used and applied. EPA requires this information because differences in
use can translate to significant differences in exposure, and thus in
risk. For applicator exposure, use information may include, but is not
limited to, who applies the antimicrobial pesticide, the use sites,
site locations, use directions, application rates and frequencies,
application equipment and methods, protective equipment used,
protective clothing worn, and other information that will determine
exposure to antimicrobial pesticide handlers.
    The Agency acknowledges that the guideline for applicator product
use information has not yet been finalized. However, the guideline for
applicator product use information should be substantially similar to
the one for post-application. The guideline for post-application
product use information was presented to the FIFRA Science Advisory
Panel (SAP) in March 1998. (The draft guideline is available at http://
www.epa.gov/scipoly/sap/meetings/1998/march/contents.htm.) The Agency
will finalize both guidelines before publishing a final rule
establishing antimicrobial data requirements.

D. Post-Application Exposure

    The current data requirements for post-application exposure in
Sec.  161.390 are focused on reentry to treated areas by agricultural
workers. Since the promulgation of these requirements in 1984, the
Agency has become increasingly concerned about post-application risks
to persons in occupational settings other than conventional food, feed,
and fiber crop agriculture. The Agency is now proposing to require
post-application exposure data for other settings where people may be
exposed, regardless of whether they are on-the-job or bystanders. Under
current practice, post-application exposure data are generally required
for occupational and residential settings on a case-by-case basis when
specific toxicity and exposure criteria have been met. Moreover, FFDCA
mandates that EPA perform additional scientific analyses which before
1996 had not been a routine part of the Agency's risk assessment
process, including the assessment of aggregate exposures from multiple
pathways including dietary and non-dietary routes of exposure.
    The Agency proposes to require data addressing post-application
exposure for antimicrobials when the toxicity and exposure criteria are
triggered. Two new exposure data requirements (soil residue dissipation
and non-dietary ingestion exposure) are today proposed for
antimicrobials. As discussed in Unit IX.A., this not only codifies the
Agency's current practices, but also harmonizes the requirements for
antimicrobials with those of conventional pesticides. EPA now proposes
to codify these requirements in proposed Sec.  158.2270 and set out
explicitly in Sec.  158.2270(b) the triggers describing the
circumstances under which such data must be submitted.
    For post-application exposure, the proposed data requirements are
as follows:
    1. Soil residue dissipation. These data are needed to characterize
exposures to residues of antimicrobials, and most particularly wood
preservatives, that occur through contact with outdoor soils. This
information is critical for assessing risks to children who play around
and are in contact with treated wood structures such as decks, play
sets, and gazebos, and the surrounding soils. This would be a new data
requirement for antimicrobials. Protocols must be approved by the
Agency prior to the initiation of the study. Details for developing
protocols are available from the Agency.
    2. Indoor surface residue dissipation. The Agency proposes to
require the indoor surface residue dissipation study (sometimes known
as a surface wipe sampling study). This study supplies information on
residue dissipation from treated areas and articles such as carpets,
hardwood floors, and counter tops, after antimicrobial pesticides have
been used. It is also used to determine residue dissipation from decks
and other structures manufactured from treated wood.
    These data would quantify residue loads and characterize the
dissipation rate (i.e., how fast pesticide residues disperse over time
following application) of antimicrobial pesticides on indoor surfaces.
The Agency could then assess the magnitude and duration of human
exposure to antimicrobials present as surface residues. Without such
data, the Agency has no precise means of calculating human exposures to
such substances from contacting surfaces over time. This requirement
would not apply to uses that are not surface treatments, e.g., aquatic
areas, swimming pools, antifoulant coatings and paints.
    The draft guideline for indoor surface residue dissipation is
available at http://www.epa.gov/scipoly/sap/meetings/1998/march/
contents.htm. This draft guideline was externally peer-reviewed before
presentation to the SAP in 1998. An examination of the FIFRA SAP
website since 1998 to the present will show many presentations to the
SAP on assessing occupational and residential exposures. Science has
evolved in this area.
    EPA notes that it has reviewed and accepted many studies, on a
case-by-case basis, that were not conducted in accordance with current
guidelines, but which serve its needs and provide suitable information
for risk assessment purposes. The guidelines themselves do not impose
mandatory requirements. Instead, they present recognized standards for
conducting acceptable tests, guidance on evaluating and reporting data,
definition of terms, and suggested study protocols. The draft
guideline, therefore, serves as a starting point for pre-protocol
submission meetings where the Agency's scientists can provide guidance
to registrants or task forces on aspects of study design.

The Agency's scientists are always willing to work with individual
registrants to develop study designs to fulfill data requirements. The
Agency will finalize this guideline before publishing a final rule
establishing antimicrobial data requirements.
    For wood preservatives, EPA has worked with the Consumer Product
Safety Commission (CPSC) to develop methodologies for conducting
surface wipe sampling studies on wood. Protocols for wood preservative
treated surface wipe sampling studies must be approved by the Agency
prior to the initiation of the study. Details for developing protocols
are available from the Agency.
    3. Dermal exposure. EPA proposes to require dermal exposure data
for both outdoor and indoor dermal exposures to estimate the dermal
exposure to persons exposed after the pesticide application has been
completed. The discussion in Unit IX.C. of this preamble for handler
dermal studies is also applicable to post-application exposures.
    4. Inhalation exposure. EPA proposes to require inhalation exposure
data for both outdoor and indoor inhalation exposures to estimate the
inhalation exposure to persons exposed after the pesticide application
has been completed. The discussion in Unit IX.C. of this preamble for
handler inhalation studies is also applicable to post-application
exposures.
    5. Biological monitoring. A conditional requirement for biological
monitoring data was discussed in Unit IX.C. That discussion is also
applicable to the proposed conditional requirement for biological
monitoring for post-application exposure which codifies the Agency's
current practices.
    6. Product use information. EPA proposes to require product use
information for all antimicrobials. Such information has been routinely
submitted to EPA by applicants and is now being codified as a separate
and distinct requirement. For post-application exposure, required
product use information includes information on reapplication rates and
frequencies, post-application entry restrictions, re-entry intervals,
rinsing and other residue removal practices, and other use data
relevant to exposure after application. The draft guideline for post-
application product use information is available at http://www.epa.gov/
scipoly/sap/meetings/1998/march/contents.htm. The Agency will finalize
this guideline before promulgating a final rule establishing
antimicrobial data requirements.
    7. Description of human activity. For post-application exposure the
Agency is proposing to require a description of human activities.
Information on those persons who may enter treated areas after the
application is complete has been routinely submitted to EPA by
applicants and is now being codified as a separate and distinct
requirement
    These data will allow for a more accurate evaluation of the
exposure potential associated with use of an antimicrobial pesticide.
The description of human activity data would define the activity
patterns that affect exposures (e.g., defining the exposed populations
in commercial/institutional and residential settings, the application
sites, site-specific information on exposure time per activity, type of
protective clothing worn, and any other relevant use activity data).
The description of human activity information would be used with the
use information (both application and post-application), to help the
Agency determine whether the exposure potential for humans is likely to
be significant, and if additional data will be needed.
    8. Data reporting and calculations. EPA proposes to require
applicants to submit data reporting and calculation information
whenever post-application exposure data are submitted. Such information
has been routinely submitted to EPA by applicants as part of any
submission of exposure data and is now being codified as a separate and
distinct requirement. The discussion in Unit IX.C. of this preamble for
handler data reporting and calculations is also applicable to post-
application exposures. Note in particular the discussion of the
requirement at 40 CFR 26.1303 for full documentation of the ethical
conduct of all submitted research involving human subjects, whether or
not they were intentionally exposed.
    9. Non-dietary ingestion exposure. The Agency proposes to require a
non-dietary ingestion exposure study for residential types of exposures
only. This study is not required for occupational exposures since the
primary concern for adult workers is exposure via the dermal and
inhalation routes. This would be a new data requirement that evaluates
the potential oral exposures to humans, particularly children, from
antimicrobial pesticide residues from sources other than food.
    Note that EPA regulations at 40 CFR 26.1203 prohibits, without
exception, conduct of any research intended for submission to EPA under
the pesticide laws which involves intentional exposure of children
under 18. Thus, any study of potential exposure of children, oral or by
any other pathway, to antimicrobial pesticide residues must only be an
observational study, involving no intentional exposure of children.
    Incidental oral exposure via hand-to-mouth, object-to-mouth and
direct mouthing/ingestion is an important exposure pathway for infants
and toddlers. The results from these studies will be used to assess the
risks associated with the incidental ingestion of antimicrobial
pesticides by children following antimicrobial pesticide applications
in residential or public settings, or exposure to treated surfaces
(e.g., carpets, toys, wood structures). This study would be required
for uses in and around the home, daycare centers and schools.
    The Agency is primarily concerned with non-dietary exposures
immediately following application of the antimicrobial pesticide;
therefore, dissipation studies alone would not provide the information
needed to assess risks from non-dietary ingestion. Information such as
frequency/duration of hand-to-mouth activities and surface area mouthed
are often needed as input values for the calculations that are
performed to assess non-dietary ingestion exposure. When appropriate,
EPA's Exposure Factors Handbooks (see http://cfpub.epa.gov/ncea/cfm/
recordisplay.cfm?deid=20563) can be used as the source of this
frequency/duration information. However, the data in these Handbooks
cannot replace chemical-specific information from studies of treated
articles/surfaces that quantifies the amount of pesticide residue on
such surfaces.
    Non-dietary ingestion may also occur through hand-to-mouth or
object-to-mouth transfer of antimicrobial pesticide residues during
activities performed by children (e.g., crawling) that put them in
close proximity with treated surfaces. Non-dietary ingestion exposure
would be expected in residential or public (e.g., schools, daycare)
settings following exposures to:
     Soils in contact with, or adjacent to, preservative-
treated wood structures such as play structures.
     Outdoor surfaces such as decks.
     Indoor surfaces such as antimicrobial pesticide-treated
paint chips, or antimicrobial-sprayed floors or walls.
     Antimicrobial-treated textiles, polymers, or other items
(e.g., clothing, bedding, carpets, or toys).
    Non-dietary ingestion studies would, for example, monitor the
amounts of pesticide residues in the rinsate from hand washing, and
thus allow the Agency to develop science-based models or formulas to
estimate

inadvertent exposure. The draft guideline for non-dietary ingestion is
available at http://www.epa.gov/scipoly/sap/meetings/1998/march/
contents.htm. This draft guideline was externally peer-reviewed before
presentation to the SAP in 1998. An examination of the FIFRA SAP
website since 1998 to the present will show many presentations to the
SAP on assessing occupational and residential exposures. Science has
evolved in this area.
    EPA notes that it has reviewed and accepted many studies, on a
case-by-case basis, that were not conducted in accordance with current
guidelines, but which serve its needs and provide suitable information
for risk assessment purposes. The guidelines themselves do not impose
mandatory requirements. Instead, they present recognized standards for
conducting acceptable tests, guidance on evaluating and reporting data,
definition of terms, and suggested study protocols. The draft
guideline, therefore, serves as a starting point for pre-protocol
submission meetings where the Agency's scientists can provide guidance
to registrants or task forces on aspects of study design. The Agency's
scientists are always willing to work with individual registrants to
develop study designs to fulfill data requirements. The Agency will
finalize this guideline before publishing a final rule establishing
antimicrobial data requirements.

X. Residue Chemistry Data Requirements

A. General

    EPA proposes to adapt the basic residue chemistry data requirements
(Sec.  158.2290) as listed in subpart O of current part 158 to support
applications for antimicrobial products. However, EPA also proposes to
modify the applicability of those requirements to reflect the differing
risks and levels of exposure of antimicrobials. Residue chemistry data
are used by the Agency to estimate dietary exposure to pesticide
residues from food. If there are no direct or indirect food uses for
the antimicrobial, then no residue chemistry data are required.
    The proposed changes will allow EPA to better estimate human
dietary exposure to antimicrobial residues in or on food or feed, to
more accurately assess tolerances and tolerance exemptions, and to
provide additional tools for the enforcement of pesticide residue
tolerances to ensure that food entering the commercial market meets the
``reasonable certainty of no harm'' standard under FFDCA.
    The residue chemistry database is designed to determine the
composition of the pesticide residue and how much of that residue is
present in food or animal feed. Residue chemistry studies include those
which define:
     The nature of the residue, i.e., metabolism studies.
     The magnitude of the residue, i.e., those studies which
measure how much of the residue of concern is present in food, feed,
and water.
    Food-use pesticides require both types of studies. Both plant and
livestock metabolism studies are needed to determine the breakdown of
the pesticide chemical in a living system, that is, whether the
chemical stays intact or is converted into metabolites. Occasionally,
the metabolites are toxic and are included in the analyses as a residue
of concern. Magnitude of the residue (MOR) studies are performed to
determine the level of residues of concern in food. Data collection
residue analytical methods are reviewed by EPA as part of the
validation of the metabolism and MOR studies which are used to
establish tolerances.
    In addition to dietary risk assessments, residue chemistry data are
used to establish pesticide tolerances, the maximum level of pesticide
residue that may remain on food. Because these are legal limits
enforced by FDA, enforcement methods for detecting the presence and
amount of the residue are needed, and are used by FDA, USDA, and the
States for food inspection purposes.
    There are distinct differences between the residue chemistry
requirements of conventional pesticides that are applied to crops in a
field setting and those of antimicrobials that are more likely to be
applied in a confined setting such as a food processing plant. Those
differences are reflected in the data requirements. For example, no
migration studies are required for terrestrial food and feed uses in
part 158, subpart O, and no rotational crop studies are required for
any antimicrobial uses. Certain test notes in part 158, subpart O and
in subpart W are also different. As expected, the differences result
from the different use patterns.
    Units X.B. and C. of this preamble discuss the two main categories
of food-uses for the purpose of antimicrobial residue chemistry data
requirements, direct and indirect. Units X.D. through Q. of this
preamble explain changes to specific residue chemistry data
requirements appropriate to antimicrobials. For the purpose of
determining antimicrobial residue chemistry data requirements, most
antimicrobial pesticides will be classified as either direct or
indirect food uses, which are generally delineated in Units X.B. and C.
of this preamble. For the purposes of defining the residue chemistry
data requirements for antimicrobials, the table in proposed Sec.
158.2290 further delineates direct and indirect uses into four
categories: direct and indirect food uses, agricultural premises, and
aquatic uses. Applicants should consult with the Agency on the
appropriate category(ies) for their product.

B. Direct Food Uses

    If the antimicrobial is applied directly to food or water, it is a
direct food use. Such uses would include, but are not limited to:
     Livestock.
     Livestock feed.
     Drinking water for humans, livestock and/or poultry.
     Egg washes.
     Fruit and vegetable rinses.
     Aquatic areas that have the potential to contaminate
potable water.
     Post-harvest applications that occur in the field, at a
treatment facility (such as a packing shed), during transport, and
while in storage, until the processing of the raw agricultural
commodity begins.
    No currently registered antimicrobial products are applied to
agricultural field crops. Should an application for such an
antimicrobial product be submitted to EPA, then the Agency would likely
require the same data as specified in part 158, subpart O for other
field-use pesticides applied to crops, as the test notes more
accurately reflect the conditionalities of a terrestrial use pattern.

C. Indirect Food Uses

    For the purpose of determining residue chemistry data requirements,
an antimicrobial use is considered an indirect food use when the
antimicrobial pesticide is applied to a surface or incorporated into a
material that will subsequently contact food, that is, the pesticide is
not applied directly to the food. Residues of the pesticide or its
degradates can be transferred to the food when it comes into contact
with these treated surfaces and articles.
    Antimicrobial products labeled for treatment of hard non-porous
surfaces which may come into contact with food (e.g., food area
premises and equipment) are classified as indirect food contact uses.
Sanitizers and disinfectants which remain on the surface of food-
handling or processing equipment are indirect food uses. Sanitizers
incorporated into articles (e.g., plastic products such as coffee cups
or cutting boards) intended

for food contact are also indirect food uses.
    Hard surfaces are considered to be food surfaces when food is
prepared for consumption, either commercially or residentially on such
surfaces. Examples of hard surfaces are eating utensils, dinnerware,
pots and pans, cutting boards, food preparation surfaces, countertops,
refrigerator shelves, refrigerator bins, ice trays, dining table tops,
and cabinet shelves. Wood treated with an antimicrobial pesticide
product could be used to construct or maintain a bee hive, a cattle
trough or feeding station. These and other indirect contacts with food
or feed are assessed to evaluate the need for a tolerance or tolerance
exemption.
    For the purpose of conducting a risk assessment for a sanitizer (an
antimicrobial not rinsed from food-contact surfaces), the Agency uses
the directions on the antimicrobial product label in combination with
modeled data to determine the amount of the sanitizer remaining. Under
this approach, EPA will initially assume that all of the sanitizer
residues remain on the surface and thus have the potential to enter the
food. This is a worst-case or screening-level assumption. EPA will then
use this modeled estimate in combination with toxicity data to
determine if there is a risk of concern and/or whether to establish a
tolerance or tolerance exemption. If there are risk concerns and if
scientifically appropriate, EPA may refine the estimate of residues
remaining on the surface using more realistic model assumptions. If no
risks of concern are identified using these refined assumptions, then
most likely EPA would not require higher-tiered, measured surface
residue data. Of course, as an alternative to the Agency's use of these
screening-level or refined, modeled estimates, the applicant may
provide data that measures the actual amount of sanitizer remaining on
the treated surface or transferring to food.
    For disinfectants (antimicrobials with potable water rinses) EPA
proposes to generally follow the risk assessment approach outlined for
sanitizer solutions. EPA would disregard the potable water rinsing and
assume that worst-case residues (estimated using the sanitizer model)
are available for entering food items. Alternatively, the applicant can
provide data measuring the actual amount of disinfectant remaining on
the surface or transferring to food after rinsing the treated surface.
    If the antimicrobial is to be incorporated into products with food
contact uses and bears a claim of surface sanitizing activity, the
Agency will generally, in the absence of data, evaluate the need for a
tolerance or tolerance exemption by assuming complete transference of
the chemical into food over the lifetime of the treated product.
Alternatively, the applicant may submit migration studies to
demonstrate the rate or amount of transference of the antimicrobial
into food items.

D. Chemical Identity

    Currently in part 161, information on chemical identity is required
for all use patterns. Today the Agency is proposing to continue this
existing requirement by requiring information on chemical identity for
all antimicrobial use patterns.

E. Directions for Use

    Currently in part 161, directions for use are required for all use
patterns. Today the Agency is proposing to continue this existing
requirement by requiring this information for all antimicrobial use
patterns.

F. Proposed Tolerance

    Currently in part 161, a proposed tolerance is required for all
food-use patterns. Today the Agency is proposing to continue this
existing requirement by requiring a proposed tolerance for all
antimicrobial food-use patterns.

G. Reasonable Grounds in Support of Petition

    Currently in part 161, reasonable grounds in support of petition is
required for all food-use patterns. Today the Agency is proposing to
continue this existing requirement by requiring this information for
all antimicrobial food-use patterns.

H. Submittal of Analytical Reference Standards

    Currently in part 161, submittal of analytical reference standards
is required for all food-use patterns. Today the Agency is proposing to
continue this existing requirement by requiring submittal of these
standards for all antimicrobial food-use patterns.

I. Nature of the Residue in Plants

    The Agency proposes to continue to require a nature of the residue
study in plants for aquatic uses and direct food contact uses. The
Agency proposes to continue to conditionally require this study to
support agricultural premise uses.

J. Nature of the Residue in Livestock

    The Agency proposes to continue to require a nature of the residue
in livestock study to support agricultural premise uses. The Agency is
also proposing to continue to conditionally require a nature of the
residue in livestock study to support direct food contact uses and
aquatic areas. As with the data requirements for conventional pesticide
chemicals EPA is proposing to change the chemical substance with which
the test is performed. This would codify existing practices.
    For antimicrobials used to treat animal drinking water, or to treat
wood in contact with animals or animal feed, or in aquatic areas, the
Agency proposes to change the test substance for the nature of the
residue in livestock study from ``pure active ingredient, radiolabeled
(PAIRA) and plant metabolites'' to ``PAIRA or radiolabeled plant
metabolite.'' The test substance ``metabolites'' will be changed to
``metabolite'' to clarify that dosing with more than one compound in
any one study is not acceptable. This is needed because in studies
involving simultaneous dosing with both the active ingredient and plant
metabolites, it is impossible to determine the amount of metabolite due
to active metabolism from that introduced through intentional dosing.
Simultaneous dosing with the active ingredient and any metabolites may
not produce useful results, because the active ingredient and
metabolites may have different metabolic pathways that cannot be
differentiated. In most cases dosing with only the parent compound is
necessary. However, in cases where plant and animal metabolites are
found to differ, separate studies in which livestock are dosed
separately with each unique plant metabolite may also be required.
    The Agency proposes to specify in the test note that the livestock
metabolism study would be required when an antimicrobial is applied
directly to livestock, to livestock premises, to livestock drinking
water, to livestock feed, or to crops used for livestock feed. This
would also include antimicrobial uses to treat wood in contact with
animals or animal feed, or in aquatic areas given the potential use for
crop and livestock production. Such applications may result in both
oral and dermal exposure of animals to the pesticide and, depending on
the results, may necessitate magnitude of the residue studies to
quantify the residues in meat, milk, poultry, and eggs.

K. Residue Analytical Methods

    EPA proposes to require development and submission of analytical
methods whenever a numerical tolerance is established. Residue
analytical methods have two primary purposes:
     To collect residue data for establishing tolerance levels
and

conducting dietary exposure assessments.
     To enforce the tolerances established by EPA in 40 CFR
part 180.
    Residue analytical methods are currently required in part 161, and
EPA proposes to continue this requirement. These methods are required
only if a numerical tolerance is established and since numerical
tolerances are rarely established for antimicrobials, submission of
this data should be a rare occurrence.
    In part 158, subpart W, EPA is proposing to create separate entries
in the proposed table in Sec.  158.2290 for these two types of residue
analytical methods to clearly indicate the need for both types of
methods, or a method that can be used for both data collection and
enforcement purposes. EPA believes that the separation of the combined
requirement into separate and distinct requirements will provide
clarity to applicants.
    The enforcement method has the following characteristics:
     Analyzes for the residues of regulatory concern, i.e.,
those named in the established tolerance.
     Is reasonably rapid (typically one day or less).
     Uses readily available equipment and reagents.
     Must be clearly and completely described in a stepwise
manner such that laboratory personnel competent using similar
procedures can successfully perform the procedure on the first trial.
     Is subject to an independent laboratory validation.
     Has a mechanism to confirm the results.
    The data collection method has the following characteristics:
     Analyzes for all residues of toxicological concern.
     No limitation on duration of procedure.
     May use specially-developed and very expensive equipment.
     Validation is subject only to internal laboratory
controls.
    If the applicant can develop one method and the Agency finds that
this one method satisfies the criteria for both the enforcement and the
data collection method, then only one method needs to be submitted.
Otherwise, two methods must be submitted. For the proposed table in
Sec.  158.2290 the ``Rs'' and ``CRs'' specified in the residue
analytical method data requirements reflect the Agency's best
professional estimate of the likelihood of a numerical tolerance being
established for an antimicrobial pesticide chemical and thus resulting
in the requirement to submit the data.
    As with the data requirements for conventional pesticide chemicals,
the Agency proposes to change the chemical substance for residue
analytical methods from ``TGAI and metabolites'' to ``residue of
concern.'' This would codify existing test practices.
    As with conventional pesticide chemicals (subpart O of part 158),
the Agency is proposing to require an independent laboratory validation
(ILV) of residue analytical methods to ensure the accuracy and
reproducibility of data used for tolerance enforcement purposes.
Codifying this current (since 1988) practice (Ref. 28) would promote
development of clearly written, complete descriptions of analytical
methods that can be used by Federal and State enforcement agencies.

L. Multiresidue Method Testing

    The current requirement in 40 CFR part 161 for residue analytical
methods actually encompasses several submissions to the Agency. The
first is the chemical-specific method(s) discussed in Unit X.K. of this
preamble and the second is the multiresidue testing. In promulgating
its part 158 conventional pesticide data requirements, the Agency
separated this combined requirement into separate and distinct
requirements. EPA is proposing to do the same for antimicrobial
pesticides.
    Today, the Agency is proposing to codify the requirement for
testing the residue of concern of the antimicrobial pesticide using the
FDA's and the USDA's multiresidue methods (MRM) as a separate data
requirement. As above, the Rs and CRs in the proposed table in Sec.
158.2290 reflect the Agency's best professional estimate of the
likelihood of a numerical tolerance being established. This testing is
required only if a numerical tolerance is established and since
numerical tolerances are rarely established for antimicrobials,
submission of this data should be a rare occurrence.
    MRMs are important components of pesticide monitoring and
enforcement programs. In food monitoring programs, such as those of FDA
and USDA, it is not practical or feasible to test for each individual
pesticide in a separate test. The MRMs are used to detect the presence
of many pesticides, and then if needed, re-testing is done with the
chemical-specific tolerance enforcement method. Since the residue
analytical method requirement is intended to refer to a method that is
specific for one pesticide (sometimes called a ``single residue
method'') and the multiresidue methods currently in use are designed to
measure as many pesticides as possible, it is clearer to list these as
two separate data requirements.

M. Storage Stability

    As with conventional pesticides, the Agency proposes to add a
storage stability study as an explicit requirement to validate the
results of the various magnitude of the residue studies. Such data have
been required previously as a part of the magnitude of the residue
study, but will now, as with conventional pesticides, be codified as a
separate requirement. As discussed in a test note to the proposed table
in Sec.  158.2290 storage stability data are required for any food or
feed use requiring magnitude of the residue studies unless analytical
samples are stored frozen for 30 days or less, and the active
ingredient is not know to be volatile or labile. This test note would
clarify when storage stability data are needed and also harmonizes the
requirements for antimicrobials with those of conventional pesticides.
    Magnitude of the residue studies address how levels of pesticide
residues in samples of human foods and livestock feeds are determined.
These samples are often stored for extended periods of time prior to
analysis. Since tolerances are based on residues at the time of harvest
(or sample collection) and the residues may be lost by processes such
as degradation and volatilization during storage prior to analysis,
storage stability data predicting the pattern of degradation, if any,
of residues during this period are critical to understanding the
results of the field trial studies.

N. Magnitude of Residue (MOR) Studies

    As with conventional pesticides, the Agency proposes to change the
test substance from EP (end-use product) to TEP (typical end-use
product) for the following types of MOR studies: Crop field trials,
processed food or feed, potable water, fish, irrigated crops, and food
handling studies.
    Residue data are needed for only one TEP of each formulation type
used on a given commodity or site. When newer or other types of
formulations are proposed for use, either additional residue data can
be submitted to show that the use of these new or different
formulations result in residues comparable to those arising from the
original formulation for which residue chemistry data already exist, or
side-by-side bridging studies can be conducted for the different types
of formulations. If the new formulation results in residues higher than
those from use of the original formulation, then the same number of
trials would generally be

required for the new formulation as was required for the original
formulation. This would codify a longstanding practice at EPA for
various MOR studies. The Rs and CRs reflect the likelihood of the need
for MOR studies in the Agency's best professional judgment. Test notes
to the table in the proposed Sec.  158.2290 describe the specific
circumstances in which MOR studies may be required for an
antimicrobial.

O. Magnitude of Residue in Meat, Milk, Poultry, and Eggs

    Similar to the livestock metabolism study, the Agency proposes to
change the test substance for the meat/milk/poultry/egg (M/M/P/E) MOR
studies. Due to the difficulties in interpreting results of studies in
which a mixture is fed, the Agency is currently discouraging the
feeding of mixtures and is instead requesting the feeding of isolated
compounds in livestock studies. Hence, to codify current practice, the
test substance will be changed to read a single plant metabolite
instead of metabolites in the plural. Provided that plant and animal
metabolites are the same, the parent compound must be the test
substance in livestock feeding studies. If any plant metabolite exists
that is not also an animal metabolite, a separate feeding study may be
required involving dosing with that unique plant metabolite. The Agency
will inform the applicant when this additional testing is required. It
is expected that this study will be rarely requested.
    The Agency proposes to continue the conditional requirement for M/
M/P/E MOR studies for agricultural premises, indirect food uses, direct
food uses and aquatic uses. There are three types of M/M/P/E MOR
studies: livestock feeding studies, direct livestock treatments, and
agricultural premise treatments. The Agency proposes to clarify that
livestock feeding studies generally are not required when (1) residues
are not found in/on feed items or (2) livestock metabolism studies
indicate minimal transfer of the pesticide residue to tissues, milk or
eggs. For those pesticides which leave non-detectable or low residues
in feed items and for which the livestock metabolism study shows little
transfer of radioactivity to tissues, the Agency may be able to
conclude that data on the level of residues in livestock and their
byproducts are not necessary. Livestock premise treatment studies are
required for those antimicrobials used to clean or otherwise treat
livestock premises such as feedlots. These are expected to be the most
common studies applicable to antimicrobials.

P. Anticipated Residues

    The term ``anticipated residue'' (AR) refers to exposure data that
would permit significant refinement of dietary exposure estimates.
Refinement means that the Agency would estimate very realistic dietary
exposure estimates after first using the screening-level estimates that
allow EPA to perform a very quick, but conservative dietary risk
assessment.
    As previously discussed, no currently registered antimicrobial
products are applied to agricultural field crops. Generally, for
antimicrobial direct food-uses, when performing the initial, screening-
level dietary risk assessment, EPA uses the antimicrobial tolerances as
the input values for dietary modeling. If there are risk concerns and
if scientifically appropriate, EPA may refine (that is to be more
realistic) the input values by using data showing the pesticide
residues in food closer to the point of consumption. Market basket
surveys are an example of one source of residue data that could be used
to generate more realistic dietary exposure estimates for direct food-
uses. Anticipated residue data would be required when estimates of risk
using residues at the tolerance level result in a risk of concern, and
a more realistic estimate is needed.
    However, antimicrobials also include indirect food uses such as
sanitizers and disinfectants which remain on the surface of food-
handling or processing equipment. For these indirect food-uses,
generally when performing the initial, screening-level dietary risk
assessment, EPA uses several high-end (over-estimated) assumptions as
the input values for dietary modeling. In such an assessment, the same
assumptions are used for every dietary assessment. Such an assessment
can be performed quickly, and if there are no risk concerns, then the
dietary assessment is considered to be complete. However, if there are
risk concerns and as scientifically appropriate, EPA would begin a
process of using the available information and data to refine, that is
to be more realistic, in estimating input values.
    Since the screening-level risk assessment did not consider the
particular use pattern of the antimicrobial chemical, as a first
refinement, EPA would modify the assumptions to account for the
particular use pattern of the chemical. Refinements to the assumptions
can also be made if measured data such as a migration study were
available.
    AR data would be required when estimates of risk have been refined
using information and any measured data initially available to EPA, and
these refined risks result in a risk of concern. Taking samples from
treated hard surfaces is an example of one source of residue data that
could be used to generate more realistic dietary exposure estimates for
an indirect food-use.
    If there is no food-use, then AR data would not be submitted to
EPA. AR data would be a conditional requirement that is triggered only
when estimates of risk conducted using residues at the tolerance level
may result in a risk of concern. This means that AR data would be
required only for a food-use, and only if a numerical tolerance is
established, and then only if the risk assessment conducted at
tolerance level results in a risk of concern. This would be an
infrequent occurrence for antimicrobials. Establishing this data
requirement for antimicrobials not only codifies the Agency's current
practices, but also harmonizes the requirements for antimicrobials with
those of conventional pesticides.

Q. Food Migration Studies

    This study is unique to antimicrobials and this proposal codifies
current practices. EPA is proposing to conditionally require a
migration study for indirect food uses when modeled estimates of the
amount of antimicrobial residues transferred to the food or feed may
result in a risk of concern. This study would not be required for any
other uses.
    A migration study is performed to determine the amount of a
chemical substance that can enter a food commodity through contact with
a treated surface. There are two basic types of migration studies. The
first type includes sanitizing and disinfecting solutions that are
applied to equipment in a food-processing facility. The second type
includes matrices such as wood, plastic, paper, cloth, or rubber which
may be impregnated with antimicrobial pesticides. The migration of the
antimicrobial into the food occurs when the food commodity comes into
contact with the treated surface or the impregnated matrix.
    As previously discussed, the Agency believes that it is possible to
model a worst-case estimate of the amount of the antimicrobial chemical
that migrates into the food commodity. If the worst-case estimates do
not result in a risk of concern, then the applicant would not need to
submit a migration study. As an alternative to these worst-case
estimates, the applicant may provide data for the

amount of sanitizer/disinfectant remaining on the surface.
    There is no Agency guideline for conducting a migration study. EPA
routinely accepts studies performed according to FDA's food migration
protocol/guidance. Applicants are encouraged to use existing FDA
methodologies. Information that could be of value to applicants
developing protocols is on the FDA website (Refs. 7, 9, 10, and 11).
Protocols must be approved by the Agency prior to the initiation of the
study. However, if a migration study has been reviewed and accepted by
FDA, then this fact should be included in the submission to EPA, along
with the migration study.

XI. Environmental Risk Assessment

A. General

    Environmental fate studies evaluate the mobility, distribution and
dissipation of a pesticide in various compartments of the environment,
such as water, soil, air, and sediment. These studies are designed to
identify which dissipation processes are likely to occur when the
pesticide is released into the environment and characterize the
significant degradates likely to result from these processes. Data from
these studies are used as inputs in exposure models, and, in
conjunction with ecological effects studies, are used to assess whether
a pesticide has the potential to cause adverse effects to wildlife,
fish, plants, and humans. Environmental fate studies are discussed in
Unit XII. of this preamble.
    Ecological effects data are used by the Agency to determine the
toxicological hazards of pesticides to various nontarget organisms,
such as birds, mammals, fish, bees, terrestrial and aquatic
invertebrates, and plants. These tests include short-term acute,
subacute, reproduction, simulated field, and full field studies
arranged in a tiered system that progresses from the basic laboratory
tests to the applied field tests. Ecological effects testing for
nontarget organisms are discussed in Unit XIII, and nontarget plants in
Unit XIV of this preamble.
    These data provide a foundation for an environmental risk
assessment. The results of the environmental fate assessment are
evaluated in conjunction with the results of the ecological effects
data to determine the potential of the pesticide to cause harmful
effects to nontarget organisms and plants.
    The Agency has divided the antimicrobial pesticides into two groups
for determining environmental fate and ecotoxicity data requirements:
the low environmental exposure grouping and high environmental exposure
grouping as discussed in Unit XI.B.

B. Determination of the Two Groupings: Low and High Environmental
Exposure

    1. Factors considered in determining the groupings. As previously
discussed, EPA is proposing to establish its 12 antimicrobial use
patterns in Sec.  158.2201. EPA examined these use patterns and
identified those that occur outdoors, discharge effluent directly to
the outdoors, or result in materials treated with antimicrobials (i.e.,
wood preservatives and antifoulants) being placed in the environment.
Given this direct link to the environment, and correspondingly higher
exposure potential, there is a greater potential for concern. In fact,
EPA has been requiring more data for such use patterns than for other
antimicrobial use patterns.
    2. The high environmental exposure grouping. The Agency believes
that the potential for environmental exposure is high for three of the
use patterns and part of a fourth use pattern. For the purposes of
requiring data, the following use patterns represent the high
environmental exposure grouping for environmental fate (Sec.  158.2280)
and ecotoxicity (Sec.  158.2240 and Sec.  158.2250) data requirements:
     Once-through industrial processes and water systems (part
of the industrial processes and water systems use pattern).
     Antifoulant paints and coatings.
     Wood preservatives.
     Aquatic areas.
    The data that have been typically required for the use patterns now
included in the high environmental exposure grouping are used to
calculate estimated environmental concentrations (EECs) of the
pesticide in different environmental media. These EECs are needed to
conduct quantitative environmental and ecological risk assessments.
These data would also have applicability to drinking water exposure
assessments that are used in human health risk assessments.
    3. The low environmental exposure grouping. The low environmental
exposure grouping is defined as those use patterns that are not
included in the high environmental exposure grouping. For the purposes
of requiring data, the following use patterns represent the low
environmental exposure grouping for environmental fate (Sec.  158.2280)
and ecotoxicity (Sec.  158.2240 and Sec.  158.2250) data requirements:
     Agricultural premises and equipment.
     Food-handling and storage establishments, premises and
equipment.
     Commercial, institutional and industrial premises and
equipment.
     Residential and public access premises.
     Medical premises and equipment.
     Human drinking water systems.
     Materials preservatives.
     Swimming pools.
     Recirculating industrial processes and water systems (part
of the industrial processes and water systems use pattern).

C. Data Requirements for Wood Preservatives

    As discussed previously in this proposal, wood preservatives are
considered to be an antimicrobial use pattern with high expectation of
environmental exposure. Wood that has been treated with a wood
preservative product is placed directly into the outdoor environment,
thus leading to the potential for significant release of the wood
preservative into the environment. The data required to register a wood
preservative product depend on the use site of the treated wood, which
can be land-only, aquatic-only or both. For instance, a wood
preservative product which would be used in or near water will usually
have more data requirements concerning the effects of the pesticide on
aquatic organisms than a product that is not used in or near water.
    Therefore, if a product specifies that wood that has been treated
with that product cannot be used in areas with the potential for that
wood coming into contact with water, then EPA believes that the
potential for exposure is decreased. Accordingly, it is current EPA
practice to require fewer environmental fate and ecological effects
studies for such products. In practice it is difficult to assure that
wood treated with a wood preservative that is for land-use only will
not come in contact with water. Treated wood intended for a use with
little potential aquatic exposure could be inadvertently diverted to
other uses, such as marine docks or pilings, which would have
considerable aquatic exposure. The Agency does not know if or how often
this kind of diversion occurs. However, the Agency notes that in the
United States, wood preservatives are categorized using the American
Wood Preservers' Association Use Category system. These categories
describe the exposure conditions which treated wood products can be
subjected to when in service. The categories, although general, provide
some measure of control over how treated wood products are used.

    A concern that has been raised to EPA is the difference in how
different countries regulate wood preservative products. This could
present a challenge for joint reviews of wood preservatives since
different data requirements and differing programmatic objectives could
result in different regulatory decisions.
    Today's proposed data requirements are based on EPA's current
practice of determining the data required for a wood preservative
product dependent on the usage (land-only versus land and aquatic). The
Agency requests comments on the regulation of wood preservative
products, and based on the comments received could continue with the
split usage or determine to no longer have such a split usage.

XII. Environmental Fate Data Requirements

A. Environmental Fate Data Requirements for Antimicrobials

    The Agency proposes to adapt the basic environmental fate data
types (Sec.  158.2280) as listed in subpart N of current part 158 to
support applications for antimicrobial products. EPA also proposes to
modify the applicability of those requirements to antimicrobials to
reflect differing risks and levels of exposure. Moreover, new types of
data are needed to evaluate the risks associated with use patterns more
typically associated with antimicrobials, such as discharge through
sewer systems and wastewater treatment plants to the environment. As
discussed in this Unit, such studies could include: Activated sludge
sorption isotherm, ready biodegradability, and modified activated
sludge, respiration inhibition test.
    Fate studies characterize how a pesticide chemical dissipates once
it is released into the environment, and identify the significant
transformation products likely to result from these processes. Fate
studies include both laboratory and field studies. Such studies can
provide input parameters needed in simulation modeling. Under a tiered
testing scheme, a specified set of laboratory studies determined by the
use patterns is performed first, and then a preliminary, qualitative
environmental fate and transport assessment is developed from the
results of those lower-tiered studies and the modeling. This assessment
could determine that no additional studies are needed. Or, this
assessment could trigger higher-tiered laboratory-based studies, and/or
to design or trigger appropriate field studies. Fate studies can also
be used as triggers for determining which ecological effects data will
be needed to support registration.
    Once the higher-tiered studies have been reviewed and evaluated,
then the Agency would use all these data to develop quantitative
environmental fate and drinking water exposure assessments, and to
calculate estimated environmental concentrations of the pesticide in
different media (such as water, sediment, or soils) under various
pesticide application and site scenarios. The Agency uses these
estimates of exposure in conjunction with toxicity data to assess
whether a pesticide has the potential to cause adverse effects on human
health via exposure through drinking water and the environment via
exposures through both water and soil.

B. History of Environmental Fate Data Requirements for Antimicrobials

    In 1984, at the time of promulgation of the original part 158 data
requirements, there were no environmental fate data requirements for
the indoor use pattern. At that time, EPA assumed that many of the
indoor uses went down-the-drain to a wastewater treatment plant (WWTP),
at which point dilution and degradation, or removal by WWTP processes
would mitigate environmental concerns. Thus, currently, in part 161,
there are no environmental fate data requirements for the indoor use
pattern.
    In 1997, the Agency presented a draft of the antimicrobial data
requirements to the FIFRA Science Advisory Panel (SAP) (Ref. 29). As
part of its presentation EPA explained its intent to divide
antimicrobial uses into two groupings based on the potential for
environmental exposure (high environmental exposure and low
environmental exposure). In 1997, the Agency defined the low
environmental exposure grouping as the following eight use scenarios:
Agricultural premises and equipment; food-handling/storage
establishments premises and equipment; commercial, institutional and
industrial premises and equipment; residential and public access
premises; medical premises and equipment; human drinking water systems;
materials preservatives; and swimming pools. For these eight use
scenarios for environmental fate data the Agency intended to require a
very reduced data set (hydrolysis data).
    In its report, the SAP expressed its concerns about ``the lack of
chemical fate data,'' indicated that hydrolysis would be an important
pathway of concern for only a subset of antimicrobial chemicals, and
stated that both biodegradation data, and microbial data should also be
required. According to the SAP, this was ``to ensure the safety of
environmental discharge but also for protection of publicly owned
treatment works (POTWs) and other treatment systems which often rely on
microbial treatment processes.'' In response to the SAP's concerns, the
Agency reexamined the need for environmental fate data other than
hydrolysis. As a result of this 1997 reexamination, the Agency
determined to conditionally require data on photodegradation in water
for low environmental exposures. At that time, the Agency determined
not to require biodegradation or microbial data.
    More recently, as part of its development of this proposed rule,
EPA re-evaluated the 1997 SAP recommendations concerning the data
requirements for environmental fate, and nontarget plant and organisms.
The reason for this re-evaluation was, in part, due to certain comments
that were received in response to the 2005 proposed rule for
conventional pesticide chemicals (70 FR 12276, March 11, 2005).
Additionally, the Agency was also becoming increasingly aware of
detections of antimicrobial chemicals in various environmental
compartments.
    The Agency received comments from four California water treatment
authorities and from environmental agencies from two cities in
California. The comments centered on their strong recommendations that
FIFRA data requirements should be equivalent to the data required to
develop water quality criteria (WQC) under the Clean Water Act (CWA)
and should consider water quality issues related to urban pesticide
use. California water-treatment authorities questioned the adequacy of
the Agency's assessment of risks with regard to water quality
considerations including: Use of aquatic toxicity data, surface water
quality studies, and urban uses of pesticides, particularly when these
uses result in pesticide residues in receiving waters from storm sewers
or sewage treatment plants.
    EPA believes that even though these comments were received in
response to the conventional pesticide chemicals proposed rule, the
submitted information on receiving waters for wastewater treatment
plants is particularly applicable to antimicrobials, many of which are
used indoors. This means that the antimicrobial goes down-the-drain and
eventually reaches a wastewater treatment plant. Therefore, in its
response to comments document for the final rule for conventional
pesticide chemicals, EPA agreed that pesticide discharge into municipal
sewage systems is an important issue

particularly for those antimicrobial pesticides which are typically
rinsed down the drain. EPA stated it would consider the issue of down-
the-drain chemicals in the proposed rule for antimicrobials.
    As a first step toward re-evaluating its processes and procedures
for conducting a risk assessment for an antimicrobial chemical that
goes down-the-drain, the Pesticide Program discussed these issues with
EPA's Office of Water (OW). The Agency is becoming increasingly aware
of detections of antimicrobial pesticide chemicals in various
environmental compartments, including surface water. An example of a
chemical with such detections is triclosan (Refs. 12, 17, 22, and 23).
The detection of such chemicals in surface water indicates that the
antimicrobial (or its degradate) is moving from the area of
application, down-the-drain to a WWTP, and then into the environment
via the treated effluent. Certain chemicals can pose a risk even at low
levels. Based on the Agency's concerns about the potential effects of
antimicrobials on the biological treatment processes used in WWTPs,
concerns about potential bioconcentration of antimicrobials after
release, and possible effects on nontarget species, the Agency now
believes that new environmental fate data requirements are needed for
down-the-drain antimicrobial uses.
    Therefore, EPA is proposing to require data to address
environmental fate (degradation), biodegradation data, and microbial
data, for the low environmental exposure grouping (as defined in Unit
XI.B. and once-through industrial processes and water systems. These
data reflect the Agency's concern about the potential movement of
antimicrobials and their degradates from the indoor environment to the
outdoor environment. Additionally, these lower-tiered data will allow
EPA to conduct screening-level environmental fate assessments which can
then indicate the need for higher-tiered fate and ecotoxicity studies
and higher-tiered environmental assessments.
    EPA specifically requests comments on the Agency's rationale for
requiring data to perform a screening assessment on down-the-drain
antimicrobial uses, the potential for performing higher-tiered studies
based on the results of the screening assessment, and the cost and
burden of performing the studies.
    EPA also notes that three use patterns, wood preservatives,
antifoulants, and aquatic uses are not considered down-the-drain use
patterns. As previously discussed, these uses either occur outdoors and
thus discharge directly to the environment, or result in materials
treated with antimicrobials being placed in the environment. Since
these use patterns are unlikely to go down-the-drain, a screening-level
environmental fate assessment is not needed.

C. Today's Proposal for Low Environmental Exposure Antimicrobials

    The Agency believes that environmental exposures from the use
patterns discussed in Unit XI.B.3. of this preamble are likely to be
small, because (1) the sites where these uses occur are not rapidly or
directly connected to aquatic environments, (2) some of the
applications occur on a very infrequent basis and other applications
involve very small amounts of the antimicrobial, and (3) in many cases
wastewaters containing these antimicrobials are processed in WWTPs. The
indirect movement of antimicrobials from the use sites into the outdoor
environment occurs mostly through water. In many cases, leachates,
rinsates, and flushes are released down-the-drain, and eventually reach
a WWTP. WWTPs degrade chemicals in their influent, although the degree
of degradation varies widely depending on the chemical, the treatment
process and other factors (e.g., ambient temperature). After treatment,
the effluent (the treated water and any chemicals remaining in that
water) is released into the aquatic environment, or to the terrestrial
environment via land application of sewage sludge.
    Given the expectation of low exposures to the environment, EPA
proposes to use a tiered system of data requirements to determine the
type of environmental fate assessment needed for the low environmental
exposure grouping. A screening-level assessment would be used to
determine the potential of the antimicrobial chemical to directly harm
the microbial treatment processes present in wastewater treatment
systems, the environmental compartment(s) that the antimicrobial is
likely to partition to, and the amount of antimicrobial that could be
present in the effluent that the treatment plant releases to the
environment. The presence of antimicrobials in an effluent release
means that an ecological assessment could be required to evaluate risks
to endangered species. It is also possible that estimation of
concentrations to use in a drinking water assessment could be required.
    The lower-tiered environmental fate studies being proposed for the
screening-level assessment for the low environmental exposure grouping
are discussed in detail in Units XII.E. - K. of this preamble. The
higher-tiered studies that would be triggered are based on a weight-of-
evidence evaluation of the results of the lower-tiered studies are
discussed in Units XII.L. - Q. EPA's proposal to conditionally require
these data for the low environmental exposure grouping would for these
studies expand the number of use patterns for which the test is
conditionally required.
    It may be possible to model some of the needed parameters. The
applicant is encouraged to review the approach discussed in Unit
XVIII.A. of this preamble on the use of Structure-Activity-Relationship
(SAR) assessments to ascertain if such techniques could provide useful
information in preparing their submission to EPA.
    EPA is proposing to conduct the screening-level of its fate
assessment for these low environmental exposure antimicrobials with
non-direct, delayed environmental connections in a three-pronged
approach. The three prongs are designed to (1) estimate the number of
days per year of exceedance of the antimicrobial surface water
concentration of concern to aquatic organisms in a surface water body
downstream of a treatment plant, (2) determine any negative effect of
the antimicrobials in the influent on the activated sludge biomass in
biological wastewater treatment systems, and (3) determine the
potential for the antimicrobial to accumulate in sediment or in
organisms downstream from the WWTP release, or for there to be negative
impacts on nontarget organisms in the receiving water body.
    For the first prong, modeling would be used to estimate a
screening-level exposure concentration of the antimicrobial in a
surface water body that receives effluent from a WWTP. EPA anticipates
using the Down-the-Drain model with the Probabilistic Dilution Model
(PDM) option in the Exposure and Fate Assessment Screening Tool (E-
FAST) (Version 2.0) available from the Agency's website (see http://
www.epa.gov/oppt/exposure/pubs/efast.htm). This model option uses
readily available data as inputs to estimate conservative (i.e., high-
end) exposure concentrations. E-FAST has been independently peer-
reviewed by EPA's Science Advisory Board. Comments from that peer
review have been incorporated into Version 2.0 of E-FAST.
    The PDM option of E-FAST can predict downstream chemical
concentrations from an industrial discharge and from disposal of
consumer products into household wastewater. The module uses a simple

mass balance approach that uses probability distributions as inputs.
The concentration of the chemical in the receiving surface water body
is also calculated as a probability distribution of the ratio of WWTP
effluent flow and stream flow immediately downstream of the WWTP. The
Down-the-Drain Model can be run with or without the PDM option.
    The Down-the-Drain Model requires as an input value the production
volume of the chemical. If this information cannot be supplied by the
applicant, then the Agency would need to estimate the volume. The
production volume would be used as if the entire volume of the chemical
were expected to go down the drain. However, the Agency would be able
to modify the production volume to account for the percentage of the
chemical that is expected to actually go down the drain. As an example,
almost all of a toilet bowl cleaner can be reasonably expected to go
down the drain, but a hard surface cleaner could also vaporize into the
air, dry on the surface, or be disposed of on paper towels into the
trash. Therefore it may be reasonable to adjust the production volume
used as an input to the Down-the-Drain model. The model estimates human
exposure from ingestion of drinking water and fish, and concentrations
of chemicals in surface waters downstream of WWTPs. The PDM option
estimates the number of days of exceedance of a concentration of
concern for aquatic organisms. Concentrations of concern are based on
measurements of acute and/or chronic effects to aquatic organisms.
    For the second prong of the assessment, EPA intends to require five
environmental fate studies to determine the potential of the
antimicrobial to harm the microbial treatment processes in wastewater
treatment systems, and to determine the potential amount of
antimicrobial present in the effluent that the treatment plant releases
to the environment. Higher-tiered studies would be triggered based on a
weight-of-evidence evaluation of the results of the following lower
tiered studies: Hydrolysis; photodegradation in water; modified
activated sludge, respiration inhibition test; activated sludge
sorption isotherm; and ready biodegradability. These tests are
discussed in Units XII.E., F., H., I., and K. of this preamble.
     The data from the hydrolysis study would allow EPA to
determine if the antimicrobial hydrolyzes in water during transport to
the WWTP, and also after release to the environment. These data are
routinely used to understand the persistence of a chemical in the
environment, and when the hydrolysis breakdown products should also be
considered in the environmental fate assessment.
     The data from the photodegradation in water study would
allow EPA to determine if the antimicrobial degrades in shallow water
due to exposure to sunlight. These data are used to understand the
persistence of a chemical in surface water.
     The modified activated sludge, respiration inhibition test
would allow EPA to identify antimicrobials which could harm the
microorganisms found in biological wastewater treatment systems and
would also indicate suitable antimicrobial concentrations for use in
the ready biodegradability test.
     The activated sludge sorption isotherm study would allow
EPA to assess the distribution of the antimicrobial between the sludge
and aqueous phases.
     The ready biodegradability study would allow the Agency to
determine whether the chemical tested achieves ``pass levels'' for
ready biodegradability. These screening tests are so stringent that it
is assumed that the chemicals that meet the pass levels will rapidly
and completely biodegrade in aquatic environments under aerobic
conditions.
    Modeling could also be used to predict the removal of a chemical in
a sewage treatment plant. STPWINTM is part of the EPI SUITE
modeling available via the Agency's website (see http://www.epa.gov/
oppt/exposure/pubs/episuite.htm). STPWINTM can predict
values not only for the total removal but also three contributing
processes: Biodegradation, sorption to sludge, and stripping to air.
    The third prong of the fate assessment would use the available
product chemistry data (for example octanol/water partition
coefficient, vapor pressure, or solubility in water) or predicted/
modeled data to determine the potential for the antimicrobial to
bioconcentrate. This is consistent with the approach used in the
Agency's PBT profiler, an assessment tool that estimates environmental
persistence (P), bioconcentration potential (B), and aquatic toxicity
(T) of a chemical based on its molecular structure. (see http://
www.epa.gov/oppt/pbtprofiler.)
    The Agency would then use the results of all three prongs to
conduct a screening-level environmental fate assessment. It is also
possible that information from open literature could be useful to the
Agency for its assessment. By combining the modeled exposure estimates
with information on the persistence of the antimicrobial, its
distribution in the environment, and its ability to harm the
microorganisms found in a biological WWTP, the Agency could determine
if there are risk concerns. Based on the concerns, EPA would be able to
determine if a more in-depth risk assessment would be required for
certain environmental media. Higher-tiered data could be required to
support such a risk assessment. The specific data would depend on the
environmental medium in which the antimicrobial and its transformation
products reside, and on the concentrations in the environment.
     If the antimicrobial is completely degraded to non-toxic
degradates, then it is likely that no higher-tiered environmental fate
data would be required.
     If the antimicrobial is not completely degraded by the
WWTP and is in the effluent released to surface water, then depending
on the concentrations that then occur in the environment, an assessment
similar to that of an antimicrobial with high environmental exposure
could be needed.
     If the antimicrobial partitions to water, then the
possible higher-tiered environmental fate studies would include:
Leaching and adsorption/desorption, and aerobic and anaerobic aquatic
metabolism.
     If the antimicrobial is likely to partition to sludge,
soil, or sediment, then possible higher-tiered environmental fate
studies would include aerobic and anaerobic soil metabolism studies,
and sediment studies. EPA has considered that antimicrobials may be
present in biosolids (sewage sludge) that are land applied. While soil
and sediment data would be required for an antimicrobial risk
assessment, these data may also be useful to EPA's Biosolids Program
conducted under 40 CFR part 503.
    The Agency specifically seeks comment on this proposed approach for
performing a screening-level environment fate assessment and the
potential for triggering higher-tiered studies.

D. Case Studies

    To assess whether the proposed approach provides the data needed to
assess exposure and risk of antimicrobial pesticides released to the
environment via down-the-drain use patterns, the Agency has conducted
four case studies. All of the models used for the case studies are
peer-reviewed, and publicly available. These case studies, entitled
``Four Case Studies of Antimicrobial Pesticides in the Down-the-Drain
Screening Model, Using the Proposed Approach for a Screening-Level
Environmental fate Assessment'' (Ref. 42) reflect a particular
integration

of the modeling results specific to the needs of antimicrobials.
    Four antimicrobial pesticides that have completed scientific review
in the reregistration process were selected to represent a range of
influent volumes to WWTPs, and general environmental fate and transport
properties. Antimicrobials undergoing reregistration were chosen
because they have fairly complete supporting data bases, and are well
understood; that is, they allow a comparison of the proposed approach
with real-world information.
    In selecting these four chemicals, the Agency attempted to select
at least one chemical that should trigger higher tier data requirements
and one that should trigger no higher tier data requirements. The
environmental fate and transport characteristics considered during the
case studies were environmental persistence, biodegradability,
hydrolytic stability, and sorption potential. Although not intended to
represent all possible combinations of chemical characteristics, use
scenarios, and usage volumes, the four antimicrobials selected for the
case studies were intended to include a sufficiently broad range of
possible outcomes to credibly assess the proposed approach.
     Chemical A was intended to represent a chemical with a
high loading (mass) within the WWTP's influent, high toxicity to fish
and aquatic invertebrates, high hydrolytic stability, relatively high
potential to biodegrade during wastewater treatment, and low to
moderate potential to adsorb to activated sludge. This chemical was
picked as a ``worst-case'' example.
     Chemical B was intended to represent a chemical with a
relatively low to moderate loading (mass) within the WWTP's influent,
high toxicity to fish and aquatic invertebrates, high hydrolytic
stability, and no available data on biodegradability during wastewater
treatment or the potential to adsorb to activated sludge.
     Chemical C represents a ``best-case'' example. It is an
organic acid that has a high loading (mass) within the WWTP's influent,
potential to bioaccumulate, high water solubility, no environmental
fate data, and no ecotoxicity data. This chemical was selected as a
case study because it degrades quickly and would be expected to have
little potential for ecotoxicity.
     Chemical D represents a mixture of two organic chemicals
with relatively low loading (mass) within the WWTP's influent volume,
high resistance to biodegradation during wastewater treatment, low
potential to sorb to activated sludge, and fairly low toxicity to fish
and aquatic invertebrates.
    The specific identities of the antimicrobials have been ``blinded''
to focus those who may wish to comment on the proposed approach, and
not what the result ``should'' be for a particular chemical.
    Many, but not all, of the values selected for input data for the
case studies were based on measured or estimated values for existing
antimicrobial pesticides. In some instances, values for input data
needed to run models to assess exposure and risk from down-the-drain
releases were not available. In those instances, hypothetical values
were used. Hypothetical values were also sometimes selected to enable
the cases to have sufficiently different key environmental fate and
transport properties to be able to more rigorously test the proposed
tiered approach for assessing exposure and risk to chemicals that are
released down-the-drain.

                         Table 1.--Case Studies
------------------------------------------------------------------------
                   Study                               Results
------------------------------------------------------------------------
Chemical A: A Chemical that Does Not        The proposed approach
 Hydrolyze and Only Partially Biodegrades    indicated Chemical A has
                                             considerable potential to
                                             pose ecological concerns.
                                             Aerobic and anaerobic soil
                                             metabolism studies are
                                             needed to refine
                                             environmental fate and
                                             dissipation, and higher-
                                             tier ecotoxicity studies
                                             are needed to determine
                                             risk to nontarget species.
------------------------------------------------------------------------
Chemical B: A Chemical Which Is Stable to   The proposed approach
 Hydrolysis, But There Is No Data on the     indicated that the lower
 Potential to Biodegrade During Wastewater   tiered environmental fate
 Treatment or Adsorb to Activated Sludge     studies are needed to
                                             determine Chemical B's
                                             dissipation rate in
                                             wastewater treatment
                                             plants. Several higher
                                             tiered ecotoxicity studies
                                             are needed to determine
                                             risk to nontarget species.
------------------------------------------------------------------------
Chemical C: An Organic Acid that is Highly  There are no data to show
 Soluble in Water                            that Chemical C would harm
                                             microorganisms found in
                                             biological wastewater
                                             treatment systems.
------------------------------------------------------------------------
Chemical D: A Mixture of Chemicals          Chemical D does not appear
                                             to pose ecological risks at
                                             the assumed production
                                             levels. However, the
                                             potential for
                                             biodegradation and any
                                             potential impacts on waste
                                             water treatment plant
                                             organisms could not be
                                             ascertained with the
                                             available information.
                                             Therefore, the proposed new
                                             lower tiered environmental
                                             fate studies are required.
------------------------------------------------------------------------

    From these case studies the Agency concludes that the proposed
approach produces the results desired by the Agency. The proposed
approach effectively distinguishes between chemicals that will require
more in-depth review and therefore higher-tiered studies versus
chemicals that require only the lower tiered environmental fate and
ecotoxicity studies to determine that no or few additional higher
tiered studies are needed.
    The Agency specifically seeks comment on the case studies (Ref. 42)
performed, including the assumptions used as model inputs. EPA will
consider comments specific to the case studies along with comments on
the proposed approach, as the Agency evaluates the use of the proposed
approach for down-the-drain antimicrobials in the final rule for
antimicrobial data requirements.

E. Hydrolysis Study

    EPA proposes to require a hydrolysis study for all antimicrobial
pesticides. In 40 CFR part 161, hydrolysis studies are currently
required for all use patterns except indoor. (The indoor part 161 use
pattern is being considered by EPA to be similar to the low
environmental exposure grouping.) Accordingly, EPA proposes to continue
to require hydrolysis studies for all of the high environmental
exposure use patterns (once-through industrial processes and water
systems, antifoulant paints and coatings, wood preservatives, and

aquatic areas) and to codify the requirement for all other
antimicrobial use patterns. In practice, hydrolysis studies have been
required for all antimicrobial chemicals for over 10 years.
    As previously discussed, EPA intends to require the hydrolysis
study as part of the lower tier of environmental fate data requirements
for down-the-drain chemicals. Chemicals that hydrolyze rapidly to less
toxic chemicals may need few higher tiered studies. This study will
allow EPA to determine how fast the antimicrobial breaks down in the
presence of water and what degradates are formed.

F. Photodegradation in Water

    In 40 CFR part 161, the photodegradation in water study is required
for aquatic use patterns. The Agency proposes to continue its existing
requirement for a photodegradation in water study for the antimicrobial
aquatic areas use pattern. The Agency also proposes to require the
study for all other antimicrobial uses. This would expand the number of
use patterns for which this study is required.
    This study will allow EPA to determine the degradation of the
pesticide in shallow water bodies as a result of exposure to sunlight.
Chemicals that degrade quickly in the environment may need few higher
tier studies. As with the data requirements for conventional pesticide
chemicals, EPA intends to clarify in a test note certain conditions
when photodegradation testing would not be required. Data on
photodegradation in water would not be required when the electronic
absorption spectra, measured at pHs 5, 7, and 9 of the chemical and its
hydrolytic products, if any, do not show absorption or tailing between
290 and 800 nanometers. If no absorption or tailing occurs in this
range, it is unlikely that photodegradation occurs (Refs. 25 and 27).

G. Photodegradation in Soil

    The Agency is proposing to require the photodegradation in soil
study for wood preservatives only. Leaching of wood preservatives (both
the parent or transformation products) from preservative-treated wood
could contaminate the surrounding soils. This would be a new data
requirement which would provide data on the dissipation, nature and
persistence of wood preservative degradation products formed by soil
surface catalyzed photolysis. Using these data the Agency can assess
the extent and duration of human (e.g., children playing below decks)
and/or nontarget organism exposures to soils adjacent to preservative-
treated wood structures. Such soils may contain the parent compound
and/or transformation products, which could include those formed via
photodegradation processes.

H. Activated Sludge Sorption Isotherm

    The activated sludge sorption isotherm study would be a new data
requirement. EPA is proposing to require this study only for the low
environmental exposure grouping and the once-through industrial
processes and water systems. This study is not required for wood
preservatives, antifoulants, or aquatic areas.
    For antimicrobial chemicals that go down-the-drain and reach a
WWTP, as part of its screening-level environmental fate assessment, EPA
will analyze the potential impact of the antimicrobial chemical on the
microorganisms in the typical biological treatment processes of a WWTP.
The activated sludge sorption isotherm study would allow EPA to assess
the distribution of the antimicrobial between the sludge and aqueous
phases. This information is important in determining the method used in
the ready biodegradability test and the higher-tiered studies that may
be required. Antimicrobials that are predominantly in the water column
and do not sorb to sludge may not need testing that focuses on sediment
and soils, such as the aerobic and anaerobic soil metabolism studies.
Antimicrobials that predominantly sorb to the sludge, soil, and
sediment may not need testing that focuses on water, such as the
aerobic and anaerobic aquatic metabolism studies.

I. Ready Biodegradability

    The ready biodegradability study would be a new data requirement.
EPA is proposing to require this study only for the low environmental
exposure grouping and the once-through industrial processes and water
systems. This study is not required for wood preservatives,
antifoulants, or aquatic areas.
    For antimicrobial chemicals that go down-the-drain and reach a
WWTP, as part of its screening-level environmental fate assessment, EPA
will analyze the potential impact of the antimicrobial chemical on the
microorganisms in the biological treatment processes of a WWTP.
Biodegradation is an important environmental pathway in which the
antimicrobial is broken down into ``smaller'' chemicals by bacteria.
This study supplies information on the rate of breakdown and the
completeness of the degradation to carbon dioxide and water. A ready
biodegradability study would allow the Agency to determine whether the
chemical achieves ``pass levels'' for ready biodegradability (e.g., 70%
removal of dissolved organic carbon). These screening tests are so
stringent that it is assumed that antimicrobials that ``pass'' will
rapidly and completely biodegrade in aquatic environments under aerobic
conditions. Chemicals that degrade quickly and completely may need few
higher tiered studies.

J. Porous Pot Test

    The Agency is proposing to conditionally require the porous pot
study for antimicrobials based on the results of the ready
biodegradability test. This would be a new data requirement. EPA is
proposing to require this study only for the low environmental exposure
grouping and the once-through industrial processes and water systems.
This study is not required for wood preservatives, antifoulants, or
aquatic areas.
    The porous pot study simulates the processes in the aeration basin
of the activated sludge sewage treatment process. It is therefore a
more realistic test than the biodegradability test. A chemical that did
not ``pass'' the biodegradability test could degrade (partially or
completely) under different conditions. The porous pot study would
provide a measure of the extent of biodegradation or removal likely to
occur during sewage treatment. An antimicrobial that degrades quickly
and completely in a typical wastewater treatment plant may need few
higher tiered studies.

K. Modified Activated Sludge, Respiration Inhibition Test

    The modified activated sludge, respiration inhibition test would be
a new data requirement. EPA is proposing to require this study only for
the low environmental exposure grouping and the once-through industrial
processes and water systems. This study is not required for wood
preservatives, antifoulants, or aquatic areas.
    For antimicrobial chemicals that go down-the-drain and reach a
WWTP, as part of its screening-level environmental fate assessment, EPA
will analyze the potential impact of the antimicrobial chemical on the
microorganisms in the biological treatment processes of a WWTP. The
modified activated sludge, respiration inhibition test would allow EPA
to identify antimicrobials which could harm the microorganisms found in
WWTPs and thus impair the ability of these bacteria to carry out their
intended function. Additionally, this study would also indicate
suitable

concentrations for use in the ready biodegradability test.

L. Leaching and Adsorption/Desorption

    In 40 CFR part 161, leaching and adsorption/desorption studies are
required for all use patterns except the indoor. Accordingly, EPA
proposes to continue to require the leaching and adsorption/desorption
studies for all of the high environmental exposure use patterns: Once-
through industrial processes and water systems, antifoulant paints and
coatings, wood preservatives, and aquatic areas.
    EPA is also proposing to conditionally require these data for the
low environmental exposure grouping. This would expand the number of
use patterns for which the test is conditionally required. For the low
environmental exposure grouping, the leaching and adsorption/desorption
study is considered to be a higher-tiered study that would be triggered
based on a weight-of-evidence evaluation of the results of the
hydrolysis, photodegradation in water, activated sludge sorption
isotherm, ready biodegradability, and modified activated sludge,
respiration inhibition tests.
    The leaching and adsorption/desorption study would provide
information on the mobility of the antimicrobial pesticide in soils.
The antimicrobial pesticide may or may not be transported to surface
water and/or ground water bodies used for drinking water. The presence
of an antimicrobial pesticide in drinking water sources could
contribute to exposure via drinking water.

M. Aerobic Soil Metabolism

    The Agency proposes to adapt its current requirement in 40 CFR part
161 for an aerobic soil metabolism study to the specific needs of
antimicrobial chemicals. Currently, 40 CFR part 161 requires this study
for terrestrial and outdoor types of uses.
    The aerobic soil metabolism study would be conditionally required
for the low environmental exposure grouping, and once-through
industrial processes and water systems. This would expand the number of
use patterns for which the test is conditionally required. The aerobic
soil metabolism study is considered to be a higher-tiered study that
would be triggered based on a weight-of-evidence evaluation of the
results of the hydrolysis, photodegradation in water, activated sludge
sorption isotherm, ready biodegradability, and modified activated
sludge, respiration inhibition tests.
    For aquatic areas, data would be required only for use sites that
are intermittently dry. This would codify current practices for aquatic
areas.
    For wood preservatives, the Agency proposes to require an aerobic
soil metabolism study. This would codify current practices for wood
preservatives.
    The aerobic soil metabolism study would allow EPA to better
understand the antimicrobial pesticide's degradation under aerobic
(oxygen-rich) conditions in the laboratory. The results of the study
would help to determine how fast the antimicrobial degrades in the
presence of microorganisms in different natural soils, and what
metabolites are formed. Chemicals that degrade quickly in soil are
likely to have lower exposure estimates.

N. Anaerobic Soil Metabolism

    Due to a printing error, the data requirement for an anaerobic soil
metabolism study was inadvertently omitted from the data tables (now in
40 CFR part 161) in 1991, and subsequent publications of the CFR. EPA
asserts that this requirement is still in existence: This data
requirement was never intentionally removed from the CFR by notice and
comment rulemaking, and is not considered a new requirement. Therefore,
EPA proposes to adapt its current requirement for an anaerobic soil
metabolism study to the specific needs of antimicrobial chemicals by
conditionally requiring the study for the low environmental exposure
grouping, and wood preservatives.
    EPA is expanding the number of use patterns for which the test is
conditionally required. For the low environmental exposure grouping,
the anaerobic soil metabolism study is considered to be a higher-tiered
study that would be triggered based on a weight-of-evidence evaluation
of the results of the hydrolysis, photodegradation in water, activated
sludge sorption isotherm, ready biodegradability, and modified
activated sludge, respiration inhibition tests.
    For wood preservatives, the anaerobic soil metabolism study would
be required if treated wood is used in aquatic environments or in soils
which may become flooded or waterlogged. This would codify current
practices for wood preservatives.
    The anaerobic soil metabolism study would facilitate a better
understanding of the antimicrobial pesticide's degradation under
anaerobic (oxygen-poor) conditions in the laboratory. The results of
the study would help to determine how fast the antimicrobial degrades
in the presence of microorganisms in different natural soils, and what
metabolites are formed. Chemicals that degrade quickly in soil are
likely to have lower exposure estimates.

O. Aerobic and Anaerobic Aquatic Metabolism

    In 40 CFR part 161 both the aerobic and anaerobic aquatic
metabolism studies are required for aquatic uses. For antimicrobial
chemicals, the Agency considers this to include the following uses:
Once-through industrial processes and water systems, antifoulant paints
and coatings, and aquatic areas. Therefore, the Agency proposes to
continue its current requirement for aerobic and anaerobic aquatic
metabolism studies for these uses. For wood preservatives these studies
have been required on a case-by-case basis; therefore, this proposal
would codify current practices.
    EPA is also proposing to conditionally require these two studies
for the low environmental exposure grouping. This would expand the
number of use patterns for which the test is conditionally required..
    Anaerobic aquatic metabolism studies describe and measure the
formation of pesticide residues in the water column or sediment under
low-oxygen conditions. Aerobic aquatic metabolism studies determine the
effects that exposure to aerobic, or oxygen-rich conditions in the
water column or sediment can have on a pesticide when it is dispersed
through the aquatic environment. Since the degradation or dissipation
pathways of pesticides in aquatic environments are almost always
different from those of terrestrial systems, soil metabolism studies
may not clearly define the paths of degradation found in aquatic
environments. For the low environmental exposure grouping, the aerobic
and anaerobic aquatic metabolism studies are considered to be higher-
tiered studies that would be triggered based on a weight-of-evidence
evaluation of the results of the hydrolysis, photodegradation in water,
activated sludge sorption isotherm, ready biodegradability, and
modified activated sludge, respiration inhibition tests. Chemicals that
degrade quickly in water or sediment are likely to have lower exposure
estimates.

P. Aquatic Sediment Studies

    Aquatic sediment studies are required for aquatic use patterns in
40 CFR part 161. Accordingly, the Agency proposes to continue its
current requirement for aquatic sediment studies for the antimicrobial
aquatic areas use pattern. EPA is also proposing to conditionally

require an aquatic sediment study for all other antimicrobial use
patterns based on the antimicrobial's potential for aquatic exposure.
    For the low environmental exposure grouping, the aquatic sediment
study is considered to be a higher-tiered study that would be triggered
based on a weight-of-evidence evaluation of the results of the
hydrolysis, photodegradation in water, activated sludge sorption
isotherm, ready biodegradability, and modified activated sludge,
respiration inhibition tests. This would expand the number of use
patterns for which the test is conditionally required.
    For the once-through industrial processes and water systems,
antifoulant paints and coatings, and wood preservatives, data would be
required based on the potential for aquatic exposure and if the weight-
of-evidence indicates that the active ingredient or principal
transformation products are likely to have the potential for
persistence, mobility, nontarget aquatic toxicity or bioaccumulation.
This would codify current practices.
    The aquatic field dissipation study is used to determine the
nontarget fate of a terrestrially applied pesticide that has a high
potential to enter aquatic environments and to substantiate laboratory
findings. The laboratory studies address one environmental fate process
at a time. The aquatic field dissipation study examines pesticide loss
or movement in water and sediment. Under field conditions degradation/
dissipation processes can proceed differently from how they occurred
under laboratory conditions. Data from this study can reduce the
potential overestimation to both exposure and risk that can result from
having only laboratory generated data. Protocols must be approved by
the Agency prior to the initiation of the study. Details for developing
protocols are available from the Agency.

Q. Monitoring of Representative U.S. Waters

    The Agency is proposing to conditionally require monitoring of
representative U.S. waters for all antimicrobial use patterns. This
would include freshwater, saltwater, surfacewater, and groundwater.
This would codify current practices.
    The Agency would use a weight-of-evidence approach taking into
account factors such as available monitoring data; the vulnerability of
the freshwater, estuarine, or marine water resources; and the
persistence and fate of the pesticide active ingredient (or degradate).
Protocols must be approved by the Agency prior to the initiation of the
study. Details for developing protocols are available from the Agency.
    Based on past experience, the Agency believes that these monitoring
data would be required only for a very small number of antimicrobial
pesticide registrations. Monitoring for tributyltin antifoulants of the
near coastal waters of the United States including the Great Lakes was
required under the Organotin Anti-fouling Paint Control Act of 1988. In
1989, pesticide registrants were required to provide these monitoring
data under FIFRA section 3(c)(2)(B). These tributyltin antifoulants
data are the only monitoring of representative U. S. waters that has
been required for an antimicrobial to date.

R. Special Leaching Study

    The Agency is proposing to require special leaching studies for
antifoulant paints and coatings, and wood preservatives. Part 161 is
not explicit in the data that are currently required because those use
patterns are not delineated sufficiently for antimicrobial pesticide
chemicals. This proposal would codify the Agency's current practices.
These studies are needed because leaching from treated materials is the
primary source of environmental exposure to antifoulants and wood
preservatives. These studies would provide basic information about the
availability of the pesticide to the environment, and would be used to
perform exposure and risk assessments.
    There is no OPPTS Harmonized guideline for these studies. The
applicant may perform the study with a protocol of their choice, or may
use the American Wood Preservers' Association's (AWPA) Standard Method
of Determining the Leachability of Wood Preservatives (AWPA E11-97),
AWPA's Standard Method for Determining the Leachability of Wood
Preservatives in Soil Contact (AWPA E20-04), and the American Society
for Testing and Materials (ASTM) Standard Test Method for Organotin
Release Rates of Antifouling Coating Systems in Sea Water (ASTM D5108-
90), or their equivalents. As stated in the test notes to the table in
proposed Sec.  158.2280, prior approval by the Agency of studies
conducted according to AWPA E11-97 or ASTM D5108-90 is not required.
However, all studies that would be conducted according to other
protocols must be approved by the Agency prior to the initiation of the
study. Details for developing protocols are available from the Agency.

XIII. Nontarget Organisms Data Requirements

A. Nontarget Organisms Data Requirements for Antimicrobials

    EPA proposes to adapt the basic nontarget organism data types
(Sec.  158.2240) as listed in subpart G of current part 158 to support
applications for antimicrobial products. EPA proposes to modify the
applicability of those requirements to antimicrobials to reflect
differing risks and levels of exposure. Part 161 is not explicit in the
data that are currently required because those use patterns are not
delineated sufficiently for antimicrobial pesticide chemicals. The
proposed table, in Sec.  158.2240, will provide greater transparency
and clarity.
    Ecological effects testing includes short-term, acute, subacute,
chronic, and reproduction studies, which progress from laboratory tests
to applied field tests. These data allow the Agency to determine if the
standard for registration is met and whether precautionary label
statements concerning toxicity or potential adverse effects to
nontarget organisms are necessary.
    The Agency is proposing to use a tiered system of ecological
effects testing to assess the potential risks of pesticide uses to
nontarget animals (aquatic and terrestrial vertebrates and
invertebrates) for antimicrobial pesticide chemicals. For the first
tier of testing EPA proposes to require for all antimicrobial
pesticides three types of acute ecological effects studies.
     Avian acute oral LD50.
     Acute freshwater fish LC50.
     Acute freshwater invertebrates EC50.
    These acute studies measure toxicity in representative species of
the nontarget species most likely to be adversely affected and allow
EPA to develop precautionary labeling. Such labeling includes
statements such as ``This product is extremely toxic to birds'' or
``This product is toxic to fish.'' These statements provide needed
information in case of unintended or co-incident exposure to
antimicrobials, such as a transportation accident. And, in fact, these
studies are currently required for an application for registration.
    These first tier data would be required for all antimicrobial use
patterns and performed with the technical grade active ingredient
(TGAI). Higher-tiered data would be required when the appropriate
trigger in Sec.  158.2240 is met. For instance, results from these
first tier studies may indicate the need for acute toxicity testing in
an additional species, or higher-tiered studies to assess hazard

to other species or in other parts of the environment. Other factors,
such as, toxicity, persistence, and/or potential for bioaccumulation,
may indicate the need for higher-tiered ecological effects and
environmental fate data. All typical end-use product (TEP) testing is
considered to be higher tier. An applicant must carefully consider
whether studies listed in the higher tier data requirements are
required for registration of his product and should consult with the
Agency, as needed.
    The Agency has divided the antimicrobial pesticides into two groups
for determining ecological effect data requirements, based on their
expected environmental exposure. The two groupings are the same
groupings used for environmental fate data requirements: Low and high
environmental exposure groupings. (see Unit XI.B of this preamble.)

B. The Low Environmental Exposure Grouping

    The use patterns within this grouping are the same as those
described in Unit XI.B. of this preamble for environmental fate data
requirements. As previously discussed in this Unit, EPA proposes to
require a first tier of three ecological effects studies for all
antimicrobials. These three acute ecotoxicity studies in combination
with the screening-level environmental fate assessment proposed to be
required for assessing the impacts of antimicrobial pesticides on
WWTPs, are the initial studies for environmental modeling for risk
assessment purposes. For the low environmental exposure grouping,
higher-tiered ecotoxicity studies are conditioned on a weight-of-
evidence evaluation of the results of the tier one ecotoxicity studies
and/or the results of the screening-level environmental fate
assessment. Thus, the studies described in Unit XIII.F., G., I., J.,
K., L., and M. could be triggered.

C. The High Environmental Exposure Grouping

    As with the environmental fate data requirements, the high exposure
environmental group consists of the once-through industrial processes
and water systems, antifoulant paints and coatings, aquatic areas, and
wood preservatives. These uses either occur outdoors, discharge
effluent directly to the outdoors, or result in materials treated with
antimicrobials (e.g., wood preservatives and antifoulants) being placed
in the environment, thereby leading to potentially significant
environmental exposure. For the high environmental exposure grouping,
EPA proposes to require three first tier ecological effects studies and
depending on the use pattern, other ecotoxicity studies such as avian
studies and TEP testing. The Agency may require additional ecotoxicity
studies based on the results of these studies or on other information.

D. Acute Avian Oral Toxicity

    In 40 CFR part 161 acute avian studies are conditionally required
for ``indoor'' uses of antimicrobials, and are required for aquatic
uses of antimicrobials. (The indoor part 161 use pattern is being
considered by EPA to be similar to the low environmental exposure
grouping.) The Agency is proposing to require submission of acute avian
LD50 toxicity studies for all antimicrobial use patterns.
These studies are needed as part of the tier one ecotoxicity testing,
and as previously explained are used to develop precautionary labeling.
    Testing in one avian species is required for the low environmental
exposure grouping. The shift from CR to R for the low environmental
exposure grouping would expand the number of use patterns for which
this study is required.
    For antimicrobial chemicals, the Agency considers the aquatic use
pattern in part 161 to include the following antimicrobial use
patterns: Once-through industrial processes and water systems,
antifoulant paints and coatings, and aquatic areas. Therefore, the
Agency proposes to continue its current requirement for acute avian
oral acute toxicity studies for these uses. For wood preservatives
these studies have been required on a case-by-case basis; therefore,
this proposal would codify current practices.
    As with the data requirements for conventional pesticide chemicals,
the Agency is proposing to change the testing requirement from one
species to two species for all antimicrobial use patterns except the
low environmental exposure grouping. The change to two species is
consistent with the Agency's current practices.
    The species proposed in this proposal differ from those in the
requirements for conventional pesticides. Many conventional chemicals
are applied outdoors and are considered to be terrestrial uses. For
antimicrobials the Agency is proposing that the testing be conducted
with a waterfowl species and an upland game bird species. The selection
of waterfowl and upland game species is consistent with the current
submissions by registrants of antimicrobial products and reflects the
data needed for the many indoor and aquatic uses of antimicrobials.

E. Acute Aquatic Toxicity Studies

    The Agency is proposing to require acute aquatic toxicity studies
(LC50 fish and EC50 invertebrate) for all
antimicrobial uses. These studies are needed as part of the tier one
ecotoxicity testing, and as previously explained are used to develop
precautionary labeling.
    1. Tier 1 testing. In part 161, acute aquatic toxicity studies are
conditionally required for ``indoor'' uses of antimicrobials, and are
required for aquatic uses of antimicrobials.
    For antimicrobial chemicals, the Agency considers the aquatic use
pattern in part 161 to include the following uses: Once-through
industrial processes and water systems, antifoulant paints and
coatings, and aquatic areas. Therefore, the Agency proposes to continue
its current requirement for two acute aquatic fish toxicity studies
(one warm water and one cold water species) and one invertebrate
toxicity study for these use patterns. For wood preservatives these
three studies have been required on a case-by-case basis; therefore,
this proposal would codify current practices.
    For the low environmental exposure grouping, the Agency is
proposing to require the acute freshwater fish toxicity study in one
species, either a warm water or a cold water species. Testing on a
second species is required if the active ingredient or principal
transformation products are stable in the environment or if the
LC50 in the first species tested is greater than 1 part per
million (ppm) or 1 milligram/liter (mg/L). This would codify existing
practices. Additionally, the shift from CR to R for the low
environmental exposure grouping (which contains many of the ``indoor''
uses) would also codify current practices.
    2. TEP testing. Typical End-Use Product (TEP) testing is proposed
for both the acute freshwater fish and invertebrate toxicity studies.
This is an existing requirement according to the test notes to the
table in Sec.  161.490.

F. Avian Dietary Toxicity

    Currently in part 161 an avian dietary LC50 study is
conditionally required for the greenhouse and indoor use patterns and
required for all other use patterns. Today the Agency is proposing to
continue this existing requirement by requiring the avian dietary study
for aquatic areas and conditionally requiring the study for all other
antimicrobial use patterns.

G. Avian Reproduction

    The Agency has adapted the current data requirements in part 161
for avian

reproduction testing to determine the avian reproduction data
requirements for antimicrobial chemicals. An avian reproduction study
is conditionally required for aquatic uses in part 161.
    The Agency is proposing to require the avian reproduction study for
the antimicrobial aquatic areas use pattern. The proposed change from
conditionally required to required is consistent with the Agency's
current practices.
    For all other antimicrobial use patterns, the Agency is proposing
to conditionally require the avian reproduction study. For wood
preservatives this study has always been considered when EPA made its
case-by-case determinations on the data needed for risk assessment;
therefore, this proposal would codify the current practices used for
wood preservatives. Since part 161 conditionally requires this testing
for ``aquatic uses,'' the Agency's proposal continues the existing data
requirement for the once-through industrial processes and water
systems. Since the testing is also proposed to be conditionally
required for the low environmental exposure grouping, this would expand
the number of use patterns for which these studies are conditionally
required.

H. Acute Estuarine and Marine Study

    Acute estuarine and marine toxicity studies are performed on three
species: An estuarine/marine mollusk, an estuarine/marine invertebrate,
and an estuarine/marine fish. These studies measure toxicity in
representative estuarine and marine species of the nontarget species
most likely to be adversely affected.
    1. TGAI testing. The Agency is proposing to require these three
acute estuarine and marine studies for antifoulant paints and coatings,
and conditionally require these studies for wood preservatives. This
would codify the Agency's current practices.
    Testing for all other antimicrobial use patterns would also be
conditionally required. The Agency is proposing in part 158, subpart W
to use the same conditionalities (as described in the test notes) for
requiring these studies as in part 161, i.e. the testing is required if
residues from the parent compound and/or transformation products are
likely to enter the estuarine/marine environment.
    Part 161 conditionally requires this testing for ``aquatic uses.''
Therefore, the Agency's proposal continues the existing data
requirement for the once-through industrial processes and water
systems, and aquatic areas. Since the testing is also proposed to be
conditionally required for the low environmental exposure grouping,
this would expand the number of use patterns for which these studies
are conditionally required.
    2. TEP testing. For the acute estuarine and marine studies, TEP
testing is proposed to be conditionally required for the low
environmental exposure grouping, once-through industrial processes and
water systems, and aquatic areas. This is an existing requirement
according to the table in Sec.  161.490.

I. Fish Early Life Stage and Aquatic Invertebrate Life-Cycle Study

    The Agency proposes in Sec.  158.2240 to require both a fish early
life stage and an aquatic invertebrate life-cycle study for once-
through industrial processes and water systems, antifoulant paints and
coatings, and aquatic areas. For these use patterns this would codify
current practices.
    The Agency also proposes to conditionally require both studies for
the low environmental exposure grouping. This would expand the number
of use patterns for which the test is conditionally required.
    The Agency proposes to conditionally require both studies for wood
preservatives. The studies would be required if pesticide residues from
treated wood would be likely to enter freshwater or estuarine/marine
environments, as determined by the Agency.
    Currently, in part 161 only one of these studies is conditionally
required. Part 161 requires the submission of either the fish early
life stage or the aquatic invertebrate life-cycle study, based on the
more sensitive of the two species, as determined by the acute
ecotoxicity studies. However, since both fish and invertebrates may be
exposed when an antimicrobial pesticide enters natural waters, the
Agency now believes both studies are needed. Neither study would
adequately substitute for the other. While data from acute invertebrate
and acute fish studies would be available, EPA does not believe that
these acute studies would predict chronic sensitivity.
    For the low environmental exposure grouping the requirements are
triggered if antimicrobial pesticide residues from the parent compound
and/or transformation products are likely to enter freshwater or
estuarine/marine environments, as determined by the Agency. For wood
preservatives the requirements are triggered if antimicrobial pesticide
residues from the parent compound, transformation products, and/or
leachates from preservative-treated wood are likely to enter freshwater
or estuarine/marine environments, as determined by the Agency.

J. Fish Life Cycle

    Currently, this existing data requirement is conditionally required
for all antimicrobials except ``indoor'' uses in part 161. The Agency
is now proposing to expand this conditional requirement to all
antimicrobial use patterns.
    The fish life cycle study is a two generation reproductive study in
fish that can characterize a number of sensitive life stages. Just as
with conventional pesticide chemicals, it is triggered on the results
of the fish early-life stage or invertebrate life cycle test, or other
information indicating the reproductive physiology of fish may be
affected. For the low environmental exposure grouping, the screening-
level fate assessment would also inform the determination to require
this study. If the antimicrobial is not degraded by the processes in
the WWTP and is in the effluent released to surface water, then this
study may be required.

K. Aquatic Organisms, Bioavailability, Biomagnification Toxicity Tests

    This data requirement is composed of three studies: The oyster
bioconcentration factor, the fish bioconcentration factor, and the
aquatic food chain transfer. All three studies are not needed for every
antimicrobial. The most commonly submitted study is the fish
bioconcentration factor.
    Currently, these studies are conditionally required for all
antimicrobials except ``indoor'' uses in part 161. The Agency is now
proposing to expand this conditional requirement to all antimicrobial
use patterns. For the low environmental exposure grouping, the
screening-level fate assessment would also inform the determination to
require this study. If the antimicrobial is not degraded by the
processes in the WWTP and is in the effluent released to surface water,
then this study may be required.
    For antimicrobials that have the potential to reach freshwater or
saltwater, these studies are needed to identify those antimicrobials
that could concentrate in various aquatic taxa. EPA is proposing to
clarify in the test notes the three specific circumstances under which
the study is not required. These three circumstances are the same as in
the final rule for conventional pesticide chemicals.

L. Simulated or Actual Field Testing for Aquatic Organisms

    For all antimicrobial use patterns, the Agency is proposing to
conditionally require simulated or field studies for aquatic organisms.
These studies would be triggered when under actual use conditions
significant impairment of nontarget aquatic organisms is likely to
occur in the natural environment. This proposal would codify current
practices.
    The Agency currently determines whether simulated or field studies
are required for antimicrobials on a case-by-case basis, considering
information such as:
     The pesticide's intended use.
     The pesticide's use rates.
     The pesticide's toxicity.
     The pesticide's physical and chemical properties.
     The parent compound's environmental fate characteristics
and transformation products (such as metabolites and degradation
products).
     Nontarget organisms likely to be exposed.
     Likelihood of exposure.
    As with conventional pesticides, the Agency is proposing to require
independent laboratory validation of the environmental chemistry
methods used to generate the data associated with this study.

M. Sediment Testing

    The Agency is proposing to require acute invertebrate sediment
testing, both freshwater and marine, for antifoulant paints and
coatings and to conditionally require these studies for once-through
industrial processes and water systems, wood preservatives, and aquatic
areas. This would codify current practices. Additionally, EPA proposes
to expand the conditional requirement to all other antimicrobial use
patterns. This study would be triggered based on the antimicrobials
presence in the water column (for example when released from a WWTP),
the potential to sorb to sediment, and the persistence of the
antimicrobial.
    The Agency is proposing to conditionally require chronic
invertebrate sediment testing, both freshwater and marine, for all
antimicrobial use patterns. This study is triggered by the same
criteria as the acute sediment study, but would be of longer duration
as determined by the persistence of the antimicrobial. This conditional
requirement would codify current practices for the high environmental
exposure grouping, and would then expand the requirement to the low
environmental exposure grouping.
    Testing of aquatic organisms exposed to treated sediments allows
EPA to assess the effects of sediment-bound pesticide residues in
aquatic environments. The effects of sediment-bound pesticides (or
their degradates) on aquatic environments cannot be accurately assessed
from bioassays on compounds suspended in the water column alone. For
example, lipophilic or hydrophobic chemicals can dissipate from the
water column, but may remain in the aquatic environment adsorbed to
sediment. As discussed in the proposed rule for conventional pesticides
(70 FR 12275) sediment-bound pesticides may differ significantly from
pesticides in solution, showing different physical, chemical, and
biological properties, chemical partitioning, bioavailability,
concentrations in interstitial or pore water, exposure from sediment
ingestion and possible manifestations of food chain effects. By serving
as a potential pesticide sink, exposure to these compounds may lead to
significant environmental risk to a wide variety of fish and aquatic
invertebrates which live and feed at the bottom of a lake or stream.
Sediment toxicity testing is needed to assess the bioavailability of a
sediment-bound compound and to characterize the possible impact to
sediment-dwelling benthic organisms.
    Once the Agency determines or extrapolates that the use pattern has
the likelihood for chemical exposure to an aquatic system, then the
available information on the adsorption of the chemical is reviewed. If
the Agency determines that the antimicrobial meets one or more of the
criteria for adsorption, then the available information on persistence
of the chemical is reviewed. If one or more of the criteria for
persistence are met, then a sediment study is required. Persistence
(half-life of the pesticide in sediment) drives the decision regarding
whether the acute or chronic study is conducted.
    Before designing the protocol, consultation with the Agency is
needed if the applicant is uncertain as to which length of study is
appropriate. For certain antimicrobials that are highly persistent,
only the chronic study may be required. Protocols must be approved by
the Agency prior to the initiation of the study. Details for developing
protocols are available from the Agency.

N. Honeybee Protection

    The current data requirements for testing pesticide toxicity to
honeybees at Sec.  161.590 require the honeybee acute contact
LD50 study when honeybees are likely to be exposed. The
Agency proposes to conditionally require the acute study for wood
preservatives and the low environmental exposure grouping. Since the
study would be required only for uses involving treatment of beehives,
empty or occupied, and since there are few such uses for
antimicrobials, this study would be infrequently required. This study
may not be required if the use pattern (as described on the label)
prohibits fumigating or spraying beehives.
    Since beehives can be constructed of materials that have been
treated with antimicrobials, the Agency proposes to conditionally
require a study to determine the toxicity of treated wood and other
materials to bees. This study must be conducted in a manner similar to
that of the Honey Bee Toxicity of Residues on Foliage. This would
codify current practices. Protocols must be approved by the Agency
prior to the initiation of the study. Details for developing protocols
are available from the Agency.

XIV. Plant Protection Data Requirements

A. Plant Protection Data Requirements

    EPA proposes to adapt the basic nontarget plant protection data
types as listed in 40 CFR part 158, subpart G to support applications
for antimicrobial products. EPA proposes to modify the applicability of
those requirements to antimicrobials to reflect differing risks and
levels of exposure. Part 161 is not explicit in the data that are
currently required because those use patterns are not delineated for
antimicrobial pesticide chemicals. The proposed table in Sec.  158.2250
will provide greater transparency and clarity.
    Plants represent the most basic component of any functioning
ecosystem by providing oxygen and a food source for aquatic and
terrestrial animals. Therefore, it is important to determine the
toxicity of the antimicrobial to plants. The data obtained from these
studies will be used to conduct nontarget plant risk assessments. For
aquatic environments such an assessment could include an effluent from
a wastewater treatment plant being released into the environment. For
terrestrial environments such an assessment could include wood
preservatives in contact with soil, land-application of biosolids, or
antimicrobials that partition to soil and sediment.

B. Requirement for Tier II Testing for Antimicrobials

    The Agency's guidelines for conducting nontarget plant protection

studies specify two types of tests: Single-dose studies (referred to in
the guidelines as Tier I tests) and multiple-dose studies (Tier II).
Usually, the applicant would conduct the single-dose studies first, and
then, based on the results of the single-dose studies, proceed to the
multiple-dose studies, which evaluate the effects of multiple dosage
levels on plant growth and are used to determine acute toxicity levels
in comparison with environmental concentrations. Such studies are used
to estimate the risk to nontarget plants and endangered plant species.
    Many antimicrobial pesticides are used to control plant pests such
as algae in industrial processes (paper making, cooling towers,
wastewater, sewage water treatment), and residential uses (swimming
pools, ornamental ponds, moss growing on roofs). Some antifoulants,
ballast water treatments, and wood preservatives are also intended to
control plant pests. Therefore, antimicrobial pesticides used for plant
pest control are expected to be phytotoxic to nontarget plants once
released into terrestrial or aquatic environments.
    Accordingly, for all antimicrobial use patterns, the Agency is
proposing only to require multiple-dose studies, which is consistent
with the testing of certain phytotoxic conventional chemicals such as
herbicides which also start at Tier II. In part 161, for most plant
studies, the Tier II study is conditionally required and the Tier I
study is required. For antimicrobials, EPA believes that the nontarget
plant studies have been interpreted in the context of, and consistent
with other phytotoxic chemicals, and this proposal would codify the
shift from the use of the Tier I study to a Tier II study.
    If the applicant is in possession of single-dose studies that the
applicant believes provide sufficient information, then the applicant
is encouraged to consult early in the application process with EPA. The
Agency can evaluate the information and inform the applicant as to the
sufficiency, or the need for multiple-dose studies. If the applicant
does not have any studies, then multiple-dose studies must be
conducted.

C. The Low Environmental Exposure Grouping

    The use patterns within this grouping are the same as those
described in the Unit XI.B. of this preamble for environmental fate
data requirements.

D. The High Environmental Exposure Grouping

    The use patterns within this grouping are the same as those
described in the Unit XI.B. of this preamble for environmental fate
data requirements.

E. Seedling Emergence (Tier II - Dose-Response)

    This terrestrial plant toxicity test is designed to evaluate
toxicity to germinating seedlings and their ability to survive after
chemical uptake from the surrounding soil. The Agency is proposing to
require this study for the high environmental exposure grouping. This
proposal would codify the shift from the use of the Tier I study to a
Tier II study and thereby would codify current practices.
    The Agency is also proposing to conditionally require the Tier II
study for low environmental exposure grouping based on the results of
the algal study. This would expand the number of use patterns for which
this study is conditionally required.

F. Vegetative Vigor (Tier II - Dose-Response)

    This terrestrial plant toxicity test is designed to evaluate