UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON D.C., 20460

PC Code: 125601 DP Barcode: 393895 March 26

, 2013

MEMORANDUM

Subject: Registration Review

– Ecological Risk Assessment and Effects Determination of Paclobutrazol

To: Khue Nugyen , Chemical Review Manager
Laura Parsons , Risk Manager Pesticide Re

- evaluation Division Office of Pesticide Programs ( 7508P )

From: Meghan Radtke, Ph.D., Biologist Faruque Khan, Ph.D., Senior Scientist Environmental Risk Branch 1 Environmental Fate and Effects Division Office of Pesticide Programs ( 7507P)

Approved by : Edward Odenkirchen

, Ph.D., Acting Branch Chief Sujatha Sankula, Ph.D., Lead Biologist Environmental Risk Branch 1 Environmental Fate and Effects Division Office of Pesticide Programs ( 7507P)

Attached is the ecological risk assessment and effects determination for the registration
review of the plant growth reg ulator, paclobutrazol

.

In general, most of the registered uses of paclobutrazol were found to potentially adversely
affect listed and non

- listed species. The exception was the seed treatment use. Cucurbit, tomato, pepper, cabbage, broccoli, and caulif lower seed treatments are not expected to cause adverse direct or indirect effects for any species. For the other uses (potted ornamentals drench and spray, tree injection, turf, soil injection/basal drench), t he following taxo nomic

groups of listed and n on

- listed organisms were found to be potentially of concern for direct
toxic risk from the registered uses of paclobutrazol:• M ammals (acute and chronic)

• B irds , reptiles, and land

- phase amphibians (chronic)

• Freshwater fish and aquatic

- phase amphibians (chronic)

• Estuarine/marine fish (chronic)

• Freshwater invertebrates (acute and chronic)

• Estuarine/marine invertebrates (acute and chronic)

• Aquatic vascular plants

• Terrestrial plants

Mammals

• Risk quotient analysis indicates potential acute risks of concern from turf applications and soil injection/drench

• Risk quotients range from 0.10 to 0.11 for turf and 0.13 to 0.34 for soil injection/drench.

• Risk quotient analysis indicates chronic risk concern s for all uses but the seed

treatments.

Birds, Reptiles, and Land

- Phase Amphibians

• Risk quotient analysis indicates potential chronic risk concerns from the soil injection/drench use.

• Risk quotients range from 1.1 to 2.3.

• Risks from tree injection, seed treatment, and potted ornamental drench and spray are
not expe cted to be of concern

.

Freshwater Fish and Aquatic

- Phase Amphibians

• Risk quotient analysis indicates potential chronic risk concerns from the turf and potted ornamentals drench.

Estuarine/Marine Fish

• Risk quotient analysis indicate s potential acute risk concerns from the potted
ornamental drench.

• Risk quotient analysis indicates potential chronic risk concern s from the turf and potted ornamentals drench.

Freshwater Invertebrates

• Risk quotient analysis indicates potential acute and chronic risk concern s f rom the turf and potted ornamental drench uses.

• The highest RQs for turf are 0.28 (acute) and 7.6 (chronic)

.

• The highest RQs for potted ornamental drench are 1.4 (acute) and 37 (chronic).Estuarine/Marine Invertebrates

• Risk quotient analysis indicates potential acute and chronic risks from the turf and potted ornamental drench uses.

• The highest RQs for turf are 0.28 (acute) and 1.1 (chronic).

• The highest RQs for potted ornamental drench are 1.4 (acute) and 9.5 (chronic).

Aquatic Vascular Plants

• Risk qu otient analysis indicates potential risk concern s from the turf and potted
ornamental drench uses.

Terrestrial Plants

• Risk quotient analysis indicates potential risk concern s from the turf and soil injection/basal drench uses.

Groups that were not found to be of concern for direct toxic risk include:

• Birds and reptiles (acute)

• Freshwater mollusks (acute)

• Freshwater fish (acute)

• Estuarine/marine fish (acute)

• Amphibians (acute)

• Non

- vascular plants

• Terrestrial invertebrates

Given that there are possible direct effects to mammals, birds, aquatic organisms, and plants,
indirect effects to all other organisms could occur. Indirect effects may include, but are not necessarily limited to, food, shelter, seed dispersal/pollin ation, or o ther habitat alter ations

.

## REGISTRATION REVIEW

ECOLOGICAL RISK ASSE SSMENT AND EFFECTS DETERMINATION

PACLOBUTRAZOL

CAS Number 76738

- 62

- 0

USEPA PC CODE 12 5601

(α R ,β R )

- rel

- β

- [(4

- chlorophenyl)methyl]

- α - (1,1

- dimethylethyl)

- 1 H

- 1,2,4

- triazole

- 1

- ethanol

Prepared by:

Meghan Radtke, Ph.D., Biologist Faruque Khan, Ph.D. Senior Scientist Environmental Risk Branch I

Reviewed by: Anita Ullaga d di, M.S., Biologist Christopher Koper, M.S., Chemist Environmental Risk Branch I Environmental Fate and Effects Division U. S. Environmental Protection Agency Office of Pesticide Programs Environmental Fate and Effects Division Environmental Risk Branch I 1200 Pennsylvania Ave., NW Mail Code 7507P Washington, DC 20460v 

### Executive Summary

E.1 Nature of Stressor

Paclobutrazol is a systemic plant growth regulator that is used to modify the physical structure of vegetation. It inhibits cell elongation and internode extension by interfering with gibberellins biosynthesis. It is used to produce denser, more compact plants

– rang ing from vegetables to turf to ornamental trees. It is currently registered for application to turf grass and a number of ornamentals (trees, shrubs, bulbs) to produce more compact plants and reduce mowing and trimming. It is also registered for use as a seed treatm ent for tomatoes,

peppers, cucurbits

, broccoli, cauliflower, and cabbage

. Formulated products vary in concentration and form, according to their use. For turf, products range from 0.018 to 22.3 percent active ingredient in a gra nular form. F or outdoor trees and ornamental use s (greenhouse and outdoors) , paclobutrazol is sold as a ready

- to

- use solution (2.51% ai), an emulsifiable concentrate ( 0.4 to 22.3% ai), a concentrated liquid (0.13 to 21.8% ai), or a wettable powder (50% ai). For seed t reatments, paclobutrazol is available as an emulsifiable
concentrate at a concentration of 22.3 to 22.9 percent active ingredient. Registered application methods for paclobutrazol are foliar spray (greenhouse and outdoors) , soil drench (greenhouse and outdoors)

, soil injection, tree injection, bulb soak, plug/liner soak, and seed

treatment.

Two major environmental degradates, the ketone analog of the parent (CGA 149907) and

1H

- 1,2,4

- triazol

- 3

- ol (NOA457654 )

, were identified in the en vironmental fate and terrestrial field dissipation studies. P aclobutrazol and these major degradates are considered as stressors for this risk assessment.



### E.2 Assessment of Risk

E.2.1 Physico

- Chemical and Environmental Fate Properties

Paclobutrazol is a racemic mixture of the (2 R , 3 R )

- and (2 S , 3 S )

- enantiomers but the physiochemical and fate properties of each enantiomer were not investigated in the submitted
studies. Therefore, it is assumed that each enantiomer of paclobutrazol has similar physio chemical and fate properties based on submitted studies. Paclobutrazol has a low solubility (25.9 mg/L) in water. The vapor pressure ( 1.28 x 10 - 9 mm Hg @ 25.0°C) and Henry's Law Constant (8.09 x 10 - 10 atm m 3 /mol) indicate that the compound is relatively

non

- volatile under field conditions. Paclobutrazol is stable to hydrolysis and photolysis. Under aerobic conditions, paclobutrazol appears to be generally quite persistent in acidic soils, with half

- lives gr eater than 300 days. However in soils with neutral or higher pH,
estimated half

- lives were as short as 25 days. Batch equilibrium results indicate that the mobility of paclobutrazol is quite variable ; ranging from mobile to slightly mobile ; t errestrial
f ield dissipation studies in various regions suggest that paclobutrazol is persistent andvi mobile. Two major environmental degradates, ketone analog of parent (CGA 149907, ≤ 40.0%) and 1H

- 1,2,4

- triazol

- 3

- ol (NOA457654, ≤ 25.1%) were identified in the
envir onmental fate and terrestrial field dissipation studies. Selected environmental fate studies indicate that NOA457654 is not a persistent chemical but that it is mobile. Laboratory and field studies suggest that paclobutrazol and its degradates have the potential

to move into groundwater via leaching and surface water, mainly through runoff.

E.2.2 Ecological Risk Conclusions The Agency assessed risk to a number of taxa

, including:

• Birds (which are also used as surrogates for reptiles and terrestrial

- ph ase amphibians)

• Mammals

• Fish (freshwater and estuarine / marine; freshwater fish are used as surrogates for aquatic

- phase amphibians)

• Aquatic invertebrates (freshwater and estuarine / marine)

• Terrestrial invertebrates

• Terrestrial plants

• A quatic plants (vascular and non

- vascular)

A direct ( adv erse) effect to an organism is considered to be that which occurs from exposure

to paclobutrazol. An indirect (adverse) effect to an organism is an adverse modification to a resource used by that organism, such as loss of prey or habitat, which is caused by the use of paclobutrazol

. This distinction is important when considering risks to species that are federally listed as endangered or threatened (referred to as “listed species”).

The specific taxa that may be at risk from paclobutrazol are highly dependent on the specific registered paclobutrazol use . For example, risk is unlikely from paclobutrazol use on seed treatments (pepper, tomato, cucurbit, cabbage, cauliflower, broccoli) , which represent the lowest ap plication rate of paclobutrazol products . Alternatively, for application s to turf,
which have a higher application rate and exposure potent ial, this assessment identifies
chronic risk for all size classes of mammals, as well as risk to terrestrial plants and aquatic
invertebrates (chronic and acute)

.

In general, registered uses of paclobutrazol may cause direct adve rse effects to some mammals, birds, reptiles, amphibians, fish, aquatic invertebrates

, and plants. B irds may be at risk from chronic dietary exposures from the soil injection/drench use. M ammals may be at acute risk from turf applications (short grass only) and soil injection/drench (vegetation); chronic risks span all uses but the seed treatments and include diets of short grass, tall grass, broadleaf plants/small insects, and fruits/pods/seeds/large insects. D irect risk s to terrestrial
invertebrates are not expected.vii R isks were identified for direct effects to fresh water or estuarine

- marine fish and
invertebrates from the current registe red uses of paclobutrazol

. Freshwater fish and mollusks are unlikely to be at acute risk from the registered paclobutrazol uses; however, risks were identified for chronic exposures to freshwater and estuarine/marine fish, and acute and chronic exposures to freshwater and estuarine/marine invertebrates. In particular, turf and potted ornamental drenches triggered these risks. Acute risks to estuarine/marine fish were also identified, but only for the potted ornamental drench use.

D irect effect s are expe cted for aquatic vascular plants for the turf and potted ornamentals

uses. D irect effects also are expected for terrestrial plants

– both terrestrial and semi

- aquatic

– as a result of spray drift (turf only) and runoff

.

Given that there are possible direct effects to mammals, birds

, aquatic organisms, and plants

, indirect effects to other organisms could occur. Indirect effects could take the form of food, shelter, seed dispersal/pollination, or other alterations of habitat.

The level of concern (LOC) from acute exposure is different for listed (endange red and/or threatened; LOC = 0.1 )

, and non

- listed (LOC = 0.5) terrestrial animals ; and for listed (LOC = 0.05)

, and non

- listed (LOC = 0.5) aquatic organisms . For chronic exposure, the LOC i s the
same for listed and non

- listed animals and is 1.0. The LOC is also 1.0 for both listed and

non

- listed plants (aquatic or terrestrial) . As the LOCs are different for listed and non

- listed species, evaluation of potential risk from direct exposure to paclobutrazol for non

- listed and listed species are summarized separately

. Tables E.1

– E.4 list the potential direct and indirect effects to listed species as well as the organism group and size classes potentially at
risk from use of paclobutrazol

.viii Table E. 1. Potential risks to n on - listed and listed species associated with d irect or indirect e ffects from p aclobutrazol

Taxonomic Group Effects Endpoint 1 Direct Effects Indirect Effects from Direct Effect s to: 1 Non

- listed Listed

Aquatic vascular plants Measures of biomass

– Vascular plant

– EC 50 ( Lemna

spp. )
Non

- vascular plant

– EC 50 ( green algae ) (surrogate data) Yes May Affect/ Likely to Adversely Affect Terrestrial p lants

Aquatic non

vascular plants No; RQs<LOC N o Effect ; RQs<LOC Currently n o listed non

- vascular plants

Terrestrial plants

- dicots Measures of biomass

V egetative v igor EC 25 and NOAEC (tomato ) Seedling emergence EC 25 and NOAEC (surrogate data) Yes M ay Affect/ Likely to Adversely Affect

Mammals, birds, terrestrial invertebrates

Terrestrial plants

- monocots Measures of biomass

Vegetative v igor EC 25 (non

definitive) and NOAEC ( corn, onion, ryegrass, wheat ) Seedling emergence EC 25 (wheat) and NOAEC (surrogate data) Yes May Affect/Likely to Adversely Affect

Freshwater fish/amphibians Acute: Mortality

- LC 50 (grass

carp ) Mortality

– LC 50 (Asiatic toad) No; RQs<LOC No Effect ; RQs<LOC Terrestrial i nvertebrate s, aquatic invertebrates , t errestrial and aquatic p lants Chronic: Chronic early life

- stage

- NOAEC (rainbow trout) Yes May Affect/Likely to Adversely Affect

Estuarine/m arine fish Acute: Mortality

- LC 50 (sheepshead minnow ) (surrogate data) No; RQs<LOC May Affect/Likely to Adversely Affect Terrestrial and aquatic plants

, t errestrial invertebrates, birds and/or m ammals Chronic: Early

- life stage NOAEC (sheepshead minnow) (surrogate data) Yes May Affect/Likely to Adversely Affect

Freshwater invertebrates Acute: Mortality

- EC 50 ( D.magna ) Mortality

- LC 50 (Chinese mystery snail) No; RQs<LOC May Affect/Likely

to Adversely Affect ; No Effect (freshwater mollusks only) T errestrial and aquatic p lants

Chronic: Growth and Reproduction

- NOAEC ( D.

magna ) (surrogate data) Yes May Affect/Likely to Adversely Affect

Estuarine/marine i nvertebrates Acute: EC 50 ( Eastern o yster and mysid shrimp ) (surrogate data) No; RQs<LOC May Affect/Likely to Adversely Affect Terrestrial and aquatic p lants
Chronic: chronic toxicity NOAEC (mysid shrimp) (surrogate data) Yes May Affect/Likely to Adversely Affectix Taxonomic Group Effects Endpoint 1 Direct Effects Indirect Effects from Direct Effect s to: 1 Non

- listed Listed

Mammals Acute : Oral LD 50 (rat ) Yes May Affect, Likely to Adversely Affect ; Terrestrial invertebrates, birds,

r eptiles, land

- phase a mphibians;

t errestrial p lants Chronic : Growth, survival, and reproduction

- Multi

- gen rat study Yes May Affect, Likely to Adversely Affect

Birds (surrogate for reptiles and land

phase amphibians) Acute: Oral LD 50 (mallard duck ) Acute: Dietary LC 50 (bobwh ite quail ) No; RQs<LOC No; RQs<LOC Terrestrial invertebrates,

m ammals , t errestrial p lants Chronic : Growth, survival, and r eproduction

- (bobwhite quail) Chronic dietary

- Yes May Affect, Likely to Adversely Affect

Terrestrial invertebrates Acute: Contact LD 50 (honeybee) (surrogate data) No No Terrestrial p lants

1 Direct effects to species may result in indirect effects to other species by changing av ail ability of prey and modification to habitat.

Table E. 2. Potential direct effects to l isted and n on - listed terrestrial organisms from exposure to p aclobutrazol 1

Paclobutrazol Lis ted Terrestrial Species Non

- listed Terrestrial Species

Birds 2 Mammals Plants Birds 2 Mammals Plants

Acute Chronic Acute Chronic Acute Chronic Acute Chronic

Turf N N Y (S,M) Y (S

, M

, L) Y N N N Y (S.M.L) Y

Potted ornamental

spray N N N Y (S,M,L) N N N N Y (S,M ,L ) Y

Tree injection N N N Y (S,M,L) N/A N N N Y (S,M ,L ) N/A

Soil injection/basal drench N Y Y (S,M, L) Y (S,M,L) Y N Y N Y (S,M,L) Y

Potted ornamental drench N N N Y (S,M,L) N N N N Y (S,M,L) Y

Tomato seed

treatment N N N N N N N N N N

Pepper seed

treatment N N N N N N N N N N

Cucurbit seed

treatment N N N N N N N N N N

Broccoli seed

treatment N N N N N N N N N N

Cauliflower seed treatment N N N N N N N N N Nx Paclobutrazol Lis ted Terrestrial Species Non

- listed Terrestrial Species

Birds 2 Mammals Plants Birds 2 Mammals Plants

Acute Chronic Acute Chronic Acute Chronic Acute Chronic

Cabbage seed

treatment N N N N N N N N N N

1 Y= Potential direct effects (RQ ≥ LOC) ; N = Potential direct effects not expected (RQ < LOC) ; ; N/A = not available (incomplete exposure pathway, thus it was not analyzed); S, M or L indicate which size class is potentially affected; S = small bird (20 g) or mammal (15 g); M = medium bird (100 g) or mammal (35 g); L = large bird (1000 g) or mammal (1 000 g). For mammals, chronic size classes are for dose

- based exposure only. Dietary

- based acute and chronic exposure for birds and mammals is not evaluated using body weights. RQ values were determined for these specific weights only, therefore, it is expected that potential direct effects may exist between two size classes in which the lower size class exceeded the LOC but the next size class did not. Therefore, for example, if small birds (20 g) exceeded the LOC but medium birds (100 g) did not, then potential direct effects may exist for all birds less than 100 g at any life stage until can be shown otherwise.

2 Birds are surrogates for terrestrial reptile s and terrestrial

- phase amphibia ns.

Table E.3. Potential direct effects to l isted a quatic o rg anisms from exposure to
p aclobutrazol 1

Paclobutrazol

Freshwater Fish Estuarine/Marine
Fish Vascular Aquatic
Plants Freshwater
Invertebrates Estuarine/Marine
Invertebrates

Acute Chronic Acute Chronic Acute Chronic Acute Chronic

Turf N Y N Y Y Y Y Y Y

Potted
ornamental
drench N Y Y Y Y Y Y Y Y

1 Y= Potential direct effects; N = Potential direct effects not expected

Table E.4. Potential direct e ffects to n on - l isted a quatic organisms from exposure to

p aclobutrazol 1

Paclobutrazol

Freshwater Fish Estuarine/Marine
Fish Vascular Aquatic
Plants Freshwater
Invertebrates Estuarine/Marine
Invertebrates

Acute Chronic Acute Chronic Acute Chronic Acute Chronic

Turf N Y N Y Y N Y N Y

Potted
ornamental
drench N Y N Y Y Y Y Y Y

1 Y= Potential direct effects; N = Potential direct effects not expectedxi 

### E. 3 Uncertainties
Certain data and other supporting information were not available to the Agency as it conducted the preliminary risk assessment for paclobutrazol . As such, certain assumptions
were made and conclusio ns were based on the information that was available. For some

taxa, t h is may have resulte d in the use of overly conservative approach es for evaluating risk

. EFED has identified the information it believes may help best resolve these uncertainties,
such as toxicity data for plants . Additional information may allow EFED to re fine its risk

conc lusions for certain species. Below is a summary of the uncertainties associated with the
risk assessment of paclobutrazol

.

E.3.1 Ecotoxicity Data G aps Data for the following fate and eco

- toxicity studies were not available. The Final Work Plan
for paclobutrazol requested seedling emergence and vegetati ve vigor data, but the studies submitted in response to this request were found to have major deficiencies that, in some cases, resulted in a n “invalid” classification . Data for the other studies were not r equested in
the Final Work Plan

. Open literature searches were performed, but even with the addition of information from these sources, data suitable for quantitative use in the risk assessment still were not available for estuarine/marine fish (acu te and chronic), freshwater invertebrates (chronic), estuarine/marine invertebrates (acute and chronic), seedling emergence (monocots and dicots), vegetative vigor (monocots), honey bees (acute contact), and vascular aquatic plants

.

To address each gap

, toxicity data were used from other triazoles that were similar in structure to paclobutrazol (Appendix F ) 1

. Crystal Ball (2000 version 5.0) was used to create a fitted lognormal distribution of toxicity endpoints running a Monte Carlo sampling scheme (10 ,000 trials). T he 5 th percentile of the data was calculated and used in the risk assessment. Not every triazole had a complete set of data, so the chemicals and number of data points varied for each paclobutrazol data gap. This approach was chosen as it was thought to be
conservative. The following bulleted list contains a brief description of how each data gap
was filled.

• Estuarine/Marine Fish (Acute) OPPTS 850.1075

. Definitive LC 50 data from six triazoles (cyproconazole, fenbuconazole, hexaconazole, metconazole, myclobutanil, tebuconazole, triticonazole) were available. A surrogate toxicity value for paclobutrazol acute effects on estuarine/marine fish was developed based on the 5 th
percentile of the distribution of data.

1 In situations where paclobutrazol data were available, the toxicity values for chemically similar triazoles were compared with the paclobutrazol data. There were no consistent patterns of toxicity. Paclobutrazol was the most toxic of the triazoles for t errestrial plants, but not the most toxic in other scenarios. No single triazole emerged as being consistently toxicologically similar to paclobutrazol, and thus an appropriate surrogate in itself.xii • Estuarine/Mar ine Fish (Chronic) OPPTS 850.1400

. Definitive NOAEC/NOEC data from three triazoles (metconazole, tebuconazole, triticonazole) were available. A surrogate toxicity value for paclobutrazol chronic effects on estuarine/marine fish was developed based on the 5 th percentile of the distribution of data.

• Freshwater Invertebrates (Chronic) OPPTS 850.1300

. Definitive NOAEC/NOEC data from eight triazoles (cyproconazole, fenbuconazole, hexaconazole, metconazole, tebuconazole, triadimefon, triadimenol, triticonazole ) were available. A surrogate toxicity value for paclobutrazol chronic effects on freshwater invertebrates was developed based on the 5 th percentile of the distribution of data.

• Estuarine /Marine Invertebrates (Acute) OPPTS 850.1025 and OPPTS 850. 1035

. D efinitive LC 50 /EC 50 data from seven triazoles (cyproconazole, fenbuconazole, hexaconazole, metconazole, myclobutanil, tebuconazole, triticonazole) were available. A surrogate toxicity value for paclobutrazol acute effects on
estuarine/marine invertebrates was developed based on the 5 th percentile of the
distribution of data. In addition, acute toxicity data were available for a freshwater
mollusk.

• Estuarine/Marine Invertebrates (Chronic) OPPTS 850.1350

. Definitive NOAEC/NOEC data were available for only one triazole

– tebuconazole. Consequently, tebuconazole’s toxicity value was used as a surrogate for paclobutrazol
chronic effects on estuarine/marine invertebrates.

• Seedling Emergence (Monocots and Dicot s) OPPTS 850.4225

. Definitive monocot NOAEC/NOEC data from four triazoles (cyproconazole, metconazole, tebuconazole, triticonazole) were available. A surrogate toxicity value for paclobutrazol effects on monocot seedling emergence was developed based on the 5 th percentile of the
distribution of data. Definitive dicot EC 25 data from three triazoles (cyproconazole, tebuconazole, triticonazole) and definitive dicot NOAEC/NOEC data from three triazoles (cyproconazole, metconazole, triticonazole) were availa ble. Surrogate toxicity values for paclobutrazol effects on dicot seedling emergence were developed
based on the 5 th percentile of these two data distributions.

• Vegetative Vigor (Monocots) OPPTS 850.4250

. Definitive monocot NOAEC/NOEC
data from three t riazoles (cyproconazole, metconazole, tebuconazole) were available. A surrogate toxicity value for paclobutrazol effects on monocot vegetative vigor was developed based on the 5 th percentile of the distribution of data.

• Honey Bee (Acute Contact) OPPTS 850 .3020

. Only non

- definitive LD 50 data were available for five triazoles (cyproconazole, fenbuconazole, metconazole, triadimefon, triticonazole). Consequently, t he most conservative value (tri ticonazole) was used in
the risk assessment

.

• Aquatic Vascular Pl ants (EC 50 ) OPPTS 850.4400

. Definitive EC 50 data were available for four triazoles (cyproconazole, metconazole, tebuconazole, triticonazole).xiii A surrogate toxicity value for paclobutrazol effects on aquatic vascular plants was developed based on the 5 th percentile of the distribution of data.

• Aquatic Non

- Vascular Plants (EC 50 ) OPPTS 850.5400

. Toxicity data were not available for algal species. Open literature provided some toxicity information on paclobutrazol to green algae.

• Passerine Birds (Acute ) OP PTS 850.2100

. Data were not available; there fore, the acute oral toxicity of paclobutrazol to the mallard duck was used to evaluate risk.

E.3.2 Application Rates Many of the labels did not contain application information in pounds of active ingredient per

acre (Table E

. 5) . Tree injection, and soil injection/basal drench for ornamental trees provided application rates in grams of paclobut razol per tree diameter. To evaluate exposure, assumptions (based on open literature) on the number of trees expecte d to be present in one
acre as well as a conservative application rate in pounds of paclobutrazol per acre were made. These assumptions may be overestimating or underestimating exposure.

Greenhouse seed treatme nts for cucurbits, peppers, tomatoes

, broccoli, cauliflower, and cabbage were stipulated in terms of micrograms of paclobutrazol per seed. To evaluate environmental exposure, the number of transplants per acre was derived from open literature sources. These assumptions may be overestimating or underestimating exposure.

Pre

- plant plug and liner soak labels did not provide specific use rates because the rate is influenced by varying soak times, the extent of rooting of each plant, the media moisture levels, the differ ing sensitivities of culti vars and species being treated, cultural practices, and environmental factors. Consequently, it was not possible to calculate a per

- acre application rate for these uses. It was assumed that the pre

- plant plug and liner soak application rate
would not exc eed the soil drench and/or bench spray for greenhouse or namental transplants (see below). This assumption may be overestimating or underestimating exposure.

Soil drench and bench spray application rates for greenhouse ornamental transplants were
describe d in terms of parts per million per various size pot or bench area. To evaluate exposure, assumptions (based on open literature) were made to estimate the application rate per acre. These assumptions may be overestimating or underestimating exposure.xiv Table E

. 5. Summary of missing label information and approaches used in risk

assessment

Use Missing Label Information Risk Assessment Approach Tree injection (ornamental trees) lb ai/A Convert ppm per tree DBH into lb ai/A, making assumptions about the
number and size of trees in
an urban acre Soil injection/basal drench (ornamental trees) lb ai/A Convert ppm per tree DBH into lb ai/A, making assumptions about the
number and size of trees in
an urban acre Seed treatment (cucurbit, tomato, pepper, cabba ge, cauliflower, broccoli) lb ai/A Use high

- end seeding rates for each crop to determine
the lb ai/A Soil drench and bench spray application (greenhouse ornamental transplants) lb ai/A after plants have been
moved outside of the greenhouse setting Multiplied the ppm per pot application rate times the number of “can tight” pots found in an acre of nursey
land to derive lb ai/A

E.3.3 Rate of Paclobutrazol Uptake into Plants Spray, drench, and seed treatment applications assume that paclobutrazol wi ll be absorbed into plants in one of two ways: directly through the leaves, stem, or seed coat; or taken up through the roots from the soil. Information was not available on the rate a t which this occurred. This posed a challenge for assessing risk to t errestrial and aquatic organisms. For example, in the tree drench scenario, the most conservative assumption for assessing risk to terrestrial animals is to assume 100 percent of the paclobutrazol is taken up into the plant. Conversely, the most conserva tive assumption for assessing risks to aquatic organisms or other terrestrial plants (via runoff) is to assume that none of the paclobutrazol was taken up into the plant and is all still available in the soil. This approach of using the most
conservative assumptions for each organism group assessed essentially “double counts” the amount of paclobutrazol available to non

- target organisms and over

- estimates risk to some groups, if not all. However, without data to show how quickly paclobutrazol is absorbed into plants, it is difficult to choose realistic exposure scenarios. Consequently, the following plant

- to

- soil scenario s were considered: 100%:100%, 50%:50%, 25%:75%, and 75%:25%.xv E.3. 4 Distribution of Paclobutrazol in Plants The application methods for paclobutrazol rely on its translocation to internodes and dividing cells within the plant. In particular, drenches and tree/soil injections rely on the chemical being transported from the roots or trunk of the tree to the leave s and stems. No information is available about whether all of the paclobutrazol concentrates in the leaves of the tree or if it remains equally distributed throughout the entire tree (roots, trunk, branches, fruit, leaves, etc.) or its translocation rate

. In the risk assessment, the conservative assumption was made that paclobutrazol concentrates in the leaves of the plant (leaves are used as a surrogate for fruit, seeds, or other edible non

- woody food items) and that it does so very quickly after being a pplied. This may have resulted in overly conservative estimates of paclobutrazol exposure through the consumption of treated foliage.

E. 3. 5 Fate Data Gaps Data for the following fate study were not available

.

• OPPTS 850.173 0

– Fish B ioconcentration F act or (BCF) . In lieu of data, KABAM was used to model the bioaccumulation potential of paclobutrazol. Results indicated
that the likelihood of bioaccumulation in aquatic food web was low.

E. 3.6 In complete Life Histories of Listed Species Currently, a database of life histories for each of the listed animals and plants is not available for use by EFED . These life histories would include information such as body size at each life stage, food sources, relationships with other taxa, habitat, and reproduct ive habits. As such, conservative (protective) assumptions were made concerning the potential relationships between species in that each species was assumed to have a relationship with the other taxa.
This is assumed to be an overestimation of the actual spe cies that have a species depende nt relationship.

E. 3. 7 Locations of Listed Species In addition, the specific occurrences of listed species are not known in some cases beyond the
county

- level. I f the location of a species was not known in greater detail than the county level, the species was assumed to occur anywhere within that county at any time. This assumption may lead to an overestimation of co

- occurrence with paclobutrazol exposure and overestimation of the number of species potentially at r isk.

E. 3. 8 Seasonal Carryover in Plants Paclobutrazol is a systemic and is known to persist for years in trees (based on label information and application intervals). It is unknown if for grasses and perennials, paclobutrazol levels are maintained acros s seasons and expressed in subsequent “generations” of foliage.xvi E.3.9 Information on Crop Locations, Actual Use Rates
, and Application
Method s While the assessment was based on the maximum application rates and methods stated on the registered labels, i nformation on the actual use rates and application method s employed in residential settings, golf courses, right

- of

- ways, athletic fields, and in agricultural field s were not available to refin e the risk characterization of paclobutrazol

. In addition, sub

- county
information on where treated tomatoes, peppers, cucurbits , broccoli, cauliflower, and cabbage are grown would allow for greater confidence in estimates of crop co

- occurrences with listed species.

E. 3.10 Greenhouse Discharges

Pacl obutrazol is applied as a liquid to potted plants within greenhouses, as well as a bulb and plug/liner soak. It is possible that paclobutrazol may be present in the runoff water. This is a scenario that was not assessed and a point of uncertainty.xvii 

### Table of Contents
Introduction

..... ................................ ................................ ................................ ....................... 2 3 Purpose of assessment.....

................................ ................................ ................................ 2 3 Problem f ormulation

................................ ................................ ................................ ............... 24 Previous risk a ssessments

................................ ................................ ................................ 25 Stressor source and d istribution

................................ ................................ ....................... 2 5 Mechanism of a ction ...............................................................................2 5 Overview of pesticide use and u sage

........................ ..................................... 2 6 Tree injection..................................................................... ...............30 Soil injection

..................................................................... ...............31 Basal drench

.................................................................. .................. 31 Seed treatment

........................................................................ . .......... 3 2
Pre

- plant plug/liner soak and pre

- plant bulb soaks

.............................. . ......... 3 3 Soil drench and bench sprays (potted ornamentals)

....................................... 3 3 Environmental fate and t ransport

................................ ................................ .................... 3 5 Summary of environmental f ate

.................................... . ..................... . .... 3 5 Degradation

.............................................................................. . ...... .3 9 Mobility and transport ..............

......................................................................... . ....40 Field studies ............................................................................ .........40 Degradates

....................................................................................... 40 Bioaccumulation

.............................................................................. ..4 2 Receptors

................................ ................................ ................................ ......................... 4 3 Effects to o rganisms

... ......................................................................... ... 43 Registrant submitted studies for paclobutrazol

............................ . ................ 4 3 O pen literature studies

.................. ............... ... .................................... 43 Incident database r eview

.......................................................................... 4 3 Data g aps i dentified

................................................................................ 4 4 Ecosystems potentially at r isk ....................................................................4 4 Degradates

........................... ............................................................ 4 6 Conceptual m odel

................................ ................................ ................................ ....... 4 6 Risk h ypothesis

................................ ................................ ................................ ........... 4 8 Terrestrial environment........................................................................ 4 8 Aquatic environment

........................................................................... 4 9 Analysis p lan

................................ ................................ ................................ ............... 4 9
Measures to e valuate the risk hypothesis and conceptual m odel

......................... 4 9 Measures of e ffect ..............................................................................4 9 Integration of exposure and e ffects

........................................................... 50 Analysis of co

- occurance of f ederall y listed s pecies with paclobutrazol

............... 50 Exposure a ssessment

................................ ................................ ................................ ............... 5 2 Aquatic exposure a ssessment

................................ ................................ .............................. 5 2 Monitoring data

.................................................................................... 5 2 PRZM/EXAMS

... ................................................... ......... .................. 5 2 Aquatic exposure modeling results

................................ ................................ .................. 5 5 Terrestrial e xposure

................................ ................................ ................................ ............. 5 7 Dietary

- b ased paclobutrazol residue l evels

................................ ................................ ..... 5 7xviii EEC estimates for tree injection, soil injection, tree drench, and potted ornamentals (drench).............................................................................................. 60 Tree injection, soil injection/tree drench, and woody potted ornamental drench leaf bio mass estimates

............................................................................... 6 1
Non

- woody potted ornamental drench application

......................................... 66 EEC estimates for seed treatment to tomato, pepper, cucurbit, broccoli, caulifl ower, cabbage

.............................................................................................. 6 8 Off

- field terrestrial and wetland/riparian p lant paclobutrazol e xposure

......................... 70 Effects c haracterization

................................ ................................ ................................ ........... 7 4 Terrestrial vertebrate t oxicology

................................ ................................ ......................... 7 5 Effects on b irds

................................ ................................ ................................ ................ 7 7 Effects on m ammals

................................ ................................ ................................ ........ 7 8 Terrestrial invertebrate t oxicology

................................ ................................ ...................... 7 8 Surrogate data approach

................................ ................................ ................................ .. 7 9 Aquatic vertebrate (fish) t oxicology

................................ ................................ ................... 80 Effects to freshwater f ish and aquatic

- phase amphibians

................................ ................ 80 Effects to estuarine

- marine f ish

................................ ................................ ....................... 8 2 Surrogate data approach

........................................................................ 8 2 Aquatic invertebrate t oxicology

................................ ................................ .......................... 8 2 Effects to freshwater i nvertebrates

................................ ................................ .................. 8 3 Surrogate data approach........................................................................ 8 5 Effects to estuarine

- marine i nvertebrates

................................ ................................ ........ 8 5 Surrogate data approach

........................................................................ 8 5
Terr estrial plant t oxicology

................................ ................................ ................................ . 8 5 Surrogate data approach

................................ ................................ ................................ .. 8 7 Aquatic plant t oxicology

................................ ................................ ................................ ..... 8 8 Surrogate data approach

................................ ................................ ................................ .. 8 8 Results: risk c haracterization

................................ ................................ ................................ . 90 Risk e stimation

................................ ................................ ................................ .................... 90 Direct effects to non

- target terrestrial v ertebrates

................................ ........................... 90 Direct effects to birds, reptiles, and (land

- phase) a mphibians

............................... 90 Direct effects to m ammals

........................................................................ 92 Acute effect s............. ...............................................................................................9 2 Chronic effects.................................................................................. 9 2 Direct effects to non

- target terrestrial i nvertebrates

................................ ........................ 9 5 Direct effects to terrestrial and wetland/riparian p lants

................................ ................... 9 5 Direct e f fects to freshwater fish (amphibians), invertebrates and estuarine

- marine fish (amphibians) and invertebrates and aquatic p lants

................................ .......................... 9 7 Freshwater fish and aquatic

- phase amphibians

- acute risk

............................... 9 7 Freshwater fish and aquatic

- phase amphibians

- chronic risk

. ........................... 9 8 Estuarine/marin e fish

- acute risk

... ......................................................... 9 9 Estuarine/marine fish

- chronic risk

.... ...................................................... 9 9 Freshwater invertebrates

- acute risk

.................................................. ...... 100 Freshwater invertebrates

- chronic risk

............................................ ......... 100 Estuarine/marine invertebrates

- acute risk

..... ............................................ 10 1 Estuarine/marine invertebrates

- chronic risk .............................................10 2xix Aquatic vascular and non

- vascular plants

................................................ . 10 3 Probit slope response a nalysis of LOC values and acute RQ v alues

............................. 10 4 Ris k d escription

................................ ................................ ................................ ................. 10 5 Exposure uncertainties

................................ ................................ ................................ ... 10 6 Direct effects to terrestrial birds, reptiles and a mphibians

.................................. 10 8 Acute risk .......................................................................................10 8 Chronic risk ....................................................................................10 8 Summary of risks from direct effects

.... ...................................................10 9 Direct effects to terrestrial m ammals

........................................................... 1 1 0 Acute risk .......................................................................................1 1 0 Chronic risk ....................................................................................11 1 Summary of risks from direct effects

....................................................... 11 4 Direct effects to terrestrial i nvertebrates

....................................................... 11 5 Summary of risks from direct effects

...................................................... .115 Direct effects to terrestrial p lants

............................................................... 11 5 Summary of risks from direct effects

................................................... ....11 9 Direct effects to aquatic fish, i nvertebrates , and p lants

......... ............................. 1 20 Freshwater fish and amphibians (aquatic

- phase), and estuarine

- marine fish

...... ... 1 20 Acute risk

..................................................................... ............1 20 Chronic risk

.............................................................................. 1 21 Freshwater and estuarine

- marine invertebrates

....................................... ....12 4 Acute risk

................................................................................. 12 4 Chronic risk

................................................ ..................... .........12 6 Aquatic plants

- vascular and non

- vascular

............................................. ...12 8 Summary of risk from direct effects

........................................................ 1 30 Listed species effects a na lysis

................................ ................................ ....................... 1 30 Action a rea

......................................................................................... 13 6 Effects area d etermination

....................................................................... 13 6 Direct effects....................................................................................... 13 6 Indirect effects

..................................................................... ...............13 7 Uncertainties ............................................................................................1 41 Effects and risk assessment u ncertainties

................................ ................................ .......... 1 41 Ecotoxicity data gaps

................................ ................................ ................................ ..... 1 41 Application rates

................................ ................................ ................................ ............ 1 43 Rate of paclobutrazol uptake into plants

................................ ................................ ....... 1 43 Distribution of paclobutrazol in plants

................................ ................................ .......... 1 44
Fate data gaps

................................ ................................ ................................ ................ 1 44 Incomplete life histories of listed species

................................ ................................ ...... 1 44 Locations of listed species

................................ ................................ ............................. 1 44 Information on crop locations, actual use rates, and application methods

.................... 14 5 Other routes of e xposure

................................ ................................ ................................ 14 5 Foliar dissipation half

- lif e

................................ ................................ ............................. 14 5 Species sensitivities.............................................................................. 14 5 Endocrine d isrupter

................................ ................................ ................................ ........ 14 6 Seasonal carryover in plants

................................ ................................ .......................... 14 7 Greenhouse discharges

................................ ................................ ................................ .. 14 7xx Spatial analyses

................................ ................................ ................................ .............. 14 7 References ...............................................................................................14 8 Appendix A

- B ibliography o f MRIDs............... .................................................1 52 Appendix B

– H alf

- life calculations of total toxic residues

......... ...................... ... ...... 15 7 Appendix C

– C hemical structures

...... ......................................... ...........................1 61 Appendix D

– KABAM inputs and outputs....

................................ ...........................1 62 Appendix E

– ECOTOX literature search

.......................................................... 1 6 8 Appendix F

– S urrogate chemicals

............................................ .............................. 205 Appendix G

– SIP and STIR model output......

............................. .............................. 20 8 Appendix H

– Risk quotient method and levels of concern..

.............. .............................. 2 11 Appendix I

– S urface water model results and sample input and o utputs

......... ........... ... 2 13 Appendix J

– TerrPlant output

....................................................................... 21 8 Appendix K

– T errestrial EEC calculations

............ ............................................ ..2 30xxi 

### List of Abbreviated Terms and Symbols
@ symbol for “at”
% symbol for “percent”

> symbol for “greater than”

< symbol for “less than” μg/L symbol for “micrograms per liter” oC symbol for “degrees Celsius” ai active ingredient Acc# accession number
BEAD B iological and Economical Analysis Division b w body weight CI confidence interval CL confidence limit
DP# data p ackage EC e mulsifiable concentrate EC 25 25% effect concentration EC 50 50% (or median) effect concentration ECOTOX EPA managed database EEC estimated environmental concentration
EFED Environmental Fate and Effects Division

e.g

. Latin exempli gratia (“for example”) et al. Latin et alii (“and others”)

etc. Latin et cetera (“and the rest” or “and so forth”) FESTF FIFRA Endangered Species Task Force
FIFRA Federal Insecticide Fungicide and Rodenticide Act FQPA Food Quality Protection Act f t f eet
g g ram GENEEC Generic Estimated Exposure Concentration model IC 5 0 50% (or median) inhibition concentration
i.e

. Latin for id est (“that is”) IMS information management s ystem K g kilogram(s)
K m kilometer(s)
K oc symbol for the organic carbon partitioning coefficient
LAA likely to adversely affect
L bs p ounds lb ai/A pound(s) of active ingredient per acre LC 50 50% (or median) lethal concentration
LD 50 50% (or median) lethal dose LOAEC lowest observable adverse effect concentration LOAEL lowest observable adverse effect level LOC level of concern LOD level of detection LOEC lowest observable effect concentration
K ow symbol for the octanol water partitioning coefficientxxii LOQ level of quantitation LUIS l abel use information system

m meter(s)
MA may affect

m g milligram(s) mg/kg milligrams per kilogram (equivalent to ppm , except in the case of discussing dose such as mg/kg

- bw ) mg/L milligrams per liter (equivalent to ppm)

m i mile(s)
MM may modify p r imary constituent e lement MM/NSF may modify primary constituent element/no s hapefile mmHg millimeter of mercury
MRID master record identification number
MW molecular weight NASS National Agricultural Statistics Service NAWQA National Water Quality Assessment
NE no effect NLAA not likely to adversely affect NMFS National Marine Fisheries Service NOAA National Oceanic and Atmospheric Administration NOAEC no observable adverse effect concentration NOAEL no observable adverse effect level NOEC no observable effect concentration OCSPP Office of Chemical Safety and Pollution Prevention OPP Office of Pesticide Programs OPPTS Office of Prevention, Pesticides and Toxic Substances pH symbol for the negative logarithm of the hydrogen ion activity in an aqueous solution, dimensionless pKa symbol for the negative logarithm of the acid dissociat ion constant, dimensionless

p pb parts per billion (equivalent to μg/L or μg/kg)

p pm parts per million (equivalent to mg/L or mg/kg) SLUA s creening level usage analysis USDA United States Department of Agriculture USEPA United States Environmental Protection Agency USFWS United States Fish and Wildlife Service USGS United States Geological Survey
W t w eight23 

# Introduction

Purpose of Assessment

The purpose of t his assessment is to evaluate the potential risk s of paclobutrazol ’s registered

use and pending registrations on federally listed endangered and threatened ( “ listed ” ) species
and all other non

- target plant and animal (“non

- listed”) species

. Th is risk assessment incorporates the available effects data, modeling, and risk methodologies , some of which may not have been available at the time when previous paclobutrazol regist ration actions
occurred. Risks from direct and indirect effects are deriv ed and evaluated in accordance with the risk assessment methodology described in the Agency ’s Overview Document (US EPA

, 2004). These risk findings are then used as part of an “effects determination” for listed species . T he Agency will reach one of the f ollowing three conclusions regarding the potential for the registered paclobutrazol use on food and non

- food crops to affect fe d erally listed species :

• “No effect”;

• “ May affect , but not likely to adversely affect”; or

• “ May affect , and l ikely to adversely affect”.

If the results of the risk assessment show no indirect effects and the levels of concern (LOC) are not exceeded for direct effects for a given listed species taxonomic grouping ( e.g ., freshwater fish, small herbivorous mammal) , a “no effect” (NE) determination is made,
based on paclobutrazol’s use within the action area for a species with in the given taxonomic group. If, however, there is a potential for indirect effects and/or exposure exceeds the listed species LOC values fo r direct effects for a given group, the Agency concludes a preliminary “may affect” (MA) for a species within the taxonomic group. The Agency then considers additional lines of evidence such as the geographical nature of the exposure, as well as more

in

- d epth evaluations of the toxicological and ecological requirements to determine a rationale for a “not likely to adversely affect” (NLAA) or “likely to adversely affect” (LAA)
determination.

Similarly the Agency will reach one of the following conclusions regarding the potential for paclobutrazol uses to result in destruction or adverse modification of critical habitat:

• “No effect”;

• “ May Modify Primary Constituent Elements”

The Agency uses the risk assessment analysis for direct effects to categories of biologi cal resource requirements to draw conclusions about effects to principle constituent elements of24 critical habitat . The Agency is limited in a practical sense to those principle constituent elements of critical habitat that are of a biological natu re. If the results of the risk assessment show that no LOC is exceeded for all taxonomic groups a “no effect” (NE) determination for
habitat modification is made. If a n LOC is exceeded for one or more taxonomic groupings the Agency then considers additio nal lines of evidence such as the type and degree of effect on the taxonomic groupings, expected resultant effects on biologically mediated environmental processes ( e.g ., increased sedimentation from loss of vegetation) as compared
to baseline environmenta l conditions, co

- occurrence of the action area with critical habitat, the type of principle constituent elements associated with critical habitat for listed species in a taxonomic grouping to determine a rationale for a “may modify primary constituent
elem ents”.



### Problem Formulation

The problem formulation for this assessment and effects determination was provided in the

U S EPA Registration Review

– EFED Problem Formulation for Paclobutrazol Registration Review March 13, 2 007 document. Data were requested for five studies:

• 850.7050

– UV/Visible absorption (“acceptable” classification)

• 850.1400

– Fish early

- life stage toxicity test (“acceptable” classification)

• 850.2300

– Avian reproduction test (“acceptable classification)

• 850.4100

– Terrestrial plant toxi city

– seedling emergence (“invalid” classification)

• 850.4150

– Terrestrial plant toxicity

– vegetative vigor (“supplemental” classification)

A dditional information on paclobutrazol was extracted from the scientific open literature.
All submitted data an d other information for paclobutrazol are listed in the MRID bibliography in Appendix A

.

There were several modifications to the risk assessment process originally proposed in the problem formulation.

• Seed treatments (cucurbits, tomatoes, peppers

, cabbage, cauliflower, broccoli ) and plant/plug liner soaks were registered after the completion of the problem formulation
and are thus considered in this risk assessment.

• Two paclobutrazol major degradates ( CGA 149907 and 1H

- 1,2,4

- triazol

- 3

- ol (NOA457654 ) were identified as being stressors of concern

. Since there are no toxicity and environmental fate data available for these degradates at this time , a total toxics residue approach was taken rather than solely considering paclobutrazol.25 • A 5 t h percentile s urrogate toxicity data approach was used to fill in data gaps rather than the proposed acute

- to

- chronic

- ratio because paired datasets (e.g., same species and same chemical) were not available in most instances.

Under the Federal Insecticide, Fungicide, an d Rodenticide Act (FIFRA), all pesticides distributed or sold in the United States generally must be registered by the United States Environmental Protection Agency (U.S. EPA). To determine whether a pestic ide can be registered, EPA evaluates its safety t o non

- target species based on a wide range of environmental and health effects studies. In 1996, FIFRA was amended by the Food Quality
Protection Act (FQPA) , and EPA was mandated to implement a new program for the periodic review of pesticides, i.e ., reg istration review 2 . The registration review prog ram is
intended to ensure that as the ability to assess risk evolves and as policies and practices change, all registered pesticides continue to meet the statutory standard of no unreasonable
adverse effects to human health and the environment. Changes in science, public policy, and pesticide use practices will occur over time. Through the new registration review program, the Agency periodically reevaluates pesticides to make sure that as change occurs, prod ucts
in the ma r ketplace can be used safe ly.

Previous Risk Assessments

The three most recent completed screening level risk assessments for use on tomatoes, peppers, and cucurbits seeds (DP Barcode D329407, June 4, 2007)

, use for pre

- plant plug and liner soaks (DP Barcode D338570, June 12, 2007) , and use on broccoli, cauliflower, and cabbage seeds (DP Barcode D398449, August 17, 2012) did not identify any adverse risks to listed species. However, there were a number of da ta gaps where assumptions were made. Of significance was the lack of plant data (terrestrial and aquatic) for these risk assessments.

The risk assessments available in the docket, and which serve as the basis for this problem formulation, include the fol lowing:

• June 12, 2007 assessmen t of pre

- plant and liner soaks

• June 4, 2007 and August 17, 2012 assessment s of seed treatment s

• Assessments for a variety of turf, ornamental, and tree uses in the 1980s

The risk assessments did not identify any risks to a ny specific taxa.

Stressor Source and Distribution

M ECHANISM OF A CTION Paclobutrazol is a plant growth regulator that inhibits gibberellin biosynthesis. Gibberellin

pro motes cell elongation in plants; thus, inhibiting it decreases cell length and results in more

2 http://www.epa.gov/oppsrrd1/registration_review/26 compact plants. Paclobutrazol enters the plant through leaves (foliar application), root uptake (soil drenches and injections), seed coat (seed treatment) or by direct injection into the tree, depen ding on the application method. The compound is then systemically transported through the plant via the xylem. Depending on the plant, paclobutrazol levels can persist within the plant from 8 weeks (turf) to several years (trees) with physical effects st ill visible. Paclobutrazol and its two major degradates (see “Degradates” section, below) are considered
stressors of concern.

O VERVIEW OF P ESTICIDE U SE AND U SAGE Paclobutrazol, also known by the trade name s Clipper, Bonzi, Paczol, and others , is a plant growth regulator that is currently registered for application to a number of foo d and non

- food crops to induce compact plant growth

. Registered application methods for paclobutrazol are foliar spray, soil injection , soil drench, bulb soak, seed treatment

, plug/liner soak, and tree injections. It is used to control the size of numerous plants including turf, trees in right

- of

ways, ornamental trees and shrubs, and bulbs ( cut flower trade). Ten different companies currently have registered products with p aclobutrazol concentrations ranging from 0.018 to 50 percent. Current r egistrations for formulated products and u ses of paclobutrazol are shown in Table 1

, below. Uses of paclobutrazol are shown in Table 2

, below.

An average of 31,500 pounds of paclobutrazol (averaged from 2002, 2004, and 2006) is applied in the United States each year with the majority being applied to turf (24,500 lb). Paclobutrazol also was used as a growth regulator in nurseries/greenhouses (6000 lb) and landscape settings (1,000 lb). Specific usage information from the California Pesticide Use Report indicated th at 1140 pounds of paclobutrazol were used in 2009 with the following breakdown: landscape maintenance (815 lb), greenhouse flowers/greens (3 lb), greenhouse container plants (55 lb), greenhouse grown transplant material (6 lb), outdoor container plants (2 4 lb), outdoor flowers/greens (7 lb), outdoor grown transplant material (2 lb), ornamental turf (31 lb), rights of way (194 lb), and structural pest control 3 (3 lb).

3 Acco rding to BEAD, this use may be 1) a mistake in the California database; or 2) a non

- standard term used by applicators (e.g., a tree that is close to a building that has potential to cause structural damage may be recorded as “structural pest control” rathe r than “landscape maintenance”).27 Table 1 . Current r egistrations for p aclobutrazol

P roduct Name Registrant EPA Registration #

(latest label date) Active Ingredient

(% w/w) Form Use (s)

Bonzi 50 WP Syngenta Crop Protection, Inc. 000100

- 00992 (2/24/86) 50 Wettable powder Ornamental herbaceous plants, ornamental non

flowering plants, ornamental woody shrubs and vines
Bonzi II Ornamental

Growth Regulator Syngenta Crop Protection, Inc. 000100

- 01079 (1/9/04) 0.13 Soluble

concentrate Ornamental herbaceous plants, ornamental woody shrubs and vines
Bonzi Ornamental Growth Regulator Syngenta Crop Protection, Inc. 000100

- 00996 (8/18/10) 0.4 Soluble

concentrate Ornamental herbaceous plants, ornamental woody shrubs and vines,

Cambistat Rainbow Treecare Scientific Advancements 74779

- 3 8/17/10 22.3 Emulsifiable

concentrate Ornamental and/or shade trees

Clipper 20 UL Syngenta Crop Protection, Inc. 000100

- 00995 (1/17/86) 2.51 Ready

- to

- use solution Ornamental and/or shade trees

Clipper 50 WP Syngenta Crop Protection, Inc. 000100

- 00991 (6/6/85) 50 Wettable powder Ornamental and/or shade trees
Clipper E 20 UL Tree

Growth Regulator Syngenta Crop Protection, Inc. 000100

- 01037 (4/3/89) 2.51 Ready

- to

- use solution Nonagricultural uncultivated areas/soils, ornamental and/or shade trees

Cutdown Phoenix Environmental

Care, LLC. 81943

- 31 10/7/08 22.3 Emulsifiable

concentrate Turf grass and trees

ETI 107 01 G Etigra 000228

- 679 (5/6/08) 0.4 Emulsifiable

concentrate Ornamental herbaceous plants

Fertilizer with TGR
Poa annua control The Andersons Lawn Fertilizer Division, Inc. 009198

- 00196 (6/18/10) 1.38 Granular Golf course turf, ornamental lawns and turf

High K Fertilizer with TGR Poa annua control The Andersons Lawn Fertilizer Division, Inc. 009198

- 00201 (6/10/09) 0.34 Granular Golf course turf

Paclo 2 SC Fine Agrochemicals, Ltd. 62097

- 24 (11/7/08) 22.3 Soluble

concentrate Ornamental and/or shade trees

Paclobutrazol 2 SC Syngenta Crop Protection, Inc. 000100

- 01014 (8/13/10) 22.3 Soluble

concentrate Turf, ornamental and/or shade trees, seeds (tomato, pepper, cucurbit , broccoli, cauliflower, and cabbage )
Paczol Ornamental Growth Regulator Chemtura Corporation 000400

- 00515 (11/6/08) 0.4 Emulsifiable

concentrate Ornamental herbaceous plants, ornamental woody shrubs and vines

Piccolo Fine Agrochemicals, Ltd. 062097

- 00011 (8/29/07) 0.4 Emulsifiable

concentrate Ornamental herbaceous plants, ornamental woody shrubs and vines28 P roduct Name Registrant EPA Registration #

(latest label date) Active Ingredient

(% w/w) Form Use (s)

Piccolo 10x Fine Agrochemicals, Ltd. 62097

- 25 8/24/11 4 Flowable

concentrate Ornamental herbaceous plants

Profile 2 SC Tree Growth Regulator SePRO Corporation 067690

- 00022 (11/2/10) 21.8 Soluble

concentrate Turf, ornamental and/or shade trees,

Scotts Turf Manager
II The Scotts Company 000538

- 00201 (3/24/86) 0.066 Granular Ornamental lawns and turf

Scotts Turf Manager

for St. Augustine Grass The Scotts Company 000538

- 00199 (8/26/93) 0.018 Granular Ornamental lawns and turf

TGR Turf Enhancer 2SC The Andersons Lawn Fertilizer Division, Inc. 009198

- 00205 (8/31/11) 22.3 Soluble

concentrate Golf course turf

TGR Winter Overseeding

Enhancer The Andersons
Lawn Fertilizer Division, Inc. 009198

- 00199 (7/10/09) 1.38 Granular Golf course turf, ornamental lawns and turf

The Andersons Fertilizer with 0.25% Paclobutrazol The Andersons Lawn Fertilizer Division, Inc. 009198

- 00215 (1/30/09 0.25 Granular Golf course turf

Tide Paclo 0.4% Liquid Zhejiang Tide Cropscience Company, Ltd. 080697

- 00003 (12/30/10) 0.4 Soluble

concentrate Ornamental herbaceous plants, ornamental woody shrubs and vines

Tide Paclo 2 SC Zhejiang Tide Cropscience Company, Ltd. 80697

- 4 8/13/10 22.3 Emulsifiable

concentrate Turf grass and trees

Trimtect Rainbow Treecare Scientific Advancements 74779

- 7 5/24/11 8 Emulsifiable

concentrate Ornamental and/or shade trees29 Table 2

. Current r egistrations of p aclobutrazol

Crop Maximum Application
R ate Number of Applications Application Method Shortest Application

Interval

(days) Reg

. #*

Broccoli, cauliflower, and cabbage 2 μ g ai/seed 1 Seed treatment** N/A 000100

- 1014

Cucurbit 6.5 μ g/seed 1 Seed
Treatment ** N/A 000100

- 01014

Herbaceous and ornamentals (greenhouse) *** 5.7 mg ai/ft 2 NS Spray, D rench, Bulb S oak

, Plug/Liner Soak As needed 000100

- 00992 000100

- 00996 000100

- 01079 000400

- 00515 062097

- 00011 080697

- 00003

000228

- 679

62097

- 25 Pepper 16 μ g ai /seed 1 Seed
Treatment ** N/A 000100

- 01014

Tomato 12.5 μ g ai /seed 1 Seed
Treatment ** N/A 000100

- 01014

Trees (shade and ornamental) 0.009 lb ai per inch

DBH 1 Soil Injection, Basal Drench, Tree Injection 3 years or as needed 000100

- 01037 000100

- 00991 000100

- 00995 000100

- 01014 067690

- 00022

000228

- 680

74779

- 3 74779

- 7 80697

- 4 81943

- 31 62097

- 24
Turf 0.75 lb ai/A 3 Spray, Broadcast 14 009198

- 00196 009198

- 00199 009198

- 00201 009198

- 00205 009198

- 00215 000100

- 01014 067690

- 00022 000538

- 00201 000538

- 00199

000228

- 680

80697

- 4 81943

- 31
NS

- not specified on label

* Application rates represent maximum application rate for a least one of the EPA Reg

. # listed. Other labels may have slightly different application rates. **Seeds are germinated in greenhouses and seedlings are later transplante d outdoors. ***May be planted outdoors after cultivation in a nursery or greenhouse.30 Many of the labels for registered products did not contain application information in pounds of active ingredient per acre. The Biological and Economic Analysis Division (BEAD) calculated rates in pounds of paclobutrazol per acre, making a number of assumptions about the application method ( US EPA , 2011 a )

.

Tree Injection For tree injection application rates, BEAD used the Clipper 20 UL label. Clipper is a tree growth retardant for ornamental trees. Injections should be made at every 8 inches around the circumference of the trunk. The amount of paclobutrazol injected depends on the number
of holes and the size of the tree. The following table is presented on the label (Table 3) :

Tabl e 3. Tree size and use p arameters for Clipper 20 UL (2.51% ai)

Tree Diameter (inches) 1 Number of Injection Holes Volume of Clipper 20 UL per Injection Site (ml) Total Volume of Clipper 20 UL per Tree (ml) Total G rams of Paclobutrazol per Tree 2

8 3 50 150 4.6
12 5 50 250 7.7
16 6 75 450 13.8
20 8 75 600 18.4
24 9 75 675 20.7
28 11 75 825 25.3
32 13 75 975 29.9

1 Assumed to be equivalent to the diameter at breast height (DBH)

2 Total grams ai per tree = total volume (ml) per tree*density (1.22 grams per ml [Tomlin 2003]*percent product concentration (2.51%)

To calculate a “pounds of paclobutrazol per acre” rate based on the label directions, the density and sizes of trees in urban settings is necessary. Urban forest information was taken from Nowak et al. (2001). They characterize urban forests as ecosystem s with trees and other vegetation in association with people and their developments. Nowak et al. (2001 through 2011) conducted a series of studies assessing the effects and values of urban forests in 24 cities in the United States and Canada. They repor t the overall density of trees per acre and the distribution of tree size (diameter at breast height

– DBH) for each city. Using this information, BEAD calculated the median value for density and DBH. These values were used to calculate tree injection, t ree basal drench, and tree soil injection rates for paclobutrazol (see Table 1 in US EPA , 2011 a ).

Total grams ai per tree (4.6g)*number of trees per acre (36)*conversion factor (1 lb/453.59g) = 0.36 lb ai/A for tree injections.31 This is considered a conservative estimate because: 1) applications using soil injections or basal drench around the base of the tree are much easier and faster to accomplish than tree injections (Chaney 2005); 2) soil injection around the base of the tre e and basal drench also control the growth rate of grass around the tree (Chaney 2005); 3) the formulation contains
metha nol which has resulted in crack s, weeping injection holes, and internal wood
discoloration and has reduced the use of alcohol

- containin g products in forestry (Chaney 2005).

Soil Injection For soil injections, BEAD used the Paclobutrazol 2SC label (2 pounds ai/gallon) . The label calculates an application rate based on tree size and species. The dose for a 6

- inch DBH tree ranges from 25 to 100 ml of formulation per tree.

Using the median values for the number of trees planted per acre, tree DBH (see tree injection description), and the maximum application for a 6

- inch DBH tree, BEAD calculated the following rate:

Formulation per tree (100 ml)*(1 gallon formulation/3785.4ml)*(2 lb ai/gallon)*number of trees per acre (36) = 1.9 lb ai/A

This is considered a conservative estimate because the maximum amount of active ingredient per tree is used and many small trees in urban forests are not treated with growth regulators.

Basal Drench For tree basal drenches, BEAD used the Profile 2SC label (2 pounds ai/gallon). The label groups various species of trees and states the following application rates:

1 to 2 g ai/in DBH (e.g., sweetgum)

2 to 3 g ai/in DBH (e.g., elm, maple, oak) 3 to 4 g ai/in DBH (e.g., Bradford pear, ash)

Using the maximum application rate listed above, and the median values for number of trees per acre and tree diameter, the following application rate was calculated:

Grams ai applied per inch DBH (4) * median DBH (6) * (1 lb/453.59g) * number of trees per acre (36) = 1.9 lb ai/A

This is considered a conservative estimate because the maximum amount of active ingredient per tree is used and many small trees in urban forests are not treated with growth regulators.32 Seed Treatment For seed treatments (tomato, pepper, cucurbits , cabbage, broccoli, cauliflower ), BEAD used the Paclobutrazol 2SC label (2 lb ai/gallon). Paclobutrazol 2SC is applied to seeds using slurries, film coatings, and direct application at the following rates:

Tomato

– 1 to 12.5 μg ai/seed Pepper

– 1 to 16 μg ai/seed
Cucurbits

– 1 to 6.5 μg ai/seed
Broccoli

– 0.1 to 2 μg ai/seed
Cauliflower

– 0.1 to 2 μg ai/seed Cabbage

– 0.1 to 2 μg ai/seed

Seeding rate s vary by seed size; usually larger seeds, like pumpkin, have wider spacing intervals in fields. To be conservative for cucurbits, the crop that was thought to have the largest seeding rate (i.e., smallest seed) was chosen as a representative for the othe r cucurbits. Using seeding rates pro vid ed by BEAD (US EPA 2011 b ) the following equation was used to calculate paclobutrazol application rates in pounds of active ingredient per acre, for each of
the six crops:

(μg ai/seed)(1 lb ai/ 453,592,370 μg ai) * (seed or transplants/A) = lb ai/A

Using the seeding /transplant rates provided by BEAD (US EPA 2011 b )

, the following rates
are calculated:

Tomato = (12.5 μg ai/seed)*(1 lb ai/453,592,370 μg ai)*(14,400 seeds/A) = 0.00040 lb ai/A Pepper = (16 μg ai/seed) *( 1 lb ai/453,592,370 μg ai)*(22,400 seeds/A) = 0.00079 lb ai/A Cucurbits = (6.5 μg ai/seed)*(1 lb ai/453,592,370 μg ai)*(20,200 seeds/A) = 0.00029 lb ai/A Broccoli = (2 μg ai/seed)*(1 lb ai/453,592,370 μg ai)*(21,780 seeds/A) = 0.000096 lb ai/A
Cauliflower = (2 μg ai/seed)* (1 lb ai/453,592,370 μg ai)*(14,520 seeds/A) = 0.000064 lb
ai/A Cabbage = (2 μg ai/seed) *(1 lb ai/453,592,370 μg ai)*(29,040 seeds/A) = 0.00012 lb ai/A

These estimates are characterized as conservative because: 1) the maximum applicatio n rat e per seed is used for all six crops; 2) it includes mean maximum planting densities across the U.S. for all end uses of the crop. Often crops intended for processing are planted at higher
densities than that inte n d ed for fres h markets; 3) the range of the number of seeds per acre given in US EPA 2011b is upwardly biased because the presented values are based on the minimum row width and the maximum number of seeds per row foot. Growers plant to an overall density per acre based on local conditions, so as the row width shrinks, the distance between seeds increases; 4) in the case of cucurbits, only the seeding rates for cucumbers and33 summer squash were considered. If pumpkins and melons were to be included, the mean number of seeds per acre would be s u bstantially lower as these crops have more widely spaced plantings.

Pre

- Plant Plug/Liner Soak and Pre

- Plant Bulb Soaks
BEAD examined the Paczol label for information about pre

- plant plug/liner soaks and pre

plant bulb soak s . Specific use rates are not given for these methods because the rate is influenced by varying soak times, the extent of rooting for each plant, the media moisture levels, the differing sensitivities of cultivars and species being treated, cultural practices, and
environmental factors . BEAD did not have additional information to be able to calculate a per container application rate and therefore could not calculate an equivalent per acre application rate.

Although application rates for these methods could not be calculated, it is not expected that they would exceed the rates calculated for the soil drench or bench spray applications under greenhouse conditions , based on the label . Further, the registrant indicated that the bulb soaks are mainly for the cut flower trade and BEAD st ates that pre

- plant soaks for plug/liners are most frequently used when preparing containers for the retail market , which would resul t in negligible environmental exposures

.

Soil Drench and Bench Sprays (Potted Ornamentals) BEAD used the Bonzi II label (0 .036 g ai/fluid ounce of product) to calculate application rates for bench sprays and soil drenches. The label provides general information about the concentration of product to be used in spray or drench scenarios for specific types of plants (Table 4)

.

Table 4. Types of ornamentals and recommended c oncentrations on the Bonzi II l abel Plant Type Concentration of Spray (ppm) Concentration of Drench (ppm) Azaleas (florist) 100 to 200 5 to 15 Bedding plants 5 to 90 1 Bedding plant plugs 1 to 20 Not recommended Bulb crops “least desirable method” 5 to 200 Pot chrysanthemums 50 to 200 1 to 4 Flowering and foliage plants 30 to 50 1 to 2
Geraniums 10 to 30 “make with caution”
Hibiscus 30 to 150 4
Poinsettias 10 to 30 (15 to 45 in Florida) 2 to 4 Woody landscape plants 100 434 For bench spray calculations, plants in containers are placed as closely together as possible and two to three quarts of spray volume per 100 ft 2 are applied. Four

- hundred 6

- inch diameter containers can be packed onto a 100 ft 2 bench (5 ft x 20 ft). Approximately 79 percent of the applied spray will be deposited in the containers (area of containers [400*π*r 2 (78.5 ft 2 ) ÷ area sprayed (100 ft 2 ) = 78.53 percent]. This produces an application volume per 6

- inch container of 0.188 fluid ounces per pot (0.785*3 quarts spray per 100 ft 2 * 32 fluid ounces per quart * 100 ft 2 per 400 pots). Similarly, assuming that 224 8

- inch containers can be placed on a 100 ft 2 bench (4 ft x 25 ft), the application volume per 8

- inch container is 0.337 fluid ounces per pot. Finally, assuming that 88 liner trays may be placed
on a 100 ft 2 bench, the application volume per tray is 1.1 fluid ounces (3 quarts spray per 100
ft 2 * 32 fluid ounces per quart * 100 ft 2 per 88 trays). All of the applied spray is assumed to
be d eposited in the tray containers

.

For drenches, the label includes a table of volumes based on the size of the container. For example, 4 fluid ounces is a pplied to a 6

- inch pot and 10 fluid ounces is applied to an 8

- inch
pot.

To calculate the application rates, assumptions about the most likely pot sizes needed to be
made. There is considerable variation in the sizes of containers used in ornamental produ ctions. For example, a “#1” container, as designated by the American Nursery and Landscape Association (ANLA), is specified to contain between 152 and 251 in 3 (0.65 to 1.08 gallons) (ANLA, 2004). Dimensions of a # 1 container vary, with top diameter s ran ging from 6 inches to 8 inches. “Azalea pots” contain 132 in 3 and typically measure 5’ 7/8” (diameter) by 4’ 7/8” (height). The dimensions of propagation liner trays are 18’ 3/8” (width) by 9’ 3/16” and contain either 18 (i.e., 3 x 6) or 32 (i.e., 4 x 8) square cavities (Nursery Supplies 2011). Approximately 88 trays can be placed on a 100 ft 2 bench (6 ft x 16 and 2/3 ft).

BEAD also characterized the layout and density of pots in a typical nursery setting. Nurseries are designed to allow for an orderly movement of plants into and out of areas by workers and to allow access for the care of the plants. Yeager and Ingram (2010) describe a typical layout as having plant beds that are 8 ft wide, separated by 2 ft walkways. Equipment access is provided by a narrow road (10 to 20 ft wide) every 100 ft between the plant beds and by a 30 ft wide perimeter road. This layout results in approximately 50 percent of the area consisting of plant beds, with the remaining area in service roads and access paths.

Base d on this layout, the highest density possible (“can tight ” ) of 6

- inch containers in the plant bed area (50 percent of the total area) is 87,120 containers per acre. If 8

- inch containers are used instead, the overall density would be about 49,000 containe rs per acre ; 9 x 18 inch propagation trays yields 19,360 containers per acre

.35 BEAD used the following generic equation to calculate application rates:

(o z spray/ container)*(1 gallon spray/128 oz spray)*(oz formulation/gallon spray)*(1 gallon formulation/128 oz formulation)*(1 g ai/gallon formulation)*(1 lb ai/453.59 g ai)*(containers/A) = lb ai/A

BEAD calculated rates for the following scenarios using the maximum application rate of paclobutrazol (200 ppm solution

– spray and drench):

6

- inch pot (spray application)

– ( 0.188 oz spray/6

- inch pot )*( 1 gallon spray/128 oz )*( 20 oz formulation/gallon spray )*( 1 gallon formulation/128 oz formulation )*( 4.608 g ai/gallon
formulation )*( 1 lb/453.59 g )*( 87,120 6

- inch pots/A ) = 0.20 lb ai/A

6

- inch pot (drench)

– ( 4 oz drench/6

- inch pot ) * ( 1 gallon drench/128 oz drench ) * ( 20 oz formulation/gallon drench ) * (1 gallon formulation/128 oz formulation ) * ( 4.608 g/gallon
formulation ) * ( 1 lb/453.59 g ) * ( 87,120 6

- inch pots/A ) = 4.3 lb ai/A

8

- inch pot (spray)

– ( 0.337 oz spray/8

- inch pot ) * ( 1 gallon spray/128 oz spray ) * ( 20 oz formulation/gallon spray ) * ( 1 gallon formulation/128 oz formulation ) * ( 4.608 g/gallon
formulation ) * ( 1 lb/453.59 g ) * ( 49,000 8

- inch pots/A ) = 0.2 lb ai/A

8

- inch pot (drench)

– ( 10 oz drench/8

- inch pot ) * ( 1 gallon drench/128 oz drench ) * ( 20 oz formulation/gallon drench ) * ( 1 gallon formulation/128 oz formulation ) * ( 4.608 g/gallon
formulation ) * ( 1 lb/453.59 g ) * ( 49,000 8

- inch pots/A ) = 6.1 lb ai/A

18

- inch by 9

- inch propagation trays (spray)

– ( 1.1 oz spray/18

- inch by 9

- inch tray ) * ( 1 gallon spray/128 oz spray ) * ( 20 oz formulation/gallon spray ) * ( 1 gallon formulation/128oz
formulation ) * ( 4.608 g/gallon formulation ) * ( 1 lb/453.59 g ) * ( 19,360 18

- inch by 9

- inch trays/A ) = 0.26 lb ai/A

These are characte rized as conservative estimates because of the use of the maximum application rate per container and the highest density of containers in the plant beds.

Environmental Fate and Transport
S UMMARY OF E NVIRONMENTAL F ATE Paclobutrazol is a racemic mixture of the (2 R , 3 R )

- and (2 S , 3 S )

- enantiomers, but the submitted physiochemical and fate properties of e ach enantiomer were not investig ated in the submitted studies. Therefore, it is assumed that each enantiomer of paclobutrazol has similar physiochemical and f ate properties based on the submitted studies. Paclobutrazol has a low solubility (25.9 mg/L) in water. The vapor pressure (1.28 x 10 - 9 mm Hg at 25.0oC) and Henry’s Law Constant (8.09 x 10 - 10 atm m 3 /mol) indicate that the compound is relatively36 non

- volat ile under field conditions. The log K ow of 3.2 indicates the potential for this chemical to bioaccumulate in aquatic organisms

.

Paclobutrazol is stable to hydrolysis and photolysis. Under aerobic conditions, paclobutrazol appears to be generally quite p ersistent in acidic soils, with half

- lives greater than 300 days. However, in soils with neutral or higher pH, estimated half

- lives were as short as 25 days. In anaerobic aquatic metabolism studies, paclobutrazol variably partitioned to the sediment and degraded with a half

- life of more than one year in flood loam and silt loam soils. Since the extrapolated half

- liv es were beyond the duration of the experiment, paclobutrazol was considered stable in the anaerobic aquatic system. Paclobutrazol residues w ere persistent and mobile in terrestrial field dissipation studies in California, West Vir g inia, Florida, North Carolina, Illinois, and Mississippi. Half

- lives of paclobutrazol residues ranged from 450 to 950 days for orchard soils in California, West Vir ginia, and Florida, and 175 to 252 days in agricultural soils in Mississippi, North Carolina, and Illinois. The potential mobility of this

comp ound is quite variable, ranging from highly mobile to moderately mobile in soil, according to the mobility class ification of the Food and Agriculture Organization (FAO, 2000). Two major environmental degradates, ketone analog of paren t (CGA 149907, ≤ 40.0%) and 1H

- 1,2,4

- triazol

- 3

- ol (NOA457654, ≤ 25.1%) were identified in the
environmental fate and terrestrial fiel d dissipation studies. Based on laboratory and field studies, paclobutrazol has the potential to migrate into groundwater via leaching and surface water, mainly through runoff. Table 5 summarizes the physiochemical and environmental fate and transport properties of paclobutrazol

.

Table 5

. Summary of physical, chemical, and fate p roperties of p aclobutrazol

Parameter Value Reference Comments

Chemical Paclobutrazol MRID 456625

- 01

--- Chemical Class Triazole

--- CAS No. 76738

- 62

- 0

--- Empirical Formula C 15 H 20 Cl N 3 O MRID 456625

- 01

--- IUPAC ( 2 RS, 3 RS )

- 1

- (4

- chlorophenyl)

- 4,4

- dimethyl

2

- (1 H

- 1,2,4

- triazol

- 1

- yl)pentan

- 3

- ol MRID 456625

- 01

---

CAS Name (α R ,β R )

- rel

- β

- [(4

- chlorophenyl)methyl]

- α

- (1,1

- dimethylethyl)

- 1 H

1,2,4

- triazole

- 1

- ethanol MRID 456625

- 01

---

Structure MRID 456625

- 01

---37 Parameter Value Reference Comments

Selected Physical/Chemical Parameters

Molecular mass 293.8 g/mol MRID 456625

- 01

--- Solubility ( 20.0 °C) 25.9 m g/L (water) 2.8 g /L ( n

- Octanol ) 79.8 g/L ( methanol ) 5.22 g/L (xylene) MRID 456625

- 05
MRID 456625

- 03

---

Vapor pressure (25 .0 °C) 1.7 x 10 - 7 Pa (1.28 x 10 - 9 mm Hg) MRID 456625

- 05

---
Henry’s law constant (2 5 °C ) 8.2 x 10 - 7 Pa M 3 mol - 1 (8.09 x 10

- 12 atm M 3 mol - 1 ) MRID 456625

- 05

---

Octanol

- water partition coefficient (LogK OW ) (25°C) 3.18 MRID 456625

- 05

---

Persistence

Hydrolysis pH 4 : stable pH 7: stable pH 9: stable MRID 00132698

---

Aqueous Photolysis (t 1⁄2 ) Stable MRID 00132699

--- Soil Photolysis (t 1⁄2 ) Stable MRID 40685002 After 33 days paclobutrazol decrease to 86.4 % of applied radioactivity

Aerobic Soil Metabolism (t 1⁄2 ) Sandy clay l oam 19 (21 and 17) months 1 ,2 [47 (58 and 36 ) months ] 3 MRID 4 0685003 Major metabolite (CGA 149907 (≈18.7%)

Sandy clay loam 301 days [3 85 days] MRID 47338504 Supplemental

No major metabolites detected above 10%.

Sandy loam 26 days 4 [75.3 days] Major metabolites NOA 457654(25.1%) CGA 149907(13.3%)
Sandy loam 25 days 4 [55.9 days ] Major metabolites NOA 457654 (20.5%) CGA 149907(26.3%)

Anaerobic Soil Metabolism No data Anaerobic Aquatic Metabolism (t 1⁄2 ) Stable MRID 40685003 After a year of incubation, paclobutrazol decrease to ≤79% of applied radioactivity Major transformation product: (CGA 149907 (≈16.8%)

Aerobic Aquatic Metabolism No data

--

Mobility38 Parameter Value Reference Comments

Soil Partition Coefficient Adsorption K d (mL/g) 9.5 ( Clay loam ) 10.2 ( Sandy Clay loam )
7.6 ( Silty clay loam ) 17.3 ( Silt loam ) 5 4.1 (sandy loam) 2.4 (loamy sand) 5.8 (Silty clay) 1.4 (Sand) MRID 40685005 There was no significant correlation (r 2 = 0.12) between K d and % organic carbon.

Soil Partition Coefficient Desorption K des (mL/g) 6

15.6 ( Clay loam ) 18.1 ( Sandy Clay loam ) 14.0 ( Silty clay loam ) 34.0 ( Silt loam ) 5 5.1 (sandy loam) 10.4 (loamy sand) 2.7 (Silty clay) 6.1 (Sand) MRID 4 0685005

---

Adsorption K d (mL/g) 1.7 (Sandy loam) 5 0.8 (Sandy loam) 2.4 (Silty clay loam) 1.8 (Clay loam) Desorption K des (mL/g) 6 10.9 (Sandy loam) 5 3.81 (Sandy loam) 2.66 (Silty clay loam) 11.7 (Clay loam) MRID 47338504 Supplemental

Leaching Aged methine 14 C

- labeled paclobutrazol residues were relatively immobile

Aged trizole 14 C

- labeled paclobutrazol residues were mobile in loamy sand and clay loam soils and low mobility in sands and sandy loam soils MRID 40685004 Major transformation product CGA 149907 (≈12.6%)

Field Dissipation
Terrestrial Field Dissipation (t 1⁄2 ) 450 to 973 days (CA, WV, FL) MRID 40685006

- 406850012 Supplemental Major transformation product CGA 149907

88 days (CA) 133 days (NY) MRID 47338505 Supplemental Major transformation product

- CGA 149907 (40%)39 Parameter Value Reference Comments

1 Calculated half

- lives are based on 14 C labeled triazole and methane of paclobutrazol

2 Extrapolated half

- lives exceeded beyond the study period except soils with pH > 7.0

3 Italic half

- lives are calculated based on paclobutrazol and its major degradates (CGA 149907 and NOA 457654). Calculation can be found in Appendix B

. 4 High Soil pH (≥ 7.0) may have contributed faster degradation rates for aerobic soil metabolism

5 Japa nese soils, excluded during exposure assessment

6 Reported values are based on second desorption step

a. Degr a dation

In the terrestrial environment, paclobutrazol appears to be generally quite persistent in acidic soils, with h alf

- lives greater than 300 days; however, under certain conditions (soils with neutral or higher pH) estimated half

- lives are as short as 25 days. Triazole

- and methine

labeled paclobutrazol degraded with a half life of mor e than a year in loam soil (18 a cres, pH 6.6, organic matte r 4.6%). By the end of an entire incubation year, 54 percent of triazole

labeled and 50.4 percent of methine

- labeled parent were not degraded (MRID 40685003).

T wo transformation products were identified: CGA 149907 (ketone analog of parent) and 1,2,4

- tri azol. The major degradate of both test substance s was CGA 149907 at a maximum concentration of 15.0 and 16.8% of the applied.

The biotransformation of the t riazole ring was al so studied in three other soils (MRID 43455801): a sandy clay loam soil (18 a cres, pH 5.0, organic matter 4.5%), a sandy loam soil (Gartenacker, pH 7.1, organic matter 3.8%)

, and a sandy loam soil (Pappelacker, pH 7.0, organic matter 2.3%). Paclobutrazol degraded with half

- li ves of 301 days in the 18 a cres of sandy clay loam soil, 25 days in the Gartenacker sandy loam soil, and 26 days in the Pappelacker sandy loam soils. T wo transformation products were identified: CGA 149907
and H

- 1,2,4

- t riazol

- 3

- ol (NOA 457654). Both compounds were minor tra nsformation products in the 18 a cr es of sandy clay loam soil

, but major products (13.3 to 26. 3%) in the Gartenacker and Pappelacker sandy loam soils (Table 5 ) . Up to four unidentified minor transformation products were also detected; each accounted for ≤ 1.8% of the applied.

In aquatic systems, paclobutrazol is stable to hydrolysis and photolysis (MRIDs 00132698, 00132699)

. In anaerobic aquatic metabolism studies, paclobutrazol variably partitioned to
the sediment. Both triazole and methane labeled paclobutrazol degraded with a half

- l ife of more than one year in flood loam and silt loam. The estimations of half

- lives of paclobutrazol were not calculated because estimates involve extrapolation beyond the duration of experiment. At 1 year post treatment, 72.4 percent of triazole

- labele d and 60.5 percent of methine

- labeled parent were still present (MRID 40685003).40 b. Mobility and Transport

Batch equilibrium studies resulted in adsorption coefficients (K ads ) ranging from 0.8 to 17.3 ml/g with a median value of 3.74 ml/g for a wide range of soil textures (MRID 4188113 and 47338503). Values for K des ranged from 2.66 to 34.0 ml/g with a median value of 10.7 ml/ g (Table 5 ). Batch equilibrium results indicate that the mobility of paclobutrazol is quite variable, ranging from mobile to slightly mobile (FAO, 2000).

Soil column leaching experiments involving aged (9 week) residues of methine

- labeled paclobutrazol determined that the compound was relatively immobile in 30 cm columns of sand, sandy loam, loamy sand, and clay loa m soils leached with 66 cm of calcium chloride solution over 9 weeks. In contrast, aged residues of triazole

- labeled paclobutrazol determined the compound to be of low mobili ty in 30 cm columns of sand and sandy loam soils, and mobile in loamy sand and cl ay loam soils. In all cases, the majority (58.6

- 90.7 percent of the applied) of aged residue did not leach out of the upper 10 cm of the treated soil
columns.

c. Field Studies

Paclobutra zol resi d u es were persistent and mobile in terrestrial field dissip ation studies in California, West Virginia, Florida, North Carolina, Illinois, and Mississippi (Supplemental MRID 00155854, 40685007, 40685009, 40685010, 40685011, 4068512 and 40685006; and Pearson, 1985 no MRID). Paclobutrazol residues include paclobutra zol and its ketone
metabolite. Half

- lives of paclobutrazol residues ranged from 450

- 950 days for orchard soils in California, West Virginia, and Florida, and 25 weeks to 36 weeks in agricultural soils in Mississippi, North Carolina, and Illinois. Althoug h it was charact erized as mobile in some
soils in laboratory studies, no significant movement of paclobutrazol was detected in the agricul tural soils. In the orchard stud ies, paclobutrazol residues (parent plus degradate) were detected at 10 percent or le ss of total applied, in a soil depth of 48 inches in the California study, 24 inches in the West Virginia study, and 48 inches in the Florida study. Note that these depths are the maximum depths sampled at each study. The CGA 149907 metabolite was predomi nately detected in the subsurface soil layers, also at insignificant levels.

d

. Degradates

Two major environmental degradates, ketone analog of parent (CGA 149907, ≤ 40.0%) and

1H

- 1,2,4

- triazol

- 3

- ol (NOA457654, ≤ 25.1%) of paclobutrazol

, were identified in the environmental fate and terrestrial field dissipation studies

. Two minor degradates: CGA 710191(1H

- 1,2,4

- Triazole) and CGA 142856 (1,2,4

- Triazol

- 1

- yl

- acetic acid) were also
detected in environmental fate studies. NOA 457654 as well as these minor metabolites are common degradates of many triazole containing fungicides. Structures of major and minor degradates formed in various environmental fate studies were provided in Appendix C

.41 Selected environmental fate studie s suggest that NOA

- 457654 is n ot persistent under aerobic
soil condition s but highly mobile to mob i le ( Table 6 ). T he estimated DT 50 values for
NOA457654 of 8.5 days in th e 18 a cres sandy clay loam soil, 4.0 days in the Gartenacker silt loam soil, 10.4 days in the Borstel loamy sand soil, and 3.5 days in the Pappelacker sandy
loam soil were based on single first

- order (SFO) reaction kinetics

. Batch equilibrium studies
resulted in adsorption coefficients (K ads ) ranging from 0.13 to 0.30 ml/g with corresponding Koc values ranging fro m 8.1 to 13.0 ml/g (MRID 47338502). Values for K des ranged from 1.0 to 1.8 ml/g with cor re sponding K OC value s ranging from 66.5 to 74.6 ml/g. These results
indicate that NOA

- 457654 is highly mobile to mobile according to the mobility classification
of FA O ( 2000 )

. The time

- dependent sorption of NOA457654 was also investigated in four
soils

. I t was determined that the amount of radioactivity recovered in the soil pore water decreased constantly over time and ultimately reached amounts that were similar to those recovered in the desorption solutions. A rapid decrease in the amount of radioactivity

r ecovered during the initial 3 days was likely because complete equilibrium had not been achieved, and to the rapid biodegradation of NOA457654 (MRID 4733850 1 ).

Table 6 . Selected physical, chemical, and fate p roperties of NOA

- 457654

Parameter Value Reference Comments

Chemical NOA

- 457654 MRID 473385

- 01

--- Chemical Class Triazole MRID 473385

- 01

--- CAS No. 122442

- 66

- 4 MRID 473385

- 01

--- CAS Name 4H

- 1,2,4

- Triazol

- 3

- ol MRID 473385

- 01

--- IUPAC Name 1H

- 1,2,4

- Triazol

- 3

- ol. MRID 473385

- 01

--- Synonyms Hydroxytriazole, Triazole hydroxy, J7140/45/2 MRID 473385

- 01

---
Empirical Formula C 2 H 3 N 3 O MRID 473385

- 01

--- Molecular Weight 85.07 g/mole MRID 473385

- 01

---

Aerobic Soil Metabolism (t 1⁄2 ) Sandy clay loam soil 8.5 days MRID 473385

- 01 No major degradate except CO 2 Silt loam soil 4.0 days Loamy sand soil 10.4 days Sandy loam soil 3.5 days42 Parameter Value Reference Comments

Soil Partition Coefficient Adsorption K ads (mL/g) 0.13 (Loamy Sand) 0.25 (Loam) 0.19 (Sandy loam) 0.30 (Sandy loam) Adsorption K OC (mL/g) 8.9 (Loamy Sand) 10.7 (Loam) 8.1 (Sandy loam) 13.0 (Sandy loam) MRID 47338502 Calculated r 2 value for
K ads vs. % organic carbon content was 0.93and K ads vs. % clay was 0.8

Desorption K d es (mL/g) 1.0 ( Loamy Sand ) 1.7 ( Loam) 1.5 ( Sandy loam ) 1.8 ( Sandy loam) Adsorption K OC (mL/g) 72,7 ( Loamy Sand ) 74.6 ( Loam) 72.0 ( Sandy loam ) 66.5 ( Sandy loam) ---

e

. Bioaccumulation The log K ow of 3.2 indicates the potential for paclobutrazol to bioaccumulate in aquatic organisms; however, no acceptable bioaccumulation study is available at this time. KABAM ( K OW (based) A quatic B io A ccumulation M odel, Version 1.0) is used to estimate potential bioaccumulation of paclobutrazol in freshwater aquatic food webs and subsequent risks to mammals and birds via consumption of contaminated aquatic prey. Estimated
b ioconcentration factor (BCF) range s from 40 to 77 μ g/L (Table 12 of Appendix D ), and

sugges t s that the potential bioaccumulat ion of paclobutrazol in aquatic species is low. Estimated chronic RQ values for mammals and birds consuming fish contaminated by

p aclobutrazol are well bel ow the LOC (Table 16, Appendix D ). Model inputs and outputs

are p rovided in Appendix D

. Detailed model description can be obtained from following

URL

. http://www.epa.gov/oppefed1/models/water/kabam/kabam_user_guide.html#Section1_143 Receptors

E FFECTS TO O RGANISMS Registrant Submitted Studies for Paclobutrazol
The registrant (s) submitted studies include two fish acute toxicity stud ies

, one acute aquatic
invertebrate study , a fathead minnow early life

- stage study, one avian acute oral toxicity study

, two avian acute dietary studies, two avian reproduction studies

, an d one vegetative vigor terrestrial plant toxicity stud y (dicots only)

. Also submitted were an acute oral rat study and a two

- generation reproductive rat study. The acute toxicity studies testing fish

, freshwater invertebrates, and mammals demonstrated th at paclobutrazol is slightly toxic to these organisms ; paclobutrazol is practically non

- toxic to birds . The vegetative vigor study
dem onstrated toxicity to dicots, with t he tomato as the most sensitive species

.

Open Literature Studies Open literature studies from the ECOTOX database were reviewed for inclusion in the risk

assessment. F ive open literature paper s on paclobutrazol were included in this risk
assessment: effects to water flea ( Daphnia magna ) , green algae ( Selenastrum capric ornutum ) , mollusk ( Cipangopaludina chinensis ) , aquatic worm ( Limnodrilus hoffmeisteri )

, toad ( Bufo bufo gangarizas) , predatory mites ( Neoseiulus cucumeris and Orius
insidiosus ) , and two vascular aquatic plants ( Myriophyllum spicatum L. and Hydrilla
verticillata ). All acceptable and non

- acceptable papers and rationales of why they were not
included in the risk assessment are listed in Appendix E

.

The paclobutrazol effects data and the values used in the risk assessment and effects
determination are summarized in the Effects Characterization Section

.

I NCIDENT D ATABASE R EVIEW A review of the Ecological Incident Information System on September 23, 2011 (EIIS, version 2.1), which is maintai ned by the Agency’s Office of Pesticide Programs, the Aggregate Summary Module of OPP’s Incident Database, and the Avian Monitoring Information System ( AIM S), which is maintai ned by the Amer ican Bird Conservancy,
indicated several incidents associated with the use of paclobutrazol

.

According to Office of Pesticides Program Ecological Incident Information System (EIIS),

t he incident (Incident # I016555

- 001) was reported on 8/22/05 for three dead squirrels in Okeechobee County, Florida. Paclobutrazol (formulated product Profile 2SC) was applied
via soil in jection to ornamental and woody plants, a registered use. It was assumed that the squirrels had ingested the material after it had been applied; the application rate was not specified in the incident report. The incident was listed as “unlikely” to have been caused by paclobutrazol.44 There were two minor incidents listed in the Aggregate Summary Module of OPP’s Incident Database. The formulation, Profile 2SC, was associated with both of them. The first
incident occurred between 4/1/05 and 6/30/05 and was classified as a minor fish and wildlife
incident. The second occurrence was between 10/1/09 and 12/31/09 and was cl as sified as a minor plant incident. There were no paclobutrazol incidents reported in the AIMS database
and EFED is unaware of othe r in cidents outside of these three databases.

D ATA G APS I DENTIFIED The following toxicity data gaps have been identified :

• OPPTS 850.1025

- Oyster Acute Toxicity Test

• OPPTS 850.1035

- Mysid Acute Toxicity Test

• OPPTS 850.1075

- Acute Estuarine/Marine Fish Toxicity Test

• OPPTS 850.1300

- Freshwater (Aquatic) Invertebrate Life Cycle

• OPPTS 850.1350

- Mysid Chronic Toxicity Test

• OPPTS 850.1400

- Estuarine/Marine Fish Early

- Life Toxicity Test

• OPPTS 850.2100

- Acute Oral Toxicity Test with a Passerine Species

• OP PTS 850.3020

- Honey B ee Acute Contact Toxicity

• OPPTS 850.4225

- Seedling Emergence Tier II (ninety percent of the species tested in the submitted study exhibited a solvent effect)

• OPPTS 850.4250

- Vegetative Vigor Tier II

– monocots only ( monocots in the submitted toxicity study exhibited a solvent effect )

• OPPTS 850.5400

- A lgal Toxicity

– Tiers 1 and 2

E COSYSTEMS P OTENTIALLY AT R ISK The ecosystems at risk are often extensive in scope, and as a result it may not be possible to be specific at the screening level. Paclobutrazol is mainly registered for non

- food uses (turf, ornamental trees, shade trees, greenhouse transplants). It is also registered as a seed
treatment for tomatoe s, peppers, cucurbits, broccoli, cauliflower, and cabbage. I n general

terms, terrestrial ecosystems potentially at risk could include the treated trees/right

- of

- ways,45 golf courses, residences, treated field s, and areas immediately adjacent to the se that may receive drift or runoff. Areas adjacent to the treated areas could includ e cultivated fields, fencerows and hedgerows, meadows, fallow fields or grasslands, woodlands, riparian habitats
and other uncultivated areas.

Aquatic ecosystems potentially at risk include wa ter bodies adjacent to or downstream from
the treated area an d might include impounded bodies such as ponds, lakes and reservoirs, or flowing waterways such as streams or rivers. For uses in coastal areas, aquatic habitat also
includ es marine ecosystems and estuaries.

The previous problem formulation identified the areas with the greatest potential concern for
effects to non

- target organisms to be golf courses, plant nurseries, urban landscape areas, residential landscapes, road right

- of

- ways, and water bodies directly adjacent to treated areas that may receive c hemical residues via drift and/or runoff. An additional use as a seed

tr eatment for tomato, pepper, cucurbit , broccoli, cauliflower, and cabbage was registered after the pr oblem formulation was assembled.

For turf uses (golf course, parks, sports fields, etc.) , paclobutrazol is applied either as a spray or in granular form from a drop spreader at rates ranging from 0.1 to 0.75 lb ai/A. I t is expected that potential candidate sites for this paclobutrazol use extend to most areas of the
United States.

Tre e applications involve urban environments, utility right

- of

- ways, residential areas, and
other non

- crop areas. The compound may be applied as a basal drench in a trench surrounding the tree trunk

- soil intersection, soil injection to a depth of 3 to 6 inch es around the base of the tree, or direct injection into the tree trunk. Application rates for basal and soil
i njection range from 1 to 4 g ai per inch of diameter at breast height (DBH) and is tree species depende nt. Tree trunk inject ion s are similar. Given that the pesticide is t ransported through the plant via the x ylem, it is presumed that all or some of the applied pesticide will reach portions of the treated trees that are considered edible for wildlife. To evaluate the
poten tial ex posure to wildlife, assumption s of the concentrations of paclobutrazol in tree parts (e.g., mature leaves, buds, flowers, or fruits/seeds) following tree treatment will be important to the risk assessment. Given that no such data have been provided, a ran ge of simplifying assumptions for the concentrations of paclobutrazol in above ground structural parts of the tree will be assumed (i.e., concentration in the leaves as a surrogate for other non

woody food items ) . It is expected that potential candidate s ites for this paclobutrazol use
extends to most areas of the United States.

For potted ornamental uses, the pesticide is applied as an indoor or outdoor foliar spra y, bulb soak, pre

- plant plug and liner soak, and indoor soil drench. Labeling does not pr esent the46 application rates in terms of pounds of active ingredient per unit area for these uses , but the Biological and Economic Analysis Division (BEAD) has calculated rates (described in Terrestrial Exposure section) based on the labels’ descriptions ( B ecker, 2011 )

. The rates applied to greenhouse plant s may be conservatively used to assess potential exposures in the field once plants are transplanted. Such an assessment is accompanied by the conservative assumption that 100 percent of the applied pest icide is retained in soils prior to transplant and that plants are placed in the field to cover the entirety of the target landscape.

For tomato, pepper, cucurbit , broccoli, cauliflower, and cabbage uses, the labeled use
involves treatment of the seeds before planting in greenhouses. Specific rates are des ignated for each type of seed. Ecosystems near trans planted peppers, cucurbits, tomatoes , broccoli, cauliflower, and cabbage treated with paclobutrazol could be at risk.

Degradates
As discussed in th e environmental fate section

, paclobutrazol has two major degradates. Toxicity information specific to these degradates is not available; consequently, the assumption has been made that the degradates are as toxic as the parent, paclobutrazol.

Conceptual Model For a chemical to pose an ecological risk, it must reach ecological receptors in biologically significant concentrations. An expo sure pathway is the means by which a pesticide moves in the environment from a source to an ecological recept or. For an ecological exposure pathway to be complete, it must have a source, a release mechanism, an environmental transport medium, a point of exposure for ecological receptors, and a feasible route of

exposure.

The conceptu al model (Figures 1 and 2) d epi cts the potential pathways for ecological risk associated with paclobutrazol use. The conceptual model provides an overview of the expected exposure routes for organisms within the paclobutrazol action area. For terrestrial organisms, the major route of exposure considered is the dietary rout e ; consumption of food items such as plant leaves or insects that have paclobu t razol residues as a result of sprayi ng, seed treatment, drift, and translocation from soil or plant injection through xylem flow. It i s important t o note that since current screen ing risk assessment processes for wildlife exposure via treated vegetation do not address systemic pesticides, additional risk assessment characterization is needed to discuss interplant, and soil to plant trans fer. P aclobutrazol exposure to wildlife from tree injection, soil drench, root area injection, etc. could explore pesticide residues as either a uniform translocation to all above ground biomass, or translocation concentrating the material in fruits, seed s, and leaves of vegetation. Either approach could be employed to establish co

- exposure to herbivorous wildlife. Exposure through inhalation is unlikely given paclobutrazol’s low vapor pressure and the results of47 EFED’s Screening Tool for Inhalation Risk (STIR v. 1.0). EFED’s Screening Imbibition Program (SIP v. 1.0) indicated a potential chronic risk to mammals through the consumption of drinking water, but the actual concern for this exposure pathway is low because of paclobutrazol’s tendency to adhere to the soil substrate, with only a fraction of it being available for leaching (Appendix G ). Exposure could occur through guttation water, which would primarily be a concern for terrestrial invertebrates.

For aquatic animal species, the major routes of exposure are considered to be via the respiratory surface (gills) or the integument.

Direct contact and/or root uptake is the major route of exposure for terrestrial and wetland (riparian) plants, while aquatic plants may be exposed via direct uptake and adsorption. Estimated exposure concentrations for all organisms are obtained through the use of several Agency exposure models.

** Route of exposure includes only ingestion of fish and aquatic invertebrates Stressor

Source

Receptors

Attribute Change Paclobutrazol Applications to Turf, Trees, Ornamentals, Tomatoes, Peppers, and Cucurbits

Spray drift a

Aquatic animals Invertebrates Vertebrates **Piscivorous mammals and birds

Individual organisms Reduced survival Reduced growth Reduced reproduction Food chain Reduction in algae and

vascular plants Reduction in prey Modification of PCEs

related to prey availability Habitat integrity Reduction in primary productivity Reduced cover Community change Modification of PCEs related to

habitat Surface water/

Sediment Runoff b

Aquatic Animals Invertebrates Vertebrates Exposure Media

Uptake/gills or integument

Ingestion Ingestion Atmospheric transport

Wet/dry deposition Soil Leaching to Groundwater

Uptake/gills or integument

Aquatic Plants Non

- vascular Vascular Uptake/cell, roots, leaves Riparian plants terrestrial
exposure pathways see

Figure 2 Injection into Plant c

Figure 1. Conceptual model for the aquatic effects of paclobutrazol applications. Dotted
lin es indicate the pathway is not expected to be significant. a Not expected for tree injection, soil injection, greenhouse soil drench, or seed treatments. b Not expected for tree injection.

c Injection to plan t will require an estimate of translocation to edible portions of the plant.48 Stressor

Source

Attribute Change Paclobutrazol Applications to Turf, Trees, Ornamentals, Tomatoes, Peppers, and Cucurbits

Direct application Spray drift

Terrestrial vertebrates Terrestrial

Inverts

Individual organisms Reduced survival Reduced growth Reduced reproduction Food chain Reduction in prey and food Modification of PCEs related to prey availability Habitat integrity Reduction in primary productivity Reduced cover Community change Modification of PCEs related

to habitat Terrestrial plants grasses/forbs, fruit, seeds (trees, shrubs) Runoff

Terrestrial vertebrates Exposure Media & Receptors Soil

Ingestion Ingestion Dermal uptake/Ingestion Atmospheric transport

Root uptake/contact
Wet/dry deposition

Ingestion Leaching to Groundwater Irrigation

water

Figure 2. Conceptual model for the terrestrial effects of paclobutrazol applications.

Risk Hypothesis

For paclobutrazol , the following ecological risk hypothes es are being tested in th e risk

assessment:

Terrestrial Environment

• Exposure to paclobutrazol residues on insects, seeds, foliage , and other plant parts
from direct deposition , tree injection, seed treatment, or spray drift from labeled use of the pesticide has the potential to cause reduced survival, growth and reproduction

to t errestrial vertebrates (birds, mammals, reptiles, terrestrial

- phase amphibians) and
terrestrial invertebrates

.

• Exposure to paclobutr azol residues on foliage , roots, or other plant parts from spray drift alone or from runoff from labeled use of the pesticide has the potential to result

in reduced survival and biomass to u pland plants and r iparian/wetland plants in a reas adjacent to a tr eated area

.49 Aquatic Environment

• Exposure to paclobutrazol residues in water from spray drift , soil drenches/injections,

or runoff from labeled uses of the herbicide has the potential to cause reduced survival, growth and reproduction to a quatic inverte brates and fish in surface waters adjacent to a treate d area.

• Exposure to paclobutrazol residues in water from spray drift , soil drenches/injections,
or runoff from labeled uses of the pesticide has the potential to cause reduced survival
and biomass to a quatic vascular and non

- vascular plants in surface wa ters adjacent to
a treated area

.

Analysis Plan In registration r eview, pesticide ecological risk assessments will follow the Agency’s Guidelines for Ecological Risk Assessment and will be in compliance with the paper titled “Overview of the Ecological Risk Assessment Process in the Office of Pesticide Programs, U.S. Environmental Protection Agency” ( US EPA

, 2004 )

.

The focus of an ecological risk assessment is on both the toxic effects of a pesticide to non

target organisms and the potential routes of the pesticide’s exposure to non

- target organisms. In addition to addressing a pesticide’s toxic effects and potential routes of exposure, an ecological risk assessment addresses the uncer tain ties associated with a pesticide’s risk to

non

- target organisms.

M EASURES TO E VALUATE THE R ISK H YPOTHESIS AND C ONCEPTUAL M ODEL Measures of exposure are based on aquatic and terrestrial models that predict estimated environmental concentrations (EECs) of paclobutrazol us ing maximum labeled application rates and methods of application. The model s used to predict aquatic EECs are the PRZM [ P esticide R oot Z one M odel (PRZM v3.12.2 ) ] and EXAMS [ EX posure A nalysis M odeling
S ystem (v2.98.4.6 ) ] model s . The model used to predict terrestrial EECs on food items is T

REX [ Terrestrial Residue Exposure Model version 1. 4 .1 ( Oct. 9, 2008) ] . The model used to derive EECs relevant to terrestrial and wetland plants is TerrPlant [ Version 1.2.2 (10/29/09) ]

.

M EASURES OF E FFECT
Data identified in the Effects Characterization Section are used as measures of effect for
direct and indirect effects to non

- target organisms. Data were obtained from registrant
submitted studies or from open literature studies identified by ECOTOX. The ECOTOXicology database (ECOTOX) was searched to provide more ecological effects data and to bridge existing data gaps. ECOTOX is a source for locating single chemical toxicity data for aquatic life, t errestrial plants, and wildlife and is maintained by the USEPA, Office50 of Research and Development, and the National Health and Environmental Effects Research Laboratory's Mid

- Continent Ecology Division

.

The acute measures of effect used for animals in this screening level assessment are the LD 50 , LC 50 a nd EC 50 . LD stands for "Lethal Dose", and LD 50 is the amount of a material, given all at once, that is estimated to cause the death of 50% of the test organisms. LC stands for
“Lethal Concentration” and LC 50 is the concentration of a chemical that is est imated to kill 50% of the test organisms. EC stands for “Effective Concentration” and the EC 50 is the concentration of a chemical that is estimated to produce a specific effect in 50% of the test organisms. Endpoints for chronic measures of exposure for listed and non

- listed animals are
the NOAEL/NOAEC and NOEC. NOAEL stands for “No Observed

- Adverse

- Effect

- Level” and refers to the highest tested dose of a substance that has been reported to have no harmful (adverse) effects on test organisms. The NOAEC ( i.e. , “No

- Observed

- Adverse

- Effect

Concentration”) is the highest test concentration at which none of the observed effects were statistically different from the control. The NOEC is the No

- Observed

- Effects

Concentration. For non

- listed plants, only acute exposures are assessed ( i.e. , EC 25 for terrestrial plants and EC 50 for aquatic plants).

**I NTEGRATION OF**  **E XPOSURE AND**  **E FFECTS**  Risk characterization is the integration of exposure and ecological effects characterization to determine the potential ecologic al risk from agricultural and non

- agricultural uses of paclobutrazol , and the likelihood of direct and indirect effects to non

- target organisms in aquatic and terrestrial habitats. The exposure and toxicity effects data are integrated to
evaluate the risk s of adverse ecological effects on non

- target species. For the assessment of paclobutrazol risks, the risk quotient (RQ) method is used to compare exposure and measured toxicity values. EECs are divided by acute and chronic toxicity values. The resultin g RQs are then compared to the Agency’s levels of concern (LOCs) (US EPA

, 2004).

There is no established acute listed or non

- listed LOC for terrestrial invertebrates. The LOCs currently in use for birds, mammals and aquatic species are based on 1975 re gulations for the enforcement of FIFRA (40 CFR Part 154: 49005; 49007; 49016). Refer to Appendix H for
addition information on the LOCs.

A NALYSIS OF C O
- OCCURANCE OF F EDERALLY L ISTED S PECIES WITH P ACLOBUTRAZOL Consistent with the Agency’s responsibility u nder the Endangered Species Act (ESA), the Agency will evaluate risks to f ederally

- listed threatened and/or endangered (listed) species from registered uses of paclobutrazol . This assessment will be conducted i n accordance with the Overview Document (US EPA

, 2004), provisions of the ESA, and the Services’ Endangered Species Consultation Handbook (U.S. FWS/NMFS

, 1998).51 In the case of a nationwide risk assessment conducted under Registration Review, the action area will encompass the entire U.S. and its te rritories to ensure that the initial area of consideration encompasses all areas where the pesticide may be used now and in the future, including the potential for off

- site transport via spray drift and downstream dilution. Additionally, the concept of a nationwide action area takes into account the potential for direct and indirect effects and any potential modification to critical habitat based on ecological effect measures associated with reduction in survival, growth, and reproduction, as
well as the f ull suite of sub

- lethal effects available in the effects literature.

It is important to note that the nationwide action area does not imply that direct and/or indirect effects and critical habitat modification are expected to or are likely to occur over the full extent of the action area, but rather to identify all listed species and critical habitat that may potentially be affected by the action. The Agency will use more rigorous analysis including consideration of available land cover data, toxicity da ta, and exposure information to determine areas where individual listed species and designated critical habitat may be affected or modified via endpoints associated with reduced survival, growth, or reproduction. The Information Management System (IMS), a work product of the industry

- based FIFRA Endangered Species Task Force (FESTF) w ill be used to evaluate the co

- occurrence of listed species and critical habitat within the paclobutrazol action area. FESTF was formed to fulfill data requirements relative to species/pesticide use proximity.52 

# Exposure Assessment

Aquatic Exposure Assessment

Monitoring Data

Paclobutrazol is not included as one of the analytes monitored in the U.S. surface and groundwater under the USGS’s National Water Quality Assessment (NAWQA) program. There were no available monitoring data at the time of this assessment ( January 201 2 ).

Aquatic Exposur e Modeling

S creening

- level surface water exposure s for aquatic risk assessment were conducted for all of the registered uses except seed treatments. It is assumed that aqua tic exposure from paclobutrazol’s agricultural use s would be insignificant s ince t he application rates of seed

treatments a re several orders of magnitude lower than ornamentals and turf uses

. Modeled application rates represent the maximum use pattern of the proposed label for use on
ornamentals and turf. The aquatic exposure estimate s presented in this assessment we re based on the use of models because no surface or groundwater monitoring data are available for paclobutrazol within the continental U.S. Two major environmental degradates, CGA 149907 (maximum of 40.4%) and NOA457654 (m aximum of 25.1%) were identified in the environmental fate and terrestrial field dissipation studies

. T here are no toxicity data related to aquatic species as well as no environmental fate properties for these major degradates to exclude any of the degradate s listed above. Therefore, a total toxic residue (parent plus degradates of concern) approach is included and expected to provide protective exposure estimation for aquatic organisms exposed to the major degradates of paclobutrazol

. In addition, aquatic exposure was also estimated for parent (paclobutrazol) only.

PRZM/EXAMS

T he model Pesticide Root Zone Model (PRZM v3.12.2 ) linked with EXposure Analysis Modeling System (EXAMS v2.98.4.6 ) via the model shell PRZM/EXAMS (PE v5.0, Nov.
15 , 2006 ) w as run to estimate baseline

- level expo sures for representative crop scenarios. The PRZM model simulates pesticide movement and transformation on and across the agricultural field resulting from crop applications. The EXAMS model simulates pesticide
loadi ng via runoff, erosion, and spray drift assuming a “standard” 1

- ha pond, 2

- m deep (20,000 m 3 ) with no outlet that borders a 10

- ha treated field. Simulations are run for multiple (usually 30) years, and the Agency estimates peak and running mean values tha t are expected once every ten years based on the daily values generated during the simulation. The coupled53 PE model s and users manuals are available from the U.S. Environmental Protection Agency

Wa ter Models web

- page (U.S. EPA, 2011 ).

Exposure estimates generated using this “standard” pond are intended to represent a wide variety of vulnerable water bodies that occur at the top of watersheds including prairie pot holes, playa lakes, wetlands, vernal pools, man

- made and natural ponds, and intermittent and
first

- order streams. As a group, there are factors that make these water bodies more or less vulnerable than the standard surrogate pond. Static water bodies that have larger ratios of pesticide

- treated drainage area to water body volume would be expecte d to have higher peak EECs than the standard pond. These water bodies will be either smaller in size or have large drainage areas. Smaller water bodies have limited storage capacity and thus may overflow and carry pesticide in the discharge, whereas the standard pond has no discharge. As watershed size increases, it becomes increasingly unlikely that the entire watershed is planted
with a non

- major single crop that is all treated simultaneously with the pesticide. Headwater streams can also have peak co ncentrations higher than the standard pond, but they likely persist for only short periods of time and are then carried and dissipated downstream.

Paclobutrazol can be applied as either a spray or as a drench. The O verview of Pesticide Use and Usage sect ion described earlier provided various application methods and applica tion rates for paclobutrazol. A summary of inputs used to estimate paclobutrazol concentrations in the aquatic systems for ecological risk assessment are listed in Table 7

.

Table 7 . P RZM

- EXAMS input parameter values for p aclobutrazol

Parameter Value Source Comments

Application Rate (lb ai /A) 2.50 lb a i/A (based on 59% retention of parent in soil

column) 1

0.55 lbs/A ( based on

91 % retention of parent in soil column

2.0 lbs/A for turf 2 Memo from the Biological and Economic Analysis Division (BEAD) (US EPA, 2011)

Product Label Maximum application rate w as estimated based on information provided by BEAD

(US EPA 2011) and adjusted with the

retention of paclobutrazol in a soil column leaching study (MRID 40685004)

EPA Reg No. 100

- 1079

Number of Applications 1 (Nursery) 3 (Turf) Product Label EPA Reg No. 100

- 1079

Application frequency (days) Drench

– None Foliar

- 14 Product Label EPA Reg No. 100

- 107954 Parameter Value Source Comments

Scenarios Ornamentals CA Ornamentals STD FL Ornamentals STD MI Ornamentals STD NJ Ornamentals STD OR Ornamentals STD TN Ornamentals STD
T urf FL Turf STD PA Turf STD Selected ornamental scenarios were chosen to represent various regions of the Continental United States

Application Date Ornamentals

– 01 (Mar

– Sept) 3

Turf

FL Turf

- 15 (Feb

Sept) 4 PA Turf 15 (Apr

Sept) 5 ---

Spray Drift

Fraction Drench

- 0 Ground foliar

- 0.1 Model input guidance (US EPA, 2010) --- Application Efficiency Drench

- 1.0 Ground Foliar

- 0.99 Model input guidance (US EPA, 2010) --- Soil Partitioning Coefficient (K d ml/g) 4.5 MRID s 4188113 and 47338503 Mean value

Aerobic Soil Metabolism t 1/2 (d) 1003.2 (Total residue) 6 444.2 (Parent) 6 MRID s 40685003 and 47 338504 90 th percentile upper confidence bound on the mean.

Method of Application Drench Ground Paclobutrazol labels ---

Spray Drift Fractions 0 (drench) 6.4 (ground foliar) Paclobutrazol labels Model input guidance (US EPA, 2010) Solubility in Water (mg/L) 25.9 MRID 456625

- 05

---

Aerobic Aquatic Metabolism t 1/2 (days) 2006.4 (Total Residue) 888.4 (Parent) 2X of Aerobic soil metabolism half

- life Model input guidance (US EPA, 2010)

Hydrolysis t 1/2 0 MRID 00132698 Stable to hydrolysis

Aquatic Photolysis t 1/2 (days) 0 MRID 0013299 Stable to aquatic photolysis55 Parameter Value Source Comments

1 Example of application rate calculation: 6.1 lbs/A

- (6.1lbs/A*0.59) Where

6.1 lbs/A is application rate for drench application for 8

- inch container grown ornamentals (US EPA, 2011) 0.59 is the minimum fraction of retention of parent (paclobutrazol) in column leaching study (MRID 40685004)

2 Maximum single application rate of 0.67 lbs/A was used instead of 0.75 lbs/A to account maximum seasonal rate of 2.0 lbs/A due to Tier I m odel limitation. Model accepts only uniform rate for multiple applications.

3 I n absence of application date from the label, model simulations were performed from March to September with date of application first of the month

4 In absence of application d ate in label, model simulations were performed from February to September with date of application 15 th of the month

5 In absence of application date in label, model simulations were performed from March to September with date of application 15 th of the month

6 S ome of the estimated half

- li ves (Table 5) are beyond the study period and can be considered as stable.
Howeve r , to use 90 th percentile of the de gradation rate in the modeling, all estimated half

- lives were considered

A quatic Exposure Modeling Results

The aquatic EECs for the various scenarios and application methods are listed in Table 8

. In
the absence of a specific application schedule for ornamentals and turf

, the “M ulti Run”
function of the PE5 model was used to generate EECs for multiple application dates. Table 8 below provides a range of EECs for the parent only, and total toxic residue s ; A ppendix I provides detailed results.

Table 8 . Range of estimated environmental concentrations (EECs) of total r esidue (paclobutrazol plus degradates) and paclobutrazol for surface w ater

Aquatic Exposure (model) Use Scenario (modeled rate) Environmental Column Peak EEC ( μg/L ) 21

- Day EEC ( μg/L ) 60

- Day EEC ( μg/L )
Total Toxic Residue (Paclobutrazol plus CGA 149907 and NOA 457654 ) 1

Surface Water (PRZM/EXAMS) Ornamentals: CA Ornamentals STD FL Ornamentals STD MI Ornamentals STD NJ Ornamentals STD OR Ornamentals STD
TN Ornamentals STD (1app. X 2.50 lbs ai/acre) Water 0.04

- 13 146

- 333 198

- 301

- 143

- 247

52

- 103 146

- 258 0.04

- 13 145

- 332 197

- 301 143

- 256 52

- 103 145

- 257 0.04

- 13 140

- 331 197

- 197 142

- 255 52

- 103
144

- 25656 Aquatic Exposure (model) Use Scenario (modeled rate) Environmental Column Peak EEC ( μg/L ) 21

- Day EEC ( μg/L ) 60

- Day EEC ( μg/L )
Total Toxic Residue (Paclobutrazol plus CGA 149907 and NOA 457654 ) 1

Ornamentals: CA Ornamentals STD FL Ornamentals STD MI Ornamentals STD NJ Ornamentals STD OR Ornamentals STD
TN Ornamentals STD (1app. X 0.56 lbs ai/acre) 0.01

- 2.8 32

- 74 44

- 67 32

- 57
12

- 23 32

- 57 0.01

- 2.8 32

- 74 44

- 67 32

- 57
12

- 23 32

- 57 0.01

- 2.8 32

- 73 44

- 66 32

- 57
12

- 23 32

- 57

Turf FL Turf STD PA Turf STD (3app. [ 2 app.x 0.75lbs and 1app x 0.5lbs ] ai/acre) 39

- 21 68

- 35 39

- 21 68

- 35 39

- 21 68

- 35

Parent Paclobutrazol only 2

FL Ornamentals STD (1app. X 2.50 lbs ai/acre)

Water 187 184 184

PA Turf STD (3app. [ 2 app.x 0.75lbs and 1app x 0.5lbs ] ai/acre) 51 51 51

1 To tal toxic simulation includes two degradates, CGA 149907 and NOA457654 )

2 Exposure of parent only based on highest exposure scenarios (FL Ornamentals STD and PA Turf STD) identified from total toxic residue simulations

The ecological pond modeled with EXAMS is a static water body of fixed volume with no
outlet. Since paclobutrazol is persistent in aquatic environments and the ecological pond has no outlet, there was a modeled accumulation of paclobutrazol in the pond th roughout the 30 year simulation ( as shown in Figure 1 ) for paclobutrazol applied to FL Nurse ry . Exposure endpoint s, in this assessment, are based on yearly peak concentrations. In the case of persistent compounds, a 1

- in

- 10 year EEC from PRZM/EXAMS does not reflect varying meteorological conditions that are expected once every 10 years, since the yearly peaks are

no t independent but are actually correlated to the previous year’s peak concentration. The
linked PRZM/EXAMS model runs simulate the effe ct of daily weather on the treated agricultural field over a period of thirty years. During this time, pesticide is was hed

- off of the field into the water body by twenty to forty rainfall/runoff events per year. Each new addition of pesticide to the water body adds to the pesticide which has arrived earlier either through previous runoff events or through spray

- drift and begins degrading on the day it
reaches the water.57 Figure 3. PRZM/EXAMS acute EECs for paclobutrazol applied to Florida nursery with selected aquatic toxicity assessment endpoints



### Terrestrial Exposure

Dietary

- Based Paclobutrazol Residue Levels The Agency uses the 

### T

- REX model (v1.4.1, USEPA, Oct. 9, 2008) to estimate the terrestrial animal exposure values resulting from possible dietary ingestion of paclobutrazol residues on vegetative matter and insects present on non

- food and fo od crops from exposure to paclobutrazol

. In all screening

- level assessments, the organisms are assumed to consume 100% of their diet as one food type. This model incorporates the Kenaga nomograph, as modified by Fletcher et al. (1994), which is based on a large set of actual field residue data. The upper limit values from the nomograph represented the 95th percentile of residue values from actual field measurements (Hoerger and Kenaga, 1972). The Terrestrial Residue Exposure Model version 1. 4 .1 (T

- REX) w as employed to estimate (1) EECs for different food items for birds and mammals, (2) dose/diet based risk to birds as well as dose based risk to mammals, and (3) EECs for small insects were used to estimate risk to terrestrial
invertebrates from d irect contact (Table 9 )

.

Results of the T

- REX v1.4.1 modeling of paclobutrazol residue levels on those dietary food items which potentially occur on some treated fields, for mammals, birds 4 , and terrestrial

4 B irds are also used as a surrogate for reptiles and terrestrial

- phase amphibians

.58 invertebrates are provided in Table s 10

– 12

. Residue levels for dietary items were calculated for the turf, and spray applications to potted ornamentals

.

Results include dietary

- based values [ i.e ., milligrams of paclobutrazol pe r kilogram of diet (mg/kg

- diet)] , and both an upper

- bound and mean esti mate of these exposure levels. The

upper

- bound values are derived using the upper

- bound Kenaga nomogram which used the highest of the highest normalized residue values from a number of studies, as a tolerance limit approach.

As birds are also used as a surrogate for reptiles and terrestrial

- phase amphibians within this assessment, it is assumed that dose

- based exposure levels for these animals are the same as birds ( i.e ., food ingestion rate per body weight for a bird is the same as for an amphibian and reptile). However, reptiles and amphibians have a lower ingestion rate for a given body weight than birds (US EPA

, 1993). Therefore, the dose

- based EECs presented here represent an overestimate of exposure for reptiles and amphibians of a given body size

.

Table 9 . Input p arameters for T

- REX m odeling s cenarios

Use Maximum Application Rate (lb ai/A) Number of Applications (Interval between Applications, days) Source (other labels have same or lower application rates) Other Parameters

Herbaceous and ornamentals (greenhouse) 0.26 (spray) 1 Bonzi II 100

- 1079 Foliar half life = 35 days Avian NOAEC

– 453 mg ai/kg

- diet (bobwhite quail) Mammal LD 50 = 1336 mg ai/kg

- bw (rat) Mammal NOEL = 2.5 mg ai/kg

- bw (rat) Turf 0.75 3 (28) 1 Profile 2SC 67690

- 00022

1 3 applications at 0.75 lb ai/A exceeds the maximum seasonal rate of 2 lb ai/A by 0.25 lb ai/A. A T

- REX scenario was run with 3 applications at 0.66 lb ai/A. Risk quotients were ~12% lower, but none of the exceeding risk quotients were reduced below the l evel of concern. Thus the higher application rate was used for this assessment to ensure that it was maximally protective.59 Table 10 . Avian p aclobutrazol upper bound EEC v alues for spray applications to turf and potted o rnamentals

Feeding Category Dietary

based EECs (mg/kg

- food item) Dose

- based EECs (mg/kg

- bw)

Small (20 g) Medium (100 g) Large (1000 g)

Profile 2SC on Turf

– 3 applications at 0.75 lb ai/A (28 day interval) 1
Short grass 342.76 390.37 222.61 99.66 Tall grass 157.10 178.92 102.03 45.68 Broadleaf plants/small insects 192.80 219.58 125.22 56.06 Fruits/pods/seeds/large insects 21.42 24.40 13.91 6.23 Granivores

- 5.42 3.09 1.38 Bonzi II Spray for Potted Ornamentals

– 1 application at 0.26 lb ai/A Short grass 62.40 71.07 40.53 18.14 Tall grass 28.60 32.57 18.57 8.32 Broadleaf plants/small insects 35.10 39.98 22.80 10.21 Fruits/pods/seeds/large insects 3.90 4.44 2.53 1.13 Granivores

- 0.99 0.56 0.25

1 3 applications at 0.75 lb ai/A exceeds the maximum seasonal rate of 2 lb ai/A by 0.25 lb ai/A. A T

- REX scenario was run with 3 applications at 0.66 lb ai/A. Risk quotients were ~12% lower, but none of the exceeding risk quotients were reduced below the l evel of concern. Thus the higher application rate was used for this assessment to ensure that it was maximally protective.

Table 11 . Mammalian p aclobutrazol upper bound EEC v alues for spray a p plications to turf and potted o rnamentals

Feeding Category Dietary

based EECs (mg/kg

- food item) Dose

- based EECs (mg/kg

- bw)

Small (15 g) Medium (135 g) Large (1000 g)

Profile 2SC on Turf

– 3 applications at 0.75 lb ai/A (28 day interval) 1
Short grass 342.76 326.80 225.86 52.37 Tall grass 157.10 149.78 103.52 24.00 Broadleaf plants/small insects 192.80 183.82 127.05 29.46 Fruits/pods/seeds/large insects 21.42 20.42 14.12 3.27 Granivores

- 4.54 3.14 0.73 Bonzi II Spray for Potted Ornamentals

– 1 application at 0.26 lb ai/A60 Feeding Category Dietary

based EECs (mg/kg

- food item) Dose

- based EECs (mg/kg

- bw)

Small (15 g) Medium (135 g) Large (1000 g)

Short grass 62.40 59.49 41.12 9.53 Tall grass 28.60 27.27 18.85 4.37 Broadleaf plants/small insects 35.10 33.47 23.13 5.36 Fruits/pods/seeds/large insects 3.90 3.72 2.57 0.60 Granivores

- 0.83 0.57 0.13

1 3 applications at 0.75 lb ai/A exceeds the maximum seasonal rate of 2 lb ai/A by 0.25 lb ai/A. A T

- REX scenario was run with 3 applications at 0.66 lb ai/A. Risk quotients were ~12% lower, but none of the exceeding risk quotients were reduced below the l evel of concern. Thus the higher application rate was used for this assessment to ensure that it was maximally protective.

Table 12

. Adult insect foliar spray upper

- bound EEC v alues

Use EEC (based on arthropod) (mg/kg

- diet) (dose in μg ai/bee *) 1

Profile 2SC on Turf 1 app at 0.7 5 lb ai/A 2 101.25 ( 12.9 )

Bonzi II Spray for Potted Ornamentals 1 app at 0. 26 lb ai/A 35.10 ( 4.5 )

*Conversion made by multiplying EEC by body weight of adult bee (0.128 g)

1 Based on single app at the highest single application rate because application interval is >5 days

2 3 applications at 0.75 lb ai/A exceeds the maximum seasonal rate of 2 lb ai/A by 0.25 lb ai/A. A T

- REX scenario was run with 3 applications at 0.66 lb ai/A. Risk quotients were ~12% lower, but none of the exceeding risk quotients were reduced below the level of concern. Thus the higher application rate was used for this assessment to ensure that it was maximally protective.

EEC Estimates for Tree Injection, Soil Injection, Tree Drench, and Po tted Ornamentals (Drench)

T

- REX could not be used to calculate EEC s for tree injection, basal (tree) drench, and potted
ornamental drenches. T

- REX assumes that the chemical is applied over the tops of the plants and that terrestrial organisms are exposed to the chemical via the residues left on plant parts. The residues will degrade over time as they are exposed to environmental conditions. For injections and drenches , paclobutrazol is taken up into the plant via the roots or direct injection into the t ree. Terrestrial organisms can still be exposed to paclobutrazol through eating leaves or other plant parts, but the chemical is contained within the vegetation61 (systemic) rather than on the vegetation’s surface. Therefore, different methods were employe d to estimate the concentrations of paclobutrazol in plants, based on the application
method.

Tree Injection, Soil Injection/ Tree Drench, and Woody Potted Ornamental Drench Leaf
Biomass Estimates

An EEC is the concentration of paclobutrazol that is expected to be present in a unit of food. Therefore, to calculate an EEC, it is necessary to determine the biomass of the food item and the amount of paclo butrazol it is expected to contain.

For tree injection, soil/injection/ tree drenches, and woody p otted ornamental drenches, it is assumed that paclobutrazol will accumulate in the leaves of the plant (a surrogate for other

non

- woody food items such as fruit) . Both hardwoods and softwoods were considered in this
scenario. Leaf biomass (dry weight) fo r hardwoods and softwoods were estimated using general hardwood and softwood leaf biomass equations from Jenkins et al. (2003).

General hardwood equation for dry weight (Sollins et al., 1973)

ln leaf biomass (kg) =

- 3.862 + 1.74*(ln(dbh 1 ))

For the tree injection and soil injection /tree drench scenario, a diameter at breast height ( DBH ) of 6 inch es (15.24 cm) is used. This DBH was selected based on BEAD’s assumption that the average sized tree in an acre of urban trees has a DBH of 6 inches (Becker, 201 1).

ln leaf biomass (kg) =

- 3.862 + 0*15.24 + 1.74*(ln(15.24 1 )) ln leaf biomass (kg) =

- 3.862 + 0 + 4.74 ln leaf biomass (kg) = 0.878

L eaf biomass = e 0.878 = 2.4 kg

The correction for bias when converting from ln to arithmetic units = 1.34 (Sollins et al

., 1973). Therefore:
Leaf biomass = 2.4*1.34 = 3.216 kg dry weight

For leaves, 85 percent (mean) of the wet weight is water (USEPA, 1993); therefore, the general equation to convert leaf dry weight into wet weight is:

Leaf w et weight = (100% total leaf weight) *( kg of leaf dry weight) / ( % leaf dry weight )

Hardwood leaf wet weight = (100%)*(3.216 kg) / (15%)62 Hardwood (6

- inch DBH ) leaf wet weight = 21.44 kg wet weight

A similar calculation is performed for the woody potted ornamental drench sce nario; however, a DBH of 1 inch (2.54 cm) is assumed because woody potted ornamentals are
small.

ln leaf biomass (kg) =

- 3.862 + 0*2.54 + 1.74*(ln(2.54 1 )) ln leaf biomass (kg) =

- 3.862 + 0 + 1.621 ln leaf biomass (kg) =

- 2.241

L eaf biomass = e - 2.241 = 0.106 kg

The correction for bias when converting from ln to arithmetic units = 1. 34 (Sollins et al., 1973). Therefore:

L eaf biomass = 0.106*1.34 = 0.142 kg dry weight

For leaves, 85 percent of the wet weight is water (USEPA, 1993); therefore, the general equation to convert leaf dry weight into wet weight is:

W et weight = (100% total weight) *( kg of dry weight) / ( % dry weight )

Hardwood leaf wet weight = (100%)*(0.142 kg) / (15%)
Hardwood (1

- inch DBH ) leaf wet weight = 0.95 kg wet weight

General softwood equation for dry weight (Sollins et al., 1973)

ln leaf biomass (kg) =

- 2.907 + 0*dbh + 1.674*(ln(dbh 1 ))

For the tree injection and soil injection /tree drench scenario, a DBH of 6 inch es (15.24 cm) is
used. This DBH was selected based on BEAD’s assumption that the average sized tree in an

acre of trees has a DBH of 6 inches (Becker, 2011).

ln leaf biomass (kg) =

- 2.907 + 0*15.24 + 1.674*(ln(15.24 1 )) ln leaf biomass (kg) =

- 2.907 + 0 + 4.56 ln leaf biomass (kg) = 1.653

L eaf biomass = e 1 .653 = 5.222 kg

The correction for bias when converting from ln to arithmetic units = 1.34 (Sollins et al., 1973). Therefore:

L eaf biomass = 5.222*1.34 = 7 kg dry weight63 For leaves, 85 percent of the wet weight is water (USEPA, 1993); therefore, the general equation to convert leaf dry weight into wet weight is:

W et weight = (100% total weight) *( kg of dry weight) / ( % dry weight )

Softwood leaf wet weight = (100%)*(7 kg) / (15%)
Softwood (6

- inch DBH ) leaf wet weight = 47 kg wet weight

A similar calculation is performed for the woody potted ornamental drench scenario; however, a DBH of 1 inch (2.54 cm) is assumed because woody potted ornamentals are
small.

ln leaf biomass (kg) =

- 2.907 + 0*2.54 + 1.674*(ln(2.54 1 )) ln leaf biomass (kg) =

- 2.907 + 0 + 1.56 ln leaf biomass (kg) =

- 1.347

L eaf biomass = e - 1.347 = 0.26 kg

The correction for bias when converting from ln to arithmetic units = 1.34 (Sollins et al., 1973). Therefore:

L eaf biomass = 0.26*1.34 = 0.35 kg dry weight

For leaves, 85 pe rcent of the wet weight is water (USEPA, 1993); therefore, the general equation to convert leaf dry weight into wet weight is:

W et weight = (100% total weight) *( kg of dry weight) / ( % dry weight )

Softwood leaf wet weight = (100%)*(0.35 kg) / (1 5%)
Softwood (1

- inch DBH ) leaf wet weight = 2.3 kg wet weight

Table 13

. Summary of hardwood and softwood leaf biomass wet w eights

6

- Inch DBH (kg) 1

- Inch DBH (kg)

Hardwood (wet weight) 21.44 0.95

Softwood (wet weight) 47 2.3

Using the information in Table 13

, EECs can be calculated for tree injection, soil injection/ tree drench, and woody potted ornamental drench applications.

Tree Injection64 Becker (2011) established that the application rate for tree injection or tree drench treatments
as 0.36 lb ai/A. He made the assumption that on average, there would be 36 trees per acre.
Thus:

(0.36 lb ai/A) / (36 trees/A) = 0.01 lb ai/tree

Conversion to mg = (0.01 lb ai)*(453592 mg ai/lb) = 4536 mg ai/tree

It is assumed that the ent ire application of paclobutrazol will accumulate in the leaves (a surrogate for other non

- woody food items such as seeds) of the tree. To determine the dietary concentration (EEC) of paclobutrazol in the leaves of hardwoods and softwoods, the paclobutrazo l application per tree is divided by the leaf biomass ( Table 13 ).

Hardwoods = (4536 mg ai/tree) / 21.44 kg = 212 mg ai/kg

- leaves Softwoods = (4536 mg ai/tree) / 47 kg = 9.4 mg ai/kg

- leaves

The EECs must be adjusted for mammal body weight. The T

- REX analysis uses three size classes for mammals: 15, 35, and 1000g. According to the T

- REX User’s Manual, a 15 g mammal consumes 95 percent of its body weight daily, a 35 g mammal consumes 66 percent of its body weight daily, and a 1000 g mammal consumes 15 percent of its body weight daily. Consequently, the general equation for determining the dose of paclobutrazol received per day is:

EEC mg ai/kg

- bw = (dietary concentration mg ai/kg

- diet)*(body weight consumption kg

diet/kg

- bw)

Hardwoods
15 g mammal EEC = (212 mg ai/kg

- diet)*(0.95 kg

- diet/kg

- bw) = 201 mg ai/kg

- bw 35 g mammal EEC = (212 mg ai/kg

- diet)*(0.66 kg

- diet/kg

- bw) = 140 mg ai/kg

- bw 1000 g mammal EEC = (212 mg ai/kg

- diet)*(0.15 kg

- diet/kg

- bw) = 32 mg ai/kg

- bw

Softwoods 15 g mammal EEC = (9.4 mg ai/kg

- diet)*(0.95 kg

- diet/kg

- bw) = 9 mg ai/kg

- bw 35 g mammal EEC = (9.4 mg ai/kg

- diet)*(0.66 kg

- diet/kg

- bw) = 4.2 mg ai/kg

- bw 1000 g mammal EEC = (9.4 mg ai/kg

- diet)*(0.15 kg

- diet/kg

- bw) = 1.4 mg ai/kg

- bw

Soil Injection and Tree Drench Risk Becker (2011) established that the application rate for tree injection or tree drench treatments as 1.9 lb ai/A. He made the assumption that on average, there would be 36 trees per acre.
Thus:65 (1.9 lb ai/A) / (36 trees/A) = 0.5 lb ai/tree

C onversion to mg = (0.5 lb ai)*(453592 mg ai/lb) = 22680 mg ai/tree

It is assumed that the entire application of paclobutrazol will accumulate in the leaves (a surrogate for other non

- woody food items such as fruit) of the tree. To determine the dietary

c oncentration (EEC) of paclobutrazol in the leaves of hardwoods and softwoods, the paclobutrazol application per tree is divided b y the leaf biomass (see Table 13 for values).

Hardwoods = (22680 mg ai/tree) / 21.44 kg = 1058 mg ai/kg

- leaves Softwoods = (22 680 mg ai/tree) / 47 kg = 483 mg ai/kg

- leaves

The EECs must be adjusted for mammal body weight. The T

- REX analysis uses three size classes for mammals: 15, 35, and 1000 g. According to the T

- REX User’s Manual, a 15 g mammal consumes 95 percent of its b ody weight daily, a 35 g mammal consumes 66 percent of its body weight daily, and a 1000 g mammal consumes 15 percent of its body weight daily. Consequently, the general equation for determining the dose of paclobutrazol received per day is:

EEC mg ai/kg

- bw = (dietary concentration mg ai/kg

- diet)*(body weight consumption kg

diet/kg

- bw)

Hardwoods 15 g mammal EEC = (1058 mg ai/kg

- diet)*(0.95 kg

- diet/kg

- bw) = 1005 mg ai/kg

- bw 35 g mammal EEC = (1058 mg ai/kg

- diet)*(0.66 kg

- diet/kg

- bw) = 698 mg ai/kg

- bw 1000 g mammal EEC = (1058 mg ai/kg

- diet)*(0.15 kg

- diet/kg

- bw) = 159 mg ai/kg

- bw

Softwoods 15 g mammal EEC = (483 mg ai/kg

- diet)*(0.95 kg

- diet/kg

- bw) = 459 mg ai/kg

- bw 35 g mammal EEC = (483 mg ai/kg

- diet)*(0.66 kg

- diet/kg

- bw) = 319 mg ai/kg

- bw 1000 g mammal EEC = (483 mg ai/kg

- diet)*(0.15 kg

- diet/kg

- bw) = 72 mg ai/kg

- bw

Woody Potted Ornamental Drench Becker (2011) established that the highest application rate for drench applications to potted ornamentals is 6.1 lb ai/A. He made the assumption that on average, 49,000 8

- inch pots would fit into an acre of outdoor storage space at a nursery. Thus:

(6.1 lb ai/A) / (49,000 pots/A) = 0.00012 lb ai/tree66 Conversion to mg = (0.00012 lb ai)*(453592 mg ai/lb) = 56 mg ai/tree

It is assumed that the ent ire application of paclobutrazol will accumulate in the leaves (a surrogate for other non

- woody food items such as flowers) of the tree. To determine the dietary concentration (EEC) of paclobutrazol in the leaves of hardwoods and softwoods, the paclobutra zol application per tree is divided b y the leaf biomass (see Table 13 for values).

Hardwoods = (56 mg ai/tree) / 0.95 kg = 59 mg ai/kg

- leaves Softwoods = (56 mg ai/tree) / 2.3 kg = 24 mg ai/kg

- leaves

The EECs must be adjusted for mammal body weight. The T

- REX analysis uses three size classes for mammals: 15, 35, and 1000 g. According to the T

- REX User’s Manual, a 15 g mammal consumes 95 percent of its body weight daily, a 35 g mammal consumes 66 percent of its body weight daily, and a 1000 g mammal con sumes 15 percent of its body weight daily. Consequently, the general equation for determining the dose of paclobutrazol received per day is:

EEC mg ai/kg

- bw = (dietary concentration mg ai/kg

- diet)*(body weight consumption kg

diet/kg

- bw)

Hardwoods 15 g mammal EEC = (59 mg ai/kg

- diet)*(0.95 kg

- diet/kg

- bw) = 56 mg ai/kg

- bw 35 g mammal EEC = (59 mg ai/kg

- diet)*(0.66 kg

- diet/kg

- bw) = 39 mg ai/kg

- bw 1000 g mammal EEC = (59 mg ai/kg

- diet)*(0.15 kg

- diet/kg

- bw) = 9 mg ai/kg

- bw

Softwoods 15 g mammal EEC = ( 24 mg ai/kg

- diet)*(0.95 kg

- diet/kg

- bw) = 23 mg ai/kg

- bw 35 g mammal EEC = (24 mg ai/kg

- diet)*(0.66 kg

- diet/kg

- bw) = 16 mg ai/kg

- bw 1000 g mammal EEC = (24 mg ai/kg

- diet)*(0.15 kg

- diet/kg

- bw) = 3.6 mg ai/kg

- bw

Non

- Woody Potted Ornamental Drench Applications Leaf biomass equations were not available for non

- woody plants. Therefore, the assumption was made that the entire application of paclobutrazol would concentrate in the plant.

Becker (2011)’s 6.1 lb ai/A was used to calculate the concentr ation (EEC) of paclobutrazol per plant. 49,000 8

- inch pots are expected to fit into an acre of storage area at a typical nursery. Thus,

(6.1 lb ai/A) / 49,000 = 0.0012 lb ai/plant67 Conversion to mg = (0.00012 lb ai)*(453592 mg ai/lb) = 56 mg ai/plant

I t is assumed that the entire application of paclobutrazol will accumulate in the plant and that the average weight of a plant is 0.5 kg. Thus, to calculate the dietary concentration (EEC) of paclobutrazol in a plant, the paclobutrazol application per plan t is divided by its weight (0.5 kg).

(56 mg ai/plant) / 0.5 kg = 112 mg ai/kg

- plant

The EECs must be adjusted for mammal body weight. The T

- REX analysis uses three size classes for mammals: 15, 35, and 1000 g. According to the T

- REX User’s Manual, a 1 5 g mammal consumes 95 percent of its body weight daily, a 35 g mammal consumes 66 percent of its body weight daily, and a 1000 g mammal consumes 15 percent of its body weight daily. Consequently, the general equation for determining the dose of paclobutr azol received per day is:

EEC mg ai/kg

- bw = (dietary concentration mg ai/kg

- diet)*(body weight consumption kg

diet/kg

- bw)

15 g mammal EEC = (112 mg ai/kg

- diet)*(0.95 kg

- diet/kg

- bw) = 106 mg ai/kg

- bw 35 g mammal EEC = (112 mg ai/kg

- diet)*(0.66 kg

- diet/kg

- bw) = 74 mg ai/kg

- bw 1000 g mammal EEC = (112 mg ai/kg

- diet)*(0.15 kg

- diet/kg

- bw) = 17 mg ai/kg

- bw

Table 14. Summary of mammalian and avian EECs for tree i njection, soil
i njection/ tree drench, potted woody ornamental drench, and potted non

- woody

o rnamenta l drench u ses
Bird Mammal Dietary (mg ai/kg

- plant) Acute Dose (mg ai/kg

- bw) 15 g 35 g 1000g Tree Injection Hardwood 212 201 140 32

Tree Injection Softwood 9.4 9 4.2 1.4

Soil Injection/Drench Hardwood 1058 1005 698 159

Soil Injection/Drench Softwood 483 459 319 72

Potted Woody Ornamental Drench 59 56 39 968 Bird Mammal Dietary (mg ai/kg

- plant) Acute Dose (mg ai/kg

- bw) 15 g 35 g 1000g
Hardwood Potted Woody Ornamental Drench Softwood 24 23 16 3.6

Potted Non

- Woody Ornamental Drench 112 106 74 17

EEC Estimates for Seed T reatment to Tomato, Pepper, Cucurbits , Broccoli, Cauliflower, Cabbage Treated seeds remain in greenhouse settings until they are large enough to be transplanted to commercial agricultural fields. To evaluate potential risks to terr estrial species from this use, the assumption is being made that the entire treatment of paclobutrazol that was applied to the seed before planting is still present in the plant when a bird or mammal might consume it in the field. It is not expected that terrestrial organisms would have direct access to the
treated seed because the seeds are being planted in a greenhouse

.

It is assumed that the entire application of paclobutrazol will accumulate in the plant. Latimer (1992) reports the average dry weight of a 7

- week old tomato transplant as 1120 mg. Data specific to cucurbits, peppers , broccoli, cauliflower, and cabbage were not available, so the tomato data were used to approximate the weight of these other crops, as well.

For plants, 80 percent of t he wet weight is water (USEPA, 1993); therefore, the general equation to convert leaf dry weight into wet weight is:

W et weight = (100% total weight) *( kg of dry weight) / ( % dry weight )

Transplant wet weight = (100%)*(1120 mg) / (20%) Transplant = (5600 mg)*(1g / 1000 mg)*(1 kg / 1000 g) = 0.0056 kg wet weight

To calculate the dietary concentration (EEC) of paclobutrazol in a plant, the paclobutrazol application per plant is divided by its weight (0.0056 kg). Maximum paclobutrazol

app lications per seed (and thus, per plant) are: tomato

– 0.0125 mg ai/seed; cucurbit

– 0.0065 mg ai/seed; pepper

– 0.016 mg ai/seed. Thus:

Tomato EEC = (0.0125 mg ai/plant) / (0.0056 kg) = 2.2 mg ai/kg

- plant Cucurbit EEC = (0.0065 mg ai/plant) / (0.0056 k g) = 1.2 mg ai/kg

- plant Pepper EEC = (0.016 mg ai/plant) / (0.0056 kg) = 2.9 mg ai/kg

- plant69 Broccoli EEC = ( 0.002 mg ai/plant) / (0.0056 kg) = 0.36 mg ai/kg

- plant Cauliflower EEC = ( 0.002 mg ai/plant) / (0.0056 kg) = 0.36 mg ai/kg

- plant Cabbage EEC = ( 0.002 mg ai/plant) / (0.0056 kg) = 0.36 mg ai/kg

- plant

The EECs must be adjusted for mammal body weight. The T

- REX analysis uses three size classes for mammals: 15, 35, and 1000 g. According to the T

- REX User’s Manual, a 15 g mammal consumes 95 percent of its body weight daily, a 35 g mammal consumes 66 percent of its body weight daily, and a 1000 g mammal consumes 15 percent of its body weight daily. Consequently, the general equation for determining the dose of paclobutrazol received per day is:

EEC mg ai/kg

- bw = (dietary concentration mg ai/kg

- diet)*(body weight consumption kg

diet/kg

- bw)

Tomato 15 g mammal EEC = (2.2 mg ai/kg

- diet)*(0.95 kg

- diet/kg

- bw) = 2.1 mg ai/kg

- bw 35 g mammal EEC = (2.2 mg ai/kg

- diet)*(0.66 kg

- diet/kg

- bw) = 1.5 mg ai/kg

- bw

1 000 g mammal EEC = (2.2 mg ai/kg

- diet)*(0.15 kg

- diet/kg

- bw) = 0.33 mg ai/kg

- bw

Cucurbit 15 g mammal EEC = (1.2 mg ai/kg

- diet)*(0.95 kg

- diet/kg

- bw) = 1.1 mg ai/kg

- bw 35 g mammal EEC = (1.2 mg ai/kg

- diet)*(0.66 kg

- diet/kg

- bw) = 0.79 mg ai/kg

- bw 1000 g mamma l EEC = (1.2 mg ai/kg

- diet)*(0.15 kg

- diet/kg

- bw) = 0.18 mg ai/kg

- bw

Pepper 15 g mammal EEC = (2.9 mg ai/kg

- diet)*(0.95 kg

- diet/kg

- bw) = 2.8 mg ai/kg

- bw 35 g mammal EEC = (2.9 mg ai/kg

- diet)*(0.66 kg

- diet/kg

- bw) = 1.9 mg ai/kg

- bw 1000 g mammal EEC = (2.9 mg ai/kg

- diet)*(0.15 kg

- diet/kg

- bw) = 0.44 mg ai/kg

- bw

Broccoli 15 g mammal EEC = (0.36 mg ai/kg

- diet)*(0.95 kg

- diet/kg

- bw) = 0.34 mg ai/kg

- bw 35 g mammal EEC = (0.36 mg ai/kg

- diet)*(0.66 kg

- diet/kg

- bw) = 0.24 mg ai/kg

- bw 1000 g mammal EEC = (0.36 mg ai/kg

- diet)*(0.15 kg

- diet/kg

- bw) = 0.05 mg ai/kg

- bw

Cauliflower 15 g mammal EEC = (0.36 mg ai/kg

- diet)*(0.95 kg

- diet/kg

- bw) = 0.34 mg ai/kg

- bw 35 g mammal EEC = (0.36 mg ai/kg

- diet)*(0.66 kg

- diet/kg

- bw) = 0.24 mg ai/kg

- bw
1000 g mammal EEC = (0.36 mg ai/kg

- diet)*(0.15 kg

- diet/kg

- bw) = 0.05 mg ai/kg

- bw70 Cabbage 15 g mammal EEC = (0.36 mg ai/kg

- diet)*(0.95 kg

- diet/kg

- bw) = 0.34 mg ai/kg

- bw 35 g mammal EEC = (0.36 mg ai/kg

- diet)*(0.66 kg

- diet/kg

- bw) = 0.24 mg ai/kg

- bw 1000 g mam mal EEC = (0.36 mg ai/kg

- diet)*(0.15 kg

- diet/kg

- bw) = 0.05 mg ai/kg

- bw

Table 15 . Summary of mammalian and a vian EECs for seed t reatments

Bird Mammal Dietary (mg ai/kg

- plant) Acute Dose (mg ai/kg

- bw) 15 g 35 g 1000g

Tomato 2.2 2.1 1.5 0.33 Cucurbit 1.2 1.1 0.79 0.18 Pepper 2.9 2.8 1.9 0.44
Broccoli 0.36 0.34 0.24 0.05
Cauliflower 0.36 0.34 0.24 0.05 Cabbage 0.36 0.34 0.24 0.05

Off

- Field Terrestrial and Wetland/Riparian Plant Paclobutrazol Exposure
TerrPlant 1.2.2 (10/29/09) was used a s a Tier 1 model for screening level assessments of pesticides. The m odel provide s estimates of exposure to terrestrial plants fro m single pesticide applications; however, t he model does not consider exposures to plants from multiple pesticide application s. TerrPlant derives pesticide EECs in runoff and in spray drift

, and develops risk quotients for non

- listed and listed species of monocots and dicots inhabiting dry and semi

- aquatic areas

.

Paclobutrazol can be applied a number of differe nt ways, depending on its use. See Appendix J for TerrPlant’s input for each scenario.

For turf, it was assumed that the application would take place in situ (i.e. on lawns) via ground application. Spray drift is assumed and soil incorporation is expected to be less than
1 inch.

For the soil injection/basal drench for ornamental trees, paclobutrazol is injected directly into
the soil at depths of 3 to 6 inches (soil injection) or can be applied vi a a drench around the base of the tree (basal drench). For the latter, the label stipulates that if there is a risk for runoff, the paclobutrazol should be applied via a shallow trench around the base of the tree.
Clean soil should be used to cover the t rench. Based on these application methods , a soil incorporation depth of 3

- inches and zero spray drift were incorporated into the TerrPlant
model.71 For the seed treatments (tomato, pepper

, cucurbits , broccoli, cauliflower, cabbage ), the label implies that seeds are treated in greenhouses with the intention to transplant young plants for commercial agriculture. To model this, the assumption has been made that the paclobutrazol applied to the seed coat was not absorbed by the seed and is now evenly disperse d in the pot of soil. Exposure occurs when the seedling is transplanted into an agricultural field. For this scenario, TerrPlant assumed no risk of spray drift and a paclobutrazol incorporation depth of
3

- inches (the depth of a transplant pot).

For the spray and drench treatments to potted ornamentals, plants are treated in a greenhouse setting. Many of the varieties listed on the label are commonly planted outdoors as ornamentals. For both the spray and drench scenarios, zero spray drift is expected b ecause: 1) applications take place within greenhouses; and 2) drift is not expected for a drench application method.

Tre e injections were not modeled because paclobutrazol is injected directly into the plant and there is no opportunity for exposure via r unoff or spray drift.

The estimated e xposure concentrations of paclobutrazol for terrestrial plant s are presented below (Table 16 ). The most protective application scenarios for each use were selected,
based on information from the label.

Table 16

. T errestrial plant exposure c onc entration e stimates for p aclobutrazol
Description Equation EEC (lb ai/A) Profile 2SC on Turf

– 1 ground application at 0.75 lb ai/A Runoff to dry areas (A/I)*R 0.0055
Runoff to semi

- aquatic areas (A/I)*R*10 0.055 Spray drift A*D 0.0055 Total for dry areas ((A/I)*R)+(A*D) 0.011
Total for semi

- aquatic areas ((A/I)*R*10)+(A*D) 0.0605 Paclobutrazol 2SC Soil Injection /Basal Drench for Ornamental Trees

– 1 application at 3 inches deep at 1.9 lb ai/A Runoff to dry areas (A/I)*R 0.012666667
Runoff to semi

- aquatic areas (A/I)*R*10 0.126666667 Total for dry areas ((A/I)*R)+(A*D) 0.012666667
Total for semi

- aquatic areas ((A/I)*R*10)+(A*D) 0.126666667 Paclobutrazol 2SC Seed Treatment for Cucurbits

– 1 application at 3 inches deep at 0.00029 lb ai/A Runoff to dry areas (A/I)*R 0.000001 9 Runoff to semi

- aquatic areas (A/I)*R*10 0.00001 9 Total for dry areas ((A/I)*R)+(A*D) 0.000001 9 Total for semi

- aquatic areas ((A/I)*R*10)+(A*D) 0.00001 972 Description Equation EEC (lb ai/A) Paclobutrazol 2SC Seed Treatment for Pepper

– 1 application at 3 inches deep at 0.00079 lb ai/A Runoff to dry areas (A/I)*R 0.0000053
Runoff to semi

- aquatic areas (A/I)*R*10 0.000053 Total for dry areas ((A/I)*R)+(A*D) 0.0000053
Total for semi

- aquatic areas ((A/I)*R*10)+(A*D) 0.000053 Paclobutrazol 2SC Seed Treatment for Tomato

– 1 application at 3 inches deep at 0.00040 lb ai/A Runoff to dry areas (A/I)*R 0.0000027
Runoff to semi

- aquatic areas (A/I)*R*10 0.000027 Total for dry areas ((A/I)*R)+(A*D) 0.0000027
Total for semi

- aquatic areas ((A/I)*R*10)+(A*D) 0.000027 Paclobutrazol 2SC Seed Treatment for Broccoli

– 1 application at 3 inches deep at 0.000096 lb ai/A Runoff to dry areas (A/I)*R 0.00000064
Runoff to semi

- aquatic areas (A/I)*R*10 0.0000064 Total for dry areas ((A/I)*R)+(A*D) 0.00000064
Total for semi

- aquatic areas ((A/I)*R*10)+(A*D) 0.0000064 Paclobutrazol 2SC Seed Treatment for Cauliflower

– 1 application at 3 inches deep at 0.000064 lb ai/A Runoff to dry areas (A/I)*R 0.00000043
Runoff to semi

- aquatic areas (A/I)*R*10 0.0000043 Total for dry areas ((A/I)*R)+(A*D) 0.00000043
Total for semi

- aquatic areas ((A/I)*R*10)+(A*D) 0.0000043 Paclobutrazol 2SC Seed Treatment for Cabbage

– 1 application at 3 inches deep at 0.00012 lb ai/A Runoff to dry areas (A/I)*R 0.0000008
Runoff to semi

- aquatic areas (A/I)*R*10 0.000008 Total for dry areas ((A/I)*R)+(A*D) 0.0000008
Total for semi

- aquatic areas ((A/I)*R*10)+(A*D) 0.000008 Bonzi II Spray for Potted Ornamentals for Transplant

– 1 application at 0.26 lb ai/A Runoff to dry areas (A/I)*R 0.0052
Runoff to semi

- aquatic areas (A/I)*R*10 0.052 Total for dry areas ((A/I)*R)+(A*D) 0.0052
Total for semi

- aquatic areas ((A/I)*R*10)+(A*D) 0.052
Bonzi II Drench for Potted Ornamentals for Transplant

– 1 application at 6.1 lb ai/A Runoff to dry areas (A/I)*R 0.122
Runoff to semi

- aquatic areas (A/I)*R*10 1.22 Total for dry areas ((A/I)*R)+(A*D) 0.122
Total for semi

- aquatic areas ((A/I)*R*10)+(A*D) 1.22
A = application rate I = incorporation73 Description Equation EEC (lb ai/A)
R = runoff fraction D = drift fractionChapter 3 Effects Characterization

7

4 

# Effects Characterization

Several paclobutrazol toxicity studies were submitted by the registrant since the Registration
Review Revised Paclobutrazol Final Work Plan ( US EPA

, 2007) : fish early

- life stage, avian reproduction (mallard duck and bobwhite quail), vegetative vigor, and seedling emergence. The fish early

- life stage and two avian studies were classified as “acceptable” and filled data

gap s in the ecotoxicologica l risk picture. The plant studies both exhibited solv ent effects and only the dicot da ta from the vegetative vigor were determined to be reliable enough to be
used in a risk assessment

There were three open literature stud ies on the effects of paclobutrazol that were used quantitatively in this assessment: an acute water flea study, an aquatic vascular plant study (hydrilla and Eurasian watermilfoil ) , and an acute aquatic organisms study (water flea, green algae, aquatic tubificid worm, Asiatic toad, and neonate grass carp). In addition, there was a predatory mite study that was used qualitatively in this assessment. There were other open literature studies and articles referencing paclobutrazol, but these were not included in this

assessment because toxicity results were less sensitive than registrant submitted data , or the information was not appropriate for inclusion for a variety of reasons including the venue provided insufficient scientific information to evaluate and validate findings ( e .g ., abstract, review), the doses were not convertible into units used in risk assessment models, or the article was not pertinent to toxicity and effects ( e.g. , analytical methods). Paclobutrazol results that were found in the open literature and passed the initial screen but which were not used in the assessment and the reasons for their exclusion are provided in Appendix E

.

Finally, even with the additional information from the open literature, a number of toxicity data gaps still remain. These includ e: estuarine/marine fish and invertebrates (acute and chronic), freshwater invertebrate (chronic), seedling emergence (monocot and dicot),

ve getative vigor (monocot), honey bee (acute contact), and vascular aquatic plants. To address each gap , toxicity da ta were used from other triazoles that were similar in structure to paclobutrazol (Appendix F )

. In situations where paclobutrazol data were available, the toxicity values for chemically similar triazoles were compared with the paclobutrazol data.
There w ere no consistent patterns of toxicity. Paclobutrazol was the most toxic of the triazoles for terrestrial plants, but not the most toxic in other scenarios. No single triazole emerged as being consistently toxicologically similar to paclobutrazol, and th us an appropriate surrogate in itself.

Crystal Ball (2000 version 5.0) was used to create a fitted lognormal distribution to the surrogate data running a Monte Carlo sampling scheme (10,000 trials). The 5 th percentile of
the data was calculated and used in the risk assessment. Not every triazole had a complete set of data, so the chemicals and number of data points varied for each paclobutrazol data gap. This approach was chosen as it was thought to be conservative; however, it is possibleChapter 3 Effects Characterization

75 that for any given endpoint, the triazole

- calculated paclobutrazol surrogate could have
underestimated the risk.



### Terrestrial Vertebrate Toxicology

Information is available on acute oral dose and dietary

- based effects of and chronic toxicity
of paclobutrazol in birds . Paclobutrazol is classified as practically non

- toxic to birds, based
on the LD 50 ; however a passerine acute oral toxicity study was not available. Reproduction studies were conducted for both the mallard duck and the bobwhite quail. The bobwh ite quail was twice as sensitive to paclobutrazol compared with the mallard duck. The most
sensitiv e bobwhite quail toxicity value was adult female body weight gain while the most sensitive parameters for the mallard duck were the ratio of live 3

- week emb ryos to viable embryos, the ratio of hatchlings to eggs set, the ratio of hatchlings to live 3

- week embryos, and the ratio of hatchling survivors to eggs set.

Information is available on the acute oral dose and chronic effects of paclobutrazol on
mammal s. An acute oral toxicity study with rats established LD 50 values for both male and
female rats. Chronic toxicity values were based on increased liver weights and on fatty change in the liver of female rats ; and increased incidence of chromodacryorrhea a nd thickened eyelids, dental malocclusion, increased liver weights, mottling or accentuation of the lobular structure, liver enlargement, pallor and discoloration in male and female pups.
No information was available on effects of paclobutrazol on reptil es or to terrestrial

- phase amphibians. Effects and effect levels in birds will be used as a surrogate for reptiles and the
terrestrial

- phase of amphibians in this assessment. Toxicological endpoints selected for terrestrial animal assessment endpoints ar e con tain ed in Table 1 7

.

T able 17 . Summary of specific measurement endpoint values selected to e valua te risk
for birds and mammal assessment e ndpoints

Assessment Endpoint Measurement Endpoint Selected Measurement Endpoint Value and Source

Species Toxicological Endpoint and Effect(s) Chemical / Source / Study Classification

Survival and Reproduction of Birds, Reptiles and Amphibians Mortality: acute oral avian LD 50 Mallard duck ( Anas platyrynchos ) LD 50 > 7913 mg/kg

- bw Paclobutrazol technical grade, % purity not reported

MRID 00117484

AcceptableChapter 3 Effects Characterization

76 Assessment Endpoint Measurement Endpoint Selected Measurement Endpoint Value and Source

Species Toxicological Endpoint and Effect(s) Chemical / Source / Study Classification
Mortality: subacute avian LC 50 Mallard duck ( A nas platyrhynchos ) 8

- d ay LC 50 > 20,000 mg ai/kg

- diet

No mortality, but slight decrease in food consumption at 11,000 and 20,000 mg ai/kg

diet. Paclobutrazol technical grade, 92.4% ai

MRID 00117485 (mallard)

Acceptable
Mortality: subacute avian LC 50 Bobwhite quail ( Colinus virginianus ) 11

- day LC 50 > 5000 mg ai/kg

- diet

Erratic mortalities were reported, some of which were likely from bullying behavior of the birds. Other sub

- lethal effects that were observed were loss of balance, quietness, and unsteadiness. Paclobutrazol technical grade, 92.4% ai

MRID 00117486

Acceptable
Reproduction: chronic reproduction NOAEC Mallard duck ( A nas platyrhynchos ) NOAEC = 995 mg ai/kg

- diet LOAEC = 3010 mg ai/kg

- diet (10 weeks diet exposure to adults)

The most sensitive parameters were a r educed ratio of live 3

- week embryos to viable embryos, reduced ratio of hatchlings to eggs set, reduced ratio of hatchlings to live 3

- week embryos, and reduced ratio of hatchling survivors to eggs set

.

Other effects included a reduction in hatchability in the 995 and 3010 mg ai/kg

- diet

groups. Paclobutrazol technical grade, 95.1%

MRID 48270602

Acceptable

Reproduction: chronic reproduction NOAEC Bobwhite quail ( Colinus virginianus ) NOAEC = 453 mg a i/kg

- diet LOAEC = 888 mg ai/kg

- diet (14 w ee ks diet exposure to adults)

The most sensitive parameter was a decrease in female body weight gain. No other treatment

related effects were observed. Paclobutrazol technical grade 95 .6% a i

MRID 48270601

Acceptable

Survival and Reproduction of Mammals Mortality: acute oral
LD 50 Rat ( Rattus norvegicus) Male LD 50 = 1954 mg/kg

- bw Female LD 50 = 1336 mg/kg

- bw

Unsteady gait, loss of righting reflex, piloerection, coma, hypothermia, respiratory stress, and urinary incontinence appeared after
1

- hour of dosing. Paclobutrazol technical grade, % purity not reported

MRID 117478; Acc# 248688

AcceptableChapter 3 Effects Characterization

77 Assessment Endpoint Measurement Endpoint Selected Measurement Endpoint Value and Source

Species Toxicological Endpoint and Effect(s) Chemical / Source / Study Classification
Reproduction: chronic reproduction NOAEC Rat ( Rattus norvegicus) NOEL = 50 mg/kg

- diet (2.5 mg/kg

- bw / day) LOEL = 250 mg/kg

- diet (12.5 mg/kg

- bw / day) ( 2 gen eration repro duction study )

Based on increased liver weights and on fatty change in the liver of fe males; increased incidence of chromodacryorrhea and thickened eyelids, dental malocclusion, increased liver weights, mottling or accentuation of the lobular structure, liver enlargement, pallor and discoloration in male and female pups. Paclobutrazol techn ical grade, 92.4%

MRID 40734303

Acceptable

Effects on Birds
There w as one acute avian oral toxicity study with technical grade paclobutrazol (MRID 00117484)

. The acute oral LD 50 of paclobutrazol was >7913 mg/kg

- bw in the mallard duck. Only one mortality (7913 mg ai/kg

- bw group) was reported during the study, but it was attributed to “bullying” rather than as a response to the dosing. No changes in food consumption, body weight gain or other effects were observed.

There were two avian subacute dietary studies with technical grade paclobutrazol . One study was conducted with mallard ducks and the other with bobwhite quail. The dietary 8

- d 5 LC 50 value for the bobwhite quail was > 5000 mg ai/kg

- diet (MRID 00117486) an d the value for the mallard duck was > 20,000 mg ai/kg

- diet (MRID 00117485)

. For the mallard dietary exposure study

, no mortalities were observed , but there was a slight decrease in food consumption and weight gain in the 11,000 and 20,000 mg ai/kg

- diet g roups. The bobwhite quail study was extended by 3 days (total of 11 days) because of an erratic dose

- response curve and a high amount of “bullying” among birds. The bullying behavior was felt to
contribute to some of the mortalities at different dose lev els, but was not thought to be induced by the paclobutrazol dosing. However, even when bullied birds were excluded from the mortality count, the dose

- response curve was still erratic [mortalities: 2 controls (out of 30), 0 at 554 ppm, 2 at 1007 ppm, 7 at 1830 ppm, 0 at 3328 ppm, 1 at 6050 ppm, 1 at 11,000 ppm, and 2 at 20,000 ppm]. These results are not in line with the range finding test which demonstrated no mortality up to 20,00 0 ppm. The study also reported “quieting” and loss of
balance in some bird s in the 1007, 1830, and 20,000 ppm. Two “unsteady” birds in groups 1830 and 20,000 ppm were found dead on days 4 and 9 of the experiment. Given these results, and the fact that the LC 50 for the mallard duck was so high, it was determined that a

conserva tive estimate for the bobwhite quail was LC 50 > 5000 mg ai/kg

- diet.

5 Study duration consists of 5 days exposure plus 3 days post

- exposure

.Chapter 3 Effects Characterization

78 There were two chronic reproduction studies with technical grade paclobutrazol. The bobwhite quail study yielded a NOAEC of 453 mg ai/kg

- diet and a LOAEC of 888 mg ai/kg

diet (MRID 48270601) . The values were based on adult female body weight gain; no other

treatment

- related effects were observed. Four mortalities occurred during the expe riment (two in the control and two in the 900 mg/kg group), but these were attributed to mate aggression rather than paclobutrazol. The mallard duck was less sensitive to chronic exposures of paclobutrazol with a NOAEC of 995 mg ai/kg

- diet and a LOAEC of 3010 mg ai/kg

- diet (MRID 48270602)

. A single incidental mortality occurred in the contro l group and two incidental mortalities occurred in the 1000 mg ai/kg treatment group, but they were not
considered treatment

- related (one showed no behavior or physiological signs of problems upon necropsy and the other had a prolapsed uterus) . There were no treatment

- related effects observed for any reproductive endpoint at levels up to and including 995 mg ai/kg. There were statistically significant reductions in several reproductive ratios at the 3010 mg ai/kg diet level: percentage of live 3

- week emb ryos to viable embryos (4% lower than control), ratio of hatchlings to eggs set (27% lower than control), ratio of hatchlings to live 3

- week embryos (26% lower than control), and the ratio of hatchling survivors to eggs set (27% lower than control). No st atistically significant treatment related effects were observed for any other reproductive endpoints, including egg shell thickness or offspring body weights.

Effects on Mammals An acute oral mammal toxicity study yielded LD 50 s of 1954 and 1336 mg ai/kg

- b w for male and female rats, respectively (MRID 00117478) . Pa c l obutrazol was assigned a toxicity class of III, based on these data. The study also reported that an unsteady gait, loss of righting reflex, piloerection, coma, hypothermia, respiratory stress , and urinary incontinence appeared within the first hour after doses were given. A two

- generation rat reproduction study yielded a NOEL of 2.5 mg ai/kg

- bw and a LOEL of 12.5 mg ai/kg

- bw. At 250 ppm and above, an increased incidence of chromodacryorrhea and thickened eyelids was observed in both generations (parents and pups). At 1250 ppm, increases in liver weights were observed in females of both generations (23% absolute, 26% relative F 0 ; 7% absolute, 14% relative F 1 ) and fatty change in the liver was observed in F 0 females (76% versus none of the controls). Increased liver weights, mottling or accentuation of the lobular structure, liver enlargement and pallor an d discoloration were observed in male and female pups from both generations.
In addition , dental malocclusion was observed in both generations and thickening of the urinary bladder wall was observed in one F 0 and in three F 1 high dose females.



### Terrestrial Invertebrate Toxicology

There were no t oxicity data suitable for quantitative use in risk assessments for exposures of
terrestrial invertebrates to paclobutraz ol available

. There was one open literature study that was classified as “qualitative,” meaning that it provided useful information but did not meet the requirements for toxicity values to be used quantitatively in the risk assessment. OettingChapter 3 Effects Characterization

79 and Latimer (1995) conducted a residue exposure study on predatory mites using the formulated product, Bonzi (0.4% paclobutrazol). Two species of predatory mi tes ( Neoseiulus cucumeris and Orius insidiosus ) were exposed to three concentrations of Bonzi (40, 80, and 160 ppm). In the first scenario, mites were exposed to “wet” foliage (foliage that had just been dipped into a concentration of Bonzi). In the seco nd scenario, mites were exposed to foliage that had been allowed to dry for one hour. For both scenarios, mortality was recorded at 24 and 48 hours after exposure to the treated foliage. In three instances, mortality in the negative control groups was gr eater than 20 percent (“wet” and “dry”
scenarios for N

. cucumeris, and “wet” scenario for O. insidiosus ); thus information from these trials is not valid for this risk assessment. For the remaining scenario (“dry” scenario
for O. insidiosus ), the 48

- hour NOAEC was determined to be 160 ppm, based on a visual inspection of the mortality data reported in the publication. In addition to the high mortality rate in three of the control gr oups, the experiment only used five individuals per replicate (compared wi th 25 individuals per replicate for the guideline honeybee test). Sub

- lethal
effects also were not reported in the study; however, it should not be assumed that such effects were not present.

S URROGATE D ATA A PPROACH Honey bee t oxicity data were collecte d from triazoles that were similar in structure to paclobutrazol

. Only non

- definitive acute contact LD 50 data were available for five triazoles (cyproconazole, fenbuconazole, metconazole, triadimefon, triticonazole) , thus, it was not possible to calculate a toxicity value based on the 5 th percentile of data. To fill this data gap

, t he most conservative toxicity value

– tri ticonazole ( i.e. , the chemical with the lowest non

definitive value)

– was used in the risk assessment (Table 18 )

.

Table 1 8 . Summary of specific measurement endpoint values selected to evaluate r isk
for honey b ees

Assessment Endpoint Measurement Endpoint Selected Measurement Endpoint Value and Source

Species Toxicological Endpoint and Effect(s) (μg ai/bee) Chemical / Source /

Acute Contact Toxicity Mortality: acute

contact LD 50 Honey Bee ( Apis mellifera ) LD 50 > 24 Tri ticonazole

MRID 44802122Chapter 3 Effects Characterization

80 

### Aquatic Vertebrate ( Fish ) Toxicology

Table 19 . Summary of specific measurement endpoint values selected to evaluate risk
for fish and amphibian assessment e ndpoints

Assessment Endpoint Measurement Endpoint Selected Measurement Endpoint Value and Source
Species Toxicological Endpoint and Effect(s) (mg ai/L) Chemical/ Source / Study Classification

Survival and reproduction of freshwater fish Acute mortality:

most se nsitive acute freshwater fish 48

- h our LC 50 Grass carp ( Ctenopharyngodon idellus ) 48

- hour LC 50 = 15.9 2 Paclobutrazol

MRID 48605402

Quantitative
Chronic Early Life Stage: most sensitive NOAEC Rainbow trout ( Salmo gairdneri ) NOAEC = 0.049 Paclobutrazol

MRID 47918901

Acceptable

Survival and reproduction of estuarine/marine fish Acute mortality: most sensitive acute estuarine/marine fish 48

- hour LC 50 Sheepshead minnow ( Cyprinodon variegatus ) 48

- hour LC 50 = 1.58 1 Cyproconazole, fenbuconazole, hexaconazole, metconazole, mycobutanil, tebuconazole

N / A

N / A Chronic Early Life Stage: most sensitive NOAEC Sheepshead minnow ( Cyprinodon variegatus ) NOAEC = 0.004 1 Metconazole, tebuconazole, triticonazole

N/A

N/A

Survival of amphibians Acute mortality: most sensitive acute amphibian 96

- h our LC 50 Asiatic toad ( Bufo bufo gangarizas ) 96

- hr LC 50 = 8.9 Paclobutrazol

MRID 48605402

Quantitative 3

1 The 5 th percentile as calculated from a dist ribution of data from structurally

- similar triazoles.

2 Normally a 96

- hour LC 50 would be used. The duration of this study was only 48 hours. At 24 hours, the LC 50 was determined to be 19.1 mg ai/L. It is expected that the toxicity value would have continued to decrease with a longer exposure period. Thus, it was determined that the grass carp is more sensitive than rainbow trout (96

- hour LC 50 = 27.8 mg ai/L) and bluegill sunfish (96

- hour LC 50 = 23.6 mg ai/L) for which registrant

- submitted studies are available.

3 Open litera ture source.

Effects to Freshwater Fish and Aquatic

- Phase Amphibians

Information is available for three acute and one chronic toxicity studies of paclobutrazol with
freshwater fish ; no studies are available for estuarine/ marine fish. One study is available for the acute effects to amphibians. Paclobutrazol is classified as slightly toxic to freshwater fish and moderately toxic to amphibians on an acute basis. All studies for paclobutrazol were completed using the technical grade.Chapter 3 Effects Characterization

81 Data are available for acute effects of paclobutrazol to warm and cold water species of
freshwater fish. There are three acute freshwater fish studies using technical grade paclobutrazol

. Based on the toxicity data available

, paclobutrazol is classified as slightly
toxic to freshwater fish. The 96

- hour LC 50 values for bluegill sunfish (warm water species ) and rainbow trout (cold water species) are 23.6 mg ai/L and 27.8 mg ai/L, respectively (MRIDs 00117488, 00117487); the 48

- hour LC 50 for grass carp (warm water species) i s 15.9 mg ai/L (MRID 48605402). The rainbow trout study reported hyperactivity followed by keeling and distension of the abdomen. Darkened pigmentation was noted at the 13.5 mg/L treatment level and higher. After the 96

- hour expo sure to paclobutrazol concentrations, fish in the 28 and 32 mg/L treatment groups were removed from the test water and placed in clean freshwater. Observations continued for a period of 144 hours. After 48 hours, most of the fish were no longer showing s igns of keeling and distension in their abdomens , although pigmentation still remained dark. At 144 hours, one fish in the 32 mg/L group and three in the 28 mg/L group were still dark in color, but all others had recovered to a normal physical

state

. The bluegill sunfish test reported quiescence, darkened pigmentat ion, and loss of
balance . Darkened pigmentation was reported for all concentrations above and including the 17.3 mg/L treatment group.

An open literature study provided acute toxicological i nformation for the grass carp ( Ctenopharyngodon idellus ). Approximately 12 hours after hatching, grass carp were placed in solutions of paclobutrazol, including a negative control. LC 50 values were calculated at 24 and 48 hours after exposure; a 96

- hour LC 50 was not available. Therefore, the LC 50 from this study may be underestimating toxicity to the grass carp. No sub

- lethal effects were reported in the study; however, this does not rule out the possibility that sub

- lethal effects wer e present

.

There is one chronic toxicity study for freshwater fish. The NOAEC and LOAEC for the fathead minnow ( Pimphales promelas ) were established as 0.049 mg ai/L and 0.087 mg ai/L, respectively. Growth was the most sensitive endpoint (length and weight). Average len gth at the 0.087 mg ai/L treatment level was 19.7 mm versus 26.1 mm in the control ( p < 0.05). Likewise, the average dry weight for the 0.087 mg ai/L treatment level was 0.0213 g compared with 0.0363 g for the control ( p <0.05). Post

- hatch larval survival also was
affected but was less sensitive than the aforementioned growth effects; post

- hatch larval survival effects were first observed at 0.180 mg ai/L (10% survival versus the control at 75% survival).

The amphibian study (MRI D 48605402) was conducted with Bufo bufo gangarizas (Asiatic toad) tadpoles. Tadpoles less than 3

- days old were placed in several different concentrations of paclobutrazol. LC 50 s were calculated at 24, 48, 72, and 96 hours; the 96

- hour LC 50 wasChapter 3 Effects Characterization

82 reported as 8.9 mg ai/L. No sub

- lethal effects were r epo rted in the study, however, this does not rule out the possibility that sub

- lethal effects were present.

Effects to Estuarine

- Marine Fish
There wer e no toxicity data for the effects of paclobutrazol on estua rine/marine fish.

S URROGATE D ATA A PPROACH
T oxicity data were collected from triazoles that were similar in structure to paclobutrazol

. For acute effects to estuarine/marine fish, d efinitive LC 50 data from six triazoles (cyproconazole, fenbuconazole, hexaconazole, metconazole, myclobutanil, tebuconazole, triticonazole) were available. A surrogate toxicity value for paclobutrazol acute effects on estuarine/marine fish was developed based on the 5 t h percentile of the distribution of data. For chronic effects to estuarine/marine fish, d efinitive NOAEC/NOEC data from three triazoles (metconazole, tebuconazole, triticonazole) were available. A surrogate toxicity value for paclobutrazol chronic effect s on estuarine/marine fish was developed based on the
5 th percentile of the distribution of data.



### Aquatic Invertebrate Toxicology

There are five freshwater invertebrate acute toxicity studies ; no data were available for
chronic f reshwater invertebrate effects or estuarine

- marine acute and chronic effects for paclobutrazol . Information is available for three studies conducted with D

. magna , an aquatic tubificid worm ( Limnodrilus hoffmeisteri ), and a freshwater mollusk ( Cipangopalu dina chinensis ). Paclobutrazol is classified as slightly toxic to highly toxic to
D

. magna , slightly toxic to the aquatic tubificid worm and freshwater mollusk. A ll the studies were conducted with technical grade paclobutrazol

. Toxicological endpoints s elected
for freshwater and estuarine

- marine assessment endpoints are con tain ed in Table 20

.Chapter 3 Effects Characterization

83 Table 20

. Summary of specific measurement endpoint values selected to evaluate risk for aquatic invertebrate assessment e ndpoints

Assessment Endpoint Measurement Endpoint Selected Measurement Endpoint Value and Source
Species Toxicological Endpoint and Effect(s) (mg ai/L) Chemical/ Source / Study Classification

Survival and reproduction of freshwater invertebrates Acute mortality: most sensitive acute freshwater invertebrate 48

- h our EC 50 Water flea ( D.

magna ) 1 48

- h our EC 50 = 0.24 48

- hour L OEC = 0.05 Paclobutrazol

MRID 48605401

Quantitative 2

Chronic effects: most sensitive NOAEC Water flea ( D.

magna ) NOAEC = 0.009 3 Cyproconazole, fenbuconazole, hexaconazole, metconazole, tebuconazole, triadimefon, triadimenol, triticonazole

N/A

N/A

Survival of freshwater mollusks Acute mortality: most sensitive acute freshwater mollusk 48

- hour L C 50 Chinese mystery snail ( C ipangopaludina chinensis ) 48

- h ou r L C 50 = 12.6 Paclobutrazol

MRID 48605401

Quantitative 2

Survival and reproduction of estuarine/marine invertebrates Acute mortality: most sensitive estuarine/marine invertebrate 48

- hour EC 50 /LC 50 Eastern oyster ( Crassostrea virginianus )

Mysid shrimp ( Americamysis bahia ) EC 50 = 0.24 3 Cyproconazole, fenbuconazole, hexaconazole, metconazole,

myc l obutanil, tebuconazole, triticonazole

N/A

N/A

Chronic effects: most sensitive
N OAEC Mysid shrimp ( Americamysis bahia ) NOAEC = 0.035 Tebuconazole

MRID 42038201

N/A

1 Conducted on the embryo part of the life

- stage.
2 Open literature source.

3 The 5 th percentile as calculated from a distr ibution of data from structurally

- similar triazoles.

Effects to Freshwater Invertebrates

Information is available for three acute paclobutrazol toxicity studies conducted using D.

magna

. Paclobutrazol is classified as slightly to highly toxic to D. magna on an acute basis.Chapter 3 Effects Characterization

84 T wo studies using first instar daphnids yielded a 48

- hour LC 50 of 28. 2 mg ai/L and a 48

- hour
EC 50 of 33.2 mg ai/L (MRIDs 48605402, 00117489). MRID 00117489 tested five different concentrations of paclobutrazol; however, the highest one exhibited precipitate that was observed to stick to the daphnids. All test solutions we re verified and samples were centrifuged before analysis. A number of statistical analyses were performed and it was
determined that the EC 50 calculation was valid, despite being based on four concentrations
rather than five. This test also established a n EC 50 (94 mg ai/L) for a formulated product

– GFU 0 29 (50% wettable powder). MRID 48605402 was an open literature study that tested daphnia that were less than 25 hours old. Individuals were exposed to five different concentrations of paclobutrazol an d monitored every 24 hours to detect mortality. No sub

lethal effects were documented; however, this does not mean that sub

- lethal effects did not

occur

.

A third open literature study (MRID48605401) was conducted on neonate and embryo daphnia. Toxicity values ranged from 48

- hour EC 50 = 25.6 mg ai/L (neonate) to 48

- hour

EC 50 = 0.24 mg ai/L (embryo). In general, the study followed EPA 850.101 0 guidelines; however, the guidelines do not usually test daphnia at the embryo stage. For this part of the test, embryos were exposed to various concentrations of paclobutrazol and observed daily to detect developmental abnormalities and premature death. No sub

- lethal effects were reported for the neonate study. For the embryo study, malformation of several organs was visible at 48 hours including: the second antenna, rostrum, malpighian tube, sensory bristles, and tail spine. In addition, embryonic development was inhibited at 48 hours and deformed growth

was note d at 72 hours.

MRID 48605402 also derived acute toxicity values for the Chinese mystery snail ( Cipangopaludina chinensis ) and an aquatic tubificid worm ( Limnodrilus hoffmeisteri ). As with the daphnid study, Chinese mystery snails (average weight

- 2.06 g ) and aquatic tubificid worms ( average length

– 13.7 mm) were subjected to five different paclobutrazol concentrations, including a control. The 48

- hour LC 50 for the Chinese mystery snail was 12.6 mg ai/L and the 48

- hour LC 50 for the aquatic tubificid wor m was 49.9 mg ai/L. Toxicity values for the aquatic tubificid worm were calculated at the 72 and 96 hour marks as well. These values were lower than the 48 hour value (72

- hour LC 50 = 41.5 mg ai/L and 96

- hour

LC 50 = 34.9 mg ai/L); however, the aquatic mod els used to generate EECs are sufficiently conservative making it overly conservative to use a 96

- hour toxicity value when the norm is
48 hours. Sub

- lethal effects were not reported in the study, but this does not preclude the possibility that sub

- lethal effects were present.

There were no chronic studies available for freshwater invertebrates.Chapter 3 Effects Characterization

85 S URROGATE D ATA A PPROACH C hronic toxicity data for freshwater invertebrate s were collected from triazoles that were similar in structure to paclobutrazol

. Definit ive NOAEC/NOEC data from eight triazoles (cyproconazole, fenbuconazole, hexaconazole, metconazole, tebuconazole, triadimefon, triadimenol, triticonazole) were available. A surrogate toxicity value for paclobutrazol
chronic effects on freshwater invertebra tes was developed based on the 5 th percenti le of the
distribution of data.

Effects to Estuarine

- Marine Invertebrates There are no data for the effects of paclobutrazol on estuarine/marine invertebrates available.

S URROGATE D ATA A PPROACH
T oxicity data were collected from triazoles that were similar in structure to paclobutrazol

. For acute effects to estuarine/marine invertebrates, d efinitive LC 50 /EC 50 data from seven triazoles (cyproconazole, fenbuconazole, hexaconazole, metconazole, myclobutanil,
tebu conazole, triticonazole) were available. A surrogate toxicity value for paclobutrazol acute effects on estuarine/marine invertebrates was developed based on the 5 th percentile of
the distribution of data.

For chronic effects to estuarine/marine inverteb rates d efinitive NOAEC/NOEC data were available for only one triazole

– tebuconazole. Consequently, tebuconazole’s toxicity value was used as a surrogate for paclobutrazol chronic effects on estuarine/marine invertebrates.



### Terrestrial Plant Toxicology

To xicity data involving exposures of terrestrial plants to paclobutrazol are available fro m a registrant submitted study; only dicot vegetative vigor data are available because of methodological issues with the other guideline studies. Surrogate data were c alculated from other structurally

- similar triazoles. The available data are described below and summarized

in Table 21

.Chapter 3 Effects Characterization

86 Table 21

. Effects to plants from paclobutrazol

Assessment Endpoint Measurement Endpoint Selected Measurement Endpoint Value and Source
Species Toxicological Endpoint and Effect(s) (lb ai/A) Chemical/ Source / Study Classification

Effects to terrestrial plants Vegetative vigor: dicot EC 25 and NOAEC (based on shoot length) Tomato ( Lycopersicon esculentum ) EC 25 = 0.032
N O A EC <0.0090 Paclobutrazol

MRID 47918903

Supplemental

Vegetative vigor: monocot EC 25 Corn ( Zea mays ), onion ( Allium

cepa ), ryegrass ( Lollium perenne ), wheat ( Triticum
aestivum ) EC 25 > 0.097 Metconazole

MRID 46902215

Vegetative vigor: monocot NOAEC N/A NOAEC = 0.059 1 Cyproconazole, metconazole, tebuconazole

N/A

N/A

Effects to terrestrial plants Seedling emergence: dicot EC 25 N/A EC 25 = 0.009 1 Cyproconazole, tebuconazole, triticonazole

N/A

N/A Seedling emergence: dicot NOAEC N/A NOAEC = 0.002 1 Cyproconazole, triticonazole, metconazole

N/A

N/A Seedling

emergence: monocot EC 25 Wheat ( Triticum
aestivum ) EC 25 > 0.098 Metconazole

MRID 46902214

Seedling

emergence: monocot NOAEC N/A NOAEC = 0.071 1 Cyproconazole, metconazole, tebuconazole, triticonazole

N/A

N/A

1 The 5 th percentile as calculated from a distr ibution of data from structurally

- similar triazoles.Chapter 3 Effects Characterization

87 The r egistrant submitted two plant studies (seedling emergence and vegetative vigor) in support of registration review for paclobutrazol. Initially, these studies were classified as “supplemental” because they were performed with technical grade active ingredient (TGAI) rather than a formulated product. Subsequently, it was discovered that there was a solvent control response in both studies. In the seedling emergence study (MRID 47918902), nine of the ten species tested reacted to the solvent. In some species, growth was promoted while in others, growth was inhibited. The only species that did not react to the solvent was the tomato ( Lycopersicon esculentum ). Thus, this study was re

- classified as “invalid.” For the vegetative vigor study (MRID 47918903), three of t he four monocots (ryegrass, onion, and oat) tested exhibited a growth promotion effect by the solvent; corn was not affected. None of the dicots appeared to be affected by the solvent; therefore it was determined that only the
dicot data were reliable eno ugh to be used in risk assessments. Of the dicots tested, the tomato ( Lycopersicon esculentum ) was the most sensitive with an EC 25 of 0.032 lb ai/A and a NOAEC of < 0.0090 lb ai/A (based on shoot length).

S URROGATE D ATA A PPROACH For seedling emergence, o nly non

- definitive EC 25 data were available for monocots. Consequently, the most conservative endpoint (metconazole) was used in the risk

assessment. D efinitive monocot NOAEC/NOEC data from four triazoles (cyproconazole, metconazole, tebuconazole, tritic onazole) were available. A surrogate toxicity value for paclobutrazol effects on monocot seedling emergence (NOAEC) was developed based on the
5 th percentile of the distribution of data.

Definitive dicot EC 25 data from three triazoles (cyproconazole, t ebuconazole, triticonazole) and definitive dicot NOAEC/NOEC data from three triazoles (cyproconazole, metconazole, triticonazole) were available. Surrogate toxicity values for paclobutrazol effects on dicot seedling emergence were developed based on the 5 th percentile s of these two data
distributions.

For vegetative vigor, only non

- definitive EC 25 data were available for monocots. Consequently, the most conservative endpoint (metconazole) was used in the risk

assessment. D efinitive monocot NOAEC/NOEC data from three triazoles (cyproconazole, metconazole, tebuconazole) were available. A surrogate toxicity value for paclobutrazol effects on monocot vegetative vigor was developed based on the 5 th percentile of the
distribution of data.Chapter 3 Effects Characterization

88 

### Aquatic Plant Toxicology

Aquatic plant toxicity data (Table 22) are available for paclobutrazol from two open
literature studies. MRID 48605402 tested the effects of five different concentrations of technical grade paclobutrazol on green algae ( Selenastrum capricornutum ). The EC 50 was determined by observing which of the five concentrations of paclobutrazol reduced algal productivity by 50 percent after 96 hours of exposure. The 96

- hour EC 50 was determined to be 40.8 mg ai/L. A 120

- hour EC 50 also was repo rted (32.9 mg ai/L), but was not used in this risk assessment because the PRZM/EXAMS peak EEC estimates are conservative making it overly conservative to use the more sensitive endpoints obtained from the longer testing
intervals.

MRID 4863750 1 examined t he effects of paclobutrazol (end use product) on two vascular aquatic plants: a dicot

– Eurasian watermilfoil ( Myriophyllum spicatum L. ) and a monocot

– hydrilla ( Hydrilla verticillata ). 4

- inch segments of each plant were exposed to concentrations of pac lobutrazol for 4 weeks (hydrilla

– 0, 75, 375, and 750 μg ai/L; milfoil

– 0, 0.75, 7.5, 37, and 75μg ai/L). Measurements were taken at 0, 1, 2, and 4 weeks for: main stem length, lateral stem length and number, root length and number, fresh and dry weigh ts, and chlorophyll concentration. T he NOAEC and LOAEC for hydrilla were <75 μg ai/L and 75 μg ai/L, based on main stem length and number of lateral stems. The milfoil NOAEC and LOAEC were <0.75 μg ai/L and 0.75 μg ai/L, based on main stem length, total stem length (main + laterals) and fresh weight.

In addition, MRID 4863750 1 examined the amount of time needed for hydrilla and milfoil to recover from various paclobutrazol exposure durations. 4

- inch apical segments of hydrilla and milfoil were exposed to concentrations of paclobutrazol (hydrilla = 750μg ai/L; milfoil = 75 μg ai/L) for a period of 1, 3, 7, and 14 days. Following the exposure to paclobutrazol, the plant segments were rinsed in distilled, autoclave water and the returned to a fresh untre ated medium for the duration of the experiment. Plants were measured for re

- growth at 2, 4, and 6 weeks following the paclobutrazol exposure period. The results of the study sho w ed that hydrilla recovered to untreated stem lengths after a 6 week period, regardless of the initial paclobutrazol exposure duration. Milfoil was more sensitive and remained sup pressed after 6 weeks, even when the initial p aclobutrazol exposure was only one day. These results indicate potential differences in the sensitivities of aquatic vascular monocots and dicots to paclobutrazol.

S URROGATE D ATA A PPROACH Acut e toxicity data from structurally

- similar triazoles were collected for aquatic vascular plants. Definitive EC 50 data were available for four triazoles (cyproconazole, metconazole,Chapter 3 Effects Characterization

89 tebuconazole, triticonazole). A surrogate toxicity value for paclobutrazol effects on aquatic vascular plants was developed based on the 5 th percentile of the distribution of data.

Table 22

. Summary of specific m easureme nt e ndpoint values selected to calculate risk

q uotient values to evaluate risk for aquatic plant assessment e ndpoints

Assessment Endpoint Measurement Endpoint Selected Measurement Endpoint Value and Source

Species Toxicological Endpoint and Effect(s) (μg ai/L) Chemical/ Source / Study Classification

Survival and biomass of aquatic vascular and non

- vascular plants Non

- vascular species: the most sensitive productivity
E C 50 Green algae ( Selenastrum capricornutum ) 96

- hour EC 50 = 40,800 Paclobutrazol

MRID 48605402

Quantitative 1

Vascu lar species: the NOAEC and LOAEC based on the most sensitive growth parameter Freshwater Eurasian watermilfoil ( Myriophyllum spicatum L. ) 28

- d ay NOAEC <0.75 28

- day LOAEC = 0.75

Most se nsitive endpoint was main stem length, total stem length (main + laterals), and fresh weight. Paclobutrazol

MRID 48637501

Quantitative 1

Vascular species: endpoints based on mortality EC 50 Duckweed ( Lemna gibba ) EC 50 = 8 2 Cyproconazole, metconazole, tebuconazole, triticonazole

1 Open literature source.

2 The 5 th percentile as calculated from a distr ibution of data from structurally

- similar triazoles.90 

# Results: Risk Characterization

Risk Estimation

As described in the Paclobutrazol Work Plan, estimates of e xposure and ecotoxicity of paclobutrazol are integrated using standard risk quotient (RQ) methods to evaluate the potential for adverse ecological effects to mammalian, avian, and other non

- target species.

R isk quotient results r epresent expected direct effects to organisms ( i.e . effects from direct toxicity to paclobutrazol exposure) in contrast to indirect effects to an organism resulting from a modification of a resource such as loss of their prey or habitat.

Direct Effects to Non

- Target Terrestrial Vertebrates

D IRECT E FFECTS TO B IRDS , R EPTILES , AND ( LAND
- PHASE ) A MPHIBIANS Chronic risk quotients were calculated for the maximum usage rates of paclobutrazol for turf, seed treatments (tomato, pepper, cucurbits , broccoli, cauliflower, cabbage ), tree injection/drench, potted ornamentals

– spray, and potte d ornamentals

– drench ( Tables 23
and 24 )

. Chronic

- based risk quotients were calculated based on a bobwhite quail avian reproduction study (MRID 48270601) using technical g rade paclobutrazol. Risk quotients
were not calculated for acute dose

- based or acute dietary

- based risks beca use all of the toxicity data were non

- definitive. Risk s from these potential exposure pathways were
evaluated and discussed in the Risk Descripti on Section.

T

- REX was used to calculate chronic dietary risk quotients for turf and spray applications to potted ornamentals. For turf, the risk quotients ranged from 0.05 to 0.79 and did not exceed
the LOC of 1. The spray application for potted ornamen tals yield ed r isk quotients from 0.01 to 0.14 ( Table 23 ).

Chronic dietary r isk quotients for tree injection, soil injection/drench, potted ornamental drench, and seed treatments were based on non

- T

- REX EEC calculations. Risk quotients for tree injectio n did not exceed the LOC. Risk quotien ts for soil injection/drench exceeded the LOC of 1 for both hardwoods (2.3) and softwoods (1.1). Consequently, there may be a chronic dietary risk to birds that consume leaves, fruit, seeds, or other vegetative items for this use. None of the other uses (seed treatment, woody and non

- woody potted ornamental drench) exceeded the LOC; risk quotients ranged from 0.0008 to 0.25 ( Table 24 ).91 Table 23

. Upper bound chronic dietary

- based risk quotients for birds derived from T

REX for application s of paclobutrazol on turf and potted ornamentals (spray)

Risk Quotients Based on Kenaga Upper Bound EEC Chronic Dietary

- Based Risk Quotients

Profile 2SC on Turf

– 3 applications at 0.75 lb ai/A (28 day interval) 1

Short grass 0.79 Tall grass 0.36 Broadleaf plants/small insects 0.44 Fruits/pods/seeds/lg insects 0.05 Bonzi II Spray for Potted Ornamentals

– 1 application at 0.26 lb ai/A Short grass 0.14 Tall grass 0.07 Broadleaf plants/small insects 0.08 Fruits/pods/seeds/lg insects 0.01

1 3 applications at 0.75 lb ai/A exceeds the maximum seasonal rate of 2 lb ai/A by 0.25 lb ai/A ; however, risk quotients did not exceed the LOC even at this higher rate

.

Table 24 . Chronic dietary

- based risk quotients for b i rds for tree i njection , soil
i njection /drench, potted ornamental drench, and seed t reatments (see Appendix K for RQ calculations) Avian Chronic Dietary RQ (mg ai/kg

- diet) Tree injection at 0.36 lb ai/A
Hardwoods 0.47
Softwoods 0.02
Soil injection/drench at 1.9 lb ai/A
Hardwoods 2.3* **
Softwoods 1.1* ** Woody potted ornamental drench at 6.1 lb ai/A
Hardwoods 0.13 Softwoods 0.05

Non

- woody potted ornamental drench at 6.1 lb ai/A

Non

- woody plants 0.25
Seed treatments

Tomato <0.01 Cucurbit <0.01 Pepper <0.01
Broccoli <0.01 Cauliflower <0.01 Cabbage <0.01

* ** Exceeds chronic LOC of 1.92 D IRECT E FFECTS TO M AMMALS For mammal ian species, acute dose

- based risk quotient s were calculated for the maximum usage rates of paclobutrazol on turf, tree injection/drench, potted ornamentals

– spray, and potted ornamentals

– drench , and seed treatments ( Table s 25 and 26 ). Acute dose

- based risk quotient s were calculated based on the acute oral toxicity study using technical grade paclobutrazol with the female rat (MRID 117478, Accession Number 248688 ) and dose

based EECs were calculated from estimated paclobutrazol residues on dietary items. A
chronic two

- generation rat r eproduction study (MRID 40724303 )

, where paclobutrazol was mixed into the rat diet

, was used to calculate both the dietary

- and dosed

- based chronic risk
to mammals ( Table s 25 and 26 ).

Acute Effects The highest r isk quotients resulted from soil injection/drench appl ications. Risk quotients

r anged from 0.07 to 0.34; 15, 35 , and 1000 g mammal s consuming leaves (leaves were used as a surrogate for other non

- woody food items) from hardwood trees injected or drenched with paclobutrazol may be at risk (LOC of 0.1 for list ed species ). Small and medium

- sized mammals consuming leaves from softwoods also exceeded the LOC (0.1). For turf, the acute
dose

- based risk q uotients ranged from <0.01 to 0.11 and exceeded the acute listed LOC (0.1) for 15 and 35 g mammals consuming a d iet of short grass. For tree injections, risk quotients ranged from 0.001 to 0.07 and did not exceed the LOC. For spray applications to potted ornamentals, risk quotients ranged from <0.01 to 0.02 and did not exceed the LOC

. D rench applications to potte d ornamentals (woody and non

- woody) yielded risk quotients from
<0.0 03 to 0.04 and did not exceed the LOC

. For seed treatments, risk quotients ranged from
0.000 05 to 0.001 and did not exceed the LOC.

Chronic Effects For turf, the chronic dose

- based risk quotients ranged from 0.38 to 59.5 and exceeded the LOC of 1. All size classes of mammals were affected (15, 35, and 1000 g) that consumed a diet of short grass, t all grass, broadleaf plants, small insects , fruits, pods, seeds, and large
insects ; “gr anivore” was the only dietary class to not exceed an LOC. The highest risk quotients were found in small and medium sized mammals consuming an exclusive diet of short grass. Chronic dietary

- based risk quotients were exceeded for diets of short grass, tal l grass, broadleaf plants, and small insects ; risk quotients ranged from 0.43 to 6.86

.

For spray applications to potted ornamentals, chronic dose

- based risk quotients ranged from 0.07 to 10.8. The LOC of 1 was exceeded for small, medium, and large mammal s (15, 35,
and 1000 g) consuming short grass, tall grass, and broadleaf/small insects. The chronic dietary risk quotients ranged from 0.08 to 1.25. An exclusive diet of short grass was the only
diet to exceed the LOC of 1.93 For tree injection application s to trees, chronic dose

- based risk quotients ranged from 17 to
37 for hardwoods and 0.73 to 1.6 for softwoods. The LOC of 1 was exceeded for all size classes of mammals consuming hardwood leaves (used as a surrogate for other non

- woody food items) and fo r the smallest mammal size class (15 g) with a diet of softwood leaves. These results indicate that mammals may be at risk from the chronic consumption of leaves from paclobutrazol

- treated trees.

For soil injection/drench applications to trees, chronic d ose

- based risk quotients ranged from
83 to 183 for hardwoods and 38 to 87 for softwoods. The LOC of 1 was exceeded for both
of the scenarios in small, medium, and large mammal size classes. These results indicate that mammals may be at risk from the chro nic consumption of leaves of paclobutrazol

- treated

trees.

For drench applications to potted ornamentals, chronic dose

- based risk quotients ranged from 5 to 11 for woody hardwoods, 2 to 4 for woody softwoods, and 9 to 19 for non

- woody species. The LOC of 1 was exceeded for all of these scenarios in all size classes indicating
that mammals with diets of non

- woody plants or leave s of woody plants may be at risk from the chronic consumption of paclobutrazol

- treated potted ornamentals.

For seed trea tments t o tomato, cucurbit, pepper, broccoli, cauliflower, and cabbage, chronic
d ose

- based risk quotients ranged from 0.03 to 0.51 . The se values d o not exceed the LOC of

1 , thus mammals are not expected to be at chronic risk from consuming seed

- treated transplant s in the field.

Table 25 . T

- REX upper b ound risk q uotients for m ammal s for paclobutrazol turf and spray applications to potted o rnamentals
Risk Quotients Based on Kenaga Upper Bound EEC Dose

- Based RQs Chronic Dietary

Based RQs 15 g 35 g 1000 g

Acute Chronic Acute Chronic Acute Chronic

Profile 2SC on Turf

– 3 applications at 0.75 lb ai/A (28 day interval) 1
Short grass 0.11 * 59.5* * * 0.10 * 50.8* * * 0.05 27.2* * * 6.86* * * Tall grass 0.05 27.3* * * 0.04 23.3* * * 0.02 12.5* * * 3.14* * *
Broadleaf plants/small insects 0.06 33.5* * * 0.05 28.6* * * 0.03 15.3* * * 3.86* * * Fruits/pods/seeds/lg insects 0.01 3.72* * * 0.01 3.18* * * <0.01 1.70* * * 0.43 Granivores <0.01 0.83 <0.01 0.71 <0.01 0.38

- Bonzi II Spray for Potted Ornamentals

– 1 application at 0.26 lb ai/A
Short grass 0.02 10.8* * * 0.02 9.25* * * 0.01 4.96* * * 1.25* * * Tall grass 0.01 4.96* * * 0.01 4.24* * * <0.01 2.27* * * 0.5794 Risk Quotients Based on Kenaga Upper Bound EEC Dose

- Based RQs Chronic Dietary

Based RQs 15 g 35 g 1000 g

Acute Chronic Acute Chronic Acute Chronic

Broadleaf plants/small insects 0.01 6.09* * * 0.01 5.20* * * 0.01 2.79* * * 0.70 Fruits/pods/seeds/lg insects <0.01 0.68 <0.01 0.58 <0.01 0.31 0.08 Granivores <0.01 0.15 <0.01 0.13 <0.01 0.07

- 1 3 applications at 0.75 lb ai/A exceeds the maximum seasonal rate of 2 lb ai/A by 0.25 lb ai/A. A
T

- REX scenario was run with 3 applications at 0.66 lb ai/A. Risk quotients were ~12% lower, but none of the exceeding risk quotients were reduced below the l evel of concern. Thus the higher application rate was used for this assessment to ensure that it was maximally protective. *Exceeds the acute listed LOC of 0.1

* * * E xceeds the chronic LOC of 1

Table 26 . Risk quotients for mammals for paclobutrazol tree i njection , soil
i njection /drench, potted ornamentals drench, and seed treatment a pplications (see Appendix K for RQ calculations)

Mammal Dose

- Based RQs Acute Chronic 15 g 35 g 1000 g 15 g 35 g 1000 g
Tree i njection at 0.36 lb ai/A
Hardwoods 0.07 0.06 0.03 37* * * 31* * * 17* * * Softwoods 0.003 0.001 0.001 1.6* * * 0.94 0.73 Soil injection/drench at 1.9 lb ai/A
Hardwoods 0.34* 0.29* 0.15 * 183* * * 157* * * 83* * * Softwoods 0.16 * 0.13 * 0.07 87* * * 72* * * 38* * * Woody potted ornamental drench at 6.1 lb ai/A
Hardwoods 0.02 0.02 0.01 11* * * 9* * * 5* * * Softwoods 0.01 0.01 0.003 4* * * 4* * * 2* * *

Non

- woody potted ornamental drench at 6.1 lb ai/A
Non

- woody plants 0.04 0.03 0.02 19* * * 17* * * 9* * *
Seed treatments
Tomato 0.0007 0.0006 0.0003 0.38 0.34 0.17 Cucurbit 0.0004 0.0003 0.0002 0.20 0.18 0.09 Pepper 0.001 0.0008 0.0004 0.51 0.43 0.23
Broccoli 0.0001 0.0001 0.00005 0.06 0.05 0.03
Cauliflower 0.0001 0.0001 0.00005 0.06 0.05 0.03 Cabbage 0.0001 0.0001 0.00005 0.06 0.05 0.03
*Exceeds acute listed species LOC of 0.1

* * * Exceeds chronic LOC of 195 Direct Effects to Non

- Target Terrestrial Invertebrates Honey bee toxicity data were not available for paclobutrazol. Consequently, a non

- definitive toxicity value was used based on other structurally similar chemicals. The risks to terrestrial
insects are discussed in the Risk Description Section of this document.

Direct Effects to Terrestrial and Wetland/Riparian Plants TerrPlant was used to model potential runoff and spray dri ft effects from the different paclobutrazol uses (Table 27) . The maximum application rates for turf, ornamental tree soil injection/basal drench, seed tre atment (peppe r, cucurbits, tomato , broccoli, cauliflower, cabbage ), potted ornamentals

– spray, and p otted ornamentals

– drench were used to calculate risk quotients for semi

- aquatic and upland terrestrial plants. Insufficient data were available to calculate risk quotients for non

- listed monocots; thus this group will be discussed
in the Risk Descriptio n Sectio n

.

For turf, risk quotients ranged from 0.13 to 78.75. LOCs were exceeded for listed monocots (semi

- aquatic), listed dicots (dry and semi

- aquatic), and non

- listed dicots (dry and semi

aquatic).

For ornamental tree soil injection and basal drench , risk quotients ranged from <0.1 to 63.33. LOCs were exceeded for listed monocots (semi

- aquatic), listed dicots (dry and semi

- aquatic),
and non

- listed dicots (dry and semi

- aquatic).

For the seed tre atments (cucurbits, pepper, tomato , broccoli, cauliflow er, cabbage ), risk quotients were all <0.1. Consequently, none of the seed treatments exceeded the LOC.

For the potted ornamentals spray treatment, risk quotients ranged from < 0.1 to 26. LOCs were exceeded for listed dicots (dry and semi

- aquatic) and non

- listed dicots (semi

- aquatic only).

For the potted ornamentals drench application, risk quotients ranged from <0.1 to 610. Risk quotients exceeded the LOC for dry and semi

- a quatic monocots (listed) and dicots (listed and

non

- listed).

Table 2 7. Summary of risk quotient values for plants in dry and semi

- aquatic a r eas exposed to paclobutrazol through runoff and/or spray d rift
Plant Type Listed Status Dry Semi

- Aquatic Spray Drift 4
Profile 2SC on Turf

– 1 ground application at 0.75 lb ai/A

Monocot non

- listed N/A N/A N/A
Monocot l isted 1 0.32 2.22* ** 0.13
Dicot non

- listed 2 2.50* ** 17.50* ** 0.8396 Plant Type Listed Status Dry Semi

- Aquatic Spray Drift 4

Dicot l isted 3 11.25* ** 78.75* ** 3.75* ** Paclobutrazol 2SC Soil Injection /Basal Drench for Ornamental Trees

– 1 application at 3 inches deep at 1.9 lb ai/A

Monocot non

- listed N/A N/A N/A
Monocot l isted 1 0.18 1.78* ** N/A
Dicot non

- listed 2 1.41* ** 14.07* ** N/A
Dicot l isted 3 6.33* ** 63.33* ** N/A Paclobutrazol 2SC Seed Treatment for Cucurbits

– 1 application at 3 inches deep at 0.00029 lb ai/A

Monocot non

- listed N/A N/A N/A
Monocot l isted 1 <0.1 <0.1 N/A
Dicot non

- listed 2 <0.1 <0.1 N/A
Dicot l isted 3 <0.1 <0.1 N/A Paclobutrazol 2SC Seed Treatment for Pepper

– 1 application at 3 inches deep at 0.00079 lb ai/A

Monocot non

- listed N/A N/A N/A
Monocot l isted 1 <0.1 <0.1 N/A
Dicot non

- listed 2 <0.1 <0.1 N/A
Dicot l isted 3 <0.1 <0.1 N/A
Paclobutrazol 2SC Seed Treatment for Tomato

– 1 application at 3 inches deep at 0.00040 lb ai/A

Monocot non

- listed N/A N/A N/A
Monocot l isted 1 <0.1 <0.1 N/A
Dicot non

- listed 2 <0.1 <0.1 N/A
Dicot l isted 3 <0.1 <0.1 N/A Paclobutrazol 2SC Seed Treatment for Broccoli

– 1 application at 3 inches deep at 0.000096 lb ai/A

Monocot non

- listed N/A N/A N/A
Monocot listed 1 <0.1 <0.1 N/A
Dicot non

- listed 2 <0.1 <0.1 N/A
Dicot l isted 3 <0.1 <0.1 N/A Paclobutrazol 2SC Seed Treatment for Cauliflower

– 1 application at 3 inches deep at 0.000064 lb ai/A

Monocot non

- listed N/A N/A N/A
Monocot listed 1 <0.1 <0.1 N/A
Dicot non

- listed 2 <0.1 <0.1 N/A
Dicot l isted 3 <0.1 <0.1 N/A Paclobutrazol 2SC Seed Treatment for Cabbage

– 1 application at 3 inches deep at 0.000012 lb ai/A

Monocot non

- listed N/A N/A N/A
Monocot listed 1 <0.1 <0.1 N/A
Dicot non

- listed 2 <0.1 <0.1 N/A97 Plant Type Listed Status Dry Semi

- Aquatic Spray Drift 4

Dicot l isted 3 <0.1 <0.1 N/A Bonzi II Spray for Potted Ornamentals for Transplant

– 1 application at 0.26 lb ai/A

Monocot non

- listed N/A N/A N/A
Monocot l isted 1 <0.1 0.73 N/A
Dicot non

- listed 2 0.58 5.78* ** N/A
Dicot l isted 3 2.60* ** 26.00* ** N/A
Bonzi II Drench for Potted Ornamentals for Transplant

– 1 application at 6.1 lb ai/A

Monocot non

- listed N/A N/A N/A
Monocot l isted 1 1.72* ** 17.18* ** N/A
Dicot non

- listed 2 13.56* ** 135.56* ** N/A
Dicot l isted 3 61.00* ** 610.00* ** N/A

* ** Exceeds LOC of 1.

1 The vegetative vigor NOAEC used in the risk quotient calculation was based on the 5 th percentile as calculated from a distribution of data from cyproconazole, metconazol e , and tebuconazole.

2 The seedling emergence EC 25 used in the risk quotient calculation was based on the 5 th percentile as calculated from a distribution of data from cyproconazole, tebuconazole, and triticonazole.

3 The seedling emergence NOAEC used in the risk q uotient calculation was based on the 5 th percentile as calculated from a distribution of data from cyproconazole, triticonazole, and metconazole.

4 Spray drift was only a potential exposure route for the turf use.

Direct Effects to Freshwater Fish (Amphibians), Invertebrates and Estuarine

Marine Fish (Amphibians) and Invertebrates and Aquatic Plants Fish, aquatic i nvertebrate s, and aquatic plant risk quotients are calculated using aquatic EECs
derived as described in the exposure analysis using PRZM/EXAMS in conjunction with selected acute and chronic fish and aquatic invertebrate toxicity values

. A range of months were considered, thus the risk quotient s are presented as a range instead of a single value.

P aclobutrazol is persistent in aquatic environments

, thus a n accumulation of paclobutrazol was modeled during the 30 year pond simulations, as described earlier for paclobutrazol applied to FL Nursery

. The calculated risk quotient s are based on total toxic residue exposure from the parent ( paclobutrazol ) and its major degradates (CGA149907 and NOA457654) for the aquatic environment

.

Freshwater Fish and Aquatic

- Phase Amphibians

– Acute Risk For freshwater fish, acute risk quotients ranged from < 0. 1 to 0.0 2 and did not exc eed the
listed species acute LOC of 0. 05 for any of the uses

. Freshwater aquatic

- phase amphibian

acute risk quotients ranged from < 0.0 1 to 0.0 4 and also did not exceed the listed acute LOC
of 0. 05 for any of the uses (Table 28)

.98 Freshwater Fish and Aquatic

- Phase Amphibians

– Chronic Risk For freshwater fish, r isk quotients ranged from <0.1 to 6.8 for ornamentals assuming an

a pplication rate of 2.5 lb ai/A . All but the RQs from the Califo rnia scenario exceeded the
LOC of 1. Risk quotients ranged from <0.1 to 1.5 fo r ornamentals assuming an application
rate of 0.56 lb ai/A . Depending on the month and application location, the high end risk quotients exceeded the LOC of 1. For turf, risk quotients ranged from 0.43 to 1.4 with only the high end Pennsylvania scenario exceeding the LOC of 1 (Table 28)

.

Table 28. Acute and chronic risks from paclobutrazol to freshwater fish and

a mphibians

Aquatic Exposure (model) Use Scenario (modeled rate) Environmental Column Freshwater Fish Acute RQ (Peak EEC/LC 50 ) LC 50 = 15,900 μg ai/L Freshwater Fish Chronic RQ (60

- Day EEC/ NOAEC) NOAEC = 49 μg ai/L Freshwater Amphibian Acute RQ (Peak EEC/LC 50 ) LC 50 = 8900 μg ai/L Total Toxic Residue (Paclobutrazol plu s CGA 149907 and NOA 457654 ) 1

Surface Water (Tier 2 PRZM/EXAMS) Ornamentals: CA Ornamentals STD FL Ornamentals STD MI Ornamentals STD NJ Ornamentals STD OR Ornamentals STD
TN Ornamentals STD (1 app. X 2.5 lb ai/A)

Water <0.01

- <0.01 0.01

- 0.02 0.01

- 0.02

< 0.01

- 0.02 <0.01

- 0.01 0.01

- 0.02 < 0 .1

- 0.26 2 .9

- 6.8* ** 4.0

- 6.1* ** 2.9

- 5.2* ** 1.1

- 2.1* ** 3.0

- 5.2 * ** <0.01

- <0.01 0.02

- 0.04 0.02

- 0.03 0.02

- 0.03 0.01

- 0.01 0.02

- 0.03

Ornamentals: CA Ornamentals STD FL Ornamentals STD MI Ornamentals STD NJ Ornamentals STD OR Ornamentals STD
TN Ornamentals STD (1 app. X 0.56 lb ai/A) <0.01

- <0.01 <0.01

- <0.01 <0.01

- <0.01 <0.01

- <0.01 <0.01

- <0.01 <0.01

- <0.01 < 0 .1

- 0.1 0.65

- 1.5* ** 0.90

- 1.3* ** 0.65

- 1.2* **
0.24

- 0.47 0.7

- 1.2 * ** <0.01

- 0<0.01 <0.01

- 0.01 <0.01

- 0.01 <0.01

- 0.01 <0.01

- < 0.01 <0.01

- 0.01

Turf: FL Turf STD PA Turf STD (3 app. [2 app. X 0.75 lb and 1 app. X 0.5 lb] ai/A) <0.01

- <0.01 <0.01

- <0.01 0.43

- 0.80 0.71

- 1.4* ** <0.01

- <0.01 <0.01

- 0.01

Parent Paclobutrazol Only 2

FL Ornamentals STD (1 app. X 2.5 lb ai/A)

Water 0.01 3.8* ** 0.02

PA Turf STD (3 app. [2 app. X 0.75 and 1 app. X 0.5 lb] ai/A <0.01 1.0* ** 0.01

1 Multiple months were modeled; the range of RQs represents the highest and lowest EECs.

2 Exposure of parent only based on highest exposure scenarios (FL Ornamentals STD and PA Turf STD) identified from t otal toxic residue simulations.99 Aquatic Exposure (model) Use Scenario (modeled rate) Environmental Column Freshwater Fish Acute RQ (Peak EEC/LC 50 ) LC 50 = 15,900 μg ai/L Freshwater Fish Chronic RQ (60

- Day EEC/ NOAEC) NOAEC = 49 μg ai/L Freshwater Amphibian Acute RQ (Peak EEC/LC 50 ) LC 50 = 8900 μg ai/L

* ** Exceeds chronic LOC (1)

Estuarine/Marine Fish

– Acute Risk
For estuarine/marine fish

, risk quotients ranged from < 0.01 to 0.21 for ornamentals, assuming a n application rate of 2.5 lb ai/A . Specifically, all but the California scenario and
the lower bound estimate in the Oregon scenario exceeded the acute listed species LOC of
0.05 . In addition, the upper bound estimate of the 0.56 lb ai/A ornamentals in the Florida scenario (risk quotient = 0.05 ) equaled the acute listed species LOC of 0.05. The turf scenarios did not yield risk qu otients that exceeded the LOC (Table 29)

.

Estuarine/Marine Fish

– Chronic Risk

For estuar ine/marine fish, risk quotients ranged from <1 to 83 for the ornamental scenario with a 2.5 lb ai/A application rate , <1 to 18 for ornamentals with a 0.56 lb ai/A application

rate , and 5 to 17 for turf scenarios. All of the risk quotients except some of t he California
scenario s were above the LOC of 1 (Table 29)

.

Table 29. Acute and chronic risks from p aclobutrazol to estuarine/m arine f ish

Aquatic Exposure (model) Use Scenario (modeled rate) Environmental Column Estuarine / Marine Fish Acute RQ (Peak EEC/LC 50 ) LC 50 = 1580 μg ai/L 1 Estuarine / Marine Fish Chronic RQ (60

- Day EEC/ NOAEC) NOAEC = 4 μg ai/L 2
Total Toxic Residue (Paclobutrazol plus CGA 149907 and NOA 457654 ) 3,4

Surface Water ( Tier 2 PRZM/EXAMS) Ornamentals: CA Ornamentals STD
FL Ornamentals STD MI Ornamentals STD NJ Ornamentals STD OR Ornamentals STD
TN Ornamentals STD (1 app. X 2.5 lb ai/A) Water < 0

. 0 1

- 0.01 0.09

- 0.21* 0.12

- 0.19 * 0.09

- 0.16* 0.03

- 0.07* 0.09

- 0.16 * <1

- 3.2 *** 35

- 83* ** 49

- 75* ** 36

- 64* ** 13

- 26* ** 36

- 64 ***

Ornamentals: CA Ornamentals STD FL Ornamentals STD MI Ornamentals STD NJ Ornamentals STD OR Ornamentals STD
TN Ornamentals STD (1 app. X 0.56 lb ai/A) < 0

. 00 1

- 0 .002 0.02

- 0.05*
0.03

- 0.04 0.02

- 0.04 0.008

- 0.01 0.02

- 0.04 <1

- 0.7 8

- 18* ** 11

- 17* ** 8

- 14* ** 3

- 6* ** 8

- 14 ***100 Aquatic Exposure (model) Use Scenario (modeled rate) Environmental Column Estuarine / Marine Fish Acute RQ (Peak EEC/LC 50 ) LC 50 = 1580 μg ai/L 1 Estuarine / Marine Fish Chronic RQ (60

- Day EEC/ NOAEC) NOAEC = 4 μg ai/L 2

Turf: FL Turf STD PA Turf STD (3 app. [2 app. X 0.75 lb and 1 app. X 0.5 lb] ai/A) 0.01

- 0.02 0.02

- 0.04 5

- 10* ** 9

- 17* **

Parent Paclobutrazol Only 5

FL Ornamentals STD (1 app. X 2.5 lb ai/A)

Water 0.11* 46 ***

PA Turf STD (3 app. [2 app. X 0.75 and 1 app. X 0.5 lb] ai/A 0.03 13 ***

1 The LC 50 used in the risk quotient calculation was based on the 5 th percentile as calculated from a distribution of data from cyproconazole, fenbuconazole, hexaconazole, metconazole, mycobutanil, and tebuconazole.

2 The NOAEC used in the risk quotient calculation was based on the 5 th percentile as calculated from a distribution of data from metconazole, tebuconazole, and triticonazole.

3 Multiple months were modeled; the ran ge of RQs represents the highest and lowest EECs.

4 Total toxic residue simulation includes two metabolites (CGA 149907and NOA 457654 )

5 Exposure of parent only based on highest exposure scenarios (FL Ornamentals STD and PA Turf STD) identified from t otal toxic residue simulations.
*E xceeds acute listed species LOC (0.05 )

* ** Exceeds ch ronic LOC (1)

Freshwater Invertebrates

– Acute Risk

F or freshwater mollusks

, risk quotients ranged from < 0.0 1 to 0.0 3 and did not exceed the
LOC of 0.05 ; therefore, acute risks to freshwater mollusks are not anticipated. For
freshwater invertebrates

, t he acute LOC of 0.5 (non

- listed species) was exceeded for the 2.5
lb ai/A Florida ornamental , Michigan ornamental, and New Jersey ornamental scenarios. All
other ornamental and turf scenarios had risk quotients that exceeded the acute listed species
LOC of 0.05 (Table 30).

Freshwater Invertebrates

– Chronic Risk

For chronic risk, risk quotients ranged from <0.01 to 37. A ll but some of the California
scenarios exceeded the LOC of 1, regardless of the month of application, the application rate,
or the inclus ion of major paclobutrazol degra dates (Table 30).

Table 30

. Acute and chronic risks from p aclobutrazol to freshwater i nvertebrates

Aquatic Exposure (model) Use Scenario (modeled rate) Environmental Column Freshwater Invertebrate Acute RQ Freshwater Invertebrate Chronic RQ Freshwater Mollusk Acute RQ101 (Peak EEC/EC 50 ) EC 50 = 240 μg ai/L (60

- Day EEC/ NOAEC) NOAEC = 9 μg ai/L 1 (Peak EEC/LC 50 ) LC 50 = 12600 μg ai/L Total Toxic Residue (Paclobutrazol plus CGA 149907 and NOA 457654 ) 2 ,3

Surface Water ( Tier 2 PRZM/EXAMS) Ornamentals: CA Ornamentals STD FL Ornamentals STD MI Ornamentals STD NJ Ornamentals STD OR Ornamentals STD
TN Ornamentals STD (1 app. X 2.5 lb ai/A)

Water < 0

. 01

- 0.05 * 0.61

- 1.4** 0.83

- 1.3* * 0.60

- 1.1 ** 0.22

- 0.43* 0.6 1

- 1.1 ** < 0 .0 1

- 1.4 *** 16

- 37* ** 22

- 33* ** 16

- 28* ** 5.8

- 11* ** 16

- 28 *** <0.01

- <0.01 0.01

- 0.03 0.02

- 0.02 0.01

- 0.02 <0.01

- 0.01 0.01

- 0.02

Ornamentals: CA Ornamentals STD
FL Ornamentals STD MI Ornamentals STD NJ Ornamentals STD OR Ornamentals STD
TN Ornamentals STD (1 app. X 0.56 lb ai/A) < 0. 01

- 0.01 0.13

- 0.31 * 0.18

- 0.28* 0.13

- 0.24* 0.05

- 0.10* 0.13

- 0.24 * < 0. 0 1

- .031 3.6

- 8.1* ** 4.9

- 7.3* ** 3.6

- 6.3* ** 1.3

- 2.6* ** 3.6

- 6.3 *** < 0.01

- <0.01 <0.01

- 0.01 <0.01

- 0.01 <0.01

- 0.01 <0.01

- <0.01 <0.01

- 0.01

Turf: FL Turf STD PA Turf STD (3 app. [2 app. X 0.75 lb and 1 app. X 0.5 lb] ai/A) 0.09

- 0.16* 0.15

- 0.28* 2.3

- 4.3* ** 3.9

- 7.6* ** <0.01

- <0.01 <0.01

- 0.01

Parent Paclobutrazol Only 4

FL Ornamentals STD (1 app. X 2.5 lb ai/A)

Water 0.78** 20* ** 0.01

PA Turf STD (3 app. [2 app. X 0.75 and 1 app. X 0.5 lb] ai/A 0.21* 5.7* ** <0.01

1 The NOAEC used in the risk quotient calculation was based on the 5 th percentile as calculated from a distribution of data from cyproconazole, fenbuconazole, hexaconazole, metconazole, tebuconazole, triadimefon, triadimenol, and triticonazole.

2 Multiple months were modeled; the range of RQs represents the highest and lowest EECs.

3 Total toxic residue simulation includes two metabolites (CGA 149907and NOA 457654 )

4 Exposure of parent only based on highest exposure scenarios (FL Ornamentals STD and PA Turf STD) identified from t otal toxic residue simulations.

* E xceeds acute listed species LOC (0.05 )

** Exceeds acute non

- listed species LOC (0.5)

* ** Exceeds chronic LOC (1)

Estuarine/Marine Invertebrates

– Acute Risk
For estuarine/marine invertebrates

, risk quotients ranged from <0.01 to 1.4 for all uses of paclobutrazol. The acute non

- listed species LOC (0.5) was exceeded for the Florida, Michigan, and New Jersey 2.5 lb ai/A application to ornamentals as well as the Florida
ornamental s 2.5 lb ai/A par ent paclobutrazol

- only scenario. With the exception of some of102 the California scenarios, the acute listed species LOC (0.05 ) was equaled or exceeded (Table 31).

Estuarine/Marine Invertebrates

– Chronic Risk For estuarine/marine invertebrates, risk quotients ranged from <0.1 to 9.5 for ornamental scenarios at 2.5 lb ai/A. All of these risk quotients exceeded the LOC of 1. The risk quotients for the lower ornamental application rate (0.56 lb ai/A) ranged from <0.1 to 2.1.
The Florida , Tennessee, and New Jersey scenarios each had one risk quotient that exceeded the LOC (1), whereas all of the risk quotients generated in the Michigan scenario exceeded the LOC. Turf risk quotients ranged from 0.60 to 2.0 with b oth scenarios having at least one risk quotient that exceeded the LOC of 1 (Table 31).

Table 31. Acute and chronic risks from p aclobutrazol to estuarine/marine
i nvertebrates

Aquatic Exposure (model) Use Scenario (modeled rate) Environmental Column Estuarine / Marine
Invertebrates Acute RQ (Peak EEC/EC 50 ) EC 50 = 240 μg ai/L 1 Estuarine / Marine
Invertebrates Chronic RQ (60

- Day EEC/ NOAEC) NOAEC = 35 μg ai/L 2
Total Toxic Residue (Paclobutrazol plus CGA 149907 and NOA 457654 ) 3 ,4

Surface Water ( Tier 2 PRZM/EXAMS) Ornamentals: CA Ornamentals STD FL Ornamentals STD MI Ornamentals STD NJ Ornamentals STD OR Ornamentals STD
TN Ornamentals STD (1 app. X 2.5 lb ai/A)

Water < 0.0 1

- 0.05 * 0.61

- 1.4** 0.83

- 1.3** 0.60

- 1.1** 0.22

- 0.43* 0.61

- 1.1 ** < 0. 1

- 0.4 4.0

- 9.5* ** 5.6

- 8.6* * * 4.1

- 7.3* * * 1.5

- 2.9 ** * 4.1

- 7.3 ***

Ornamentals: CA Ornamentals STD FL Ornamentals STD MI Ornamentals STD NJ Ornamentals STD OR Ornamentals STD
TN Ornamentals STD (1 app. X 0.56 lb ai/A) < 0.0 1

- 0.01 0.13

- 0.31* 0.18

- 0.28* 0.13

- 0.24* 0.05

- 0.10* 0. 13

- 0.2 4* < 0. 1

- 0.1 0.91

- 2.1* ** 1.3

- 1.9* ** 0.91

- 1.6* * *
0.34

- 0.66 0.9

- 1.6 ***

Turf: FL Turf STD PA Turf STD (3 app. [2 app. X 0.75 lb and 1 app. X 0.5 lb] ai/A) 0.09

- 0.16 * 0.15

- 0.28 * 0.60

- 1.1* * * 1.0

- 2.0* * *

Parent Paclobutrazol Only 5

FL Ornamentals STD (1 app. X 2.5 lb ai/A) Water 0.78** 5.3* **

PA Turf STD 0.21* 1.5* * *103 Aquatic Exposure (model) Use Scenario (modeled rate) Environmental Column Estuarine / Marine Invertebrates Acute RQ (Peak EEC/EC 50 ) EC 50 = 240 μg ai/L 1 Estuarine / Marine Invertebrates Chronic RQ (60

- Day EEC/ NOAEC) NOAEC = 35 μg ai/L 2
(3 app. [2 app. X 0.75 and 1 app. X 0.5 lb] ai/A

1 The EC 50 used in the risk quotient calculation was based on the 5 th percentile as calculated from a distribution of data from cyproconazole, fe n buconazole, hexaconazole, metconazole, mycobutranil, tebuconazole, and triticonazole.

2 The NOAEC used in the risk quotie nt calculation was based on tebuconazole, the only structurally

similar triazole available with chronic estuarine/marine invertebrate toxicity data.

3 Multiple months were modeled; the range of RQs represents the highest and lowest EECs.

4 Total toxic residu e simulation includes two metabolites (CGA 149907and NOA 457654 )

5 Exposure of parent only based on highest exposure scenarios (FL Ornamentals STD and PA Turf STD) identified from t otal toxic residue simulations.

* Exceeds acute listed species LOC (0. 0 5) **Exceeds acute non

- listed species LOC (0.5)

* * * Exceeds chronic LOC (1)

Aquatic Vascular and Non

- vascular Plants

F or aquatic vascular plan t s , risk quotients ranged from <0.1 to 42. All of the values , except some of the California scenarios, exceeded the LOC of 1, indicating potential risk of registered paclobutrazol applications to aquatic vascular plants. For aquatic non

- vascular plants, risk quotients ranged from <0.01 to 0.01 and did not exceed the LOC of 1 (Table 32).

Table 32. Risks from p aclobutrazol to aquatic vascular and non

- vascular p lants

Aquatic Exposure (model) Use Scenario (modeled rate) Environmental Column Aquatic Vascular Plant RQ (Peak EEC/EC 50 ) EC 50 = 8 μg ai/L 1 Aquatic Non

Vascular Plant RQ (Peak EEC/ EC 50 ) EC 50 = 40800 μg ai/L

Total Toxic Residue (Paclobutrazol plus CGA 149907 and NOA 457654 ) 2 ,3

Surface Water ( Tier 2 PRZM/EXAMS) Ornamentals: CA Ornamentals STD FL Ornamentals STD MI Ornamentals STD NJ Ornamentals STD OR Ornamentals STD
TN Ornamentals STD (1 app. X 2.5 lb ai/A) Water < 0. 1

- 1.6 *** 18

- 42* ** 25

- 38* ** 18

- 32* ** 6.5

- 13* ** 18.3

- 32.3 *** <0.01

- <0.01 <0.01

- 0.01 <0.01

- 0.01 <0.01

- 0.01 <0.01

- <0.01 <0.01

- 0.01

Ornamentals: CA Ornamentals STD FL Ornamentals STD MI Ornamentals STD < 0. 1

- 0.4 4.0

- 9.3* ** 5.5

- 8.4* ** <0.01

- <0.01 <0.01

- <0.01 <0.01

- <0.01104 NJ Ornamentals STD OR Ornamentals STD
TN Ornamentals STD (1 app. X 0.56 lb ai/A) 4.0

- 7.1* ** 1.5

- 2.9* ** 4.0

- 7.1 *** <0.01

- <0.01 <0.01

- <0.01 <0.01

- <0.01

Turf: FL Turf STD PA Turf STD (3 app. [2 app. X 0.75 lb and 1 app. X 0.5 lb] ai/A) 2.7

- 4.9* ** 4.4

- 8.5* ** <0.01

- <0.01 <0.01

- <0.01

Parent Paclobutrazol Only 3

FL Ornamentals STD (1 app. X 2.5 lb ai/A)

Water 23* ** <0.01

PA Turf STD (3 app. [2 app. X 0.75 and 1 app. X 0.5 lb] ai/A 6.4* ** <0.01

1 The EC 50 used in the risk quotient calculation was based on the 5 th percentile as calculated from a distribution of data from cyproconazole, metconazole, tebuconazole, and triticonazole

. 2 Multiple months were modeled; the range of RQs represents the highest and lowest EECs.

3 Exposure of parent only based on highest exposure scenarios (FL Ornamentals STD and PA Turf STD) identified from t otal toxic residue simulations.

* **Exceeds LOC (1 )

Probit Slope Response Analysis of LOC Values and Acute RQ Values As part of the risk estimation, the probability of mortality associated with the listed acute LOC values is estimated along with the probability of acute mortality occurring if exposure
at the EEC takes place . The probability of morta lity calculations are based on the probit slope dose

- response relationship. The probability of mortali ty for an exposed individual is calculated using an Excel spreadsheet tool IECV1.1 (Individual Effect Chance Model Version 1.1) developed by EFED of the U.S. EPA, OPP, Environmental Fate and Effects Division (June 22, 2004).

The model provides the option of inserting taxa

- specific probit slopes and confidence intervals. If specific information is not available, the model uses a default value of 4.5 for

t he probit slope and 2 and 9 for the upper and lower 95% confidence interval bounds. For paclobutrazol, taxa

- specific data were not available. For birds, the acute oral toxicity study yielded non

- definitive values, thus a probit slope could not be calcula ted. The mammal acute oral study did not calculate a probit slope. The freshwater fish and invertebrate toxicity information was taken from the open literature and did not provide enough information to calculate a probit slope. Finally, the estuarine/ma rine fish and invertebrate data were taken
from the 5 th percentile of structurally

- similar triazoles, thus probit slopes were not available for these groups either. The default values were used for all of the modeled scenarios.

Risk quotient values for comparison were chosen based on the results of the risk assessment. For freshwater fish and estuarine/marine fish, the LOC of 0.05 was chosen because none of105 risk quotients calculated from the paclobutrazol uses exceeded the LOC. Likewise, the LOC
of 0.1 was chosen for birds as the EECs did not exceed the non

- definitive toxicity value. For freshwater invertebrates and estuarine/marine invertebrates, the highest calculated risk quotient was chosen

– 0.35 for both cases. Several r isk quotients were considered for mammals. They were chosen based on application scenario and represent the highest RQ and the lowest RQ that exceeded the LOC (0.1) (Table 33 )

.

Table 33. Odds of mortality for an individual bird, mammal, fish, or aquatic invertebrate at selected acute risk quotient values for paclobutrazol
RQ Slope (default) 95% Confidence Interval (default) Odds (1 in...) 95% Confidence Interval (odds)
Mammal (turf app.) 0.11 4.5 2, 9 125,000 36.2

– 3.19 x 10 17

Mammal (soil injection) 0.34 4.5 2, 9 57 5.73

– 80,700

Mammal (soil injection) 0.13 4.5 2, 9 29,900 26.2

– 1.31 x 10 15

Bird 0.1 4.5 2, 9 294,000 44

– 8.86 x 10 18

Freshwater fish 0.05 4.5 2, 9 4.18 x 10 8 216

– 1.75 x 10 31

Estuarine/marine
fish 0.05 4.5 2, 9 4.18 x 10 8 216

– 1.75 x 10 31

Freshwater
invertebrates 0.35 4.5 2, 9 49.8 5.53

– 4.91 x 10 4

Estuarine/marine
invertebrates 0.35 4.5 2, 9 49.8 5.53

– 4.91 x 10 4



### Risk Description
The following section expl ain s the overall effect conclusions regarding the potential ecological risk from the various uses of paclobutrazol . The risk conclusions take into
consideration all lines of evidence, such as the risk estimates (risk quotient results) ; information on the od ds of mortality for th e acute risk quotient values ; comparisons of non

definitive endpoints ( i.e ., limit tests) to EECs; information such as monitoring data, field studies, and incident data that may provide additional insights into the likelihood of

exposure ; and other factor s that modify the likelihood of exposure such as timing of application, overlap of area affected and the degree of effect with the presence/absence of taxa, species sensitivity distribution, and presence/absence of dietary items

.106 Exposure Uncertainties
Th ere were a number of exposure uncertainties that are applicable to most or all of the scenarios that were considered. Rather than repeat them for each section, they are described
below.

There is uncertainty concerning the expected exposure of paclobutr azol in the environment. For all uses but turf, the amount of paclobutrazol that could be applied within a geographica l area is unclear. BEAD estimated a paclobutrazol application rate in pounds of active ingredient per acre, based on labels for tree inj ection, soil injection/drench, potted ornamentals drench, and seed treatments. A number of assumptions were made in these

sc enarios to derive an environmentally protective estimate of the amount of paclobutrazol that could be applied within an acre ( see P esticide Use Overview S ection for details ). For terrestrial scenarios, the concentration of paclobutrazol in leaves could have been more directly calculated from the directions on the label (grams of ai/tree); however, it was decided for consistency sake to use the same application rates in lb ai/A for both the terrestrial and aquatic analyses.

For many of the endpoints typically used in risk assessments, no paclobutrazol

- specific data
were available. In these instances, surrogate data from structurally

- similar triazoles were used in lieu of paclobutrazol data ( see the Effects Characterization Section for details). In some instances, the surrogate data may have overestimated the toxicity threshold for certain groups of organisms, resulting in risk quotie nts that exceed the level of concern. Surrogate data were employed for the following endpoints: honey bee acute contact toxicity, seedling emergence, vegetative vigor (monocots only), estuarine/marine fish acute and chronic toxicity, estuarine/marine inv ertebrates acute and chronic toxicity, aquatic vascular plants. Where appropriate, changes to the RQs from using the most sensitive toxicity value from the structurally similar triazoles are discussed in the taxa specific sections below

.

There is also un certainty regarding the concentration of paclobutrazol that would be available in edible plant parts. Paclobutrazol is a systemic chemical and is transported throughout the entire plant. This characteristic is what makes tree injections, drenches, etc. e fficient applications methods. When estimating the concentration of paclobutrazol that would be
present in tree leaves (tree injection, soil injection/drench, and potted ornamental drench), it was assumed that the entire application of paclobutrazol would concentrate in the leaves. This may be an overestimate as paclobutrazol may be distributed throughout the tree, or it may more slowly “time release” than immediately concentrate in the leaves of the plant, or it may be metabolized by the tree. For seed treatments, it was assumed that the entire application of paclobutrazol would be equally distributed throughout the transplanted pepper,107 tomato, cucurbit , broccoli, cauliflower, or cabbage and that a n organism would have the ability to consume the entire p lant.

There is uncertainty regarding the biomass estimates for trees and seedlings. For trees, general hardwood and softwood equations were used along with the size assumptions that BEAD used in its calculations of paclobutrazol application rates. These are general equations/assumptions and may over or underestimate biomass, depending on the tree species and its geographical location. For seeds, tomato transplant data were us ed and applied to cucurbits, peppers , broccoli, cauliflower, and cabbage as wel l.

There is uncertainty regarding the percent uptake of paclobutrazol from soil drench, soil injection, and seed treatment applications. The basic premise for paclobutrazol applications made to soil is that most of the chemical will be taken up into th e plant via it s roots; however,
few data are available that document the efficiency of this mechanism. Sharma and Awasthi (2005) demonstrate for soil drenches of paclobutrazol to mango trees, that residues in the soil range from 1 to 3% for a single yearl y application, ~25% for an application in year 2, and 30 to 54% for an application in year 3. F or exposure pathways considered in the risk assessment that depend on paclobutrazol being available in the soil (i.e. runoff scenarios), it was
assumed that 100 percent of the applied paclobutrazol was in the soil and that none of it h ad been taken up into the plant; however, alternative scenarios (75%, 50%, and 25%) uptake are also presented. Likewise, when considering paclobutrazol exposure through soil from t he seed treatments, it was assumed that all of the paclobutrazol was available in the soil and that none of it had been absorbed into the seed through the seed coat. These are very conservative assumptions that were made in the absence of data; they may o ver

- estimate risk

to non

- target terrestrial plants and aquatic organisms.

Since paclobutrazol is persistent in aquatic environments , there was a modeled accumulation
of paclobutrazol in the PRZM/EXAMS standard farm pond throughout th e 30 year
simulations , as demonstrated by the daily EECs for applications to FL nursery in the Figure
3

. Accumulation reached the plateau within a few years during the model simulation. Based
on the non

- linear accumulation as predicted in the Figure 3

, t he 1

- in

- 10

- year conce ntrations are expected to occur with continuing use of paclobut r azol; however, the time required to reach the chronic risk to animals or risk to plant s (level of concern = 1) may occur with the first application depending on application rate, management practices, location, and meteorological conditions ( e.g. potential adverse effects may occur to listed vascular plants and on a chronic basis immediately following the firs t season of paclobutrazol use in
nurseries in Florida). Potential risks to many aq uatic organisms from various paclobutrazol uses are expected to increase with continued paclobutrazol applications.108 F or the spray and drench applications to ornamental plants, it is unclear how many applications may take place . These treatments occu r in nursery/greenhouse settings. The applications may be made indoors, but then the potted plants are set outdoors to mature before shipping to market. This presents two levels of uncertainty. First, if potted plants are
stored outdoors for an extended period of time, they may warrant additional applications of paclobutrazol. Second, if the turnover rate of potted plants in outdoor storage areas is high, a discreet geographical area may be exposed to maximum paclobutrazol application rates many
times w ithin a growing season. These points were not taken into consideration in the risk assessment; it was assumed that only one application of paclobutrazol would occur when modeling spray and drench applications to potted ornamentals.

D IRECT E FFECTS TO T E RRESTRIAL B IRDS , R EPTILES , AND A MPHIBIANS Acute Risk
Acute dose

- based and dietary

- based risk quotients could not be calculated to evaluate the risks to birds because only non

- definitive acute toxicity data were available. Instead, the

non

- definitive toxic ity values were directly compared to the EECs (Table 34 ). In all cases,

n one of the dietary EECs were larger than the non

- definitive toxicity value s for bobwhite quail and mallard duck , thus

, the potential for acute risk is considered to be low for acute
dose

- based and dietary

- based exposure of non

- listed birds, reptiles, and land

- phase amphibians from paclobutrazol for all registered uses. Likewise, the probit slope response analysis indicated a 1 in 294,000 chance of mortality with exposure to paclobutr azol.

Table 34

. Comparison of the highest calculated dietary EEC for each use of paclobutrazol to the most sensitive avian toxicity value

Application Rate (Crop) Dietary
Item EEC (mg ai/kg

- bw) LD 50 (mallard) > 7913 mg ai/kg

- bw EEC (mg ai /kg

- diet) LC 50 (bobwhite) > 5000 mg ai/kg

- diet
3 ground spray applications at 0.75 lb ai/A (turf) Short g rass 390 390 <7913 343 343 < 5000

1 tree injection at 0.36 lb ai/A Leaves N/A N/A 212 212 < 5000

1 soil injection/drench at 1.9 lb ai/A Leaves N/A N/A 1058 1058 < 5000

1 spray application at 0.26 lb ai/A (potted ornamentals) Short grass 71 71 <7913 62.4 62.4 < 5000

1 drench application at 6.1 lb ai/A (potted ornamentals) Leaves N/A N/A 112 112 < 5000

1 seed treatment (pepper) Transplant N/A N/A 2.9 2.9 < 5000

Chronic Risk Chronic risk quotients were calculated for dietary

- based chronic risks. The soil injection/drench application of 1.9 lb ai/A t o trees was the only use to exceed the LOC (1). Risk quotients for both hardwoods (2.3) and softwoods (1.1) exceeded the LOC. These numbers indicate that there is a potential chronic risk for birds consuming non

- woody109 vegetative items (leaves were used a surrogate for fruit, flowers, seeds, and other n on

- woody foods) that have been treated with paclobutrazol via soil injection or basal drench; however, they are based on the very conservative assumption that 100 percent of the paclobutrazol application has been taken up by the tree and has concentrated i n the edible parts that a bird
may eat ( e.g., fruit, seeds, flowers)

. Less conservative assumptions of 75, 50, and 25 percent uptake by the tree were also modeled ( Table 35 )

.

Table 35. Paclobutrazol uptake scenarios for birds based on a hardwood EEC of 1058 mg ai/kg

- leaves, a softwood EEC of 483 mg ai/kg

- leaves, and a NOAEC of 453 mg ai/kg

diet
Paclobutrazol Uptake Tree Type EEC Risk Quotient

100% Hardwood 1058 2.3* **

Softwood 483 1.1* **

75% Hardwood 794 1.75* **

Softwood 362 0.80

50% Hardwood 529 1.17* **

Softwood 242 0.53

25% Hardwood 265 0.58

Softwood 121 0.27

* ** Exceeds the LOC of 1.

Based on the alternative paclobutrazol uptake scenarios, avian risk from the consumption of softwood leaves falls below the LOC when 75 percent uptake is assumed while the risk from hardwood leaf consumption is reduced below the LOC at 25 percent uptake. Data are not available that describe the rate of uptake by a tree, but given that the chemical’s efficacy relies on the uptake of paclobutrazol from the soil into the tree, it is possible that more than
25% of the chemical is absorbed into the tree.

The c hronic risk concern for birds is probably most relevant to a scenario where a large number of trees have been treated in an area (e.g., right

- of

- ways, large landscaping operations). Such scenarios may be limited in their occurrence because paclobutrazol, although registered for use in right

- of

- ways, is probably not the most cost effective way of controlling growth. Furthermore, use in landscapes would probably be targeted to specific trees, leaving many trees untreated.

Summary of Risks from Direct Eff ects A summary of the potential for acute and chronic risks to birds (surrogates for reptiles and
land

- phase amphibians) is listed below:110 • The potential for acute risk to non

- listed birds (surrogates for reptiles and land

- phase amphibians) is low, based on comparisons between dose

- based and dietary

- based EECs and toxicity data. For all uses, the EECs are much lower than the toxicity
value.

• The potential for chronic risk to birds (reptiles and land

- phase amphibians) exists as the risk quotients for soil injection/drench application s to trees exceeded the LOC.

D IRECT E FFECTS TO T ERRESTRIAL M AMMALS Acute Risk Soil injection/drench at 1.9 lb ai/A dose

- based risk quotients exceeded the acute listed LOC of 0.1 for small (15 g), medium (35 g) and large (1000 g) sized mammals. Risk quotients
were calculated for both hardwood s and softwoods for this use. All of t he risk quotients for
the hardw oods exceeded the LOC (0.34, 0.29 , and 0.15 ) while the risk quotients for the
softwoods only exceeded f or small and medium

- sized mammals (0.16 and 0.13)

. The turf scenario also exceeded the acute listed LOC (0.1) for 15 and 35 g mammals consuming a strict diet of short grass. No other acute dose

- based risk quotients exceeded the LOC for any
other use. It was only possible to calculate dietary risk quotients for the turf and potted ornamental spray uses; neither of these exceeded the LOC.

For the soil injection/drench the risk quotients indicate that there is a potential acute risk for mammals consuming t he leaves of trees that have been treated with paclobutrazol via soil injection or basal drench . The probit slope response analysis further characterizes this risk by indicating a 1 in 57 chance of mortality with exposure to paclobutrazol. However, these risk quotients are based on the very conservative assumption that 100 percent of the paclobutrazol application has been taken up by the tree and has concentrated in the edible parts that a mammal may eat. Less conservative assumptions of 75, 50, and 25 p ercent uptake by the tree were also modeled ( Table 36 )

.

Table 36. Paclobutrazol uptake scenarios based on adjusted mammal LD 50 s of 2936 mg ai/kg

- bw (15 g), 2376 mg ai/kg

- bw (35 g), and 1028 mg ai/kg

- bw (1000 g)

Paclobutrazol Uptake Tree Type EEC Risk Quotient 15 g 35 g 1000 g 15 g 35 g 1000 g

100% Hardwood 1005 698 159 0.34* 0.29* 0.15*

Softwood 459 319 72 0.16* 0.13* 0.07

75% Hardwood 754 524 119 0.26* 0.22* 0.12*

Softwood 344 239 54 0.12* 0.10* 0.05

50% Hardwood 503 349 80 0.17* 0.15* 0.08

Softwood 230 160 36 0.08 0.07 0.04

25% Hardwood 251 175 40 0.09 0.07 0.04

Softwood 115 80 18 0.04 0.03 0.02111 *Exceeds the LOC of 0.1 (listed species).

Based on the alternative paclobutrazol uptake scenarios, mammal risk from the consumption of softwood leaves falls below the LOC when 50 percent uptake is assumed while the risk from hardwood leaf consumption is reduced below the LOC at 25 percent uptake. Data are not available that describe the rate of uptake by a tree, but given that chemic al’s efficacy relies on the uptake of paclobutrazol from the soil into the tree, it is likely that more than
25% of the chemical is absorbed into the tree.

For turf, the acute dose

- based risk quotients for small and medium

- sized mammals slightly
exceeded the listed species LOC of 0.1. Supporting this, the probit slope response analysis (using the highest risk quotient of 0.11) indicated a 1 in 125,000 chance of mortality with paclobutrazol exposure. The scenario used to calculate the risk quotients was o verly conservative because 0.75 lb ai/A was applied 3 times, thus exceeding the seasonal maximum application rate of 2 lb ai/A. T

- REX’s limitations do not allow for uneven applications. Running the scenario with an application rate of 0.66 lb ai/A slight ly reduces the risk quotients to 0.1 for small mammals and 0.08 for medium mammals. One limitation of this scenario is that it does not apply the maximum single application rate of paclobutrazol (Table 37 ).

Table 37. Alternative turf scenarios for acu te mammal exposure using T

- REX

Scenario Food Item Acute Dose Risk Quotient 15 g 35 g 1000g 3 applications at
0.75 lb ai/A (28

- day interval) Short grass 0.11* 0.10* 0.05 Tall grass 0.05 0.04 0.02 Broadleaf plants/small insects 0.06 0.05 0.03 Fruits/pods/seeds/lg insects 0.01 0.01 <0.01

Granivores <0.01 <0.01 <0.01 3 applications at
0.66 lb ai/A (28

- day interval) Short grass 0.10* 0.08 0.04 Tall grass 0.04 0.04 0.02

Broadleaf plants/small insects 0.06 0.05 0.03 Fruits/pods/seeds/lg insects 0.01 0.01 <0.01

Granivores <0.01 <0.01 <0.01 *Exceeds the LOC of 0.1 (listed species)

Chronic Risk
Seed treatme nts to tomatoes, cucurbits, peppers , broccoli, cauliflower, and cabbage were the only paclobutrazol uses to not produce risk quotients that exceeded the LOC. Only dose

based chronic risk quotients were calculated for the seed treatmen t s.112 Paclobutrazol was applied to turf at 0.75 lb ai/A with an application interval of 28 da ys. Three applications were made (this exceeds the maximum application rate of 2 lb ai/A per season by 0.25 lb ai/A because of restrictions to T

- REX, but the results were not substantially different when lower application rates were used). Chronic dose

- ba sed risk quotients exceeded the chronic LOC of 1 for all size classes of mammals that feed on short grass (27.2

– 59.5), tall grass (12.5

– 27.3), broadleaf plants/small insects (15.3

– 33.5), and fruits/pods/seeds/large insects (1.70

– 3.72). Granivores was the only dietary class that did
not exceed dose

- based chronic risk quotients. For chronic dietary

- based risk, risk quotients exceeded the LOC for short grass (6.86), tall grass (3.14) and broadleaf plants/small insects (3.86).

Paclobutrazol was applied as a spray to potted ornamentals in a single application of 0.26 lb
ai/A. Chronic dose

- based risk quotients exceeded the LOC of 1 for all size classes of mammals that feed on short grass (4.96

– 10.8), tall grass (2.27

– 4.96), and broadleaf plant s/small insects (2.79

– 6.09). Fruit/pod/seed/large insect eaters and granivores were not at risk, based on chronic dose

- based risk quotients. Short grass eaters were the only dietary class that was at risk based on dietary

- based risk quotients (1.25).

Only chronic dose

- based risk quotients were calculated for the remaining uses. Paclobutrazol was applied as a tree injection at an equivalent rate of 0.36 lb ai/A. Applications to both hardwoods and softwoods were considered. Risk quotients for
hardwood s exceeded the LOC for all mammal size classes (17 to 37). For softwoods, only the 15 g mammal size class exceeded the LOC of 1 (1.6).

Paclobutrazol was applied to trees via soil injection/drench at rate of 1.9 lb ai/A. Applications to both hardwoods and softwoods were considered. Chronic dose

- based risk quotients exceeded the LOC of 1 for both classifications of trees as well as all mammal size classes. Hardwood risk quotients ranged from 83 to 183 and softwood risk quotients ranged
from 38 to 87. These numbers are based on the very conservative assumption that 100 percent of the paclobutrazol application has been taken up by the tree and has concentrated in the edible parts that a mammal may eat. Less conservative assumptions of 75, 50, and 25

per cent uptake by the tree were also modeled ( Table 38 )

.

Table 38. Paclobutrazol soil injection/drench uptake scenarios based on adjusted
mammal NOAEC s of 5.49 mg ai/kg

- bw (1 5 g), 4.45 mg ai/kg

- bw (35 g), and 1.92 mg ai/kg

- bw (1000 g)

Paclobutrazol Uptake T ree Type EEC Risk Quotient 15 g 35 g 1000 g 15 g 35 g 1000 g

100% Hardwood 1005 698 159 183* ** 157* ** 83* **

Softwood 459 319 72 87* ** 72* ** 38* **113 Paclobutrazol Uptake T ree Type EEC Risk Quotient 15 g 35 g 1000 g 15 g 35 g 1000 g

75% Hardwood 754 524 119 137* ** 118* ** 62* **

Softwood 344 239 54 63* ** 54* ** 28* **

50% Hardwood 503 349 80 92* ** 78* ** 42* **

Softwood 230 160 36 42* ** 36* ** 19* **

25% Hardwood 251 175 40 46* ** 39* ** 21* **

Softwood 115 80 18 21* ** 18* ** 9* **

* ** Exceeds the LOC of 1

Based on the alternative paclobutrazol uptake scenarios for the soil injection/drench, none of them result in risk quotients that are below the level of concern. This indicates that regardless of the exposure scenarios, the potential exists for chronic ri sk to all size classes of
mammals that feed on non

- woody vegetative food items

.

Paclobutrazol can be applied as a drench to potted ornamentals at 6.1 lb ai/A. For this scenario, woody hardwoods, woody softwoods, and non

- woody potted plants were
considere d. All scenarios yielded chronic dose

- based risk quotients above the LOC of 1 for all mammal size classes. Woody hardwoods risk quotients ranged from 5 to 11, woody softwoods risk quotients ranged from 2 to 4, and non

- woody risk quotients ranged from 9 t o 19. As with the soil injection/drench use, these scenarios assume 100 percent uptake of the paclobutrazol into the plant leaves (woody species) or entire plant (non

- woody species). Less conservative assumptions of 75, 50, and 25 percent uptake by the t ree were also modeled ( Table 39).

Table 39. Paclobutrazol drench uptake scenarios based on adjusted mammal NOAECs of 5.49 mg ai/kg

- bw (15 g), 4.45 mg ai/kg

- bw (35 g) , and 1.92 mg ai/kg

- bw (1000 g)

Paclobutrazol Uptake Tree Type EEC Risk Quotient

15 g 35 g 1000 g 15 g 35 g 1000 g

100% Hardwood 59 39 9 11* ** 9* ** 5* **

Softwood 23 16 3.6 4* ** 4* ** 2* **

Non

- woody 106 74 17 19* ** 17* ** 9* **

75% Hardwood 44 29 7 8* ** 6.5* ** 3.6* **

Softwood 17 12 2.7 3.1* ** 2.7* ** 1.4* **

Non

- woody 80 56 13 15* ** 13* ** 6.8* **

50% Hardwood 30 20 4.5 5.5* ** 4.5* ** 2.3* **

Softwood 12 8 1.8 2.2* ** 1.8* ** 0.94

Non

- woody 53 37 8.5 9.7* ** 8.3* ** 4.4* **
25% Hardwood 15 10 2 2.7* ** 2.2* ** 1.0* **114 Paclobutrazol Uptake Tree Type EEC Risk Quotient

15 g 35 g 1000 g 15 g 35 g 1000 g

Softwood 6 4 0.9 1.1* ** 0.90 0.47

Non

- woody 27 19 4.3 4.9* ** 4.3* ** 2.2* **

*Exceeds the LOC of 1

Based on the alternative paclobutrazol uptake scenarios for the potted ornamental drench, only three of them result in risk quotients that are below the level of concern: 50% uptake in
softwoods

– large mammals; 25% uptake in softwoods

– medium and large mammals. This
indicates that there is the potential of chronic risk to all size classes of ma mmals that feed on
tree leaves.

Summary of Risks from Direct Effects A summary of the potential for acute and chronic risks to mammals is listed below:

• The re is the potentia l for acute and ch r o nic risk to mammals for soil injection/drenches to trees at a 1.9 lb ai/A application rate. A cut e dose

- based risk quotients exceed ed the list ed LOC for all mammals in hardwoods and small and
medium

- sized mammals in softwoo ds ; reduced uptake scenarios lowered the risk quotients and eliminated all of them at 25 percent paclobutrazol uptake . Chronic
dose

- based risk quotients exceeded the LOC for all mammal size classes in
hardwoods and softwoods.

• The potential for acute and chronic risk to mammals exists for turf uses. Acute dose

based risk quotients exceeded the listed LOC for small and medium

- siz ed mammals; assuming a lower application rate (0.66 lb ai/A) reduced the magnitude of the risk quotients , but did not substantia lly alter the risk picture

. Chronic dose

- based and dietary

- based risk quotients exceeded the LOC for all size classes of mammals on
several varieties of food.

• The potential for chronic risk to mammals exists for potted ornamental spray uses.
Chronic dose

- based and dietary

- based risk quotients exceeded the LOC for multiple size classes of mammals and dietary items (dose

- based only).

• The potential for chronic risks to mammals exists from tree injection uses. Chronic
dose

- based risk quotients exceeded t he LOC for hardwoods (all mammal size classes) and softwoods (15 g mammals).

• The potential for chronic risks to mammals exists from drenches to ornamental potted plants at 6.1 lb ai/A. Chronic dose

- based risk quotients exceeded the LOC for hardwoods, soft woods, and non

- woody pla nts for all mammal size classes; for most cases, alternative paclobutrazol uptake scenarios did not reduce their magnitude enough to preclude risk.115 D IRECT E FFECTS TO T ERRESTRIAL I NVERTEBRATES Risk quotients could not be calculated for terrestrial invertebrates because only non

definitive data were available (from a surrogate chemical). In lieu of this, the EEC (converted to a dose) was compared directly with the toxicity value for honeybees. For both the turf and potted ornamental plant uses, the EEC was less than the contact LD 50 , thus direct effects to terrestrial invertebrates are not expected for contact exposures (Table 40 ). Acute oral toxicity could not be assessed because data were not available and the results of the

conta ct analysis were used as a surrogate for this route of exposure.

Table 40 . Comparison of Small and Large Insect EECs from Foliar Application of Paclobutrazol to the Extrapolated Acute Contact Honeybee Concentration
Application Rate (Crop) Dietary Item EEC (μg ai/bee ) Contact LD 50 1

( μg ai / bee)

Turf Large insects 12.9 24
Spray to potted ornamentals Large insects 4.5 24

1 This value was extrapolated from triticonazol because toxicity data were not available for paclobutrazol.

There was an open literature paper identified in ECOTOX that examined the effects of paclobutrazol residues on predatory mites (Oetting and Latimer 1995). Based on mortality rates, a 48

- hour NOAEC was established of 160 ppm for Orius insidiosus

. This sup ports the risk quotient analysis that risk s from acute contact exposure are not expected.

Summary of Risks from Direct Effects A summary of the potential for acute risks terrestrial invertebrates is listed below:

• The potential for acute risk to terrestrial invertebr ates is not expected for terrestrial
invertebrates

, based on a comparison of EECs and honey bee acute contact LD 50 toxicity data from a surrogate triazole

, and the mite data.

D IRECT E FFECTS TO T ERRESTRIAL P LANTS
Pac l obutrazol data (EC 25 and NOAEC) were not available for monocot seedling emergence and vegetative vigor, and dicot seedling emergence. Theref ore, data from other structurally

similar triazoles were used as surrogates for these data. In addition, r isk quotients were not
calculated for non

- listed monocots because the available data were non

- definitive. In lieu of a risk quotient, the EECs for each use were compared directly to the most sensitive toxicity
value ( Table 41 )

.116 T urf was the only use that considered s pray drif t as a potential route of exposure in addition
to runoff. A single ground application of 0.75 lb ai/A scenario was modeled and resulted in risk quotients that exceeded the LOC of 1 for listed semi

- aquatic monocots (2.22), non

- listed dry and semi

- aquatic d icots (2.50

– 17.50), and listed dry, semi

- aquatic, and spray drift dicots (3.75

– 78.75). The comparison of the most sensitive non

- definitive monocot EC 25 to EECs for dry, semi

- aquatic, and spray drift yielded no instances in which the EEC was greater than
the EC 25 ( Table 41 ).

Paclobutrazol soil injection/basal drench was modeled because of the potential for runoff from soil injection or drench application. A single injection/drench scenario of 1.9 lb ai/A at 3 inches in depth was modeled and resulted in risk quotients that exceeded the LOC of 1 for
listed semi

- aquatic monocots (1.78), non

- listed dry and semi

- aquatic dicots (1.41 to 14.07) and listed dry and semi

- aquatic dicots (6.33

– 63.33). For the comparison of the most
sensitive non

- definitive monocot EC 25 to EECs for dry and semi

- aquatic monocots, the semi

aquatic EEC was greater than the EC 25 ( Table 41 ). This indicates a potential risk to non

listed semi

- aquatic monocots from soil injection/basa l drench.

Paclobutrazol seed treatments were modeled for tomato (0.00040 lb ai/A), cucurbit (0. 00029 lb ai/A), pepper (0. 00079 lb ai/A) , broccoli (0.000096 lb ai/A), cauliflower (0.000064 lb ai/A), and cabbage (0.00012 lb ai/A) . Seed treatments occur wit hin the greenhouse and seedlings are assumed to be transplanted into outdoor fields when they are about 7 weeks old. For the terrestrial plant model, it is assumed that the entire application of paclobutrazol to the seed coat ends up in the soil rather th an the plant. Thus, paclobutrazol in runoff could be a concern. Each seed treatment application rate was modeled with an incorporation depth of 3 inches. None of the risk quotients that were produced exceeded the LOC of 1. None of the compari s ons betwe en the most sensitive non

- definitive EC 25 for monocots and the corresponding EECs for dry and semi

- aquatic monocots yielded EECs that were greater than
the EC 25 ( Table 41 ).

The model for paclobutrazol spray on potted ornamentals considered ru noff, but not spray drift as a potential exposure pathway. Spray drift was not considered a potential exposure pathway because spray applications take place within greenhouse settings. Environmental exposure is expected to occur when treated potted plants are set or planted outside, usually in a commercial setting. A single spray application of 0.26 lb ai/A was modeled and resulted in risk quotients that exceeded the LOC of 1 for non

- listed semi

- aquatic dicots (5.78) and listed dry and semi

- aquatic dicots (2.60

– 26. 00). The comparison between the most sensitive non

definitive monocot EC 25 and the EECs for dry and semi

- aquatic monocots did not yield EECs that were greater than the EC 25 ( Table 4 1 ).117 Paclobutrazol drench on potted ornamentals was modeled with a single application of 6.1 lb
ai/A. Drenches take place within greenhouses and environmental exposure occurs when plants are stored or planted outdoors. Risk quotients exceeded the LOC of 1 for listed dry
and semi

- aquatic monocots (1.72

– 17.18), non

- listed dry and semi

- aquatic dicots (13.56

– 135.56), and listed dry and semi

- aquatic dicots (61.00

– 610.00). The comparison between
the most sensitive non

- definitive monocot EC 25 and the EECs for dry and semi

- aquatic monocots yielded EECs that were greater than the EC 25 in both instances ( Table 4 1 ). These results indicate that paclobutrazol drenches to ornamental potted plants may pose risks to

non

- listed dry and semi

- aquatic monocots.

Table 4 1

. Comparison of EECs to the most sensitive non

- listed monocot toxicity v alue

Application Rate (Crop) “Dry” EEC (lb ai/A) EC 25 > 0.097 1
lb ai/A “Semi

- aquatic” EEC (lb ai/A) EC 25 > 0.097 1
lb ai/A “Spray drift” EEC (lb ai/A) EC 25 > 0.097 1
lb ai/A
1 ground spray application at 0.75 lb ai/A (turf) 0.011 EEC < 0.097 0.0605 EEC < 0.097 0.0055 EEC < 0.097

1 soil injection/drench at 1.9 lb ai/A 0.0127 EEC < 0.097 0.127 EEC > 0.097 N/A N/A

1 spray application at 0.26 lb ai/A (potted ornamentals) 0.0052 EEC< 0.097 0.052 EEC < 0.097 N/A N/A

1 drench application at 6.1 lb ai/A (potted ornamentals) 0.122 EEC > 0.097 1.22 EEC > 0.097 N/A N/A

1 seed treatment (pepper) 0.0000053 EEC < 0.097 0.000053 EEC < 0.097 N/A N/A

1 This value was used from metconazol e because toxicity data were not available for paclobutrazol.

Some uncertainty is introduced into the RQ analysis because surrogate data were used for many of the toxicity endpoints. Alternatively, the toxicity value from the most sensitive
chemical could be used instead of basing the toxicity value on the 5 th percentile value. For this approach, most of the toxicity values are slightly higher than those predicted by the 5 th
percentile (Table 42 ) . In two instances (veg vigor and seed emergence monoc ot EC 25 ), only

non

- definitive data were available and the most sensitive of these were used in the risk assessment anyway. For veg vigor monocot NOAEC, the most sensitive actual value was a “less then” value, thus the 5 th percentile estimate may have offe red a less sensitive toxicity
value than real febuconazole NOAEC. Re

- running TerrPlant using the values (excluding the

non

- definitives) in the “most sensitive endpoint” column (Table 42 ), the risk quotients are lowered for all scenarios. However, only th e soil injection/basal drench for ornamental trees experiences a change in the overall risk conclusions. With the alternate approach, listed
semi

- aquatic monocots and non

- listed dry dicots, are no longer expected to be potentially at
direct risk from this application method. The overall risk conclusions for the other modeled scenarios do not change, supporting the premise that the 5 th percentile approach is a reasonably conservative method to fill in toxicity datagaps.118 Table 42. Comparison of 5 th percen tile data points and the most sensitive endpoint
available for triazoles Endpoint 1 5 th Percentile (lb ai/A) Most Sensitive Endpoint (lb ai/A) Veg vigor monocot EC 25 N/A >0.097 (metconazole) Veg vigor monocot NOAEC 0.059 <0.061 (febuconazole) Seed emerg dicot EC 25 0.009 0.015 (triticonazole) Seed emerg dicot NOAEC 0.002 0.004 (triticonazole) Seed emerg monocot EC 25 N/A >0.098 (metconazole) Seed emerg monocot NOAEC 0.071 0.098 (metconazole)

1 Vegetative vigor dicot endpoints were available for paclobutrazol N/A Only non

- definitive data were available and 5 th percentile could not be calculated. In lieu of this, the most sensitive non

- definitive value was used in the risk assessment.

All of the original scenarios assumed that 100 percent of th e paclobutrazol in runoff would be taken up by non

- target plants. This is a conservative assumption; less conservative scenarios of 75, 50, and 25 percent uptak e were also considered (Table 4 3 ). Seed treatments
were not considered because the risk quotie nts did not exceed the LOC even with the conservative assumption of 100 percent uptake.

Table 4 3

. Risk quotients for a lternative paclobutrazol uptake scenarios for terrestrial plant runoff using TerrPlant

100% 75% 50% 25% Dry Semi

aquatic Dry Semi

aquatic Dry Semi

aquatic Dry Semi

aquatic Profile 2SC on Turf

– 1 ground application at 0.75 lb ai/A

Monocot

listed 0.32 2.22* ** 0.16 1.58* ** 0.11 1.06* ** <0. 1 0.53

Dicot

non

- listed 2.50* ** 17.50* ** 1.24* ** 12.44* ** 0.83 8.33* ** 0.42 4.18* **

Dicot

listed 11.25* ** 78.75* ** 5.60* ** 56.00* ** 3.75* ** 37.50* ** 1.88* ** 18.80* **

Paclobutrazol 2SC Soil Injection/Basal Drench for Ornamental Trees

– 1 application at 3 inches deep at 1.9 lb ai/A

Monocot

listed 0.18 1.78* ** 0.13 1.34* ** <0.1 0.89 <0.1 0.45

Dicot

- non

listed 1.41* ** 14.07* ** 1.06* ** 10.56* ** 0.70 7.04* ** 0.35 3.52* **119 100% 75% 50% 25% Dry Semi

aquatic Dry Semi

aquatic Dry Semi

aquatic Dry Semi

aquatic

Dicot

- listed 6.33* ** 63.33* ** 4.75* ** 47.50* ** 3.17* ** 31.67* ** 1.58* ** 15.83* ** Bonzi II Spray for Potted Ornamentals for Transplant

– 1 application at 0.26 lb ai/A

Monocot

listed <0.1 0.73 <0.1 0.55 <0.1 0.37 <0.1 0.18

Dicot

- non

listed 0.58 5.78* ** 0.43 4.33* ** 0.29 2.89* ** 0.14 1.44* **

Dicot

- listed 2.60* ** 26.00* ** 1.95* ** 19.50* ** 1.30* ** 13.00* ** 0.65 6.50* ** Bonzi II Drench for Potted Ornamentals for Transplant

– 1 application at 6.1 lb ai/A

Monocot

listed 1.72* ** 17.18* ** 1.29* ** 12.89* ** 0.86 8.59* ** 0.43 4.30* **

Dicot

- non

listed 13.56* ** 135.6 * ** 10.2 * ** 101. 7* ** 6.78* ** 67.78* ** 3.39* ** 33.89* **

Dicot

- listed 61.00* ** 610. 0* ** 45.8 * ** 457.5 * ** 30.5* ** 305.0* ** 15.3 * ** 152.50* **

* ** Exceeds the LOC of 1.

Based on the alternative uptake scenarios, even when it is assumed that only 25 percent of the available paclobutrazol will be incorporated into a plant, risk quotients exceed the LOC
of 1 for all modeled uses. Paclobutrazol is a plant growth regulator, thus risk to non

- target plants is expected.

Summary of Risks from Direct Effects A summary of the potential for risks terrestrial plants is listed below:

• The potential for direct effects to listed and non

- listed terrestrial plants is unlikely
from the seed treatments.

• The potential for direct effects to listed and non

- listed terrestrial plants is likely for all other application scenarios (turf, potted ornamental drench, potted ornamental spr ay, soil injection/basal drench), even when reduced uptake scenarios are considered.120 D IRECT E FFECTS TO A QUATIC F ISH , I NVERTEBRATES , AND P LANTS Paclobutrazol exposure to aquatic environments was modeled for drenches to potted plants and turf applications. These application methods were considered the most likely to result in a complete exposure pathway to the aquatic environment. T he PRZM/EXAMS model explored a number of different timing and geographical location scenarios . In addition, the
drench scenari o explored a conservative and more liberal concentration of available paclobutrazol in the water column , based on leaching experiments . Paclobutrazol studies indicated a range of mobility in soil. Scenarios were modeled using a total toxic residues

appro ach (i.e., paclobutrazol plus its two major degradates

.

Freshwater Fish and Amphibians (Aquatic

- Phase ), and Estuarine

- M arine Fish
Acute Risk Freshwater fish and aquatic

- phase amphibian acute toxicity data were available. Risk quotients for these groups d id not exceed the LOCs for listed or non

- listed species. Paclobutrazol data were not available for acute toxicity to estuarine/marine fish; therefore, data from structurally

- similar triazoles were used as a surrogate. Applications to turf did not yield r isk quotient s that exceeded the LOCs but ornamental drenches at the higher application rate (2.5 lb ai/A) did

. As an alternative approach , the most sensitive surrogate toxicity value for structurally similar triazoles was used for RQ calculation rather th an the value generated from the 5 th percentile method. The most sensitive LC 50 was 1800 μg ai/L (fenbuconazole) compared with the 5 th percentile generated LC 50 of 1580 μg ai/L. Re

calculating RQs, with the fenbuconazole value, the RQs are lower, but the overall risk conclusions for each use does not change

The risk quotients are based on the assumption that 100 percent of the applied paclobutrazol
is available in the soi l (i.e., none of it was taken up by the plant to which it was applied).
This is a co nservative assumption and several less conservative scenarios that assumed 75,
50

, and 25 percent availability in th e soil were considered (Table 4 4 ).

Table 4 4

. Alternative paclobutrazol soil availability scenarios for acute toxicity to
estuarine/marine fish

Aquatic Exposure (model) Use Scenario (modeled rate) Environmental Column 100% 75% 50% 25%

Total Toxic Residue (Paclobutrazol plus CGA 149907 and NOA 457654 ) 3

Surface
Water ( Tier 2 PRZM/ EXAMS) Ornamentals: CA Ornamentals STD FL Ornamentals STD
MI Ornamentals STD NJ Ornamentals STD OR Ornamentals STD
TN Ornamentals STD (1 app. X 2.5 lb ai/A) Water < 0.0 1

- 0.01 0.09

- 0.21* 0.12

- 0.19 * 0.09

- 0.16* 0.03

- 0.07* 0.09

- 0.16 * < 0.0 0 1

- 0.008 0.07

- 0.16 * 0.09

- 0.14 * 0.07

- 0.12 * 0.02

- 0.05 * 0.07

- 0.12 * < 0.0 0 1

- 0.005 0.05

- 0.11 * 0.06

- 0.10 * 0. 0 5

- 0.08 * 0.02

- 0.04 0.05

- 0. 0 6 * < 0.0 0 1

- 0.003 0.02

- 0.05*
0.03

- 0.05*
0.02

- 0.04 0.008

- 0.02 0.02

- 0.04121 Aquatic Exposure (model) Use Scenario (modeled rate) Environmental Column 100% 75% 50% 25%

Ornamentals:

CA Ornamentals STD FL Ornamentals STD MI Ornamentals STD NJ Ornamentals STD OR Ornamentals STD
TN Ornamentals STD (1 app. X 0.56 lb ai/A) < 0.0 01

- 0. 0 0 2 0.02

- 0.05 *
0.03

- 0.04 0.02

- 0.04 0.008

- 0.01 0.02

- 0.04 < 0.0 01

- 0.0 02 0.02

- 0.04 0.02

- 0.03 0.02

- 0.03 0.006

- 0.008 0.015

- 0.03 < 0.0 01

- 0.0 01 0.01

- 0.03 0.02

- 0.02 0.01

- 0.02 0.004

- 0.0 0 5 0.1

- 0.02 < 0.0 1

- 0.0 01 0.005

- 0.01 0.008

- 0.01 0.005

- 0.01 0.002

- 0.003 0.005

- 0.01

Parent Paclobutrazol Only 4

FL Ornamentals STD (1 app. X 2.5 lb ai/A) Water 0.11* 0.08 * 0.06 * 0.03

1 The LC 50 used in the risk quotient calculation was based on the 5 th percentile as calculated from a distribution of data from cyproconazole, fenbuconazole, hexaconazole, metconazole, mycobutanil, and tebuconazole.

2 The NOAEC used in the risk quotient calculation was based on the 5 th percentile as calculated from a distribution of data from metconazole, tebuconazole, and triticonazole.

3 Multiple months were modeled; the range of RQs represents the highest and lowest EECs.

4 Exposure of parent only based on highest exposure scenarios (F L Ornamentals STD and PA Turf STD) identified from t otal toxic residue simulations.
*E xceeds acute list ed species LOC (0.05 )

The alternative soil availability scenarios indicate that less than 25% of the applied paclobutrazol would need to be available in the soil to lower the risk quotients below the
level of concern.

Chronic Risk Chronic freshwater fish data were available and used to represent aquatic

- phase amphibians in addition to fish. Risk quotients calculated from these data exceeded the LOC of 1 for almost every scenario that was tested. Likewise, risk quotients calculated for estuarine/marine fish exceeded the LOC for every situation. Paclobutrazol toxicity data were not available for chronic effects to estuarine/marine fish, thus the 5 th percentile method was used to estimate the chronic value from structurally similar triazoles. An alternative approach of using the most sensitive triazole value (NOAEC = 11μg ai/L metconazole)
versus the 5 th percentile value (NOAEC = 4 μg ai/L) w as expl ored. There were no changes to the overall risk conclusions, even though the RQs were slightly lowered.

The chronic freshwater and estuarine/marine fish risk quotients are based on the assumption that 100 percent of the applied paclobutrazol is av ailable in the soi l (i.e., none of it was taken up by the plant to which it was applied). This is a conservative assumption and several less conservative scenarios that assumed 75, 50 and 25 percent availability in the soil were considered (Tables 4 5 and 4 6 ).122 Table 4 5

. Risk quotients for a lternative paclobutrazol soil availability scenarios for chronic toxicity to freshwater fish

Aquatic Exposure (model) Use Scenario (modeled rate) Environment al Column 100% 75% 50% 25%

Total Toxic Residue (Paclobutrazol plus CGA 149907 and NOA 457654 ) 3

Surface
Water ( Tier 2 PRZM/ EXAMS) Ornamentals: CA Ornamentals STD FL Ornamentals STD MI Ornamentals STD NJ Ornamentals STD OR Ornamentals STD
TN Ornamentals STD (1 app. X 2.5 lb ai/A)

Water < 0. 1

- 0.26 2 .9

- 6.8* ** 4.0

- 6.1* ** 2.9

- 5.2* ** 1.1

- 2.1* ** 3.0

- 5.2 *** <0.1

- 0.20 2. 2

- 5.1* ** 3.0

- 4.6* ** 2.2

- 3.9* ** 0.83

- 1.6* ** 2.3

- 3.9 *** <0.1

- 0.13 1.5

- 3.4* ** 2.0

- 3.1* ** 1.5

- 2.6* ** 0.6

- 1.1* ** 1.5

- 2.6 *** < 0.0 1

- 0.07 0. 73

- 1.7* ** 1.0

- 1.5* ** 0.73

- 1.3* **
0.28

- 0.53 0.8

- 1.3 ***

Ornamentals: CA Ornamentals STD FL Ornamentals STD MI Ornamentals STD NJ Ornamentals STD OR Ornamentals STD
TN Ornamentals STD (1 app. X 0.56 lb ai/A) < 0. 1

- 0.1 0.65

- 1.5* ** 0.90

- 1.3* ** 0.65

- 1.2* **
0.24

- 0.47 0.7

- 1.2 *** < 0.0 1

- 0.08 0.49

- 1.1* ** 0.68

- 0.98 0.49

- 0.90 0.18

- 0.35 0.53

- 0.9 < 0.0 1

- .05 0.33

- 0.75 0.45

- 0.65 0.33

- 0.60 0.12

- 0.24 0.35

- 0.6 < 0.0 1

- 0.03 0.16

- 0.38 0.22

- 0.33 0.16

- 0.3 0.06

- 0.12 0.18

- 0.3

Turf: FL Turf STD PA Turf STD (3 app. [2 app. X 0.75 lb and 1 app. X 0.5 lb] ai/A) 0.43

- 0.80 0.71

- 1.4* ** 0.32

- 0.60 0.53

- 1.1* ** 0.22

- 0.40 0.36

- 0.70 0.11

- 0.20 0.18

- 0.35

Parent Paclobutrazol Only 4

FL Ornamentals STD (1 app. X 2.5 lb ai/A)

Water 3.8* ** 2.9* ** 1.9* ** 0.95

PA Turf STD (3 app. [2 app. X 0.75 and 1 app. X 0.5 lb] ai/A 1.0* ** 0.75 0.50 0.25

1 The LC 50 used in the risk quotient calculation was based on the 5 th percentile as calculated from a distribution of data from cyproconazole, fenbuconazole, hexaconazole, metconazole, mycobutanil, and tebuconazole.

2 The NOAEC used in the risk quotient calculation was based on the 5 th percentile as calculated from a distribution of data from metconazole, tebuconazole, and triticonazole.

3 Multiple months were modeled; the range of RQs rep resents the highest and lowest EECs.

4 Exposure of parent only based on highest exposure scenarios (FL Ornamentals STD and PA Turf STD) identified from t otal toxic residue simulations.

* ** E xceeds chronic LOC (1 )

The alternative soil availability scenarios for chronic effects to freshwater fish indicate that less than 25 percent of the applied paclobutrazol (i.e. 75 percent of the paclobutrazol was taken up into the plant to which it was applied), would need to be present in the soil to lower the risk quotients below the level of concern for potted ornamentals

. For turf, the RQs are below the LOC at 50% uptake.123 Table 4 6

. Risk quotients for alternative paclobutrazol soil availability scenarios for chronic toxicity to estuarine/marine fish

Aquatic Exposure (model) Use Scenario (modeled rate) Environment al Column 100% 75% 50% 25%

Total Toxic Residue (Paclobutrazol plus 149907 and NOA 457654 ) 3

Surface Water ( Tier

2 PRZM/ EXAMS) Ornamentals: CA Ornamentals STD
FL Ornamentals STD MI Ornamentals STD NJ Ornamentals STD OR Ornamentals STD
TN Ornamentals STD (1 app. X 2.5 lb ai/A)

Water < 0. 1

- 3.2 *** 35

- 83* ** 49

- 75* ** 36

- 64* ** 13

- 26* ** 36

- 64 *** <0.1

- 2.4 *** 26

- 62* ** 37

- 56* ** 27

- 48* ** 9.8

- 20* ** 27

- 48 *** < 0.0 1

- 1.6 *** 18

- 42* ** 25

- 38* ** 18

- 32* ** 6.5

- 13* ** 18

- 32 *** < 0.0 1

- 0.8 8.8

- 21* ** 12

- 19* ** 9.0

- 16* ** 3.3

- 6.5* ** 9

- 16 ***

Ornamentals: CA Ornamentals STD FL Ornamentals STD MI Ornamentals STD NJ Ornamentals STD OR Ornamentals STD
TN Ornamentals STD (1 app. X 0.56 lb ai/A) < 0. 1

- 0.7 8

- 18* ** 11

- 17* ** 8

- 14* ** 3

- 6* ** 8

- 14 *** <0.1

- 0.53 6.0

- 14* ** 8.3

- 13* ** 6.0

- 11* ** 2.3

- 4.5* ** 6.0

- 11 *** < 0. 1

- 0.35 4.0

- 9.0* ** 5.5

- 8.5* ** 4.0

- 7.0* ** 1.5

- 3.0* ** 4

- 7 *** <0.1

- 0.18 2.0

- 4.5* ** 2.8

- 4.3* ** 2.0

- 3.5* ** 0.75

- 1.5* ** 2.0

- 3.5 ***

Turf: FL Turf STD PA Turf STD (3 app. [2 app. X 0.75 lb and 1 app. X 0.5 lb] ai/A) 5

- 10* ** 9

- 17* ** 3.8

- 8.0* ** 6.8

- 13* ** 2.5

- 5.0* ** 4.5

- 8.5* ** 1.3

- 2.5* ** 2.3

- 4.3* **

Parent Paclobutrazol Only 4

FL Ornamentals STD (1 app. X 2.5 lb ai/A)

Water 46* ** 35* ** 23* ** 12* **

PA Turf STD (3 app. [2 app. X 0.75 and 1 app. X 0.5 lb] ai/A 13* ** 9.8* ** 6.5* ** 3.3* **

1 The LC 50 used in the risk quotient calculation was based on the 5 th percentile as calculated from a distribution of data from cyproconazole, fenbuconazole, hexaconazole, metconazole, mycobutanil, and tebuconazole.

2 The NOAEC used in the risk quotient calculation was based on the 5 th percentile as calculated from a distrib ution of data from metconazole, tebuconazole, and triticonazole.

3 Multiple months were modeled; the range of RQs represents the highest and lowest EECs.

4 Exposure of parent only based on highest exposure scenarios (FL Ornamentals STD and PA Turf STD) ident ified from

t otal toxic residue simulations.

* ** E xceeds chronic LOC (1 )

Even with the assumption that only 25 percent of the applied paclobutrazol is available in the soil (i.e. 75 percent was taken up by the plant), the risk quotients exceed the LOC of 1, indicating chronic risk to estuarine/marine fish.124 Freshwater and Estuarine

- Marine Invertebrates
Acute Risk Acute paclobutrazol toxicity data for freshwater invertebrates and mollusks were available. Risk quotients did not exceed the LOCs for freshwa ter mollusks; however, LOCs were
exceeded for all of the scenarios considered for freshwater invertebrates. The acute LOC of 0.5 was exceeded for 75 percent of the drench applications to potted ornamentals at the 2.5 l b
ai/A level. The acute listed LOC o f 0.05 was exceeded for the remaining po tted ornamental application, and turf scenarios. For estuarine/marine invertebrates, acute tox icity data for paclobutrazol were not available. Therefore, surrogate data from structurally

- similar
triazoles was used instead . This resulted in a 5 th percentile estimate that was equivalent to the most sensitive triazole endpoint (mycobutanil EC 50 = 240μg ai/L); thus, there was no
difference between the 5 th percentile approach and the most sensitive triazole endpoint

app roach . Risk quotients followed the same pattern as the freshwater invertebrates with the acute LOC (0.5) being exceeded for most potted ornamental applications at 2.5 lb ai/A and
all other uses exceedi ng the acute listed LOC (0.05 ). A probit slope respon se analysis indicated a 1 in 49.8 chance of mortality with exposure to paclobutrazol for both freshwater
and estuarine/marine invertebrates ; the highest risk quotient was the same for both groups.
These results indicate that there is acute risk to listed and non

- listed freshwater and estuarine/marine invertebrates, excluding freshwater mollusks.

Data for an aquatic tubificid worm ( Limnodrilus hoffmeisteri ) were available from an open literature study identified by ECOTOX (Liu et al. 1996). The study indi cated an acute 96

- hour LC 50 was 34.9 mg ai/L (34900 μ g ai/L). Compared with the Daphnia EC 50 that was used in the risk quotient calculations, the tubificid worm is much less sensitive. Using the highest p eak EEC of 333 ( Total Toxic Residue approach

– Florida Ornamentals at 2.5 lb ai/A), the risk quotient is 0.01, well below the LOCs.

In all scenarios, the assumption was made that 100 percent of the applied paclobutrazol is
available in the soi l (i.e., none of it was taken up by the plant t o which it was applied). This is a conservative assumption and several less conservative scenarios that assumed 75, 50 and 25 percent availability in the soil were considered for acute risks to freshwater and

estuar ine/marine invertebrates (Table 4 7 ).125 Table 47

. Risk quotients for alternative paclobutrazol soil availability scenarios for acute toxicity to freshwater and estuarine/marine invertebrates (RQs were the same for both groups, thus they are combined in one table)

Aquatic Exposure (model) Use Scenario (modeled rate) Environmental Column 100% 75% 50% 25%

Total Toxic Residue (Paclobutrazol plus CGA 149907 and NOA 457654 ) 3

Surface Water ( Tier

2 PRZM/ EXAMS) Ornamentals: CA Ornamentals STD FL Ornamentals STD MI Ornamentals STD NJ Ornamentals STD OR Ornamentals STD
TN Ornamentals STD (1 app. X 2.5 lb ai/A)

Water < 0.0 1

- 0.05 * 0.61

- 1.4** 0.83

- 1.3** 0.60

- 1.1** 0.22

- 0.43* 0.61

- 1.1 ** < 0.0 1

- 0.04 0.46

- 1.1** 0.62

- 0.98** 0.45

- 0.83** 0.17

- 0.32* 0.46

- 0.83 ** < 0.0 1

- 0.03 0.31

- 0.70** 0.42

- 0.65** 0.30

- 0.55** 0.11

- 0.22* 0.31

- 0.55 ** < 0.0 1

- 0.01 0.15

- 0.35* 0.21

- 0.33 * 0.15

- 0.28 * 0.06

- 0.11 * 0.02

- 0.28 *

Ornamentals: CA Ornamentals STD FL Ornamentals STD MI Ornamentals STD NJ Ornamentals STD OR Ornamentals STD
TN Ornamentals STD (1 app. X 0.56 lb ai/A) < 0.0 1

- 0.01 0.13

- 0.31* 0.18

- 0.28 * 0.13

- 0.24 * 0.05

- 0.10 * 0. 13

- 0.24 * < 0.0 1

- 0.01 0.10

- 0.23* 0.14

- 0.21* 0.10

- 0.18* 0.04

- 0.08* 0.1

- 0.2 * < 0.0 1

- 0.0 1 0.07

- 0.16* 0.09

- 0.14* 0.07

- 0.12* 0.03

- 0.05* 0.07

- 0.12 * < 0.0 1

- < 0.0 1 0.03

- 0.08* 0.05

- 0.07* 0.03

- 0.06*
0.01

- 0.03 0.3

- 0.06 *

Turf: FL Turf STD PA Turf STD (3 app. [2 app. X 0.75 lb and 1 app. X 0.5 lb] ai/A) 0.09

- 0.16* 0.15

- 0.28* 0.07

- 0.12* 0.11

- 0.21* 0.05

- 0.08* 0.08

- 0.14* 0.02

- 0.04 0.04

- 0.07*

Parent Paclobutrazol Only 4

FL Ornamentals STD (1 app. X 2.5 lb ai/A)

Water 0.78* * 0.59* * 0.39* 0.20*

PA Turf STD (3 app. [2 app. X 0.75 and 1 app. X 0.5 lb] ai/A 0.21* 0.16* 0.11* 0.05*

1 The LC 50 used in the risk quotient calculation was based on the 5 th percentile as calculated from a distribution of data from cyproconazole, fenbuconazole, hexaconazole, metconazole, mycobutanil, and tebuconazole.

2 The NOAEC used in the risk quotient calculation was based on the 5 th percentile as calculated from a distrib ution of data from metconazole, tebuconazole, and triticonazole.

3 Multiple months were modeled; the range of RQs represents the highest and lowest EECs.

4 Exposure of parent only based on highest exposure scenarios (FL Ornamentals STD and PA Turf STD) ident ified from

t otal toxic residue simulations.
*E xceeds the acute listed species LOC (0.05 )

* * Exceeds the acute non

- listed species LOC (0.5)

Even with the assumption that only 25 percent of the applied paclobutrazol is available in the soil (i.e. 75 percent was taken up by the plant), the majority of the risk quotients exceed the LOC of 1, indicating acute risk to freshwater and estuarine/marine invertebrates.126 Chronic Risk Paclobutrazol chronic toxicity data for freshwater invertebr ates were not available ; thus surrogate data from structurally similar triazoles were used instead

. This resulted in r isk

q uotient s that exceeded the LOC of 1 for all uses

. As an alternative, the most sensitive endpoint from the triazoles (febuconazole NOAEC = 13 μg ai/L) was considered instead of the NOAEC generated by the 5 th percentile approach. U sing the 13 μg ai/L value , RQs were lowered; however, the risk conclusions remained the same. This indicates that paclobutrazol applications to potted ornamentals and turf present chronic risks to freshwater invertebrates.

Paclobutrazol toxicity data were not available for est uarine/marine invertebrates; therefore, surrogate data from structurally

- similar triazoles was used instead. In this case, there was only one surrogate chemical available (tebuconazole), thus the most sensitive triazole NOAEC was used in the analysis by d efault. The risk quotients exceeded the LOC of 1 for the majority of the modeled scenarios. The exceptions included several scenarios in the 0.56 lb ai/A drench to ornamental potted plants; however, there were severa l scenarios within this
category that exceeded the LOC of 1. These results indicate that paclobutrazol applications to potted ornamental plants and turf present chronic risks to freshwater and estuarine/marine
invertebrates.

In all scenarios, the assumption was made that 100 percent of the applied paclobutrazol is
available in the soi l (i.e., none of it was taken up by the plant to which it was applied). This is a conservative assumption and several less conservative scenarios that assumed 75, 50 and 25 percent availability in the soil were considered for acute risks to freshwater and
estuarine /marine invertebrates (Tables 48 and 4 9 ).

Table 4 8

. Risk quotients for alternative paclobutrazol soil availability scenarios for
chronic toxicity to freshwater invertebrates

Aquatic Exposure (model) Use Scenario (modeled rate) Environmental Column 100% 75% 50% 25%

Total Toxic Residue (Paclobutrazol plus CGA 149907 and NOA 457654 ) 3

Surface Water ( Tier

2 PRZM/ EXAMS) Ornamentals: CA Ornamentals STD FL Ornamentals STD MI Ornamentals STD NJ Ornamentals STD OR Ornamentals STD
TN Ornamentals STD (1 app. X 2.5 lb ai/A) Water <0.1

- 1.4 *** 16

- 37* ** 22

- 33* ** 16

- 28* ** 5.8

- 11* ** 16

- 28 *** <0.1

- 1.1 ***
12

- 30* ** 17

- 25* ** 12

- 21* ** 4.4

- 8.3* ** 12

- 21 *** <0.1

- 0.7 8.0

- 19* ** 11

- 17* ** 8.0

- 14* ** 2.9

- 5.5* ** 8.0

- 14 *** <0.1

- 0.4 4.0

- 9.3* ** 5.5

- 8.3* ** 4.0

- 7.0* ** 1.5

- 2.8* ** 4.0

- 7.0 ***

Ornamentals: CA Ornamentals STD FL Ornamentals STD MI Ornamentals STD NJ Ornamentals STD OR Ornamentals STD <0.1

- 0.31 3.6

- 8.1* ** 4.9

- 7.3* ** 3.6

- 6.3* ** 1.3

- 2.6* ** <0.01

- 0.02 2.7

- 6.1* ** 3.7

- 5.5* ** 2.7

- 4.7 * ** 0.98

- 2.0* ** < 0.0 1

- 0.02 1.8

- 4.1* ** 2.5

- 3.7* ** 1.8

- 3.2* ** 0.65

- 1.3* ** 0.0

- 0.001 0.9

- 1.0* ** 1.2

- 1.8* ** 0.9

- 1.6* ** 0.33

- 0.65127 Aquatic Exposure (model) Use Scenario (modeled rate) Environmental Column 100% 75% 50% 25%

Ornamentals STD (1 app. X 0.56 lb ai/A) 3.6

- 6.3 *** 2.7

- 4.7 *** 1.8

- 3.2 *** 0.9

- 1.6 ***

Turf: FL Turf STD PA Turf STD (3 app. [2 app. X 0.75 lb and 1 app. X 0.5 lb] ai/A) 2.3

- 4.3* ** 3.9

- 7.6* ** 1.7

- 3.2* ** 2.9

- 5.7* ** 1.2

- 2.2* ** 2.0

- 3.8* ** 0.58

- 1.1* ** 0.98

- 1.9* **

Parent Paclobutrazol Only 4

FL Ornamentals STD (1 app. X 2.5 lb ai/A)

Water 20* ** 15* ** 10* ** 5* **

PA Turf STD (3 app. [2 app. X 0.75 and 1 app. X 0.5 lb] ai/A 5.7* ** 4.3* ** 2.9* ** 1.4* **

1 The LC 50 used in the risk quotient calculation was based on the 5 th percentile as calculated from a distribution of data from cyproconazole, fenbuconazole, hexaconazole, metconazole, mycobutanil, and tebuconazole.

2 The NOAEC used in the risk quotient calculation was based on the 5 th percentile as calculated from a distribution of data from metconazole, tebuconazole, and triticona zole.

3 Multiple months were modeled; the range of RQs represents the highest and lowest EECs.

4 Exposure of parent only based on highest exposure scenarios (FL Ornamentals STD and PA Turf STD) identified from

t otal toxic residue simulations.

* ** E xceeds the chronic LOC (1 )

Even with the assumption that only 25 percent of the applied paclobutrazol is available in the soil (i.e. 75 percent was taken up by the plant), the majority of the risk quotients exceed the LOC of 1, indicating chronic risk to freshwater invertebrates.

Table 4 9

. Risk quotients for alternative paclobutrazol soil availability scenarios for chronic toxicity to estuarine/marine invertebrates

Aquatic Exposure (model) Use Scenario (modeled rate) Environmental Column 100% 75% 50% 25%

Total Toxic Residue (Paclobutrazol plus CGA 149907 and NOA 457654 ) 3

Surface Water ( Tier

2 PRZM/ EXAMS) Ornamentals: CA Ornamentals STD FL Ornamentals STD MI Ornamentals STD NJ Ornamentals STD OR Ornamentals STD
TN Ornamentals STD (1 app. X 2.5 lb ai/A) Water <0.1

- 0.4 4.0

- 9.5* ** 5.6

- 8.6* ** 4.1

- 7.3* ** 1.5

- 2.9* ** 4.1

- 7.2 *** <0.1

- 0.3 3.0

- 7.1* ** 4.2

- 6.5* ** 3.1

- 5.5* ** 1.1

- 2.2* ** 3.1

- 5.5 *** <0.1

- 0.2 2.0

- 4.8* ** 2.8

- 4.3* ** 2.1

- 3.7* ** 0.75

- 1.5* ** 2.1

- 3.7 *** <0.1

- 0.1 1.0

- 2.4* ** 1.4

- 2.2* ** 1.0

- 1.8* ** 0.38

- 0.73 1.0

- 1.8 ***

Ornamentals: CA Ornamentals STD FL Ornamentals STD MI Ornamentals STD NJ Ornamentals STD OR Ornamentals STD < 0.0 1

- 0.01 0.91

- 2.1* ** 1.3

- 1.9* ** 0.91

- 1.6* ** 0.34

- 0.66 < 0.0 1

- .0 1 0.68

- 1.6* ** 0.98

- 1.4* **
0.68

- 1.2* ** 0.26

- 0.50 < 0.0 1

- 0.0 1 0.46

- 1.1* ** 0.65

- 0.95 0.46

- 0.80 0.17

- 0.33 < 0.0 1

- <0 .0 1 0.22

- 0.53 0.33

- 0.48 0.22

- 0.40 0.09

- 0.17128 Aquatic Exposure (model) Use Scenario (modeled rate) Environmental Column 100% 75% 50% 25%

TN Ornamentals STD (1 app. X 0.56 lb ai/A) 0.9

- 1.6 *** 0.7

- 1.2 *** 0.5

- 0.8 0.2

- 0.4

Turf: FL Turf STD PA Turf STD (3 app. [2 app. X 0.75 lb and 1 app. X 0.5 lb] ai/A) 0.60

- 1.1* ** 1.0

- 2.0* ** 0.45

- 0.83 0.75

- 1.5* ** 0.30

- 0.55 0.5

- 1.0* ** 0.15

- 0.28 0.25

- 0.50

Parent Paclobutrazol Only 4

FL Ornamentals STD (1 app. X 2.5 lb ai/A)

Water 5.3* ** 4.0* ** 2.7* ** 1.3* **

PA Turf STD (3 app. [2 app. X 0.75 and 1 app. X 0.5 lb] ai/A 1.5* ** 1.1* ** 0.75 0.38

1 The LC 50 used in the risk quotient calculation was based on the 5 th percentile as calculated from a distribution of data from cyproconazole, fenbuconazole, hexaconazole, metconazole, mycobutanil, and tebuconazole.

2 The NOAEC used in the risk quotient calculation was based on the 5 th percentile as calculated from a distribution of data from metconazole, tebuconazole, and triticonazole.

3 Multiple months were modeled; the range of RQs rep resents the highest and lowest EECs.

4 Exposure of parent only based on highest exposure scenarios (FL Ornamentals STD and PA Turf STD) identified from

t otal toxic residue simulations.

* ** E x ceeds the acute listed LOC (1 )

Even with the assumption that only 25 percent of the applied paclobutrazol is available in the soil (i.e. 75 percent was taken up by the plant), the potted ornamentals RQs do not fall below the level of concern. However, the turf concern is eliminated wit h a 25 percent soil availability.

Aquatic Plants

– Vascular and Non

- vascular Paclobutrazol toxicity data were available for aquatic non

- vascular plants. A limited set of

non

- definitive data were available for aquatic vascular pl ants; thus the 5 th perce ntile was used as an endpoint from structurally

- similar triazoles. None of the risk quotients for aquatic non

vascular plants exceeded the LOC; however, all of the risk quotients for aquatic vascular plants exceeded the acute LOC of 0.5. To verify that t he 5 th percentile approach for generating an endpoint was not too conservative, the most sensitive EC 50 (22 μg ai/L

– metconazole) was used to calculate RQs as well. The resulting RQs were lower; however it did not change the risk conclusion for any of th e uses. T he assumption was made that 100 percent of the applied paclobutrazol is available in the soi l (i.e., none of it was taken up by the plant to which it was applied). This is a conservative assumption and several less
conservative scenarios that as sumed 75, 50 and 25 percent availability in the soil were considered for risks to aq uatic vascular plants (Table 50 ).129 Table 50

. Risk quotients for alternative paclobutrazol soil availability scenarios for toxicity to aquatic vascular plants

Aquatic Exposure (model) Use Scenario (modeled rate) Environmental Column 100% 75% 50% 25%

Total Toxic Residue (Paclobutrazol plus CGA 149907 and NOA 457654 ) 3

Surface
Water ( Tier 2 PRZM/ EXAMS) Ornamentals: CA Ornamentals STD FL Ornamentals STD MI Ornamentals STD NJ Ornamentals STD OR Ornamentals STD
TN Ornamentals STD (1 app. X 2.5 lb ai/A)

Water <0.1

- 1.6 *** 18

- 42* ** 25

- 38* ** 18

- 32* ** 6.5

- 13* ** 18

- 32 *** <0.1

- 1.2 ***
14

- 32* ** 19

- 29* ** 14

- 24* ** 4.9

- 9.8* ** 13.7

- 24 *** <0.1

- 0.8 9.0

- 21* ** 13

- 19* ** 9.0

- 16* ** 3.3

- 7.5* ** 9.0

- 16 *** <0.1

- 0.4 4.5

- 11* ** 6.3

- 9.5* ** 4.5

- 8.0* ** 1.6

- 3.3* ** 4.5

- 8.0 ***

Ornamentals: CA Ornamentals STD FL Ornamentals STD MI Ornamentals STD NJ Ornamentals STD OR Ornamentals STD
TN Ornamentals STD (1 app. X 0.56 lb ai/A) <0.1

- 0.4 4.0

- 9.3* ** 5.5

- 8.4* ** 4.0

- 7.1* ** 1.5

- 2.9* ** 4.0

- 7.1 *** <0.1

- 0.3 3.0

- 7.0* ** 4.1

- 6.3* ** 3.0

- 5.3* ** 1.1

- 2.2* ** 3.0

- 5.3 *** <0.1

- 0.2 2.0

- 4.7* ** 2.8

- 4.2* ** 2.0

- 3.6* ** 0.75

- 1.5* ** 2.0

- 3.6 *** <0.1

- 0.1 1.0

- 2.3* ** 1.4

- 2.1* ** 1.0

- 1.8* ** 0.38

- 0.73 1.0

- 1.8 ***

Turf: FL Turf STD PA Turf STD (3 app. [2 app. X 0.75 lb and 1 app. X 0.5 lb] ai/A) 2.7

- 4.9* ** 4.4

- 8.5* ** 2.0

- 3.7* ** 3.3

- 6.4* ** 1.4

- 2.5* ** 2.2

- 4.3* ** 0.68

- 1.2* ** 1.1

- 2.1 ** *

Parent Paclobutrazol Only 4

FL Ornamentals STD (1 app. X 2.5 lb ai/A)

Water 23* ** 17* ** 12* ** 6.3* **

PA Turf STD (3 app. [2 app. X 0.75 and 1 app. X 0.5 lb] ai/A 6.4* ** 4.8* ** 3.2* ** 1.6* **

1 The LC 50 used in the risk quotient calculation was based on the 5 th percentile as calculated from a distribution of data from cyproconazole, fenbuconazole, hexaconazole, metconazole, mycobutanil, and tebuconazole.

2 The NOAEC used in the risk quotient calculation was based on the 5 th percentile as calculated from a distribution of data from metconazole, tebuconazole, and triticonazole.

3 Multiple months were modeled; the range of RQs represents the highest and lowest EECs.

4 Exposure of parent only based on highest exposure scenarios (F L Ornamentals STD and PA Turf STD) identified from t otal toxic residue simulations.

* ** E xceeds th e aquatic plant LOC (1 )

Even with the assumption that only 25 percent of the applied paclobutrazol is available in the soil (i.e. 75 percent was taken up by the terrestrial plant), the majority of the risk quotients exceed the LOC of 1, indicating chronic risk to aquatic vascular plants.

The ECOTOX literature search identified one study on aqua tic vascular plants (MRID
48637501 ) that examined the effects of p aclobutrazol on a dicot (Eurasian watermilfoil

– Myriophyllum spicatum L. ) and a monocot (hydrilla

– Hydrilla verticillata ). In particular, the130 study examined the duration of time necessary for Eurasian watermilfoil and hydrilla to recover from a single e xposure to paclobutrazol. Recover y was characterized by comparing the total stem length (i.e., length of main stem plus lateral stems) of controls to the treated groups. Exposures ranged from 0 to 14 days, depending on the treatment group. The study
fou nd that hydrilla recovered to a normal total stem length after 6

- weeks, regardless of the initial exposure duration. In contrast Eurasian milfoil did not reach normal total stem lengths by 6

- weeks, even when the paclobutrazol exposure period was limited t o a single day. Overall, this study indicates that the Eurasian watermilfoil was more sensitive to paclobutrazol exposures than hydrilla. If this study can be extrapolated more broadly, it may indicate that aquatic dicots are likely to be more sensitive to paclobutrazol than aquatic

monocots.

Summary of Risk from Direct Effects A summary of the potential for risks to aquatic organisms is listed below:

• There are no acute risks for freshwater fish, aquatic

- phase amphibians, and freshwater
mollusks.

• Estuarine/marine fish are not at acute risk from the turf use, but are potentially at risk from the potted ornamental drench application.

• There are potential chronic risks to freshwater fish and aquatic

- phase amphibians; however, if only 50 percent, rather than 100 percent, of the paclobutrazol application
remains in the so il, the potted ornamental use risk quotients fall below the LOC.

• There is potential risk for all application scenarios, including the reduced percentage of paclobutrazol in soil sce narios for: chronic estuarine/marine fish, acute freshwater invertebrates, acute estuarine/marine invertebrates, and chronic freshwater
invertebrates.

• There are potential chronic risks to estuarine/marine invertebrates , even when reduced percents of paclob utrazol in the soil are considered for the potted ornamentals use; the risk quotients for turf use fall below the LOC with a 25 percent soil availability assumption.

• There are potential risks to vascular aquatic plants, even when reduced percents of paclob utrazol in the soil are considered.

• There are no risks to non

- vascular plants from the application scenarios that were
considered.

Listed Species Effects Analysis The direct and indirect effects analysis for general taxa of listed species is summarized in
Table 51 , for paclobutrazol uses . The analysis is based on the direct and indirect effects concluded from the analysis of risk estimates.131 Table 51

. Summary of indirect and direct effects to listed species and preliminary e ffe cts determination for paclobutrazol u ses
Listed species

group (1) Direct Effect Assessment Endpoints Direct Effects Indirect Effects Effects Determination

Non

- vascular Aquatic Plant Species Primary productivity No Effect

– risk quotients below LOC. Direct effects to non

- listed and listed terrestrial plants may occur from paclobutrazol spray drift (turf application) or runoff from drench and soil injection applications. This could result in reduced growth of non

- target plants and modify the structural habitat near aquatic environments. This could affect non

- vascular plant habitat by changing the water temperature, dissolved oxygen levels, sedimentation

, etc. Therefore, indirect effects to aquatic non

- vascular plants from effects to terrestrial plants may occur

.

However, c urrently, there are n o listed no n

- vascular aquatic plant species

, therefore adverse effects to listed non

- vascular plants is not expected

. N o Effect

Vascular Aquatic Plant Species Primary productivity assessed from effects on main stem length, total stem length (main + laterals), and fresh weight May A ffect, Likely to Adversely Affect

risk quotients above the LOC (using surrogate data)

. Direct effects to non

- listed and listed terrestrial plants may occur from paclobutrazol spray drift (turf application) or runoff from drench and soil injection applicat ions. This could result in reduced growth of non

- target plants and modify the structural habitat near aquatic envir onments. This could affect vascular plant habitat by changing the water temperature, dissolved oxygen levels, sedimentation, etc. Therefor e, indirect effects to aquatic vascular plants from effects to terrestrial plants may occur.

May affect and likely affected based on direct effects and indirect effects from direct effects on terrestrial plants. M ay A ffect, Likely to Adversely Affect

Freshwater Fish and Amphibians Acute mortality N o E ffect

– risk quotients below LOC. Adverse direct effects may be expected to aquatic organisms (fish, invertebrates, vascular plants ) as potential food sources

.

Direct effects to non

- listed and listed terrestrial plants may occur from paclobutrazol spray drift (turf application) or runoff from drench and soil injection applications. This could result in reduced growth of non

- target plants and modify the structural habitat near aquatic environmen ts. This M ay Affect, Likely to Adversely Affect132 Listed species

group (1) Direct Effect Assessment Endpoints Direct Effects Indirect Effects Effects Determination

Chronic survival, growth and reproduction May Affect, Likely to Adversely Effect

risk quotients above LOC

. could affect freshwater fish and amphibian habitat by changing the water temperature, dissolved oxygen levels, sedimentation, etc. Therefore, indirect effects to freshwater fish and am phibian s from effects to terrestrial plants

may occur.

I f in direct effects to aquatic habitats from terrestrial plants occur, which then indirectly affect aquatic organism availability as a food source for other organisms, then freshwater fish and amphibians may be adversely affected by changes in prey populations.

Likely to adversely affect would be based on direct chronic effects to freshwater fish and amphibians as well as indirect effects from direct effects on aquatic organisms (fish, invertebrates plants), if the species is dependent on them as a food source and from adverse effects on terrestrial plants which may affect habitat and and/or aquatic prey populations
Freshwater Invertebrates Acute mortality May Affect, Likely to Adversely Affect

– risk quotients above LOC (except for freshwater mollusks)

. Adverse direct effects to vascular aquatic plants are expected and could affect food sources or habitat for freshwater invertebrates

.

Direct effects to non

- listed and listed terrestrial plants may occur from paclobutrazol spray drift (turf application) or runoff from drench and soil injection applications. This could result in reduced growth of non

- target plants and modify the structural habitat near aquatic environments. This could affect freshwater invertebrate habitat by changing the water temperature, dissolved oxygen levels, sedimentation, etc. Therefore, indirect effects to freshwater invertebrates from effects to terrestrial plants may occur.

If indirect effects to aquatic habitats from terrestrial plants occur, which then indirectly affect aquatic organism availability as a food source for other organis ms, then freshwater invertebrates may be adversely affected by changes in prey populations.

May affect and likely to adversely affect based on direct acute and chronic effects to freshwater invertebrates and indirect effects from direct effects on

terre strial plants which may affect habitat and and/or aquatic prey populations

. M ay Affect, Likely to Adversely Affect

Chronic survival and reproduction May Affect, Likely to Adversely Affect

– risk quotients above LOC.133 Listed species

group (1) Direct Effect Assessment Endpoints Direct Effects Indirect Effects Effects Determination

Estuarine/ Marine Fish Acute mortality May Affect, Likely to Adversely Affect

– risk quotients above LOC (based on surrogate data). Adverse direct effects are expected for aquatic vascular plants and invertebrates that may serve as a food source for the fish.

Direct effects t o non

- listed and listed terrestrial plants may occur from paclobutrazol spray drift (turf application) or runoff from drench and soil injection applications. This could result in reduced growth of non

- target plants and modify the structural habitat near a quatic environments. This could affect estuarine/marine fish habitat by changing the water temperature, dissolved oxygen levels, sedimentation, etc. Therefore, indirect effects to estuarine/marine fish from effects to terrestrial plants may occur.

If indirect effects to aquatic habitats from terrestrial plants occur, which then indirectly affect aquatic organism availability as a food source for other organisms, then estuarine/marine fish may be adversely affected by changes in prey populations.

M ay affect and likely to adversely affect based on direct effects to acute and chronic estuarine/marine fish and indirect effects from direct effects on terrestrial plants and aquatic organisms, which may affect habitat and and/or aquatic prey populations

. M ay Affect, Likely to Adversely Affect

A ssessment of chronic growth and survival May Affect, Likely to Adversely Affect

– risk quotients above LOC (based on surrogate data).

Estuarine/
M arine Invertebrates Acute mortality May Affect, Likely to Adversel y Affect

risk quotients above LOC (based on surrogate data) Adverse direct effects are expected for aquatic vascular plants that may serve as a food source or habitat to the estuarine/marine invertebrates.

Direct effects to non

- listed and listed terrestrial plants may occur from paclobutrazol spray drift (turf application) or runoff from drench and soil M ay Affect, Likely to Adversely Affect134 Listed species

group (1) Direct Effect Assessment Endpoints Direct Effects Indirect Effects Effects Determination

A ssessment of chronic growth and reproductive effects May Affect, Likely to Adversely Affect

– risk quotients above LOC (based on surrogate data). injection applications. This could result in reduced growth of non

- target plants and modify the structural habitat near aquatic environmen ts. This could affect estuarine/marine invertebrate habitat by changing the water temperature, dissolved oxygen levels, sedimentation, etc. Therefore, indirect effects to estuarine/marine invertebrates from effects to terrestrial plants may

occur.

If in direct effects to aquatic habitats from terrestrial plants occur, which then indirectly affect aquatic organism availability as a food source for other organisms, then estuarine/marine invertebrates may be adversely affected by changes in prey populations.

May affect and likely to adversely affect based on direct acute and chronic risks to estuarine/marine invertebrates and indirect effects from direct effects on terrestrial plants which may affect habitats and/or aquatic prey populations
Non

- target plants in terrestrial and semi

- aquatic

areas Primary productivity assessed from effects on biomass as measured using survival and dry weight ; incident data

. May Affect and Likely to Adversely Affect

– Evidence that direct foliar exposure or exposure to roots via runoff to paclobutrazol causes direct toxicity which may result in reduced biomass (based on surrogate and paclobutrazol

specific data). Potential adverse effects to terrestrial invertebrates . A s terrestrial invertebrates are foragers and/or pollinators for terrestrial plants, indirect effects to ter restrial plants may occur if a plant is dependent on a particular species. Also, there is the potential for adverse direct effects to birds and mammals which may be seed dispersers for terrestrial plants. Therefore

, indirect effects on terrestrial plants from paclobutrazol are likely to have adverse e ffects if a species is dependent on another species for pollination.

There are also potential adverse effects from habitat modification. Paclobutrazol modifies plants by promoting a more compact growth form. Any plant, animal, bird, or insect that depends on plants for shelter may be affected by a change in plant structure. May Affec t , Likely to Adversely Affect

Bi rds, Reptiles, and Land

- Phase Amphibians Acute mortality No Effect

– risk quotients below LOC. Potential for direct effect s to mammals and other birds, reptiles and amphibians, therefore, indirect effects could occur from a reduction in prey populations. M ay Affect, Likely to Adversely Affect135 Listed species

group (1) Direct Effect Assessment Endpoints Direct Effects Indirect Effects Effects Determination

Chronic reproduction May Affect

, Likely to Adversely Affect

– risk quotients above LOC. Direct effects to non

- listed and liste d terrestrial may occur from paclobutrazol spray drift and runoff exposure; therefore

, indirect effects could occur from an alteration in habitat in which a species relies on for forage, shelter, and/or reproduction needs.

If indirect effects to aquatic habitats from terrestrial plants occur, which then indirectly affect aquatic organism availability as a food source for other organisms, then birds, reptiles, and land

- phase amphibians may be adversely affected by changes in prey populations.

Likely to have a dverse indirect effects depending on the relationship with prey and predator populations, plants as food source and habitat reliance.
Mammals Acute mortality May Affect

, Likely to Adversely Affect

– risk quotients above LOC. Potential for direct effects to other mammals and birds, reptiles and amphibians, therefore, indirect effects could occur from a reduction in prey populations.

Direct effects to non

- listed and listed terrestrial may occur from paclobutrazol spray drift and runoff exposure; therefore, indirect effects could occur from an alteration in habitat in which a sp ecies relies on for forage, shelter, and/or reproduction needs.

If indirect effects to aquatic habitats from terrestrial plants occur, which then indirectly affect aquatic organism availability as a food source for other organisms, then mammals may be adv ersely affected by changes in prey populations.

Likely to have adverse indirect effects depending on the relationship with prey and predator populations, plants as food source and habitat reliance. M ay Affect, Likely to Adversely Affect

Chronic Reproduction May Affect, Likely

to Adversely Affect

– risk quotients above LOC.

Terrestrial
Insects Acute mortality based on

contact No Effect

– based on surrogate data. Direct effects to non

- listed and listed terrestrial plants may occur from paclobutrazol spray drift and runoff exposure ; therefore

, indirect effects could occur from an alteration in habitat in which a species relies on for forage, shelter, and/or reproduction needs.

Likely to have adverse indirect effects depending on the rela tionship with prey and predator populations, plants as food source and habitat reliance. M ay Affect, Likely to Adversely Affect136 A CTION A REA In the case of a nationwide r isk assessment conducted under registration r eview, the action area will encompass the entire U.S. and its territories. The purpose of defining the action
area as the entire U.S. and its territories is to ensure that the initial area of consideration encompasses all areas where the pesticide may be used now and in the future, including the potential for off

- site transport via spray drift and downstream dilution. Additionally, the concept of a nationwide action area takes into account the potential for direct and indirect effects and any potential mo dification to critical habitat based on ecological effect measures associated with reduction in survival, growth, and reproduction, as well as the full suite of
sub

- lethal effects available in the effects literature.

It is important to note that the nati onwide action area does not imply that direct and/or indirect effects and critical habitat modification are expected to or are likely to occur over the full extent of the action area, but rather to identify all listed species and critical habitat that

may potentially be affected by the action. The Agency will use more rigorous analysis including consideration of available land cover data, toxicity data, and exposure information to determine areas where individual listed species and designated critical habi tat may be affected or modified via endpoints associated with reduced survival, growth, or reproduction

.

E FFECTS A REA D ETERMINATION The potential for direct and/or indirect effects is possible to listed species from exposure to paclobutrazol

.

Direct Effects There are potential direct effects to the listed species for the following taxa:

• Birds, Reptiles, and Land

- phase Amphibians (based on chronic risk quotients exceeding the LOC)

• Mammals (based on acute and chronic risk quotients exceeding the LOC)

• Terrestrial Plants ( based on risk quotients exceeding the LOC)

• Estuarine/Marine Fish (based on acute and chronic risk quotients exceeding the LOC)

• Freshwater Fish (based on chronic risk quotients exceeding the LOC)

• Freshwa ter Invertebrates (based on acute and chronic risk quotients exceeding the LOC)

• Estuarine/Marine Invertebrates (based on acute and chronic risk quotients exceeding the LOC)

• Vascular Aquatic Plants (based on risk quotients exceeding the LOC)137 Indirect Eff ects As there are potential direct effects to birds

, reptiles , amphibians , mammals, terrestrial plants, estuarine/marine fish, freshwater fish, freshwater invertebrates, estuarine/marine invertebrates, and vascular aquatic plants, indirect effects could oc cur to other taxa.

• Indirect effects to listed fish, aquatic invertebrates, amphibian s , reptile s, and other terrestrial organisms ( e.g . birds, mammals and other invertebrates) that are dependent

on aquatic invertebrates and plants for food.

• Indirect effects to terrestrial plants for which terrestrial animals ( e.g

. birds and mammals) are needed for reproduction ( e.g . pollination, seed dispersal) as there may be a potential change in terrestrial animal communities/population s

.

• Indirect effect s to a listed species that is dependant to a bird, reptile, amphibian, mammal, fish, aquatic invertebrate, or aquatic vascular plant during some phase of
their life

- cycle.

• Indirect effects to list ed species that are dependent on a plant in terrestrial or s emi

aquatic areas during some phase of their life

- cycle for things such as food, shelter, reproductive habitats

.

The following table shows the potential taxa indirectly affected by direct effects ( Table 52 )

Table 52 . Organism groups that are potentially indirectly affected by direct effects to

other organisms

Taxon Directly Affected Taxon Indirectly Affected Reason for Indirect Effect

Birds , Reptiles, Amphibians Mammals, Plants, Reptiles, other Birds , F ish Change in prey population (food source) ; Reduction in potential pollinators/seed dispersers
Mammals Reptiles, Birds, Plants, Amphibians Change in prey population (food source) ; Reduction in potential pollinators/seed dispersers Aquatic Invertebrates F ish

, Reptiles , Amphibians, Plants, Mammals Change in prey population (food source)
Fish Reptiles, Fish, Amphibians, Mammals, Birds Change in prey population (food source)
Plants All taxa (birds, mammals, reptiles, amphibians, fish, aquatic and terrestrial invertebrates) Change in food so urces; change in habitats

Based on this screening

- level assessment, there are potential concerns for direct toxic effects
to listed and non

- listed mammals, terrestrial plants, freshwater invertebrates, estuarine/marine invertebrates, freshwater fish, estuarine/marine fish, vascular aquatic plants, birds, reptiles, and amphibians from the use of paclobutrazol on some o f its registered use sites. Listed species of all taxa may also be affected through indirect effects because of the potential for direct toxic effects on listed and non

- listed species. Potential direct toxic effects on these species may be associated with modification of primary constituent elements of138 designated critical habitats, where such designations have been made. However, a t this current stage of the Registration Review process, it is premature to make effects determinations for listed species until further refinements are conducted. To make effects determinations for individual species, useful refinements may include analyses of 1) more detailed, species

- specific ecological and biological data; 2) more detailed and accurate information on pac lobutrazol use patterns and application rates; and 3) sub

- county level spatial proximity data for the co

- occurrence of potential effects areas and listed species and any designated critical habitat. Examples of such refinements are described below.

EFED is currently developing tools that are expected to further refine the assessment and are designed to support effects determinations for individual federally listed species and their designated critical habitats (where applicable). Scientific information o btained from the U.S. Fish & Wildlife Service (USFWS), the National Marine Fisheries Service (NMFS), and other reliable sources is being collated by EFED to address all currently listed species. The
information will be stored in an Office of Pesticide Pro grams Pesticide Registration Information SysteM (PRISM) knowledgebase. The listed species knowledgebase will consist of an information repository that houses biological and behavioral information relevant to individual species ( e.g. , habitat, diet, and li fe history, including specific temporal and spatial associations) and a document repository that contains supporting documents ( e.g ., USFWS recovery plans) and electronic information ( e.g ., GIS data files). For terrestrial taxa, the biological information relevant to risk quotient (RQ) calculations ( e.g ., diet and body weight) will be used to parameterize exposure estimates to derive species

- specific RQs using a method consistent with currently used methods in the T

- REX and T

- HERPS models.

Refinements m ay also include more detailed analyses of the registered uses and their use patterns that result in LOC exceedances for federally listed species in the screening

- level assessment. The analyses may include more information on where, when, and how paclobutr azol is used on all use sites

. Actual usage data (when available) and national land

cover datasets that indicate potential use sites [ e.g ., national land cover dataset (NLCD), crop data layer (CDL)] may be used to support a more refined analysis of where paclobutrazol is reasonably expected to be used. Similarly, refinements for the timing of applications and
how paclobutrazol is used may be based on the analysis of additional usage data, beyond what were available at the time of the screening

- level asses sment, and a more in

- depth exploration of agronomic practices.

In addition, a committee of the National Research Council (NRC) has been tasked with providing advice on ecological risk assessment tools and scientific approaches under ESA and FIFRA (Proje ct Identification Number DELS

- BEST

- 11

- 01). The committee has been asked to review the use of “best available data;” methods for evaluating sub

- lethal, indirect, and cumulative effects; the state of the science regarding assessment of mixtures and139 pesticid e inert ingredients; the development, application, and interpretation of results from predictive models; uncertainty factors; and what constitutes authoritative geospatial and temporal information for the assessment of individual species and habitat effect s. The Agency anticipates that this NRC report, tentatively expected in Spring 2013, will provide recommendations to ensure the scientific soundness and maximize the utility of risk assessment refinements for listed species.

The refinements based on indi vidual species data; additional, detailed usage information, when available; and further recommendations from the NRC report are expected to help to more accurately identify potential areas of effect and to better inform effects and habitat
determinations for listed species and any designated critical habitats. For example, if paclobutrazol is used when a particular species of concern is not present ( e.g ., it is migratory)
or is not co

- located in space, then risk of potential direct effects to the species may often be precluded. If LOCs are still exceeded for terrestrial plants , mammals, freshwater invertebrates, estu arine/marine invertebrates, freshwater fish , estuarine/marine fish, birds, reptiles, amphibians, and vascular aquatic plants after conducting the refined analyses, further analyses of the potential spatial and temporal co

- occurrence of listed species of concern (and any designated critical habitat) may be conducted. The extent of possible refinement in the analyses of spatial/temporal co

- occur rence will largely depend on the scale and quality of the available sub

- county level use site ( e.g ., NLCD, CDL) and species location
data

.

The Agency has refined the list of endangered and threatened species that may be affected by paclobutrazol uses base d on the best available information to date

. For the seed treatment uses (tomato, cucurbit, pepper, cabbage, cauliflower, broccoli) no direct or indirect effects are expected for listed species because these uses did not result in risk quotients that

exce eded the level of concern for any taxonomic group. The remaining uses (potted ornamental drench and spray, tree injection, soil injection/basal drench, turf) will need to be considered in more depth before effects calls are made. At this time, the Agency does not have a spatial data layer that captures turf, ornamental plants, and shade tree uses. Further, the biological, geographical, and use pattern information outlined above will be necessary to
refine the assessment. The following taxa will need to be co nsidered for each use (Table 53 ).140 Table 53. List of uses and taxa that need further consideration for direct effects calls
Taxa for further consideration

Potted ornamental drench Mammals, freshwater fish, estuarine/marine fish, freshwater invertebrates, estuarine/marine invertebrates, and vascular aquatic plants Potted ornamental spray Mammals Tree injection Mammals Soil injection/basal drench Birds, mammals, and terrestrial plants Turf and golf courses Mammals, terrestrial plants, freshwater fish, estuarine/marine fish, freshwater invertebrates, estuarine/marine invertebrates, and vascular aquatic plants141 

# Uncert ai nties

A description of assumptions, uncer tain ties, strengths, and limitations of the basic risk assessment performed is described in Chapter 6 of the Agency’s Overview Document (EPA, 2004) and include s those related to exposure for all taxa, those related to exposure for aquatic species, those relate d to exposure for terrestrial animals, those related to the effects assessment, and those associated with the acute LOC values. This Chapter discusses
additional un cer tain ties associated with refinements made to the basic risk assessment.



### Effects and Risk Assessment Uncer tain ties

E cotoxicity Data G aps Data for the following fate and eco

- toxicity studies were not available. The Final Work Plan for paclobutrazol requested seedling emergence and vegetati ve vigor data, but the studies
submitt ed in response to this request were found to be partially or completely invalid. Data
for the other studies were not r equested in the Final Work Plan

. Open literature searches were performed, but even with the addition of information from these sources, data still were not available for estuarine/marine fish (acute and chronic), freshwater invertebrates (chronic), estuarine/marine invertebrates (acute and chronic), seedling emergence (monocots and dicots), vegetative vigor (monocots), honey bees (acute co ntact), and vascular aquatic plants

. To address each gap, toxicity data was used from other triazoles that were similar in structure to paclobutrazol (Appendix F ) . Crystal Ball (2000 version 5.0) was used to create a fitted lognormal distribution running a Monte Carlo sampling scheme (10,000 trials). The 5 th
percentile of the data was calculated used in the risk assessment. Not every triazole had a complete set of data, so the chemicals and number of data points varied for each paclobutrazol data gap. This approach was chosen as it was thought to be conservative; however, it is possible that for any given endpoint, the triazole

- calculated paclobutrazol surrogate could have underestimated the risk. The following bulleted list contains a brief descriptio n of how each data gap was filled.

• Estuarine/Marine Fish (Acute) OPPTS 850.1075

. Definitive LC 50 data from six triazoles (cyproconazole, fenbuconazole, hexaconazole, metconazole, myclobutanil, tebuconazole, triticonazole) were available. A surrogate t oxicity value for paclobutrazol acute effects on estuarine/marine fish was developed based on the 5 th
percentile of the distribution of data.

• Estuarine/Marine Fish (Chronic) OPPTS 850.1400

. Definitive NOAEC/NOEC data from three triazoles (metconazole, tebuconazole, triticonazole) were available. A surrogate toxicity value for paclobutrazol chronic effects on estuarine/marine fish was developed based on the 5 th percentile of the distributio n of data.142 • Freshwater Invertebrates (Chronic) OPPTS 850.1300

. Definitive NOAEC/NOEC data from eight triazoles (cyproconazole, fenbuconazole, hexaconazole, metconazole, tebuconazole, triadimefon, triadimenol, triticonazole) were available. A surrogate

tox icity value for paclobutrazol chronic effects on freshwater invertebrates was developed based on the 5 th percentile of the distribution of data.

• Estuarine/Marine Invertebrates (Acute) OPPTS 850.1025 and OPPTS 850. 1035

. Definitive LC 50 /EC 50 data from seve n triazoles (cyproconazole, fenbuconazole, hexaconazole, metconazole, myclobutanil, tebuconazole, triticonazole) were available. A surrogate toxicity value for paclobutrazol acute effects on estuarine/marine invertebrates was developed based on the 5 th pe rcentile of the
distribution of data. In addition, acute toxicity data were available for a freshwater
mollusk.

• Estuarine/Marine Invertebrates (Chronic) OPPTS 850.1350

. Definitive NOAEC/NOEC data were available for only one triazole

– tebuconazole.
Cons equently, tebuconazole’s toxicity value was used as a surrogate for paclobutrazol
chronic effects on estuarine/marine invertebrates.

• Seedling Emergence (Monocots and Dicots) OPPTS 850.4225

. Definitive monocot NOAEC/NOEC data from four triazoles (cyprocon azole, metconazole, tebuconazole, triticonazole) were available. A surrogate toxicity value for paclobutrazol effects on monocot seedling emergence was developed based on the 5 th percentile of the
distribution of data. Definitive dicot EC 25 data from thr ee triazoles (cyproconazole, tebuconazole, triticonazole) and definitive dicot NOAEC/NOEC data from three triazoles (cyproconazole, metconazole, triticonazole) were available. Surrogate toxicity values for paclobutrazol effects on dicot seedling emergence were developed
based on the 5 th percentile of these two data distributions.

• Vegetative Vigor (Monocots) OPPTS 850.4250

. Definitive monocot NOAEC/NOEC data from three triazoles (cyproconazole, metconazole, tebuconazole) were available. A surrogate toxi city value for paclobutrazol effects on monocot vegetative vigor was developed based on the 5 th percentile of the distribution of data.

• Honey Bee (Acute Contact) OPPTS 850.3020

. Only non

- definitive LD 50 data were available for five triazoles (cyproconazole, fenbuconazole, metconazole, triadimefon, triticonazole). Consequently, t he most conservative value (tri ticonazole) was used in
the risk assessment

• Aquatic Vascular Plants (EC 50 ) OPPTS 850.4400

. Def initive EC 50 data were available for four triazoles (cyproconazole, metconazole, tebuconazole, triticonazole). A surrogate toxicity value for paclobutrazol effects on aquatic vascular plants was developed based on the 5 th percentile of the distribution of data.

• Aquatic Non

- Vascular Plants (EC 50 ) OPPTS 850.5400

. Toxicity data were not available for algal species. Open literature provided some toxicity information on paclobutrazol to green algae.143 • Passerine Birds (Acute) OPPTS 850.2100

. Data were not available, there fore, the acute oral toxicity of paclobutrazol to the mallard duck was used to evaluate risk.

Application Rates Many of the labels did not contain application information in pounds of active ingredient per acre. Tree injection, and soil injection/basal drench for ornamental trees provided application rates in grams of paclobutrazol per tree diameter. To evaluate exposure, assumptions (based on open literature) on the number of trees expected to be present in one acre as well as a

conser vative application rate in pounds of paclobutrazol per acre were made. These assumptions may be overestimating or underestimating exposure.

Greenhouse seed treatme nts for cucurbits, peppers, tomatoes , broccoli, cauliflower, and cabbage were stipulated in terms of micrograms of paclobutrazol per seed. To evaluate environmental exposure, the number of transplants per acre was derived from open literature sources. These assumptions may be overestimating or underestimating exposure.

Pre

- plant plug and line r soak labels did not provide specific use rates because the rate is influenced by varying soak times, the extent of rooting of each plant, the media moisture levels, the differ ing sensitivities of cultivars and species being treated, cultural practices, a nd environmental factors. Consequently, it was not possible to calculate a per

- acre application rate for these uses. It was assumed that the pre

- plant plug and liner soak application rate would not exceed the soil drench and/or bench spray for greenhouse or namental transplants (see below). This assumption may be overestimating or underestimating exposure.

Soil drench and bench spray application rates for greenhouse ornamental transplants were described in terms of parts per million per various size pot or bench area. To evaluate exposure, assumptions (based on open literature) were made to estimate the application rate per acre. These assumptions may be overestimating or underestimating exposure.

Rate of Paclobutrazol Uptake into Plants Spray, drench, and seed treatment applications assume that paclobutrazol will be absorbed into plants in one of two ways: directly through the leaves, stem, or seed coat; or taken up through the roots from the soil. Information was not available on the rate at which t his occurred. This posed a challenge for assessing risk to terrestrial and aquatic organisms. For example, in the tree drench scenario, the most conservative assumption for assessing risk to terrestrial animals is to assume 100 percent of the paclobutraz ol is taken up into the plant. Conversely, the most conservative assumption for assessing risks to aquatic organisms or other terrestrial plants (via runoff) is to assume that none of the paclobutrazol was taken up into the plant and is all still availabl e in the soil. This approach of using the most conservative assumptions for each organism group assessed essentially “double counts” the144 amount of paclobutrazol available to non

- target organisms and over

- estimates risk to some groups, if not all. However , without data to show how quickly paclobutrazol is absorbed into plants, it is difficult to choose realistic exposure scenarios. Consequently, the following plant

- to

- soil scenari os were considered: 100%:100%, 50%:50%, 25%:75%, and 75%:25%.

Distribution of Paclobutrazol in Plants The application methods for paclobutrazol rely on its translocation to internodes and dividing cells within the plant. In particular, drenches and tree/soil injections rely on the chemical being transported from the roots or tr unk of the tree to the leaves and stems. No information is available about whether all of the paclobutrazol concentrates in the leaves of the tree or if it remains equally distributed throughout the entire tree (roots, trunk, branches, fruit, leaves,

etc. ) or its translocation rate. In the risk assessment, the conservative assumption was made that paclobutrazol concentrates in the leaves of the plant and that it does so very quickly after being applied. This may have resulted in overly conservative estim ates of paclobutrazol exposure through the consumption of treated foliage.

Fate Data Gap s
T he following fate study is not available.

• OPPTS 850.1730

– Fish Bioconcentration Factor (BCF). To evaluate bioaccumulation, the model, KABAM, was employed. Results indicated that the potential for bioa ccumulation in aquatic food web is low.

In complete Life Histories of Listed Species Currently, an approved database of the complete life histories for each of the listed animals and plants is not available. These life histories would include information such as body size at each life stage, food sources, relationships with other taxa, habitat, and dietary and reproductive habits. As such, conservative assumptions were made concerning the potential
relationsh ips between species in that each specie s was assumed to have a relationship with
the other taxa. This is assumed to be an overestimation of the actual s pecies that have an species dependant relationship.

Locations of Listed Species In addition, the loc ations of listed species are not known in some cases beyond the county

level. If the location of a species was not known beyond county level, the species was assumed to occur anywhere within that county at any time. This assumption may lead to an

overest imation of co

- occurrence with paclobutrazol exposure and overestimation of the number of species potentially at risk.145 Information on Crop Locations, Actual Use Rates
, and Application Method s While the assessment was based on the maximum application rate s and methods stated on the registered labels, information on the use rates and application methods actually used in residential settings, golf courses, right

- of

- ways, athletic fields, and in fields were not
available to refine the risk characterization of paclobutrazol. In addition, sub

- county
information on where treated tomatoes, peppers, cucurbits , broccoli, cauliflower, and cabbage are grown would have been helpful when determining co

- occurrences with listed species.

Other Routes of Exposure
Screeni ng

- level risk assessments for applications of pesticides consider dietary exposure alone. Other routes of exposure, not considered in this assessment, are discussed below:

Incidental soil ingestion exposure

- This risk assessment does not consider incide ntal soil ingestion. Available data suggests that up to 15% of the diet can consist of incidentally ingested soil depending on the species and feeding strategy (Beyer et al. , 1994). This route of exposure may be important for applications of paclobutrazol as a soil drench or soil injection

.

Dermal Exposure

- The screening assessment does not consider dermal exposure, except as it is indirectly included in calculations of risk quotient ’s based on lethal doses per unit of pesticide treated area . Dermal exposure may occur through three potential sources: (1) direct application of spray to terrestrial wildlife in the treated area or within the drift footprint, (2) incidental contact with contaminated vegetation, or (3) contact w ith contaminated w ater or
soil. As foliar application and drenches are primary application route s on the registered
labels for paclobutrazol

, dermal contact with paclobutrazol to non

- target animals may occur.

Foliar Dissipation Half

- lif e An additional source of uncer tain t y is the foliar dissipation half

- life , which is useful for spray applications to foliage . No half

- life data were provided, thus a default of 35 days was used.
It is not known if this half

- life over or under

- estimates the true half

- life for paclobutrazol.

Species Sensitivity Although the screening

- level risk assessment relies on a selected toxicity endpoint from the most sensitive species tested, it does not necessarily mean that the selected toxicity endpoints
reflect the sensitivity of the most sensitive species existing in a given environment. The relative position of the most sensitive species tested in the distribution of all possible species is a function of the overall variability among species to a particular chemical. In the case of
list ed species, there is uncer tain ty regarding the relationship of the listed species’ sensitivity and the most sensitive species tested.146 The Agency is not limited to a base set of surrogate toxicity information in establishing risk
assessment conclusions. T he Agency also considers toxicity data on non

- standard test species when available

.

Endocrine Disrupt o r Screening Program (EDSP)

As required by FIFRA and FFDCA, EPA reviews numerous studies to assess potential adverse outcomes from exposure to chemicals. Collectively, these studies include acute, subchronic and chronic toxicity, including assessments of carcinogenicity, neurotoxicity, developmental, reproductive, and general or systemic toxicity. These studies include endpoints which may be susceptible t o endocrine influence, including effects on endocrine target organ histopathology, organ weights, estrus cyclicity, sexual maturation, fertility, pregnancy rates, reproductive loss, and sex ratios in offspring. For ecological hazard assessments, EPA evalu ates acute tests and chronic studies that assess growth, developmental and reproductive effects in different taxonomic groups. As part of its decision

, EPA reviewed these data and selected the most sensitive endpoints for relevant risk assessment
scenario s from the existing hazard database. However, as required by FFDCA section 408(p), paclobutrazol is subject to the endocrine screening part of the Endocrine Disruptor Screening Program (EDSP).

EPA has developed the EDSP to determine whether certain subs tances (including pesticide active and other ingredients) may have an effect in humans or wildlife similar to an effect produced by a “naturally occurring estrogen, or other such endocrine effects as the Administrator may designate.” The EDSP employs a tw o

- tiered approach to making the statutorily required determinations. Tier 1 consists of a battery of 11 screening assays to identify the potential of a chemical substance to interact with the estrogen, androgen, or thyroid (E, A, or T) hormonal systems. C hemicals that go through Tier 1 screening and are found to have the potential to interact with E, A, or T hormonal systems will proceed to the next stage of the EDSP where EPA will determine which, if any, of the Tier 2 tests are necessary based on the ava ilable data. Tier 2 testing is designed to identify any adverse
endocrine

- related effects caused by the substance, and establish a dose

- response relationship between the dose and the E, A, or T effect.

Under FFDCA section 408(p), the Agency must screen a ll pesticide chemicals. Between October 2009 and February 2010, EPA issued test orders/data call

- ins for the first group of 67 chemicals, which contains 58 pesticide active ingredients and 9 inert ingredients.

P aclobutrazol is not among the group of 58 p esticide active ingredients on the initial list to be screened under the EDSP. Accordingly, as part of registration review, EPA will issue future
EDSP orders/data call

- ins, requiring the submission of EDSP screening assays for147 paclobutrazol

. For further information on the status of the EDSP, the policies and procedures, the list of 67 chemicals, future lists, the test guidelines and the Tier 1 screening battery, please visit our website: http://www.epa.gov/endo/

.

Seasonal Carryover in Plants Paclobutrazol is a systemic and is known to persist for years in trees (based on label information and application intervals). It is unknown if for grasses and perennials, paclobutrazol levels are maintained across seasons and expressed in subsequent “gen erations” of foliage.

Greenhouse Discharges Paclobutrazol is applied as a liquid to potted plants within greenhouses, as well as a bulb and plug/liner soak. It is possible that paclobutrazol may be present in the runoff water. This is a
scenario that wa s not assessed and a point of uncertainty.

Spatial Analysis Data are not available for the percent of cropped areas and changes in crops (e.g., crop rotation or permanent shifts) over time. This remains an uncertainty, particularly for the proximity anal ysis for listed species.148 

# References

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Association. ANSI Z60. 1

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Beyer, W.N., E. Connor, and S. Gerould. 1994. Estimates of soil ingestion by wildlife. Journal of Wildlife Management , 58:375

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Chaney, W. R. 2 005. Growth retardants: a promising tool for managing urban trees. Purdue University Extension. FNR

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Fletcher, J., Nellessen, J.

, & Pfleeger, T. ( 1994 ) . Literature review and evaluation of the
EPA Food

- Ch ain (Kenaga) Nomogram, an Instrument for Estimating Pesticide Residues
on Plants. Environ. Tox. Chem

. , 13

, 1383

- 1391.

Hoerger, F., & Kenaga, E.E.. ( 1972 )

. Pesticide residues on plants: Correlation of representative data as a basis for estimation of their m agnitude in the environment

. In F. Coulston and F. Korte, eds

., Environmental Quality and Safety: Chemistry, Toxicology, and Technology

. Stuttgart, West Germany: Georg Thieme Publ, pp. 9

- 28.

Jenkins, J., D. Chojinacky, L. Heath, and R. Birdsey. 2003. Comprehensive database of
diameter

- based biomass regressions for North American tree species. General Technical Report NE

- 319, Forest Service, United States Department of Agriculture.

Nowak, D. J., M. H. Noble, S. M. Sisinni, and J. F. Dwyer. 2001. People and trees: assessing the U.S. urban forest resource. Journal of Forestry 99(3): 37

- 42.

Nowak, D. J., R. E. Hoehn III, D. D. Crane, J. C. Stevens, and C. L. Fisher. 2010a. Assessing ur ban forest effects and values, Chicago’s urban forest. United States Department of Agriculture, Forest Service , Northern Research Station Resource Bulletin

NRS

- 37.

Nowak, D. J., R. E. Hoehn III, D. E. Craine, J. C. Stevens, and J. T. Walton. 2006a

Asse ssing urban forest effects and values, Washington, D. C.’s urban forest. United States Department of Agriculture, Forest Service, Northern Research Station Resource Bulletin
NRS

- 1.

Nowak, D. J., R. E. Hoehn III, D. E. Crane, J. C. Stevens, and J. T. Walt on. 2007a. Assessing urban forest effects and values, New York City’s urban forest United States.149 Department of Agriculture, Forest Service, Northern Research Station Resource Bulletin
NRS

- 9.

Nowak, D. J., R. E. Hoehn III, D. E. Crane, J. C. Stevens, an d J. T. Walton. 2007b. Assessing urban forest effects and values, Philadelphia’s urban forest. United States Department of Agriculture, Forest Service, Northern Research Station Resource Bulletin
NRS

- 7.

Nowak, D. J., R. E. Hoehn III, D. E. Crane, J. C. Stevens, and J. T. Walton. 2007c. Assessing urban forest effects and values, San Francisco’s urban forest. United States Department of Agriculture, Forest Service, Northern Research Station Resource Bulletin

NRS

- 8.

Nowak, D. J., R. E. Heohn III, D. E. Craine, J. C. Stevens and J. T. Walton. 2007d. Assessing urban forest effects and values , Casper’s urban forest. United States Department of Agriculture, Forest Service, Northern Research Station Bulletin NRS

- 4.

Nowak, D. J., R. E. Hoehn III, D. E. Cr ane, J. C. Stevens, and V. Cotrone. 2010b. Assessing urban forest effects and values, Scranton’s urban forest. United States Department of Agriculture, Forest Service, Northern Research Station Resource Bulletin NRS

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Nowak, D. J., R. E., Hoehn III, D. E. Crane, J. C. Stevens, J. T. Walton, J. Bon, and G. Ina. 2006b. Assessing urban forest effects and values, Minneapolis’ urban forest. United States Department of Agriculture, Forest Service, Northern Research Station Resource
Bulletin NE

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Nowa k, D. J., R. E., Hoehn III, D. E. Crane, L. Weller, and A. Davila. 2011. Assessing urban forest effects and values, Lost Angeles’ urban forest. United States Department of Agriculture, Forest Service, Northern Research Station Resource Bulletin NRS

- 47.

Nowak, D. J., R. E. Hoehn III, J. Wang. A. Lee, V. Krishnamurthy, and G. Schwetz. 2009. Urban forest assessment in northern Delaware. United States Department of Agriculture, Forest Service, Northern Research Station Resource Bulletin NRS

- 33.

Nursery Supply, Inc. 2011. Nursery Supplies Catalog.

Oetting, R. D., and J. G. Latimer. 1995. Effects of soaps, oils, and plant growth regulators (PGRs) on Neoseiulus cucumeris (Oudemans) and PGRs on Orius insidiousus (Say). Journal of Agricultural Entomolog y . 12(2

- 3): 101

- 109.150 Sharma, D. and M. D. Awasthi. 2005. Uptake of soil applied paclobutrazol in mango ( Mangifera indica L.) and its persistence in fruit and soil. Chemosphere . 60: 164

- 169.

Sollins , P., D. E. Reichle, J. S. Olson. 1973. Organic matter budget and model for a southern Appalachian Lirodendron forest. Publication EDFB

- IBP

- 73

- 2. Oak Ridge, TN: Oak Ridge National Laboratory.

Tomlin, C. D. S. (ed.). 1997. The Pesticide Manual

– World Compendium, 11 th ed., Britis h Crop Protection Council, Surrey, England, P. 813.

Tomlin, C. D. S. [Ed.]. 2003. The Pesticide Manual, 13 th edition. British Crop Protection Council. 1344 pages.

United States Environmental Protection Agency (EPA). 1993. Wildlife Exposure Handbook, Volume I of II. Office of Research and Development, Washington, DC.

EPA/600/R

- 93/187a.

United States Environmental Protection Agency (EPA). 2004. Overview of the Ecological Risk Assessment Process in the Office of Pesticide Programs, U.S. Environmental Protection Age ncy, Endangered and Threatened Species Effects Determination. Office of Prevention, Pesticides and Toxic Substances, Office of Pesticide Programs, Washington, D.C., January 23, 2004.

United States Environmental Protection Agency (EPA). 2007. Paclobutr azol Final Work Plan for Registration Review

. Docket Number: EPA

- HQ

- OPP

- 2006

- 0109

- 0016

. www.regulations.gov

United States Environmental Protection Agency (EPA). 2011a. Per

- acre application rates for ornamental trees in urban forests, seed treatment a nd container

- grown ornamental uses of paclobutrazol. Memo to Environmental Fate and Effects Division and Pesticide

Re

- Evaluation Division, Office of Pesticide Programs, United States Environmental Protection Agency.

United States Environmental Protection Agency (EPA). 2011b. Acres planted per day and seeding rates of crops grown in the United States. Memo to P. Deschamp, Health Effects Division and D. Spatz, Environmental Fate and Effects Division, Office of Pesticide Programs, United States Environmen tal Protection Agency.

United States Environmental Protection Agency (EPA). 2012. Section 3

– ecological risk assessment of proposed new paclobutrazol (125601) seed treatments on broccoli,151 cauliflower, and cabbage. Environmental Fate and Effects Divisi on, Office of Pesticide Programs, United States Environmental Protection Agency.

U.S. Fish and Wildlife Service (USFWS) and National Marine Fisheries Service (NMFS). 1998. Endangered Species Consultation Handbook Procedures for Conducting
Consultation an d Conference Activities Under Section 7 of the Endangered Species Act.
Final Draft. March 1998.

Yeager, T. H. and D. L. Ingram. 2010. Layout and design considerations for a wholesale container nursery. CIR558, Environmental Horticulture Department, Fl orida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida.152 

## Appendix A

– Bibliography of MRIDs

Ecological Effects Studies
117478 Barber, J., G. Parkinson, G. Oliver, et al. 1982. PP333: acute oral, dermal, and intraperitoneal toxicity: report number CTL/P/748. Final report. (Unpublished study received October 28, 1982 under 10182

- 77; prepared by Imperial Chemical Industries PLC, England, submitted by ICI Americas, Inc., Wilmington, DE; CDL 248688

- B).

11 7484 Ross, D., N. Roberts, and C. Phillips. 1979. The acute oral toxicity (LD 50 ) of
PP333 to the mallard duck. ICI 252WL/781176 ; CTL/C/ 686. (Unpublished study received October 28, 1982 und 10182

- 77; prepared by Huntingdon Research Centre, England, su bmitted by ICI Americas, Inc., Wilmington, DE; CDL: 248689

- B).

117485 Roberts, N.

, C. Fairley, and R. Almond. 1982. The subacute dietary toxicity (LC 50 ) of PP333 to the mallard duck. ICI 417WL/82629; CTL/C/1173. Final report. (Unpublished study rec eived October 28, 1982 under 10182

- 77; prepared by Hun tin g don Research Centre, England, submitted by ICI Americas, Inc., Wilmington, DE; CDL:
248689

- C).

117486 Roberts, N., C. Fairley, and R. Almond. 1982. The subacute dietary toxicity (LC 50 )
of PP333 to the bobwhite quail. ICI 418/82661; CTL/?/1172. Final report. (Unpublished study received October 28, 1982 under 10182

- 77; prepared by Huntingdon Research Centre, England, submitted by ICI Americas, Inc., Wilmington, DE; CDL:
248689

- D).

117487 Hill, R., B. Young, and S. Cornish. 1978. Determination of the acute toxicity of PP333 to rainbow trout. BL/B/1935. (Unpublished study received October 28, 1982
under 10182

- 77, prepared by Imperial Chemical Industries Ltd., England, submitted by
ICI America s, Inc., Wilmington, DE; CDL: 248689

- E.

117488 Hill, R., and B. Maddock. 1982. PP333: determination of the acute toxicity to bluegill sunfish. BL/B/2209. Final report. (Unpublished study received October 28,
1982 under 10182

- 77; prepared by Imperia l Chemical Industries PLC, England, submitted by ICI Americas, Inc., Wilmington, DE; CDL: 248689

- F.

117489 Hamer, M., I. Hill, and S. Walker. 1982. PP333: toxicity of the technical material
and formulation GFU 029 to first instar Daphnia magna . Repor t series RJ 0282B. Final report. (Unpublished study received October 28, 1982 under 10182

- 77; prepared by Imperial Chemical Industries, Ltd., England, submitted by ICI Americas, Inc., Wilmington, DE; CDL: 248689

- G.153 40734303 Wickramaratne, G. A. 1987. Paclobutrazol: two generation reproduction study in rats including individual animal data. Unpublished study performed by ICI Central Toxicology Laboratory, Alderley Park, Macclesfield, Cheshire, UK. Study sponsored by ICI Americas Inc., Agricultural P roducts, Wilmington DE. Report submitted February 27, 1987.

47918901 Martin, J. A. 2009. Paclobutrazol

– early life

- stage toxicity test with fathead minnow ( Pimephales promelas ). Unpublished study performed by Springborn Smithers Laboratories, Wareha m, MA. Laboratory report number: 1781.6743. Study sponsored by Syngenta Crop Protection, Inc., Greensboro, NC. Study initiated July 16, 2009 and submitted November 23, 2009.

47918903 Martin, J. A. 2009. Paclobutrazol technical

– vegetative vigor test following U.S. EPA OPPTS Draft Guideline 850.4250 and OECD Draft Guideline 208, Part B. Unpublished study performed by Springborn Smithers Laboratories, Wareham, MA. Laboratory report number: 1781.6742. Study sponsored by Syngenta Crop Protection, Inc., Greensboro, NC. Study completed November 23, 2009.

48270601 Stafford, J. 2010. Paclobutrazol

- reproductive toxicity test with northern
b obwhite ( Colinus virginianus ) f ollowing FIFRA Guideline 71

- 4, OPPTS 850.2300 and OECD 206. Unpublished stud y performed by Springborn Smithers Laboratories (CRC), Snow Camp, NC. Laboratory Project No. 1781.4110. Study sponsored and submitted by Syngenta Crop Protection, Inc., Greensboro, NC. Study initiated September 29, 2009 and completed October 19, 2010.

48270602 Mitchell, L., K.H. Martin, J.B. Beavers, and M. Jaber. 2002. Paclobutrazole: A Reproduction Study with the Mallard. Unpublished study performed by Wildlife International, Ltd, Easton, Maryland. Laboratory Project No. 528

- 113. Study sponsored by Syngenta Crop Protection AG, Basel, Switzerland and submitted by Syngenta Crop Protection, Inc. Greensboro, NC. Study initiated November 26, 2001 and completed July 19, 2002.

48605401 Wang, K

- S., C

- Y Lu, and S

- H Chang. 2011. Evaluation of acute to xicity and teratogenic effects of plant growth regulators by Daphnia magna embryo assay. Journal of Hazardous Materials . 190: 520

- 528.

48605402 Liu, Z. T., Z. M. Kong, F. Zhou, and L. S. Wang. 1996. Bioconcentration and toxicity effect on lipid con tent of aquatic organisms. Bulletin of Environmental Contamination and Toxicology. 56: 135

- 142.154 4863750 1 Lembi, C.A., and M. D. Netherland. 1990. Bioassy of plant growth regulator activity on aquatic plants. Technical Report A

- 90

- 7, U.S. Army Waterways Experiment Station, Vicksburg, MS.



### Environmental Fate Studies

132698 Woods, T.; Leahey, J. (1983) PP333: Hydrolysis in Water at pH 4, 7 and 9: Report Series RJ 0316B. (Unpublished study received Nov 10, 1983 under 10182

- 82; pr epared by Imperial Chemical In dustries Ltd., Eng., submitted by ICI Americas, Inc., Wilmington, DE; CDL:251748

- B)

132699 Woods, T.; Leahey, J. (1983) PP333: Photolysis in Aqueous Solution: Report Series RJ 0317B. (Unpublished study received Nov 10, 1983 under 10182

- 82; prepared by Imperial Chemical Industries Ltd., Eng., submitted by ICI Americas, Inc., Wilmington, DE; CDL:2 51748

- C)

40685003 Harvey, B.; Hill, I. (1985) Paclobutrazol: Degradation in Aerobic and Flooded Soils: Laboratory Project ID: RJ0370B. Unpublished study prepared by ICI Plant Protection Division. 45 p.

47338504 Oliver, R.; Webb, J. (2005) Paclobutrazol : Rate of Degradation in Three Soils Under Laboratory Conditions: Final Report. Project Number: RJ3677B, 04JH025, T008689/07. Unpublished study prepared by Syngenta Jealotts Hill International. 77 p.

40685003 Harvey, B.; Hill, I. (1985) Paclobutrazol: De gradation in Aerobic and Flooded Soils: Laboratory Project ID: RJ0370B. Unpublished study prepared by ICI Plant Protection Division. 45 p.

40685005 Takacs, M.; White, B. (1986) Paclobutrazol: Adsorption and Desorption Equilibria in Soils: Laboratory Project ID: TMJ2377B. Un

- published study prepared by ICI Plant Protection Division. 26 p.

47338503 Shaw, D. (2002) Paclobutrazol: Adsorption and Desorption Properties in Four Soil: Final Report. Project Number: GZR/007/014132, GZR/007, T008688/07. Unpublished study prepared by Huntingdon Life Sciences, Ltd. 71 p. Relates to L0001128.

40685004 Mistry, R.; Hill, I. (1986) Paclobu trazol: Mobility of Paclobutra zol and Its Degradation Products in Soil Columns: Laboratory Project ID: RJ0495B. Unpublished study prepared by ICI Plant Protection Division. 64 p.

40685006 Mak, C.; Crook, S.; Atreya, N. (1987) Paclobutrazol: Field Dissipation following Subsu rface Applications in US Orchard Soils Up to 12 Months: Laboratory Project ID: RJ0574B. Unpublished study prepared by ICI Plant Protection Division. 74 p.

40685007 Hendley, P.; Davis, L.; Oliver, B. (1987) Paclobutrazol: Field Dissipation and Leaching fo llowing Subsurface Application in Orchard Soils

-- California Site

--155 Report of Field Data: Laboratory Project ID: TMU3304/B. Unpublished study prepared by ICI Biological Research Center. 19 p.

40685008 Hendley, P.; Davis, L.; Oliver, B. (1987) Paclobutrazol : Field Dissipation and Leaching following Subsurface Application in Orchard Soils

-- California Site

-- Second Follow

- up Report of Field Data: Laboratory Project ID: TMU3346/B. Unpublished study pre

- pared by ICI Biological Research Center. 20 p.

40685009 H endley, P.; Davis, L.; Oliver, B. (1987) Paclobutrazol: Field Dissipation and Leaching following Subsurface Application in Orchard Soils

-- Florida Site

-- Follow

- up Report of Field Data: Laboratory Project ID: TMU3303/B. Unpublished study prepared by ICI Biol ogical Research Center. 18 p.

40685010 Hendley, P.; Davis, L.; Oliver, B. (1987) Paclobutrazol: Field Dissipation and Leaching following Subsurface Application in Orchard Soils

-- Florida Site

-- Second Follow

- up Report of Field Data: Laboratory Project ID: TMU3345B. Unpublished study pre

- pared by ICI Biological Research Center. 19 p.

40685011 Hendley, P.; Davis, L.; Oliver, B. (1987) Paclobutrazol: Field Dissipation and Leaching following Subsurface Application in Orchard Soils

-- West Virginia Site

-

- Follow

- up Report of Field Data: Laboratory Project ID: TMU3305B. Unpublished study pre

- pared by ICI Biological Research Center. 18 p.

40685012 Hendley, P.; Davis, L.; Oliver, B. (1987) Paclobutrazol: Field Dissipation and Leaching following Subsurface Application in Orchard Soils

-- West Virginia Site

-

- Second Follow

- up Report of Field Data: Laborator y Project ID: TMU3347/B. Unpublished study prepared by ICI Biological Research Center. 19 p.

4733850 1 Adam, D. 2007. 14 C

- NOA457654: rate of degradation and time

- dependent sorption in four soils. Unpublished study performed by RCC Ltd., Itingen, Switzerland; sponsored by Syngenta Ltd., Berkshire, UK and submitted by Syngenta Crop Protection, Inc., Greensboro, NC. Report Number B26763. Task Number T011573

- 06. Experimental start date March 20, 2007 and completion date June 19, 2007 (p. 13). Fina l report issued July 13, 2007.

4733850 2 Lin, Y

. 2006

. NOA457654 (degradate of paclobutrazol): adsorption/desorption properties in four soils . Unpublished study performed , sponsored and submitted by Syngenta Crop Protection, Inc., Greensboro, NC

. Report Number T000759

- 06. Task Number T000759

- 06. Experimental start date May 15, 2006 and completion date August 11, 2006 (p. 5). Final report issued October 26, 2006.

4733850 3 Paclobutrazol adsorption and desorption properties in four soils . Unpubli shed study performed by Huntingdon Life Sciences Ltd., Cambridgeshire, England; sponsored by Syngenta, Bracknell, Berkshire, UK; and submitted by Syngenta Crop Protection, Inc., Greensboro, NC

. Report Number GZR 007/014132. Study Number GZR 007. Task Nu mber T008688

- 07. Experimental start date July 19, 2001 and completion date September 18, 2001 (p. 31). Final report issued January 2, 2002.156 4733850 4 Oliver, R.G. and J. Webb

. 2005

. Paclobutrazol rate of degradation in three soils under laboratory con ditions . Unpublished study performed by Syngenta Jealott’s Hill International, Berkshire, UK; sponsored and submitted by Syngenta Crop Protection, Inc., Greensboro, North Carolina

. Report Number RJ3677B. Study Number 04JH025. Task Number T008689

- 07. E xperimental start data January 11, 2005 and completion date July 12, 2005 (p. 21). Final report issued October 3, 2005.

47338505 Bewick, B.; Hendley, P.; Hoag, R.; et al. (1989) Paclobutrazol: The Fate of (Carbon

- 14)

- Paclobutrazol in Soil Under Field Conditions: Final Report. Project Number: RJ0710B, PP333AD02, T000229/08. Unpublished study prepared by ICI Agrochemicals. 212 p.157 

## A ppendix B

– Half

- Lif e Calculations of Total Toxic Residue s

Aerobic Soil Metabolism (MRID 40685003)

y =

- 0.0332x + 4.486 R2 = 0.9921

4.05 4.10 4.15 4.20 4.25 4.30 4.35 4.40 4.45 4.50 4.55

0 2 4 6 8 10 12 14LN (% of Applied)

Months Dissipation of paclobutrazol in 18 Acre sandy clay loam soil system (12 Months)

y =

- 0.0398x + 4.5257 R2 = 0.9726

4 4.1 4.2 4.3 4.4 4.5 4.6

0 2 4 6 8 10 12 14LN (% of Aplied)

Months Dissipation of paclobutrazol in 18 Acre sandy clay loam soil system (12 Months) DT 50 = 21 months

DT 50 = 17 months158 y =

- 0.012x + 4.5088 R2 = 0.8271

4.34 4.36 4.38 4.40 4.42 4.44 4.46 4.48 4.50 4.52 4.54

0 2 4 6 8 10 12 14LN (% of Applied)

Months (Post

- treatment) Dissipation of paclobutrazol in 18 Acre sandy clay loam soil system (12 Months)

y =

- 0.0195x + 4.5422 R2 = 0.9652

4.25

4.3 4.35

4.4 4.45

4.5 4.55

4.6

0 2 4 6 8 10 12LN (% of Applied)

Months (Post

- Treatment) Dissipation of paclobutrazol in 18 Acre sandy clay
loam soil system (12 Months 

## ) DT 50 = 58 months

DT 50 = 36 months159 y =

- 0.0018x + 4.4919 R2 = 0.4736

4.20 4.25 4.30 4.35 4.40 4.45 4.50 4.55 4.60

0 20 40 60 80 100 120 140LN (% of Applied)

Days (Post

- Treatment) Dissipation of paclobutrazol in 18 Acres sandy clay loam soil system (0

- 120 days)

y =

- 0.0124x + 4.5691 R2 = 0.9886

0.00 1.00 2.00 3.00 4.00 5.00

0 20 40 60 80 100LN (% of Applied)

Days Dissipation of paclobutrazol in Pappelacker sandy loam soil system (0

- 120 days)

Half

- Life = 56 d ays Half

- life = 385 days160 y =

- 0.0092x + 4.5731 R2 = 0.9755

0.00 1.00 2.00 3.00 4.00 5.00

0 20 40 60 80 100 120 140LN (% of Applied)

Days Half

- life = 75 Days161 

## A ppendix C

- Chemical Structures

Structures of parent and identification of degradates in environmental fate studies

Common Name/Code Chemical Name (IUPAC) Chemical Structure

Paclobutrazol (2 RS, 3 RS )

- 1

- (4

- Chlorophenyl)

- 4,4

- dimethyl

- 2

- (1 H

- 1,2,4

-

triazol

- 1

- yl)pentan

- 3

- ol.

CGA 149907 Ketone analog [CGA 132263,

R 079105] (2RS)

- 1

- (4

- Chlorophenyl)

- 4,4

- dimethyl

- 2

- (1H

- 1,2,4 triazol

- 1

- yl) pentan

- 3

- one.

Triazole [CGA 71019] [J7140/44/3, Compound V] 1H

- 1,2,4

- Triazole.

CGA 142856 [Triazole acid,

J7140/44/4, Compound VII] 1,2,4

- Triazol

- 1

- yl

- acetic acid.

NOA 457654

[Triazole hydroxy, J7140/45/2, Compound IX] 1H

- 1,2,4

- Triazol

- 3

- ol.

1 Bolded degra dates are major metabolites of N N N Cl O H

C H 3 C H 3

C H 3

N N

N Cl O

C H 3 C H 3

C H 3

N N

N

H

N N N

O H O

N H N N O H162 

## Appendix D

– KABAM Inputs and Outputs

Table 1. Chemical characteristics of Paclobutrazol.

Characteristic Value Comments/Guidance

Pesticide Name Paclobutrazol Required input

Log K OW 3.2 Required input Enter value from acceptable or supplemental study submitted by registrant or available in scientific literature.

K OW 1585 No input necessary. This value is calculated automatically from the Log K OW value entered above.

K OC (L/kg OC) 530 (Estimated 0.35xKow) Required input Input value used in PRZM/EXAMS to derive EECs. Follow input parameter guidance for deriving this parameter value (USEPA 2002).

Time to steady state (T S ; days) 3 No input necessary. This value is calculated automatically from the Log K OW value entered above.

Pore water EEC (μg/L) 338 Required input Enter value generated by PRZM/EXAMS benthic file. PRZM/EXAMS EEC represents the freely dissolved concentration of the pesticide in the pore water of the sediment. The appropriate averaging period of the EEC is dependent on the specific pesticide being mod eled and is based on the time it takes for the chemical to reach steady state. Select the EEC generated by PRZM/EXAMS which has an averaging period closest to the time to steady state calculated above. In cases where the time to steady state exceeds 365 d ays, the user should select the EEC representing the average of yearly averages. The peak EEC should not be used.

Water Column EEC (μg/L) 330 Required input Enter value generated by PRZM/EXAMS water column file. PRZM/EXAMS EEC represents the freely dissolved concentration of the pesticide in the water column. The appropriate averaging period of the EEC is dependent on the specific pesticide being modeled and is based on the time it takes for the chemical to reach steady state. The averaging period used for the water column EEC should be the same as the one selected for the pore water EEC (discussed above).163 Table 2. Input parameters for rate constants. "calculated" indicates that model will calculate
rate constant.

Trophic level k 1 (L/kg*d) k 2 (d - 1 ) k D (kg

- food/kg

org/d) k E (d - 1 ) k M * (d - 1 ) phytoplankton calculated calculated 0* 0* 0 zooplankton calculated calculated calculated calculated 0 benthic invertebrates calculated calculated calculated calculated 0
filter feeders calculated calculated calculated calculated 0
small fish calculated calculated calculated calculated 0
medium fish calculated calculated calculated calculated 0 large fish calculated calculated calculated calculated 0

* Default value is 0. k 1 and k 2 represent the uptake and elimination constants respectively, through respiration.

k D and k E represent the uptake and elimination constants, respectively, through diet.

k M represents the metabolism rate constant.

Table 3. Mammalian and avian toxicity data for Paclobutrazol. These are required inputs.

Animal Measure of effect (units) Value Species If selected species is

"other," enter body weight (in kg) here.

Avian LD 50 (mg/kg

- bw) mallard duck LC 50 (mg/kg

diet) Northern bobwhite quail
NOAEC (mg/kg

diet) 453 mallard duck

Mineau Scaling Factor 1.15 Default value for all species is 1.15 (for chemical specific values, see Mineau et al. 1996).

Mammalian LD 50 (mg/kg

- bw) 1336 laboratory rat LC 50 (mg/kg

diet) N/A other Chronic Endpoint 50 laboratory rat

units of chronic endpoint* mg/kg

- bw

*ppm = mg/kg

- diet

OUTPUTS164 Table 11. Estimated concentrations of Paclobutrazol in ecosystem components.

Ecosystem Component Total concentration

(μg/kg

- ww) Lipid normalized concentration

(μg/kg

- lipid) Contribution due to diet (μg/kg

- ww) Contribution due to respiration (μg/kg

- ww) Water (total)* 330 N/A N/A N/A Water (freely dissolved)* 330 N/A N/A N/A Sediment (pore water)* 338 N/A N/A N/A Sediment (in solid)** 7,166 N/A N/A N/A Phytoplankton 24,730 1236485 N/A 24,729.70 Zooplankton 18,176 605867 10.20 18,165.83
Benthic Invertebrates 19,833 661103 29.66 19,803.43
Filter Feeders 13,152 657592 19.27 13,132.58
Small Fish 25,493 637329 109.37 25,383.77
Medium Fish 25,575 639364 206.59 25,367.96 Large Fish 25,683 642076 369.14 25,313.92 * Units: μg/L; **Units: μg/kg

- dw

Table 12. Total BCF and BAF values of Paclobutrazol in aquatic trophic levels. 0 5000 10000 15000 20000 25000 30000

Zooplankton Benthic Invertebrates Filter Feeders Small Fish Medium Fish Large FishConcentration (μg/kg)

Trophic Level

Figure 1. Total pesticide concentration per trophic level Contribution due to respiration (μg/kg

- ww)

Contribution due to diet (μg/kg

- ww)165 Trophic Level Total BCF (μg/kg

ww)/(μg/L) Total BAF (μg/kg

ww)/(μg/L) Phytoplankton 77 75 Zooplankton 55 55
Benthic Invertebrates 60 60
Filter Feeders 40 40
Small Fish 77 77
Medium Fish 77 77 Large Fish 77 78

Table 13. Lipid

- normalized BCF, BAF, BMF and BSAF values of Paclobutrazol in aquatic trophic levels.

Trophic Level BCF (μg/kg

lipid)/(μg/L) BAF (μg/kg

lipid)/(μg/L) BMF (μg/kg

lipid)/(μg/kg

lipid) BSAF (μg/kg

lipid)/(μg/kg

OC) Phytoplankton 3849 3747 N/A 7 Zooplankton 1835 1836 0.49 3
Benthic Invertebrates 2001 2003 1.09 4
Filter Feeders 1990 1993 1.08 4
Small Fish 1924 1931 1.01 4
Medium Fish 1924 1937 0.98 4 Large Fish 1922 1946 1.00 4

Table 14. Calculation of EECs for mammals and birds consuming fish contaminated by Paclobutrazol.

Wildlife Species Biological Parameters EECs (pesticide intake) Body Weight

(kg) Dry Food Ingestion Rate (kg

- dry

food/kg

bw/day) Wet Food Ingestion Rate (kg

- wet

food/kg

bw/day) Drinking Water Intake (L/d) Dose Based (mg/kg

bw/d) Dietary Based (ppm)

Mammalian

fog/water shrew 0.02 0.140 0.585 0.003 11.655 19.83

rice rat/star

- nosed mole 0.1 0.107 0.484 0.011 9.475 19.50

small mink 0.5 0.079 0.293 0.048 7.537 25.57

large mink 1.8 0.062 0.229 0.168 5.892 25.57

small river otter 5.0 0.052 0.191 0.421 4.914 25.57

large river otter 15.0 0.042 0.157 1.133 4.060 25.68

Avian166 sandpipers 0.0 0.228 1.034 0.004 20.2852 19.55

cranes 6.7 0.030 0.136 0.211 2.6713 19.58

rails 0.1 0.147 0.577 0.010 13.1315 22.66

herons 2.9 0.040 0.157 0.120 3.5873 22.70

small osprey 1.3 0.054 0.199 0.069 5.1178 25.57

white pelican 7.5 0.029 0.107 0.228 2.7504 25.68

Table 15. Calculation of toxicity values for mammals and birds consuming fish contaminated by Paclobutrazol.

Wildlife Species Toxicity Values Acute Chronic
Dose Based (mg/kg

bw) Dietary Based (mg/kg

- diet) Dose Based (mg/kg

- bw) Dietary Based (mg/kg

- diet)

Mammalian fog/water shrew 2805.47 N/A 105.00 1000

rice rat/star

- nosed mole 1903.13 N/A 71.22 1000

small mink 1254.64 N/A 46.96 1000

large mink 887.17 N/A 33.20 1000

small river otter 687.20 N/A 25.72 1000

large river otter 522.16 N/A 19.54 1000

Avian sandpipers 0.00 0.00 N/A 453

cranes 0.00 0.00 N/A 453

rails 0.00 0.00 N/A 453

herons 0.00 0.00 N/A 453

small osprey 0.00 0.00 N/A 453

white pelican 0.00 0.00 N/A 453167 Table 16. Calculation of RQ values for mammals and birds consuming fish contaminated by Paclobutrazol.

Wildlife Species Acute Chronic Dose Based Dietary Based Dose Based Dietary Based

Mammalian fog/water shrew 0.004 N/A 0.111 0.020

rice rat/star

- nosed mole 0.005 N/A 0.133 0.019

small mink 0.006 N/A 0.161 0.026

large mink 0.007 N/A 0.177 0.026

small river otter 0.007 N/A 0.191 0.026

large river otter 0.008 N/A 0.208 0.026

Avian sandpipers #DIV/0! #DIV/0! N/A 0.043

cranes #DIV/0! #DIV/0! N/A 0.043

rails #DIV/0! #DIV/0! N/A 0.050

herons #DIV/0! #DIV/0! N/A 0.050

small osprey #DIV/0! #DIV/0! N/A 0.056

white pelican #DIV/0! #DIV/0! N/A 0.0571 68 

## Appendix E

– ECOTOX Literature Search

Papers That Were Accepted

Al

- Nimri, L. F. and Coolbaugh, R. C. (1990). Inhibition of Abscisic Acid Biosynthesis in Cercospora rosicola by Triarimol. J. Plant Growth Regul. 9: 221

- 225.

EcoReference No.: 94586 Chemical of Concern: ACM,CMZ,PBZ; Habitat : T; Effect Codes : BCM,POP;
Code : LITE EVAL CODED (ACM,CMZ,PBZ).
Not evaluated because units were not transferrable into lb ai/A.

Benjawan, C., Chutichudat, P., Boontiang, K., and Chanaboon, T. (2006). Effect of Chemical Paclobutrazol on Fruit Development, Quality and Fruit Yield of Kaew Mango (Mangifera indica L.) in Northeast Thailand. Pak. J. Biol. Sci. 9: 717

- 722.

EcoReference No.: 111578 Chemical of Concern: PBZ; Habitat : T; Effect Codes : GRO,PHY,POP; Code : LITE EVAL CODED (PBZ).
Not evaluated because units were not transferrable into lb ai/A.

Bigot, J. and Boucaud, J. (1998). Effects of Synthetic Plant Growth Retardants and Abscisic Acid on Root Functions of Brassica rapa Plants Exposed to Low Root

- Zone Temperature. New Phytol. 139: 255

- 265.

EcoRefe rence No.: 66797 Chemical of Concern: ASA,MFD,PBZ; Habitat : T; Effect Codes : PHY; Code : LITE EVAL CODED (ASA,MFD,PBZ).
Not evaluated because units were not transferrable into lb ai/A.

Chorbadjian, R. (2009). Phenotypic Variation in Host Quality of P ines for the European Pine Sawfly (Neodiprion sertifer). Ph.D. Thesis, The Ohio State University, OH 169 p. (UMI# 3345826).

EcoReference No.: 152510 Chemical of Concern: PBZ; Habitat : T; Effect Codes : BCM,GRO,PHY; Code : LITE EVAL CODED (PBZ).

Not evaluated because units were not transferrable into lb ai/A.

Dawson, I. A. and King, R. W. (1993). Effect of Environment and Applied Chemicals on the169 Flowering and Form of Geraldton Wax (Chamelaucium uncinatum Schauer). Sci.

Hortic. 54: 233

- 246.

EcoRefe rence No.: 151275 Chemical of Concern: BAD,CQTC,DMZ,EPH,MLH,PBZ; Habitat : T; Effect
Codes : GRO,PHY,REP; Code : LITE EVAL CODED (BAD,PBZ), NO ENDPOINT (CQTC,DMZ,EPH,MLH).
Not evaluated because units were not transferrable into lb ai/A.

Ding, F., Song, W. H., Guo, J., Gao, M. L., and Hu, W. X. (2009). Oxidative Stress and
Structure

- Activity Relationship in the Zebrafish (Danio rerio) Under Exposure to
Paclobutrazol. J. Environ. Sci. Health Part B: Pestic. Food Contam. Agric. Wastes

44: 44

- 50.

EcoRefer ence No.: 120224 Chemical of Concern: PBZ; Habitat : A; Effect Codes : BCM,MOR; Code : LITE EVAL CODED (PBZ). Evaluated, but classified as “invalid” because it was unclear if the purity of the material had been adjusted for in the reported results.

Dubois, V., Moritz, T., and Garcia

- Martinez, J. (2011). Comparison of the Role of Gibberellins and Ethylene in Response to Submergence of Two Lowland Rice Cultivars, Senia and Bomba. J. Plant Physiol. 168: 233

- 241.

EcoReference No.: 152434
Chemical of Co ncern: 1MCP,ETL,GIB,PBZ; Habitat : AT; Effect Codes : BCM,CEL,GRO; Code : LITE EVAL CODED (1MCP,ETL,GIB,PBZ), NO EFED CHEM (1MCP).
Not evaluated because units were not transferrable into lb ai/A.

Escalona, M., Lorenzo, J. C., Gonzalez, B., Daquinta, M. , Gonzalez, J. L., Desjardins, Y., and Borroto, C. G. (1999). Pineapple (Ananas comosus L. Merr) Micropropagation in Temporary Immersion Systems. Plant Cell Rep. 18: 743

- 748.

EcoReference No.: 108781 Chemical of Concern: BAD,GIB,PBZ; Habitat : T; Effec t Codes : REP; Code : LITE EVAL CODED (PBZ), NO MIXTURE (BAD,GIB).
Not evaluated because units were not transferrable into lb ai/A.

Fagerness, M. J. and Yelverton, F. H. (2001). Plant Growth Regulator and Mowing Height170 Effects on Seasonal Root Growth of Penncross Creeping Bentgrass. Crop Sci. 41:
1901

- 1905.

EcoReference No.: 111282 Chemical of Concern: PBZ,TXE; Habitat : T; Effect Codes : POP; Code : LITE EVAL CODED (PBZ,TXE).
Not evaluated because duration of measurement was not transferable to EPA risk

assessments.

Gandiaga, S. (2007). Effects of Hydrology and Applied Gibberellic Acid and Paclobutrazol on the Growth of the Invasive Exotic Lygodium microphyllum (Old World Climbing Fern). M.S. Thesis, Florida Atlantic University, FL 40 p. (UMI# 1443 672).

EcoReference No.: 152512 Chemical of Concern: GIB,PBZ; Habitat : T; Effect Codes : GRO,PHY,REP; Code : LITE EVAL CODED (GIB,PBZ).
Not evaluated because the units could not be converted into lb ai/A.

Gandiaga, S., Volin, J. C., Kruger, E. L., and Kitajima, K. (2009). Effects of Hydrology on the Growth and Physiology of an Invasive Exotic, Lygodium microphyllum (Old World Climbing Fern). Weed Res. 49: 283

- 290 Publlished from MS Thesis EcoRef
#152512.

EcoReference No.: 152582 Chemical of Concern: GIB,PBZ; Habitat : T; Effect Codes : GRO,PHY; Code : LITE EVAL CODED (GIB,PBZ).
Not evaluated because the units could not be convereted into lb ai/A.

Gocal, G. F. W., Sheldon, C. C., Gubler, F., Moritz, T., Bagnall, D. J., MacMilla n, C. P., Li, S. F., Parish, R. W., Dennis, E. S., Weigel, D., and King, R. W. (2001). GAMYB

Like Genes, Flowering, and Gibberellin Signaling in Arabidopsis. Plant Physiol.
127: 1682

- 1693.

EcoReference No.: 108777 Chemical of Concern: GIB,PBZ; Habitat : T; Effect Codes : BCM,CEL,GRO,REP;
Code : LITE EVAL CODED (GIB,PBZ).
Not evaluated because the units could not be converted into lb ai/A.

Guoping, Z. (1997). Gibberellic Acid3 Modifies Some Growth and Physiologic Effects of Paclobutrazol (PP333) on Whe at. J. Plant Growth Regul. 16: 21

- 25.171 EcoReference No.: 105433 Chemical of Concern: GIB,PBZ; Habitat : T; Effect Codes : BCM,GRO,POP; Code : LITE EVAL CODED (PBZ), NO MIXTURE (GIB).
Not evaluated because the units could not be converted in lb ai/A.

Hajihashemi, S., Kiarostami, K., Enteshari, S., and Saboora, A. (2006). The Effects of Salt Stress and Paclobutrazol on Some Physiological Parameters of Two Salt

- Tolerant and
Salt

- Sensitive Cultivars of Wheat. Pak. J. Biol. Sci. 9: 1370

- 1374.

EcoReferenc e No.: 111577 Chemical of Concern: Halides,NaCl,PBZ; Habitat : T; Effect Codes : BCM; Code : LITE EVAL CODED (Halides,NaCl,PBZ).
Not evaluated because the units could not be converted into lb ai/A.

Hamid, M. M. and Williams, R. R. (1997). Translocation of Paclobutrazol and Gibberellic Acid in Sturt's Desert Pea (Swainsona formosa). Plant Growth Regul. 23: 167

- 171.

EcoReference No.: 100708 Chemical of Concern: GIB,PBZ; Habitat : T; Effect Codes : GRO; Code : LITE EVAL CODED (GIB,PBZ).
Not evaluated because it was not the most sensitive plant.

Hutchinson, M. J., Krishnaraj, S., and Saxena, P. K. (1997). Inhibitory Effect of GA3 on the Development of Thidiazuron

- Induced Somatic Embryogenesis in Geranium (Pelargonium x hortorum Bailey) Hypocotyl Cultur es. Plant Cell Rep. 16: 435

- 438 .

EcoReference No.: 111020 Chemical of Concern: ACM,GIB,PBZ,TDZ; Habitat : T; Effect Codes : REP; Code : LITE EVAL CODED (ACM,GIB,PBZ), NO MIXTURE (TDZ).
Not evaluated because the units could not be converted into lb ai /A.

Isgrigg III, J. (1999). Ecological Adaptations of Annual Bluegrass to Plant Growth Regulators and Herbicides. Ph.D.Thesis, North Carolina State Univ, NC 162 p. (UMI #9960156).

EcoReference No.: 121125
Chemical of Concern: ATZ,BFL,CPZ,DQT,DTP,FPD,FRM ,GYP,MBZ,NONA,ODZ,OYZ,PBZ,PCZ,PDM, PRM,PZM,SFZ,SZ,TXE; Habitat : T; Effect Codes : BCM,GRO,PHY,POP; Code :172 LITE EVAL CODED (ATZ,BFL,DQT,FPD,FRM,GYP,MBZ,OYZ,PBZ,PDM,PRM,PZM,SFZ,SZ,TXE), NO EFED CHEM (CPZ,DTP,ODZ), NO MIXTURE (NONA,PCZ).
Not evaluated because it was a mixture.

Kumar, S., Kashyap, M., and Sharma, D. R. (2005). In Vitro Regeneration and Bulblet Growth from Lily Bulbscale Explants as Affected by Retardants, Sucrose and
Irradiance. Biol. Plant. (Praha) 49: 629

- 632.

EcoReference No.: 1100 06 Chemical of Concern: CQTC,DMZ,PBZ; Habitat : T; Effect Codes : GRO,REP;
Code : LITE EVAL CODED (CQTC,DMZ,PBZ).
Not evaluated because the units could not be converted into lb ai/A.

Lembi, C. A. and Netherland, M. D. (1990). Bioassay of Plant Growth R egulator Activity on Aquatic Plants. Technical Report A

- 90

- 7, U.S.Army Corp Eng.Waterways Exp.Stn., Vicksburg, MS 36 p. (NTIS/02971610_a).

EcoReference No.: 107916 Chemical of Concern: BSFM,FPD,PBZ; Habitat : A; Effect Codes : BCM,GRO,PHY; Code : LITE EVAL CODED (FPD,PBZ), NO EFED CHEM (BSFM). Study was evaluated and used in the risk assessment.

Manivannan, P., Abdul Jaleel, C., Kishorekumar, A., Sankar, B., Somasundaram, R., and Panneerselvam, R. (2008). Protection of Vigna unguiculata (L.) Walp. Pl ants from Salt Stress by Paclobutrazol. Colloids Surf. B Biointerfaces 61: 315

- 318.

EcoReference No.: 152518 Chemical of Concern: Halides,NaCl,PBZ; Habitat : T; Effect Codes : BCM,GRO;
Code : LITE EVAL CODED (Halides,NaCl,PBZ).
Not evaluated because the endpoint was not useful.

Marshall, J. G. and Dumbroff, E. B. (1999). Turgor Regulation via Cell Wall Adjustment in White Spruce. Plant Physiol. 119: 313

- 319.

EcoReference No.: 108741 Chemical of Concern: PBZ; Habitat : T; Effect Codes : BCM,PHY; C ode : LITE EVAL CODED (PBZ).
Not evaluated because the units could not be converted into lb ai/A.173 Nagano, S., Mori, G., and Oda, M. (2010). Promotion of Seed Germination in Musa velutina Wendl. & Drude by Scarification and GA3. J. Hortic. Sci. Biotechno l. 85: 267

- 270.

EcoReference No.: 152445 Chemical of Concern: GIB,PBZ; Habitat : T; Effect Codes : BCM,REP; Code : LITE EVAL CODED (GIB,PBZ). Not evaluated because the endpoint was not useful.

Netherland, M. D. and Lembi, C. A. (1992). Gibberellin Syn thesis Inhibitor Effects on Submersed Aquatic Weed Species. Weed Sci. 40: 29

- 36.

EcoReference No.: 9710 Chemical of Concern: FPD,PBZ; Habitat : A; Effect Codes : BCM,GRO,PHY;
Code : LITE EVAL CODED (FPD,PBZ).
Evaluated and used in the risk assessment.

Ochoa, J., Franco, J. A., Banon, S., and Fernandez, J. A. (2009). Distribution in Plant, Substrate and Leachate of Paclobutrazol Following Application to Containerized Nerium oleander L. Seedlings. Spanish J.Agric.Res. 7: 621

- 628.

EcoReference No.: 152 345 Chemical of Concern: PBZ; Habitat : T; Effect Codes : ACC,GRO; Code : LITE EVAL CODED (PBZ).
Not evaluated because the units could not be converted into lb ai/A.

Oetting, R. D. and Latimer, J. G. (1995). Effects of Soaps, Oils, and Plant Growth Regulators (PGRs) on Neoseiulus cucumeris (Oudemans) and PGRs on Orius insidiosus (Say). J. Agric. Entomol. 12: 101

- 109.

EcoReference No.: 81074 Chemical of Concern: ACM,A LSV,CQTC,DMZ,MOIL,MSO,PBZ; Habitat : T;
Effect Codes : MOR; Code : LITE EVAL CODED (ACM,ALSV,CQTC,DMZ,MOIL,MSO,PBZ), TARGET (ALSV,MOIL).
Evaluated and used in the risk assessment.

Ozmen, A. D., Ozdemir, F., and Turkan, I. (2003). Effects of Paclobutraz ol on Response of Two Barley Cultivars to Salt Stress. Biol. Plant. (Praha) 46: 263

- 268.

EcoReference No.: 105666174 Chemical of Concern: Halides,NaCl,PBZ; Habitat : T; Effect Codes : BCM,GRO;
Code : LITE EVAL CODED (Halides,NaCl,PBZ).
Not evaluated beca use the units could not be converted in lb ai/A.

Rohwer, C. (2008). Jasmonate

- Induced Defense Against Tetranychus urticae Koch. in Greenhouse Crops. Ph.D. Thesis, University of Minnesota, St. Paul, MN 189 p. (UMI# 3321929).

EcoReference No.: 152515 Chemical of Concern: DMZ,PBZ; Habitat : T; Effect Codes : BCM,BEH,GRO,MOR,POP; Code : LITE EVAL CODED (DMZ,PBZ). Evaluated and found to be invalid because of an aphid infestation during the experiment.

Seymour, M. (1996). Response of Narrow

- Leafed Lupi n (Lupinus angustifolius L.) to Foliar Application of Growth Regulators in Western Australia. Aust. J. Exp. Agric. 36:
473

- 478.

EcoReference No.: 70689 Chemical of Concern: BAD,CPR,CZE,DU,IZT,MBZ,MQC,NAA,PBZ,SZ; Habitat : T; Effect Codes : GRO,POP,REP ; Code : LITE EVAL CODED (BAD,DU,MBZ,PBZ,SZ), NO EFED CHEM (CPR,CZE,IZT,MQC,NAA). Not evaluated because the duration of the experiment was not comparable to OPP guideline studies.

Steffens, B., Wang, J., and Sauter, M. (2006). Interactions Between Ethyle ne, Gibberellin and Abscisic Acid Regulate Emergence and Growth Rate of Adventitious Roots in Deepwater Rice. Planta 223: 604

- 612.

EcoReference No.: 94888 Chemical of Concern: ASA,EPH,GIB,PBZ; Habitat : A; Effect Codes : GRO; Code : LITE EVAL CODED (AS A,EPH,GIB,PBZ).
Not evaluated because the units could not be converted into lb ai/A.

Tanimoto, T. (2007). Modification of Sex Expression in Sagittaria latifolia by the Application of Gibberellic Acid and Paclobutrazol. J. Jpn. Soc. Hortic. Sci. 76: 47

- 5 3.

EcoReference No.: 96445 Chemical of Concern: GIB,PBZ; Habitat : A; Effect Codes : REP; Code : LITE175 EVAL CODED (GIB,PBZ). Not evaluated because the duration unit of the experiment was not convertible into days.

Tari, I. and Nagy, M. (1996). Abscisic Acid and Ethrel Abolish the Inhibition of
Adventitious Root Formation of Paclobutrazol

- Treated Bean Primary Leaf Cuttings. Biol. Plant. (Praha) 38: 369

- 375.

EcoReference No.: 100154 Chemical of Concern: ASAM,CoCl,EPH,PBZ; Habitat : T; Effect Codes : BCM,GRO; Code : LITE EVAL CODED (ASAM,EPH,PBZ), NO EFED CHEM (CoCl).
Not evaluated because the units could not be converted into lb ai/A.

Vergieva, T. (1998). Single Day Treatment

- a Feasible Tool in Revealing not Dependent on Maternal Toxicity Terat ogenic Potential. Adv. Exp. Med. Biol. 444: 191

- 199.

EcoReference No.: 105597 Chemical of Concern: BMY,PBZ; Habitat : T; Effect Codes : CEL,GRO,PHY,REP;
Code : LITE EVAL CODED (BMY,PBZ). Not evaluated because it was not the most sensitive endpoint.

W ang, K. S., Lu, C. Y., and Chang, S. H. (2011). Evaluation of Acute Toxicity and Teratogenic Effects of Plant Growth Regulators by Daphnia magna Embryo Assay.
J. Hazard. Mater. IN PRESS: 9 p.

EcoReference No.: 152403 Chemical of Concern: CTK,EPH,GIB,MNP Na,PBZ; Habitat : A; Effect Codes : GRO,MOR; Code : LITE EVAL CODED (CTK,EPH,GIB,MNPNa,PBZ), NO EFED CHEM (CTK).
Evaluated and used in the risk assessment.

Weiland, J. E., Nelson, A. H., and Hudler, G. W. (2009). Effects of Mefenoxam, Phosphonate, and Paclobutrazol on In Vitro Characteristics of Phytophthora cactorum and P. citricola and on Canker Size of European Beech. Plant Dis. 93: 741

- 746.

EcoReference No.: 152439 Chemical of Concern: MFX,PBZ,RMLX; Habitat : T; Effect Codes : POP,REP;
Code : LITE EVAL CODED (MFX,PBZ,RMLX), TARGET (MFX,RMLX).
Not evaluated because the units could not be converted into lb ai/A.176 Wiesman, Z. and Lavee, S. (1995). Enhanc ement of IBA Stimulatory Effect on Rooting of Olive Cultivar Stem Cuttings. Sci. Hortic. 62: 189

- 198.

EcoReference No.: 114107 Chemical of Concern: INDBA,PBZ; Habitat : T; Effect Codes : GRO; Code : LITE EVAL CODED (INDBA,PBZ).
Not evaluated because t he units coult not be converted into lb ai/A.



### Papers That Were Not Accepted Accepted for EcoTox but not OPP

Alabadi, D., Gil, J., Blazquez, M. A., and Garcia

- Martinez, J. L. (2004). Gibberellins Repress Photomorphogenesis in Darkness. Plant Physiol. 134: 1050

- 1057.

EcoReference No.: 120141 Chemical of Concern: BLD,GIB,PBZ; Habitat : T; Effect Codes : CEL,GRO; Code : NO EFED CHEM (BLD), NO ENDPOINT (GIB,PBZ), TARGET (PBZ) . Ascough, G. D., Erwin, J., and Van Staden, J. (2007). In Vitro Propagation of Four Watsonia Species. Plant Cell, Tissue Organ Cult. 88: 135

- 145.

EcoReference No.: 115053 Chemical of Concern: 24D,24DXY,BAD,IAA,INDBA,NAA,PBZ; Habitat : T;
Effect Codes : GRO,MOR; Code : NO EFED CHEM (NAA), NO ENDPOINT (PBZ), OK (24D,24DXY,BAD,IA A,INDBA).

Baker, E. A., Hayes, A. L., and Butler, R. C. (1992). Physicochemical Properties of Agrochemicals: Their Effects on Foliar Penetration. Pestic. Sci. 34: 167

- 182 .

EcoReference No.: 70752
Chemical of Concern: ACP,ATZ,BTN,CQTC,DFP,FXP,GYP,MLH,M LX,NYP,PBZ,SZ,TDF,TDM;
Habitat : T; Effect Codes : ACC; Code : NO CONTROL (ACP,ATZ,CQTC,GYP,MLH,MLX,PBZ,SZ,TDF), NO EFED CHEM (BTN,DFP,FXP,NYP,TDM), NO ENDPOINT (ACP,ATZ,CQTC,GYP,MLH,MLX,PBZ,SZ,TDF).

Cohen, R., Pivonia, S., Shtienberg, D., Edelstein, M. , Raz, D., Gerstl, Z., and Katan, J. (1999). Efficacy of Fluazinam in Suppression of Monosporascus cannonballus, the Causal Agent of Sudden Wilt of Melons. Plant Dis. 83: 1137

- 1141.177 EcoReference No.: 108337
Chemical of Concern: BMY,CBD,DCNA,FNZ,FRM,FTF,H CZ,IPD,MYC,Maneb,OTQ,OXC,PBZ,PNB,TC M,TCMTB,TDM,THM,TPM; Habitat : T; Effect Codes : POP; Code : NO EFED CHEM (HCZ,OTQ,OXC,TCM,TDM,TPM), NO ENDPOINT (BMY,CBD,DCNA,FRM,FTF,IPD,MYC,Maneb,PBZ,PNB,TCMTB,THM), NO MIXTURE (THM), TARGET (BMY,CBD,DCNA,FNZ,FRM,FTF ,IPD,MYC,Maneb,PNB,TCMTB,THM).

Costa, G., Spinelli, F., Sabatini, E., and Rademacher, W. (2004). Incidence of Scab (Venturia inaequalis) in Apple as Affected by Different Plant Growth Retardants. Acta Hortic. (Wagening.) 653: 133

- 137.

EcoReference No.: 99893 Chemical of Concern: CQTC,PBZ,PHDCa,TXE; Habitat : T; Effect Codes : GRO,POP; Code : NO EFED CHEM (PHDCa), NO ENDPOINT (CQTC,PBZ,TXE). Frear, D. S., Swanson, H. R., and Tanaka, F. S. (1993). Metabolism of Flumetsulam (DE

498) in Wheat, Corn, and Barley. Pestic. Biochem. Physiol. 45: 178

- 192.

EcoReference No.: 106957 Chemical of Concern: FTS,PBZ,PPB; Habitat : T; Effect Codes : ACC; Co de : NO CONTROL (FTS,PBZ,PPB), NO ENDPOINT (FTS,PBZ,PPB). Huarte, H. R. and Benech

- Arnold, R. L. (2010). Hormonal Nature of Seed Responses to Fluctuating Temperatures in Cynara cardunculus (L.). Seed Sci.Res. 20: 39

- 45.

EcoReference No.: 152436
Chemical of Concern: FDE,GIB,PBZ,PCB; Habitat : T; Effect Codes : REP; Code : NO EFED CHEM (PCB), NO ENDPOINT (FDE,PBZ), OK (GIB). Jasik, J., Boggetti, B., Caricato, G., and Mantell, S. (1997). Characterisation of Morphology and Root Formation in the Model Woody Perennial Shrub Solanum aviculare Forst. Expressing rolABC Genes of Agrobacterium rhizogenes. Plant Sci. 124: 57

- 68.

EcoReference No.: 113943 Chemical of Concern: CTK,GIB,INDBA,PBZ; Habitat : T; Effect Codes : GRO;
Code : LITE EVAL CODED (INDBA), NO EF ED CHEM (CTK), NO MIXTURE (GIB,PBZ). Khaimov, A. and Mizrahi, Y. (2006). Effects of Day

- Length, Radiation, Flower Thinning and Growth Regulators on Flowering of the Vine Cacti Hylocereus undatus and Selenicereus megalanthus. J. Hortic. Sci. Biotechnol. 81 : 465

- 470.178 EcoReference No.: 151299 Chemical of Concern: BAD,EPH,GIB,PBZ; Habitat : T; Effect Codes : GRO,POP,REP; Code : NO ENDPOINT (BAD,EPH,GIB,PBZ). Khan, M. S. H., Wagatsuma, T., Akhter, A., and Tawaraya, K. (2009). Sterol Biosynthesis Inhibition by Paclobutrazol Induces Greater Aluminum (Al) Sensitivity in Al

Tolerant Rice. Am. J. Plant Physiol. 4: 89

- 99.

EcoReference No.: 152400
Chemical of Concer n: AlCl,PBZ; Habitat : A; Effect Codes : ACC,BCM,GRO;
Code : NO EFED CHEM (AlCl), NO ENDPOINT (PBZ). Kostenyuk, I., Oh, B. J., and So, I. S. (1999). Induction of Early Flowering in Cymbidium
Niveo

- marginatum Mak In Vitro. Plant Cell Rep. 19: 1

- 5.

EcoRe ference No.: 108745 Chemical of Concern: BAD,GIB,NAA,PBZ,TDZ; Habitat : T; Effect Codes : GRO,REP; Code : NO EFED CHEM (NAA), NO ENDPOINT (PBZ), OK (BAD,GIB,TDZ).
Koukourikou

- Petridou, M. and Porlingis, I. (1997). Presowing Application of Gibberellic
Aci d on Seeds Used for the Mung Bean Bioassay, Promotes Root Formation in Cuttings. Sci. Hortic. 70: 203

- 210.

EcoReference No.: 113951 Chemical of Concern: GIB,INDBA,PBZ; Habitat : T; Effect Codes : GRO; Code : NO ENDPOINT (PBZ), OK (GIB,INDBA). Lee, E. H ., Kramer, G. F., Rowland, R. A., and Agrawal, M. (1992). Antioxidants and Growth Regulators Counter the Effects of O3 and SO2 in Crop Plants. Agric. Ecosyst. Environ. 38: 99

- 106.

EcoReference No.: 119873 Chemical of Concern: FPD,PBZ,SO2; Habitat : T; Effect Codes : BCM,PHY; Code : LITE EVAL CODED (SO2), NO MIXTURE (FPD,PBZ). Liu, Y., Xu, Y., Xiao, J., Ma, Q., Li, D., Xue, Z., and Chong, K. (2011). OsDOG, a
Gibberellin

- Induced A20/AN1 Zinc

- Finger Protein, Negatively Regulates
Gibberellin

- Mediated Cell E longation in Rice. J. Plant Physiol. IN PRESS: 8 p.

EcoReference No.: 152444 Chemical of Concern: GIB,PBZ; Habitat : T; Effect Codes : CEL,GRO; Code : NO ENDPOINT (GIB,PBZ). Pennucci, A. and Jagschitz, J. A. (1984). Preemergent Herbicides for Crabgrass and Spurge179 Control in Lawn Turf. Proc. Northeast. Weed Sci. Soc. 38: 265

- 270.

EcoReference No.: 44111
Chemical of Concern: 24D,24DXY,BFL,BS,BTC,BTL,DCPA,DEE,EFS,FNPE,FPD,MCPP1,MSMA,NPP, ODZ,PBZ,PDM,SID,TFN; Habitat : T; Effect Codes : POP; Code : NO EF ED CHEM (BTC,BTL,DEE,EFS,MSMA,NPP,ODZ), NO ENDPOINT (24D,24DXY,BFL,BS,DCPA,FNPE,FPD,MCPP1,PBZ,PDM,SID,TFN), NO MIXTURE (24D,24DXY,MCPP1,TFN).

Price, C. E. and Anderson, N. H. (1985). Uptake of Chemicals from Foliar Deposits: Effects of Plant Species and Molecular Structure. Pestic. Sci. 16: 369

- 377 .

EcoReference No.: 103298 Chemical of Concern: 24DIO,24DXY,FSF,NaDPA,PBZ,PIRM,PMR; Habitat : T;
Effect Codes : ACC; Code : NO CONTROL (FSF,NaDPA,PBZ,PIRM,PMR), NO EFED CHEM (24DIO,24DXY), NO ENDPOINT (FSF, NaDPA,PBZ,PIRM,PMR). Ramoutar, D. (2009). Pyrethroid Resistance in the Annual Bluegrass Weevil, Listronotus maculicollis (Coleoptera: Curculionidae), from Southern New England Golf Courses. Ph.D. Thesis, University of Rhode Island, RI 161 p. (UMI# 341550 5).

EcoReference No.: 152514 Chemical of Concern: BFT,CTD,FPD,FRM,GCYH,PBZ,PCZ,PPB,SS,TBF,TXE;
Habitat : T; Effect Codes : MOR; Code : NO EFED CHEM (CTD,SS), NO MIXTURE (CTD,FPD,FRM,PBZ,PCZ,PPB,TBF,TXE), TARGET (BFT,GCYH). Ramoutar, D., Cowles, R. S., R equintina, E. Jr., and Alm, S. R. (2010). Synergism Between Demethylation Inhibitor Fungicides or Gibberellin Inhibitor Plant Growth Regulators and Bifenthrin in a Pyrethroid

- Resistant Population of Listronotus maculicollis (Coleoptera: Curculionidae). J. Econ. Entomol. 103: 1810

- 1814 Chapter 5 in Thesis
EcoRef# 152514.

EcoReference No.: 152401 Chemical of Concern: BFT,FPD,FRM,PBZ,PCZ,TXE; Habitat : T; Effect Codes : MOR; Code : NO ENDPOINT (BFT,FRM,TXE), NO MIXTURE (PBZ), OK (FPD,PCZ), TARGET (BFT). Rosado, A., Schapire, A. L., Bressan, R. A., Harfouche, A. L., Hasegawa, P. M., Valpuesta, V., and Botella, M. A. (2006). The Arabidopsis Tetratricopeptide Repeat

- Containing Protein TTL1 is Required for Osmotic Stress Responses and Abscisic Acid
Sensitivit y. Plant Physiol. 142: 1113

- 1126.180 EcoReference No.: 119582 Chemical of Concern: ASA,CTK,GIB,Halides,KCl,NAA,NaCl,PBZ; Habitat : T;
Effect Codes : CEL,GRO,REP; Code : NO EFED CHEM (CTK,KCl,NAA), NO ENDPOINT (ASA,GIB,Halides,NaCl,PBZ). Salaita, L., Kar, R. K., Majee, M., and Downie, A. B. (2005). Identification and Characterization of Mutants Capable of Rapid Seed Germination at 10(Degrees)C
from Activation

- Tagged Lines of Arabidopsis thaliana. J. Exp. Bot. 56: 2059

- 2069.

EcoReference No.: 104465 Chemical of Concern: ASAM,PBZ; Habitat : T; Effect Codes : PHY,REP; Code : NO ENDPOINT (ASAM,PBZ). Sharma, D., Shalini, L., and Raja, M. E. (2008). Uptake and Persistence of Soil Applied Paclobutrazol in 'Alphonso' Mango and Soil in the Konka n Region of Maharashtra,
India. Toxicol. Environ. Chem. 90: 577

- 583.

EcoReference No.: 152519 Chemical of Concern: PBZ; Habitat : T; Effect Codes : ACC; Code : NO CONTROL (PBZ), NO ENDPOINT (PBZ). Spinelli, F., Sabatini, E., Costa, G., and Rademacher, W. (2010). Reduction of Scab Incidence (Venturia inaequalis) in Apple with Prohexadione

- Ca and Trinexapac

Ethyl, Two Growth Regulating Acylcyclohexanediones. Crop Prot. 29: 691

- 698.

EcoReference No.: 152402 Chemical of Concern: CQTC,KRSM,MEM,PBZ,TXE; H abitat : T; Effect Codes : GRO,POP,REP; Code : NO EFED CHEM (KRSM), NO ENDPOINT (PBZ), NO MIXTURE (KRSM), OK (CQTC,MEM,TXE). Tukey, L. D. (1983). Vegetative Control and Fruiting on Mature Apple Trees Treated with
PP333. Acta Hortic. (Wagening.) 137: 103

- 109.

EcoReference No.: 44150 Chemical of Concern: PBZ; Habitat : T; Effect Codes : BCM,GRO,PHY,POP;
Code : NO CONTROL (PBZ), NO ENDPOINT (PBZ). White, C. N. and Rivin, C. J. (2000). Gibberellins and Seed Development in Maize. II. Gibberellin Synthesis Inhibition Enhances Abscisic Acid Signaling in Cultured Embryos. Plant Physiol. 122: 1089

- 1097.

EcoReference No.: 98439 Chemical of Concern: ASA,PBZ; Habitat : T; Effect Codes : BCM,REP; Code : NO ENDPOINT (ASA,PBZ). Wiesman, Z. and Riov, J. ( 1994). Interaction of Paclobutrazol and Indole

- 3

- Butyric Acid in181 Relation to Rooting of Mung Bean (Vigna radiata) Cuttings. Physiol. Plant. 92: 608

- 612.

EcoReference No.: 120336 Chemical of Concern: GIB,INDBA,PBZ; Habitat : T; Effect Codes : GRO,PHY;
Code : N O ENDPOINT (GIB,INDBA,PBZ). Ziv, M. and Ariel, T. (1991). Bud Proliferation and Plant Regeneration in Liquid

- Cultured Philodendron Treated with Ancymidol and Paclobutrazol. J. Plant Growth Regul. 10:
53

- 57.

EcoReference No.: 152455
Chemical of Concern: P BZ; Habitat : T; Effect Codes : GRO; Code : NO ENDPOINT (PBZ).

Excluded

Adriansen, E. and Odgaard, P. (1997). Residues of Paclobutrazol and Uniconazole in Nutrient Solutions From Ebb and Flood Irrigation of Pot Plants. Scientia Horticulturae, 69 (1

- 2) pp. 73

- 83, 1997

. Chem Codes : Chemical of Concern: PBZ Code : FATE.

Al

- Badawy, A. A., Barrett, J. E., and Nell, T. A. (1995). Growth of Begonia as Influenced by Paclobutrazol Residue in Compost

- Amended Media. 92nd annual meeting of the american society for horticultural science and the 40th annual congress of the canadian society for horticultural science, montreal, quebec, canada, july 30

- august 3, 1995. Hortscience 30: 802.
Chem Codes : Chemical of Concern: PBZ Code : ABSTRACT.

Aldrich, J. H. and Nor cini, J. G. (1996). Effect of Growth Retardants on Production of Containerized 'barbara Karst' Bougainvillea. 93rd annual conference of the american society for horticultural science, lexington, kentucky, usa, october 6

- 10, 1996.

Hortscience 31: 679.
Che m Codes : Chemical of Concern: PBZ Code : ABSTRACT.

Amini AnicĚ§a, GleĚ varec GaeĚ  ll JoeĚ  l (2009). Low Levels o Ajmalicine in Catharanthus Roseus Cell Suspens ion Cultures. Planta Medica, vol. 75, no. 2, pp. 187

- 191, 2009

. Chem Codes : Chemical of Concern: PBZ Code : IN VITRO.

Anon ( Pesticide Fact Sheet Number 62: Clipper (Paclobutrazol). Govt reports182 announcements &amp; index (gra&i), issue 02, 1987

. Chem Codes : Chemical of Concern: PBZ Code : NO TOX DATA.

Appleford, N. E. J., Wilkinson, M. D., Ma, Q., Evans, D. J., Stone, M. C., Pearce, S. P., Powers, S. J., Thomas, S. G., Jones, H. D., Phillips, A. L., Hedden, P., and Lenton, J. R. (2007). D ecreased Shoot Stature and Grain (Alpha)

- Amylase Activity Following Ectopic Expression of a Gibberellin 2

- Oxidase Gene in Transgenic Wheat. Journal of Experimental Botany, 58 (12) pp. 3213

- 3226, 2007

. Chem Codes : Chemical of Concern: PBZ Code : NO TOXIC ANT.

Bai, S. and Chaney, W. (2001). Gibberellin Synthesis Inhibitors Affect Electron Transport in
Plant Mitochondria. Plant Growth Regulation 35: 257

- 262.
Chem Codes : Chemical of Concern: PBZ Code : IN VITRO.

Bangerth K.F. (2009). Floral Induction in Mature, Perennial Angiosperm Fruit Trees: Similarities and Discrepancies With Annual/Biennial Plants and the Involvement of
Plant Hormones. Scientia Horticulturae, vol. 122, no. 2, pp. 153

- 163, 2009

. Chem Codes : Chemical of Concern: PBZ Code : BENEFICI AL EFFECT.

Barratt, D. H. P. (1986). Modulation by abscisic acid of storage protein accumulation in Vicia Faba L. cotyledons cultured in vitro. Plant Science 46: 159

- 167.
Chem Codes : Chemical of Concern: PBZ Code : IN VITRO.

Bellerby, John M., Morris, John H., and Smith, W. Ewen (1985). An aromatic schiff base stabilised as a coordinated enol iminium zwitterion by complex formation with a
series of divalent metal ions. Inorganica Chimica Acta 96: 203

- 207.
Chem Codes : Chemical of Concern: PBZ Code : CHEM METHODS.

Ben

- Cheikh, W., Perez

- Botella, J., Tadeo, F. R., Talon, M., and Primo

- Millo, E. (1997). Pollination Increases Gibberellin Levels in Developing Ovaries of Seeded Varieties
of Citrus. Plant Physiology, 114 (2) pp. 557

- 564, 1997

. Chem Codes : Chemical of Concern: PBZ Code : IN VITRO.

Berghage, R. D., Macneal, E. P., Wheeler, E. F., and Zachritz, W. H. (1999). "Green" Water Treatment for the Green Industries: Opportunities for Biofiltration of Greenhouse and Nursery Irrigation Water and Runoff With Constructed Wetlands. Hortscience 34:
50

- 54.
Chem Codes : Chemical of Concern: PBZ Code : FATE.

Black, S. N., Williams, L. J., Davey, R. J., Moffatt, F., Jones, R. V. H., McEwan, D. M., and183 Sadler, D. E. (1989). The preparation of enantiomers of p aclobutrazol: A crystal chemistry approach. Tetrahedron 45: 2677

- 2682.
Chem Codes : Chemical of Concern: PBZ Code : CHEM METHODS.

Bo Nielsen, J., Ahm SØ, Rensen, J., and Nielsen, F. ( The Usual Suspects

- Influence of Physicochemical Properties on L ag Time, Skin Deposition, and Percutaneous Penetration of Nine Model Compounds. J toxicol environ health a. 2009; 72(5):315

- 23. [Journal of toxicology and environmental health. Part a]: J Toxicol Environ
Health A

. Chem Codes : Chemical of Concern: PBZ C ode : HUMAN HEALTH.

Breceda, A., Ortiz, V., and Scrosati, R. (2005). Mauto (Lysiloma Divaricatum, Fabaceae) Allometry as an Indicator of Cattle Grazing Pressure in a Tropical Dry Forest in
Northwestern Mexico. Rangeland Ecology & Management [Rangeland Ec ol. Manage.]. Vol. 58, no. 1, pp. 85

- 88. Jan 2005.
Chem Codes : Chemical of Concern: PBZ Code : SURVEY.

Burden, R. S., Carter, G. A., Clark, T., Cooke, D. T., Croker, S. J., Deas, A. Hb, Hedden, P., James, C. S., and Lenton, J. R. (1987). Comparative Ac tivity of the Enantiomers of Triadimenol and Paclobutrazol as Inhibitors of Fungal Growth and Plant Sterol and Gibberellin Biosynthesis. Symposium on gibberellin and sterol synthesis inhibitors, london, england, uk, march 5, 1987. Pestic sci 21: 253

- 268.
Chem Codes : Chemical of Concern: PBZ Code : REVIEW.

Burden, R. S., Cooke, D. T., and Carter, G. A. ( 1989). Inhibitors of Sterol Biosynthesis and Growth in Plants and Fungi. Phytochemistry (oxf) 28: 1791

- 1804.
Chem Codes : Chemical of Concern: PBZ Cod e : REVIEW.

Burden, R. S., Deas, A. Hb, and Clark, T. (1987). Separation of Enantiomers of Fungicidal and Plant Growth Regulatory Triazole Alcohols Using Chiral Derivatization and Capillary Gas Chromatography. J chromatogr 391: 273

- 279.
Chem Codes : Chemical of Concern: PBZ Code : CHEM METHODS.

Burpee, L. L. (1996). Interactions Among Plant Growth Regulators and Fungicides on Dollar Spot of Creeping Bentgrass. Meeting of the american phytopathological society, southern division, greensboro, nort h carolina, usa, february 3

- 7, 1996. Phytopathology 86: S104.
Chem Codes : Chemical of Concern: PBZ Code : ABSTRACT.

Calvo, A. P., Nicola(acute)s, C., Nicola(acute)s, G., and Rodri(acute)guez, D. (2004).184 Evidence of a Cross

- Talk Regulation of a Ga 20

- Ox idase (Fsga20ox1) by Gibberellins and Ethylene During the Breaking of Dormancy in Fagus Sylvatica
Seeds. Physiologia Plantarum, 120 (4) pp. 623

- 630, 2004

. Chem Codes : Chemical of Concern: PBZ Code : IN VITRO.

Canivenc, M. C., Cagnac, B., Cabanne, F., a nd Scalla, R. (1989). Induced Changes of Chlorotoluron Metabolism in Wheat Cell Suspension Cultures. Plant physiol biochem (paris) 27: 193

- 202.
Chem Codes : Chemical of Concern: PBZ Code : IN VITRO.

Cerco(acute)s, M., Urbez, C., and Carbonell, J. (2003) . A Serine Carboxypeptidase Gene (Pscp), Expressed in Early Steps of Reproductive and Vegetative Development in Pisum Sativum, Is Induced by Gibberellins. Plant Molecular Biology, 51 (2) pp. 165

- 174, 2003

. Chem Codes : Chemical of Concern: PBZ Code : IN VITRO.

Chen, Run tao, Deng, Ying yu, and Chen, Xiao yan (2008). Study on the two

- generation reproductive toxicity of paclobutrazol in SD rats. Toxicology Letters 180: S165.
Chem Codes : Chemical of Concern: PBZ Code : ABSTRACT.

Chen, T., Dwyre

- Gygax, C., Hadfield, S. T., Willetts, C., and Breuil, C. (1996). Development of an Enzyme

- Linked Immunosorbent Assay for a Broad Spectrum Triazole Fungicide: Hexaconazole. Journal of agricultural and food chemistry 44:
1352

- 1356.
Chem Codes : Chemical of Concern : PBZ Code : METHODS.

Ciferri, Claudio, Pasqualato, Sebastiano, Screpanti, Emanuela, Varetti, Gianluca, Santaguida, Stefano, Dos Reis, Gabriel, Maiolica, Alessio, Polka, Jessica, De Luca, Jennifer G., De Wulf, Peter, Salek, Mogjiborahman, Rappsilber, Jur i, Moores, Carolyn A., Salmon, Edward D., and Musacchio, Andrea (2008

- ). Implications for Kinetochore

Microtubule Attachment from the Structure of an Engineered Ndc80 Complex. Cell
133: 427

- 439.
Chem Codes : Chemical of Concern: PBZ Code : NO TOXICANT.

Clark, T. and Deas, A. Hb (1985). Separation of Enantiomers of Fungicides and Some Analogs by Capillary Gas Chromatography Using Chirasil Val. J chromatogr 329:
181

- 185.
Chem Codes : Chemical of Concern: PBZ Code : CHEM METHODS.

Cohen, S., Svrjcek, A., Durborow, T., and Barnes, N. L. (1999). Water Quality Impacts by185 Golf Courses. Journal of environmental quality 28: 798

- 809.
Chem Codes : Chemical of Concern: PBZ Code : FATE.

Cross, J. V. and Berrie, A. M. (1990). Efficacy of Reduced Volume and Reduce d Dose Rate Spray Programmes in Apple Orchards. Crop Prot. 9: 207

- 217.
Chem Codes : Chemical of Concern: PBZ,VCZ Code : MIXTURE.

Davidson, S. E., Smith, J. J., Helliwell, C. A., Poole, A. T., and Reid, J. B. (2004). The Pea
Gene Lh Encodes Ent

- Kaurene O xidase. Plant Physiology, 134 (3) pp. 1123

- 1134,

2004

. Chem Codes : Chemical of Concern: PBZ Code : IN VITRO.

Dewar, D. E. and Hume, D. J. (1995). Effects of Paclobutrazol Seed Treatments on Canola Yield and Quality. 1994 annual meeting of the canadian society of agronomy, regina, saskatchewan, canada. Canadian journal of plant science 75: 211.
Chem Codes : Chemical of Concern: PBZ Code : ABSTRACT.

Dugardeyn, Jasper and Van Der Straeten, Dominique (2007). Ethylene: Fine

- tuning plant growth and develop ment by stimulation and inhibition of elongation. Plant Science
175: 59

- 70.
Chem Codes : Chemical of Concern: PBZ Code : NO TOXICANT.

Elmore, C. L., Gibeault, V. A., and Cudney, D. W. (1997). Invasion Resistance of Tall Fescue (Festuca Arundinaceae) and Perennial Ryegrass (Lolium Perenne) to Kikuyugrass (Pennisetum Clandestinum). Weed Technology, 11 (1) pp. 24

- 29, 1997

. Chem Codes : Chemical of Concern: PBZ Code : NO TOXICANT.

Fatland, B. L., Nikolau, B. J., and Wurtele, E. S. (2005). Reverse Genetic Characterization of Cytosolic Acetyl

- Coa Generation by Atp

- Citrate Lyase in Arabidopsis. Plant Cell, 17 (1) pp. 182

- 203, 2005

. Chem Codes : Chemical of Concern: PBZ Code : IN VITRO.

Faust, M. and Miller, A. N. (1989). Effect of Bioregulators and Herbici des on Calcium and Phosphorus Content of Fruits. Sixth international symposium on growth regulators in fruit production, penticton, british columbia, canada, july 25

- 29, 1988. Acta hortic (wageningen) 0: 409

- 416.
Chem Codes : Chemical of Concern: PBZ Co de : REVIEW.

Ferracini, Vera Lúcia, de Queiroz, Sonia Claudia Nascimento, and Rosa, Maria Aparecida (2008

- ). Determination of paclobutrazol in mango by LC/MS/MS system. Toxicology186 Letters 180: S166.
Chem Codes : Chemical of Concern: PBZ Code : CHEM MET HODS.

Fidanza, M. A., Wetzel III, H. C., Agnew, M. L., and Kaminski, J. E. (2006). Evaluation of Fungicide and Plant Growth Regulator Tank

- Mix Programmes on Dollar Spot Severity of Creeping Bentgrass. Crop Prot. 25: 1032

- 1038.
Chem Codes : Chemical of Co ncern: AZX,CTN,FDX,PBZ,PCZ,TXE Code : MIXTURE.

Fos, M., Proan(tilde)o, K., Alabadi(acute), D., Nuez, F., Carbonell, J., and Garci(acute)a

Marti(acute)nez, J. L. (2003). Polyamine Metabolism Is Altered in Unpollinated Parthenocarpic Pat

- 2 Tomato Ovaries. Plant Physiology, 131 (1) pp. 359

- 366, 2003

. Chem Codes : Chemical of Concern: PBZ Code : IN VITRO.

Gao, Y., Zhao, Y., Li, T., Liu, Y., Ren, C., and Wang, M. ( Molecular Cloning and Expression Analysis of an F

- Box Protein Gene Responsive to Plant Hormon es in Brassica Napus. Mol biol rep. 2010, feb; 37(2):1037

- 44. [Molecular biology reports]: Mol Biol Rep

. Chem Codes : Chemical of Concern: PBZ Code : IN VITRO.

German Society of Food Chemistry Southeastern Chapter (1998). 7th Workshop of the Southeastern Chapter of the German Society of Food Chemistry (Koethen, Germany; April 16

- 17, 1998). Lebensmittelchemie 52: 128

- 132.
Chem Codes : Chemical of Concern: PBZ Code : HUMAN HEALTH.

Ghosh, S., Penterman, J. N., Madey, E., Baird, L. M., Frederic k, J. M., Cummings, D. J.,
Hall

- Glenn, F., De Giacomo, A., Volk, S., and Dumbroff, E. B. (2003). Paclobutrazol: Its Physiological Effects and Biochemical Functions During Plant

Stress. Physiology and Molecular Biology of Plants 9: 163

- 173.
Chem Codes : Ch emical of Concern: PBZ Code : REVIEW.

Gogoláková, Anna and Strba, Peter (2009). The impact of retardant Bonzi on growth and flowering of Hibiscus rosa

- sinensis L. Comparative Biochemistry and Physiology

- Part A: Molecular & Integrative Physiology 153: S199.
Chem Codes : Chemical of Concern: PBZ Code : ABSTRACT.

Gong, P., Sun, T. H., Beudert, G., and Hahn, H. H. (1997). Ecological Effects of Combined Organic or Inorganic Pollution on Soil Microbial Activities. Water Air Soil Pollut.
96: 133

- 143.
Chem Codes : Chemical of Concern: As,Cu,PBZ,PHE,Zn Code :187 BACTERIA,MIXTURE.

Gong, P., Sun, T. H., Beudert, G., and Hahn, H. H. (1997). Ecological Effects of Combined Organic or Inorganic Pollution on Soil Microbial Activities. Water Air Soil Pollut.
96: 133

- 143.
Chem Codes : Chemical of Concern: PBZ Code : BACTERIA,MIXTURE.

Gong, P., Sun, T. H., Beudert, G., and Hahn, H. H. (1997). Ecological Effects of Combined Organic or Inorganic Pollution on Soil Microbial Activities. Water air and soil pollution 96: 133

- 143.
Chem Codes : Chemical of Concern: PBZ Code : BACTERIA, MIXTURE.

Gong Ping and Beudert, G. (1996). Ecological Effects of Multi

- Effects

- Triazole on Soil
Microbe. Huanjing kexue 17: 36

- 38, 92.
Chem Codes : Chemical of Concern: PBZ Code : NON

- ENGLISH.

Gong Ping, Sun Tieheng, Beudert, G., and Hahn, H. H. (1996). Side

- Effects of Organic and Inorganic Pollutants on Soil Nitrification and Respiration. Journal of environmental sciences (china) 8: 66

- 76.
Chem Codes : Chemical of Concern: PBZ Code : FATE.

Gonza(acute)lez

- Garci(acute)a, M. P., Rodri(acute)guez, D., Nicola(acute)s, C., Nicola(acute)s, G., and Lorenzo, O. (2006). A Protein Phosphatase 2a From Fagus Sylvatica Is Regulated by Ga and Okadaic Acid in Seeds and Related to the
Transiti on From Dormancy to Germination. Physiologia Plantarum, 128 (1) pp. 153

- 162, 2006 128: 153

- 162.
Chem Codes : Chemical of Concern: PBZ Code : IN VITRO.

Gonçalves, I. C. R., Araújo, A. S. F., Carvalho, E. M. S., and Carneiro, R. F. V. (2005). Effect of p aclobutrazol on microbial biomass, respiration and cellulose decomposition
in soil. European Journal of Soil Biology 45: 235

- 238.
Chem Codes : Chemical of Concern: PBZ Code : FATE.

Gopi, R., Jaleel, C. Abdul, Sairam, R., Lakshmanan, G. M. A., Gomathin ayagam, M., and Panneerselvam, R. ( Differential effects of hexaconazole and paclobutrazol on biomass, electrolyte leakage, lipid peroxidation and antioxidant potential of Daucus

carota L. Colloids and Surfaces B: Biointerfaces In Press, Accepted Manuscri pt: 148.
Chem Codes : Chemical of Concern: PBZ Code : NO SOURCE.

Gray, William M and Estelle, Mark (1998). Biochemical genetics of plant growth. Current188 Opinion in Biotechnology 9: 196

- 201.
Chem Codes : Chemical of Concern: PBZ Code : IN VITRO.

Gutie (acute)rrez

- Man(tilde)ero, F. J., Ramos

- Solano, B., Probanza, A., Mehouachi, J., Tadeo, F. R., and Talon, M. (2001). The Plant

- Growth

- Promoting Rhizobacteria Bacillus Pumilus and Bacillus Licheniformis Produce High Amounts of Physiologically Active Gibbere llins. Physiologia Plantarum, 111 (2) pp. 206

- 211,

2001

. Chem Codes : Chemical of Concern: PBZ Code : BACTERIA.

Harrison, J., Marshall, C., and Baylis, A. D. (1994). Studies on a Tillering Inhibitor Pps889. Annual meeting of the society for experimenta l biology, swansea, wales, uk, april 11

- 15, 1994. Journal of experimental botany 45: 56.
Chem Codes : Chemical of Concern: PBZ Code : ABSTRACT.

Haughan, Penny A., Burden, Raymond S., Lenton, John R., and Goad, L. John (1989). Inhibition of celery cell gr owth and sterol biosynthesis by the enantiomers of paclobutrazol. Phytochemistry 28: 781

- 787.
Chem Codes : Chemical of Concern: PBZ Code : IN VITRO.

Haughan, Penny A., Lenton, John R., and Goad, L. John (1988). Sterol requirements and paclobutrazol inhibition of a celery cell culture. Phytochemistry 27: 2491

- 2500.
Chem Codes : Chemical of Concern: PBZ Code : IN VITRO.

Haughan, Penny A., Lenton, John R., and John Goad, L. (1987). Paclobutrazol inhibition of sterol biosynthesis in a cell suspension culture and evidence of an essential role for

24

- ethylsterol in plant cell division. Biochemical and Biophysical Research

Communications 146: 510

- 516.
Chem Codes : Chemical of Concern: PBZ Code : IN VITRO.

Holloway, P. J. and Stock, D. (1990). Factors Affecting the Activation of Foliar Uptake of Agrochemicals by Surfactants. Karsa, d. R. (Ed.). Royal society of chemistry special publication, no. 77. Industrial applications of surfactants ii. Symposium, manchester, england, uk, april 19

- 20, 1989. Viii+4 03p. Royal society of chemistry: cambridge, england, uk; crc press, inc.: Boca raton, florida, usa. Illus. Maps. Isbn 0

- 85186

- 617

- 4.; 303

- 337.
Chem Codes : Chemical of Concern: PBZ Code : REVIEW.

Horowitz, M., Smith, E. M., and Gorski, S. F. (1990). Sl ow

- Release Tablets as Carriers for
Herbicides and Growth

- Regulators. 11th conference of the weed science society of189 israel, bet dagan, israel, february 26

- 27, 1990. Phytoparasitica 18: 255

- 256.
Chem Codes : Chemical of Concern: PBZ Code : ABSTRACT.

Hsue h, W., Li, R., and Pei, Y. (1986). Separation of 1 2 4 Triazole Derivatives by High

Performance Liquid Chromatography. J chromatogr 356: 433

- 437.
Chem Codes : Chemical of Concern: PBZ Code : CHEM METHODS.

Huang, Q., Li, W., and Hartung, J. S. (2003). Association of Xylella Fastidiosa With Leaf Scorch in Japanese Beech Bonsai. Canadian Journal of Plant Pathology, 25 (4) pp.

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- 405, 2003

. Chem Codes : Chemical of Concern: PBZ Code : BACTERIA, IN VITRO.

Huett, D. O., George, A. P., Slack, J. M., and Morris, S. C. (1997). Diagnostic Leaf Nutrient
Standards for Low

- Chill Peaches in Subtropical Australia. Australian Journal of Experimental Agriculture, 37 (1) pp. 119

- 126, 1997

. Chem Codes : Chemical of Concern: PBZ Code : SURVEY.

Huey Jen Chen, Mubarack, M. M., Naess, S. K., Stover, E., and Swartz, H. J. (1996). Technique Development Towards Production of an in Vitro Graft Chimera in Rubus. Fruit Varieties Journal, 50 (2) pp. 105

- 113, 1996

. Chem Codes : Chemical of Concern: PBZ Code : IN VITRO.

Hunter, D. M. and Proctor, J. Ta (1987). Effect of Paclobutrazol on Photosynthesis in Grapes. 84th annual meeting of the american society for horticultural science and the 34th annual congress of the interamerican society for tropical horticulture,
orla ndo, florida, usa, november 6

- 12, 1987. Hortscience 22: 1109.
Chem Codes : Chemical of Concern: PBZ Code : ABSTRACT.

Illing, H. Pa (1997). Is Working in Greenhouses Healthy? Evidence Concerning the Toxic Risks That Might Affect Greenhouse Workers. Occup ational medicine (london) 47:
281

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Chem Codes : Chemical of Concern: PBZ Code : HUMAN HEALTH.

Inagaki Soichi, Miura

- Kamio Asuka, Saze Hidetoshi, Kakutani Tetsuji, Nakamura Yasukazu, Lu Falong, Cui, X. i. a., Cao Xiaofeng, Kimura Hiroshi, and Inagaki Soichi (2010). Autocatalytic Differentiation of Epigenetic Modifications Within the Arabidopsis

Genome. EMBO Journal, vol. 29, no. 20, pp. 3496

- 3506, 2010

. Chem Codes : Chemical of Concern: PBZ Code : NO TOXICANT.

Jacyna, T. and Dodds, K. G. (1992). Ef fect of Various Methods of Paclobutrazol Application190 on Cherry Tree Performance and Soil Residue. 52nd annual meeting of the ashs (american society for horticultural science) southern region, lexington, kentucky, usa, february 1

- 3, 1992. Hortscience 27: 1 168.
Chem Codes : Chemical of Concern: PBZ Code : ABSTRACT.

Jarvis, T. D., Earley, F. Gp, and Rees, H. H. (1994). Inhibition of the Ecdysteroid Biosynthetic Pathway in Ovarian Follicle Cells of Locusta Migratoria. Pesticide biochemistry and physiology 48: 153

- 162.
Chem Codes : Chemical of Concern: PBZ Code : IN VITRO.

Jennings, J. C., Coolbaugh, R. C., Nakata, D. A., and West, C. A. (1993). Characterization and Solubilization of Kaurenoic Acid Hydroxylase from Gibberella fujikuroi. Plant Physiol. 10 1: 925

- 930.
Chem Codes : Chemical of Concern: PBZ,SFZ Code : IN VITRO.

Jennings, J. C., Coolbaugh, R. C., Nakata, D. A., and West, C. A. (1993). Characterization and Solubilization of Kaurenoic Acid Hydroxylase From Gibberella Fujikuroi. Plant Physiol. 101: 925

- 930.
Chem Codes : Chemical of Concern: PBZ,SFZ Code : IN VITRO.

Jiménez, Jesús ngel, onso

- Ramírez, Ana, and Nicolás, Carlos (2008

- ). Two cDNA clones (FsDhn1 and FsClo1) up

- regulated by ABA are involved in drought responses in Fagus sylvatica L. seeds. Journal of Plant Physiology 165: 1798

- 1807.
Chem Codes : Chemical of Concern: PBZ Code : NO TOXICANT.

Jonsson, C. M., Ferracini, V. L., Paraiba, L. C., Rangel, M., and Aguiar, S. R. (2002). Biochemical Changes and Accumulation in "Pacu" Fish (Me tynnis Argenteus) Exposed to Paclobutrazol (Alteracoes Bioquimicas E Acumulo Em Pacus (Metynnis Argenteus) Expostos Ao Paclobutrazol). Sci. Agric. 59: 441

- 446(POR) (ENG ABS).
Chem Codes : Chemical of Concern: PBZ Code : NON

- ENGLISH.

Kato, H. (1987). 198 6 Evaluation of Candidate Pesticides: B

- 1 Fungicides Rice and Other
Cereals. Jpn. Pestic. Inf. 50: 29

- 32.
Chem Codes : Chemical of Concern: CuO,PBZ Code : NO DURATION.

Kawabata, O. and Defrank, J. (1993). Purple Nutsedge Suppression With Soil

- Applied
Paclobutrazol. Hortscience 28: 59.
Chem Codes : Chemical of Concern: PBZ Code : ABSTRACT.

Kenna, M. and Curry, K. (1989). Growth Regulation of Four Bermudagrass Cultivars. 86th191 annual meeting of the american society for horticultural science, tulsa, ok lahoma, usa, july 29

- august 3, 1989. Hortscience 0: 70.
Chem Codes : Chemical of Concern: PBZ Code : ABSTRACT.

Kishor Arun, Srivastav Manish, Dubey A.K., Singh A.K., Sairam R.K., Pandey R.N., Dahuja Anil, and Sharma R.R. (2009). Paclobutrazol Minimises t he Effects of Salt Stress in Mango (Mangifera Indica L.). Journal of Horticultural Science and Biotechnology, vol. 84, no. 4, pp. 459

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. Chem Codes : Chemical of Concern: PBZ Code : BENEFICIAL EFFECTS.

Kobayashi, M., Nagayama, T., Hashimoto, T. , Haneishi, N., Ito, M., Tamura, Y., and Tomomatsu, T. (1998). Survey of Pesticides Residues in Vegetable Products Collected From 1994 Through 1997. Journal of the food hygienic society of japan
39: 233

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Chem Codes : Chemical of Concern: PBZ Code : HUMAN HEALTH.

Kozlowski, T. T., Kramer, P. J., and Pallardy, S. G. (1991). Physiological Ecology the Physiological Ecology of Woody Plants. Kozlowski, t. T., P. J. Kramer and s. G. Pallardy. Physiological ecology: the physiological ecology of woody plant s. Xix+657p. Academic press, inc.: San diego, california, usa London, england, uk. Illus. Maps. Isbn 0

- 12

- 424160

- 3.; 0: Xix+657p.
Chem Codes : Chemical of Concern: PBZ Code : REVIEW.

Krizek, D. T., Mirecki, R., and Semeniuk, P. (1987). Influence of Paclo butrazol Pretreatment and Sulfur Dioxide Dose Rate on Sulfur Dioxide Sensitivity and Transpiration Rate in
Coleus. 84th annual meeting of the american society for horticultural science and the 34th annual congress of the interamerican society for tropical horticulture, orlando, florida, usa, november 6

- 12, 1987. Hortscience 22: 1155.
Chem Codes : Chemical of Concern: PBZ Code : ABSTRACT.

Kuehny, J. S., Chang, W. C., and Branch, P. (1996). Influence of Plant Growth Regulators on Postharvest Quality of Za ntedeschia and Preplant Treatment for Preventing Erwinia
Infection. 93rd annual conference of the american society for horticultural science, lexington, kentucky, usa, october 6

- 10, 1996. Hortscience 31: 597.
Chem Codes : Chemical of Concern: PBZ Code : ABSTRACT.

Kutzner, B. and Buchenauer, H. (1986). Effect of Various Triazole Fungicides on Growth and Lipid Metabolism of Fusarium Moniliforme as Well as on Gibberellin Contents in Culture Filtrates of the Fungus (Wirkung Verschiedener Triazolfungizide Au f Wachstum Und Lipidstoffwechsel Von Fusarium Moniliforme Sowie Auf Die192 Gibberellingehalte in Kulturfilitraten Des Pilzes). Z. Pflanzenkrankh. Pflanzenschutz
93: 597

- 607(GER) (ENG ABS).
Chem Codes : Chemical of Concern: BTN,PBZ Code : NON

- ENGLISH.

Latim er, J. G. and Oetting, R. D. (1995). Conditioning Treatments Affect Growth and Spider
Mite Infestation of Greenhouse

- Grown Bedding Plants. 92nd annual meeting of the american society for horticultural science and the 40th annual congress of the
canadian s ociety for horticultural science, montreal, quebec, canada, july 30

- august 3, 1995. Hortscience 30: 829.
Chem Codes : Chemical of Concern: PBZ Code : ABSTRACT.

Lee, E. H., Byun, J. K., and Steffens, G. L. (1985). Increased Tolerance of Plants to Sulfur Dioxide Chilling and Heat Stress by a New Gibberellin Biosynthesis Inhibitor Paclobutrazol Pp

- 333. Annual meeting of the american society of plant physiologists, providence, r.i., Usa, june 23

- 28, 1985. Plant physiol (bethesda) 77: 135.
Chem Codes : Chemi cal of Concern: PBZ Code : ABSTRACT.

Lee, E. H., Rowland, R., and Mulchi, C. (1989). Use of Antioxidant Compounds to Overcome Air Pollution Stress in Crop Plants. Annual meeting of the american society of plant physiologists held jointly with the canad ian society of plant physiologists, toronto, ontario, canada, july 30

- august 3, 1989. Plant physiol (bethesda) 89: 182.
Chem Codes : Chemical of Concern: PBZ Code : ABSTRACT.

Lee, S., Lee, S., Yang, K. Y., Kim, Y. M., Park, S. Y., Kim, S. Y., and Soh, M. S. (2006). Overexpression of Pre1 and Its Homologous Genes Activates Gibberellin

- Dependent Responses in Arabidopsis Thaliana. Plant and Cell Physiology, 47 (5) pp. 591

- 600,
2006

. Chem Codes : Chemical of Concern: PBZ Code : IN VITRO.

Leon

- Kloosterziel, K. M., Gil, M. A., Ruijs, G. J., Jacobsen, S. E., Olszewski, N. E., Schwartz, S. H., Zeevaart, J. A. D., and Koornneef, M. (1996). Isolation and
Characterization of Abscisic Acid

- Deficient Arabidopsis Mutants at Two New Loci.
Plant Journal 10: 655

- 661.
C hem Codes : Chemical of Concern: PBZ Code : NO TOX DATA.

Leshem, B., Ronen, R., and Lurie, S. (1994). Thidazuron and Paclobutrazol Appear to Mimic Cytokinin and Auxin Influences on Organ Regeneration and Protein Profiles in Cultured Melon Cotyledons. J ournal of Plant Physiology, 143 (3) pp. 344

- 348, 1994

. Chem Codes : Chemical of Concern: PBZ Code : IN VITRO.193 Liao, W. B., Ruan, M. B., Cui, B. M., Xu, N. F., Lu, J. J., and Peng, M. (2009). Isolation and Characterization of a Gai/Rga

- Like Gene From Gossypium Hirsutum. Plant Growth Regulation, 58 (1) pp. 35

- 45, 2009

. Chem Codes : Chemical of Concern: PBZ Code : IN VITRO.

Libal

- Weksler, Y., Vishnevetsky, M., Ovadis, M., and Vainstein, A. (1997). Isolation and Regulation of Accumulation of a Minor C hromoplast

- Specific Protein From
Cucumber Corollas. Plant Physiology 113: 59

- 63.
Chem Codes : Chemical of Concern: PBZ Code : IN VITRO.

Liu, K., Lee, X. S., and Qiu, W. (1989). Chemical Pruning of Pittosporum

- Tobira With Caprylic Acid and Paclobutrazol and the Physiological Effect. Acta hortic sin 16: 51

- 56.
Chem Codes : Chemical of Concern: PBZ Code : NON

- ENGLISH.

Lorenzo, J. C., Gonzalez, B. L., Escalona, M., Teisson, C., Espinosa, P., and Borroto, C. (1998). Sugarcane Shoot Formation in an Improved Temporary Immersion System. Plant Cell, Tissue Organ Cult. 54: 197

- 200.
Chem Codes : Chemical of Concern: PBZ Code : REFS CHECKED,REVIEW.

Lurie, S., Ronen, R., Lipsker, Z., and Aloni, B. (1994). Effects of Paclobutrazol and Chilling Temperatures on Li pids, Antioxidants and Atpase Activity of Plasma Membrane Isolated From Green Bell Pepper Fruits. Physiologia Plantarum, 91 (4) pp. 593

- 598,
1994

. Chem Codes : Chemical of Concern: PBZ Code : IN VITRO.

Marangoni, A. G. and Stanley, D. W. (1991). Studies on the Long

- Term Storage of Mature,
Green Tomato Fruit. J hortic sci 66: 81

- 84.
Chem Codes : Chemical of Concern: PBZ Code : NO SPECIES (DEAD).

Mathews, S. (2009). Use of a Tree Growth Regulator to Manage Vegetation Near Overhead
Power Lines. M .S. Thesis, Oklahoma Oklahoma State University, OK 25 p. (UMI# 1469173).
Chem Codes : Chemical of Concern: PBZ Code : NO CONC .

Mathis, P. (1995). Photosynthesis: From Light to Biosphere. In: P.Mathis (Ed.), Proc.10th Int.Photosynthesis Congr., Aug.20

- 25, 1995, Montpellier, France, Photosynthesis: From Light to Biosphere, Kluwer Acad.Publ., Dordrecht, Netherlands 4: (Table of Contents).194 Chem Codes : Chemical of Concern: AlS,CaCl2,CdN,HOX,Halides,NaCl,PBZ,PQT,PbN Code : SKIMMED .

Mathis, P. (1995). Pho tosynthesis: From Light to Biosphere. In: P.Mathis (Ed.), Proc.10th Int.Photosynthesis Congr., Aug.20

- 25, 1995, Montpellier, France, Photosynthesis: From Light to Biosphere, Kluwer Acad.Publ., Dordrecht, Netherlands 4: (Table of Contents).
Chem Codes : C hemical of Concern: AlS,CaCl2,CdN,HOX,Halides,NaCl,PBZ,PQT,PbN Code : SKIMMED .

Meilan, R. (1997). Floral Induction in Woody Angiosperms. New Forests 14: 179

- 202.
Chem Codes : Chemical of Concern: PBZ Code : REVIEW.

Mercier, J., Stienstra, W. C., and Krupa, S. V. (1998). Reduction in Dollar Spot of Turf Associated With Applications of the Growth Regulator Paclobutrazol. Annual meeting of the american phytopathological society, las vegas, nevada, usa, november

8

- 12, 1998. Phytopathology 88: S62.
Chem Codes : Chemical of Concern: PBZ Code : ABSTRACT.

Messersmith, C. G. and Adkins, S. W. (1995). Integrating Weed

- Feeding Insects and
Herbicides for Weed Control. Weed technology 9: 199

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Chem Codes : Chemical of Concern: PBZ Code : REVIEW.

Miura, A., Nakamura, M., Inagaki, S., Kobayashi, A., Saze, H., and Kakutani, T. (2009). An Arabidopsis Jmjc Domain Protein Protects Transcribed Genes From Dna Methylation at Chg Sites. EMBO Journal, 28 (8) pp. 1078

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. Chem Codes : Chemical of Concern: P BZ Code : NO TOXICANT.

Miyazaki, A. (1997). Progress and Prospects of Optically Active Pesticides. J. Pestic. Sci.
22: 136

- 155(JPN).
Chem Codes : Chemical of Concern: ACP,CPY,CYF,CYH,CYP,FNPE,FRM,HTX,MLN,MYC,Naled,PBZ,PPG,VCZ
Code : NON

- ENGLISH.

Miyazaki, A. (1997). Progress and Prospects of Optically Active Pesticides. J. Pestic. Sci.
22: 136

- 155(JPN).
Chem Codes : Chemical of Concern: ACP,CPY,CYF,CYH,CYP,FNPE,FRM,HTX,MLN,MYC,Naled,PBZ,PPG,VCZ
Code : NON

- ENGLISH.195 Miyazaki, A. (1997). Progress and Prospects of Optically Active Pesticides. Journal of pesticide science 22: 136

- 155.
Chem Codes : Chemical of Concern: PBZ Code : CHEM METHODS.

Nagaraju, V., Bhowmik, G., and Parthasarathy, V. A. (2002). Effect of Paclobutrazol and
Sucrose on in Vit ro Cormel Formation in Gladiolus. Acta Botanica Croatica 61: 27

- 33.
Chem Codes : Chemical of Concern: PBZ Code : IN VITRO.

Nobel, A. (1993). Partition Coefficients N Octanol Water for Pesticides. J chromatogr 642:
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- 14.
Chem Codes : Chemical of Concern : PBZ Code : CHEM METHODS.

Olle, M. and Bender, I. (2009). Causes and Control of Calcium Deficiency Disorders in Vegetables: a Review. Journal of Horticultural Science and Biotechnology, vol. 84, no. 6, pp. 577

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. Chem Codes : Chemical of Concer n: PBZ Code : NUTRIENT.

Owen, W. J. (1992). Potential for Synergising Herbicides Through Modification of
Metabolism. Denholm, i., A. L. Devonshire and d. W. Hollomon (ed.). Resistance '91: achievements and developments in combating pesticide resistance. Sci symposium, harpenden, england, uk, july 15

- 17, 1991. Xiii+367p. Elsevier science publishers ltd.: London, england, uk; new york, new york, usa. Isbn 1

- 85166

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340

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Chem Codes : Chemical of Concern: PBZ Code : REVIEW.

Pallett, K. E. (1991). O ther Primary Target Sites for Herbicides. Kirkwood, r. C. (Ed.). Topics in applied chemistry: target sites for herbicide action. Xv+339p. Plenum press: new york, new york, usa London, england, uk. Illus. Isbn 0

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123

- 167.
Chem Codes : Chemi cal of Concern: PBZ Code : REVIEW.

Parai(acute)ba, L. C. (2007). Pesticide Bioconcentration Modelling for Fruit Trees. Chemosphere, 66 (8) pp. 1468

- 1475, 2007

. Chem Codes : Chemical of Concern: PBZ Code : MODELING.

Park, Ji Yeon, Choi, Jeong Heui, bd El

- Aty, A. M., Kim, Bo Mi, Oh, Jae Ho, Do, Jung Ah, Kwon, Ki Sung, Shim, Ki Hoon, Choi, Ok Ja, Shin, Sung Chul, and Shim, Jae Han (2011

- ). Simultaneous multiresidue analysis of 41 pesticide residues in cooked foodstuff using QuEChERS: Comparison with class ical method. Food Chemistry196 128: 241

- 253.
Chem Codes : Chemical of Concern: PBZ Code : FOOD.

Park, Jung Eun, Kim, Youn Sung, Yoon, Hae Kyung, and Park, Chung Mo (2007).
Functional characterization of a small auxin

- up RNA gene in apical hook development in Arabidopsis. Plant Science 172: 150

- 157.
Chem Codes : Chemical of Concern: PBZ Code : NO TOXICANT.

Passioura, J. B. (2002). Soil Conditions and Plant Growth. Plant, Cell and Environment 25:
311

- 318.
Chem Codes : Chemical of Concern: PBZ Code : BI OLOGICAL TOXICANT.

Paulsen, P. J. and Hensley, D. (1995). Chemical Growth Regulation of Landscape
Groundcovers. 92nd annual meeting of the american society for horticultural science and the 40th annual congress of the canadian society for horticultural s cience, montreal, quebec, canada, july 30

- august 3, 1995. Hortscience 30: 854.
Chem Codes : Chemical of Concern: PBZ Code : ABSTRACT.

Pennucci, A. and Jackson, N. (1986). Distinguishing Phytotoxicity and Pathogenicity by Fungi in Growth Retardant Treated Turfgrass. Annual meeting of the american phytopathological society (northeastern division), nov. 6

- 8, 1985. Phytopathology 76:
657.
Chem Codes : Chemical of Concern: PBZ Code : ABSTRACT.

Pennucci, A. and Jackson, N. (1986). In

- Vitro Growth Promotion of Several Turfgrass Pathogens by Plant Growth Retardants. Annual meeting of the american phytopathological society (northeastern division), nov. 6

- 8, 1985. Phytopathology 76:
657.
Chem Codes : Chemical of Concern: PBZ Code : ABSTRACT.

Petridou, M., Voy iatzi, C., and Voyiatzis, D. (2001). Methanol, Ethanol and Other Compounds Retard Leaf Senescence and Improve the Vase Life and Quality of Cut Chrysanthemum Flowers. Postharvest Biology and Technology, 23 (1) pp. 79

- 83,

2001

. Chem Codes : Chemical of Conc ern: PBZ Code : NO SPECIES (DEAD).

Pinhero, R. G., Paliyath, G., Murr, D. P., and Fletcher, R. A. (1997). Paclobutrazol

- and Ancymidol

- Induced Changes in Antioxidant Enzymes of Maize Seedlings. Plant biology '97: 1997 annual meetings of the american soc iety of plant physiologists and the canadian society of plant physiologists, japanese society of plant physiologists197 and the australian society of plant physiologists, vancouver, british columbia, canada, august 2

- 6, 1997. Plant physiology (rockville) 114: 103.
Chem Codes : Chemical of Concern: PBZ Code : ABSTRACT.

Purohit, A. K., Rawat, T. S., and Kumar, A. (2003). Shelf Life and Quality of Ber [Zizyphus Mauritiana Lamk.] Fruit Cv. Umran in Response to Post Harvest Application of
Ultraviolet Radiation an d Paclobutrazol. Plant Foods for Human Nutrition, 58 (3) pp. 1

- 7, 2003

. Chem Codes : Chemical of Concern: PBZ Code : NO SPECIES (DEAD).

Qiao, Q. i., Xing Fu

- Wu, Chen Hong

- Feng, Qiao, Q. i., Qiao, Q. i., and Xiao Ya

- Ping (2009). Somatic Embryogenesis an d in Vitro Flowering in Saposhnikovia Divaricata. Journal of Plant Growth Regulation, vol. 28, no. 1, pp. 81

- 86, 2009

. Chem Codes : Chemical of Concern: PBZ Code : BENEFICIAL EFFECTS.

Querrec, L. and Filion, L. (2008). White

- Tailed Deer Activity Reconst ructed From Tree

Rings in Eastern Boreal Canada. Forest Ecology and Management, 255 (1) pp. 234

- 244, 2008

. Chem Codes : Chemical of Concern: PBZ Code : NO TOXICANT.

Rahier, A. and Taton, M. (1997). Fungicides as Tools in Studying Postsqualene Sterol Syn thesis in Plants. Pesticide biochemistry and physiology 57: 1

- 27.
Chem Codes : Chemical of Concern: PBZ Code : REVIEW.

Raun andersen, H., Vinggaard, A., Hoj rasmussen, T., Gjermandsen, I. M., and Cecilie
bonefeld

- Jorgensen, E. (2002). Effects of Current ly Used Pesticides in Assays for Estrogenicity, Androgenicity, and Aromatase Activity in Vitro. Toxicology and Applied Pharmacology [Toxicol. Appl. Pharmacol.]. Vol. 179, no. 1, pp. 1

- 12. 15 Feb

2002.
Chem Codes : Chemical of Concern: PBZ Code : HUMAN HEALTH.

Raventos, D., Meier, C., Mattsson, O., Jensen, A. B., and Mundy, J. (2000). Fusion Genetic Analysis of Gibberellin Signaling Mutants. Plant Journal, 22 (5) pp. 427

- 438, 2000

. Chem Codes : Chemical of Concern: PBZ Code : IN VITRO.

Reeder, A. L., Foley, G. L., Nichols, D. K., Hansen, L. G., Wikoff, B., Faeh, S., Eisold, J., Wheeler, M. B., Warner, R., Murphy, J. E., and Beasley, V. R. (1998). Forms and Prevalence of Intersexuality and Effects of Environmental Contaminants on Sexuality
in Cricket F rogs (Acris crepitans). Environ. Health Perspect. 106: 261

- 266.
Chem Codes : Chemical of Concern:198 ACR,ADC,AMTR,AND,ATZ,BDC,BMY,BTC,BTY,CBF,CBL,CHD,CPP,CPY,DD T,DFP,DLD,DMT,DS,DU,DZ,DZE,EN,EP,EPRN,EPTC,ES,FNF,FNTH,HCCH,HP T,HXZ,Hg,IFP,LNR,MBZ,MCB,MDT,MLN,MOM ,MP,MRX,MTL,MTZ,MVP,MX C,NPM,NPP,OML,OXT,OYZ,PBZ,PDM,PPCP,PPN,PPZ,PRN,PRT,Pb,SZ,TBF,TB O,TFN Code : NO DURATION,SURVEY.

Reeder, A. L., Foley, G. L., Nichols, D. K., Hansen, L. G., Wikoff, B., Faeh, S., Eisold, J., Wheeler, M. B., Warner, R., Murphy, J. E., and Beasley, V. R. (1998). Forms and Prevalence of Intersexuality and Effects of Environmental Contaminants on Sexuality in Cricket Frogs (Acris Crepitans). Environ. Health Perspect. 106: 261

- 266.
Chem Codes : Chemical of Concern: ACR,ADC,AMTR,AND,ATZ,BD C,BMY,BTC,BTY,CBF,CBL,CHD,CPP,CPY,DD T,DFP,DLD,DMT,DS,DU,DZ,DZE,EN,EP,EPRN,EPTC,ES,FNF,FNTH,HCCH,HP T,HXZ,Hg,IFP,LNR,MBZ,MCB,MDT,MLN,MOM,MP,MRX,MTL,MTZ,MVP,MX C,NPM,NPP,OML,OXT,OYZ,PBZ,PDM,PPN,PPZ,PRN,PRT,Pb,SZ,TBF,TBO,TFN
Code : NO DURATION,SURVEY.

Rieger, M. and Scalabrelli, G. (1989). Paclobutrazol

- Induced Alteration of Growth and Root Physiology of Nemaguard Peach. 86th annual meeting of the american society for horticultural science, tulsa, oklahoma, usa, july 29

- august 3, 1989. Hortscience 0:
113.
Che m Codes : Chemical of Concern: PBZ Code : ABSTRACT.

Romanowska

- Duda, Z., Knypl, J. S., and Bernat, T. (1994). High Sensitivity of Spirodela Oligorrhiza and Onion to Paclobutrazol. 9th congress of the federation of european societies of plant physiology, brno, czech republic, july 3

- 8, 1994. Biologia plantarum (prague) 36: S385.
Chem Codes : Chemical of Concern: PBZ Code : ABSTRACT.

Saavedra Xandra, Modrego Abelardo, RodriĚ guez Dolores, GonzaĚlez

- GarciĚ a Mary Paz, Sanz Luis, NicolaĚ s Gregorio, and Lorenzo Oscar (2010). The Nuclear Interactor Pyl8/Rcar3 of Fagus Sylvatica Fspp2c1 Is a Positive Regulator of Abscisic Acid Signaling in Seeds and Stress. Plant Physiology, vol. 152, no. 1, pp. 133

- 150,

2010

. Chem Codes : Chemical of Concern: PBZ Code : IN VITRO (NO COC).

Sadhu, B. P. and Gupta, K. (1997). Triazole: a Plant Growth Regulator and a Fungicide. Geobios (jodhpur) 24: 181

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Saze, H., Sasaki, T., and Kakutani, T. (2008). Negative Regulation of Dna Methylation in
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Saze, H., Shiraishi, A., Miura, A., and Kakutani, T. (2008). Control of Genic Dna Methylation by a Jmjc Domain

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Schilter, B., Renwick, A. G., and Huggett, A. C. (1996). Limits for Pesticide Residues in Infant Foods: a Safety Based Proposal. Regulatory toxicology and pharmacology 24:
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Chem Codes : Chemical of Concern: PBZ Code : HUMAN HEALTH.

Shalini, L. and Sharma, D. (2006). Persistence and Movement of Paclobutrazol Residues in a Mango Orchard Soil. Bulletin of Environmental Contamination and Toxicology, 76 (6) pp. 93 0

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. Chem Codes : Chemical of Concern: PBZ Code : FATE.

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Srivastav Manish, Kishor Arun, Dahuja Ani l, and Sharma R.R. (2010). Effect of Paclobutrazol and Salinity on Ion Leakage, Proline Content and Activities of Antioxidant Enzymes in Mango (Mangifera Indica L.). Scientia Horticulturae, vol. 125, no. 4, pp. 785

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. Chem Codes : Chemical of Conc ern: PBZ Code : BENEFICIAL EFFECTS.

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Chem Codes : Chemical of Concern: PBZ Code : NON

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Tokunaga, N., Uchimura, N., and Sato , Y. (2006). Involvement of Gibberellin in Tracheary Element Differentiation and Lignification in Zinnia Elegans Xylogenic Culture. Protoplasma, 228 (4) pp. 179

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. Chem Codes : Chemical of Concern: PBZ Code : IN VITRO.

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. Chem Codes : Chemical of Concern: PBZ Code : NO TOXICANT.

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. Chem Codes : Chemical of Co ncern: PBZ Code : BENEFICIAL EFFECTS.

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. Chem Codes : Chemical of Concern: PBZ Code : IN VITRO.

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. Chem Codes : Chemical of Concern: PBZ Code : NO TOXICANT.

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Chem Codes : Chemical of Concern: PBZ Code : NON

- ENGLISH.

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Chem Codes : Chemical of Concern: PBZ Code : CHEM METHODS.

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Chem Codes : Chemical of Concern: PBZ Cod e : CHEM METHODS.

Zhang Li

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- Yi, Zhu Jia

- Ying, Wang, H. a. o., Wang Wenfei, Zhao, J. u. n., Yang Hongjuan, Xu Yunyuan, Lin Wen

- Hui, Chong Kang, Wanga Zhi

- Yong, Zhang
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- Yong, Wu Jinxia, Zhang Zhiguo, Sun Xuehui, Lu Tiegang,
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. Chem Codes : Chemical of Concern: PBZ Code : NO TOXICANT.

Zhou, Y. C., Noussourou, M., Kon, T., Rojas, M. R., Jiang, H., Chen, L. F., Gamby, K., Foster, R., and Gilbertson, R. L. (2008). Evide nce of Local Evolution of Tomato

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## Appendix F

- Surrogate Chemicals

Paclobutrazol toxicity data were not available for estuarine/marine fish and invertebrates (acute and chronic), freshwater invertebrates (chronic), seedling emergence, vegetative vigor (monocots), honey bees, and aquatic vascular plants. In lieu of these data, the triazole chemical family was examined to identify other triazoles that were similar in structure to paclobutrazol. In all, 13 triazoles were identified; however, four of them (diclobutrazol, ipconazole, penconazole, simeconazol) lacked ecotoxici ty data. Data from the remaining nine were used to construct toxicity distributions for each endpoint gap. Data were analysed in Crystal Ball (2000, version 5.0); first they were fit to a lognormal distribution and then a Monte Carol sampling scheme was implemented with 10,000 trials. Finally, the 5 th
percentile of the simulated distribution curve was calculated and used in lieu of paclobutrazol data in the risk assessment. The structures of the nine triazoles with toxicity data are below.



### Cyproconazol e

Fenbuconazole

Hexaconzole206 

### Metconazole

Mycobutanil

Tebuconazole

Triadimefon207 

### Triadimenol

Triticonazole208 

## Appendix G

– SIP and STIR Model Output

SIP

Table 1. Inputs
Parameter Value
Chemical name Paclobutrazol Solubility (in water at 25 o C; mg/L) 25.9

Mammalian LD 50 (mg/kg

- bw) 1336 Mammalian test species laboratory rat Body weight (g) of "other" mammalian species

Mammalian NOAEL (mg/kg

- bw) 2.5 Mammalian test species laboratory rat Body weight (g) of "other" mammalian species

Avian LD 50 (mg/kg

- bw) 7913 Avian test species mallard duck Body weight (g) of "other" avian species Mineau scaling factor 1.15

Mallard NOAEC (mg/kg

- diet) 995 Bobwhite quail NOAEC (mg/kg

- diet) 453 NOAEC (mg/kg

- diet) for other bird species Body weight (g) of other avian species NOAEC (mg/kg

- diet) for 2nd other bird species Body weight (g) of 2nd other avian species

Table 2. Mammalian Results
Parameter Acute Chronic Upper bound exposure (mg/kg

- bw) 4.4548 4.4548 Adjusted toxicity value (mg/kg

- bw) 1027.5985 1.9229 Ratio of exposure to toxicity 0.0043 2.3167

Conclusion* Drinking water exposure alone is NOT a potential

concern for mammals Exposure through drinking water alone is a

potential concern for mammals

Table 3. Avian Results
Parameter Acute Chronic209 Upper bound exposure (mg/kg

- bw) 20.9790 20.9790 Adjusted toxicity value (mg/kg

- bw) 4108.6307 48.1531 Ratio of exposure to acute toxicity 0.0051 0.4357

Conclusion* Drinking water exposure alone is NOT a potential concern for birds Drinking water exposure alone is NOT a potential concern for birds

*Conclusion is for drinking water exposure alone. This does not combine all routes of exposure. Therefore, when aggregated with other routes ( i.e ., diet, inhalation, dermal), pesticide exposure through drinking water may contribute to a total exposure that has potential for effects to non

- target animals.



### STIR



## Input

Application and Chemical Information

Enter Chemical Name Paclobutrazol Enter Chemical Use Drench Is the Application a Spray? (enter y or n) n If Spray What Type (enter ground or air) ground
Enter Chemical Molecular Weight (g/mole) 293.8 Enter Chemical Vapor Pressure (mmHg) 1.28E

- 09 Enter Application Rate (lb a.i./acre) 6.1

Toxicity Properties

**Bird**
Enter Lowest Bird Oral LD 50 (mg/kg bw) 7913 Enter Mineau Scaling Factor 1.15 Enter Tested Bird Weight (kg) 1.58
**Mammal**
Enter Lowest Rat Oral LD 50 (mg/kg bw) 1336
Enter Lowest Rat Inhalation LC 50 (mg/L) 250 Duration of Rat Inhalation Study (hrs) 4 Enter Rat Weight (kg) 0.35



## Output

Results Avian (0.020 kg ) Maximum Vapor Concentration in Air at Saturation (mg/m 3 ) 2.02E

- 05
Maximum 1

- hour Vapor Inhalation Dose (mg/kg) 2.54E

- 06 Adjusted Inhalation LD 50 5.95E+03

Ratio of Vapor Dose to Adjusted Inhalation LD 50 4.28E

- 10 Exposure not Likely Significant Maximum Post

- treatment Spray Inhalation Dose (mg/kg) not applicable Ratio of Droplet Inhalation Dose to Adjusted Inhalation LD 50 not applicable not applicable210 Results Mammalian (0.015 kg ) Maximum Vapor Concentration in Air at Saturation (mg/m 3 ) 2.02E

- 05
Maximum 1

- hour Vapor Inhalation Dose (mg/kg) 3.20E

- 06 Adjusted Inhalation LD 50 1.49E+04

Ratio of Vapor Dose to Adjusted Inhalation LD 50 2.15E

- 10 Exposure not Likely Significant Maximum Post

- treatment Spray Inhalation Dose (mg/kg) not applicable Ratio of Droplet Inhalation Dose to Adjusted Inhalation LD 50 not applicable not applicable211 

## Appendix H

– Risk Quotient Method and Levels of Concern

The Risk Quotient Method is the means by which the Environmental Fate and Effects Division (EFED) integrates the results of exposure and ecotoxicity data. In this method, both acute and chronic risk quotients are calculated by dividing exposure estimates by the most sensitive ecotoxicit y values derived from the studies. Calculated risk quotients are then compared to OPP's levels of concern. The levels of concern are the criteria used by OPP to indicate potential risk to non

- target organisms and the need to consider regulatory action.
E FED has defined levels of concern for acute risk, potential restricted use, and for listed species. Risk presumptions, along with the corresponding risk quotients and levels of concern are summarized in the table below.



### Levels of Concern for Assessed Taxa

Risk Presumption Risk Quotient Level of Concern

Birds

Acute Risk EEC/LC 50 or LD 50 /sqft or LD 50 /day 0.5

Acute Restricted Use EEC/LC 50 or LD 50 /sqft or LD 50 /day (or LD 50 < 50 mg/kg) 0.2

Acute Listed Species EEC/LC 50 or LD 50 /sqft or LD 50 /day 0.1

Chronic Risk EEC/NOAEC 1

Mammals

Acute Risk EEC/LC 50 or LD 50 /sqft or LD 50 /day 0.5

Acute Restricted Use EEC/LC 50 or LD 50 /sqft or LD 50 /day (or LD 50 < 50 mg/kg) 0.2

Acute Listed Species EEC/LC 50 or LD 50 /sqft or LD 50 /day 0.1

Chronic Risk EEC/NOAEC 1

Aquatic Animals

Acute Risk EEC/LC 50 or EC 50 0.5

Acute Restricted Use EEC/LC 50 or EC 50 0.1

Acute Listed Species EEC/LC 50 or EC 50 0.05

Chronic Risk EEC/NOAEC 1

Terrestrial and Semi

- Aquatic Plants

Acute Risk EEC/EC 25 1212 Risk Presumption Risk Quotient Level of Concern

Acute Listed Species EEC/EC 05 or NOAEC 1

Aquatic Plants

Acute Risk EEC/EC 50 1

Acute Listed Species EEC/EC 05 or NOAEC 1213 

## Appendix I

– Surface Water Model Results and Sample Input and Outputs

Range of estimated environmental concentrations (EECs) of total residue (paclobutrazol plus degradates) and paclobutrazol for surface water

Month California Florida Michigan New Jersey Oregon Tennessee Estimated Exposure Concentrations (μg/L) based on total toxic residue 1 and 2.5 lbs/Acre application rate 2

Peak 21

- day 60

- Day Peak 21

- day 60

- Day Peak 21

- day 60

- Day Peak 21

- day 60

- Day Peak 21

- day 60

- Day Peak 21

- day 60

- Day April 12.7 12.7 12.5 156 155 154 198 197 197 143 143 142 52 52 52 187.4 186.5 185.6 May 8.1 8.0 8.0 260 260 258 211 211 210 145 145 144 68 68 68 169.8 168.9 168.8
June 0.04 0.04 0.04 333 332 331 208 208 207 169 169 168 92 92 92 144.0 143.0 142.9 July 0.3 0.3 0.3 146 145 140 200 199 199 180 180 179 97 97 97 179.3 179.3 178.4 August 3.5 3.5 3.5 212 211 208 239 238 237 219 218 218 103 103 103 172.8 171.8 171.7 September 7.2 7.2 7.1 207 206 205 301 301 300 257 256 255 96 96 96 255.0 254.0 253.0 Estimated Exposure Concentrations (μg/L) based on total toxic residue and 0.57lbs/Acre application rate 3 April 2.8 2.8 2.8 34 34 34 44 44 44 32 32 32 12 12 11 41.4 41.3 41.1 May 1.8 1.8 1.8 58 57 57 47 47 46 32 32 32 15 15 15 37.5 37.4 37.3
June 0.01 0.01 0.01 74 74 73 46 46 46 37 37 37 20 20 20 31.9 31.8 31.6 July 0.1 0.1 0.1 32 32 32 44 44 44 40 40 40 21 21 21 39.8 39.6 39.4 August 0.8 0.8 0.8 47 47 46 53 53 52 48 48 48 23 23 23 38.2 38.1 38.0 September 1.6 1.6 1.6 46 46 45 67 67 66 57 57 57 21 21 21 56.4 56.3 56.0 Estimated Exposure Concentrations (μg/L) based on parent (paclobutrazon) only and 2.50 lbs/Acre application rate 4

June 4 187 184 183 NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA

1 Paclobutrazol plus its major degradates, CGA 149907 and NOA 457654

2 Application rate estimated based on minimum amount of parent retention (58.6 %)in a column leaching study (MRID 40685004)

3 Application rate estimated based on maximum amount of parent retention (90.7 %)in a column leaching study (MRID 0685004)

4 Exposure of parent only based on highest exposure scenario identified from total toxic residue simulations NA Not Analyzed Red high

- lighted values ar e the highest exposure for nursery scenario Green high

- lighted values are the lowest exposure for nursery scenario214 

### Sample Input and Output of PRZM/EXAMS: FL Ornamental

stored as FL_NURS_H_01

- 04_01

- 06.out

Chemical: Paclobutrazol

PRZM environme

nt: FLnursery STD_V2.t

xt modified Tueday, 27 May 2008 at 11:22:34

EXAMS environme

nt: pond298.e

xv modified Tueday, 26 August 2008 at 06:14:08

Metfile: w12839.dv f modified Tueday, 26 August 2008 at 06:14:20

Water segment concentrations (ppb)

Year Peak 96 hr 21 Day 60 Day 90 Day Yearly

1961 36.9 36.8 36.4 35.7 35.0 18.8

1962 56.7 56.5 56.0 55.0 54.3 42.7

1963 57.9 57.8 57.6 57.3 56.9 53.0

1964 117.0 117.0 116.0 113.0 111.0 84.0

1965 119.0 119.0 118.0 117.0 116.0 108.0

1966 161.0 160.0 159.0 157.0 155.0 133.0

1967 195.0 195.0 193.0 191.0 189.0 165.0

1968 222.0 222.0 221.0 218.0 217.0 195.0

1969 231.0 231.0 230.0 228.0 227.0 212.0

1970 217.0 217.0 217.0 215.0 214.0 210.0

1971 226.0 225.0 225.0 223.0 221.0 209.0

1972 255.0 255.0 253.0 250.0 248.0 226.0

1973 242.0 242.0 241.0 240.0 239.0 232.0

1974 294.0 294.0 292.0 288.0 285.0 254.0

1975 266.0 266.0 265.0 264.0 263.0 256.0

1976 263.0 263.0 263.0 260.0 259.0 248.0

1977 410.0 409.0 405.0 398.0 393.0 322.0

1978 362.0 361.0 361.0 359.0 358.0 350.0

1979 335.0 335.0 334.0 333.0 332.0 325.0

1980 312.0 312.0 311.0 310.0 309.0 301.0

1981 288.0 288.0 287.0 286.0 285.0 280.0

1982 298.0 297.0 296.0 295.0 293.0 277.0

1983 316.0 316.0 315.0 311.0 309.0 288.0

1984 295.0 295.0 294.0 292.0 290.0 285.0

1985 276.0 276.0 276.0 275.0 274.0 267.0215 1986 287.0 287.0 285.0 283.0 281.0 265.0

1987 264.0 264.0 263.0 262.0 261.0 256.0

1988 288.0 288.0 286.0 283.0 281.0 260.0

1989 275.0 275.0 274.0 273.0 271.0 262.0

1990 257.0 257.0 256.0 255.0 254.0 249.0

Sorted results

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

0.03 410.0 409.0 405.0 398.0 393.0 350.0

0.06 362.0 361.0 361.0 359.0 358.0 325.0

0.10 335.0 335.0 334.0 333.0 332.0 322.0

0.13 316.0 316.0 315.0 311.0 309.0 301.0

0.16 312.0 312.0 311.0 310.0 309.0 288.0

0.19 298.0 297.0 296.0 295.0 293.0 285.0

0.23 295.0 295.0 294.0 292.0 290.0 280.0

0.26 294.0 294.0 292.0 288.0 285.0 277.0

0.29 288.0 288.0 287.0 286.0 285.0 267.0

0.32 288.0 288.0 286.0 283.0 281.0 265.0

0.35 287.0 287.0 285.0 283.0 281.0 262.0

0.39 276.0 276.0 276.0 275.0 274.0 260.0

0.42 275.0 275.0 274.0 273.0 271.0 256.0

0.45 266.0 266.0 265.0 264.0 263.0 256.0

0.48 264.0 264.0 263.0 262.0 261.0 254.0

0.52 263.0 263.0 263.0 260.0 259.0 249.0

0.55 257.0 257.0 256.0 255.0 254.0 248.0

0.58 255.0 255.0 253.0 250.0 248.0 232.0

0.61 242.0 242.0 241.0 240.0 239.0 226.0

0.65 231.0 231.0 230.0 228.0 227.0 212.0

0.68 226.0 225.0 225.0 223.0 221.0 210.0

0.71 222.0 222.0 221.0 218.0 217.0 209.0

0.74 217.0 217.0 217.0 215.0 214.0 195.0

0.77 195.0 195.0 193.0 191.0 189.0 165.0

0.81 161.0 160.0 159.0 157.0 155.0 133.0

0.84 119.0 119.0 118.0 117.0 116.0 108.0

0.87 117.0 117.0 116.0 113.0 111.0 84.0

0.90 57.9 57.8 57.6 57.3 56.9 53.0

0.94 56.7 56.5 56.0 55.0 54.3 42.7

0.97 36.9 36.8 36.4 35.7 35.0 18.8

0.1 333.1 333.1 332.1 330.8 329.7 319.9
Average of

yearly

averages: 221.1

Inputs generated by pe5.pl

- Novemeber 2006216 Data used for this run:
Output File: FL_NURS_H_01

- 04_01

- 06

Metfile: w12839.dvf

PRZM scenario: FLnurserySTD_V2.txt

EXAMS environme nt file: pond298.exv

Chemical
Name: Paclobutrazol

Descriptio

n Variable
Name Value Units Comments

Molecular weight mwt 293.8 g/mol

Henry's
Law Const. henry 8.09E

- 12 atm

- m^3/mol

Vapor
Pressure vapr 1.28E

- 09 torr

Solubility sol 25.9 mg/L

Kd Kd 4.5 mg/L

Koc Koc mg/L
Photolysis half

- life kdp 0 days Half

- life

Aerobic Aquatic Metabolis

m kbacw 2006.4 days Halfife

Anaerobic Aquatic Metabolis

m kbacs 0 days Halfife

Aerobic Soil Metabolis

m asm 1003.2 days Halfife

Hydrolysis

: pH 7 0 days Half

- life

Method: CAM 1 integer See PRZM manual
Incorporati on Depth: DEPI 0 cm

Applicatio
n Rate: TAPP 2.8 kg/ha

Applicatio

n Efficiency: APPEFF 1 fraction

Spray Drift DRFT 0 fraction of application rate applied to pond
Applicatio

n Date Date 6

- Jan dd/mm or dd/mmm or dd

- mm or dd

- mmm

Record 17: FILTRA

IPSCND 1

UPTKF

Record 18: PLVKRT

PLDKRT

FEXTRC 0.5217 Flag for Index Res.
Run IR EPA Pond

Flag for runoff calc. RUNOFF none none, monthly or total(average of entire run)218 

## Appendix J

– TerrPlant Output

Profile 2SC on Turf

– 1 ground application at 0.75 lb ai/A

Chemical Identity.

Parameter User Inputs

Chemical Name Paclobutrazol
PC code 125601
Use Turf Application Method Broadcast

Application Form liquid Solubility in Water (ppm) 27

Input parameters used to derive EECs.

Input Parameter Symbol Value (user inputs) Units
Application Rate A 0.75

Incorporation I 1 none Runoff Fraction R 0.02 none

Drift Fraction D 0.01 none

EECs for Paclobutrazol.
Description Equation EEC Runoff to dry areas (A/I)*R 0.015
Runoff to semi

- aquatic areas (A/I)*R*10 0.15 Spray drift A*D 0.0075 Total for dry areas ((A/I)*R)+(A*D) 0.0225
Total for semi

- aquatic areas ((A/I)*R*10)+(A*D) 0.1575

Plant survival and growth data used for RQ derivation. Seedling Emergence Vegetative Vigor Plant type EC 25 NOAEC EC 25 NOAEC

Monocot x 0.071 x 0.059

Dicot 0.009 0.002 0.032 x219 RQ values for plants in dry and semi

- aquatic areas exposed to Paclobutrazol through runoff and/or spray drift.*
Plant Type Listed Status Dry Semi

- Aquatic Spray Drift

Monocot non

- listed N/A N/A N/A
Monocot listed 0.32 2.22 0.13

Dicot non

- listed 2.50 17.50 0.83
Dicot listed 11.25 78.75 3.75
*If RQ > 1.0, the LOC is exceeded, resulting in potential for risk to that plant group.



### Paclobutrazol 2SC Soil Injection /Basal Drench for Ornamental Trees

– 1 application at 3 inches deep at 1.9 lb ai/A

Chemical Identity.

Parameter User Inputs

Chemical Name Paclobutrazol
PC code 125601
Use Ornamental Tree Application Method Soil Injection /Basal Drench

Application Form liquid Solubility in Water (ppm) 27

Input parameters used to derive EECs.

Input Parameter Symbol Value (user inputs) Units
Application Rate A 1.9

Incorporation I 3 none Runoff Fraction R 0.02 none

Drift Fraction D 0 none

EECs for Paclobutrazol.
Description Equation EEC
Runoff to dry areas (A/I)*R 0.012666667
Runoff to semi

- aquatic areas (A/I)*R*10 0.126666667 Spray drift A*D 0 Total for dry areas ((A/I)*R)+(A*D) 0.012666667
Total for semi

- aquatic areas ((A/I)*R*10)+(A*D) 0.126666667220 Plant survival and growth data used for RQ derivation. Seedling Emergence Vegetative Vigor Plant type EC 25 NOAEC EC 25 NOAEC

Monocot x 0.071 x 0.059

Dicot 0.009 0.002 0.032 x

RQ values for plants in dry and semi

- aquatic areas exposed to Paclobutrazol through runoff and/or spray drift.*
Plant Type Listed Status Dry Semi

- Aquatic Spray Drift

Monocot non

- listed N/A N/A N/A
Monocot listed 0.18 1.78 <0.1

Dicot non

- listed 1.41 14.07 <0.1
Dicot listed 6.33 63.33 <0.1 *If RQ > 1.0, the LOC is exceeded, resulting in potential for risk to that plant group.



### Paclobutrazol 2SC Seed Treatment for Cucurbits

– 1 application at 3 inches deep at 0.00029 lb ai/A

Chemical Identity.

Parameter User Inputs

Chemical Name Paclobutrazol
PC code 125601
Use Cucurbits Application Method Seed Treatment

Application Form liquid Solubility in Water (ppm) 27

Input parameters used to derive EECs.

Input Parameter Symbol Value (user inputs) Units
Application Rate A 0.00029

Incorporation I 3 none Runoff Fraction R 0.02 none

Drift Fraction D 0 none221 EECs for Paclobutrazol.
Description Equation EEC Runoff to dry areas (A/I)*R 0.000001 9
Runoff to semi

- aquatic areas (A/I)*R*10 0.00001 9 Spray drift A*D 0 Total for dry areas ((A/I)*R)+(A*D) 0.000001 9
Total for semi

- aquatic areas ((A/I)*R*10)+(A*D) 0.00001 9

Plant survival and growth data used for RQ derivation. Seedling Emergence Vegetative Vigor Plant type EC 25 NOAEC EC 25 NOAEC

Monocot x 0.071 x 0.059

Dicot 0.009 0.002 0.032 x

RQ values for plants in dry and semi

- aquatic areas exposed to Paclobutrazol through runoff and/or spray drift.*
Plant Type Listed Status Dry Semi

- Aquatic Spray Drift

Monocot non

- listed N/A N/A N/A
Monocot listed <0.1 <0.1 <0.1

Dicot non

- listed <0.1 <0.1 <0.1
Dicot listed <0.1 <0.1 <0.1
*If RQ > 1.0, the LOC is exceeded, resulting in potential for risk to that plant group.



### Paclobutrazol 2SC Seed Treatment for Pepper

– 1 application at 3 inches deep at 0.00079 lb ai/A

Chemical Identity.

Parameter User Inputs

Chemical Name Paclobutrazol
PC code 125601
Use Pepper Application Method Seed Treatment

Application Form liquid Solubility in Water (ppm) 27

Input parameters used to derive EECs.

Input Parameter Symbol Value (user inputs) Units
Application Rate A 0.00079

Incorporation I 3 none Runoff Fraction R 0.02 none222 Drift Fraction D 0 none

EECs for Paclobutrazol.
Description Equation EEC Runoff to dry areas (A/I)*R 0.0000053
Runoff to semi

- aquatic areas (A/I)*R*10 0.000053 Spray drift A*D 0 Total for dry areas ((A/I)*R)+(A*D) 0.0000053
Total for semi

- aquatic areas ((A/I)*R*10)+(A*D) 0.000053

Plant survival and growth data used for RQ derivation. Seedling Emergence Vegetative Vigor Plant type EC 25 NOAEC EC 25 NOAEC

Monocot x 0.071 x 0.059

Dicot 0.009 0.002 0.032 x

RQ values for plants in dry and semi

- aquatic areas exposed to Paclobutrazol through runoff and/or spray drift.*
Plant Type Listed Status Dry Semi

- Aquatic Spray Drift

Monocot non

- listed N/A N/A N/A
Monocot listed <0.1 <0.1 <0.1

Dicot non

- listed <0.1 <0.1 <0.1
Dicot listed <0.1 <0.1 <0.1 *If RQ > 1.0, the LOC is exceeded, resulting in potential for risk to that plant group.



### Paclobutrazol 2SC Seed Treatment for Tomato

– 1 application at 3 inches deep at 0.00040 lb ai/A

Chemical Identity.

Parameter User Inputs

Chemical Name Paclobutrazol
PC code 125601
Use Tomato Application Method Seed Treatment

Application Form liquid Solubility in Water (ppm) 27223 Input parameters used to derive EECs.

Input Parameter Symbol Value (user inputs) Units
Application Rate A 0.0004

Incorporation I 3 none Runoff Fraction R 0.02 none

Drift Fraction D 0 none

EECs for Paclobutrazol.
Description Equation EEC Runoff to dry areas (A/I)*R 0.0000027
Runoff to semi

- aquatic areas (A/I)*R*10 0.000027 Spray drift A*D 0 Total for dry areas ((A/I)*R)+(A*D) 0.0000027
Total for semi

- aquatic areas ((A/I)*R*10)+(A*D) 0.000027

Plant survival and growth data used for RQ derivation. Seedling Emergence Vegetative Vigor Plant type EC 25 NOAEC EC 25 NOAEC

Monocot x 0.071 x 0.059

Dicot 0.009 0.002 0.032 x

RQ values for plants in dry and semi

- aquatic areas exposed to Paclobutrazol through runoff and/or spray drift.*
Plant Type Listed Status Dry Semi

- Aquatic Spray Drift

Monocot non

- listed N/A N/A N/A
Monocot listed <0.1 <0.1 <0.1

Dicot non

- listed <0.1 < 0.1 <0.1
Dicot listed <0.1 <0.1 <0.1
*If RQ > 1.0, the LOC is exceeded, resulting in potential for risk to that plant group.224 

### Paclobutraz ol 2SC Seed Treatment for Broccoli

– 1 application at 3 inches deep at 0.000096 lb ai/A

Parameter User Inputs

Chemical Name Paclobutrazol
PC code 125601
Use Broccoli Application Method Seed treatment

Application Form liquid Solubility in Water (ppm) 27

Input parameters used to derive EECs.

Input Parameter Symbol Value (user inputs) Units
Application Rate A 0.000096

Incorporation I 3 none Runoff Fraction R 0.02 none

Drift Fraction D 0 none

EECs f or Paclobutrazol.
Description Equation EEC
Runoff to dry areas (A/I)*R 0.00000064
Runoff to semi

- aquatic areas (A/I)*R*10 0.0000064 Spray drift A*D 0 Total for dry areas ((A/I)*R)+(A*D) 0.00000064
Total for semi

- aquatic areas ((A/I)*R*10)+(A*D) 0.0000064

Plant survival and growth data used for RQ derivation

. Seedling Emergence Vegetative Vigor Plant type EC 25 NOAEC EC 25 NOAEC

Monocot x 0.071 x 0.059

Dicot 0.009 0.002 0.032 x

RQ values for plants in dry and semi

- aquatic areas exposed to Paclobutrazol through runoff and/or spray drift.*

Plant Type Listed Status Dry Semi

- Aquatic Spray Drift

Monocot non

- listed #VALUE! #VALUE! #DIV/0!
Monocot listed <0.1 <0.1 <0.1

Dicot non

- listed <0.1 <0.1 <0.1
Dicot listed <0.1 <0.1 <0.1 *If RQ > 1.0, the LOC is exceeded, resulting in potential for risk to that plant group.225 

### Paclobutrazol 2SC Seed Treatment for Cauliflower

– 1 application at 3 inches deep at 0.000064 lb ai/A

Parameter User Inputs

Chemical Name Paclobutrazol
PC code 125601
Use Broccoli Application Method Seed treatment

Application Form liquid Solubility in Water (ppm) 27

Input parameters used to derive EECs.

Input Parameter Symbol Value (user inputs) Units
Application Rate A 0.000064

Incorporation I 3 none Runoff Fraction R 0.02 none

Drift Fraction D 0 none

EECs for Paclobutrazol.
Description Equation EEC
Runoff to dry areas (A/I)*R 4.26667E

- 07
Runoff to semi

- aquatic areas (A/I)*R*10 4.26667E

- 06 Spray drift A*D 0 Total for dry areas ((A/I)*R)+(A*D) 4.26667E

- 07
Total for semi

- aquatic areas ((A/I)*R*10)+(A*D) 4.26667E

- 06

Plant survival and growth data used for RQ derivation. Seedling Emergence Vegetative Vigor Plant type EC 25 NOAEC EC 25 NOAEC

Monocot x 0.071 x 0.059

Dicot 0.009 0.002 0.032 x

RQ values for plants in dry and semi

- aquatic areas exposed to Paclobutrazol through runoff and/or spray drift.*

Plant Type Listed Status Dry Semi

- Aquatic Spray Drift

Monocot non

- listed #VALUE! #VALUE! #DIV/0!
Monocot listed <0.1 <0.1 <0.1

Dicot non

- listed <0.1 <0.1 <0.1
Dicot listed <0.1 <0.1 <0.1 *If RQ > 1.0, the LOC is exceeded, resulting in potential for risk to that plant group.226 

### Paclobutrazol 2SC Seed Treatment for Cabbage

– 1 application at 3 inches deep at 0.00012 lb ai/A

Parameter User Inputs

Chemical Name Paclobutrazol
PC code 125601
Use Broccoli Application Method Seed treatment

Application Form liquid Solubility in Water (ppm) 27

Input parameters used to derive EECs.

Input Parameter Symbol Value (user inputs) Units
Application Rate A 0.00012

Incorporation I 3 none Runoff Fraction R 0.02 none

Drift Fraction D 0 none

EECs for Paclobutrazol.
Description Equation EEC Runoff to dry areas (A/I)*R 0.0000008
Runoff to semi

- aquatic areas (A/I)*R*10 0.000008 Spray drift A*D 0 Total for dry areas ((A/I)*R)+(A*D) 0.0000008
Total for semi

- aquatic areas ((A/I)*R*10)+(A*D) 0.000008

Plant survival and growth data used for RQ derivation. Seedling Emergence Vegetative Vigor Plant type EC 25 NOAEC EC 25 NOAEC

Monocot x 0.071 x 0.059

Dicot 0.009 0.002 0.032 x

RQ values for plants in dry and semi

- aquatic areas exposed to Paclobutrazol through runoff and/or spray drift.*

Plant Type Listed Status Dry Semi

- Aquatic Spray Drift

Monocot non

- listed #VALUE! #VALUE! #DIV/0!
Monocot listed <0.1 <0.1 <0.1

Dicot non

- listed <0.1 <0.1 <0.1
Dicot listed <0.1 <0.1 <0.1

*If RQ > 1.0, the LOC is exceeded, resulting in potential for risk to that plant group.227 

### Bonzi II Spray for Potted Ornamentals for Transplant

– 1 application at 0.26 lb ai/A

Chemical Identity.

Parameter User Inputs

Chemical Name Paclobutrazol
PC code 125601
Use Ornamental Potted Plants for Transplant Application Method Spray

Application Form liquid Solubility in Water (ppm) 27

Input parameters used to derive EECs.

Input Parameter Symbol Value (user inputs) Units
Application Rate A 0.26

Incorporation I 1 none Runoff Fraction R 0.02 none

Drift Fraction D 0 none

EECs for Paclobutrazol.
Description Equation EEC Runoff to dry areas (A/I)*R 0.0052
Runoff to semi

- aquatic areas (A/I)*R*10 0.052 Spray drift A*D 0 Total for dry areas ((A/I)*R)+(A*D) 0.0052
Total for semi

- aquatic areas ((A/I)*R*10)+(A*D) 0.052

Plant survival and growth data used for RQ derivation. Seedling Emergence Vegetative Vigor
Plant type EC 25 NOAEC EC 25 NOAEC

Monocot x 0.071 x 0.059

Dicot 0.009 0.002 0.032 x

RQ values for plants in dry and semi

- aquatic areas exposed to Paclobutrazol through runoff and/or spray drift.*
Plant Type Listed Status Dry Semi

- Aquatic Spray Drift

Monocot non

- listed N/A N/A N/A
Monocot listed <0.1 0.73 <0.1

Dicot non

- listed 0.58 5.78 <0.1
Dicot listed 2.60 26.00 <0.1
*If RQ > 1.0, the LOC is exceeded, resulting in potential for risk to that plant group.228 

### Bonzi II Spray for Potted Ornamentals for Transplant

– 1 application at 6.1 lb ai/A

Chemical Identity.

Parameter User Inputs

Chemical Name Paclobutrazol
PC code 125601
Use Ornamental Potted Plants for Transplant Application Method Drench

Application Form liquid Solubility in Water (ppm) 27

Input parameters used to derive EECs.

Input Parameter Symbol Value (user inputs) Units
Application Rate A 6.1

Incorporation I 1 none Runoff Fraction R 0.02 none

Drift Fraction D 0 none

EECs for Paclobutrazol.
Description Equation EEC Runoff to dry areas (A/I)*R 0.122
Runoff to semi

- aquatic areas (A/I)*R*10 1.22 Spray drift A*D 0 Total for dry areas ((A/I)*R)+(A*D) 0.122
Total for semi

- aquatic areas ((A/I)*R*10)+(A*D) 1.22

Plant survival and growth data used for RQ derivation. Seedling Emergence Vegetative Vigor Plant type EC 25 NOAEC EC 25 NOAEC

Monocot x 0.071 x 0.059

Dicot 0.009 0.002 0.032 x229 RQ values for plants in dry and semi

- aquatic areas exposed to Paclobutrazol through runoff and/or spray drift.*
Plant Type Listed Status Dry Semi

- Aquatic Spray Drift

Monocot non

- listed N/A N/A N/A
Monocot listed 1.72 17.18 <0.1

Dicot non

- listed 13.56 135.56 <0.1
Dicot listed 61.00 610.00 <0.1
*If RQ > 1.0, the LOC is exceeded, resulting in potential for risk to that plant group.230 

## Appendix K

– Terrestrial EEC Calculations

Profile 2SC on Turf

– 3 applications at 0.75 lb ai/A (28 day interval) (T

REX)

Upper Bound Kenaga, Acute Avian Dose

- Based Risk Quotients

Size Class (grams) Adjusted LD50 EECs and RQs

Short Grass Tall Grass Broadleaf Plants/ Small Insects Fruits/Pods/ Seeds/ Large Insects Granivore

EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ

20 0.00 390.37 N/A 178.92 N/A 219.58 N/A 24.40 N/A 5.42 N/A

100 0.00 222.61 N/A 102.03 N/A 125.22 N/A 13.91 N/A 3.09 N/A

1000 0.00 99.66 N/A 45.68 N/A 56.06 N/A 6.23 N/A 1.38 N/A

Upper Bound Kenaga, Subacute Avian Dietary Based Risk Quotients

LC50 EECs and RQs

Short Grass Tall Grass Broadleaf Plants/ Small Insects Fruits/Pods/ Seeds/ Large Insects

EEC RQ EEC RQ EEC RQ EEC RQ

0 342.76 N/A 157.10 N/A 192.80 N/A 21.42 N/A

Size class not used for dietary risk quotients231 Upper Bound Kenaga, Chronic Avian Dietary Based Risk Quotients

NOAEC (ppm) EECs and RQs

Short Grass Tall Grass Broadleaf Plants/ Small Insects Fruits/Pods/ Seeds/ Large Insects

EEC RQ EEC RQ EEC RQ EEC RQ

435 342.76 0.79 157.10 0.36 192.80 0.44 21.42 0.05

Size class not used for dietary risk quotients

Upper Bound Kenaga, Acute Mammalian Dose

- Based Risk Quotients

Size Class (grams) Adjusted LD50 EECs and RQs

Short Grass Tall Grass Broadleaf Plants/ Small Insects Fruits/Pods/ Seeds/ Large Insects Granivore

EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ

15 29 36.30 326.80 0.11 149.78 0.05 183.82 0.06 20.42 0.01 4.54 <0.01

35 2375.78 225.86 0.10 103.52 0.04 127.05 0.05 14.12 0.01 3.14 <0.01

1000 1027.60 52.37 0.05 24.00 0.02 29.46 0.03 3.27 <0.01 0.73 <0.01

Upper Bound Kenaga, Acute Mammalian Dietary Based Risk Quotients

LC50 (ppm) EECs and RQs

Short Grass Tall Grass Broadleaf Plants/ Small Insects Fruits/Pods/ Seeds/ Large Insects

EEC RQ EEC RQ EEC RQ EEC RQ

0 342.76 N/A 157.10 N/A 192.80 N/A 21.42 N/A

Size class not used for dietary risk quotients232 Upper Bound Kenaga, Chronic Mammalian Dietary Based Risk Quotients

NOAEC (ppm) EECs and RQs

Short Grass Tall Grass Broadleaf Plants/ Small Insects Fruits/Pods/ Seeds/ Large Insects

EEC RQ EEC RQ EEC RQ EEC RQ

50 342.76 6.86 157.10 3.14 192.80 3.86 21.42 0.43 Size class not used for dietary risk quotients

Upper Bound Kenaga, Chronic Mammalian Dose

- Based Risk Quotients

Size Class (grams) Adjusted NOAEL EECs and RQs

Short Grass Tall Grass Broadleaf Plants/ Small Insects Fruits/Pods/ Seeds/ Large Insects Granivore

EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ

15 5. 49 326.80 59.48 149.78 27.26 183.82 33.46 20.42 3.72 4.54 0.83

35 4.45 225.86 50.80 103.52 23.29 127.05 28.58 14.12 3.18 3.14 0.71

1000 1.92 52.37 27.23 24.00 12.48 29.46 15.32 3.27 1.70 0.73 0.38



### Bonzi II Spray for Potted Ornamentals

– 1 application at 0.26 lb ai/A (T

REX)

Upper Bound Kenaga, Acute Avian Dose

- Based Risk Quotients

Size Class (grams) Adjusted LD50 EECs and RQs

Short Grass Tall Grass Broadleaf Plants/ Small Insects Fruits/Pods/ Seeds/ Large Insects Granivore

EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ

20 0.00 71.07 N/A 32.57 N/A 39.98 N/A 4.44 N/A 0.99 N/A

100 0.00 40.53 N/A 18.57 N/A 22.80 N/A 2.53 N/A 0.56 N/A

1 000 0.00 18.14 N/A 8.32 N/A 10.21 N/A 1.13 N/A 0.25 N/A233 Upper Bound Kenaga, Subacute Avian Dietary Based Risk Quotients

LC50 EECs and RQs

Short Grass Tall Grass Broadleaf Plants/ Small Insects Fruits/Pods/ Seeds/ Large Insects

EEC RQ EEC RQ EEC RQ EEC RQ
0 62.40 N/A 28.60 N/A 35.10 N/A 3.90 N/A

Size class not used for dietary risk quotients

Upper Bound Kenaga, Chronic Avian Dietary Based Risk Quotients

NOAEC (ppm) EECs and RQs

Short Grass Tall Grass Broadleaf Plants/ Small Insects Fruits/Pods/ Seeds/ Large Insects

EEC RQ EEC RQ EEC RQ EEC RQ

435 62.40 0.14 28.60 0.07 35.10 0.08 3.90 0.01
Size class not used for dietary risk quotients

Upper Bound Kenaga, Acute Mammalian Dose

- Based Risk Quotients

Size Class (grams) Adjusted LD50 EECs and RQs

Short Grass Tall Grass Broadleaf Plants/ Small Insects Fruits/Pods/ Seeds/ Large Insects Granivore

EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ
15 2936.30 59.49 0.02 27.27 0.01 33.47 0.01 3.72 <0.01 0.83 <0.01
35 2375.78 41.12 0.02 18.85 0.01 23.13 0.01 2.57 <0.01 0.57 <0.01
1000 1027.60 9.53 0.01 4.37 <0.01 5.36 0.01 0.60 <0.01 0.13 <0.01234 Upper Bound Kenaga, Acute Mammalian Dietary Based Risk Quotients

LC50 (ppm) EECs and RQs

Short Grass Tall Grass Broadleaf Plants/ Small Insects Fruits/Pods/ Seeds/ Large Insects

EEC RQ EEC RQ EEC RQ EEC RQ

0 62.40 N/A 28.60 N/A 35.10 N/A 3.90 N/A

Size class not used for dietary risk quotients

Upper Bound Kenaga, Chronic Mammalian Dietary Based Risk Quotients

NOAEC (ppm) EECs and RQs

Short Grass Tall Grass Broadleaf Plants/ Small Insects Fruits/Pods/ Seeds/ Large Insects
EEC RQ EEC RQ EEC RQ EEC RQ
50 62.40 1.25 28.60 0.57 35.10 0.70 3.90 0.08 Size class not used for dietary risk quotients

Upper Bound Kenaga, Chronic Mammalian Dose

- Based Risk Quotients

Size Class (grams) Adjusted NOAEL EECs and RQs

Short Grass Tall Grass Broadleaf Plants/ Small Insects Fruits/Pods/ Seeds/ Large Insects Granivore

EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ
15 5.49 59.49 10.83 27.27 4.96 33.47 6.09 3.72 0.68 0.83 0.15
35 4.45 41.12 9.25 18.85 4.24 23.13 5.20 2.57 0.58 0.57 0.13

1000 1.92 9.53 4.96 4.37 2.27 5.36 2.79 0.60 0.31 0.13 0.07



### Clipper 20 UL Ornamental Tree Injection

– 1 application at 0.36 lb ai/A

Risk Quotient = EEC / Toxicological Value

Birds

The following definitive data are available for birds:
NOAEC = 453 mg/kg

- diet235 Chronic Dietary Risk Quotients = EEC/NOAEC Hardwoods = (212 mg ai/kg

- leaves) / (453 mg ai/kg

- diet) = 0.47 Softwoods = (9.4 mg ai/kg

- leaves) / (453 mg ai/kg

- diet) = 0.02

Mammals

The following definitive data are available for mammals:

L D 50 = 1336 mg/kg

- bw NOEL = 2.5 mg/kg

- bw

Adjusted toxicity values were calculated for mammal size classes by T

- REX 15 g mammal LD 50 = 2936 mg/kg

- bw 35 g mammal LD 50 = 2376 mg/kg

- bw 1000 g mammal LD 50 = 1028 mg/kg

- bw 15 g mammal NOEL = 5.49 mg/kg

- bw 35 g mammal NOEL = 4.45 mg/kg

- bw 1000 g mammal NOEL = 1.92 mg/kg

- bw

Acute Dose

- Based Risk Quotients = EEC/LD 50

Hardwoods 15 g mammal = ( 201 mg ai/kg

- bw) / (2936 mg ai/kg

- bw) = 0.07 35 g mammal = ( 140 mg ai/kg

- bw) / (2376 mg ai/kg

- bw) = 0.06 1000g mammal = (3 2 mg ai/kg

- bw) / (1028 mg/kg

- bw) = 0 .03

Softwoods 15 g mammal = ( 9 mg ai/kg

- bw) / (2936 mg ai/kg

- bw) = 0.003 35 g mammal = ( 4.2 mg ai/kg

- bw) / (2376 mg ai/kg

- bw) = 0. 001

1 000 g mammal = (1.4 mg ai/kg

- bw) / (1028 mg/kg

- bw) = 0. 001

Chronic Dose

- Based Risk Quotients = EEC/NOEL

Hardwoods 15 g mammal = (201 mg ai/kg

- bw) / (5.49 mg ai/kg

- bw) = 37 35 g mammal = (140 mg ai/kg

- bw) / (4.45 mg ai/kg

- bw) = 31 1000 g mammal = (32 mg ai/kg

- bw) / (1.92 mg ai/kg

- bw) = 17

Softwoods 15 g mammal = (9 mg ai/kg

- bw) / (5.49 mg ai/kg

- bw) = 1.6236 35 g mammal = (4.2 mg ai/kg

- bw) / (4.45 mg ai/kg

- bw) = 0.94 1000g mammal = (1.4 mg ai/kg

- bw) / (1.92 mg ai/kg

- bw) = 0.73



### Paclobutrazol 2SC Soil Injection /Basal Drench for Ornamental Trees

– 1 application at 1.9 lb ai/A

Risk Quotient = EEC / Toxicological Value

Birds

The following definitive data are available for birds: NOAEC = 453 mg/kg

- diet

Chronic Dietary Risk Quotients = EEC/NOAEC Hardwoods = (1058 mg ai/kg

- lea ves) / (453 mg ai/kg

- diet) = 2.3 Softwoods = (483 mg ai/kg

- leaves) / (453 mg ai/kg

- diet) = 1.1

Mammals

The following definitive data are available for mammals:

LD 50 = 1336 mg/kg

- bw NOEL = 2.5 mg/kg

- bw

Adjusted toxicity values were calculated for mammal size classes by T

- REX 15 g mammal LD 50 = 2936 mg/kg

- bw 35 g mammal LD 50 = 2376 mg/kg

- bw 1000 g mammal LD 50 = 1028 mg/kg

- bw 15 g mammal NOEL = 5.49 mg/kg

- bw 35 g mammal NOEL = 4.45 mg/kg

- bw 1000 g mammal NOEL = 1.92 mg/kg

- bw

Acute Dose

- Based Risk Quotients = EEC/LD 50

Hardwoods 15 g mammal = (1005 mg ai/kg

- bw) / (2936 mg ai/kg

- bw) = 0.34 35 g mammal = (698 mg ai/kg

- bw) / (2376 mg ai/kg

- bw) = 0.29 1000g mammal = (159 mg ai/kg

- bw) / (1028 mg/kg

- bw) = 0. 15

Softwoods 15 g mammal = (459 mg ai/kg

- bw) / (2936 mg ai/kg

- bw) = 0.16237 35 g mammal = (319 mg ai/kg

- bw) / (2376 mg ai/kg

- bw) = 0.13

1 000 g mammal = (72 mg ai/kg

- bw) / (1028 mg/kg

- bw) = 0. 07

Chronic Dose

- Based Risk Quotients = EEC/NOEL

Hardwoods 15 g mammal = (1005 mg ai/kg

- bw) / (5.49 mg ai/kg

- bw) = 183 35 g mammal = (698 mg ai/kg

- bw) / (4.45 mg ai/kg

- bw) = 157 1000 g mammal = (159 mg ai/kg

- bw) / (1.92 mg ai/kg

- bw) = 83

Softwoods 15 g mammal = (459 mg ai/kg

- bw) / (5.49 mg ai/kg

- bw) = 87 35 g mammal = (319 mg ai/kg

- bw) / (4.45 mg ai/kg

- bw) = 72 1000g mammal = (72 mg ai/kg

- bw) / (1.92 mg ai/kg

- bw) = 38



### Bonzi II Drench for Potted Ornamentals

– 1 application at 6.1 lb ai/A

Woody Potted Ornamentals Risk Quotient = EEC / Toxicological Value

Birds

The following definitive data are available for birds: NOAEC = 453 mg/kg

- diet

Chronic Dietary Risk Quotients = EEC/NOAEC Hardwoods = (59 mg ai/kg

- leaves) / (453 mg ai/kg

- diet) = 0.13 Softwoods = (24 mg ai/kg

- leaves) / (453 mg ai/kg

- diet) = 0.05

Ma mmals

The following definitive data are available for mammals:

LD 50 = 1336 mg/kg

- bw NOEL = 2.5 mg/kg

- bw

Adjusted toxicity values were calculated for mammal size classes by T

- REX 15 g mammal LD 50 = 2936 mg/kg

- bw 35 g mammal LD 50 = 2376 mg/kg

- bw 1000 g mammal LD 50 = 1028 mg/kg

- bw 15 g mammal NOEL = 5.49 mg/kg

- bw238 35 g mammal NOEL = 4.45 mg/kg

- bw 1000 g mammal NOEL = 1.92 mg/kg

- bw

Acute Dose

- Based Risk Quotients = EEC/LD 50

Hardwoods 15 g mammal = ( 59 mg ai/kg

- bw) / (2936 mg ai/kg

- bw) = 0.02 35 g mammal = ( 39 mg ai/kg

- bw) / (2376 mg ai/kg

- bw) = 0.02 1000g mammal = (9 mg ai/kg

- bw) / (1028 mg/kg

- bw) = 0.01

Softwoods 15 g mammal = ( 23 mg ai/kg

- bw) / (2936 mg ai/kg

- bw) = 0.01 35 g mammal = ( 16 mg ai/kg

- bw) / (2376 mg ai/kg

- bw) = 0.01

1 000 g mammal = (3.6 mg ai/kg

- bw) / (1028 mg/kg

- bw) = 0.003

Chronic Dose

- Based Risk Quotients = EEC/NOEL

Hardwoods 15 g mammal = ( 59 mg ai/kg

- bw) / (5.49 mg ai/kg

- bw) = 11 35 g mammal = ( 39 mg ai/kg

- bw) / (4.45 mg ai/kg

- bw) = 9 1000 g mammal = ( 9 mg ai/kg

- bw) / (1.92 mg ai/kg

- bw) = 5

Softwoods 15 g mammal = ( 23 mg ai/kg

- bw) / (5.49 mg ai/kg

- bw) = 4 35 g mammal = (16 mg ai/kg

- bw) / (4.45 mg ai/kg

- bw) = 4 1000g mammal = (3.6 mg ai/kg

- bw) / (1.92 mg ai/kg

- bw) = 2

Non

- Woody Potted Ornamentals

Risk Quotient = EEC / Toxicological Value

Birds

The following definitive data are available for birds: NOAEC = 453 mg/kg

- diet

Chronic Dietary Risk Quotients = EEC/NOAEC

Non

- woody plants = (112 mg ai/kg

- plant) / (453 mg ai/kg

- diet) = 0.25

Mammals239 The follow ing definitive data are available for mammals:

LD 50 = 1336 mg/kg

- bw NOEL = 2.5 mg/kg

- bw

Adjusted toxicity values were calculated for mammal size classes by T

- REX 15 g mammal LD 50 = 2936 mg/kg

- bw 35 g mammal LD 50 = 2376 mg/kg

- bw 1000 g mammal LD 50 = 1028 mg/kg

- bw 15 g mammal NOEL = 5.49 mg/kg

- bw 35 g mammal NOEL = 4.45 mg/kg

- bw 1000 g mammal NOEL = 1.92 mg/kg

- bw

Acute Dose

- Based Risk Quotients = EEC/LD 50

15 g mammal = ( 106 mg ai/kg

- bw) / (2936 mg ai/kg

- bw) = 0.04 35 g mammal = ( 74 mg ai/kg

- bw) / (2376 mg ai/kg

- bw) = 0.03 1000g mammal = (17 mg ai/kg

- bw) / (1028 mg/kg

- bw) = 0.02

Chronic Dose

- Based Risk Quotients = EEC/NOEL

15 g mammal = ( 106 mg ai/kg

- bw) / (5.49 mg ai/kg

- bw) = 19 35 g mammal = (74 mg ai/kg

- bw) / (4.45 mg ai/kg

- bw) = 17 1000g mammal = (17 mg ai/kg

- bw) / (1.92 mg ai/kg

- bw) = 9



### Paclobutrazol 2SC Seed Treatment for Tomato, Cucurbit, and Pepper

– 1 application at 0.0040, 0.00029 , and 0.0079 lb ai/A, respectively

Risk Quotient = EEC / Toxicological Value

Birds

The fol lowing definitive data are available for birds: NOAEC = 453 mg/kg

- diet

Chronic Dietary Risk Quotients = EEC/NOAEC Tomato = (2.2 mg ai/kg

- diet) / (453 mg ai/kg

- diet) = 0.005 Cucurbit = (1.2 mg ai/kg

- diet) / (453 mg ai/kg

- diet) = 0.003 Pepper = (2.9 mg ai/kg

- diet) / (453 mg ai/kg

- diet) = 0.006 Broccoli = (0.36 mg ai/kg

- diet) / (453 mg ai/kg

- diet) = 0.0008240 Cauliflower = (0.36 mg ai/kg

- diet) / (453 mg ai/kg

- diet) = 0.0008 Cabbage = (0.36 mg ai/kg

- diet) / (453 mg ai/kg

- diet) = 0.0008

Mammals

The following definitive data are available for mammals:

LD 50 = 1336 mg/kg

- bw NOEL = 2.5 mg/kg

- bw

Adjusted toxicity values were calculated for mammal size classes by T

- REX 15 g mammal LD 50 = 2936 mg/kg

- bw 35 g mammal LD 50 = 2376 mg/kg

- bw 1000 g m ammal LD 50 = 1028 mg/kg

- bw 15 g mammal NOEL = 5.49 mg/kg

- bw 35 g mammal NOEL = 4.45 mg/kg

- bw 1000 g mammal NOEL = 1.92 mg/kg

- bw

Acute Dietary Risk Quotients = EEC/LD 50 Tomato 15 g mammal = (2.1 mg ai/kg

- diet) / (2936 mg ai/kg

- diet) = 0.0007 35 g mammal = (1.5 mg ai/kg

- diet) / (2376 mg ai/kg

- diet) = 0.0006 1000 g mammal = (0.33 mg ai/kg

- diet) / (1028 mg ai/kg

- diet) = 0.0003

Cucurbit 15 g mammal = (1.1 mg ai/kg

- diet) / (2936 mg ai/kg

- diet) = 0.0004 35 g mammal = (0.79 mg ai/kg

- diet) / (2376 mg ai/kg

- diet) = 0.0003 1000 g mammal = (0.18 mg ai/kg

- diet) / (1028 mg ai/kg

- diet) = 0.0002

Pepper 15 g mammal = (2.8 mg ai/kg

- diet) / (2936 mg ai/kg

- diet) = 0.001 35 g mammal = (1.9 mg ai/kg

- diet) / (2376 mg ai/kg

- diet) = 0.0008 1000 g mammal = (0.44 mg ai/kg

- diet) / (1028 mg ai/kg

- diet) = 0.0004

Broccoli 15 g mammal = ( 0.34 mg ai/kg

- diet) / (2936 mg ai/kg

- diet) = 0.0001 35 g mammal = ( 0.24 mg ai/kg

- diet) / (2376 mg ai/kg

- diet) = 0.0001 1000 g mammal = ( 0.05 mg ai/kg

- diet) / (102 8 mg ai/kg

- diet) = 0.00005

Cauliflower 15 g mammal = ( 0.34 mg ai/kg

- diet) / (2936 mg ai/kg

- diet) = 0.0001241 35 g mammal = ( 0.24 mg ai/kg

- diet) / (2376 mg ai/kg

- diet) = 0.0001 1000 g mammal = ( 0.05 mg ai/kg

- diet) / (1028 mg ai/kg

- diet) = 0.00005

Cabbage
15 g mammal = ( 0.34 mg ai/kg

- diet) / (2936 mg ai/kg

- diet) = 0.0001 35 g mammal = ( 0.24 mg ai/kg

- diet) / (2376 mg ai/kg

- diet) = 0.0001 1000 g mammal = ( 0.05 mg ai/kg

- diet) / (1028 mg ai/kg

- diet) = 0.00005

Chronic Dietary Risk Quotients = EEC/NOEL

Tomato 15 g mammal = (2.1 mg ai/kg

- diet) / (5.49 mg ai/kg

- diet) = 0.38 35 g mammal = (1.5 mg ai/kg

- diet) / (4.45 mg ai/kg

- diet) = 0.34 1000 g mammal = (0.33 mg ai/kg

- diet) / (1.92 mg ai/kg

- diet) = 0.17

Cucurbit 15 g mammal = (1.1 mg ai/kg

- diet) / 5.49 mg ai/kg

- diet) = 0.20 35 g mammal = (0.79 mg ai/kg

- diet) / (4.45 mg ai/kg

- diet) = 0. 18 1000 g mammal = (0.18 mg ai/kg

- diet) / (1.92 mg ai/kg

- diet) = 0.09

Pepper 15 g mammal = (2.8 mg ai/kg

- diet) / (5.49 mg ai/kg

- diet) = 0.51 35 g mammal = (1.9 mg ai/kg

- diet) / (4.45 mg ai/kg

- diet) = 0.43 1000 g mammal = (0.44 mg ai/kg

- diet) / (1.92 mg ai/kg

- diet) = 0.23

Broccoli 15 g mammal = ( 0.34 mg ai/kg

- diet) / (5.49 mg ai/kg

- diet) = 0.06 35 g mammal = ( 0.24 mg ai/kg

- diet) / (4.45 mg ai/kg

- diet) = 0.05 1000 g mammal = ( 0.05 mg ai/kg

- diet) / (1.92 mg ai/kg

- diet) = 0.03

Cauliflower 15 g mammal = ( 0.34 mg ai/kg

- diet) / (5.49 mg ai/kg

- diet) = 0.06 35 g mammal = ( 0.24 mg ai/kg

- die t) / (4.45 mg ai/kg

- diet) = 0.05 1000 g mammal = ( 0.05 mg ai/kg

- diet) / (1.92 mg ai/kg

- diet) = 0.03

Cabbage 15 g mammal = ( 0.34 mg ai/kg

- diet) / (5.49 mg ai/kg

- diet) = 0.06 35 g mammal = ( 0.24 mg ai/kg

- diet) / (4.45 mg ai/kg

- diet) = 0.05 1000 g mammal = ( 0.05 mg ai/kg

- diet) / (1.92 mg ai/kg

- diet) = 0.03