[Federal Register Volume 76, Number 217 (Wednesday, November 9, 2011)]
[Notices]
[Pages 69780-69783]
[FR Doc No: 2011-29037]

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SECURITIES AND EXCHANGE COMMISSION

[Release No. 34-65682; File No. SR-CBOE-2011-099]

Self-Regulatory Organizations; Chicago Board Options Exchange,
Incorporated; Notice of Proposed Rule Change, as Modified by Amendment
No. 1 Thereto, Concerning Industry Directors and the Nomination of
Representative Directors

 November 3, 2011.
    Pursuant to Section 19(b)(1) of the Securities Exchange Act of 1934
(the ``Act''),\1\ and Rule 19b-4 thereunder,\2\ notice is hereby given
that on October 21, 2011, the Chicago Board Options Exchange,
Incorporated (``Exchange'' or ``CBOE'') 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 Exchange. On November 1, 2011, the Exchange submitted a technical
amendment (``Amendment No. 1'') to the proposed rule change.\3\ The
Commission is publishing this notice to solicit comments on the
proposed rule change, as amended, from interested persons.
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    \1\ 15 U.S.C. 78s(b)(1).
    \2\ 17 CFR 240.19b-4.
    \3\ As provided in the instructions to Form 19b-4, the Exchange
noted in Item 2 of its filing that it needed to obtain, but had not
yet obtained, formal approval from its Board of Directors for the
Bylaw, Certificate of Incorporation, and Voting Agreement changes
set forth in this proposed rule change. The Exchange also noted that
it needed to obtain, but had not yet obtained, approval from CBOE
Holdings, the Exchange's sole stockholder, of the changes to the
Certificate of Incorporation and Voting Agreement. The Exchange
stated that once these approvals were obtained, it would file a
technical amendment to this proposed rule change to reflect these
approvals. Amendment No. 1 reflected that the requisite approvals
were obtained on November 1, 2011, and represented that no further
action in connection with this proposed rule change was required. In
addition, Amendment No. 1 contained the Exchange's consent to an
extension of time for Commission consideration of this proposed rule
change for an additional thirty-five days after November 1, 2011
(the filing date of this amendment).
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I. Self-Regulatory Organization's Statement of the Terms of Substance
of the Proposed Rule Change

    The Exchange proposes to: (i) Amend its Bylaws to eliminate the
requirement that at least 30% of the members of the Board of Directors
must be Industry Directors; (ii) amend its Bylaws relating to its
Advisory Board; (iii) amend its Bylaws relating to the nomination of
Representative Directors; and (iv) make conforming changes to the CBOE
Certificate of Incorporation and the

Voting Agreement between CBOE and CBOE Holdings, Inc. (``CBOE
Holdings''). The text of the proposed amendments to CBOE's Bylaws,
CBOE's Certificate of Incorporation and the Voting Agreement are
available on the Exchange's Web site (http://www.cboe.org/legal), at
the Exchange's Office of the Secretary and at the Commission.

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 Exchange 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 the
Statutory Basis for, the Proposed Rule Change

1. Purpose
    The purpose of this proposed rule change is to (i) Amend CBOE's
Bylaws to eliminate the requirement that at least 30% of the members of
the Board of Directors must be Industry Directors; (ii) amend CBOE's
Bylaws relating to its Advisory Board; (iii) amend CBOE's Bylaws
relating to the nomination of Representative Directors; and (iv) make
conforming changes to CBOE's Certificate of Incorporation and the
Voting Agreement between CBOE and CBOE Holdings.
(1) Elimination of 30% Industry Director Requirement
    In light of CBOE's demutualization and conversion from a membership
organization to a stock corporation owned by a public holding company
in June, 2010, and based on the Exchange's experience since that time
in operating in that form, the Exchange believes that it is no longer
necessary that its Bylaws contain a requirement that its Board of
Directors be composed of at least 30% Industry Directors. The Exchange
believes that eliminating the requirement that at least 30% of its
Board be composed of Industry Directors as defined in the Bylaws
provides it with appropriate flexibility as it evaluates the structure
and composition of its Board in the future. The Exchange notes that it
has not made a determination as to whether it will reduce (or
eliminate) the number of directors on its Board who qualify as an
Industry Director as defined in the Bylaws. Even if the number of
individuals who would technically qualify as Industry Directors on the
Board of Directors is reduced, the Exchange recognizes the importance
of having directors who have industry expertise and knowledge (whether
those directors are Industry Directors or Non-Industry Directors).
Additionally, no matter what the composition of its Board is, the
Exchange intends to maintain the fair representation of its Trading
Permit Holders in the selection of its directors and administration of
its affairs consistent with Section 6(b)(3) of the Securities Exchange
Act of 1934, as amended (``Act''), as further described below.
    In the event the Exchange determines in the future to reduce the
number of directors on its Board who would qualify as an Industry
Director, the Exchange believes that a Board composed of all or nearly
all Non-Industry Directors would be consistent with the Act, including
Section 6(b)(3) of the Act relating to the fair representation of CBOE
Trading Permit Holders in the selection of directors and the
administration of the Exchange.\4\ The Exchanges also notes that in
such a case, at all times at least 20% of the directors serving on the
Board shall be Representative Directors nominated (or otherwise
selected through the petition process) by the Representative Director
Nominating Body as provided in Section 3.2 of the Bylaws. Under Section
3.2, the Representative Director Nominating Body provides a mechanism
for Trading Permit Holders to provide input with respect to the
nominees for Representative Directors and also allows for Trading
Permit Holders to nominate alternative candidates by petition.
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    \4\ See, e.g., Securities Exchange Act Release No. 48946
(December 17, 2003), 68 FR 74678 (December 24, 2003) (approving SR-
NYSE-2003-34).
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    In connection with the proposed elimination of the requirement that
at least 30% of the Board shall be composed of Industry Directors, CBOE
also proposes to amend Section 4.4 of its Bylaws relating to the
composition of the Nominating and Governance Committee. Specifically,
CBOE proposes to delete the clause that states that the Nominating and
Governance Committee shall consist of both Industry and Non-Industry
Directors, given that at some point in the future the Board may not
have Industry Directors serving on it.
(2) Amendments Relating to the Advisory Board
    Recently, CBOE amended its Bylaws to provide for the establishment
of an Advisory Board which shall advise the Office of the Chairman
regarding matters of interest to Trading Permit Holders. CBOE now
proposes to amend Section 6.1 of the Bylaws to clarify that the
Exchange ``will'' (as opposed to ``may'') have an Advisory Board, which
shall advise the Board of Directors in addition to the Office of the
Chairman regarding matters that impact Trading Permit Holders. CBOE
also proposes to amend Section 6.1 of its Bylaws to expressly provide
that at least two members of the Advisory Board shall be Trading Permit
Holders or persons associated with Trading Permit Holders. CBOE notes
that the Advisory Board provides a mechanism for Trading Permit Holders
to provide industry feedback to CBOE's Chairman and CEO, Executive Vice
Chairman, President and Lead Director, all of whom are members of the
Advisory Board, consistent with Section 6(b)(3) of the Act.
(3) Nomination of Representative Directors
    The Exchange Bylaws will continue to require that at least 20% of
CBOE's directors must be Representative Directors. However, the
Exchange proposes to amend its Bylaws in a number of respects with
regard to the nomination process for the Representative Directors.
Currently, as described in Section 3.2 of the Bylaws, the
Representative Directors are nominated (or otherwise selected through a
petition process) by the Industry-Director Subcommittee of the CBOE
Nominating and Governance Committee. The Industry-Director Subcommittee
is composed of all of the Industry Directors serving on the Nominating
and Governance Committee. CBOE Trading Permit Holders may nominate
alternative Representative Director candidates to those nominated by
the Industry Director Subcommittee, in which case a Run-off Election is
held in which CBOE's Trading Permit Holders vote to determine which
candidates will be elected to the CBOE Board of Directors to serve as
Representative Directors.
    Because it is possible that at some point in the future CBOE's
Board may not have Industry Directors as defined in the Bylaws serving
on it, CBOE proposes to amend its Bylaws to eliminate the requirement
in Section 3.2 that the Representative Directors must be Industry
Directors. In addition, CBOE proposes to incorporate into the Bylaws

the concept of a Representative Director Nominating Body which shall
mean the current Industry-Director Subcommittee of the Nominating and
Governance Committee if there are at least two Industry Directors on
the Nominating and Governance Committee. If the Nominating and
Governance Committee has less than two Industry Directors as defined in
the Bylaws, then the Representative Director Nominating Body shall mean
the Trading Permit Holders Subcommittee of the Advisory Board.\5\ The
Representative Director Nominating Body will nominate the
Representative Directors in accordance with the provisions of Section
3.2 of the Bylaws. In that regard, it will perform the functions
currently performed by the Industry-Director Subcommittee.
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    \5\ See proposed new Bylaw definition 1.1(k) and the proposed
changes to Sections 4.4 and 6.1 of the Bylaws.
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    In addition, CBOE proposes to amend Section 3.2 of the Bylaws with
regard to the time period by which the Representative Director nominees
are announced via circular to the Trading Permit Holders, the deadline
for Trading Permit Holders to nominate alternative candidates via
petition, and the timing of any Run-Off Election. Presently, Section
3.2 of the Bylaws provides that the Industry-Director Subcommittee
shall issue a circular announcing its Representative Director nominees
not later than January 15th, or the first business day thereafter if
the 15th is not a business day. Trading Permit Holders may nominate
alternative candidates for the Representative Director positions by
petition, which petition needs to be filed with the Secretary of the
Exchange not later than 5 p.m. on the Monday preceding the first Friday
in February (or the first business day thereafter in the event that
Monday occurs on a holiday). If one or more valid petitions are
received, a Run-Off Election is held at least 20 days prior to the
mailing of any notice of the annual meeting.
    CBOE believes that it would be useful and appropriate to modify
these deadlines in order to provide the Exchange, the Nominating and
Governance Committee and the Representative Director Nominating Body
with additional flexibility. The Exchange proposes to amend Section 3.2
to provide that:

     The Representative Director Nominating Body shall issue
a circular to the Trading Permit Holders identifying the
Representative Director nominees not earlier than December 1st and
not later than January 15th, or the first business day thereafter if
January 15th is not a business day;
     Trading Permit Holders may nominate alternative
candidates for election to the Representative Director positions to
be elected in a given year by submitting a petition to the Secretary
not later than 5 p.m. (Chicago time) on the 10th business day
following the issuance of the circular to the Trading Permit Holders
identifying the Representative Director nominees selected by the
Representative Director Nominating Body (``Petition Deadline''). The
Exchange believes that 10 business days is a reasonable and
sufficient amount of time for Trading Permit Holders to obtain a
petition signed by individuals representing not more than 10% of the
total outstanding Trading Permits at that time to nominate by
petition alternative candidates for election to the Representative
Director positions. CBOE notes that many Trading Permit Holders hold
multiple permits. CBOE also notes that 10 business days is
consistent with the minimum time period that was effective in 2010
and that would be available in 2011 under the existing Bylaws for
the nomination of alternative candidates by petition; and
     The Run-off Election will be held not more than 45 days
after the Petition Deadline.

    As noted, the Exchange believes that modifying these deadlines as
proposed will provide the Exchange with additional flexibility and
enable the Exchange to complete the process for determining its
nominees at an earlier point in time without changing the time period.
Modifying these deadlines also will assist in synchronizing CBOE's
nomination process with the nomination process for CBOE's parent
company, CBOE Holdings, Inc. In addition to the above changes, CBOE
proposes to replace all references to the Industry-Director
Subcommittee in the Bylaws with the term Representative Director
Nominating Body.
    Finally, CBOE proposes to amend Section 2.2 of its Bylaws relating
to the timing of its annual meeting to clarify that in no event shall
the annual meeting date each year be prior to the completion of the
process for the nomination of the Representative Directors for that
annual meeting as set forth in Sections 3.1 and 3.2.
    CBOE is not proposing to amend any other provisions with regard to
the timing and process for the nomination of the Representative
Directors.
(4) Amendment to Certificate of Incorporation and Voting Agreement
    CBOE also proposes to make conforming changes to its Certificate of
Incorporation and the Voting Agreement between it and its parent
company, CBOE Holdings. Specifically, CBOE proposes to amend its
Certificate of Incorporation and the Voting Agreement to replace the
references to the Industry-Director Subcommittee with the term
Representative Director Nominating Body. It also proposes to make non-
substantive changes to the Voting Agreement.
2. Statutory Basis
    For the reasons set forth above, CBOE believes that this filing is
consistent with Section 6(b) of the Act,\6\ in general, and furthers
the objectives of Section 6(b)(1) of the Act \7\ and Section 6(b)(5) of
the Act \8\ in particular, in that (i) It enables CBOE to be so
organized as to have the capacity to be able to carry out the purposes
of the Act and to comply, and to enforce compliance by its Trading
Permit Holders and persons associated with its Trading Permit Holders,
with the provisions of the Act, the rules and regulations thereunder,
and the rules of CBOE and (ii) to prevent fraudulent and manipulative
acts and practices, to promote just and equitable principles of trade,
to remove impediments to, and perfect the mechanism of, a free and open
market and, in general, to protect investors and the public interest.
Specifically, CBOE believes that the proposed changes will improve and
add greater flexibility to CBOE's governance structure (i) By
eliminating the requirement that the Board of Directors shall be
composed of at least 30% Industry Directors as defined in the Bylaws;
(ii) by modifying the process for the nomination of Representative
Directors, including granting the Trading Permit Holders and persons
associated with Trading Permit Holders on the Advisory Board the
authority to nominate the Representative Directors in those instances
in which the Nominating and Governance Committee has less than two
Industry Directors; (iii) by amending the Bylaws to provide that the
Exchange will establish an Advisory Board, which CBOE views as a useful
vehicle for the Board to receive input from the perspective of Trading
Permit Holders and with respect to matters of interest to Trading
Permit Holders; and (iv) by modifying the deadlines relating to the
nomination of the Representative Directors, which CBOE believes will
provide it, the Nominating and Governance Committee and the
Representative Director Nominating Body with additional flexibility
with respect to the timing of the nomination process so that the
Exchange is not locked into specific dates that may not work well
during a particular year. Additionally, CBOE believes that this filing
is consistent with Section 6(b)(3) of the Act in that CBOE's Bylaws
will continue to provide for the fair

representation of CBOE Trading Permit Holders in the selection of
directors and the administration of the Exchange.
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    \6\ 15 U.S.C. 78f(b).
    \7\ 15 U.S.C. 78f(b)(1).
    \8\ 15 U.S.C. 78f(b)(5).
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B. Self-Regulatory Organization's Statement on Burden on Competition

    CBOE does not believe that the proposed rule change will impose any
burden on competition 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

    The Exchange neither solicited nor received comments on the
proposal.

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 such proposed rule change, or
    (B) Institute proceedings to determine whether the proposed rule
change should be disapproved.
    As reflected in Amendment No. 1, the Exchange has consented to an
extension of time for Commission consideration of this proposal for an
additional thirty-five days after the filing of Amendment No. 1.\9\
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    \9\ Amendment No. 1 was filed on November 1, 2011. See supra
note 3 (describing Amendment No. 1).
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IV. Solicitation of Comments

    Interested persons are invited to submit written data, views, and
arguments concerning the foregoing, including whether the proposed rule
change is consistent with the Act. 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 email to<EMAIL_ADDRESS>Please include
File Number SR-CBOE-2011-099 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-CBOE-2011-099. This file
number should be included on the subject line if email 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 Web site
viewing and printing in the Commission's Public Reference Room 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 offices of the Exchange. 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 available publicly. All submissions should refer to
File Number SR-CBOE-2011-099, and should be submitted on or before
November 30, 2011.

    For the Commission, by the Division of Trading and Markets,
pursuant to delegated authority.\10\
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    \10\ 17 CFR 200.30-3(a)(12).
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Kevin M. O'Neill,
Deputy Secretary.
[FR Doc. 2011-29037 Filed 11-8-11; 8:45 am]
BILLING CODE 8011-01-P


[Federal Register Volume 84, Number 101 (Friday, May 24, 2019)]
[Rules and Regulations]
[Pages 24027-24028]
[FR Doc No: 2019-10953]

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DEPARTMENT OF HEALTH AND HUMAN SERVICES

Food and Drug Administration

21 CFR Part 216

[Docket No. FDA-2019-D-2011]

Section 503A Bulks List Final Rule Questions and Answers;
Guidance for Industry; Small Entity Compliance Guide; Availability

AGENCY: Food and Drug Administration, HHS.

ACTION: Notification of availability.

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SUMMARY: The Food and Drug Administration (FDA, the Agency, or we) is
announcing the availability of a guidance for industry entitled
``Section 503A Bulks List Final Rule Questions and Answers--Small
Entity Compliance Guide.'' The small entity compliance guide (SECG) is
intended to help small entities comply with the final rule establishing
the list of bulk drug substances that can be used in accordance with
certain compounding provisions of the Federal Food, Drug, and Cosmetic
Act (FD&C Act).

DATES: The announcement of the guidance is published in the Federal
Register on May 24, 2019.

ADDRESSES: You may submit either electronic or written comments on
Agency guidances at any time as follows:

Electronic Submissions

    Submit electronic comments in the following way:
     Federal eRulemaking Portal: https://www.regulations.gov.
Follow the instructions for submitting comments. Comments submitted
electronically, including attachments, to https://www.regulations.gov
will be posted to the docket unchanged. Because your comment will be
made public, you are solely responsible for ensuring that your comment
does not include any confidential information that you or a third party
may not wish to be posted, such as medical information, your or anyone
else's Social Security number, or confidential business information,
such as a manufacturing process. Please note that if you include your
name, contact information, or other information that identifies you in
the body of your comments, that information will be posted on https://www.regulations.gov.
     If you want to submit a comment with confidential
information that you do not wish to be made available to the public,
submit the comment as a written/paper submission and in the manner
detailed (see ``Written/Paper Submissions'' and ``Instructions'').

Written/Paper Submissions

    Submit written/paper submissions as follows:
     Mail/Hand Delivery/Courier (for written/paper
submissions): Dockets Management Staff (HFA-305), Food and Drug
Administration, 5630 Fishers Lane, Rm. 1061, Rockville, MD 20852.
     For written/paper comments submitted to the Dockets
Management Staff, FDA will post your comment, as well as any
attachments, except for information submitted, marked and identified,
as confidential, if submitted as detailed in ``Instructions.''

    Instructions: All submissions received must include the Docket No.
FDA-2019-D-2011 for ``Section 503A Bulks List Final Rule Questions and
Answers; Guidance for Industry; Small Entity Compliance Guide;
Availability.'' Received comments will be placed in the docket and,
except for those submitted as ``Confidential Submissions,'' publicly
viewable at https://www.regulations.gov or at the Dockets Management
Staff between 9 a.m. and 4 p.m., Monday through Friday.
     Confidential Submissions--To submit a comment with
confidential information that you do not wish to be made publicly
available, submit your comments only as a written/paper submission. You
should submit two copies total. One copy will include the information
you claim to be confidential with a heading or cover note that states
``THIS DOCUMENT CONTAINS CONFIDENTIAL INFORMATION.'' The Agency will
review this copy, including the claimed confidential information, in
its consideration of comments. The second copy, which will have the
claimed confidential information redacted/blacked out, will be
available for public viewing and posted on https://www.regulations.gov.
Submit both copies to the Dockets Management Staff. If you do not wish
your name and contact information to be made publicly available, you
can provide this information on the cover sheet and not in the body of
your comments and you must identify this information as
``confidential.'' Any information marked as ``confidential'' will not
be disclosed except in accordance with 21 CFR 10.20 and other
applicable disclosure law. For more information about FDA's posting of
comments to public dockets, see 80 FR 56469, September 18, 2015, or
access the information at: https://www.gpo.gov/fdsys/pkg/FR-2015-09-18/pdf/2015-23389.pdf.
    Docket: For access to the docket to read background documents or
the electronic and written/paper comments received, go to https://www.regulations.gov and insert the docket number, found in brackets in
the heading of this document, into the ``Search'' box and follow the
prompts and/or go to the Dockets Management Staff, 5630 Fishers Lane,
Rm. 1061, Rockville, MD 20852.
    You may submit comments on any guidance at any time (see 21 CFR
10.115(g)(5)).
    Submit written requests for single copies of the SECG to the
Division of Drug Information, Center for Drug Evaluation and Research,
Food and Drug Administration, 10001 New Hampshire Ave., Hillandale
Building, 4th Floor, Silver Spring, MD 20993-0002. Send one self-
addressed adhesive label to assist that office in processing your
requests. See the SUPPLEMENTARY INFORMATION section for electronic
access to the SECG.

FOR FURTHER INFORMATION CONTACT: Rosilend Lawson, Center for Drug
Evaluation and Research, Office of Unapproved Drugs and Labeling
Compliance, Food and Drug Administration, 10903 New Hampshire Ave.,
Bldg. 51, Rm. 5197, Silver Spring, MD 20993-0002,<PHONE_NUMBER>,
<EMAIL_ADDRESS>
SUPPLEMENTARY INFORMATION:

I. Background

    In the Federal Register of February 19, 2019 (84 FR 4696), we
issued a final rule establishing the list of bulk drug substances that
can be used in compounding under section 503A of the FD&C Act (the
final rule) (21 U.S.C. 353a). The final rule, entitled ``List of Bulk
Drug Substances That Can Be Used To Compound Drug Products in
Accordance With Section 503A of the Federal Food, Drug, and Cosmetic
Act,'' is codified at 21 CFR 216.23 and became effective March 21,
2019.
    We examined the economic implications of the final rule as required
by the Regulatory Flexibility Act (5 U.S.C. 601-612) and, because we do
not have enough information about the effect of the final rule on small
entities, determined that the final rule will have a significant
economic impact on a substantial number of small entities. In
compliance with section 212 of the Small Business Regulatory
Enforcement Fairness Act (Pub. L. 104-121, as amended by Pub. L. 110-
28), we are making available the SECG to explain the actions that a
small entity must take to comply with the rule.
    We are issuing the SECG consistent with our good guidance practices
regulation (21 CFR 10.115). The SECG represents the current thinking of
FDA on the final rule. It does not establish any rights for any person
and is not binding on FDA or the public. You can use an alternative
approach if it satisfies the requirements of the applicable statutes
and regulations. This guidance is not subject to Executive Order 12866.

II. Electronic Access

    Persons with access to the internet may obtain the SECG at either
https://www.fda.gov/Drugs/GuidanceComplianceRegulatoryInformation/Guidances/default.htm or https://www.regulations.gov. Use the FDA
website listed in the previous sentence to find the most current
version of the guidance.

    Dated: May 21, 2019.
Lowell J. Schiller,
Principal Associate Commissioner for Policy.
[FR Doc. 2019-10953 Filed 5-23-19; 8:45 am]
 BILLING CODE 4164-01-P


Minutes of the March 20, 2012
Exposure Modeling Public Meeting
Office of Pesticide Programs (OPP) 4[th] Floor Conference Center
2777 South Crystal Drive  -  Potomac Yard Two, North
Arlington, VA  22202

Welcome and Introductions

The USEPA/OPP/EFED hosts biannual Exposure Modeling Public Meetings (EMPMs), which provide a forum for exchanging information between OPP/EFED and stakeholders with similar technical expertise on current issues related to pesticide exposure modeling in support of risk assessment.  Katrina White and Dirk Young chaired the March 20, 2012 meeting in the capacity of co-chairs of the Water Quality Technical Team.  The minutes and presentation slides for the March 20, 2012 EMPM are posted in the docket (EPA-HQ-OPP-2009-0879), which can be accessed at http://www.regulations.gov/.   The docket ID # is reported on the EMPM webpage: http://www.epa.gov/oppefed1/models/water/empm_top.htm

Brief Updates:
* EFED has updated the HUC8 percert cropped area (PCA) adjustment factors.  They can be found in the  guidance document titled, "Development and Use of Percent Cropped Area and Percent Turf Area Adjustment Factors in Drinking Water Exposure Assessments: 2012 Update" available at http://www.epa.gov/oppefed1/models/water/pca_adjustment_dwa.html
* Guidance for Evaluating and Calculating Degradation Kinetics in Environmental Media is now available at: http://www.epa.gov/oppfead1/international/naftatwg/guidance/degradation-kin.pdf

Presentations Abstracts and Notes:

1. NAFTA Guidance for Calculating Degradation Kinetics in Environmental Media
   Dirk Young[1], Ian Kennedy[2]
   [1]Environmental Fate and Effects Division.  United States Environmental Protection Agency
   [2]Health Canada

The USEPA and Health Canada (NAFTA partners) have developed guidance for calculating degradation rates for transport model inputs (i.e., PRZM and EXAMS).  The NAFTA guidance specifies the conditions under which a first-order model can be used to represent pesticide degradation data in NAFTA assessments and provides a procedure to determine a representative rate when the data deviate from a first-order concept. The NAFTA guidance is based on the premise that there is no "correct" transformation of non-first-order data into first-order model parameters; therefore, any parameter transformation will require a subjective decision based on an agreed-upon level of protectiveness. The emphasis of the NAFTA procedure is therefore on standardization of a process rather than on statistics of determining "best fit" models.  In this regard the NAFTA group has arrived at a comparatively simple method that has preserved some standard assumptions used by FOCUS such as use of a DT90 as a reference point.

Notes:
In his presentation, Dirk Young explained the NAFTA guidance for calculating degradation kinetics that USEPA and Health Canada (NAFTA partners) have developed for transport model inputs. Dirk explained how EPA and Health Canada used data from aerobic soil metabolism studies to describe the challenges when the data did not follow first-order kinetics. Therefore, the main idea behind the NAFTA project was to find a standardization process to determine a representative single first-order rate for modeling when the data deviate from first-order degradation.

The first step in the NAFTA guidance is to determine whether the data is significantly non-first order. If data are non-first order, then the representative half-life using the indeterminate order rate equation (IORE) and the double first order in parallel (DFOP) equation (this is the DFOP slow rate) is obtained. A representative single first order half-life using the IORE equation is called the TIORE.  The lower of TIORE or the DFOP slow rate is used as a representative single first-order model input value.  The NAFTA project is currently completed; however, the implementation plan and technical evaluation of the R program and package to calculate kinetics is yet to be completed.

Questions:
   1. What is DFOP? Is it two-compartment decay? DFOP stands for Double First-Order in Parallel and it is a two-compartment decay.
   2. Are you combining studies to do this data analysis? Because it is conservative as it takes the 90[th] percentile confidence. No, we are not combining studies. You can have different soil studies and some of them will follow Single First-Order (SFO), while others will not follow SFO. Therefore, you will be using this approach for soils that do not follow SFO.

2. Update: Implementation of PRZM-GW
   Reuben Baris, Michael Barrett, Rochelle F. H. Bohaty, Marietta Echeverria, Ian Kennedy, Greg Malis, Dirk Young, and James Wolf
   Environmental Fate and Effects Division.  United States Environmental Protection Agency, Arlington, VA

Estimation of pesticide concentrations in groundwater is one of the considerations as part of the exposure assessment in the pesticide registration process. For this reason, Canada and the United States combined efforts as part of the North American Free Trade Agreement (NAFTA) to develop a harmonized groundwater modeling protocol. This included the development of a common conceptual groundwater modeling scenario for regulatory purposes designed to be protective of even the most vulnerable drinking water supplies. The Pesticide Root Zone Model (PRZM) was selected as the NAFTA regulatory tool. Evaluation of PRZM was completed by comparing simulated pesticide concentrations to available targeted and non-targeted monitoring data. For the majority of chemicals tested, PRZM-predicted pesticide concentrations represent upper bound estimates of exposure in groundwater when conservative input parameters are used (e.g., maximum application rates, annually repeated applications, conservative degradation assumptions).  There are some pesticide detections in monitoring data that are not captured by PRZM model estimates. This may be a result of physical processes that are not accounted for in PRZM (e.g., preferential flow or macroparticle transport). With site specific adjustments to the PRZM input values estimated pesticide concentrations compare very well to monitoring data (the same order or within an order of magnitude). The evaluation demonstrates that PRZM is a versatile assessment tool that can be used both as a screening tool and a refined site-specific tool in risk assessment.

Notes:

The presentation began by outlining the guidance documents under which PRZM-GW and all EPA models are implemented: Guidance on the Development, Evaluation, and Application of Environmental Models produced by the Council for Regulatory Environmental Modeling (CREM) and Guidance for Quality Assurance Project Plans for Modeling produced by the Office of Environmental Information (OEI).  A new guidance, Guidance on Quality Assurance Project Plans, combines the two aforementioned guidance documents.  It was then explained how these guidances apply to the project.

The conceptual model is the same as the previous one presented to the EMPM, with the exception of a variable well screen length to replace a one-meter standard well screen length.  Of the 19 models that were considered,  3 models were evaluated  (PRZM, LEACHM, and PEARL), and  PRZM was  eventually selected.  The data quality objectives for the model specify  that non-targeted monitoring data should have lower values than the estimated value, and targeted monitoring results should have similar concentrations to simulations.  Some observed concentrations in non-targeted studies were above simulated concentrations; however, this may be attributed to  preferential flow and other unaccounted factors.  In the National Alachlor Well-Water Survey, PRZM provided conservative estimates for wells.  Even when the hydrolysis half-life was estimated to be 4 years, large differences in EDWCs could be seen between a long hydrolysis half-life and stability to hydrolysis since PRZM-GW simulations run for 30 to 100 years.  Label rates and soil degradation differences also contribute significantly to changing EDWCs.   The model is still in the evaluation phase within EFED, and guidance for consistent use among risk assessors is being developed concurrently.

Q: From Stuart Cohen: How do PRZM-GW concentrations compare to SCIGROW concentrations?
A: SCIGROW only models one year, whereas PRZM-GW models 30 to 100 years so results are not directly comparable.  Also, SCIGROW is regression based whereas PRZM-GW is mechanistic.  However, there are comparisons that will be released with other model documentation.

Q: For a hydrolytically stable compound, how does PRZM-GW compare to monitoring and SCIGROW?
A: The models are not directly comparable with respect to hydrolysis alone because SCIGROW does not include hydrolysis as an input.  Long term simulations like PRZM-GW need accurate hydrolysis estimates.  Chemicals with pH- dependent hydrolysis half-lives can have high monitoring detections in sites highly acidic or highly alkaline because extreme pH values are not modeled.  2,4-D is an example of this.

Q: PMRA: How is soil hydrolysis accounted for relative to aerobic soil metabolism?
A: Degradation from aerobic soil metabolism is restricted to the top one meter in the soil profile.  Degradation from hydrolysis is active in the full soil profile.
Note from Cal DPR: With respect to monitoring data, California Department of Pesticide Regulation has not found alachlor parent in samples, only its associated degradates.  Additionally, CalDPR is finding concentrations 3-4X higher in run-off areas as opposed to groundwater.

Q: Cal DPR: The diuron example shows that the application rate is important.  How was the application rate determined? It should be noted that diuron is used as a desiccant at 2 lb/acre.
A: The application rate was calculated over the full 25 mi[2] application area.

Q: Syngenta: How is over-prediction accounted for in the model evaluation?
A: EFED is working with BEAD to better characterize use data and we have a number of other refinements that can be made.

3. Measuring and Estimating Concentrations in Drinking Water:  A Historical Perspective
   Russell L. Jones
   BayerCrop Science

After the adoption of the Food Quality Protection Act in 1996, risk assessments for registration had to include the contribution of residues in drinking water to dietary assessments.  This triggered work modeling and monitoring work by both EPA and industry to determine satisfactory methods for estimating and measuring concentrations in drinking water from both ground and surface water.  This presentation reviews the developments in modeling and monitoring of drinking water from surface water over the past 15 years, including identification of the most sensitive drinking water intakes, SWMI, WARP, and the Index Reservoir as well as the evolution in surface water monitoring studies.  The results of the past research will be used to suggest potential approaches to obtaining appropriate estimates of drinking water based on either modeling or monitoring.

Notes:
The Food Quality Protection Act of 1996 required risk assessments for registration to include the contribution of residues in drinking water to dietary assessments.  This triggered modeling and monitoring activities by both EPA and industry to determine satisfactory methods for estimating and measuring concentrations in drinking water from both ground and surface water. The focus of this talk is on surface water assessments, which historically have been the driving exposure pathway for most drinking water risk assessments. Improvements made over the years include the addition of the index reservoir and percent crop area (PCA) factors in drinking water exposure assessments. The assessment methods have not changed significantly in the last 10 years. Often the predicted concentrations are much larger than monitored results, which "demonstrates the overly conservative nature of drinking water assessments."

Examples were given from aldicarb, bromoxynil, carbaryl, ethoprophos, oxadiazon, and iprodione exposure assessments, using OPP models versus monitoring observations in raw and finished drinking water samples. Usually model estimates were orders of magnitude greater than measured concentrations*. (EPA Comment: However, it is true that it is often easy to miss peak concentrations at a site by a significant factor with all but the most intense monitoring programs.) Current OPP models for rice and cranberries may be especially conservative. One major factor increasing the likelihood of overestimation of drinking water concentrations is that the highest use intensities are usually in small watersheds where the small streams are not directly used for drinking water. Regression models such as the Surface-Water Mobility Index (SWMI) and Watershed Regressions for Pesticides (WARP) have advanced our ability to predict moderate- and long-term exposure levels by identifying input factors responsible for most of the variability in observed data  -  with emphasis on model inputs that can be generated from commonly available data sources in the US. EPA was involved in the early development of WARP but was unable to continue supporting its development for drinking water assessments "due to non-technical reasons."

The accuracy of drinking water assessments can be improved greatly by obtaining data to refine inputs to better reflect real world exposure scenarios. A major area for refinement is in the area of use intensity where improved representation of percent crop area, percent crop treated, and typical application rates is needed; all have been used by OPP in cumulative risk assessments. Pesticide sales data is often a good surrogate source for refining usage inputs when direct localized usage information is not available. Acute exposure estimation from monitoring data can also be improved by techniques like the use of "bias factors."  One should try to determine whether the underestimation bias from insufficiently frequent sampling to capture peak exposure is as important as the overestimation from conservative assumptions in modeling. An example of this was illustrated from the carbaryl data.  The sampling schedule used for carbaryl should have been more than adequate to accurately determine the 70[th] and 90[th] percentile concentrations.  Since the modeling was overestimating these concentrations by 1-3 orders of magnitude, then one could not attribute the difference between the modeled and measured concentrations at higher percentiles, but only to missing the peaks.

* Examples of acute and annual mean exposure modeling estimates and targeted monitoring result ratios:
Aldicarb: 1.5 x to 30x
Bromoxynil: 35x
Carbaryl: 100x to 2000x
Ethoprophos: 100x to 1000x
Oxadiazon: 300x
Iprodione: 600x
3,5-DCA: 5000x
[Above were the ratios of model predicted acute concentrations to observed concentrations, chronic (annual mean) concentrations were also compared.]

4. Improved Characterization of the Temporal and Spatial Variability of Potential Surface Water Drinking Water Exposure by Using Environmental and Historic Monitoring Databases
   Paul Hendley[1], Wenlin Chen[1], Robert Joseph[1],  Ron Williams[1], Chris Harbourt[2] & Paul Miller[2]
   [1]Syngenta Crop Protection LLC, Greensboro, NC
   [2]Waterborne Environmental Inc., Champaign, IL

The extensive atrazine surface water monitoring database totals over 300,000 samples including ~120,000 drinking water samples from high frequency seasonal monitoring programs covering more than 15 years and >210 Community Water Systems (CWS). This wealth of frequent monitoring data sampled across a wide range of years and sites allows for robust conclusions to be drawn with very high statistical certainty regarding the highest centiles of potential atrazine exposures. To complement the monitoring data, site-specific details have also been accumulated on CWS watersheds, source waters and water handling procedures; this information has been used to better understand the expected temporal concentration patterns at individual CWS. We will outline how these and related data (e.g. daily flow and chemical monitoring data from Heidelberg University) have been used to examine approaches for optimizing sampling strategies for assessing potential drinking water concentrations in surface water. Scenarios with different sampling frequencies have been simulated and the results have been compared to measured data for each year and site. This talk will demonstrate how lower frequency monitoring data can be used to estimate potential maximum shorter duration concentrations.

Notes:
For larger sampling sizes (e.g.,> 7000), there is a greater confidence in capturing the highest centile concentration (99[th]%-tile) compared to smaller sampling sizes.

Two considerations/enhancements to the database for capturing peaks in monitoring (i.e., did you miss peaks?)
1) biased factors and error ratios
2) supplement monitoring data with model estimates (PRZM-hybrid)

Because the atrazine dataset is so large, it may be possible to apply conclusions from these studies to the general monitoring study design (e.g., baseline for using year-to-year variation).

Questions:
1) What is the effect and applicability of chemical specific biased factors? Can they be applied across chemicals?
- Potentially, but this would need some additional research.
2) How much data are available across water systems?
- 150 or greater water systems.

5. Estimating Upper Centile Pesticide Concentrations and Sample Size Requirement
Wenlin Chen[1], Paul Mosquin[2]
[1]Syngenta Crop Protection, LLC
 [2]RTI International

A survey sampling approach is presented for estimating upper centiles of aggregate distributions of surface water pesticide concentrations obtained from monitoring with large sample sizes but variable sampling frequency. It is applied to three atrazine monitoring programs of Community Water Systems (CWS) that used surface water as their drinking water source: 1. the nationwide Safe Drinking Water Act (SDWA) data, 2.the Syngenta Voluntary Monitoring Program (VMP), and 3. the Atrazine Monitoring Program (AMP). Requisite sample sizes are determined using statistical tolerance limits, relative standard error, and the Woodruff interval sample size criterion. These analyses provide 99.9% confidence that the existing data include the 99.9th centile atrazine concentration for CWS raw and finished water in the Midwest atrazine high-use areas and in the nationwide SDWA dataset, assuming no bias due to nonrandom selection of CWS and monitored days during these years. The general validity of these approaches is established by a simulation that shows estimates to be close to target quantities for weights based on sampling probabilities or time intervals between samples.

Notes:
Additional detail on the analysis is included in Mosquin et al., 2012 (JEQ publication)

There are two approaches to focus monitoring design (precision and sample size) on confidence in capturing upper centile concentration and relative standard error (Slides 12 and 13, respectively)

Question:
1) How is right-handed bias handled in Woodruff; how is it used? What is the Woodruff method?
-Woodruff is the skewness of a binomial approximation
-Enough samples as defined by Woodruff allow you to have good coverage at X-centiles, and at x-sample size.

6. Estimation of Upper Percentiles of Chlorpyrifos Surface Water Concentration from Yearly Monitoring Program Data
   Paul L. Mosquin[1], G. Gordon Brown[1], Roy W. Whitmore[1], Nick Poletika[2]
   [1]RTI International, Department of Statistics & Epidemiology, Research Triangle Park, NC, 27709, United States
   [2]Dow AgroSciences LLC, Department of Field Exposure and Effects, Indianapolis, IN, 46268, United States

This talk presents a finite population method to estimate annual 95[th], 99[th] and 99.9[th] centiles of surface water chlorpyrifos concentrations and associated confidence intervals using historical surface water pesticide monitoring programs with large number of measurements. The method provides reliable estimates, accounting for infrequent sample collection, measurements below reporting limits, and the strong seasonality present in these datasets. Data from three monitoring programs are considered: the USGS National Water-Quality Assessment Program (NAWQA), the Heidelberg University National Center for Water Quality Research (NCWQR) monitoring data, and the Washington State Department of Agriculture/ Department of Ecology surface water monitoring program. Results for temporal trends will be provided, including a comparison of estimates before and after chlorpyrifos was withdrawn from residential use in 2001.

Notes:
The authors discussed a finite population method to estimate annual 95[th], 99[th] and 99.9[th] centiles of chlorpyrifos concentrations in surface water and associated confidence intervals using historical surface water monitoring data from three different monitoring programs.  The three monitoring programs included: the USGS National Water-Quality Assessment Program (NAWQA), the Heidelberg, University National Center for Water Quality Research (NCWQR) monitoring data, and the Washington State Department of Agriculture/ Department of Ecology surface water monitoring program. In their talk, the authors presented a comparison of chlorpyrifos concentration estimates before and after the removal of residential chlorpyrifos uses as well as a comparison of chlorpyrifos concentrations in agricultural and urban watersheds.

The following issues were highlighted by the presenters:  1) the monitoring sampling is generally not from a probability design; 2) there are potentially only a few observations per year at a given site; 3) and non-detections are common.

The correlation of the monitoring datasets and actual chlorpyrifos use -- application timing, crops, etc. -- was not discussed.  Therefore, the representation of the annual 95[th], 99[th] and 99.9[th] centiles of chlorpyrifos concentrations in surface water was not clear.

7. Sampling Plans for Water Quality Assessment
   John W. Green, Ph.D.
   DuPont Applied Statistics Group

Sampling plans for monitoring chemical concentrations in rivers were investigated for two California streams of differing order to assess the relative merits of daily sampling versus less frequent sampling. The assessments were based on the ability to estimate time-weighted total and peak concentrations on a monthly or annual basis and to detect the presence of spikes in these concentrations. A secondary purpose was to determine the feasibility of predicting spikes in chemical concentrations from the river discharge rate. In these streams, some less frequent sampling plans were shown to provide almost the same utility as daily sampling for the first purpose and discharge rate was shown to have little correlation with chemical concentration.

Notes:
Sampling plans for monitoring chemical concentrations in rivers were investigated for two California Rivers (Orestimba Creek at River Road near Crows Landing and Sacramento River at I Street Bridge) to assess the merit of daily sampling versus less frequent sampling. The assessments were based on the ability to estimate time-weighted total and peak pesticide concentrations on a monthly or annual basis and to detect the presence of spikes in these concentrations. The feasibility of predicting spikes in chemical concentrations from the river discharge rate was also investigated. The presenter suggested that for these datasets, less frequent sampling plans provide almost the same utility as daily sampling and that pesticide concentrations did not correlate with the discharge rate.

8. Update on Development of Drinking Water Intake Watershed PCAs
   Jim Carleton, Rochelle Bohaty, Marietta Echeverria, Nelson Thurman, Michelle Thawley, Katrina White, Mohammed Ruhman
   Environmental Fate and Effects Division.  United States Environmental Protection Agency, Arlington, VA

EFED uses percent crop area (PCA) adjustment factors in its drinking water assessments to account for the fact that watersheds supplying surface drinking water sources may not be devoted entirely to agriculture.  The first PCAs were developed in the late 1990s and mid 2000s, based on cropped acreage within 8-digit HUCs.  More recently, EFED has developed delineations for watersheds associated specifically with drinking water intakes that supply community water systems.  EFED is planning to use this new dataset to develop drinking water intake watershed-specific PCAs.  This talk will discuss the intake watershed dataset and PCA development methodologies in general terms, along with unique issues and challenges associated with the use of these new data for PCA development.

Notes:
Drinking water intake (DWI) percent cropped area (PCA) adjustment factors are being developed to represent delineated watersheds with surface water intakes serving community water systems (CWS).  These PCAs use the same crop distribution data as other PCA projects (Ag Census and NLCD), but are based on the 4,840 DWI catchments judged "reasonable" by the USGS.  Some DWIs were not included because they are not associated with NHD+; however, surrogate PCAs can be used in these instances.  The catchments vary greatly in size (1/3 are less than 10 mi[2] and (1/4) are greater than 1,000 mi[2]).  These PCAs are limited by the resolutions of the datasets involved (AgCensus only provides data at the county level), and there is temporal variation in cropland data.  Also, there are concerns with releasing drinking water intake data as it relates to homeland security.  Next steps in this project are to develop draft PCAs, validate the GIS process, evaluate draft PCAs, finalize PCAs, and finalize the report and guidance document.

Q: Will drinking water intake PCAs replace HUC-derived PCAs?
A: This is a policy decision that will be made in the future.  However, a HUC PCA may be more appropriate in some cases as DWIs are not available for all localities.

Q: The analysis being done for DWI PCAs seems very similar to an approach currently underway for assessing endangered species.  Are these efforts duplicative?
A: These efforts are not the same as there are pixel value differences between the data sets being used and the land cover data is being used for very different purposes (e.g., proximity analysis versus percent of a watershed with a specified land cover).

Q: Is any work being done beyond GIS work to determine the appropriateness of including water storage reservoirs among the DWI PCA catchments?
A: No, only GIS analysis is being used to identify catchments.  EFED does not have the resources to individually verify all water storage reservoirs.

Q: Will a specific representative DWI catchment be identified as being protective and representative for specific crop(s)?
A: For the HUC PCAs, specific crops and regions are identified that address this issue; however, identifying crops and regions for DWI PCAs cannot be done easily as many of the catchments are nested within large catchments complicating which catchment is representative.

Q: What are the minor crops in consideration for crop specific PCAs?
A: The same groups as for HUC PCAs: all agriculture, corn, soybean, cotton, wheat, turf, orchard/vineyard, vegetable, and rice

Q: What is the measure of success for this project?
A: When verification, comparison to monitoring, comparison to old PCAs, and implementation for use in EFED is completed, the project will be considered a success.

Q: What is included in the turf layer?
A: The turf layer used to calculate the HUC8, HUC10, and HUC12 PCAs recently completed covers residential turf and sod farms.  There was uncertainty for that turf layer for sod farms as many acres of sod farms are not reported in Nationall Agricultural Statistis (NASS) data.  A new turf layer has been created that is specific to residential turf (e.g., did not account for sod farm turf) and that layer was used with the DWI-PCA calculation.  The all agricultural PCA is expected to be used for sod farms for PCAs completed in the future.

9. Exposure Assessment for Pronamide Drinking Water Residues in California Central Coast Lettuce Production Areas
   Nick Poletika[1], Brian Bret[2], Mike Winchell[3]
   [1]Dow AgroSciences LLC
   [2]Dow AgroSciences LLC, Regulatory and Government Affairs NAFTA
   [3]Stone Environmental, Inc.  Applied Information Management

Regulatory pesticide human exposure models are intentionally designed to be protective of individuals in populations.  Consequently, they tend to be quite conservative in early assessment tiers, and predictions are generally refined with data in subsequent assessments.  For drinking water obtained from surface water, pesticide exposure model concentration estimates for agricultural use generally are in the ug L[-1] to tens of ug L[-1] range, which can lead to concern if human health endpoints for a specific pesticide are low values.  Currently US EPA OPP accepts only targeted monitoring studies for refinement of model estimated concentrations.  We present an alternative assessment method to targeted monitoring for a pesticide with a limited range of label crops and geographic regions of use that relies on proximity analysis of use sites and drinking water intakes.  We also address national security issues related to sensitive intake location data and consider the general utility of the approach.

Notes:
Using the case study of pronamide on leaf lettuce in the central California coastal region, the presentation focused on an approach for evaluating drinking water exposure by examining public records and data sets to assess potential contamination of surface water sources.  By using historical surface water drinking water intake locations, SDWIS data, Internet resources (e.g., Google Earth), and discussions with community water system (CWS) employees, a dataset was compiled of active drinking water intakes.  The exposure potential for the active drinking water intake was assessed by using the ArcGIS tool NHDFlowline and use data from California's Pesticide Use Reports.  Sites were eliminated from future consideration if the pesticide was not used in the county, if there was no hydrologic connection (as determined by NHDFlowline), or if the intake was located upstream of the use sites.  One revelation of the research was that in the central California coast region a number of CWS receive raw water from remote sources, which tend to be in the elevated regions of the State, as opposed to the valley regions where lettuce is grown.  Based on the pronamide case study, of the 233 locations evaluated, none had the potential for pronamide contamination and exposure.  The recommendation was made that this approach could be extended to other regions of California, but that routine updates would need to be conducted to demonstrate that no exposure changes had occurred.  As drinking water intake locations are considered sensitive information, it was also recommended that EPA work with the USGS to more easily conduct this type of analysis in the future.

Q: Can this analysis be done for other crops, or is it  only applicable for lettuce?
A: Using the PUR data in general, this analysis  could be conducted  for other crops.

10. Hybrid PRZM:"Filling in the Gaps" in Field Sampling Data using Realistic Simulation Modeling
   Paul Miller, PhD[1], Chris Harbourt, PhD[1], William J. Northcott, PhD[1], Paul Hendley, PhD[2], and Jessie J. Prenger[1]
   [1]Waterborne Environmental, Inc.
[2]Syngenta

The Hybrid-PRZM approach can be used to combine observations from field monitoring with results from simulation modeling  based on local rainfall for the same period to "fill in" gaps between sampling occasions. The approach uses Pesticide Root Zone Model (PRZM) simulations based on local rainfall data together with site-specific watershed soil and agronomic characteristics. The model is used to estimate edge-of-field atrazine concentrations occurring on days with rainfall; the simulation results are scaled to watershed conditions without calibration. The PRZM model results supplement field monitoring data with estimates of potential runoff events on days when runoff inducing rain falls in a watershed between sampling occasions.  This technique captures the strengths of field and simulation approaches to develop conservative daily time series using quality sampling results and appropriate simulation assumptions.  Significant developments are presented here that result in improved exposure simulation results; these include the use of NEXRAD local precipitation data combined with a land workability algorithm to develop appropriate distributions of application dates across a watershed.

Notes:
The hybrid PRZM techniques for estimating peak concentrations / acute exposure levels in surface waters are being developed at Waterborne Environmental, Inc. in cooperation with Syngenta Crop Protection.
Why is this needed? There's a concern that monitoring programs may be missing peak concentrations, in some cases by quite a large margin.
The use of bias factors is one promising method for extrapolating from moderate-frequency monitoring data to conservative estimation of what the peak daily exposures might look like if higher frequency monitoring data were available for the pesticide of interest.
The author proposed a more "realistic" way of estimating high frequency data (i.e., acute exposure levels). The method utilizes regionally specific data for inputs into the PRZM modeling system to set up simulations that are calibrated (but with no "model specific" calibration required) with the available monitoring data to fill in the exposure distribution. This method has been applied to predict site and event specific concentrations of atrazine at the edge of field. The local information includes:
   * Nexrad rain temp solar data
   * Planting date, crop maturity
   * Soil characteristics
   * Cropland data layer,
   * Historical and current weather (Growing degree days, rainfall etc.)
   * Crop yield and soil moisture models
   * Etc.

Locally measured weather and pesticide application data are used. The watershed PCT (percent crop treated) calculations are based on Cropland Data Layer (CDL) land-use data from the NASS and grower survey data (local but not specific  -  see presentation authors for details). The atrazine example presented crop reporting district - based application rates.
SSURGO soils data is used for site-specific inputs on corn and sorghum in the example presented.
Algorithms have been developed to simulate farmer behavior and agronomic timing based on local conditions to give more realistic inputs on a daily basis. The method accounts for daily changes in land workability and distribution of practices over the watershed  -  there is a LOCAL response regarding whether land can be worked.  The reluctance of farmers to plant too early is accounted for.
The first planting date is determined from 14 day moving average of air temperature when 55 degrees and soil moisture is less than 0.85 and date is April 1 or later then planting is possible (for Midwest?)
Several adjustments to the inputs were made to improve the precision and accuracy of modeling of runoff events. The modeled window for potential applications was started 7 days prior to the accumulation of 630 GGD (growing degree days). If local variation is not considered, predictions are still acceptable.
Conclusions:
PRZM hybrid shows considerable promise for supplementing 7-day interval monitoring data.
The method predicts the relative magnitude of peaks but over predicts (the overall peak?) by >20 ppb- The method reflects reality in that peaks are predicted only during real runoff periods. The new land workability approach provided improved estimates of atrazine application timing.
The authors will be evaluating larger community water supply watersheds as well - the examples in this presentation were for watersheds of 10 to 1000 square miles that were part of the atrazine ecological monitoring program. Instead of a mechanistic approach, a WARP-type (USGS model) regression approach for larger watersheds may be used. Probabilistic approaches will also be investigated.