and industrial chemicals have been associated with human exposure to cyanide and have caused serious poisoning and, in some cases, death. Drugs that release cyanide upon metabolism include Laetrile ( amygdalin), formerly used in clinical trials for the treatment of cancer ( Khandekar and Edelman, 1979) and a drug used to reduce high blood pressure ( Aitken et al., 1977; Vesey et al., 1976). Industrial chemicals such as acetonitrile, propionitrile, acrylonitrile,

n butyronitrile, maleonitrile, and succinonitrile ( Willhite and Smith, 1981) are also metabolized to cyanide.

Occupational exposure to HCN occurs primarily through inhalation and, less frequently,

through dermal exposure. The National Occupational Exposure Survey ( NOES) conducted by the NIOSH from 1980 to 1983 estimated that over 250,000 workers are exposed to cyanide Drinking Water Criteria Document for Cyanogen Chloride and Potential Metabolites EPA/ OW/ OST/ HECD IV 14 Final draft compounds with 4005 workers exposed to HCN ( NIOSH, 1990). These estimates did not include workers potentially exposed to trade name compounds that contain cyanide. Occupations where workers may be exposed to HCN include electroplating, metallurgy, cyanotype printing,

pesticide application, firefighting, steel manufacturing, gas works operations, and metal cleaning;

and workers involved in the manufacture of cyanides and other simple aliphatic nitriles, methyl methacrylate, cyanuric acid, dyes, pharmaceutical, or chelating agents; and people who work in tanneries, metal cleaning, photoengraving or photography, and as blacksmiths ( Fiksel et al., 1981;

Lucas, 1992, Willhite and Smith, 1981). Workers in the oil shale retorting industries may also be exposed to HCN present in the offgas from the retorting process. Emergency personnel, police and firefighters, and medical personnel may be exposed to HCN when exposed to house or other building fires ( Andrews, et al., 1989), or during resuscitation efforts or the removal of the gastric contents of postmortem victims of cyanide poisoning ( Andrews, et al., 1989).

In a survey of various plating facilities, NIOSH found HCN in the workplace air at concentrations ranging from 0.001 to 4.3 mg/ m3 ( NIOSH, 1982; NIOSH, 1976). In a recent NIOSH survey of a university art department foundry, 4.3 mg/ m3 HCN was detected in the smoke produced during the pouring of castings. Although the ATSDR document provided no information on the amount of time and frequency that these workers were exposed to these concentrations of HCN, these levels were below the NIOSH recommended 15 minute short term exposure limit ( STEL) of 5 mg/ m3 for HCN ( reported in the ASTDR document as the NIOSH ceiling limit). Drinking Water Criteria Document for Cyanogen Chloride and Potential Metabolites EPA/ OW/ OST/ HECD IV 15 Final draft B. 1 Dietary Intake Cyanogen chloride. There are no quantitative data on the occurrence of cyanogen chloride in food. Cyanogen chloride was not included among the analytes measured in the current Total Diet Study ( TDS), sometimes called the Market Basket Study, an ongoing FDA program that determines levels of various pesticide residues, contaminants, and nutrients in foods ( U. S.

FDA, 2002).

However, Wu et al. ( 1998) investigated DBP formation in the preparation of instant tea with water containing chlorine residual. Tea polyphenols or tea tannins are somewhat similar to humic substances in both color and structure and have the potential to react with the chlorine residual present in tap water to form DBPs. Aquatic humic substances were compared to the instant tea samples in terms of DBP formation under selected laboratory conditions. Wu et al.

( 1998) incubated instant tea with water treated with sufficient chlorine to result in a minimal chlorine residual concentration of at least 0.6 mg/ L at the end of the 24 hour reaction period.

They found that all of the DBPs evaluated were present except for the cyanogen halides, including cyanogen chloride, which are unstable in the presence of free chlorine ( Xie and Reckhow, 1992).

In contrast, when Wu et al. ( 1998) incubated instant tea with sufficient chloramine to result in a minimal residual chloramine concentration of 2.4 mg/ L at the end of the 24 hour reaction period,

cyanogen chloride was detected, yet at lower concentrations than in the aquatic humic samples. Drinking Water Criteria Document for Cyanogen Chloride and Potential Metabolites EPA/ OW/ OST/ HECD IV 16 Final draft Hydrogen cyanide. This section summarizes information gathered from the ATSDR ( 1997) Toxicological Profile for Cyanide.

There are little quantitative data on the occurrence of hydrogen cyanide in food. Cyanide was not included among the analytes measured in the current Total Diet Study ( TDS), sometimes called the Market Basket Study, an ongoing FDA program that determines levels of various pesticide residues, contaminants, and nutrients in foods ( U. S. FDA, 2002).

Although some plants contain HCN, and HCN can be present in food as residues from HCN fumigation ( Fiksel et al., 1981), the primary HCN source in food is cyanogenic glycosides.

HCN is released during maceration in which intracellular   glucosidase is activated, or in the stomach by acid hydrolysis ( U. S. EPA, 1980; Fiksel et al., 1981; Seigler, 1991), or in the gut by the action of   glucosidase produced by microflora ( WHO, 1992). The potential toxicity of cyanogenic plants depends on their bioavailability ( Seigler, 1991) and their ability to release HCN during preparation or digestion ( WHO, 1992). Cyanogenic glycosides absorbed intact from the gut are not metabolized by mammalian enzymes ( Seigler, 1991).

The cyanogenic content of a food is usually expressed as the amount of HCN released by acid hydrolysis; glycoside concentrations are rarely reported ( WHO, 1992). Over 2650 plant species produce HCN. These include almonds; pits from stone fruits such as apricots, peaches,

plums, cherries; sorghum; soybeans; lima beans; sweet potatoes; maize; millet; sugarcane; bamboo Drinking Water Criteria Document for Cyanogen Chloride and Potential Metabolites EPA/ OW/ OST/ HECD IV 17 Final draft shoots; and cassava ( Fiksel et al., 1981) which is a major starchy food for more than 300 million people in many tropical countries of the world ( Seigler, 1991).

HCN has been detected in cereal grains and their products at concentrations ranging from 0.001 to 0.45

g/ g, in soy protein products at concentrations ranging from 0.07 to 0.3

g/ g, and in lima beans at concentrations ranging from 0.1 to 3 mg/ g ( Honig et al., 1983; Towill et al.,

1978). The HCN content of U. S. lima beans generally ranges from 0.1 and 0.17 mg/ g ( Towill et al., 1978). The HCN equivalent of total cyanogenic content ( i. e., cyanogenic glycosides,

cyanohydrins, and HCN) of cassava root ranges from 91 to 1,515 mg/ kg HCN dry weight ( O'Brien et al., 1992).

Depending on the type of cultivar, season, and geographical area, the HCN concentration in apricot pits may vary from 8.9 to 217

g/ g on a weight per weight basis ( w/ w) ( Lasch and El Shawa, 1981). Swain et al. ( 1992) reported a mean HCN concentration in black cherry ( Prunus serotina Ehrh.) fruits at a concentration greater than 3

mole/ seed at maturity. This is equivalent to a mean HCN content of 78

g/ seed; insufficient information was available to allow conversion of these results to weight per weight units. In a laboratory study, Voldrich and Kyzlink ( 1992)

found that, depending on the glycoside content of the raw fruits and the conditions of heat processing, HCN concentrations in canned unpitted fruits ( peaches, apricots, plums, and cherries)

ranged from 0 to 4 mg/ kg ( w/ w). As reported in the ATSDR ( 1997), these authors concluded that a 70 kg adult could consume approximately 1 kg of canned fruit a day at the highest Drinking Water Criteria Document for Cyanogen Chloride and Potential Metabolites EPA/ OW/ OST/ HECD IV 18 Final draft concentration of 4 mg/ kg HCN without exceeding the allowable daily intake ( ADI) of 0.05 mg/ kg day. However, consumption of 1 kg of canned fruit at 4 mg/ kg HCN would result in a dose of 0.06 mg/ kg day ([ 4mg/ kg * 1 kg]/ 70 kg body weight), which would slightly exceed the ADI of 0.05 mg/ kg day. Therefore, in order not to exceed the ADI of 0.05 mg/ kg day, it is estimated that a 70 kg adult could consume 1 kg of canned fruit a day at a concentration of 3.5 mg/ kg HCN ([ 3.5 mg/ kg * 1kg]/ 70 kg body weight), or consume 880 g of canned fruit a day at a maximum concentration of 4 mg/ kg HCN ([ 4 mg/ kg * 0.88 kg]/ 70 kg body weight). The authors further correctly concluded that a safe portion for a 15 kg child would be only about 180 grams of canned fruit at a maximum concentration of 4 mg/ kg HCN. This is equivalent to the ADI of 0.05 mg/ kg day.

In an analysis of 233 samples of commercially available and homemade stone fruit juices,

Stadelmann ( 1976) reported that pitted fruit juices had lower HCN concentrations than unpitted or partially pitted fruit juices, indicating that the pits are the primary source of cyanides in these juices. The HCN content of a home made mixed cherry juice from pitted fruits was 5.3 mg/ L compared to 23.5 mg/ L HCN in a cherry juice containing 100% crushed pits. Stadelmann ( 1976)

also reported median HCN concentrations of 4.6 mg/ L in commercial cherry juice, 2.2 mg/ L in commercial prune juice, and 1.9 mg/ L in commercial peach juice. Stadelmann ( 1976)

recommended that the maximum HCN content allowed in fruit juice should be set at a level of 5 mg/ L. Drinking Water Criteria Document for Cyanogen Chloride and Potential Metabolites EPA/ OW/ OST/ HECD IV 19 Final draft B. 2 Air Intake Cyanogen chloride. There is no information in the available literature on the concentration of cyanogen chloride in the air.

Hydrogen cyanide. This section summarizes information gathered from the ATSDR ( 1997) Toxicological Profile for Cyanide.

Cyanide is released to the air primarily as HCN gas and, to a lesser extent, as particulate cyanides. The major sources of HCN release are vehicle exhaust ( Fiksel, et al, 1981) and biomass burning ( Crutzen and Carmichael, 1993; Lobert and Warnatz, 1993). HCN has an estimated 2.5

year residence time in the atmosphere and can be transported over long distances before reacting with photochemically generated hydroxyl radicals. Neither photolysis nor deposition by rainwater are expected to be significant removal mechanisms.

Ambient air concentrations of HCN in the northern hemisphere's non urban troposphere range from 160 to 166 ppt ( 177 ng/ m3 to 184 ng/ m3). Although ambient air monitoring data of HCN near source areas ( e. g., HCN manufacturing industries, coke production industries,

wastedisposal sites) could not be located in the available literature, HCN concentrations in these areas were expected to be higher than the non urban tropospheric concentrations. Drinking Water Criteria Document for Cyanogen Chloride and Potential Metabolites EPA/ OW/ OST/ HECD IV 20 Final draft People who smoke and nonsmokers exposed to secondary tobacco smoke may also be exposed to HCN at concentrations greater than background levels ( Fiksel, et al, 1981). HCN levels in mainstream ( inhaled) smoke from U. S. commercial cigarettes have been reported to range from 10 to 400

g per cigarette. The ratio of HCN concentration in sidestream smoke to mainstream smoke ranges from 0.006 to 0.27 ( Fiksel, et al, 1981). Therefore, nonsmokers exposed to secondary tobacco smoke could be exposed to 0.06 ( 10

g/ cigarette × 0.006) to 108

g HCN/ cigarette ( 400

g/ cigarette × 0.27).

B. 3 Dermal Exposure Cyanogen chloride. There is no information in the available literature on dermal exposure to cyanogen chloride.

Hydrogen cyanide. According to information presented in the ATSDR ( 1997)

Toxicological Profile for Cyanide, dermal absorption of HCN is not a significant route of exposure for the general population.

C. Overall Exposure Cyanogen chloride. The relative source contribution ( RSC) for cyanogen chloride is derived by application of the Exposure Decision Tree approach published in EPA's Methodology Drinking Water Criteria Document for Cyanogen Chloride and Potential Metabolites EPA/ OW/ OST/ HECD IV 21 Final draft for Deriving Ambient Water Quality Criteria for the Protection of Human Health ( U. S. EPA,

2000d). The RSC is the fraction of an individual's total exposure allocated to drinking water. An RSC of 20% accounts for the likelihood of exposure to cyanogen chloride or cyanide from sources other than tap water, such as ambient air and food, in the absence of adequate data. This value also takes into account the potential for exposure to cyanide ( a key cyanogen chloride metabolite) via food, air, and smoking, as described in the next paragraphs. The data are not adequate to quantify the contributions of each source for an overall assessment of exposure.

There are very limited quantitative data on the presence of cyanogen chloride in the environment and on cyanogen chloride exposure. There is no information in the available literature on the concentration of cyanogen chloride in the air and no information in the available literature on dermal exposure to cyanogen chloride. No quantification of cyanogen chloride body burden was located, but the rapid metabolism of cyanogen chloride ( see Chapter 3) indicates that any body burden would be negligible. There is no quantitative data on dietary levels. Although one investigator found that cyanogen chloride may be produced from the reaction of instant tea with water containing chloramine residual, no quantification of cyanogen chloride concentration was provided. Cyanogen chloride was not included among the analytes measured in the current FDA Market Basket Study ( U. S. FDA, 2002).

The mean concentrations of cyanogen chloride in finished and DS maximum samples in surface water were 3.25 and 3.02

g/ L, respectively. The mean concentrations of cyanogen Drinking Water Criteria Document for Cyanogen Chloride and Potential Metabolites EPA/ OW/ OST/ HECD IV 22 Final draft chloride in finished and DS maximum samples in groundwater were 2.12 and 1.63

g/ L,

respectively. There were no statistically significant differences between the concentration of cyanogen chloride in finished water and the DS maximum samples in either surface water or groundwater. However, the finished and DS maximum mean cyanogen chloride concentrations in surface water were significantly higher ( at p = 0.05) than their respective concentrations in groundwater. Because cyanogen chloride is formed when chlorine reacts with organic material in the presence of ammonia, only plants that used chloramine as a primary or secondary disinfectant were required to monitor for cyanogen chloride. Thirty five percent of the surface water plants and 23 percent of the groundwater plants reported cyanogen chloride observations ( U. S. EPA,

2000c).

Although NIOSH ( 1990) estimated that 1393 workers were exposed to cyanogen chloride, no information on exposure levels was available.

Hydrogen cyanide. The relative source contribution ( RSC) for cyanide is derived by application of the Exposure Decision Tree approach published in EPA's Methodology for Deriving Ambient Water Quality Criteria for the Protection of Human Health ( U. S. EPA,

2000d). The RSC is the fraction of an individual's total exposure allocated to drinking water. An RSC of 20% accounts for the likelihood of exposure to cyanide from sources other than tap water, such as ambient air and food, in the absence of adequate data. The available data are sufficient to demonstrate that food, air, and smoking are relevant sources of exposure to cyanide Drinking Water Criteria Document for Cyanogen Chloride and Potential Metabolites EPA/ OW/ OST/ HECD IV 23 Final draft in addition to drinking water. However, the data are not adequate enough to quantify the contributions of each source for an overall assessment of exposure.

There are limited quantitative data on the presence of cyanide in the environment and cyanide exposure.

Cyanide concentrations averaged 2844

g/ L in 3% of the samples in 7% of the plants treating surface water. In 2% of the samples in 3% of the plants treating groundwater, cyanide concentrations averaged 2194

g/ L. There was no statistically significant difference between the overall cyanide concentrations in surface water and groundwater. As discussed above, this average is not very representative of overall population exposure, in light of the small number of water systems with detectable cyanide levels, and the wide variability in the systems with detectable levels.

There was no information presented in the ATSDR ( 1997) Toxicological Profile for Cyanide on the concentration of HCN in soil or sediments. However, because of its highly volatile nature and its expected tendency to biodegrade and leach out of the soil, HCN is not expected to be present in soil in any appreciable amount.

Based on information presented in the ATSDR ( 1997) Toxicological Profile for Cyanide,

a number of drugs ( e. g., Laetrile and a drug used to reduce high blood pressure), as well as a Drinking Water Criteria Document for Cyanogen Chloride and Potential Metabolites EPA/ OW/ OST/ HECD IV 24 Final draft number of industrial chemicals ( acetonitrile, propionitrile, acrylonitrile, n butyronitrile,

maleonitrile, and succinonitrile), release cyanide upon metabolism. However, exposure to these substances would be limited to a subset of the population.

According to information presented in the ATSDR ( 1997) Toxicological Profile for Cyanide, the National Occupational Exposure Survey ( NOES) conducted by NIOSH from 1980 to 1983 estimated that 4005 workers were exposed to HCN. NIOSH found HCN in the workplace air at concentrations ranging from 0.001 to 4.3 mg/ m3. Although the ATSDR document provided no information on the amount of time and frequency that workers were exposed to these concentrations of HCN, the reported levels were below the NIOSH recommended 15 minute short term exposure limit ( STEL) of 5 mg/ m3 for HCN.

Although the ATSDR ( 1997) Toxicological Profile for Cyanide reported that over 2650 plant species produce cyanogenic compounds, cyanide was not included among the analytes measured in the current FDA Market Basket Study ( U. S. FDA, 2002). In addition, the potential toxicity of cyanogenic plants depends on the bioavailability of cyanide in food prepared from the plants, and on the potential for release of cyanide during preparation or digestion. Although estimates of the HCN concentration in the total diet of a U. S. adult were not located in the available literature, and human exposure to HCN from foods in which it occurs naturally in the United States is expected to be low, the exposure to HCN in food was expected to exceed HCN Drinking Water Criteria Document for Cyanogen Chloride and Potential Metabolites EPA/ OW/ OST/ HECD IV 25 Final draft intake from inhalation of air and ingestion of drinking water ( Fiksel et al., 1981). The ATSDR ( 1997) Toxicological Profile for Cyanide provided no quantitative data.

Ambient air concentrations of HCN in the northern hemisphere's non urban troposphere range from 160 to 166 ppt ( 177 ng/ m3 to 184 ng/ m3) ( ATSDR, 1997). Based on an atmospheric concentration of 170 ppt ( 188 ng/ m3) and a daily average inhalation rate of 20 m3, the ATSDR ( 1997) Toxicological Profile for Cyanide estimated an inhalation exposure to the general U. S.

non urban, nonsmoking population of 3.8

g cyanide/ day.

Smokers could be exposed to 10 to 400

g HCN per cigarette. Nonsmokers exposed to secondary tobacco smoke could be exposed to 0.06 to 108

g HCN/ cigarette.

According to information presented in the ATSDR ( 1997) Toxicological Profile for Cyanide, dermal absorption is not a significant route of exposure for the general population.

Thiocyanate, cyanate, and cyanamide. Exposure to these chemicals was not assessed for this document. In the absence of data, the default of 20% is used for the RSC for these chemicals.

D. Summary Drinking Water Criteria Document for Cyanogen Chloride and Potential Metabolites EPA/ OW/ OST/ HECD IV 26 Final draft Cyanogen chloride. The ICR database ( U. S. EPA, 2000b) contains some information on concentrations of cyanogen chloride in drinking water systems, and on how those concentrations vary with input water characteristics and treatment methods. The database contains information from 6 quarterly samples from 7/ 97 to 12/ 98, from approximately 300 large systems covering approximately 500 plants. The mean concentrations of cyanogen chloride at the distribution system maximum for drinking water derived from surface water and groundwater were 3.02 and 1.63

g/ L, respectively. The mean concentration of cyanogen chloride in finished water and the mean distribution system maximum were significantly higher in treated surface water ( at p = 0.05)

than their respective concentrations in treated groundwater. Because cyanogen chloride is formed when chlorine reacts with organic material in the presence of ammonia, only plants that used chloramine as a primary or secondary disinfectant were required to monitor for cyanogen chloride. Therefore, 35% of the surface water plants and 23% of the groundwater plants reported cyanogen chloride observations ( U. S. EPA, 2000c).

The National Occupational Exposure Survey ( NOES) conducted by NIOSH from 1980 to 1983 estimated that 1393 workers were exposed to cyanogen chloride.

There is no information in the available literature on the concentration of cyanogen chloride in the air and no information in the available literature on dermal exposure to cyanogen chloride. Cyanogen chloride body burden is expected to be negligible, in light of its rapid metabolism. There is no quantitative data on dietary levels. Although one investigator found that Drinking Water Criteria Document for Cyanogen Chloride and Potential Metabolites EPA/ OW/ OST/ HECD IV 27 Final draft cyanogen chloride may be produced from the reaction of instant tea with water containing chloramine residual, no quantification of cyanogen chloride concentration was provided.

Cyanogen chloride was not included among the analytes measured in the current FDA Market Basket Study ( U. S. FDA, 2002).

Due to the lack of data, no estimate can be made on average daily exposure to cyanogen chloride. An RSC of 20% is used for cyanogen chloride to account for the likelihood of exposure to cyanogen chloride or cyanide from sources other than tap water, such as ambient air and food,

in the absence of adequate data.

Hydrogen cyanide. The latest information on concentrations of cyanide in public water supplies drinking water comes from the latest quarterly reporting ( updated April 28, 2000) of the NCOD, which contains information from thousands of drinking water systems. Cyanide was detected in 7% of the plants ( 3% of the samples) using surface water as a source, and in 3% of the plants ( 2% of the samples) using groundwater as a source. Although the average cyanide concentrations in treated surface water were reported as 2844

g/ L, and the average concentrations in treated groundwater were reported as 2194

g/ L, there was no statistically significant difference between the two cyanide concentrations. Average cyanide concentrations in surface water and groundwater were calculated only for those samples where cyanide was detected. Non detects were not included in the calculation of average concentrations. Therefore,

the calculated averages may not accurately reflect the cyanide concentrations to which Drinking Water Criteria Document for Cyanogen Chloride and Potential Metabolites EPA/ OW/ OST/ HECD IV 28 Final draft populations served by these water systems are exposed. Medians were not available from the NCOD survey.

There was no information presented in the ATSDR ( 1997) Toxicological Profile for Cyanide on the concentration of HCN in soil or sediments. However, because of its highly volatile nature and its expected tendency to biodegrade and leach out of the soil, HCN is not expected to be present in soil in any appreciable amount.

Based on information presented in the ATSDR ( 1997) Toxicological Profile for Cyanide,

between 1981 and 1983, 4005 workers were potentially exposed to HCN. In addition to HCN concentrations in drinking water, there are some limited data on HCN concentrations in air and food.

Based on an atmospheric concentration of 170 ppt ( 188 ng/ m3) and a daily average inhalation rate of 20 m3, the ATSDR ( 1997) Toxicological Profile for Cyanide estimated an inhalation exposure to the general U. S. non urban, nonsmoking population of 3.8

g cyanide/ day.

Although concentrations of HCN in foods are expected to be low, one author estimated that intake from food would exceed HCN intake from inhalation of air and ingestion of drinking water ( Fiksel et al, 1981). However, estimates of the HCN concentration in the total diet were not located in the available literature. Cyanide was not included among the analytes measured in the current FDA Market Basket Study ( U. S. FDA, 2002). Therefore, no independent estimate of Drinking Water Criteria Document for Cyanogen Chloride and Potential Metabolites EPA/ OW/ OST/ HECD IV 29 Final draft daily HCN intake from food could be made. An RSC of 20% accounts for the likelihood of exposure to cyanide from sources other than tap water, such as ambient air and food, in the absence of adequate data.

HCN is a metabolite of a number of industrial chemicals ( acetonitrile, propionitrile,

acrylonitrile, n butyronitrile, maleonitrile, and succinonitrile). As a result, occupational or environmental exposure to these chemicals could contribute to the background levels of HCN in biological fluids. HCN is also a metabolite of pharmaceuticals such as Laetrile and a drug used to reduce high blood pressure, and clinical use of these compounds could induce a body burden of HCN.

Exposure to thiocyanate, cyanate, and cyanamide was not assessed for this document. In the absence of data, the default of 20% is used for the RSC for these chemicals.


[Federal Register Volume 76, Number 192 (Tuesday, October 4, 2011)]
[Notices]
[Pages 61463-61466]
[FR Doc No: 2011-25519]

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SECURITIES AND EXCHANGE COMMISSION

[Release No. 34-65439; File No. SR-NYSEArca-2011-68]

Self-Regulatory Organizations; NYSE Arca, Inc.; Notice of Filing
of Proposed Rule Change Amending NYSE Arca Equities Rule 7.12 To Revise
the Current Methodology for Determining When To Halt Trading in All
Stocks Due to Extraordinary Market Volatility

September 28, 2011
    Pursuant to Section 19(b)(1) \1\ of the Securities Exchange Act of
1934 (the ``Act'') \2\ and Rule 19b-4 thereunder,\3\ notice is hereby
given that, on September 27, 2011, NYSE Arca, Inc. (the ``Exchange'' or
``NYSE Arca'') filed with the Securities and Exchange Commission (the
``Commission'') the proposed rule change as described in Items I and II
below, which Items have been prepared by the self-regulatory
organization. The Commission is publishing this notice to solicit
comments on the proposed rule change from interested persons.
---------------------------------------------------------------------------

    \1\ 15 U.S.C. 78s(b)(1).
    \2\ 15 U.S.C. 78a.
    \3\ 17 CFR 240.19b-4.
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I. Self-Regulatory Organization's Statement of the Terms of Substance
of the Proposed Rule Change

    The Exchange proposes to amend NYSE Arca Equities Rule 7.12 to
revise the current methodology for determining when to halt trading in
all stocks due to extraordinary market volatility. The text of the
proposed rule change is available at the Exchange, the Commission's
Public Reference Room, and http://www.nyse.com.

II. Self-Regulatory Organization's Statement of the Purpose of, and
Statutory Basis for, the Proposed Rule Change

    In its filing with the Commission, the self-regulatory organization
included statements concerning the purpose of, and basis for, the
proposed rule change and discussed any comments it received on the
proposed rule change. The text of those statements may be examined at
the places specified in Item IV below. The Exchange has prepared
summaries, set forth in sections A, B, and C below, of the most
significant parts of such statements.

A. Self-Regulatory Organization's Statement of the Purpose of, and
Statutory Basis for, the Proposed Rule Change

1. Purpose
    The Exchange proposes to amend NYSE Arca Equities Rule 7.12 to
revise the current methodology for determining when to halt trading in
all stocks due to extraordinary market volatility. The Exchange is
proposing this rule change in consultation with other equity, options,
and futures markets, the Financial Industry Regulatory Authority, Inc.
(``FINRA''), and staffs of the Commission and the Commodity Futures
Trading Commission.
    Since May 6, 2010, when the markets experienced excessive
volatility in an abbreviated time period, i.e., the ``flash crash,''
the exchanges and FINRA have implemented market-wide measures designed
to restore investor confidence by reducing the potential for excessive
market volatility. Among the measures adopted include pilot plans for
stock-by-stock trading pauses \4\ and related changes to the clearly
erroneous

execution rules \5\ and more stringent market maker quoting
requirements.\6\ In addition, on April 5, 2011, the equities exchanges
and FINRA filed a plan pursuant to Rule 608 of Regulation NMS to
address extraordinary market volatility (the ``Limit Up-Limit Down
Plan'').\7\ As proposed, the Limit Up-Limit Down Plan is designed to
prevent trades in individual NMS stocks from occurring outside
specified price bands.
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    \4\ NYSE Arca Equities Rule 7.11.
    \5\ NYSE Arca Equities Rule 7.10.
    \6\ NYSE Arca Equities Rule 7.23(a)(1).
    \7\ See Securities Exchange Act Release No. 64547 (May 25,
2011), 76 FR 31647 (June 1, 2011).
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    The Joint CFTC-SEC Advisory Committee on Emerging Regulatory Issues
(``Committee'') has recommended that, in addition to the initiatives
already adopted or proposed, the markets should consider reforming the
existing market-wide circuit breakers. Among other things, the
Committee noted that the interrelatedness of today's highly electronic
markets warrants the need to review the present operation of the
system-wide circuit breakers now in place. Specifically, the Committee
recommended that the markets consider replacing the Dow Jones
Industrial Average (``DJIA'') with the S&P 500[reg] Index (``S&P
500''), revising the 10%, 20%, and 30% decline percentages, reducing
the length of trading halts, and allowing halts to be triggered up to
3:30 p.m.\8\
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    \8\ See Summary Report of the Committee, ``Recommendations
Regarding Regulatory Responses to the Market Events of May 6, 2010''
(Feb, 18, 2011). The Exchange notes that NYSE Euronext submitted a
comment letter to the Committee that recommended, among other
things, reform of the market-wide circuit breaker rules. See Letter
to Elizabeth Murphy, Secretary, Commission, from Janet M. Kissane,
SVP and Corporate Secretary, NYSE Euronext (July 19, 2010). The
proposed reforms set forth in this rule proposal differ slightly
from the changes recommended in that comment letter, and represent
consensus among the markets of how to address reform of the market-
wide circuit breakers.
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    The exchanges and FINRA have taken into consideration the
Committee's recommendations, and with some modifications, have proposed
changes to market-wide circuit breakers that the Exchange believes will
provide for a more meaningful measure in today's faster, more
electronic markets, of when to halt stocks on a market-wide basis as a
result of rapid market declines.
Background
    In October 1988 as part of an effort by the securities and futures
markets to implement a coordinated means to address potentially
destabilizing market volatility, the New York Stock Exchange, LLC
(``NYSE'') and other markets adopted rules governing Trading Halts Due
to Extraordinary Market Volatility (i.e., NYSE Rule 80B).\9\ NYSE Rule
80B provides for market-wide halts in trading at specified levels in
order to promote stability and investor confidence during a period of
significant stress. As the Commission noted in its approval order, NYSE
Rule 80B was intended to enable market participants to establish an
equilibrium between buying and selling interest and to ensure that
market participants have an opportunity to become aware of and respond
to significant price movements. Importantly, the market-wide circuit
breakers were not intended to prevent markets from adjusting to new
price levels; rather, they provide for a speed bump for extremely rapid
market declines.\10\
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    \9\ See Securities Exchange Act Release No. 26198 (Oct. 19,
1988) (SR-CBOE-88-14, SR-NASD-88-46, SR-NYSE-88-22, SR-NYSE-88-23,
SR-NYSE-88-24, and SR-Amex-88-24). NYSE Arca Equities Rule 7.12 was
adopted in 2001 when the Pacific Exchange, Inc. filed a rule
proposal to create an electronic trading facility called the
Archipelago Exchange (``ArcaEx''). See Securities Exchange Act
Release No. 44983 (Oct. 25, 2001), 66 FR 55225 (Nov. 1, 2001) (SR-
PCX-00-25). The Pacific Exchange, Inc. is now known as NYSE Arca,
and ArcaEx is now known as NYSE Arca Equities.
    \10\ Id.
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    In its current form,\11\ NYSE Arca Equities Rule 7.12 provides for
Level 1, 2, and 3 declines and specified trading halts following such
declines. The values of Levels 1, 2 and 3 are calculated at the
beginning of each calendar quarter, using 10%, 20% and 30%,
respectively, of the average closing value of the DJIA for the month
prior to the beginning of the quarter. Each percentage calculation is
rounded to the nearest fifty points to create the Levels' trigger
points. The NYSE disseminates the new trigger levels quarterly to the
media and via an Information Memo and is available on the NYSE's Web
site.\12\ The values then remain in effect until the next quarterly
calculation, notwithstanding whether the DJIA has moved and a Level 1,
2, or 3 decline is no longer equal to an actual 10%, 20%, or 30%
decline in the most recent closing value of the DJIA.
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    \11\ The rule was last amended in 1998, when declines based on
specified point drops in the DJIA were replaced with the current
methodology of using a percentage decline that is recalculated
quarterly. See Securities Exchange Act Release No. 39846 (April 9,
1998), 63 FR 18477 (April 15, 1998) (SR-NYSE-98-06, SR-Amex-98-09,
SR-BSE-98-06, SR-CHX-98-08, SR-NASD-98-27, and SR-Phlx-98-15).
    \12\ See e.g., NYSE Regulation Information Memos 11-19 (June 30,
2011) and 11-10 (March 31, 2011).
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    Once a Rule 7.12 circuit breaker is in effect, trading in all
stocks halt for the time periods specified below:

Level 1 Halt

    Anytime before 2 p.m.--one hour; at or after 2 p.m. but before 2:30
p.m.--30 minutes; at or after 2:30 p.m.--trading shall continue, unless
there is a Level 2 Halt.

Level 2 Halt

    Anytime before 1 p.m.--two hours; at or after 1 p.m. but before 2
p.m.--one hour; at or after 2 p.m.--trading shall halt and not resume
for the rest of the day.

Level 3 Halt

    At any time--trading shall halt and not resume for the rest of the
day.
Proposed Amendments
    As noted above, the Exchange, other equities, options, and futures
markets, and FINRA propose to amend the market-wide circuit breakers to
take into consideration the recommendations of the Committee, and to
provide for more meaningful measures in today's markets of when to halt
trading in all stocks. Accordingly, the Exchange proposes to amend NYSE
Arca Equities Rule 7.12 as follows: (i) Replace the DJIA with the S&P
500; (ii) replace the quarterly calendar recalculation of Rule 7.12
triggers with daily recalculations; (iii) replace the 10%, 20%, and 30%
market decline percentages with 7%, 13%, and 20% market decline
percentages; (iv) modify the length of the trading halts associated
with each market decline level; and (v) modify the times when a trading
halt may be triggered. The Exchange believes that these proposed
amendments update the rule to reflect today's high-speed, highly
electronic trading market while still meeting the original purpose of
Rule 7.12: To ensure that market participants have an opportunity to
become aware of and respond to significant price movements.
    First, the Exchange proposes to replace the DJIA with the S&P 500.
The Exchange believes that because the S&P 500 is based on the trading
prices of 500 stocks, as compared to the 30 stocks that comprise the
DJIA, the S&P 500 represents a broader base of securities against which
to measure whether extraordinary market-wide volatility is occurring.
In addition, as noted by the Committee, using an index that correlates
closely with derivative products, such as the E-Mini and SPY, will
allow for a better cross-market measure of market volatility.
    Second, the Exchange proposes to change the recalculation of the
trigger values from once every calendar quarter to daily. The Exchange
believes that updating the trigger values daily will better reflect
current market conditions.

In particular, a daily recalculation will ensure that the percentage
drop triggers relate to current market conditions, and are not compared
to what may be stale market conditions. As noted in the proposed rule,
the daily calculations of the trigger values will be published before
the trading day begins.\13\
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    \13\ The Exchange and other markets will advise via Trader
Update the specific methodology for publishing the daily
calculations, as well as the manner by which the markets will halt
trading in all stocks should a Rule 7.12 trading halt be triggered.
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    Third, the Exchange proposes to decrease the current Level 1, 2,
and 3 declines of 10%, 20%, and 30% to a Level 1 Market Decline of 7%,
a Level 2 Market Decline of 13%, and Level 3 Market Decline of 20%. In
particular, as demonstrated by the May 6, 2010 flash crash, the current
Level 1 10% decline may be too high a threshold before determining
whether to halt trading across all securities. In fact, since adoption,
the markets have halted only once, on October 27, 1997.\14\
Accordingly, to reflect the potential that a lower, yet still
significant decline may warrant a market-wide trading halt, the
Exchange proposes to lower the market decline percentage thresholds.
---------------------------------------------------------------------------

    \14\ At that time, the triggers were based on absolute declines
in the DJIA (350 point decrease for a Level 1 halt and 550 point
decrease for a Level 2 halt).
---------------------------------------------------------------------------

    As further proposed, the Exchange would halt trading based on a
Level 1 or Level 2 Market Decline only once per day. For example, if a
Level 1 Market Decline were to occur and trading were halted, following
the reopening of trading, the Exchange would not halt the market again
unless a Level 2 Market Decline were to occur. Likewise, following the
reopening of trading after a Level 2 Market Decline, the Exchange would
not halt trading again unless a Level 3 Market Decline were to occur,
at which point, trading in all stocks would be halted until the primary
market reopens the next trading day.
    Fourth, to correspond with the lower percentages associated with
triggering a trading halt, the Exchange also proposes to shorten the
length of the market-wide trading halts associated with each Level. As
proposed, a Level 1 or 2 Market Decline occurring after 9:30 a.m.
Eastern and up to and including 3:25 p.m. Eastern, or in the case of an
early scheduled close, 12:25 p.m. Eastern, would result in a trading
halt in all stocks for 15 minutes.\15\
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    \15\ Consistent with the current Rule 7.12 and NYSE Arca
Equities Rule 1.1(j), the proposed Rule 7.12 uses Pacific Time
instead of Eastern Time.
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    The Exchange believes that by reducing the percentage threshold,
coupled with the reduced length of a trading halt, the proposed rule
would allow for trading halts for serious market declines, while at the
same time, would minimize disruption to the market by allowing for
trading to continue after the proposed more-abbreviated trading halt.
The Exchange believes that in today's markets, where trading
information travels in micro-second speed, a 15-minute trading halt
strikes the appropriate balance between the need to halt trading for
market participants to assess the market, while at the same time
reducing the time that the market is halted.
    Finally, because the proposed Level 1 and Level 2 trading halts
will now be 15 minutes, the Exchange proposes amending the rule to
allow for a Level 1 or 2 Market Decline to trigger a trading halt up to
3:25 p.m. Eastern. Under the current rule, a trading halt cannot be
triggered after 2:30 p.m., and this time corresponds to the need for
the markets both to reopen following a 30-minute halt and to engage in
a fair and orderly closing process. However, as the markets experienced
on May 6, 2010, even if the Level 1 decline had occurred that day,
because the market decline occurred after 2:30 p.m., it would not have
triggered a halt under the current rule. The Committee recommended that
trading halts be triggered up to 3:30 p.m. The Exchange agrees that the
proposed amendments must strike the appropriate balance between
permitting trading halts as late in the day as feasible without
interrupting the closing process.
    Accordingly, to accommodate existing NYSE rules concerning closing
procedures, including the publication of imbalance information
beginning at 3:45 p.m. Eastern and the restrictions on entry and
cancellation of market on close (``MOC'') and limit on close (``LOC'')
orders after 3:45 p.m.,\16\ the Exchange proposes that the last Level 1
or Level 2 Market Decline trading halt should be 3:25 p.m. The Exchange
proposes 3:25 p.m. as the cut-off time so that there is time following
the 15-minute trading halt for the markets to reopen before the 3:45
cut-off for entry and cancellation of MOC and LOC orders under Exchange
rules.
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    \16\ See NYSE Rule 123C.
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    As with current Level 3 declines, under the proposed rule, a Level
3 Market Decline would halt trading for the remainder of the trading
day, including any trading that may take place after 4:00 p.m.,
Eastern, and would not resume until the next trading day.
    In addition to these proposed changes, the Exchange proposes to add
to Rule 7.12 how the markets will reopen following a 15-minute trading
halt. In particular, similar to the reopening procedures set forth in
Rule 7.12, the Exchange proposes that if the primary market halts
trading in all stocks, all markets will halt trading in those stocks
until the primary market has resumed trading or notice has been
provided by the primary market that trading may resume. As further
proposed, if the primary market does not re-open a security within 15
minutes following the end of the trading halt, other markets may resume
trading in that security.
    The Exchange proposes to implement the changes to NYSE Arca
Equities Rule 7.12 at the same time that the Limit Up-Limit Down Plan,
if approved, is implemented.
2. Statutory Basis
    The basis under the Act for these proposed rule changes are [sic]
the requirement under Section 6(b)(5)\17\ that an Exchange have rules
that are designed to promote just and equitable principles of trade, to
remove impediments to and perfect the mechanism of a free and open
market and a national market system and, in general, to protect
investors and the public interest. Specifically, this rule proposal
supports the objectives of perfecting the mechanism of a free and open
market and the national market system because it promotes uniformity
across markets concerning when and how to halt trading in all stocks as
a result of extraordinary market volatility.
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    \17\ 15 U.S.C. 78f(b)(5).
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B. Self-Regulatory Organization's Statement on Burden on Competition

    The Exchange does not believe that the proposed rule change will
impose any burden on competition that is not necessary or appropriate
in furtherance of the purposes of the Act.

C. Self-Regulatory Organization's Statement on Comments on the Proposed
Rule Change Received From Members, Participants, or Others

    No written comments were solicited or received with respect to the
proposed rule change.

III. Date of Effectiveness of the Proposed Rule Change and Timing for
Commission Action

    Within 45 days of the date of publication of this notice in the
Federal Register or within such longer period (i) as the Commission may
designate up to 90 days of such date if it finds such longer period to
be appropriate and

publishes its reasons for so finding or (ii) as to which the self-
regulatory organization consents, the Commission will:
    (A) By order approve or disapprove the proposed rule change, or
    (B) Institute proceedings to determine whether the proposed rule
change should be disapproved.

IV. Solicitation of Comments

    Interested persons are invited to submit written data, views, and
arguments concerning the foregoing, including whether the proposed
changes to the market-wide circuit breaker regime are consistent with
the Act. The Commission specifically requests comment on the following:
     As discussed above, the proposed rule change would narrow
the percentage market declines that would trigger a market-wide halt in
trading. How would the proposed changes interact with the existing
single-stock circuit breaker pilot program \18\ or, if approved, the
proposed NMS Plan to establish a limit-up/limit-down mechanism for
individual securities? \19\
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    \18\ See Securities Exchange Act Release No. 64735 (June 23,
2011), 76 FR 38243 (June 29, 2011) (SR-BATS-2011-016; SR-BYX-2011-
011; SR-BX-2011-025; SR-CBOE-2011-049; SR-CHX-2011-09; SR-EDGA-2011-
15; SR-EDGX-2011-14; SR-FINRA-2011-023; SR-ISE-2011-028; SR-NASDAQ-
2011-067; SR-NYSE-2011-21; SR-NYSEAmex-2011-32; SR-NYSEArca-2011-26;
SR-NSX-2011-06; SR-Phlx-2011-64) (approving the ``Phase III Pilot
Program''). The Phase III Pilot Program has been extended through
January 2012. See, e.g., Securities Exchange Act Release 65094
(August 10, 2011), 76 FR 50779 (August 16, 2011) (SR-NASDAQ-2011-
011).
    \19\ See Securities Exchange Act Release No. 64547 (May 25,
2011), 76 FR 31647 (June 1,
     2011).
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     To what extent could the concurrent triggering of single
stock circuit breakers in many S&P 500 Index stocks lead to
difficulties in calculating the index? Would the triggering of many
single stock circuit breakers in a general market downturn cause the
index calculation to become stale and thereby delay the triggering of
the market-wide circuit breaker?
     Should the market-wide circuit breaker be triggered if a
sufficient number of single-stock circuit breakers or price limits are
triggered, and materially affect calculations of the S&P 500 Index?
     Should market centers implement rules that mandate
cancellation of pending orders in the event a market-wide circuit
breaker is triggered? If so, should such a rule require cancellation of
all orders or only certain order types (e.g., limit orders)? Should all
trading halts trigger such cancellation policies or should the
cancellation policies apply only to a Level 3 Market Decline?
     Should some provision be made to end the regular trading
session if a market decline suddenly occurs after 3:25 p.m. but does
not reach the 20% level?
     In the event of a Level 3 Market Decline, should some
provision be made for the markets to hold a closing auction?
     Should the primary market have a longer period (e.g., 30
minutes) to reopen trading following a Level 2 Market Decline before
trading resumes in other venues?
     In the event of a Level 3 Market Decline, should the
markets wait for the primary market to reopen trading in a particular
security on the next trading day before trading in that security
resumes?
    Comments may be submitted by any of the following methods:

Electronic comments

     Use the Commission's Internet comment form (http://www.sec.gov/rules/sro.shtml); or
     Send an e-mail to<EMAIL_ADDRESS>Please include
File Number SR-NYSEArca-2011-68 on the subject line.

Paper Comments

     Send paper comments in triplicate to Elizabeth M. Murphy,
Secretary, Securities and Exchange Commission, 100 F Street, NE.,
Washington, DC 20549-1090.

All submissions should refer to File Number SR-NYSEArca- 2011-68. This
file number should be included on the subject line if e-mail is used.
To help the Commission process and review your comments more
efficiently, please use only one method. The Commission will post all
comments on the Commission's Internet Web site (http://www.sec.gov/rules/sro.shtml). Copies of the submission, all subsequent amendments,
all written statements with respect to the proposed rule change that
are filed with the Commission, and all written communications relating
to the proposed rule change between the Commission and any person,
other than those that may be withheld from the public in accordance
with the provisions of 5 U.S.C. 552, will be available for website
viewing and printing in the Commission's Public Reference Room, 100 F
Street, NE., Washington, DC 20549, on official business days between
the hours of 10 a.m. and 3 p.m. Copies of such filing also will be
available for inspection and copying at the principal office of NYSE
Arca. All comments received will be posted without change; the
Commission does not edit personal identifying information from
submissions. You should submit only information that you wish to make
publicly available. All submissions should refer to File Number SR-
NYSEArca-2011-68 and should be submitted on or before October 25, 2011.

    For the Commission, by the Division of Trading and Markets,
pursuant to delegated authority.\20\
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    \20\ 17 CFR 200.30-3(a)(12).
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Elizabeth M. Murphy,
Secretary.
[FR Doc. 2011-25519 Filed 10-3-11; 8:45 am]
BILLING CODE 8011-01-P