- Page 2 of 53

-

Risk Conclusions

The results of this screening

- level risk assessment indicate that the current uses of maleic hydrazide are not expected to cause direct adverse effects to Federally listed threatened and endangered (he reafter referred to as “listed”) and non

- listed freshwater and estuarine/marine fish
and invertebrates on an acute or chronic exposure basis. Direct adverse effects to listed and non

listed aquatic plants are also not expected. Acute risk to non

- listed m ammals is not expected, but
acute risk to listed mammals is uncer tain due due to maximum estimated environmental concentrations (EECs) being higher than the nondefinitive endpoint (greater than) values , highest concentration tested, in acute toxicity tes ts with mammals. Chronic risk to mammals is expected for certain size class/dietary item combinations when application rates are greater than 4.6 lbs
a.i./A. Acute and chronic risk to listed and non

- listed birds is uncertain due to max EECs higher
than the nondefinitive acute endpoints and a lack of chronic toxicity data with avian species.
Potential r isk to non

- listed species of beneficial terrestrial invertebrates is similarly uncertain due to nondefinitive ecotoxicity endpoints in acute contact honey be e studies which are lower than
the EECs . H owever , risk to listed species of beneficial terrestrial invertebrates is considered likely due to toxicity data showing substantial mortality effects to parasitic wasps and predatory mites at application rates th at are approximately 1/3 the registered maximum application rate

. Risk to listed and non

- listed monocot yledon (monocot) species is expected from the registered uses of maleic hydrazide. Risk to listed and non

- listed dicotyledon (dicot) species is expecte d in
semi

- aquatic areas, but may be re duced in dry areas when ground applications are used in place of aerial applications. Risk from spray drift alone is not predicted for ground applications but may be expected for listed and non

- listed monocot specie s when aerial applications of maleic hydrazide are made.

D esignations of “uncertain” for taxa in this assessment are a result o f incomplete ecotoxicology
data. Where uncertainty designations are made for a taxon, efforts have been made to
characterize the risk picture. For instance, multiple lines of evidence support the potential for
effects to non

- target terrestrial invertebrates, whereas for mammals , available lines of evidence
indicat e that the potential for acute risk may be low er

.

Table 1 summarizes the representative uses assessed and the taxa that may potentially be directly

at r isk from exposure to maleic hydrazide

. Additional description is further summarized in Appendix 3

.Page 3 of 53

Table 1 : Summary of Risk Determinations for Current ly Regi stered Uses of Maleic Hydrazide 1

U se Fish 2 Aquatic

Invertebrates 3 Aquatic

Plants 4 Terrestrial Plants Birds 5 Mammals Terrestrial

Invertebrates

Acute Chronic Acute Chronic Listed Non - Listed Monocots Dicots Acute Chronic Acute Chronic Listed Non - List ed Listed NonListed Listed Non

Listed

Agricultural
Fallow/Idleland/

Conservation

Reserve X X X X U U U a X X U

Ornamental
and/or Shade

Trees 6 X X X X U U U a X X U

Golf Course Turf, Nonagricultural Rights

- of

- Way,
Urban Areas 5 X X X X b U U U a X X U

Tobacco X X X c X c U U U a X X U

Ornamental Woody Shrubs
and Vines X d X d X c X c U U U a X

Potato (White/Irish) X d X d X c X c U U X

Onion X e X e X c X c U a U U

Citrus X e X e X f X f U a U U

1 A b olded and shaded “ X ” indicates risk is expected to listed and non

- listed species

. An italicized “ X ” indicates that risk is expected to listed species only. A “U” indicates that risk is uncertain due to a lack of data. A blank box indicates that no risk i s expected. See Risk Characterization section for more information.

2 Fish includes both estuarine/marine and freshwater fish and are also considered surrogates for aquatic

- phase amphibians.

3 Aquatic Invertebrates includes both estuarine/marine and fre shwater invertebrates.

4 Aquatic Plants includes both vascular and non

- vascular plants.

5 Birds are considered surrogates for reptiles and terrestrial

- phase amphibians.

6 Also i n c lu d es Ornamental Lawns and Turf and Residential Lawns use patterns

7 Also i ncludes Industrial/Construction Areas (Outdoor), Nonagricultural Uncultivated Areas/Soils, Fencerows/Hedgerows, and Airports/Landing Fields use patterns.

a Acute risk is not expected for non

- listed species and is uncertain for listed species.

b Risk to non

- listed dicots is only predicted in semi

- aquatic areas (regardless of application method)

c Risk to both listed and non

- listed dicots is only predicted in semi

- aquatic areas (regardless of application method)

d Risk to non

- listed mon ocots is only predicted in semi

- aquatic areas (regardless of application method)

e Risk to both listed and non

- listed monocots is only predicted in semi

- aquatic areas (regardless of application method)

f Risk to both listed and non

- listed dicots is only predicted in semi

- aquatic areas, however non

- listed dicots in
semi

- aquatic areas are not considered at risk for scenarios with only ground applications.Page 4 of 53

Basic Uncertainties

 No available ecotoxicity or fate data were evaluated b y EFED for hydrazine, a n impurity present in low levels in technical grade maleic hydrazide.

 Several registered product labels do no t specify the number of applications per yea r

. This assessment assumed that only 1 application at the maximum application rate is made (the exception to this is for citrus, where the label does state that 2 applications can be made). This may underestimate risk for those use sites that do not state the maximum number of applications.

 No chronic data are available for avia n reproduction.

 Terrestrial animal acute and chronic studies did not test concentrations up to the maximum EECs predicted in this assessment, but generally did not have effects at the
concentrations tested.- Page 5 of 53

-



## Environmental Fate and Ecological R isk Assessment for the

Registration of Maleic Hydrazide
and its P otassium S alt (K

- MH)

Maleic Hydrazide 1,2

- dihydro

- 3,6

- pyridazinedione CAS Registry Number 123

- 33

- 1
PC Code 051501

Maleic Hydrazide P otassium salt
C AS Registry Number 28382

- 15

- 2
PC Code 051503 Prepared by:

Ibrahim Abdel

- Saheb , Ph.D. Environmental Scientist Michael Wagman, Biologist

U. S. Environmental Protection Agency Office of Pesticide Programs
Environmental Fate and Effects Division
Environmental Risk Branc h VI 1200 Pennsylvania Ave., NW

Mail Code 7507P Washington DC 20460 Reviewed by: Amy Blankinship, Senior Science Advisor , ERB VI William P. Eckel, Ph.D, Senior Science Advisor, ERB VI Mark Corbin, Branch Chief, ERB VI

June 18 , 2014Page 6 of 53



## Table of Contents

1. Executive Summary

................................ ................................ ................................ ................................ ................. 7
2. Problem Formulation

................................ ................................ ................................ ................................ ............ 11
2.1. Nature of Regulator y Action

................................ ................................ ................................ ....................... 11
2.2. Mode of Action

................................ ................................ ................................ ................................ .............. 12
2.3. Use Characterization

................................ ................................ ................................ ................................ .... 12
2 .4. Conceptual Model

................................ ................................ ................................ ................................ ......... 15 3. Analysis

................................ ................................ ................................ ................................ ................................ ... 20 3.1. Exposure Characterization

................................ ................................ ................................ ................................ 20 3.2. Ecological Effects Characterization

................................ ................................ ................................ .................. 26
4. Risk Characterization

................................ ................................ ................................ ................................ ........... 32
4.1. Risk Estimation

................................ ................................ ................................ ................................ ................... 32 4.2. Risk Description

................................ ................................ ................................ ................................ ................... 38 4.2.1. Risks to Aquatic Organisms

................................ ................................ ................................ .............................. 38 4.2.2. Risks to Terrestrial Orga nisms

................................ ................................ ................................ .......................... 39
5. Federally Threatened and Endangered (Listed) Species Concerns

................................ ................................ .... 43
6. Literature Cited

................................ ................................ ................................ ................................ ........................ 46 Appendix 1

– Surface Water Concentration Calculator Modleing Summary

.................... 47 Appendix 2

- Environmental Fate Studies Summary

................................ ............................ 48 Appendix 3

– Summary of Risk Conclusions by Use Site and Taxa

................................ ...... 50Page 7 of 53

1. Executive Summary

EFED has completed the R egistration R eview preliminary ecological risk assessment for maleic hydrazide acid ( 1 ,2

- dihydro

- 3,6

- pyridazinedione CAS Registry Number 123

- 33

- 1 ; PC Code:
051501 )

, i ts potassiu m salt (CAS Registry Number 28382

- 15

- 2 ; PC Code 051503 ) and their end

use product s. Maleic hydrazide is a systemic growth retardant with end use products generally

f ormulated using the potassium salt of maleic hydrazide. When sprayed on plants, it is absorbed and moves internally where it blocks cell division

. It is a plant growth regulator (sprout inhibitor)
and herbicide whose mode of activity is as a uracil antimet abolite. Maleic hydrazide is registered for use on tobacco, potatoes, onions, non

- bearing citrus, turf, utility and highway rights

- of

- way, airports, industrial land, lawns, recreational areas, ornamental/shade trees and ornamental plants.
Most of the malei c hydrazide used in the U.S. is applied to tobacco (80%) , followed by potatoes (18%) . Formulations include an emulsifiable concentrate and soluble concentrate/liquid and solid. Maleic hydrazide is applied by aircraft or ground spray equipment. Current use practice limitations prohibit treating crops within 7 days of harvest, and grazing or feeding forage or hay from treated
areas to livestock.

M aleic hydrazide is not persistent unders aerobic soil conditions. It de grades to transformation products with a h alf life of < 24 hours

. It is stable to hydrolysis though it photolyzes in water
with an observed half

- life of >30 days at pH 9. Maleic hydrazide is expected to be mobile, due to its low adsorption to soils with K OC values that range from 11.5

– 70 mL/g o .c. Maleic hydrazide is moderately persistent under anaerobic soil conditions (half

- life 30

- 60 days ). Maleic hydrazide did not persist in the available field dissipation studies and degraded with half

- lives of 3 days on bare ground and 5 days in turf plot s, 2

- 3 days (sandy loam, potatoes ), 7 days (loam, tobacco). The potential for maleic hydrazide to bioaccumulate in fish is anticipated to be very low, as indicated by the octanol/water partition coefficient ( log Kow=

- 0.68)

.

Maleic hydrazide is not likely to volatilize given its vapor pr essure (7.5 x 10

- 8 mm Hg at 25 o C and Henry’s Law constant = 2.5 x 10

- 5 m 3 atm g/mol at 2 5 o C).

No available fate or ecotoxicity data has been evaluated by EFED for hydrazine, a n impurity present at low levels in technical grade ma leic hydrazide. High levels of hydrazine as an impurity was responsible for carcinogenicity reported in several mammalian toxicity studies.

Maleic hydrazide is practically non

- toxic on an acute basis to freshwater and estuarine/marine fish
and invertebrat es. On a chronic exposure basis, maleic hydrazide was not found to have any
treatment related effects to freshwater and estuarine/marine fish and invertebrates up to the highest concentration tested, 9,600 μg a.i./L (for fathead minnow)

— 99,000 μg a.i./L ( for daphnids)

.

Maleic hydrazide is practically nontoxic to birds, mammals, and beneficial insects ( i.e. , honey bees) on an acute exposure basis as no effects were recorded in the available studies ( i.e. , the

LD 50 /LC 50 effect level was greater than the highest concentration tested ). Chronic toxicity testing
with mammals identified a decrease in body weight gain of multiple generations in a 2

- gener ation rat study (MRID 00128720 ). No avian reproduction data are available to assess chronic effects to
bird s. The 1994 RED (USEPA, 1994) determined that avian reproduction studies were notPage 8 of 53

required for maleic hydrazide because “it is not applied more than once prior to or during the breeding season and it i s practically nontoxic to birds.” However, the 2009 problem formulation (USEPA, 2009 a ), noted that many uses “do not specify on the label the number of applications and application intervals,” but nonetheless did not request avian reproduction data.

Based on the available plant toxicity data, maleic hydr azide exhibited low toxic ity to aquatic plants , but may exhibit toxicity to some species of terrestrial plants.

No degradates of maleic hydrazide are considered metabolites of concern

. The major degradate of maleic hydrazide is CO 2 . Other nonvolatile degradates, maleic acid and maleimide, were identified in small amounts (<5% of the applied) which further degrade into CO 2.

Potential effects to federally

- listed endangered and threatened speci es (listed species) based on LOC exceedances require an in

- depth listed species evaluation determining the potential co

occurrence of listed species and use patterns of maleic hydrazide . Identified potential risks to listed species are summarized in Table 2

.

Table 2 . Potential Effects to Federally Listed Taxa Associated with Direct Effects from the Registered Uses of Maleic Hydrazide.

Listed Plant Taxon Potential Direct Effects

Terrestrial and semi

- aquatic plants

– monocots and dicots Yes

Aquatic nonva scular plants No Aquatic vascular plants No

Listed Animal Taxon Potential Direct Effects

Acute Chronic

Terrestrial invertebrates Yes 1 Uncertain

Mammals Uncertain 2 Yes

Birds Uncertain 2 Uncertain 3 Reptiles Uncertain 2 Uncertain 2 ,3 Amphibians Uncertai n 2, 4 Uncertain 2, 3,4

Freshwater fish No No

Freshwater invertebrates No No

Mollusks No No

Estuarine/marine fish No No

Estuarine/marine invertebrates No No

1 Although an LC 50 was not attainable in the acute contact toxicity tests with honey bees, the li mit dose (36.3 μg a.i./bee) was not high enough to preclude risk at the non

- listed species LOC (0.4), based on the maximum EECs (35.1 μg/bee) for registered maleic hydrazide uses. Further, given that additional toxicity data with predatory mites and paras itic wasps showed lethal effects at concentrations well below the maximum application rate, EFED cannot preclude effects to listed beneficial terrestrial invertebrates.

2 Risk to this taxa was considered uncertain due to the use of non

- definitive toxicolog ical endpoints that were below maximum EECs. Although no effects were observed in acute toxicological studies, the doses tested did not exceed the maximum EECs predicted by the maximum application rates.

3 Chronic risk to this taxa is uncertai n due to a lack of avian reproduction data

4 Risk to these taxa are uncertain for terrestrial

- phase amphibians. No direct effects are expected for aquatic phase amphibians.

Based on this screening

- level assessment, acute and chronic risk resulting from direct effects is not expected for freshwater and estuarine/marine fish (surrogates for aquatic

- phase amphibians) and invertebrates or aquatic plants from the use of maleic hydrazide on all of its registered use
sites. Acute and chronic risk resulting fro m direct effects cannot be precluded for listed birds (surrogates for reptiles and terrestrial

- phase amphibians), mammal s, and terrestrial invertebratesPage 9 of 53

from the use of maleic hydrazide on all its registered use sites. Risk can also not be precluded for

t errestrial plants , which would be expe cted given maleic hydrazide ’ s mode of action.

Potential direct effects on listed birds (and reptiles and terrestrial phase amphibians), mammals, terrestrial invertebrates and terrestrial plants and non

- listed birds, terrestrial invertebrates and terrestrial pl ants from the use of m aleic hydrazide may be associated with modification of primary constituent elements (PCEs) of designated critical habitat, where such designations have been made. However, at this current stage of the Registration Review process, it is premature to make

e ffects determinations until further refinements are conducted. In order to make species

- specific effects determinations, useful refinements include more detailed 1) species

- specific ecological and biological data; 2) information on use patterns for maleic hydrazide ; and 3) sub

- county level spatial proximity analyses for the co

- occurrence of potential areas of effects and listed species/designated critical habitats of concern. Examples of such refinements are described below.

EFED is currently developing tools that are expected to further refine the species

- specific assessment and designed to aid in making effects determinations for individual listed species and/or their designated critical habitats (if applicable). Information obtained from the U.S. Fis h & 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 Programs Pesticide Registrati on Information System (PRISM) knowledgebase, which consists of an information repository for biological and behavioral data relevant to specific species and/or their habitats) and a document repository that contains supporting documents (e.g., USFWS recove ry plans) and electronic information ( e.g ., GIS data files). These data will be relied upon to provide information on habitat, diet, life history variables, and temporal and spatial data. For terrestrial taxa specifically, the biological information rele vant to Risk Quotient (RQ) calculations ( e.g ., diet and body weight) will be used to parameterize exposure estimates to derive species

- specific RQs consistent with currently used methods in the

T

- REX and T

- HERPS models.

Refinements may also include more detailed analyses of the registered uses and their use patterns that result in level of concern (LOC) exceedances for listed species in the screening

- level assessment. The analyses may include more information on where, when, and how maleic hydrazide is used on crops including: onion, shallot, potato, tobacco and citrus as well as non

agricultural uses including rights

- of

- way (ROW), ornamental lawns, turf, and golf courses

. 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 maleic hydrazide is reasonably expected to be used. Similarly, refinements for the timing of applications and how maleic hydrazide is used may involve an analysis of reported usage data (if available) and a more in

- depth exploration of agronomic practices.

The U.S. Environmental Protection Agency (EPA) , along with the U.S. Department of Agriculture (USDA), the U.S . Fish and Wildlife Service (FWS), and the National Marine Fisheries Service (NMFS), have announced the availability of a report developed by the National Academy of Sciences’ National Research Council outlining recommendations on specific scientific andPage 10 of 53

t echnical issues related to the development of endangered and threatened species risk assessments for pesticides that are compliant with the Endangered Species Act (ESA) and the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA). The EPA, USDA, FWS and NMFS asked the NRC to consider a range of scientific and technical issues including:

• identifying best available scientific data and information;

• considering sub

- lethal, indirect and cumulative effects;

• assessing the effects of chemical mixture s and inert ingredients;

• analyzing the effects of pesticide use through the use of models;

• incorporating uncertainties into the evaluations; and

• using geospatial information and datasets that can be employed by the agencies in the
course of these assessments.

After reviewing the NRC’s recommendations on these scientific and technical issues, the EPA and its federal partners will determine how these recommendations can be implemented and incorporated into the scientific approaches for developing l isted species risk assessments. It is anticipated that any draft guidance and/or science policies developed by EPA and its federal partners as a result of the NAS recommendations would be released for public comment prior to implementation.

The refinemen ts based on species

- specific data and detailed usage information, when available, 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 criti cal habita ts. For example, if maleic hydrazide 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 to the species may often be precluded. If LOCs are still exceeded for birds (surro gates for terrestrial

- phase amphibians and reptiles), mammals, terrestrial invertebrates and terrestrial plants after conducting the refined analyses, further analyses of the potential spatial/temporal co

- occurrence of listed species of concern (and any d esignated critical habitat) may be conducted. The extent of possible refinement in the analyses of spatial/temporal

co

- occurrence will largely depend on the scale and quality of the available sub

- county level use site (e.g., NLCD, CDL) and species locatio n data

.

Uncertainties

Although the majority of product labels explicitly state that the maximum number of applications is 1 per year, s everal registered product labels do not specify the number of applications per year. This assessment assumed only 1 ap plication at the maximum rate for each use site (except for citrus, for which labels clearly allow 2 applications at the maximum rate). Thus this assessment may underestimate exposure to maleic hydrazide for those use sites with labels that do not specify the maximum number of applications per year or crop cycle

.

No available fate or ecotoxicity data has been evaluated for hydrazine, a n impurity present in low levels in technical grade maleic hydrazide. This assessment does not quantitatively evaluate risk posed by the hydrazine impurity

. If hydrazine is more persistant in the environment than maleic hydrazide , the n potential for risk from maleic hydrazide and its contaminat will be underestimated. If hydrazine is more toxic than maleic hydrazide and is p resent in concentrations higher than what was tested in the maleic hydrazide ecotoxicity studies (<0.12 ppm in the most recently conductedPage 11 of 53

toxicity studies), then this assessment may underestimate risk posed by maleic hydrazide due to
the hydrazine contami nation. No avian reproduction data are available , therefore chronic risk to birds cannot be precluded in this assessment . Acute and chronic studies with terrestrial animal species did not result in any toxic effects, therefore the maximum concentration t ested was used as the endpoint ( i.e. LD 50 , LC 50 , or NOAEC) for risk estimation. However, these studies did not test concentrations up to the maximum estimated environmental concentrations (EECs) for maleic hydr a zide uses , therefore actual risk to terrestri al animal species remains uncertain.

2. Problem Formulation

The purpose of problem formulation is to provide the foundation for the environmental fate and ecological risk assessment in support of the Registration Review of the Plant growth regulator,

h erbicide : m aleic h ydrazide [ ( 1,2

- dihydro

- 3,6

- pyridazinedione ) ; CAS#: 123

- 33

- 1 ; PC Code:
051501 ]

, and its potassiu m salt (CAS Registry Number 28382

- 15

- 2 ; PC Code 051503 ) . The problem formulation sets the objectives for the risk assessment, establishes a ri sk hypothesis and conceptual model depicting potential risk, and provides a plan for analyzing the data and characterizing the risk associated with the uses of m aleic h ydrazide (USEPA, 1998).

2.1. Nature of Regulatory Action

Under the Federal Insectici de, Fungicide, and Rodenticide Act (FIFRA), all pesticides distributed or sold in the United States must be registered by the United States Environmental Protection Agency (EPA or the Agency). To determine whether a pesticide can be registered, the EPA

ev aluates the product’s safety to 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 re view of pesticides, i.e

., R egistration R eview 1 . The registration review program 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 registration review program, the Agency periodically reevaluates pesticides to make sure tha t as changes occur, products in the marketplace can be used safely.

Additionally, potential effects to federally listed endangered and threatened species (hereafter
referred to as “listed” ) and their designated critical habitat are also considered under t he Endangered Species Act (ESA) in order to ensure that the conti nued registration of maleic hydrazide is not likely to jeopardize the continued existence of listed species or adversely modify their critical habitat. In order to meet the requirements of F IFRA and the ESA, this assessment follows EPA guidance on conducting ecological risk assessments (USEPA, 1998) and Office of Pesticide Program’s Overview Document, which contains guidance for assessing pesticide risks

to non

- listed and listed species (USEP A, 2004).

1 http://www.epa.gov/oppsrrd1/registration_review/Page 12 of 53

2.2

. Mode of Action

Maleic hydrazide is a plant growth regulator (sprout inhibitor) and herbicide whose mode of activity is as a uracil antimetabolite. It is registered for use on tobacco, potatoes, onions, non

bearing citrus, turf, utility and highway rights

- of

- way, airports, industrial land, lawns,

r ecreational areas, ornamental/shade trees and ornamental plants. When sprayed on plants, it is absorbed and moves internally where it blocks cell division.

2.3

. Use Characterization

Formula tions include an emulsifiable concentrate and soluble concentrate/liquid and solid. Maleic hydrazide is applied by aircraft or ground spray equipment. Formulations include an emulsifiable concentrate, liquid soluble concentrate and solid soluble concentrat e. Maleic hydrazide is applied by aircraft or ground spray equipment. Current use practice limitations prohibit treating crops within 7 days of harvest, and grazing or feeding forage or hay from
treated areas to livestock. For many of the use sites, espec ially the ones with the highest application rates (agricultural fallow, idleland, conservation reserve, and ornamental and shade trees), labels are lacking information on the maximum number of applications per year and/or the maximum application rate per y ear

. This assessment has assumed that the maximum application rate is applied once (unless otherwise stated) without any succeeding retreatment. Therefore, this assessment may underestimate risk if multiple applications at the maximum application rate

ar e applied in a season. U se patterns for Maleic hydrazide based on crop agricultural and no n agricultural uses are summarized in Table s 3

- 4 , below.

Table 3: Use Site and Application Rates for Registered Maleic Hydrazide Uses Crop/Use Site Maximum Applicat ion Rate (lbs a.i./A) Number of

Applications/

Year (min

retreatment interval) Agricultural
Fallow/Idleland /Conservation

Reserve 1 3 NS

Ornamental and/or Shade

Trees 9.2 NS

Ornamental Lawns and Turf

, Residential Lawns 8.7 1

Airports/Landing Fields,
Golf Course Turf,
Industrial/Construction Areas (Outdoor), Nonagricultural Rights

- of

Way/Fencrows/Hedgerows, 8 1Page 13 of 53

Nonagricultural Uncultivated Areas/Soils, Urban Areas

Tobacco 6.1 1 Ornamental Woody Shrubs
and Vines 4.6 NS

Potato (White/Irish) 4.3 1

Onion 2.9 1

Citrus 1.9 2 (42)

Table 4

. Maleic hydrazide Uses by Label

Label Formulation % a.i. Crops/Sites No.

apps /Yr Method of

App lication

000400

- 00084 L 21.7 POTATO, TOBACCO,

ONION

, AGRICULTURAL
FALLOW/IDLELAND 1 Ground and Air

000400

- 00094 L 21.7 ORNAMENTAL LAWNS

AND TURF

, AGRICULTURAL FALLOW/IDLELAND, GOLF COURSE TURF,
RESIDENTIAL LAWNS 1 Boom sprayer

000400

- 00165 SC/S 80 AGRICULTURAL
FALLOW/IDLELAND

, AIRPORTS/LANDING

FIELDS

, NONAGRICULTURAL
RIGHTS

- OF

WAY/FENCEROWS/HEDGER OWS, ORNAMENTAL
AND/O R SHADE TREES,
GOLF COURSE TURF

, POTATO, TOBACCO, ONION 1 Tractor

- mounted sprayer Ground, Air, Boom sprayer

000400

- 00452 L 30.3 POTATO, TOBACCO, ONION 1 Ground, Air, Boom sprayer

000400

- 00482 EC 21 TOBACCO 1 Dropline, Tractor

- mounted sprayer, Jug

003 862

- 00159 L 21.7 NONAGRICULTURAL
RIGHTS

- OF

WAY/FENCEROWS/HEDGER OWS, ORNAMENTAL LAWNS AND TURF,

AIRPORTS/LANDING FIELDS, ORNAMENTAL AND/OR SHADE TREES,
ORNAMENTAL WOODY

SHRUBS AND VINES 1 Hose

- end sprayer

005549

- 00089 EC 21.7 TOBACCO 1 Tractor

- mounted sp rayer,

power sprayer

019713

- 00001 L 30.2 ORNAMENTAL AND/OR SHADE TREES,
AIRPORTS/LANDING

FIELDS 1 Airblast, boom sprayerPage 14 of 53 , NONAGRICULTURAL
RIGHTS

- OF

WAY/FENCEROWS/HEDGER
OWS

, ORNAMENTAL
LAWNS AND TURF

, GOLF
COURSE TURF

, RESIDENTIAL LAWNS

019713

- 00002 L 30.2 NONAGRICULTURAL
RIGHTS

- OF

WAY/FENCEROWS/HEDGER
OWS

, ORNAMENTAL
LAWNS AND TURF

, RESIDENTIAL LAWNS

, CITRUS

, POTATO, ONION 1 Animal

- drawn sprayer, aircraft,

Tractor

- mounted sprayer,

sprayer

019713

- 00017 L 27.8 TOBACCO 1 Animal

- drawn sprayer, Comp ressed air sprayer,

Tractor

- mounted sprayer

019713

- 00020 L 21.6 TOBACCO 1 Compressed air sprayer

Tractor

- mounted sprayer

019713

- 00105 EC 11.1 TOBACCO Not specified Sprayer,

Compressed air sprayer

019713

- 00293 L 30.2 TOBACCO Not specified Compressed ai r sprayer,

Tractor

- mounted sprayer

019713

- 00294 L 21.6 TOBACCO Not specified Compressed air sprayer,

Tractor

- mounted sprayer

019713

- 00361 DF 80 ORNAMENTAL AND/OR
SHADE TREES

, ORNAMENTAL WOODY

SHRUBS AND VINES

, AIRPORTS/LANDING
FIELDS

, NONAGRICULTURAL

R IGHTS

- OF

WAY/FENCEROWS/HEDGER
OWS

, NONAGRICULTURAL
UNCULTIVATED
AREAS/SOILS

, GOLF

COURSE TURF

, POTATO, TOBACCO, ONION 1 Ground, Air,

Tractor

- mounted sprayer

019713

- 00371 SC/S 80 TOBACCO Not specified Tractor

- mounted sprayer,

Compressed air sprayer

0197 13

- 00372 SC/S 80 ORNAMENTAL LAWNS

AND TURF

, RESIDENTIAL
LAWNS

, NONAGRICULTURAL
RIGHTS

- OF

WAY/FENCEROWS/HEDGER

OWS

, CITRUS

, POTATO,
ONION Not specified Tractor

- mounted sprayer,

Compressed air sprayer

051873

- 00002 EC 21.7 TOBACCO Not specified Animal

- drawn sprayer

, Tractor

- mounted sprayer, Compressed air sprayer,

051873

- 00006 EC 11.1 TOBACCO Not specified Compressed air sprayer,

sprayerPage 15 of 53

051873

- 00008 EC 21.7 ORNAMENTAL AND/OR
SHADE TREES

, AIRPORTS/LANDING
FIELDS

, GOLF COURSE

TURF

, INDUSTRIAL AREAS (OU TDOOR)

, NONAGRICULTURAL
RIGHTS

- OF

WAY/FENCEROWS/HEDGER
OWS

, ORNAMENTAL

WOODY SHRUBS AND
VINES Not specified Pump

- up sprayer, Air carrier

sprayer, Boom sprayer

051873

- 00009 L
30.15 TOBACCO Not specified Animal

- drawn sprayer

, Tractor

- mounted sprayer,

Co mpressed air sprayer

051873

- 00017 SC/S 80 TOBACCO Not specified Animal

- drawn sprayer

, Tractor

- mounted sprayer, Compressed air sprayer

A screening level estimate of current usage of m aleic hydrazide is presented in Table 5

. This screening level us a ge assessment presents usage data on an annual basis and is derived from USDA’s National Agricultural Statistics Service with data updated to 2012

.

T able 5

. Maleic hydrazide Screening Level Usage Analysis (SLUA) for 2012

Percent Crop Treated Crop Lb s. A.I. Average Maximum

1 Onions 30,000 10 20

2 Potatoes 200,000 10 15

3 Shallot* <500 N/C N/C

4 Tobacco 600,000 65 80
* California data, only LBS a.i. available . No information available about use of this chemical on this crop
in other states.

N/C = not calculated

2. 4

. Conceptual Model

The potential terrestrial and aquatic exposure pathways and effects of the registered uses of m aleic hydrazide are shown in Figure 1 . The conceptual model used to depict the potential ecological
risk associat ed with the registered use s of maleic hydrazide assumes that, as a plant growth regulator (sprout inhibitor) and herbicide

, m aleic hydrazide is capable of adversely affecting terrestrial and aquatic animals and plants, provided that environmental concentra tions are sufficiently elevated as a result of the label ed uses. Solid arrows in Figure 1 depict the most likely routes of exposure and effects; dashed lines depict potential routes of exposure that are not considered likely for m aleic hydrazide

.Page 16 of 53

The hyp othesis for the risks of maleic hydrazide to non

- target animals focuses on both aquatic and terrestrial environments via potential exposure to the parent from direct spray, spray drift, and runoff. Leaching is considered a significant route of transport c onsidering maleic hydrazide is
mobile in water. Dotted exposure routes are not likely (not anticipated to volatize). For terrestrial organisms, the major route of exposure is via diet, such as through consumption of plant leaves or insects, which contain maleic hydrazide residues as a result of direct application and/or spray drift

, or root uptake and translocation . For aquatic animal species, the major routes of exposure are direct contact via the respiratory surface (gills) or the integument . Aquatic v ascular and non

vascular plants may also be exposed via direct uptake and adsorption. Risk to terrestrial plants is also considered in this screening

- level assessment. In addition , maleic hydrazide has a low potential for sorption to sediment; therefore, exposure to organisms that reside primarily in the

“ benthos” is not likely . Estimated exposure concentrations for all organisms are obtained through the use of several Agency exposure models.

The following risk hypothesis is presumed for this screening l evel assessment:

Based on the application methods, mode of action, direct toxicity to non

- target aquatic and terrestrial species, the registered uses of maleic hydrazide ha s the potential to reduce survival, reproduction, and/or growth in listed and non

- l isted terrestrial and aquatic organisms

.Page 17 of 53Page 18 of 53

Analysis Plan

Residues of Concern

In October 1976, maleic hydrazide went into Special Review (then called Rebuttable Presumption Against Registration or RPAR) because it met the risk criteria for oncog enic, mutagenic and reproductive effects. Based on other data submitted, EPA determined that the oncogenicity and reproductive effects triggers were not supported, and that only weak evidence supported the mutagenicity trigger. In concluding the RPAR in Ju ne 1982, EPA allowed
continued use of maleic hydrazide and its potassium salt (K

- MH), but established an upper limit
of 15 ppm for the impurity hydrazine (associated with tumor induction) in technical grade maleic hydrazide. At this level, lifetime cancer risks for both dietary and worker exposure were not
considered of concern (USEPA

, 2009 a ). This assessment considers the presence of hydrazine as an uncertainty and risk from hydrazine is qualitatively considered in the risk description section ( Section 4. 2.1 and 4.2.2 ). No degradates were considered residues of concern in this assessment.

Mixtures

Evaluation of pesticide environmental mixtures is beyond the scope of this assessment because of myriad factors that cannot be quantified based on the availab le data. Those factors include identification of other possible co

- contaminants and their concentrations, differences in the pattern and duration of exposure among contaminants, and the differential effects of other physical/chemical characteristics of th e receiving waters ( e.g. organic matter present in sediment and suspended water). Evaluation of factors that could influence additivity/synergism is beyond the scope of this assessment and the capabilities of the available data to allow for an evaluation. However, it is acknowledged that not considering mixtures could over

- or under

- estimate risks depending on the type of interaction and factors discussed above.

Measures of Exposure

EFED uses standard available models to evaluate potential exposures t o aquatic and terrestrial organisms as described at http://www.epa.gov/pesticides/science/models_db.htm

.

Since the previous exposure assessments were completed (DP 362546; USEPA 2009)

, the following main changes in standard procedures have been made:

1) Transformation rates for fate studies were recalculated according to the North American Free Trade Agreement (NAFTA) Guidance for Evaluating and Calculating Degradation Kinetics
in Environmental Med ia ( NAFTA, 201 1 ) . These updated results will be used in estimating model inputs for estimating aquatic exposure.

The most up to date procedures and models are used in the Registration Review exposure

assessments.Page 19 of 53

Measures of Effect

Selected toxicity data are used to calculate risk estimates. Any additional informat ion submitted by the registrant or found in the open literature are also to be considered. The open literature studies are identified using EPA’s ECOTOXicity (ECOTOX) 2 database , which employs a literature search engine for locating chemical toxicity data for aquatic life, terrestrial plants, and wildlife. The evaluation of both sources of data can also provide insight into the direct and indirect effects of pesticides on biotic communities from loss of species that are sensitive to the chemicals
and from changes in structure and functional characteristics of the affected communities.

Endangered Species Assessments

Consistent with the Agency’s responsibility under the Endangered Species Act (ESA), the Agency evaluates potential risks to listed species fro m registered uses of pesticides in Registration Review

. These assessments are conducted in accordance with standard EPA procedures and good scientific judgment. The process for evaluating potential risks to listed species is further described in the
Overv iew Document at http://www.epa.gov/oppfead1/endanger/litstatus/riskasses.htm

.

Endocrine Disruptor Screening Program

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 tox icity. These studies include endpoints which may be susceptible to endocrine influence, including effects on endocrine target organ histopathology, organ weights, estrus cyclicity, sexual maturation, fertility, pregnancy rates, reproductive loss,
and sex r atios in offspring. For ecological hazard assessments, EPA evaluates acute tests and chronic studies that assess growth, developmental and reproductive effects in different taxonomic groups. As part of the Problem Formulation for Registration Review for maleic hydrazide EPA reviewed these data and selected the most sensitive endpoints for relevant risk assessment scenarios from the existing hazard database. However, as required by FFDCA section 408(p), maleic hydrazide is subject to the endocrine screeni ng part of the Endocrine Disruptor Screening Program (EDSP).

EPA has developed the EDSP to determine whether certain substances (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 two

- 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. Chemicals that go through Tier 1 screening and are found to have the potential to interact with E, A, or T hormonal systems will proce ed to the next stage of the EDSP where EPA will determine which, if any, of the Tier 2 tests are necessary based on the available data. Tier 2

2 http://cfpub.epa.gov/ecotox/Page 20 of 53

testing is designed to identify any adverse endocrine

- related effects caused by the substance, and
establish a do se

- response relationship between the dose and the E, A, or T effect.

Under FFDCA section 408(p), the Agency must screen all pesticide chemicals. Between October 2009 and February 2010, EPA issued test orders/data call

- ins for the first group of 67
chemi cals, which contains 58 pesticide active ingredients and 9 inert ingredients. A second list of chemicals identified for EDSP screening was published on June 14, 2013 3 and includes some pesticides scheduled for registration review and chemicals found in wa ter

. Neither of these lists should be construed as a list of known or likely endocrine disruptors.

For further information on the status of the EDSP, the policies and procedures, the lists of chemicals, future lists, the test guidelines and the Tier 1 sc reening battery, please visit our
website. 4

3. Analysis

3.1. Exposure Characterization

3.1.1. Environmental Fate and Transport Characterization

The major route of dissipation of maleic hydrazide in the environment is by biotic processes. Hydrolysi s, photodegradation, and volatilization do not appear to play a significant role in the dissipation process. The major degradate of maleic hydrazide is CO 2 . Other nonvolatile degradates, maleic acid and maleimide, were identified in small amounts (<5% of t he applied) which further degrade into CO 2.

Maleic hydrazide is fairly non

- persistent, with a soil aerobic half

- life of <24 hours, and moderately persistent under anaerobic soil conditions (half

- life 30

- 60 days). Maleic hydrazide is expected to be mobile, due to its low adsorption to soils. K d values for parent maleic hydrazide were 0.14 to 2.61 (MRID# (00151952). Sorption correlates with organic carbon (Koc ranges from 11.5

– 70 mL/g) ; thus an d ac cording to the FAO classification, maliec hydrazide is

cons idered as mobile in soil (FAO, 2000).

The terrestrial field dissipation half

- lives are 3 days on bare ground and 5 days in turf plots, 2

- 3 days (sandy loam, potatoes), 7 days (loam, tobacco).

No available fate data were evaluated for hydrazine, a n impu rity in technical grade maleic hydrazide. Estimated environmental fate values from TOXNET suggest that if released to air, a vapor pressure of 14.4 mm Hg at 25 o C indicates that hydrazine will exist solely in the vapor phase in the ambient atmosphere. Vapo r

- phase hydrazine is degraded in the atmosphere by reaction with photochemically produced hydroxyl radicals and ozone with estimated half

- lives of

3 See http://www.regulations.gov/#!documentDetail;D=EPA

- HQ

- OPPT

- 2009

- 0477

- 0074 for the final second list of
chemicals.

4 http://www.epa.gov/endo/Page 21 of 53

about 6 and 9 hours, respectively. Volatilization in water is not expected to be an important
environmental f

ate process for either the free base or the protonated species given the estimated Henry's law constant of the free base is 6.1X10

- 7 atm

- m 3 /mole and the fact that cations do not volatilize. Hydrazine is soluble in water based on an e stimated water solubili ty value of 1X10 6 mg/L. The estimated half

- life of hydrazine in pond water was about 8.3 days and degradation occurred through a combination of abiotic and biotic mechanisms.

Surface Water Impact Although available data indicate that maleic hydrazide degr ades rapidly under aerobic conditions (observed half

- life of <24 hours) and has a half

- life of less than two weeks in the field, maleic hydrazide residues were mobile to very mobile (up to 100% of the applied radioactivity was present in the leachate from sandy soil columns). Its persistence under anaerobic conditions could pose a risk of contamination of surface waters if maleic hydrazide were washed into anaerobic zones by rainfall events that occur soon after application. Because there is a potential
for surface water runoff, the following label advisory is required for all maleic hydrazide products that do not already contain this language ( e.g. Reg. Nos. 400

- 84 and 400

- 452) :

Surface water advisory: "Under some conditions, maleic hydrazide may have a si gnificant potential for runoff into surface water (primarily via dissolution in runoff water), for several days post

- application. Conditions favoring runoff include poorly draining soils or wet soils with readily visible slopes, frequently flooded areas, a reas where an intense or sustained rainfall is forecast to occur within 48 hours, areas overlying extremely shallow ground water, and areas overlying tile drainage systems that flow to surface water."

T able 6 lists the environmental fate properties of m aleic hydrazide , along with the major and minor degradates detected in the submitted environmental fate and transport studies

.

Table 6

. Summary of maleic hydrazide Environmental Fate Properties

Study Value (units) Major Degradates Minor Degradates MRID # Study Status and
Comments

Hydrolysis pH 3 : stable

pH 6 : stable pH 9: stable 00143322 A cceptable.

Direct Aqueous Photolysis (<10% degraded at 28

days)

- pH 5
Stable

- pH 7

t 1/2 >30 days at pH 9 42872301 42692101, 43141001,
43177301
00141951 A ccep table

Aerobic Soil
Metabolism (t 1/2 ) <24

hours Major: CO 2

( 70.59

- 72.59% of the applied at 90 days
posttreatment ) Minor: maleic acid
and maleimide , up to 3.70% and 0.96% 41896201 A cceptable

. U p to five
unidentified nonvolatile degradates were detected; however, none of these

were present at greater than 2.28% of the appliedPage 22 of 53 Study Value (units) Major Degradates Minor Degradates MRID # Study Status and
Comments

of the applied, respectively, each at 12 hours posttreatment

A na erobic Soil
Metabolism t 1/2 : 30

- 60 days Major: CO 2 (maximum of 68.31

- 72.23% of the applied after 60 days
of anaero bic incubation)

. Minor: maleic acid
and maleimide (maximums of 2.34%
and 0.58% of the applied, respectively,
at the start of anaerobic incubation). 41918201 A cceptable

. Minor degradates did not persist
under anaerobic
conditions

Kd

- ads (mL/g) 0.14 to 2.61 00151952 Supplemental. Aged (30

- day) maleic hydrazide residues were very mobile in sandy loam soil leached
under fast rain conditions (1 inch/hour) with 47.4%
of the applied radioactivity detected in
the leachate. Under slow
rain conditions (0.5 inch/da y)

. Terrestrial Field Dissipation (t 1/2 ) days 3 (bare ground)

5 (turf plots)

<14 (bare ground) <27 tobacco plots 42790901
42744801

42693301 Acceptable. M aleic

hydrazide was not
detected below the 30

- cm soil depth at either
location

.

Fish
Bioaccumul ation Bioconcentration factor

BCF (log Kow=

- 0.6 ) 00163301 Acceptable

3.1.2. Measures of Aquatic Exposure

Aquatic exposures are quantitatively estimated for all assessed uses using scenarios that represent high exposure sites for maleic hydrazide use.

Aquatic exposure modeling was performed using the tier 1 ecological exposure model Surface

Water Concentration Calculator (SWCC, 2014)

, because the toxicity endpoints were all “greater than”Page 23 of 53

values in the part

- per

- million range ( Table 12 ), and the m aximum application rate (13 lb/acre) was not expected to result in exposures in the ppm range.

Maleic hydrazide environmental fate data used for generating model parameters are listed in
Table 7

. Chemical property input values were chosen in accordance with current input
parameter guidance (USEPA, 2009 b )

.

Table 7 . Summary of SWCC Environmental Fate Data Used for Aquatic Exposure Inputs
for M aleic hydrazide

.
Fate Property Value (unit) MRID (or source) Comment

Application rate (lbai/A) 13 EPA Reg. No 400

- 94 (1)

No. Applications 1 EPA Reg. No 400

- 94 (1)

K oc 35 (mean of 5 values) 00151952 Surface Water
Concentration Calculator User Manual, 2014

Solubility in Water 4,507 mg/L @ 25 o C Tomlin, C.D.S. (ed.). The
Pesticide Manual

- World Compendium , 11 th ed., British Crop Protection Council, Surrey, England 1997, p. 757]

Photolysis in Water Stable 42872301 42692101, 43141001,

43177301
00141951

Aerobic Soil
Metabolism Half

- lives 3 days 41896201 Surface Water
Concentration Calculator

User Ma nual, 2014

Hydrolysis Stable 00143322

Aerobic Aquatic Metabolism (water column) 6 days No data Surface Water
Concentration Calculator User Manual, 2014

Chemical Application
Method Ground (spray) EPA Reg. No 400

- 94 (1)

Results from the SWCC mo del are presented in Table 8

. Output that generates peak EECs are reported in Appendix 1

.Page 24 of 53

Table 8 . Tier I Concentrations of Maleic hydrazide in Surface W ater

.

*: R epresents the crop with Max imum application rate (13 lb/acre)

3.1.3. Measures of Terrestrial Exposure

3.1.3.1. Terrestrial Animals

Ingestion of Food Items Base d on Foliar Application

Exposure estimates for terrestrial animals assumed to be in the target area or in an area exposed to spray drift are derived using the T

- REX 5 model (version 1.5.2

., 6/11/2013 ). This model incorporates the Kenaga nomograph, as modi fied by Fletcher et al. (1994), which is based on a large set of actual field residue data. The upper limit values from the nomograph represent an approximation of the highest residue value observed in the data set (Hoerger and Kenaga 1972).
Consideratio n is given to different types of feeding strategies for mammals and birds, including herbivores, insectivores and granivores. For dose

- based exposures, three weight classes of birds (20, 100, and 1000 g) and mammals (15, 35

, and 1000 g) are considered. Gi ven that no data on interception and subsequent dissipation from foliar surfaces are available for maleic hydrazide , a default foliar dissipation half

- life of 35 days is used based on the work of Willis and McDowell (1987). Th is assessment assumes a maxim um application rate of 1 3 lbs a.i./A and one application of maleic hydrazide per year (maximum labeled rate across all active labels) to estimate terrestrial exposure for this assessment. The dietary

- based EECs (upper bound Kenaga) on a variety of food
it ems from the use of maleic hydrazide applied at the maximum label rate is provided in Table 9 ; dose

- based EECs are provided in Table 10

.

Table 9 . T

- REX Calculated Dietary

- Based EECs of Maleic Hydrazide on Food Residues.

Food Type Agricultural Fallow/Id leland Use Site Maximum Dietary

- based EECs (mg/kg)

Short Grass 3120

Tall Grass 1430 Broadleaf plants 1755

5 USEPA. 2013. Pesticides: Science and Policy. Terrestrial Models, T

- REX Version 1.5.2 http://www.epa.gov/oppefed1/models/terrestrial/

Crop* Peak (μg/L) 21

- day average (μg/L) 60

- day average

(μg/L)

A gricultural / fallow/ idlelan d
conservation reserve 469 26 8 125Page 25 of 53

Fruits/pods/ seeds 1 95 Arthropods 1 222

Table 10 . T

- REX Calculated Maximum Dose

- Based EECs of Maleic Hydrazide Uses on
Terrestrial Food Residue s (Agricultural Fallow/Idleland/Conservation Reserve Use Sites)

Food Type Dose

- based EECs (mg/kg

- bw) (birds) Dose

- based EECs (mg/kg

- bw) (mammals)

Small (20 g) Medium

(100 g) Large

(1000 g) Small

(15 g) Medium

(35 g) Large

(1000 g) Short grass 3 553.4 202 6.3 907.2 2 974.7 2055.9 476.7 Tall grass 1 628.6 928.7 415.8 1 363.4 942.3 218.5 Broadleaf plants 1 998.8 1139.8 510.3 1 673.3 1156.5 268.1 Fruits/pod s 222.1 126.6 56.7 1 85.9 128.5 29.8 Arthropods 1 391.7 793.6 355.3 1 165.1 805.2 186.7 Seeds (granivore) 4 9 .4 28.1 12.6 41.3 28.6 6.6

3.1.3.2. Terrestrial Plants

Maleic hydrazide exposure to terrestrial and semi

- aquatic plants i s estimated using the TerrPlant 6
( v ersion 1.2. 2 ) model. The model generates EECs for plants residing near a use area that may be

ex posed via runoff and/or spray drift. The EECs are generated from one application at the maximum rate for a particular use and compound

- specific solubility information. Only a single application is considered because it is assumed that for plants, toxic e ffects are likely to manifest shortly after the initial exposure and that subsequent exposures do not contribute to the response. Hence, the model estimates EECs based on application rate, the solubility factor

, and default assumptions of drift. The EECs for terrestrial and semi

- aquatic plants for a single application of maleic hydrazide at the maximum label rate are presented in Table 1 1

.

Table 11

. Max EECs for Terrestrial and Semi

- Aquatic Plants Near Maleic Hydrazide Use
Areas.

Single Max. Applicatio n Rate (lbs a.i./A , Agricultural
Fallow/Idleland/Conservation Reserve Use Sites) EECs (lbs a.i./A)

Total Loading to Adjacent Dry Areas (sheet runoff + drift) Total Loading to
Semi

- Aquatic Areas (channelized runoff + drift) Drift EEC

Ground

spray Aer ial

spray Ground

spray Aerial

spray Ground

spray Aerial

spray
1 3 0. 78 1. 3 6. 63 7.15 0.1 3 0.6 5

6 USEPA. 2013a. Pesticides: Science and Policy. Terrestrial Models, TerrPlant Version 1.2.2

. http://www.epa.gov/oppefed1/models/terrestrial/Page 26 of 53 3.2. Ecological Effects Characterization

The ecological effects characterization for maleic hydrazide is based on data generated from guideline studies submitted by the registrant and from open literature studies in the ECOTOX database (http:/www/epa.gov/ecotox).

A brief description of available aquatic and terrestrial toxicity data used to calculate RQs is provided below in Sections 3.2.1 and 3.2.2

. As noted in Section 3.2.3, there are currently no reported ecological incidents involving maleic hydrazide

.

3.2.1. Aquatic Effects Characterization

Aquatic toxicity data for animals and plants are summarized in Table 1 2

. For freshwater and

est uarine/marine fish and invertebrates (and for aquatic

- phase amphibians, for which fish are considered surrogates)

, the compound is considered practically non

- toxic. Several of the aquatic studies conducted using maleic hydrazide experienced highly acidic conditions in the highest

treatment c oncentrations tested and adequately buffered maleic hydrazide standards were not used. Where this occurred, it is unclear whether effects observed were due to the inherent toxicity of the
test chemical or were rather due to the acidity in the test system. However, treatment related effects were not seen in these studies except at very high concentrations that are unlikely to be achieved under current use patterns.

The most sensitive acute endpoint for estuarine/mar ine fish was an LC 50 > 104,000 μg a.i./L (the highest treatment level tested) for sheepshead minnow in a s tudy using maleic hydrazide’s potassium salt where no mortality or sublethal effects were observed at any test concentration. In a recently submitted acute study on the fathead minnow (MRID 48876701 ), the LC 50 was also
considered non

- definitive due to the highly acidic concentrations at the higher test concentrations. However, no treatment related mortalities or sublethal effects were seen at concentr ations up to 240,000 μg a.i./L in this study. It was unclear whether the mortality and sublethal effects, including fish on the bottom of the test vessel and fin deterioration, observed at the higher test
concentrations were due to the acidic conditions ( pH declined to below 5.0 at 460,000 and 930,000 μg a.i./L) or to the toxicity of the chemical at those concentrations. An acute toxicological study with the potassium salt did not indicate any toxicity differentials between the salt and the acid (MRIDs 001 46142, 00124739 ) to rainbow trout. On a chronic exposure basis, maleic hydrazide was tested at concentrations up to 9,600 μg a.i./L without any treatment related effects to fathead
minnow. No chronic studies have been conducted with an estuarine/marine f ish species and an ACR (acute to chronic ratio) approach cannot be used due to nondefinitive endpoints. However, considering the lack of acute effects in both freshwater and saltwater fish species (and no other indication that estuarine/marine species may be more sensitive compared to freshwater species), and the lack of chronic effects observed in the fathead minnow early life stage study, the chronic NOAEC established for freshwater fish species (9,600 μg a.i./L) will also be used to assess risk to

estuar ine/marine fish species in this risk assessment.

In an acute freshwater invertebrate study with Daphnia magna (MRID 00124741), the EC 50 was determined to be 107,500 μg a.i./L, and there was no increase in mortality compared to controls atPage 27 of 53

concentration l ess than 100,000 μg a.i./L. It was unclear whether some of the mortality observed at the higher test concentrations (100,000 and 180,000 μg a.i./L) was due to the toxicity of the test compound or the acidic conditions present at the highest test concentra tions (pH declined to 5.41 in the highest test concentration)

. The potassium salt of maleic hydrazide did not appear to have any increased toxicity to daphnids with an LC 50 greater than 1,000,000 μg a.i./ L (MRID 00146143). On a chronic exposure basis, mal eic hydrazide was tested at concentrations up to

9 9,0 00 μg a.i./L without any treatment related effects to daphnids (MRID 48876702). Similarly,

no mortality or sublethal effects were observed in an acute mysid study (MRID 44411103) using the potassium sal t , tested at concentrations up to 103,000 μg a.i./L . No mortality was observed in an acute eastern oyster study (MRID 44411102), and the IC 50 was considered to be > 111,000 μg a.i./L however a statistically significant (18%) inhibition on shell growth was observed above the 73,200 μg a.i./L (LOAEC = 111,000 μg a.i./L) treatment level. No chronic studies have been
conducted with an estuarine/marine invertebrate and an ACR approach cannot be used due to nondefinitive endpoints. However, considering the lack of acute effects in both freshwater and saltwater invertebrate studies and the lack of chronic effects in the daphnid life cycle test, the chronic NOAEC established for freshwater invertebrate species (99,000 μg a.i./L) will also be used
to evaluate risk for estuarine/marine species in this risk assessment.

Aquatic vascular and nonvascular plants were also relatively in sensitive to maleic hydrazide . The

14

- day NOAEC and EC 50 values for the vascular aquatic plant duckweed ( Lemna gibba) were 23,700 μg a.i

. /L and 114,000 μg a.i. /L, respectively (MRID 43006904) based on reduced front

count

. Of the four nonvascular algal species tested, none had a definitive EC 50 value, with nondefinite values ranging from > 9,840 to > 102,000 μg a.i./L. . The most sensiti ve definitive
NOAEC value for a nonvascular aquatic plant was for blue

- green algae ( Anabaena flos aquae )
with a NOAEC of 60,000 μg a.i./ L based on reduced cell density at the LOAEC of 95,000 μg a.i./L.

Table 1 2 . Summary of Most Sensitive Acute and Chroni c Toxicity Data for Aquatic
A nimals Exposed to either Maleic Hydrazide Acid or Potassium Salt

. Bolded values represent the endpoints used for risk estimation.

Species TGAI/

TEP (% a.i.) Acute Toxicity Chronic Toxicity

96

- hr
LC 50 /EC 50 (μg a.i./L) 48

- h r EC 50

(μg a.i./L) Toxicity

Classification (MRID , study
classification ) NOAEC/

LOAEC (μg a.i./L) Endpoints

(MRID , study
classification )

Rainbow trout Oncorhynchus mykiss TGAI
%a.i. not reported 1,608,000

-- Practically non

toxic (00124739

, Acceptable ) No Data N/A

Fathead minnow Pimephales promelas TGAI
100% a.i.
Acid > 240,000

- - Practically non

toxic (48876701

, Supplemental

-- Qualitative ) 9,600 /

> 9,600 None affecected

(48876702

, Acceptable )

Waterflea Daphnia magna TGAI
% a.i. not reported -- 107,500 Practically non

toxic (00124741

, Acceptable ) 99,000 /

> 99,000 None Affected

(48877502

, Acceptable )Page 28 of 53 Species TGAI/

TEP (% a.i.) Acute Toxicity Chronic Toxicity

96

- hr
LC 50 /EC 50 (μg a.i./L) 48

- h r EC 50

(μg a.i./L) Toxicity

Classification (MRID , study
classification ) NOAEC/

LOAEC (μg a.i./L) Endpoints

(MRID , study
classification )

Sheepshead minnow Cyprinodon variegatu s TGAI
98.98% a.i.
Potassium
Salt > 104,000

-- Practically non

toxic (44411101, Supplemental

-- Quantitative) No Data N/A

Mysid shrimp Americamysis bahia TGAI
98.98% a.i.
Potassium
Salt > 103,000

-- Practically non

toxic (44411103) No Data N/A

Eastern oyster

Crassostrea v irginia TGAI
98.98% a.i.
Potassium
Salt > 111,000

-- Practically non

toxic ( 44411102 ) No Data N /A

Aquatic Plants

Duckweed Lemna gibba TGAI
98.98% a.i.
Potassium
Salt N / A N / A N / A 14

- day EC 50

= 114,000

14

- d

NOAEC/
LOAEC = 23,700 / 38,600 Frond numbers

(43006904

, Acceptable )

Blue

- green algae Anabaena flos

- aquae TGAI
98.98% a.i.
Potassium
Salt N / A N / A N / A 96

- hr IC 50 > 95,000
NOAEC/

LOAEC = 60,000 / 95,000 Cell numbers

(43006901, Acceptable)

3.2.2. Terrestrial Effects Characterization

Toxicity values for terrestrial animals and plants are summarized in Tables 1 3 and 1 4

, respectively

. Maleic h ydrazide is practically non

- toxic to mammals, birds (and to reptiles and
terrestrial

- phase amphibians for which birds serve as surrogates) , and honey bees ( Apis mellifera ) on an acute exposure basis

. No sublethal effects or mortalities were observed in ei ther the acute
bird or mammalian studies. In one avian acute oral study (MRID 00124742), a slight, non

statistically significant reduction in body weight gain was observed at the 2150 and 4640 mg/kg
treatment levels. Sub

- acute dietary studies with both t he bobwhite and mallard (MRIDs 00126033
and 00107417 ) found no mortality or sublethal effects at the highest treatment level tested (10,000 mg/kg

- diet). The non

- definitive highest treatment concentrations from these acute studies will be conservatively us ed as the acute endp oints (LD 50 /LC 50 ) for risk estimation in this risk assessment.

In a chronic two generation mammalian reproduction stud y with two litters per generation, the potassium salt of maleic hydrazide was incorporated continuously in the feed o f male and female Sprague

- Dawley rats for two successive generations at dietary concentrations of 0,1000, 10,000, 30,000 and 50,000 ppm. The 50,000 ppm treatment group was discontinued during the study afterPage 29 of 53

the F 1 generation due to decreased body weights noted in both the 30,000 and 50,000 ppm F 0 adults
and F 1 pups during lactation. The NOAEL, based on reduced body weights of F 0 females at 30,000 ppm (8.5% inhibition) was considered to be 10,000 ppm. Additional effects observed at the 50,000 ppm treatm ent level included F 1 pup weights (21

— 24% inhibition) and F 2 pup weights (9

- 11% inhibition). No reproductive effects were observed in either male or female animals at any dietary level.

No chronic avian reproduction data is available

. The 1994 RED state d that “Avian reproduction studies are not required for maleic hydrazide because it is not applied more than once prior to or during the breeding season, and it is practically nontoxic to birds” and the 2009 Problem Formulation (USEPA, 2009) did not indica te this as a data gap. Given a lack of acute mortality or
sublethal effects in all tested terrestrial animals and no terrestrial animal incident data, there is no indication of a strong likelihood of chronic effects to avian species at the concentrations of maleic hydrazide expected on the field or dietary items

. N o reproductive effects were observed in the mammalian chronic study discussed above. However, d ue to the lack of chronic avian data and
the observed effects on body weight in the mammalian chro nic reproduction study (discussed above) , there is uncertainty around the potential for chronic effects to birds and chronic risk to avian species cannot be precluded.

In an acute study with honey bees (MRID 00018842) exposed to the MH

- 30 © formulation (% a.i. not reported), the LD 50 was reported to be > 36.26 μg/bee, with only 3.2% mortality at the limit concentration. Two nonguideline studies (MRIDs 44990001 & 44990002) were submitted with additional terrestrial invertebrate data. Parasitic wasps ( Aphid ius rhopalosiphi ) and predatory mites ( Typhlodromus pyri ) exposed to the Royal MH

- 60 SG formulation (60.2% ai maleic hydrazide , formulation not registered in the U.S. ) applied at 4.45 lbs ai/A experienced 68% mortality in wasps after 48 hours and 47% morta lity of mites after 24 hours (50% mortality after 7 days). Additional sublethal effects included reduced coordination in the wasp study.

Tier II seedling emergence and vegetative vigor testing was conducted with a typical end

- use product (TEP) containi ng 30.2% maleic hydrazide potassium salt (23% maleic hydrazide acid equivalents ). Onion was the most sensitive monocot species in both the seedling emergence and vegetative vigor studies with a NOAEC and EC 25 of 0.38 and 0.53 lbs ai/A, respectively, for

s eedling emergence and 0.38 and 1.44 lbs ai/A, respectively, for vegetative vigor. Tomato was the most sensitive dicot in the seedling emergence test with a NOAEC and EC 25 of 0.75 and 1.03, respectively. Cabbage was the most sensitive dicot in the vegetat ive vigor study with a NOAEC
and EC 25 of 0.75 and 1.10, respectively.Page 30 of 53

Table 13 . Maleic Hydrazide Acid and Potassium Salt Terrestrial Animal Toxicity Summary . Bolded values indicate endpoints used in risk estimation.

Parameter Study Type Species Exposu re Duration TGAI/

TEP (% a.i.) Toxicity

Value /End point
Affected Reference

Toxicity
Classification/ Study
Classification

1.
Abundance ( i.e ., survival, reproduction, and growth)
of individual
birds 1a. Acute

(Dose

based) Mallard duck

Anas platyrhy nchos Single oral

dose TGAI

% a.i. not reported
Acid >4

, 640

mg/kg bw (LD 50 ) /
No effect 00124742

Practically

non

- toxic/ Acceptable

Mallard duck

A. platyrhynchos Single oral

dose TEP

34.5% a.i.
Potassium
Salt > 2

, 250

mg/kg bw (LD 50 ) /No
effect 00146141

Pra ctically

non

- toxic/ Acceptable

Canary

Serinus canaria Single oral

dose TGAI

100% a.i.
Acid >2,000

mg/kg bw (LD 50 ) / No
effect 48877501

Practically

non

- toxic/ Acceptable

1b. Acute (Dietary

based) Northern

Bobwhite
Colinus virginianus 8

- Day

dietary TGA I

% a.i. not reported > 10,000

mg/kg diet (LC 50 ) /No
effect 00126033

Practically

non

- toxic/ Acceptable

Mallard duck A. platyrhynchos 8

- Day

dietary TGAI

% a.i.
Acid > 10,000

mg/kg diet (LC 50 ) / No
effect 00107417

Practically

non

- toxic/ Acceptable

Mallar d duck A. platyrhynchos 8

- Day

dietary TEP

34.5% a.i.
Potassium
Salt >5620

mg/kg diet (LC 50 ) /No
effect 00147000

Practically

non

- toxic/ Acceptable

1c. Chronic (Dietary

based) Northern

bobwhite ( C. virginianus ) and Mallard Duck (

A. platyrhynchos ) Avian

reproduction study No Data No Data N/A

2.
Abundance ( i.e ., survival, reproduction, and growth)
of individual
mammal 2a. Acute Rat ( Rattus norvegicus ) Single oral

dose >5,000 mg/kg bw (LD 50 ) 00079657,

00079658, 41185401, 00079661, 00079660, and
41289101 Practically

non

- toxic/ AcceptablePage 31 of 53 Parameter Study Type Species Exposu re Duration TGAI/

TEP (% a.i.) Toxicity

Value /End point
Affected Reference

Toxicity
Classification/ Study
Classification

2b. Chronic Rat ( Rattus

orvegicus ) 2

- Generation

reproduction study 10,000 mg/kg

- diet (NOAEL)
LOAEL = 30,000 mg/kg

- diet
based on
decreased
F0 body weight 00128720

(Core

minimum)

3. Survival of
beneficial
insects 3a. Acute

Contact Honey Bee

( Apis mellifera ) 48 hours TEP
% a.i. not reported > 36.26

μg/bee (LD 50 ) / Mortality 00018842

Practically

non

- toxic/ Acceptable

Table 14 . Summary of Tier I I Terrestrial Plant Toxicity Data for Maleic Hydrazide
Potassium Salt

C rop Species EC 25 (lbs a.i./A) NOAEC (lbs

a.i./A) Most

sensitive parameter MRID

Seedling Emergence

Monocots Oat 1.3 5 < 0.375 Plant Height 41289301

Ryegrass 2.52 1.5 Plant Height 41289301

Corn 3.02 1.5 Plant Height 41289301

Onion 0.53 0.3 8 Plant Heig ht 41289301

Dicots Lettuce 2.7 7 1.5 Plant Height 41289301

Soybean 1.09 0.75 Dry Weight 41289301

Carrot > 6.0 6.0 NA 41289301

Tomato 1.03 0.75 Dry Weight 41289301

Cucumber >6.0 6.0 NA 41289301 Cabbage 1.0 7 0.75 Dry Weight 41289301

Vegetative Vigo r

Monocots Oat 1.95 1.50 Plant Height, Dry Weight 41289302

Ryegrass 4.87 3.00 Plant Height 41289302

Corn 4.01 1.50 Plant Height 41289302

Onion 1.44 0.38 Plant Height 41289302

Dicots Soybean 2.31 0.38 Phytotoxicity 41289302

Carrot 4.73 0.75 Phyto toxicity 41289302

Tomato 4.71 1.50 Plant Height, Phytotoxicity 41289302

Cucumber 4.63 1.50 Plant Height, 41289302Page 32 of 53 Phytotoxicity Cabbage 1.10 0.75 Dry Weight, Phytotoxicity 41289302

Lettuce 2.22 0.75 Plant Height, Dry Weight 41289302

3.2.3. Revi ew of Incident Data

A review of the Environmental Incident Information System (EIIS , version 2.1 .1 ) database and the Incident Data System (IDS) database , which are maintained by the Agency’s Office of Pesticide Programs, and the Avian Monitoring Informati on System (AIMS), which is maintained by the American Bird Conservancy, for ecological incidents involving maleic hydrazide acid and potassium salt was completed on March 11, 2014

. The results o f this review show no reported
incidents.

However, because of limitations in the incident reporting system, the lack of incident reports cannot be construed as the absence of incidents from the registered use of maleic hydrazide

. Reporting by states is only voluntary, and individuals discovering incidents may not be informed on the procedure of reporting these occurrences. Additionally, much of the se database s are generated from registrant

- submitted incident reports. In addition, incident reports for non

- target organisms typically provide information only on morta lity events and plant damage incidents. Impacts to non

- commercial beneficial insects and other invertebrates are not likely to be reported. Except for phytotoxic effects in terrestrial plants, sublethal effects for organisms such as reduced growth or impa ired reproduction are rarely reported. Because of these logistical difficulties, EIIS is most likely a minimal representation of all pesticide

- related ecological incidents and the absence of incident reports cannot be construed as the absence of incident s

.

4. Risk Characterization

4.1. Risk Estimation

4.1.1. Aquatic Organisms

The peak EEC s in surface water generated from the SWCC model (using the maximum application
rate from agricultural fallow/idle land/conservation reserve , the use site with the highest rates) represents acute exposure to fish, aquatic invertebrates, and aquatic plants, and the highest 21

- day
and 60

- day average EEC s represents chronic exposure to aquatic invertebrates and fish

, respectively

. Acute and chronic RQs for fresh water and estuarine/marine animals and aquatic vascular and nonvascular plants are summarized in Table 1 5

.Page 33 of 53 4.1.1.1. Aquatic Animals

Fish

There were no exceedances of any LOC for acute or chronic risk to freshwater or estuarine/marine
fish. Since no chron ic data was available for estuarine/marine fish and no acute mortality or
sublethal effects were observed in either the acute freshwater or saltwater fish studies and neither were effects observed in the chronic freshwater fish early life stage study, the chronic endpoint from the fathead minnow ELS study was used to estimate chronic risk to estuarine/marine fish.

Aquatic invertebrates

There were no exceedances of any LOC for acute or chronic risk to freshwater or estuarine/marine
invertebrates. Since no chronic data was available for estuarine/marine invertebrates and no acute mortality or sublethal effects were observed in either the acute daphnid or mysid studies , the chronic endpoint from the daphnid life cycle study was used to estimate chronic ris k
estuarine/marine invertebrates.

Aquatic Plants

As shown in Table 1 5

, RQs for vascular and nonvascular plants do not exceed any LOCs (1.0) for any of the currently registered uses of maleic hydrazide, as evidenced by the RQs derived from
the most c onservative exposure scenario ( i.e.

, Agricultural Fallow/Idleland/Conservation Reserve
at the maximum rate of 1 3 lbs a.i./A), which do not result in LOC exceedances.

Table 1 5 . Summary of Acute and Chronic RQs for Freshwater and Estuarine/Marine Fish,

I nvertebrates and Aquatic Plants Exposed to Maleic Hydrazide (Maximum EECs b ased on
the Agricultural Fallow/Idleland/Conservation Reserve Use Pattern )
Species Toxicity Endpoint (ppb) Maximum

EECs Maximum

RQs

Freshwater Fish:
Fathead Minnow ( Pimmephal es promelas ) Acute > 240,000 469 < 0.01

Chronic 9,600 1 25 0.01

Saltwater Fish: Sheepshead minnow ( Cyprinodon variegatus ) Acute > 104,000 469 < 0.01

Chronic 9,6 00 1 1 25 0.01

Freshwater Invertebrates:
Waterflea ( Daphnia magna ) Acute 107,500 469 < 0.0 1

Chronic 99,000 26 8 < 0.01

Saltwater Invertebrates: Mysid shrimp (Americamysis bahia) Acute > 103 ,000 469 < 0.01

Chronic 99,000 2 26 8 < 0.01

Aquatic Non

- Vascular
Plant
Blue

- green algae ( Anabaena flos

- aquae ) Non

Listed > 95,000 469 < 0.01

Listed 60,000 469 < 0.01

Aquatic Vascular Plants: Duckweed ( Lemna gibba ) Non

- listed 114,000 469 < 0.01

Listed 23,700 469 0.0 2Page 34 of 53 * EECs are estimated surface water concentrations based on SWCC model runs.

1 No chronic data was available for estuarine/marine f ish. Since no acute effects were observed in either the acute freshwater or saltwater fish studies, the chronic freshwater fish NOAEC is used in place of an
estuarine/marine fish NOAEC.

2 No chronic data was available for estuarine/marine invertebrates. S ince no acute mortality was observed in either the acute freshwater or saltwater invertebrate studies, the chronic freshwater NOAEC is used in place
of an estuarine/marine invertebrate NOAEC.

4.1.2. Terrestrial Organisms

4.1.2.1. Terrestrial Animals

Ingestion of Food Items Based on Foliar Application

Based on the available toxicity data, no acute mortality and/or sublethal effects were observed in any of the avian or mammalian studies at the highest levels tested. O nly non

- definitive (“greater

than ”) acute and sub

- acute toxicity endpoints are available for birds and mammals ; therefore, the

acute RQs presented in Ta ble 1 6 are also non

- definitive (“less than”) maximum RQs

. Further discussion of the predicted exposure values relative to the lev els at which no mortality occurred is provided as part of the risk description in Section 4.2.2

. No chronic avian data was available to quantitatively evaluate chro nic risk to birds , therefore chronic risk to birds is uncertain.

Using the non

- definitive acute oral LD 50 as a conservative endpoint for birds (the canary LD 50 of > 2,000 mg/kg

- bw and the test organism body weight of 24.5 g) and for the maximum applicati on rate across all use sites (1 3 lbs ai/A for Agricultural Fallow )

, exceedances of t he non

listed species dose

- based LOC (0.5) occur for small birds feeding on short grass, tall grass, broadleaf plants and arthropods (RQs range from 0. 72 to 1. 83 ), and medi um birds feeding on short grass (RQ = 0. 82 ). The listed species dose

- based LOC (0.1) is exceeded for small birds feeding on all dietary items except for granivores (RQs range from 0.11 to 1. 83 ), medium birds feeding on all dietary items except for fruits/ pods/seeds and granivores (RQs range from 0.3 2 to 0. 82 ), and large birds feeding on all dietary items except for fruits/pods/seeds and granivores (RQs range from 0.1 0 to 0.2 6 ). Using the non

- definitive sub

- acute dietary endpoint for birds, the listed speci es dietary

- based LOC (0.1) is exceeded for birds consuming all dietary items except for fruits/pods/seeds (RQs range from 0.0 2 to 0. 31 ) , but the non

- listed species LOC (0.5) was only marginally exceeded for birds feeding on short grass (RQ = 0.56 )

.

Using the non

- definitive acute en dpoints for mammals and for the maximum application rate across all use sites (1 3 lbs ai/A for Agricultural Fallow ) , there were no exceedances of the non

listed species LOC. Exceedances of the listed species LOC (0.1) were gener ally marginal and occured for all size classes of mammals feeding on short grass (RQs range from 0.1 2 to 0.2 7 ), small and medium mammals feeding on tall grass and broadleaf plants (RQs range from 0.1 1 to 0.1 5 ), and small mammals feeding on arthropods (RQ = 0.1 1 ). The chronic dose

- based LOC (1.0) is exceeded for all size classes of mammals consuming short grass (RQs range from 1. 2 4 to 2. 71

, small and medium mammals consuming broadleaf plants and tall grass (RQs range from
1. 06 to 1.52 , respectively) and s mall mammals consuming arthropods (RQ = 1.06 ) and the chronic dietary

- based LOC (1.0) was not exceeded for mammals (RQ s 0.02

— 0. 31 )Page 35 of 53

Lower application rates associated with other uses of maleic hydrazide result in less uncertainty regarding the potential f

or risk. As t he resulting EECs from lower application rates decrease and approach the highest doses tested in the non

- definitive acute studies, EFED has greater confidence that the potential for risk is low. For example, under the ornament al and shade tre es use pattern (maximum application rate of 9.2 lbs ai/A), there is no longer an y expectation for acute or chronic risk to large mammals feeding on short grass as the non

- definitive endpoints
exceed the EEC for this use

. Under the tobacco use pattern (max imum application rate of 6.1 lbs
a.i./A ) anticipated acute risk becomes very low to birds from d ietary exposure to residues on broadleaf plants as the non

- definitive endpoints exceed the EEC for this use site

. Under the Ornamental Woody Shrubs use patte rn (maximum application rate of 4.6 lbs a.i./A, anticipated
acute risk becomes very low for large birds or medium mammals and chronic risk would not be expected for any mammalian size classes

. Under the potato use pattern (maximum application
rate of 4 .3 lbs ai/A), the anticipated risk becomes low for all listed and non

- listed mammal s

. Under the onion use pattern (maximum application rate of 2.9 lbs ai/A, the anticipated acute risk
becomes low for all non

- listed avian species. A full comparison of what e xceedances occur under the different use patterns is described in the beginning of this assessment in Table 1 and in Appendix 3

.Page 36 of 53

Table 1 6

. Maximum Acute and Chronic Risk Estimates to Birds and Mammals fro m the Maximum Application Rates by Use

Pattern

Use Site (Maximum Application Rate)

Agri

cultural
Fallow (13 lbs ai/A) Orna

mental
Shade

Trees (9.2 lbs ai/A) Golf Course

Turf (8 lbs
ai/A ) Tobacco

(6.1 lbs ai/A) Orna

mental Woody Shrubs (4.6 lbs ai/A) Potato

(4.3 lbs ai/A) Onion (2.9

lbs ai/A)

Ac ute: Dose

- Based

Birds 20 g Short G rass , Tall Grass, Broadleaf

Plants, Fruits/Pods, Arthropods 0.0 3

— 1.83 0.02

— 1. 30 0.0 2

— 1.13 0.01

— 0.86 0.01

— 0.65 0.01

— 0.61 0.01

— 0.41

100 g Short Grass, Tall Grass, Broadleaf

Plants, Arthropods 0.01

— 0. 82 0.01

— 0.5 8 0.01

— 0.50 0.01

— 0.38 <0.01

— 0.29 <0.01

— 0.27 <0.01

— 0.18

1000 g Short Grass, Tall Grass, Broadleaf

Plants, Arthropods < 0.01

— 0.2 6 < 0.01

— 0.1 8 <0.0 1

— 0.16 <0.01

— 0.12 <0 .10 <0.10 <0.07

Mammals 15 g Short grass , Tall Grass, Broadleaf Plants, Arthropods <0.01

— 0.2 7 < 0.01

— 0 .1 9 <0.0 1

— 0.17 <0.01

— 0.13 <0.01

— 0.10 <0.10 <0.07

35 g Short Grass, Tall Grass, Broadleaf

Plants < 0.01

— 0.2 3 < 0.01

— 0.1 6 <0.0 1

— 0.14 <0.01

— 0.11 <0.08 <0.09 <0.06

1000 g Short Grass < 0.01

-- 0.1 2 <0.01

— 0.0 9 <0.0 8 <0.06 <0.04 <0.05 <0.04

Acute: Dietary

- Based

Birds N/A Short Grass, Tall Grass, Broadleaf Plants, Arthropods 0.02

— 0.56 0.01

— 0.39 0.01

— 0. 34 0.01

— 0. 26 0.01

— 0. 20 0.01

— 0.18 0.01

— 0.12

Chronic : Dose

- Based

Mammals 15 g Short G rass, Tall Grass, Broadleaf

P lant s, Arthropods 0.0 4

— 2. 71 0.0 3

— 1. 92 0.02

— 1.67 0. 02

— 1.27 <0.9 7 <0.91 <0.61

35g Short Grass, Tall Grass Broadleaf
Plants 0.03

— 2. 31 0.02

— 1. 6 4 0.02

— 1.42 0.02

— 1.08 <0.8 3 <0.77 <0.53

1000g Short Grass 0.02

-- 1. 2 4 0.01

— 0. 88 <0. 76 <0.58 <0.4 5 <0.42 <0.29

1 Food indicates the dietary items for which LOC exce edances occur for the highest use pattern (Agricultural Fallow) only.

2 RQs in bold exceed the non

- listed species LOC. RQs in bold italics exceed only the listed species LOC.Page 37 of 53 4.1.2.3. Terrestrial Invertebrates

On an acute exposure basis, maleic hydrazid e is classified as ‘practically nontoxic’ to non

- target
terrestrial insects including honey bees ( honey bee acute contact LD 50 > 36.26 μg ai/bee , with only 3.2% mortality at the limit dose ). If an RQ were calculated for terrestrial invertebrates 7

,
conserva tively assuming the LD 50 to be 36.26 μg ai/bee and the acute contact exposure to be the application rate (13 lbs a.i./A) * 2.7 μg a.i./bee or 3 5

. 1 μg, the resultant RQ would be 0.97 or approximately two times the proposed terrestrial invertebrate LOC (0.4 ). The proposed non

- listed species LOC would also be exceeded for use patterns w ith maximum application rates greater than
6.1 lbs a.i./A ( e.g. tobacco with an RQ > 0. 45 ) . The ornamental woody shrubs and vines, potato, onion and citrus use patterns would not exceed the proposed non

- listed species LOC, but would exceed the interim listed species LOC of 0.05 (RQs would range from 0.13

– 0.30 ) . A full comparison of what exceedances occur and the resulting risk picture under the different use patterns is descr ibed at the beginning of this assessment in Table 1 and Appendix 3

.

4.1.2.4. Plants

The RQs for terrestrial and semi

- aquatic plants for a single application of maleic hydrazide at the
maximum labeled rate of 1 3 lbs a.i./A under both ground and aerial app lication scenarios is presented in Table 17

. RQs were exceeded for listed and non

- listed monocots in both dry and
semi

- aquatic areas under both ground and aerial application scenarios. RQs were also exceeded
for listed and non

- listed monocots due to spra y drift for aerial applications only. For dicot plant species, RQs were exceeded for listed and non

- listed species in semi

- aquatic areas from both ground and aerial application scenarios, but RQs were only exceeded for listed and non

- listed species in dry areas under aerial application scenarios and marginally exceeded (RQ = 1.04 ) for listed dicots under ground application scenarios . Spray drift alone did not result in any exceedances for dicot species.

Risk to plant species is may be less for other us e patterns. For example, for ornamental and/or
shade tree s (maximum application rate of 9.2 lbs a.i./A applied aerially ), non

- listed dicots are no longer at risk in dry areas (RQ = 0.89 ) and non

- listed monocots no longer exceed the spray drift
LOC (RQ = 0

. 87 )

. Under the golf course turf use pattern (maximum application rate of 8.0 lbs
a.i./A ), using ground applications only, non

- listed monocots in dry areas no longer exceed the LOC (RQ = 0.91). Under the tobacco use pattern (maximum application rate of 6.1 lbs a.i./A), using ground applications only, no listed or non

- listed monocot or dicot in dry areas would exceed the LOC (Max RQ = 0.96) while for aerial application scenarios there would no longer be exceedances for listed dicots in dry areas or listed monocots from spray drift alone. For the Ornamental Woody Shrubs and vines use pattern (maximum application rate of 4.6 lbs a.i./A) with aerial applications,

non

- listed monocots in dry habitats would no longer be at risk. For aerial applications on onio ns (maximum application rate of 2.9 lbs a.i./A), listed monocots in dry areas would also no longer
have exceedances. However, e ven if applied by ground applications only, both listed and non

listed monocots and dicots in semi

- aquatic areas would be consid ered at risk under the maximum

7 The employed methodology for calculating an RQ for pollinators was first proposed in the 2012 Pollinator Risk
Assessment Framework SAP Whit e Paper, and subsequently validated by the panel. The White Paper is accessible online at regulations.gov, under docket EPA

- HQ

- OPP

- 2012

- 0543Page 38 of 53

application rate in all use patterns, except for non

- listed dicots (RQ of 0.9 4 ) under the citrus use pattern only. A full comparison of what exceedances occur under the different use patterns is
described in the executive su mmary in Table 1 and in Appendix 3

.

Table 17 . RQ values for plants in dry and semi

- aquatic areas exposed to Maleic Hydrazide through runoff and/or spray drift from the maximum application rate of 1 3 lbs a.i./A for Agricultural Fallow

.

Plant Type Listed S tatus Dry Semi

- Aquatic Spray Drift

Ground Aerial Ground Aerial Ground Aerial

Monocot non

- listed 1.47 2.45 12.51 13.49 0.25 1.2 3

Monocot L isted 2.05 3.42 17.45 18.82 0.34 1.71

Dicot non

- listed 0.76 1.26 6.44 6.94 0.13 0.63

Dicot listed 1.04 1.73 8. 84 9.53 0.17 0.87

*If RQ > 1.0, the LOC is exceeded, resulting in potential for risk to that plant group.

4.2. Risk Description

The results of this screening

- level risk assessment indicate that the registered uses of maleic hydrazide do not have the p otential to cause direct adverse acute or chronic effects to freshwater
and estuarine/marine fish and invertebrates or adverse effects to aquatic vascular and non

- vascular plants

. Maleic hydrazide is not acutely toxic to avian or mammalian species, howeve r doses tested were not high enough to capture toxic effects at predicted maximum EEC s . As a result , s ince
terrestrial EECs exceed 1 / 10 and 1⁄2 the tested doses, acute risk to listed and non

- listed avian and mammalian species cannot be precluded

, though the levels of risk estimated may be overly
conservative . Chronic risk is indicated for mammals, though this varies depending on the size class and dietary item consumed. Chronic risk to birds is uncertain due to the lack of avian reproduction data.

Risk t o monocots is indicated regardless of habitat or application method, although spray drift alone will not result in risk when only ground applications are used. Non

- listed d icots are mainly
considered at risk in semi

- aquatic habitats and where aerial appli cations are used in dry areas (there is only a marginal exceedance, RQ = 1.04 for listed dicots in dry areas under ground application scenarios)

.

4.2.1 . Risks to Aquatic Organisms

Predicted EEC values are expected to be several orders of magnitude lower than any ecotoxicity endpoints for aquatic animals and plants. Although no chronic data are available for a saltwater fish species, the freshwater fish NOAEC was used for risk estimation. E stuarine/marine fish species would have to be several orde rs (~2

- 3 orders) of magnitude more sensitive than freshwater fish on a chronic basis in order to exceed the listed species LOC. Therefore, even if estuarine/marine fish were to be more sensitive on a chronic basis, there is sufficient distance between pot ential chronic endpoints and EECs to consider risk to this taxa low.Page 39 of 53

Since no chronic data was available for estuarine/marine invertebrates and no acute mortality or sublethal effects were observed in either the acute daphnid or mysid studies

, and there is no other indication that estuarine/marine species are more sensitive than freshwater species, the chronic endpoint from the daphnid life cycle study was used to estimate chronic risk estuarine/marine invertebrates. Sublethal effects (diminished shell gr owth) was observed in the Eastern oyster acute study, therefore it is possible that using the chronic daphnid endpoint underestimates risk to this taxa and other bivalves. However, for the chronic LOC to be exceeded, bivalve taxa would need
to be several orders (~ 3 orders) of magnitude more sensitive than daphnids or mysids on a chronic basis. Given that the sublethal effects observed in the acute oyster study were only observed at very high concentrations (NOEC = 73,200 μg a.i/L), chronic risk to this ta xa is considered highly unlikely given current use patterns.

No aquatic toxicological data has been evaluated for the impurity hydrazine. Although no ecotoxicological information has been evaluated by EFED for hydrazine, the Hazardous
Substances Data B ank database accessible via Toxnet ( http://toxnet.nlm.nih.gov/ does contain unreviewed ecotoxicity data. The most sensitive fish and aquatic invertebrate acute endpoints recorded in this database are 610 μg a.i./ L for the guppy ( Lebistes reticulatus ) and 160 μg a.i./L for the waterflea ( D. pulex ). The most sensitive aquatic plant endpoint recorded in this database

was a 96

- hr EC 50 of 0.02 ug a.i./L for green algae ( S. capricornutum ). These toxicity values are

se veral orders of magnitude (at least 3 orders) more sensitive than for maleic hydrazide. For most of the older aquatic maleic hydrazide toxicological data, hydrazine was not analyzed for in the test material. Newer aquatic studies with the fathead minnow (MRIDs 48876701 & 48876702 ) used technical maleic hydrazide with analysis showing hydrazine concentrations less than 0.12 ppm. EPA had previously established an upper limit of 15 ppm for the impurity hydrazine in technical grade maleic hydrazide and techn ical labels do not indicate the amount of hydrazine present

.

4.2.2 . Risks to Terrestrial Organisms

Based on the results of the screening

- level assessment, the registered uses of maleic hydrazide result in potential for direct acute and chronic effects to certain size class and dietary combinations
of birds and mammals. However, this conclusion is uncertain due to the use of nondefinitive toxicity endpoints that did not test up to the highest concentrations predicted in acute and chronic
dose

- and dieta ry

- based modeling.

In order to gain a better understanding of how the EECs for the maximum maleic hydrazide application rate relate to the toxicity data currently available for birds, T

- REX was used to calculate RQs using the conservative assumption that the highest value in the avian acute oral study ( i.e.,

acute LD 50 = 2, 00 0 mg a.i./kg

- bw in the canary study ) and the highest value in the avian sub

- acute dietary study ( i.e., acute LC 50 = 5,620 mg a.i./kg

- diet) represent the avian acute endpoints. The

re sulting acute dose

- based and dietary

- based acute RQs for all size and dietary classes, based on the upper

- bound Kenaga values ranged from <0.01 to 1.83 . In actuality, these RQs would be lower than the estimated values because no mortality or sublethal eff ects were identified at the 2,000 mg a.i./kg

- bw acute oral and 5,620 mg a.i./kg

- diet sub acute dietary exposure levels. For example, if
the mallard non

- definitive acute oral endpoint of 4,600 mg a.i/kg

- bw were used (only slight decreases in body weight gai n were actually seen at this treatment level) instead of the non

-Page 40 of 53

definitive canary endpoint, for the maximum application rate of 13 lbs a.i./A, dose

- based RQs would range from <0.01 to a maximum of 1. 49 and the only exceedances of the non

- listed species
LO C would be for small and medium birds consuming short grass (RQs of 1.49 and 0.67

, respectively) and small birds consuming tall grass, broadleaf plants and arthropods (RQs of 0.58

— 0.84 )

. Similarly, no mortality or sublethal effects were seen in the sub

- ac ute dietary studies on the bobwhite and mallard with maleic hydrazide acid at the highest concentrations of 10,000 mg/kg

diet. If this value was used instead of the LC 50 of 5,620 mg/kg

- diet used in the assessment, than
the non

- listed species dietary LOC w ould not be exceeded and the listed species LOC would be exceeded for short grass, tall grass, broadleaf plants, and arthopods (RQs range from 0.02

— 0.31 )

. Similarly, if the actual sub

- acute LC 50 value were two times higher than this ( i.e. the true LC 50 was 20,000 mg ai/kg

- diet) than the listed species dietary LOC would only be exceeded for birds feeding on short grass (RQ would be 0.16 for this dietary item)

. Figure 2 shows how upper bound residue
estimates decline over time compared to the avian dietary

- b ased LOCs. For the most conservative dietary item (short grass), residues decline below the listed species LOC over a period of approximately 60 days.

If mean Kenaga EECs (for the maximum application rate of 13 lbs a.i./A) and the original
nondefinitiv e toxicity values were used instead of m aximum EECs, the non

- listed species acute
dose

- based LOC would only be exceeded for small birds f eeding on short grass and arthropods (RQ = 0.65 and 0.50 , respectively ) while the listed species LOC would still be exc eeded for small and medium sized birds feeding on short grass, tall grass, broadleaf plants and arthropods (RQs would range from < 0.01 to 0.65 ). Using mean Kenaga EEC values, the dietary

- based

l isted species LOC would only be exceeded for birds consuming short grass , tall grass, broadleaf plants and arthopods (RQs would range from 0.02 to 0.24 ).

No chronic avian reproduction data was submitted. Additionally, effects on body weight were seen in multiple generations in the mammalian reproduction test. Th erefore, chronic risk cannot be precluded for avian species (and to terrestrial

- phase amphibians and reptiles for which birds serve as surrogates).Page 41 of 53

Figure 2: Terrestrial Maleic Hydrazide Residues (Upper Bound Kenaga Estimates) on Different Dietary I tems over T ime. Horizontal lines show the Avian Acute Dietary Listed and Non

- Listed Species LOCsPage 42 of 53

In order to gain a better understanding of how the EECs for the maximum maleic hydrazide application rate relate to the toxicity data currently available fo r mammals, T

- REX was used to calculate RQs using the conservative assumption that the highest value in the mammalian acute oral study ( i.e. , acute LD 50 = 5,000 mg/kg and the highest value in the mammalian 2

- generation reproduction study ( i.e. , NOAEC = 10,0 00 ppm ) represent the mammalian acute and chronic endpoints. The resulting dose

- based acute RQs for all size and dietary classes, based on the upper

bound Kenaga values were all less than 0.27 , the resulting chronic dietary

- based RQ did not exceed any LOC s and the resulting chro n ic dose

- based RQ exceeded the LOC for all size classes o f mammals consuming short grass, small and medium sized mammals feeding on tall grass and broadleaf plants and small sized mammals only feeding on arthopods. Th e actual LD 50 would have to be greater than 13,000 ( i.e. more than 2x the nondefinitive acute endpoint) in order to completely eliminate the potential for acute risk to all mammals.

The chronic NOAEC endpoint for mammals was based on a statistically significant 8.5% effect on body weight at 30,000 ppm in the available rat reproduction study. There is some uncertainty

if this level of effect would result in decreased biological fitness of listed and non

- listed mammals. If a NOAEC of 30,000 ppm was used instead (LOAEC = 50,000 ppm in this scenario), than there
would be no exceedances for chronic dose

- based effects to mammals for any size

- class or dietary combination (the maximum RQ would be 0.90 for small mammals consuming short grass).

If using mean Kenaga EEC values instead of upper bound Kenaga values , there would only be a marginal exceedance of the acute listed species LOC for small mammals feeding on short grass (RQ = 0.10 ) and no other acute or chronic LOC exceedances for mammals, although on a chronic
dose basi s, small mammals consuming short grass would only narrowly not exceed the LOC (RQ = 0.96).

Only non

- definitive acute contact toxicity data is avail able for honey bee s. The proposed LOC (0.4) for beneficial terrestrial invertebrates is exceeded by more th an a factor of 2 assuming that
the actual contact LD 50 for honey bee s was the limit dose (36.26 μg/bee, at which only 3.2% mortality actually occurred in the test study). The true LD 50 would have to be approximately 90 μg a.i./bee in order not to exceed t he proposed LOC, but would have to b e at least an order of magnitude higher not to exceed the interim listed species LOC (0.05). Hazard to potentially sensitive life stages ( i.e. egg, larvae and juveniles) may not be evident from the honey bee contact

tox icity test that used adult worker honey bee s. The additional data indicating high levels of mortality in predatory mite and parasitic wasp studies at concentrations approximately 1/3 the maximum application rate (and only slightly above the maximum applica tion rate in the potato use pattern) provide additional lines of evidence that listed species of beneficial terrestri al invertebrates may be at risk for all use patterns except potentially for onion and citrus use sites.

The EECs predicted by EFED’s cur rent screening tool, Terrplant

, indicated risk to listed and non

listed species of monocots and dicots in both semiaquatic and dry habitats when aerial applications
are made. When only ground applications are permitted, then no risk is predicted for non

- l isted dicots in dry areas and listed species only marginally exceed the LOC (RQ = 1. 04 ) Spray drift alone results in potential risk to listed and non

- listed monocot species when maleic hydrazide isPage 43 of 53

applied aerially, but no risk is indicated for even listed species of either dicots or monocots from spray drift caused by ground applications.

To determine the extent of the area off the field for which RQs exceed the relevant LOC from spray drift , EFED uses the refined modeling tool, AgDrift 2.1.1. With sta ndard default assumptions, the RQ exceeds the list ed species LOC at distances ≥312 feet and ≥158 feet from the application site for listed monocots and dicots, respe ctively when maleic hydrazide is applied aerially. For ground applications and standard default assumptions, the RQ from spray drift only

ex ceeds the list ed species LOC at distances < 30 feet and < 16 feet from the application site for listed monocots and dicots, respectively. For n on

- listed monocots and dicots , when applied aerially, the RQ exceeds the non

- listed species LOC at distances < 8 5 feet and < 113 feet, respectively while for ground applicat ions, the RQ is only exceeded within 11 feet of the application site. Di f

ferent droplet spectra ( i.e. coarser droplet size distributions) would yield less spray drift and lower RQs.

No terre strial toxicological data has been evaluated for the impurity hydrazine. Although no ecotoxicological information has been evaluated by EFED for hydrazine, the Hazardous Substances Data Bank database accessible via Toxnet ( http://toxnet.nlm.nih.gov/ does contain ecotoxicity data that has not been reviewed by EFED

. The most sensitive terrestrial animal endpoints found in this database for hydrazine are for rabbit (species not listed in the database)
with an acute oral LD 50 of 20 mg/kg and roach ( Rutilus rutilus ) with a 24

- hr LC 50 of 0.54 mg/L. These toxicity values are several orders of magnitude (at least 2 orders) more sensitive than for maleic hydrazide. For most of the older terrestrial maleic hydrazide toxi cological data, hydrazine was not analyzed for in the test material. A newer terrestrial study with the canary (MRID 48877501) used technical maleic hydrazide with analysis showing hydrazine concentrations less than 0.12 ppm. EPA had previously establish ed an upper limit of 15 ppm for the impurity hydrazine in technical grade maleic hydrazide, and technical labels do not indicate the amount of hydrazine present. Therefore, the toxicological information from the available maleic hydrazide
terrestrial stud ies may underestimate toxicity (and increase the uncertainty in the risk estimates) if the actual amount of hydrazine impurity as a result of the maleic hydrazide manufacting process results in higher hydrazine concentrations than what was tested in the ma leic hydrazide laboratory toxicity studies.

5. Federally Threatened and Endangered (Listed) Species Concerns

Section 7 of the Endangered Species Act, 16 U.S.C. Section 1536(a)(2), requires all federal agencies to consult with the National Marine Fisherie s Service (NMFS) for marine and anadromous listed species, and/or the United States Fish and Wildlife Service (USFWS) for listed wildlife and freshwater organisms, if they are proposing an "action" that may affect listed species or their designated critica l habitat. Each federal agency is required under the Act to ensure that any action they authorize, fund, or carry out is not likely to jeopardize the continued existence of a listed species or result in the destruction or adverse modification of designate d critical habitat. To jeopardize the continued existence of a listed species means "to engage in an action that reasonably would be expected, directly or indirectly, to reduce appreciably the likelihood of bothPage 44 of 53

the survival and recovery of a listed speci es in the wild by reducing the reproduction, numbers, or distribution of the species" (50 C.F.R. § 402.02).

To facilitate compliance with the requirements of the Endangered Species Act (subsection (a)(2)), the Office of Pesticide Programs has established procedures to evaluate whether a proposed registration action may directly or indirectly appreciably reduce the likelihood of both the survival and recovery of a listed species in the wild by reducing the reproduction, numbers, or distribution of any liste d species (USEPA, 2004). After the Agency’s screening level risk assessment is conducted, if any of the Agency’s listed species’ LOCs are exceeded for either direct or indirect effects, an analysis is conducted to determine if any listed or candidate spec ies may co

- occur in the area of the proposed pesticide use or areas downstream or downwind that could be contaminated from drift or runoff/erosion. If listed or candidate species may be present in the proposed action area, further biological assessment is undertaken. The extent to which listed species may be at risk is considered, which then determines the need for the development of a more comprehensive consultation package, as required by the Endangered Species Act.

The federal action addressed herein is the proposed renewed registration of maleic hydrazide on agricultural use sites. It is expected that its use could occur nationwide.

5.1. Action Area

For listed species assessment purposes, the action area is considered to be the area affected directly or indirectly by maleic hydrazide use and not merely the immediate area where maleic hydrazide is applied. At the initial baseline, the risk assessment considers broadly described taxonomic groups and conservatively assumes that listed species within those broad groups are co

- located with the pesticide treatment area. This means that listed terrestrial plants and wildlife are assumed to be located on or adjacent to the treated site and listed aquatic organisms are assumed to be located in a surface water body adjacent to the treated site. The assessment also assumes that the listed species are located within an assumed area, which has the relatively highest potential exposure to the pesticide, and that exposures are likely t o decrease with distance from the treatment

area.

5.2. Taxonomic Groups Potentially at Risk

If the assumptions associated with the baseline action area result in RQs that are below the listed specie s LOCs, a "no effect" determination conclusion is made with respect to listed species in that taxa, and no further refinement of the action area is necessary. Furthermore, RQs below the listed species LOCs for a given taxonomic group indicate no concern f or indirect effects on listed species that depend upon the taxonomic group for which the RQ was calculated. However, in situations where the screening assumptions lead to RQs in excess of the listed species LOCs for a given taxonomic group, a potential fo r a "may affect" conclusion exists and may be associated with direct effects on listed species belonging to that taxonomic group or may extend to indirect effects upon listed species that depend upon that taxonomic group as a resource. In such cases, addi tional information on the biology of listed species, the locations of these species, and the locations of use sites are considered to determine the extent to which screening assumptions regarding an actionPage 45 of 53

area apply to a particular listed organism. These subsequent refinement steps will consider how this information would impact the action area for a particular listed organism and potentially include areas of exposure that are downwind and downstream of the pesticide use site.

Assessment endpoints, expos ure pathways, and the conceptual models addressing maleic hydrazide uses, and the associated exposure and effects analyses conducted for the maleic hydrazide baseline risk assessment are in Sections 2 to 3 . The assessment endpoints used in the
baseline ri sk assessment include those defined operationally as reduced survival and reproductive impairment for both aquatic and terrestrial animal species and survival, reproduction, and growth of aquatic and terrestrial plant species from both direct acute and chr onic exposures. These assessment endpoints are intended to address the standard set forth in the Endangered Species Act requiring federal agencies to ensure that any action they authorize does not appreciably reduce the
likelihood of both the survival and recovery of a listed species in the wild by reducing the reproduction, numbers, or distribution of the species. Risk estimates (RQs) which, integrating exposure and effects, are calculated for broad based taxonomic groups in the screening

- level risk

asse ssment presented in Section 4.

Both acute endangered species and chronic risk LOCs are considered in the baseline risk assessment to identify direct and indirect effects to taxa of listed species. This section identifies direct effect concerns, by taxa t hat are triggered by exceeding endangered LOCs in the baseline risk assessment, with an evaluation of the potential probability of individual effects for exposures that may occur at the established endangered species LOC. Data on exposure and effects coll ected under field and laboratory conditions are evaluated to make determinations on the predictive utility of the direct effect screening assessment findings to listed species. Potential for direct effects to
listed taxa are described in Table 1 8

.

Table 1 8 . Potential Effects to Federally Listed Taxa Associated with Direct Effects from

th e Registered Uses of Maleic Hydrazide

. Listed Plant Taxon Potential Direct Effects

Terrestrial and semi

- aquatic plants

– monocots and dicots Yes

Aquatic nonvascular pl ants No Aquatic vascular plants No

Listed Animal Taxon Potential Direct Effects

Acute Chronic

Terrestrial invertebrates Yes 1 Uncertain

Mammals Uncertain 2 Yes

Birds Uncertain 2 Uncertain 3 Reptiles Uncertain 2 Uncertain 2 ,3 Amphibians Uncertain 2, 4 Unce rtain 2, 3,4

Freshwater fish No No

Freshwater invertebrates No No

Mollusks No No

Estuarine/marine fish N o No

Estuarine/marine invertebrates No No

1 Although an LC 50 was not attainable in the acute contact toxicity test with honey bees, the limit dose ( 36.3 μg a.i./bee) was not high enough to preclude risk at the non

- listed species LOC (0.4), based on the EECs ( 35.1 μg/bee ) for registered maleic hydrazide uses. Further, given that additional toxicity data with predatory mites and parasitic wasps showed lethal effects at concentrations well below the maximum application

rate , EFED cannot preclude effects to this taxon.Page 46 of 53 2 Risk to this t axa was considered uncertain due to the use of non

- defini tive toxicological endpoints that were below maximum EECs.
Altho ugh no effects were observed in acute toxicological studies, the doses tested did not exceed the maximum EECs predicted by the maximum application rates.

3 Chronic risk to this taxa is uncertain due to a lack of avian reproduction data

4 Risk t o this taxa is uncertain for terrestrial

- phase amphibians. No direct effects are expected for aquatic phase amphibians.

6 . Literature Cited

Ahrens, W.H. Herbicide Handbook of the Weed Science Society of America. 7th ed. Champaign, IL: Weed Science So ciety of America, 1994., p. 180

.

Baris, R., M. Barrett, R.F.H. Bohaty, M. Echeverria, P. Villanueva, J. Wolf, and D. Young. 2012. Guidance for Using PRZM

- GW in Drinking Water Exposure Assessments. Environmental Fate and Effects Division, Office of Pesti cide Programs, Office of Chemical Safety and Pollution Prevention, USEPA. Washington, D.C.

FAO. 2000. Appendix 2. Parameters of pesticides that influence processes in the soil . In FAO
Inf ormation Division Editorial Group (Ed.), Pesticide Disposal Series 8. Assessing Soil Contamination. A Reference Manual. Rome: Food & Agriculture Organization of the United Nations (FAO). (Accessed March 31 , 20 14 ).

NAFTA. 2011. Guidance for Evaluating and Calculating Degradation Kinetics in
Environmental Media . December 2011. NAFTA Technical Working Group on
Pesticides. Accessed on March 21, 2014 at: http://ww w.epa.gov/oppfead1/international/naftatwg/guidance/degradation

- kin.pdf

Tomlin, C.D.S. (ed.). The Pesticide Manual

- World Compendium, 11 th ed., British Crop Protection Council, Surrey, England 1997, p. 757.

USEPA, 1994. Reregistration Eligibility Dec ision (RED) Maleic Hydrdazide. Office of Prevention, Pesticides and Toxic Substances. Washington, D.C.

USEPA, 2009 a

. Registration Review

- Preliminary Pr oble m Formul ati on for the Ecological Risk

Assessment of Maleic hydrazide

. Office of Pesticide Progr ams (DP Barcode 362546).

USEPA, 2009 b . Input Parameter Guidance. Version 2.1. Environmental Fate and Effects Division. October 22, 2009 http://www.epa.gov/oppefed1/ models/water/input_parameter_guidance.htmPage 47 of 53



### Appendix 1

– Surface Wa ter Concentration Calculator Model ing Summary

Cropped Area Fraction 1.0

Koc (ml/g) 35

Water Half

- Life (days) @ 25 °C 6

Benthic Half

- Life (days) @ 25 °C 0

Photolysis Half

- Life (d ays) @ 40 °Lat 0

Hydrolysis Half

- Life (days) 0

Soil Half

- Life (days) @ 22 °C 3

Foliar Half

- Life (days) 35

Molecular Wt 112.09

Vapor Pressure (torr) 7.5E

- 8

Solubility (mg/l) 4507Page 48 of 53 

### Appendix 2

- Environment al Fate Studies Summary

835.2120 : H y drol y sis (00143322)

[ 14 C]

- 4 ,5

- Maleic hydrazide (radiochemical purity >99%), at 50 ppm, was stable to hydrolysis (<6% degradation) in buffered solutions (pH 3, 6, and 9) maintained for 61 days at 45 0 C and for
an ad ditional 30 days at 80°C.

835.2240: Photodearadation in Water (428723, (4269210) [ 1,4

- 14 C ] M aleic hydrazide (6

- hydroxy

- 2 H

- pyridazin

- 3

- one; radiochemical purity >99%), at approximately 0.12 mg/L, degraded slowly (~10% at 28 days) at

- pH 5, was stable at pH 7, and degraded with an observed half

- life of >30 days at pH 9 in sterile aqueous buffer solutions that
were irradiated for 12 hours/day for 30 days at 23

- 30°C using a xenon lamp that had an intensity (daily intensity 24.9

- 49.3 mwatts/cm2) and emissi on spectrm: similar to sunlight. At 30 days posttreatment, [14~]maleich ydrazide was the only [14~]compound isolated from the pH 5 and 7 solutions. In the irradiated pH 9 solution, [14~]maleich ydrazide was 0.121

- 0.124 mg/L immediately posttreatment, 0.061

- 0.091 mg/L at 16 days, 0.084

- 0.091 mg/L at 24 days, and
0.031

- 0.078 mg/L at 30 days; two photodegradates were isolated from the 30

- day solution, but were neither identified nor quantified. [14c]~aleic hydrazide was the only [ 14 C ] compound isolated
from th e dark controls. Material balances ranged from 96.4% to 109% of the applied in the
irradiated solutions and from 97.7% to 114% in dark controls; there was no discernable pattern of
decline with any solution. The pH of buffer solutions remained constant ove r the study period.

835.2410 : Photode g radation on Soil (00151951)

[ 14 C]

- 4 ,5

- Maleic hydrazide, potassium salt at 20 ppm on sandy loam soil was stable to photodegradation on sandy loam soil irradiated continuously with artificial light (1.4 w/m2) for

17 days (equivalent to 34 days of sunlight).

835.4100 : Aerobic Soil Metabolism (4189620) Maleic hydrazide degraded witlh an observed half

- life of approximately 24 hours in loamy sand
soil that was incubated in the dark at 17

- 22°C and 75% of 0.33 bar moisture capacity for 90 days. Two degradates, maleic acid and maleimide, were detected in the soil in small quantities (<5%) during the study. At 90 days posttreatment, C02 was the major degradate (approximately 70% of the applied).

835.4200 : Anaerobic Soil Meta bolism (41918201) Maleic hydrazide degraded with an observed half

- life of 30

- 60 days in anaerobic (flooding plus nitrogen atmosphere) loamy sand soil that was incubated in the dark at 18

- 21°C for 60 days. Two nonvolatile degradates, maleic acid and maleim ide, were identified in the soil plus floodwater inPage 49 of 53

small quantities (<5%) at the start of anaerobic incubation, but did not persist. After 60 days of anaerobic incubation, (GOz was the major degradate (approximately 70% of the applied).

835.1230 ; 835.12 40 : Leachin g /Adsorp t o ion/Desorption ( 41896202, 00151952 )

In the study (41896202), based on column leaching studies, aged (12 hours) maleic hydrazide and maleic hydrazide residues were found to be mobile (39.76% of the applied radioactivity was in the
lea chate) in columns of loamy sand soil, and very mobile (100.79% of the applied radioactivity in
the leachate) in columns of sand soil leached over a period of 7 days.

The study ( 00151952) using batch equilibrium techniques, unaged maleic hydrazide was very mobile in a silt loam, a sandy clay loam, a sandy loam, and two sand soils; Freundlich K ads values

were 0.14

- 2.61 and K des values were 0.39

- 14.45. A soil column study of unaged maleic hydrazide had high mobility, with all of the radioactivity being elute d in less than 10 inches of water (two sand soils).

835.6100: Terrestrial field dissipation studies (42744801 and 42790901)

The study conducted on sandy loam soil located in California (42744801 and 42790901) provides acceptable information that maleic hydrazide dissipated with observed half

- lives of 3 and 5 days in bareground and vegetated (turf) plots, respectively. The study conducted on loam soil located in North Carolina (42693301) provides acceptable information that maleic hydrazide dissipated
wi th observed halflives of 14 and 27 days in bareground and vegetated (mature tobacco) plots, respectively. The study conducted on clay loam soil in New Mexico (40034802) provides supplemental information that maleic hydrazide, potassium salt, dissipated wit h a half

life of 3

- 7days; no residues were detected (<0.05 ppm) at depths greater than 12 inches.

850.1730: Fish BCF ( 0016330 ) The 1988 Registration Standard for maleic hydrazide specified that the bioaccumulation in fish study was not required because the reviewed octanol/water partition coefficient (K ow ) study (00163301) gave a value of ( log Kow=

- 0.68 ) , indicating a very low potential for maleic hydrazide to bioaccumulate in fish or other aquatic nontarget organisms

.

835.4300: Aerobic Aquatic Metab olism studies

- Anaerobic Aquatic Metabolism.
No studies were reviewed. No data are required at this time because maleic hydrazide has no aquatic or forestry uses.Page 50 of 53 

### Appendix 3

– Summary of Risk Conclusions by Use Site and Taxa

Use Pattern Category 1 Aqua tic

Invertebrates Fish (surrogate

for aquatic

phase amphibians) Birds, (surrogate for

terrestrial

- phase amphibians and reptiles) Mammals Plants Beneficial
Terrestrial

Invertebrates

Agricultural
Fallow/Idleland/
Conservation

Reserve Acute risk:

Not expecte d

Chronic risk : Not expected Acute risk:

Not expected

Chronic risk : Not expected Acute risk :

Dietary

- risk to listed and

non

- listed birds and dose

based r isk to all size classes
of listed birds and dose

- based
risk to small and medium

non

- listed birds is uncertain
due to nondefinitive data that did not test up to predicted

EECs

.

Chronic risk : Uncertian due to lack of
chronic data Acute risk : Risk to all size classes of
listed mammals is uncertain
due to nondefinitive data
that did not test up to

pre dicted EECs . Risk is not predicted for non

- listed
mammals

Chronic risk : Potential for dose

- based risk to mammals depending on size class and dietary items. Terrestrial: Likelihood of risk expected, especially for listed and non

listed monocot species i n all habitats and from spray drift. Risk expected for dicots in
semi

- aquatic habitats (ground or air) and dry habitats from aerial applications only.

Aquatic: Not expected Non

- listed species:
Risk to non

- listed species is uncertain
due to non

definit ive data that did not test up to predicted EECs.

Listed species:

L ikelihood of risk expected to listed species

.

Ornamental
and/or Shade Trees,
Ornamental Lawns and Turf,
Residential

Lawns Acute risk:

Not expected

Chronic risk : Not expected Acute risk:

Not expected

Chronic risk : Not expected Acute risk :

Dose

- based r isk to small and
medium sized listed and non

listed birds and large listed
birds is uncertain due to
nondefinitive data that did not test up to predicted EECs

. Not expected for large no n

listed birds. Dietary

- based
risk uncertain for listed birds only.

Chronic risk : Uncertian due to lack of
chronic data Acute risk : Risk to small and medium
sized listed mammals is
uncertain due to
nondefinitive data that did not test up to predicted

EE Cs . Not expected for large listed mammals or any

non

- listed mammals.

Chronic risk : Potential for dose

- based risk
to small and medium sized mammals feeding on short grass only Terrestrial: Likelihood of risk expected, especially for listed and non

liste d monocot species in all habitats, listed dicots in dry (aerial application only) and
semi

- aquatic habitats and non

listed dicots in semi

- aquatic habitats only. Risk from spray drift is only expected for listed
monocots under aerial applications.

Aquatic : Not expected Non

- listed species:
Risk to non

- listed species is uncertain
due to non

definitive data that did not test up to predicted EECs.

Listed species:

L ikelihood of risk expected to listed speciesPage 51 of 53 Golf Course Turf, Industrial/
Construction

Areas (Outdoor), Nonagricultural Rights

- of

Way/Fencrows/ Hedgerows, Nonagricultural
Uncultivated Areas/Soils, Urban Areas, Airports/Landing
Fields Acute risk:

Not expected

Chronic risk : Not expected Acute risk:

Not expected

Chronic risk : Not expected Ac ute risk:

Dose

- based r isk to small and
medium sized listed and non

listed birds and large listed
birds is uncertain due to
nondefinitive data that did not test up to predicted EECs

. Not expected for large non

listed birds. Dietary

- based
risk uncertain fo r listed birds only.

Chronic risk : Uncertian due to lack of
chronic data Acute risk : Risk to small and medium
sized listed mammals is
uncertain due to
nondefinitive data that did not test up to predicted

EECs . Not expected for large listed mammals or a ny

non

- listed mammals.

Chronic risk : Potential for dose

- based risk
to small and medium sized mammals feeding on short grass only Terrestrial: Risk expected for all plants in
semi

- aquatic areas regardless of application method, but only listed species of monocots in dry areas when ground applications are used (under aerial applications in dry areas, both listed
monocots and dicots are
considered at risk ) . Risk from spray drift is only expected for
listed monocots under aerial applications

Aquatic:

Not expected Non

- listed species:
Risk to non

- listed species is uncertain
due to non

definitive data that did not test up to predicted EECs.

Listed species:

L ikelihood of risk expected to listed species

Tobacco Acute risk:

Not expected

Chronic risk : Not expected Acute risk:

Not expected

Chronic risk : Not expected Acute risk :

Dose

- based risk to small
listed and non

- listed birds and listed medium and large
sized birds is uncertain due to
nondefinitive data that did not test up to predicted EECs.

Not e xpected for medium or large non

- listed birds. Dietary risk uncertain for listed birds only.

Chronic risk : Uncertian due to lack of
chronic data Acute risk:
Risk to small and medium
sized listed mammals is
uncertain due to
nondefinitive data that did

no t test up to predicted

EECs . Not expected for large listed mammals or any

non

- listed mammals.

Chronic risk : Potential for dose

- based risk
to small and medium sized mammals feeding on short grass only Terrestrial: Risk expected for all listed and

non

- li sted plants in semi

aquatic areas, regardless of application method. Risk expected for listed and non

listed monocots in dry areas only under aerial applications. Risk from spray drift alone not expected for any plants regardless of application
method.

Aquatic: Not expected Non

- listed species:
Risk to non

- listed species is uncertain
due to non

definitive data that did not test up to predicted EECs.

Listed species:

L ikelihood of risk expected to listed speciesPage 52 of 53 Ornamental Woody Shrubs
and Vines Acute r isk:

Not expected

Chronic risk : Not expected Acute risk:

Not expected

Chronic risk : Not expected Acute risk :

Dose

- based risk to small
listed and non

- listed birds
and medium sized listed birds
is uncertain due to
nondefinitive data that did

not test up to predicted EECs. Not expected for medium or large non

- listed birds. Dietary risk uncertain for listed birds only.

Chronic risk : Uncertian due to lack of
chronic data Acute risk:
Risk to small listed
mammals is uncertain due to
nondefinitive data that did not test up to predicted

EECs (marginal exceedance). Not expected for medium or large listed mammals or any non

- listed
mammals.

Chronic risk : Not expected Terrestrial: Risk expected for all listed and

non

- listed plants in semi

aquatic areas, regardless of application method. Risk expected for listed monocots in dry areas only under aerial applications. Risk from spray drift alone not expected for any plants regardless of application method.

Aquatic: Not expected Non

- listed species:

Not e xpected

Listed species:

L ikelihood of risk expected to listed species

Potato (White/Irish) Acute risk:

Not expected

Chronic risk : Not expected Acute risk:

Not expected

Chronic risk : Not expected Acute risk :

Dose

- based risk to small
listed and no n

- listed birds
and medium sized listed birds
is uncertain due to
nondefinitive data that did not test up to predicted EECs. Not expected for medium or large non

- listed birds. Dietary risk uncertain for listed birds only.

Chronic risk : Uncertian due to lack of
chronic data Acute risk: Not expected

Chronic risk : Not expected Terrestrial: Risk expected for all listed and

non

- listed plants in semi

aquatic areas, regardless of application method. Risk expected for listed monocots in dry areas only under a erial applications. Risk from spray drift alone not expected for any plants regardless of application method.

Aquatic: Not expected Non

- listed species: Not expected

Listed species:

L ikelihood of risk expected to listed speciesPage 53 of 53 Onion Acute risk:

Not expected

Chronic risk : Not expected Acute risk:

Not expected

Chronic risk : Not expected Acute risk:

Dose

- based risk to small and
medium sized listed birds is
uncertain due to
nondefinitive data that did not test up to predicted EECs. Not expected fo r any non

listed birds. Dietary risk
uncertain for listed birds feeding on short grass only.

Chronic risk : Uncertian due to lack of
chronic data Acute risk: Not expected

Chronic risk : Not expected Terrestrial: Risk expected for all listed and

non

- list ed plants in semi

aquatic areas, regardless of application method. No r isk expected for any plants in dry areas or due to spray drift regardless of application
method.

Aquatic: Not expected Non

- listed species: Not expected

Listed species:

R isk to list ed species uncertain.

Citrus Acute risk:

Not expected

Chronic risk : Not expected Acute risk:

Not expected

Chronic risk : Not expected Acute risk:

Dose

- based risk to small and
medium sized listed birds is
uncertain due to
nondefinitive data that did not test up to predicted EECs. Not expected for any non

listed birds. Dietary risk
uncertain for listed birds feeding on short grass only.

Chronic risk : Uncertian due to lack of
chronic data Acute risk: Not expected

Chronic risk : Not expected Terrestr ial: Risk expected for all listed and

non

- listed plants in semi

aquatic areas when aerial application is used. Under ground applications in semi

aquatic areas, risk is not expected for non

- listed dicots, but is expected for listed
dicots and non

- listed an d
listed monocots. No r isk expected for any plants in dry areas or due to spray drift regardless of application
method.

Aquatic: Not expected Non

- listed species: Not expected

Listed species:

R isk to listed species uncertain

1 Use pattern categories are based on similar application rates