Endocrine Disruptor Screening Program; Chemical Selection Approach for Initial Round of Screening, 56449-56465 [05-19260]

Agencies

• ENVIRONMENTAL PROTECTION AGENCY

[Federal Register Volume 70, Number 186 (Tuesday, September 27, 2005)]
[Notices]
[Pages 56449-56465]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 05-19260]


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ENVIRONMENTAL PROTECTION AGENCY

[OPPT-2004-0109 FRL-7716-9]


Endocrine Disruptor Screening Program; Chemical Selection 
Approach for Initial Round of Screening

AGENCY: Environmental Protection Agency (EPA).

ACTION: Notice.

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SUMMARY: This notice describes the approach EPA plans to use for 
selecting the first group of chemicals to be screened in the Agency's 
Endocrine Disruptor Screening Program (EDSP). The Food Quality 
Protection Act of 1996 (FQPA) amended the Federal Food, Drug, and 
Cosmetic Act (FFDCA) to direct EPA to develop a chemical screening 
program using appropriate validated test systems and other 
scientifically relevant information to determine whether certain 
substances may have hormonal effects. In December 2002, EPA sought 
comment on its approach for selecting the initial list of chemicals for 
which testing will be required under the EDSP. Following review and 
revision based on the public comments, EPA is now describing the 
approach that it intends to use for selecting the chemicals for the 
initial list. For this initial approach, as recommended by scientific 
advisory committees, EPA will select 50 to 100 chemicals. The chemicals 
will be selected based on their relatively high potential for human 
exposure rather than using a combination of exposure- and effects-
related factors. The scope of this first group of chemicals to be 
tested includes pesticide active ingredients and High Production Volume 
(HPV) chemicals used as pesticide inerts. This will allow EPA to focus 
its initial screening efforts on a smaller and more manageable universe 
of chemicals that emphasizes the early attention to the pesticide 
chemicals that Congress specifically mandated EPA to test for possible 
endocrine effects. This notice does not identify the initial list of 
chemicals, nor does it describe other aspects of the EDSP such as the 
administrative procedures EPA will use to require testing, the 
validated tests and battery that will be included in the EDSP, or the 
timeframe for requiring the testing or receiving the data. The initial 
chemical list and the details of the EDSP process that will apply to 
the initial chemical list will be addressed in subsequent notices 
published in the Federal Register.

FOR FURTHER INFORMATION CONTACT: For general information contact: Colby 
Lintner, Regulatory Coordinator, Environmental Assistance Division 
(7408M), Office of Pollution Prevention and Toxics, Environmental 
Protection Agency, 1200 Pennsylvania Ave., NW., Washington, DC 20460-
0001; telephone number: (202) 554-1404; e-mail address: TSCA-
Hotline@epa.gov.
    For technical information contact: Mary Belefski, Office of Science 
Coordination and Policy (7201M), Environmental Protection Agency, 1200 
Pennsylvania Ave., NW., Washington, DC 20460-0001; telephone number: 
(202) 564-8461; e-mail address: belefski.mary@epa.gov.

SUPPLEMENTARY INFORMATION:

I. General Information

A. Does this Action Apply to Me?

    This action is directed to the public in general. This action may, 
however, be of interest if you produce, manufacture, use, consume, work 
with, or import pesticide chemicals, substances that may have an effect 
cumulative to an effect of a pesticide, or substances found in sources 
of drinking water. To determine whether you or your business may be 
affected by this action, you should carefully examine section 408(p) of 
FFDCA, 21 U.S.C. 346a(p), and the Safe Drinking Water Act (SDWA), 42

[[Page 56450]]

U.S.C. 300j-17. Since other entities may also be interested, the Agency 
has not attempted to describe all the specific entities that may be 
affected by this action. If you have any questions regarding the 
applicability of this action to a particular entity, consult the person 
listed under FOR FURTHER INFORMATION CONTACT.

B. How Can I Get Copies of this Document and Other Related Information?

    1. Docket. EPA has established an official public docket for this 
action under docket identification (ID) number OPPT-2004-0109. The 
official public docket consists of the documents specifically 
referenced in this action, including EPA's response to comments 
received and other information related to this action. In addition, 
documents are also in docket ID number OPPT-2002-0066 for the proposed 
approach. Although a part of the official docket, the public docket 
does not include Confidential Business Information (CBI) or other 
information whose disclosure is restricted by statute. The official 
public docket is the collection of materials that is available for 
public viewing at the EPA Docket Center, Rm. B102-Reading Room, EPA 
West, 1301 Constitution Ave., NW., Washington, DC. The EPA Docket 
Center is open from 8:30 a.m. to 4:30 p.m., Monday through Friday, 
excluding legal holidays. The EPA Docket Center Reading Room telephone 
number is (202) 566-1744 and the telephone number for the OPPT Docket, 
which is located in EPA Docket Center, is (202) 566-0280.
    2. Electronic access. You may access this Federal Register document 
electronically through the EPA Internet under the ``Federal Register'' 
listings at https://www.epa.gov/fedrgstr/.
    An electronic version of the public docket is available through 
EPA's electronic public docket and comment system, EPA Dockets. You may 
use EPA Dockets at https://www.epa.gov/edocket/ to view public comments, 
to access the index listing of the contents of the official public 
docket, and to access those documents in the public docket that are 
available electronically. Although not all docket materials may be 
available electronically, you may still access any of the publicly 
available docket materials through the docket facility identified in 
Unit I.B.1. Once in the system, select ``search,'' then key in the 
appropriate docket ID number.
    Certain types of information will not be placed in the EPA Dockets. 
Information claimed as CBI and other information whose disclosure is 
restricted by statute, which is not included in the official public 
docket, will not be available for public viewing in EPA's electronic 
public docket. EPA's policy is that copyrighted material will not be 
placed in EPA's electronic public docket but will be available only in 
printed, paper form in the official public docket. To the extent 
feasible, publicly available docket materials will be made available in 
EPA's electronic public docket. When a document is selected from the 
index list in EPA Dockets, the system will identify whether the 
document is available for viewing in EPA's electronic public docket. 
Although not all docket materials may be available electronically, you 
may still access any of the publicly available docket materials through 
the docket facility identified in Unit I.B.1. EPA intends to work 
towards providing electronic access to all of the publicly available 
docket materials through EPA's electronic public docket.

II. Introduction

A. What Action is the Agency Taking?

    Following review of public comments received in response to the 
Federal Register notice of December 30, 2002 (67 FR 79611) (FRL-7286-
6), EPA is describing the approach it plans to use for selecting an 
initial group of chemicals to be screened in the Agency's EDSP. This 
notice does not identify the initial list of chemicals, nor does it 
describe other aspects of the EDSP such as the administrative 
procedures EPA will use to require testing, the validated tests and 
battery that will be included in the EDSP, or the timeframe for 
requiring the testing or receiving the data. The initial chemical list 
and the details of the EDSP process that will apply to the initial 
chemical list will be addressed in subsequent notices published in the 
Federal Register.
    EPA anticipates that it may modify its chemical selection approach 
for subsequent screening based on experience gained from the results of 
testing chemicals on the initial list, its needs to extend screening to 
additional categories of chemicals (e.g., non-pesticide substances) and 
additional pathways of exposure, and the availability of new priority-
setting tools (e.g., High Throughput Pre-Screening (HTPS) or 
Quantitative Structure Activity Relationship (QSAR) models).
    EPA developed its EDSP in response to the Congressional mandate in 
section 408(p) of FFDCA to ``develop a screening program * * * to 
determine whether certain substances may have an effect in humans that 
is similar to an effect produced by a naturally occurring estrogen, or 
such other endocrine effects as [EPA] may designate'' (21 U.S.C. 
346a(p)). When carrying out the program, the statute requires EPA to 
``provide for the testing of all pesticide chemicals.'' The statute 
also provides EPA with discretionary authority to ``provide for the 
testing of any other substance that may have an effect that is 
cumulative to an effect of a pesticide chemical if the Administrator 
determines that a substantial population may be exposed to such a 
substance.'' In addition, section 1457 of SDWA provides EPA with 
discretionary authority to provide for testing, under the FFDCA 408(p) 
screening program, ``of any other substances that may be found in 
sources of drinking water if the Administrator determines that a 
substantial population may be exposed to such substance.''
    The purpose of this notice is to describe the approach that EPA 
plans to use to select this initial set of chemicals to undergo 
screening. EPA will use an approach based in part on the compartment-
based priority-setting approach described in the Federal Register 
notices of December 28, 1998 (63 FR 71542) (FRL-6052-9) and December 
30, 2002. This approach focuses on human exposure-related factors 
rather than using a combination of exposure- and effects-related 
factors. However, in making selections for this exposure-based initial 
list, EPA does not plan to select substances it considers to be a low 
priority for early screening under the EDSP because they are 
anticipated to have low potential to cause endocrine disruption (e.g., 
certain Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) 
List 4 inerts, most polymers with number average molecular weight 
greater than 1,000 daltons, strong mineral acids, and strong mineral 
bases). Also, chemicals that are being used by EPA as ``positive 
controls'' to validate the screening assays will be excluded from its 
initial list.
    Although EPA's general focus in this approach for the initial list 
is on pesticide active ingredients and inerts with relatively greater 
potential human exposure, EPA believes that the approach will also 
identify chemicals with high potential for exposure of humans from non-
pesticide uses or chemicals with widespread environmental exposures to 
other organisms. EPA does not intend to develop an ordinal ranking of 
priorities of the chemicals within any list developed using this 
approach.
    The Agency will use the approach set forth in this notice to select 
the initial list of chemicals to test first under the

[[Page 56451]]

EDSP based primarily on exposure data. Therefore, this initial list of 
chemicals should not be construed as a list of known or likely 
endocrine disruptors nor characterized as such. Nothing in the approach 
for selecting the initial list would provide a basis to infer that any 
of the chemicals selected for the list interferes with or is suspected 
to interfere with the endocrine systems of humans or other species.
    In subsequent notices published in the Federal Register, EPA 
intends to issue the draft initial list of chemicals resulting from the 
implementation of this approach, and to describe the other aspects of 
the EDSP, including the procedures it will use to require the testing 
and the timeframe for the initial screening. EPA intends to provide 
time for review and comment on the draft initial list prior to the 
Agency's imposition of actual screening of the initial chemicals.

B. What is the Agency's Authority for Taking this Action?

    Section 408(p) of FFDCA requires EPA ``to develop a screening 
program to determine whether certain substances may have an effect in 
humans that is similar to an effect produced by a naturally occurring 
estrogen, or such other endocrine effect as [EPA] may designate.'' 
(FFDCA 21 U.S.C. 346a(p)). The statute generally requires EPA to 
``provide for the testing of all pesticide chemicals.'' (FFDCA 21 
U.S.C. 346a(p)(3)). However, EPA is authorized to exempt a chemical, by 
order upon a determination that ``the substance is anticipated not to 
produce any effect in humans similar to an effect produced by a 
naturally occurring estrogen.'' (FFDCA 21 U.S.C. 346a(p)(4)). 
``Pesticide chemical'' is defined as ``any substance that is a 
pesticide within the meaning of the Federal Insecticide, Fungicide, and 
Rodenticide Act, including all active and inert ingredients of such 
pesticide.'' (FFDCA section 201(q)(1) (21 U.S.C. 231(q)(1))).

III. Background

A. EPA's Endocrine Disruptor Screening Program (EDSP)

    EPA initially set forth the EDSP in the August 11,1998 Federal 
Register notice (63 FR 42852) (FRL-6021-3) and solicited public comment 
on the program in the December 28, 1998 Federal Register notice. The 
program set forth in these notices was based on the recommendations of 
the Endocrine Disruptor Screening and Testing Advisory Committee 
(EDSTAC), which was chartered under the Federal Advisory Committee Act 
(FACA), 5 U.S.C. App.2, section 9(c). The EDSTAC was comprised of 
members representing the commercial chemical and pesticides industries, 
Federal and State agencies, worker protection and labor organizations, 
environmental and public health groups, and research scientists. EPA 
charged EDSTAC to advise the Agency regarding:
    1. Methods for chemical selection and setting priorities for 
screening.
    2. A set of available, validated screening assays for early 
application.
    3. Ways to identify new and existing screening assays and 
mechanisms for their validation.
    4. Processes and criteria for deciding when additional tests beyond 
screening would be needed and how to validate such tests.
    5. Processes for communicating to the public about EDSTAC's 
agreements, recommendations, and information developed during priority 
setting, screening, and testing.
    In response to this charge, EDSTAC recommended that EPA's program 
address both potential human and ecological effects; examine effects on 
estrogen, androgen, and thyroid hormone-related processes; and include 
non-pesticide chemicals, contaminants, and mixtures in addition to 
pesticides (Ref. 1). Based on these recommendations, EPA developed a 
tiered approach for their program (referred to as the EDSP). The core 
elements of EDSP are: Priority setting, Tier 1 screening, and Tier 2 
testing. Tier 1 is envisioned as a battery of screening assays 
(referred to as ``screening'') that would identify substances that have 
the potential to interact with the estrogen, androgen, or thyroid 
hormone systems. The purpose of Tier 2 testing (referred to as 
``testing'') is to determine whether the substance could, in fact, 
cause endocrine effects mediated by estrogen-, androgen-, or thyroid-
related processes, and to establish the relationship between doses of 
an endocrine-active substance administered in the test and any effects 
observed.
    In addition, based on EDSTAC's recommendations, EPA proposed in the 
December 28, 1998 Federal Register notice an approach to establish the 
priority of chemicals for Tier 1 screening. The approach reflected the 
concern that the quantity and quality of exposure and effects 
information would be uneven across chemicals. EPA wanted to ensure that 
data-rich and data-poor chemicals were not directly compared in the 
priority-setting process because data-poor chemicals might tend to be 
ranked low under such an approach. Thus, EPA proposed to develop 
categories of information relating to the production, release, 
exposure, and hazard of chemicals and to group the chemicals according 
to the available data. This approach was termed a ``compartment-based 
approach.'' The compartment-based approach was based on exposure- and 
effects-related compartments even though it was recognized that effects 
or toxicity data relevant to endocrine disruption would be extremely 
limited for the majority of chemicals. To partly compensate for the 
lack of relevant toxicity data, EPA proposed to conduct a HTPS study 
addressing all chemicals with a production volume in excess of 10,000 
pounds per year, excluding pesticide active ingredients. EPA developed 
the Endocrine Disruptor Priority Setting Database (EDPSD) to assist in 
assigning chemicals to compartments and setting priorities. More 
information on the EDPSD is available at https://www.epa.gov/scipoly/
oscpendo/prioritysetting.
    EPA currently is implementing its EDSP in three major parts. The 
Agency is:
    1. Developing and validating the screening level assays, selecting 
the appropriate screening assays for the screening battery based on the 
validation data, and developing and validating Tier 2 tests.
    2. Finalizing the priority-setting chemical selection approach to 
be applied to select an initial list of chemicals to go through 
screening.
    3. Developing the procedures the Agency will use to require 
screening.
    This notice deals only with finalizing the priority-setting 
chemical selection approach to be applied to select an initial list of 
chemicals to go through screening. As indicated, EPA intends to address 
the other aspects of the EDSP in subsequent notices published in the 
Federal Register.

B. Science Advisory Board/FIFRA Scientific Advisory Panel Review

    EPA asked its Science Advisory Board (SAB) and the FIFRA Scientific 
Advisory Panel (SAP), independent scientific review committees of non-
EPA scientists, to review jointly the Agency's proposed EDSP. The 
Agency's charge to the SAB/SAP Subcommittee was broad and complex 
consisting of 18 questions in four broad areas:
    1. Scope of the program.
    2. Priority setting.
    3. HTPS.
    4. Screening and testing.
    The SAB/SAP Subcommittee met on March 30-April 1, 1999. Its report 
was published the following July (Ref. 2). In general, the SAB/SAP 
Subcommittee

[[Page 56452]]

agreed with the program that EPA had developed for conducting endocrine 
disruptor screening. The following are recommendations from the SAB/SAP 
Subcommittee with respect to the scope of the program and setting of 
priorities for screening.
    In the December 28, 1998 Federal Register notice, EPA explained 
that it was considering 87,000 substances as potential candidates for 
testing under EDSP. The SAP/SAB Subcommittee expressed some 
reservations about the ambitious scope of the universe of chemicals 
that EPA envisioned as potentially being included in the program. The 
SAP/SAB Subcommittee felt that developing massive amounts of screening 
data on a large universe of chemicals would not necessarily expedite 
the development of the appropriate underpinning that the Agency needs 
before it proceeds with the screening of the large universe of 
chemicals that it anticipates will be included in EDSP. The SAB/SAP 
Subcommittee also expressed concern that it did not see a provision for 
mid-course correction or optimization of the program. Thus, the SAB/SAP 
Subcommittee recommended that the EPA start by applying EDSP to 50 to 
100 compounds and submit the data to independent review to consider 
eliminating methods that do not work, and also evaluate how to optimize 
the program.
    The SAB/SAP Subcommittee also recommended against including 
mixtures in the initial set of chemicals to be tested. The SAB/SAP 
Subcommittee thought that the question of testing mixtures should be 
deferred until single-compound methods had been successfully 
demonstrated.
    The SAB/SAP Subcommittee also found that the compartment-based 
approach to priority setting was supportable when ranking is based on 
both effect and exposure data. It suggested that the greatest weight 
should be given to chemicals for which there are data that indicate 
actual human or environmental exposure and effects. Lower weight should 
be given to chemicals for which the data are indicative of probable 
exposure (in food or drinking water) or probable effects (from animal 
studies). The lowest weight and priority should be given to chemicals 
for which the data are indicative of possible exposure (based on 
release or production volume) or possible effects (from in vitro or 
HTPS assays). The SAB/SAP Subcommittee expressed concern that the lack 
of effects data on the universe of chemicals currently in commercial 
use would lead to a database that only identifies known problem 
chemicals that are already well studied. To overcome this obstacle, the 
SAB/SAP Subcommittee encouraged the development of new techniques 
including QSAR and molecular modeling to help identify the bio-
available, potentially active compounds for further testing in EDSP. 
The SAB/SAP Subcommittee supported the concept of nominations by 
citizens, but recommended that the process needed further definition.
    Finally, the SAB/SAP Subcommittee agreed with EPA's assessment that 
the HTPS system, which EPA subjected to a demonstration project, was 
not ready for use but that the concept was still valuable. The SAB/SAP 
Subcommittee encouraged EPA to be open to other types of assays for 
HTPS including receptor binding, gene chip and microarrays, and 
computer modeling. The SAB/SAP Subcommittee also gave some guidance 
regarding further development and employment of HTPS, including the 
need for standardization and validation of any system to be used in 
priority setting.

C. Public Comments on Priority Setting

    In addition to comments provided by the SAB/SAP Subcommittee, 
comments were also provided by the public on priority setting in 
response to EPA's EDSP Proposed Statement of Policy notice published in 
the December 28, 1998 Federal Register, at two public meetings held on 
the Endocrine Disruptor Priority Setting Database (EDPSD), and from the 
request for comment on the proposed approach in the December 30, 2002 
Federal Register notice. The January 20, 1999 meeting was published in 
the Federal Register of December 28, 1998 (63 FR 71568) (FRL-6052-8) 
and the June 5-6, 2000 meeting was published in the Federal Register of 
May 19, 2000 (65 FR 31900) (FRL-6559-9). All of these comments were 
helpful to the Agency in developing the approach presented in this 
notice for selecting the initial list of chemicals to be screened in 
EDSP.

IV. Summary of Comments Received on EPA's Proposed Approach to 
Selecting the Initial Set of Chemicals

    After reviewing all of the comments received, EPA has decided to 
make some changes to the proposed approach. The priority-setting issues 
raised in the most recent comments on the proposed approach are 
addressed in the Comment Response Document for Endocrine Disruptor 
Chemical Selection/Priority Setting (Ref. 3), which can be found in the 
public docket. This unit addresses the major comments that caused EPA 
to revise its proposed approach.

A. Use of Effects Data for Chemical Selection

    In the proposed chemical selection approach in the December 30, 
2002 Federal Register notice, EPA stated that, prior to publishing the 
draft initial list of chemicals for screening, the Agency intended to 
review the available effects information for those candidate chemicals 
identified using the exposure-based approach, in order to identify any 
chemical for which the effects information either clearly indicates an 
endocrine-mediated effect/perturbation or clearly indicates low 
potential to cause endocrine disruption. Such chemicals would then be 
excluded from the initial list. Most commenters urged EPA to utilize 
existing effects data to the greatest extent that is scientifically 
justifiable, and emphasized that an exposure-based approach should only 
be used, if at all, for the initial list.
    Following review of the comments and further evaluation of the 
proposed approach, EPA has decided for the initial list to limit its 
review of effects data and primarily select chemical candidates based 
on exposure. With two exceptions where EPA believes that it has 
sufficient information of an appropriate quality, EPA generally 
believes that it lacks sufficient information and experience to 
determine whether a chemical should be designated as a ``potential 
endocrine disruptor.'' As a general matter, EPA will therefore not 
exclude chemicals from the initial list based on a finding of the 
chemical's endocrine disruption potential.
    Generally, with respect to using additional existing effects data, 
given the current state of scientific understanding of endocrine system 
effects and the types of testing currently available for most pesticide 
chemicals, EPA has decided for this initial list that it would be 
impractical to establish criteria for judging whether a chemical should 
be designated as a ``potential endocrine disruptor'' and removed from 
the initial group for screening. Although a relatively broad range of 
toxicity data are available for pesticide active ingredients regulated 
under FIFRA, in most cases EPA has not yet established how the 
available data might be confidently used to predict the endocrine 
disruption potentials of these chemicals. This may be due to the non-
specific nature of an effect or effects observed, questions related to 
whether the mode of action in producing a given effect or effects is or 
are endocrine system-mediated in whole or in part, or the lack of 
relevant data to make a judgement altogether. When the draft

[[Page 56453]]

initial list is published, any company subject to a testing requirement 
may request, during the comment period, a waiver (supported by 
appropriate data) on the grounds that the chemical is an endocrine 
disruptor and that EDSP screening is unnecessary.
    EPA has identified two exceptions. First, chemicals that are being 
used by EPA as ``positive controls'' to validate the screening assays 
will be excluded from its initial list. Inclusion of these chemicals in 
the initial list would be to require companies to generate duplicative 
data unnecessarily. These chemicals were selected because they were 
expected to elicit positive responses in the assays proposed to 
identify estrogen-, androgen-, and/or thyroid-system disruptors. 
Second, EPA does not plan to select substances it anticipates as having 
low potential to cause endocrine disruption (e.g., certain FIFRA List 4 
inerts, most polymers with number average molecular weight greater than 
1,000 daltons, strong mineral acids, and strong mineral bases), and 
considers these substances to be a low priority for early screening 
under the EDSP. High molecular weight substances are unlikely to reach 
molecular receptors or other target tissue; highly reactive chemicals 
will destroy tissue at the point of entry leading to toxicity other 
than through the endocrine system.

B. Appropriateness of the Proposed Data Sources

    Many comments received on the appropriateness of the data sources 
identified in the December 30, 2002 Federal Register notice questioned 
the relevance and quality of the proposed data sources. Specific issues 
raised in these comments included: The inability to analyze and fully 
understand the data in some data sources because the raw data 
underlying the summary data are not accessible; several databases are 
very dated and may not be relevant to potential exposures today; 
several databases may not be relevant to or extrapolated to the U.S. 
population as a whole; some databases/data sources used biased sampling 
rather than random or probability design; although the data do indicate 
exposure, they do not fully characterize exposure in terms of time, 
duration, and level of exposure; and that the EPA review of the 
databases should comply with the Agency's policies provided in its 
December 2002 information quality guidelines (Ref. 4).
    In accordance with EPA's information quality guidelines, EPA has 
reviewed the data sources described in this chemical selection approach 
for the initial round of screening in the EDSP. Following review of the 
proposed databases (Ref. 5), EPA made the determination to exclude the 
Heidelberg College's Monitoring Data at this time because it has 
limited public availability, at best, and because comparable data are 
available from two other sources that are publicly available. For the 
remainder of the data sources, EPA believes that the data sources are 
appropriate and relevant for the intended application and that the 
quality and transparency of the information is sufficient for the 
intended use. The most current versions of the databases will be used 
and evaluated when developing the initial list.
    EPA acknowledges that many of the proposed data sources may be 
limited in their usefulness for certain applications but believes, 
nonetheless, that the data sources are of appropriate quality for their 
intended use and purpose for a number of reasons. First, the most 
current versions of the databases will be used and evaluated when 
developing the initial list. In addition, the limitations of an 
individual data set can be overcome, to some extent, by consideration 
of multiple sets of data and multiple databases. EPA thinks that, when 
considered collectively, the databases discussed in Units VI. and VII. 
are not as vulnerable to criticism as a particular individual data set. 
Finally, EPA generally determines the quality of data sources based on 
the Agency's intended use of the data. For the initial list, EPA will 
select 50 to 100 pesticide active ingredients and HPV chemicals used as 
pesticide inerts to which the public may be more highly exposed. EPA 
will use these data sources to help select just the first round of 
chemicals to be screened and does not intend to use these sources to 
create a definitive, scientifically rigorous list of chemicals with a 
high potential for exposure, nor to develop quantitative exposure 
estimates in this analysis. The chemicals identified under this 
approach belong to the group of chemicals that are required to be 
tested under FFDCA section 408(p)(3)(A)--pesticide chemicals. Because 
Congress specifically required that these chemicals be tested, the 
impact of EPA's assessments in this case is quite limited--merely 
determining the timing of the testing, rather than whether the testing 
is to be conducted. Consequently, EPA believes the proposed data 
sources are of sufficient quality for their intended use.

C. Synchronization of the Endocrine Disruptor Screening Program's 
Components

    In response to comments and consistent with its intent to have the 
initial list drafted and finalized when the screening assays are 
available for testing, EPA plans on publishing the draft initial 
chemical list well in advance of when an appropriate screening test 
battery is ready for use. This interval is intended to allow adequate 
time for EPA to solicit and consider public comments on the draft list 
without delaying the initial round of testing.

V. EPA's Approach to Selecting the Initial Set of Chemicals to Undergo 
Screening

    On the basis of EPA's experience to date and comments received, EPA 
is setting forth its approach for selecting the first group of 
chemicals to be screened in the EDSP. Based on the SAB/SAP Subcommittee 
recommendations and public comments, EPA will select and screen 
approximately 50 to 100 chemicals drawn from pesticide active 
ingredients and pesticide inerts with relatively large overall 
production volumes considering both pesticide and non-pesticide uses 
(HPV/Inert chemicals) to help the Agency further refine the EDSP. EPA 
will list the chemicals alphabetically, or numerically by CAS number, 
to avoid the appearance of a specific ranking of the chemicals selected 
for initial screening.
    As recommended by the SAP/SAB Subcommittee, the Agency intends to 
conduct a review of the data received from the screening to evaluate 
whether the program could be improved or optimized, and if so, how. In 
addition to Agency scientists, the review of the initial list screening 
results will be evaluated by an expert panel such as one under the SAP/
SAB Subcommittee. Evaluation of the screening results for the initial 
50 to 100 chemicals will add substantially to our understanding of the 
performance of the Tier I test battery. Thus, the evaluation may 
identify methodological issues encountered when this larger set of 
chemicals are tested by laboratories not involved in the assay 
validation effort that may lead to further optimization of the assays 
to improve performance. The evaluation may also identify interpretive 
issues such as a determination that a specific assay may not be needed 
because another assay in the screening battery adequately measures the 
same effect. Other information from the review process

[[Page 56454]]

may help identify potential issues or areas for improvement, such as 
whether there is sufficient laboratory capacity or problems with 
correctly performing the tests, whether there are issues with the 
industry's ability to test the identified chemicals, or whether there 
are any procedural changes that would improve the overall program.
    EPA will use an approach based in part on the compartment-based 
priority-setting approach described in the December 28, 1998 Federal 
Register notice that provided details about the EDSP and that the SAB/
SAP Subcommittee commented on in 1999. As explained in Unit IV.A., the 
approach focuses primarily on exposure-related factors rather than 
using a combination of exposure- and effects-related factors. Although 
EPA will use many of the exposure data sets previously identified for 
use in the EDPSD in this approach, EPA anticipates not directly using 
the EDPSD itself at this time in light of the narrower scope and focus 
of this initial list. EPA anticipates that it will modify its chemical 
selection approach for subsequent screening lists based on experience 
gained from the results of testing chemicals on the initial list, the 
feasibility of incorporating different categories of chemicals (e.g., 
non-pesticide substances), and the availability of new priority-setting 
tools (e.g., HTPS and QSAR models).
    EPA will use several groups of data to identify pesticide active 
ingredients to include on the initial list of chemicals for screening. 
These data focus on human exposure by different pathways:
    1. As a consequence of consuming food containing pesticide 
residues.
    2. As a consequence of consuming drinking water containing 
pesticide residues.
    3. As a consequence of residential use of pesticide products.
    4. Through occupational contact with pesticide-treated surfaces.
    For each of the four pathways, EPA will use the most current data 
available from each data source to identify active ingredients. To 
ensure, to the extent possible, that all pesticide chemicals are 
addressed using this approach based on comparable exposure potential, 
EPA is most interested in identifying and selecting data sources which 
provide occurrence/usage data on a broad range of pesticide chemicals 
and across a wide geographical scope. Although the final selected data 
sources do have limitations, EPA is confident that these data sources 
can be used to identify pesticide active ingredients likely to be among 
those having either potentially widespread or higher levels of human 
exposure than would be expected for other active ingredients. EPA does 
not plan to use these data sources to create a definitive, 
scientifically rigorous list of pesticide chemicals to which the public 
is the most highly exposed. Nor is EPA proposing to use these databases 
to create quantitative exposure estimates in this analysis.
    EPA is giving higher priority to chemicals likely to have human 
exposure via multiple pathways, with the highest priority being given 
to substances having potential exposure through all four pathways, 
followed by those having potential exposure via three pathways, etc. 
for inclusion on the list for initial screening. Details on EPA's 
approach for selecting pesticide active ingredients are presented in 
Unit VI.
    EPA will use a similar approach to identify HPV/Inert chemicals to 
be included in the initial list for screening in the screening battery. 
However, EPA generally has more extensive information available to 
assess potential exposure to pesticide active ingredients via food, 
water, occupational, and residential exposure pathways than is 
available to assess exposure to HPV/Inert chemicals. In addition, EPA 
generally has more extensive information available on usage (including 
both agricultural and residential) of active ingredients than is 
available for HPV/Inert chemicals (including both pesticidal and non-
pesticidal uses of those same substances). For these reasons, the 
specific pathways and data sources EPA has identified for selecting an 
initial set of HPV/Inert chemicals for endocrine disruptor screening 
differ somewhat from those for selecting pesticide active ingredients.
    For HPV/Inert chemicals, EPA will focus on several indicators of 
the potential for human exposure, including production volume, specific 
pathways of exposure, and presence in human tissues. First, EPA will 
use the most current databases available to identify chemicals that are 
both pesticide inerts and HPV (defined as chemicals that are 
manufactured or imported into the United States for all uses in amounts 
equal to or greater than one million pounds per year) chemicals. This 
first step will focus initial screening of pesticide inerts on 
chemicals with higher potential human exposure on the basis of large 
amounts produced or imported each year in the United States. Second, 
EPA will review the most current existing data available for its use to 
identify HPV/Inert chemicals that have been found to be present in: 
Human biological samples, ecological tissues that have human food uses 
(i.e., fish tissues), drinking water, and/or indoor air. Using this 
approach, an HPV/Inert chemical appearing in monitoring data from one 
or more of these media, would be a higher priority for testing than an 
HPV/Inert chemical that does not appear in monitoring data from any of 
the media. Details on EPA's priority-setting approach for selecting 
HPV/Inert chemicals are presented in Unit VII.
    While EPA's general focus in this approach is on pesticide active 
ingredients and HPV/Inert chemicals with relatively greater potential 
human exposure, this does not necessarily mean that the list developed 
using this approach will not contain substances which also have 
potentially high levels of environmental exposure to ecological 
receptors. As explained in Units VI. and VII., EPA believes that the 
approach to select an initial list of pesticide active ingredients and 
HPV/Inert chemicals for screening, while focused on human exposure, 
will also capture many chemicals to which other organisms have 
potential for widespread environmental exposures. In addition, because 
the screening battery will likely include assays involving different 
species (e.g., amphibians and fish) whose results are relevant to both 
humans and wildlife, EPA will capture information relevant to 
ecological protection.
    The approach is consistent with the proposed approach and many of 
the comments received on the December 30, 2002 Federal Register notice. 
For its approach EPA is:
    1. Focusing chemical selection for this initial list on the subset 
of chemicals for which testing is required (i.e., pesticide chemicals).
    2. Using exposure data as the primary basis for chemical selection 
rather than using HTPS, QSARs, or other hazard data in conjunction with 
exposure data.
    3. Excluding substances for the initial list anticipated to have 
low potential to cause endocrine disruption (e.g., certain FIFRA List 4 
inerts, most polymers with number average molecular weight greater than 
1,000 daltons, strong mineral acids, and strong mineral bases).
    4. Deferring consideration of nominations from the public.
    5. Not including mixtures for the initial list.
    6. Excluding chemicals that are no longer produced or used in the 
United States.
    7. Excluding ``positive control'' chemicals used for the validation 
of the screening assays.

[[Page 56455]]

    EPA will issue an additional Federal Register notice setting forth 
the draft initial list of chemicals it proposes for screening. EPA 
expects that low-priority designations will initially be made on a 
case-by-case basis. Therefore, the Federal Register notice in which EPA 
will publish for public comment the draft initial list of chemicals for 
screening will clearly identify any chemical, which was identified 
having priority for testing through the application of the exposure-
based criteria, but was excluded because it is considered to be a low 
priority for one of the reasons listed in this unit. That Federal 
Register notice will explain the rationale underlying any decisions 
made for selection of chemicals in the draft initial list. The draft 
initial list of chemicals is expected to be published to allow 
sufficient time for review and comment prior to actual testing. After 
considering comment on the draft list of chemicals, EPA will issue the 
initial list of chemicals for which screening will be required.

VI. Approach for Selecting Pesticide Active Ingredients

    As proposed, EPA will use several criteria to identify pesticide 
active ingredients for the initial round of the screening. These 
criteria would focus on human exposure by different pathways: As a 
consequence of consuming food containing pesticide residues, drinking 
water containing pesticide residues, and residential use of pesticide 
products; and through occupational contact with pesticide-treated 
surfaces. For each of the four pathways, EPA will review the most 
current existing databases available to identify active ingredients 
generally expected to be among those having either widespread or high 
levels of human exposure.
    While EPA's general focus is on pesticide active ingredients with 
relatively greater potential human exposure, this focus does not 
necessarily mean that the list of active ingredients will not contain 
substances which also have potentially high levels of environmental 
exposure to ecological receptors. Many of the pesticide active 
ingredients having greater potential for human exposure will also have 
greater potential for exposure to wildlife. For example, one pathway of 
human exposure, drinking water, is also a pathway through which aquatic 
life and many terrestrial species are exposed. Most of the databases 
that EPA will consider in evaluating active ingredients for exposure 
through drinking water contain monitoring data collected on raw surface 
water (i.e., before the water enters a public water system). Thus, 
these monitoring data show the levels of pesticide residues that fish, 
amphibians, and other aquatic species will encounter. Similarly, when 
data show higher and more widely distributed levels of pesticide 
residues in food, EPA thinks that such residues generally tend to 
reflect greater usage and/or persistence of the pesticide on crops and 
thus, greater environmental loads. Accordingly, EPA believes that the 
approach to evaluate pesticide active ingredients, while focused on 
human exposure, will also capture many active ingredients with 
widespread environmental exposures.

A. Food Pathway

    Every person eats food and a significant portion of food contains 
some amount of pesticide residues, although usually at very low levels. 
Therefore, pesticide residues in food have the potential to cause 
widespread human exposure. Pesticides have different use patterns and 
have different physical and chemical properties that affect how they 
move in the environment and how quickly they break down. As a result, 
there are often significant differences among pesticides in the 
proportion of food containing residues and in the levels of such 
residues. People also consume different amounts of different foods. All 
of these factors mean that people ingest greater quantities of some 
pesticide active ingredients than others.
    To evaluate the interplay of these different variables, EPA will 
identify the pesticide active ingredients which are found most 
frequently as residues on the top 20 foods that people consume. First, 
EPA will use the most recent Continuing Survey of Food Intake by 
Individuals (CSFII) to determine the mean amount of each raw 
agricultural commodity consumed in the general population. The CSFII is 
a database derived from a survey performed by the U.S. Department of 
Agriculture (USDA) in 1994-1996 and supplemented with additional survey 
responses collected in 1998. USDA collected food diary information from 
over 20,000 individuals who were interviewed on 2 non-consecutive days, 
generally spaced 3 to 10 days apart. After appropriate statistical 
weighting, the survey, in the aggregate, is representative of the U.S. 
population in terms of age, gender, major ethnic groups, and socio-
economic status. Moreover, sampling was representative of different 
days of the week, seasons of the year, and parts of the country. 
Extensive quality control procedures assured that the data collected in 
the survey were accurate and reliable. More information on USDA's food 
surveys and the CSFII (1994-1996) is available at https://
www.barc.usda.gov/bhnrc/foodsurvey.
    Using standard, scientifically peer-reviewed recipes, EPA has 
converted the reported food consumption for each CSFII survey 
respondent into the constituent raw agricultural commodities. For 
example, if a person reported eating six ounces of beef stew, EPA 
estimated the amount of beef, carrot, potato, and each other raw 
agricultural commodity used in making that quantity of beef stew. EPA 
made similar conversions for each of the different finished foods 
reported in the CSFII--from apple pie to yogurt. EPA then estimated the 
total amount of each of the various raw agricultural commodities eaten 
over the course of the day, for example summing the amount of apple 
consumed from drinking cider and eating apple sauce. The results of 
these recipe translations appears in the revised Food Commodity Intake 
Database (FCID) (Ref. 6). Information on the FCID can be reviewed at 
https://www.barc.usda.gov/bhnrc/foodsurvey/fcid.html. This individual 
food consumption database provides the basis for identifying the top 20 
foods consumed, in terms of mean daily consumption for the general 
population. Table 1 of this unit presents these raw agricultural 
commodities.


                       Table 1.--Top Twenty Foods
------------------------------------------------------------------------
 
------------------------------------------------------------------------
 Foods accounting for the largest quantity of food intake by individuals
                        (arranged alphabetically)
------------------------------------------------------------------------
1.........................................  Apple
2.........................................  Banana
3.........................................  Beef
4.........................................  Carrot
5.........................................  Chicken
6.........................................  Corn, field
7.........................................  Corn, sweet
8.........................................  Egg
9.........................................  Grape
10........................................  Lettuce
11........................................  Milk
12........................................  Onion
13........................................  Orange
14........................................  Pork
15........................................  Potato
16........................................  Rice
17........................................  Soybean, oil
18........................................  Sugar
19........................................  Tomato
20........................................  Wheat
------------------------------------------------------------------------


    Having identified the top 20 raw agricultural foods, EPA will 
characterize the pesticide residue levels on these foods using 
information collected by two Federal Agency monitoring programs, the 
USDA Pesticide Data Program (PDP) and the Surveillance

[[Page 56456]]

Monitoring Program conducted by FDA's Center for Food Safety and 
Applied Nutrition. PDP has been collecting pesticide residue data since 
1991. PDP is designed to provide a nationally representative database 
on the distribution of pesticide residues in food as close as possible 
to the actual time of consumption as practical. Using analytical 
methods that have been standardized and validated, and following strict 
quality control procedures, USDA has focused on foods highly consumed 
by children throughout the year. Over the years of operation, PDP has 
collected data on over 290 different pesticides and 50 different 
commodities. Additional information can be found at https://
www.ams.usda.gov/science/pdp/index.htm. The FDA Surveillance Monitoring 
Program is designed primarily for enforcement of pesticide tolerances 
on imported foods and domestic foods shipped in interstate commerce. 
Domestic samples are collected as close as possible to the point that 
the food enters the distribution system. FDA samples imported food at 
the port of entry into the United States. Additional information on the 
FDA program appears at https://www.cfsan.fda.gov/~dms/pesrpts.html.
    Because of the differences in how samples are collected and 
handled, EPA will rely on the PDP database when both sources cover the 
same pesticides and commodities. The FDA Surveillance Monitoring 
Program data covers different pesticides and commodities in different 
years from the PDP monitoring (e.g., in 1999, FDA used analytical 
methods capable of detecting 366 different active ingredients). 
Therefore, in making its weight-of-the-evidence judgement, EPA will 
consider the FDA information as a supplement to the information from 
the PDP database.
    EPA will review the two residue monitoring databases to identify 
the pesticide active ingredients which appear on the largest proportion 
of the samples, focusing on the 20 foods which make up the largest part 
of the U.S. diet. EPA will then review all of the information to make a 
judgment about whether the pesticide is likely to have relatively more 
widespread or higher levels of human exposure by the food pathway than 
other pesticides. This judgement involves consideration of such factors 
as the number of foods on which the residue is detected, the quantity 
of the diet represented by the food, and the overall number of 
detections and the frequency of detection.
    EPA recognizes that this approach would be more likely to give 
higher priority to the pesticides which are the subject of routine 
monitoring in either PDP or FDA's Surveillance Monitoring Program. Both 
programs rely primarily on ``multi-residue methods'' that are capable 
of detecting many different chemical substances using a single 
analytical procedure. Active ingredients which require specialized 
analytical methodology may not be looked for and thus would be unlikely 
to be included for consideration in the food pathway. This limitation 
particularly applies to newer pesticide active ingredients. 
Notwithstanding these limitations, EPA believes the approach described 
is a practicable approach for identifying pesticide active ingredients 
with widespread or high levels of exposure.

B. Water Pathway

    Portions of the general population may be exposed to pesticide 
residues in sources of drinking water. Although monitoring data 
indicate that most pesticide active ingredients are rarely detected, 
analytical surveys in virtually every region of the country have 
detected a number of active ingredients in ground and surface water 
used as sources of drinking water. Monitoring also indicates that, even 
when found in water, residue levels vary significantly both seasonally 
and regionally for a single pesticide, as well as across pesticides. 
Particularly for surface water, residues tend to occur in pulses that 
can last days to weeks to months, depending on the type of water body 
and the pesticide. Almost every person consumes some water every day, 
either in prepared foods or beverages (e.g., coffee, tea, or 
reconstituted juice) or simply by drinking water; therefore, water may 
be a significant source of exposure.
    To assess relative exposure to different pesticides in water, EPA 
will examine a number of different databases that contain the results 
of programs to monitor surface and ground water for the presence of 
pesticide residues. The different media covered by these databases 
include, finished drinking water, ambient water, finished ground water, 
fish tissue, and sediment, all of which reflect the presence of a 
substance in water sources. The presence of a substance in these media 
establishes the potential for exposure via drinking water. All sources 
of drinking water exposure will be considered of equal priority.
    As with the residue data for the food pathway, EPA will compile the 
information from the various databases concerning the detection of 
different pesticides in water. After compiling the information, EPA 
will examine the results to identify pesticides for which there appears 
to be greater potential for widespread human exposure, based on factors 
such as the number of samples and the geographic distribution of the 
detections. The presence of a single or only a few detections of a 
pesticide in a limited geographic area typically would not be a 
sufficient basis for concluding that the pesticide should be identified 
as potentially having either widespread or high levels of exposure by 
the water pathway.
    These databases, which contain data collected by Federal and State 
agencies, academicians, pesticide companies, and others, are summarized 
in this unit:
    1. EPA Pesticides in Ground Water Database. The Pesticides in 
Ground Water Database (PGWDB) was created to provide a more complete 
picture of ground water monitoring for pesticides in the United States. 
It is a collection of ground water monitoring studies conducted by 
Federal, State, and local governments; the pesticide industry; and 
private institutions between 1971-1991. The PGWDB compiles, in tabular 
format, data from monitoring of untreated ground water and contains 
data only from studies in which pesticides were included as analytes. 
Some data limitations include: Age of the data; differences in the 
design of studies; lack of historical pesticide use or hydrological 
information; and lack of information on well use, sampling practices, 
and laboratory procedures. Further details can be found in EPA 
Pesticides in Ground Water Database, A Compilation of Monitoring 
Studies: 1971-1991 National Summary (Ref. 7).
    2. EPA Chemical-Specific Monitoring Data. Pesticide registrants 
have conducted and submitted to the Agency targeted surface water and 
ground water monitoring studies for approximately 50 pesticide active 
ingredients. The Agency decides whether to require monitoring of 
untreated or ambient surface or ground water for a pesticide based on 
the environmental fate characteristics (persistence and mobility) of 
the pesticide; the current or proposed use patterns for the pesticide; 
and other information that would indicate potentially significant 
levels of the pesticide that could be present in water. The design of 
monitoring studies takes into consideration application rate, crops, 
and the location of potentially more vulnerable use sites. These 
studies are performed under Good Laboratory Practice regulations, and 
contain internal quality assurance procedures. When submitted, the 
monitoring data undergo primary and secondary review

[[Page 56457]]

by Agency scientists. In implementing its approach for selecting the 
initial list of chemicals for screening, EPA will review these 
chemical-specific monitoring data sources to determine if they contain 
information for pesticide active ingredients without data from other 
water monitoring data sources.
    3. United States Geological Survey/EPA Reservoir Monitoring Study. 
The United States Geological Survey (USGS)/EPA Reservoir Monitoring 
Study was a pilot monitoring program initiated by the USGS and EPA to 
provide information on pesticide concentrations in drinking water and 
to assist in the implementation of FQPA. Drinking-water utilities that 
withdrew water from reservoirs were sampled in 1999 and 2000. Water 
samples were collected from raw water (at the intake point) and from 
finished drinking water (at the tap prior to entering the distribution 
system). At some sites, samples were also collected at the reservoir 
outflow. Sampling frequencies were designed to measure long-term mean 
and short-term peak concentrations of pesticides in drinking water. The 
analytical methods used for analyzing the pesticides in the water 
samples included 178 different pesticides and degradation products. 
Additional information on the USGS/EPA Reservoir Monitoring Study can 
be found in Pesticides in Select Water Supply Reservoirs and Finished 
Drinking Water, 1990-2000: Summary of Results from a Pilot Monitoring 
Program (Ref. 8).
    4. Environmental Monitoring and Assessment Program. Environmental 
Monitoring and Assessment Program (EMAP) is an EPA research initiative 
designed to support the development of tools necessary to monitor and 
assess the status and trends of national ecological resources. Research 
is conducted on various ecosystems (e.g., estuaries, forests, 
rangelands, and lakes). Sediment samples were collected in 18 states at 
various times between 1990 and 1998. This data source provides 
information about the contaminants present in sediment/soil that humans 
and wildlife may contact. EMAP includes relevant data for over 170 
chemicals and three separate data sets for estuary sediments. In 
addition, six additional estuary data sets are now available that will 
also be considered. Extensive field and laboratory quality assurance/
quality control (QA/QC) procedures were performed during the collection 
and analysis of the samples. Further details can be found at https://
www.epa.gov/emap.
    5. National Sediment Inventory. The Water Resources Development Act 
(WRDA) of 1992 directed EPA, in consultation with the National Oceanic 
and Atmospheric Administration (NOAA) and the U.S. Army Corps of 
Engineers (USACE), to conduct a national survey of data regarding the 
quality of sediments in the United States. To comply with the WRDA 
mandate, EPA's Office of Science and Technology initiated the National 
Sediment Inventory (NSI). The NSI is a database that documents the 
composition of sediment in rivers, lakes, oceans, and estuaries. The 
NSI tissue residues studies (primarily fish) help assess sediment 
quality and can be used to assess potential exposure of humans to these 
chemicals through the consumption of fish. Also, sediment chemistry 
data are evaluated for theoretical bioaccumulation potential. The NSI 
includes data collected by a variety of Federal, State, regional, 
local, and other monitoring programs from 1980 through 1999. It 
includes over 4.6 million analytical observations for over 50,000 
monitoring stations across the country of sediment chemistry, tissue 
residues, and sediment toxicity data. NSI's minimum data requirements 
include monitoring program identification, sampling date, latitude and 
longitude coordinates, and measured units. EPA retains additional data 
such as QA/QC information, if available, but did not require that 
information for a data set to be included in NSI. Additional 
limitations of the compiled data include the mixture of data sets 
derived using different sampling strategies, incomplete sampling 
coverage, and the age and quality of the data. Because the data 
analyzed in the NSI report were collected over a relatively long period 
of time, conditions may have changed since the sediment was sampled. 
Further details on the NSI database and the National Sediment Quality 
Survey, which the NSI was developed to support, can be found at https://
www.epa.gov/waterscience/cs/nsidbase.html.
    6. National Drinking Water Chemical Occurrence Database. EPA 
developed the National Drinking Water Chemical Occurrence Database 
(NCOD) to satisfy the statutory requirements set forth by Congress in 
the 1996 amendments to SDWA to maintain a national drinking water 
contaminant occurrence database using occurrence data for both 
regulated and unregulated contaminants in public water systems. NCOD 
provides a library of water sample analytical data (or ``samples 
data'') that EPA is currently using and has used in the past for 
analysis, rulemaking, and rule evaluation. The drinking water sample 
data, collected at public water systems, are for both regulated and 
unregulated contaminants. The data have been extensively checked for 
data quality and analyzed for national representativeness.
    Currently, NCOD provides links to the unregulated contaminant 
monitoring data (UCMR), which are being collected and added to NCOD, as 
well as to static data sets that have been used in published regulatory 
analyses. These latter (static) data sets have been extensively 
quality-checked, and their corresponding reports provide full 
descriptions (meta data) of the data. Further details can be found at 
https://www.epa.gov/safewater/data/ncod.html.
    7. National Stream Quality Accounting Network Data. The National 
Stream Quality Accounting Network (NASQAN), a monitoring and data 
collection program conducted by the USGS, is designed to characterize 
raw surface water and sediment in large sub-basins of rivers, determine 
regional source areas for chemicals, and assess the effects of human 
influences on observed concentrations and amounts of chemicals. Since 
1995, NASQAN has focused on monitoring the water quality of four of the 
nation's largest river systems: The Mississippi, the Columbia, the 
Colorado, and the Rio Grande. A network of 40 stations monitors the 
concentrations of a broad range of chemicals including pesticides, 
major ions, and trace elements. NASQAN contains relevant data for over 
70 chemicals. NASQAN samplers collect quality control samples to 
evaluate the quality of sampling data. However, the data in NASQAN do 
not characterize ambient water quality throughout the United States, 
only for four river basins and sub-basins. Further details can be found 
at https://water.usgs.gov/nasqan.
    EPA will use the most current NASQAN data available. Following a 
brief review of current NASQAN data, EPA determined that no sediment 
data exists and only surface water data were available for pesticide 
active ingredients. NASQAN data may be updated prior to selecting the 
initial list of chemicals for screening and it is possible that 
sediment data may be made available and used for pesticide active 
ingredients for screening.
    8. National Water Quality Assessment Program. Congress appropriated 
funds in 1986 for the USGS to design and implement a program to address 
questions related to status and long-term trends in raw surface and 
ground water quality at national, regional, and local scales. The USGS 
began a pilot program in seven project areas to develop and

[[Page 56458]]

refine a plan for the National Water Quality Assessment (NAWQA) 
Program. In 1991, the USGS began full implementation of the program. 
The NAWQA Program builds upon an existing base of water-quality studies 
of the