**Environmental Fate and Ecological Risk Assessment**

**for the Reregistration of**

**MCPB and MCPB Sodium for Use on Peas**

+----------------------+-----------------------------------------------+
|                      |                                               |
+----------------------+-----------------------------------------------+
| Marie Janson,        | ![](m                                         |
| Environmental        | edia/image1.wmf){width="0.3472222222222222in" |
| Scientist            | height="0.20972222222222223in"}               |
|                      |                                               |
| Alex Clem,           | United States Environmental Protection Agency |
| Environmental        |                                               |
| Scientist            | Office of Pesticide Programs                  |
|                      |                                               |
|                      | Environmental Fate and Effects Division       |
|                      |                                               |
|                      | Environmental Risk Branch I                   |
|                      |                                               |
|                      | Ariel Rios Building                           |
|                      |                                               |
|                      | 1200 Pennsylvania Ave., NW                    |
|                      |                                               |
|                      | Mail Code 7507C                               |
|                      |                                               |
|                      | Washington, DC 20460                          |
+----------------------+-----------------------------------------------+
| Reviewed and         |                                               |
| Approved by:         |                                               |
|                      |                                               |
| Ed Odenkirchen,      |                                               |
| SeniorScientist      |                                               |
|                      |                                               |
| Kevin Costello,      |                                               |
| Acting Branch Chief  |                                               |
|                      |                                               |
| Environmental Risk   |                                               |
|                      |                                               |
| Branch I             |                                               |
+----------------------+-----------------------------------------------+

**TABLE OF CONTENTS**

LIST OF TABLES iii

LIST OF FIGURES iv

I. EXECUTIVE SUMMARY 1

A. Nature of Chemical Stressor 1

B. Potential Risks to Non-target Organisms 2

C. Conclusions - Exposure Characterization 6

D. Conclusions - Effects Characterization 6

E. Uncertainties and Data Gaps 7

II\. PROBLEM FORMULATION 10

A. Stressor Source and Distribution 10

1\. Source and Intensity 10

2\. Physical/Chemical/Fate and Transport Properties 10

3\. Pesticide Type, Class, Mode of Action 14

4\. Overview of Pesticide Usage 15

B. Receptors 15

1\. Aquatic Effects 15

2\. Terrestrial Effects 15

3\. Ecosystems at Risk 16

C. Assessment Endpoints 16

D. Conceptual Model 16

1\. Risk Hypothesis 16

2\. Diagram 18

E. Analysis Plan 19

1\. Preliminary Identification of Data Gaps and Methods 20

2\. Measures to Evaluate Risk Hypotheses and Conceptual Model 21

III\. ANALYSIS 22

A. Use Characterization 22

B. Exposure Characterization 23

1\. Environmental Fate and Transport Study Summaries 23

2\. Measures of Aquatic Exposure 25

3\. Measures of Terrestrial Exposure 27

C. Ecological Effects Characterization 28

1\. Aquatic Effects Characterization 28

2\. Terrestrial Effects Characterization 33

IV\. RISK CHARACTERIZATION 40

A. Risk Estimation - Integration of Exposure and Effects Data 40

1\. Non-target Aquatic Animals and Plants 40

2\. Non-target Terrestrial Animals and Plants 42

**TABLE OF CONTENTS (CONT.)**

B. Risk Description 47

1\. Risks to Aquatic Organisms 47

2\. Risks to Terrestrial Organisms 47

3\. Review of Incident Data 51

4\. Federally Threatened and Endangered (Listed) Species Concerns 51

C. Description of Assumptions, Limitations, Uncertainties, Strengths and
Data Gaps 58

APPENDIX A: Environmental Fate Studies 59

APPENDIX B: Aquatic Exposure Model Results 69

APPENDIX C: Terrestrial Bird and Mammal Model Results 85

APPENDIX D: TerrPlant and AgDrift Model and Results 92

APPENDIX E: Ecological Effects Data 98

APPENDIX F: Data Requirements 104

APPENDIX G: Environmental Fate Bibliography 108

APPENDIX H: Ecotoxicity Bibliography 110

APPENDIX I: Locates Endangered Species 114

APPENDIX J: MCPA/MCPB Calculations Acute to Chronic Ratio Aquatic
Organisms\...\..... 137

**TABLE OF CONTENTS (CONT.)**

**LIST OF TABLES**

I.a. Summary of Environmental Risk Conclusions for Aquatic Organisms and
Plants

for label use application rate (1.5 ae). 3

I.b. Summary of Environmental Risk Conclusions for Terrestrial Organisms
and Plants

for label use application rate (1.5 ae) 4

I.c. Environmental Fate Data Requirements 7

I.d. Ecological Toxicity Data Requirements 8

II.a. Some Physical-Chemical and Other Properties of MCPB. 13

II.b. Some Physical-Chemical and Other Properties of MCPB Sodium 14

II.c. Use of MCPB and MCPB Sodium on Peas. 15

II.d. Risk Presumptions for Terrestrial Animals (birds and wild mammals)
19

II.e. Risk Presumptions for Aquatic Animals 19

II.f. Risk Presumptions for Terrestrial and Semi-Aquatic Plants 19

II.g. Risk Presumptions for Aquatic Plants 20

III.a. PRZM/EXAMS Input Parameters for MCPB 26

III.b. Estimated Environmental Concentrations (μg ae/L) of MCPB +
Metabolites in Surface Water(PRZM-EXAMS) from All Uses for Ecological
Assessment. 27

III.c. Estimated Environmental Concentrations (ppm ae) of MCPB Acid on
Terrestrial Food

Items from Use on Peas 27

III.d. Summary of Endpoints for MCPB Acute and Chronic Aquatic Toxicity
Studies for RQ Evaluation 30

III.e. Freshwater Fish Acute Toxicity for MCPB Sodium. 31

III.f. Freshwater Invertebrate Acute Toxicity for MCPB Sodium. 31

III.g. Non-target Aquatic Plant Toxicity for MCPB Sodium. 33

III.h. Avian Acute Oral Toxicity for MCPB Sodium. 34

III.i. Avian Acute Dietary Studies for MCPB Sodium. 34

III.j. Mammalian Acute Toxicity for MCPB. 35

III.k. Mammalian Chronic and Developmental/Reproductive Toxicity for
MCPB 36

III.l. Non-target Insects - Acute Contact. 37

III.m. Terrestrial Non-target Plant Toxicity. 39

IV.a. Summarized Acute Aquatic Organism Risk Quotients for MCPB Acid 40

IV.b. Summarized Acute Aquatic Plant Risk Quotients for MCPB Acid 41

IV.c. Summary of endpoints for MCPB acute terrestrial toxicity studies
42

IV.d. Avian Acute Risk Quotient Summary 43

IV.e. Mammalian Acute Risk Quotient Summary 44

IV.f. Mammalian Chronic Risk Quotient Summary 45

IVg. Summarized Terrestrial Plant Risk Quotients 46

IV.h. Distance of Disposition of MCPB Equivalent to Rates Tested in

Vegetative Vigor Study 50

IV.i. Summarized Data from LOCATES 58

Data Requirement Tables for MCPB 103

**TABLE OF CONTENTS (CONT.)**

**LIST OF FIGURES**

Figure II. a. Chemical structures of MCPB and MCPB sodium 13

Figure II. b. Conceptual Model 18

**I. EXECUTIVE SUMMARY**

**A. Nature of Chemical Stressor**

> *Use, Application Rate, Mode of Action*
>
> MCPB \[4-(2-methyl-4-chlorophenoxy)butyric acid\] is an acidic phenoxy
> herbicide that is currently registered only for use on peas (field,
> canned, and dried) to control or suppress Canada thistle and certain
> other broadleaf weeds. It is applied when the peas are tolerant to the
> herbicide, which is from the time of shoot emergence until about three
> leaf nodes before flowering (typically 6 to 12 nodes).
>
> MCPB is formulated as its sodium salt (sometimes designated as MCPB
> sodium), which can be applied once annually through direct aerial or
> ground spray. The maximum application rate for the salt is 1.6
> lbs/acre (1.79 kg/ha); or, in terms of acid equivalents (ae), this
> rate converts to 1.5 lbs/acre (1.68 kg/ha) of MCPB acid.
>
> Information from the published literature (Dexter et al. 1994, Heimann
> and Neman 1997) concerning the mode of action of phenoxy herbicides
> indicates that they are systemic growth regulating hormones that act
> at multiple sites in a plant to disrupt hormone (auxin) balance and
> protein synthesis. The result is plant growth abnormalities. Uptake of
> phenoxy herbicides is said to be primarily through the foliage, but
> root and seed uptake are also said to occur.
>
> *Environmental Fate Summary*
>
> Based on laboratory studies and physicochemical properties, MCPB is
> not volatile, not persistent, and not likely to bioconcentrate. Its
> acidic/anionic nature, physicochemical properties, and relatively low
> sorption to soil (average soil sorption coefficient of 0.85 mL/g),
> indicate that MCPB is prone to leach and runoff. Field dissipation
> studies are not available.
>
> In addition to MCPB, two by-products of its aerobic soil metabolism,
> although minor (\<10%) in concentration, are also of potential concern
> because of their chemical structural similarity to parent. These are:
> (1) MCPA \[(4-chloro-2-methylphenoxy)acetic acid\], which is another
> registered herbicide of the phenoxy class, and (2) the closely related
> CHPA-hexose conjugate \[(4-chloro-2-methylphenoxy)-2-β-glucopyranoside
> acetic acid\]. Chemical structures of these compounds are in
> Appendix A. In the single aerobic soil metabolism study available,
> these two compounds were each detected at average maxima of
> approximately 6-7% of applied radioactivity during the first 3 to 15
> days of incubation, with both decreasing to less than 2% by the end of
> a 120-day study. The only major identified transformation product was
> carbon dioxide.
>
> The MCPA metabolite, as previously documented in its USEPA
> Reregistration Eligibility Document (dated September 30, 2004) and
> evidenced in fate studies of MCPB, is similar to MCPB in all available
> characteristics. Although we do not have such information for the
> CHPA-hexose conjugate, based on its chemical structure, it is
> reasonable to assume that it also shares the same general chemical
> profile. As it so happens, because of their relatively minor presence
> and lack of persistence, whether we included or excluded these two
> metabolites had little influence on the overall risk assessment. Their
> inclusion makes negligible difference in terrestrial exposure and in
> acute aquatic exposure. Excluding the two metabolites from the longest
> (60 day) chronic aquatic exposure assessment results in a decrease in
> aquatic concentration of only approximately 10%, an amount well within
> the variation in natural processes and experimental error.
> Nevertheless, we included both metabolites in combination with parent
> MCPB as total toxic residues with a combined or overall half-life of
> 26 days, and assumed toxicities and environmental fate properties
> equivalent to parent.
>
> MCPB was essentially stable to hydrolysis (extrapolated half-life
> greater than 500 days based on a study lasting only 30 days), but
> photolyzed in laboratory water under optimal light exposure conditions
> with half-lives of approximately 2 to 3 days. Phototransformation
> products included 4 -(4-hydroxy-[o]{.underline}-tolyloxy)butyric acid;
> 2,4-dihyroxyphenyl formate; o-cresol; benzoic acid; and
> 2-hydroxyphenyl formate. Specific study information is not available
> concerning the fate of these products, and we have not included any
> potential effects of aqueous photolysis products in the risk
> assessment. However, based on their chemical structure, these are not
> expected to be persistent. Furthermore, should there be any concerns
> for toxicity, we can conclude that, either singly or in summation,
> these products would be in aquatic concentrations below the maximum
> concentrations estimated for parent. Additional exposure refinements
> could be pursued, if warranted by any toxicological concerns.

**B. Potential Risks to Non-target Organisms**

The risk assessment indicates the potential acute risks to non-target
terrestrial plants, birds, and mammals. Also, this risk assessment
indicates potential chronic (developmental/reproductive) risk to
mammals, and potential risks to endangered species from MCPB usage on
peas. Tables Ia and Table Ib summarize risks and uncertainties for
aquatic and terrestrial organisms and plants. No estuarine marine fish
or invertebrate data were submitted. Because peas may be planted near

estuarine marine environments this data would be of significant value
for the evaluation of estuarine marine organisms. Potential chronic
risks for aquatic organisms cannot be evaluated due to lack of submitted
data. Consequently, it is not possible to discount possible risks to
these organisms until further data is submitted.

**Table I.a. Summary of Environmental Risk Conclusions for Aquatic
Organisms and Plants for label use application rate (1.5ae/A)**

+------------------+---------------------------------------------------+
| **Assessment     | **Summarized Risk Characterization and Important  |
| Endpoint**       | Uncertainties**                                   |
+==================+===================================================+
| Acute Risk to    | No exceedences occurred for acute freshwater fish |
| Freshwater Fish  | ,acute restricted use or endangered species LOCs  |
|                  | for ground or aerial spray applications.          |
+------------------+---------------------------------------------------+
| Chronic Risk to  | No chronic freshwater fish toxicity data were     |
| Freshwater Fish  | submitted for the TGAI.                           |
|                  |                                                   |
|                  | Therefore, it is not possible to discount         |
|                  | possible chronic risks to freshwater fish until   |
|                  | further data is submitted.                        |
+------------------+---------------------------------------------------+
| Acute Risk to    | No exceedences occurred for acute freshwater      |
| Freshwater       | invertebrates ,acute restricted use or endangered |
| Invertebrates    | species LOCs for ground or aerial spray           |
|                  | applications.                                     |
+------------------+---------------------------------------------------+
| Chronic Risk to  | No chronic freshwater invertebrate toxicity data  |
| Freshwater       | were submitted for the TGAI.                      |
| Invertebrates    |                                                   |
|                  | Therefore, it is not possible to discount         |
|                  | possible chronic risks freshwater invertebrates   |
|                  | until further data is submitted.                  |
+------------------+---------------------------------------------------+
| Acute Risk to    | No acute estuarine/marine fish toxicity data were |
| Estuarine/Marine | submitted for the TGAI.                           |
| Fish             |                                                   |
|                  | Therefore, it is not possible to discount         |
|                  | possible acute and endangered species risks       |
|                  | estuarine/marine fish until further data is       |
|                  | submitted.                                        |
+------------------+---------------------------------------------------+
| Chronic Risk to  | No chronic estuarine/marine fish toxicity data    |
| Estuarine/Marine | were submitted for the TGAI.                      |
| Fish             |                                                   |
|                  | Therefore, it is not possible to discount         |
|                  | possible chronic risks estuarine/marine fish      |
|                  | until further data is submitted.                  |
+------------------+---------------------------------------------------+
| Acute Risk to    | No acute estuarine/marine invertebrate data was   |
| Estuarine/Marine | submitted for the TGAI. Therefore, it is not      |
| Invertebrates    | possible to discount possible acute and           |
|                  | endangered species risks estuarine/marine         |
|                  | invertebrates until further data is submitted.    |
+------------------+---------------------------------------------------+
| Chronic Risk to  | No chronic estuarine/marine invertebrate toxicity |
| Estuarine/Marine | data was submitted for the TGAI. Therefore, it is |
| Invertebrates    | not possible to discount possible chronic risks   |
|                  | estuarine/marine fish until further data is       |
|                  | submitted.                                        |
+------------------+---------------------------------------------------+
| Risk to Aquatic  | No exceedences occurred for acute non-endangered  |
| Vascular Plants  | aquatic vascular plants. Endangered vascular      |
|                  | plants can not be assessed due to non-discreet    |
|                  | NOEC value.                                       |
+------------------+---------------------------------------------------+
| Risk to Aquatic  | No exceedences occurred for acute non-endangered  |
| Non-vascular     | aquatic non-vascular plants.                      |
| Plants           |                                                   |
+------------------+---------------------------------------------------+

**Table I.b. Summary of Environmental Risk Conclusions for Terrestrial
Organisms and Plants for label use application rate (1.5ae/A)**

+-----------------+----------------------------------------------------+
| **Assessment    | **Summarized Risk Characterization and Important   |
| Endpoint**      | Uncertainties**                                    |
+=================+====================================================+
| Acute Risk to   | Acute risk, acute restricted use and endangered    |
| Birds           | species LOCs were exceeded for 20 g and 100g       |
|                 | birds. Acute restricted use and endangered species |
|                 | LOCs were exceeded for 1000g birds.                |
+-----------------+----------------------------------------------------+
| Chronic Risk to | No chronic bird toxicity data were submitted for   |
| Birds           | MCPB.                                              |
|                 |                                                    |
|                 | However, the chronic bird study from MCPA was      |
|                 | substituted for MCPB.                              |
|                 |                                                    |
|                 | No exceedences occurred for chronic risk to birds. |
+-----------------+----------------------------------------------------+
| Acute Risk to   | No exceedences occurred for acute or acute         |
| Mammals         | restricted use mammal LOCs.. Endangered species    |
|                 | LOCs were exceeded for 15g and 35g mammals         |
+-----------------+----------------------------------------------------+
| Chronic Risk to | Chronic risk LOCs were exceeded in all weight      |
| Mammals         | classes(15g, 35g, and 1000g) of mammals            |
+-----------------+----------------------------------------------------+
| Terrestrial     | Acute non-endangered and acute endangered species  |
| Plants          | LOCs are exceeded for monocots and dicots from     |
|                 | both aerial and ground applications.               |
+-----------------+----------------------------------------------------+
| Non-target      | Based on acute contact toxicity studies on         |
| Insects         | honeybees, MCPB is classified as non-toxic to      |
|                 | these receptors.                                   |
+-----------------+----------------------------------------------------+

The results of this risk assessment indicate that MCPB applied at the
maximum application rate according to label directions, as a liquid
spray for ground or aerial applications, will impact non-target plants
for some distance from the application site. At the label application
rate of 1.5 lbs ae/acre, model-estimated RQs exceeded acute risk LOCs
for non-target monocots and dicots located in dryland and semi-aquatic
areas adjacent to treated areas, both as a result of combined runoff and
spray drift, and from spray drift alone. .

Risk quotients for birds exceed the acute risk LOC from consumption of
short grass (all avian weight classes), broadleaf forage/small insects
(20 g and 100 g birds) and tall grass (20 g birds) feed items. Because
these acute lethality risks were calculated based on a laboratory method
of dosing and not actual feeding habits in the field, they represent a
conservative estimation of risk The laboratory method is a gavage dose
which represents a very short-term high intensity exposure, whereas
dietary exposure may be of a more prolonged nature. The dietary approach
assumes that animals in the field are consuming food at a rate similar
to that of confined laboratory animals. The strength of this assumption
is uncertain, because energy content in food items differs between the
field and in the laboratory, as do the energy requirements of wild and
captive animals. However, because acute effects were observed in both
studies, including the dietary study at doses \> 569 ppm ae, acute risks
to avian species using the treated fields or inhabiting adjacent edge or
riparian communities could result from the labeled use of MCPB.

Assuming maximum and mean residue levels at the maximum application
rate, chronic risk LOCs were exceeded in all weight classes (15 g, 35 g,
and 1000g) of mammals for consumption of short grass, tall grass and
broadleaf forage/small insects. Assuming maximum residue levels at the
maximum application rate, chronic risk LOCs were exceeded in 15 g and
35g mammals for consumption of fruit and large insects. However, because
the chronic LOCs are exceeded for multiple food categories, potential
exposure may still be high enough to warrant concern. Based on effects
seen in the chronic mammalian toxicity studies, MCPB may be classified
as a potential endocrine disruptor. When the appropriate screening
and/or testing protocols being considered under the Agency's Endocrine
Disruptor Screening Program have been developed, MCPB may be subjected
to additional screening and/or testing to better characterize effects
related to endocrine disruption.

The preliminary risk assessment for endangered species indicates that
MCPB exceeds the endangered species LOCs for the single application per
year for peas grown with an application rate of 1.5 lbs ae/acre for the
following taxonomic groups:

0.  small 20g, medium 100g and large 1000 g birds feeding on short
    grass, tall grass, and broadleaf forage/small insects; small birds
    feeding on fruits pods seeds, and large insects

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0.  small 15g and medium 35g mammals feeding on short grass; small
    mammals (15 g) feeding on broadleaf forage/small insects.

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```
0.  non-target terrestrial plants - monocots and dicots adjacent to
    treated areas and semi-aquatic.

Information from LOCATES indicates that several species of birds,
mammals and plants are potentially affected by use of MCPB on peas.

Exposure to MCPB results in direct effects to plant species that could
result in effects at the higher levels of organization (i.e. population,
trophic level, community, ecosystem). Consequently, there may be a
concern for potential indirect effects to listed species dependent upon
birds that consume feed items contaminated with MCPB residues, such as
predatory birds and mammals. The guideline terrestrial plant studies
indicate direct adverse effects to seedling emergence as well as
non-lethal effects including brown leaf tips, necrosis, chlorosis, stem
tumors, leaf curl, and decrease in size. In the guideline aquatic
vascular plant studies, concentrations as low as 0.16 mg ae/L resulted
in chlorosis, curling, and decreased root formation in the plant. In
terrestrial and shallow-water aquatic communities, plants are the
primary producers upon which the succeeding trophic levels depend. If
the available plant material is impacted due to the effects of MCPB,
this may have negative effects not only on the herbivores, but
throughout the food chain. Also, depending on the severity of impacts to
the plant communities (edge and riparian vegetation), community
assemblages and ecosystem stability may be altered (i.e. reduced bird
populations in edge habitats; reduced riparian vegetation resulting in
increased light penetration and temperature in aquatic habitats).
Furthermore, reduction of upstream riparian vegetation that would
otherwise supply downstream habitats could result not only in a loss of
a significant component of food for aquatic herbivores and detritivores,
but also of habitat (i.e. leaf packs, materials for case-building for
invertebrates). This assessment of risk to aquatic receptors provides
toxicity data on freshwater systems only due to lack of submitted
estuarine/marine toxicity data.

The risk assessment indicates that there are no acute risks to fish,
fresh water aquatic invertebrates, algae or mammals. There were no
exceedances of the aquatic Acute Risk, Acute Restricted Use, and
Endangered Species LOCs for freshwater fish and aquatic invertebrates.
There were also no exceedances of the non-endangered Acute Risk LOC for
aquatic algae and vascular plants. Consequently, freshwater fish,
freshwater invertebrates, algae and vascular plants inhabiting surface
waters adjacent to an MCPB treated field would not be at risk for
adverse acute effects to growth and survival when exposed to residues in
surface runoff and spray drift as a result of ground and/or aerial spray
application. Acute Risk LOCs were not exceeded for mammals consuming
short grass, tall grass, broadleaf forage and small insects, fruit and
large insects, or seeds and pods with maximum or mean residue levels.
EFED currently does not quantify risks to terrestrial non-target
insects.

**C. Conclusions - Exposure Characterization**

Routes of exposure evaluated in this risk assessment focused on
deposition, runoff and spray drift from ground and aerial spray
applications of MCPB for peas. Based on the physical and chemical
properties as well as the laboratory fate studies, MCPB will
predominately exist in the ionic or salt form at ambient environmental
pHs. In addition, the only registered formulation for field application
is the MCPB sodium salt. MCPB salt is highly soluble (200,000 mg/L) in
water and mobile in aqueous environmental systems. MCPB degrades rapidly
via photolysis (half-life of 2.6 days) and is readily biodegraded in
aerobic and anaerobic soils; thus long term persistence in soils is not
likely. The low octanol-water partition coefficient (1.33) indicates
that MCPB would have a low tendency to bioaccumulate. In addition, based
on its tendency not to persist in the environment and the single
application per year, long-term persistence in the environment is not
likely. No information is available on aquatic biodegradation of MCPB.

A review of ground water and surface water monitoring data indicated no
detection of MCPB and there were no reported incidents from MCPB usage.

**D. Conclusions - Effects Characterization**

Available acute toxicity data indicate that MCPB sodium is moderately
toxic to rainbow trout and slightly toxic to bluegill sunfish and
daphnids. No toxicity studies have been conducted to determine potential
chronic effects to fish and aquatic invertebrates. Laboratory studies
indicate that MCPB is toxic to algae and aquatic vascular plant species,
based on observed adverse effects on growth and development.

Available acute toxicity data indicate that MCPB sodium is practically
non-toxic to bobwhite quail and mallard ducks in the diet. However, an
oral gavage study with bobwhite quail indicates that MCPB sodium was
moderately toxic. MCPB is classified as practically non-toxic to small
mammals on an acute oral basis. However, a 13-week chronic oral study in
dogs reported reproductive effects, including testicular and prostate
atrophy and curtailment of spermatogenic activity. In developmental
studies with rats and rabbits, maternal toxicity was observed at doses
ranging from 20 - 100 mg/kg/day (NOAEL rabbit = 5 mg ai/kg/day; 4.55 mg
ae/kg/day) and developmental effects were observed in rats at a dose of
100 mg/kg/day. An acute contact study indicates that MCPB sodium is
relatively non-toxic to honey bees. No toxicity studies have been
conducted to determine the effect of residues to pollinators. An MCPA
chronic bird study was substituted for MCPB which resulted in a NOAEC of
1000 mg/kg-diet.

Terrestrial plant toxicity studies indicate that MCPB sodium negatively
impacts seedling emergence and vegetative vigor in monocots and dicots.
Non-lethal effects included brown leaf tips, necrosis, decrease in size,
leaf curling, chlorosis, and stem tumors. Consequently, exposure to MCPB
presents a potential risk to non-target plants inhabiting edge habitats
adjacent to target fields and riparian vegetation along streams and/or
ponds in close proximity to sprayed fields.

**E. Uncertainties and Data Gaps**

There are a few areas of uncertainty in the terrestrial and the aquatic
organism risk assessments that could potentially cause an
underestimation of risk. First, MCPB chronic toxicity data for aquatic
organisms are not available. MCPB acute toxicity data for estuarine
marine fish and invertebrates are not available; thus the potential risk
to estuarine marine fish and estuarine marine invertebrates cannot be
precluded. Because the potential for risk to these taxa cannot be
evaluated, this risk assessment should be considered incomplete.

Additional uncertainty results from the lack of information and/or data
in several components of this ecological risk assessment. For instance,
this assessment accounts only for exposure of non-target organisms to
MCPB, but not to its degradates. Data are not available concerning the
fate and toxicity of the photolytic degradation products of MCPB. MCPA
is a product of anaerobic biodegradation in soil and this assessment
provides available toxicity data for MCPA that indicates that the
toxicity of MCPA acid is very similar to that of MCPB (Reregistration
Eligibility Decision for MCPA, 2004).

Tables I.c. and I.d.summarize data gaps and environmental fate and
ecological toxicity data requirements submitted respectively.

+-------+-------------------+--------+------------+------------------+
| **    |                   |        |            |                  |
| TABLE |                   |        |            |                  |
| I.c.  |                   |        |            |                  |
| of    |                   |        |            |                  |
| Env   |                   |        |            |                  |
| ironm |                   |        |            |                  |
| ental |                   |        |            |                  |
| Fate  |                   |        |            |                  |
| Data  |                   |        |            |                  |
| Requ  |                   |        |            |                  |
| ireme |                   |        |            |                  |
| nts** |                   |        |            |                  |
+=======+===================+========+============+==================+
| **    | **Data            | **MRID | **Study    | **Is more data   |
| Guide | Requirement**     | \#**   | Classi     | needed?**        |
| -line |                   |        | fication** |                  |
| \#**  |                   |        |            |                  |
+-------+-------------------+--------+------------+------------------+
| 161-1 | Hydrolysis        | 42     | Acceptable | no               |
|       |                   | 574301 |            |                  |
+-------+-------------------+--------+------------+------------------+
| 161-2 | Photodegradation  | 42     | Acceptable | no               |
|       | in Water          | 574302 |            |                  |
+-------+-------------------+--------+------------+------------------+
| 161-3 | Photodegradation  | 43     | Invalid    | no               |
|       | on Soil           | 829901 |            |                  |
+-------+-------------------+--------+------------+------------------+
| 161-4 | Photodegradation  | N/A    |            | no               |
|       | in Air            |        |            |                  |
+-------+-------------------+--------+------------+------------------+
| 162-1 | Aerobic Soil      | 43     | Acceptable | no               |
|       | Metabolism        | 247601 |            |                  |
+-------+-------------------+--------+------------+------------------+
| 162-2 | Anaerobic Soil    | 43     | Acceptable | no               |
|       | Metabolism        | 015501 |            |                  |
+-------+-------------------+--------+------------+------------------+
| 162-3 | Anaerobic Aquatic | No     |            | no               |
|       | Metabolism        | study  |            |                  |
|       |                   | sub    |            |                  |
|       |                   | mitted |            |                  |
+-------+-------------------+--------+------------+------------------+
| 162-4 | Aerobic Aquatic   | No     |            | (not at this     |
|       | Metabolism        | study  |            | time)            |
|       |                   | sub    |            |                  |
|       |                   | mitted |            |                  |
+-------+-------------------+--------+------------+------------------+
| 163-1 | Leaching-Adso     | 42     | Acceptable | no               |
|       | rption/Desorption | 693701 |            |                  |
|       |                   |        |            |                  |
|       |                   | 43     |            |                  |
|       |                   | 466401 |            |                  |
+-------+-------------------+--------+------------+------------------+
| 163-2 | Laboratory        | N/A    |            |                  |
|       | Volatility        |        |            |                  |
+-------+-------------------+--------+------------+------------------+
| 163-3 | Field Volatility  | N/A    |            |                  |
+-------+-------------------+--------+------------+------------------+
| 164-1 | Terrestrial Field | No     |            | yes              |
|       | Dissipation       | study  |            |                  |
|       |                   | sub    |            |                  |
|       |                   | mitted |            |                  |
+-------+-------------------+--------+------------+------------------+
| 164-2 | Aquatic Field     | N/A    |            |                  |
|       | Dissipation       |        |            |                  |
+-------+-------------------+--------+------------+------------------+
| 164-3 | Forestry          | N/A    |            |                  |
|       | Dissipation       |        |            |                  |
+-------+-------------------+--------+------------+------------------+
| 165-4 | Accumulation in   | N/A    |            |                  |
|       | Fish              |        |            |                  |
+-------+-------------------+--------+------------+------------------+
| 165-5 | Accumulation-     | N/A    |            |                  |
|       | aquatic           |        |            |                  |
|       | non-target        |        |            |                  |
+-------+-------------------+--------+------------+------------------+
| 166-1 | Ground Water-     | N/A    |            |                  |
|       | small prospective |        |            |                  |
+-------+-------------------+--------+------------+------------------+
| 166-2 | Groundwater -     | N/A    |            |                  |
|       | small             |        |            |                  |
|       | retrospective     |        |            |                  |
+-------+-------------------+--------+------------+------------------+
| 201-1 | Droplet Size      | N/A    |            |                  |
|       | Spectrum          |        |            |                  |
+-------+-------------------+--------+------------+------------------+
| 202-1 | Drift Field       | N/A    |            |                  |
|       | Evaluation        |        |            |                  |
+-------+-------------------+--------+------------+------------------+

+-------+-------------------+---------+------------+------------------+
| **    |                   |         |            |                  |
| TABLE |                   |         |            |                  |
| I     |                   |         |            |                  |
| .d.of |                   |         |            |                  |
| Ecolo |                   |         |            |                  |
| gical |                   |         |            |                  |
| Tox   |                   |         |            |                  |
| icity |                   |         |            |                  |
| Data  |                   |         |            |                  |
| Requ  |                   |         |            |                  |
| ireme |                   |         |            |                  |
| nts** |                   |         |            |                  |
+-------+-------------------+---------+------------+------------------+
| *     | **Data            | **MRID  | **Classi   | **Is more data   |
| *Guid | Requirement**     | \#**    | fication** | needed?**        |
| eline |                   |         |            |                  |
| \#**  |                   |         |            |                  |
+-------+-------------------+---------+------------+------------------+
| 71-1  | Avian acute oral  | 4       | Acceptable | No               |
|       | LD~50~            | 2560801 |            |                  |
|       |                   |         |            |                  |
|       | (bobwhite quail)  |         |            |                  |
+-------+-------------------+---------+------------+------------------+
| 71-2  | Avian acute       | 4       | Acceptable | No               |
|       | dietary LC~50~    | 2560802 |            |                  |
|       |                   |         | Acceptable |                  |
|       | (bobwhite quail)  | 4       |            |                  |
|       |                   | 2560803 |            |                  |
|       | (mallard duck)    |         |            |                  |
+-------+-------------------+---------+------------+------------------+
| 71-4  | Avian             | 4       | Acceptable | No               |
|       | reproduction      | 3505201 |            |                  |
|       |                   |         |            |                  |
|       | (bobwhite quail)  | MCPA    |            |                  |
|       |                   |         |            |                  |
|       | (mallard duck)    |         |            |                  |
+-------+-------------------+---------+------------+------------------+
| 72-1  | Freshwater fish   | 4       | Acceptable | No               |
|       | acute LC~500~     | 2532608 |            |                  |
|       |                   |         | Acceptable |                  |
|       | (rainbow trout)   | 4       |            |                  |
|       |                   | 2532601 |            |                  |
|       | (bluegill         |         |            |                  |
|       | sunfish**)**      |         |            |                  |
+-------+-------------------+---------+------------+------------------+
| 72-2  | Freshwater        | 4       | Acceptable | No               |
|       | invertebrate      | 2532602 |            |                  |
|       | acute EC~50~      |         |            |                  |
|       | (daphnia)         |         |            |                  |
+-------+-------------------+---------+------------+------------------+
| 72-3a | Estuarine/marine  | N/A     |            | Yes              |
|       | fish acute LC~50~ |         |            |                  |
|       | (sheepshead       |         |            |                  |
|       | minnow)           |         |            |                  |
+-------+-------------------+---------+------------+------------------+
| 72-3b | Estuarine/marine  | N/A     |            | Yes              |
|       | invertebrate      |         |            |                  |
|       | acute EC~50~      |         |            |                  |
|       |                   |         |            |                  |
|       | (eastern oyster)  |         |            |                  |
+-------+-------------------+---------+------------+------------------+
| 72-4a | Estuarine marine  | N/A     |            | reserved         |
|       | fish early life   |         |            |                  |
|       | stage             |         |            |                  |
+-------+-------------------+---------+------------+------------------+
| 72-4a | Freshwater fish   | N/A     |            | Yes              |
|       | early life stage  |         |            |                  |
|       |                   |         |            |                  |
|       | (fathead minnow)  |         |            |                  |
+-------+-------------------+---------+------------+------------------+
| 72-4b | Freshwater        | N/A     |            | Yes              |
|       | invertebrate life |         |            |                  |
|       | cycle (daphnia)   |         |            |                  |
+-------+-------------------+---------+------------+------------------+
| 72-4d | Estuarine/marine  | N/A     |            | reserved         |
|       | life cycle        |         |            |                  |
|       |                   |         |            |                  |
|       | (mysid)           |         |            |                  |
+-------+-------------------+---------+------------+------------------+
| 72-5  | Freshwater fish   | N/A     |            | reserved         |
|       | full life cycle   |         |            |                  |
+-------+-------------------+---------+------------+------------------+
| 72-7  | Aquatic Field     | N/A     |            | No               |
|       | Study             |         |            |                  |
+-------+-------------------+---------+------------+------------------+
| 81-1  | Acute mammalian   | 144801  | Acceptable | No               |
|       | oral LD~50~       |         |            |                  |
|       |                   |         |            |                  |
|       | (rat)             |         |            |                  |
+-------+-------------------+---------+------------+------------------+
| 82    | Mammalian chronic | 116345  | Acceptab   | No               |
| -1(a) |                   |         | le-minimum |                  |
|       | (dog)             | 116344  |            |                  |
| 82    |                   |         | Acceptable |                  |
| -1(b) | (rat)             |         | -minimum   |                  |
+-------+-------------------+---------+------------+------------------+
| 83-3  | Mammalian         | 4       | Acceptable | No               |
|       | Developmental     | 0865401 |            |                  |
|       |                   |         | Acceptable |                  |
|       | (rat)             | 4       |            |                  |
|       |                   | 0865402 |            |                  |
|       | (rabbit)          |         |            |                  |
+-------+-------------------+---------+------------+------------------+
| 83-4  | Mammalian         | N/A     |            | Yes              |
|       | Reproduction      |         |            |                  |
| MCPB  |                   |         |            |                  |
+-------+-------------------+---------+------------+------------------+
| 83-4  | Mammalian         | 4       | Acceptable | No               |
|       | Reproduction      | 0041701 |            |                  |
| MPCA  |                   |         |            |                  |
+-------+-------------------+---------+------------+------------------+
| 123   | Seedling          | 4       | Acceptable | No               |
| -1(a) | Emergence - Tier  | 2560804 |            |                  |
|       | II                |         |            |                  |
+-------+-------------------+---------+------------+------------------+
| 122   | Vegetative        | 4       | Acceptable | No               |
| -1(b) | Vigor - Tier I    | 2560804 |            |                  |
+-------+-------------------+---------+------------+------------------+
| 123   | Vegetative        | 4       | Acceptable | No               |
| -1(b) | Vigor - Tier II   | 2560804 |            |                  |
+-------+-------------------+---------+------------+------------------+
| 122-2 | Aquatic plant     | 4       | Acceptable | No               |
|       | algae             | 2532605 |            |                  |
|       |                   |         | Acceptable |                  |
|       | (green algae)     | 4       |            |                  |
|       |                   | 2532603 | Acceptable |                  |
|       | (blue-green       |         |            |                  |
|       | algae)            | 4       | Acceptable |                  |
|       |                   | 2532609 |            |                  |
|       | (diatom)          |         |            |                  |
|       |                   | 4       |            |                  |
|       | (marine diatom)   | 2532606 |            |                  |
+-------+-------------------+---------+------------+------------------+
| 123-2 | Aquatic plant     | 4       | Acceptable | No               |
|       | acute EC~50~      | 2532604 |            |                  |
|       |                   |         |            |                  |
|       | (duckweed)        |         |            |                  |
+-------+-------------------+---------+------------+------------------+
| 141-1 | Acute honey bee   | 4       | Acceptable | No               |
|       | contact LD~50~    | 2532607 |            |                  |
+-------+-------------------+---------+------------+------------------+
| 141-2 | Honey Bee Residue | N/A     |            | Yes              |
|       | on Foliage        |         |            |                  |
+-------+-------------------+---------+------------+------------------+
| 141-5 | Honey Bee Field   | N/A     |            | Yes              |
|       | Testing for       |         |            |                  |
|       | Pollinator        |         |            |                  |
+-------+-------------------+---------+------------+------------------+

> **II. PROBLEM FORMULATION**

The purpose of the ecological risk assessment (ERA) is to evaluate and
address ecological risks associated with the reregistration of the
herbicide MCPB \[4-(2-methyl-4-chlorophenoxy) butyric acid\] for use on
peas; including field, canned and dried peas. The current registration
allows nationwide use on peas to control Canada thistle and other
broadleaf weeds.

**A. Stressor Source and Distribution**

**1. Source and Intensity:** MCPB is a phenoxy herbicide that is
currently registered for use on peas (field, canned, and dried) to
control or suppress Canada thistle and certain other broadleaf weeds. It
is formulated only as its sodium salt (MCPB sodium). It is applied once
annually through direct aerial (fine-medium and coarse spray) or ground
spray application at a maximum rate of 1.6 lbs ai/acre (1.5 pounds acid
equivalent per acre). Exposure to MCPB can occur by ground deposition,
indirect spray drift, and surface water runoff.

**2. Physical/Chemical/Fate and Transport Properties:** A summary of
selected physical and chemical properties for MCPB and MCPB sodium are
presented below in Tables II.a and b, respectively. Section III.B.1 and
Appendix A have more detail on specific environmental fate studies.

> Only laboratory environmental fate studies are available for MCPB.
> Field dissipation studies are not available. No study data (laboratory
> or field) are available for biodegradation in water (aerobic or
> anaerobic aquatic metabolism). In the absence of aquatic
> biodegradation data, for simulation modeling purposes EFED substitutes
> soil metabolism data with adjustment factors to allow for natural
> substrate variation.
>
> As can be seen from Tables IIa and IIb, MCPB is an acidic compound
> (pKa values of 4.6 and 4.8). (This acid strength is comparable to that
> for acetic acid, which is the essential component present at a
> concentration of 5% in vinegar.) Because of its acidity, MCPB will
> exist predominately in the ionic (anionic) or salt form at typical
> environmental pHs. The calculated degree of ionization corresponding
> to MCPB's acid strength is greater than 99% at pH 7, and ranges from
> approximately 70% to 99.99+% from pH 5 to 9, respectively. In all
> formulations registered for field application, MCPB is added as its
> sodium salt, which has a solubility in water of approximately 200,000
> mg/L (200 g/L).
>
> The relatively low Henry's Law Constant and vapor pressure for MCPB
> and collateral evidence showing its absence in traps for volatile
> organic compounds in various laboratory studies indicate that it is
> non-volatile.
>
> Based on laboratory studies, MCPB biodegrades in soil. In the only
> soil tested for aerobic metabolism, MCPB had a half-life of
> approximately 18 days. The major identified transformation product was
> carbon dioxide. Two by-products of aerobic soil metabolism, although
> minor (\<10%) in concentration, are also of potential concern because
> of their chemical structural similarity to parent. These are: (1) MCPA
> \[(4-chloro-2-methylphenoxy)acetic acid\], which is another registered
> herbicide of the phenoxy class, and (2) the closely related
> CHPA-hexose conjugate \[(4-chloro-2-methylphenoxy)-2-β-glucopyranoside
> acetic acid\]. Chemical structures of these compounds are in
> Appendix A. In the single aerobic soil metabolism study available,
> these two compounds were each detected at average maxima of
> approximately 6-7% of applied radioactivity during the first 3 to 15
> days of incubation, with both decreasing to less than 2% by the end of
> a 120-day study.
>
> The MCPA metabolite, as previously documented in its USEPA
> Reregistration Eligibility Document (dated September 30, 2004) and
> evidenced in fate studies of MCPB, is similar to MCPB in all available
> characteristics. Although we do not have such information for the
> CHPA-hexose conjugate, based on its chemical structure, it is
> reasonable to assume that it also shares the same general chemical
> profile. As it so happens, because of their relatively minor presence
> and lack of persistence, whether we included or excluded these two
> metabolites had little influence on the overall risk assessment. Their
> inclusion makes negligible difference in terrestrial exposure and in
> acute aquatic exposure. Excluding the two metabolites from the longest
> (60 day) chronic aquatic exposure assessment results in a decrease in
> aquatic concentration of only approximately 10%, an amount well within
> the variation in natural processes and experimental error.
> Nevertheless, we included both metabolites in combination with parent
> MCPB as total toxic residues with a combined or overall half-life of
> 26 days, and assumed toxicities and environmental fate properties
> equivalent to parent. (For modeling purposes, in order to allow for
> natural variation in the microbiological activity of soils, EFED uses
> three times a single soil value as a reasonable upper confidence bound
> for an average half-life, which in this case is approximately
> 78 days).
>
> In the only soil tested for anaerobic metabolism, MCPB had a system
> half-life of approximately 11 days. (Again, for modeling purposes, in
> order to allow for natural variation in microbiological activity of
> soils, EFED uses three times a single soil value as a reasonable upper
> confidence bound for an average half-life, which in this case is
> approximately 34 days.) The major transformation product in the
> aerobic phase of this anaerobic soil metabolism study was again MCPA
> \[(4-chloro-2-methylphenoxy)acetic acid\]. Within experimental error,
> this product did not appear to form during the anaerobic phase.
>
> MCPB was essentially stable to hydrolysis (extrapolated half-life
> greater than 500 days based on a study lasting only 30 days), but
> photolyzed in laboratory water under optimal light exposure conditions
> with half-lives of approximately 2 to 3 days. \[When input directly
> into current EFED aquatic models, these photolysis half-lives
> translate into effective half-lives approximately 124 times longer
> (250 to 400 days) based on scenario water depths, clarity, and other
> factors.\] Phototransformation products included 4
> -(4-hydroxy-[o]{.underline}-tolyloxy)butyric acid; 2,4-dihyroxyphenyl
> formate; o-cresol; benzoic acid; and 2-hydroxyphenyl formate. Specific
> study information is not available concerning the fate of these
> products, and we have not included any potential effects of aqueous
> photolysis products in the risk assessment. However, based on their
> chemical structure, these are not expected to be persistent.
> Furthermore, should there be any concerns for toxicity, we can
> conclude that, either singly or in summation, these products would be
> in aquatic concentrations below the maximum concentrations estimated
> for parent. Additional exposure refinements could be pursued, if
> warranted by any toxicological concerns.
>
> Adsorption/desorption (batch equilibrium) of MCPB in four soils and
> one sediment indicate that MCPB is mobile. Mean adsorption
> coefficients (K~ads)~ measured for each of the soils were 1.69, 0.26,
> 0.65, and 0.78 mL/g (median of 0.72, average of 0.85 mL/g); respective
> textures of these soils were sandy clay loam, sand, sandy loam, and
> clay loam. The sediment was a sandy loam (pH of 5.95 and 2.85% organic
> carbon) for which the mean K~ads~ was 10.58 mL/g. Adsorption
> coefficients normalized for organic carbon (K~oc~) were 129.57, 47.91,
> 85.54, 31.27, and 371.17 mL/g organic carbon for the sandy clay loam,
> sand, sandy loam, and clay loam soils and sandy loam sediment,
> respectively (average K~oc~ for the five values of 130 mL/g organic
> carbon, median of 86 mL/g organic carbon). The study was not
> consistent with guidelines in that the soils used in the study were
> not the same as those used in the aerobic soil metabolism studies.
>
> Based on its acid nature and consistent correlations among relatively
> high solubility, relatively low octanol-to-water partitioning ratio
> (1.33 at pH 7), and relatively low sorption to soil, MCPB would be
> prone to leach to ground water and runoff to surface water. Judging
> from these factors and its lack of persistence in soil,
> bioconcentration of MCPB is not expected.

**Figure II. a. Chemical structures of MCPB and MCPB sodium** **MCPB**

![](media/image2.wmf){width="3.7583333333333333in"
height="1.320138888888889in"}

**MCPB Sodium**

![](media/image2.wmf){width="4.006944444444445in"
height="1.4166666666666667in"}

+--------------------------+--------------------------------------------+
| **TABLE II.a. Some       |                                            |
| Physical-Chemical and    |                                            |
| Other Properties of      |                                            |
| MCPB.**                  |                                            |
+==========================+============================================+
| CAS Name                 | 4-(2-methyl-4-chlorophenoxy)butyric acid   |
+--------------------------+--------------------------------------------+
| IUPAC Name               | 4                                          |
|                          | -                                          |
|                          | (4-chloro-[o]{.underline}-tolyloxy)butyric |
|                          | acid                                       |
+--------------------------+--------------------------------------------+
| CAS No                   | 94-81-5                                    |
+--------------------------+--------------------------------------------+
| PC Code                  | 019201                                     |
+--------------------------+--------------------------------------------+
| Empirical Formula        | C~11~H~13~ClO~3~                           |
+--------------------------+--------------------------------------------+
| Molecular Weight         | 228.6                                      |
+--------------------------+--------------------------------------------+
| Common Name              | MCPB                                       |
+--------------------------+--------------------------------------------+
| Formulated Product       | Thristrol                                  |
+--------------------------+--------------------------------------------+
| Pesticide Type           | Herbicide                                  |
+--------------------------+--------------------------------------------+
| Chemical Family          | Phenoxy                                    |
+--------------------------+--------------------------------------------+
| Color/Form               | Brown flakes; white crystalline solid      |
|                          | (purified technical - 99.5% pure)          |
+--------------------------+--------------------------------------------+
| Odor                     | Slightly phenolic                          |
+--------------------------+--------------------------------------------+
| Melting Point            | 101.5 - 103.0°C                            |
+--------------------------+--------------------------------------------+
| Flash Point              | Not flammable                              |
+--------------------------+--------------------------------------------+
| Relative Density         | 1.26 g/ml (at 20°C)                        |
+--------------------------+--------------------------------------------+
| Water Solubility (at     | 60.4 mg/L (purified technical substance in |
| 20°C)                    | purified water)                            |
|                          |                                            |
|                          | 29.9 mg/L at pH 4                          |
|                          |                                            |
|                          | 3.83 mg/L at pH 7                          |
|                          |                                            |
|                          | \> 250 g/L at pH 10 (Podall 2002)          |
+--------------------------+--------------------------------------------+
| Solubility in other      | n-Heptane 0.414 g/L at 20°C; Xylene 37.6   |
| solvents                 | g/L at 20°C                                |
|                          |                                            |
|                          | dichloromethane 69.9 g/L at 20°C; Methanol |
|                          | \>250 g/L at 20°C                          |
|                          |                                            |
|                          | n-Octanol 71.6g/L at 20°C; Acetone \>250   |
|                          | g/L at 20°C                                |
|                          |                                            |
|                          | Ethyl acetate 144 g/L at 20°C (Podall      |
|                          | 2002)                                      |
+--------------------------+--------------------------------------------+
| Vapor Pressure           | 4.0 x10^-7^ torr (for purified technical   |
|                          | at 25°C) (Podall 2002)                     |
+--------------------------+--------------------------------------------+
| Henry's Law Constant     | 3.42 x 10^-9^ atm x m^3^/mol; estimated at |
|                          | 25°C (Howard and Meylan, 1997)             |
+--------------------------+--------------------------------------------+
| pKa                      | 4.6 at 20°C (Podall 2002)                  |
+--------------------------+--------------------------------------------+
| log P~ow~                | 1.33 (at pH 7 and 20°C)                    |
|                          |                                            |
|                          | 3.45 (at pH 4 and 20°C)                    |
|                          |                                            |
|                          | -0.21 (at pH 10 and 20°C) (Podall 2002)    |
+--------------------------+--------------------------------------------+

Redraw to be configuration shown for MCPB; move Na to end of carboxyl
group; show Na with positive charge and COO with negative charge.

+---------------------+------------------------------------------------+
| **TABLE II.b. Some  |                                                |
| Physical-Chemical   |                                                |
| and Other           |                                                |
| Properties of MCPB  |                                                |
| Sodium.**           |                                                |
+=====================+================================================+
| CAS Name            | Sodium 4-(2-methyl-4-chlorophenoxy)butyrate    |
+---------------------+------------------------------------------------+
| IUPAC Name          | N/A                                            |
+---------------------+------------------------------------------------+
| CAS No              | 6062-26-6                                      |
+---------------------+------------------------------------------------+
| PC Code             | 019202                                         |
+---------------------+------------------------------------------------+
| Empirical Formula   | C~11~H~12~ClNaO~3~                             |
+---------------------+------------------------------------------------+
| Molecular Weight    | 250.65677                                      |
+---------------------+------------------------------------------------+
| Common Name         | MCPB sodium salt                               |
+---------------------+------------------------------------------------+
| Formulated Product  | Thristrol                                      |
+---------------------+------------------------------------------------+
| Pesticide Type      | Herbicide                                      |
+---------------------+------------------------------------------------+
| Chemical Family     | Phenoxy                                        |
+---------------------+------------------------------------------------+
| Color/Form          | Colorless liquid with phenolic odor            |
+---------------------+------------------------------------------------+
| Odor                | Slightly phenolic                              |
+---------------------+------------------------------------------------+
| Melting Point       | N/A                                            |
+---------------------+------------------------------------------------+
| Flash Point         | Not flammable                                  |
+---------------------+------------------------------------------------+
| Relative Density    | N/A                                            |
+---------------------+------------------------------------------------+
| Water Solubility    | 200,000 mg/L @ 25°C (WSSA 1994)                |
+---------------------+------------------------------------------------+
| Solubility in other | N/A                                            |
| solvents            |                                                |
|                     |                                                |
| (g/L at 20°C)       |                                                |
+---------------------+------------------------------------------------+

**3. Pesticide Type, Class, Mode of Action:** MCPB is a phenoxy
herbicide that is used for control of broadleaf weeds. Information from
the published literature (NDSU 1994, Heimann and Neman 1997) concerning
the mode of action of phenoxy herbicides indicates that they are
systemic growth regulating hormones that act at multiple sites in a
plant to disrupt hormone (auxin) balance and protein synthesis,
resulting in plant growth abnormalities.

Cell division is affected and can result in changes in cell size and
shape and the cessation

of tissue growth.

> Uptake of phenoxy herbicides is primarily through the foliage but root
> and seed uptake can also occur. It is then translocated to areas of
> new plant growth by the xylem and phloem..
>
> Damage may include petiole twisting (epinasty), fused petioles
> (trumpeting), crinkling and cupping of leaf margins, thickening and
> flattening of stems (fasciation), and proliferation and distortion of
> roots and flowering parts. Roots may lose the ability to take up soil
> nutrients and the xylem and phloem in stems may not be able to
> transport nutrients throughout the plant. The extent of damage is
> dependent upon the concentration and duration of exposure. Non-target
> plants that do not receive a lethal dose may continue to grow normally
> beyond the affected parts unless tissue damage occurs while the plant
> is immature, thus retarding terminal growth. Phenoxy herbicides are
> also known to affect photosynthesis and root absorption. Examples of
> sensitive or susceptible plants include cotton, tomatoes, grapes,
> corn, soybeans, sugarbeets, sugarcane, and ornamentals.

**4. Overview of Pesticide Usage:** MCPB sodium salt is currently
registered for use on peas (including field, canned, and dried), and no
other agricultural crop. It is used postemergent primarily to suppress
Canada thistle bud formation. MCPB is applied when the peas are tolerant
to the herbicide, from shoot emergence until about three leaf nodes
before flowering (typically 6 to 12 nodes). Canada thistle reduces pea
yields through competition and presents problems during harvesting. The
buds are difficult to remove from the harvested crop resulting in loss
of crop quality and profit to the grower. During the canning and/or
freeze processing of peas, the unopened Canada thistle buds contaminate
the product. Other target pests include buttercup, mustard,
lambsquarters, purslane, ragweed, smartweed, and pigweed. Table II.c.
summarizes the application rates from the various product labels for all
proposed applications.

+-----------+----------+---------+---------+---------+--------------+
| **TABLE   |          |         |         |         |              |
| II.c. Use |          |         |         |         |              |
| of MCPB   |          |         |         |         |              |
| and MCPB  |          |         |         |         |              |
| Sodium on |          |         |         |         |              |
| Peas.**   |          |         |         |         |              |
+-----------+----------+---------+---------+---------+--------------+
| **Crop**  | **P      | **Appl. | **Appl. | **Max   | *            |
|           | roduct** | Rate**  | Rate**  | \#**    | *Application |
|           |          |         |         |         | Methods**    |
|           |          | **(lb   | **(lb   | **Ap    |              |
|           |          | ai/A)** | ae/A)** | pl/Yr** |              |
+-----------+----------+---------+---------+---------+--------------+
| Peas      | T        | 1.6     | 1.5     | 1       | Spray/ground |
|           | histrol® |         |         |         | and aerial   |
|           | H        |         |         |         |              |
|           | erbicide |         |         |         |              |
+-----------+----------+---------+---------+---------+--------------+
| Peas      | Sodium   | 1.6     | 1.5     | 1       | Spray/ground |
|           | MCPB     |         |         |         | and aerial   |
|           | Solution |         |         |         |              |
+-----------+----------+---------+---------+---------+--------------+

There are two registered products: Thistrol® Herbicide (71368-5) and
Sodium MCPB Solution (71368-7). The registrants include A.H. Marks and
Company Ltd., Nufarm BV and Nufarm, Inc. The product label for Thistrol®
lists the active ingredient (23.5%) as sodium salt of
4-(2-methyl-4-chlorophenoxy) butyric acid and 76.5% inert ingredients
(not provided).

**B. Receptors**

**1.** **Aquatic Effects:** The emphasis of the risk assessment is to
address risk to non-target aquatic species that may be exposed to
residual MCPB and MCPB sodium. Spray drift and runoff to adjacent bodies
of water are the most likely sources of MCPB and MCPB sodium exposure to
nontarget aquatic organisms, including endangered and threatened
species. Aquatic organisms downstream from application areas could also
potentially be exposed.

**2.** **Terrestrial Effects:** Ground deposition and spray drift with
resulting residues on animal feed items are the most likely sources of
MCPB and MCPB sodium exposure to nontarget terrestrial organisms,
including endangered and threatened species. Additional sources of
exposure to MCPB sodium could be from water drunk from puddles in
treated fields, ingested from feathers or fur through preening or
grooming or from inhalation at the time of spraying. However, this
screening assessment only estimates potential dietary exposure.

Spray drift and runoff from treated fields present a potential exposure
route for non-target plants in edge habitats adjacent to target fields
and riparian vegetation along streams and/or ponds in close proximity to
sprayed fields.

**3. Ecosystems at Risk:** Because peas can be grown throughout the
country, a variety of ecosystems may be exposed. The crop profile for
Maryland peas indicates that peas are grown in estuarine watershed.
Other crop profiles such as Delaware suggest that MCPB may be used in
estuarine as well as freshwater environments. In terrestrial and
shallow-water aquatic communities, plants are the primary producers upon
which the succeeding trophic levels depend. If the available plant
material is impacted due to the effects of MCPB and MCPB sodium, this
may have negative effects not only on the herbivores, but throughout the
food chain. Also, depending on the severity of impacts to the plant
communities (i.e., edge habitats, algal biomass, riparian vegetation),
community assemblages and ecosystem stability may be altered (i.e.
reduced bird populations in edge habitats; reduced riparian vegetation
resulting in increased light penetration and temperature in aquatic
habitats). Furthermore, reduction of upstream riparian vegetation that
would otherwise supply downstream habitats could result not only in a
loss of a significant component of food for aquatic herbivores and
detritivores, but also of habitat (i.e. leaf packs, materials for
case-building for invertebrates).

**C. Assessment Endpoints**

The major assessment endpoints related to aquatic environments are:

> (a). Direct effects to survival, reproduction and growth of fish and
> aquatic invertebrates in the water column via acute and/or chronic
> toxicity.
>
> (b). Direct effects to growth and development of algae and vascular
> plants via acute toxicity.
>
> (c). Direct effects to endangered/threatened aquatic species via acute
> and/or chronic toxicity.

The major endpoints related to terrestrial environments at issue are:

> (a). Direct effects to growth and development of non-target plants.
>
> (b). Direct effects on survival, growth and reproduction of birds,
> mammals, and by extension amphibians and reptiles via acute and/or
> chronic toxicity.

**D. Conceptual Model**

**1. Risk Hypothesis:**

The Office of Pesticide Programs uses a screening risk hypothesis for
its initial risk assessments.

> *The risk hypothesis is that the use of MCPB in accordance with the
> label results in adverse effects on survival and/or fecundity of
> non-target terrestrial and/or aquatic animals; and that the use of
> MCPB according to the label results in adverse effects on survival,
> reproduction and/or growth on aquatic, semi-aquatic and terrestrial
> plants.*

**2. Diagram:** Based on an examination of the physical/chemical
properties of MCPB and MCPB sodium, the fate and disposition in the
environment, and mode of application (e.g., ground and aerial spray
application); a conceptual model (Figure II.b) was developed that
represents the possible relationships between the stressor, ecological
endpoints, and the measurement endpoints. Risk to non-target animals is
also possible from dermal contact or inhalation, but because these are
not considered in the risk assessment, they are not shown in the diagram
below.

**Figure II .b.** **Conceptual Model** Fig

![](media/image3.png){width="7.2652777777777775in"
height="6.713888888888889in"}

**E. Analysis Plan**

This screening assessment uses a risk quotient (ratio of exposure
concentration to effects concentration) approach to evaluate the
potential for adverse effects on non-target terrestrial and aquatic
animals. Calculated risk quotients are compared to predetermined
levels-of-concern (LOCs) to provide a preliminary indication of the
potential for risk. Although risk, in the context intended here, is
often defined as the likelihood and magnitude of adverse ecological
effects, the risk quotient-based approach does not provide a
quantitative estimate of likelihood and/or magnitude of an adverse
effect. Such estimates may be possible through a more refined,
probabilistic assessment.

Risk presumptions, along with the corresponding RQs, equations, and
LOC's are summarized in **Tables II-d to II-g.** The exposure estimates
in this screening assessment are derived using maximum label rates and
minimum application intervals for each use.

**Table II-d. Risk presumptions for terrestrial animals (birds and wild
mammals).**

  ----------------------- ----------------------- -----------------------
  **Risk Presumption**    **RQ**                  **LOC**

  Acute                   EEC^1^/(LC~50~ or       0.5
                          LD~50~/ft^2^ or         
                          LD~50~/day)             

  Acute Restricted Use    EEC^1^/(LC~50~ or       0.2
                          LD~50~/ft^2^ or         
                          LD~50~/day) (or LD50 \< 
                          50 mg/kg)               

  Acute Endangered        EEC^1^/(LC~50~ or       0.1
  Species                 LD~50~/ft^2^ or         
                          LD~50~/day)             

  Chronic Risk            EEC/NOEC                1
  ----------------------- ----------------------- -----------------------

^1^ abbreviation for Estimated Environmental Concentration (ppm) on
avian/mammalian food items

**Table II-e. Risk presumptions for aquatic animals.**

  ----------------------- ----------------------- -----------------------
  **Risk Presumption**    **RQ**                  **LOC**

  Acute                   EEC^1^/(LC~50~ or       0.5
                          EC~50~)                 

  Acute Restricted Use    EEC/(LC~50~ or EC~50~)  0.1

  Acute Endangered        EEC/(LC~50~ or EC~50~)  0.05
  Species                                         

  Chronic Risk            EEC/NOEC                1
  ----------------------- ----------------------- -----------------------

^1^EEC = (ppm or ppb) in water

**Table II-f. Risk presumptions for terrestrial and semi-aquatic
plants.**

  ----------------------- ----------------------- -----------------------
  **Risk Presumption**    **RQ**                  **LOC**

  Acute Risk              EEC^1^/EC~25~           1

  Acute Endangered        EEC/(EC~05~ or NOEC)    1
  Species                                         
  ----------------------- ----------------------- -----------------------

^1^ EEC = lbs ai/A

**Table II-g. Risk presumptions for aquatic plants.**

  ----------------------- ----------------------- -----------------------
  **Risk Presumption**    **RQ**                  **LOC**

  Acute High Risk         EEC^1^/EC~50~           1

  Acute Endangered        EEC/(EC~05~ or NOEC)    1
  Species                                         
  ----------------------- ----------------------- -----------------------

^1^ EEC = (ppb/ppm) in water

Three measures are used to evaluate the risk hypotheses developed in the
conceptual model for MCPB usage. First, the measures of exposure are
derived as estimated environmental concentrations (EECs) based on Prism
Exam model predictions and environmental fate data. Second, the measures
of effect characterize the assessment endpoints and are based on
toxicity data that describe the effects of MCPB on individuals and
species through terrestrial models such as; Trex (version 1.1), Agdrift
(version 2.01) and Terrplant version 1.0). Third, the measures of
ecosystem and receptor characteristics describe the attributes of the
receptors and/or ecosystems that may be affected by exposure to the
stressor (i.e. behavior and life history characteristics). This analysis
plan also identifies the data gaps and uncertainties for conducting the
risk assessment and suggests recommendations for new data collection.

**1. Preliminary Identification of Data Gaps and Methods:**
Environmental fate data are available concerning the hydrolysis and
photodegradation of MCPB in water, the biodegradation of MCPB in soil,
and the mobility of MCPB in soil. However, information is not available
concerning the fate of the aqueous phototransformation products. There
are no acceptable study data on soil photolysis and aerobic or anaerobic
aquatic biodegradation.

Toxicity studies are available to determine the potential acute effects
to fish and aquatic invertebrates; however, no toxicity studies have
been conducted to determine potential chronic effects to fish and
aquatic invertebrates. The following chronic studies have not been
submitted: early life-cycle fish study, full life-cycle fish study, and
full life-cycle aquatic invertebrate study.

Therefore, chronic risk to these taxa cannot be evaluated and the risk
assessment should be considered incomplete. Chronic risk to
non-endangered and listed aquatic animals cannot be dismissed.

Toxicity studies are available to determine the potential acute effects
to birds, mammals and honey bees and the potential
reproductive/developmental effects to mammals. MCPB residues may affect
the foraging behavior of herbivores (birds, mammals) and of pollinators.
However, data are not available to determine the potential exposure
levels from residues in foliage, flowers and seeds. The only residue
study (MRID 44754101) available examined residues on peas at harvest.
Therefore, the level of residues that occurred directly after
application (which would represent the highest concentration to which
animals could be exposed) was not specified. No toxicity studies have
been conducted to determine the effect of residues to pollinators. An
MCPA chronic bird study was substituted for MCPB which resulted in a
NOAEC of 1000 mg/kg-diet.

Spray drift presents a potential risk to non-target plants inhabiting
edge habitats adjacent to target fields and riparian vegetation along
streams and/or ponds in close proximity to sprayed fields.

However, no-effect levels in the vegetative vigor tests were not
established for terrestrial plants.

Also, the NOECs for aquatic plants were not determined. Therefore, the
magnitude of spray drift that would cause effects to plants is not
known.

Potential risk to estuarine/marine species cannot be determined because
studies were not submitted by the registrant.

**2. Measures to Evaluate Risk Hypotheses and Conceptual Model**

*Measures of Exposure*

Based on the conceptual model presented above, the potential exposure
pathways for aquatic species include runoff/leaching, spray drift, and
residues in sediments. The potential exposure pathways for terrestrial
species include ground deposition, runoff/leaching and spray drift
resulting in residues on non-target plants. The exposure assessment for
this risk assessment of MCPB will use Tier II models to provide a more
realistic characterization that reflects actual labeled use. The Tier II
PRZM/EXAMS models will be used to predict EECs in surface water. This
model provides peak concentrations in a variety of scenarios for ponds
adjacent to treated areas, and can be used to vary the level of spray
drift and surface runoff from a single large rain event. No
transformation products were considered in the aquatic assessment as the
environmental fate database was incomplete for degradates.

As part of the terrestrial assessment, EFED modeled exposure
concentrations of MCPB to nontarget terrestrial plants and animals
following the proposed application rates provided by the registrant. For
terrestrial birds and mammals, estimates of initial levels of MCPB
residues on various food items, which may be contacted or consumed by
wildlife, were determined using the Kenega-Fletcher nomogram followed by
a first order decline model TREX 1.1. Exposure concentrations for
nontarget plants were estimated using the TerrPlant 1.0 model. AgDrift
2.0.1 model provides further refinement of spray drift dispersion and
deposition to terrestrial plants located in proximity to treated fields.

*Measures of Effect*

Measures of effect are obtained from a suite of registrant-submitted
guideline studies conducted with a limited number of surrogate species.
The test species are not intended to be representative of the most
sensitive species, but rather were selected based on their ability to
thrive under laboratory conditions. Consistent with EPA test guidelines,
the registrant has provided ecological effect data. Acceptable guideline
studies are available to assess the acute toxicity of MCPB sodium to
aquatic fish and invertebrates, algae, aquatic vascular plants, birds,
mammals, honey bees, and terrestrial plants, including monocots and
dicots. Acceptable guideline studies are available to assess the
subchronic and developmental effects to mammals.

Acute measures of effect are the concentrations that produce 50%
mortality or growth reduction in the test organisms (LC~50~s and
EC~50~s, respectively). The measure of effect for terrestrial plants is
the EC~25~. Chronic effects endpoints for listed and non-listed plants
are the highest test concentration where there is no observed adverse
effect (NOAECs) on survival and growth of terrestrial and aquatic
plants.

**III. ANALYSIS**

Analysis is a process that examines the two primary components of risk,
exposure and effects, and their relationships between each other and
site characteristics. The objective is to provide the ingredients
necessary for determining or predicting ecological responses to
pesticide uses under exposure conditions of interest. The products of
analysis provide the basis for estimating and describing risks in risk
characterization. The MCPB analysis consists of evaluating environmental
fate data, modeling exposure concentrations and evaluating toxicity
information to formulate potential risks to the defined endpoints shown
in Figure II.b. The analysis is based on Tier II modeling of estimated
exposure concentrations combined with toxicity information from MCPB
toxicity studies.

**A. Use Characterization**

MCPB (4-(2-methyl-4-chlorophenoxy)butyric acid ) is formulated as a
sodium salt in aqueous solution. Methods of application include
controlled droplet applicator, high volume ground sprayer, low volume
ground sprayer, hand held sprayer, high volume spray (dilute), low
volume spray (concentrate), aerial and ground broadcast, and spot
treatment. Timing of application for the one registered use for peas is
when shoots emerge until about three leaf nodes before flowering.

Supported formulations of MCPB are Thistrol® Herbicide (71368-5) and
Sodium MCPB Solution (71368-7). Copies of all labels may be found at
http://www.cdpr.ca.gov/docs/epa/m2.htm[.]{.underline}

The labels for MCPB do not contain specific requirements to minimize
spray drift; only a broad statement is included to avoid spray drift to
prevent injury to susceptible crops. The exception is the state of
Florida, which has promulgated a rule (Organo-Auxin Herbicide Rule) that
stipulates that buffer zones up to a half-mile wide be observed when
spraying phenoxy herbicides. The width of the required buffer zone is
dependent on the wind speed and direction, and whether aerial or ground
spray equipment is used. This has the potential to reduce the exposure
susceptible non-target plants to spray drift.

MCPB can be used on green and dry peas. The USDA crop profiles suggest
that as a result, MCPB may be used throughout the country. For instance,
USDA crop profiles indicate dry and green peas are grown in the
following states: Delaware, Idaho (green peas); Idaho, Montana,
Washington (dry peas) and Maryland, Minnesota, New York, Oregon and
Wisconsin (peas).

The USGS also indicates MCPB usage on peas in Illinios, Michigan,
Pennsylvania, New Jersey and Maine.

Because peas can be grown throughout the country, a variety of
ecosystems may be exposed.

The crop profile for Maryland peas indicates that peas are grown in
estuarine watersheds which include Dorchester and Caroline counties.
Other crop profiles such as Delaware suggest that MCPB may be used in
estuarine as well as freshwater environments. USDA crop profiles and
USGS 1992 use map can be accessed through the following websites.

[http://pestdata.ncsu.edu/cropprofiles/cropprofiles.cfm]{.underline}

[http://ca.water.usgs.gov/pnsp/use92/mcpb.html.]{.underline}

**B. Exposure Characterization**

The MCPB exposure characterization in this assessment combines the
environmental fate data with Tier II exposure models to estimate
environmental exposure concentrations (EECs). Exposure models estimate
EECs following the conceptual diagram of MCPB usage and potential
exposure shown in Figure II.b. EECs for aquatic endpoints are developed
using the Tier II surface water models PRZM/EXAMS. These models are more
comprehensive and determine EECs based on geographic areas nationwide
and product use sites in close proximity to water bodies. EECs for birds
and terrestrial mammals are estimated using the T-REX 1.1 model, and
EECs for non-target plants are estimated by the TerrPlant 1.0 model.

**1. Environmental Fate and Transport Study Summaries:** Laboratory
environmental fate data indicate that MCPB is likely to be mobile, but
not persistent in the environment. Adsorption/desorption studies of MCPB
and a low octanol-water partition coefficient indicate MCPB to be mobile
in soil and soil:water systems. However, soil half-lives indicate that
MCPB would be relatively short-lived and not likely to persist for
extended periods in soils. Under aerobic soil conditions, the overall
half-life was 27 days and the major transformation product was
volatilized ^14^CO~2.~ The half-life for the anaerobic biodegradation of
\[^14^C\]MCPB in sandy loam soil was 7.8 days and the major
transformation product was (4-chloro-2-methylphenoxy)acetic acid (MCPA).

Based on the physical and chemical properties, MCPB will exist
predominately in the ionic or salt form at ambient environmental pHs.
Based on simple chemical equilibrium calculation for MCPB (a monobasic
acid with a pKa of approximately 4.6), the degree of ionization of MCPB
at pH 7 is 99.6%, and ranges from approximately 70% to 99.99+% at pHs 5
and 9, respectively. The only registered formulation for field
application is the sodium salt.

The ***hydrolysis*** of \[phenyl-U^-14^C\]-labeled (
4-(2-methyl-4-chlorophenoxy)butyric acid (MCPB) was studied in the dark
at 25 ± 1°C in sterile aqueous 0.1 M buffer solutions adjusted to pH 5
(acetate), pH 7 (phosphate) and pH 9 (borate) for 30 days in this
acceptable study. The concentration of \[^14^C\]MCPB decreased from
94.4% at day 0 to 91.5% of the applied at study termination in the pH 5
solution, from 95.8% to 91.9% at pH 7, and from 95.7% to 93.2% of the
applied at pH 9. No major transformation product was detected in any of
the solutions.

Because less than 4% of MCPB hydrolyzed at any pH tested during a 30-day
period, MCPB is essentially stable to hydrolysis for environmental fate
purposes (that is, half-lives are indeterminately long during a 30-day
test period). Gross extrapolation indicates half-lives to be greater
than 500 days (MRID 42574301).

The ***aqueous phototransformation*** of \[phenyl-U^-14^C\]-labeled
(4-(2-methyl-4-chlorophenoxy) butyric acid(MCPB) was studied at 25 ± 1°C
in sterile aqueous acetate, phosphate and borate buffer solutions at pH
5, 7 and 9, respectively. Irradiation was for 30 days (12 hours
light/12 hours dark) with a filtered xenon arc lamp light source. The
concentrations of \[^14^C\]MCPB decreased from 94.4% at day 0 to 0.2% of
the applied at day 30 in the pH 5 solution, from 95.9% to \<0.1% at pH
7, and from 95.7% to \<0.1% at pH 9. Five transformation products were
isolated at \>10% of the applied: 4
-(4-hydroxy-[o]{.underline}-tolyloxy)butyric acid; 2,4-dihyroxyphenyl
formate; o-cresol; benzoic acid; and 2-hydroxyphenyl formate. The
half-lives of MCPB in the irradiated pH 5, 7 and 9 buffer solutions
measured in this acceptable study were 2.2, 2.6 and 2.4 days,
respectively. Because the wavelengths and intensity of the filtered
xenon arc lamp used in the laboratory experiment were equivalent to
sunlight and there was no degradation in the dark control, no
adjustments to the half-lives are necessary (MRID 42574302).

The ***adsorption/desorption*** characteristics of phenyl ring-labeled
\[^14^C\]MCPB (4-(2-methyl-4-chlorophenoxy) butyric acid dissolved in
methanol were studied in sterile sandy clay loam soil \[pH- 6.09,
organic carbon - 1.3%\] from France, and the following three soils and
one sediment from England: sand soil \[pH - 7.93, organic carbon -
0.53%\], sandy loam soil \[pH - 6.08, organic carbon - 0.76%\], clay
loam soil \[pH - 7.6, organic carbon - 2.49%\], and sandy loam aquatic
sediment \[pH - 5.95, organic carbon - 2.85%\] in a batch equilibrium
experiment. The mean adsorption K~ads~ values calculated from this
acceptable study were 1.69, 0.26, 0.65, 0.78, and 10.58 mL/g for the
sandy clay loam, sand, sandy loam, and clay loam soils and sandy loam
sediment, respectively. Adsorption K~oc~ values were 129.57, 47.91,
85.54, 31.27, and 371.17 mL/g for the sandy clay loam, sand, sandy loam,
and clay loam soils and sandy loam sediment, respectively. At the end of
the desorption, 64.0%, 32.18%, 60.22%, 60.59%, and 24.63% of the
adsorbed amount was desorbed in the sandy clay loam, sand, sandy loam,
and clay loam soils and sandy loam sediment, respectively (MRID
42693701).

The ***aerobic soil metabolism*** of \[phenyl-U^-14^C\]-labeled
(4-(2-methyl-4-chlorophenoxy) butyric acid (MCPB) was studied in sandy
loam soil (pH in water 5.38, organic carbon 2.3%) from the United
Kingdom for 120 days under aerobic conditions in darkness at 22 ± 1°C
and soil moisture of 75% of 1/3 bar. The major transformation product of
\[^14^C\]MCPB was volatilized ^14^CO~2~ which increased to a maximum
64.9 ± 0.6% of the applied at 65 days and was 54.5-61.8% at 90-120 days;
no organic volatiles were detected. The overall aerobic half-life in
this acceptable study was 27.0 days (r^2^ = 0.774, 0-120 days) with an
initial half-life of 9.1 days (r^2^ = 0.952, 0-29 days) and a secondary
half-life of 79 days (r^2^ = 0.659, 29-120 days). Two minor
transformation products identified in soil extracts were the hexose
conjugate of (4-chloro-2-methylphenoxy)-2-β-glucopyranoside acetic acid
minor (CHPA) and (4-chloro-2-methylphenoxy)acetic acid (MCPA), which
were detected at maximums of 9.5% (8 days) and 7.2% (15 days) of the
applied radioactivity, respectively, with both decreasing to ≤2.1% by
120 days. Five additional unidentified \[^14^C\]compounds were each
≤5.3% of the applied at any sampling interval.

The registrant proposed a biotransformation pathway for the degradation
of MCPB in aerobic soil indicating degradation of MCPB to
(4-chloro-2-methylphenoxy)acetic acid (MCPA), which degrades to
(4-chloro-2-methylphenoxy)-2-β-glucopyranoside acetic acid minor (CHPA)
and conjugates with hexose; and significant production of CO~2~. (MRID
43247601).

The ***anaerobic soil metabolism*** of \[phenyl-U^-14^C\]-labeled
(4-(2-methyl-4-chlorophenoxy)butyric acid (MCPB) was studied in sandy
loam soil (pH in water 7.7, organic carbon 0.3%) incubated for 62 days
under anaerobic conditions (flooding plus nitrogen atmosphere) in
darkness at 25 ± 1°C following 4 days of aerobic incubation. Anaerobic
half-life values of \[^14^C\]MCPB in the water, soil and entire system
using least squares linear regression analysis, based on first-order
kinetics, of \[^14^C\]MCPB recovered in each sample were 18.9, 7.8 and
11.4 days, respectively. The major transformation product of
\[^14^C\]MCPB was (4-chloro-2-methylphenoxy)acetic acid (MCPA) detected
at maximums of 34.8% in the soil at 4 days just prior to flooding, 33.4%
in the water after 14 days of anaerobic incubation, and 46.9% in the
total soil:water system after 29 days. After 62 days of anaerobic
incubation, \[^14^C\]MCPA was 6.6 ± 2.1% of the applied in the soil,
27.8 ± 4.8% in the water and 34.3 ± 2.7% in the entire soil:water system
(MRID 43015501). This study was classified as "acceptable".

Valid ***terrestrial field dissipation*** and ***soil photolysis***
studies are not available.

**2. Measures of Aquatic Exposure**

*Aquatic Exposure Modeling*

Aquatic exposure concentrations for MCPB in the standard field pond were
estimated using the PRZM 3.12 and EXAMS 2.98 models in tandem.
PRZM/EXAMS is a Tier II screening model designed to estimate pesticide
concentrations found in water at the edge of a treated field. As such,
it provides high-end values of the pesticide concentrations that might
be found in ecologically sensitive environments following pesticide
application.

PRZM/EXAMS is a multi-year runoff model that also accounts for spray
drift from single and multiple applications. In the ecological exposure
assessment, PRZM/EXAMS simulates a 10 hectare (ha) field immediately
adjacent to a 1 ha pond, 2 meters deep with no outlet. The geographic
location of the field is specific to the crop being simulated using site
specific information on the soils, weather, cropping, and management
factors associated with the scenario. The crop/location scenario is
intended to represent a high-end vulnerable site on which the crop is
normally grown. Based on historical rainfall patterns, the pond receives
multiple runoff events during the years simulated.

Acute risk assessments are performed using 1 in 10 year peak EEC values
for single applications of MCPB. Chronic risk assessments for aquatic
invertebrates and fish are performed using the average 21-day and 60-day
EECs, respectively.

Table III.a. presents the input parameters used in the Tier II
PRZM/EXAMS modeling for ecological assessment of MCPB for surface water
sources. To simulate field application of MCPB to peas, two scenarios
were selected representing different MCPB usage areas based on geography
and weather. A California lettuce and an Oregon snap bean scenario were
chosen as representative of the agricultural practices and areas in
which peas are grown. The EECs for the two scenarios are presented in
Table III.b. The Oregon scenario represents the typical use of MCPB
application to peas, and the California scenario represents a reasonable
upper bound estimate. Results for the two cases are similar. We also
investigated several other possible scenarios (approximately six
others), and found all EECs to be rather tightly grouped in a range from
approximately 15 to 40 μg ae/L. The PRZM/EXAMS input and output files
from the California and Oregon aquatic ecological exposure assessments
are presented in Appendix B.

+----------------------+--------------+---------------+---------------+
| TABLE III.a.         |              |               |               |
| PRZM/EXAMS Input     |              |               |               |
| Parameters for MCPB. |              |               |               |
+======================+==============+===============+===============+
| **Model Parameter**  | **Value**    | **Comments**  | **Source**    |
+----------------------+--------------+---------------+---------------+
| Application Rate per | 1.68 kg      | application   | Label         |
| Event                | ae/acre      | to peas by    |               |
|                      |              | ground and    |               |
|                      | (1.5 lbs     | aerial spray  |               |
|                      | ae/acre)     | application   |               |
+----------------------+--------------+---------------+---------------+
| Number of            | 1            |               | Label         |
| Applications per     | application  |               |               |
| Crop Season          | per year;    |               |               |
|                      | assumes one  |               |               |
|                      | planting     |               |               |
|                      | season per   |               |               |
|                      | year         |               |               |
+----------------------+--------------+---------------+---------------+
| Spray Application    | 0.99         |               | EFED          |
| Efficiencies         |              |               | Guidance,     |
|                      | 0.95         |               | 2002          |
| > ground             |              |               |               |
| >                    |              |               |               |
| > aerial             |              |               |               |
+----------------------+--------------+---------------+---------------+
| Spray Drift Fraction | 0.01         |               | EFED          |
|                      |              |               | Guidance,     |
| > ground             | 0.05         |               | 2002          |
| >                    |              |               |               |
| > aerial             |              |               |               |
+----------------------+--------------+---------------+---------------+
| Aerobic Soil         | 78 days ^1^  | estimated     | MRID 43247601 |
| Metabolism           |              | upper 90 ^th^ |               |
|                      |              | percentile    |               |
| t ~½~                |              |               |               |
+----------------------+--------------+---------------+---------------+
| Anaerobic Soil       | 34 days ^2^  | estimated     | MRID 43015501 |
| Metabolism           |              | upper 90 ^th^ |               |
|                      |              | percentile    |               |
| t ~½~                |              |               |               |
+----------------------+--------------+---------------+---------------+
| Aerobic Aquatic      | 156 days ^3^ | estimated     | EFED          |
| Degradation          |              |               | Guidance,     |
|                      |              | (2x aerobic   | 2002          |
| t ~½~                |              | soil          |               |
|                      |              |               |               |
|                      |              | metabolism    |               |
|                      |              | half-life)    |               |
+----------------------+--------------+---------------+---------------+
| Anaerobic Aquatic    | 68 days ^4^  | estimated     | EFED          |
| Degradation          |              |               | Guidance,     |
|                      |              | (2x anaerobic | 2002          |
| t ~½~                |              | soil          |               |
|                      |              |               |               |
|                      |              | metabolism    |               |
|                      |              | half-life)    |               |
+----------------------+--------------+---------------+---------------+
| Aqueous Photolysis t | 2.6 days     | pH 7          | MRID 42574302 |
| ~½~                  |              |               |               |
+----------------------+--------------+---------------+---------------+
| Hydrolysis t ~½~     | stable       |               | MRID 42574301 |
+----------------------+--------------+---------------+---------------+
| Kd/Koc               | 0.85 mL/g    | Average Kd    | MRID 42693701 |
|                      | ^5^          |               |               |
+----------------------+--------------+---------------+---------------+
| Molecular Weight     | 228.6        |               | Chemical      |
|                      |              |               | Formula       |
+----------------------+--------------+---------------+---------------+
| Water Solubility     | 600 mg/L     | 10 x          | Product       |
|                      |              | solubility    | Chemistry     |
+----------------------+--------------+---------------+---------------+
| Vapor Pressure       | 4.0E-7 torr  |               | Product       |
|                      |              |               | Chemistry     |
+----------------------+--------------+---------------+---------------+
| Henry's Law Constant | 3.42 x       |               | (Howard and   |
|                      | 10^-9^       |               | Meylan, 1997) |
| (estimated at 25°C)  | atm-m^3^/mol |               |               |
+----------------------+--------------+---------------+---------------+

^1^ Upper 90^th^ Percentile based on three times the single value for
the combined/total aerobic soil metabolism half life of 26 days for
MCPB, MCPA, and CHPA/CHPA hexose conjugate.

^2^ Upper 90^th^ Percentile based on three times the single anaerobic
soil metabolism half life of 11.4 days.

^3^ 2x aerobic soil metabolism half-life (EFED Modeling Input Parameter
Guidance, 2002).

^4^ 2x anaerobic soil metabolism half-life (EFED Modeling Input
Parameter Guidance, 2002).

^5^ From adsorption/desorption data including Kd values of 1.69, 0.26,
0.65, and 0.78 mL/g from MRID 42693701.

+-----------------+-------------+---------------+---------+----------+
| **TABLE III.b.  |             |               |         |          |
| Estimated       |             |               |         |          |
| Environmental   |             |               |         |          |
| Concentrations  |             |               |         |          |
| (μg ae/L) of    |             |               |         |          |
| MCPB +          |             |               |         |          |
| Metabolites     |             |               |         |          |
| (MCPA and       |             |               |         |          |
| CH              |             |               |         |          |
| PA/CHPA-hexose) |             |               |         |          |
| in Surface      |             |               |         |          |
| Water           |             |               |         |          |
| (PRZM-EXAMS)    |             |               |         |          |
| from All Uses   |             |               |         |          |
| for Ecological  |             |               |         |          |
| Assessment.**   |             |               |         |          |
+=================+=============+===============+=========+==========+
| **Simulation    |             | **            |         |          |
| Scenario**      |             | Concentration |         |          |
|                 |             | (μg ae/L)**   |         |          |
+-----------------+-------------+---------------+---------+----------+
| **Crop and      | **          | **1 in 10     | **21    | **60 Day |
| Location**      | Application | year Peak**   | Day     | Max.**   |
|                 | rate**      |               | Max.**  |          |
+-----------------+-------------+---------------+---------+----------+
| Lettuce (CA)    | 1.5 lbs     | 40.4          | 39.0    | 36.4     |
|                 | ae/acre     |               |         |          |
| (Surrogate for  |             | 43.2          | 41.7    | 38.9     |
| Peas)           | (1.68 kg    |               |         |          |
|                 | ae/ha)      |               |         |          |
|                 |             |               |         |          |
|                 | ground      |               |         |          |
|                 | spray       |               |         |          |
|                 |             |               |         |          |
|                 | aerial      |               |         |          |
|                 | spray       |               |         |          |
+-----------------+-------------+---------------+---------+----------+
| Snap Beans (OR) | 1.5 lbs     | 29.5          | 29.0    | 28.1     |
|                 | ae/acre     |               |         |          |
| (Surrogate for  |             | 33.1          | 32.5    | 31.5     |
| Peas)           | (1.68 kg    |               |         |          |
|                 | ae/ha)      |               |         |          |
|                 |             |               |         |          |
|                 | ground      |               |         |          |
|                 | spray       |               |         |          |
|                 |             |               |         |          |
|                 | aerial      |               |         |          |
|                 | spray       |               |         |          |
+-----------------+-------------+---------------+---------+----------+

The following surrogate scenarios are among those available in
PRZM/EXAMS to simulate peas grown in different regions of the US:

California lettuce scenario represents a reasonable upper bound estimate
for areas in which peas are or may be grown.

Oregon snap bean scenario represents a typical use scenario for areas in
which peas are grown.

Input and output for PRZM3.12/EXAMS2.98 modeling is in Appendix B.

*Aquatic Exposure Monitoring and Field Data*

> Surface water and groundwater monitoring data were not available for
> evaluation in this risk assessment.

**3. Measures of Terrestrial Exposure**

*Terrestrial Exposure Modeling*

For birds and mammals, MCPB concentrations on food items, based on data
from Hoerger and Kenaga (1972) and Fletcher et al. (1994), are predicted
using a first-order residue decline method. EFEDs T-REX (Ver. 1.1) model
predicts maximum and mean EECs resulting from the single application of
MCPB. Acute and Chronic RQs are calculated using these EECs and
appropriate toxicity data.

+------------+------------------------+------------------+-----------+
| **TABLE    |                        |                  |           |
| III.c.     |                        |                  |           |
| Estimated  |                        |                  |           |
| Env        |                        |                  |           |
| ironmental |                        |                  |           |
| Conc       |                        |                  |           |
| entrations |                        |                  |           |
| (ppm ae)   |                        |                  |           |
| of MCPB    |                        |                  |           |
| Acid on    |                        |                  |           |
| T          |                        |                  |           |
| errestrial |                        |                  |           |
| Food Items |                        |                  |           |
| from Use   |                        |                  |           |
| on Peas.** |                        |                  |           |
+============+========================+==================+===========+
| **         |                        | **Concentration  |           |
| Simulation |                        | (ppm ae)**       |           |
| Scenario** |                        |                  |           |
+------------+------------------------+------------------+-----------+
| **Crop**   | **Food item**          | **Maximum**      | **Mean**  |
+------------+------------------------+------------------+-----------+
| Peas       | Short Grass            | 360              | 127.5     |
|            |                        |                  |           |
|            | Tall Grass             | 165              | 54        |
|            |                        |                  |           |
|            | Broadleaf Plants/Small | 202.5            | 67.5      |
|            | Insects                |                  |           |
|            |                        | 22.5             | 10.5      |
|            | F                      |                  |           |
|            | ruits/Pods/Seeds/Large |                  |           |
|            | Insects                |                  |           |
+------------+------------------------+------------------+-----------+

Effects on non-target terrestrial plants are most likely to occur as a
result of spray drift from aerial and ground applications of the liquid
formulation. Spray drift is an important factor in characterizing the
risk of MCPB to non-target plants. The TerrPlant (Ver.1.0) model
predicts EECs for terrestrial plants located adjacent to the treated
field. MCPB applied according to label directions as a liquid spray for
ground or aerial applications may impact non-target plants for some
distance from the application site depending on droplet size, wind
speed, and other factors. The MCPB product label does not specify a
required or recommended droplet size for spray applications. MCPB
applied as a fine or medium spray has the potential to damage off-target
plants. In addition to the TerrPlant modeling of EECs, refinement of
spray drift from treated fields was assessed with the AgDrift (Ver.
2.0.1) model. The AgDrift model provides estimates of drift dispersion
and deposition as the result of ground and aerial spray droplet and
nozzle size, wind speed and distance from the treated field.

*Residue Studies*

No residues of MCPB or its primary degradate, MCPA, were detected on
peas and pods at harvest after broadcast treatment of Thistrol (1.5 lbs.
ae/acre) in eight field trials conducted in 1999 (MRID 44754101).
Succulent peas and pods were sampled 29-34 days after treatment with
MCPB (1.5 lbs. ae/acre) and dried peas were sampled 42-64 days after
MCPB treatment and analyzed for residues. The maximum residue to which
animals could be exposed would occur directly after application. The
decline of residues from this maximum level was therefore not measured.
To assess the potential risk to birds and terrestrial animals from
exposure to residues immediately following application to pea plants,
EFED modeled exposure concentrations using TRex (ver. 1.1). These
modeled residue concentrations on pea plants provide the avian and
terrestrial mammal EECs for risk calculations. Since the foliar
dissipation half-life could not be determined from the residue study, a
default value of 35 days was used.

**C. Ecological Effects Characterization**

**1. Aquatic Effects Characterization**

The following tables present measures of effect both in terms of active
ingredient and acid equivalents. Conversion from active ingredient to
acid equivalents was made in accordance with molecular weight
differences. One gram-mole of MCPB acid has a mass of 228.67 grams and
one gram-mole of MCPB sodium salt has a mass of 250.66 grams; therefore,
one unit of the salt would be equivalent to 0.912 units of the acid.
Hence, the LC50 values from the toxicity tests with MCPB sodium were
converted to acid equivalents by multiplying the values by 0.91.

  -----------------------------------------------------------------------
  **TABLE III.d. Summary of endpoints for MCPB acute and chronic aquatic
  toxicity studies for RQ evaluation**
  -----------------------------------------------------------------------

  -----------------------------------------------------------------------

+------------+-----------+---------------+-------+-------------------+
| **         | **Env     | **Toxicity    | **MR  | **Comment**       |
| Endpoint** | ironment/ | Value Used in | ID#** |                   |
|            | Species** | Risk          |       |                   |
|            |           | Assessment**  |       |                   |
+============+===========+===============+=======+===================+
| Acute      | [Fresh    | 96-hr LC~50~  | 425   | Acceptable        |
| Toxicity   | water]{.u | = 3.9         | 32608 |                   |
| to Fish    | nderline} |               |       |                   |
|            |           | mg ae/L       |       |                   |
|            | Rainbow   |               |       |                   |
|            | Trout     |               |       |                   |
|            | (TGAI)    |               |       |                   |
+------------+-----------+---------------+-------+-------------------+
|            | [Es       | No data       | NA    | No studies were   |
|            | tuarine/m |               |       | submitted         |
|            | arine]{.u |               |       |                   |
|            | nderline} |               |       |                   |
|            |           |               |       |                   |
|            | No data   |               |       |                   |
|            |           |               |       |                   |
|            | (TGAI)    |               |       |                   |
+------------+-----------+---------------+-------+-------------------+
| Chronic    | [Fresh    | No data       | NA    | No studies were   |
| Toxicity   | water]{.u |               |       | submitted         |
| to Fish    | nderline} |               |       |                   |
|            |           |               |       |                   |
|            | No data   |               |       |                   |
|            |           |               |       |                   |
|            | (TGAI)    |               |       |                   |
+------------+-----------+---------------+-------+-------------------+
|            | [Es       | No data       | NA    | No studies were   |
|            | tuarine/m |               |       | submitted         |
|            | arine]{.u |               |       |                   |
|            | nderline} |               |       |                   |
|            |           |               |       |                   |
|            | No data   |               |       |                   |
+------------+-----------+---------------+-------+-------------------+
| Acute      | [Fresh    | 48-hr EC~50~  | 425   | Acceptable        |
| Toxicity   | water]{.u | = 50.0        | 32602 |                   |
| to         | nderline} |               |       |                   |
| Inv        |           | mg ae/L       |       |                   |
| ertebrates | *Daphnia  |               |       |                   |
|            | magna*    |               |       |                   |
|            |           |               |       |                   |
|            | (TGAI)    |               |       |                   |
+------------+-----------+---------------+-------+-------------------+
|            | [Es       | No data       | NA    | No studies were   |
|            | tuarine/m |               |       | submitted         |
|            | arine]{.u |               |       |                   |
|            | nderline} |               |       |                   |
|            |           |               |       |                   |
|            | No data   |               |       |                   |
|            |           |               |       |                   |
|            | (TGAI)    |               |       |                   |
+------------+-----------+---------------+-------+-------------------+
| Chronic    | [Fresh    | No data       | NA    | No studies were   |
| Toxicity   | water]{.u |               |       | submitted         |
| to         | nderline} |               |       |                   |
| Inv        |           |               |       |                   |
| ertebrates | No data   |               |       |                   |
|            |           |               |       |                   |
|            | (TGAI)    |               |       |                   |
+------------+-----------+---------------+-------+-------------------+
|            | [Es       | No data       | NA    | No studies were   |
|            | tuarine/m |               |       | submitted         |
|            | arine]{.u |               |       |                   |
|            | nderline} |               |       |                   |
|            |           |               |       |                   |
|            | No data   |               |       |                   |
+------------+-----------+---------------+-------+-------------------+
| Toxicity   | [Vas      | EC~50~ = 0.21 | 4.2   | Based on frond    |
| to Aquatic | cular]{.u | mg ae/L       | 5e+15 | production        |
| Plants     | nderline} |               |       |                   |
|            |           | NOEC =        |       | Based on reduced  |
|            | Duckweed  | \<.01mg       |       | cell density      |
|            |           | ae/L\*        |       |                   |
|            | (TGAI)    |               |       |                   |
|            |           | EC~50~ = 0.38 |       |                   |
|            | [NonVas   | mg ae/L       |       |                   |
|            | cular]{.u |               |       |                   |
|            | nderline} | NOEC =        |       |                   |
|            |           | \<.31mg       |       |                   |
|            | Green     | ae/L\*        |       |                   |
|            | Algae     |               |       |                   |
|            |           |               |       |                   |
|            | (TGAI)    |               |       |                   |
+------------+-----------+---------------+-------+-------------------+

\*NOEC can not be determined due to non-discreet toxicity value
therefore definitive endangered species RQs can not be calculated.
EC~05~ was not available.

Freshwater Fish, Acute

Fish toxicity studies for two freshwater species using the TGAI are
required to establish the acute toxicity of MCPB to fish. The preferred
test species are rainbow trout (a coldwater fish) and bluegill sunfish
(a warmwater fish). The acute studies that were submitted that tested
the parent compound showed that MCPB sodium is moderately toxic to the
more sensitive coldwater rainbow trout (LC~50~ 3.9 mg ae/L) and slightly
toxic to the warmwater bluegill (LC~50~ 12.7 mg ae/L). EFED will use
(LC~50~ 3.9 mg ae/L) for evaluating acute risk to freshwater fish. The
guideline (72-1) is fulfilled (MRID 42532608; MRID 42532601).

+-----------------+--------+--------+---------+------------+---------+
| **TABLE III.e.  |        |        |         |            |         |
| Freshwater Fish |        |        |         |            |         |
| Acute Toxicity  |        |        |         |            |         |
| for MCPB        |        |        |         |            |         |
| Sodium.**       |        |        |         |            |         |
+=================+========+========+=========+============+=========+
| Species         | 9      | 9      | T       | MRID No.   | Study   |
|                 | 6-hour | 6-hour | oxicity |            | Classif |
|                 |        |        | C       | A          | ication |
|                 | LC~50~ | LC~50~ | ategory | uthor/Year |         |
|                 |        |        |         |            |         |
|                 | (mg    | (mg    |         |            |         |
|                 | ai/L)  | ae/L)  |         |            |         |
|                 |        |        |         |            |         |
|                 | (no    | (no    |         |            |         |
|                 | minal) | minal) |         |            |         |
+-----------------+--------+--------+---------+------------+---------+
| Bluegill        | 14     | 12.7   | S       | 42532601   | Acc     |
| sunfish         |        |        | lightly |            | eptable |
|                 |        |        | toxic   | Be         |         |
| *(Lepomis       |        |        |         | ttencourt, |         |
| macrochirus)*   |        |        |         | 1992       |         |
+-----------------+--------+--------+---------+------------+---------+
| Rainbow trout   | 4.3    | 3.9    | Mod     | 42532608   | Acc     |
|                 |        |        | erately |            | eptable |
| *(Oncorhynchus  |        |        | toxic   | Be         |         |
| mykiss)*        |        |        |         | ttencourt, |         |
|                 |        |        |         | 1992       |         |
+-----------------+--------+--------+---------+------------+---------+

Studies performed by the registrant for the anaerobic soil degradate
MCPA indicate that it is less toxic to fish (LC~50~ values ranging from
\>68 - \>79 mg ae/L).

*Freshwater Invertebrates, Acute*

A freshwater aquatic invertebrate toxicity test using the TGAI is
required to establish the toxicity of MCPB to aquatic invertebrates. The
preferred test species is *Daphnia magna*. The data that were submitted
that tested the parent compound showed that MCPB sodium is slightly
toxic to *Daphnia magna* with an acute 48-hour EC~50~ value of 50 mg
ae/L. EFED will use this value for evaluating acute risk to freshwater
invertebrates. The guideline requirement (72-2) for acute invertebrate
toxicity is fulfilled (MRID 42532602).

+------------+--------+---------+-------------+------------+----------+
| **TABLE    |        |         |             |            |          |
| III.f.     |        |         |             |            |          |
| Freshwater |        |         |             |            |          |
| In         |        |         |             |            |          |
| vertebrate |        |         |             |            |          |
| Acute      |        |         |             |            |          |
| Toxicity   |        |         |             |            |          |
| for MCPB   |        |         |             |            |          |
| Sodium**.  |        |         |             |            |          |
+------------+--------+---------+-------------+------------+----------+
| Species    | 4      | 48-hour | Toxicity    | MRID No.   | Study    |
|            | 8-hour | EC~50~  | category    |            |          |
|            | EC~50~ |         |             | A          | Classi   |
|            |        | (mg     |             | uthor/Year | fication |
|            | (mg    | ae/L)   |             |            |          |
|            | ai/L)  |         |             |            |          |
+------------+--------+---------+-------------+------------+----------+
| Waterflea  | 55     | 50      | Slightly    | 42532602   | Ac       |
|            |        |         | toxic       |            | ceptable |
| (*Daphnia  |        |         |             | Putt, 1992 |          |
| magna*)    |        |         |             |            |          |
+------------+--------+---------+-------------+------------+----------+

A study performed by the registrant for MCPA indicates that the
degradate is practically non-toxic to aquatic invertebrates with an
EC~50~ of \>184 mg ae/L.

*Freshwater Fish, Chronic*

A freshwater fish early life-stage test and life cycle fish test using
the TGAI were not submitted by the registrant. Therefore, the guidelines
(72-4a; 72-5) were not fulfilled.

*Freshwater Invertebrate, Chronic*

A freshwater aquatic invertebrate life-cycle test using the TGAI was not
submitted by the registrant. The preferred test is a 21-day life cycle
study with *Daphnia magna*. The guideline (72-4b) was not fulfilled.

*Freshwater Field Studies*

Aquatic field studies were not submitted.

*Estuarine/Marine Fish and Invertebrate, Acute and Chronic*

Estuarine/marine studies were not submitted by the registrant.
Therefore, the following guidelines were not fulfilled: (72-3a for acute
fish - sheepshead minnow; 72-3b for acute invertebrate - eastern oyster;
72-4d for mysid life cycle).

*Aquatic Plants*

Several aquatic plant toxicity studies using the TGAI were submitted to
establish the toxicity of MCPB to non-target aquatic plants. The
recommendation is for testing of five species: freshwater green alga
*(Selenastrum capricornutum)*, duckweed *(Lemna gibba)*, marine diatom
*(Skeletonema costatum)*, blue-green algae *(Anabaena flos-aquae)*, and
a freshwater diatom. The EC~50~ for the freshwater vascular plant
(duckweed) is 0.21 mg ae/L, based on reduced frond production; and the
lowest EC~50~ for freshwater non-vascular plants is 0.38 mg ae/L, based
on reduced cell density in the green algae study. Studies submitted for
the algal species indicate that the green algae is more sensitive to
MCPB sodium than the blue-green algae causing reductions in cell density
at the lowest level tested (0.31 mg ae/L). The freshwater diatom was
more sensitive to MCPB sodium than the marine diatom causing reductions
in cell density at test levels as low as 0.12 mg ae/L. The aquatic
vascular plant, duckweed was the most sensitive of the five aquatic
species tested. Concentrations as low as 0.15 mg ae/L resulted in
chlorosis, curling, and decreased root formation in the plant. In
addition, frond biomass was significantly reduced at 0.42 mg ae/L. The
guideline requirements (122-2 and 123-2) are fulfilled; MRID 42532603;
MRID 42532604; MRID 42532605; MRID 42532606; and MRID 42532609) for the
five required species.

+-------------+---------+---------+-----------+-----------+----------+
| **TABLE     |         |         |           |           |          |
| III.g.      |         |         |           |           |          |
| Non-target  |         |         |           |           |          |
| Aquatic     |         |         |           |           |          |
| Plant       |         |         |           |           |          |
| Toxicity    |         |         |           |           |          |
| for MCPB    |         |         |           |           |          |
| Sodiu       |         |         |           |           |          |
| m.(ai)/MCPB |         |         |           |           |          |
| acid (ae)** |         |         |           |           |          |
+-------------+---------+---------+-----------+-----------+----------+
| **Species** | *       | *       | **        | **MRID    | **Study  |
|             | *EC~50~ | *EC~50~ | Endpoints | No.**     | Classifi |
| **\[Study   | /NOEC** | /NOEC** | A         |           | cation** |
| Type\]**    |         |         | ffected** | **Author, |          |
|             | **(mg   | **(mg   |           | Year**    |          |
|             | ai/L)** | ae/L)** |           |           |          |
+-------------+---------+---------+-----------+-----------+----------+
| Duckweed    | 0.23/   | 0.21/\  | Frond     | 42532604  | Ac       |
|             | \<0.011 | <0.01\* | p         |           | ceptable |
| (*Lemna     |         |         | roduction | Hoberg,   |          |
| gibba*)     | 1       | 1.      |           | 1992      |          |
|             | .7/0.17 | 55/0.15 | Frond     |           |          |
| \[Tier I\]  |         |         | biomass   |           |          |
+-------------+---------+---------+-----------+-----------+----------+
| Green Algae | 0.42    | 0.38/\  | Cell      | 42532605  | Ac       |
|             | /\<0.34 | <0.31\* | density   |           | ceptable |
| (*          |         |         |           | Hoberg,   |          |
| Selenastrum |         |         |           | 1992      |          |
| capr        |         |         |           |           |          |
| icornutum*) |         |         |           |           |          |
|             |         |         |           |           |          |
| \[Tier I\]  |         |         |           |           |          |
+-------------+---------+---------+-----------+-----------+----------+
| Blue-green  | \>      | \>      | Cell      | 42532603  | Ac       |
| Algae       | 2.1/2.1 | 1.9/1.9 | density   |           | ceptable |
|             |         |         |           | Hoberg,   |          |
| (*Anabaena  |         |         |           | 1992      |          |
| f           |         |         |           |           |          |
| los-aquae*) |         |         |           |           |          |
|             |         |         |           |           |          |
| \[Tier I\]  |         |         |           |           |          |
+-------------+---------+---------+-----------+-----------+----------+
| Diatom      | 0.7     | 0.6     | Cell      | 42532609  | Ac       |
|             | 1/0.048 | 5/0.044 | density   |           | ceptable |
| (*Navicula  |         |         |           | Hoberg,   |          |
| pe          |         |         |           | 1992      |          |
| lliculosa*) |         |         |           |           |          |
|             |         |         |           |           |          |
| \[Tier I &  |         |         |           |           |          |
| II\]        |         |         |           |           |          |
+-------------+---------+---------+-----------+-----------+----------+
| Diatom      | 1.5     | 1.      | Cell      | 42532606  | Ac       |
|             | /\<0.11 | 36/0.10 | density   |           | ceptable |
| (*          |         |         |           | Hoberg,   |          |
| Skeletonema |         |         |           | 1992      |          |
| costatum*)  |         |         |           |           |          |
|             |         |         |           |           |          |
| \[Tier I &  |         |         |           |           |          |
| II\]        |         |         |           |           |          |
+-------------+---------+---------+-----------+-----------+----------+

\*Can not determine a NOEC due to a non-discreet toxicity value.
Endangered species risk quotient can not be calculated without a NOEC.

Aquatic plant studies with the anaerobic soil degradate MCPA acid
indicate that the toxicity is very similar to MCPB with the EC~50~ for
the freshwater vascular plant (duckweed) of 0.17 mg ae/L (MRID 43126501)
and the lowest EC~50~ for the freshwater non-vascular plant (diatom) of
0.63 mg ae/L (MRID 43083202).

**2. Terrestrial Effects Characterization**

The following tables present measures of effect both in terms of active
ingredient and acid equivalents. Conversion from active ingredient to
acid equivalents was made in accordance with molecular weight
differences. One gram-mole of MCPB acid has a mass of 228.67 grams and
one gram-mole of MCPB sodium salt has a mass of 250.66 grams; therefore,
one unit of the salt would be equivalent to 0.912 units of the acid.
Hence, the LC50 values from the toxicity tests with MCPB sodium were
converted to acid equivalents by multiplying the values by 0.91.

*Birds, Acute*

An oral toxicity study using the technical grade of the active
ingredient (TGAI) is required to establish the acute toxicity of MCPB to
birds. The preferred guideline test species is either mallard duck (a
waterfowl) or bobwhite quail (an upland gamebird). The data that were
submitted report that the 14-day oral LD~50~ is 257 mg ae/kg. The NOEL
was not determined due to abnormal effects at the lowest level tested.
Observed effects including lethargy, dyspnea, loss of righting reflex
and diarrhea. Gross necropsy showed white areas/film on the heart,
liver, gizzard, gallbladder, crop or intestines. Based on these results,
MCPB is categorized as moderately toxic to avian species on an acute
oral basis; the guideline (71-1) is fulfilled (MRID 42560801).

+-------------------+-------+--------+---------+-----------+----------+
| **TABLE III.h.    |       |        |         |           |          |
| Avian Acute Oral  |       |        |         |           |          |
| Gavage Toxicity   |       |        |         |           |          |
| for MCPB Sodium.  |       |        |         |           |          |
| (ai)/MCPB Acid    |       |        |         |           |          |
| (ae)**            |       |        |         |           |          |
+===================+=======+========+=========+===========+==========+
| **Species**       | *     | **     | **T     | **MRID    | *        |
|                   | *LD50 | LD50** | oxicity | No.**     | *Study** |
|                   | (mg   |        | Cat     |           |          |
|                   | ai    | **(mg  | egory** | **Author, | **       |
|                   | /kg** | ae     |         | Year**    | Classifi |
|                   |       | /kg)** |         |           | cation** |
+-------------------+-------+--------+---------+-----------+----------+
| Northern bobwhite | 282   | 257    | Mod     | 42560801  | Ac       |
| quail             |       |        | erately |           | ceptable |
|                   |       |        | toxic   | Pederson  |          |
| *(Colinus         |       |        |         | and       |          |
| virginianus)*     |       |        |         | Helsten,  |          |
|                   |       |        |         | 1992      |          |
+-------------------+-------+--------+---------+-----------+----------+

Two dietary studies using the TGAI are required to establish the acute
toxicity of MCPB to birds. The preferred test species are mallard duck
and bobwhite quail. The data that were submitted show that the 8-day
acute dietary LC~50~ for both species was \>4,550 ppm ae; therefore,
MCPB sodium is categorized as practically non-toxic to avian species on
an acute dietary basis. The 8-day NOELs for each species based on
sublethal effects (reduced body weight gain) were 1138 ppm ae. In
addition, gross necropsy revealed white spots on the liver of one bird
and a dark red spot on the liver of another bird. The guideline (71-2)
is fulfilled (MRID 42560802; MRID 42560803).

+-------------+-------+--------+-----------+------------+------------+
| **TABLE     |       |        |           |            |            |
| III.i.      |       |        |           |            |            |
| Avian Acute |       |        |           |            |            |
| Dietary     |       |        |           |            |            |
| Studies for |       |        |           |            |            |
| MCPB Sodium |       |        |           |            |            |
| (ai)/MCPB   |       |        |           |            |            |
| Acid (ae)** |       |        |           |            |            |
+=============+=======+========+===========+============+============+
| **Species** | **    | *      | *         | **MRID     | **Study    |
|             | 8-Day | *8-Day | *Toxicity | No.**      | Classi     |
|             | L     | LC50** | C         |            | fication** |
|             | C50** |        | ategory** | **Author,  |            |
|             |       | **(ppm |           | Year**     |            |
|             | *     | ae)**  |           |            |            |
|             | *(ppm |        |           |            |            |
|             | ai)** |        |           |            |            |
+-------------+-------+--------+-----------+------------+------------+
| Northern    | \>    | \      | Pr        | 42560802   | Acceptable |
| bobwhite    | 5,000 | >4,550 | actically |            |            |
| quail       |       |        |           | Pederson   |            |
|             |       |        | non-toxic | and        |            |
| *(Colinus   |       |        |           | Helsten,   |            |
| vi          |       |        |           | 1992       |            |
| rginianus)* |       |        |           |            |            |
+-------------+-------+--------+-----------+------------+------------+
| Mallard     | \>    | \      | Pr        | 42560803   | Acceptable |
| duck        | 5,000 | >4,550 | actically |            |            |
|             |       |        |           | Pederson   |            |
| *(Anas      |       |        | non-toxic | and        |            |
| plat        |       |        |           | Helsten,   |            |
| yrhynchos)* |       |        |           | 1992       |            |
+-------------+-------+--------+-----------+------------+------------+

Avian toxicity studies performed to determine the toxicity of the
anaerobic soil degradate MCPA indicate similar results to MCPB sodium
(oral LD~50~ 221 to 377 mg ae/kg-bw in bobwhite quail; acute dietary
LC~50~ \>4,680 mg ae/kg-diet for both bobwhite quail and mallard duck).

*Birds, Chronic*

Avian reproduction studies using the TGAI are usually required for
pesticide registration because birds may be subject to repeated or
continuous exposure to the pesticide, especially preceding or during the
breeding season. The preferred test species are mallard duck and
bobwhite quail. No chronic bird studies were submitted for MCPB.

EFED considered MCPA as a substitute for MCPB for chronic risk to birds,
because the LD50 for bobwhite quail suggests that the acute potency of
MCPB lies within the range of toxicity for acid equivalent MCPA. Also,
rapid dissociation of MCPB to MCPA is expected to occur in the bird gut
due to the chemical properties of MCPB.

The chronic bird study for MCPA with bobwhite quail has a NOAEC of 1000
mg/kg-diet ( MRID \# 435052-01) . No further studies are required for
chronic risk to birds for MCPB at this time.

*Mammals, Acute*

Wild mammal testing is required on a case-by-case basis, depending on
the results of lower tier laboratory mammalian studies, intended use
pattern and pertinent environmental fate characteristics. In most cases,
rat or mouse toxicity values obtained from the Agency\'s Health Effects
Division (HED) substitute for wild mammal testing. These toxicity values
are reported below.

The results indicate that MCPB is categorized as slightly toxic to
practically non-toxic to small mammals on an acute oral basis (LD~50~
values range from 912 - 7,400 mg ai/kg/day). The guideline 81-1 is
fulfilled (MRID 116340; MRID 144801).

+----------+----+----------+---------------------+----------+----------+
| **TABLE  |    |          |                     |          |          |
| III.j.   |    |          |                     |          |          |
| M        |    |          |                     |          |          |
| ammalian |    |          |                     |          |          |
| Acute    |    |          |                     |          |          |
| Toxicity |    |          |                     |          |          |
| for      |    |          |                     |          |          |
| MCPB.**  |    |          |                     |          |          |
+==========+====+==========+=====================+==========+==========+
| **S      | *  | **Test** | **Toxicity**        | **       | **MRID   |
| pecies** | *% |          |                     | Affected | No.**    |
|          | Pu | **Type** |                     | End      |          |
|          | ri |          |                     | points** | **Study  |
|          | ty |          |                     |          | author   |
|          | ** |          |                     |          | Classifi |
|          |    |          |                     |          | cation** |
+----------+----+----------+---------------------+----------+----------+
| Rat      | Te | Acute    | LD~50~ =3100-5800mg | M        | 144801   |
|          | ch | oral     | ai/kg/day (males)   | ortality |          |
| (*Rattus |    |          |                     |          | Kynoch,  |
| norv     |    |          | LD~50~ =3800-74     |          | 1985     |
| egicus*) |    |          | 00mg ai/kg/day      |          |          |
|          |    |          | (females)           |          | Ac       |
|          |    |          |                     |          | ceptable |
+----------+----+----------+---------------------+----------+----------+
| Rat      | Te | Acute    | LD~50~ = 912-2700   | M        | 116340   |
|          | ch | oral     | mg ai/kg/day        | ortality |          |
| (*Rattus |    |          | (males)             |          | Holsing, |
| norv     |    |          |                     |          | 1969     |
| egicus*) |    |          | LD~50~ = 969-2981   |          |          |
|          |    |          | mg ai/kg/day        |          | Ac       |
|          |    |          | (females)           |          | ceptable |
+----------+----+----------+---------------------+----------+----------+

*Mammals, Subchronic and Developmental/Reproductive*

Three subchronic feeding studies were performed with MCPB. In the two
dog studies, reproductive effects, including testicular and prostate
atrophy and curtailment of spermatogenic activity, were observed. In the
acceptable dog study (MRID 42883603), the LOAEL was 44 mg ai/kg/day
based on reduced testes weights and physiological changes in clinical
chemistry. The NOAEL was 25 mg ai/kg/day. Clinical chemistry changes in
these studies (increase in creatinine and urea nitrogen) were also
related to MCPB exposure. In the rat study, the decreased food
consumption and body weight gains were attributed to the lack of
palatability of MCPB in the feed. Because no microscopic effects were
observed in the rat study, the other effects were considered not to be
toxicologically significant. The guidelines 82-1a and 82-1b are
fulfilled (MRID 42883602; MRID 42883603).

In developmental toxicity studies with rats and rabbits, maternal
toxicity was observed at doses ranging from 20 - 100 mg/kg/day. In the
rat study, the maternal toxicity observed at 100 mg ai/kg/day included
decreased body weights and body weight gains during gestation. In the
rabbit study, maternal toxicity observed at 20 mg ai/kg/day included
maternal deaths, clinical signs of toxicity, decrease in body weight
gain during treatment, and change in color of liver and kidneys.

Developmental effects were observed in rats at a dose of 100 mg
ai/kg/day, including decreased mean body weights/litter for males and
females, increases in unossified or poorly ossified sites and increases
in several other skeletal variations. No malformations or variations
were observed in the rabbit fetuses at the highest dose tested, 20 mg
ai/kg/day. EFED will use the NOAEL for maternal toxicity of 5 mg
ai/kg/day from the rabbit study for evaluating the developmental
toxicity of MCPB acid to mammals. The guideline 83-3 is fulfilled (MRID
40865401; MRID 40865402).

Maternal toxicity and developmental effects were also observed in a
2-generation reproduction study with rats exposed to the degradate MCPA
(MRID 40041701). The NOAEL for maternal toxicity was 7.5 mg ai/kg/day
and the LOAEL was 22.5 mg ai/kg/day based on increased absolute and
relative ovary weights. No maternal mortality was observed with exposure
to MCPA. The LOAEL for offspring toxicity was 22.5 mg ai/kg/day based on
decreased pup weight gain during lactation; the NOAEL was 7.5 mg
ai/kg/day. No LOAEL was established for developmental toxicity.

+--------+----+--------+------------------------+----------+----------+
| *      |    |        |                        |          |          |
| *TABLE |    |        |                        |          |          |
| III.k. |    |        |                        |          |          |
| Mam    |    |        |                        |          |          |
| malian |    |        |                        |          |          |
| C      |    |        |                        |          |          |
| hronic |    |        |                        |          |          |
| and    |    |        |                        |          |          |
| De     |    |        |                        |          |          |
| velopm |    |        |                        |          |          |
| ental/ |    |        |                        |          |          |
| Reprod |    |        |                        |          |          |
| uctive |    |        |                        |          |          |
| To     |    |        |                        |          |          |
| xicity |    |        |                        |          |          |
| for    |    |        |                        |          |          |
| M      |    |        |                        |          |          |
| CPB.** |    |        |                        |          |          |
+========+====+========+========================+==========+==========+
| **Spe  | *  | **     | **Toxicity ai**        | **       | **MRID   |
| cies** | *% | Test** |                        | Affected | No.**    |
|        | Pu |        |                        | End      |          |
|        | ri | **     |                        | points** | **Study  |
|        | ty | Type** |                        |          | author   |
|        | ** |        |                        |          | Classifi |
|        |    |        |                        |          | cation** |
+--------+----+--------+------------------------+----------+----------+
| Dog    | NA | Subc   | NOEL = 480 ppm         | Reprodu  | 116345   |
|        |    | hronic |                        | ction^1^ |          |
|        |    | fee    | LOEL = 1600 ppm        |          | Rhodia,  |
|        |    | ding - |                        |          | 1970     |
|        |    | 13     |                        |          |          |
|        |    | weeks  |                        |          | Supp     |
|        |    |        |                        |          | lemental |
+--------+----+--------+------------------------+----------+----------+
| Dog    | 91 | Subc   | NOEL = 25 mg ai/kg/day | Reprodu  | 42883603 |
|        | .1 | hronic |                        | ction^2^ |          |
|        |    | fee    | LOEL = 44 mg ai/kg/day |          | Dalgard, |
|        |    | ding - |                        |          | 1993     |
|        |    | 13     |                        |          |          |
|        |    | weeks  |                        |          | Ac       |
|        |    |        |                        |          | ceptable |
|        |    |        |                        |          | -minimum |
+--------+----+--------+------------------------+----------+----------+
| Rat    | 91 | Subc   | NOEL = 158 mg          | No       | 4        |
|        | .1 | hronic | ai/kg/day              | effects  | 2883602; |
|        |    | fee    |                        |          | 42883601 |
|        |    | ding - |                        |          |          |
|        |    | 13     |                        |          | Trutter, |
|        |    | weeks  |                        |          | 1993     |
|        |    |        |                        |          |          |
|        |    |        |                        |          | Ac       |
|        |    |        |                        |          | ceptable |
|        |    |        |                        |          | -minimum |
+--------+----+--------+------------------------+----------+----------+
| Rat    | 97 | D      | NOAEL/LOAEL = 25/100   | Maternal | 40865402 |
|        | .6 | evelop | mg ai/kg/day           | tox^3^   |          |
|        |    | mental | NOAEL/LOAEL= 25/100 mg |          | Tyl,     |
|        |    |        | ai/kg/day              | Devel    | 1988     |
|        |    |        |                        | opmental |          |
|        |    |        |                        |          | Ac       |
|        |    |        |                        |          | ceptable |
+--------+----+--------+------------------------+----------+----------+
| Rabbit | 97 | D      | NOAEL/LOAEL = 5/20 mg  | Maternal | 40865401 |
|        | .6 | evelop | ai/kg/day NOAEL = 20   | tox^4^   |          |
|        |    | mental | mg ai/kg/day           |          | Tyl &    |
|        |    |        |                        | Devel    | Neeper-  |
|        |    |        |                        | opmental | Bradley, |
|        |    |        |                        |          | 1988     |
|        |    |        |                        |          |          |
|        |    |        |                        |          | Ac       |
|        |    |        |                        |          | ceptable |
+--------+----+--------+------------------------+----------+----------+
| Rat    | 9  | Reprod | NOAEL/LOAEL = 7.5/22.5 | Maternal | 40041701 |
| (MCPA) | 4. | uction | mg ai/kg/day           | tox^5^   |          |
|        | 8% |        |                        |          | Ma       |
|        |    |        | NOAEL/LOAEL = 7.5/22.5 | O        | cKenzie, |
|        |    |        | mg ai/kg/day           | ffspring | 1986     |
|        |    |        |                        | tox      |          |
|        |    |        | NOAEL = 22.5 mg        |          | Ac       |
|        |    |        | ai/kg/day              | Devel    | ceptable |
|        |    |        |                        | opmental |          |
+--------+----+--------+------------------------+----------+----------+

^1^ Testicular and prostate atrophy; curtailment of spermatogenic
activity.

^2^ Reduced testes weights; physiological changes in clinical chemistry.

^3^ Maternal toxicity - Decreased body weight and body weight gain
during gestation.

Developmental toxicity - Decreased mean body weights/litter; increases
in unossified or poorly ossified sites; skeletal variations.

^4^ Maternal toxicity - Death, clinical signs of toxicity, decrease in
body weight gain, change in color of liver and kidneys.

Developmental toxicity - No malformations or variations were observed in
the fetuses.

^5^Maternal toxicity - Increased absolute and relative ovary weights

Offspring toxicity - Decreased pup weight gain during lactation.

Developmental toxicity - No malformations were observed in the fetuses.

*Insects, Acute Contact*

A honey bee acute contact study using the TGAI is required for MCPB
because its foliar application treatment use will result in honey bee
exposure. The acute contact LD~50~, using the honey bee, *Apis
mellifera*, is an acute contact, single-dose laboratory study designed
to estimate the quantity of toxicant required to cause 50% mortality in
a test population of bees. The acute contact LD~50~ for MCPB sodium is
\> 23 µg ae/bee and it is, therefore, classified as practically
non-toxic to bees on a contact exposure basis. The guideline (141-1) is
fulfilled (MRID 42532607). No acute contact studies were available for
the degradate MCPA.

+-----------+-----------+----------+----------+----------+----------+
| **TABLE   |           |          |          |          |          |
| III.l.    |           |          |          |          |          |
| N         |           |          |          |          |          |
| on-target |           |          |          |          |          |
| Insects - |           |          |          |          |          |
| Acute     |           |          |          |          |          |
| Contact   |           |          |          |          |          |
| for MCPB  |           |          |          |          |          |
| Sodium    |           |          |          |          |          |
| (ai)/MCPB |           |          |          |          |          |
| Acid      |           |          |          |          |          |
| (ae)**    |           |          |          |          |          |
+===========+===========+==========+==========+==========+==========+
| **        | *         | **       | **       | **MRID   | **Study  |
| Species** | *LD~50~** | LD~50~** | Toxicity | No.**    | Classifi |
|           |           |          | Ca       |          | cation** |
|           | **(µg     | **(µg    | tegory** | **Autho  |          |
|           | ai/bee)** | a        |          | r/Year** |          |
|           |           | e/bee)** |          |          |          |
+-----------+-----------+----------+----------+----------+----------+
| Honey Bee | \>25      | \>23     | Re       | 42532607 | Ac       |
|           |           |          | latively |          | ceptable |
| *(Apis    |           |          |          | Maggi,   |          |
| me        |           |          | n        | 1992     |          |
| llifera)* |           |          | on-toxic |          |          |
+-----------+-----------+----------+----------+----------+----------+

*Insects, Residual Contact*

A honey bee toxicity of residues on foliage study is required on an
end-use product for any pesticide intended for outdoor application when
the proposed use pattern indicates that honey bees may be exposed to the
pesticide and when the formulation contains one or more active
ingredients having an acute contact honey bee LD~50~ which falls in the
moderately toxic or highly toxic range. The purpose of this guideline
study is to develop data on the residual toxicity to honey bees. Bee
mortality determinations are made from bees exposed to treated foliage
harvested at various time periods after treatment. No residue toxicity
study was submitted by the registrant; however, the acute contact honey
bee LD~50~ falls in the relatively non-toxic range.

*Terrestrial Plants*

Terrestrial Tier II studies are required for any pesticide showing a
negative response equal to or greater than 25% in Tier I studies. Tier I
and II terrestrial plant toxicity studies were conducted to establish
the toxicity of MCPB to non-target terrestrial plants. The
recommendations for seedling emergence and vegetative vigor studies are
for testing of (1) six species of at least four dicotyledonous families,
one species of which is soybean (*Glycine max*) and the second of which
is a root crop, and (2) four species of at least two monocotyledonous
families, one of which is corn (*Zea mays*). The guidelines (122-1a;
122-1b; 123-1a; 123-1b) are fulfilled (MRID 42560804). The guideline
study met the requirements for Tier II seedling emergence testing for
all ten required species; for Tier II vegetative vigor testing for
cabbage, cucumber, lettuce, onion, ryegrass, radish, soybean, and
tomato; and for Tier I vegetative vigor testing for corn and oat. Tier
II vegetative vigor testing was not required for corn and oat because
results from Tier I testing showed that \<25% detrimental effects were
observed from the maximum label rate.

These studies indicate that the most sensitive monocot species in
seedling emergence tests was the onion with the lowest EC~25~ of 0.02 lb
ae/A based on shoot length. This value represents 0.093% of the maximum
application rate for MCPB sodium. The most sensitive dicot species
tested was cabbage with an EC~25~ of 0.016 lb ae/A in the seedling
emergence study based on shoot length. The most sensitive monocot in the
vegetative vigor test was also onion, with an EC25 of 0.016 lb ae/A
based on shoot weight. The most sensitive dicot species tested was
tomato with an extrapolated EC~25~ of 0.0017 lb ae/A in the seedling
emergence study based on shoot weight.

The observed non-lethal effects included brown leaf tips in cabbage,
corn, onion, ryegrass, radish, and soybean; necrosis in corn, radish,
onion, and soybean; chlorosis in onion, cucumber, and lettuce; stem
tumors in soybean and tomato; leaf curl in tomato, and decreased size in
cabbage, cucumber, lettuce, onion, and ryegrass.

There is significant uncertainty in the vegetative vigor EC~25~ values
for dicots, because they were extrapolated below the lowest dose tested
in the study. Furthermore, the NOEC values reported in the original
study were reported as being higher than the EC~25~ values. Further
extrapolation of the data needs to be done to derive EC~05~ values from
the dose response curves for the vegetative vigor study. The uncertainty
in these EC~05~ values will be high; new data with lower application
rates which bracket observed EC~25~ and EC~05~ levels would improve the
assessment of potential risks to nonendangered and endangered/listed
terrestrial plants.

Results of Tier II toxicity tests with the soil degradate MCPA indicate
that it also adversely affects seedling emergence and vegetative vigor
in monocots and dicots. As with MCPB, onion was the most sensitive
monocot tested with the lowest EC~25~ of 0.028 lb ae/A in the seedling
emergence test. The most sensitive dicot species tested was cabbage with
an EC~25~ of 0.008 lb ae/A in the seedling emergence study. The most
sensitive dicot in the vegetative vigor test were the lettuce and turnip
with an EC~25~ of 0.013 lb ae/A (MRID 43083205).

*Terrestrial Field Studies*

The requirement for terrestrial field studies was waived.

+------+-------+-------+-----+-----+------+------+-------+---------+
| **T  |       |       |     |     |      |      |       |         |
| ABLE |       |       |     |     |      |      |       |         |
| II   |       |       |     |     |      |      |       |         |
| I.m. |       |       |     |     |      |      |       |         |
| Ter  |       |       |     |     |      |      |       |         |
| rest |       |       |     |     |      |      |       |         |
| rial |       |       |     |     |      |      |       |         |
| No   |       |       |     |     |      |      |       |         |
| n-ta |       |       |     |     |      |      |       |         |
| rget |       |       |     |     |      |      |       |         |
| P    |       |       |     |     |      |      |       |         |
| lant |       |       |     |     |      |      |       |         |
| Tox  |       |       |     |     |      |      |       |         |
| icit |       |       |     |     |      |      |       |         |
| y.** |       |       |     |     |      |      |       |         |
| ^\*^ |       |       |     |     |      |      |       |         |
+------+-------+-------+-----+-----+------+------+-------+---------+
| **S  | **See |       | **V |     |      |      |       |         |
| peci | dling |       | ege |     |      |      |       |         |
| es** | E     |       | tat |     |      |      |       |         |
|      | merge |       | ive |     |      |      |       |         |
|      | nce** |       | V   |     |      |      |       |         |
|      |       |       | igo |     |      |      |       |         |
|      |       |       | r** |     |      |      |       |         |
+------+-------+-------+-----+-----+------+------+-------+---------+
|      | **    |       | **R |     | **S  |      | **    |         |
|      | Shoot |       | oot |     | hoot |      | Shoot |         |
|      | len   |       | we  |     | leng |      | wei   |         |
|      | gth** |       | igh |     | th** |      | ght** |         |
|      |       |       | t** |     |      |      |       |         |
+------+-------+-------+-----+-----+------+------+-------+---------+
|      | **E   | **E   | **  | **  | *    | *    | **E   | **EC~2  |
|      | C~25~ | C~25~ | EC~ | EC~ | *EC~ | *EC~ | C~25~ | 5~/NOEC |
|      | /NOEC | /NOEC | 25~ | 25~ | 25~/ | 25~/ | /NOEC | (lb     |
|      | (lb   | (lb   | /** | /** | NOEC | NOEC | (lb   | ae/A)** |
|      | ai    | ae    |     |     | (lb  | (lb  | ai    |         |
|      | /A)** | /A)** | **N | **N | ai/  | ae/  | /A)** |         |
|      |       |       | OEC | OEC | A)** | A)** |       |         |
|      |       |       | (lb | (lb |      |      |       |         |
|      |       |       | a   | a   |      |      |       |         |
|      |       |       | i/A | e/A |      |      |       |         |
|      |       |       | )** | )** |      |      |       |         |
+------+-------+-------+-----+-----+------+------+-------+---------+
| **Mo |       |       |     |     |      |      |       |         |
| noco |       |       |     |     |      |      |       |         |
| ts** |       |       |     |     |      |      |       |         |
+------+-------+-------+-----+-----+------+------+-------+---------+
| Corn | 0.23  | 0.21  | --  | --  | --   | --   | --    | --      |
|      | /0.19 | /0.17 |     |     |      |      |       |         |
+------+-------+-------+-----+-----+------+------+-------+---------+
| Oat  | 0.12/ | 0.11  | --  | --  | --   | --   | --    | --      |
|      | 0.093 | /0.08 |     |     |      |      |       |         |
+------+-------+-------+-----+-----+------+------+-------+---------+
| O    | 0     | 0.02  | --  | --  | --   | --   | 0.0   | 0.016   |
| nion | .021/ | /0.01 |     |     |      |      | 18/\< | /\<0.08 |
|      | 0.012 |       |     |     |      |      | 0.088 |         |
+------+-------+-------+-----+-----+------+------+-------+---------+
| Ryeg | 0.48  | 0.44  | --  | --  | --   | --/  | --    | --      |
| rass | /\*\* | /\*\* |     |     | /1.3 | 1.18 |       |         |
+------+-------+-------+-----+-----+------+------+-------+---------+
|      |       |       |     |     |      |      |       |         |
+------+-------+-------+-----+-----+------+------+-------+---------+
| **   |       |       |     |     |      |      |       |         |
| Dico |       |       |     |     |      |      |       |         |
| ts** |       |       |     |     |      |      |       |         |
+------+-------+-------+-----+-----+------+------+-------+---------+
| Cab  | 0     | 0.016 | --  | --  | 0.24 | 0.21 | 0.007 | 0.      |
| bage | .017/ | /0.01 | /0. | /0. | /\-- | /\-- | 9/\-- | 0072/-- |
|      | 0.012 |       | 088 | 080 |      |      |       |         |
+------+-------+-------+-----+-----+------+------+-------+---------+
| Cucu | 0.10/ | 0     | --  | --  | 0    | 0    | --    | --      |
| mber | 0.093 | .091/ |     |     | .53/ | .48/ |       |         |
|      |       | 0.085 |     |     | 0.34 | 0.31 |       |         |
+------+-------+-------+-----+-----+------+------+-------+---------+
| Let  | 0.059 | 0.054 | 0.  | \-  | 0.05 | 0    | 0.017 | 0.0     |
| tuce | /\*\* | /\*\* | 027 | -0. | 5/-- | .050 | /\*\* | 15/\*\* |
|      |       |       | /-- | 025 |      | /\-- |       |         |
|      |       |       |     | /-- |      |      |       |         |
+------+-------+-------+-----+-----+------+------+-------+---------+
| Ra   | 0.045 | 0.041 | --  | --  | 0.   | 0.   | --    | --      |
| dish | /\*\* | /\*\* |     |     | 22/0 | 20/0 |       |         |
|      |       |       |     |     | .043 | .039 |       |         |
+------+-------+-------+-----+-----+------+------+-------+---------+
| Soy  | 0.13/ | 0.12/ | 0.  | 0.  | 0.4  | 0.4  | 0.072 | 0.0     |
| bean | 0.048 | 0.044 | 14/ | 13/ | 5/-- | 1/-- | /\*\* | 66/\*\* |
|      |       |       | \-- | \-- |      |      |       |         |
+------+-------+-------+-----+-----+------+------+-------+---------+
| To   | 0.17/ | 0.15/ | --  | \-- | 0.4  | 0.4  | 0     | 0.00    |
| mato | 0.093 | 0.085 |     |     | 5/-- | 1/-- | .0017 | 15/\*\* |
|      |       |       |     |     |      |      | /\*\* |         |
+------+-------+-------+-----+-----+------+------+-------+---------+

^\*^MRID 42560804, Study author: K. Christensen, 1992, 38.9% active
ingredient.

^\*^NOEC reported in study higher than EC~25~. Further statistical
analysis needed to establish EC~05~ for endangered species assessment.

39

**IV. RISK CHARACTERIZATION**

Risk characterization provides the final step in the risk assessment
process. In this step, exposure and effects characterization are
integrated to provide an estimate of risk relative to established levels
of concern (LOCs). The results are then interpreted for the risk manager
through a risk description and synthesized into an overall conclusion.

**A. Risk Estimation - Integration of Exposure and Effects Data**

**1. Non-target Aquatic Animals and Plants**

Estimated environmental concentrations (EECs) from ground and aerial
spray scenarios were calculated using the PRZM 3.12/EXAMS 2.98 Oregon
snap bean scenario and California lettuce scenario. As described in the
exposure characterization, the input parameters were adjusted to account
for degradates MCPA and CHPA-hexose, which accounted for a maximum of
6 - 7% of MCPB in the aerobic soil metabolism study. Since MCPA has been
shown to be less toxic to aquatic organisms than parent MCPB, and the
toxicity of CHPA-hexose is not known, the inclusion of these residues in
the aquatic exposure modeling may be a conservative assumption.

*Fish and Invertebrates*

For ground and aerial spray scenarios using the PRZM 3.12/EXAMS 2.98
Oregon snap bean scenario and California lettuce scenario, the aquatic
Acute Risk, Acute Restricted Use, and Endangered Species LOCs were not
exceeded for freshwater fish and invertebrates with the assumption of
the maximum estimated concentration of MCPB acid in the water body under
consideration.

Table IV.a. has summarized the risk quotients for freshwater fish and
invertebrates with Oregon and California PRZM 3.12/EXAMS 2.98 scenarios.

  ---------------------------------------------------------------------------
  **TABLE IV.a. Summarized Acute Aquatic                
  Organism Risk Quotients for MCPB                      
  Acid^a,b,c,d^**                                       
  -------------------------------------- -------------- ---------------------
  **Application/Scenario**               **Freshwater   **Freshwater
                                         Fish**         Invertebrates**

  Peas (ground spray application) Oregon \<0.01         \<0.01

  Peas (aerial spray application) Oregon \<0.01         \<0.01

  Peas (ground spray application)        0.01           \<.0.01
  California                                            

  Peas (aerial spray application)        0.01           \<0.01
  California                                            
  ---------------------------------------------------------------------------

^a^ Detailed calculations of PRZM 3.12/EXAMS 2.98 modeling for peas
grown in Oregon and California are provided in Appendix B.

^b^ Acute toxicity thresholds (LC~50~ or EC~50~) were 3.9 and 50 mg ae/L
for freshwater fish and freshwater invertebrates, respectively.

^C^ EECs for Oregon bean Scenario were 29.7 and 33.4 µg/L for ground
spray and aerial spray, respectively.

^D^EECs for California lettuce Scenario were 40.6 and 43.4 µg/L for
ground spray and aerial spray, respectively.

Chronic risk to freshwater and estuarine marine fish and invertebrates
cannot be assessed because chronic toxicity data have not been
submitted.

*Aquatic Plants*

For MCPB acid runoff/drift, there were no exceedances of the
non-endangered Acute Risk LOC for the pea scenarios that were modeled
(Table IV.b.). However, the LOCs for endangered freshwater vascular
plants could not be assessed due to a non-discreet NOEC value.

+----------------------------+----------+-----------+-----------------+
| **TABLE IV.b. Summarized   |          |           |                 |
| Acute Aquatic Plant Risk   |          |           |                 |
| Quotients for MCPB Acid**  |          |           |                 |
+============================+==========+===========+=================+
| **Application/Scenario**   | **Enda   | **Non-end |                 |
|                            | ngered** | angered** |                 |
|                            |          |           |                 |
|                            | **fr     |           |                 |
|                            | eshwater |           |                 |
|                            | va       |           |                 |
|                            | scular** |           |                 |
+----------------------------+----------+-----------+-----------------+
|                            |          | **F       | **Freshwater**  |
|                            |          | reshwater |                 |
|                            |          | v         | *               |
|                            |          | ascular** | *non-vascular** |
+----------------------------+----------+-----------+-----------------+
| Peas (ground spray         | N/A      | 0.14      | 0.08            |
| application) Oregon        |          |           |                 |
+----------------------------+----------+-----------+-----------------+
| Peas (aerial spray         | N/A      | 0.16      | 0.09            |
| application) Oregon        |          |           |                 |
+----------------------------+----------+-----------+-----------------+
| Peas (ground spray         | N/A      | 0.19      | 0.10            |
| application) California    |          |           |                 |
+----------------------------+----------+-----------+-----------------+
| Peas (aerial spray         | N/A      | 0.21      | 0.11            |
| application) California    |          |           |                 |
+----------------------------+----------+-----------+-----------------+

**2. Non-target Terrestrial Animals and Plants**

The following Table IV.c. summarizes the endpoints used in this
assessment for RQ evaluation for non-target terrestrial animals and
plants:

+-------------------------+------------------------------+-------------+
| **TABLE IV.c. Summary   |                              |             |
| of endpoints for MCPB   |                              |             |
| acute terrestrial       |                              |             |
| toxicity studies for RQ |                              |             |
| evaluation^a^**         |                              |             |
+-------------------------+------------------------------+-------------+
| **Species**             | **toxicity value used in     | **MRID#**   |
|                         | risk assessment in ae**      |             |
+-------------------------+------------------------------+-------------+
| bird (oral gavage       | 257                          | 42560801    |
| dose), LD~50~, mg       |                              |             |
| ae/kg-bw                |                              |             |
+-------------------------+------------------------------+-------------+
| mammal, LD~50~, mg      | 832                          | 116340      |
| ae/kg-bw                |                              |             |
+-------------------------+------------------------------+-------------+
| honey bee, LD~50~, µg   | 23                           | 42532607    |
| ae/bee                  |                              |             |
+-------------------------+------------------------------+-------------+
| terrestrial monocots    | 0.02                         | 42560804    |
| emergence, EC~25~, lbs  |                              |             |
| ae/ac                   |                              |             |
+-------------------------+------------------------------+-------------+
| terrestrial dicots      | 0.016                        | 42560804    |
| emergence,              |                              |             |
|                         |                              |             |
| EC~25~, lbs ae/ac       |                              |             |
+-------------------------+------------------------------+-------------+
| terrestrial monocots    | 0.018                        | 42560804    |
| vegetative vigor,       |                              |             |
| EC~25~, lbs ae/ac       |                              |             |
+-------------------------+------------------------------+-------------+
| terrestrial dicots      | 0.0017                       | 42560804    |
| vegetative vigor,       |                              |             |
|                         |                              |             |
| EC~25~, lbs ae/ac       |                              |             |
+-------------------------+------------------------------+-------------+

^a^ Details for each study are presented in earlier sections of this
document and in Appendix F.

*Birds*

Acute avian RQs were calculated using the oral gavage study with
bobwhite quail, which resulted in a 14-day LD~50~ of 257 mg ae/kg-bw
(MRID 42560801). Assuming the maximum application rate (

1.5 lbs ae/acre) and maximum predicted residue levels, acute risk, acute
restricted use and endangered species LOCs were exceeded for 20 g and
100g birds. Acute restricted use and endangered species LOCs were
exceeded for 1000g birds.

As shown in Table IV.d., the acute LOC is exceeded for 20 g and 100 g
birds for short grass and broadleaf forage and small insect feed items.
The acute LOC is also exceeded for 20 g birds for tall grass feed, and
nearly so for 100 g birds. The endangered species LOC is exceeded for
all weight classes for short grass, broadleaf forage and small insects,
and tall grass feed items. The endangered species LOC is also exceeded
for 20 g birds consuming fruits, pods, seeds, and large insects. The
endangered species LOC is exceeded for short grass even if mean residues
are considered.

RQs were not calculated based on the acute dietary studies because no
mortalities occurred at the highest concentration tested (LC~50~ \> 4550
mg ae/kg-diet). In addition, the data evaluation records noted
inconsistencies in the reporting of the measured concentrations of the
chemical in the diet. Because of the lack of mortality in the acute
dietary study, there is some uncertainty in the overall finding of
potential acute risk to birds.

+------------------------+----------+-----------------+----------------+
| **TABLE IV.d. Avian    |          |                 |                |
| Acute Risk Quotient    |          |                 |                |
| Summary ^a,b,c,d^**    |          |                 |                |
+------------------------+----------+-----------------+----------------+
| **Food type**          | **Weight | **1.5 lbs       |                |
|                        | class    | ae/acre**       |                |
|                        | (g)**    |                 |                |
+------------------------+----------+-----------------+----------------+
|                        |          | **Acute RQ^d^** |                |
+------------------------+----------+-----------------+----------------+
|                        |          | **predicted     | **predicted    |
|                        |          | maximum         | mean           |
|                        |          | residues**      | residues**     |
+------------------------+----------+-----------------+----------------+
| short grass            | 20       | 2.26\*\*\*      | 0.80\*\*\*     |
+------------------------+----------+-----------------+----------------+
|                        | 100      | 1.01\*\*\*      | 0.36\*\*       |
+------------------------+----------+-----------------+----------------+
|                        | 1000     | 0.32\*\*        | 0.11\*         |
+------------------------+----------+-----------------+----------------+
| tall grass             | 20       | 1.03\*\*\*      | 0.34\*\*       |
+------------------------+----------+-----------------+----------------+
|                        | 100      | 0.46\*\*        | 0.15\*         |
+------------------------+----------+-----------------+----------------+
|                        | 1000     | 0.15\*          | 0.05           |
+------------------------+----------+-----------------+----------------+
| broadleaf forage,      | 20       | 1.27\*\*\*      | 0.42\*\*       |
| small insects          |          |                 |                |
+------------------------+----------+-----------------+----------------+
|                        | 100      | 0.57\*\*\*      | 0.19\*         |
+------------------------+----------+-----------------+----------------+
|                        | 1000     | 0.18\*          | 0.06           |
+------------------------+----------+-----------------+----------------+
| fruit, pods, seeds,    | 20       | 0.14\*          | 0.07           |
|                        |          |                 |                |
| large insects          |          |                 |                |
+------------------------+----------+-----------------+----------------+
|                        | 100      | 0.06            | 0.03           |
+------------------------+----------+-----------------+----------------+
|                        | 1000     | 0.02            | 0.01           |
+------------------------+----------+-----------------+----------------+

RQ values are dose base calculations

\* indicates an exceedance of Endangered Species Level of Concern (LOC);
RQ \> 0.10.

\*\* indicates an exceedance of Acute Restricted Use LOC; RQ \> 0.20.

\*\*\* indicates an exceedance of Acute Risk LOC; RQ \> 0.50.

*Mammals*

To evaluate the acute risk to mammals, RQs were calculated using the
minimum LD~50~ obtained from the acute oral studies (832 mg ae/kg-bwt,
MRID 116340) at the maximum labeled rate of 1.5 lbs ae/acre. To evaluate
the chronic (developmental/reproductive) risk to mammals, RQs were
calculated using the NOAEL for maternal toxicity obtained from the
rabbit developmental toxicity study with MCPB acid equivalent (NOAEL=
4.56 mg ae/kg/day, MRID 40865401). The exposure model T-REX is set up to
calculate RQs for the laboratory rat, which is the typical surrogate
species for environmental risk assessments. Because the toxicity study
for rabbit was used in this case, the toxicity values for the rabbit
study were adjusted for a 3000 g rabbit in T-REX model. The RQs are
detailed in Tables IV.e. and IV.f. and they are summarized in Appendix
F.

Assuming maximum residue levels at the maximum single application rate
(1.5 lbs ae/acre), the Acute Endangered Species Risk LOC was exceeded
for small mammals (15 g and 35g) consuming short grass (RQ = 0.19 and
0.16, respectively) and for small mammals (15 g) consuming broadleaf
forage and small insects (RQ = 0.11). Acute and acute restricted use
LOCs were not exceeded. There were no exceedences of the risk LOCs by
mammals consuming foods at the predicted mean MCPB residue levels.

  ------------------ ----------------- ----------------- -----------------
  **TABLE IV.e.                                          
  Mammalian Acute                                        
  Risk Quotient                                          
  Summary**                                              

  **Food type**      **Weight class    **1.5 lbs         
                     (g)**             ae/acre**         

                                       **Predicted       **Predicted mean
                                       maximum           residues**
                                       residues**        

  short grass        15                0.19\*            0.07

                     35                0.16\*            0.06

                     1000              0.08              0.03

  tall grass         15                0.09              0.03

                     35                0.07              0.02

                     1000              0.04              0.01

  broadleaf forage,  15                0.11\*            0.04
  small insects                                          

                     35                0.09              0.03

                     1000              0.05              0.02

  fruit, large       15                0.01              0.01
  insects                                                

                     35                0.01              \<0.01

                     1000              0.01              \<0.01

  seeds, pods        15                \<0.01            \<0.01

                     35                \<0.01            \<0.01

                     1000              \<0.01            \<0.01
  ------------------ ----------------- ----------------- -----------------

\* indicates an exceedance of Endangered Species Level of Concern (LOC);
RQ \> 0.10.

Assuming maximum and mean residue levels at the maximum application
rate, Chronic Risk LOCs were exceeded in all weight classes (15 g, 35 g,
and 1000g) of mammals for consumption of short grass, tall grass and
broadleaf forage/small insects. Assuming maximum residue levels at the
maximum application rate, Chronic Risk LOCs were exceeded in 15 g and
35g mammals for consumption of fruit and large insects.

  ------------------ ----------------- ----------------- -----------------
  **TABLE IV.f.                                          
  Mammalian Chronic                                      
  Risk Quotient                                          
  Summary**                                              

  **Food type**      **Weight class    **1.5 lbs         
                     (g)**             ae/acre**         

                                       **Predicted       **Predicted mean
                                       maximum           residues**
                                       residues**        

  short grass        15                19.94\*           6.44\*

                     35                17.12\*           5.53\*

                     1000              9.00\*            2.91\*

  tall grass         15                9.14\*            2.73\*

                     35                7.85\*            2.34\*

                     1000              4.12\*            1.23\*

  broadleaf forage,  15                11.22\*           3.41\*
  small insects                                          

                     35                9.63\*            2.93\*

                     1000              5.06\*            1.54\*

  fruit, large       15                1.25\*            0.53
  insects                                                

                     35                1.07\*            0.46

                     1000              0.56              0.24

  seeds, pods        15                0.47              0.12

                     35                0.24              0.1

                     1000              0.11              0.08
  ------------------ ----------------- ----------------- -----------------

\* indicates an exceedance of Chronic LOC, RQ \> 1.0.

*Terrestrial Non-Target Insects*

EFED currently does not quantify risks to terrestrial non-target
insects; therefore, risk quotients are not calculated for these
organisms. Risks are qualitatively discussed in the Terrestrial Organism
Risk Characterization section of this document.

**3. Non-target Terrestrial Plants in Dryland and Semi-aquatic Areas:**
An analysis of the results indicates exceedance of the Acute Risk LOC
for non-endangered monocots and dicots in dryland and semi-aquatic areas
located adjacent to treated areas, both as a result of combined runoff
and spray drift, and from spray drift alone. (Table IV.g). The
Endangered Species LOC was exceeded for monocots and dicots located
adjacent to treated areas and in semi-aquatic areas and for dicots as a
result of spray drift. The most sensitive seedling emergence EC~25~
values were 0.02 and 0.016 lb ae/acre for monocots and dicots,
respectively. These values are used to calculate risk quotients for
exposure from combined runoff and spray drift to adjacent fields.

Risk to terrestrial plants from spray drift alone is evaluated by
comparing the estimated exposure from drift to the most sensitive EC~25~
calculated from vegetative vigor laboratory tests. Among monocot species
tested, only onion showed sensitivity to MCPB in the vegetative vigor
test, with an EC~25~ of 0.016 a.e/acre, based on reductions in shoot
weight. Based on this value, the acute LOC for monocots is exceeded. A
NOEC could not be established in this study, but the exceedence of the
LOC for nonendangered plants indicates that risk to endangered and
listed monocots is also a concern. The fact that effects (and therefore
risk) were indicated for only one of four monocots tested suggests that
only a subset of non-target monocots may be at risk. The fact that
monocots are not broadly sensitive is consistent with the fact that MCPA
is an herbicide used to control broadleaf weeds.

Reduction in shoot weight was the most sensitive endpoint for the four
most sensitive dicots tested in the vegetative vigor study. However, the
magnitude of the EC~25~ values is uncertain because they were
extrapolated below the lowest dose tested in the study. For instance,
although the calculated EC~25~ for MCPB on tomato is 0.0015 lb ae/acre,
the lowest application rate tested in this study was 0.08 lb ai/acre.
Similarly, the EC~25~ of 0.015 for lettuce was extrapolated below the
lowest application rate of 0.039. Based on these EC~25~ values, however,
the RQs exceed the level of concern.

Because RQs based on the EC~25~ values exceed the acute LOC, and
exposure can be expected which would cause greater than a 25% effect,
risk to endangered plants is also a concern. However, risk quotients
with which to evaluate risk from spray drift to endangered plants were
not calculated because the NOEC values in the [vegetative
vigor]{.underline} study for the dicots were reported as being higher
than the EC~25~ values. A NOEC could not be determined for onion, the
only monocot tested which was sensitive to MCPB. Therefore, a RQ could
not be derived for comparison to the endangered species LOC.

Further extrapolation of the data needs to be done to derive EC~05~
values from the dose response curves for the vegetative vigor study. The
uncertainty in these EC~05~ values will be high; new data with lower
application rates which bracket observed EC~25~ and EC~05~ levels would
improve the assessment of potential risks to nonendangered and
endangered/listed terrestrial plants.

Detailed calculations for plant risk quotients are presented in Appendix
F.

+--------+---------+---------+--------+---------+---------+---------+
| *      |         |         |        |         |         |         |
| *TABLE |         |         |        |         |         |         |
| IV.g.  |         |         |        |         |         |         |
| Summ   |         |         |        |         |         |         |
| arized |         |         |        |         |         |         |
| Terre  |         |         |        |         |         |         |
| strial |         |         |        |         |         |         |
| Plant  |         |         |        |         |         |         |
| Risk   |         |         |        |         |         |         |
| Quoti  |         |         |        |         |         |         |
| ents** |         |         |        |         |         |         |
+========+=========+=========+========+=========+=========+=========+
| **Scen | **Acute |         |        | **Acute |         |         |
| ario** | Non-end |         |        | End     |         |         |
|        | angered |         |        | angered |         |         |
|        | RQs**   |         |        | RQs**   |         |         |
+--------+---------+---------+--------+---------+---------+---------+
|        | **A     | **Semi- | **D    | **A     | **Semi- | **      |
|        | djacent | aquatic | rift** | djacent | aquatic | Drift** |
|        | to**    | areas** |        | to**    | areas** |         |
|        |         |         |        |         |         |         |
|        | **      |         |        | **      |         |         |
|        | treated |         |        | treated |         |         |
|        | sites** |         |        | sites** |         |         |
+--------+---------+---------+--------+---------+---------+---------+
| **     |         |         |        |         |         |         |
| Ground |         |         |        |         |         |         |
| spray  |         |         |        |         |         |         |
| appli  |         |         |        |         |         |         |
| cation |         |         |        |         |         |         |
| (1.5   |         |         |        |         |         |         |
| lbs    |         |         |        |         |         |         |
| ae/a   |         |         |        |         |         |         |
| cre)** |         |         |        |         |         |         |
+--------+---------+---------+--------+---------+---------+---------+
| M      | 4.5     | 38.2    | 0.94   | 9.00\*  | 76.50\* | \--     |
| onocot | 0\*\*\* | 5\*\*\* |        |         |         |         |
+--------+---------+---------+--------+---------+---------+---------+
| Dicot  | 5.6     | 47.8    | 2.08   | 9.00\*  | 76.50\* | \--     |
|        | 3\*\*\* | 1\*\*\* | \*\*\* |         |         |         |
+--------+---------+---------+--------+---------+---------+---------+
| **     |         |         |        |         |         |         |
| Aerial |         |         |        |         |         |         |
| spray  |         |         |        |         |         |         |
| appli  |         |         |        |         |         |         |
| cation |         |         |        |         |         |         |
| (1.5   |         |         |        |         |         |         |
| lbs    |         |         |        |         |         |         |
| ae/a   |         |         |        |         |         |         |
| cre)** |         |         |        |         |         |         |
+--------+---------+---------+--------+---------+---------+---------+
| M      | 6.0     | 26.2    | 4.69   | 12.00\* | 52.50\* | \--     |
| onocot | 0\*\*\* | 5\*\*\* | \*\*\* |         |         |         |
+--------+---------+---------+--------+---------+---------+---------+
| Dicot  | 7.5     | 32.8    | 10.42  | 12.00\* | 52.50\* | \--     |
|        | 0\*\*\* | 1\*\*\* | \*\*\* |         |         |         |
+--------+---------+---------+--------+---------+---------+---------+

\* indicates an exceedance of the Endangered Species Level of Concern
(LOC).

\*\*\* indicates an exceedance of the Acute Risk LOC.

**B. Risk Description**

**1. Risks to Aquatic Organisms:** In the conceptual model, spray drift
and runoff to adjacent bodies of water were predicted as the most likely
sources of MCPB and MCPB sodium exposure to nontarget aquatic organisms.

*Fish and Invertebrates*

Based on acute risk quotients below the levels of concern, freshwater
fish and invertebrates inhabiting surface waters adjacent to MCPB
treated fields do not appear to be at risk for adverse acute effects on
growth and survival. Toxicity studies are not available to determine the
potential chronic effects to fish and invertebrates and acute risks to
estuarine marine fish and estuarine marine invertebrates. Therefore, a
complete risk assessment cannot be done for fish and invertebrates, and
it is not possible to certify that MCPB use is "not likely to adversely
affect" listed fish and invertebrates.

*Aquatic Plants*

Toxicity studies with aquatic plant species indicate that exposure to
MCPB results in significantly adverse effects to growth and development.
The EC~50~ for the freshwater vascular plant (duckweed) is 0.21 mg ae/L,
based on reduced frond production; and the lowest EC~50~ for the
freshwater non-vascular plant (green algae) is 0.38 mg ae/L, based on
reduced cell density. Concentrations as low as 0.13 mg ae/L resulted in
chlorosis, curling, and decreased root formation in the aquatic vascular
plant, duckweed. In addition, frond biomass was significantly reduced at
0.42 mg ae/L.

> For MCPB acid runoff/drift, there were no exceedances of the
> non-endangered Acute Risk LOC for the pea scenarios that were modeled
> (Table IV.b.). However, it is not possible to calculate risk quotients
> to compare to the endangered species LOC, since a definitive NOEC was
> not determined for duckweed and green algae.

**2. Risks to Terrestrial Organisms:** In the conceptual model, ground
deposition and spray drift with resulting residues on foliage, on
flowers and seeds, and soil invertebrates were predicted as the most
likely sources of MCPB and MCPB sodium exposure to nontarget terrestrial
organisms. An additional predicted source of exposure to MCPB sodium was
in puddled water on treated fields through preening and grooming,
involving the oral ingestion of material from the feathers or fur.

> Risks to terrestrial organisms (i.e. birds, mammals, and plants) were
> assessed based on modeled Estimated Environmental Concentrations
> (EECs) and available toxicity data. As part of the terrestrial
> assessment, EFED modeled exposure concentrations of MCPB to nontarget
> terrestrial plants and animals following the proposed application
> rates provided by the registrant. For terrestrial birds and mammals,
> estimates of initial levels of MCPB residues on various food items,
> which may be contacted or consumed by wildlife, were determined using
> the Kenega-Fletcher nomogram followed by a first order decline model
> TREX 1.1. Likewise, the TerrPlant 1.0 model estimated exposure to
> nontarget plants and the AgDrift 2.0.1 model provided further
> refinement of spray drift dispersion and deposition to terrestrial
> plants located in proximity to treated fields.
>
> *Birds*
>
> MCPB is categorized as moderately toxic to avian species on an acute
> oral basis (14-day LD~50~ 257 mg ae/kg); but is practically non-toxic
> to avian species on an acute dietary basis (8-day LD~50~ \>4,550 ppm
> ae). In the oral study, the bobwhite quail exhibited sublethal
> effects; including reduced body weight gain (dietary exposure),
> lethargy, dyspnea, loss of righting reflex and diarrhea. Gross
> necropsy of birds in both the oral gavage and dietary studies showed
> white areas/film on the heart, liver (dietary exposure), gizzard,
> gallbladder, crop or intestines. The 8-day NOELs for each species in
> the dietary study, based on sublethal effects (reduced body weight
> gain), were 1138 ppm ae.
>
> Based on these acute toxicity data, there is a large differential in
> the acute lethality when MCPB is administered as a single gavage or
> when mixed in the feed. However, there are limitations to both the
> dose-based and dietary-based method of calculating risk quotients. The
> dose-based approach assumes that the uptake and absorption kinetics of
> a gavage toxicity study approximate the absorption associated with
> uptake from a dietary matrix. Toxic response is a function of duration
> and intensity of exposure and the importance of absorption kinetics
> across the gut and enzymatic activation/deactivation of a toxicant may
> be important and are likely to be variable across chemicals and
> species.
>
> For many compounds a gavage dose represents a very short-term high
> intensity exposure, whereas dietary exposure may be of a more
> prolonged nature. The dietary approach assumes that animals in the
> field are consuming food at a rate similar to that of confined
> laboratory animals. The strength of this assumption is uncertain,
> because energy content in food items differs between the field and in
> the laboratory, as do the energy requirements of wild and captive
> animals.
>
> In any case, because sublethal effects were observed in both studies,
> including the dietary study at doses \> 569 ppm ae, sublethal risks to
> avian species using the treated fields or inhabiting adjacent edge or
> riparian communities could result from the labeled use of MCPB.

Avian reproduction studies using the TGAI are usually required for
pesticide registration because birds may be subject to repeated or
continuous exposure to the pesticide, especially preceding or during the
breeding season. The preferred test species are mallard duck and
bobwhite quail. No chronic bird studies were submitted for MCPB.

EFED considered MCPA as a substitute for MCPB for chronic risk to birds,
because the LD50 for bobwhite quail suggests that the acute potency of
MCPB lies within the range of toxicity for acid equivalent MCPA. Also,
rapid dissociation of MCPB to MCPA is expected to occur in the bird gut
due to the chemical properties of MCPB.

The chronic bird study for MCPA with bobwhite quail has a NOAEC of 1000
mg/kg-diet ( MRID \# 435052-01) . No further studies are required for
chronic risk to birds for MCPB at this time.

> *Mammals*
>
> MCPB is classified as slightly toxic to practically non-toxic to small
> mammals on an acute oral basis (LD~50~ values range from 912 - 7,400
> mg ai/kg/day). Reproductive effects were observed in dogs at 44 mg
> ai/kg/day based on reduced testes weights and physiological changes in
> clinical chemistry. In developmental studies with rats and rabbits,
> maternal toxicity was observed at doses ranging from 20 - 100 mg
> ai/kg/day. In the rat study, the maternal toxicity observed at 100 mg
> ai/kg/day included decreased body weights and body weight gains during
> gestation. In the rabbit study, maternal toxicity observed at 20 mg
> ai/kg/day included maternal deaths, clinical signs of toxicity,
> decrease in body weight gain during treatment, and change in color of
> liver and kidneys. The maternal toxicity NOAEL for this study was 5 mg
> ai/kg/day. Developmental effects were observed in rats at a dose of
> 100 mg/kg/day, including decreased mean body weights/litter for males
> and females, increases in unossified or poorly ossified sites and
> increases in several other skeletal variations.
>
> The risk assessment and calculated RQs assume 100% of the diet is
> relegated to single food types foraged only from treated fields.
> However, because the Chronic LOCs are exceeded for multiple food
> categories, potential exposure may still be high enough to warrant
> concern. Other exposure routes are possible for animals residing in or
> moving through treated areas. Ingestion of contaminated soils, dermal
> contact, and inhalation are not considered in this screening
> assessment, and represent potential routes of exposure. Consumption of
> drinking water would appear to be inconsequential if water
> concentrations were equivalent to the concentrations from PRZM/EXAMS;
> however, concentrations in puddled water sources on treated fields may
> be higher than concentrations in modeled ponds. Preening and grooming
> exposures, involving the oral ingestion of material from the feathers
> or fur remains an unquantified, but potentially important, exposure
> route. Consequently; based on these results, mammals may be subject to
> developmental/reproductive effects and direct effects on foraging
> behavior when chronically exposed to MCPB as a result of the labeled
> use of the herbicide.
>
> Based on possible endocrine-related effects related to mammals (via
> reproductive effects) MRID 116345 and MRID 42883603, MCPB may be
> classified as a potential endocrine disruptor. EPA is required under
> the Federal Food, Drug, and Cosmetic Act (FFDCA), as amended by the
> Food Quality Protection Act (FQPA), to develop a screening program to
> determine whether certain substances (including all pesticide active
> and other ingredients) "*may have an effect in humans that is similar
> to an effect produced by a naturally occurring estrogen, or other such
> endocrine effects as the Administrator may designate.*" Following the
> recommendations of its Endocrine Disruptor Screening and Testing
> Advisory Committee (EDSTAC), EPA determined that there was a
> scientific basis for including, as part of the program, the androgen
> and thyroid hormone systems, in addition to the estrogen hormone
> system. EPA also adopted EDSTAC's recommendation that the Program
> include evaluations of potential effects in wildlife. For pesticide
> chemicals, EPA will use the Federal Insecticide, Fungicide, and
> Rodenticide Act (FIFRA) and, to the extent that effects in wildlife
> may help determine whether a substance may have an effect in humans,
> FFDCA authority to require the wildlife evaluations. As the science
> develops and resources allow, screening of additional hormone systems
> may be added to the Endocrine Disruptor Screening Program (EDSP). When
> the appropriate screening and/or testing protocols being considered
> under the Agency's EDSP have been developed, MCPB may be subjected to
> additional screening and/or testing to better characterize effects
> related to endocrine disruption.
>
> *Terrestrial Non-target Insects*
>
> EFED currently does not quantify risks to terrestrial non-target
> insects. Risk quotients are therefore not calculated for these
> organisms. MCPB was practically non-toxic to honey bees (LD~50~ of
> \>23 µg ae/bee) in an acute contact study, but potential exposure has
> not been quantified.
>
> *Terrestrial Plants in Dryland and Semi-aquatic Areas*
>
> An analysis of the results indicates exceedance of the Acute Risk LOC
> for non-endangered monocots and dicots located adjacent to treated
> areas, in semi-aquatic areas, and as a result of spray drift. (Table
> IV.g). The Endangered Species LOC was exceeded for monocots and dicots
> located in dryland and semi-aquatic areas adjacent to treated areas
> and for dicots as a result of spray drift. The potential risk to
> endangered terrestrial plants will be discussed in greater detail in
> Section IV.B.4.
>
> In spite of the uncertainty in the magnitude of the EC~25~ values used
> to calculate the RQs for MCPB, other data in the vegetative vigor
> studies indicate the potential for risk to non-target dicots from
> spray drift alone. Using the spray drift model AgDrift, the distances
> were calculated at which exposure would be equivalent to the lowest
> application rates tested in the vegetative vigor study which led to
> adverse effects. This Tier 1 AgDrift assessment assumed a fine to
> medium droplet size spectrum, and an aerial application. Table IV.h.
> shows these rates for each crop, the level of effect seen at that
> rate, and the distance at which that deposition would occur.

  -----------------------------------------------------------------------
  TABLE IV.h. -                                         
  Distance of                                           
  Deposition of                                         
  MCPB Equivalent                                       
  to Rates Tested                                       
  in Vegetative                                         
  Vigor Study                                           
  ----------------- ----------------- ----------------- -----------------
  Crop              Lowest Rate       \% Effect to      Distance of
                    Tested with       Shoot Weight at   Deposition at
                    Adverse Effect    that Rate         that Rate (ft)
                    (lb ae/acre)                        

  Cabbage           0.08              49                177

  Lettuce           0.039             26                361

  Soybean           0.17              53                85

  Tomato            0.08              43                177
  -----------------------------------------------------------------------

> Highly active herbicides, such as the growth regulators, present the
> greatest drift hazard because extremely small amounts can cause severe
> problems. Even if only a small surface area of the plant is exposed to
> MCPB, or a seedling is exposed to MCPB as it breaks through the soil
> surface, there is a possibility that the plant may be severely damaged
> or die as a result. In the vegetative vigor test, effects observed
> included mortality (one cucmber plant, two radish plants), leaf
> necrosis, decreased plant size, leaf curl, and stem tumors. Such
> damage, even if only minor, may be sufficient to prevent the plant
> from competing successfully with other plants for resources and water.
>
> Currently, the labels for the registered MCPB herbicides do not place
> restrictions on droplet size or wind speed during application. The
> exception is the state of Florida, which has promulgated a rule
> (Organo-Auxin Herbicide Rule) that stipulates that buffer zones up to
> a half-mile wide be observed when spraying phenoxy herbicides. The
> width of the required buffer zone is dependent on the wind speed and
> direction, and whether aerial or ground spray equipment is used. This
> has the potential to reduce the exposure susceptible non-target plants
> to spray drift. However, since the vegetative vigor tests could not
> determine a no-effect application rate for MCPB, the effectiveness of
> these buffers to eliminate risk to plants cannot be evaluated.
>
> Direct effects to plant species could result in indirect effects at
> the higher levels of organization (i.e. population, trophic level,
> community, ecosystem). In terrestrial and shallow-water aquatic
> communities, plants are the primary producers upon which the
> succeeding trophic levels depend. If the available plant material is
> impacted due to the effects of MCPB and MCPB sodium, this may have
> negative effects not only on the herbivores, but throughout the food
> chain. Also, depending on the severity of impacts to the plant
> communities (edge and riparian vegetation), community assemblages and
> ecosystem stability may be altered (i.e. reduced bird populations in
> edge habitats; reduced riparian vegetation resulting in increased
> light penetration and temperature in aquatic habitats). Furthermore,
> reduction of upstream riparian vegetation that would otherwise supply
> downstream habitats could result not only in a loss of a significant
> component of food for aquatic herbivores and detritivores, but also of
> habitat (i.e. leaf packs, materials for case-building for
> invertebrates). The assessment of risk to aquatic receptors will focus
> on freshwater systems and exclude saltwater/estuarine systems based on
> the regional use patterns of the herbicide. Field studies are not
> available to quantify actual risk to plant and animal communities in
> edge and riparian habitats; however, the potential for adverse effects
> may occur.

**3. Review of Incident Data:** FIFRA 6(a)(2) incident data add lines of
evidence to provide evidence that the risk predictions from the
screening level assessment are substantiated with actual effects in the
field. No aquatic or terrestrial incidents have been reported to the
Agency for MCPB as of March 1, 2005. The lack of reported incidents
cannot be considered as evidence of lack of hazard. Incident reporting
is a voluntary process. At the present time, the lack of mortality
incidents in the Ecological Incident Information System (EIIS) database
cannot be considered as evidence of a lack of hazard to aquatic and/or
terrestrial organisms.

**4. Federally Threatened and Endangered (Listed) Species Concerns**

> *Action Area*
>
> For listed species assessment purposes, the action area is considered
> to be the area affected directly or indirectly by the Federal action
> and not merely the immediate area involved in the action. At the
> initial screening-level, the risk assessment considers broadly
> described taxonomic groups and so conservatively assumes that listed
> species within those broad groups are collocated with the pesticide
> treatment area. This means that terrestrial plants and wildlife are
> assumed to be located on or adjacent to the treated site and aquatic
> organisms are assumed to be located in a surface water body adjacent
> to the treated site. The assessment also assumes that the listed
> species are located within an assumed area which has the relatively
> highest potential exposure to the pesticide, and that exposures are
> likely to decrease with distance from the treatment area. Section
> II.A.4. of this risk assessment presents the pesticide use sites that
> are used to establish initial collocation of species with treatment
> areas.
>
> If the assumptions associated with the screening-level action area
> result in RQs that are below the listed species LOCs, direct effects
> to listed species are not expected for that taxon. Furthermore, RQs
> below the listed species LOCs for a given taxonomic group indicate no
> concern for indirect effects upon listed species that depend upon the
> taxonomic group covered by the RQ as a resource. However, in
> situations where the screening assumptions lead to RQs in excess of
> the listed species LOCs for a given taxonomic group, a potential for a
> \"may affect\" conclusion exists and may be associated with direct
> effects on listed species belonging to that taxonomic group or may
> extend to indirect effects upon listed species that depend upon that
> taxonomic group as a resource. In addition, if no toxicity data are
> available on which to calculate RQs, then risk to listed species in a
> particular taxon cannot be dismissed.
>
> If it is not possible to come to a "not likely to adversely affect"
> conclusion, additional information on the biology of listed species,
> the locations of these species, and the locations of use sites could
> be considered along with available information on the fate and
> transport properties of the pesticide to determine the extent to which
> screening assumptions regarding an action area apply to a particular
> listed organism. These subsequent refinement steps could consider how
> this information would impact the action area for a particular listed
> organism and may potentially include areas of exposure that are
> downwind and downstream of the pesticide use site.
>
> *Taxonomic Groups Potentially at Risk*
>
> The preliminary risk assessment for endangered species indicates that
> MCPB exceeds the Endangered Species LOCs for the single application
> per year for peas with an application rate of 1.5 lbs ae/acre:

0.  freshwater vascular plants

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0.  small (20g), medium (100 g) and large birds (1000 g) feeding on
    short grass, tall grass, and broadleaf forage/small insects; small
    birds feeding on fruit, pods, seeds, and large insects

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0.  (15 and 35 g) mammals feeding on short grass; small mammals (15 g)
    feeding on broadleaf forage/small insects.

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0.  non-target terrestrial plants - monocots and dicots adjacent to
    treated areas and semi-aquatic.

> *Discussion of Risk Quotients*
>
> The Agency's LOC for listed freshwater vascular plants, birds,
> mammals, and non-target terrestrial plants is exceeded for the use of
> MCPB as outlined in previous sections. Should estimated exposure
> levels occur in proximity to listed resources, the available screening
> level information suggests a potential concern for direct effects on
> listed species within these taxonomic groups listed above associated
> with the use of MCPB as described in Section II.A.4. The registrant
> must provide information on the proximity of Federally listed
> freshwater vascular plants, small and large birds, small mammals, and
> non-target terrestrial plants to the MCPB use sites. This requirement
> may be satisfied in one of three ways: 1) having membership in the
> FIFRA Endangered Species Task Force (Pesticide Registration \[PR\]
> Notice 2000-2); 2) citing FIFRA Endangered Species Task Force data; or
> 3) independently producing these data, provided the information is of
> sufficient quality to meet FIFRA requirements. The information will be
> used by the OPP Endangered Species Protection Program to develop
> recommendations to avoid adverse effects to listed species.
>
> [Use of Probit Slope Response Relationship to Provide Information on
> the Endangered Species Levels of Concern]{.underline}
>
> The Agency uses the probit dose response relationship as a tool for
> providing additional information on the listed animal species acute
> levels of concern. The acute listed species LOCs of 0.1 and 0.05 are
> used for terrestrial and aquatic animals, respectively. As part of the
> risk characterization, an interpretation of acute LOCs for listed
> species is discussed. This interpretation is presented in terms of the
> chance of an individual event (i.e., mortality or immobilization)
> should exposure at the estimated environmental concentration actually
> occur for a species with sensitivity to difenoconazole on par with the
> acute toxicity endpoint selected for RQ calculation. To accomplish
> this interpretation, the Agency uses the slope of the dose response
> relationship available from the toxicity study used to establish the
> acute toxicity measurement endpoints for each taxonomic group. The
> individual effects probability associated with the LOCs is based on
> the mean estimate of the slope and an assumption of a probit dose
> response relationship. In addition to a single effects probability
> estimate based on the mean, upper and lower estimates of the effects
> probability are also provided to account for variance in the slope.
> The upper and lower bounds of the effects probability are based on
> available information on the 95% confidence interval of the slope. A
> statement regarding the confidence in the applicability of the assumed
> probit dose response relationship for predicting individual event
> probabilities is also included. Studies with good probit fit
> characteristics (i.e., statistically appropriate for the data set) are
> associated with a high degree of confidence. Conversely, a low degree
> of confidence is associated with data from studies that do not
> statistically support a probit dose response relationship. In
> addition, confidence in the data set may be reduced by high variance
> in the slope (i.e., large 95% confidence intervals), despite good
> probit fit characteristics.
>
> Individual effect probabilities are calculated based on an Excel
> spreadsheet tool IECV1.1 (Individual Effect Chance Model Version 1.1)
> developed by the U.S. EPA, OPP, Environmental Fate and Effects
> Division (June 22, 2004). The model allows for such calculations by
> entering the mean slope estimate (and the 95% confidence bounds of
> that estimate) as the slope parameter for the spreadsheet. In
> addition, the LOC (0.1 for terrestrial animals and 0.05 for aquatic
> animals) is entered as the desired threshold.

[Probit Slope Analysis]{.underline}

The probit slope response relationship is evaluated to calculate the
change of an individual event corresponding to the listed species acute
LOCs. If information is unavailable to estimate a slope for a particular
study, a default slope assumption of 4.5 is used as per original Agency
assumptions of typical slope cited in Urban and Cook (1986).

Freshwater Fish

The following calculations were calculated by the probit method.

Analysis of raw data from the rainbow trout LC~50~ 3.9 mg ae/L study
(MRID 42532608) estimate a slope of 9.39(95% C.I. 5.46- 13.33) Based on
this slope, and taking into account the RQs that occur for aquatic
species at 1.5 ae/A application rate for MCPB the individual mortality
associated with the maximum calculated RQ value (.01) results in an
estimated chance of individual mortality of 1 in 1.00E +16. RQ's
exceedences do not occur for freshwater fish species at MCPB application
1.5 ae/A. The corresponding estimated chance of individual mortality
associated with the listed species LOC of 0.05 is 1 in 1.00E +16.

Freshwater Invertebrates

Analysis of raw data from the daphnid acute LC~50~ 50.0study (MRID
42532602) estimates a slope of 9.22(95% C.I. 5.41- 13.03). Based on this
slope, and taking into account the RQs that occur for aquatic species
for MCPB at 1.5ae/A application rate the individual mortality associated
with the maximum calculated RQ values (.01) result in an estimated
chance of individual mortality of 1 in 1.00E +16. RQ's exceedences do
not occur for freshwater invertebrate species at 1.5 ae/A application
rate . The corresponding estimated chance of individual mortality
associated with the listed species LOC of 0.05 is 1 in 1.00E +16.

Estuarine and Marine Fish

No probit dose can be determined due to lack of submitted data.

Estuarine and Marine Invertebrates

No probit dose can be determined due to lack of submitted data.

Avian

Analysis of raw data from the bobwhite quail LD50 257 study (MRID
42560801) estimates a slope of 5.68 (95% C.I. 3.12 - 8.25). Based on
this slope, and taking into account the RQs that occur for avian
terrestrial species at MCPB application rate of 1.5ae/A, the individual
mortality associated with the maximum calculated RQ value ( 2.26) for a
20 gram bird eating short grass results is an estimated chance of
individual mortality of 1 in 1.02E +00 . RQ's exceedances do not occur
for avian species at all food type scenarios. The corresponding
estimated chance of individual mortality associated with the listed
species LOC of 0.1 is 1 in 1.48E +08.

Mammals

Raw data is not provided in the rat acute LD~50~ 832 ae mg /kg-bwt study
(MRID 116340) to calculate a slope. The default slope of 4.5 was used in
the probit analysis. Based on this slope, and taking into account the
RQs that occur for mammal terrestrial species at MCPB application rate
1.5ae/A , the individual mortality associated with the maximum RQ value
(15 gram mammal and 35 gram mammal), respectively eating short grass,
calculated RQ values (.17 and .15) result in an estimated chance of
individual mortality of 1 in 3.74E + 03 and 1 in 9.56E +03,
respectively. RQ's exceedences do not occur for mammal species at all
food type scenarios. The corresponding estimated chance of individual
mortality associated with the listed species LOC of 0.1 is 1 in 4.17E
+08**.**

> [Data Related to Under-represented Taxa:]{.underline} Additional
> effects data from other analyzed sources (ECOTOX Database) requires
> further evaluation for data related to under-represented taxa and
> support study data for MCPB.
>
> [Implications of Sublethal Effects:]{.underline} Chronic studies were
> not available for freshwater and estuarine marine aquatic species and
> for birds. RQs did exceed Chronic LOCs for mammals in all weight
> classes (15 g, 35 g, and 1000g) for consumption of short grass, tall
> grass and broadleaf forage/small insects and in 15 g and 35g mammals
> for consumption of fruit and large insects. Maternal toxicity observed
> in a rat developmental toxicity study (MRID 40865402) included
> decreased body weight and body weight gain during gestation and
> developmental toxicity observed in the same study included decreased
> mean body weights/litter, increases in unossified or poorly ossified
> sites, and skeletal variations. Maternal toxicity observed in a rabbit
> developmental toxicity study (MRID 40865401) included death, clinical
> signs of toxicity, decrease in body weight gain, and change in color
> of liver and kidneys. It should be noted that in acute bird guideline
> studies, discolorations on several organs, including white areas/film
> on the heart, liver, gizzard, gallbladder, crop and intestines were
> also observed. In addition, sublethal effects in subchronic feeding
> studies (13 weeks) with dogs included testicular and prostate atrophy
> and curtailment of spermatogenic activity (MRID 116345); reduced
> testes weights and physiological changes in clinical chemistry (MRID
> 42883603). The reproductive and developmental effects observed in
> these studies may lead to a potential concern for impacts to
> populations of mammals consuming feed items contaminated with MCPB and
> to the predators that feed on them.
>
> *Indirect Effects Analysis*
>
> Acute Risk and Acute Restricted Use LOCs were exceeded for birds (20,
> 100, and 1000 g) consuming the various feed items and results of the
> probit dose analysis for bobwhite quail indicated a 1 in 15 chance of
> mortality based on the maximum use scenario EEC. Consequently, there
> may be a concern for potential indirect effects to listed species
> dependent upon birds that consume feed items (short and tall grasses;
> broadleaf plants; small and/or large insects; and fruits, seeds, and
> pods) contaminated with MCPB residues; such as predatory birds and
> mammals.
>
> The Acute Risk LOCs for non-target monocots and dicots were exceeded
> for plants located adjacent to treated areas and in semi-aquatic
> areas. Exposure to MCPB results in direct effects to plant species
> that could result in indirect effects at the higher levels of
> organization (i.e. population, trophic level, community, ecosystem).
> The guideline terrestrial plant studies indicate direct adverse
> effects to seedling emergence as well as non-lethal effects including
> brown leaf tips in cabbage, corn, onion, ryegrass, radish, and
> soybean; necrosis in corn, radish, onion, and soybean; chlorosis in
> onion, cucumber, and lettuce; stem tumors in soybean and tomato; leaf
> curl in tomato, and decrease in size in cabbage, cucumber, lettuce,
> onion, and ryegrass. In the guideline aquatic vascular plant studies,
> concentrations as low as 0.16 mg ae/L resulted in chlorosis, curling,
> and decreased root formation in the plant. In terrestrial and
> shallow-water aquatic communities, plants are the primary producers
> upon which the succeeding trophic levels depend.
>
> If the available plant material is impacted due to the effects of
> MCPB, this may have negative effects not only on the herbivorous
> animals, but throughout the food chain. Also, depending on the
> severity of impacts to the plant communities (edge and riparian
> vegetation), community assemblages and ecosystem stability may be
> altered (i.e. reduced bird populations in edge habitats; reduced
> riparian vegetation resulting in increased light penetration and
> temperature in aquatic habitats). Furthermore, reduction of upstream
> riparian vegetation that would otherwise supply downstream habitats
> could result not only in a loss of a significant component of food for
> aquatic herbivores and detritivores, but also of habitat (i.e. leaf
> packs, materials for case-building for invertebrates). The assessment
> of risk to aquatic receptors both freshwater and saltwater/estuarine
> systems is also of potential concern.
>
> *Critical Habitat*
>
> In the evaluation of pesticide effects on designated critical habitat,
> consideration is given to the physical and biological features
> (constituent elements) of a critical habitat identified by the U.S
> Fish and Wildlife and National Marine Fisheries Services as essential
> to the conservation of a listed species and which may require special
> management considerations or protection. The evaluation of impacts for
> a screening level pesticide risk assessment focuses on the biological
> features that are constituent elements and is accomplished using the
> screening-level taxonomic analysis (risk quotients, RQs) and listed
> species levels of concern (LOCs) that are used to evaluate direct and
> indirect effects to listed organisms.
>
> The screening-level risk assessment has identified potential concerns
> for indirect effects on listed species for those organisms dependent
> upon birds, small mammals, aquatic vascular plants, and terrestrial
> and semi-aquatic plants. In light of the potential for indirect
> effects, the next step for EPA and the Service(s) is to identify which
> listed species and critical habitat are potentially implicated.
> Analytically, the identification of such species and critical habitat
> can occur in either of two ways. First, the agencies could determine
> whether the action area overlaps critical habitat or the occupied
> range of any listed species. If so, EPA would examine whether the
> pesticide\'s potential impacts on non-endangered species would affect
> the listed species indirectly or directly affect a constituent element
> of the critical habitat. Alternatively, the agencies could determine
> which listed species depend on biological resources, or have
> constituent elements that fall into, the taxa that may be directly or
> indirectly impacted by the pesticide. Then EPA would determine whether
> use of the pesticide overlaps the critical habitat or the occupied
> range of those listed species. At present, the information reviewed by
> EPA does not permit use of either analytical approach to make a
> definitive identification of species that are potentially impacted
> indirectly or critical habitats that is potentially impacted directly
> by the use of the pesticide. EPA and the Service(s) are working
> together to conduct the necessary analysis.
>
> This screening-level risk assessment for critical habitat provides a
> listing of potential biological features that, if they are constituent
> elements of one or more critical habitats, would be of potential
> concern. These correspond to the taxa identified above as being of
> potential concern for indirect effects and include the following:
> birds, small mammals, aquatic vascular plants, and terrestrial and
> semi-aquatic plants. This list should serve as an initial step in
> problem formulation for further assessment of critical habitat impacts
> outlined above, should additional work be necessary.
>
> *Co-occurrence Analysis*
>
> Because the Endangered Species LOCs for freshwater vascular plants and
> for terrestrial monocots and dicots are exceeded for the use of MCPB,
> the LOCATES was run for all taxonomic groups. Therefore, a potential
> concern exists with species that are obligates and have very specific
> habitats or feeding requirements. For terrestrial monocots and dicots,
> both the Acute Risk LOCs for non-endangered species and the Endangered
> Species LOCs were exceeded; consequently a potential concern arises
> for species with both narrow and general dependencies. In addition,
> Endangered Species LOCs were exceeded for small (20g) medium (100 g)
> and large birds (1000 g) feeding on short grass, tall grass, and
> broadleaf forage/small insects; small birds feeding on fruit and large
> insects; small (15 and 35 g) mammals feeding on short grass; and small
> mammals (15 g) feeding on broadleaf forage/small insects. Information
> from LOCATES, as presented in Table IV.i. below, indicates that
> several potentially affected species of birds, mammals and plants
> appear to be co-located with pesticide use areas. Results of the
> probit dose analysis for bobwhite quail indicated a 1 in 15 chance of
> mortality based on the maximum use scenario EEC. Consequently, there
> may be a concern for potential indirect effects to listed species
> dependent upon birds that consume feed items (short and tall grasses;
> broadleaf plants; small and/or large insects; and fruits, seeds, and
> pods) contaminated with MCPB residues; such as predatory birds and
> mammals. In addition, there may be a potential concern for indirect
> effects related to plants that require birds and/or mammals for
> pollination or seed dispersal and for animals that use burrows for
> shelter or breeding habitat. Results of this risk assessment indicate
> no direct risk to freshwater fish and invertebrates; however, these
> species may be dependent on aquatic plants for survival.

**Table IV .i. Tabulation by taxonomic group and crop of listed species
that occur in MCPB use areas** **summarized by Locates**

  ----------------------- ------------- --------- ---------- ------------ ------ ------------- ----------- --------- -------- ------- --------
                          **Taxonomic                                                                                                 
                          Group**                                                                                                     

                          Birds         Mammals   Reptiles   Amphibians   Fish   Crustaceans   Arachnids   Insects   Snails   Clams   Plants

  Peas (all varieties)    48            38        21         10           39     11            1           27        10       37      350

  Total States            39            36        12         5            22     5             1           14        5        20      37
  ----------------------- ------------- --------- ---------- ------------ ------ ------------- ----------- --------- -------- ------- --------

**C. Description of Assumptions, Limitations, Uncertainties, Strengths
and Data Gaps**

> *Uncertainties and assumptions related to selection of parent toxicity
> data and expsoure estimates related to MCPB the degradate MCPA.*

The risk assessment for aquatic organisms estimated exposure
concentrations on the basis of residual MCPB plus the degradate MCPA. If
both are assumed to be of equal toxic potency, no bias has been
introduced to the risk assessment by this assumption. However, A
comparison of MCPB toxicity data with the available toxicity for MCPA
published in the EPA RED chapter for that compound, indicates that some
differences in toxic potency may exist for the two compounds. Using
common aquatic species tested for each compound (acid equivalent) the
following comparisons can be made:

[Species]{.underline} [Test Type]{.underline} [MCPB Result]{.underline}
[MCPA Result]{.underline}

Rainbow trout 96-h LC50 3.9 mg ae/L 96 mg ae/L

Daphnid 48-h LC50 50 mg ae/L 82 mg ae/L

The aquatic organism comparisons would suggest that MCPA (acid
equivalent) is less toxic that the MCPB. Therefore, assuming equal
potency between the two compounds, and adding the exposures together
would likely overestimate risk for aquatic organisms. This finding,
however, does not alter the conclusions of the aquatic risk assessment,
which suggests no concern for acute effects in freshwater aquatic
organisms.

Chronic data for risks to freshwater fish, freshwater invertebrates,
estuarine marine fish and acute estuarine marine fish for MCPB were
calculated via acute to chronic ratios from MCPA data due to lack of
submitted data for MCPB.

There were no LOC exceedences for chronic risks to freshwater fish,
freshwater invertebrates, estuarine marine fish and acute estuarine
marine fish for MCPB based on values calculated from MCPA on a acute to
chronic ratio for both Oregon and California scenarios.

However, there is low confidence in these numbers due to interspecies
differences and toxicity differences between MCPB and MCPA for
freshwater fish and invertebrates. Higher uncertainty exists with
estuarine marine acute and chronic fish. Estuarine marine invertebrates
were calculated with acute to chronic ratio but with little confidence.
LOCs were exceeded for acute estuarine marine invertebrates (RQs 0.07 -
0.01) for acute restricted use and acute endangered species.

Therefore, acute estuarine marine fish and acute estuarine marine
invertebrates for MCPB are requested because no estuarine marine studies
were submitted for MCPB, low confidence in estuarine marine and
invertebrate calculations from acute to chronic ratios and the apparent
differences in endpoints for MCPA and MCPB. These endpoint differences
are as follows: MCPA is less toxic to acute freshwater fish (96 mg ae/L)
than MCPB (3.9 mg ae/L)

However, MCPB is more toxic to acute freshwater invertebrates (50 mg
ae/L) than MCPA (82 mg ae/L). Therefore, chronic studies for freshwater
fish and invertebrates will be requested due to endpoint differences and
low confidence in acute to chronic ratios as mentioned above. The
chronic studies for estuarine marine fish and estuarine invertebrates
are reserved based on the outcome of acute estuarine marine fish and
invertebrate submitted studies.

Input values and calculations on the acute to chronic ratios for MCPA
and MCPB are located in

Appendix J.

> Terrestrial wildlife exposures were conducted solely on the exposure
> for MCPB. MCPA was not included in the exposure assessment. A
> comparison of MCPB toxicity data with the available toxicity for MCPA
> published in the EPA RED chapter for that compound, indicates that
> some differences in toxic potency may exist for the two compounds.
> Using common terrestrial species tested for each compound (acid
> equivalent) the following comparisons can be made:
>
> [Species]{.underline} [Test Type]{.underline} [MCPB
> Result]{.underline} [MCPA Result]{.underline}
>
> Bobwhite LD50 257 mg ae/kg-bw 221-377 mg ae/kg-bw

Rat LD50 832 mg ae/kg-bw 1383 mg ae/kg-bw

> The comparison for bobwhite quail would suggest that the acute potency
> of MCPB lies within the range of toxicity for acid equivalent MCPA.
> Relying solely on MCPB, may underestimate the contribution of MCPA
> residues to overall toxic exposure. However, the fact that the
> exposure model incorporates a 35-day half-life assumption tends to
> offset this potential under estimation.
>
> EFED is aware that HED is considering both MCPB and MCPA exposure in
> its human health risk assessment and treating the two compounds as
> equally toxic. EFED, as per the approach with birds, has only
> considered the MCPB exposure. However, the selection of the long
> 35-day foliar half-life would suggest that any contribution of MCPA
> would be low. Consequently, EFED does not believe that the current
> mammalian wildlife risk assessment has any extensive bias in this
> regard.
>
> *Uncertainties, assumptions, and limitations associated with models*
>
> Extrapolating the risk conclusions from the standard pond scenario
> modeled by PRZM/EXAMS may either underestimate or overestimate the
> potential risks. Major uncertainties with the standard runoff scenario
> are associated with the physical construct of the watershed and
> representation of vulnerable aquatic environments for different
> geographic regions. The physicochemical properties (pH, redox
> conditions, etc.) of the standard farm pond are based on a Georgia
> farm pond. These properties are likely to be regionally specific
> because of local hydrogeological conditions. Any alteration in water
> quality parameters may impact the environmental behavior of the
> pesticide. The farm pond represents a well mixed, static water body.
> Because the farm pond is a static water body (no flow through), it
> does not account for pesticide removal through flow through or
> accidental water releases. However, the lack of water flow in the farm
> pond provides an environmental condition for accumulation of
> persistent pesticides. The assumption of uniform mixing does not
> account for stratification due to thermoclines (e.g., seasonal
> stratification in deep water bodies). Additionally, the physical
> construct of the standard runoff scenario assumes a watershed:pond
> area ratio of 10. This ratio is recommended to maintain a sustainable
> pond in the Southeastern United States. The use of higher
> watershed:pond ratios (as recommended for sustainable ponds in drier
> regions of the United States) may lead to higher pesticide
> concentrations when compared to the standard watershed:pond ratio.
>
> The standard pond scenario assumes that uniform environmental and
> management conditions exist over the standard 10 hectare watershed.
> Soils can vary substantially across even small areas, and thus, this
> variation is not reflected in the model simulations. Additionally, the
> impact of unique soil characteristics (e.g., fragipan) and soil
> management practices (e.g., tile drainage) are not considered in the
> standard runoff scenario. The assumption of uniform site and
> management conditions is not expected to represent some site-specific
> conditions. Extrapolating the risk conclusions from the standard pond
> scenario to other aquatic habitats (e.g., marshes, streams, creeks,
> and shallow rivers, intermittent aquatic areas) may either
> underestimate or overestimate the potential risks in those habitats.
>
> *Uncertainties and data gaps associated with the environmental fate
> and toxicity data*
>
> There are a number of areas of uncertainty in the terrestrial and the
> aquatic organism risk assessments that could potentially cause an
> underestimation of risk. First, this assessment accounts only for
> exposure of non-target organisms to MCPB, but not to its degradates.
> The risks presented in this assessment could be underestimated if
> degradates also exhibit toxicity under the conditions of use proposed
> on the label. Data are not available concerning the fate and toxicity
> of the photolytic degradation products of MCPB. MCPA is a degradation
> product of biodegradation in soil and this assessment provides
> available toxicity data for MCPA that indicates that the toxicity of
> MCPA acid is very similar to that of MCPB (Reregistration Eligibility
> Decision for MCPA, 2004). Second, the risk assessment only considers
> the most sensitive species tested and only considers a subset of
> possible use scenarios. For the aquatic organism risk assessment,
> there are uncertainties associated with the PRZM/EXAMS model, input
> values, and scenarios including the use of surrogate scenarios,
> however these uncertainties cannot be quantified. The potential
> impacts of these uncertainties are outlined in the Aquatic Exposure
> and Risk Assessment and the Terrestrial Exposure and Risk Assessment
> sections of this document.
>
> Additional uncertainty results from the lack of information and/or
> data in several components of this ecological risk assessment. First,
> MCPB chronic toxicity data for birds and aquatic organisms are not
> available, thus the potential risk due to prolonged exposures cannot
> be estimated. Second, data are unavailable concerning residue levels
> in foliage, flowers, and seeds to accurately predict potential risks
> to terrestrial organisms which may contact MCPB residues after
> application. Third, estuarine/marine fish and invertebrate data are
> not available. Finally, aerobic and anaerobic aquatic metabolism and
> terrestrial field dissipation studies have not been submitted for
> MCPB.

**APPENDIX A: Environmental Fate Studies** **and Selected Chemical
Structures**

**[MCPB (acid)]{.underline}**

![](media/image2.wmf){width="3.7583333333333333in"
height="1.320138888888889in"}

**[MCPB (sodium salt)]{.underline}**

![](media/image2.wmf){width="4.006944444444445in"
height="1.4166666666666667in"}

**[MCPA]{.underline}**

![](media/image2.wmf){width="3.042361111111111in"
height="1.2993055555555555in"}

**[CHPA (transient intermediate)]{.underline}**

![](media/image2.wmf){width="2.8805555555555555in"
height="1.5909722222222222in"}

**[CHPA-hexose conjugate]{.underline}**

![](media/image2.wmf){width="3.1416666666666666in"
height="2.946527777777778in"}

**Environmental Fate Studies**

**Hydrolysis**

Das, Y.T. 1992. Hydrolysis of \[^14^C\]MCPB in aqueous solutions
buffered at pH 5, 7 and 9. Unpublished study performed by Innovative
Scientific Services, Inc., Piscataway, NJ and sponsored by Rhône-Poulenc
Agrochemie, Lyon Cedex, France. ISSI Study Number 92010; Rhone-Poulenc
Study Number 92-06. Study was initiated on February 17, 1992 and
completed on September 23, 1992. MRID 42574301

The hydrolysis of \[phenyl-U^-14^C\]-labeled
(4-(2-methyl-4-chlorophenoxy)butyric acid (MCPB), at 10.3 mg a.i/L, was
studied in the dark at 25 ± 1°C in sterile aqueous 0.1 M buffer
solutions adjusted to pH 5 (acetate), pH 7 (phosphate) and pH 9 (borate)
for 30 days. The experiment was conducted in accordance with the US EPA
Pesticide Assessment Guidelines, Subdivision N, Section 161-1 and in
compliance with 40 CFR 160 (FIFRA Good Laboratory Practice Standards).
Samples were analyzed for MCPB and its transformation products without
extraction or concentration using HPLC. Identification was made by
comparison to unlabeled reference standards and confirmed by GC-MS.

Total radiocarbon recovery in the pH 5 solution averaged (n = 14) 99.8 ±
0.6% of the applied, in the pH 7 solution averaged 101.0 ± 0.4%, and in
the pH 9 solution averaged 102.1 ± 0.4%. The concentration of
\[^14^C\]MCPB decreased from 94.4% at day 0 to 91.5% of the applied at
study termination in the pH 5 solution, from 95.8% to 91.9% at pH 7, and
from 95.7% to 93.2% of the applied at pH 9. No major transformation
product was detected in any of the pH solutions. Five \[^14^C\]compounds
were isolated at maximum concentrations of 1.6-5.2% of the recovered;
one was tentatively identified as 4-(o-tolyloxy)butyric acid. Volatiles
were not measured. Half-life values were not calculated. Since \<5% of
the applied MCPB degraded during the 30 days, the slope of the
regression line was not significantly different from zero (a grossly
extrapolated half-life would be approximately 500 days).

**Photolysis**

Das, Y.T. 1992. Photodegradation of \[^14^C\]MCPB in aqueous solutions
buffered at pH 5, 7 and 9 under artificial sunlight. Unpublished study
performed by Innovative Scientific Services, Inc., Piscataway, NJ and
sponsored by Rhône-Poulenc Agrochemie, Lyon Cedex, France. ISSI Study
Number 92011; Rhone-Poulenc Study Number 92-07. Study was initiated on
February 17, 1992, and completed on September 23, 1992. MRID 42574302

The aqueous phototransformation of \[phenyl-U^-14^C\]-labeled
(4-(2-methyl-4-chlorophenoxy) butyric acid (MCPB) was studied at 25 ±
1°C in sterile aqueous acetate, phosphate and borate buffer solutions at
pH 5, 7 and 9, respectively at an initial concentration of 10.3 mg a.i/L
under irradiation using a filtered xenon arc lamp for 30 days (12 hours
light/12 hours dark). Test vessels were not connected to traps for the
collection of CO~2~ and organic volatiles in the definitive study.
Irradiated and dark control samples were sampled at 0, 1, 2, 3, 4, 7, 14
and 30 days; and 0, 1, 3, 7, 14, 21 and 30 days, respectively. Samples
were analyzed for MCPB and its transformation products without
extraction or concentration using HPLC. Identification was made by
comparison to unlabeled reference standards and confirmed by GC-MS.

[In the irradiated samples]{.underline}, total radiocarbon recovery
total radiocarbon recovery in the pH 5 solution averaged (n = 14) 96.9 ±
1.6%, in the pH 7 solution averaged 98.3 ± 1.5%, and in the pH 9
solution averaged 99.3 ± 1.6% of the applied amount at pH 5, 7 and 9,
respectively. The reviewer-calculated concentrations of \[^14^C\]MCPB
decreased from 94.4% at day 0 to 0.2% of the applied at day 30 in the pH
5 solution, from 95.9% to \<0.1% at pH 7, and from 95.7% to \<0.1% at pH
9. Five transformation products were isolated at \>10% of the applied: 4
-(4-hydroxy-[o]{.underline}-tolyloxy)butyric acid; 2,4-dihyroxyphenyl
formate; o-cresol; benzoic acid; and 2-hydroxyphenyl formate.
4-(4-Hydroxy-[o]{.underline}-tolyloxy)butyric acid was a mean maximum of
32.0% of the applied at 4 days and decreased to 4.8% by 30 days in the
pH 5 solution; was 27.5% at 7 days and decreased to 5.1% in the pH 7
solution; and was 17.4% at 30 days in pH 9 solution. 2,4-Dihyroxyphenyl
formate was a maximum mean concentration of 39.5% of the applied at 30
days in the pH 5 solution; was 33.0-35.3% at 14-30 days in the pH 7
solution; and was 22.8% at 30 days in the pH 9 solution. o-Cresol was a
maximum mean concentration of 17.1%, 47.3% and 25.7% of the applied at
30 days in pH 5, 7 and 9 solutions, respectively. Benzoic acid was at a
maximum mean concentration of 13.1% at 30 days inthe pH 5 solution, 1.6%
at 7 days in the pH 7 solution, and 7.2% at 30 days in the pH 9
solution. 2-Hydroxyphenyl formate was a maximum mean concentration of
10.0%, 4.7% and 14.0% of the applied at 14 days in pH 5, 7 and 9
solutions, respectively, and decreased in all solutions by 30 days.
There were two minor transformation products: 4-(o-tolyloxy)butyric acid
at a maximum mean 1.5-2.5% of the applied and 4-chloro-o-cresol (pH 5
and 9 only) at a maximum 3.6-5.1%. Volatiles were not measured. Eight
unidentified \[^14^C\]compounds, each a maximum of ≤8.8% of the applied,
totaled \<14.3% at all sampling intervals. Volatiles were not measured.

[In the nonirradiated samples]{.underline}, total radiocarbon recovery
in the pH 5 solution averaged (n = 14) 99.8 ± 0.6% of the applied, in
the pH 7 solution averaged 101.0 ± 0.4%, and in the pH 9 solution
averaged 102.1 ± 0.4%. The reviewer-calculated concentrations of
\[^14^C\]MCPB decreased from 94.4% at day 0 to 91.5% of the applied at
day 30 in the pH 5 solution, from 95.8% to 91.9% at pH 7, and from 95.7%
to 93.2% of the applied at pH 9. No major transformation product was
detected in any of the pH solutions. Fifteen \[^14^C\]compounds were
isolated, of which five were detected at maximum concentrations of
1.6-5.2% of the recovered. Volatiles were not measured.

The half-lives of MCPB in the irradiated pH 5, 7 and 9 buffer solutions
were calculated assuming pseudo first-order reaction kinetics.
Respective values were determined to be 2.2, 2.6 and 2.4 days,
respectively. There was no statistically significant difference between
the rate of degradation at different pHs. Since there was no degradation
in the dark control, the phototransformation half-lives do not need to
be adjusted for degradation in the controls. Likewise, since the
wavelengths and intensity of the light source were equivalent to
sunlight, no adjustments for light source are necessary.

*Transformation Products:* [In the irradiated samples]{.underline}, five
transformation products were isolated at \>10% of the applied: 4
-(4-hydroxy-[o]{.underline}-tolyloxy)butyric acid; 2,4-dihyroxyphenyl
formate; o-cresol; benzoic acid; and 2-hydroxyphenyl formate.
4-(4-Hydroxy-[o]{.underline}-tolyloxy)butyric acid was a mean maximum of
32.0% of the applied at 4 days and decreased to 4.8% by 30 days in the
pH 5 solution; was 27.5% at 7 days and decreased to 5.1% in the pH 7
solution; and was 17.4% at 30 days in pH 9 solution. 2,4-Dihyroxyphenyl
formate was a maximum mean concentration of 39.5% of the applied at 30
days in the pH 5 solution; was 33.0-35.3% at 14-30 days in the pH 7
solution; and was 22.8% at 30 days in the pH 9 solution. o-Cresol was a
maximum mean concentration of 17.1%, 47.3% and 25.7% of the applied at
30 days in pH 5, 7 and 9 solutions, respectively. Benzoic acid was at a
maximum mean concentration of 13.1% at 30 days in the pH 5 solution,
1.6% at 7 days in the pH 7 solution, and 7.2% at 30 days in the pH 9
solution. 2-Hydroxyphenyl formate was a maximum mean concentration of
10.0%, 4.7% and 14.0% of the applied at 14 days in pH 5, 7 and 9
solutions, respectively, and decreased in all solutions by 30 days.
There were two minor transformation products: 4-(o-tolyloxy)butyric acid
at a maximum mean 1.5-2.5% of the applied and 4-chloro-o-cresol (pH 5
and 9 only) at a maximum 3.6-5.1%. Volatiles were not measured. Eight
unidentified \[^14^C\]compounds, each a maximum of ≤8.8% of the applied,
totaled \<14.3% at all sampling intervals. Volatiles were not measured.

In the non-irradiated samples, no major transformation product was
detected in any of the pH solutions. Fifteen \[^14^C\]compounds were
isolated, of which five were detected at maximum concentrations of
1.6-5.2% of the recovered. Volatiles were not measured.

*Pathway:* It was proposed that at all pHs, MCPB was dechlorinated then
hydroxylated, resulting in the formation of
4-(4-hydroxy-o-tolyloxy)butyric acid (p. 33, Figure 80, p. 138, MRID
42574302).

*Aqueous Photolysis Summary*

Half-lives for irradiated samples: 2.2 days (pH 5), 2.6 days (pH 7) and
2.4 days (pH 9)

Major identified transformation products:
4-(4-hydroxy-[o]{.underline}-tolyloxy)butyric acid, 2,4-dihyroxyphenyl
formate, [o]{.underline}-cresol, benzoic acid and 2-hydroxyphenyl
formate.

Minor identified transformation products: 4-(o-tolyloxy)butyric acid and
4-chloro-o-cresol.

**Adsorption/Desorption in Soil**

Robson, M.M. 1993. Determination of adsorption/desorption
characteristics of 4-(2-methyl, 4-chlorophenoxy)butyric acid (MCPB) in
soil. Unpublished study performed by Hazleton UK, North Yorkshire,
England. HUK Study No. 68/127. Study sponsored by Rhône-Poulenc
Agriculture, Essex, England. Study initiated April 3, 1992 and completed
February 10, 1993. MRID 42693701

The adsorption/desorption characteristics of phenyl ring-labeled
\[^14^C\]MCPB (4-(2-methyl-4-chlorophenoxy) butyric acid dissolved in
methanol was studied in sterile sandy clay loam soil \[pH- 6.09, organic
carbon - 1.3%\] from France, and the following three soils and one
sediment from England: sand soil \[pH - 7.93, organic carbon - 0.53%\],
sandy loam soil \[pH - 6.08, organic carbon - 0.76%\], clay loam soil
\[pH - 7.6, organic carbon - 2.49%\], and sandy loam aquatic sediment
\[pH - 5.95, organic carbon - 2.85%\] in a batch equilibrium experiment.
The soils and sediment were sterilized using gamma irradiation (25 kGy).
The adsorption phase of the study was carried out by equilibrating
sterilized soil with \[^14^C\]MCPB at nominal concentrations of 0.04,
0.2, 1.0, and 5.0 µg/mL at ambient temperature (19-23°C) for 48 hours;
lighting conditions were not reported. The equilibrating solution used
was 0.01 M CaCl~2~, with soil/solution ratios of 1:5 (w:v) for the four
soils and one sediment. The desorption phase of the study was carried
out by replacing the adsorption solution with an equivalent volume of
sterilized, pesticide-free 0.01 M CaCl~2~ solution and equilibrating
once for 48 hours at 19-23°C. The desorption phase was conducted once.

After 48 hours of equilibration, 0.33-13.99, 0.05-11.20, 0.09-11.99,
0.13-11.11, and 0.69-76.33 µg/g of the applied \[^14^C\]MCPB was
adsorbed to the sandy clay loam, sand, sandy loam, and clay loam soils
and sediment, respectively. The mean adsorption K~ads~ values were 1.69,
0.26, 0.65, 0.78, and 10.58 mL/g for the sandy clay loam, sand, sandy
loam, and clay loam soils and sandy loam sediment, respectively.
Adsorption K~oc~ values were 129.57, 47.91, 85.54, 31.27, and 371.17
mL/g for the sandy clay loam, sand, sandy loam, and clay loam soils and
sandy loam sediment, respectively. At the end of the desorption, 64.0%,
32.18%, 60.22%, 60.59%, and 24.63% of the adsorbed amount was desorbed
in the sandy clay loam, sandy, sandy loam, and clay loam soils and sandy
loam sediment, respectively. The desorption K~oc~ and K~d~ values were
not provided.

**Anaerobic Biotransformation in Soil**

Goodyear, A. 1993. (^14^C)-MCPB: anaerobic soil metabolism. Unpublished
study performed by Hazleton UK, North Yorkshire, England, and sponsored
by MCPB Task Force, c/o Rhône-Poulenc Agricultural Limited, Essex,
England. Laboratory Study No. 68/131 and Report No. 68/131-1015. MRID
43015501

The biotransformation of \[phenyl-U^-14^C\]-labeled
(4-(2-methyl-4-chlorophenoxy)butyric acid (MCPB) was studied in sandy
loam soil (pH in water 7.7, organic carbon 0.3%) incubated for 62 days
under anaerobic conditions (flooding plus nitrogen atmosphere) in
darkness at 25 ± 1°C following 4 days of aerobic incubation.
\[^14^C\]MCPB was applied at a nominal rate of 3.4 mg a.i./kg soil
(equivalent to 3.8 kg a.i./ha). Soil samples were analysed after 0 and 4
days of aerobic incubation and after 8, 14, 29 and 62 days of anaerobic
incubation (12, 18, 33 and 66 days posttreatment).

Overall material balance averaged 99.6 ± 5.9% (range 91.1-110.3%, n = 2)
of the applied radioactivity, with material balances declining from
109.6 ± 0.7% at day 0 to 91.7 ± 0.6% (91.1-92.3%) after 29 days of
anaerobic incubation (33 days posttreatment), then increasing to 96.2 ±
0.5% after 62 days (66 days posttreatment, final sampling interval).
Distribution ratios for \[^14^C\]residues between the soil and water
layer were 5:1 after 8 days of anaerobic incubation, 10:1 after 29 days
and 7:1 after 62 days (Attachment 2).

In the sandy loam soil:water systems, \[^14^C\]MCPB decreased from an
average 40.9 ± 2.6% of the applied at 4 days posttreatment just prior to
flooding to 17.7 ± 1.8% after 14 days of anaerobic incubation (18 days
posttreatment) and 7.8 ± 0.1% after 29 days (33 days posttreatment),
then increased to 22.5 ± 4.9% after 62 days (66 days posttreatment).
\[^14^C\]MCPB in the soil decreased from 106.3 ± 0.0% of the applied at
day 0 to 40.9 ± 2.6% at 4 days just prior to flooding, 17.0 ± 2.3% after
8 days of anaerobic incubation, 3.0 ± 0.7% after 29 days, then increased
to 14.2 ± 1.5% after 62 days. \[^14^C\]MCPB in the water decreased from
11.9 ± 5.0% of the applied after 8 days of anaerobic incubation (12 days
post.) to 4.7 ± 0.7% after 29 days, then increased to 8.3 ± 3.4% after
62 days.

The major transformation product of \[^14^C\]MCPB was
(4-chloro-2-methylphenoxy)acetic acid (MCPA) detected at maximums of
34.8% in the soil at 4 days just prior to flooding, 33.4% in the water
after 14 days of anaerobic incubation, and 46.9% in the total soil:water
system after 29 days. After 62 days of anaerobic incubation,
\[^14^C\]MCPA was 6.6 ± 2.1% of the applied in the soil, 27.8 ± 4.8% in
the water and 34.3 ± 2.7% in the entire soil:water system.

*Half-life:* Half-life values of \[phenyl-U-^14^C\]MCPB in the total
soil:water system were determined by the registrant using linear
regression analysis and the Timme-Freshe square-root of first order
decay model of the mean \[^14^C\]MCPB recovered at the 8-, 14- and
33-day anaerobic intervals (12- to 33-day posttreatment intervals; pp.
25, 28, 31, see Reviewer's Comment no. 1). Half-life values of
\[^14^C\]MCPB in the water, soil and entire system were determined by
the Dynamac reviewer using least squares linear regression analysis,
based on first-order kinetics, of \[^14^C\]MCPB recovered in each sample
as calculated by Corel Quattro Pro 8 software (Attachment 2).

Table 7: Half-life (t~1/2~) values of MCPB in sandy loam soil under 62
days of anaerobic conditions following 4 days of aerobic incubation.

+------------------------------+--------+-------------+-------+------+
| **Regression Equation**      | **Sy   | **Intervals | *     |      |
|                              | stem** | used**      | *half |      |
|                              |        |             | -life |      |
|                              |        | **(days     | (da   |      |
|                              |        | postt       | ys)** |      |
|                              |        | reatment)** |       |      |
+==============================+========+=============+=======+======+
|                              |        |             | **t~1 | **r^ |
|                              |        |             | /2~** | 2^** |
+------------------------------+--------+-------------+-------+------+
| **First Order** - linear     | water  | 12-33       | 18.9  | 0    |
| least squares regression.    |        |             |       | .520 |
|                              |        |             |       |      |
| Linear form y = mx + b as    |        |             |       |      |
| lnC= ‑kt + lnC~0~; lnC~0~ is |        |             |       |      |
| initial concentration (b = y |        |             |       |      |
| intercept), lnC is           |        |             |       |      |
| concentration at time t (y), |        |             |       |      |
| k is the slope (m), t is     |        |             |       |      |
| time (x) or kt = lnC~0~ ‑    |        |             |       |      |
| lnC.                         |        |             |       |      |
|                              |        |             |       |      |
| Half-life (t ½) = -(ln 2/k). |        |             |       |      |
+------------------------------+--------+-------------+-------+------+
|                              | soil   | 4-33        | 7.8   | 0    |
|                              |        |             |       | .975 |
+------------------------------+--------+-------------+-------+------+
|                              | entire | 4-33        | 11.9  | 0    |
|                              | system |             |       | .946 |
+------------------------------+--------+-------------+-------+------+
|                              | entire | 12-33       | 11.4  | 0    |
|                              | system |             |       | .996 |
+------------------------------+--------+-------------+-------+------+
| **Timme-Freshe** - computer  | entire | 12-33       | 9.5   | not  |
| model fits data to 1^st^,    | system |             |       | repo |
| 1.5 and 2^nd^ order decay    |        |             |       | rted |
| curves; a square-root of the |        |             |       |      |
| 1^st^ order decline curve    |        |             |       |      |
| was utilized.                |        |             |       |      |
+------------------------------+--------+-------------+-------+------+

*Transformation Products:* The major transformation product of
\[^14^C\]MCPB was (4-chloro-2-methylphenoxy)acetic acid (MCPA) detected
at maximums of 34.8% in the soil at 4 days just prior to flooding, 33.4%
in the water after 14 days of anaerobic incubation, and 46.9% in the
total soil:water system after 29 days (pp. 41-43). After 62 days of
anaerobic incubation, \[^14^C\]MCPA was 6.6 ± 2.1% (4.5-8.6%) of the
applied in the soil, 27.8 ± 4.8% (23.0-32.6%) in the water, and 34.3 ±
2.7% (31.6-37.0%) in the entire system.

**Aerobic Soil Biotransformation**

John, A., *et al*. 1994. MCPB: aerobic soil metabolism. Unpublished
study performed and sponsored by MCPB Task Force, c/o Rhône-Poulenc
Agricultural Limited, Essex, England. Laboratory Project and Study ID: P
93/194. MRID 43247601

The biotransformation of \[phenyl-U^-14^C\]-labeled
(4-(2-methyl-4-chlorophenoxy)butyric acid (MCPB) was studied in sandy
loam soil (pH in water 5.38, organic carbon 2.3%) from the United
Kingdom for 120 days under aerobic conditions in darkness at 22 ± 1°C
and soil moisture of 75% of 1/3 bar. \[^14^C\]MCPB was applied at a
nominal rate of 3.4 mg a.i./kg soil (equivalent to 3.8 kg a.i./ha). The
test system consisted of flasks (not described) containing treated soil
attached in series to a flow-through apparatus with traps for the
collection of CO~2~ and volatile organics. Soil samples were analysed
after 0, 1, 3, 8, 15, 21, 29, 65, 90 and 120 days of incubation.

The major transformation product of \[^14^C\]MCPB was volatilized
^14^CO~2~ which increased to a maximum 64.9 ± 0.6% of the applied at 65
days and was 54.5-61.8% at 90-120 days; no organic volatiles were
detected. Two minor transformation products identified in soil extracts
were the hexose conjugate of
(4-chloro-2-methylphenoxy)-2-β-glucopyranoside acetic acid minor (CHPA)
and (4-chloro-2-methylphenoxy)acetic acid (MCPA), which were each
detected at maximums of 9.5% (8 days) and 7.2% (15 days) of the applied
radioactivity, respectively, with both decreasing to ≤2.1% by 120 days.
Five unidentified \[^14^C\]compounds (Metabolites 3-7) were each ≤5.3%
of the applied at any sampling interval. Extractable \[^14^C\]residues
decreased from 99.7 ± 1.9% of the applied at day 0 to 4.9-5.8% at 65-120
days. Non-extractable residues increased from 1.0% at day 0 to 41.5 ±
1.3% at 29 days, then gradually decreased to 30.9 ± 0.2% at 120 days. In
8- and 120-day extracted soil, 6.2-9.5%, 9.9-13.8%, and 7.7-10% of the
applied was associated with the fulvic acid, humic acid, and humin
fractions, respectively.

Soil type: United Kingdom (Essex) sandy loam.

First-order half-life for parent MCPB\*: 18 days (data from 0-120 days)

Combined first-order half-life for MCPB, MCPA, and CHPA-hexose
conjugate: 26 days (data from 0-120 days)

\*Note: There was an error in the calculation of half-life of MCPB in
the original Data Evaluation Report (DER). In the original DER the
half-life for the 120-day period was incorrectly calculated to be
approximately 27 days.

Major transformation product: CO~2~.

Minor transformation products:

(4-Chloro-2-methylphenoxy)acetic acid (MCPA)

(4-chloro-2-methylphenoxy)-2-β-glucopyranoside acetic acid (CHPA, as
hexose conjugate)

Five unidentified \[^14^C\]compounds.

A biotransformation pathway for the degradation of MCPB in aerobic soil
was proposed by the registrant (p. 42). The putative path was MCPB
degradation to (4-chloro-2-methylphenoxy)acetic acid (MCPA), which
degrades to (4-chloro-2-methylphenoxy)-2-β-glucopyranoside acetic acid
minor (CHPA) and conjugates with hexose. There was significant
production of CO~2~ and soil bound residues.

**Soil Leaching**

John, A.E., M.K. Jones and P. Lowden. 1994. MCPB: Fresh and aged
leaching study in five soils. Laboratory Project ID. P 92/333.
Unpublished study performed and submitted by Rhône-Poulenc Agriculture
Limited, Essex, England. Laboratory Project ID: P 92/333. MRID 43466401

This column leaching study was previously considered supplemental
because the CEC of the test soils and sediment was not reported, and,
for the aging portion of the study, degradates were not identified after
aging and prior to leaching. In the course of the current fate
assessment, we again evaluated the results of this study for possible
utility in characterization of mobility. We noted that missing from the
report was the concentration of MCPB, if any, in any of the leachates.
Therefore, although ostensible K~d~ values were reported in the study,
it is unclear what these values and their method of computation
represent or whether these reasonably approximate equilibrium values.
Therefore, the reported K~d~ values are presently of indeterminate
value. However, since the Agency does not rely on column leaching
studies for quantitative exposure assessments, and since we do have an
acceptable batch equilibrium study (see adsorption-desorption study
above, MRID 42693701), which is the preferred method for quantitative
modeling purposes, results from the column leaching study are not needed
for MCPB. Therefore, if the registrant so chooses, no further work is
required for this study.

**APPENDIX B: Aquatic Exposure Model Results**

***Aquatic Exposure Modeling***

PRZM 3.12 and EXAMS 2.98 models in tandem

Aquatic exposure concentrations for MCPB in the standard field pond were
estimated

using the PRZM 3.12 and EXAMS 2.98 models in tandem. PRZM/EXAMS is a
Tier II screening model designed to estimate pesticide concentrations
found in water at the edge of a treated field. As such, it provides
high-end values of the pesticide concentrations that might be found in
ecologically sensitive environments following pesticide application.

PRZM/EXAMS is a multi-year runoff model that also accounts for spray
drift from single and multiple applications. In the ecological exposure
assessment, PRZM/EXAMS simulates a 10 hectare (ha) field immediately
adjacent to a 1 ha pond, 2 meters deep with no outlet. The geographic
location of the field is specific to the crop being simulated using site
specific information on the soils, weather, cropping, and management
factors associated with the scenario. The crop/location scenario is
intended to represent a high-end vulnerable site on which the crop is
normally grown. Based on historical rainfall patterns, the pond receives
multiple runoff events during the years simulated.

Acute risk assessments are performed using 1 in 10 year peak EEC values
for single applications of MCPB. Chronic risk assessments for aquatic
invertebrates and fish are performed using the average 21-day and 60-day
EECs, respectively.

Table B.1. presents the input parameters used in the Tier II PRZM/EXAMS
modeling for ecological assessment of MCPB for surface water sources. To
simulate field application of MCPB to peas, two scenarios were selected
representing different MCPB usage areas based on geography and weather.
A California lettuce and an Oregon snap bean scenario were chosen as
representative of the agricultural practices and areas in which peas are
grown. The EECs for the two scenarios are presented in Table B.2. The
Oregon scenario represents the typical use of MCPB application to peas,
and the California scenario represents a reasonable upper bound
estimate. Results for the two cases are similar. We also investigated
several other possible scenarios (approximately six others), and found
all EECs to be rather tightly grouped in a range from approximately 15
to 40 μg ae/L. The PRZM/EXAMS input and output files from the California
and Oregon aquatic ecological exposure assessments for aerial and ground
applications are presented in Tables B.3., B.4.,B.5. and B.6.

+----------------------+--------------+---------------+---------------+
| TABLE B.1.           |              |               |               |
| PRZM/EXAMS Input     |              |               |               |
| Parameters for MCPB. |              |               |               |
+======================+==============+===============+===============+
| **Model Parameter**  | **Value**    | **Comments**  | **Source**    |
+----------------------+--------------+---------------+---------------+
| Application Rate per | 1.68 kg      | application   | Label         |
| Event                | ae/acre      | to peas by    |               |
|                      |              | ground and    |               |
|                      | (1.5 lbs     | aerial spray  |               |
|                      | ae/acre)     | application   |               |
+----------------------+--------------+---------------+---------------+
| Number of            | 1            |               | Label         |
| Applications per     | application  |               |               |
| Crop Season          | per year;    |               |               |
|                      | assumes one  |               |               |
|                      | planting     |               |               |
|                      | season per   |               |               |
|                      | year         |               |               |
+----------------------+--------------+---------------+---------------+
| Spray Application    | 0.99         |               | EFED          |
| Efficiencies         |              |               | Guidance,     |
|                      | 0.95         |               | 2002          |
| > ground             |              |               |               |
| >                    |              |               |               |
| > aerial             |              |               |               |
+----------------------+--------------+---------------+---------------+
| Spray Drift Fraction | 0.01         |               | EFED          |
|                      |              |               | Guidance,     |
| > ground             | 0.05         |               | 2002          |
| >                    |              |               |               |
| > aerial             |              |               |               |
+----------------------+--------------+---------------+---------------+
| Aerobic Soil         | 78 days ^1^  | estimated     | MRID 43247601 |
| Metabolism           |              | upper 90 ^th^ |               |
|                      |              | percentile    |               |
| t ~½~                |              |               |               |
+----------------------+--------------+---------------+---------------+
| Anaerobic Soil       | 34 days ^2^  | estimated     | MRID 43015501 |
| Metabolism           |              | upper 90 ^th^ |               |
|                      |              | percentile    |               |
| t ~½~                |              |               |               |
+----------------------+--------------+---------------+---------------+
| Aerobic Aquatic      | 156 days ^3^ | estimated     | EFED          |
| Degradation          |              |               | Guidance,     |
|                      |              | (2x aerobic   | 2002          |
| t ~½~                |              | soil          |               |
|                      |              |               |               |
|                      |              | metabolism    |               |
|                      |              | half-life)    |               |
+----------------------+--------------+---------------+---------------+
| Anaerobic Aquatic    | 68 days ^4^  | estimated     | EFED          |
| Degradation          |              |               | Guidance,     |
|                      |              | (2x anaerobic | 2002          |
| t ~½~                |              | soil          |               |
|                      |              |               |               |
|                      |              | metabolism    |               |
|                      |              | half-life)    |               |
+----------------------+--------------+---------------+---------------+
| Aqueous Photolysis t | 2.6 days     | pH 7          | MRID 42574302 |
| ~½~                  |              |               |               |
+----------------------+--------------+---------------+---------------+
| Hydrolysis t ~½~     | stable       |               | MRID 42574301 |
+----------------------+--------------+---------------+---------------+
| Kd/Koc               | 0.85 mL/g    | Average Kd    | MRID 42693701 |
|                      | ^5^          |               |               |
+----------------------+--------------+---------------+---------------+
| Molecular Weight     | 228.6        |               | Chemical      |
|                      |              |               | Formula       |
+----------------------+--------------+---------------+---------------+
| Water Solubility     | 600 mg/L     | 10 x          | Product       |
|                      |              | solubility    | Chemistry     |
+----------------------+--------------+---------------+---------------+
| Vapor Pressure       | 4.0E-7 torr  |               | Product       |
|                      |              |               | Chemistry     |
+----------------------+--------------+---------------+---------------+
| Henry's Law Constant | 3.42 x       |               | (Howard and   |
|                      | 10^-9^       |               | Meylan, 1997) |
| (estimated at 25°C)  | atm-m^3^/mol |               |               |
+----------------------+--------------+---------------+---------------+

^1^ Upper 90^th^ Percentile based on three times the single value for
the combined/total aerobic soil metabolism half life of 26 days for
MCPB, MCPA, and CHPA/CHPA hexose conjugate.

^2^ Upper 90^th^ Percentile based on three times the single anaerobic
soil metabolism half life of 11.4 days.

^3^ 2x aerobic soil metabolism half-life (EFED Modeling Input Parameter
Guidance, 2002).

^4^ 2x anaerobic soil metabolism half-life (EFED Modeling Input
Parameter Guidance, 2002).

^5^ From adsorption/desorption data including Kd values of 1.69, 0.26,
0.65, and 0.78 mL/g from MRID 42693701.

+-----------------+-------------+---------------+---------+----------+
| **TABLE B.2.    |             |               |         |          |
| Estimated       |             |               |         |          |
| Environmental   |             |               |         |          |
| Concentrations  |             |               |         |          |
| (μg ae/L) of    |             |               |         |          |
| MCPB +          |             |               |         |          |
| Metabolites     |             |               |         |          |
| (MCPA and       |             |               |         |          |
| CH              |             |               |         |          |
| PA/CHPA-hexose) |             |               |         |          |
| in Surface      |             |               |         |          |
| Water           |             |               |         |          |
| (PRZM-EXAMS)    |             |               |         |          |
| from All Uses   |             |               |         |          |
| for Ecological  |             |               |         |          |
| Assessment.**   |             |               |         |          |
+=================+=============+===============+=========+==========+
| **Simulation    |             | **            |         |          |
| Scenario**      |             | Concentration |         |          |
|                 |             | (μg ae/L)**   |         |          |
+-----------------+-------------+---------------+---------+----------+
| **Crop and      | **          | **1 in 10     | **21    | **60 Day |
| Location**      | Application | year Peak**   | Day     | Max.**   |
|                 | rate**      |               | Max.**  |          |
+-----------------+-------------+---------------+---------+----------+
| Lettuce (CA)    | 1.5 lbs     | 40.4          | 39.0    | 36.4     |
|                 | ae/acre     |               |         |          |
| (Surrogate for  |             | 43.2          | 41.7    | 38.9     |
| Peas)           | (1.68 kg    |               |         |          |
|                 | ae/ha)      |               |         |          |
|                 |             |               |         |          |
|                 | ground      |               |         |          |
|                 | spray       |               |         |          |
|                 |             |               |         |          |
|                 | aerial      |               |         |          |
|                 | spray       |               |         |          |
+-----------------+-------------+---------------+---------+----------+
| Snap Beans (OR) | 1.5 lbs     | 29.5          | 29.0    | 28.1     |
|                 | ae/acre     |               |         |          |
| (Surrogate for  |             | 33.1          | 32.5    | 31.5     |
| Peas)           | (1.68 kg    |               |         |          |
|                 | ae/ha)      |               |         |          |
|                 |             |               |         |          |
|                 | ground      |               |         |          |
|                 | spray       |               |         |          |
|                 |             |               |         |          |
|                 | aerial      |               |         |          |
|                 | spray       |               |         |          |
+-----------------+-------------+---------------+---------+----------+

The following surrogate scenarios are among those available in
PRZM/EXAMS to simulate peas grown in different regions of the US:
California lettuce scenario represents a reasonable upper bound estimate
for areas in which peasare or may be grown. Oregon snap bean scenario
represents a typical use scenario for areas in which peas are grown.

**TABLE B.3. Prism/Exams Output California Lettuce Scenario Aerial
Application**

  ---------------------------- ---------------------------- ---------- -------------- ----------- ------------ ----------
  stored as MCPBCAa1.out                                                                                       

  Chemical:                                                                                                    
  MCPB_CA_lettuce_NEW_aerial                                                                                   

  PRZM environment:            modified Monday, 11 October                                                     
  CAlettuceC.txt               2004 at 16:23:40                                                                

  EXAMS environment:           modified Thuday, 29 August                                                      
  pond298.exv                  2002 at 16:33:30                                                                

  Metfile: w23273.dvf          modified Wedday, 3 July 2002                                                    
                               at 09:04:22                                                                     

  Water segment concentrations                                                                                 
  (ppb)                                                                                                        

                                                                                                               

  Year                         Peak                         96 hr      21 Day         60 Day      90 Day       Yearly

  1961                         4.2                          4.154      4.051          3.799       3.598        2.235

  1962                         7.448                        7.396      7.179          6.72        6.385        4.147

  1963                         24.08                        23.9       23.18          22.21       21.21        12.61

  1964                         15.23                        15.12      14.82          14.03       13.37        9.328

  1965                         8.774                        8.711      8.525          8.26        7.947        5.532

  1966                         6.675                        6.625      6.416          5.967       5.65         3.851

  1967                         9.819                        9.748      9.562          9.12        8.687        5.602

  1968                         13.05                        12.94      12.55          11.75       11.11        6.992

  1969                         10.97                        10.88      10.52          9.773       9.254        6.351

  1970                         29.48                        29.23      28.21          26.09       24.69        14.91

  1971                         11.81                        11.73      11.37          10.77       10.42        8.076

  1972                         7.908                        7.846      7.591          7.05        6.668        4.785

  1973                         11.5                         11.45      11.11          10.35       9.881        6.413

  1974                         45.33                        45.09      44.28          41.48       39.31        23.36

  1975                         25.37                        25.19      24.46          22.86       21.7         14.91

  1976                         16.15                        16.03      15.51          14.69       14.09        9.64

  1977                         20.08                        19.92      19.27          18.11       17.72        11.5

  1978                         30.72                        30.48      29.77          27.78       26.28        16.12

  1979                         12.8                         12.74      12.38          11.89       11.47        8.159

  1980                         11.46                        11.37      11.05          10.29       9.765        6.318

  Year                         Peak                         96 hr      21 Day         60 Day      90 Day       Yearly

  1981                         47.84                        47.48      46.21          43.17       40.99        23.96

  1982                         17.61                        17.49      17.07          16.2        15.56        11.28

  1983                         23.98                        23.83      23.12          21.61       20.49        12.42

  1984                         10.05                        9.973      9.658          9.242       8.776        5.989

  1985                         7.51                         7.455      7.232          6.807       6.468        4.185

  1986                         18.29                        18.17      17.72          16.68       15.83        9.474

  1987                         44.61                        44.39      43.06          40.08       37.91        22.61

  1988                         19.15                        19.01      18.5           17.25       16.29        12.38

  1989                         10.12                        10.07      9.77           9.091       8.599        6.005

  1990                         6.794                        6.744      6.54           6.095       5.776        3.858

                                                                                                               

  Sorted results                                                                                               

  Prob.                        Peak                         96 hr      21 Day         60 Day      90 Day       Yearly

  0.032258065                  47.84                        47.48      46.21          43.17       40.99        23.96

  0.064516129                  45.33                        45.09      44.28          41.48       39.31        23.36

  0.096774194                  44.61                        44.39      43.06          40.08       37.91        22.61

  0.129032258                  30.72                        30.48      29.77          27.78       26.28        16.12

  0.161290323                  29.48                        29.23      28.21          26.09       24.69        14.91

  0.193548387                  25.37                        25.19      24.46          22.86       21.7         14.91

  0.225806452                  24.08                        23.9       23.18          22.21       21.21        12.61

  0.258064516                  23.98                        23.83      23.12          21.61       20.49        12.42

  0.290322581                  20.08                        19.92      19.27          18.11       17.72        12.38

  0.322580645                  19.15                        19.01      18.5           17.25       16.29        11.5

  0.35483871                   18.29                        18.17      17.72          16.68       15.83        11.28

  0.387096774                  17.61                        17.49      17.07          16.2        15.56        9.64

  0.419354839                  16.15                        16.03      15.51          14.69       14.09        9.474

  0.451612903                  15.23                        15.12      14.82          14.03       13.37        9.328

  0.483870968                  13.05                        12.94      12.55          11.89       11.47        8.159

  0.516129032                  12.8                         12.74      12.38          11.75       11.11        8.076

  0.548387097                  11.81                        11.73      11.37          10.77       10.42        6.992

  0.580645161                  11.5                         11.45      11.11          10.35       9.881        6.413

  0.612903226                  11.46                        11.37      11.05          10.29       9.765        6.351

  0.64516129                   10.97                        10.88      10.52          9.773       9.254        6.318

  0.677419355                  10.12                        10.07      9.77           9.242       8.776        6.005

  0.709677419                  10.05                        9.973      9.658          9.12        8.687        5.989

  0.741935484                  9.819                        9.748      9.562          9.091       8.599        5.602

  0.774193548                  8.774                        8.711      8.525          8.26        7.947        5.532

  0.806451613                  7.908                        7.846      7.591          7.05        6.668        4.785

  0.838709677                  7.51                         7.455      7.232          6.807       6.468        4.185

  0.870967742                  7.448                        7.396      7.179          6.72        6.385        4.147

  0.903225806                  6.794                        6.744      6.54           6.095       5.776        3.858

  0.935483871                  6.675                        6.625      6.416          5.967       5.65         3.851

  0.967741935                  4.2                          4.154      4.051          3.799       3.598        2.235

                                                                                                               

  0.1                          43.221                       42.999     41.731         38.85       36.747       21.961

                                                                                                  Average of   9.766667
                                                                                                  yearly       
                                                                                                  averages:    

                                                                                                               

  Inputs generated by pe4.pl -                                                                                 
  8-August-2003                                                                                                

                                                                                                               

  Data used for this run:                                                                                      

  Output File: MCPBCAa1                                                                                        

  Metfile:                     w23273.dvf                                                                      

  PRZM scenario:               CAlettuceC.txt                                                                  

  EXAMS environment file:      pond298.exv                                                                     

  Chemical Name:               MCPB_CA_lettuce_NEW_aerial                                                      

  Description                  Variable Name                Value      Units          Comments                 

  Molecular weight             mwt                          228.6      g/mol                                   

  Henry\'s Law Const.          henry                        3.42E-09   atm-m\^3/mol                            
  ---------------------------- ---------------------------- ---------- -------------- ----------- ------------ ----------

  --------------- ------------ ---------- --------------- ----------- ------------ ------
  Vapor Pressure  vapr         4.00E-07   torr                                     

  Solubility      sol          600        mg/L                                     

  Kd              Kd           0.85       mg/L                                     

  Koc             Koc                     mg/L                                     

  Photolysis      kdp          2.6        days            Half-life                
  half-life                                                                        

  Aerobic Aquatic kbacw        156        days            Halfife                  
  Metabolism                                                                       

  Anaerobic       kbacs        68         days            Halfife                  
  Aquatic                                                                          
  Metabolism                                                                       

  Aerobic Soil    asm          78         days            Halfife                  
  Metabolism                                                                       

  Hydrolysis:     pH 7         0          days            Half-life                

  Method:         CAM          1          integer         See PRZM                 
                                                          manual                   

  Incorporation   DEPI         0          cm                                       
  Depth:                                                                           

  Application     TAPP         1.68       kg/ha                                    
  Rate:                                                                            

  Application     APPEFF       0.95       fraction                                 
  Efficiency:                                                                      

  Spray Drift     DRFT         0.05       fraction of                              
                                          application                              
                                          rate applied to                          
                                          pond                                     

  Application     Date         3-Jan      dd/mm or dd/mmm                          
  Date                                    or dd-mm or                              
                                          dd-mmm                                   

  Record 17:      FILTRA                                                           

                  IPSCND       1                                                   

                  UPTKF                                                            

  Record 18:      PLVKRT                                                           

                  PLDKRT                                                           

                  FEXTRC       0.5                                                 

  Flag for Index  IR           Pond                                                
  Res. Run                                                                         

  Flag for runoff RUNOFF       none       none, monthly                            
  calc.                                   or                                       
                                          total(average                            
                                          of entire run)                           
  --------------- ------------ ---------- --------------- ----------- ------------ ------

**TABLE B.4. Prism/Exams Output California Lettuce Scenario Ground
Application**

  ---------------------------- ---------------------------- ---------- --------------- ----------- ----------- ----------
  stored as MCPBCAg1.out                                                                                       

  Chemical:                                                                                                    
  MCPB_CA_lettuce_NEW_ground                                                                                   

  PRZM environment:            modified Monday, 11 October                                                     
  CAlettuceC.txt               2004 at 16:23:40                                                                

  EXAMS environment:           modified Thuday, 29 August                                                      
  pond298.exv                  2002 at 16:33:30                                                                

  Metfile: w23273.dvf          modified Wedday, 3 July 2002                                                    
                               at 09:04:22                                                                     

  Water segment concentrations                                                                                 
  (ppb)                                                                                                        

                                                                                                               

  Year                         Peak                         96 hr      21 Day          60 Day      90 Day      Yearly

  1961                         2.02                         2.008      1.949           1.406       1.06        0.6341

  1962                         3.426                        3.402      3.304           3.081       2.919       1.995

  1963                         20.89                        20.73      20.1            19.2        18.35       10.65

  1964                         11.66                        11.57      11.27           10.71       10.21       7.169

  1965                         4.57                         4.546      4.469           4.335       4.227       3.181

  1966                         2.199                        2.183      2.116           1.972       1.869       1.471

  1967                         5.77                         5.728      5.612           5.408       5.165       3.271

  1968                         9.071                        9          8.728           8.212       7.771       4.791

  1969                         7.345                        7.287      7.046           6.54        6.191       4.118

  1970                         26.08                        25.85      24.95           23.06       21.79       13.06

  1971                         8.319                        8.262      8.024           7.522       7.411       5.876

  1972                         3.499                        3.473      3.364           3.131       3.072       2.473

  1973                         7.576                        7.542      7.32            6.806       6.437       4.151

  1974                         42.5                         42.29      41.57           38.96       36.93       21.79

  1975                         21.81                        21.65      21.03           19.66       18.67       12.97

  1976                         12.12                        12.03      11.65           11.11       10.7        7.54

  1977                         16.53                        16.4       15.85           14.95       14.76       9.52

  1978                         27.41                        27.19      26.6            24.83       23.49       14.34

  1979                         9.092                        9.046      8.786           8.236       7.981       6.015

  1980                         7.354                        7.298      7.085           6.607       6.276       4.096

  1981                         45.23                        44.89      43.69           40.82       38.72       22.5

  1982                         13.96                        13.86      13.53           12.7        12.48       9.261

  1983                         20.3                         20.17      19.58           18.31       17.35       10.48

  1984                         6.079                        6.034      5.845           5.528       5.353       3.885

  1985                         3.34                         3.316      3.218           3           2.85        1.964

  1986                         14.67                        14.57      14.21           13.34       12.67       7.416

  1987                         41.87                        41.67      40.42           37.63       35.59       21.06

  1988                         16.17                        16.05      15.6            14.55       13.75       10.44

  1989                         6.001                        5.961      5.795           5.463       5.496       3.79

  1990                         2.415                        2.398      2.328           2.173       2.065       1.571

                                                                                                               

  Sorted results                                                                                               

  Prob.                        Peak                         96 hr      21 Day          60 Day      90 Day      Yearly

  0.032258                     45.23                        44.89      43.69           40.82       38.72       22.5

  0.064516                     42.5                         42.29      41.57           38.96       36.93       21.79

  0.096774                     41.87                        41.67      40.42           37.63       35.59       21.06

  0.129032                     27.41                        27.19      26.6            24.83       23.49       14.34

  0.16129                      26.08                        25.85      24.95           23.06       21.79       13.06

  0.193548                     21.81                        21.65      21.03           19.66       18.67       12.97

  0.225806                     20.89                        20.73      20.1            19.2        18.35       10.65

  0.258065                     20.3                         20.17      19.58           18.31       17.35       10.48

  Prob.                        Peak                         96 hr      21 Day          60 Day      90 Day      Yearly

  0.290323                     16.53                        16.4       15.85           14.95       14.76       10.44

  0.322581                     16.17                        16.05      15.6            14.55       13.75       9.52

  0.354839                     14.67                        14.57      14.21           13.34       12.67       9.261

  0.387097                     13.96                        13.86      13.53           12.7        12.48       7.54

  0.419355                     12.12                        12.03      11.65           11.11       10.7        7.416

  0.451613                     11.66                        11.57      11.27           10.71       10.21       7.169

  0.483871                     9.092                        9.046      8.786           8.236       7.981       6.015

  0.516129                     9.071                        9          8.728           8.212       7.771       5.876

  0.548387                     8.319                        8.262      8.024           7.522       7.411       4.791

  0.580645                     7.576                        7.542      7.32            6.806       6.437       4.151

  0.612903                     7.354                        7.298      7.085           6.607       6.276       4.118

  0.645161                     7.345                        7.287      7.046           6.54        6.191       4.096

  0.677419                     6.079                        6.034      5.845           5.528       5.496       3.885

  0.709677                     6.001                        5.961      5.795           5.463       5.353       3.79

  0.741935                     5.77                         5.728      5.612           5.408       5.165       3.271

  0.774194                     4.57                         4.546      4.469           4.335       4.227       3.181

  0.806452                     3.499                        3.473      3.364           3.131       3.072       2.473

  0.83871                      3.426                        3.402      3.304           3.081       2.919       1.995

  0.870968                     3.34                         3.316      3.218           3           2.85        1.964

  0.903226                     2.415                        2.398      2.328           2.173       2.065       1.571

  0.935484                     2.199                        2.183      2.116           1.972       1.869       1.471

  0.967742                     2.02                         2.008      1.949           1.406       1.06        0.6341

                                                                                                               

  0.1                          40.424                       40.222     39.038          36.35       34.38       20.388

                                                                                                   Average of  7.715937
                                                                                                   yearly      
                                                                                                   averages:   

                                                                                                               

  Inputs generated by pe4.pl -                                                                                 
  8-August-2003                                                                                                

                                                                                                               

  Data used for this run:                                                                                      

  Output File: MCPBCAg1                                                                                        

  Metfile:                     w23273.dvf                                                                      

  PRZM scenario:               CAlettuceC.txt                                                                  

  EXAMS environment file:      pond298.exv                                                                     

  Chemical Name:               MCPB_CA_lettuce_NEW_ground                                                      

  Description                  Variable Name                Value      Units           Comments                

  Molecular weight             mwt                          228.6      g/mol                                   

  Henry\'s Law Const.          henry                        3.42E-09   atm-m\^3/mol                            

  Vapor Pressure               vapr                         4.00E-07   torr                                    

  Solubility                   sol                          600        mg/L                                    

  Kd                           Kd                           0.85       mg/L                                    

  Koc                          Koc                                     mg/L                                    

  Photolysis half-life         kdp                          2.6        days            Half-life               

  Aerobic Aquatic Metabolism   kbacw                        156        days            Halfife                 

  Anaerobic Aquatic Metabolism kbacs                        68         days            Halfife                 

  Aerobic Soil Metabolism      asm                          78         days            Halfife                 

  Hydrolysis:                  pH 7                         0          days            Half-life               

  Method:                      CAM                          1          integer         See PRZM                
                                                                                       manual                  

  Incorporation Depth:         DEPI                         0          cm                                      

  Application Rate:            TAPP                         1.68       kg/ha                                   

  Application Efficiency:      APPEFF                       0.99       fraction                                

  Spray Drift                  DRFT                         0.01       fraction of                             
                                                                       application                             
                                                                       rate applied to                         
                                                                       pond                                    

  Application Date             Date                         3-Jan      dd/mm or dd/mmm                         
                                                                       or dd-mm or                             
                                                                       dd-mmm                                  

  Record 17:                   FILTRA                                                                          

                               IPSCND                       1                                                  

                               UPTKF                                                                           

  Record 18:                   PLVKRT                                                                          

                               PLDKRT                                                                          

                               FEXTRC                       0.5                                                

  Flag for Index Res. Run      IR                           Pond                                               

  Flag for runoff calc.        RUNOFF                       none       none, monthly                           
                                                                       or                                      
                                                                       total(average                           
                                                                       of entire run)                          
  ---------------------------- ---------------------------- ---------- --------------- ----------- ----------- ----------

**TABLE B.5.** **Prism/Exams Output Oregon Bean Scenario Aerial
Application**

  ----------------------------- ----------------------------- -------- --------- ---------- ----------- ----------
  stored as MCPBORa1.out                                                                                

  Chemical:                                                                                             
  MCPB_OR_snapbean_NEW_aerial                                                                           

  PRZM environment:             modified Satday, 12 October                                             
  ORsnbeansC.txt                2002 at 17:20:58                                                        

  EXAMS environment:            modified Thuday, 29 August                                              
  pond298.exv                   2002 at 16:33:30                                                        

  Metfile: w24232.dvf           modified Wedday, 3 July 2002                                            
                                at 09:06:10                                                             

  Water segment concentrations                                                                          
  (ppb)                                                                                                 

                                                                                                        

  Year                          Peak                          96 hr    21 Day    60 Day     90 Day      Yearly

  1961                          39.96                         39.78    39.16     37.25      35.7        21.12

  1962                          18.43                         18.33    18.14     17.61      16.99       12.51

  1963                          14.98                         14.93    14.63     13.96      13.54       9.535

  1964                          19.47                         19.39    19        18.24      17.57       11.51

  1965                          11.6                          11.54    11.27     10.96      10.78       7.885

  1966                          25.77                         25.62    25.15     23.75      22.71       14.12

  1967                          15.06                         15.02    14.75     14.05      13.54       9.435

  1968                          13.02                         12.94    12.71     12.06      11.56       7.818

  1969                          13.17                         13.09    12.82     12.24      11.68       7.82

  1970                          16.94                         16.87    16.49     15.74      15.1        9.766

  1971                          25.85                         25.76    25.26     24.12      23.23       14.93

  1972                          37.5                          37.38    37.06     35.37      33.94       21.53

  1973                          27.86                         27.71    27.48     26.45      25.38       17.23

  1974                          23.75                         23.63    23.19     22.04      21.21       14.33

  1975                          16.66                         16.6     16.26     15.44      14.77       10.37

  1976                          13.63                         13.56    13.28     12.59      12.04       8.439

  1977                          17.95                         17.89    17.56     16.63      15.94       10.31

  1978                          11.13                         11.06    10.9      10.42      10.19       7.179

  1979                          22.32                         22.18    21.7      20.53      19.61       12.14

  1980                          19.67                         19.56    19.2      18.16      17.4        11.71

  1981                          33.45                         33.25    32.84     31.87      30.68       19.47

  1982                          27.84                         27.73    27.31     26.01      24.93       16.67

  1983                          26.25                         26.13    25.62     24.29      23.2        15.34

  1984                          16.72                         16.67    16.35     15.53      14.89       10.52

  1985                          14.75                         14.7     14.4      13.62      13          8.816

  1986                          22.81                         22.67    22.37     21.61      20.74       13.1

  1987                          21.24                         21.12    20.74     19.77      18.92       12.39

  1988                          15.01                         14.92    14.63     14.23      13.71       9.378

  1989                          29.8                          29.68    29.33     27.86      26.6        16.58

  1990                          22.58                         22.49    22.01     20.78      19.9        13.45

                                                                                                        

  Sorted results                                                                                        

  Prob.                         Peak                          96 hr    21 Day    60 Day     90 Day      Yearly

  0.032258                      39.96                         39.78    39.16     37.25      35.7        21.53

  0.064516                      37.5                          37.38    37.06     35.37      33.94       21.12

  0.096774                      33.45                         33.25    32.84     31.87      30.68       19.47

  0.129032                      29.8                          29.68    29.33     27.86      26.6        17.23

  0.16129                       27.86                         27.73    27.48     26.45      25.38       16.67

  0.193548                      27.84                         27.71    27.31     26.01      24.93       16.58

  0.225806                      26.25                         26.13    25.62     24.29      23.23       15.34

  Prob.                         Peak                          96 hr    21 Day    60 Day     90 Day      Yearly

  0.258065                      25.85                         25.76    25.26     24.12      23.2        14.93

  0.290323                      25.77                         25.62    25.15     23.75      22.71       14.33

  0.322581                      23.75                         23.63    23.19     22.04      21.21       14.12

  0.354839                      22.81                         22.67    22.37     21.61      20.74       13.45

  0.387097                      22.58                         22.49    22.01     20.78      19.9        13.1

  0.419355                      22.32                         22.18    21.7      20.53      19.61       12.51

  0.451613                      21.24                         21.12    20.74     19.77      18.92       12.39

  0.483871                      19.67                         19.56    19.2      18.24      17.57       12.14

  0.516129                      19.47                         19.39    19        18.16      17.4        11.71

  0.548387                      18.43                         18.33    18.14     17.61      16.99       11.51

  0.580645                      17.95                         17.89    17.56     16.63      15.94       10.52

  0.612903                      16.94                         16.87    16.49     15.74      15.1        10.37

  0.645161                      16.72                         16.67    16.35     15.53      14.89       10.31

  0.677419                      16.66                         16.6     16.26     15.44      14.77       9.766

  0.709677                      15.06                         15.02    14.75     14.23      13.71       9.535

  0.741935                      15.01                         14.93    14.63     14.05      13.54       9.435

  0.774194                      14.98                         14.92    14.63     13.96      13.54       9.378

  0.806452                      14.75                         14.7     14.4      13.62      13          8.816

  0.83871                       13.63                         13.56    13.28     12.59      12.04       8.439

  0.870968                      13.17                         13.09    12.82     12.24      11.68       7.885

  0.903226                      13.02                         12.94    12.71     12.06      11.56       7.82

  0.935484                      11.6                          11.54    11.27     10.96      10.78       7.818

  0.967742                      11.13                         11.06    10.9      10.42      10.19       7.179

                                                                                                        

  0.1                           33.085                        32.893   32.489    31.469     30.272      19.246

                                                                                            Average of  12.51337
                                                                                            yearly      
                                                                                            averages:   

                                                                                                        

  Inputs generated by pe4.pl -                                                                          
  8-August-2003                                                                                         

                                                                                                        

  Data used for this run:                                                                               

  Output File: MCPBORa1                                                                                 

  Metfile:                      w24232.dvf                                                              

  PRZM scenario:                ORsnbeansC.txt                                                          

  EXAMS environment file:       pond298.exv                                                             

  Chemical Name:                MCPB_OR_snapbean_NEW_aerial                                             

  Description                   Variable Name                 Value    Units     Comments               

  Molecular weight              mwt                           228.6    g/mol                            
  ----------------------------- ----------------------------- -------- --------- ---------- ----------- ----------

  --------------- ------------- ---------- --------------- ----------- ---------- -------
  Henry\'s Law    henry         3.42E-09   atm-m\^3/mol                           
  Const.                                                                          

  Vapor Pressure  vapr          4.00E-07   torr                                   

  Solubility      sol           600        mg/L                                   

  Kd              Kd            0.85       mg/L                                   

  Koc             Koc                      mg/L                                   

  Photolysis      kdp           2.6        days            Half-life              
  half-life                                                                       

  Aerobic Aquatic kbacw         156        days            Halfife                
  Metabolism                                                                      

  Anaerobic       kbacs         68         days            Halfife                
  Aquatic                                                                         
  Metabolism                                                                      

  Aerobic Soil    asm           78         days            Halfife                
  Metabolism                                                                      

  Hydrolysis:     pH 7          0          days            Half-life              

  Method:         CAM           1          integer         See PRZM               
                                                           manual                 

  Incorporation   DEPI          0          cm                                     
  Depth:                                                                          

  Application     TAPP          1.68       kg/ha                                  
  Rate:                                                                           

  Application     APPEFF        0.95       fraction                               
  Efficiency:                                                                     

  Spray Drift     DRFT          0.05       fraction of                            
                                           application                            
                                           rate applied to                        
                                           pond                                   

  Application     Date          3-Jan      dd/mm or dd/mmm                        
  Date                                     or dd-mm or                            
                                           dd-mmm                                 

  Record 17:      FILTRA                                                          

                  IPSCND        1                                                 

                  UPTKF                                                           

  Record 18:      PLVKRT                                                          

                  PLDKRT                                                          

                  FEXTRC        0.5                                               

  Flag for Index  IR            Pond                                              
  Res. Run                                                                        

  Flag for runoff RUNOFF        none       none, monthly                          
  calc.                                    or                                     
                                           total(average                          
                                           of entire run)                         
  --------------- ------------- ---------- --------------- ----------- ---------- -------

**TABLE B.6. Prism/Exams Output Oregon Bean Scenario Ground
Application**

  ----------------------------- ----------------------------- ---------- --------------- ----------- ----------- ----------
  stored as MCPBORg1.out                                                                                         

  Chemical:                                                                                                      
  MCPB_OR_snapbean_NEW_ground                                                                                    

  PRZM environment:             modified Satday, 12 October                                                      
  ORsnbeansC.txt                2002 at 17:20:58                                                                 

  EXAMS environment:            modified Thuday, 29 August                                                       
  pond298.exv                   2002 at 16:33:30                                                                 

  Metfile: w24232.dvf           modified Wedday, 3 July 2002                                                     
                                at 09:06:10                                                                      

  Water segment concentrations                                                                                   
  (ppb)                                                                                                          

                                                                                                                 

  Year                          Peak                          96 hr      21 Day          60 Day      90 Day      Yearly

  1961                          38.19                         38.03      37.42           35.6        34.13       20.18

  1962                          14.67                         14.6       14.45           14.07       13.64       10.39

  1963                          10.95                         10.91      10.69           10.17       9.749       6.991

  1964                          15.25                         15.19      14.89           14.27       13.72       8.96

  1965                          7.58                          7.536      7.367           6.997       6.81        5.206

  1966                          21.78                         21.65      21.28           20.09       19.18       11.74

  1967                          10.75                         10.72      10.54           10.05       9.628       6.903

  1968                          8.725                         8.677      8.52            8.086       7.741       5.231

  1969                          8.776                         8.722      8.571           8.214       7.847       5.177

  1970                          12.65                         12.59      12.3            11.78       11.3        7.21

  1971                          21.89                         21.81      21.38           20.37       19.62       12.52

  1972                          33.99                         33.89      33.56           32.05       30.76       19.42

  1973                          23.96                         23.84      23.61           22.78       21.87       14.96

  1974                          19.74                         19.64      19.26           18.31       17.58       11.93

  1975                          12.44                         12.41      12.17           11.55       11.05       7.803

  1976                          9.316                         9.275      9.087           8.601       8.231       5.754

  1977                          13.61                         13.57      13.33           12.63       12.1        7.728

  1978                          6.75                          6.713      6.64            6.389       6.113       4.515

  1979                          18.1                          17.98      17.58           16.64       15.9        9.694

  1980                          15.53                         15.45      15.17           14.36       13.74       9.225

  1981                          29.9                          29.72      29.41           28.5        27.46       17.31

  1982                          23.87                         23.76      23.44           22.35       21.43       14.41

  1983                          22.33                         22.23      21.82           20.68       19.75       13.03

  1984                          12.52                         12.48      12.24           11.64       11.16       7.997

  1985                          10.54                         10.5       10.27           9.716       9.274       6.221

  1986                          18.96                         18.84      18.42           17.9        17.19       10.72

  1987                          17.17                         17.08      16.76           15.93       15.27       10.03

  1988                          10.93                         10.87      10.65           10.28       9.931       6.886

  1989                          26.1                          25.99      25.65           24.39       23.29       14.36

  1990                          18.53                         18.46      18.08           17.07       16.33       11.11

                                                                                                                 

  Sorted results                                                                                                 

  Prob.                         Peak                          96 hr      21 Day          60 Day      90 Day      Yearly

  0.032258                      38.19                         38.03      37.42           35.6        34.13       20.18

  0.064516                      33.99                         33.89      33.56           32.05       30.76       19.42

  0.096774                      29.9                          29.72      29.41           28.5        27.46       17.31

  0.129032                      26.1                          25.99      25.65           24.39       23.29       14.96

  0.16129                       23.96                         23.84      23.61           22.78       21.87       14.41

  0.193548                      23.87                         23.76      23.44           22.35       21.43       14.36

  0.225806                      22.33                         22.23      21.82           20.68       19.75       13.03

  0.258065                      21.89                         21.81      21.38           20.37       19.62       12.52

  0.290323                      21.78                         21.65      21.28           20.09       19.18       11.93

  Prob.                         Peak                          96 hr      21 Day          60 Day      90 Day      Yearly

  0.322581                      19.74                         19.64      19.26           18.31       17.58       11.74

  0.354839                      18.96                         18.84      18.42           17.9        17.19       11.11

  0.387097                      18.53                         18.46      18.08           17.07       16.33       10.72

  0.419355                      18.1                          17.98      17.58           16.64       15.9        10.39

  0.451613                      17.17                         17.08      16.76           15.93       15.27       10.03

  0.483871                      15.53                         15.45      15.17           14.36       13.74       9.694

  0.516129                      15.25                         15.19      14.89           14.27       13.72       9.225

  0.548387                      14.67                         14.6       14.45           14.07       13.64       8.96

  0.580645                      13.61                         13.57      13.33           12.63       12.1        7.997

  0.612903                      12.65                         12.59      12.3            11.78       11.3        7.803

  0.645161                      12.52                         12.48      12.24           11.64       11.16       7.728

  0.677419                      12.44                         12.41      12.17           11.55       11.05       7.21

  0.709677                      10.95                         10.91      10.69           10.28       9.931       6.991

  0.741935                      10.93                         10.87      10.65           10.17       9.749       6.903

  0.774194                      10.75                         10.72      10.54           10.05       9.628       6.886

  0.806452                      10.54                         10.5       10.27           9.716       9.274       6.221

  0.83871                       9.316                         9.275      9.087           8.601       8.231       5.754

  0.870968                      8.776                         8.722      8.571           8.214       7.847       5.231

  0.903226                      8.725                         8.677      8.52            8.086       7.741       5.206

  0.935484                      7.58                          7.536      7.367           6.997       6.81        5.177

  0.967742                      6.75                          6.713      6.64            6.389       6.113       4.515

                                                                                                                 

  0.1                           29.52                         29.347     29.034          28.089      27.043      17.075

                                                                                                     Average of  10.12037
                                                                                                     yearly      
                                                                                                     averages:   

                                                                                                                 

  Inputs generated by pe4.pl -                                                                                   
  8-August-2003                                                                                                  

                                                                                                                 

  Data used for this run:                                                                                        

  Output File: MCPBORg1                                                                                          

  Metfile:                      w24232.dvf                                                                       

  PRZM scenario:                ORsnbeansC.txt                                                                   

  EXAMS environment file:       pond298.exv                                                                      

  Chemical Name:                MCPB_OR_snapbean_NEW_ground                                                      

  Description                   Variable Name                 Value      Units           Comments                

  Molecular weight              mwt                           228.6      g/mol                                   

  Henry\'s Law Const.           henry                         3.42E-09   atm-m\^3/mol                            

  Vapor Pressure                vapr                          4.00E-07   torr                                    

  Solubility                    sol                           600        mg/L                                    

  Kd                            Kd                            0.85       mg/L                                    

  Koc                           Koc                                      mg/L                                    

  Photolysis half-life          kdp                           2.6        days            Half-life               

  Aerobic Aquatic Metabolism    kbacw                         156        days            Halfife                 

  Anaerobic Aquatic Metabolism  kbacs                         68         days            Halfife                 

  Aerobic Soil Metabolism       asm                           78         days            Halfife                 

  Hydrolysis:                   pH 7                          0          days            Half-life               

  Method:                       CAM                           1          integer         See PRZM                
                                                                                         manual                  

  Incorporation Depth:          DEPI                          0          cm                                      

  Application Rate:             TAPP                          1.68       kg/ha                                   

  Application Efficiency:       APPEFF                        0.99       fraction                                

  Spray Drift                   DRFT                          0.01       fraction of                             
                                                                         application                             
                                                                         rate applied to                         
                                                                         pond                                    

  Application Date              Date                          3-Jan      dd/mm or dd/mmm                         
                                                                         or dd-mm or                             
                                                                         dd-mmm                                  

  Record 17:                    FILTRA                                                                           

                                IPSCND                        1                                                  

                                UPTKF                                                                            

  Record 18:                    PLVKRT                                                                           

                                PLDKRT                                                                           

                                FEXTRC                        0.5                                                

  Flag for Index Res. Run       IR                            Pond                                               

  Flag for runoff calc.         RUNOFF                        none       none, monthly                           
                                                                         or                                      
                                                                         total(average                           
                                                                         of entire run)                          
  ----------------------------- ----------------------------- ---------- --------------- ----------- ----------- ----------

**APPENDIX C: Terrestrial Bird and Mammal TREX Version 1.1 Model
Results**

**TREX (Version1.1)**

As part of the terrestrial assessment, EFED modeled exposure
concentrations of MCPB to non-target animals following the proposed
application rates provided by the registrant. For terrestrial birds and
mammals, estimates of initial levels of MCPB residues on various food
items, which may be contacted or consumed by wildlife, were determined
using the Kenega-Fletcher nomogram followed by a first order decline
model TREX 1.1.

Upper bound Kenega-Fletcher values were used for RQ calculations

1\. Upper Bound Kenaga Residues for RQ Calculations Birds and Mammals

TREX Version 1.1 Model

> (May 25, 2005)

+-------------------------------+-----------+--------------+----------+
|                               |           |              |          |
+-------------------------------+-----------+--------------+----------+
| INPUT VALUES                  |           |              |          |
+-------------------------------+-----------+--------------+----------+
| Chemical Name:                | MCPB      |              |          |
+-------------------------------+-----------+--------------+----------+
| Use                           | Peas      |              |          |
+-------------------------------+-----------+--------------+----------+
| Formulation                   | MCPB      |              |          |
|                               | sodium    |              |          |
|                               | salt      |              |          |
+-------------------------------+-----------+--------------+----------+
| Application Rate              | 1.5       | lbs          |          |
|                               |           | a.e./acre    |          |
+-------------------------------+-----------+--------------+----------+
| Half-life                     | 35        | days         |          |
+-------------------------------+-----------+--------------+----------+
| Application Interval          | 1         | days         |          |
+-------------------------------+-----------+--------------+----------+
| Maximum \# Apps./Year         | 1         |              |          |
+-------------------------------+-----------+--------------+----------+
| Length of Simulation          | 1         | year         |          |
+-------------------------------+-----------+--------------+----------+
| Concentration of Concern      | 0.00      | (ppm)        |          |
+-------------------------------+-----------+--------------+----------+
| Name of Concentration of      | Avian     |              |          |
| Concern                       | acute     |              |          |
|                               | LC50      |              |          |
+-------------------------------+-----------+--------------+----------+
| **Endpoints**                 |           |              |          |
+-------------------------------+-----------+--------------+----------+
| Avian                         | >         |              |          |
|                               |  Bobwhite |              |          |
|                               | > quail   |              |          |
|                               | >         |              |          |
|                               | > LD50    |              |          |
|                               | > (       |              |          |
|                               | mg/kg-bw) |              |          |
+-------------------------------+-----------+--------------+----------+
|                               | Bobwhite  |              |          |
|                               | quail     |              |          |
|                               |           |              |          |
|                               | LC50      |              |          |
|                               | (mg       |              |          |
|                               | /kg-diet) |              |          |
+-------------------------------+-----------+--------------+----------+
|                               | Bobwhite  |              |          |
|                               | quail     |              |          |
|                               | NOAEL     |              |          |
|                               | (         |              |          |
|                               | mg/kg-bw) |              |          |
+-------------------------------+-----------+--------------+----------+
|                               | Bobwhite  |              |          |
|                               | quail     |              |          |
|                               | NOAEC     |              |          |
|                               | (mg       |              |          |
|                               | /kg-diet) |              |          |
+-------------------------------+-----------+--------------+----------+
|                               |           |              |          |
+-------------------------------+-----------+--------------+----------+
| Mammals                       | > LD50    |              |          |
|                               | > (       |              |          |
|                               | mg/kg-bw) |              |          |
+-------------------------------+-----------+--------------+----------+
|                               | LC50      |              |          |
|                               | (mg       |              |          |
|                               | /kg-diet) |              |          |
+-------------------------------+-----------+--------------+----------+
|                               | NOAEL     |              |          |
|                               | (         |              |          |
|                               | mg/kg-bw) |              |          |
+-------------------------------+-----------+--------------+----------+
|                               | NOAEC     |              |          |
|                               | (mg       |              |          |
|                               | /kg-diet) |              |          |
+-------------------------------+-----------+--------------+----------+
|                               |           |              |          |
+-------------------------------+-----------+--------------+----------+
| **EECs (ppm)**                | *         |              |          |
|                               | *Kenaga** |              |          |
+-------------------------------+-----------+--------------+----------+
|                               | *         |              |          |
|                               | *Values** |              |          |
+-------------------------------+-----------+--------------+----------+
| Short Grass                   | 360       |              |          |
+-------------------------------+-----------+--------------+----------+
| Tall Grass                    | 165       |              |          |
+-------------------------------+-----------+--------------+----------+
| Broadleafplants/sminsects     | 202.5     |              |          |
+-------------------------------+-----------+--------------+----------+
| Fruits/pods/seeds/lg insects  | 22.50     |              |          |
+-------------------------------+-----------+--------------+----------+

+--------------------------+--------+--------+---------------+--------+
| **Avian Results**        |        |        |               |        |
|                          |        |        |               |        |
| **Upper Bound Kenaga**   |        |        |               |        |
+--------------------------+--------+--------+---------------+--------+
|                          |        |        |               |        |
+--------------------------+--------+--------+---------------+--------+
|                          | **A    | **     | **% body      | **Adju |
|                          | vian** | Body** | wgt**         | sted** |
+--------------------------+--------+--------+---------------+--------+
|                          | **C    | **We   | **consumed**  | **     |
|                          | lass** | ight** |               | LD50** |
+--------------------------+--------+--------+---------------+--------+
|                          | Small  | 20     | 114           | 182    |
+--------------------------+--------+--------+---------------+--------+
|                          | Mid    | 100    | 65            | 232    |
+--------------------------+--------+--------+---------------+--------+
|                          | Large  | 1000   | 29            | 327    |
+--------------------------+--------+--------+---------------+--------+
|                          |        |        |               |        |
+--------------------------+--------+--------+---------------+--------+
| EEC equivalent dose      | Avian  |        |               |        |
| (mg/kg-bw)               | C      |        |               |        |
|                          | lasses |        |               |        |
|                          | and    |        |               |        |
|                          | Body   |        |               |        |
|                          | W      |        |               |        |
|                          | eights |        |               |        |
+--------------------------+--------+--------+---------------+--------+
|                          | small  | mid    | large         |        |
+--------------------------+--------+--------+---------------+--------+
|                          | 20 g   | 100 g  | 1000 g        |        |
+--------------------------+--------+--------+---------------+--------+
| Short Grass              | 410    | 234    | 104           |        |
+--------------------------+--------+--------+---------------+--------+
| Tall Grass               | 188    | 107    | 48            |        |
+--------------------------+--------+--------+---------------+--------+
| Broadleaf plants/sm      | 231    | 132    | 59            |        |
| insects                  |        |        |               |        |
+--------------------------+--------+--------+---------------+--------+
| Fruits/pods/lg insects   | 26     | 15     | 7             |        |
+--------------------------+--------+--------+---------------+--------+
|                          |        |        |               |        |
+--------------------------+--------+--------+---------------+--------+
| Dose-based RQs           | Avian  |        |               |        |
|                          | Acute  |        |               |        |
| (daily dose/LD50)        | RQs    |        |               |        |
+--------------------------+--------+--------+---------------+--------+
|                          | 20 g   | 100 g  | 1000 g        |        |
+--------------------------+--------+--------+---------------+--------+
| Short Grass              | 2.26   | 1.01   | 0.32          |        |
+--------------------------+--------+--------+---------------+--------+
| Tall Grass               | 1.03   | 0.46   | 0.15          |        |
+--------------------------+--------+--------+---------------+--------+
| Broadleaf plants/sm      | 1.27   | 0.57   | 0.18          |        |
| insects                  |        |        |               |        |
+--------------------------+--------+--------+---------------+--------+
| Fruits/pods/lg insects   | 0.14   | 0.06   | 0.02          |        |
+--------------------------+--------+--------+---------------+--------+
|                          |        |        |               |        |
+--------------------------+--------+--------+---------------+--------+
|                          |        |        |               |        |
+--------------------------+--------+--------+---------------+--------+

+-----------------------------------------+-------------+-------------+
| Dietary-based RQs                       | RQs         |             |
|                                         |             |             |
| (dietary-based EEC/LD50)                |             |             |
+-----------------------------------------+-------------+-------------+
|                                         | Acute       | Chronic     |
+-----------------------------------------+-------------+-------------+
| Short Grass                             |             | 0.36        |
+-----------------------------------------+-------------+-------------+
| Tall Grass                              |             | 0.17        |
+-----------------------------------------+-------------+-------------+
| Broadleaf plants/sm insects             |             | 0.20        |
+-----------------------------------------+-------------+-------------+
| Fruits/pods/lg insects                  |             | 0.02        |
+-----------------------------------------+-------------+-------------+

+--------------+----------+-------+--------+---------+------+------+
| **Mammalian  | **Upper  |       |        |         |      |      |
| Results**    | Bound    |       |        |         |      |      |
|              | Kenaga** |       |        |         |      |      |
+--------------+----------+-------+--------+---------+------+------+
|              |          |       |        |         |      |      |
+--------------+----------+-------+--------+---------+------+------+
|              | M        | Body  | \%     | A       | Adju |      |
|              | ammalian |       | body   | djusted | sted |      |
|              |          |       | wgt    |         |      |      |
+--------------+----------+-------+--------+---------+------+------+
|              | Class    | W     | co     | LD50    | N    |      |
|              |          | eight | nsumed |         | OAEL |      |
+--------------+----------+-------+--------+---------+------+------+
|              |          | 15    | 95     | 1829    | 17   |      |
+--------------+----------+-------+--------+---------+------+------+
|              | Her      | 35    | 66     | 1480    | 14   |      |
|              | bivores/ |       |        |         |      |      |
+--------------+----------+-------+--------+---------+------+------+
|              | inse     | 1000  | 15     | 640     | 6    |      |
|              | ctivores |       |        |         |      |      |
+--------------+----------+-------+--------+---------+------+------+
|              |          | 15    | 21     | 1829    | 10   |      |
+--------------+----------+-------+--------+---------+------+------+
|              | Gr       | 35    | 15     | 1480    | 14   |      |
|              | ainvores |       |        |         |      |      |
+--------------+----------+-------+--------+---------+------+------+
|              |          | 1000  | 3      | 640     | 6    |      |
+--------------+----------+-------+--------+---------+------+------+
|              |          |       |        |         |      |      |
+--------------+----------+-------+--------+---------+------+------+
| EEC          | M        |       |        |         |      |      |
| equivalent   | ammalian |       |        |         |      |      |
| dose         | Classes  |       |        |         |      |      |
|              | and Body |       |        |         |      |      |
| (mg/kg-bw)   | weight   |       |        |         |      |      |
+--------------+----------+-------+--------+---------+------+------+
|              | Her      |       |        | Gra     |      |      |
|              | bivores/ |       |        | nivores |      |      |
|              | inse     |       |        |         |      |      |
|              | ctivores |       |        |         |      |      |
+--------------+----------+-------+--------+---------+------+------+
|              | 15 g     | 35 g  | 1000 g | 15 g    | 35 g | 1000 |
|              |          |       |        |         |      | g    |
+--------------+----------+-------+--------+---------+------+------+
| Short Grass  | 342      | 238   | 54     |         |      |      |
+--------------+----------+-------+--------+---------+------+------+
| Tall Grass   | 157      | 109   | 25     |         |      |      |
+--------------+----------+-------+--------+---------+------+------+
| Broadleaf    | 192      | 134   | 30     |         |      |      |
| plants/sm    |          |       |        |         |      |      |
| Insects      |          |       |        |         |      |      |
+--------------+----------+-------+--------+---------+------+------+
| Fruit        | 21       | 15    | 3      | 5       | 3    | 1    |
| s/pods/seed/ |          |       |        |         |      |      |
|              |          |       |        |         |      |      |
| > lg insects |          |       |        |         |      |      |
+--------------+----------+-------+--------+---------+------+------+
|              |          |       |        |         |      |      |
+--------------+----------+-------+--------+---------+------+------+
| Dose-based   | 15 g     |       | 35 g   |         |      | 1000 |
| RQs (daily   | mammal   |       | mammal |         |      | g    |
| dose/LD50 or |          |       |        |         |      | ma   |
| NOAEL)       |          |       |        |         |      | mmal |
+--------------+----------+-------+--------+---------+------+------+
|              |          |       |        |         |      |      |
+--------------+----------+-------+--------+---------+------+------+
|              | Acute    | Ch    | Acute  | Chronic | A    | Chr  |
|              |          | ronic |        |         | cute | onic |
+--------------+----------+-------+--------+---------+------+------+
| Short Grass  | 0.19     | 19.94 | 0.16   | 17.12   | 0.08 | 9    |
+--------------+----------+-------+--------+---------+------+------+
| Tall Grass   | 0.09     | 9.14  | 0.07   | 7.85    | 0.04 | 4.12 |
+--------------+----------+-------+--------+---------+------+------+
| Broadleaf    | 0.11     | 11.22 | 0.09   | 9.63    | 0.05 | 5.06 |
| plants/sm    |          |       |        |         |      |      |
| insects      |          |       |        |         |      |      |
+--------------+----------+-------+--------+---------+------+------+
| Fr           | 0.01     | 1.25  | 0.01   | 1.07    | 0.01 | 0.56 |
| uits/pods/lg |          |       |        |         |      |      |
| insects      |          |       |        |         |      |      |
+--------------+----------+-------+--------+---------+------+------+
| Seeds        | 0.00     | 0.47  | 0      | 0.24    | 0.00 | 0.11 |
| (granivore)  |          |       |        |         |      |      |
+--------------+----------+-------+--------+---------+------+------+
|              |          |       |        |         |      |      |
+--------------+----------+-------+--------+---------+------+------+

**2.** .**Mean Kenaga Residues for Risk Characterization only Birds and
Mammals**

**TREX model version 1.1**

+----------------------+---------+--------------+----------+-----------+
| **Avian Results Mean |         |              |          |           |
| Kenaga Residues**    |         |              |          |           |
+----------------------+---------+--------------+----------+-----------+
|                      |         |              |          |           |
+----------------------+---------+--------------+----------+-----------+
|                      | Avian   | Body         | \% body  | Adjusted  |
|                      |         |              | wgt      |           |
+----------------------+---------+--------------+----------+-----------+
|                      | Class   | Weight       | consumed | LD50      |
+----------------------+---------+--------------+----------+-----------+
|                      | Small   | 20           | 114      | 182       |
+----------------------+---------+--------------+----------+-----------+
|                      | Mid     | 100          | 65       | 232       |
+----------------------+---------+--------------+----------+-----------+
|                      | Large   | 1000         | 29       | 327       |
+----------------------+---------+--------------+----------+-----------+
|                      |         |              |          |           |
+----------------------+---------+--------------+----------+-----------+
| EEC equivalent dose  | Avian   |              |          |           |
|                      | Classes |              |          |           |
| (mg/kg-bw)           | and     |              |          |           |
|                      | Body    |              |          |           |
|                      | Weights |              |          |           |
+----------------------+---------+--------------+----------+-----------+
|                      | small   | mid          | large    |           |
+----------------------+---------+--------------+----------+-----------+
|                      | 20 g    | 100 g        | 1000 g   |           |
+----------------------+---------+--------------+----------+-----------+
| Short Grass          | 145     | 83           | 37       |           |
+----------------------+---------+--------------+----------+-----------+
| Tall Grass           | 62      | 35           | 16       |           |
+----------------------+---------+--------------+----------+-----------+
| Broadleaf plants/    | 77      | 44           | 20       |           |
|                      |         |              |          |           |
| > sm insects         |         |              |          |           |
+----------------------+---------+--------------+----------+-----------+
| Fruits/pods/         | 12      | 7            | 3        |           |
|                      |         |              |          |           |
| > lg insects         |         |              |          |           |
+----------------------+---------+--------------+----------+-----------+
|                      |         |              |          |           |
+----------------------+---------+--------------+----------+-----------+
| Dose-based Rqs       | Avian   |              |          |           |
| (daily dose/LD50)    | Acute   |              |          |           |
|                      | RQs     |              |          |           |
+----------------------+---------+--------------+----------+-----------+
|                      | 20 g    | 100 g        | 1000 g   |           |
+----------------------+---------+--------------+----------+-----------+
| Short Grass          | 0.8     | 0.36         | 0.11     |           |
+----------------------+---------+--------------+----------+-----------+
| Tall Grass           | 0.34    | 0.15         | 0.05     |           |
+----------------------+---------+--------------+----------+-----------+
| Broadleaf plants/    | 0.42    | 0.19         | 0.06     |           |
|                      |         |              |          |           |
| > sm insects         |         |              |          |           |
+----------------------+---------+--------------+----------+-----------+
| Fruits/pods/         | 0.07    | 0.03         | 0.01     |           |
|                      |         |              |          |           |
| > lg insects         |         |              |          |           |
+----------------------+---------+--------------+----------+-----------+
|                      |         |              |          |           |
+----------------------+---------+--------------+----------+-----------+
| Dietary-based RQs    | RQs     |              |          |           |
| (EEC/LC50 or NOAEC)  |         |              |          |           |
+----------------------+---------+--------------+----------+-----------+
|                      |         |              |          |           |
+----------------------+---------+--------------+----------+-----------+
|                      | Acute   | Chronic      |          |           |
+----------------------+---------+--------------+----------+-----------+
| Short Grass          |         | 0.13         |          |           |
+----------------------+---------+--------------+----------+-----------+
| Tall Grass           |         | 0.05         |          |           |
+----------------------+---------+--------------+----------+-----------+
| Broadleaf plants/sm  |         | 0.07         |          |           |
| Insects              |         |              |          |           |
+----------------------+---------+--------------+----------+-----------+
| Fruits/pods/lg       |         | 0.01         |          |           |
| insects              |         |              |          |           |
+----------------------+---------+--------------+----------+-----------+
|                      |         |              |          |           |
+----------------------+---------+--------------+----------+-----------+

+--------------+---------+-----+------+------+-----+----------------+
| **Mammalian  |         |     |      |      |     |                |
| Results Mean |         |     |      |      |     |                |
| Kenaga       |         |     |      |      |     |                |
| Residues**   |         |     |      |      |     |                |
+--------------+---------+-----+------+------+-----+----------------+
|              |         |     |      |      |     |                |
+--------------+---------+-----+------+------+-----+----------------+
|              | Ma      | B   | \%   | Adju | Ad  |                |
|              | mmalian | ody | body | sted | jus |                |
|              |         |     | wgt  |      | ted |                |
+--------------+---------+-----+------+------+-----+----------------+
|              | Class   | Wei | cons | LD50 | NO  |                |
|              |         | ght | umed |      | AEL |                |
+--------------+---------+-----+------+------+-----+----------------+
|              |         | 15  | 95   | 1829 | 19  |                |
+--------------+---------+-----+------+------+-----+----------------+
|              | Her     | 35  | 66   | 1480 | 15  |                |
|              | bivores |     |      |      |     |                |
+--------------+---------+-----+------+------+-----+----------------+
|              | insec   | 1   | 15   | 640  | 7   |                |
|              | tivores | 000 |      |      |     |                |
+--------------+---------+-----+------+------+-----+----------------+
|              |         | 15  | 21   | 1829 | 19  |                |
+--------------+---------+-----+------+------+-----+----------------+
|              | Gra     | 35  | 15   | 1480 | 15  |                |
|              | invores |     |      |      |     |                |
+--------------+---------+-----+------+------+-----+----------------+
|              |         | 1   | 3    | 640  | 4   |                |
|              |         | 000 |      |      |     |                |
+--------------+---------+-----+------+------+-----+----------------+
|              |         |     |      |      |     |                |
+--------------+---------+-----+------+------+-----+----------------+
| EEC          | Ma      |     |      |      |     |                |
| equivalent   | mmalian |     |      |      |     |                |
| dose         | Classes |     |      |      |     |                |
| (mg/kg-bw)   | and     |     |      |      |     |                |
|              | Body    |     |      |      |     |                |
|              | weight  |     |      |      |     |                |
+--------------+---------+-----+------+------+-----+----------------+
|              | **Herb  |     |      | **   |     |                |
|              | ivores/ |     |      | Gran |     |                |
|              | insecti |     |      | ivor |     |                |
|              | vores** |     |      | es** |     |                |
+--------------+---------+-----+------+------+-----+----------------+
|              | 15 g    | 35  | 1000 | 15 g | 35  | 1000 g         |
|              |         | g   | g    |      | g   |                |
+--------------+---------+-----+------+------+-----+----------------+
| Short Grass  | 121     | 84  | 19   |      |     |                |
+--------------+---------+-----+------+------+-----+----------------+
| Tall Grass   | 51      | 36  | 8    |      |     |                |
+--------------+---------+-----+------+------+-----+----------------+
| Broa         | 64      | 45  | 10   |      |     |                |
| dleafplants/ |         |     |      |      |     |                |
|              |         |     |      |      |     |                |
| > sm Insects |         |     |      |      |     |                |
+--------------+---------+-----+------+------+-----+----------------+
| Fruits       | 10      | 7   | 2    | 2    | 2   | 0              |
| /pods/seeds/ |         |     |      |      |     |                |
|              |         |     |      |      |     |                |
| > lg insects |         |     |      |      |     |                |
+--------------+---------+-----+------+------+-----+----------------+
|              |         |     |      |      |     |                |
+--------------+---------+-----+------+------+-----+----------------+
| **Dose-based | **15 g  |     | **35 |      |     | **1000 g       |
| RQs (daily   | m       |     | g    |      |     | mammal**       |
| dose/LD50 or | ammal** |     | mamm |      |     |                |
| NOAEL)**     |         |     | al** |      |     |                |
+--------------+---------+-----+------+------+-----+----------------+
|              |         |     |      |      |     |                |
+--------------+---------+-----+------+------+-----+----------------+
|              | Acute   | C   | A    | Chr  | Ac  | Chronic        |
|              |         | hro | cute | onic | ute |                |
|              |         | nic |      |      |     |                |
+--------------+---------+-----+------+------+-----+----------------+
| Short Grass  | 0.07    | 6   | 0.06 | 5.53 | 0   | 2.91           |
|              |         | .44 |      |      | .03 |                |
+--------------+---------+-----+------+------+-----+----------------+
| Tall Grass   | 0.03    | 2   | 0.02 | 2.34 | 0   | 1.23           |
|              |         | .73 |      |      | .01 |                |
+--------------+---------+-----+------+------+-----+----------------+
| Broadleaf    | 0.04    | 3   | 0.03 | 2.93 | 0   | 1.54           |
| plants/sm    |         | .41 |      |      | .02 |                |
| insects      |         |     |      |      |     |                |
+--------------+---------+-----+------+------+-----+----------------+
| Fr           | 0.01    | 0   | 0    | 0.46 | 0   | 0.24           |
| uits/pods/lg |         | .53 |      |      | .00 |                |
| insects      |         |     |      |      |     |                |
+--------------+---------+-----+------+------+-----+----------------+
| Seeds        | 0.00    | 0   | 0    | 0.1  | 0   | 0.08           |
| (granivore)  |         | .12 |      |      | .00 |                |
+--------------+---------+-----+------+------+-----+----------------+
|              |         |     |      |      |     |                |
+--------------+---------+-----+------+------+-----+----------------+

APPENDIX D: TerrPlant and AgDrift Model and Results

TERRPLANT MODEL Version 1.0

Terrestrial plant exposure characterization employs runoff and spray
drift scenarios contained in OPP's Terrplant model. Exposure
calculations are based on a pesticide's water solubility and the amount
of pesticide present on the surface soil within the first inch of depth.
For dry areas, the loading of pesticide active ingredient or acid
equivalent from runoff to an adjacent non-target area is assumed to
occur from one acre of treatment to one acre of non-target area. For
terrestrial plants inhabiting semi-aquatic (wetland) areas, runoff is
considered to occur from a larger source area with active ingredient
loading originating from 10 acres of treated area to a single acre of
non-target wetland. Default spray drift assumptions are 1% for ground
applications and 5% for aerial, forced air (i.e., air pressure within a
spray tank that forces the spray liquid through the boom nozzles), and
chemigation applications. Predicted EECs resulting from spray drift and
aerial applications are derived for non-granular applications only.

<table>
<colgroup>
<col style="width: 12%" />
<col style="width: 5%" />
<col style="width: 1%" />
<col style="width: 8%" />
<col style="width: 8%" />
<col style="width: 7%" />
<col style="width: 8%" />
<col style="width: 0%" />
<col style="width: 6%" />
<col style="width: 6%" />
<col style="width: 7%" />
<col style="width: 7%" />
<col style="width: 9%" />
<col style="width: 9%" />
</colgroup>
<tbody>
<tr class="odd">
<td colspan="7"><strong>Terrestrial Plant EECs and Acute Non Endangered
RQs (8/8/01; version 1.0))</strong></td>
<td></td>
<td></td>
<td colspan="2"><strong>Chemical: MCPB</strong></td>
<td></td>
<td></td>
<td></td>
</tr>
<tr class="even">
<td colspan="3"><strong>Input Values</strong></td>
<td></td>
<td></td>
<td></td>
<td rowspan="3"></td>
<td rowspan="2"></td>
<td rowspan="2"></td>
<td rowspan="3"></td>
<td></td>
<td></td>
<td></td>
<td></td>
</tr>
<tr class="odd">
<td><p><strong>Application Rate</strong></p>
<p><strong>(lb a.e./acre)</strong></p></td>
<td><strong>1.5</strong></td>
<td></td>
<td colspan="3"><p><strong>Estimated Environmental Concentrations (EECs)
for NON-GRANULAR formulation applications</strong></p>
<blockquote>
<p><strong>(lbs a.i./acre)</strong></p>
</blockquote></td>
<td colspan="4"><strong>Risk Quotients (RQs) for NON-GRANULAR
formulation applications</strong></td>
</tr>
<tr class="even">
<td><strong>Runoff Value (0.01, 0.02, or 0.05 if chemical solubility
&lt;10, 10-100, or &gt;100 ppm, respectively)</strong></td>
<td><strong>0.05</strong></td>
<td></td>
<td><strong>Application Method</strong></td>
<td><strong>Total Loading to Adjacent Areas (EEC = Sheet Runoff
+Drift)</strong></td>
<td><strong>Total Loading to Semi-aquatic Areas (EEC = Channelized
Runoff + Drift)</strong></td>
<td colspan="2"><strong>DRIFT EEC (for ground: application rate x 0.01)
(for aerial: application rate x 0.05)</strong></td>
<td colspan="2"><strong>Emergence RQs, Adjacent Areas RQ = EEC/Seedling
Emergence EC25</strong></td>
<td colspan="2"><p><strong>Emergence RQs, Semi-aquatic
Areas</strong></p>
<p><strong>RQ = EEC/Seedling Emergence EC25</strong></p></td>
</tr>
<tr class="odd">
<td><strong>Minimum Incorporation Depth (inches)</strong></td>
<td><strong>0</strong></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td><strong>Monocot</strong></td>
<td><strong>Dicot</strong></td>
<td><strong>Monocot</strong></td>
<td><strong>Dicot</strong></td>
<td><strong>Monocot</strong></td>
<td><strong>Dicot</strong></td>
</tr>
<tr class="even">
<td></td>
<td></td>
<td></td>
<td><strong>Ground Unincorp.</strong></td>
<td><strong>0.0900</strong></td>
<td><strong>0.765</strong></td>
<td><strong>0.0150</strong></td>
<td></td>
<td><strong>4.50</strong></td>
<td><strong>5.63</strong></td>
<td><strong>38.25</strong></td>
<td><strong>47.81</strong></td>
<td><strong>0.94</strong></td>
<td><strong>10</strong></td>
</tr>
<tr class="odd">
<td><strong>Seed Emerg Monocot EC25 (lb a.e./acre)</strong></td>
<td><strong>0.02</strong></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
</tr>
<tr class="even">
<td><p><strong>Seed Emerg Dicot EC25</strong></p>
<p><strong>(lb a.e./acre)</strong></p></td>
<td><strong>0.016</strong></td>
<td></td>
<td><strong>Aerial, Airblast, Spray Chemigation</strong></td>
<td><strong>0.1200</strong></td>
<td><strong>0.525</strong></td>
<td><strong>0.0750</strong></td>
<td></td>
<td><strong>6</strong></td>
<td><strong>7.50</strong></td>
<td><strong>26.25</strong></td>
<td><strong>32.81</strong></td>
<td><strong>4.69</strong></td>
<td><strong>50</strong></td>
</tr>
<tr class="odd">
<td><p><strong>Veg Vigor Monocot EC25</strong></p>
<p><strong>(lb a.e./acre)</strong></p></td>
<td><strong>0.016</strong></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td rowspan="2"></td>
<td rowspan="2"></td>
<td rowspan="2"></td>
<td></td>
<td></td>
<td></td>
</tr>
<tr class="even">
<td><p><strong>Veg Vigor Dicot EC25</strong></p>
<p><strong>(lb a.e./acre)</strong></p></td>
<td><strong>0.002</strong></td>
<td></td>
<td></td>
<td colspan="4"></td>
<td colspan="3"></td>
</tr>
</tbody>
</table>

<table>
<colgroup>
<col style="width: 13%" />
<col style="width: 5%" />
<col style="width: 1%" />
<col style="width: 9%" />
<col style="width: 8%" />
<col style="width: 8%" />
<col style="width: 8%" />
<col style="width: 0%" />
<col style="width: 6%" />
<col style="width: 6%" />
<col style="width: 7%" />
<col style="width: 8%" />
<col style="width: 6%" />
<col style="width: 6%" />
</colgroup>
<tbody>
<tr class="odd">
<td colspan="6"><strong>Terrestrial Plant EECs and Acute Endangered RQs
(8/8/01; version 1.0)</strong></td>
<td></td>
<td></td>
<td></td>
<td colspan="2"><strong>Chemical:MCPB</strong></td>
<td></td>
<td></td>
<td></td>
</tr>
<tr class="even">
<td></td>
<td colspan="2"><strong>Input Values</strong></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td rowspan="3"></td>
<td rowspan="2"></td>
<td rowspan="2"></td>
<td rowspan="3"></td>
<td></td>
<td></td>
<td></td>
</tr>
<tr class="odd">
<td><strong>Application Rate (lb a.e./acre)</strong></td>
<td><strong>1.5</strong></td>
<td></td>
<td colspan="4"><strong>Estimated Environmental Concentrations (EECs)
for NON-GRANULAR formulation applications (lbs a.i./acre)</strong></td>
<td colspan="3"><strong>Risk Quotients (RQs) for NON-GRANULAR
formulation applications</strong></td>
</tr>
<tr class="even">
<td><p><strong>Runoff Value</strong></p>
<p><strong>(0.01, 0.02, or 0.05 if chemical solubility &lt;10, 10-100,
or &gt;100 ppm, respectively)</strong></p></td>
<td><strong>0.05</strong></td>
<td></td>
<td><p><strong>Application</strong></p>
<p><strong>Method</strong></p></td>
<td><strong>Total Loading to Adjacent Areas (EEC = Sheet Runoff +
Drift)</strong></td>
<td><strong>Total Loading to Semi-aquatic Areas (EEC = (Channelized
Runoff + Drift)</strong></td>
<td><strong>DRIFT EEC (for ground: application rate x 0.01) (for aerial:
application rate x 0.05)</strong></td>
<td colspan="2"><strong>Emergence RQs, Adjacent Areas RQ = EEC/Seedling
Emergence EC05 or NOAEC</strong></td>
<td colspan="2"><p><strong>Emergence RQs, Semi-aquatic
areas</strong></p>
<p><strong>RQ = EEC/Seedling Emergence EC05 or NOAEC</strong></p></td>
<td><p><strong>Drift Rqs</strong></p>
<p><strong>RQ = EEC/Vegetative Vigor EC05 or NOAEC</strong></p></td>
</tr>
<tr class="odd">
<td><strong>Minimum Incorporation Depth (inches)</strong></td>
<td><strong>0</strong></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td><strong>Monocot</strong></td>
<td><strong>Dicot</strong></td>
<td><strong>Monocot</strong></td>
<td><strong>Dicot</strong></td>
<td><strong>Monocot</strong></td>
<td><strong>Dicot</strong></td>
</tr>
<tr class="even">
<td></td>
<td></td>
<td></td>
<td><strong>Ground Unincorp.</strong></td>
<td><strong>0.0900</strong></td>
<td><strong>0.7650</strong></td>
<td><strong>0.0150</strong></td>
<td></td>
<td><strong>9.00</strong></td>
<td><strong>9.00</strong></td>
<td><strong>76.50</strong></td>
<td><strong>76.50</strong></td>
<td></td>
<td></td>
</tr>
<tr class="odd">
<td><p><strong>Seed Emerg Monocot EC05 or NOAEC</strong></p>
<p><strong>(lb a.e./acre)</strong></p></td>
<td><strong>0.01</strong></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
</tr>
<tr class="even">
<td><p><strong>Seed Emerg Dicot EC05 or NOAEC</strong></p>
<p><strong>(lb a.e./acre)</strong></p></td>
<td><strong>0.01</strong></td>
<td></td>
<td><strong>Aerial, Airblast, Spray Chemigation</strong></td>
<td><strong>0.1200</strong></td>
<td><strong>0.5250</strong></td>
<td><strong>0.0750</strong></td>
<td></td>
<td><strong>12.00</strong></td>
<td><strong>12.00</strong></td>
<td><strong>52.50</strong></td>
<td><strong>52.50</strong></td>
<td></td>
<td></td>
</tr>
<tr class="odd">
<td><strong>Veg Vigor Monocot EC05 or NOAEC (lbs a../acre)</strong></td>
<td><strong>---------</strong></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td rowspan="2"></td>
<td rowspan="2"></td>
<td rowspan="2"></td>
<td></td>
<td></td>
<td></td>
</tr>
<tr class="even">
<td><p><strong>Veg Vigor Dicot EC05 or NOAEC</strong></p>
<p><strong>(lb a.e./acre)</strong></p></td>
<td><strong>---------</strong></td>
<td></td>
<td></td>
<td colspan="4"></td>
<td colspan="3"></td>
</tr>
</tbody>
</table>

**AGDRIFT Model (Version 2.01)**

The AgDRIFT model (Version 2.01) was used to refine the spray drift
exposure estimate for terrestrial plants. Downwind spray drift buffers
were developed for possible use in mitigating risks for endangered
terrestrial plants that grow in close proximity to agricultural and
non-agricultural fields that may be treated with liquid spray
applications of MCPB. The model was used to estimate spray buffer
distances for ground and aerial application to reach the NOAEC and
EC~25~ doses for the most sensitive monocot and dicot species in the
seedling emergence and the vegetative vigor studies. The standard
toxicity level EFED uses for calculating risk quotients for
non-endangered terrestrial plants is the EC~25~. For endangered plants,
the NOAEC (or EC~05~ if a NOAEC value is not available) is used.
Seedling emergence endpoints are representative of exposure through soil
to germinating plants, while vegetative vigor endpoints are
representative of foliar exposure. The terrestrial plant measurement
endpoints used in the model are specified in Table D- 1.

**[Aerial Application]{.underline}**

The most important factors affecting drift from aerial applications are
spray droplet size, release height, and wind speed. The aerial part of
the AgDRIFT model predicts mean dissipation distances based on the
inputs provided.

For aerial applications, the model contains three tiers of increasing
complexity.

However, only Tier 1 Aerial Model was used to estimate spray buffer
distances for an initial screening .

**[Tier I Aerial Modeling]{.underline}**

The AgDRIFT Tier I model for aerial application limits the input
parameters to droplet size only. The output of the Tier I AgDRIFT model
provides distances required to dissipate spray drift to the NOAEC and
EC~25~ levels.

> An analysis of the results indicates exceedance of the Acute Risk LOC
> for non-endangered monocots and dicots located adjacent to treated
> areas, in semi-aquatic areas, and as a result of spray drift.. The
> Endangered Species LOC was exceeded for monocots and dicots located in
> dryland and semi-aquatic areas adjacent to treated areas and for
> dicots as a result of spray drift.
>
> In spite of the uncertainty in the magnitude of the EC~25~ values used
> to calculate the RQs for MCPB, other data in the vegetative vigor
> studies indicate the potential for risk to non-target dicots from
> spray drift alone. Using the spray drift model AgDrift, the distances
> were calculated at which exposure would be equivalent to the lowest
> application rates tested in the vegetative vigor study which led to
> adverse effects. This Tier 1 AgDrift assessment assumed a fine to
> medium droplet size spectrum, and an aerial application. Table D .2..
> shows these rates for each crop, the fraction of the applied, and the
> distance at which that deposition would occur.

Highly active herbicides, such as the growth regulators, present the
greatest drift hazard because extremely small amounts can cause severe
problems. Even if only a small surface area of the plant is exposed to
MCPB, or a seedling is exposed to MCPB as it breaks through the soil
surface, there is a possibility that the plant may be severely damaged
or die as a result. In the vegetative vigor test, effects observed
included mortality (one cucmber plant, two radish plants), leaf
necrosis, decreased plant size, leaf curl, and stem tumors. Such damage,
even if only minor, may be sufficient to prevent the plant from
competing successfully with other plants for resources and water.
However, since the vegetative vigor tests could not determine a
no-effect application rate for MCPB, the effectiveness of these buffers
to eliminate risk to plants cannot be evaluated.

  ------------------------------------------------------------------------------
  TABLE D.2. Input                                                  
  and Output                                                        
  Parameters                                                        
  AGDRIFT to                                                        
  Estimate Distance                                                 
  of Deposition of                                                  
  MCPB Equivalent                                                   
  to Rates Tested                                                   
  in Vegetative                                                     
  Vigor Study                                                       
  ----------------- ----------------- ----------------- ----------- ------------
  Crop              input parameter   input parameter   output      output
                    initial average   active rate lb    parameter   parameter
                    disposition (lb   ae/acre           fraction of Distance of
                    ae/acre)                            the applied Deposition

  Cabbage           0.08              1.5               0.0533      177

  Lettuce           0.039             1.5               0.026       361

  Soybean           0.17              1.5               0.1134      85

  Tomato            0.08              1.5               0.0533      177
  ------------------------------------------------------------------------------

**APPENDIX E: Ecological Effects Data**

Ecological Effects Data

71-1 Avian Acute Oral

Bobwhite Quail. MRID 42560801 (Acceptable). In a 14-day oral gavage
study, MCPB sodium was determined to be moderately toxic to bobwhite
quail with an LD~50~ of 282 mg ai/kg (95% confidence interval 241-330 mg
ai/kg). The NOEL was not determined due to abnormal effects at the
lowest test level. The study is scientifically sound and follows the
guideline protocols.

Study design:10 birds, five males and five females were assigned to each
treatment level, including the controls. Observations for mortality and
sublethal effects were made once a day for 14 days post dosing. Body
weights were measured at test initiation, and on days 3, 7, and 14.
Average estimated feed consumption was determined for each group for
days 0-3, 4-7, and 8-14.

Reported results: Bobwhite were exposed to six nominal concentrations of
MCPB: 0, 147, 215, 316, 464 and 681 mg ai/kg. There were 10 mortalities
(100%) at the 681 level, 9 at 464 level, 6 at 316 level, 2 at 215 level
and 1 at 147 level. Signs of toxicity were observed at all test groups.
Birds in the 681mg/kg group appeared lethargic, and exhibited dyspnea
(gasping), loss of righting reflex and diarrhea. Birds in the other
treatment groups exhibited lethargy and diarrhea. Gross necropsis were
performed on all 28 birds that died and all showed abnormalities such
as; white areas and or white film on the heart, liver, gizzard,
gallbladder, crop or intestines. Also clear fluid from the beak was
observed.

71-2 Avian Acute Dietary

Bobwhite Quail. MRID 42560802 (Acceptable). In an 8-day dietary study,
MCPB sodium was determined to be practically non-toxic to bobwhite quail
with an LC~50~ \>5000 ppm ai (nominal concentration). The NOEL was 1250
ppm ai (nominal concentration). The study is scientifically sound and
generally followed guideline protocols.

Study design: Ten birds were assigned to each treatment level, including
five vehicle control groups.

Reported Results: Bobwhite were exposed to five nominal concentrations
of MCPB-NA:312, 625, 1250, 2500 and 5000 ppm. There were no mortalities
at any test level or in control groups.There were no clinical signs of
toxicity at any test level. The gross necropsis revealed abnormal
findings in 2 birds. Three white spots were present on the liver of 1
bird in the 1250 ppm ai group and a dark red spot was found on the liver
at the 5000 ppm ai group.

Mallard. MRID 42560803 ( Acceptable). In an 8-day dietary study, MCPB
sodium was determined to be practically non-toxic to mallard ducklings
with an LC~50~ \>5000 ppm ai (nominal concentration). The NOEL was 1250
ppm ai (nominal concentration). The study is scientifically sound and
generally followed guideline protocols.

Study design: Ten birds were assigned to each treatment level, including
five vehicle control groups.

Reported Results: Mallard were exposed to five nominal concentrations of
MCPB-NA:312, 625, 1250, 2500 and 5000 ppm. There were no mortalities at
any test level or in control groups.There were no clinical signs of
toxicity at any test level. The gross necropsis revealed no abnormal
findings.

72-1 Freshwater Fish Acute

Rainbow Trout. MRID 42532608 (Acceptable). In a 96-hour flow-through
test, MCPB sodium was determined to be moderately toxic to rainbow trout
with an LC~50~ of 4.3 mg ai/L. The NOEC was determined to be 1.0 mg
ai/L. The study is scientifically sound and meets guideline protocols.

Study design: Six concentrations of chemical and dilution water control
were used, each with two replicates of ten fish. Observations for
mortality and sublethal effects were made daily throughout the exposure
period.

Reported results: The mean measured concentrations of MCPB NA were:
0(control), 8.0, 4.9, 2.8, 1.8, 1.0, and 0.60 mg ai/L. Sublethal effects
(eg. Loss of equilibrium and darkening) were observed in surviving fish
at the 4.9, 2.8, and 1.8 mg ai/L; there were no other abnormal effects
at any other test levels. There was 100% mortality at the 8.0 mg ai/L
level within 48 hours, 70% mortality at

4.9 mg ai/L level by 96 hours, and 5% at 2.8 mg ai/L at 96 hours.

Bluegill Sunfish. MRID 42532601 (Acceptable). In a 96-hour flow-through
test, MCPB sodium was determined to be slightly toxic to bluegill
sunfish with an LC~50~ of 14 mg ai/L. The NOEC was determined to be 8.9
mg ai/L. The study is scientifically sound and meets guideline
protocols.

Study design: Six concentrations of chemical and dilution water control
were used, each with two replicates of 10 fish. Observations for
mortality and sublethal effects were made daily throughout the exposure
period.

Reported results: The mean measured concentrations of MCPB NA were:
0(control), 29, 16, 8.9, 56.4, 3.5 and 2 mg ai/L. Sublethal effects (eg.
Loss of equilibrium and darkening) were observed in surviving fish at
the 16 mg ai/L level; There were no other sublethal abnormal effects at
any other test levels. There was 100% mortality at the 25 mg ai/L within
72 hours, and 75% mortality at the 16 mg ai /L level by 96 hours. There
was a single mortality at the 3.5 mg ai/L level, but this was not
considered treatment related as there were no mortalities at the next
highest level (8.9 mgai/L).

72-2 Freshwater Invertebrate Acute

Daphnia. MRID 42532602 (Acceptable). In a 48-hour flow-through test,
MCPB sodium was determined to be slightly toxic to daphnids with an
EC~50~ of 55 mg ai/L (95% confidence interval of 49 - 63 mg ai/L). The
NOEC was determined to be 20 mg ai/L. The study is scientifically sound
and meets guideline protocols.

Study design: Five concentrations of chemical and dilution water control
were used, each with two replicates of 20 daphnids. Observations for
mortality and sublethal effects were made daily throughout the exposure
period.

Reported results: The mean measured concentrations of MCPB NA were:
0(control), 87, 51, 33, 20, and 12 mg ai/L. Sublethal effects (e.g.
lethargy an carapace) were observed in all surviving daphnids at 87 and
51 mg ai/L, and in 15% of the daphnids at 33 mg ai/L. There was 95%
mortality at the 87 mg ai/L and 45% mortality at 51 mg ai/L by the end
of the test period.

81-1 Acute Mammalian Oral

Rat. MRID 144801 (Acceptable). In an acute oral study, MCPB acid was
determined to have a low toxicity (Toxicity Category III) to rats with
LD~50~\'s of 4.7 (3.8 - 6.0) g/kg for males and females combined. The
study is scientifically sound and meets guideline protocols.

Rat. MRID 116340 (Acceptable). In an acute oral study, MCPB acid was
determined to have a low toxicity

(Toxicity Category III) to rats with LD~50~\'s of 1570 (912 - 2700)
mg/kg in males and 1700 (969 - 2981) mg/kg in females. The study is
scientifically sound and meets guideline protocols.

82-1 Mammalian Chronic

Dog. MRID 116345 (Supplemental). In a 90-day feeding study, MCPB acid
was determined to produce reproductive effects (testicular and prostate
atrophy; curtailment of spermatogenic activitiy) in dogs with a LOEL of
1600 ppm and the NOEL of 480 ppm. This study was considered supplemental
because little data was provided on the concentration and stability of
the test material in the diet and the pathological examination was
insufficient.

Dog. MRID 42883603 (Acceptable). In a 13-week feeding study, MCPB acid
was determined to produce sublethal and reproductive effects (reduced
testes weights; physiological changes in clinical chemistry) in dogs
with a LOAEL of 44 mg/kg/day and a NOAEL of 25 mg/kg/day. The study is
scientifically sound and meets the guideline protocols.

Rat. MRID 42883602 (Acceptable). In a 13-week feeding study, MCPB acid
did not produce any toxicologically significant effects to rat;
consequently, the NOAEL was determined to be 158 mg/kg/day, the highest
dose tested. The study is scientifically sound and meets the guideline
protocols.

83-3 Mammalian Developmental

Rat. MRID 40865402 (Acceptable). In a developmental toxicity study, MCPB
acid produced maternal toxicity and developmental toxicity in Sprague
Dawley rats at 100 mg ai/kg/day (LOAEL). The NOAEL for both was 25 mg
ai/kg/day. The study is scientifically sound and meets guideline
protocols.

Rabbit. MRID 40865401 (Acceptable). In a developmental toxicity study,
MCPB acid produced maternal toxicity (death) at 20 mg ai/kg/day (LOAEL)
in New Zealand white rabbits. The NOAEL for maternal toxicity was 5 mg
ai/kg/day the NOAEL for developmental toxicity was 20 mg ai/kg/day. The
study is scientifically sound and meets guideline protocols.

83-4 Mammalian Reproduction - MCPA

Rat. MRID 40041701 (Acceptable). In a 2-generation reproduction study,
MCPA acid produced maternal and offspring toxicity at 22.5 mg ai/kg/day
(LOAEL) in Crl:CD (SD) rats. The NOAEL for maternal and offspring
toxicity was 7.5 mg ai/kg/day. There were no treatment-related
developmental effects to the fetuses. The study is scientifically sound
and meets guideline protocols.

122-1(b) Vegetative Vigor - Tier I

Corn and Oats. MRID 42560804 (Acceptable). In a Tier I vegetative vigor
test, corn and oats had \<25% detrimental effects. The NOECs for the
corn and oats were 1.5 lb ai/acre and 1.3 lb ai/acre, respectively. The
study is scientifically sound and meets the guideline protocols.

122-2 Aquatic Plant Algae

Blue-green algae. MRID 42532603 (Acceptable). In a Tier I toxicity test
with blue-green algae, the EC~50~ for cell density was \>2.1 mg ai/L.
Tier II testing was not required for this species because the NOEC
exceeded the maximum label rate of 1.5 lb ai/acre. The study is
scientifically sound and meets the guideline protocols.

Green algae. MRID 42532605 (Acceptable). In a Tier I toxicity test with
green algae, the 120-hour EC~50~ for cell density was 0.42 mg ai/L. The
study is scientifically sound and meets the guideline protocols.

Marine diatom. MRID 42532606 (Acceptable). In a Tier I and II toxicity
test with the marine diatom, the 120-hour EC~50~ for cell density was
1.5 mg ai/L. The study is scientifically sound and meets the guideline
protocols.

Diatom. MRID 42532609 (Acceptable). In a Tier I and II toxicity test
with the diatom, the 120-hour EC~50~ for cell density was 0.71 mg ai/L
with a 95% confidence limit of (0.11 - 4.6), The NOEC was .048mg ai/L.
The study is scientifically sound and meets the guideline protocols

123-1(a) Seedling Emergence - Tier II

Monocots (5 species) and Dicots (5 species). MRID 42560804 (Acceptable).
In a Tier II seedling emergence study, mortality and morphological
abnormalities were observed in all species tested (cabbage, corn,
cucumber, lettuce, oats, onion, ryegrass, radish, soybean, and tomato)
with shoot length being the most sensitive parameter tested and cabbage
the most sensitive species (EC~25~ 0.017 lb ai/acre, NOEC 0.012 lb
ai/acre). The study is scientifically sound and meets guideline
protocols.

123-1(b) Vegetative Vigor - Tier II

Monocots (3 species) and Dicots (5 species). MRID 42560804 (Acceptable).
In a Tier II vegetative vigor study, mortality and morphological
abnormalities were observed in all species tested (cabbage, cucumber,
lettuce, onion, ryegrass, radish, soybean, and tomato) with shoot weight
being the most sensitive parameter tested and tomato the most sensitive
species (EC~25~ 0.0017 lb ai/L). There is uncertainty in the vegetative
vigor EC~25~ values for dicots, because they were extrapolated below the
lowest dose tested in the study. Furthermore, the NOEC values reported
in the original study were reported as being higher than the EC~25~
values. Further extrapolation of the data needs to be done to derive
EC~05~ values from the dose response curves for the vegetative vigor
study. The study is scientifically sound and meets guideline protocols.

123-2 Aquatic Plant Acute

Duckweed. MRID 42532604 (Acceptable). In a 14-day toxicity test with
duckweed, the EC~50~ for frond production was 0.23 mg ai/L and the
EC~50~ for frond biomass was 1.7 mg ai/L. The study is scientifically
sound and meets guideline protocols.

141-1 Acute Honey Bee Contact

Honey Bee. MRID 42532607 (Acceptable). In a 48-hour acute contact study
with the honey bee, the LD~50~ was \>25 µg/bee classifies MCPB as
relatively non- toxic to honey bees. . The study is scientifically sound
and meets guideline protocols.

Design and Dose: Three replicates of 25 bees each were used for each
treatment and the controls.

One treatment level ( 25 µg/bee) was used.

Reported results: There was 15% mortality (11) bees in the treated bees
after 48 hours. No other significant effects were reported.

APPENDIX F: Data Requirements

Appendix F: Data Requirement Tables for MCPB

+-------+-------------------+--------+------------+------------------+
| TABLE |                   |        |            |                  |
| of    |                   |        |            |                  |
| Env   |                   |        |            |                  |
| ironm |                   |        |            |                  |
| ental |                   |        |            |                  |
| Fate  |                   |        |            |                  |
| Data  |                   |        |            |                  |
| Re    |                   |        |            |                  |
| quire |                   |        |            |                  |
| ments |                   |        |            |                  |
+=======+===================+========+============+==================+
| Guide | Data Requirement  | MRID   | Study      | Is more data     |
| -line |                   | \#     | Clas       | needed?          |
| \#    |                   |        | sification |                  |
+-------+-------------------+--------+------------+------------------+
| 161-1 | Hydrolysis        | 42     | Acceptable | no               |
|       |                   | 574301 |            |                  |
+-------+-------------------+--------+------------+------------------+
| 161-2 | Photodegradation  | 42     | Acceptable | no               |
|       | in Water          | 574302 |            |                  |
+-------+-------------------+--------+------------+------------------+
| 161-3 | Photodegradation  | 43     | Invalid    | no               |
|       | on Soil           | 829901 |            |                  |
+-------+-------------------+--------+------------+------------------+
| 161-4 | Photodegradation  | N/A    |            | no               |
|       | in Air            |        |            |                  |
+-------+-------------------+--------+------------+------------------+
| 162-1 | Aerobic Soil      | 43     | Acceptable | no               |
|       | Metabolism        | 247601 |            |                  |
+-------+-------------------+--------+------------+------------------+
| 162-2 | Anaerobic Soil    | 43     | Acceptable | no               |
|       | Metabolism        | 015501 |            |                  |
+-------+-------------------+--------+------------+------------------+
| 162-3 | Anaerobic Aquatic | No     |            | no               |
|       | Metabolism        | study  |            |                  |
|       |                   | sub    |            |                  |
|       |                   | mitted |            |                  |
+-------+-------------------+--------+------------+------------------+
| 162-4 | Aerobic Aquatic   | No     |            | (not at this     |
|       | Metabolism        | study  |            | time)            |
|       |                   | sub    |            |                  |
|       |                   | mitted |            |                  |
+-------+-------------------+--------+------------+------------------+
| 163-1 | Leaching-Adso     | 42     | Acceptable | no               |
|       | rption/Desorption | 693701 |            |                  |
|       |                   |        |            |                  |
|       |                   | 43     |            |                  |
|       |                   | 466401 |            |                  |
+-------+-------------------+--------+------------+------------------+
| 163-2 | Laboratory        | N/A    |            |                  |
|       | Volatility        |        |            |                  |
+-------+-------------------+--------+------------+------------------+
| 163-3 | Field Volatility  | N/A    |            |                  |
+-------+-------------------+--------+------------+------------------+
| 164-1 | Terrestrial Field | No     |            | yes              |
|       | Dissipation       | study  |            |                  |
|       |                   | sub    |            |                  |
|       |                   | mitted |            |                  |
+-------+-------------------+--------+------------+------------------+
| 164-2 | Aquatic Field     | N/A    |            |                  |
|       | Dissipation       |        |            |                  |
+-------+-------------------+--------+------------+------------------+
| 164-3 | Forestry          | N/A    |            |                  |
|       | Dissipation       |        |            |                  |
+-------+-------------------+--------+------------+------------------+
| 165-4 | Accumulation in   | N/A    |            |                  |
|       | Fish              |        |            |                  |
+-------+-------------------+--------+------------+------------------+
| 165-5 | Accumulation-     | N/A    |            |                  |
|       | aquatic           |        |            |                  |
|       | non-target        |        |            |                  |
+-------+-------------------+--------+------------+------------------+
| 166-1 | Ground Water-     | N/A    |            |                  |
|       | small prospective |        |            |                  |
+-------+-------------------+--------+------------+------------------+
| 166-2 | Groundwater -     | N/A    |            |                  |
|       | small             |        |            |                  |
|       | retrospective     |        |            |                  |
+-------+-------------------+--------+------------+------------------+
| 201-1 | Droplet Size      | N/A    |            |                  |
|       | Spectrum          |        |            |                  |
+-------+-------------------+--------+------------+------------------+
| 202-1 | Drift Field       | N/A    |            |                  |
|       | Evaluation        |        |            |                  |
+-------+-------------------+--------+------------+------------------+

+-------+-------------------+-----------+----------+------------------+
| TABLE |                   |           |          |                  |
| of    |                   |           |          |                  |
| Ecolo |                   |           |          |                  |
| gical |                   |           |          |                  |
| Tox   |                   |           |          |                  |
| icity |                   |           |          |                  |
| Data  |                   |           |          |                  |
| Re    |                   |           |          |                  |
| quire |                   |           |          |                  |
| ments |                   |           |          |                  |
+-------+-------------------+-----------+----------+------------------+
| *     | **Data            | **MRID    | **       | **Is more data   |
| *Guid | Requirement**     | \#**      | Classifi | needed?**        |
| eline |                   |           | cation** |                  |
| \#**  |                   |           |          |                  |
+-------+-------------------+-----------+----------+------------------+
| 71-1  | Avian acute oral  | 42560801  | Ac       | No               |
|       | LD~50~            |           | ceptable |                  |
|       |                   |           |          |                  |
|       | (bobwhite quail)  |           |          |                  |
+-------+-------------------+-----------+----------+------------------+
| 71-2  | Avian acute       | 42560802  | Ac       | No               |
|       | dietary LC~50~    |           | ceptable |                  |
|       |                   | 42560803  |          |                  |
|       | (bobwhite quail)  |           | Ac       |                  |
|       |                   |           | ceptable |                  |
|       | (mallard duck)    |           |          |                  |
+-------+-------------------+-----------+----------+------------------+
| 71-4  | Avian             | 43505201  | Ac       | No               |
|       | reproduction      | (MCPA)    | ceptable |                  |
|       |                   |           |          |                  |
|       | (bobwhite quail)  |           |          |                  |
|       |                   |           |          |                  |
|       | (mallard duck)    |           |          |                  |
+-------+-------------------+-----------+----------+------------------+
| 72-1  | Freshwater fish   | 42532608  | Ac       | No               |
|       | acute LC~500~     | 42532601  | ceptable |                  |
|       |                   |           |          |                  |
|       | (rainbow trout)   |           | Ac       |                  |
|       |                   |           | ceptable |                  |
|       | (bluegill         |           |          |                  |
|       | sunfish)          |           |          |                  |
+-------+-------------------+-----------+----------+------------------+
| 72-2  | Freshwater        | 42532602  | Ac       | No               |
|       | invertebrate      |           | ceptable |                  |
|       | acute EC~50~      |           |          |                  |
|       | (daphnia)         |           |          |                  |
+-------+-------------------+-----------+----------+------------------+
| 72-3a | Estuarine/marine  | N/A       |          | Yes              |
|       | fish acute LC~50~ |           |          |                  |
|       | (sheepshead       |           |          |                  |
|       | minnow)           |           |          |                  |
+-------+-------------------+-----------+----------+------------------+
| 72-3b | Estuarine/marine  | N/A       |          | Yes              |
|       | invertebrate      |           |          |                  |
|       | acute EC~50~      |           |          |                  |
|       |                   |           |          |                  |
|       | (eastern oyster)  |           |          |                  |
+-------+-------------------+-----------+----------+------------------+
| 72-4a | Estuarine marine  | N/A       |          | Reserved         |
|       | fish early life   |           |          |                  |
|       | stage             |           |          |                  |
+-------+-------------------+-----------+----------+------------------+
| 72-4a | Freshwater fish   | N/A       |          | Yes              |
|       | early life stage  |           |          |                  |
|       |                   |           |          |                  |
|       | (fathead minnow)  |           |          |                  |
+-------+-------------------+-----------+----------+------------------+
| 72-4b | Freshwater        | N/A       |          | Yes              |
|       | invertebrate life |           |          |                  |
|       | cycle (daphnia)   |           |          |                  |
+-------+-------------------+-----------+----------+------------------+
| 72-4d | Estuarine/marine  | N/A       |          | Reserved         |
|       | life cycle        |           |          |                  |
|       |                   |           |          |                  |
|       | (mysid)           |           |          |                  |
+-------+-------------------+-----------+----------+------------------+
| 72-5  | Freshwater fish   | N/A       |          | Reserved         |
|       | full life cycle   |           |          |                  |
+-------+-------------------+-----------+----------+------------------+
| 72-7  | Aquatic Field     | N/A       |          | No               |
|       | Study             |           |          |                  |
+-------+-------------------+-----------+----------+------------------+
| 81-1  | Acute mammalian   | 144801    | Ac       | No               |
|       | oral LD~50~       |           | ceptable |                  |
|       |                   | 116340    |          |                  |
|       | (rat)             |           |          |                  |
+-------+-------------------+-----------+----------+------------------+
| 82    | Mammalian chronic | 1.        | Ac       | No               |
| -1(a) |                   | 16345e+11 | ceptable |                  |
|       | (dog)             |           | -minimum |                  |
| 82    |                   |           |          |                  |
| -1(b) | (rat)             |           | Ac       |                  |
|       |                   |           | ceptable |                  |
|       |                   |           | -minimum |                  |
+-------+-------------------+-----------+----------+------------------+
| 83    | Mammalian Chronic | N/A       |          | Reserved         |
| -1(a) |                   |           |          |                  |
|       |                   |           |          |                  |
| 83    |                   |           |          |                  |
| -1(b) |                   |           |          |                  |
+-------+-------------------+-----------+----------+------------------+
| 83-3  | Mammalian         | 408654    | Ac       | No               |
|       | Developmental     |           | ceptable |                  |
|       |                   |           |          |                  |
|       | (rat)             |           | Ac       |                  |
|       |                   |           | ceptable |                  |
|       | (rabbit)          |           |          |                  |
+-------+-------------------+-----------+----------+------------------+
| 83-4  | Mammalian         | N/A       |          | Yes              |
|       | Reproduction      |           |          |                  |
| MCPB  |                   |           |          |                  |
+-------+-------------------+-----------+----------+------------------+
| 83-4  | Mammalian         | 40041701  | Ac       | No               |
|       | Reproduction      |           | ceptable |                  |
| MPCA  |                   |           |          |                  |
+-------+-------------------+-----------+----------+------------------+
| 123   | Seedling          | 42560804  | Ac       | No               |
| -1(a) | Emergence - Tier  |           | ceptable |                  |
|       | II                |           |          |                  |
+-------+-------------------+-----------+----------+------------------+
| 122   | Vegetative        | 42560804  | Ac       | No               |
| -1(b) | Vigor - Tier I    |           | ceptable |                  |
+-------+-------------------+-----------+----------+------------------+
| 123   | Vegetative        | 42560804  | Ac       | No               |
| -1(b) | Vigor - Tier II   |           | ceptable |                  |
+-------+-------------------+-----------+----------+------------------+
| 122-2 | Aquatic plant     | 42532605  | Ac       | No               |
|       | algae             |           | ceptable |                  |
|       |                   | 42532603  |          |                  |
|       | (green algae)     |           | Ac       |                  |
|       |                   | 42532609  | ceptable |                  |
|       | (blue-green       | 42532606  |          |                  |
|       | algae)            |           | Ac       |                  |
|       |                   |           | ceptable |                  |
|       | (diatom)          |           |          |                  |
|       |                   |           | Ac       |                  |
|       | (marine diatom)   |           | ceptable |                  |
+-------+-------------------+-----------+----------+------------------+
| 123-2 | Aquatic plant     | 42532604  | Ac       | No               |
|       | acute EC~50~      |           | ceptable |                  |
|       |                   |           |          |                  |
|       | (duckweed)        |           |          |                  |
+-------+-------------------+-----------+----------+------------------+
| 141-1 | Acute honey bee   | 42532607  | Ac       | No               |
|       | contact LD~50~    |           | ceptable |                  |
+-------+-------------------+-----------+----------+------------------+
| 141-2 | Honey Bee Residue | N/A       |          | Yes              |
|       | on Foliage        |           |          |                  |
+-------+-------------------+-----------+----------+------------------+
| 141-5 | Honey Bee Field   | N/A       |          | Yes              |
|       | Testing for       |           |          |                  |
|       | Pollinator        |           |          |                  |
+-------+-------------------+-----------+----------+------------------+

APPENDIX G: Environmental Fate Bibliography

Environmental Fate Bibliography

Das, Y.T. 1992. Hydrolysis of \[^14^C\]MCPB in aqueous solutions
buffered at pH 5, 7 and 9. Unpublished study performed by Innovative
Scientific Services, Inc., Piscataway, NJ and sponsored by Rhône-Poulenc
Agrochemie, Lyon Cedex, France. ISSI Study Number 92010; Rhone-Poulenc
Study Number 92-06. September 23, 1992. MRID 42574301

Das, Y.T. 1992. Photodegradation of \[^14^C\]MCPB in aqueous solutions
buffered at pH 5, 7 and 9 under artificial sunlight. Unpublished study
performed by Innovative Scientific Services, Inc., Piscataway, NJ and
sponsored by Rhône-Poulenc Agrochemie, Lyon Cedex, France. ISSI Study
Number 92011; Rhone-Poulenc Study Number 92-07. September 23, 1992. MRID
42574302

Robson, M.M. 1993. Determination of adsorption/desorption
characteristics of 4-(2-methyl, 4-chlorophenoxy)butyric acid (MCPB) in
soil. Unpublished study performed by Hazleton UK, North Yorkshire,
England. HUK Study No. 68/127. Study sponsored by Rhône-Poulenc
Agriculture, Essex, England. February 10, 1993. MRID 42693701

Goodyear, A. 1993. (^14^C)-MCPB: anaerobic soil metabolism. Unpublished
study performed by Hazleton UK, North Yorkshire, England, and sponsored
by MCPB Task Force, c/o Rhône-Poulenc Agricultural Limited, Essex,
England. Laboratory Study No. 68/131 and Report No. 68/131-1015. MRID
43015501

Howard, P.H. and W.M. Meylan. 1997. Handbook of Physical Properties of
Organic Chemicals. Lewis Publishers, New York. p.121.

John, A., *et al*. 1994. MCPB: aerobic soil metabolism. Unpublished
study performed and sponsored by MCPB Task Force, c/o Rhône-Poulenc
Agricultural Limited, Essex, England. Laboratory Project and Study ID: P
93/194. MRID 43247601

John, A.E., M.K. Jones and P. Lowden. 1994. MCPB: Fresh and aged
leaching study in five soils. Laboratory Project ID. P 92/333.
Unpublished study performed and submitted by Rhône-Poulenc Agriculture
Limited, Essex, England. Laboratory Project ID: P 92/333. MRID 43466401

Ferreira, E. M., A. E. John, P. Lowden, and D. J. Austin. 1992. MCPB
soil photolysis study. Laboratory Project ID: P92/126. Unpublished study
performed and submitted by Rhône-Poulenc Agriculture Limited, Ongar,
Essex, England. MRID 43829901

Podall, H. 2002. CBI Product Chemistry Review. March 8, 2002.

Tomlin, C.D.S., ed. 1997. The Pesticide Manual - #65 MCPB Sodium Salt.
British Crop Protection Council, 11^th^ ed, Farnham, Surrey, UK. p. 254.

WSSA (Weed Science Society of America). 1994. Herbicide Handbook. Ahrens
W.H., Ed., Champaign, IL. p. 352.

**APPENDIX H: Ecotoxicity Bibliography**

**Ecotoxicity Bibliography**

Bettencourt, M.J. 1992. MCPB Sodium - Acute toxicity to rainbow trout
(*Oncorhynchus mykiss*) under flow-through conditions. Unpublished study
performed by Springborn Laboratories, Inc., Wareham, MA and sponsored by
Rhône-Poulenc Agrochemie, Research Triangle Park, NC. SLI Report Number
92-7-4228. MRID 42532608

Bettencourt, M.J. 1992. MCPB Sodium - Acute toxicity to bluegill sunfish
(*Lepomis macrochiru*s) under flow-through conditions. Unpublished study
performed by Springborn Laboratories, Inc., Wareham, MA and sponsored by
Rhône-Poulenc Agrochemie, Research Triangle Park, NC. SLI Report Number
92-8-4263. MRID 42532601

Christensen, K.P. 1992. MCPB Sodium - Determination of effects on seed
germination, seedling emergence and vegetative vigor of ten plant
species. Unpublished study performed by Springborn Laboratories, Inc.,
Wareham, MA and sponsored by Rhône-Poulenc Agrochemie, Research Triangle
Park, NC. Study Number HWA 656-172. July 14, 1993. MRID 42560804

Corley, J. and D.L. Kunkel. 1999. MCPB: Magnitude of the residue on pea
(reregistration). Unpublished study performed by Environmental
Toxicology Laboratory, University of California, Davis, CA and sponsored
by Rutgers University, North Brunswick, NJ. Study Number 05470.94-CAR23.
MRID 44754101

Dalgard, D.W. 1993. 13-Week dietary toxicity study with MCPB in dogs.
Unpublished study performed by Hazleton Washington, Inc., Vienna, VA and
sponsored by Rhône-Poulenc Agrochemie, Research Triangle Park, NC. SLI
Report Number 92-8-4263. MRID 42883603

Dexter, A.G., J.L. Gunsolus, and W.S. Curran. 1994. Herbicide Mode of
Action and Sugarbeet Injury Symptoms. North Dakota State University of
Agriculture and Applied Science, Fargo, ND.

Ferrell, J.A., G.E. MacDonald, B.J. Brecke, A.C. Bennett, and J.
Tredaway Ducar. 2005. Florida's Organo-Auxin Herbicide Rule - 2005.
University of Florida, Institute of Food and Agricultural Sciences,
Gainesville, FL.

Heimann, M.F. and R.C. Newman. 1997. Plant injury due to turfgrass
broadleaf weed herbicides. University of Wisconsin - Cooperative
Extension, Madison, WI.

Hoberg, J.R. 1992. MCPB Sodium - Toxicity to the freshwater blue-green
alga, *Anabaena flos-aquae*. Unpublished study performed by Springborn
Laboratories, Wareham, MA and sponsored by Rhône-Poulenc Agrochemie,
Research Triangle Park, NC. Study Number 10566.0392.6230.420. MRID
42532603

Hoberg, J.R. 1992. MCPB Sodium - Toxicity to the green alga,
*Selenastrum capricornutum*. Unpublished study performed by Springborn
Laboratories, Wareham, MA and sponsored by Rhône-Poulenc Agrochemie,
Research Triangle Park, NC. Study Report Number 92-8-4361. MRID 42532605

Hoberg, J.R. 1992. MCPB Sodium - Toxicity to the freshwater diatom,
*Navicula pelliculos*a Unpublished study performed by Springborn
Laboratories, Wareham, MA and sponsored by Rhône-Poulenc Agrochemie,
Research Triangle Park, NC. Study Number 10566.0392.6230.440. MRID
42532609

Hoberg, J.R. 1992. MCPB Sodium - Toxicity to the marine diatom,
*Skeletonema costatum*. Unpublished study performed by Springborn
Laboratories, Wareham, MA and sponsored by Rhône-Poulenc Agrochemie,
Research Triangle Park, NC. Study Report Number 92-8-4372. MRID 42532606

Hoberg, J.R. 1992. MCPB Sodium - Toxicity to the duckweed, *Lemna
gibba*. Unpublished study performed by Springborn Laboratories, Wareham,
MA and sponsored by Rhône-Poulenc Agrochemie, Research Triangle Park,
NC. Study Report Number 92-8-4368. MRID 42532604

Holsing, G. 1969. Acute Oral - Rats - MCPB Technical. Unpublished study
performed by TRW, Inc. and sponsored by Rhodia, Inc. Project Report
Number 517-102. MRID 116340

Kynoch, S. 1985. Acute oral toxicity to rats of MCPB Technical Acid.
Unpublished study performed by Huntingdon Research Center. MRID 144801

Lingenfelter, D.D. and N.L. Hartwig. 2003. Introduction to Weeds and
Herbicides. Penn State College of Agricultural Sciences - Agricultural
Research and Cooperative Extension. Pp. 1 - 20.

MacKenzie, K. 1986. Two-generation reproduction study with MCPA in rats.
Unpublished study performed by Hazleton Laboratories America, Inc.,
Madison, WI. Laboratory Study Number 6148-100. MRID 40041701

Maggi, V.L. 1992. Acute contact toxicity of MCPB sodium salt to honey
bees (*Apis mellifera*). Unpublished study performed by California
Agricultural Research, Inc., Kerman, CA and sponsored by Rhône-Poulenc
Agrochemie, Research Triangle Park, NC. Laboratory Study Number CAR
169-92. MRID 42532607

Pedersen, C.A. and B.R. Helsten. 1992. MCPB Sodium: 14-Day acute oral
LD~50~ study in bobwhite quail. Unpublished study performed by BioLife
Associates, Ltd., Neillsville, WI and sponsored by Rhône-Poulenc
Agrochemie, Research Triangle Park, NC. Study Number BLAL 108-016-03.
MRID 42560801

Pedersen, C.A. and B.R. Helsten. 1992. MCPB Sodium: 8-Day acute dietary
study in bobwhite quail. Unpublished study performed by BioLife
Associates, Ltd., Neillsville, WI and sponsored by Rhône-Poulenc
Agrochemie, Research Triangle Park, NC. Study Number BLAL 108-014-01.
MRID 42560802

Pedersen, C.A. and B.R. Helsten. 1992. MCPB Sodium: 8-Day acute dietary
study in mallard ducklings. Unpublished study performed by BioLife
Associates, Ltd., Neillsville, WI and sponsored by Rhône-Poulenc
Agrochemie, Research Triangle Park, NC. Study Number BLAL 108-015-04.
MRID 42560803

Putt, A.E. 1992. MCPB Sodium - Acute toxicity to daphnids (*Daphnia
magna*) under flow-through conditions. Unpublished study performed by
Springborn Laboratories, Wareham, MA and sponsored by Rhône-Poulenc
Agrochemie, Research Triangle Park, NC. Study Report Number 92-7-4351.
MRID 42532602

Trutter, J.A. 1993. 13-Week dietary toxicity study with MCPB in rats.
Unpublished study performed by Hazleton Washington, Inc., Vienna, VA and
sponsored by Rhône-Poulenc Agrochemie, Research Triangle Park, NC. Study
Number HWA 656-174. MRID 42883602

Tyl, R.W. 1988. Developmental toxicity evaluation of MCPB administered
by gavage to CD (Sprague Dawley) Rats. Unpublished study performed by
Bushy Run Research Center, Export, PA and sponsored by Rhône-Poulenc
Agrochemie, Research Triangle Park, NC. Study Report Number 51-532. MRID
40865402

Tyl, R.W. and T.L. Neeper-Bradley 1988. Developmental toxicity
evaluation of MCPB administered by gavage to New Zealand White Rabbits.
Unpublished study performed by Bushy Run Research Center, Export, PA and
sponsored by Rhône-Poulenc Agrochemie, Research Triangle Park, NC. Study
Report Number 51-547. MRID 40865401

**APPENDIX I: Locates Endangered Species**

Unique Taxa Count by State for Selected Crops

Reporting for \> 1 Acres

*Cowpeas and southern peas, dry (53), Peas, dry edible (55), Cowpeas and
southern peas,*

*green (78), Peas, green, excluding cowpeas (81), Peas, all (312)*

**Cowpeas and southern peas, dry**

Bird Fish Mammal Amphibian Crustacean Reptile Arachnids Insects Plant
Snails Clam

Affected Counties: 27 17 14 13 12 13 12 14 1 2

Affected States: 5 3 4 5 2 2 0 2 3 1 2

Affected Species: 15 11 10 4 5 4 5 33 1 6

**Cowpeas and southern peas, green**

Bird Fish Mammal Amphibian Crustacean Reptile Arachnids Insects Plant
Snails Clam

Affected Counties: 162 60 52 18 2 61 6 65 4 37

Affected States: 12 9 12 4 2 9 0 3 12 2 10

Affected Species: 16 17 8 4 2 12 2 56 4 31

**Peas, all**

Bird Fish Mammal Amphibian Crustacean Reptile Arachnids Insects Plant
Snails Clam

Affected Counties: 408 152 188 37 22 91 52 204 8 60

Affected States: 39 22 36 5 5 12 1 14 37 5 20

Affected Species: 48 39 38 10 11 21 1 27 350 10 37

**Peas, dry edible**

Bird Fish Mammal Amphibian Crustacean Reptile Arachnids Insects Plant
Snails Clam

Affected Counties: 64 28 13 3 9 2

Affected States: 7 6 6 2 0 0 0 0 4 1 0

Affected Species: 5 6 4 2 4 4

**Peas, green, excluding cowpeas**

Bird Fish Mammal Amphibian Crustacean Reptile Arachnids Insects Plant
Snails Clam

Thursday, June 09, 2005 Page 1 of 20

**Peas, green, excluding cowpeas**

Bird Fish Mammal Amphibian Crustacean Reptile Arachnids Insects Plant
Snails Clam

Affected Counties: 196 65 123 11 6 29 33 137 2 32

Affected States: 35 18 29 4 2 9 0 10 32 2 17

Affected Species: 21 19 23 5 4 13 19 130 3 24

Thursday, June 09, 2005 Page 2 of 20

**Grand Summary**

Bird Fish Mammal Amphibian Crustacean Reptile Arachnids Insects Plant
Snails Clam

**Total Counties:** 408 152 188 37 22 91 1 52 204 8 60

**Total States:** 39 22 36 5 5 12 1 14 37 5 20

**Unique Species**

**Totals:** 48 39 38 10 11 21 1 27 350 10 37

**Species Affected:**

FROG, MOUNTAIN YELLOW-LEGGED Rana muscosa Amphibian

TREEFROG, PINE BARRENS Hyla andersonii Amphibian

TOAD, HOUSTON Bufo houstonensis Amphibian

TOAD, ARROYO SOUTHWESTERN Bufo californicus (=microscaphus) Amphibian

FROG, CALIFORNIA RED-LEGGED Rana aurora draytonii Amphibian

SALAMANDER, CALIFORNIA TIGER Ambystoma californiense Amphibian

SALAMANDER, DESERT SLENDER Batrachoseps aridus Amphibian

SALAMANDER, FLATWOODS Ambystoma cingulatum Amphibian

SALAMANDER, SANTA CRUZ Ambystoma macrodactylum croceum Amphibian

LONG-TOED

SALAMANDER, RED HILLS Phaeognathus hubrichti Amphibian

SPIDER, KAUAI CAVE WOLF Adelocosa anops Arachnid

TERN, CALIFORNIA LEAST Sterna antillarum browni Bird

SPARROW, FLORIDA GRASSHOPPER Ammodramus savannarum floridanus Bird

SHEARWATER, NEWELL\'S Puffinus auricularis newelli Bird

TOWNSEND\'S

CAHOW Pterodroma cahow Bird

THRUSH, LARGE KAUAI Myadestes myadestinus Bird

CURLEW, ESKIMO Numenius borealis Bird

PLOVER, PIPING Charadrius melodus Bird

PLOVER, WESTERN SNOWY Charadrius alexandrinus nivosus Bird

CROW, HAWAIIAN (\'ALALA) Corvus hawaiiensis Bird

CREEPER, HAWAII Oreomystis mana Bird

CRANE, WHOOPING Grus americana Bird

CONDOR, CALIFORNIA Gymnogyps californianus Bird

TERN, INTERIOR (POPULATION) Sterna antillarum Bird

COOT, HAWAIIAN (=ALAE KEO Fulica americana alai Bird

HAWK, HAWAIIAN (IO) Buteo solitarius Bird

CARACARA, AUDUBON\'S CRESTED Polyborus plancus audubonii Bird

THRUSH, SMALL KAUAI (PUAIOHI) Myadestes palmeri Bird

Thursday, June 09, 2005 Page 3 of 20

RAIL, CALIFORNIA CLAPPER Rallus longirostris obsoletus Bird

RAIL, LIGHT-FOOTED CLAPPER Rallus longirostris levipes Bird

RAIL, YUMA CLAPPER Rallus longirostris yumanensis Bird

GNATCATCHER, COASTAL Polioptila californica californica Bird

CALIFORNIA

STORK, WOOD Mycteria americana Bird

STILT, HAWAIIAN (=AE\'O) Himantopus mexicanus knudseni Bird

GOOSE, HAWAIIAN (NENE) Branta (=Nesochen) sandvicensis Bird

TERN, ROSEATE Sterna dougallii dougallii Bird

KITE, EVERGLADE SNAIL Rostrhamus sociabilis plumbeus Bird

\'AKIA POLA\'AU (HEMIGNATHUS Hemignathus munroi Bird

MUNROI)

OWL, NORTHERN SPOTTED Strix occidentalis caurina Bird

PALILA Loxioides bailleui Bird

DUCK, HAWAIIAN (KOLOA) Anas wyvilliana Bird

VIREO, BLACK-CAPPED Vireo atricapilla Bird

VIREO, LEAST BELL\'S Vireo bellii pusillus Bird

PELICAN, BROWN Pelecanus occidentalis Bird

\'O\'U (HONEYCREEPER) Psittirostra psittacea Bird

PETREL, HAWAIIAN DARK-RUMPED Pterodroma phaeopygia sandwichensis Bird

OWL, MEXICAN SPOTTED Strix occidentalis lucida Bird

\'AKEPA, HAWAII Loxops coccineus coccineus Bird

\'AKIA LOA, KAUAI (HEMIGNATHUS Hemignathus procerus Bird

PROCERUS)

NUKU PU\'U Hemignathus lucidus Bird

FALCON, NORTHERN APLOMADO Falco femoralis septentrionalis Bird

WOODPECKER, RED-COCKADED Picoides borealis Bird

JAY, FLORIDA SCRUB Aphelocoma coerulescens Bird

\'O\'O, KAUAI (=\'A\'A) Moho braccatus Bird

WARBLER (WOOD), Dendroica chrysoparia Bird

GOLDEN-CHEEKED

EAGLE, BALD Haliaeetus leucocephalus Bird

MURRELET, MARBLED Brachyramphus marmoratus marmoratus Bird

FLYCATCHER, SOUTHWESTERN Empidonax traillii extimus Bird

WILLOW

MOORHEN, HAWAIIAN COMMON Gallinula chloropus sandvicensis Bird

MUSSEL, DWARF WEDGE Alasmidonta heterodon Clam

MUSSEL, SCALESHELL Leptodea leptodon Clam

RIFFLESHELL, NORTHERN Epioblasma torulosa rangiana Clam

STIRRUP SHELL Quadrula stapes Clam

COMBSHELL, SOUTHERN Epioblasma penita Clam

(=PENITENT MUSSEL)

Thursday, June 09, 2005 Page 4 of 20

MOCCASINSHELL, ALABAMA Medionidus acutissimus Clam

FANSHELL Cyprogenia stegaria Clam

FATMUCKET, ARKANSAS Lampsilis powelli Clam

MUSSEL, WINGED MAPLELEAF Quadrula fragosa Clam

KIDNEYSHELL, TRIANGULAR Ptychobranchus greeni Clam

SLABSHELL, CHIPOLA Elliptio chipolaensis Clam

SPINYMUSSEL, TAR RIVER Elliptio steinstansana Clam

ROCK-POCKETBOOK, OUACHITA Arkansia wheeleri Clam

(=WHEELER\'S PM)

PIGTOE, CUMBERLAND Pleurobema gibberum Clam

(=CUMBERLAND PIGTOE MUSSEL

PIGTOE, DARK Pleurobema furvum Clam

PIGTOE, FINE-RAYED Fusconaia cuneolus Clam

PIGTOE, FLAT (=MARSHALL\'S Pleurobema marshalli Clam

MUSSEL)

PIGTOE, HEAVY (=JUDGE TAIT\'S Pleurobema taitianum Clam

MUSSEL)

PIGTOE, OVAL Pleurobema pyriforme Clam

PIGTOE, ROUGH Pleurobema plenum Clam

CLUBSHELL, OVATE Pleurobema perovatum Clam

HEELSPLITTER, INFLATED Potamilus inflatus Clam

CLUBSHELL Pleurobema clava Clam

BANKCLIMBER, PURPLE Elliptoideus sloatianus Clam

PIGTOE, SOUTHERN Pleurobema georgianum Clam

THREERIDGE, FAT Amblema neislerii Clam

PEARLYMUSSEL, PINK MUCKET Lampsilis abrupta Clam

PEARLYMUSSEL, ORANGE-FOOTED Plethobasus cooperianus Clam

PEARLYMUSSEL, HIGGINS\' EYE Lampsilis higginsii Clam

POCKETBOOK, FAT Potamilus capax Clam

POCKETBOOK, FINE-LINED Lampsilis altilis Clam

POCKETBOOK, SHINY-RAYED Lampsilis subangulata Clam

MUCKET, ORANGE-NACRE Lampsilis perovalis Clam

MOCCASINSHELL, GULF Medionidus penicillatus Clam

CLUBSHELL, SOUTHERN Pleurobema decisum Clam

PIGTOE, SHINY Fusconaia cor Clam

HEELSPLITTER, CAROLINA Lasmigona decorata Clam

SHRIMP, ALABAMA CAVE Palaemonias alabamae Crustacean

SHRIMP, VERNAL POOL TADPOLE Lepidurus packardi Crustacean

SHRIMP, VERNAL POOL FAIRY Branchinecta lynchi Crustacean

SHRIMP, SQUIRREL CHIMNEY CAVE Palaemonetes cummingi Crustacean

SHRIMP, SAN DIEGO FAIRY Branchinecta sandiegonensis Crustacean

Thursday, June 09, 2005 Page 5 of 20

SHRIMP, RIVERSIDE FAIRY Streptocephalus woottoni Crustacean

SHRIMP, CONSERVANCY FAIRY Branchinecta conservatio Crustacean

SHRIMP, CALIFORNIA FRESHWATER Syncaris pacifica Crustacean

SHRIMP, LONGHORN FAIRY Branchinecta longiantenna Crustacean

ISOPOD, MADISON CAVE Antrolana lira Crustacean

AMPHIPOD, KAUAI CAVE Spelaeorchestia koloana Crustacean

SALMON, CHUM (HOOD CANAL Oncorhynchus (=Salmo) keta Fish

SUMMER POPULATION)

SALMON, ATLANTIC Salmo salar Fish

SALMON, CHINOOK (CALIFORNIA Oncorhynchus (=Salmo) tshawytscha Fish

COASTAL ESU)

SALMON, CHINOOK (CENTRAL Oncorhynchus (=Salmo) tshawytscha Fish

VALLEY SPRING RUN)

SALMON, CHINOOK (LOWER Oncorhynchus (=Salmo) tshawytscha Fish

COLUMBIA RIVER)

SALMON, CHINOOK (PUGET SOUND) Oncorhynchus (=Salmo) tshawytscha Fish

SALMON, CHINOOK (SACRAMENTO Oncorhynchus (=Salmo) tshawytscha Fish

RIVER WINTER RUN)

SALMON, CHINOOK (SNAKE RIVER Oncorhynchus (=Salmo) tshawytscha Fish

FALL RUN)

SALMON, CHINOOK (SNAKE RIVER Oncorhynchus (=Salmo) tshawytscha Fish

SPRING/SUMMER)

SALMON, CHINOOK (UPPER Oncorhynchus (=Salmo) tshawytscha Fish

COLUMBIA RIVER SPRING)

STEELHEAD, UPPER COLUMBIA Oncorhynchus (=Salmo) mykiss Fish

RIVER POPULATION

SALMON, CHUM (COLUMBIA RIVER Oncorhynchus (=Salmo) keta Fish

POPULATION)

CHUB, MOHAVE TUI Gila bicolor mohavensis Fish

SALMON, COHO (CENTRAL Oncorhynchus (=Salmo) kisutch Fish

CALIFORNIA COAST POP)

SALMON, COHO (OREGON COAST Oncorhynchus (=Salmo) kisutch Fish

POPULATION)

SALMON, COHO (SOUTHERN Oncorhynchus (=Salmo) kisutch Fish

OR/NORTHERN CA COAST)

SALMON, SOCKEYE (SNAKE RIVER Oncorhynchus (=Salmo) nerka Fish

POPULATION)

STEELHEAD, SOUTHERN Oncorhynchus (=Salmo) mykiss Fish

CALIFORNIA POPULATION

SAWFISH, SMALLTOOTH Pristis pectinata Fish

STEELHEAD, SOUTH-CENTRAL Oncorhynchus (=Salmo) mykiss Fish

CALIFORNIA POP

SALMON, CHINOOK (UPPER Oncorhynchus (=Salmo) tshawytscha Fish

WILLAMETTE RIVER)

TROUT, BULL Salvelinus confluentus Fish

DARTER, SNAIL Percina tanasi Fish

Thursday, June 09, 2005 Page 6 of 20

DARTER, SLACKWATER Etheostoma boschungi Fish

DARTER, OKALOOSA Etheostoma okaloosae Fish

DARTER, LEOPARD Percina pantherina Fish

DARTER, ETOWAH Etheostoma etowahae Fish

DARTER, CHEROKEE Etheostoma scotti Fish

DARTER, BAYOU Etheostoma rubrum Fish

TROUT, PAIUTE CUTTHROAT Oncorhynchus clarki seleniris Fish

STEELHEAD, UPPER WILLAMETTE Oncorhynchus (=Salmo) mykiss Fish

RIVER POPULATION

TROUT, LAHONTAN CUTTHROAT Oncorhynchus clarki henshawi Fish

STEELHEAD, SNAKE RIVER BASIN Oncorhynchus (=Salmo) mykiss Fish

POPULATION

PUPFISH, DESERT Cyprinodon macularius Fish

SUCKER, SANTA ANA Catostomus santaanae Fish

SUCKER, RAZORBACK Xyrauchen texanus Fish

STURGEON, SHORTNOSE Acipenser brevirostrum Fish

STURGEON, PALLID Scaphirhynchus albus Fish

STURGEON, GULF Acipenser oxyrinchus desotoi Fish

STURGEON, ALABAMA Scaphirhynchus suttkusi Fish

CHUB, OREGON Oregonichthys crameri Fish

STICKLEBACK, UNARMORED Gasterosteus aculeatus williamsoni Fish

THREESPINE

TROUT, LITTLE KERN GOLDEN Oncorhynchus aguabonita whitei Fish

STEELHEAD, CALIFORNIA CENTRAL Oncorhynchus (=Salmo) mykiss Fish

VALLEY POP

SMELT, DELTA Hypomesus transpacificus Fish

MADTOM, SCIOTO Noturus trautmani Fish

GOBY, TIDEWATER Eucyclogobius newberryi Fish

SILVERSIDE, WACCAMAW Menidia extensa Fish

SQUAWFISH, COLORADO Ptychocheilus lucius Fish

STEELHEAD, CENTRAL CALIFORNIA Oncorhynchus (=Salmo) mykiss Fish

POPULATION

STEELHEAD, LOWER COLUMBIA Oncorhynchus (=Salmo) mykiss Fish

RIVER POPULATION

CHUB, BONYTAIL Gila elegans Fish

STEELHEAD, MIDDLE COLUMBIA Oncorhynchus (=Salmo) mykiss Fish

RIVER POPULATION

SHINER, TOPEKA Notropis topeka (=tristis) Fish

SHINER, CAPE FEAR Notropis mekistocholas Fish

SHINER, CAHABA Notropis cahabae Fish

SHINER, ARKANSAS RIVER Notropis girardi Fish

Thursday, June 09, 2005 Page 7 of 20

STEELHEAD, NORTHERN Oncorhynchus (=Salmo) mykiss Fish

CALIFORNIA POPULATION

SHINER, BLUE Cyprinella caerulea Fish

BUTTERFLY, SAINT FRANCIS\' SATYR Neonympha mitchellii francisci Insect

BUTTERFLY, QUINO CHECKERSPOT Euphydryas editha quino (=E. e. wrighti)
Insect

BUTTERFLY, BEHREN\'S SILVERSPOT Speyeria zerene behrensii Insect

BUTTERFLY, BAY CHECKERSPOT Euphydryas editha bayensis Insect

BUTTERFLY, MITCHELL\'S SATYR Neonympha mitchellii mitchellii Insect

MOTH, BLACKBURN\'S SPHINX Manduca blackburni Insect

BUTTERFLY, KARNER BLUE Lycaeides melissa samuelis Insect

BUTTERFLY, SAN BRUNO ELFIN Callophrys mossii bayensis Insect

BUTTERFLY, LOTIS BLUE Lycaeides argyrognomon lotis Insect

BEETLE, PURITAN TIGER Cicindela puritana Insect

SKIPPER, LAGUNA MOUNTAIN Pyrgus ruralis lagunae Insect

MOTH, KERN PRIMROSE SPHINX Euproserpinus euterpe Insect

BUTTERFLY, MISSION BLUE Icaricia icarioides missionensis Insect

BEETLE, VALLEY ELDERBERRY Desmocerus californicus dimorphus Insect

LONGHORN

BEETLE, DELTA GREEN GROUND Elaphrus viridis Insect

BUTTERFLY, CALLIPPE SILVERSPOT Speyeria callippe callippe Insect

BUTTERFLY, FENDER\'S BLUE Icaricia icarioides fenderi Insect

BEETLE, OHLONE TIGER Cicindela ohlone Insect

BEETLE, NORTHEASTERN BEACH Cicindela dorsalis dorsalis Insect

TIGER

FLY, DELHI SANDS FLOWER-LOVING Rhaphiomidas terminatus abdominalis
Insect

BEETLE, HUNGERFORD\'S CRAWLING Brychius hungerfordi Insect

WATER

BUTTERFLY, SMITH\'S BLUE Euphilotes enoptes smithi Insect

BUTTERFLY, MYRTLE\'S SILVERSPOT Speyeria zerene myrtleae Insect

BEETLE, AMERICAN BURYING Nicrophorus americanus Insect

GRASSHOPPER, ZAYANTE Trimerotropis infantilis Insect

BAND-WINGED

DRAGONFLY, HINES EMERALD Somatochlora hineana Insect

BEETLE, MOUNT HERMON JUNE Polyphylla barbata Insect

BAT, HAWAIIAN HOARY Lasiurus cinereus semotus Mammal

BAT, INDIANA Myotis sodalis Mammal

FOX, SANTA CRUZ ISLAND Urocyon littoralis santacruzae Mammal

FOX, SANTA ROSA ISLAND Urocyon littoralis santarosae Mammal

BAT, OZARK BIG-EARED Corynorhinus (=Plecotus) townsendii Mammal

KANGAROO RAT, FRESNO Dipodomys nitratoides exilis Mammal

KANGAROO RAT, STEPHENS\' Dipodomys stephensi (incl. D. cascus) Mammal

Thursday, June 09, 2005 Page 8 of 20

FERRET, BLACK-FOOTED Mustela nigripes Mammal

KANGAROO RAT, SAN BERNARDINO Dipodomys merriami parvus Mammal

KANGAROO RAT, MORRO BAY Dipodomys heermanni morroensis Mammal

WOODRAT, RIPARIAN Neotoma fuscipes riparia Mammal

WOLF, RED Canis rufus Mammal

WOLF, GRAY Canis lupus Mammal

OCELOT Leopardus (=Felis) pardalis Mammal

OTTER, SOUTHERN SEA Enhydra lutris nereis Mammal

KANGAROO RAT, GIANT Dipodomys ingens Mammal

LYNX, CANADA Lynx canadensis Mammal

FOX, SAN JOAQUIN KIT Vulpes macrotis mutica Mammal

MOUSE, SALT MARSH HARVEST Reithrodontomys raviventris Mammal

MOUSE, PACIFIC POCKET Perognathus longimembris pacificus Mammal

BEAR, LOUISIANA BLACK Ursus americanus luteolus Mammal

MOUSE, CHOCTAWHATCHEE BEACH Peromyscus polionotus allophrys Mammal

FOX, SAN MIGUEL ISLAND Urocyon littoralis littoralis Mammal

MOUNTAIN BEAVER, POINT ARENA Aplodontia rufa nigra Mammal

DEER, COLUMBIAN WHITE-TAILED Odocoileus virginianus leucurus Mammal

WHALE, NORTHERN RIGHT Eubalaena glacialis Mammal

CARIBOU, WOODLAND Rangifer tarandus caribou Mammal

SQUIRREL, DELMARVA PENINSULA Sciurus niger cinereus Mammal

FOX

RABBIT, PYGMY Brachylagus idahoensis Mammal

RABBIT, RIPARIAN BRUSH Sylvilagus bachmani riparius Mammal

SHREW, BUENA VISTA Sorex ornatus relictus Mammal

SHEEP, PENINSULAR BIGHORN Ovis canadensis Mammal

BAT, VIRGINIA BIG-EARED Corynorhinus (=Plecotus) townsendii Mammal

virginianus

SEAL, GUADALUPE FUR Arctocephalus townsendi Mammal

SEAL, HAWAIIAN MONK Monachus schauinslandi Mammal

KANGAROO RAT, TIPTON Dipodomys nitratoides nitratoides Mammal

MANATEE, WEST INDIAN Trichechus manatus Mammal

BEAR, GRIZZLY Ursus arctos horribilis Mammal

GOLDENROD, HOUGHTON\'S Solidago houghtonii Plant

GOLDFIELDS, BURKE\'S Lasthenia burkei Plant

GOLDEN SUNBURST, HARTWEG\'S Pseudobahia bahiifolia Plant

IRIS, DWARF LAKE Iris lacustris Plant

HAHA (CYANEA COPELANDII SSP. Cyanea copelandii ssp. copelandii Plant

COPELANDII)

HA\'IWALE (CYRTANDRA Cyrtandra limahuliensis Plant

LIMAHULIENSIS)

Thursday, June 09, 2005 Page 9 of 20

HA\'IWALE (CYRTANDRA GIFFARDII) Cyrtandra giffardii Plant

HAHA (CYANEA SHIPMANII) Cyanea shipmannii Plant

JEWELFLOWER, CALIFORNIA Caulanthus californicus Plant

IPOMOPSIS, HOLY GHOST Ipomopsis sancti-spiritus Plant

HAHA (CYANEA STICTOPHYLLA) Cyanea stictophylla Plant

HAHA (CYANEA HAMATIFLORA SSP. Cyanea hamatiflora carlsonii Plant

CARLSONII)

KAMAKAHALA (LABORDIA Labordia lydgatei Plant

LYDGATEI)

HAHA (CYANEA REMYI) Cyanea remyi Plant

KAMAKAHALA (LABORDIA Labordia tinifolia var. wahiawaensis Plant

TINIFOLIA VAR. WAHIAWAEN

GOLDFIELDS, CONTRA COSTA Lasthenia conjugens Plant

GOOSEBERRY, MICCOSUKEE Ribes echinellum Plant

(FLORIDA)

GOUANIA MEYENII (NCN) Gouania meyenii Plant

GRASS, CALIFORNIA ORCUTT Orcuttia californica Plant

GRASS, COLUSA Neostapfia colusana Plant

FOUR-O\'CLOCK, MACFARLANE\'S Mirabilis macfarlanei Plant

GRASS, HAIRY ORCUTT Orcuttia pilosa Plant

JOINT-VETCH, SENSITIVE Aeschynomene virginica Plant

HEAU (EXOCARPOS LUTEOLUS) Exocarpos luteolus Plant

FRITILLARY, GENTNER\'S Fritillaria gentneri Plant

HAPLOSTACHYS HAPLOSTACHYA Haplostachys haplostachya Plant

(NCN)

HALA PEPE (PLEOMELE Pleomele hawaiiensis Plant

FRINGEPOD, SANTA CRUZ ISLAND Thysanocarpus conchuliferus Plant

HARPERELLA Ptilimnium nodosum Plant

HAU KAUHIWI (HIBISCADELPHUS Hibiscadelphus woodii Plant

WOODI)

FRINGE TREE, PYGMY Chionanthus pygmaeus Plant

GEOCARPON MINIMUM Geocarpon minimum Plant

GERARDIA, SANDPLAIN Agalinis acuta Plant

HAU KUAHIWI (HIBISCADELPHUS Hibiscadelphus distans Plant

DISTANS)

GILIA, HOFFMANN\'S Gilia tenuiflora ssp. hoffmannii Plant

SLENDER-FLOWERED

GRASS, SACRAMENTO ORCUTT Orcuttia viscida Plant

HYPERICUM, HIGHLANDS SCRUB Hypericum cumulicola Plant

HEARTLEAF, DWARF-FLOWERED Hexastylis naniflora Plant

ILIAU (WILKESIA HOBDYI) Wilkesia hobdyi Plant

HEDYOTIS ST.-JOHNII (NCN) Hedyotis st.-johnii Plant

Thursday, June 09, 2005 Page 10 of 20

HESPEROMANNIA LYDGATEI (NCN) Hesperomannia lydgatei Plant

HIBISCUS, CLAY\'S Hibiscus clayi Plant

GRASS, SLENDER ORCUTT Orcuttia tenuis Plant

HAHA (CYANEA RECTA) Cyanea recta Plant

GRASS, SOLANO Tuctoria mucronata Plant

HAHA (CYANEA PLATYPHYLLA) Cyanea platyphylla Plant

GILIA, MONTEREY Gilia tenuiflora ssp. arenaria Plant

HILO ISCHAEMUM (ISCHAEMUM Ischaemum byrone Plant

BYRONE)

HAHA (CYANEA ASARIFOLIA) Cyanea asarifolia Plant

HOLEI (OCHROSIA KILAUEAENSIS) Ochrosia kilaueaensis Plant

HOWELLIA, WATER Howellia aquatilis Plant

HAREBELLS, AVON PARK Crotalaria avonensis Plant

GRASS, SAN JOAQUIN VALLEY Orcuttia inaequalis Plant

ORCUTT

BIRD\'S-BEAK, PENNELL\'S Cordylanthus tenuis ssp. capillaris Plant

AUPAKA (ISODENDRION Isodendrion longifolium Plant

LONGIFOLIUM)

\'AWIWI (CENTAURIUM Centaurium sebaeoides Plant

\'AWIWI (HEDYOTIS COOKIANA) Hedyotis cookiana Plant

BACCHARIS, ENCINITAS Baccharis vanessae Plant

BARBARA\'S BUTTONS, MOHR\'S Marshallia mohrii Plant

BARBERRY, ISLAND Berberis pinnata ssp. insularis Plant

BARBERRY, NEVIN\'S Berberis nevinii Plant

BEAKED-RUSH, KNIESKERN\'S Rhynchospora knieskernii Plant

BEARGRASS, BRITTON\'S Nolina brittoniana Plant

BONAMIA, FLORIDA Bonamia grandiflora Plant

BIRD\'S-BEAK, PALMATE-BRACTED Cordylanthus palmatus Plant

ASTER, FLORIDA GOLDEN Chrysopsis floridana Plant

BIRD\'S-BEAK, SALT MARSH Cordylanthus maritimus ssp. maritimus Plant

BIRD\'S-BEAK, SOFT Cordylanthus mollis ssp. mollis Plant

BLADDERPOD, MISSOURI Lesquerella filiformis Plant

BLADDERPOD, WHITE Lesquerella pallida Plant

BLAZING STAR, SCRUB Liatris ohlingerae Plant

BLUEGRASS, HAWAIIAN Poa sandvicensis Plant

BLUEGRASS, MANN\'S (POA MANNII) Poa mannii Plant

BLUEGRASS, SAN BERNARDINO Poa atropurpurea Plant

CHECKER-MALLOW, NELSON\'S Sidalcea nelsoniana Plant

BEDSTRAW, ISLAND Galium buxifolium Plant

ALOPECURUS, SONOMA Alopecurus aequalis var. sonomensis Plant

Thursday, June 09, 2005 Page 11 of 20

ADOBE SUNBURST, SAN JOAQUIN Pseudobahia peirsonii Plant

A\'E (ZANTHOXYLUM DIPETALUM Zanthoxylum dipetalum var. tomentosum Plant

VAR. TOMENTOSUM)

A\'E (ZANTHOXYLUM HAWAIIENSE) Zanthoxylum hawaiiense Plant

\'AIEA (NOTHOCESTRUM Nothocestrum breviflorum Plant

BREVIFLORUM)

\'AIEA (NOTHOCESTRUM Nothocestrum peltatum Plant

\'AKOKO (EUPHORBIA Euphorbia haeleeleana Plant

ALANI (MELICOPE HAUPUENSIS) Melicope haupuensis Plant

ALANI (MELICOPE KNUDSENII) Melicope knudsenii Plant

ALANI (MELICOPE PALLIDA) Melicope pallida Plant

AUPAKA (ISODENDRION Isodendrion laurifolium Plant

LAURIFOLIUM)

ALANI (MELICOPE Melicope zahlbruckneri Plant

AUPAKA (ISODENDRION HOSAKAE) Isodendrion hosakae Plant

ALSINIDENDRON VISCOSUM (NCN) Alsinidendron viscosum Plant

AMARANTH, SEABEACH Amaranthus pumilus Plant

AMBROSIA, SAN DIEGO Ambrosia pumila Plant

Amole, Camatta Canyon Chlorogalum purpureum var. reductum Plant

AMOLE, PURPLE Chlorogalum purpureum var. purpureum Plant

AMPHIANTHUS, LITTLE Amphianthus pusillus Plant

\'ANUNU (SICYOS ALBA) Sicyos alba Plant

ASPLENIUM FRAGILE VAR. Asplenium fragile var. insulare Plant

INSULARE (NCN)

ASTER, DECURRENT FALSE Boltonia decurrens Plant

BRODIAEA, THREAD-LEAVED Brodiaea filifolia Plant

ALANI (MELICOPE Melicope quadrangularis Plant

QUADRANGULARIS)

DROPWORT, CANBY\'S Oxypolis canbyi Plant

CROWNSCALE, SAN JACINTO Atriplex coronata var. notatior Plant

CYANEA UNDULATA (NCN) Cyanea undulata Plant

CYPRESS, GOWEN Cupressus goveniana ssp. goveniana Plant

CYPRESS, SANTA CRUZ Cupressus abramsiana Plant

DAISY, LAKESIDE Hymenoxys herbacea Plant

DAISY, PARISH\'S Erigeron parishii Plant

DAISY, WILLAMETTE Erigeron decumbens var. decumbens Plant

DAWN-FLOWER, TEXAS PRAIRIE Hymenoxys texana Plant

(=TEXAS BITTERWEED

DELISSEA RHYTODISPERMA (NCN) Delissea rhytidosperma Plant

BONAMIA MENZIESII (NCN) Bonamia menziesii Plant

DIELLIA PALLIDA (NCN) Diellia pallida Plant

CLOVER, SHOWY INDIAN Trifolium amoenum Plant

Thursday, June 09, 2005 Page 12 of 20

DUBAUTIA LATIFOLIA Dubautia latifolia Plant

DUBAUTIA PAUCIFLORULA Dubautia pauciflorula Plant

DUDLEYA, MARCESCENT Dudleya cymosa ssp. marcescens Plant

DUDLEYA, SANTA CLARA VALLEY Dudleya setchellii Plant

DUDLEYA, SANTA CRUZ ISLAND Dudleya nesiotica Plant

EVENING-PRIMROSE, ANTIOCH Oenothera deltoides ssp. howellii Plant

DUNES

FERN, AMERICAN HART\'S-TONGUE Asplenium scolopendrium var. Plant

FERN, PENDANT KIHI Adenophorus periens Plant

(ADENOPHORUS PERIENS)

FIDDLENECK, LARGE-FLOWERED Amsinckia grandiflora Plant

DIELLIA ERECTA (NCN) Diellia erecta Plant

CHAFFSEED, AMERICAN Schwalbea americana Plant

BUCKWHEAT, SCRUB Eriogonum longifolium var. Plant

BULRUSH, NORTHEASTERN Scirpus ancistrochaetus Plant

(=BARBED BRISTLE)

BUSH-CLOVER, PRAIRIE Lespedeza leptostachya Plant

BUSHMALLOW, SANTA CRUZ Malacothamnus fasciculatus var. Plant

BUTTON-CELERY, SAN DIEGO Eryngium aristulatum var. parishii Plant

CACTUS, BAKERSFIELD Opuntia treleasei Plant

CACTUS, UINTA BASIN HOOKLESS Sclerocactus glaucus Plant

CAMPION, FRINGED Silene polypetala Plant

CATCHFLY, SPALDING\'S Silene spaldingii Plant

CROWN-BEARD, BIG-LEAVED Verbesina dissita Plant

CEANOTHUS, VAIL LAKE Ceanothus ophiochilus Plant

CONEFLOWER, SMOOTH Echinacea laevigata Plant

CHAMAESYCE HALEMANUI Chamaesyce halemanui Plant

CHECKER-MALLOW, KECK\'S Sidalcea keckii Plant

CHECKER-MALLOW, KENWOOD Sidalcea oregana ssp. valida Plant

MARSH

CLADONIA, FLORIDA PERFORATE Cladonia perforata Plant

CLARKIA, PISMO Clarkia speciosa ssp. immaculata Plant

CLARKIA, SPRINGVILLE Clarkia springvillensis Plant

CLARKIA, VINE HILL Clarkia imbricata Plant

CLOVER, MONTEREY Trifolium trichocalyx Plant

CLOVER, RUNNING BUFFALO Trifolium stoloniferum Plant

FLANNELBUSH, MEXICAN Fremontodendron mexicanum Plant

CEANOTHUS, COYOTE Ceanothus ferrisae Plant

SCHIEDEA NUTTALLII (NCN) Schiedea nuttallii Plant

REMYA KAUAIENSIS (NCN) Remya kauaiensis Plant

REMYA MONTGOMERYI (NCN) Remya montgomeryi Plant

Thursday, June 09, 2005 Page 13 of 20

ROCK-CRESS, HOFFMANN\'S Arabis hoffmannii Plant

ROCK-CRESS, MCDONALD\'S Arabis mcdonaldiana Plant

ROSEMARY, SHORT-LEAVED Conradina brevifolia Plant

ROSEROOT, LEEDY\'S Sedum integrifolium ssp. leedyi Plant

SANDLACE Polygonella myriophylla Plant

SAND-VERBENA, LARGE-FRUITED Abronia macrocarpa Plant

SANDWORT, MARSH Arenaria paludicola Plant

SCHIEDEA HELLERI (NCN) Schiedea helleri Plant

PHYLLOSTEGIA KNUDSENII (NCN) Phyllostegia knudsenii Plant

SCHIEDEA MEMBRANACEA (NCN) Schiedea membranacea Plant

QUILLWORT, BLACK-SPORED Isoetes melanospora Plant

SCHIEDEA SPERGULINA VAR. Schiedea spergulina var. leiopoda Plant

LEIOPODA (NCN)

SCHIEDEA SPERGULINA VAR. Schiedea spergulina var. spergulina Plant

SPERGULINA (NCN)

SEA-BLITE, CALIFORNIA Suaeda californica Plant

SEDGE, WHITE Carex albida Plant

SILENE HAWAIIENSIS (NCN) Silene hawaiiensis Plant

SILENE LANCEOLATA (NCN) Silene lanceolata Plant

SILVERSWORD, KA\'U Argyroxiphium kauense Plant

(ARGYROXIPHIUM KAUENSE)

SILVERSWORD, MAUNA KEA Argyroxiphium sandwicense ssp. Plant

(\'AHINAHINA) sandwicense

SNEEZEWEED, VIRGINIA Helenium virginicum Plant

SPERMOLEPIS HAWAIIENSIS (NCN) Spermolepis hawaiiensis Plant

SCHIEDEA KAUAIENSIS (NCN) Schiedea kauaiensis Plant

KAUILA (COLUBRINA Colubrina oppositifolia Plant

PHYLLOSTEGIA VELUTINA (NCN) Phyllostegia velutina Plant

PHYLLOSTEGIA WAIMEAE (NCN) Phyllostegia waimeae Plant

PHYLLOSTEGIA WARSHAUERI (NCN) Phyllostegia warshaueri Plant

PHYLLOSTEGIA WAWRANA (NCN) Phyllostegia wawrana Plant

PINK, SWAMP Helonias bullata Plant

PINKROOT, GENTIAN Spigelia gentianoides Plant

PIPERIA, YADON\'S Piperia yadonii Plant

PITCHER-PLANT, ALABAMA Sarracenia rubra alabamensis Plant

CANEBRAKE

PITCHER-PLANT, GREEN Sarracenia oreophila Plant

PLATANTHERA HOLOCHILA (NCN) Platanthera holochila Plant

RATTLEWEED, HAIRY Baptisia arachnifera Plant

POA SIPHONOGLOSSA (NCN) Poa siphonoglossa Plant

QUILLWORT, LOUISIANA Isoetes louisianensis Plant

Thursday, June 09, 2005 Page 14 of 20

POGONIA, SMALL WHORLED Isotria medeoloides Plant

MINT, OTAY MESA Pogogyne nudiuscula Plant

POLYGONUM, SCOTT\'S VALLEY Polygonum hickmanii Plant

PONDBERRY Lindera melissifolia Plant

POPOLO \'AIAKEAKUA (SOLANUM Solanum sandwicense Plant

SANDWICENSE)

POPOLO KU MAI (SOLANUM Solanum incompletum Plant

INCOMPLETUM)

POTATO-BEAN, PRICE\'S Apios priceana Plant

POTENTILLA, HICKMAN\'S Potentilla hickmanii Plant

PUSSYPAWS, MARIPOSA Calyptridium pulchellum Plant

PU\'UKA\'A (CYPERUS Cyperus trachysanthos Plant

TRACHYSANTHOS)

SPINEFLOWER, MONTEREY Chorizanthe pungens var. pungens Plant

PLUM, SCRUB Prunus geniculata Plant

WATERCRESS, GAMBEL\'S Rorippa gambellii Plant

SPINEFLOWER, BEN LOMOND Chorizanthe pungens var. hartwegiana Plant

TORREYA, FLORIDA Torreya taxifolia Plant

TRILLIUM, RELICT Trillium reliquum Plant

TUCTORIA, GREEN\'S Tuctoria greenei Plant

UHIUHI (CAESALPINIA KAVAIENSIS) Caesalpinia kavaiense Plant

VETCH, HAWAIIAN (VICIA Vicia menziesii Plant

VIGNA O-WAHUENSIS (NCN) Vigna o-wahuensis Plant

VIOLA HELENAE (NCN) Viola helenae Plant

WAHINE NOHO KULA Isodendrion pyrifolium Plant

(ISODENDRION PYRIFOLIUM)

WALLFLOWER, BEN LOMOND Erysimum teretifolium Plant

THORNMINT, SAN DIEGO Acanthomintha ilicifolia Plant

WAREA, WIDE-LEAF Warea amplexifolia Plant

THISTLE, SUISUN Cirsium hydrophilum var. hydrophilum Plant

WATER-PLANTAIN, KRAL\'S Sagittaria secundifolia Plant

WAWAE\'IOLE (PHLEGMARIURUS Huperzia mannii Plant

(=HUPERZIA) MANNII)

WAWAE\'IOLE (PHLEGMARIURUS Lycopodium (=Phlegmariurus) nutans Plant

(=LYCOPODIUM) NUTAN

WHITLOW-WORT, PAPERY Paronychia chartacea Plant

WILD-BUCKWHEAT, CLAY-LOVING Eriogonum pelinophilum Plant

WINGS, PIGEON Clitoria fragrans Plant

WIREWEED Polygonella basiramia Plant

WOOLLY-STAR, SANTA ANA RIVER Eriastrum densifolium ssp. sanctorum Plant

WOOLLY-THREADS, SAN JOAQUIN Monolopia (=Lembertia) congdonii Plant

XYLOSMA CRENATUM (NCN) Xylosma crenatum Plant

Thursday, June 09, 2005 Page 15 of 20

YERBA SANTA, LOMPOC Eriodictyon capitatum Plant

WALLFLOWER, MENZIE\'S Erysimum menziesii Plant

SUNFLOWER, EGGERT\'S Helianthus eggertii Plant

PO\'E (PORTULACA SCLEROCARPA) Portulaca sclerocarpa Plant

SPINEFLOWER, ORCUTT\'S Chorizanthe orcuttiana Plant

SPINEFLOWER, ROBUST Chorizanthe robusta (incl. vars. robusta Plant

and hartwegii)

SPINEFLOWER, SCOTTS VALLEY Chorizanthe robusta var. hartwegii Plant

SPINEFLOWER, SLENDER-HORNED Dodecahema leptoceras Plant

SPINEFLOWER, SONOMA Chorizanthe valida Plant

SPURGE, HOOVER\'S Chamaesyce hooveri Plant

STENOGYNE ANGUSTIFOLIA (NCN) Stenogyne angustifolia var. angustifolia
Plant

STENOGYNE CAMPANULATA (NCN) Stenogyne campanulata Plant

STICKYSEED, BAKER\'S Blennosperma bakeri Plant

THORNMINT, SAN MATEO Acanthomintha obovata ssp. duttonii Plant

SUMAC, MICHAUX\'S Rhus michauxii Plant

SPINEFLOWER, HOWELL\'S Chorizanthe howellii Plant

SUNFLOWER, SAN MATEO WOOLLY Eriophyllum latilobum Plant

SUNFLOWER, SCHWEINITZ\'S Helianthus schweinitzii Plant

TARPLANT, GAVIOTA Deinandra increscens ssp. villosa Plant

TARPLANT, OTAY Deinandra (=Hemizonia) conjugens Plant

TARPLANT, SANTA CRUZ Holocarpha macradenia Plant

TETRAMOLOPIUM ARENARIUM Tetramolopium arenarium Plant

THELYPODY, HOWELL\'S Thelypodium howellii spectabilis Plant

SPECTACULAR

THISTLE, CHORRO CREEK BOG Cirsium fontinale var. obispoense Plant

THISTLE, FOUNTAIN Cirsium fontinale var. fontinale Plant

THISTLE, LA GRACIOSA Cirsium loncholepis Plant

THISTLE, PITCHER\'S Cirsium pitcheri Plant

STONECROP, LAKE COUNTY Parvisedum leiocarpum Plant

LYSIMACHIA FILIFOLIA (NCN) Lysimachia filifolia Plant

MARISCUS FAURIEI (NCN) Mariscus fauriei Plant

LOMATIUM, BRADSHAW\'S Lomatium bradshawii Plant

LOMATIUM, COOK\'S Lomatium cookii Plant

LOOSESTRIFE, ROUGH-LEAVED Lysimachia asperulaefolia Plant

LOULU (PRITCHARDIA AFFINIS) Pritchardia affinis Plant

LOULU (PRITCHARDIA Pritchardia napaliensis Plant

LOULU (PRITCHARDIA Pritchardia schattaueri Plant

LOULU (PRITCHARDIA VISCOSA) Pritchardia viscosa Plant

LOUSEWORT, FURBISH Pedicularis furbishiae Plant

Thursday, June 09, 2005 Page 16 of 20

LUPINE, CLOVER Lupinus tidestromii Plant

LOBELIA NIIHAUENSIS (NCN) Lobelia niihauensis Plant

LUPINE, SCRUB Lupinus aridorum Plant

LIVEFOREVER, SANTA BARBARA Dudleya traskiae Plant

ISLAND

MAHOE (ALECTRYON Alectryon macrococcus Plant

MACROCOCCUS)

MAKOU (PEUCEDANUM Peucedanum sandwicense Plant

SANDWICENSE)

MALACOTHRIX, ISLAND Malacothrix squalida Plant

MALACOTHRIX, SANTA CRUZ Malacothrix indecora Plant

MALLOW, KERN Eremalche kernensis Plant

MANZANITA, DEL MAR Arctostaphylos glandulosa ssp. crassifolia Plant

MANZANITA, MORRO Arctostaphylos morroensis Plant

POLYGALA, LEWTON\'S Polygala lewtonii Plant

MA\'O HAU HELE (HIBISCUS Hibiscus brackenridgei Plant

BRACKENRIDGEI)

PHLOX, TEXAS TRAILING Phlox nivalis ssp. texensis Plant

MAPELE (CYRTANDRA Cyrtandra cyaneoides Plant

LUPINE, NIPOMO MESA Lupinus nipomensis Plant

LAU\'EHU (PANICUM NIIHAUENSE) Panicum niihauense Plant

KAULU (PTERALYXIA KAUAIENSIS) Pteralyxia kauaiensis Plant

KIO\'ELE (HEDYOTIS CORIACEA) Hedyotis coriacea Plant

KIPONAPONA (PHYLLOSTEGIA Phyllostegia racemosa Plant

RACEMOSA)

KOKI\'O (KOKIA DRYNARIOIDES) Kokia drynarioides Plant

KOKI\'O (KOKIA KAUAIENSIS) Kokia kauaiensis Plant

KOKI\'O KE\'OKE\'O (HIBISCUS Hibiscus waimeae ssp. hannerae Plant

WAIMEAE SSP. HANNER

KOLEA (MYRSINE LINEARIFOLIA) Myrsine linearifolia Plant

KO\'OLOA\'ULA (ABUTILON Abutilon menziesii Plant

KUAWAWAENOHU Alsinidendron lychnoides Plant

(ALSINIDENDRON LYCHNOIDES)

LADIES\'-TRESSES, NAVASOTA Spiranthes parksii Plant

LOCOWEED, FASSETT\'S Oxytropis campestris var. chartacea Plant

LARKSPUR, YELLOW Delphinium luteum Plant

MA\'OLI\'OLI (SCHIEDEA Schiedea apokremnos Plant

LAUKAHI KUAHIWI (PLANTAGO Plantago hawaiensis Plant

HAWAIENSIS)

LAUKAHI KUAHIWI (PLANTAGO Plantago princeps Plant

PRINCEPS)

LAULIHILIHI (SCHIEDEA Schiedea stellarioides Plant

STELLARIOIDES)

Thursday, June 09, 2005 Page 17 of 20

LAYIA, BEACH Layia carnosa Plant

LEATHER-FLOWER, ALABAMA Clematis socialis Plant

LEATHER-FLOWER, MOREFIELD\'S Clematis morefieldii Plant

LESSINGIA, SAN FRANCISCO Lessingia germanorum (=L.g. var. Plant

germanorum)

LILY, MINNESOTA TROUT Erythronium propullans Plant

LILY, PITKIN MARSH Lilium pardalinum ssp. pitkinense Plant

LILY, WESTERN Lilium occidentale Plant

LIPOCHAETA VENOSA (NCN) Lipochaeta venosa Plant

LADIES\'-TRESSES, UTE Spiranthes diluvialis Plant

\'OHA WAI (CLERMONTIA Clermontia drepanomorpha Plant

DREPANOMORPHA)

ZIZIPHUS, FLORIDA Ziziphus celata Plant

MONKEY-FLOWER, MICHIGAN Mimulus glabratus var. michiganensis Plant

MONKSHOOD, NORTHERN WILD Aconitum noveboracense Plant

MOUNTAINBALM, INDIAN KNOB Eriodictyon altissimum Plant

\'OHA WAI (CLERMONTIA PELEANA) Clermontia peleana Plant

\'OHA WAI (CLERMONTIA Clermontia lindseyana Plant

LINDSEYANA)

MUNROIDENDRON RACEMOSUM Munroidendron racemosum Plant

(NCN)

MUSTARD, CARTER\'S Warea carteri Plant

NANI WAI\'ALE\'ALE (VIOLA Viola kauaiensis var. wahiawaensis Plant

KAUAENSIS VAR. WAHIAW

ACHYRANTHES MUTICA (NCN) Achyranthes mutica Plant

NAVARRETIA, MANY-FLOWERED Navarretia leucocephala ssp. plieantha Plant

MINT, SAN DIEGO MESA Pogogyne abramsii Plant

\'OHA (DELISSEA UNDULATA) Delissea undulata Plant

MANZANITA, SANTA ROSA ISLAND Arctostaphylos confertiflora Plant

NAVARRETIA, SPREADING Navarretia fossalis Plant

NEHE (LIPOCHAETA FAURIEI) Lipochaeta fauriei Plant

NEHE (LIPOCHAETA MICRANTHA) Lipochaeta micrantha Plant

\'OHA (DELISSEA RIVULARIS) Delissea rivularis Plant

NOHOANU (GERANIUM Geranium multiflorum Plant

MULTIFLORUM)

NEHE (LIPOCHAETA WAIMEAENSIS) Lipochaeta waimeaensis Plant

NERAUDIA OVATA (NCN) Neraudia ovata Plant

NERAUDIA SERICEA (NCN) Neraudia sericea Plant

NAVARRETIA, FEW-FLOWERED Navarretia leucocephala ssp. pauciflora Plant

(=N. pauciflora)

MEADOWFOAM, SEBASTOPOL Limnanthes vinculans Plant

PHACELIA, ISLAND Phacelia insularis ssp. insularis Plant

Thursday, June 09, 2005 Page 18 of 20

PENTACHAETA, WHITE-RAYED Pentachaeta bellidiflora Plant

PENNY-CRESS, KNEELAND PRAIRIE Thlaspi californicum Plant

PAINTBRUSH, TIBURON Castilleja affinis ssp. neglecta Plant

PAINTBRUSH, SOFT-LEAVED Castilleja mollis Plant

PAINTBRUSH, GOLDEN Castilleja levisecta Plant

OWL\'S-CLOVER, FLESHY Castilleja campestris ssp. succulenta Plant

ORCHID, WESTERN PRAIRIE Platanthera praeclara Plant

ORCHID, EASTERN PRAIRIE Platanthera leucophaea Plant

MONARDELLA, WILLOWY Monardella linoides ssp. viminea Plant

MARISCUS PENNATIFORMIS (NCN) Mariscus pennatiformis Plant

MINT, LONGSPURRED Dicerandra cornutissima Plant

\'OHAI (SESBANIA TOMENTOSA) Sesbania tomentosa Plant

MILK-VETCH, TRIPLE-RIBBED Astragalus tricarinatus Plant

ONION, MUNZ\'S Allium munzii Plant

\'OHA WAI (CLERMONTIA Clermontia pyrularia Plant

MEADOWRUE, COOLEY\'S Thalictrum cooleyi Plant

MILK-VETCH, JESUP\'S Astragalus robbinsii var. jesupi Plant

MILK-VETCH, COASTAL DUNES Astragalus tener var. titi Plant

MILK-VETCH, COACHELLA VALLEY Astragalus lentiginosus var. coachellae
Plant

MILK-VETCH, CLARA HUNT\'S Astragalus clarianus Plant

\'OLULU (BRIGHAMIA INSIGNIS) Brighamia insignis Plant

MEHAMEHAME (FLUEGGEA Flueggea neowawraea Plant

NEOWAWRAEA)

LIZARD, ISLAND NIGHT Xantusia riversiana Reptile

TURTLE, YELLOW-BLOTCHED MAP Graptemys flavimaculata Reptile

TURTLE, RINGED SAWBACK Graptemys oculifera Reptile

TURTLE, PLYMOUTH RED-BELLIED Pseudemys rubriventris bangsi Reptile

TURTLE, OLIVE (PACIFIC) RIDLEY Lepidochelys olivacea Reptile

TORTOISE, DESERT Gopherus agassizii Reptile

LIZARD, BLUNT-NOSED LEOPARD Gambelia silus Reptile

SNAKE, SAN FRANCISCO GARTER Thamnophis sirtalis tetrataenia Reptile

TURTLE, LOGGERHEAD SEA Caretta caretta Reptile

SNAKE, GIANT GARTER Thamnophis gigas Reptile

SNAKE, EASTERN INDIGO Drymarchon corais couperi Reptile

SKINK, BLUE-TAILED MOLE Eumeces egregius lividus Reptile

LIZARD, COACHELLA VALLEY Uma inornata Reptile

FRINGE-TOED

SKINK, SAND Neoseps reynoldsi Reptile

TORTOISE, GOPHER Gopherus polyphemus Reptile

TURTLE, ALABAMA RED-BELLIED Pseudemys alabamensis Reptile

Thursday, June 09, 2005 Page 19 of 20

TURTLE, FLATTENED MUSK Sternotherus depressus Reptile

TURTLE, GREEN SEA Chelonia mydas Reptile

TURTLE, HAWKSBILL SEA Eretmochelys imbricata Reptile

TURTLE, LEATHERBACK SEA Dermochelys coriacea Reptile

SNAKE, CONCHO WATER Nerodia paucimaculata Reptile

SNAIL, NEWCOMB\'S Erinna newcombi Snail

SNAIL, SNAKE RIVER PHYSA Physa natricina Snail

SNAIL, BLISS RAPIDS Taylorconcha serpenticola Snail

SPRINGSNAIL, IDAHO Fontelicella idahoensis Snail

SNAIL, MORRO SHOULDERBAND Helminthoglypta walkeriana Snail

SNAIL, TULOTOMA Tulotoma magnifica Snail

SPRINGSNAIL, BRUNEAU HOT Pyrgulopsis bruneauensis Snail

ROCKSNAIL, PLICATE Leptoxis plicata Snail

ROCKSNAIL, PAINTED Leptoxis taeniata Snail

SHAGREEN, MAGAZINE MOUNTAIN Mesodon magazinensis Snail

**No species were excluded.**

Thursday, June 09, 2005 Page 20 of 20

**APPENDIX J: MCPA/MCPB Calculations Acute to Chronic Ratio Aquatic
Organisms**

+---------------------------+-----------+--------+---------+----------+
| **Summary of endpoints    |           |        |         |          |
| (LC~50~ or EC~50~, mg     |           |        |         |          |
| ae/L) for**               |           |        |         |          |
|                           |           |        |         |          |
| **MCPA acute and chronic  |           |        |         |          |
| aquatic toxicity          |           |        |         |          |
| studies**                 |           |        |         |          |
+---------------------------+-----------+--------+---------+----------+
| **ORGANISM GROUP**        | **MCPA    | **     | **MCPA  | **MCPB** |
|                           | (acute)** | MCPB** | (chr    |          |
|                           |           |        | onic)** | **(ch    |
|                           |           | **(ac  |         | ronic)** |
|                           |           | ute)** |         |          |
+---------------------------+-----------+--------+---------+----------+
| freshwater fish (rainbow  | **96**    | *      | No data | No data  |
| trout)                    | (MCPA     | *3.9** |         |          |
|                           | DMAS)     |        |         |          |
+---------------------------+-----------+--------+---------+----------+
| freshwater fish (fathead  | No data   | No     | **12**  | No data  |
| minnow)                   |           | data   |         |          |
|                           |           |        |         |          |
| only chronic freshwater   |           |        |         |          |
| fish study for MCPA       |           |        |         |          |
+---------------------------+-----------+--------+---------+----------+
| freshwater inverts        | **82**    | **50** | **11**  | No data  |
| (Daphnid)                 | (MCPA     |        |         |          |
|                           | DMAS)     |        |         |          |
| only one study chronic    |           |        |         |          |
| freshwater invertebrate   |           |        |         |          |
| study for MCPA            |           |        |         |          |
+---------------------------+-----------+--------+---------+----------+
| estuarine/marine fish     | **179**   | No     | No data | No data  |
|                           | (MCPA     | data   |         |          |
| Atlantic Silverside       | Acid)     |        |         |          |
+---------------------------+-----------+--------+---------+----------+
| estuarine/marine inverts  | **4.9**   | No     | No data | No data  |
|                           | (MCPA     | data   |         |          |
| eastern oyster            | sodium    |        |         |          |
|                           | salt)     |        |         |          |
+---------------------------+-----------+--------+---------+----------+

+---------------------------------------+--------------+---------------+
| **Summary of endpoints (LC~50~ or     |              |               |
| EC~50~, mg ae/L)**                    |              |               |
|                                       |              |               |
| **determined by acute and chronic     |              |               |
| ratios**                              |              |               |
+---------------------------------------+--------------+---------------+
| **ORGANISM GROUP**                    | **MCPB**     | **MCPB**      |
|                                       |              |               |
|                                       | **(acute)**  | **(chronic)** |
+---------------------------------------+--------------+---------------+
| freshwater fish                       | **3.9**      | **.5**^a^     |
|                                       |              |               |
|                                       |              | Acute to      |
|                                       |              | chronic ratio |
+---------------------------------------+--------------+---------------+
| freshwater inverts                    | **50**       | **6.7**^b^    |
|                                       |              |               |
|                                       |              | Acute to      |
|                                       |              | chronic ratio |
+---------------------------------------+--------------+---------------+
| estuarine/marine fish                 | **7.3^c^**   | **.9^d^**     |
|                                       | Acute to     | Acute to      |
|                                       | chronic      | chronic       |
+---------------------------------------+--------------+---------------+
| estuarine/marine invert               | **2.9**^e^   | **.4^f^**     |
|                                       |              |               |
|                                       | Freshwat     |               |
|                                       | er/estuarine |               |
|                                       | marine ratio |               |
+---------------------------------------+--------------+---------------+

^a^MCPB Freshwater fish (chronic) **.5**= \[12(chronic freshwater fish
MCPA ) /96(acute freshwater fish MCPA)\]x3.9(acute freshwater fish MCPB)

^b^ MCPB Freshwater invertebrate (chronic) **6.7**=\[11( chronic
freshwater invertebrate MCPA ) /96(acute freshwater invertebrate
MCPA)\]x 50(acute freshwater invertebrate MCPB)

^c^MCPB Estuarine marine fish (acute) **7.3**=\[96( acute freshwater
fish MCPA ) /179(acute estuarine marine fish MCPA)\]x 3.9(acute
freshwater fish MCPB)

^d^MCPB Estuarine marine fish (chronic) **.9**=(.5 chronic freshwater
fish MCPB ) /3.9(acute freshwater fish MCPB)\]x 7.3(acute estuarine
marine fish MCPB)

^e^MCPB Estuarine marine invertebrates (acute) **2.9**=\[50( acute
freshwater invertebrate MCPB ) /82(acute freshwater invertebrates
MCPA)\]x 4.9(acute estuarine marine invertebrates MCPA)

^F^MCPB Estuarine marine invertebrates (chronic) **.4** =\[50( acute
freshwater invertebrate MCPB ) /82(acute freshwater invertebrates
MCPA)\]x 4.9(acute estuarine marine invertebrates MCPA) x\[11( chronic
freshwater invertebrate MCPA ) /82(acute freshwater invertebrates
MCPA)\]

  ----------------------------------------------------------------------------------------
  **Summarized Chronic                                                     
  Aquatic Organism Risk                                                    
  Quotients for MCPB Acid                                                  
  ^a,b^**                                                                  
  --------------------------- -------------- --------------- ------------- ---------------
  **Application/Scenario**    **Freshwater   **Freshwater    **Estuarine   **Estuarine
                              Fish^c,d^**    Invertebrates   Fish^c,d^**   Invertebrates
                                             ^e,f^**                       ^e,f^**

  Peas (ground spray          0.06           \<.01           0.03          0.07
  application) Oregon                                                      

  Peas (aerial spray          0.06           \<.01           0.04          0.08
  application) Oregon                                                      

  Peas (ground spray          0.07           \<.01           0.04          0.10
  application) California                                                  

  Peas (aerial spray          0.07           \<.01           0.04          0.10
  application) California                                                  
  ----------------------------------------------------------------------------------------

^a^ Detailed calculations of PRZM 3.12/EXAMS 2.98 modeling for peas
grown in Oregon and California are provided in Appendix B.

^b^Chronic toxicity thresholds (LC~50~ or EC~50~) calculated by acute to
chronic ratio with values from MCPA were .5 and 6.7 mg ae/L for
freshwater fish and freshwater invertebrates, respectively.

Chronic toxicity thresholds (LC~50~ or EC~50~) calculated by acute to
chronic ratio with values from MCPA were .9 and .4 mg ae/L for estuarine
marine fish and estuarine marine invertebrates, respectively.

**Chronic Fish**

^C^ EECs for Oregon bean Scenario were 28.1 and 31.5 µg/L for ground
spray and aerial spray, respectively.

^D^EECs for California lettuce Scenario were 36.4 and 38.9 µg/L for
ground spray and aerial spray, respectively.

**Chronic Invertebrates**

^e^EECs for Oregon bean Scenario were 29.0 and 32.5 µg/L for ground
spray and aerial spray, respectively.

^F^EECs for California lettuce Scenario were 39.0 and 41.7 µg/L for
ground spray and aerial spray, respectively.

  ----------------------------------------------------------------------------------------
  **Summarized Acute Aquatic                                               
  Organism Risk Quotients for                                              
  MCPB Acid ^a,b^**                                                        
  --------------------------- -------------- --------------- ------------- ---------------
  **Application/Scenario**    **Freshwater   **Freshwater    **Estuarine   **Estuarine
                              Fish^a,b^**    Invertebrates   Fish^a,b^**   Invertebrates
                                             ^a,b^**                       ^a,b^**

  Peas (ground spray          \<0.01         \<0.01          \<0.01        0.07
  application) Oregon                                                      

  Peas (aerial spray          \<0.01         \<0.01          \<0.01        0.08
  application) Oregon                                                      

  Peas (ground spray          0.01           \<0.01          \<0.01        0.10
  application) California                                                  

  Peas (aerial spray          0.01           \<0.01          \<0.01        0.10
  application) California                                                  
  ----------------------------------------------------------------------------------------

For an estuarine marine and freshwater ratio MCPB and MCPA:Acute
toxicity thresholds (LC~50~ or EC~50~) calculated with acute estuarine
marine fish and estuarine invertebrate values from MCPA 179 and 4.9
respectively; Values from MCPB were 3.9 and 50 mg ae/L for acute
freshwater fish and freshwater invertebrates, respectively.

**Acute Fish and Invertebrates**

^a^ EECs for Oregon bean Scenario were 29.5 and 33.1µg/L for ground
spray and aerial spray, respectively.

^B^EECs for California lettuce Scenario were 40.4 and 43.2 µg/L for
ground spray and aerial spray, respectively.