### Basic Uncertainties



### Numerous uncertainties in the aquatic modeling and ecological toxicity data may impact risk

conclusions for listed and non

- list ed species. For example, registered labels for hydrogen

cyanamide products include language requiring a 900 ft buffer between the site of application

and “the mean high water mark for intertidal areas, surface waters, rivers, streams, or their

flowing trib utaries” to limit the potential for exposure of hydrogen cyanamide to aquatic

environments. While aquatic estimated environmental concentrations ( EECs ) were modeled

using a 900 ft buffer for spray drift, the Agency does not currently have a method for mode ling

the impact of a buffer on run

- off. Therefore, EECs are primarily driven by the modeled run

- off,

which assumes no buffer between the site of application and the water body. Given the rapid

degradation of hydrogen cyanamide in soil (aerobic soil half

- li fe of 12 hours in sandy loam soil)

, this is a major source of uncertainty in the aquatic exposure and subsequent risk assessment.

Additionally, the aerobic aquatic metabolism half

- life value of 5.28 days represents the 90 th



### percentile of the upper confidence bound for the mean of two available half

- life values, one for

ponded systems (3.2 days) and and for stream systems (1.2), and may be overly conservative for

systems with flowing water.

In addition, EPA is aware that a significant amount of research is available that demonstrates that

a well maintain ed (e.g. non

- channelized) vegetative buffer may significantly reduce pesticide

runoff loads. As an example, the USDA’s “Conservation Buffers to Reduce Pesticide Losses”

(USD A 2000) was specifically developed to address potential impact of vegetative buffers to

reduce pesticide loading. In th at analysis, the authors made no specific recommendation s but

suggest that in order to be effective

, a buffer must be at least 100 feet wide to reduce dissolved

pesticide s and nutrient s . In addition to the research described above

, there are a number of

available models for estimating runoff losses that have the ability to estimate the influence of

buffers on these losses. EPA has begun preliminary evaluation of these models

, and although

none of these models have been implemented

, they do show promise

. EPA will continue to

evaluate these tools. Taken together, this information suggests that the 900 foot buffer currently

on product labe ls will reduce loading to aquatic resources below the levels estimated in this

assessment provided that buffers are well maintinated (e.g. non

- channelized) . However, the

extent and amount of reduction remains an uncertainty. While the approach used in th is

assessment is likely protective of more sensitive ponded systems, it may overestimate potential

exposure in flow through systems such as rivers and, to a certain extent, coastal areas. As a

result of these uncertainties

, acute and chronic risks to aqua tic organisms may be overestimated.

There is also uncertainty surrounding the potential for chronic risks to fish. Current data on the

freshwater species, rainbow trout, are not adequate to derive a definitive no observed adverse

effect concentration ( NOAEC ) because effects were noted at all test concentrations. This

represents a substantial data gap in the analysis. Since the available lowest observed adverse

effect concentration ( LOAEC ) is within one order of magnitude of the highest EEC, chronic risk

to freshwater fish cannot be precluded. However , the magnitude of biological effects observed at

the lowest concentration level appears to be close to the limit of statistical and biological

signifigance. In addition, as discussed previously

, the aquatic EECs do not take into

consideration the impacts of the required 900 ft buffer on run

- off. Therefore, the benefits of

receiving another fish early life stage study to define a NOAEC may not be substantial. For

estuarine/marine fish, chronic toxicity data wa s not available. It is not possible to calculate an

### acute

- to

- chronic ratio (ACR) because , as discussed above, only a non

- definitive NOAEC is

available for the freshwater fish. This represents a substantial data gap in the analysis.

Another area of uncer tainty surrounds the potenti al for chronic risks to estuarine/marine

invertebrates because toxicity data for this taxa is not available

. While there is uncertainty

associated with applying an acute to chronic ratio (ACR) for the daphnid (most sensitive

fre shwater invertebrate) to the mollusk (most sensitive estuarine/marine invertebrate) because of

the differences in life history, applying the ACR to the mollusk and the less sensitive Mysid

shrimp can be used to bracket the potential risks to estuarine/mari ne invertebrates. When the

ACR was used to estimate chronic toxicity to the eastern oyster, RQs ranged from 0.09 to 1.0,

indicating potential for risks to estuarine/marine mollusks from chronic exposure from hydrogen

cyanamide use on cherries. Additional ly, when the ACR for the daphnid was applied to the acute

toxicity value available for the pink shrimp (LC 50 

### = 6300 ppb), RQs ranged from 0.03 to 0.36,

suggesting that the potential for chronic risk to crustaceans is low. With this information chronic

risks to estuarine/marine invertebrates can not be precluded

, but risks to crustaceans are likely

low.

Additio nally, the Agency has only received data for two species of non

- vascular aquatic plants

, instead of the four species typically required. Without this data risks to these taxa of aquatic

plants may be underestimated.

P otential for chronic risk to birds is also uncertain because c urrent data on mallard duck are

inadequate to derive a definitive NOAEC or make a definitive determination of risk (effects were

noted at all test concentrations). While a second avian reproduction study on mallard duck that

result s in derivation of a NOAEC would reduce uncertainty, chronic risks are already identified

for birds based on the available bobwhite quail data. Therefore, additional data on the mallard

duck is not necessary at this time. In addition, acute toxicity data i s not available for a passerine

species; however, given the magnitude of difference needed to reduce application rates such that

risk would be below the level of concern, this data is unlikely to change the risk assessment.

There are considerable uncertai nties associated with the available plant toxicity data. For

seedling emergence, definitive EC 25 

### and NOAEC values were not calculable for the most

sensitive dicot species (lettuce) in the available study. As a result, risks to non

- listed plant

species coul d not be calculated and RQs for listed species were calculated based on the available

LOAEC (0.056 lbs a.i./A). RQs may underestimate the magnitude of risk to listed species

exposed to hydrogen cyanamide via run

- off and spray drift. In addition, phytotoxic ity observed

in the control group was greater than 25% for one species (oat) in the vegetative vigor study.

This suggests that growing conditions may not have been optimal for this species or cross

contamination may have occurred. As a result, this data co uld not be used in the AgDrift analysis

to calculate buffer distances. Risks may be underestimated for plants with similar toxicity to

hydrogen cyanamide as oat. In addition, the EC 25 

### value for the most sensitive dicot species

(tomato) should be interprete d with caution because it is not bracketed by the test concentrations

.

### Table 1. Risk Resulting from Hydrogen Cyanamide Exposure Presented by Taxon

Use Birds

(surrogate for

reptiles and

terrestrial

- phase

amphibians)* Mammals * Plants Terrestrial Inverts Fish

(surrogate for

aquatic

- phase

amphibians)** Aquatic

Invertebreates

Nectarines;

Peaches Acute risk :

Yes 1

( except medium and

large granivores )

Chronic risk :

Yes 1

( except birds that eat

fruits/pods/seeds ) Acute risk :

Yes 1

( except large

mammals that eat

fruits/pods/seeds )

Chronic risk :

Yes 1 ,2 Terrestrial:

Yes 1

Aquatic:

N ot expected Non

- listed and

Listed:

Uncertain 3 Acute risk:

N ot expected

Chronic risk :

Uncertain 4 Acute risk:

N ot expected

Chronic risk :

Uncertain 4

Blackberries;

Blueberries Acute risk :

Yes 1

( except large

granivores )

Chronic risk :

Yes 1 ,2 Acute risk :

Yes 1

Chronic risk :

Yes 1 ,2 Terrestrial:

Yes 1

Aquatic:

N ot expected Non

- listed and

Listed:

Uncertain 3 Acute risk:

N ot expected

Chronic risk :

Uncertain 4 Acute risk:

N ot expected

Chronic risk :

U ncertain 4

Apples;

Cherries;

California figs;

Grapes;

Kiwi fruits Acute risk :

Yes 1

( except large

granivores )

Chronic risk :

Yes 1 ,2 Acute risk :

Yes 1

Chronic risk :

Yes 1 ,2 Terrestrial:

Yes 1

Aquatic:

Uncertain 4

(non

- vascular

plants) Non

- listed and

Listed:

Uncertain 3 Acute risk:

N ot expected

Chronic risk :

Uncertain 4 Acute risk:

N ot expected

Chronic risk :

Uncertain 4

1 “Yes” indicates risk concerns for both listed and non

- listed taxa

. 2 Risk may be mediated by the rapid degradation of hydrogen cyanamide in the environment.

3 Risk is uncertain because the limit dose was not high enough to preclude risks given the high application rate of hydrogen cyanamide.

4 Risk is u ncertain due to: the absence of acceptable data describing the toxicity of hydrogen cyanamide to the taxa of interest, uncertainties in EECs given the

labeled 900 ft buffer, and uncertainties in the duration of exposure given the rapid degradation of hydro gen cyanamide in soil and water (aerobic soil half

- life of

12 hours in sandy loam soil, aerobic aquatic half

- life of 3.2 days in a pond system, and aerobic aquatic half

- life of 1.2 days in a river system).

### Additional Considerations for Listed Species

Base d on this screening

- level assessment, there are potential risks of direct effects to listed and

non

- listed mammals, birds (birds are surrogates for terrestrial phase reptiles and amphibians),

and terrestrial plants from the use s of hydrogen cyanamide

. The potential direct effects to listed

and non

- listed freshwater and estuarine/marine fish and invertebrates and terrestrial invertebrates

are uncertain given limitations in the available toxicity data. Listed species of freshwater and

estuarine/marine invert ebrates, mammals, birds, and terrestrial invertebrates may also be affected

through indirect effects because of the potential direct effects on listed and non

- listed species.

Potential direct effects on listed and non

- listed freshwater and estuarine/marine invertebrates,

birds, and terrestrial invertebrates from the use of hydrogen cyanamide may be associated with

modification of P rimary C onstituent E lements (PCEs) of designated critical habitats, where such

designations have been made. However, a t this current stage of the Registration Review process,

it is premature to make effects determinations for listed species until further scientific analysis

and refinements are conducted , based on recommendations received from the National Acad emy

of Sciences’ (NAS) National Research Council (NRC) April 2013 report, available at

http://www.nap.edu/catalog.php?record_id=18344 . The NAS report outlines recommendations

on specific scienti fic and technical issues related to the development of pesticide risk

assessments that are compliant with the Endangered Species Act (ESA) and the Federal

Insecticide, Fungicide, and Rodenticide Act (FIFRA).

The EPA along with the U.S. Fish & Wildlife Ser vice (USFWS), the National Marine Fisheries

Service (NMFS) (collectively, the Services), and the U.S. Department of Agriculture (USDA),

released a summary of their implementation plan for assessing risks of pesticides to listed species

ahead of the stakeho lder workshop held on November 15, 2013. This plan was developed in

response to the NAS’ recommendations, including a common approach to risk assessment as a

way of addressing scientific differences between EPA and the Services. During the workshop,

the agencies received feedback from the public on the interim scientific approaches that were

developed as part of the initial implementation of the NAS recommendations. These approaches

will be jointly implemented and vetted as part of a phased iterative pro cess. Once fully vetted,

EPA will further refine the listed species effects determination portion of this risk assessment.

To make effects determinations for individual listed species, useful refinements may include, but

are not limited to, analyses of: 1) more detailed, species

- specific ecological and biological data;

2) more detailed and accurate information on hydrogen cyan amide use patterns; and 3) sub

county level spatial proximity data for the co

- occurrence of potential effects areas and listed

species and any designated critical habitat. Examples of such refinements are described below.

EFED is currently developing too ls that are expected to further refine the assessment and are

designed to support effects determinations for individual federally listed species and their

designated critical habitats (where applicable). Scientific information obtained from the

Services

, and other reliable sources is being collated by EFED to address all currently listed

species. Th is information is be ing stored in an Office of Pesticide Programs (OPP) P esticide

R egistration I nformation S yste M (PRISM) listed species knowledgebase. The li sted species

knowledgebase consist s of an information repository that houses biological and behavioral

information relevant to individual species ( e.g. , habitat, diet, and life history, including specific

### temporal and spatial associations) and a document repository that contains supporting documents

( e.g ., USFWS recovery plans) and electronic information ( e.g ., GIS data files). For terrestrial

taxa, biological information relevant to the assessment ( e.g ., diet and body weight) will be used

to parameterize exposure estimates using a method consistent with currently used methods in the

T

- REX and T

- HERPS models.

Refinements will also include more detailed analyses of the registered uses and specific use

patterns that result in either “Likely to Adversely A ffect” (LAA) or “Not Likely to Adversely

Affect” (NLAA) determinations for federally listed species. The analyses may include more

information on where, when, and how hydrogen cyanamide is used on all use sites

. Actual usage

data (when available) and nat ional land

- cover datasets that indicate potential use sites [ e.g

., N ational L and C over D ataset (NLCD), C rop land D ata L ayer (CDL)] may be used to support a

more refined analysis of where hydrogen cyanamide is reasonably expected to be used.

Similarly, refi nements on the timing of applications and a more in

- depth exploration of

agronomic practices for hydrogen cyanamide may be included as part of the refinement.

The refinements based on individual species data; additional, detailed usage information, when

a vailable; and recommendations from the NRC report are expected to help to more accurately

identify potential areas of effect and to better inform effects and habitat determinations for listed

species and any designated critical habitats.

# Environmental Fate and Ecological Risk Assessment

for the R er egistration of Hydrogen Cyanamide

CH

2 

## N

2 

## CAS Registry Number 420

- 04

- 2

PC Code 014002

Prepared by:

Elizabeth Riley , Biologist

Ibrahim Abdel

- Saheb

, Ph.D, Environmental Scientist

U. S. Environmental Protection Agency

Office of Pesticide Programs

Environmental Fate and Effects Division

Environmental Risk Branch IV

1200 Pennsylvania Ave., NW

Mail Code 7507P

Washington DC 20460 Reviewed by:

Michael Wagman , Biologist ERB VI

Andrew Shelby

, Fate Scientist , ERB VI

Mark Corbin, Branch Chief, ERB VI



### Date: February 27, 2014- Page 2 of 115

- 

### Table of Contents

1.1. Nature of Chemical Stressor

................................ ................................ ................................ .................... 4

1.2. Potential Risks to Non

- target Organisms

................................ ................................ ............................... 4

1.3. Conclusions

- Exposure Characterization

................................ ................................ .............................. 6

1.4. Conclusions

- Effects and Risk Characterization

................................ ................................ .................. 7



### 2. Problem Formulation

................................ ................................ ................................ ........... 9

2.1. Nature of Regulatory Action

................................ ................................ ................................ .................. 10

2.2. Stressor Source and Distribution

................................ ................................ ................................ .......... 10

2.2.1. Nature of Chemical Stressor

................................ ................................ ................................ .............. 10

2.2.2. Overview of Pesticide Usage

................................ ................................ ................................ ............. 11

2.3. Receptors

................................ ................................ ................................ ................................ ................. 11

2.3.1. Aquatic and Terrestrial Effects

................................ ................................ ................................ .......... 11

2.3.2. Ecosystems Potentially at Risk

................................ ................................ ................................ .......... 12

2.4. Assessment Endpoints

................................ ................................ ................................ ............................ 12

2.5. Conceptual Model

................................ ................................ ................................ ................................ ... 13

2.5. 1. Risk Hypotheses

................................ ................................ ................................ ................................ 13

2.5.2. Conceptual Diagram

................................ ................................ ................................ .......................... 13

2.6. Analysis Plan

................................ ................................ ................................ ................................ ........... 15

2.6.1. Residues of Concern

................................ ................................ ................................ .......................... 15

2.6.2. Preliminary Identification of Data Gaps and Uncertainties

................................ ............................... 15

2.6.3. Evaluation of Multiple Active Ingredients and Mixtures

................................ ................................ .. 16

2.6.4. Measures of Exposure

................................ ................................ ................................ ....................... 16

2.6.5. Measures of Effect

................................ ................................ ................................ ............................. 17

2.6.6. Integration of Exposure and Effects

................................ ................................ ................................ .. 19



### 3. Analysis

................................ ................................ ................................ ............................. 20

3.1. Use Characterization

................................ ................................ ................................ .............................. 20

3.2. Exposure Characterization

................................ ................................ ................................ .................... 21

3. 2.1. Environmental Fate and Transport Characterization

................................ ................................ ......... 21

3.2.2. Measures of Aquatic Exposure

................................ ................................ ................................ .......... 25

3.2.3. Measures of Terrestrial Exposure

................................ ................................ ................................ ...... 28

3.3. Ecological Effects Characterization

................................ ................................ ................................ ...... 30

3.3.1. Aquatic Toxicity Assessment

................................ ................................ ................................ ............ 31

3.3.2 Terrestrial Effects Characterization

................................ ................................ ................................ ... 35



### 4. Risk Characterization

................................ ................................ ................................ ......... 39

4.1. Risk Estimation

................................ ................................ ................................ ................................ ....... 39

4.1.1. Aquatic Organisms

................................ ................................ ................................ ............................ 39

4.1.2. Terrestrial Organisms

................................ ................................ ................................ ........................ 41

4.2. Incident Database Review

................................ ................................ ................................ ............................. 50

4.3. Risk Description

................................ ................................ ................................ ................................ ...... 50

4.3.4. Risks to Mammals

................................ ................................ ................................ ............................. 53

4.3.5. Risk to Birds

................................ ................................ ................................ ................................ ...... 54

4.3.6. Potential Effects on Terrestrial Invertebrates

................................ ................................ .................... 55

4.3.7. Risk to Terrestrial Non

- target Plants

................................ ................................ ................................ . 55

4.4. Uncertainties and Data Gaps

................................ ................................ ................................ ................. 57

4.4.1. Fate and Transport

................................ ................................ ................................ ............................. 57

4.4.2. Aquatic Exposure

................................ ................................ ................................ .............................. 58

4.4.3. Effects Uncertainties

................................ ................................ ................................ ......................... 58



### 5. F ederally Threatened and Endangered (Listed) Species Concerns

............................... 59

5.1. Action Area

................................ ................................ ................................ ................................ ............. 60

5.2. Taxonomic Groups Potentially at Risk

................................ ................................ ................................ . 60

5.2.1. Probit Dose

- Response Analysis

................................ ................................ ................................ ...... 63



### 6. References

................................ ................................ ................................ ............................ 65- Page 3 of 115

- 6.1. Submitted Product Chemistry and Environmental Fate Studies

................................ ....................... 66

161

- 1 Hydrolysis

– 014002 Cyanamide Fate

................................ ................................ .................... 66

161

- 2 Photodegradation

- water

................................ ................................ ................................ ............ 66

162

- 1 Aerobic soil metabolism

................................ ................................ ................................ ............ 66

162

- 2 Anaerobic soil metabolism

................................ ................................ ................................ ....... 67

162

- 4 Aerobic aquatic metab.

................................ ................................ ................................ .............. 68

163

- 1 Leach/adsorp/desorption

................................ ................................ ................................ .......... 68

164

- 1 Terrestrial field dissipation

................................ ................................ ................................ ....... 68

165

- 1 Confined rotational crop

................................ ................................ ................................ ........... 69

6.2. Submitted Ecotoxicity Studies

................................ ................................ ................................ ............... 69

71

- 1 Avian Single Dose Oral Toxicity

– 014002 Cyanamide Eco

................................ ................ 69

71

- 2 Avian Dietary Toxicity

................................ ................................ ................................ .................. 70

71

- 4 Avian Reproduction

................................ ................................ ................................ ...................... 70

72

- 1 Acute Toxicity to Freshwater Fish

................................ ................................ ............................ 70

72

- 2 Acute Toxicity to Freshwater Invertebrates

................................ ................................ ............ 71

72

- 3 Acute Toxicity to Estuarine/Marine Organisms

................................ ................................ ..... 71

72

- 4 Fish Early Life Stage/Aquatic Invertebrate Life Cycle Study

................................ ............. 71

122

- 1 Seed Germination/Seedline Emergence and Vegetable Vigor

................................ ........ 72

122

- 2 Aquatic pl ant growth

................................ ................................ ................................ .................. 72

141

- 1 Honey bee acute contact

................................ ................................ ................................ ........... 73



### Appendix A. Submitted Ecological Effects Data for Hydrogen Cyanamide

........................ 74

Appendix B. Catalogue of Submitted Environmental Fate Studies for Hydrogen

cyanamide.

................................ ................................ ................................ ................................ ... 77

Appendix C. PE5 Output File

................................ ................................ ................................ .... 81

Appendix D. Example Terrestrial Exposure Model Inputs/Outputs

................................ ... 100

Appendix E. Reported Hydrogen Cyanamide Ecological Incident Summaries in the EIIS

Database

................................ ................................ ................................ ................................ ..... 108- Page 4 of 115

- 

## 1. Executive Summary

1.1. Nature of Chemical Stressor

Under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) and in order to ensure

that registered pesticides meet current scientific and regulatory standards, EPA is initiating the

re

- registration of hydrogen cyanamide (CH

2 

### N

2 

### ; CAS#: 420

- 04

- 2; PC code: 014002). Hydrogen

cyanamide is a restricted use plant growth regulator currently registered (under Section 3 of

FIFRA) for use on various crops. It is applied to the plant buds approximately 30 days before

bud break to synchronize blossoming and/or produce a more uniform bud break in plants that

have received less than their full chill hour requirement.

There is no clear understanding of the physiological and biochemical mode of action of hydrogen

cyanamide and other chemicals used in dormancy

- breaking. However, in a recent report by

Perez and Vergara (2009) it is suggested that hydro gen cyanamide and other dormancy

- breaking

compounds act by transiently inhibiting respiration, thereby triggering processes leading to shoot

growth and flowering.

This assessment is for a national registration request for the following uses: apples, blueb erries,

cherries, grapes (wine and raisin; desert; non

- desert)

, kiwi fruit (California only), peaches and

nectarines. It is registered under FIFRA section 24(c) on the following crops: blackberries in

Georgia (GA03000600), figs in California (CA04000200) a nd grapes in Hawaii (HI03000300).

Maximum single application rates range from 6.6 to 17.6 lbs a.i./A

- yr. This assessment is based

on proposed maximum application rates for all uses.

Hydrogen cyanamide and its degradates are potentially mobile in soil sin ce they are soluble in

water and were primarily associated with the aqueous phase in both the anaerobic soil

metabolism and batch equilibrium studies in this review. However, the use of hydrogen

cyanamide should not pose a significant additional ground wat er threat . This is due to the fact

that the parent compound is not persistent, and the degradates are short

- 1ived, ubiquitous, low

molecular weight organic nitrogen compounds that can be readily incorporated into the

metabolism of microbes and higher plant s.

1.2. Potential Risks to Non

- target Organisms

The results of this screening

- level assessment on the proposed hydrogen cyanamide uses indicate

that risk from acute and chronic exposure is expected for birds, reptiles, terrestrial

- phase

amphibians, and mammals. Risk is also expected for plants, especially during the most sensitive

life

- stage of seedling emergence. Potential acute risk to listed mollusks is indicated based on

marginal exceedance of the LOC. In addition, chronic risk to freshwater and estuarine/marine

fish can not be precluded. Table 1.1 describes the potential for direct effects to listed species by

taxa from the registered uses of hydrogen cyanamide.- Page 5 of 115

- 

### Table 11 . Potential Effects to Federa lly Listed Taxa Associated with Direct Effects from

the Registered Uses of Hydrogen C yanamide.

Listed Plant Taxon Potential Direct Effects

Terrestrial and semi

- aquatic

plants

– monocots and dicots Yes

Aquatic nonvascular plants Uncertain 7,8

Aquatic vascular plants No

Listed Animal Taxon Potential Direct Effects

Acute Chronic

Terrestrial invertebrates Uncertain 1 ND

Mammals Yes 2,3,5 Yes 3,5

Birds Yes 2,4,5 Yes 4,5

Reptiles Yes 2,4, 5 Yes

A mphibians No effect 6 Uncertain 7,9

Freshwater fish No effect 6 Uncertain 7,9

Freshwater invertebrates No effect 6 No effect 10

Mollus k s No effect 6 ND

E stuarine /marine fish No effect 6 Uncertain 7,11

E stuarine /marine invertebrates No effect 6 Uncertain 7

, 12

ND Not determined.

1 Although no effects were seen in the acute contact toxicity tests with honey bees, the limit dose (36.2 μg a.i./bee) was not high

enough to preclude risk at the listed species LOC, based on the relatively high hydrogen cyanamide EECs for registered uses.

2 Risks to terrestrial animals from exposure to hydrogen cyanamide are extensive as a result of the high application rates curr ently

registered for use.

3 Based on its reported toxicity to mammals, the maximum application rate that would not result in ac ute or chronic risk concerns

is 0.65 lb a.i./A or 0.005 lb a.i./A, respectively. Chance of individual effect for listed species is 1 in 1 at derived RQ.

4 Based on its reported toxicity to birds, the maximum application rate that would not result in acute risks is 0.32 lb a.i./A, while

the application rate that would not result in chronic risks is 0.64 lb a.i./A. Chance of individual effect for listed species is 1 in 1 at

derived RQ.

5 Risk may be limited by geographic and temporal use patterns of hydrogen cyanamide ( i.e., it is only for use on a nectarines,

peaches, blackberries, blueberries, figs, apples, cherries, grapes, and kiwi fruits; it is subject to several geographic use

restrictions; and is only applied December through March).

6 Risk of direct effects from acute aquatic exposure to formulated hydrogen cyanamide is expected to be below the LOC.

7 EECs are primarily driven by the modeled run

- off, which assumes no buffer between the site of application and the water body.

Hydrogen cyanamide degrades rapidly in soil (aerobic soil half

- life of 12 hours in sandy loam soil), and the aerobic aquatic

metabolism half

- life value of 5.28 days represents the 90 th percentile of the upper confidence bound for the mean of the two

available half

- life values (3.2 days in a pond system and 1.2 days in a stream system). Therefore chronic risks to aquatic

organisms may be overestimated.

8 T he acute listed species RQ is equal to the LOC for non

- vascular plants exposed to hydrogen cyanamide from the ch erry use

only. EECs would only need to drop ~1% to result in RQs below the level of concern.

9 Current data on the freshwater species, rainbow trout, are not adequate to derive a definitive NOAEC because effects were

noted at all test concentrations. Since the available LOAEC is within one order of magnitude of the highest EEC, chronic risk to

listed freshwater fish cannot be precluded. However, the magnitude of biological effects observed at the lowest concentration

level appears to be close to the limit o f statistical and biological significance.

10 Risk of direct effects from chronic aquatic exposure to formulated hydrogen cyanamide is expected to be below the LOC.

11 Chronic toxicity data was not available for estuarine/marine fish. It is not possible to calculate an acute

- to

- chronic ratio (ACR)

because only a non

- definitive NOAEC is available for the freshwater fish. This represents a substantial data gap in the analysis.

Based on the available acute toxicity data, estuarine/marine fish exhibit simila r toxicity as freshwater fish so it is likely that they

exhibit similar toxicity on a chronic exposure basis.

12 C hronic toxicity data is not available for estuarine/marine invertebrates, RQs calculated based on an ACR for the daphnid

range from well below the listed species LOC to just exceeding the listed species LOC

.



### Risks to aquatic organisms may be mitigated by the 900 ft buffer required on all hydrogen

cyanamide labels between the site of application and “the mean high water mark for intertidal

areas, surface waters, rivers, streams, or their flowing tributaries” to limit the potential for

exposure of hydrogen cyanamide to aquatic environments. While aquatic EECs were mo deled- Page 6 of 115

- 

### using a 900 ft buffer for drift, the Agency does not currently have a method for modeling the

impact of a buffer on run

- off. Therefore, EECs are primarily driven by the modeled run

- off,

which assumes no buffer between the site of application and the water body. Given the rapid

degradation of hydrogen cyanamide in soil, this is a major source of uncertainty in the aquatic

exposure and subsequent risk assessment. As a result of this limitation risks to aquatic organisms

may be overestimated.

Risks to terrestrial organisms from exposure to hydrogen cyanamide are extensive because of the

high application rates currently registered for use. Based on derived RQs, the c hance of an

i dividual e ffect to a listed bird or mammal is 1 in 1 after exposure to hydr ogen cyanamide

. In

fact, b ased on its reported toxicity to mammals, the maximum application rate of hydrogen

cyanamide that would not result in acute or chronic risk concerns is 0.65 lb a.i./A or 0.005 lb

a.i./A, respectively

. For birds, the maximum appli cation rate that would not result in acute risks

is 0.32 lb a.i./A, while the application rate that would not result in chronic risks is 0.64 lb a.i./A.

However, these risks may be mitigated by the geographic and temporal limitations of the

chemical. Hydro gen cyanamide is only registered for use on a limited number of fruit bearing

trees and ground fruit, including: nectarines, peaches, blackberries, blueberries, figs, apples,

cherries, grapes, and kiwi fruits. Further, g eo graphic restrictions outlined on t he labels limit the

use of hydrogen cyanamide on certain crops and in certain regions . For example, use on

blueberries is limited to Florida and use on grapes is limited to California and Arizona (see

Table 3.1 for more information). Th es e limited use pattern s for hydrogen cyanamide may result

in substantially less overlap with endangered species habitat than a chemical with a ubiquitous

use pattern ( e.g., corn)

. In addition to these geographic boundaries, labels state that hydrogen

cyanami de is to be applied 30 days prior to normal bud break. For the assessed uses this means

that application occurs between December and March (see Table 3.6 for more information)

. The

temporal and geographic limitations suggest that potential for acute risks are limited to those

species that are active in late winter , especially in temperate regions of the country

. The

exception may be for uses of hydrogen cyanmide in areas with winters mild enough that birds

and mammals remain active and plants do not senesce ( e.g., Ca lifornia, Hawaii, and Florida). In

addition, the chemical properties and available residue data suggest that hydrogen cyanamide

degrades rapidly in the environment. Without prolonged exposure, chronic risks to terrestrial

animals may be overestim ated

.

For terrestrial plants, AgDRIFT was used to refine potential exposure to vegetatively active

plants from drift of hydrogen cyanamide off of the field. Based on this analysis, airblast

applications for the orchard uses and ground spray for the other uses limit the potential for

exposure from drift such that most of the assessed species would not be expected to be at risk

beyond the edge of the field. Exposure through run

- off may still be a concern; however, risks

from run

- off may be over estimated g iven the rapid degradation of hydrogen cyanamide in soil

as discussed previously

.

1.3. Conclusions

- Exposure Characterization

Hydrogen cyanamide is expected to dissipate quickly in both terrestrial and aquatic environments- Page 7 of 115

- 

### under aerobic and anaerobic conditions (aerobic soil metabolism t 1/2 

### of 12 hours; and t 1/2 

### 1.2

- 3.2

day under aerobic aquatic conditions), and is considered highly mobile and nonvolatile. Aerobic

metabolism is considered the major route of degradation. Abiotic degradation processes

(hydrolysis and photolysis) are not important, as metabolism is much quicker. Cyanamide is

completely soluble in water. Hydrogen cyanamide is considered highly mobile. There is no

evidence of degradation via hydrolysis, which was studied across environmental pHs. Hydrogen

cyanamide does not bioconcentrate in aquatic organisms ( Log K

ow 

### - 0.82). 

### The use of hydrogen

cyanamide should not pose a significant additional ground water threat since the parent

compound is not persistent, and the degradates are short

- 1ived, ubiquitous, low molecular weight

organic nitrogen compounds that can be readily incorporated into the metabolism of microbes

and higher plants.

Aquatic exposure estimates are based on the exposure of the parent compound hydrogen

cyanamide only. D egradates are short

- 1ived, ubiquitous, low molecular weight organic nitrogen

compounds that can be readily incorporated into the metabolism of microbes and higher plants.

The conservative aquatic exposure estimates (for all uses modeled) result in the high

- end

exposure for each type of application method. The range of uses is listed in Table 3.1.

Acute 1

- in

- 10 year estimated environmental concentrations (EECs) in surface water for all

modeled uses of hydrogen cyanamide ranged from 9.35 μg/L to 9 2.0 μg/L with the addition of a

900 ft buffer as required on product labels.

In addition, registered labels for hydrogen cyanamide products include a language requiring a

900 ft buffer between the site of application and “the mean high water mark for intertidal areas,

surface waters, rivers, streams, or their flowing tributaries” to limit the potential for exposure of

hydrogen cyanamide to aquatic environments. While aquatic EECs were modeled using a 900 ft

buffer for drift, the Agency does not current ly have a method for modeling the impact of a buffer

on run

- off. Therefore, EECs are primarily driven by the modeled run

- off, which assumes no

buffer between the site of application and the water body. Given the rapid degradation of

hydrogen cyanamide in s oil, this is a major source of uncertainty in the aquatic exposure and

subsequent risk assessment. As a result of this limitation risks to aquatic organisms may be

overestimated , except in areas where channelized flow occurs

.

1.4. Conclusions

- Effects and Risk Characterization

Aquatic Organisms

Results of acute toxicity studies indicate that hydrogen cyanamide is “slightly toxic” to

freshwater and estuarine/marine fish and “moderately toxic” to freshwater and estuarine/marine

invertebrates on an acu te exposure basis. Toxicological sings oberseved in fish included

quiescence, ceased swimming, dark discoloration, hyperexcitability, and erratic swimming.

Acute risks to fish and aquatic invertebrates are not expected.- Page 8 of 115

- 

### Available chronic toxicity data for freshwater fish reported a NOAEC value for reproducti ve

endpoints ( i.e., days to hatch, days to swimup, and hatch survival) as 2.03 ppm with an

associated LOAEC of 4.03 ppm. However, effects on growth endpoints ( i.e. , l ength and wet

weight) were observed at all treatment levels; therefore, the NOAEC for this study was <0.507

and the LOAEC was 0.507. While r isk quotients could not be calculated for freshwater fish on a

chronic exposure basis because of the non

- definitive NOAEC, 

## the magnitude of biological

effects observed at the lowest concentration tested appear to be close to the limit of statistical

and biological significance. This information, combined with the likely overestimation of

EECs as a result of the run

- off modeling discussed above , suggest that while chronic risks to

freshwater fish can not be precluded they are likely low.

Chronic data was not available for estuarine/marine fish. Based on the available acute toxicity

data, estuarine/marine fish exhibit s imilar toxicity as freshwater fish so it is likely that they

exhibit similar toxicity on a chronic exposure basis. In addition, available aerobic aquatic

metabolism data (1.2 days in a stream system) suggests that hydrogen cyanamide degrades faster

under f lowing conditions, such as may be found in some estuarine/marine systems. As a result of

this shorter half

- life, while chronic risks can not be precluded, those estuarine/marine fish that

reside in flowing waters may be low.

Chronic risk to freshwater i nvertebrates is expected to be low based on chronic toxicity data

submitted for the daphnid, with RQs ranging from 0.06 to 0.69. Chronic toxicity data is not

available for estuarine/marine invertebrates. The acute to chronic ratio (ACR) for the daphnid

(mo st sensitive freshwater invertebrate) was applied to the available acute mollusk (the most

sensitive estuarine/marine invertebrate) and acute Mysid shrimp data in order to bracket the

potential for chronic effects to estuarine/marine invertebrates. Uncerta inties associated with this

approach are discussed further in the uncertainties section. When the ACR was used to estimate

chronic toxicity to the eastern oyster, RQs ranged from 0.09 to 1.0, indicating potential for risks

to estuarine/marine mollusks from chronic exposure from hydrogen cyanamide use on cherries.

Additionally, when the ACR for the daphnid were applied to the acute toxicity value available

for the pink shrimp (LC 50 

### = 6300 ppb), RQs ranged from 0.03 to 0.36, suggesting that the

potential for chronic risk to crustaceans is low. With this information chronic risks to mollusks

can not be precluded but risks to crustaceans are likely low.

Although hydrogen cyanamide does exhibit effects on both Lemna gibba and Anabaena flos

aquae , these effects are at much higher concentrations than those estimated for the majority of

the hydrogen cyanamide uses. However, the acute listed species RQ is equal to the LOC for

non

- vascular plants exposed to hydrogen cyanamide from the cherry use, which indicates tha t

risks to listed and non

- listed aquatic non

- vascular plants may occur

. However, EECs are

primarily driven by the modeled run

- off, which assumes no buffer between the site of application

and the water body. Given the 900 ft buffer required between the site of application and any

waterbody and the rapid degradation of hydrogen cyanamide in soil, exposure to aquatic

environments may be over estimated . As a result of this limitation risks to aquatic non

- vascular

plants may be overestimated. In fact, EECs for u se of hydrogen cyanamide on cherries would

only need to drop ~1% to result in RQs below the level of concern. In addition, risk to aquatic

nonvascular species is typically evaluated with not only the cyanobacteria species that was- Page 9 of 115

- 

### submitted, but also with a green algae, a centric diatom and a pinnate diatom. Acceptable studies

with these species have not been submitted and are an appreciable source of uncertainty in the

risk assessment. These planktonic taxa form the basis of the aquatic food web and are frequently

more sensitive to pesticides than cyanobacteria. Without data on these additional species, and

considering the listed species RQ is equal to the LOC for the highest use pattern, risks to aquatic

plants can not be precluded.

Terrestrial Organi sms

Results of toxicity studies indicate that hydrogen cynamide is “moderately toxic” to mammals on

an acute exposure basis. Acute risk concerns were triggered for all assessed uses of hydrogen

cyanamide

. Results of the screening model SIP also indicate that drinking water exposure is a

potential concern for mammals based on acute and chronic exposure.

Results of toxicity studies indicate that hydrogen cynamide is “moderately toxic” to birds on an

acute dose

- based exposure basis , while it is “practical ly non

- toxic” on an acute dietary

- based

exposure basis. Acute dose

- based risk concerns were triggered for all assessed uses of hydrogen

cyanamide. Results of the screening model s SIP and STIR indicate that drinking water and

inhalation exposure are also of potential concern for birds based on acute and chronic exposure.



## An acute contact toxicity study (MRID 438669

- 02) showed that cyanamide is essentially

non

- toxic to the honey bee (LD50 >36.2 mg a.i./bee, and NOEL approximately 12 mg

a.i./bee). However

, the high application rates used may pose risks to be es as a result of high field

residues (max EECs are over 1 6 00 ppm a.i.). A foliar dissipation study would reduce

uncertainties associated with risks to beneficial insects.

For hydrogen cyanamide, seedl ing emergence is a much more sensitive life stage than vegetative

vigor. Though there are substantial uncertanites associated with the risk picture for plants as a

result of the quality of the available seedling emergence data (discussed in section 3.3.2.4 )

, observable effects on plants at rates considerably lower than labeled rates trigger concerns for

listed and non

- listed plants

.

2. Problem Formulation

The purpose of problem formulation is to provide the foundation for the environmental fate and

ecolo gical risk assessment for the registration review risk assessment for the growth regulator

hydrogen cyanamide , ( CH

2 

### N

2 

### ; CAS#: 420

- 04

- 2 ; PC code: 014002 ). The problem formulation

sets the objectives for the risk assessment, establishes a risk hypothesis and conceptual model

depicting potential risk, and provides a plan for analyzing the data and characterizing the risk

associated with the proposed use of hydrogen cyanamide (USEPA, 1998).- Page 10 of 115

- 

### 2.1. Nature of Regulatory Action

The U.S. Environmental Protection Agency (EPA or the Agency) is required under the Federal

Insecticide, Fungicide, and Rodenticide Act (FIFRA) to ensure that the currently registered

p esticide s, including hydrogen cyanamide

, remain eligible for reregistrtion and do not result in

unreasonable adverse effects to the environment. In addition to non

- target animals and plants,

potential effects to listed species ( i.e. , species on the Federa l list of endangered and threatened

wildlife and plants) and their designated critical habitat are also considered under the

Endangered Species Act (ESA) in order to ensure that the continued registration of hydrogen

cyanamide is not likely to jeopardize t he continued existence of listed species or adversely

modify their critical habitat. In order to meet the requirements of FIFRA and the ESA, this

assessment follows EPA guidance on conducting ecological risk assessments (USEPA, 1998)

and Office of Pestici de Program’s Overview Document, which contains guidance for assessing

pesticide risks to non

- target and listed organisms (USEPA, 2004).

The end result of the EPA pesticide registration process ( i.e. , the FIFRA regulatory action) is an

approved (or disappr oved) product label. The label is a legal document that stipulates how and

where a given pesticide may be used. Product labels (also known as end

- use labels) describe the

formulation type ( e.g. , liquid or granular), acceptable methods of application, app roved use sites,

and any restrictions on how applications may be conducted. Therefore, the use, or potential use,

described by the pesticide’s labels is considered “the action” being assessed. This assessment

was prepared to support evaluation of the re r egistration of hydrogen cyanamide

.

2.2. Stressor Source and Distribution

2.2.1. Nature of Chemical Stressor

Hydrogen cyanamide is a plant growth regulator used to promote uniform bud break in fruit trees

and vines. Based on the rapid metabolism of this chemical, residues are not expected at harvest.

All registered uses can be considered non

- food uses. Hydrogen cyanamide is currently

registered for use under FIFRA Section 3 on the following bearing fruit trees and vines prior to

bud

- break: apples, blueberries, cherries, grapes (wine and raisin; kiwi fruit (California only),

peaches, and nectarines. Hydrogen cyana mide is formulated as a soluble concentrate and may be

applied using airblast or backpack sprayers. Hydrogen cyanamide is not registered for residential

use.

The mode of action is poorly understood (Or et al . 2000, 2002 ; Pe rez and Burgos 2004). It was

suggested that hydrogen cyanamide and other dormancy

- breaking compounds act by transiently

inhibiting respiration, thereby triggering processes leading to shoot growth and flowering (Pe rez

et al., 2008). The stresser of concern is the paerent only. D egrada tes are short

- 1ived, ubiquitous,

low molecular weight organic nitrogen compounds that can be readily incorporated into the

metabolism of microbes and higher plants.- Page 11 of 115

- 

### 2.2.2. Overview of Pesticide Usage

The Biological and Economic Analysis Division’s (BEAD) Screening Level Usage Analysis

(SLUA; USEPA 201 2 ) shows that an average of 263 ,000 lbs of hydrogen cyanamide is applied

annually on various crops (Table 2 .1 ). The SLUA also reports that grapes and cherrries were the

top crops treated with hydrogen cyanam ide

.

Table 2. 1. Screening Level Estimates of Agricultural Uses of Cyanamide (014002 )

Sorted Alphabetically

Crop Lbs. A.I. Percent Crop Ttd.

Avg. Max.

1 Apples 5 ,000 <1 <2.5

2 Blueberries 2,000 <2.5 <2.5

3 Cherries 100 ,000 5 10

4 Figs * 2,000 ND ND

5 Grapes 1 4 0,000 10 20

6 Kiwifruit * 1 4 ,000 ND ND

All numbers rounded.

<2.5 Less than 2.5 percent of crop treated

<1 Less than 1 percent of crop treated

ND No data

* Based on CA DPR data only (valid because 95% or more of U.S. acres grown are in California)



### 2.3. Receptors

2.3.1. Aquatic and Terrestrial Effects

In ecological risk assessment, a receptor is a biological entity that is exposed to a stressor

(USEPA, 1998). Consistent with the process described in the Overview Document (USEPA,

2004), this risk assessment uses a surrogate species approach in its evalu ation of hydrogen

cyanamide . Toxicity data generated using surrogate test species, which are intended to be

representative of broad taxonomic groups, are used to infer potential effects on a variety of

species (receptors) included under these broader taxo nomic groupings. Table 2. 2 provides the

general taxonomic groups and surrogate species tested to evaluate potential ecological effects of

hydrogen cyanamide to broad classes of non

- target organisms. Within each of these taxonomic

groups, a measure of eff ect is selected from among the available test data.

Table 2. 2 . Taxonomic Groups and Test Species Evaluated for Assessing Potential

Ecological Effects of Hydrogen cyanamide

. Taxonomic Group Typical Species

Birds 1 Mallard duck ( Anas platyrhynchos )

Bobwhite quail ( Colinus virginianus )

Mammals Norway rat ( Ratus norvegicus )

Invertebrates Honey bee ( Apis mellifera L. )- Page 12 of 115

- 

### Table 2. 2 . Taxonomic Groups and Test Species Evaluated for Assessing Potential

Ecological Effects of Hydrogen cyanamide

. Taxonomic Group Typical Species

Freshwater fish 2 Bluegill sunfish ( Lepomis macrochirus )

Rainbow trout ( Oncorhynchus mykiss )

Fathead minnow ( Pimephales promelas )

Freshwater invertebrates Water flea ( Daphnia magna )

Midge ( Chironomus riparius )

Estuarine/marine fish Sheepshead minnow ( Cyprinodon variegatus )

Estuarine/marine invertebrates Mysid ( Americamysis bahia )

Eastern oyster ( Crassostrea virginica )

Terrestrial plants 3 Monocots

– # Crop species, such as corn ( Zea mays )

Dicots

– # Crop Species, such as soybean ( Glycine max )

Aquatic plants and algae Duckweed ( Lemna gibba )

Freshwater Algae ( Pseudokirchneriella subcapitata and

Anabaena flos

- aquae )

1 Birds represent surrogates for terrestrial

- phase amphibians and reptiles.

2 Freshwater fish may be surrogates for aquatic

- phase amphibians.

3 Four species of two families of monocots, of which one is corn; six species of at least four dicot families, of w hich one is soybeans.



### 2.3.2. Ecosystems Potentially at Risk

The ecosystems potentially at risk are often extensive in scope; therefore, it may not be possible

to identify specific ecosystems during the development of a nation

- wide ecological risk

assessment. However, in general terms, terrestrial ecosystems potent ially at risk could include

the treated field and immediately adjacent areas that may receive drift or runoff. Areas adjacent

to the treated field could include cultivated fields, fencerows and hedgerows, meadows, fallow

fields or grasslands, woodlands, r iparian habitats, and other uncultivated areas.

Aquatic ecosystems potentially at risk include water bodies adjacent to or downstream from use

sites, and might include impounded bodies such as ponds, lakes and reservoirs, or flowing

waterways such as st reams or rivers including all adjacent off

- channel habitats that are

permanently or intermittently connected to flowing waters. For uses in coastal areas, aquatic

habitat also includes marine ecosystems, including estuaries, embayments, and near

- shore

envi ronments such as tidal marshes.

2.4. Assessment Endpoints

Assessment endpoints represent the actual environmental value that is to be protected, defined by

an ecological entity (species, community, or ot her entity) and its attribute or characteristics

(USEPA, 1998). For hydrogen cyanamide , ecological entities of potential concern include the

following: birds, amphibians, reptiles, mammals, freshwater fish and invertebrates,

estuarine/marine fish and inv ertebrates, non

- target terrestrial plants, terrestrial invertebrates, and

aquatic vascular and non

- vascular plants. The attributes for each of these entities may include

growth, survival, and reproduction ( Table 2. 3 in Section 2.6.4 ).- Page 13 of 115

- 

### 2.5. Conceptual Model

For a pesticide to pose an ecological risk, it must reach ecological receptors in biologically

significant concentrations. An exposure pathway is the means by which a pesticide moves in the

environment from a source to an ecological receptor. For an ecological pathway to be complete,

it must have a source, a release mechanism, an environmental transport mechanism, and a

feasible route of exposure.

The conceptual model is intended to provide a written description and visual representation of

anticipated relationships between hydrogen cyanamide , potential routes of exposure, and the

predicted effects for the assessment endpoints. The conceptual model consists of two major

components: risk hypotheses and a conceptual diagram (USEPA, 1998).

2.5.1. Risk Hypotheses

Risk hypotheses are specific assumptions about potential adverse effects ( i.e., changes in

assessment endpoints) and may be based on theory and logic, empirical data, mathematical

models, or probability models (USEPA, 1998) . For this assessment, the risk is stressor

- linked,

where the stressor is the release of hydrogen cyanamide to t he environment. The following risk

hypotheses are presumed in this assessment:

Hydrogen cyanamide , when used outdoors in accordance with registered labels, will

likely lead to off

- site movement of the compound via agricultural runoff and spray drift

lead ing to exposure of nontarget plants and animals

. Based on information on the

environmental fate, mode of action, direct toxicity and potential indirect effects, EFED

assumes that registered uses of hydrogen cyanamide have the potential to cause reduced

su rvival, growth, and reproduction to non

- target terrestrial and/ or aquatic animals and

plants.

2.5.2. Conceptual Diagram

The conceptual model is a graphical representation of predicted relationships between ecological

receptors, both listed (threatened and endangered) and non

- listed, and the stressors to which they

may be exposed. A conceptual model specifies potential rout es of exposure, biological receptor

types, and effects endpoints of potential concern.

Hydrogen cyanamide is expected to dissipate quickly in both terrestrial and aquatic environments

under aerobic and anaerobic conditions (aerobic soil metabolism t 1/2 

### of 12 hours; and t 1/2 

### 1.2 and

3.2 day under aerobic aquatic conditions), and is considered highly mobile and nonvolatile.

Aerobic metabolism is considered the major route of degradation. Abiotic degradation processes

(hydrolysis and photolysis) are not i mportant, as metabolism is much quicker. Cyanamide is

completely soluble in water, and in batch equilibrium experiments less than 2% of the mass

adsorbed to sandy and silt loam soil. Thus, it is expected to be very mobile in soil

- water systems.

The degrada tes of cyanamide include simple nitrogen compounds (dicyanodiamide, guanylurea,- Page 14 of 115

- 

### guanidine, and urea) which are readily utilized as plant nutrients.

The use of hydrogen cyanamide should not pose a significant additional ground water threat

since the parent compound is not persistent, and the degradates are short

- 1ived, ubiquitous, low

molecular weight organic nitrogen compounds that can be readily incorporated into the

metabolism of microbes and higher plants.

Hydrogen cyanamide is applied as a spray 30 da ys before bud break

. Figure 2.1 depicts the

stressors, exposure pathways, and potential effects to terrestrial organisms from proposed uses of

hydrogen cyanamide. Figure 2.2 depicts the stressors, exposure pathways, and potential effects

to aquatic organ isms from proposed uses of hydrogen cyanamide. For both figures, dotted lines

indicate exposure pathways that are expected to have a low likelihood of contributing to

ecological risk.

Figure 2.1. Conceptual model for hydrogen cyanamide effects on aquatic and terrestrial organisms.- Page 15 of 115

- 

### 2.6. Analysis Plan

2.6.1. Residues of Concern

In this assessment, the parent (hydrogen cyanamide) is t he only residue of concern. There is no

concern for the degradates. The degradates of cyanamide include simple nitrogen compounds

(dicyanodiamide, guanylurea, guanidine, and urea) which are readily utilized as plant nutrients.



### Chemical names, chemical stru ctures, and data on the formation of these degradates are provided

in Table 3.4.

2.6.2. Preliminary Identification of Data Gaps and Uncertainties

For the purposes of this assessment, data gaps refer to the absence of necessary data for a

complete risk assessment . A catalog u e of submitted ecological effects data for hydrogen

cyanamide is available in Appendix A . Without eco

- toxicity data or evidence to demonstrate

otherwise, risk to non

- listed and listed species of a taxon is presumed. An area of considerable

uncertainty for this assessment surrounds potential chronic risk to birds. Current data on mallard

duck are inadequate to derive a definitive NOAEC or make a definitive determination of risk

(effects were noted at all test concentrations). W hile chronic risk was identified for birds based

on the available bobwhite quail study, a second avian reproduction study on mallard duck that

results in derivation of a NOAEC would reduce uncertainty.

Acute oral toxicity data is not available for a pass erine species , resulting in another area of

substantial uncertainty

. In the absence of this data, risk will be presumed for passerine species. In

addition, the avoidance behavior observed in the sub

- acute dietary study with the mallard duck

(as indicated b y reduced feed consumption and weight loss at all treatment levels) suggests

potential for adverse effects to passerines from advoidance or regurgitation behavior as well. An

acute oral toxicity study with a passerine species, or a sub

- acute dietary study if regurgitation is

observed, would reduce this uncertainty.

Another area of uncertainty surrounds the potential for chronic risks to aquatic animals. Current

data on the freshwater species, rainbow trout, are not adequate to derive a definitive NOAEC

be cause effects were noted at all test concentrations. Chronic data are not available for an

estuarine/marine fish or invertebrate species, introducing additional uncertainties. Acute to

chronic ratios (ACRs) were not appropriate for use in lieu of actual da ta because 1) the chronic

freshwater fish study did not have a definitive NOAEC value and 2) the most sensitive

estuarine/marine invertebrate, the eastern oyster, does not have a similar life history to the

available freshwater species, the daphnid. Addit ionally, the Agency has only received data for

two species of non

- vascular aquatic plants , instead of the four species typically required

. Without

this data risks to this taxa of aquatic plants may be underestimated.

There are additional uncertainties associated with the available plant toxicity data. Though tier II

t errestrial plant toxicity data are available for hydrogen cyanamide , considerable variability in

the available data for certain species, most notably vari ability in plant height for the most

sensitive species in the seedling emergence study, increases the uncertainty associated with the- Page 16 of 115

- 

### plant toxicity data. For example, d e finitive EC 25 

### and NOAEC values were not determined for the

most sensitive dicot (lettu ce emergence) due to high variability in the available data. The

NOAEC for lettuce is therefore less than 0.056, the lowest dose tested. The next most sensitive

dicot species was carrot based on dry weight, with NOAEC and EC 25 

### values of 0.22 and 0.60 lb

a. i./A , respectively . This indicates that hydrogen cyanamide may affect seedling emergence at

rates up two orders of magnitude below the currently registered application rates. For the

purposes of this risk assessment, the LOAEC value for lettuce of 0.056 lb s a.i./A was used to

characterize the lower bounds of risk from exposure to terrestrial plants to hydrogen cyanamide.

For the purposes of risk assessment the submitted environmental fate data are adequate. The

quality of the submitted data is adequate. A catalog of submitted environmental fate studies for

hydrogen cyanamide and its degradates, along with justified review classifications, can be found

in Appendix B

.

2.6.3. Evaluation of Multiple Active Ingredients and Mixtures

The Agency does not r outinely include in its risk assessments an evaluation of mixtures of active

ingredients, either those mixtures of multiple active ingredients in product formulations or those

in the applicator’s tank. In the case of the product formulations of active ing redients (that is, a

registered product containing more than one active ingredient), each active ingredient is subject

to an individual risk assessment for regulatory decision regarding the active ingredient on a

particular use site. If effects data are a vailable for a formulated product containing more than

one active ingredient, they may be used qualitatively or quantitatively in accordance with the

Agency’s Overview Document and the Services’ Evaluation Memorandum (U.S. EPA 2004;

U.S. FWS/NMFS 2004).

Current registered labels of hydrogen cyanamide do not specify the use of other active

ingredients in tank mixtures. However, language does indicate that hydrogen cyanamide should

not be applied within 14 days of dormant sprays containing oil or within 30 days of dormant

sprays containing copper as this may lead to crop damage or reduced insect/disease control.

2.6.4. Measures of Exposure

Measures of exposure are based on aquatic and terrestrial models that estimate environmental

concentrations of hydrogen cyanamide using labeled application rates and methods. For aquatic

exposure the Tier II model Pesticide Root Zone Model (PRZM v3.12.2; May 12, 2005) linked

with EXposure Analysis Modeling System (EXAMS v2.98.4.6; Apr. 25, 2005) via the

PRZM/EXAMS model shell (PE v5.0, Nov. 15, 2006), i.e. , PRZM/EXAMS) was used to

estimate screening

- level exposure concentrations in aquatic environments. The measure of

exposure for aquatic species in surface water bodies receiving runoff and/or spray drift is a re turn

frequency of 1

- in

- 10 years of the estimated environmental concentrations (EEC), based on 30

- year simulations. The maximum 1

- in

- 10 year return frequency concentration is used for

estimating acute exposures to aquatic organisms (plants and animals); th e 1

- in

- 10 year 21

- day

mean concentration is used for assessing aquatic invertebrate chronic exposure; and the 1

- in

- 10- Page 17 of 115

- 

### year 60

- day mean concentration is used for assessing chronic exposure for fish (and aquatic

phase amphibians for which fish serve as surro gates).

Terrestrial exposure estimates for avian and mammalian risk assessments were derived using the

T

- REX model (version 1. 5

, 3/22/2012 ). T

- REX is used to calculate dietary and dose

- based

EECs of hydrogen cyanamide for birds (and surrogates) and mam mals inhabiting terrestrial

areas. T

- REX simulates a 1

- year time period. The default foliar dissipation half life of 35 days

(Willis and McDowell 1987) is used as input to T

- REX. Use

- specific input values, including

number of applications, application r ate and application interval are also inputs.

Exposure for terrestrial plants inhabiting dry and semi

- aquatic areas ( e.g. , low

- lying wet areas

that may dry up at times throughout the year), using TerrPlant v 1.2.1, is based on the following:

(1) the pes ticide's water solubility and the amount of pesticide present on the soil surface

and its top one centimeter,

(2) potential "sheet runoff" (one treated acre to an adjacent acre) for dry areas,

(3) potential "channel runoff" (10 acres to a distant low

- lying acre) for semi

- aquatic or

wetland areas,

(4) fractional runoff values of 0.01, 0.02, and 0.05 for pesticide water solubilities of <10,

10

- 100, and <100 ppm, respectively

(5) drift assumption of 1% for grou nd and 5% for aerial application

AgDRIFT (v 2.1.1 ) is used to refine drift exposure to terrestrial plants and to refine buffers for

aquatic assessments , providing an estimate of the area of concern for these taxa surrounding the

area of application.

The S creening I mbibition P rogram (SIP v.1.0) was used to calculate an upper bound estimate of

wildlife exposure via drinking water using hydrogen cyanamide ’s solubility avian and

mammalian toxicity endpoints.

The S creening T ool for I nhalation R isk ( STIR v.1 .0) was used to calculate an upper bound

estimate of wildlife exposure via both vapor phase and spray droplet inhalation using hydrogen

cyanamide’s vapor pressure and avian and mammalian toxicity endpoints.

2.6.5. Measures of Effect

Measures of effect are obtained from a suite of registrant

- submitted guideline studies that were

conducted with a limited number of surrogate test species ( Table 2.1) . No additional ecotoxicity

data on hydrogen cyanamide were located, based on an August 2011 query of the open literature

in the publically available version of the ECOTOX database (http://cfpub.epa.gov/ecotox/).

The acute measures of effect used in this baseline assessment are the LD 50 

### (median Lethal Dose),

LC 50 

### (median Lethal Concentration) or EC 50 

### (me dian Effects Concentration). These are

measures of acute toxicity which result in 50% of the respective effect in tested organisms. The

endpoints for chronic measures of exposure are the no observed adverse effect concentration

(NOAEC) and the no observe d adverse effect level (NOAEL). Toxicity studies were submitted- Page 18 of 115

- 

### for freshwater fish and invertebrates, estuarine/marine fish and invertebrates, aquatic plants,

birds, mammals, bees, and other terrestrial invertebrates. The endpoints used for risk

charact erization are derived from studies which underwent review and were classified as

“acceptable” (conducted under guideline conditions and considered to be scientifically valid) or

“supplemental” (conditions deviated from guidelines but the results are consid ered to be

scientifically valid).

Table 2. 3 lists the measures of environmental exposure and ecological effects used to assess the

potential risks of hydrogen cyanamide to non

- target organisms. The methods used to assess the

risk are consistent with th ose outlined in the document “Overview of the Ecological Risk

Assessment Process in the Office of Pesticide Programs” (USEPA, 2004).

Table 2. 3 . Measures of Exposure and Measures of Effect Used in Assessing Potential Risks

Associated with the Proposed Use s of Hydrogen cyanamide

.

Assessment Endpoint Surrogate Species and Measures of

Ecological Effect 1 Measures of Exposure

Birds 2 Survival Lowest acute LD 50 (single oral dose

test) and LC 50 (subacute dietary test) Upper

- bound residues on

food items

Reproduction

and Growth Lowest NOAEC

(21

- week reproduction test)

Mammals Survival Lowest acute LD 50 (single oral dose

test)

Reproduction

and Growth Lowest NOAEC

(2

- generation reproduction test)

Aquatic Animals (Fish and

invertebrates) 3 Survival Lowest tested LC 50 or EC 50 (acute toxicity test) Peak EECs 4

Reproduction

and Growth Lowest NOAEC (early life

- stage or full

life

- cycle tests) 21

- day EECs for invertebrates

and 60

- day EECs for fish 4

Terrestrial plants 5 Survival and

growth Lowest EC 25 (for non

- listed plants) and

corresponding NOAEC (for listed

plants)

(endpoints derived for monocots and

dicots from seedling emergence and

vegetative vigor studies) Estimates of runoff and spray

drift to non

- target areas

Insects 6 Survival (not

quantitatively

assessed) Lowest honeybee LD 50 (acute contact

test)

Lowest Earthworm LC 50 Maximum application rate for

honeybees and estimates of

soil concentrations for

earthworms

Aquatic plants (vascular

and non

- vascular) Survival and

growth Lowest EC 50 (for non

- listed plants) and

corresponding NOAEC or EC 05 (for

listed plants) Peak EECs 4

1 The most sensitive species tested within taxonomic groups is used for screening

- level risk assessments.

2 Birds represent surrogates for terrestrial

- phase amphibians and reptiles.

3 Freshwater fish represent surrogates for aquatic

- phase amphibians.

4 Aquatic EECs are based on modeling described in Section 3.2.2.1

. 5 Four species of two families of monocots

- one is corn, six species of at least four dicot families, of which one is soybeans.

6 Risk to terrestrial invertebrates from hydrogen cyanamide use is not evaluated, rather the potential hazard to honey bees and earthworms (i.e. the

available data) are qualitatively assessed.- Page 19 of 115

- 

### 2.6.6. Integration of Exposure and Effects

Exposure and toxicity data are integrated in order to evaluate the risks of adverse ecological

effects on non

- target species. For the screening

- level risk assessment of hydrogen cyanamide

, the deterministic risk quotient (RQ) method is used to compare estimated exposure

concentrations with measured toxicity values. The RQ method involves dividing point estimates

of environmental concentrations by acute and chronic toxicity values. The resulting unitless RQs

are then compared to the Agency’s Levels of Concern (LOC) (USEPA, 2004) ( Table 2. 4 ).

These criteria are used to indicate when applications of hydrogen cyanamide , as directed on the

proposed labels, have the potential to cause adverse effects to listed and non

- listed non

- target

organisms.

Table 2. 4 . Agency Risk Quotient (RQ) Metrics and Levels of Concern (LOC) Per Risk

Class.

RISK CLASS RISK DESCRIPTION RQ LOC

Aquatic Animals (fish and invertebrates)

Acute Potential for effects to non

- listed animals from acute

exposures Peak EEC/LC 50 1 0.5

Acute

Restricted Use Potential for effects to animals from acute exposures

Risks may be mitigated through restricted use classification Peak EEC/LC 50 1 0.1

Acute Listed

Species Listed species may be potentially affected by acute

exposures Peak EEC/LC 50 1 0.05

Chronic Potential for effects to non

- listed and listed animals from

chronic exposures 60

- day EEC/NOAEC

(fish)

1

21

- day EEC/NOAEC

(invertebrates)

Aquatic Plants

Non

- Listed Potential for effects to non

- listed plants from exposures Peak EEC/LC 50 1 1

Listed Potential for effects to listed plants from exposures Peak EEC/NOAEC 1

Terrestrial Animals (mammals and birds)

Acute Potential for effects to non

- listed animals from acute

exposures EEC 2 /LC 50 (Dietary)

0.5

EEC/LD 50 (Dose)

Acute

Restricted Use Potential for effects to animals from acute exposures

Risks may be mitigated through restricted use classification EEC 2 /LC 50 (Dietary)

0.2

EEC/LD 50 (Dose)

Acute Listed

Species Listed species may be potentially affected by acute

exposures EEC 2 /LC 50 (Dietary)

0.1

EEC/LD 50 (Dose)

Chronic Potential for effects to non

- listed and listed animals from

chronic exposures EEC 2 /NOAEC 1

Terrestrial and Semi

- Aquatic Plants

Non

- Listed Potential for effects to non

- target, non

- listed plants from

exposures EEC/ EC 25 1

Listed Plant Potential for effects to non

- target, listed plants from

exposures EEC/ NOAEC

1

EEC/ EC 05

1 LC 50 or EC 50

. 2 Based on upper bound seeding rates.- Page 20 of 115

- 

### 3. Analysis

3.1

. Use Characterization

Hydrogen cyanamide, (Dormex, EPA Reg. 

### No. 54555

- 2) is a restricted use plant growth regulator

currently registered (under Section 3 of FIFRA) for use on apples, blueberries, cherries, grapes

(wine and raisin; desert; non

- desert) kiwi fruit (California only), peache s and nectarines. It is

registered under FIFRA section 24 ( c ) on the following crops: blackberries in Georgia

(GA03000600), figs in California (CA04000200) and grapes in Hawaii (HI03000300). Hydrogen

cyanamide is applied as a single airblast or backpack spr ay to the plant buds approximately 30

days before bud break to synchronize blossoming and/or produce a more uniform bud break in

plants that have received less than their full chill hour requireme nt. Aerial application of

Dorm ex is prohibited. Hydrogen cy anamide cannot be applied through any type of irrigation

system, and is not to be used as a bloss om thinner under any conditions. As a result of label

language requiring complete dormancy of deciduous crops to avoid crop damage, this

assessment assumes a s ingle application per year. All use patterns for hydrogen cyanamide are

presented in Table 3.1

.



### Table 3.1. Summary of Agrlicultural Use for H ydrogen C yanamide

Use Site Max imum

App lication

Rate

(lb a.i./A) Maximum

Number of

App lications

* Application

Interval

(days) * Maximum

Yearly

Application

(lb a.i./A) Geographic

Restrictions

Apple 17.6 NS N/A NS No Restrictions

Blackberry 13.2 NS N/A NS No Restrictions

Blueberry 13.2 NS N/A NS Use only in FL

Cherry 17.6 NS N/A NS No Restrictions

Fig 17.6 1 N/A NS

Grapes 17.6 1 N/A NS To use on desert

grown grapes in CA

and AZ

Kiwi Fruit 17.6 1 N/A NS Use only in CA

Nectarine 6.6 NS N/A NS No use in CA

Peach 6.6 NS N/A NS No use in CA

*The assessment assumed a single application where the maximum number of applications was not specified on the

label because of label language requiring complete dormancy of deciduous crops to avoid crop damage.

NS = Not specified on labels

N/A = N ot ava ilable- Page 21 of 115

- 

### 3.2. Exposure Characterization

3.2.1. Environmental Fate and Transport Characterization

The general physical/chemical properties of hydrogen cyanamide are summarized in Table 3.2

. Environmental fate and transport properties of hydrogen cyanamide are characterized in further

detail in the following sections. The Agency’s understanding of these properties is limited by the

available dataset. Additional detail on each study is provided in below.

Table 3.2 General Physical and Chemical Pro perties of hydrogen cyanamide

Property Value Reference



### Chemical Name (IUPAC) Hydrogen cyanamide Foot Print Pesticide Properties

Database. Accessed on September

20, 2012

CAS Registry Number

420

- 04

- 2 Foot Print Pesticide Properties

Database. Accessed on September

20, 2012

Molecular Formula CH

2 

### N

2 

### Foot Print Pesticide Properties

Database. Accessed on September

20, 2012

Mol. Wt (g/mol) 42.04 Lide (2007)

Physical State Colourless solid Foot Print Pesticide Properties

Database. Accessed on September

20, 2012

Melting Point, o 

### C 46.1 Foot Print Pesticide Properties

Database. Accessed on September

20, 2012

Boiling Point, o 

### C 275.4 @ 760 mmHg Foot Print Pesticide Properties

Database. Accessed on September

20, 2012

Vapor Pressure, mmHg @ 2 0

oC 0.00375 EPIWEB 4.1

Solubility in Water @ 20 o 

### C

(mg/L) 780000 Tomlin (2003)

Octanol

- Water Partition

Coefficient (Log K

ow 

### ) (20 o 

### C) - 0.82 Tomlin (2004)

Henry’s Law constant ( atm

m3 / mol) 2.68 X 10

- 10 

### Calculated using solubility and

vapor pressure- Page 22 of 115

- 

### The available environmental fate data for hydrogen cyanamide indicate that it is not persistent in soil

or water. With the exception of except spray drift at the time of application, hydrogen cyanamide is

not expected to partition into air (based on its 

### H enry's Law constant, and and water solubility. This

Henry's Law constant indicates that cyanamide is expected to be essentially nonvolatile from

water surfaces. Cyanamide's Henry's Law constant indicates that volatilization from moist soil

surfaces is not expected to occur. Abiotic degradation processes (hydrolysis and photolysis) are not

important, as metabolism is much quicker. Cyanamide is completely miscible with water, and in

batch equilibrium experiments less than 2% of the mass adsorbed to sandy and silt loam soil. Thus, it

is expected to be very mobile in soil systems.



### A summary of the submitted environmental fate and transport data is summarized below in

Table 3.3

.

Table 3.3 Environmental Fate Data Summary for hydrogen cyanamide

Input Parameter Value Source/comment

Hydrolysis half

- life pH 5: 237 days

pH 7: 66 years

pH 9: 105 days MRID 00150354

Aqueous Photolysis half

- life 29 days in pH 5 and 38.5 d ays

in pH 7 buffers at 25 o C MRID 42178409

Aerobic Soil metabolism half

- life 12 hours in sandy loam soil MRID 42178410

Anaerobic Soil metabolism half

life 35

- day half life in sandy loam

soil MRID 42178412

Aerobic Aquatic metabolism

half

- life 1.2 and 3.2 days in the river

and pond systems MRID# 42382202

Anaerobic aquatic metabolism

half

- life Not available Waived; was not requested because no

useful results would be obtained based

on the rapid aerobic soil degradation

(MRID 42178410) Also, rapid

degradation in the Aerobic aquatic

metabolism study (MRID# 42382202).

Terrestrial Field Dissipation Not available Waived; was not requested because no

useful results would be obtained based

on the rapid aerobic soil degradation

(MRID 42178410) Also, rapid

degradation in the Aerobic aquatic

metabolism study (MRID# 42382202)

. Organic carbon normalized soil

partition coefficient Koc 7.3 EPIWEB 4.1.

In lab studies, only <2% adsorption in

sandy, sandy loam, and silt loam

soilsMRID 42178415, 42178414- Page 23 of 115

- 

### 3.2.1.1. Transport and Mobility

Data from an u 

## naged batch equibrium s tudy showed that n o more than 2 % of the applied

hydrogen cyanamide was adsorbed at all intervals to sandy, sandy loam, and silt loam soils. The

batch equil ibrium study demonstrates a lack of adsorption to soil particles. Adsorption of

hydrogen cyanamide was so limited that Freundlic h

- values would not accurately quantify the

mobility of hydrogen cyanamide.

The unaged soil column leaching study demonstrates the mobility of hydrogen cyanamide in soil.

Hydrogen cyanamide was detected at 0.08

- 2.9% o f the applied amount in the leachate, from

columns of sand, loamy sand, and sandy loam soil that were leached with 20 cm {7.8 7 inches} of

w ater ( MRID 42178415, 42178414 ).

3.2.1.2. Degradation

Hydrogen cyananide is stable to hydrolysis at pH's 5, 7 and 9 (MRID 00150354). Hydrogen

cyanamide degraded with a half

- ife of approximately 12 hours in sandy loam soil that was

incubated in darkness at 23

- 25 O 

### C and 70

- 75% of field moisture capacity. CO 2 

### was the major

degradate, and dicyanodiamide was the only minor degradate, with a half

- 1ife of 4.1 days

(MRID# 42178410). Under aerobic aquatic conditions, hydrogen cyanamide degrades rapidly

with a half

- life of 1.2 and 3.2 days in the river and pond syste ms, respectively (MRID#

42382202). Hydrogen cyanamide degraded under anaerobic soil conditions with half

- life of 35

days (MRID# 42178412); and via photolytic degradation with half

- life 29 days (MRID

42178409).

3.2.1.3. Field Studies

There are no accep table Terrestrial field dissipation (TFD) studies submitted. A compilatlon of

literature articles and submitted laboratory studies d emonstrate that hydrogen cyanamide

degrades rapidly (T 1/2 

### =0.5 d ay) in soils to to dicyanodiamide, urea and ammonia. Hydroge n

cyanamide and its degradates are mobile in soi1. However, the degradation and metabolism of

hydrogencyanamide and its degradates should exceed the potential of leaching under most

environmental conditions.- Page 24 of 115

- 

### 3.2.1.4. Bioconcentration

The Log K

ow 

### of hydrogen cyanamide (

- 0.82 ) is low and indicating the compound has a low

potential to bioaccumulate.

3.2.1.5. Environmental Degradates

Aerobic soil metabolism and aerobic aquatic metabolism are the major mean of degradation of

hydrogen cyanamide. Hydrogen cyanamide rapidly (12 hrs) degrades in aerobic soil to the

degradates CO 2 

### , and dicyanodiamide. Dicyanodiamide degraded with a half

- lif e of 4 days to the

common1y

- applied fertilizer degradates urea and ammonia. Under aerobic aquatic conditions,

hydrogen cyanamide degraded with half

- lives range from 1.2 to 3.2 days.

Hydrogen cyanamide and its degradates are potentially mobile in soil si nce they are completely

soluble in water and were primarily associated with the aqueous phase in both the anaerobic soil

metabolism and batch equilibrium studies in this review. However, the use of hydrogen

cyanamide should not pose a significant, additio nal ground water threat since the parent

compound is not persistent, and the degradates are short

- 1ived, ubiquitous, low molecular weight

organic nitrogen compounds that can be readily incorporated into the metabolism of microbes

and higher plants.

The de gradates of cyanamide (Table 3.4) include simple nitrogen compounds (dicyanodiamide,

guanylurea, guanidine, and urea) which are readily utilized as plant nutrients.



### Table 3.4 Summary of degradates distribution based on laboratory fate studies

Degradate Max. Degradate % of Applied (Time of Peak)

Hydroly

sis Aqueous

Photolysis Aerobic Soil Anaerobic

Soil Aerobic Aquatic

Urea Not

observed 42.4% (pH 5;30 d)

12.2% (pH 7, 30 d) 1.39 (<60 d) 6.7% (2 d)

13.4% (1 d)

CO 2 Not

observed 97.1% (14 d) 48.6 (15 d) 86.1% (28 d)

83.6% (28 d)

Dicyanodiamide Not

observed 5.38% (0.33 d) 5.72 (<60 d) 0.3% (6 d)- Page 25 of 115

- 

### 3.2.2. Measures of Aquatic Exposure

3.2.2.1. Surface Water Exposure

The Tier II model Pesticide Root Zone Model (PRZM v3.12.2; May 12, 2005; Carousel et al.

, undated) linked with EXposure Analysis Modeling System (EXAMS v2.98.4.6; Apr. 25, 2005;

Burns, 2004) via the PRZM/EXAMS model shell (PE v5.0, Nov. 15, 2006), i.e.

, PR ZM/EXAMS) were used to estimate screening

- level exposure concentrations in aquatic

environments. The PRZM model simulates pesticide movement and transformation on and

across the agricultural field resulting from crop applications. The EXAMS model simulat es

pesticide concentrations in water due to loading via runoff, erosion, and spray drift, assuming a

standard 1

- ha pond, 2

- m deep (20,000 m 3 

### ) with no outlet that borders a 10

- ha treated field.

Simulations are for multiple (usually 30) years, from which th e Agency estimates peak values

that are expected to recur on average once every ten years, based on time series of daily

estimated concentrations. The coupled PRZM and EXAMS models and user’s manuals are

available from the U.S. Environmental Protection Ag ency Water Models web

- page (USEPA,

2011b).

Exposure estimates generated using the standard pond are intended as surrogates for potential

concentrations in a wide variety of vulnerable water bodies, including prairie potholes, playa

lakes, vernal pools, ot her wetlands, man

- made and natural ponds, and ephemeral and first

- order

streams. Innumerable site

- specific factors will tend to make such water bodies more or less

vulnerable than the standard pond. Static water bodies that have larger ratios of pesticid e

- treated

drainage area to water body volume are generally expected to have higher peak concentrations

than the standard pond’s EECs. Such water bodies may be smaller in size, and/or have larger

drainage areas. However such water bodies may be more likely to overflow and discharge

pesticide in their effluent, whereas the standard pond has no discharge. As watershed size

increases, it becomes increasingly unlikely that the entire watershed is planted with a single crop

that is all treated simultaneously wi th a pesticide. Headwater streams may have peak

concentrations that are higher than those predicted for the standard pond, but such concentrations

will likely persist for only short periods of time or distance, as they are carried downstream and

diluted w ith water originating elsewhere.

The general chemical and environmental fate data for hydrogen cyanamide listed in Table 3.2

-

3.3 were used for generating model input parameters for PRZM and EXAMS (listed in Table

3.5 ). C hemical specific and model input v alues were chosen in accordance with current

divisional guidance (USEPA, 2009).

Table 3.5. PRZM and EXAMS Surface Water Chemical Input Parameters for

Hydrogen cyanamide

. PARAMETER (units) VALUE (S) SOURCE COMMENT

Mol. Wt (g/mol) 42.04 Lide, D.R. 2007

Solubility (mg/L) 7.8E+5 EPIWEB 4.1 Tomlin (2003) as cited in EPISuite

Henry’s Law Constant

(atm

- m 3 /mol) 2.68 X 10

- 10 EPIWEB 4.1 Value calculated from literature

values for vapor pressure and

solubility cited in EPISuite

Vap. Pressure (Torr) 0.00375 EPIWEB 4.1 Tomlin (2003) as cited in EPiSuite- Page 26 of 115

- Application Rate (lb a.i.

/A) See Table 3.6

Number of Applications 1 EPA Reg. No. 54555

- 2

Interval between

Applications (days) N/A EPA Reg. No. 54555

- 2

spray drift fraction 0.001 AgDrift modeling using a

required 900 ft buffer zone EPA Reg. No. 54555

- 2

Soil Partition Coefficient

K OC , (mL/g) 7.3 EPIWEB 4.1 Data in MRID 42178415 could not

be used to determine coefficient.

Aerobic Soil Metabolism

Half

- life

(days) 1.5 MRID 42178410 Single half

- life is available;

multiplied by 3; Guidance for

Selecting Input Parameters in

Modeling the Environmental Fate

and

Transport of Pesticides

Version 2.1 (2009)

Wetted in? No EPA Reg. No. 54555

- 2

Depth of Incorporation

(inches ) 0 EPA Reg. No. 54555

- 2

Method of Application Ground

Airblast EPA Reg. No. 54555

- 2

Hydrolysis Half

- life @ pH

7 (days) stable Literature Review EFED Review of Data, 1993.

Aerobic Aquatic

Metabolism

Half

- life (days) 5.28 MRID# 45382202 Represents the 90th percentile of the

upper confidence bound on the mean

of 2 half

- life values: 1.2, and 3.2;

mean 2.2, std. dev, 1.41 . Guidance

for Selecting Input Parameters in

Modeling the Environmental Fate

and

Transport of Pesticides

Version 2.1 (2009)

Anaerobic Aquatic

Metabolism

Half

- life (days) 210 MRID#42178412 Anaerobic soil met. half

- life (35

days) multiplied by 3 for a single

half

- life available (105 days) x2;

Guidance for Selecting Input

Parameters in

Modeling the Environmental Fate

and Transport of Pesticides

Aquatic Photolysis Half

life @ pH 7 (days) 38 MRID# 42178409 Guidance for Selecting Input

Parameters in Modeling the

Environmental Fate and

Transport of Pesticides

Version 2.1 (2009) *: D1=D2*√MW2/MW1; D1: unknown air diffusion, D2: known air diffusion =14688 (for Methanol; Thoma et al., 1992 ); MW2 for known =

32.04 (Methanol).



### The initial application date was selected in order to simulate 30 or more days before normal

budbreak. Appl ication d ates for modeling purposes were selected in accordance with the

proposed labels to generate the most conservative estimates of aquatic exposure and based on

information from the Cooperative Extension offices or the references provided in Table 3.6

.- Page 27 of 115

- 

### Table 3.6

. Modeling Scenarios used for hydrogen cycnamide applied to various crops.

Crop

Maximum

Application rate

(lb ai/acre) PRZM Scenario Application

timing Data source/

C omments

Apple

17.6 ORapples February 4 Univ. of Oregon extension office

PAapples February 20 www.boyernurseries.com

NCapples February 4 North Carolina S. Univ. extension office

Blackberry,

Blueberry

13.2 GAPeaches December 1 2007 CENSUS OF AGRICULTURE, USDA,

National Agricultural Statistics Service; Personal

communicati o n with Dr. G. Williamson @ U. FL.

Cherry

17.6 MIcherries March 24 Northwest Michigan Horticultural Research Center @

http://www.leelanaunews.com/news/OldArchive/Spec

ial_Interests/Cherry_blossom_blooms_ earliest_in_yea

rs.html.

Grapes

17.6 NYgrapes March 25 cornell.edu@

http://flg.cce.cornell.edu/2012/03/15/early

- budbreak

in

- 2012/

CAgrapes February 9 UCDAVIS.edu@ http://www.ipm.ucdavis.edu/PMG/C

302/mt302yi01.html#BREAK

Nectarine

Peaches

6.6 GApeaches February 14 Univ. of Georgia (personal contact @ 478

- 987

- 2028).

Kiwi fruit

Fig

17.6 CAfruits March 1st The California Minor Crops Council. 2003



### Based on its use pattern, one application of hydrogen cyanamide is used in this assessment.

The label ( EPA Registration Number 54555

- 2 

### ) did not specify the number of applications

allowable per season. The label should reflect this for future actions.

The modeled aquatic EECs resulting from the proposed hydrogen cyanamide uses (listed in

Table 3.7 ) were used for risk estimation in this screening

- level assessment. The model input and

output filenames supporting these values are listed in Appendix C

.- Page 28 of 115

- 

### Table 3.7. Modeled Aquatic Surface Water 1

- in

- 10

- year EECs for Registered Uses of hydrogen

cyanamide on various crops.

Crop PRZM Scenario 1

- in

- 10 year

peak daily,

ppb 1

- in

- 10 year,

peak 21

- day

average, ppb 1

- in

- 10 year,

peak 60

- day

average, ppb

Apples ORapplesSTD.txt 31.8 23.1 13.0

PAapplesSTD.txt 15.5 12.0 7.41

NCapplesSTD.txt 11.0 8.09 4.83

Blackberry/Blueberry GApeachesSTD.txt 9.35 6.42 3.00

Cherry MIcherriesSTD.txt 92.0 69.0 37.5

Grapes CAgrapes_WirrigSTD.txt 83.6 56.4 30.0

NYgrapesSTD.txt 21.2 14.6 7.85

Kiwifruit/Fig CAfruit_WirrigSTD.txt 77.5 44.7 21.6

Peaches/Nectarines GApeachesSTD.txt 28.6 18.8 9.55



### 3.2. 3

. Measures of Terrestrial Exposure

3.2.3.1

. Terrestrial Wildlife

Exposure estimates for terrestrial organisms assumed to be in the target area or in an area

exposed to off

- site deposition are derived using the T

- REX model (version 1.4.1, 10/09/2008).

This model incorporates the Kenaga nomograph, as modified by Fletcher et al. (1994), which is

based on a large set of field residue data. The upper limit values from the nomograph represent

the upper bound of residue values from actual field measurements (Hoerger and Kenaga 1972).

The Fletcher et al. (1994) modifications to the Kenaga nomograph are based on measured field

residues from 249 published research papers, including information on 118 species of plants, 121

pesticides, and 17 chemical classes. Based on these data, T

- REX assumes a 35

- day foliar

dissipation half

- l ife in the absence of other data. However, in an available residue study where

hydrogen cyanamide was applied to table grapes at a rate of up to 8 lbs a.i./A, residues 1 hour

after application were < 3.49 ppm and drop ped below the limits of detection (0.05 ppm) after 14

days (MRID # 40329902). Though there were uncertainties identified with the analytical

methods used to extract and identify residues, these data do suggest that the foliar dissipation

half

- life for hydrogen cyanamide is less than the 35 day s assumed by T

- REX. This will be

discussed further in the risk characterization section.

In order to determine if more data are necessary, the S creening T ool for I nhalation R isk (STIR

v.1.0) was used to calculate an upper bound estimate of exposure using hydrogen cyanamide ’s

vapor pressure ( 3.75 x10

- 3 

### ) and molecular weight ( 42.04 ) for vapor phase exposure as well as the- Page 29 of 115

- 

### maximum application rate and method of application for spray drift. STIR incorporates results

from several toxicity studies including ac ute oral (> 2.0 mg ai/kg

- bw , MRID# 47469103 ) and

inhalation ( 300 mg ai/L) rat toxicity endpoints obtained from the “six

- pack” of core studies,

which are a series of six guideline studies that are submitted to the Registration Division of the

Office of Pesticide Programs for technical and formulated products of a pesticide as well as the

most sensitive acute oral avian ( 173 mg ai/kg

- bw) toxicity endpoint. Based on the results of the

STIR model, inhalation exposure alone was not determined to be a potent ial pathway of concern

for mammalian species on an acute exposure basis ; however, acute inhalation exposure may be a

potential pathway of concern for avian species. Please see Appendix D for sample output

generated by STIR v.1.0. Detailed information about STIR v.1.0, as well as the tool, can be

found on the EPA’s website at: http://www.epa.gov/pesticides/science/models_pg.htm#terrestrial

.

The S creening I mbibition P rogram (SI P v.1.0) was used to calculate an upper bound estimate of

exposure using an estimate of hydrogen cyanamide ’s solubility ( 7.8x10 5 

### pp m ), as well as the

most sensitive acute and chronic avian and mammalian toxicity endpoints. As a result of

hydrogen cyanamid e’s high solubility, d rinking water exposure was determined to be a potential

pathway of concern for both avian (and surrogates) and mammalian species on an acute and

chronic exposure basis. More information on residues of hydrogen cyanamide on the field, in

run

- off, and puddle water would help to alleviate uncertainties associated with this concern.

Without this information risks to mammals and birds from drinking water will remain an

unquantifiable concern. . For a sample of the output generated by SIP v.1.0, please see Appendix

D

. Detailed information about the SIP v.1.0, as well as the tool, can be found on the EPA’s

website at http://www.epa.gov/pesticides/science/models_pg.htm#terrestrial

.

EECs for terrestrial plants are derived using TerrPlant (v.1.2.2). This model uses estimates of

pesticides in runoff and in spray drift to calculate EECs. EECs are based upon solubility

, application rate and minimum incorporation depth.

3. 2

. 3.2. Terrestrial Plants

Exposure of naturally

- occurring terrestrial and semi

- aquatic (wetland) plant species is typically

estimated using OPP’s TerrPlant (v1.2.2 ; US EPA, 2006b ) model and is assumed to encompass

areas outside the immediate use site. The TerrPlant model is used to derive EECs in runoff and

drift for terrestrial and semi

- aquatic plants near areas where hydrogen cyanamide has been

applied. Runoff exposure is assessed in two sce narios: sheet and channel runoff. In the sheet

runoff scenario, the treated area generating runoff is assumed to drain into an area with equal

size containing seedlings, resulting in 1, 2, or 5% of the a mount applied being deposited. In the

channel runof f scenario, a ten

- to

- one ratio of treatment area to receiving area results in 10, 20, or

50% of the amount applied being deposited on soil with emerging or emerged seedlings. Spray

drift is also a source of pesticide loading to non

- target areas. TerrPla nt estimates EECs based on

app lication rate, application method, chemical solubility in water

, type of runoff and default

assumptions of drift. Detailed information about TerrPlant, as well as the tool, can be found on

the EPA’s website at http://www.epa.gov/pesticides/science/models_pg.htm#terrestrial

.- Page 30 of 115

- 

### The AgDRIFT (v 2.01; May 2001) spray drift model is used to assess exposures of terrestrial

plants to hydrogen cyanamide deposited on terrestrial or aquatic habitats by spray drift at a given

distance from the application area.

3.3

. Ecological Effects Characterization

In screening

- level ecological risk assessments, effects characterization describes the types of

effects a pesticide can have on aquatic and terrestrial organisms. To date, toxicity tests for

amphibian s or reptiles are not required; birds are used as surrogates for reptiles and terrestrial

phase amphibians and freshwater fish are used as surrogates for aqua tic

- phase amphibians. This

characterization is based on the registrant

- submitted toxicity data for birds, mammals, fish,

invertebrates, and plants for hydrogen cyanamide

.

This assessment evaluates the potential for hydrogen cyanamide to directly or indi rectly affect

listed species or modify designated critical habitat. As previously discussed in Section 2.7,

assessment endpoints include direct toxic effects on the survival, reproduction, and growth of

listed entities, as well as indirect effects, such a s reduction of the prey base or modification of

habitat. In addition, potential modification of critical habitat is assessed by evaluating effects to

the PCEs, which are components of the critical habitat areas that provide essential life cycle

needs of l isted entities.

As described in the Agency’s Overview Document (USEPA 2004), the most sensitive endpoint

for each taxon is used for risk estimation. For this assessment, evaluated taxa include aquatic

phase amphibians, freshwater fish, freshwater inver tebrates, aquatic plants, birds (surrogate for

terrestrial

- phase amphibians), mammals, terrestrial invertebrates, and terrestrial plants.

Toxicity endpoints are established based on data generated from guideline studies submitted by

the registrant, and from open literature studies that meet the criteria for inclusion into the

ECOTOX database maintained by EPA/Office of Research and Development (ORD) (U.S. EPA,

2004). Open literature data presented in this assessment were obtained from ECOTOX

information obtained in December 2007. In order to be included in the ECOTOX database,

papers must meet the following minimum criteria:

(1) the toxic effects are related to single chemical exposure;

(2) the toxic effects are on an aquatic or terrestrial plant or animal spe cies;

(3) there is a biological effect on live, whole organisms;

(4) a concurrent environmental chemical concentration/dose or application rate is

reported; and

(5) there is an explicit duration of exposure.

Data that pass the ECOTOX screen are evaluated along with t he registrant

- submitted data, and

may be incorporated qualitatively or quantitatively into this endangered species assessment. In

general, effects data in the open literature that are more conservative than the registrant

submitted data are considered. T he degree to which open literature data are quantitatively or

qualitatively characterized is dependent on whether the information is relevant to the assessment- Page 31 of 115

- 

### endpoints ( i.e. , maintenance of survival, reproduction, and growth) identified in Section 2.8. For

example, endpoints such as behavior modifications are likely to be qualitatively evaluated,

because quantitative relationships between modifications and reduction in species survival,

reproduction, and/or growth are not available.

In addition to registrant

- submitted and open literature toxicity information, other sources of

information, including use of the acute probit dose

- response relationship to establish the

probability of an individual effect and reviews of the Ecological Inci dent Information System

(EIIS), are conducted to further refine the characterization of potential ecological effects

associated with exposure to hydrogen cyanamide . A summary of the available aquatic and

terrestrial ecotoxicity information, use of the pro bit dose

- response relationship, and the incident

information for hydrogen cyanamide are provided in Sections 4.1 through 4.4, respectively.

Data identified in ECOTOX were not used in this assessment because they did not represent the

most senstitive endpo ints. No data are available on the toxicity of the major degradates of

hydrogen cyanamide

.

No toxicity data were available on hydrogen cyanamide mixtures with other pesticides; no multi

a

. i

. products are registered for hydrogen cyanamide

.

3.3.1. Aquatic Toxicity Assessment

The most sensitive acute and chronic effects measurement endpoints associated with hydrogen

cyanamide exposure to freshwater and estuarine/marine species are summarized in Table 3. 8

. All acceptable and supplemental studies available f or hydrogen cyanamide are described below

.- Page 32 of 115

- 

### Table 3. 8 . Most Sensitive Acute and Chronic Toxicity Data for Aquatic Organisms

Exposed to Hydrogen cyanamide Technical

Exposure

Scenario Species Affected

Endpoint Toxicity Measurement Toxicity

Classification MRID

(Classification)

Freshwater Fish

Acute Rainbow trout

( Oncorhynchus

mykiss ) Mortality 96

- hr LC 50 = 46 mg a.i./L

Slope: 8.65 Slighty toxic MRID 00148043

(Acceptable)

Chronic Rainbow trout

( Oncorhynchus

mykiss ) Adult

growth NOAEC < 0.507 mg a.i./L

-- MRID 44076701

(Supplemental)



### Freshwater Invertebrates

Acute Water flea

( Daphnia spp.) Immobility 48

- hr EC 50 = 3.3 mg a.i./L

Slope: 7.70 Moderately

toxic MRID 00148046

(Acceptable)

Chronic Water flea

( Daphnia spp.) Adult 21

- day length NOAEC = 100 μg a.i./L

-- MRID 44076702

(Acceptable)



### Estuarine/Marine Fish

Acute Sheepshead

minnow

( Cyprinodon

variegatus ) Mortality 96

- hr LC 50 = 58 mg a.i./L

Slope: 15 Slightly toxic MRID 44804702

(Acceptable)

Chronic No data available



### Estuarine/Marine Invertebrates

Acute Eastern oyster

( Crassostrea

virginica ) Shell

deposition 96

- hr EC 50 = 2.3 mg a.i./L

Slope: NA M oderately

toxic MRID 44804704

(Acceptable)

Chronic No data available.



### Aquatic Plants

7

- day

exposure Duckweed

( Lemna gibba ) Frond

count EC 50 = 3.0 mg a.i./L

NOAEC = 0.31 mg a.i./L -- MRID 45406602

(Acceptable)

72

- hour

exposure Anabaena flos

aquae None EC 50 = 0.37 mg a.i./L

NOAEC = 0.09 mg a.i./L -- MRID 45382201

(Supplemental)



### 3.3.1.1 Toxicity to Freshwater Fish

Acute Effects

In the acute toxicity study with a warmwater species, bluegill sunfish were exposed to 49%

aqueous hydrogen cyanamide for 96 hours. The resulting 96

- hour LC 50 

### was determined to be 88

ppm a.i. (EPA Acc. No. 073728, MRID 00153786; acceptable). For the coldwa ter species,

rainbow trout (coldwater freshwater fish) were exposed to 49% aqueous hydrogen cyanamide for

96 hours. The resulting 96

- hour LC 50 

### was 46 ppm a.i. (EPA Acc. No. 073728, MRID 00148043;

acceptable). Toxicological signs observed included: quiesce nce, ceased swimming, dark

discoloration, hyperexcitability at the lower concentrations, and erratic swimming. These results

classify cyanamide as slightly toxic to fish.

Chronic Effects- Page 33 of 115

- 

### In the chronic toxicity study, rainbow trout were exposed to 50% a queous hydrogen cyanamide

(MRID 44076701; supplemental). The reported NOAEC for reproduction endpoints ( i.e., days to

hatch, days to swimup, and hatch survival) was 2.03 ppm and the associated LOAEC was 4.03

ppm. However, effects on growth endpoints ( i.e. , length and wet weight) were observed at all

treatment levels; therefore, the NOAEC for this study was <0.507 and the LOAEC was 0.507.

While effects were observed at all treatment levels, the minimum difference from the control for

the endpoints of intere st ( i.e, length and weight) to be significant is based on a relatively small

percent difference (2.7% and 7.4% for length and weight, respectively). For example, in the

lowest treatment concentration, mean length was 3% different from the control and mean wet

weight was 8.7% different from the control. It is uncertain whether these values represent

biologically relevant differences. In addition, further examination of the available raw data

suggests that the differences observed in the growth endpoints were based on the poor

performance of 3 fish (1 fish for length and 2 fish for weight) out of 59 total fish within the

treatment level. Measurements for these few fish were sufficiently reduced such that they

reduced the overall mean for the entire treatment l evel. If those fish had preformed as well as the

remaining fish in the treatment level, there would no longer be significant differences from the

controls. For example, removing the one poorly performing fish for length (25 mm vs 45.4 mm

for the treatment group) would increase the treatment level mean from 45.4 to 45.7, resulting in a

2.4% difference from the control. Since a definitive NOAEC was not determined for the most

sensitive endpoints, this study is classified as supplemental.

3.3.1.2. Toxicity to Freshwater Invertebrates

Acute Effects

The 48

- hour acute toxicity of hydrogen cyanamide TEP (Dormex, 49% a.i.) to the freshwater

invertebrate Daphnia magna is 3.3 ppm a.i., which classifies it as highly toxic (EPA Acc. No.

073728; acceptable). Subleth al effects were not reported in the study.

Chronic Effects

In the chronic toxicity study, Daphnia magna were exposed to 50% aqueous hydrogen

cyanamide (MRID 44076702; acceptable). Data indicate that hydrogen cyanamide is highly

toxic to daphnid growth and reproduction of young. The most sensitive endpoint was adult

length after 21 days exposure (LOEC=210 ppb a.i. and NOEC = 100 ppb a.i.). Numbers of

young produced per female per reproduction day were also affected at a concentration of 410

ppb a .i.

3.3.1.3. Toxicit y to Estuarine/Marine Fish

Acute Effects- Page 34 of 115

- 

### In the acute toxicity study, sheepshead minnow were exposed to 50.8% aqueous hydrogen

cyanamide for 96 hours. The resulting 96

- hour LC 50 

### was determined to be 58 ppm a.i. which

classifies hydrogen cyanamide as slightly toxic (MRID 44804702; acceptable). Signs of toxicity

observed in the two highest concentrations included surfacing, lethargy, loss of equilibrium, and

quiescence.

Chronic E ffects

No chronic toxicity tests in estuarine/marine fish with the TGAI, formulations, or degradates

were submitted.

3.3.1.4. Toxicity to Estuarine/Marine Invertebrates

Acute Effects

In a shell deposition test, Eastern oyster s ( Crassostrea virginica ) were exposed to 50.8%

aqueous hydrogen cyanamide for 96 hours (MRID 44804704, acceptable). The resulting data

indicated a 96

- hour EC 50 

### of 2.3 ppm a.i., classifying hydrogen cyanamide as moderately toxic to

the Eastern oyster.

In an additional acute toxic ity study, mysid shrimp ( Mysidopsis bahia ) were exposed to 50.8%

aqueous hydrogen cyanamide for 96 hours. The resulting 96

- hour LC 50 

### for mysids was 6.3 ppm

a.i., which classifies this compound as moderately toxic to Mysidopsis bahia (MRID 44804703;

accepta ble). Toxicological signs oberseved at the two highest concentrations included erratic

swimming and lethargy.

Chronic Effects

No chronic toxicity tests in estuarine/marine invertebrates with the TGAI, formulations, or

degradates were submitted

3.3.1.5. Toxicity to Aquatic Plants

In a registrant submitted non

- vascular plant study using Anabaena flos

- aquae the 72

- hour EC 50 

### and NOAEC values for cell density were 0.37 ppm a.i. and 0.09 ppm a.i., respectively (MRID

45382201, supplemental). In an additional study using Pseudokirchneriella subcapitata the 72

-

hour EC 50 

### and NOAEC values for cell density were and 12 ppm a.i. and 4.26 ppm a.i.,

respectively (MRID 45406601, supplemental). These studies were classified as supplemental

because the exposure window was 72 hours, while the typical guideline study exposes non

vascular plants for 96 hours.

In a regis trant submitted vascular aquatic plant study with Lemna gibba the 7

- day EC50 and

NOAEC values for frond count were 3.0 ppm a.i. and 0.31 ppm a.i., respectively (MRID

45406602, acceptable).- Page 35 of 115

- 

### 3.3.2 Terrestrial Effects Characterization

The most sensitive acute and chronic toxicity reference values associated with hydrogen

cyanamide exposure to mammals, birds, and terrestrial invertebrates are summarized in Table

3. 9 . The most sensitive measurement endpoints for terrestrial plants are presented in Table 3. 1 0

.

Table 3. 9 . Hydrogen cyanamide Technical Grade Toxicity Measurement Endpoints for

Terrestrial Animals.

Exposure

Scenario Species Exposure

Duration Toxicity

Reference Value Toxicity

Classificaiton MRID

(Classification)

Mammals

Acute

(Dose

- based) Laboratory

rat ( Rattus

norvegicus ) Single oral

dose LD50 = 300 mg

a.i./kg bw Moderately

toxic Acc. No. 073726

Acceptable

Chronic

(Dietary

- based) Laboratory

rat Two

generation NOAEL = 1.25 mg

a.i./kg/day

Endpoints based on

decreased maternal

weight gain,

decreased food

consumption -- MRID 41566504

Acceptable



### Birds

Acute

(Dose

- based) Bobwhite

quail

Colinus

virginianus 14

- day single

oral dose LD 50 = 173 mg

a.i./kg bw

Slope: NA Moderately

toxic MRID 00153783

(Acceptable)

Acute

(Dietary

- based) Bobwhite

quail

Colinus

virginianus 8

- day dietary LC 50 : >5000 mg

ai/kg diet

NOAEC: 625 mg

ai/kg diet

(based on behavior

effects) Practically non

toxic MRID 42178402

(Acceptable)

Mallard duck

Anas

platyrhynchos 8

- day dietary LC 50 : >5000 mg

ai/kg diet

NOAEC: 312.5 mg

ai/kg diet (based on

behavior effects) Practically

non

- toxic MRID 42178401

(Acceptable)

Chronic

(Dietary

- based) Mallard duck

Anas

platyrhynchos No data available.- Page 36 of 115

- 

### Table 3. 9 . Hydrogen cyanamide Technical Grade Toxicity Measurement Endpoints for

Terrestrial Animals.

Exposure

Scenario Species Exposure

Duration Toxicity

Reference Value Toxicity

Classificaiton MRID

(Classification)

Bobwhite

quail

Colinus

virginianus ca. 21 week

avian

reproduction

study LOAEC: 526 mg

ai/kg diet

NOAEC: 153 mg

ai/kg diet

(Based on 14

- day

survivor weight and

mean food

consumption) -- MRID 45797201

( Supplemental )



### Terrestrial Invertebrates

Acute

(Contact) Honeybee 48

- hour LD 50 > 36.2 μg

a.i./bee

NOAEL = 12 μg

ai/bee Practically non

toxic MRID 43866902

(Acceptable)



### Table 3. 10

. Hydrogen C yanamide Toxicity Measurement Endpoints for Terrestrial Plants.

Exposure

Scenario Formulation Species Exposure

Duration Toxicity Reference

Value Reference

(Classification)

Seedling

Emergence Cyanamide L

500 Onion

( Allium cepa ) 21

- day test

- single

application EC 25 = 0.44 lbs a.i./A

NOAEC 1 = 0.041 lbs a.i./A MRID 48404301

( Supplemental )

Lettuce

( Lactuca

sativa ) EC 25 = not calculable

NOAEC < 0.056 lbs a.i./A

Vegetative

Vigor Cyanamide L

500 Corn

( Zea mays ) 21

- day test

- single

application EC 25 = 7.9 lbs a.i./A

NOAEC = 7.2 lbs a.i./A MRID 48404302

(Supplemental)

Tomato

( Lycopersicon

esculentum ) EC 25 = 0.89 lbs a.i./A

NOAEC = 0.096 lbs a.i./A

1 The EC 05 is used in lieu of the NOAEC.



### 3.3.2.1. Toxicity to Mammals

Acute Effects

The acute oral LD50 for the laboratory rat is 300 mg a.i./kg (EPA Acc. No. 073726), which

classifies hydrogen cyanamide as moderately toxic. An acute dietary study is not available for

hydrogen cyanamide. This represents a data gap.

Chronic Effects

A two

- generation reproduction study established a NOAEL of 25 ppm a.i. or 1.25 mg a.i./kg/day.

The endpoints affected were decreased maternal bo dy weight gain and decreased food

consumption.- Page 37 of 115

- 

### 3.3.2.2. Toxicity to Birds

Acute and Subacute Dietary

Acute

In the available acute oral toxicity study the oral LD50 for the bobwhite quail was 173 mg a.i./ kg

(EPA Acc. No. 073728), classifying hydrogen cyanamide as moderately toxic to birds on an

acute basis. At the 250 mg/kg dosage one male mortality was observed on day one. Seven

mortalities occurred on day one at the 500 mg/kg level followed by two more m ortalities by the

48

- hour point. Only one bird survived at this test level. Total mortality occurred within 4 hours at

the 1000 and 2000 mg/kg dosage level. All mortalities were preceded by hypoactivity and

prostration. All birds surviving after this 48

- ho ur period returned to normal behavior.

No data is available for a passerine species.

Subacute

The 8

- day dietary LC50 for both mallard duck and bobwhite quail was determined to be greater

than 5000 ppm (MRID 42178401,42178402), which categorizes cyanamide as practically non

toxic on a sub

- acute dietary basis. However, behavioral modification, includ ing decreased food

consumption and signs of stress, occurred in both studies and treatment

- related effects on adult

body weights were reported for the mallard duck.

For the mallard duck (MRID 42178401), there were no mortalities in the control groups or in the

treatment groups (312.5, 625, 1250, 2500 , 5000 ppm a.i. ). During exposure and up to day 6 (1

day after exposure) abnormal behavioral signs were noted in test concentrations ≥ 625ppm a.i.

(nominal). These included lethargy, ruffled appearance and re duced reactions to sound and

movement stimuli. There were significant effects on body weight gain or loss at all concentration

levels. A corresponding reduction in feed consumption was also observed, thus indicating an

aversion to consumption of the hydrog en cyanamide dosed food. The NOAEC based on

behavioral modifications is < 312.5 ppm a.i.

For the bobwhite quail (MRID 42178402), there were no mortalities in the control groups or test

concentration groups (312.5, 625, 1250, 2500, and 5000 ppm). During e xposure and up to day 6

(1 day after exposure) abnormal behavioral signs were noted in test concentrations ≥ 1250, ppm

a.i. (nominal). These included lethargy, ruffled appearance and reduced reactions to sound and

movement stimuli. By day 7 all birds appea red to return to normal appearance and behavior. No

effects on body weight or food consumption were noted at any concentration level. The NOAEC

based on behavioral modifications is 625 ppm a.i. with a LOAEC of 1250 ppm a.i.

Chronic

A supplemental one

- ge neration avian reproduction study is available for the formulation

Cyanamide L 500, which is an aqueous formulation containing 50.6% active ingredient, for the- Page 38 of 115

- 

### bobwhite quail (MRID 45797201).

The body weights of surviving 14

- day old chicks were statis tically

- reduced compared to the

control group at 1040 ppm formulation (526 ppm a.i.). Therefore the LOAEC is 526 ppm a.i.

and the NOAEC is 153 ppm a.i. This study was classified as supplemental because of its use of a

formulation rather than the technical grade active ingredient.

3.3.2.3. Toxicity to Terrestrial Invertebrates

Acute Effects

Honey bee

In the acute contact toxicity study (MRID 438669

- 02), honey bees were exposed to Dormex 4.0

SL (50% hydrogen cyanamide) formulated as 10% dust. Data showed that cyanamide is

essentially non

- toxic to the honey bee (LD 50 

### >36.2 mg a.i./bee, and NOAEL approximately 12

mg a.i./bee).

3.3.2.4. Toxicity to Terrestrial Plants

Terrestrial plant toxicity data are available for the formulation Cyanamide L 500 (50.6%

cyanamide)

. In the tier II seedling emergence study (MRID 4840430 1, supplemental ) inhibitions

in emergence/survival for the most sensitive species, onion and lettuce, were 95% and 80%,

respectively. Additionally, onion experienced a 76% inhibition in plant length while lettuce

experienced a 46% inhibition in dry weight. Therefore, t h e most sensitive monocot species was

onion based on emergence and survival, with EC 05 

### and EC 25 

### values of 0.041 and 0.44 lb ai/A,

respectively. D e finitive EC 25 

### and NOAEC values were not determined for the most sensitive

dicot endpoint (lettuce emergence) as a result of high variability within treatment levels, wide

confidence intervals , and fluctuations in inhibitions as the dose increased

. Poor control

emergence (77%) may have also been a factor. The next most sensitive dicot species was carrot

based on dry weight, with NOAEC and EC 25 

### values of 0.22 and 0.60 lb a.i./A. This indicates that

h ydrogen cyanamide may affect seedling emergence at rates up to two orders of magnitude

below the currently registered application rates.

However, evidence of a low

- dose response may be indicative of the heightened species

sensitivity for lettuce, therefo re, the LOAEC value for this species is the lowest concentration

tested, 0.056 lb a.i./A. For the purposes of this risk assessment, the LOAEC value for lettuce of

0.056 lb a.i/A will be used to characterize the lower bounds of risk from exposure to terres trial

plants to hydrogen cyanamide. Submission of a seedling emergence study that provides

definitive EC 25 

### and NOAEC values for all ten species would greatly reduce the uncertainty

associated with these values.

In the vegetative vigor study (MRID 48404302 , supplemental) t he most sensitive monocot

species was corn based on dry weight, with NOAEC and EC 25 

### values of 7.2 and 7.9 lb ai/A,- Page 39 of 115

- 

### respectively. The most sensitive dicot species was tomato based on dry weight, with NOAEC

and EC 25 

### values of 0.096 and 0.89 lb ai/A, respectively. However, the EC 25 

### value for tomato

should be interpreted with caution, as it is not bracketed by the test concentrations

.

4. Risk Characterization

4.1. Risk Estimation

Toxicity data and exposure estimates are used to evaluate the potential for adverse ecological

effects on non

- target species. This screening

- level assessment for hydrogen cyanamide relies on

the deterministic RQ method to provide a metric of potential ris ks. The RQ provides a

comparison of exposure estimates to toxicity endpoints ( i.e. , the estimated exposure

concentrations are divided by acute and chronic toxicity values). The resulting unitless RQs are

compared to the Agency’s LOCs, as shown in Table 2 .3 . LOCs are used by the Agency to

indicate when the use of a pesticide, as directed by the label, has the potential to cause adverse

effects to non

- target organisms.

4.1.1. Aquatic Organisms

The highest screening

- level aquatic EECs based on the maximum application rates for each

proposed use pattern were used to derive RQs. These exposure estimates represent

concentrations in surface water ( Table 3.7 ). Peak EECs are used to represent acute exposure to

fish, aquatic invertebrates, and aquatic pl ants, and the highest 21

- day and 60

- day average EECs

represent chronic exposure to aquatic invertebrates and fish, respectively.

4.1.1.1. Fish and Invertebrates

Fish

Results of acute toxicity studies in freshwater and estuarine/marine fish ( Table 3. 9 ) indicate that

hydrogen cyanamide is “ slightly toxic” to freshwater and estuarine/marine fish on an acute

exposure basis. For both freshwater and estuarine/marine fish

, all acute RQs for the uses of

hydrogen cyanamide fall well below the Agency’s acute risk to listed species LOC (0.05), as

well as the Agency’s acute risk to non

- listed species LOC of 0.5. RQs range from <0.01 to 0.01

for freshwater and estuarine/marine invertebrates.

RQs for chronic exposures to freshwater fis h could not be calculated because a definitive

NOAEC was not available. There are no chronic toxicity data available for estuarine/marine fish.

Aquatic Invertebrates

Based on all available acute studies, hydrogen cyanamide is categorized as “ moderately toxic ” to

aquatic invertebrates on an acute exposure basis

. However, RQs for the uses of hydrogen- Page 40 of 115

- 

### cyanamide fall below the Agency’s acute risk to listed species and non

- listed speices LOCs (0.05

and 0.5, respectively). RQs range from <0.01 to 0.03 for fres hwater invertebrates and from <0.01

to 0.04 for estuarine/marine invertebrates.

RQs for chronic exposure to freshwater invertebrates fell below the Agency’s chronic risk to

listed and non

- listed species LOC (1.0). RQs for freshwater invertebrates range fr om 0.06 to

0.69. Chronic toxicity data for estuarine/marine invertebrates is not available so RQs could not

be calculated. This will be discussed further in risk characterization.

4.1.1.2. Aquatic Plants

Table 4. 1 lists acute RQs for aquatic vascular and non

- vascular plants exposed to hydrogen

cyanamide. Although hydrogen cyanamide does exhibit effects on both Lemna gibba and

Anabaena flos

- aquae , these effects are at much higher concentrations than those estimated for

the majority of the hydrogen cyanamide uses. However, the acute listed species LOC (1.0) is

equal to the LOC for non

- vascular plants exposed to hydrogen cynamide from use on cherries.

Table 4

. 1

. Acute RQs for Aquatic Vascular and Non

- vascular Plants Exposed to Hydrogen

Cyanamide

.

Use

(App. Method) Application

Rate

lbs a.i./A

(#app) PRZM Scenario Peak

EECs

(ppb) Vascular Aquatic

Plant RQs

EC 50 = 3000 ppb

NOAEC = 370 ppb Non

- vascular Plant RQs

EC 50 = 310 ppb

NOAEC = 90 ppb

Acute

Non

listed

Species Acute

Listed

Species Non

- listed

Species Listed

Species

Apples

(airblast) 17.6 (1) ORapples 31.8 0.01 0.09 0.10 0.35

PAapples 15.5 0.01 0.04 0.05 0.17

NCapples 11.0 <0.01 0.03 0.04 0.12

Blackberry,

Blueberry 13.2 (1) GApeaches 9.35 <0.01 0.03 0.03 0.10

Cherry 17.6 (1) MIcherries 92.0 0.03 0.24 0.30 1.0 *

Grapes 17.6 (1) CAgrapes_Wirri

g 83.6 0.03 0.23 0.30 0.92- Page 41 of 115

- NYgrapes 21.2 0.01 0.06 0.07 0.24

Kiwifruit,

Fig 17.6 (1) CAfruit_Wirrig 77.5 0.03 0.212 0.25 0.86

Peaches,

Nectarines 6.8 (1) GAPeaches 28.6 0.01 0.08 0.09 0.32

* Bold values indicate a cute risk to listed and non

- listed aquatic plants LOC ( 1.0 ) is exceeded

.



### 4.1.2. Terrestrial Organisms

4.1.2.1. Mammals

There are acute dose

- based exceedances of the LOC for mammals from exposure to hydrogen

cyanamide ( Table 4.2 ) . The non

- listed species LOC is exceeded for all assessed mammalian

size classes foraging on short grass, tall grass, broadleaf plants and small a nd large arthropods

for all assessed uses. For mammals foraging on fruits/pods/seeds , the non

- listed species LOC is

exceeded for all assessed size classes, except for lar g e mammals (1000 g) exposed to hydrogen

cyanamide from use on nectarines and peaches. No LOCs were exceeded for granivorous

mammals. Subacute dietary toxicity data is not available for hydrogen cyanamide. Potential risks

to mammals from dietary exposure will be discussed in more detail in the Risk Description

.

Based on the proposed maximu m application rates, there are chronic dose

- based exposure

concerns for mammals of all size class es for all use patterns for all modeled scenarios . RQ

values range from 3. 50 to 1466

. Uncertainties and assumptions will be discussed further in the

risk characterization section. Table 4.3 lists maximum chronic EECs and RQs for all of the

proposed use rates based on the upper 90 th 

### percentile Kenaga values. Additionally, there are

exceedan ces for dietary

- based exposure ( Table 4. 4 ). There are exceedances for mammals of all

size class, use patterns and modeled scenarios . RQ values range from 3.96 to 1 69

.- Page 42 of 115

- 

### Table 4.2. Acute Dosed

- based Mammalian RQs for the Uses of Hydrogen Cyanamide.

Rate

(# apps;

interval) Size

Class

(grams) Adjusted

NOAEL EECs and RQs

Short Grass Tall Grass Broadleaf

Plants Fruits/Pods/

Seeds Arthropods Granivore

EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ

6.6 (1) 1 15 659.35 1510 2.29 ** 692 1.05 ** 8 50 1.29 ** 94. 4 0.14 * 59 2 0.90 ** 2 1.0 0.03

35 533.48 104 4 1.96 ** 478 0.90 ** 587 1.10 ** 65.2 0.12 * 40 9 0.77 ** 14. 5 0.0 3

1000 230.75 242 1.05 ** 11 1 0.48 * 136 0.59 ** 15.1 0.07 94. 8 0.41 * 3.36 0.01

13.2 (1) 2 15 659.35 3020 4.58** 1384 2.10** 1699 2.58** 189 0.29* 1183 1.79 ** 42.0 0.06

35 533.48 2088 3.91** 957 1.79** 1174 2.20** 130 0.24* 818 1.53 ** 29.0 0.05

1000 230.75 484 2.10** 222 0.96** 272 1.18** 30.3 0.13* 190 0.82 ** 6.72 0.02

17.6 (1) 3 15 659.35 4027 6.11** 1846 2.80** 2265 3.44** 252 0.38* 1577 2.39** 55.9 0.08

35 533.48 2783 5.22** 1276 2.39** 1566 2.93** 174 0.33* 1090 2.04** 38.7 0.07

1000 230.75 645 2.80** 296 1.28** 363 1.57** 40.3 0.17* 253 1.10** 8.96 0.03

1 nectarines and peaches

2 blackberries and blueberries

3 California figs

, apples, cherries, grapes, and kiwi fruits

*Bold indicates exceedance of the listed species acute

- based LOC (0.1).

** Bold indicates exceedance of the non

- liste d species acute

- based LOC (0.5).- Page 43 of 115

- 

### Table 4.3. Chronic Dosed

- based Mammalian RQs for the Uses of Hydrogen Cyanamide.

Rate

(# apps;

interval) Size

Class

(grams) Adjusted

NOAEL EECs and RQs

Short Grass Tall Grass Broadleaf

Plants Fruits/Pods/

Seeds Arthropods Granivore

EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ

6.6 (1) 1 15 2.75 1510 550 69 2 252 8 50 309 94. 4 34.4 59 2 215 2 1.0 7.63

35 2.22 104 4 470 478 215 587 264 65.2 29.4 40 9 184 14.5 6.52

1000 0.96 242 252 11 1 115 136 142 15.1 15.7 94. 8 98.6 3.36 3.50

13.2 (1) 2 15 2.75 3020 1099 1384 504 1699 618 189 68.7 1183 431 42.0 15.3

35 2.22 2088 939 957 430 1174 528 130 58.7 818 368 29.0 13.0

1000 0.96 484 503 222 231 272 283 30.3 31.5 190 197 6.72 6.99

17.6 (1) 3 15 2.75 4027 1466 1846 672 2265 825 252 91.6 1577 574 55.9 20.36

35 2.22 2783 1252 1276 574 1566 704 174 78.3 1090 490 38.7 17.39

1000 0.96 645 671 296 308 363 378 40.3 42.0 253 263 8.96 9.32

1 nectarines and peaches

2 blackberries and blueberries

3 California figs

, apples, cherries, grapes, and kiwi fruits

Bold indicates exceedance of the listed and non

- listed species chronic LOC (1.0)- Page 44 of 115

- 

### Table 4.4. Chronic Dietary

- based Mammalian RQs for the Uses of Hydrogen

Cyanamide.

Rate

(# apps;

interval) NOAE

C

(ppm) EECs and RQs

Short Grass Tall Grass Broadleaf

Plants Fruits/Pods/

Seeds Arthrpods

EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ

6.6 (1) 1

25 1584 63.4 726 29.0 891 35.6 99.0 3.96 620 24.8

13.2 (1) 2 3168 127 1452 58.1 1782 71.3 198 7.92 1240 49.6

17.6 (1) 3 4224 169 1936 77.4 2376 95.0 264 10.6 1654 66.2

1 nec tarines and peaches

2 blackberries and blueberries

3 California figs

, apples, cherries, grapes, and kiwi fruits

Bold indicates exceedance of the listed and non

- listed species chronic LOC (1.0)- Page 45 of 115

- 

### 4.1.2.2. Birds

There are acute dose

- based exceedances of the LOC for birds from exposure to hydrogen

cyanamide

. The non

- listed species LOC is exceeded for all assessed avian size classes foraging

on short grass, tall grass, broadleaf plants , and arthropods for all assessed uses. For uses on

blackberries, blueberrie s, California figs, apples, cherries, grapes, and kiwi fruits, small and

medium bird (20 g and 100 g, respectively) foraging on fruits/pods/seeds exceed the non

- listed

species LOC, while large birds exceed the listed species LOC only. For uses on nectarin es and

peaches, small birds foraging o n fruits/pods/seed exceed the non

- listed species LOC, while

medium and large birds exceed the listed species LOC only. For granivorous birds, RQs exceed

the non

- listed species LOC for small birds from use of hydrogen c yanamide on California fig,

apples, cherries, grapes, and kiwi fruits. In addition, t he listed speices LOC is exceeded for small

birds from use s on peaches and nectarines, small and medium birds from uses on blackberries

and blueberries, and medium birds f rom uses on California fig s , apples, cherries, grapes, and

kiwi fruits. RQs ranged from 0.03 to 38.6 ( Table 4.5 ).

Based on the available acute dietary toxicity data, no mortality was observed in any of the avian

studies conducted on hydrogen cyanamide a t the highest concentrations; as such, hydrogen

cyanamide is categorized “practically nontoxic” to birds on an acute

- dietary exposure basis.

However, sublethal effects, including lethargy, ruffled appearance, reduced reactions to sound

and movement stimul i, effects on body weight gain or loss, and reduction in feed consumption

was also observed, indicating potential toxicity. Though the acute dietary endpoint available for

birds is a non

- definitive value (>5000 ppm), it was used to calculate the upper bou nds of

potential risk. Based on the registered maximum application rates, the subacute dietary

- based

LOC may be exceeded for non

- listed species feeding on short grass exposed to 13.2 or 17.6 lbs

of hydrogen cyanamide per acre. In addition, the LOC may be e xceeded for listed species

feeding on short grass, tall grass, broadleaf plants, and anthropods from all uses of hydrogen

cyanamide ( Table 4.6 ). The RQs, ranging from 0.02 to 0.84, represent the upper bounds of

potential risk.

Based on the registered maximum application rates, the chronic dietary

- based LOC is exceeded

for all modeled scenarios except for birds foraging on fruits/pods/seeds exposed to hydrogen

cyanamide from use s on nectarines and peaches ( i.e., the lowest application rate). RQs ranged

from 0.6 5 to 2 7 .6 ( Table 4. 7 )

.- Page 46 of 115

- 

### Table 4.5. Acute Dose

- based Avian RQ for the Uses of Hydrogen Cyanamide.

Rate

(# apps;

interval) Size

Class

(grams) Adjusted

LD 50 EECs and RQs

Short Grass Tall Grass Broadleaf

Plants Fruits/Pods/

Seeds Arthropods Granivore

EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ

6.6 (1) 1 20 124.63 1804 14.5 ** 82 7 6.63 ** 101 5 8.14 ** 11 3 0.90 ** 70 7 5.67 ** 25. 1 0.20 *

100 158.67 102 9 6.48 ** 47 2 2.97 ** 57 9 3.65 ** 64.3 0.41 * 40 3 2.54 ** 14. 3 0.09

1000 224.12 46 1 2.06 ** 211 0.94 ** 259 1.16 ** 28. 8 0.13 * 180 0.80 ** 6.40 0.03

13.2 (1) 2 20 124.63 3608 29.0** 1654 13.3** 2030 16.3** 226 1.81** 1413 11.34 ** 50.1 0.4 1*

100 158.67 2057 13.0** 943 5.94** 1157 7.29** 129 0.81** 806 5.08 ** 28.6 0.18 *

1000 224.12 921 4.11** 422 1.88** 518 2.31** 57.6 0.26* 361 1.61 ** 12.8 0.06

17.6 (1) 3 20 124.63 4811 38.6** 2205 17.7** 2706 21.7** 301 2.41** 1884 15.1 ** 66.8 0.54 **

100 158.67 2743 17.3** 1257 7.92** 1543 9.73** 171 1.08** 1074 6.77 ** 38.1 0.24 *

1000 224.12 1228 5.48** 563 2.51** 691 3.08** 76.8 0.34* 481 2.15 ** 17.1 0.08

1 nectarines and peaches

2 blackberries and blueberries

3 California figs

, apples, cherries, grapes, and kiwi fruits

*Bold indicates exceedance of the listed species acute

- based LOC (0.1).

** Bold indicates exceedance of the non

- listed species acute

- based LOC (0.5).- Page 47 of 115

- 

### Table 4.6. Subacute Dietary

- based Avian RQ for the Uses of Hydrogen Cyanamide.

Rate

(# apps;

interval) LC 50 (ppm) EECs and RQs

Short Grass Tall Grass Broadleaf

Plants Fruits/Pods/

Seeds Arthropods

EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ

6. 6 (1) 1

>5000 1584 < 0.32

* 726 < 0.15

* 891 < 0.18

* 99.0 < 0.02 620 < 0.12

*

13.2 (1) 2

3168 < 0.63

** 1452 < 0.29

* 1782 < 0.36

* 198 < 0.04 1240 < 0.25

*

17.6 (1) 3

4224 < 0.84

** 1936 < 0.39

* 2376 < 0.48

* 264 < 0.05 1654 < 0.33

*

1 nectarines and peaches

2 blackberries and blueberries

3 California figs

, apples, cherries, grapes, and kiwi fruits

*Bold indicates exceedance of the listed species acute

- based LOC (0.1).

** Bold indicates exceedance of the non

- listed species acute

- based LOC (0.5).



### Table 4. 7

. Chronic Dietary

- bas ed Avian RQ for the Uses of Hydrogen Cyanamide.

Rate

(# apps;

interval) NOAEC

(ppm) EECs and RQs

Short Grass Tall Grass Broadleaf

Plants Fruits/Pods/

Seeds Arthropods

EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ

6. 6 (1 ) 1

153 1584 10.4 726 4.75 891 5.82 99.0 0.65 620 4.05

13.2 (1) 2 3168 20.7 1452 9.49 1782 11.7 198 1.29 1240 8.11

17.6 (1) 3 4224 27.6 1936 12.7 2376 15.5 264 1.73 1654 10.8

1 nectarines and peaches

2 blackberries and blueberries

3 California figs

, apples, cherries, grapes, and kiwi fruits

Bold indicates exceedance of the listed and non

- listed species chronic LOC (1.0)



### 4.1.2.3. Terrestrial Invertebrates

In order to assess the risks of hydrogen cyanamide to terrestrial invertebrates, the honey bee

(acute contact LD 50 

### of > 36.2 μ g a.i./bee ; MRID 43866902 ) is used as a surrogate for terrestrial

invertebrates. The toxicity value for terrestrial invertebrates is calculated by multiplying the

lowest available acute contact LD 50 

### of >36.2 μg a.i./bee by 1 bee/0 .128g, which is based on the

weight of an adult honey bee. EECs (μg a.i./g of bee) calculated by T

- REX for arthropods are

divided by the calculated toxicity value for terrestrial invertebrates, which is >4.63 μg a.i./g of- Page 48 of 115

- 

### bee ( Table 4.8 ). Based on this analysis RQs for terrestrial invertebrates exceed the LOC (0.05)

for all assessed uses of hydrogen cyanamide. These RQs represent the up per bound of the

potential risk. Wi thout a definitive toxicity endpoint it is not possible to determine the magnitud e

of the risk. RQs range from 134 to 357.

Table 4.8. Terrestrial Invertebrate RQs for Hydrogen Cyanamide.

Rate

(# apps;

interval) LC 50 ( μg a.i./g bee ) EECs and RQs

Arthropods

EEC RQ

6. 6 (1) 1

> 4.63 620 < 134

13.2 (1) 2 1240 < 268

17.6 (1) 3 1654 < 357

1 nectarines and peaches

2 blackberries and blueberries

3 California figs

, apples, cherries, grapes, and kiwi fruits

Bold indicates exceedance of the LOC ( 0.05 )



### 4.1.2.4. Non

- target Terrestrial Plants

Potential effects to riparian and upland vegetation are assessed deriving RQs from terrestrial

plant seedling emergence and vegetative vigor EC 25 

### and NOAE C endpoints. As discussed in

Section 3.3.2.4 , a non

- definitive NOAEC value (<0.056 lb a.i./A) for the most sensitive dicot

species from the seedling eme rgence study was used in risk calculation. Therefore, RQs based on

this value ( i.e., dicot listed species in dry and semi

- aquatic areas) appear as greater than values in

Table s 4. 9 and 4. 10 . The magnitude of these RQs is unknown. In addition, a correspondi ng EC 25



### value was not available for the most sensitive dicot species from the seedling emergence study.

As a result

, RQs for non

- listed species could not be calculated for dicots in dry and semi

- aquatic

areas. However, RQs for dicots in these areas that were calculable exceed the LOC for listed

species for all modeled exposures. In addition, RQs for monocots in dry and semi

- aquatic areas

exceed the LOC for listed and non

- listed species for all modeled exposures

. For plants exposed

through spray drift , RQs exceed the LOC for listed monocots and dicots for all modeled

exposures, while RQs exceed the LOC for non

- listed monocots for airblast applications to

blueberries, blackberries, California figs, apples, cherries, grapes, and kiwi fruits and for non

l isted dicots for airblast applications to apples, cherries, grapes, and kiwi fruits.- Page 49 of 115

- 

### Table 4. 9 . RQs for Terrestrial Plants Inhabiting Dry and Semi

- aquatic Areas Exposed to

Hydrogen Cyanamide via Runoff and/or Spray Drift from Airblast Applications

. Application

Rate

lbs ai/A Plant Type Listed

Status Dry Semi

- Aquatic Spray Drift

6.6 2 Monocot non

- listed 1.55 8.50 0.77

Monocot listed 16.59 91.11 8.29

Dicot 1 non

- listed

-- -- 0.38

Dicot 1 listed >12.14 >66.79 6.07

13.2 3 Monocot non

- listed 3.00 16.50 1.50

Monocot listed 32.20 177.07 16.10

Dicot 1 non

- listed

-- -- 0.74

Dicot 1 listed > 23.57 >129.64 11.79

17.6 4 Monocot non

- listed 4.00 22.00 2.00

Monocot listed 42.93 236.10 21.46

Dicot 1 non

- listed

-- -- 0.99

Dicot 1 listed > 31.43 >172.86 15.71

1 definitive NOAEC and EC 25 values were not calculable for the most sensitive species in the seedling emergence study

. For

calcluations that rely on this information (i.e., plants exposure via run

- off), t he LOAEC of 0.056 lb a.i./A is used in place of a

NOAEC to represent the lower bound of risk exposure.

2 nectarines and peaches

3 blackberries and blueberries

4 California figs

, apples, cherries, grapes, and kiwi fruits

Bolded values exceed LOC for plants (RQ > 1.0)



### Table 4. 10 . RQs for Terrestrial Plants Inhabiting Dry and Semi

- aquatic Areas Exposed to

Hydrogen Cyanamide via Runoff and/or Spray Drift from Ground Spray Applications

. Application

Rate

lbs ai/A Plant Type Listed

Status Dry Semi

- Aquatic Spray Drift

6. 6 2 Monocot non

- listed 0.93 7.88 0.15

Monocot listed 9.95 84.59 1.66

Dicot 1 non

- listed

-- -- <0.1

Dicot 1 listed >7.29 >61.93 1.21

13.2 3 Monocot non

- listed 1.80 15.30 0.30

Monocot listed 19.32 164.20 3.22

Dicot 1 non

- listed

-- -- 0.15

Dicot 1 listed > 14.14 >120.21 2.36

17.6 4 Monocot non

- listed 2.40 20.40 0.40

Monocot listed 25.76 218.93 4.29

Dicot 1 non

- listed

-- -- 0.20

Dicot 1 listed > 18.86 >160.29 3.14

1 definitive NOAEC and EC 25 values were not calculable for the most sensitive species in the seedling emergence study

. For

calcluations that rely on this information (i.e., plants exposure via run

- off), t he LOAEC of 0.056 lb a.i./A is used to represent the

lower bound of risk exposu re.

2 nectarines and peaches

3 blackberries and blueberries

4 California figs

, apples, cherries, grapes, and kiwi fruits

Bolded values exceed LOC for plants (RQ > 1.0)- Page 50 of 115

- 

### 4.2. Incident Database Review

A review of the Ecological Incident InformationSystem (EIIS) database for incidents involving

hydrogen cyanamide was conducted on February 27 th 

### , 2014

. Two incidents for hydrogen

cyanamide are reported in the database ( Appendix E ). The first incident, I000423

- 001, was

classified as probable and resulted fro m an accidental misuse of hydrogen cyanamide on grape

vineyards. The incident report indicates that hydrogen cyanamide applied during stormy weather

using a high pressure sprayer resulted in defoliation of several groves of nearby lemon trees.

Label langua ge requires use of a low pressure sprayer and application only when weather

conditions do not favor drift. In the second incident, I016036

- 022 , the California Department of

Pesticide Regulations reported 380 acres of kiwifruits were damaged after hydrogen cyanamide

application. This incident is classified as possible and resulted from a registered use of hydrogen

cyanamide.

Similarly, a search of the Avian Incident Monitoring System (AIMS;

http://www.abcbirds.org/abcprograms/policy/toxins/aims/aims/index.cfm ) was conducted on

February 27 th 

### , 2014 . AIMS is a database administered by the American Bird Conservancy that

contains publicly available data on reported avian inciden ts involving pesticides. No incident s

involving hydrogen cyanamide were found.

Pesticide registrants report certain types of incidents to the Agency as aggregate counts of

incidents occurring per product per quarter. Aggregate inci dent data is not available for

hydrogen cyanamide

.

The number of reports listed in the EIIS database is believed to be only a small fraction of the

total incidents involving organism mortality and damage caused by pesticides. Few resources are

assigned to incident report ing. 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 database is generated from registrant

- submitted incident reports. In addition,

incident reports for non

- target organisms typically provide information only on mortality 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 impaired reproduction are rarely reported. Because of

these logistical difficulties, EIIS is most likely a minimal representation of all pesticide

- related

ecological incidents

.

Therefore, the weight of evidence based on the currently available data suggests that direct

effects to terrestrial plant species are expected from the currently registered use of hydrogen

cyanamide

.

4. 3

. Risk Description

The results of risk estimati on indicate that uses of hydrogen cyanamide are unlikely to a dversely

affect fish, aquatic invertebrates or aquatic plants on either an acute or chronic exposure basis.

However, acute and chronic risks to terrestrial animals ( i.e., mammals, birds, and the ir- Page 51 of 115

- 

### surrogates) are very likely. Similarly, terrestiral plant risks are well above the Agency’s levels of

concern. Therefore, the risk hypothesis for this risk assessment is partially supported ( risk to

terrestrial organisms but not for aquatic organisms ).

4. 3 .1 Exposure to Aquatic Organisms

The Tier II model Pesticide Root Zone Model (PRZM v3.12.2; May 12, 2005; Carousel et al.

, undated) linked with EXposure Analysis Modeling System (EXAMS v2.98.4.6; Apr. 25, 2005;

Burns, 2004) via the PRZM/EXAMS model shell (PE v5.0, Nov. 15, 2006), i.e.

, PRZM/EXAMS) were used to estimate screening

- level exposure concentrations in aquatic

environments. The PRZM model simula tes pesticide movement and transformation on and

across the agricultural field resulting from crop applications. The EXAMS model simulates

pesticide concentrations in water due to loading via runoff, erosion, and spray drift, assuming a

standard 1

- ha pond , 2

- m deep (20,000 m 3 

### ) with no outlet that borders a 10

- ha treated field.

Simulations are for multiple (usually 30) years, from which the Agency estimates peak values

that are expected to recur on average once every ten years, based on time series of dail y

estimated concentrations. The coupled PRZM and EXAMS models and user’s manuals are

available from the U.S. Environmental Protection Agency Water Models web

- page (USEPA,

2011b).

Aquatic exposure was modeled with a 900 foot buffer for drift but not run

- o ff. Current label

language requires a 900 foot buffer between the field of application and “the mean high water

mark for intertidal areas, surface waters, rivers, streams, or their flowing tributaries” to reduce

potential exposures to nearby waterbodies

.

The initial application date was selected in consulation with experts in order to simulate 30 or

more days before normal budbreak. Application d ates for modeling purposes were selected in

accordance with the proposed labels to generate the most conservat ive estimates of aquatic

exposure and based on information from the Cooperative Extension offices or from the World

Wide Web.

Model uncertainties are discussed in greater detail in Section 4. 4

.

4. 3 .2 Risks to Aquatic Animals

Although hydrogen cyanamide does exhibit topxic effects on freshwater and estuarine/marine

fish and invertebrates on an acute exposure basis , RQs are all well below the Agency’s levels of

concern for all of the modeled scenarios.

Risk quotients could no t be calculated for freshwater fish on a chronic exposure basis because

the available study provides a non

- definintive NOAEC value of < 507 ppb, the lowest

concentration tested. Lack of a definitive NOAEC value , and a LOAEC value within one order- Page 52 of 115

- 

### of magnit ude of the highest exposure scenario, suggest that risk to freshwater fish from chronic

exposure to hydrogen cyanamide can not be precluded. 

## However, as discussed previously

, the

magnitude of biological effects observed at the lowest concentration tested a ppear to be close

to the limit of statistical and biological significance. This information, combined with the

evidence of a dose response in the higher treatment concentrations, make it unlikely that

another early life stage test with the rainbow trout wi ll provide a NOAEC value that is

substantially lower than the lowest concentration tested in the available study.

Chronic toxicity data was not avaible for estuarine/marine fish. It is not possible to calculate an

acute

- to

- chronic ratio (ACR) because onl y a non

- definitive NOAEC is ava ilable for the

freshwater fish. Based on the available acute toxicity data, estuarine/marine fish exhibit similar

toxicity as freshwater fish so it is likely that they exhibit similar toxicity on a chronic exposure

basis . Chr onic ri sk to estuarine/marine fish can not be precluded. In addition, available aerobic

aquatic metabolism data suggests that hydrogen cyanamide degrades faster under flowing

conditions (1.2 days in a stream system versus 3.2 days in a pond system) , such as may be found

in some estuarine/marine systems. As a result of this shorter half

- life, chronic risks to

estuarine/marine fish that reside in flowing waters may be low

.

Chronic risk to freshwater invertebrates is expected to be low based on chronic toxicity data

submitted for the daphnid, with RQs ranging from 0.06 to 0.69. C hronic toxicity data is not

available for estuarine/marine invertebrates. The acute to chronic rat io (ACR) of 33 for the

daphnid (most sensitive freshwater invertebrate) was applied to the available acute mollusk (the

most sensitive estuarine/marine invertebrate) and acute Mysid shrimp data in order to bracket the

potential for chronic effects to estua rine/marine invertebrates. Uncertainties associated with this

approach are discussed further in the uncertainties section. When the ACR was used to estimate

chronic toxicity to the eastern oyster, RQs ranged from 0.09 to 1.0, indicating potential for risks

to estuarine/marine mollusks from chronic exposure from hydrogen cyanamide use on cherries.

Additionally, when the ACR for the daphnid was applied to the acute toxicity value available for

the pink shrimp (LC 50 

### = 6300 ppb), RQs ranged from 0.03 to 0.36, s uggesting that the potential

for chronic risk to crustaceans is low. With this information chronic risks to mollusks can not be

precluded but risks to crustaceans are not likely

.

4. 3 .3 Risks to Aquatic Plants

Although hydrogen cyanamide does exhibit effects on both Lemna gibba and Anabaena flos

aquae , these effects are at much higher concentrations than those estimated for the majority of

the hydrogen cyanamide uses. However, the acute listed species RQ is equ al to the LOC for

non

- vascular plants exposed to hydrogen cyanamide from the cherry use , which indicates that

risks to listed aquatic non

- vascular plants may occur

. However, as discussed previously EECs

are primarily driven by the modeled run

- off, which as sumes no buffer between the site of

application and the water body. Given the 900 ft buffer required between the site of application

and any waterbody and the rapid degradation of hydrogen cyanamide in soil, exposure to aquatic

environments may be over est imated . As a result of this limitation risks to aquatic non

- vascular- Page 53 of 115

- 

### plants may be overestimated. In fact, EECs for use of hydrogen cyanamide on cherries would

only need to drop ~1% to result in RQs below the level of concern.

In addition , risk to aquatic nonvascular species is typica lly evaluated with not only the

cyanobacteria species that was submitted, but also with a green algae , a centric diatom and a

pinnate diatom. Acceptable studies with these species have not been submitted and are an

app reciable source of uncertainty in the risk assessment. These planktonic taxa form the basis of

the aquatic food web and are frequently more sensitive to pesticides than cyanobacteria

. While

uncertainties associated with EECs discussed above likely result in an over estimation of

exposure to aquatic environments

, risks to aquatic non

- vascular plants cannot be precluded

without data on the additional algal species.

4. 3 .4. Risks to Mammals

Results of toxicity studies indicate that hydrogen cynamide is “ moderately toxic” to mammals on

an acute exposure basis. Acute risk concerns were triggered for all assessed mammalian size

classes foraging on short grass, tall grass, and broadleaf plants, and arthropods for all assessed

uses. For mammals foraging on fr uits/pods/seeds, acute risk concerns were triggered for all

assessed size classes, except for large mammals (1000 g) exposed to hydrogen cyanamide from

use on nectarines and peaches. Acute risk is not expected for granivorous mammals. Acute dose

based RQs range from 0.02 for large granivorous mammals to 6.11 for small mammals feeding

on short grass. Based on its reported toxicity to mammals, the maximum application rate of

hydrogen cyanamide that would not result in acute risk concerns is 0. 65 lbs a.i./A

.

In addition to the acute risk concerns identified, chronic dose

- based and dietary

- based risk

concerns are triggered for mammals of all size class for all use patterns for all modeled

scenarios

. RQ s for chronic dose

- based exposure range from 3.60 to 1466 a nd RQs from chronic

dietary

- based exposure range from 26.5 to 169

. Based on these conservative RQs, t he maximum

application rate of hydgrogen cyanamide that would not result in chronic dose

- based or chronic

dietary

- based concerns is 0.005 lbs a.i./A. Howev er, the chemical properties and available

residue data discussed previously suggest that hydrogen cyanamide degrades rapidly in the

environment. Without prolonged exposure, chronic risks to mammals may be considerably

reduced. However, if the foliar half

- l ife for hydrogen cyanamide is 1 day, risks to mammals from

chronic exposure would likely not occur given that the chemical is only applied once per season.

A foliar dissipation study would reduce the uncertainty associated with chronic risk to mammals.

R esults of the screening model SIP also indicate that drinking water exposure is a potential

concern for mammals based on acute and chronic exposure . Hydrogen cyanamide has a very

high solubility in water ( 78 0 ,000 mg/L) , which is the only parameter used in estimating potential

exposure, and mammals are particularly sensitive to hydrogen cyanamide on an acute and

chronic basis.

Risks may be mitigated by the geographic and temporal limitations of the chemical. Hydrogen

cy anamide is only registered for use on a limited number of fruit bearing trees and ground fruit,- Page 54 of 115

- 

### including: nectarines, peaches, blackberries, blueberries, figs, apples, cherries, grapes, and kiwi

fruits. Further, g eo graphic restrictions outlined on the lab els limit the use of hydrogen cyanamide

on certain crops and in certain regions (see Table 3.1 for more information). Thes limited use

patterns for hydrogen cyanamide may result in substantially less overlap with endangered species

habitat than a chemical with a ubiquitous use pattern ( e.g., corn). In addition to these geographic

boundaries, labels state that hydrogen cyanamide is to be applied 30 days prior to normal bud

break. For the assessed uses this means that application occurs between December and M arch

(see Table 3.6 for more information)

. The temporal and geographic limitations suggest that

potential for acute risks are limited to those species that are active in late winter , especially in

temperate regions of the country

. The exception may be for uses of hydrogen cyanmide in areas

with winters mild enough that mammals remain active and plants do not senesce ( e.g.,

California, Hawaii, and Florida).

4. 3 .5. Risk to Birds

Results of toxicity studies indicate that hydrogen cynamide is “moderately toxic” to birds on an

acute dose

- based exposure basis

. Combined with the high application rates, a cute dose

- based risk

concerns were triggered for all assessed avian size classes foraging on short grass, tall grass,

broadleaf plants, and arthropods for all assessed uses. For uses on blackberries, blueberries,

California figs, apples, cherries, grapes, and kiwi fruits, small and medium bird s (20 g and 100 g,

respectively) foraging on fruits/pods/seeds are at risk, while only listed species of large birds

may be at risk . For uses on nectarines and peaches, small birds foraging on fruits/pods/seed are

at risk , while only listed species of medium and large birds are at risk . For granivorous birds,

small birds are at risk from use of hydrogen cyanamide on California fig, apples, cherries,

grapes, and kiwi fruits. In addition, listed species of small birds may be at risk from uses on

peaches and nectarines, listed small and medium birds from uses on blackberries and blueberries,

and listed mediu m birds from uses on California figs, apples, cherries, grapes, and kiwi fruits.

The maximum application rate of hydgrogen cyanamide that would not result in acute dose

based concerns to non

- listed species is 0. 32 lbs a.i./A.

Results of the acute die tary studies classify hydrogen cyanamide as “practically non

- toxic”.

However , application rates for the assessed uses were sufficient to trigger risk concerns for birds

from dietary exposure to hydrogen cyanamide . In addition

, sublethal effects including l ethargy,

ruffled appearance, reduced reactions to sound and movement stimuli, effects on body weight

gain or loss, and reduction in feed consumption observed during the stud is indicat e that hydrogen

cyanmide is potential ly toxicity or unpalatable to upland and game bird species

. These

behavioral modifications, especially the food avoidance beha vior, may result in even greater

dietary risks to passerine species, which exhibit regurgitation behavior when they come in

contact with unpalatable or toxic substances. Acute dose

- based and dietary

- based risks to

passerine species respresent a substantial uncertainty in this anal ysis

.

In addition to the acute risks identified, chronic dietary

- based concerns are triggered for all

modeled scenarios except for birds foraging on fruits/pods/seeds exposed to hydrogen cyanamide- Page 55 of 115

- 

### from uses on nectarines and peaches ( i.e., the lowest ap plication rate). The maximum

application rate of hydrogen cyanamide that would not result in chronic dietary

- based concerns

to listed or non

- listed species is 0.64 lbs a.i./A. However, the chemical properties and available

residue data discussed previousl y suggest that hydrogen cyanamide degrades rapidly in the

environment. Without prolonged exposure, chronic risks to birds may be considerably reduced.

However, if the foliar half

- life for hydrogen cyanamide is 1 day, risks to birds from chronic

exposure wo uld likely not occur, especially given hydrogen cyanamide’s single application per

season use. A foliar dissipation study would reduce the uncertainty associated with chronic risk

to birds.

Results of the screening model s SIP and STIR indicate that drink ing water and inhalation

exposure are of potential concern for birds based on acute and chronic exposure. Hydrogen

cyanamide has a very high solubility in water ( 78 0 ,000 mg/L) and relatively volatile (0.00375

mmHg) , which are the only parameter s used in e stimating potential exposure for SIP and STIR,

respectively. In addition birds are relatively sensitive to hydrogen cyanamide on an acute and

chronic basis.

As discussed in the previous section, risks to birds may be mitigated by the geographic and

temporal limitations of hydrogen cyanamide use.

4. 3 .6. Potential Effects on Terrestrial Invertebrates



## An acute contact toxicity study (MRID 43866902) showed that cyanamide is essentially non

toxic to the honey bee (LD50 >36.2 mg a.i./bee, and NOEL appr oximately 12 mg a.i./bee).

Screening

- level risk assessments do not typically evaluate risks to terrestrial invertebrates;

however, toxicity information for beneficial insects is used to develop precautionary label

language where necessary. While hydrogen cyanamide is “practically non

- toxic” to honey bees,

the high application rates used may pose risks to bees as a result of high field residues (max

EECs are over 1 6 00 ppm a.i.). A foliar dissipation study would reduce uncertainties associated

with risks to beneficial insects.

4. 3 .7. Risk to Terrestrial Non

- target Plants

As discussed in Section 3.3.2.4

, there are considerable uncertainties associated with the available

terrestrial plant data, including the use of a non

- definitive NOAEC value (<0.056 lb a .i/A) for the

most sensitive dicot species from the seedling emergence study to calculate risk

. As a result, RQs

based on this value ( i.e., dicot listed species in dry and semi

- aquatic areas ) appear as greater than

values and y he magnitude of risk is unknown. In addition, d ue to uncertainties in the available

data set

, risk could not be estimated for non

- listed dicots in dry and semi

- aquatic areas ( i.e., risk

from exposure through run off)

. However, risk is expected for listed terrestrial plants ( dicot and

monocot) in dry and semi

- aquatic areas for all model ed exposures

. In addition, two incidencts

have been reported for hydrogen cyanamide; however, both incidents reported damage to crops

after potential misuse (I000423

- 001 and I016036

- 022).- Page 5 6 of 115

- 

### The Agency does not currently have guidance to refine the risk posed by runoff, but the risk from

spray drift alone can be refined using AgDRIFT. AgDRIFT was used to determine the distance

from the edge of field where the RQ falls below the LOC for each o f the species ( Tables 4. 8

- 4. 9 )

for airblast application s for for the most common and highest application rate ( 17.6 lbs ai/A for

use on California fig, apples, cherries, grapes, and kiwi fruit) and the lowest application r ate (6.6

lbs ai/A for use on necta rines and peaches) . Model defaults for each scenario were used.

Uncertainties and gaps in the available terrestrial plant data ( e.g., EC 25 

### values are not available

for all species) limit the accuracy of this information.

Table 4.10 Distance (feet) from the edge of field where the RQ falls below the risk

to terrestrial plant LOC for vegetative vigor and seedling emergence endpoints for

airblast application, based on AgDRIFT EECs for the aerial application at 6.6 lbs

ai/A.

Plant

Spe cies Vegetative V igor

EC 25 NO A EC Nonlisted Listed

Corn 7.9 7.2 0 0

Oat

- a

- -- a

-- a

-- a

Ryegrass >20 20 0 0

Onion 13 7.2 0 0

Lettuce 4.5 3.6 0 0

Cabbage >14 1.8 0 0

Tomato 0.89 0.096 0 0

Carrot >20 20 0 0

Cucumber 4.2 0.73 0 0

Soybean 9.6 7.2 0 0

a Phytotoxic effects >25% were observed in the control group, indicating poor husbandry. The vegetative vigor

endpoints for this species were invalidated; therefore, buffer distances could not be calculated.



### Table 4.11 Distance (feet) from the edge of field where the RQ falls below the risk to

terrestrial plant LOC for vegetative vigor and seedling emergence endpoints for

airblast application, based on AgDRIFT EECs for the aerial application at 17.6 lbs

ai/A.

Vegetative V igor- Page 57 of 115

- Plant Species

EC 25 NO A EC Nonlisted Listed

Corn 7.9 7.2 0 0

Oat

-- a

-- a

-- a

-- a

Ryegrass >20 20 0 0

Onion 13 7.2 0 0

Lettuce 4.5 3.6 0 0

Cabbage >14 1.8 0 0

Tomato 0.89 0.096 0 7

Carrot >20 20 0 0

Cucumber 4.2 0.73 0 0

Soybean 9.6 7.2 0 0

a Phytotoxic effects >25% were observed in the control group, indicating poor husbandry. The vegetative vigor

endpoints for this species were invalidated, therefore buffer distances could not be calculated.



### Airblast applications result in more drift than ground sprays, therefore, impacts from airblast

applications are expected farther from the field edge for ground applications. Application rate is

a key variable in determining the distance effective drift is expect ed to travel, so airblast

applications of 17.6 lbs ai/A will have an impact at greater distance from the application area

than the 6.6 lbs ai/A rate. For nonlisted and listed plants, assessed species are not expected to be

at risk beyond the edge of the ap plication area. In addition, h ydrogen cyanamide labels attempt

to account for possible risks to endangered species from drift by restrict ing the use of hydrogen

cyanamide products in areas with endangered species ; however, labels do not mention specific

b uffer distances

.

4. 4

. Uncertainties and Data Gaps

4. 4 .1. Fate and Transport

For the purposes of risk assessment the submitted environmental fate data are adequate. The

quality of the submitted data is generally adequate. The acceptable batchequilibrium study

(MIID 4 2178414) demonstrates a lack of adsorption to soil particles. Adsorption of hydrogen

cyanamide was so limited that Freundlick coefficient

- values would not accurately quantify the

mobility of hydrogen cyanamide. Although a sing le acceptable aerobic study was reviewed, a

conservative approach was used when evaluating aquatic exposure by multiplying the single- Page 58 of 115

- 

### value by 3 ( Table 3.5 )

.

4. 4

. 2

. Aquatic Exposure

There is uncertainty associated with the ability of the aquatic exposure modeling to simulate

aquatic exposures as well as with the selection of input parameters. In this regard, one of the

potentially important parameters that can impact concentration estimates is the selection of

appropriate application dates. Although the pesticide application dates were selected to be most

appropriate with considerations for labeled application recommendations ( e.g. , 30 days before

bud break) model simulated cropping dates, and label restrictions, variability nevertheless results

because the time span that a pesticide may be applied may be large and the actual application

dates are unknown, or vary for different regions of the country. Such variability is caused by the

temporal proximity of a pesticide application to rain events. As with all model estimates, the

values presented here should not be viewed as precise estimates.

In addition, registered labels for hydrogen cyanamide products include a language requiring a

900 ft buffer between the site of application and “the mean high water mark for intertidal areas,

surface waters, rivers, streams, or their flowing tributaries” to limit the potential for exposure of

hydrogen cyanamide to aquatic environments. While aquatic EECs were modeled using a 900 ft

buffer for drift, the Agency does n ot currently have a method for modeling the impact of a buffer

on run

- off. Therefore, EECs are primarily driven by the modeled run

- off, which assumes no

buffer between the site of application and the water body. Given the rapid degradation of

hydrogen cyan amide in soil, this is a major source of uncertainty in the aquatic exposure and

subsequent risk assessment. As a result of this limitation risks to aquatic organisms may be

overestimated.

4. 4

. 3

. Effects Uncertainties

An area of uncertainty for this assessment surrounds potential chronic risk to birds. Current data

on mallard duck are inadequate to derive a definitive NOAEC or make a definitive determination

of risk (effects were noted at all test concentrations). Whi le a second avian reproduction study

on mallard duck that results in derivation of a NOAEC would reduce uncertainty, chronic risks

are already identified for birds based on the available bobwhite quail data. Therefore, additional

data on the mallard duck i s not necessary at this time. In addition, acute toxicity data is not

available for a passerine species; however, given the magnitude of difference needed to reduce

application rates such that risk is below the level of concern, this data is unlikely to ch ange the

risk assessment.

There is also uncertainty surrounding the potential for chronic risks to fish. Current data on the

freshwater species, rainbow trout, are not adequate to derive a definitive NOAEC because effects

were noted at all test concentrat ions. This represents a substantial data gap in the analysis. Since

the available LOAEC is within one order of magnitude of the highest EEC, chronic risk to

freshwater fish cannot be precluded. However , the magnitude of biological effects observed at- Page 59 of 115

- 

### the l owest concentration level appears to be close to the limit of statistical and biological

signifigance. In addition, as discussed previously the aquatic EECs do not take into consideration

the impacts of the required 900 ft buffer on run

- off. Therefore, the benefits of receiving another

early life stage study to define a NOAEC may not be substantial.

Chronic toxicity data was not avaible for estuarine/marine fish. It is not possible to calculate an

acute

- to

- chronic ratio (ACR) because only a non

- definitive NOAEC is available for the

freshwater fish. This represents a substantial data gap in the analysis.

Another area of uncertainty surrounds the potenti al for chronic risks to estuarine/marine

invertebrates because this data is not available

. While there is uncertainty associated with

applying the acute to chronic ratio (ACR) for the daphnid (most sensitive freshwater

invertebrate) to the mollusk (most sensitive estuarine/marine invertebrate) because of the

differences in life history, applying the ACR to the mollusk and the less sensitive Mysid shrimp

can be used to bracket the potential risks to estuarine/marine invertebrates. When the ACR was

used to estimate chronic toxicity to the eastern oyster, RQs ranged from 0.09 to 1.0, indicating

potential for risks to estuarine/marine mollusks from chronic exposure from hydrogen cyanamide

use on cherries. Additionally, when the ACR for the daphnid were applied to the acute toxicity

value available for the pink shrimp (LC 50 

### = 6300 ppb), RQs ranged from 0.03 to 0 .36, suggesting

that the potential for chronic risk to crustaceans is low. With this information chronic risks to

mollusks can not be precluded but risks to crustaceans are likely low.

Additionally, the Agency has only received data for two species of non

- vascular aquatic plants

, instead of the four species typically required. Without this data risks to these taxa of aquatic

plants may be underestimated.

There are considerable uncertainties associated with the available plant toxicity data

. For

seedling emergence, d efinitive EC 25 

### and NOAEC values were not calculable for the most

sensitive dicot species (lettuce) in the available seedling emergence study. As a result, risks to

non

- listed plant species could not be calculated and RQs for liste d species were calculate d based

on the LOAEC value (0.05 6 lbs a.i./A). RQs may underestimate the magni tude of risk to listed

species exposed to hydrogen cyanamide via run

- off and spray drift. In addition, phytotoxicity

observed in the control group was gre ater than 25% for one species (oat) in the vegetative vigor

study . This suggests that growing conditions may not have been optimal for this species or cross

contamination may have occurred. As a result, this data could not be used in the AgDrift analysis

t o calculate buffer distances. Risks may be underestimated for plants with similar toxicity to oat.

In addition, the EC 25 

### value for the most sensitive dicot species (tomato) should be interpreted

with caution, as it is not bracketed by the test concentratio ns

.

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 Fisheries Service (NMFS) for marine and- Page 60 of 115

- 

### anadrom ous 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 critical habitat. Each federal agency is requ ired 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 designated

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 both the survival and recovery of a listed species in the wild by reducing the

reproduc tion, 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

propos ed 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 listed species (USEPA, 2004). After the Age ncy’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 species

may co

- occur in the area of the pro posed 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

liste d 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 new registration of hyd rogen cyanamide 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 hydrogen cyanamide use and not merely the immediate area where

hydrogen cyanamide is applied. At the initial baseline, the risk assessm ent 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 to 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

species LOCs, a "no effect" determination conclusion is made wi th respect to listed species in

that taxa, and no further refinement of the action area is necessary. Furthermore, RQs bel ow the

listed species LOCs for a given taxonomic group indicate no concern for indirect effects on listed- Page 61 of 115

- 

### species that depend upon the taxonomic group for which the RQ was calculated. However, in

situations where the screening assumptions lead to RQs in e xcess of the listed species LOCs for a

given taxonomic group, a potential for a "may affect" conclusion exists and may be associated

with direct effects on listed species belonging to that taxonomic group or may extend to indirect

effects upon listed speci es that depend upon that taxonomic group as a resource. In such cases,

additional 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 assump tions

regarding an action 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 dow nwind and downstream of the pesticide use

site.

Assessment endpoints, exposure pathways, and the conceptual models addressing proposed new

hydrogen cyanamide uses, and the associated exposure and effects analyses conducted for the

hydrogen cyanamide baseline risk assessment are in Sections 2 to 3 . The assessment endpoints

used in the baseline risk assessment include those defined operationally as reduced survival and

reproductive impairment for both aquatic and terrestrial animal species and surviva l,

reproduction, and growth of aquatic and terrestrial plant species from both direct acute and

chronic 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 exp osure and effects, are calculated for broad based taxonomic groups

in the screening

- level risk assessment presented in Section 4.

Both acute endangered species and chronic risk LOCs are considered in the baseline risk

assessment to identify direct and ind irect effects to taxa of listed species. This section identifies

direct effect concerns, by taxa that are triggered by exceeding endangered LOCs in the baseline

risk assessment, with an evaluation of the potential probability of individual effects for exp osures

that may occur at the established endangered species LOC. Data on exposure and effects

collected 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 fo r

direct effects to listed taxa are described in Table 5.1 below.- Page 62 of 115

- 

### Table 5.1. Potential Effects to Federally Listed Taxa Associated with Direct Effects from

the Registered Uses of Hydrogen C yanamide.

Listed Plant Taxon Potential Direct Effects

Terrestrial and semi

- aquatic

plants

– monocots and dicots Yes

Aquatic nonvascular plants Uncertain 7,8

Aquatic vascular plants No

Listed Animal Taxon Potential Direct Effects

Acute Chronic

Terrestrial invertebrates Uncertain 1 ND

Mammals Yes 2,3,5 Yes 3,5

Birds Yes 2,4,5 Yes 4,5

Reptiles Yes 2,4, 5 Yes

A mphibians No effect 6 Uncertain 7, 9

Freshwater fish No effect 6 Uncertain 7, 9

Freshwater invertebrates No effect 6 No effect 10

Mollus k s No effect 6 ND

E stuarine /marine fish No effect 6 Uncertain 7

, 1 1

E stuarine /marine invertebrates No effect 6 No effect 7

, 1 2

ND Not determined.

1 Although no effects were seen in the acute contact toxicity tests with honey bees, the limit dose (36.2 μg a.i./bee) was not high

enough to preclude risk at the listed species LOC, based on the relatively high hydrogen cyanamide EECs for registered uses.

2 Risks to terrestrial animals from exposure to hydrogen cyanamide are extensive as a result of the high application rates curr entl y

registered for use.

3 Based on its reported toxicity to mammals, the maximum application rate that would not result in acute or chronic risk concer ns

is 0.65 lb a.i./A or 0.005 lb a.i./A, respectively. Chance of individual effect for listed species is 1 in 1 at derived RQ.

4 Based on its reported toxicity to birds, the maximum application rate that would not result in acute risks is 0.32 lb a.i./A, while

the application rate that would not result in chronic risks is 0.64 lb a.i./A. Chance of individual effect for listed species is 1 in 1 at

derived RQ.

5 Risk may be limited by geographic and temporal use patterns of hydrogen cyanamide ( i.e., it is only for use on a nectarines,

peaches, blackberries, blueberries, figs, apples, cherri es, grapes, and kiwi fruits ; it is subject to seve ral geographic use

restrictions; and is only applied December through March).

6 Risk of direct effects from acute aquatic exposure to formulated hydrogen cyanamide is expected to be below the LOC.

7 EECs are primarily driven by the modeled run

- off, which assumes no buffer between the site of application and the water body.

Hydrogen cyanamide degrades rapidly in soil (aerobic soil half

- life of 12 hours in sandy loam soil), and the aerobic aquatic

meta bolism half

- life value of 5.28 days represents the 90 th percentile of the upper confidence bound for the mean of the two

available half

- life values (3.2 days in a pond system and 1.2 days in a stream system). Therefore chronic risks to aquatic

organisms ma y be overestimated.

8 T he acute listed species RQ is equal to the LOC for non

- vascular plants exposed to hydrogen cyanamide from the cherry use

only. EECs would only need to drop ~1% to result in RQs below the level of concern.

9 Current data on the fresh water species, rainbow trout, are not adequate to derive a definitive NOAEC because effects were

noted at all test concentrations. Since the available LOAEC is within one order of magnitude of the highest EEC, chronic risk to

listed freshwater fish cannot be precluded. However, the magnitude of biological effects observed at the lowest concentration

level appears to be close to the limit of statistical and biological significance.

10 Risk of direct effects from chronic aquatic exposure to formulated hydroge n cyanamide is expected to be below the LOC.

1 1 Chronic toxicity data was not available for estuarine/marine fish. It is not possible to calculate an acute

- to

- chronic ratio (ACR)

because only a non

- definitive NOAEC is available for the freshwater fish. T his represents a substantial data gap in the analysis.

Based on the available acute toxicity data, estuarine/marine fish exhibit similar toxicity as freshwater fish so it is likely that they

exhibit similar toxicity on a chronic exposure basis.

1 2 Though chronic toxicity data is not available for estuarine/marine invertebrates, RQs calculated based on an ACR for the

daphnid are well below the chronic risk LOC.- Page 63 of 115

- 

### 5.2.1. Probit Dose

- Response Analysis

The Agency uses the probit dose

- response relationship as a tool for providing additional

information on the potential for acute direct effects to aquatic and terrestrial animals (USEPA,

2004). As part of this evaluation, the acute RQ for listed species is presented in terms of the

chance of an individual event ( i.e. , mortality or immobilization) should exposure at the EEC

actually occur for a species with sensitivity to hydrogen cyanamide on par with the acute toxicity

endpoint selected for RQ calculation. To accomplish this inter pretation, the Agency uses the

slope of the dose

- response relationship available from the toxicity study used to establish the

acute toxicity measures of effect for each taxonomic group that is relevant to this assessment.

The individual effects probabili ty associated with the acute RQ is based on the mean estimate of

the slope and an assumption of a probit dose

- response relationship. In addition to a single effects

probability estimate based on the mean, upper and lower estimates of the effects probabili ty are

also provided to account for variance in the slope, if available. Based on the available acute

toxicity for hydrogen cyanamide , a summary of the probit dose

- response analysis is provided in

Table 5.2 . If no dose response information is available t o estimate a slope for this analysis, a

default slope assumption of 4.5 (with lower and upper bounds of 2 to 9) (Urban and Cook, 1986)

is used.

Individual effect probabilities are calculated based on an Excel spreadsheet tool IECV1.1

(Individual Effect Chance Model Version 1.1) developed by the U.S. EPA, OPP, Environmental

Fate and Effects Division (June 22, 2004). The model allows for such calculations by entering

the mean slope estimate (and the 95% confidence bounds of that estimate) as the slope par ameter

for the spreadsheet. The desired threshold for the probability of an individual effect is entered as

the listed species LOC. In addition, the probability of an individual effect is also derived based

on the calculated acute RQ, if available.- Page 64 of 115

- 

### Tabl e 5.2. Summary of Hydrogen cyanamide Probit Dose Response Analysis for Listed

Species

Taxa (study type) Acute Effect

Slope (95% C.I.) Chance of Individual

Effect at Listed Species

LOC (95% C.I.) Chance of Individual

Effect at Derived Acute

RQ 1,2, 3,4,5,6 (95% C.I.)

Bird oral dose Mortality

Default Slope = 4.5

(2

- 9) 1 in 3.34E+40

(1 in 6.32E+14 to 1 in

9.03E+78) 1 in 1

(1 in 1 to 1 in 1) 1

Bird dietary No mortality observed Not calculated; no

mortality observed Not calculated; no

mortality observed

Mammal oral dose Mortality

Default Slope = 4.5

(2

- 9) 1 in 3.34E+40

(1 in 6.32E+14 to 1 in

9.03E+78) 1 in 1

(1 in 1 to 1 in 1) 2

Freshwater Fish Mortality

Slope = 8.65

( 3.49

– 13.81 ) 1 in 9.03 E+ 2 8

(1 in 3.57E+05 to 1 in

5.68 E+ 7 1) 1 in 1.32E+120

(1 in 4.41E+20 to 1 in

4.41E+303 ) 3

Estuarine/Marine Fish Mortality

Slope = 15

( 9.17

– 21.29 ) 1 in 2.46E+84

(1 in 2.44E+32 to 1 in

2.78E+168 E+31) 1 in 1.0 E+1 6

(1 in 6.38E+134 to 1 in

1.0E+16 ) 4

Freshwater invertebrates Immobilization

Slope = 7.70

( 4.58

– 10.83 ) 1 in 4.57 E+ 23

(1 in 7.87 E+ 08 to 1 in

4.58 E+ 44 ) 1 in 2.14 E+3 1

(1 in 6.53 E+ 11 to 1 in

4.84 E+ 60 ) 5

Estuarine/Marine

invertebrates Shell Deposition

Default Slope = 4.5

(2

– 9) 1 in 4.18 E+ 08

(1 in 2.16 E+ 02 to 1 in

1.75 E+ 31 ) 1 in 6.33 E+ 09

(1 in 3.86 E+ 02 to 1 in

7.49 E+ 35 ) 6

1 Acute RQ for bird oral dose = 38.6

2 Acute RQ for mammal oral dose = 6.11

3 Acute RQ for freshwater fish = 0. 002

. 4 Acute RQ for estuarine/marine fish = 0.002

5 Acute RQ for freshwater invertebrates = 0. 03

. 6 Acute RQ for estuarine/marine invertebrates = 0.04



### As shown in Table 5.2 , t he probability for acute direct effects ( i.e. , mortality) to individual listed

bird and mammal (based on the most sensitive species, bobwhite quail or laboratory rat ) and the

highest derived RQ value s is 1 in 1

. The chance of individual effects for fish, based on the most

sensitive species, rainbow trout, is 1 in 1.32X10 120



### . The chance of an individual effect for aquatic

invertebrates, based on the most sensitive species, Eastern oyster, is 1 in 6.33 X 10 09



### . This is base

don a default slope of 4.5. If the slope was steeper the chance of an individual effect would

decrease further (slope of 9; 1 in 7.49X10 35 

### )

.- Page 65 of 115

- 

### 6. References

Francisco J. Perez, Ricardo Vergara, and Sebastia ́n Rubio. 2008. H2O2 is invo lved in the

dormancy

- breaking effect of hydrogen cyanamide in grapevine buds. Plant Growth Regul (2008)

55:149

– 155.

F.J. Perez, R. Vergara, E. Or. 2009. ‘‘On the mechanism of dormancy release in grapevine

buds:Acomparative study between hydrogen cyanamide and sodium azide’’, Plant

Growth Regul. 59

- 145.

Or E, Vilozny I, Eyal Y, Ogrodovitch A.2000. The transduction of the signal for grapebud

dormancy breaking induced by hydrogen cyanamide may involve the SNFlike protein

- kinase

GDBRPK. Plant Mol Biol 43:483

– 494.

Or E, Vilozny I, Fennell A, Eyal Y, Ogrodovitch A (2002). Dormancy in grape buds :isolation

and characterization of catalase cDNA and analysis of its expression following chemical

induction of bud dormancy release. Plant Sci 162:121

– 130.

Per ez FJ, Burgos B (2004) Alterations in the pattern of peroxidase isoenzymes and transient

increases in its activity and in H2O2 levels take place during the dormancy cycle of grapevines

buds: the effect of hydrogen cyanamide. Plant Growth Regul 43:213

– 220

USEPA 1998. Guidelines for Ecological Risk Assessment. EPA/630/R

- 95/002F. Published in

63 FR 26846; May 14, 1998. U.S. Environmental Protection Agency, Washington, DC. April,

1998.

USDA. 2000. USDA Crop Profiles. Hosted by the Integrated Pest Manageme nt Centers.

Available online at: http://www.ipmcenters.org/cropprofiles/index.cfm

.

USEPA. 2004. Overview of the Ecological Risk Assessment Process in the Office of Pesticid

Programs, U.S. E nvironmental Protection Agency. Endangered and Threatened Species Effects

Determinations. Office of Prevention, Pesticides and Toxic Substances, Office of Pesticide

Programs, Washington, D.C. January 23, 2004. Online

at: http://www.epa.gov/oppfead1/endanger/consultation/ecorisk

- overview.pdf

USEPA 2006a. Standardized Soil Mobility Classification Guidance. U.S. Environmental

Protection Agency, Office of Prevention, Pesticides and Toxic Substances, Office of

PesticidePrograms, Environmental Fate and Effects Division, Memorandum. Apr. 21, 2006.

USEPA. 2006b. User’s Guide: TerrPlant Version 1.2.2 (Terrestrial Residue Exposure model).

United States Environmental Protection Agency. Environmental Fate and Effects Division.

Office of Pesticide Programs. U.S. Environmental protection Agency. Washington, D.C.

December 26, 2006.- Page 66 of 115

- 

### USEPA. 2007. DRAFT: Registration Review: Problem Formulation for the Environmental Fate

and Ecological Risk, Endangered Species, and Drinking Water Exposure Assessments of

Hydrogen Cyanamide " 

### DP barcode 339286.

USEPA 2009. Guidance for Selecting Input Parameters in Modeling the Environmental Fate and

Transport of Pesticides. U.S. Environmental Protection Agency, Office of Prevention, Pesticides

and Toxic Substances, Office of Pesticide Programs, Environmental Fate and Effects Division,

Oct. 22, 2009. Online at:

http://www.epa.gov/oppefed1/models/water/input_parameter_guidance.htm

USEPA. 2011b. Water Models. U.S. Environmental Protection Agency, Pesticides: Science

and Policy, Models and Databases. Last updated Au g. 8, 2011. Online at:

http://www.epa.gov/oppefed1/models/water/

USFWS/NMFS. 2004. 50 CFR Part 402. Joint Counterpart Endangered Species Act Section

Consultation Regulations; Final Rule. FR 477 32

- 47762.

Urban, D.J. and N.J. Cook, 1986. Hazard Evaluation Division Standard Evaluation Procedure

Ecological Risk Assessment. EPA 540/9

- 85

- 001. U.S. Environmental Protection Agency,

Office of Pesticide Programs, Washington D.C.

6.1. Submitted Product Chemistry and Environmental Fate Studies



## 161

- 1 Hydrolysis

– 014002 Cyanamide Fate

MRID Citation Reference

00 148017 SKW Trostberg AG (1981) Behavior of the Pesticide Alzodef in

Water. Unpublished translation of Verhalten des

Pflanzenbehandlungs

- mittels Alzodef in Wasser. 11 p.



## 161

- 2 Photodegradation

- water

MRID Citation Reference

42178409 Schmidt, J. (1991) Determination of the Aqueous Photolysis Rate

of ?carbon 14|

- Cyanamide: Lab Project Number: 39035. Unpubli

shed study prepared by ABC Labs, Inc. 219 p.



## 162

- 1 Aerobic soil metabolism- Page 67 of 115

- MRID Citation Reference

00 148013 Crowther, E.; Richardson, H. (1932) The decomposition of calcium

cyanamide in the soil and its effects on germination, nitrifi

- cation

and soil reaction. J. Agric. Sci. 22:300

- 334.

00 148014 Nommik, H. (1958) On decomposition of calcium cyanamide and

dicya

- namide in the soil. Acta Agriculturae Scandinavica VIII(4):

404

- 440. Stockholm.

148016 Bosh, M.; Amberger, A. (1983) Einf luss langjaehriger duengung mit

verschiedenen N

- formen auf ph

- wert, humusfraktionen, biologi

sche aktivitaet und stickstoffdynamik einer acker

- braunerde

[Influence of long

- term fertilizing with different forms of Ni

- trogen

fertilizer on pH, humic fracti ons, biological activity and dynamics of

nitrogen of an arable brown earth]. Z. Pflanzen

- ernaehr. Bodenk.

146:714

- 724.

41566505 Schmidt, J. (1990) Preliminary Study of the Aerobic Soil

Metabolism of ?Carbon 14|

- Hydrogencyanamide: Lab Project

Number: 382 34. Unpublished study prepared by Analytical Bio

Chemistry Labora

- tories, Inc. 210 p.

42178410 Schmidt, J. (1990) Aerobic Soil Metabolism of ?carbon 14|

- Cyanamide: Lab Project Number: 38438. Unpublished study

prepared by ABC Labs, Inc. 376 p.

42178411 Schmidt, J. (1991) Supplemental Report of the Aerobic Soil

Metabolism of ?carbon 14|

- Cyanamide: Lab Project Number:

384381. Unpublished study prepared by ABC Labs, Inc. 71 p.

42211201 Schmidt, J. (1991) Supplemental Report of the Aerobic Soil

Me tabolism of ?carbon 14|

- Cyanamide: Final Supplemental

Report: Lab Project Number: 384381. Unpublished study prepared

by ABC Laboratories, Inc. 71 p.

42211202 Schmidt, J. (1990) Aerobic Soil Metabolism of ?carbon 14|

- Cyanamide: Final Report: Lab Project Number: 38438. Unpub

lished study prepared by Analytical Bio

- Chemistry Labs., Inc. 376

p.



## 162

- 2 Anaerobic soil metabolism

MRID Citation Reference

41390503 Pieters, P.; Scheepers , M. (1989) Biodegradation of Hydrogen

Cyan

- amide (H2NCN) in a Water/Sediment System: Lab Project

Number: 88

- 02053. Unpublished study prepared by BCO Analytical

Serv

- ices. 22 p.

42178412 Schmidt, J. (1990) Anaerobic Soil Metabolism of ?carbon 14|

-- Page 68 of 115

- Cyanamide: Lab Project Number: 38439. Unpublished study

prepared by ABC Labs, Inc. 286 p.

42178413 Schmidt, J. (1990) Supplemental Report of the Anaerobic Soil

Metabolism of ?carbon 14|

- Cyanamide: Lab Project Number:

384391. Unpublished study prepared by ABC Labs, Inc. 89 p.

42211203 Schmidt, J. (1991) Supplemental Report of the Anaerobic Soil

Metabolism of ?carbon 14|

- Cynanamide: Final Supplemental

Report: Lab Project Number: 384391. Unpublished study prepared

by ABC Labs., Inc. 89 p.



## 162

- 4 Aer obic aquatic metab.

MRID Citation Reference

45382202 Volkl, S. (2000) (Carbon 14)

- Cyanamide Route and Rate of

Degradation in Aerobic Aquatic Systems: Lab Project Number:

744952. Unpublished study prepared by RCC, Ltd. 177 p.



## 163

- 1 Leach/ adsorp/desorption

MRID Citation Reference

42178414 Rudel, H. (1990) Determination of the Adsorption/Desorption of

Hydrogencyanamide: Lab Project Number: SKW

- 01/7

- 13.

Unpublish

- ed study prepared by Fraunhofer

- Institut fur

Umweltichemie und Okotoxikol ogie. 38 p.

42178415 Rombke, J. (1990) Determination of the Soil Column Leaching of

Alzodef According to the BBA Guideline for the Testing of Plant

Protection Products Adopted December 1986: Lab Project

Number: BE

- EA

- 77

- 89

- 01

- LEA2. Unpublished study prepared by

Battelle Europe. 25 p.



## 164

- 1 Terrestrial field dissipation

MRID Citation Refe rence

148013 Crowther, E.; Richardson, H. (1932) The decomposition of calcium

cyanamide in the soil and its effects on germination, nitrifi

- cation

and soil reaction. J. Agric. Sci. 22:300

- 334.

148015 SKW Trostberg AG (1978) [Degradation of Hydrogen Cyanamide- Page 69 of 115

- in Seve

- ral Soils]. Unpublished translation of Modellversuche zum

Abbau des Herbiziden Wirkstoffs Cyanamid in Drei Verschiedenen

Boeden. 4 p.

148018 Amberger, A.; Niederbudde, E. (1977) Reaction of Calcium

C yanamide and Its Metabolites at Metal Oxides in Quartz Sand

and Soils. Unpublished translation of Umsetzung von Kalkstickstoff

und dessen Metaboliten an Metalloxiden in Quarzsand und Boeden

pre

- pared by SKW Trostberg and the University of Munich. 4 p.

4 2178416 Siemer, S. (1991) Field Dissipation of Hydrogen Cyanamide

(Dormex) in Soil. Unpublished study prepared by Siemer &

Associates, Inc. 457 p.



## 165

- 1 Confined rotational crop

MRID Citation Reference

45797401 Huang, M. (2002) Uptake of (Carbon 14)

- (Inert Ingredient)

Residues in Soil by Rotational Crops Under Flooded Confined

Conditions: Lab Project Number: 602CA. Unpublished study

prepared by Bayer CropScience. 28 p. {OPPTS 860.1850}



### NON Guideline

44804701 Kendall, T.; Nixon, W. (1998) Analytical Method Verification for the

Determination of Hydrogen Cyanamide Residues in Saltwater:

Final Report: Lab Project Number: 248C

- 101. Unpublished study

prepared by Wildlife International Ltd. 27 p.



### 6.2. Submitted Ecotoxicity Studies



## 71

- 1 Avian Single Dose Oral Toxicity

– 014002 Cyanamide Eco

MRID Citation Reference

153783 Robaidek , E. (1985) Avian Single

- dose Oral LD50 Bob White Quail

(Colinus virginianus) [Using Hydrogen Cyanamide]: Revised Final

Report: Study No. 6026

- 504. Unpublished study prepared by

Hazleton Laboratories America, Inc. 33 p.

153784 Robaidek , E. (1985) Avian Dietary LC50 Mallard Duck (Anas

platyrhynchos) [Using Hydrogen Cyanamide]: Final Report: Study

No. 6026

- 508. Unpublished study prepared by Hazleton Labora

-- Page 70 of 115

- tories America, Inc. 15 p.



## 71

- 2 Avian Dietary Toxicity

MRID Citation Refer ence

153785 Robaidek, E. (1985) Avian Dietary LC50 Bob White Quail (Colinus

virginianus) [Using Hydrogen Cyanamide]: Final Report: Study No.

6026

- 507. Unpublished study prepared by Hazleton Laboratories

America, Inc. 16 p.

42178401 Lynn, S.; Grimes, J.; Smith, G. (1991) Aqueous Hydrogen Cyana

mide Solution: A Dietary LC50 Study with the Mallard: Lab Project

Number: 248

- 105. Unpublished study prepared by Wild

- life

International Ltd. 19 p.

42178402 Lynn, S.; Grimes, J.; Smith, G. ( 1991) Aqueous Hydrogen

Cyanamide Solution: A Dietary LC50 Study with the Northern

Bobwhite: Lab Project Number: 248

- 104. Unpublished study

prepared by Wildlife International Ltd. 19 p.



## 71

- 4 Avian Reproduction

MRID Citation Reference

45797201 Johnson, A. (2001) Cyanamide 50% Solution Assessment to

Determine the Effects on Reproduction in the Bobwhite Quail: Lab

Project Number: STB 017/003921: STB/017. Unpublished study

prepared by Huntingdon Life Science, Ltd. 307 p.



## 72

- 1 Acute Toxicity to Freshwater Fish

MRID Citation Reference

148043 Barrows, B. (1985) The Acute Toxicity of Hydrogen Cyanamide to

the Rainbow Trout (

--- ), in a Static Test System: Project No. 85E

038RT. Unpublished study prepared by Biospherics Inc. 11 p.

148044 Riechenbach

- Klinke (1975) Research Report on the Fish Toxicity

of the Product Alzogur. Unpublished translation of Gutachten ueber

die Fischtoxizitaet des Praeparates Alzogur prepared by SKW

Trostberg AG and Institut fuer Zoologie und Hydrobiologie Fach

bereich Tiermedizin der Universitaet Muenchen. 4 p.- Page 71 of 115

- 153786 McAllister, W.; Bowman, J.; Cohle, P. (1985) Acute Toxicity of LH

21,810 A to Bluegill Sunfish (Lepomis macrochirus): Static Acute

Toxicity Report #33401. Unpublished study prepared by Anal yti

cal Bio

- Chemistry Laboratories, Inc. 54 p.



## 72

- 2 Acute Toxicity to Freshwater Invertebrates

MRID DOC NUM Citation Reference

148046 2026760 Adema, D. (1983) The Acute Toxicity of Alzodef to Daphnia

magna: Report No. R 83/198. Unpublished study prepared by

Netherlands Organization for Applied Scientific Research. 13 p.



## 72

- 3 Acute Toxicity to Estuarine/Marine Organisms

MRID Citation Reference

44804702 Gettmann, W.; Drottar , K.; Kruegar, H. (1998) Hydrogen

Cyanamide: A 96

- Hour Flow

- Through Acute Toxicity Test with the

Sheepshead Minnow (Cyprinodon variegatus): Final Report: Lab

Project Number: 248A

- 103. Unpublished study prepared by Wildlife

International Ltd. 41 p.

44804 703 Gettmann, W.; Drottar, K.; Kruegar, H. (1998) Hydrogen

Cyanamide: A 96

- Hour Flow

- Through Acute Toxicity Test with the

Saltwater Mysid (Mysidopsis bahia): Final Report: Lab Project

Number: 248A

- 102. Unpublished study prepared by Wildlife

International L td. 42 p.

44804704 Gettmann, W.; Drottar, K.; Kruegar, H. (1998) Hydrogen

Cyanamide: A 96

- Hour Shell Deposition Test with the Eastern

Oyster (Crassostrea virginica): Final Report: Lab Project Number:

248A

- 104. Unpublished study prepared by Wildlife Inter national

Ltd. 40 p.



## 72

- 4 Fish Early Life Stage/Aquatic Invertebrate Life Cycle Study

MRID Citation Reference

44076701 Rhodes, J.; O'Brien, K. (1995) Early Life

- Stage Toxicity of

Hydrogen Cyanamide to the Rainbow Trout (Oncorhynchus

mykiss) Under Flow

- Through Conditions: Final Report: Lab Project

Number: 41943: FIFRA 72

- 4 RBT. Unpublished study prepared by

ABC Labs., Inc. 297 p.- Page 72 of 115

- 44076702 Murrell, H.; Leak, T. (1995) Chronic Toxicity of Hydrogen

Cyanamide to Daphnia magna Under Flow

- Through Test

Conditions: Final Report: Lab Project Number: 41942: ABC 41942:

FIFRA E

- 72

- 4

- B. Unpublished study prepared by ABC Labs., Inc.

121 p.



## 122

- 1 Seed Germination/Seedline Emergence and Vegetable Vigor

MRID Citation Reference

45380701 Meister, A. (2000) Effects of Cyanamide L 500 on the Vegetative

Nontarget Plant Species: Tier I: Vegetative Vigor Limit Test: Final

Report: Lab Project Number: 7042087: 851

- 002. Unpublished

study prepared by Institut fur Biologische Analytik und Consulting

IBACON GmbH. 64 p. {OPPTS 850.4150}

45380702 Meister, A. (2000) Effects of Cyanamide L 500 on the Seedling

Emergence of Nontarget Plant Species: Tier I: Seedling

Emergence Limit Test: Final Report: Lab Project Number:

7041086: 851

- 001. Unpublished study prepared by Institut fur

Biologische Analytik und Consulting IBACON GmbH. 89 p.

{OPPTS 850.4100}



## 122

- 2 Aquatic plant growth

MRID Citation Reference

40380101 Siemer, S. (1986) 1985 Residue Studies Conducted on Grapes

with Dormant Applications of Dormex . Unpublished compilation

pre

- pared by SKW Trostberg AG. 86 p.

45382201 Hertl , J. (2000) Toxicity of SKW Cyanamide L 500 to Anabaena

flos

- aquae in an Algal Growth Inhibition Test: Final Report: Lab

Project Number: 6677210. Unpublished study prepared by Institut

fur Biologische Analytik und Consulting IBACON GmbH. 78 p.

45406601 S eyfried, B. (2000) Toxicity of Cyanamide L 500 to

Pseudokirchneriella subcapitata (Formerly Selenastrum

capricornutum) in a 96

- Hour Algal Growth Inhibition Test: Lab

Project Number: 744963. Unpublished study prepared by RCC Ltd.

76 p. {OPPTS 850.5400}

45 406602 Hertl, J. (2000) Toxicity of SKW Cyanamide L 500 to the Aquatic

Plant Lemna gibba in a Growth Inhibition Test: Final Report: Lab

Project Number: 6679240. Unpublished study prepared by Institut

fur Biologische Analytik und Consulting IBACON GmbH. 76 p.

{OPPTS 850.4400}- Page 73 of 115

- 

## 141

- 1 Honey bee acute contact

MRID Citation Reference

43866902 Atkins, E. (1989) Bee Adult Toxicity Dusting Test: (Dormex 4.0 SL):

Lab Project Number: 492. Unpublished study prepared by

University of California, Riverside. 26 p.- Page 74 of 115

- 

## Appendix A

. Submitted Ecological Effects Data for Hydrogen Cyanamide

Table A .1 . Submitted Terrestrial Ecological Effects Data for Hydrogen Cyanamide

OCSPP

Guideline Data

Requirement Submitted

Studies

(MRID) Study

Classifications Are Data

Needed for

Risk

Assessment? Current Additional Data Need

850.2100 Avian oral

toxicity 00153783 Acceptable Yes Acceptable acute avian acute oral

toxicity data were not submitted for a

passerine species, which is now

required under the 40 CFR Part 158

data requirements. Though the

available data indicates hydrogen

cyanamide has low toxicity to avian

species, the cur rently registered

application rates are sufficiently high

to trigger concern. In addition,

passerine species may be more or less

sensitive to this chemical as a result

of their higher metabolic rate and

differing metabolic pathways. An

avian oral toxicity study is needed for

a passerine species. A passerine study

protocol must be submitted for

review by the Agency prior to

initiation of the study.

850.2200 Avian dietary

toxicity 42178402 Acceptable No

--

42178402 Acceptable

850.2300 Avian

reproduction 45797201 Supplemental Yes Avian reproduction studies should be

conducted with an upland game bird

species and a waterfowl species as

required under the 40 CFR Part 158.

Reproduction data are needed for a

waterfowl species

.

850.3020 Honey bee

acute contact

toxicity 43866902 Acceptable No

--

850.3030 Honey bee

residue on

foliage (None) (N/A) No

--

850.3040 Field testing

for pollinators (None) (N/A) No

--

850.4100 Terrestrial

p lant toxicity:

Tier I and II

seedling

emergence 45380702

48404301 Supplemental No

--- Page 75 of 115

- Table A .1 . Submitted Terrestrial Ecological Effects Data for Hydrogen Cyanamide

OCSPP

Guideline Data

Requirement Submitted

Studies

(MRID) Study

Classifications Are Data

Needed for

Risk

Assessment? Current Additional Data Need

850.4150 Terrestrial

p lant toxicity:

Tier I and II

vegetative

vigor 48404302 Supplemental No

--

Table A .2 . Submitted Aquatic Ecological Effects Data for Hydrogen Cyanamide

OCSPP

Guideline Data

Requirement Submitted

Studies

(MRID) Study

Classifications Are Data

Needed for Risk

Assessment? Justification and Assumptions

EPA will Make in Absence of

Data

850.1010 Freshwater

invertebrate

acute toxicity 00148046 Acceptable No

--

850.1025

850.1035 Estuarine/Marine

invertebrate

acute toxicity 44804704 Acceptable No

--

44804703 Acceptable

850.1075 Freshwater fish

acute toxicity 00148043 Acceptable No

--

00153786

850.1075 Estuarine/Marine

fish acute

toxicity 44804702 Acceptable No

--

850.1300 Freshwater

invertebrate

life cycle 44706702 Acceptable No

--

850.1350 Estuarine/Marine

invertebrates

life cycle (None) (N/A) Yes The proposed uses of hydrogen

cyanamide may result in exposure

to estuarine/marine invertebrates.

An ACR is not appropriate because

the freshwater acute and chronic

data are based on the daphnid,

which does not have a similar life

history to the most sensi tive

estuarine/marine invertebrate

species studied in the acute test ( i.e.,

eastern oyster). While hydrogen

cyanamide is only moderately toxic

to estuarine/marine invertebrates

based on acute exposure, the

proposed application rates are

sufficiently high t o potentially

trigger concerns. Therefore this

study is requested to reduce the

uncertainty.

850.1400 Freshwater fish

early

- life stage 44076701 Supplemental No

--- Page 76 of 115

- Table A .2 . Submitted Aquatic Ecological Effects Data for Hydrogen Cyanamide

OCSPP

Guideline Data

Requirement Submitted

Studies

(MRID) Study

Classifications Are Data

Needed for Risk

Assessment? Justification and Assumptions

EPA will Make in Absence of

Data

850.1400 Estuarine/Marine

fish

early

- life stage (None) (N/A) Yes While this data is not currently

available, and an ACR from the

freshwater fish species is not

possible because only a non

definitive endpoint is available, risk

to estuarine/marine fish is expected

to be low. This information would

be useful for reducing uncertainties

but will not likely change the risk

conclusions.

850.1500 Fish life cycle (None) (N/A) No

--

850.4400 Aquatic plant

g rowth:

Tier II vascular

plants 45406602 Acceptable No

--

850.5400 Aquatic Plant

Growth:

Tier II algae 45382201 Supplemental Yes

--

45406601 Supplemental- Page 77 of 115

- 

### Appendix B . Catalogue of Submitted Environmental Fate Studies for Hydrogen

cyanamide

.

Submitted Environmental Fate Studies for Hydrogen cyanamide , their Review Classifications,

and Classification Justifications.

Guideline Study Title MRID Classification Comments Are data

adequate for

Risk

Assessment? Current Additional

Data Need

835.2120 Hydrolysis 48023547 Acceptable Study was conducted at 50oC.

Hydrogen cyanamide was stable at

pHs 4, 7, and 9. Yes None

835.2240 Photodegradation

in Water 48023548 Supplemental Study duration was not sufficient. A

large amount of parent remained

undegraded at the termination of the

study. Half

- lives are of uncertain

value.

Yes An acceptable aqueous

photolysis study

conducted for a

sufficient duration is

recommended to

confirm the results

reported from the

reviewed studies. Photodegradation

in River Water 48023549 Supplemental Study duration was not sufficient. A

large amount of parent remained

undegraded at the termination of the

study. Half

- lives are of uncertain

value.

Quantum Yield

of Hydrogen

cyanamide 48023550 Supplemental Dark controls were not used.

Irradiation lamp was not compared to

natural sunlight (mercury vapor lamp

was used).

835.2410 Photodegradation

on Soil -- -- Study not required since this is a seed

treatment. -- --

835.4100 Aerobic Soil

Metabolism 48023552 Supplemental German soils. Study duration was not

sufficient to characterize the

degradation of the parent and

formation and decline of major

degradates. Half

- lives were

extrapolated beyond the study

duration and thus are of uncertain

value. Comparison to intended use

sites in the US was not provided.

Yes An acceptable aerobic

soil metabolism study

conducted for a

sufficient duration to

characterize the decline

of the parent and

formation and decline

of major degradates is

recommended to

reduce the uncertainty

regarding the aerobic

degradation of

hydrogen cyanamide 48023553 Supplemental US soils. Study duration was

insufficient to completely

characterize the degradation of the

parent and formation and decline of

major degradates.

48023554 Supplemental Study was conducted using a

hydrogen cyanamide

- pyrazolyl

- AAP

as the starting material. Extraction

methods were not exhaustive,

multiple extraction methods should

have been explored. Major

degradates were not identified.

Comparison to intended use sites in

the US was not provided.- Page 78 of 115

- Guideline Study Title MRID Classification Comments Are data

adequate for

Risk

Assessment? Current Additional

Data Need

835.4200 Anaerobic Soil

Metabolism 48023555 Acceptable A large amount of parent material

remained undegraded at the study

termination (70

- 74%). Half

- lives are

extrapolated beyond the duration of

the study. An additional study

conducted for a longer duration will

not likely improve the results.

German soils were used in the study

and were not compared to intended

use sites in the US. No None

835.4300 Aerobic Aquatic

Metabolism 48023556 Supplemental Unexplained variability in the

reported data (uncharacterized

decline of the parent and major

degradates). Anglerweiher

water:sand system should not be used

for risk assessment. Hoenniger

Weiher water :sandy loam system is

acceptable for risk assessment. Yes An additional

acceptable aerobic

aquatic study that

includes a different

water: sediment system

is recommended to

address the p otential

variability that exists

between multiple

aquatic systems.

835.4400 Anaerobic

Aquatic

Metabolism 48023557 Supplemental A large amount of parent material

remained undegraded at the study

termination (86

- 90%; 120 DAT).

Hydrogen cyanamide was just

beginning to dissipate from the

sediment; a study conducted for a

sufficient determination may

determine whether hydrogen

cyanamide was in fact dissipating

from the sediment. Half

- live are

extrapolated and are of uncertain

value. System was only moderately

reducing. Only a single

water:sediment system was studied. Yes Two water:sediment

systems are

recommended from

studies conducted for a

sufficient duration to

reduce the uncertainty

regarding the anaerobic

degradation. However,

it is unlikely that

additional studies

would produce

significantly different

results.

835.1230 Mobility

- Adsorption /

Desorption 48023546 Supplemental Residues were not accounted for in

the intercalated solution in the initial

adsorption step and each desorption

step. Registrant

- calculated percent

adsorption values could not be

confirmed due to lack of raw da ta.

None of the test soils had OM

content < 1%. Foreign soils were used

for the study, comparison

information to intended US use sites

was not provided.

Yes An acceptable

adsorption/desorption

study is recommended

to address uncertainties

identified in the study

reviews.

48023544 Supplemental Study was conducted using a major

transformation product ( hydrogen

cyanamide

- hydroxy butyl).

Registrant

- calculated percent

adsorption values could not be

confirmed due to lack of raw data.

None of the test soils had an OM

content < 1%. Foreign soils were used

for the study, comparison

information to intended US use sites

was not pr ovided.- Page 79 of 115

- Guideline Study Title MRID Classification Comments Are data

adequate for

Risk

Assessment? Current Additional

Data Need

48023545 Supplemental Study was conducted using a major

transformation product ( hydrogen

cyanamide

- pyrazolyl

- AAP).

Registrant

- calculated percent

adsorption values could not be

confirmed due to lack of raw data.

None of the test soils had an OM

content < 1%. Foreign soils were used

for the study, comparison

information to intended US use sites

was not pr ovided.

835.6100 Terrestrial Field

Dissipation 48023558 Unacceptable Reported dissipation half

- lives are

comparatively shorter than other field

studies (orders of magnitude).

Additional dissipation routes (e.g.,

runoff) were not measured, therefore

there is some other dissipation route

occurring that has not been accounted

for. Exhaustive extraction methods

were not investigated. Depth of

sampling was insufficient.

Yes An acceptable

terrestrial field

dissipation study that

studies the proposed

use pa tterns (seed

treatment) is

recommended to

address the

uncertainties identified

in the study reviews. 48023559 Supplemental Test application rate was conducted

at an exaggerated rate (10x proposed

maximum labeled rate). Exhaustive

extraction methods were not

investigated. Depth of sampling was

insufficient.

48023560 Supplemental Test application rate was conducted

at an exaggerated rate (10x proposed

maximum labeled rate). Exhaustive

extraction methods were not

investigated. Depth of sampling was

insufficient. Reported LOQ did not

compare to validated LOQ.

48023561 Supplemental Test application rate was conducted

at an exaggerated rate (10x proposed

maximum labeled rate). Exhaustive

extraction methods were not

investigated. Reported LOQ did not

compare to validated LOQ.

48023562 Supplemental Test application rate was conducted

at an exaggerated rate (10x proposed

maximum labeled rate). Exhaustive

extraction methods were not

investigated. Reported LOQ did not

compare to validated LOQ.

48023563 Supplemental Test application rate was conducted

at an exaggerated rate. Exhaustive

extraction methods were not

investigated. Reported LOQ did not

compare to validated LOQ.- Page 80 of 115

- Guideline Study Title MRID Classification Comments Are data

adequate for

Risk

Assessment? Current Additional

Data Need

48023564 Supplemental Study was conducted in ecoregions

dissimilar to the intended use sites in

the US. Comparisons to intended use

sites in the US were not provided.

Application rates were not verified

using data from the monitoring

devices (e.g., filter paper).

835.6200 Aquatic Field

Dissipation 48023565 Supplemental Test application rate was conducted

at an exaggerated rate. Exhaustive

extraction methods were not

investigated. Reported LOQ did not

compare to validated LOQ. Study

was conducted on rice. Plant samples

were analyzed for parent and

degradates . Hydroxy butyl and a

carboxylic acid degradate were

detected in plant samples at low

levels. Storage stability was not

demonstrated for the longest storage

period (MRID 48023722) Yes Although not required

for current action,

future actions with

aquatic us es would

require a second study

in an aquatic system.

850.1730 Fish

Accumulation 48023589 Acceptable Low BCFs indicate that hydrogen

cyanamide will not bioconcentrate in

aquatic food webs. Mean TRR values

were used in the calculation of BCFs.

EPA typically uses maximum TRR

values from whole fish, edible, and

viscera tissues when calculating

BCFs, however mean TRR values do

not change the conclusions that

would be drawn by using maximum

values. Yes None

860.1380 Storage stability

in soil 48023719

48176601 Acceptable Initial study MRID 48176601was not

conducted for sufficient duration.

Together these two studies satisfy the

guideline requirement.

Yes None

Storage Stability 48023722 Supplemental Study duration was insufficient.

Stability was demonstrated through

222 days, however it should have

been conducted for at least as long as

the longest storage period (362 days). An acceptable storage

stability study in water

conducted for a

sufficient duration,

using water from the

aquatic field

dissipation study.- Page 81 of 115

- 

## Appendix C . PE5 Output File

stored as HcyanamideORapples.out

Chemical: Hcyanamide

PRZM environment: ORappleSTD.txt modified Tueday, 29 May 2007 at 14:00:08

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

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

Water segment concentrations (ppb)

Year Peak 96 hr 21 Day 60 Day 90 Day Yearly

1961 24. 57 22.69 18.22 10.32 7.339 1.843

1962 2.74 2.631 2.054 1.244 0.8947 0.2255

1963 0.985 0.9051 0.6488 0.3615 0.2583 0.06491

1964 0.985 0.9252 0.7195 0.4323 0.3115 0.07825

1965 0.985 0.9179 0.693 0.3973 0.282 0.07079

1966 0.985 0.9233 0.7442 0.4453 0.3181 0.0 798

1967 0.985 0.9191 0.8011 0.5014 0.3661 0.0926

1968 13.75 12.64 9.089 4.983 3.531 0.8835

1969 12.36 11.81 9.633 5.841 4.174 1.045

1970 26.51 24.58 18.25 10.4 7.457 1.877

1971 71.64 67.33 52.47 31.82 23.06 5.825

1972 0.9863 0.9194 0.6948 0.3966 0.283 0.07106

1973 0.985 0.917 0.6898 0.399 0.2849 0.07146

1974 3.441 3.223 2.569 1.525 1.09 0.2741

1975 1.136 1.064 0.8905 0.5362 0.3882 0.09799

1976 0.985 0.9248 0.7218 0.4377 0.3166 0.0797

1977 0.985 0.9144 0.6809 0.3914 0.2785 0.06994

1978 7.684 7.116 5.34 3 .04 2.16 0.5414

1979 32.41 30.98 23.6 13.24 9.334 2.334

1980 0.9854 0.9174 0.6944 0.4042 0.2881 0.07216

1981 1.048 0.9765 0.848 0.5234 0.3737 0.09378

1982 2.808 2.684 2.06 1.262 0.9263 0.2341

1983 39.02 37.14 29.07 16.07 11.32 2.831

1984 1.709 1.614 1.222 0.7621 0.5457 0.1371

1985 15.3 14.67 11.54 6.919 4.958 1.247

1986 0.9853 0.9162 0.7981 0.4629 0.3273 0.08198

1987 1.08 1.02 0.872 0.5308 0.3766 0.09412

1988 0.985 0.9179 0.6929 0.3988 0.2832 0.07082

1989 0.985 0.9346 0.7679 0.4731 0.3357 0.08392

1990 15.32 14.66 11.56 6.684 4.717 1.179

Sorted results

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

0.032258064516129 71.64 67.33 52.47 31.82 23.06 5.825

0.0645161290322581 39.02 37.14 29.07 16.07 11.32 2.831

0.0967741935483871 32.41 30.98 23.6 13.24 9.334 2.334

0.129032258064516 26.51 24.58 18.25 10.4 7.457 1.877

0.161290322580645 24.57 22.69 18.22 10.32 7.339 1.843

0.193548387096774 15.32 14.67 11.56 6.919 4.958 1.247

0.225806451612903 15.3 14.66 11.54 6.684 4.717 1.179

0.258064516129032 13.75 12.64 9.633 5.841 4.174 1.045- Page 82 of 115

- 0.290322580645161 12.36 11.81 9.089 4.983 3.531 0.8835

0.32258064516129 7.684 7.116 5.34 3.04 2.16 0.5414

0.354838709677419 3.441 3.223 2.569 1.525 1.09 0.2741

0.387096774193548 2.808 2.684 2.06 1.262 0.9263 0.2341

0.419354838709677 2.74 2.631 2.054 1.244 0.8947 0.2255

0.451612903225806 1.709 1.614 1.222 0.7621 0.5457 0.1371

0.483870967741936 1.136 1.064 0.8905 0.5362 0.3882 0.09799

0.516129032258065 1.08 1.02 0.872 0.5308 0.3766 0.09412

0.548387096774194 1.048 0.9765 0.848 0.5234 0.3737 0.09378

0.580645161290323 0.9863 0.9346 0.8011 0.5014 0.3661 0.0926

0.612903225806452 0.9854 0.9252 0.7981 0.4731 0.3357 0.08392

0.645161290322581 0.9853 0.9248 0.7679 0.4629 0.3273 0.08198

0.67741935483871 0.985 0.9233 0.7442 0.4453 0.3181 0.0798

0.7096774193548 39 0.985 0.9194 0.7218 0.4377 0.3166 0.0797

0.741935483870968 0.985 0.9191 0.7195 0.4323 0.3115 0.07825

0.774193548387097 0.985 0.9179 0.6948 0.4042 0.2881 0.07216

0.806451612903226 0.985 0.9179 0.6944 0.399 0.2849 0.07146

0.838709677419355 0.985 0.9174 0. 693 0.3988 0.2832 0.07106

0.870967741935484 0.985 0.917 0.6929 0.3973 0.283 0.07082

0.903225806451613 0.985 0.9162 0.6898 0.3966 0.282 0.07079

0.935483870967742 0.985 0.9144 0.6809 0.3914 0.2785 0.06994

0.967741935483871 0.985 0.9051 0.6488 0.3615 0.2583 0 .06491

0.1 31.82 30.34 23.065 12.956 9.1463 2.2883

Average of yearly averages: 0.724999333333333

Inputs generated by pe5.pl

- Novemeber 2006

Data used for this run:

Output File: HcyanamideORapples

Metfile: w24232.dvf

PRZM scenario: ORappleSTD.txt

EXAMS environment file: pond298.exv

Chemical Name: Hcyanamide

Description Variable Name Value Units Comments

Molecular weight mwt 42.04 g/mol

Henry's Law Const. henry 2.68E

- 10 atm

- m^3/mol

Vapor Pressure vapr 0.00375 torr

Solubility sol 7.8E5 mg/L

Kd Kd m g/L

Koc Koc 7.3 mg/L

Photolysis half

- life kdp 29 days Half

- life

Aerobic Aquatic Metabolism kbacw 5.28 days Halfife

Anaerobic Aquatic Metabolism kbacs 70 days Halfife

Aerobic Soil Metabolism asm 1.5 days Halfife

Hydrolysis: pH 7 0 days Half

- life

Method: CAM 2 integer See PRZM manual

Incorporation Depth: DEPI 0 cm

Application Rate: TAPP 19.7 kg/ha

Application Efficiency: APPEFF 0.99 fraction

Spray Drift DRFT 0.001 fraction of application rate applied to pond

Application Date Date 04

- 02 dd/mm or dd/mmm or dd

- mm or dd

- mmm

Record 17: FILTRA

IPSCND 1

UPTKF

Record 18: PLVKRT- Page 83 of 115

- PLDKRT

FEXTRC 0.5

Flag for Index Res. Run IR EPA Pond

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

stored as HcyanamidePAapples.out

Chemical: H cyanamide

PRZM environment: PAappleSTD_V2.txt modified Tueday, 20 May 2008 at 13:00:22

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

Metfile: w14751.dvf modified Wedday, 3 July 2002 at 09:06:14

Water segment concentrations (ppb )

Year Peak 96 hr 21 Day 60 Day 90 Day Yearly

1961 1.897 1.821 1.507 0.9318 0.6663 0.1661

1962 4.35 4.243 3.428 2.076 1.471 0.365

1963 1.229 1.173 0.9529 0.5592 0.3902 0.09679

1964 0.985 0.9401 0.7635 0.4636 0.3283 0.08124

1965 0.985 0.9401 0.8334 0.5313 0.3772 0.09353

1966 2.673 2.589 2.108 1.263 0.8978 0.2231

1967 0.985 0.9402 0.7949 0.5042 0.3573 0.08903

1968 0.985 0.9401 0.7537 0.4365 0.3052 0.07563

1969 0.985 0.9378 0.756 0.4593 0.3217 0.07976

1970 0.985 0.9401 0.7681 0.4815 0.3407 0.08451

1971 15.66 14.96 12.02 7.473 5.314 1.322

1972 0.9852 0.9404 0.7623 0.4637 0.3293 0.08169

1973 0.985 0.9401 0.7467 0.4287 0.3017 0.07505

1974 1.903 1.816 1.436 0.8534 0.5931 0.147

1975 2.743 2.615 2.123 1.342 0.9633 0.2394

1976 0.985 0.9269 0.7153 0.4088 0.2849 0.0705 1

1977 13.97 13.48 10.28 5.679 3.965 0.9828

1978 0.9852 0.9403 0.762 0.4647 0.3279 0.08147

1979 12.74 12.31 9.581 5.391 3.79 0.9411

1980 3.586 3.423 2.743 1.644 1.154 0.2854

1981 153 146 119 71.03 49.59 12.3

1982 0.9877 0.9428 0.7663 0.4763 0.3406 0.08526

1983 0.985 0.9518 0.7781 0.4597 0.3257 0.08108

1984 13.73 13.15 10.71 6.868 4.94 1.23

1985 8.905 8.499 6.844 4.015 2.822 0.7012

1986 8.227 7.853 6.237 3.632 2.554 0.6335

1987 7.018 6.698 5.25 3.03 2.137 0.5302

1988 0.9851 0.9402 0.7606 0.4512 0.3188 0.0789 8

1989 6.937 6.714 5.396 3.228 2.284 0.568

1990 18.97 17.88 13.56 7.584 5.301 1.317

Sorted results

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

0.032258064516129 153 146 119 71.03 49.59 12.3

0.0645161290322581 18.97 17.88 13.56 7.584 5.314 1.322

0.0967741935483871 15.66 14.96 12.02 7.473 5.301 1.317

0.129032258064516 13.97 13.48 10.71 6.868 4.94 1.23

0.161290322580645 13.73 13.15 10.28 5.679 3.965 0.9828

0.193548387096774 12.74 12.31 9.581 5.391 3.79 0.9411- Page 84 of 115

- 0.225806451612903 8.905 8.499 6.844 4.01 5 2.822 0.7012

0.258064516129032 8.227 7.853 6.237 3.632 2.554 0.6335

0.290322580645161 7.018 6.714 5.396 3.228 2.284 0.568

0.32258064516129 6.937 6.698 5.25 3.03 2.137 0.5302

0.354838709677419 4.35 4.243 3.428 2.076 1.471 0.365

0.387096774193548 3.586 3.4 23 2.743 1.644 1.154 0.2854

0.419354838709677 2.743 2.615 2.123 1.342 0.9633 0.2394

0.451612903225806 2.673 2.589 2.108 1.263 0.8978 0.2231

0.483870967741936 1.903 1.821 1.507 0.9318 0.6663 0.1661

0.516129032258065 1.897 1.816 1.436 0.8534 0.5931 0.147

0.5 48387096774194 1.229 1.173 0.9529 0.5592 0.3902 0.09679

0.580645161290323 0.9877 0.9518 0.8334 0.5313 0.3772 0.09353

0.612903225806452 0.9852 0.9428 0.7949 0.5042 0.3573 0.08903

0.645161290322581 0.9852 0.9404 0.7781 0.4815 0.3407 0.08526

0.67741935483871 0.9851 0.9403 0.7681 0.4763 0.3406 0.08451

0.709677419354839 0.985 0.9402 0.7663 0.4647 0.3293 0.08169

0.741935483870968 0.985 0.9402 0.7635 0.4637 0.3283 0.08147

0.774193548387097 0.985 0.9401 0.7623 0.4636 0.3279 0.08124

0.806451612903226 0.985 0.9401 0. 762 0.4597 0.3257 0.08108

0.838709677419355 0.985 0.9401 0.7606 0.4593 0.3217 0.07976

0.870967741935484 0.985 0.9401 0.756 0.4512 0.3188 0.07898

0.903225806451613 0.985 0.9401 0.7537 0.4365 0.3052 0.07563

0.935483870967742 0.985 0.9378 0.7467 0.4287 0.3017 0.07505

0.967741935483871 0.985 0.9269 0.7153 0.4088 0.2849 0.07051

0.1 15.491 14.812 11.889 7.4125 5.2649 1.3083

Average of yearly averages: 0.770211

Inputs generated by pe5.pl

- Novemeber 2006

Data used for this run:

Output File: HcyanamidePAapples

Metfile: w14751.dvf

PRZM scenario: PAappleSTD_V2.txt

EXAMS environment file: pond298.exv

Chemical Name: Hcyanamide

Description Variable Name Value Units Comments

Molecular weight mwt 42.04 g/mol

Henry's Law Const. henry 2.68E

- 10 atm

- m^3/ mol

Vapor Pressure vapr 0.00375 torr

Solubility sol 7.8E5 mg/L

Kd Kd mg/L

Koc Koc 7.3 mg/L

Photolysis half

- life kdp 29 days Half

- life

Aerobic Aquatic Metabolism kbacw 5.28 days Halfife

Anaerobic Aquatic Metabolism kbacs 70 days Halfife

Aerobic Soil Metabo lism asm 1.5 days Halfife

Hydrolysis: pH 7 0 days Half

- life

Method: CAM 2 integer See PRZM manual

Incorporation Depth: DEPI 0 cm

Application Rate: TAPP 19.7 kg/ha

Application Efficiency: APPEFF 0.99 fraction

Spray Drift DRFT 0.001 fraction of application rate applied to pond

Application Date Date 20

- 02 dd/mm or dd/mmm or dd

- mm or dd

- mmm

Record 17: FILTRA

IPSCND 1- Page 85 of 115

- UPTKF

Record 18: PLVKRT

PLDKRT

FEXTRC 0.5

Flag for Index Res. Run IR EPA Pond

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

stored as HcyanamideNCapples2.out

Chemical: Hcyanamide

PRZM environment: NCappleSTD.txt modified Tueday, 29 May 2007 at 13:58:16

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

Metfile: w03812.dvf mod ified Wedday, 3 July 2002 at 09:05:50

Water segment concentrations (ppb)

Year Peak 96 hr 21 Day 60 Day 90 Day Yearly

1965 14.17 13.25 10.61 6.496 4.62 1.151

1966 2.026 1.971 1.623 1.046 0.7592 0.1904

1967 0.985 0.9361 0.7685 0.465 0.3262 0.08116

1968 0.985 0.9401 0.7776 0.4846 0.3441 0.08558

1969 4.465 4.221 3.362 2.095 1.508 0.3759

1970 0.9851 0.9273 0.738 0.4424 0.3116 0.07748

1971 10.39 9.851 7.777 4.686 3.332 0.8305

1972 1.85 1.747 1.386 0.89 0.6359 0.1583

1973 0.985 0.9303 0.7868 0.4659 0.327 0.08 143

1974 0.985 0.9244 0.7945 0.4593 0.3214 0.07987

1975 0.985 0.9203 0.7036 0.4126 0.2925 0.0728

1976 0.985 0.9118 0.6889 0.3891 0.2719 0.06746

1977 0.985 0.9306 0.74 0.429 0.2987 0.07412

1978 0.985 0.9394 0.7745 0.4817 0.3408 0.08484

1979 0.985 0.9342 0.7 539 0.4453 0.3118 0.07746

1980 0.985 0.935 0.7569 0.4638 0.3279 0.08131

1981 12.01 11.29 8.807 5.157 3.638 0.9058

1982 2.589 2.429 1.896 1.126 0.7992 0.1989

1983 8.51 8.017 6.827 4.107 2.939 0.7345

1984 3.449 3.241 2.519 1.539 1.124 0.2814

1985 6.614 6.244 4.939 2.813 1.998 0.4976

1986 0.9851 0.9214 0.7084 0.4131 0.2906 0.07226

1987 0.985 0.9287 0.7329 0.4383 0.3114 0.07754

1988 0.985 0.9314 0.7431 0.4462 0.3156 0.07844

1989 0.985 0.9259 0.7234 0.4163 0.2919 0.07269

1990 6.634 6.325 5.204 3.002 2.134 0.5317

Sorted results

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

0.037037037037037 14.17 13.25 10.61 6.496 4.62 1.151

0.0740740740740741 12.01 11.29 8.807 5.157 3.638 0.9058

0.111111111111111 10.39 9.851 7.777 4.686 3.332 0.8305

0.148148148148148 8.51 8.017 6.827 4.107 2.939 0.7345

0.185185185185185 6.634 6.325 5.204 3.002 2.134 0.5317- Page 86 of 115

- 0.222222222222222 6.614 6.244 4.939 2.813 1.998 0.4976

0.259259259259259 4.465 4.221 3.362 2.095 1.508 0.3759

0.296296296296296 3.449 3.241 2.519 1.539 1.124 0.2814

0.333333333 333333 2.589 2.429 1.896 1.126 0.7992 0.1989

0.37037037037037 2.026 1.971 1.623 1.046 0.7592 0.1904

0.407407407407407 1.85 1.747 1.386 0.89 0.6359 0.1583

0.444444444444444 0.9851 0.9401 0.7945 0.4846 0.3441 0.08558

0.481481481481481 0.9851 0.9394 0.7868 0. 4817 0.3408 0.08484

0.518518518518518 0.985 0.9361 0.7776 0.4659 0.3279 0.08143

0.555555555555556 0.985 0.935 0.7745 0.465 0.327 0.08131

0.592592592592593 0.985 0.9342 0.7685 0.4638 0.3262 0.08116

0.62962962962963 0.985 0.9314 0.7569 0.4593 0.3214 0.07987

0.666666666666667 0.985 0.9306 0.7539 0.4462 0.3156 0.07844

0.703703703703704 0.985 0.9303 0.7431 0.4453 0.3118 0.07754

0.740740740740741 0.985 0.9287 0.74 0.4424 0.3116 0.07748

0.777777777777778 0.985 0.9273 0.738 0.4383 0.3114 0.07746

0.814814814814815 0 .985 0.9259 0.7329 0.429 0.2987 0.07412

0.851851851851852 0.985 0.9244 0.7234 0.4163 0.2925 0.0728

0.888888888888889 0.985 0.9214 0.7084 0.4131 0.2919 0.07269

0.925925925925926 0.985 0.9203 0.7036 0.4126 0.2906 0.07226

0.962962962962963 0.985 0.9118 0.6889 0.3891 0.2719 0.06746

0.1 10.876 10.2827 8.086 4.8273 3.4238 0.85309

Average of yearly averages: 0.270016923076923

Inputs generated by pe5.pl

- Novemeber 2006

Data used for this run:

Output File: HcyanamideNCapples2

Metfile: w03812.dvf

PRZM scenario: NCappleSTD.txt

EXAMS environment file: pond298.exv

Chemical Name: Hcyanamide

Description Variable Name Value Units Comments

Molecular weight mwt 42.04 g/mol

Henry's Law Const. henry 2.68E

- 10 atm

- m^3/mol

Vapor Pressure vapr 0.00375 torr

Solubility sol 7.8E5 mg/L

Kd Kd mg/L

Koc Koc 7.3 mg/L

Photolysis half

- life kdp 29 days Half

- life

Aerobic Aquatic Metabolism kbacw 5.28 days Halfife

Anaerobic Aquatic Metabolism kbacs 70 days Halfife

Aerobic Soil Metabolism asm 1.5 days Halfife

Hydrolysis: pH 7 0 da ys Half

- life

Method: CAM 2 integer See PRZM manual

Incorporation Depth: DEPI 0 cm

Application Rate: TAPP 19.7 kg/ha

Application Efficiency: APPEFF 0.99 fraction

Spray Drift DRFT 0.001 fraction of application rate applied to pond

Application Date Date 04

- 02 dd/mm or dd/mmm or dd

- mm or dd

- mmm

Record 17: FILTRA

IPSCND 1

UPTKF

Record 18: PLVKRT

PLDKRT- Page 87 of 115

- FEXTRC 0.5

Flag for Index Res. Run IR EPA Pond

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

stored as HcyanamideFLb lueberries.out

Chemical: Hcyanamide

PRZM environment: GAPeachesSTD.txt modified Tueday, 29 May 2007 at 13:54:56

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

Metfile: w03813.dvf modified Wedday, 3 July 2002 at 09:04:32

Water se gment concentrations (ppb)

Year Peak 96 hr 21 Day 60 Day 90 Day Yearly

1961 0.985 0.8803 0.6695 0.2939 0.1959 0.04831

1962 0.985 0.9137 0.6783 0.2988 0.1992 0.06701

1963 0.985 0.9237 0.757 0.3469 0.2313 0.07919

1964 0.985 0.9194 0.6771 0.291 0.194 0.0766

1965 0.985 0.9085 0.6604 0.2881 0.1921 0.0641

1966 0.985 0.9071 0.6741 0.2951 0.1968 0.06948

1967 0.985 0.8984 0.6344 0.2724 0.1816 0.06302

1968 9.152 8.528 6.436 2.785 1.857 0.475

1969 3.248 3.017 2.251 1.295 0.926 0.2841

1970 0.985 0.8918 0.6215 0.2679 0.1786 0.06963

1971 36.76 32.72 21.44 8.818 5.879 1.464

1972 32.73 30.3 20.35 8.105 5.404 1.696

1973 7.81 7.216 5.281 2.967 2.076 0.561

1974 0.985 0.9003 0.6377 0.2752 0.1835 0.05594

1975 0.985 0.9076 0.6575 0.2864 0.1909 0.06075

1976 2.42 2.266 1.671 0.74 06 0.4938 0.1397

1977 0.985 0.9077 0.6674 0.4102 0.2894 0.119

1978 0.985 0.8981 0.6263 0.2681 0.1788 0.06597

1979 2.047 1.87 1.313 0.5908 0.3939 0.1139

1980 0.985 0.9039 0.645 0.279 0.186 0.08219

1981 9.371 8.655 6.33 2.77 1.846 0.473

1982 2.701 2.511 1.87 8 1.05 0.7289 0.2361

1983 0.985 0.9112 0.7251 0.3202 0.2135 0.07295

1984 2.667 2.388 1.561 0.6742 0.4495 0.1324

1985 0.985 0.9155 0.7112 0.3185 0.2123 0.09539

1986 1.394 1.278 0.9076 0.3918 0.2612 0.08704

1987 0.985 0.8926 0.6092 0.2584 0.1722 0.06644

1988 0.985 0.9045 0.6469 0.2801 0.1867 0.0613

1989 6.199 5.81 4.565 1.887 1.258 0.3245

1990 2.805 2.542 1.737 0.8757 0.6001 0.1916

Sorted results

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

0.032258064516129 36.76 32.72 21.44 8.818 5.879 1.696

0.0645161290322581 32.73 30.3 20.35 8.105 5.404 1.464

0.0967741935483871 9.371 8.655 6.436 2.967 2.076 0.561

0.129032258064516 9.152 8.528 6.33 2.785 1.857 0.475

0.161290322580645 7.81 7.216 5.281 2.77 1.846 0.473

0.193548387096774 6.199 5.81 4.565 1.887 1 .258 0.3245

0.225806451612903 3.248 3.017 2.251 1.295 0.926 0.2841

0.258064516129032 2.805 2.542 1.878 1.05 0.7289 0.2361- Page 88 of 115

- 0.290322580645161 2.701 2.511 1.737 0.8757 0.6001 0.1916

0.32258064516129 2.667 2.388 1.671 0.7406 0.4938 0.1397

0.354838709677419 2.4 2 2.266 1.561 0.6742 0.4495 0.1324

0.387096774193548 2.047 1.87 1.313 0.5908 0.3939 0.119

0.419354838709677 1.394 1.278 0.9076 0.4102 0.2894 0.1139

0.451612903225806 0.985 0.9237 0.757 0.3918 0.2612 0.09539

0.483870967741936 0.985 0.9194 0.7251 0.3469 0.23 13 0.08704

0.516129032258065 0.985 0.9155 0.7112 0.3202 0.2135 0.08219

0.548387096774194 0.985 0.9137 0.6783 0.3185 0.2123 0.07919

0.580645161290323 0.985 0.9112 0.6771 0.2988 0.1992 0.0766

0.612903225806452 0.985 0.9085 0.6741 0.2951 0.1968 0.07295

0.6451 61290322581 0.985 0.9077 0.6695 0.2939 0.1959 0.06963

0.67741935483871 0.985 0.9076 0.6674 0.291 0.194 0.06948

0.709677419354839 0.985 0.9071 0.6604 0.2881 0.1921 0.06701

0.741935483870968 0.985 0.9045 0.6575 0.2864 0.1909 0.06644

0.774193548387097 0.985 0 .9039 0.6469 0.2801 0.1867 0.06597

0.806451612903226 0.985 0.9003 0.645 0.279 0.186 0.0641

0.838709677419355 0.985 0.8984 0.6377 0.2752 0.1835 0.06302

0.870967741935484 0.985 0.8981 0.6344 0.2724 0.1816 0.0613

0.903225806451613 0.985 0.8926 0.6263 0.2681 0 .1788 0.06075

0.935483870967742 0.985 0.8918 0.6215 0.2679 0.1786 0.05594

0.967741935483871 0.985 0.8803 0.6092 0.2584 0.1722 0.04831

0.1 9.3491 8.6423 6.4254 2.9488 2.0541 0.5524

Average of yearly averages: 0.246520333333333

Inputs generated by pe5.pl

- Novemeber 2006

Data used for this run:

Output File: HcyanamideFLblueberries

Metfile: w03813.dvf

PRZM scenario: GAPeachesSTD.txt

EXAMS environment file: pond298.exv

Chemical Name: Hcyanamide

Description Variable Name Value Unit s Comments

Molecular weight mwt 42.04 g/mol

Henry's Law Const. henry 2.68E

- 10 atm

- m^3/mol

Vapor Pressure vapr 0.00375 torr

Solubility sol 7.8E5 mg/L

Kd Kd mg/L

Koc Koc 7.3 mg/L

Photolysis half

- life kdp 29 days Half

- life

Aerobic Aquatic Metabolism kbacw 5. 28 days Halfife

Anaerobic Aquatic Metabolism kbacs 70 days Halfife

Aerobic Soil Metabolism asm 1.5 days Halfife

Hydrolysis: pH 7 0 days Half

- life

Method: CAM 2 integer See PRZM manual

Incorporation Depth: DEPI 0 cm

Application Rate: TAPP 19.7 kg/ha

Application Efficiency: APPEFF 0.99 fraction

Spray Drift DRFT 0.001 fraction of application rate applied to pond

Application Date Date 01

- 12 dd/mm or dd/mmm or dd

- mm or dd

- mmm

Record 17: FILTRA

IPSCND 1

UPTKF

Record 18: PLVKRT- Page 89 of 115

- PLDKRT

FEXTRC 0.5

Fla g for Index Res. Run IR EPA Pond

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

stored as HcyanamideMIcherries.out

Chemical: Hcyanamide

PRZM environment: MICherriesSTD.txt modified Tueday, 29 May 2007 at 13:56:56

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

Metfile: w14850.dvf modified Wedday, 3 July 2002 at 09:05:40

Water segment concentrations (ppb)

Year Peak 96 hr 21 Day 60 Day 90 Day Yearly

1961 17.48 16.48 13.13 7.879 5.57 1.385

1962 10.17 9.692 7.515 4.206 2.907 0.7202

1963 15.74 15.02 12.21 7.052 4.946 1.227

1964 0.9854 0.9405 0.7452 0.4216 0.2903 0.07182

1965 0.985 0.9401 0.7666 0.4728 0.3313 0.08233

1966 0.985 0.938 0.7528 0.4571 0.3227 0.07999

1967 2.635 2.516 2.026 1.202 0.8 498 0.2109

1968 0.9851 0.9345 0.7321 0.4114 0.2864 0.0708

1969 0.985 0.9401 0.7659 0.4445 0.3102 0.07704

1970 0.985 0.9401 0.7392 0.4141 0.2867 0.07099

1971 1.075 1.006 0.882 0.5464 0.3828 0.09479

1972 0.985 0.9401 0.7623 0.4621 0.3225 0.07983

1973 1.736 1 .615 1.211 0.7812 0.5514 0.1367

1974 1.99 1.888 1.416 0.8648 0.6077 0.1507

1975 5.041 4.811 3.891 2.321 1.603 0.3968

1976 110 107 85.02 47.56 33.19 8.2

1977 13.64 13.09 10.06 5.456 3.748 0.9291

1978 0.9853 0.9404 0.7638 0.4581 0.3189 0.07918

1979 15.99 15. 21 11.97 7.097 5.011 1.248

1980 0.9855 0.9406 0.7507 0.4371 0.3043 0.07553

1981 2.883 2.78 2.122 1.23 0.8605 0.2133

1982 113 108 87.59 51.86 35.82 8.883

1983 0.9883 0.9426 0.7609 0.4667 0.3328 0.08389

1984 0.985 0.9402 0.753 0.4412 0.3099 0.07667

1985 20.0 9 19.17 14.45 7.911 5.498 1.364

1986 100 96.12 74.98 40.75 28.1 6.963

1987 0.9874 0.9368 0.7213 0.3928 0.2693 0.06757

1988 1.136 1.075 0.9226 0.5673 0.3929 0.09696

1989 6.438 6.251 4.933 2.909 2.041 0.5066

1990 0.9852 0.9361 0.7474 0.4218 0.2945 0.07309

Sorted results

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

0.032258064516129 113 108 87.59 51.86 35.82 8.883

0.0645161290322581 110 107 85.02 47.56 33.19 8.2

0.0967741935483871 100 96.12 74.98 40.75 28.1 6.963- Page 90 of 115

- 0.129032258064516 20.09 19.17 14.45 7.911 5. 57 1.385

0.161290322580645 17.48 16.48 13.13 7.879 5.498 1.364

0.193548387096774 15.99 15.21 12.21 7.097 5.011 1.248

0.225806451612903 15.74 15.02 11.97 7.052 4.946 1.227

0.258064516129032 13.64 13.09 10.06 5.456 3.748 0.9291

0.290322580645161 10.17 9.692 7.515 4.206 2.907 0.7202

0.32258064516129 6.438 6.251 4.933 2.909 2.041 0.5066

0.354838709677419 5.041 4.811 3.891 2.321 1.603 0.3968

0.387096774193548 2.883 2.78 2.122 1.23 0.8605 0.2133

0.419354838709677 2.635 2.516 2.026 1.202 0.8498 0.2109

0.4516129032 25806 1.99 1.888 1.416 0.8648 0.6077 0.1507

0.483870967741936 1.736 1.615 1.211 0.7812 0.5514 0.1367

0.516129032258065 1.136 1.075 0.9226 0.5673 0.3929 0.09696

0.548387096774194 1.075 1.006 0.882 0.5464 0.3828 0.09479

0.580645161290323 0.9883 0.9426 0.7666 0.4728 0.3328 0.08389

0.612903225806452 0.9874 0.9406 0.7659 0.4667 0.3313 0.08233

0.645161290322581 0.9855 0.9405 0.7638 0.4621 0.3227 0.07999

0.67741935483871 0.9854 0.9404 0.7623 0.4581 0.3225 0.07983

0.709677419354839 0.9853 0.9402 0.7609 0.4571 0.318 9 0.07918

0.741935483870968 0.9852 0.9401 0.753 0.4445 0.3102 0.07704

0.774193548387097 0.9851 0.9401 0.7528 0.4412 0.3099 0.07667

0.806451612903226 0.985 0.9401 0.7507 0.4371 0.3043 0.07553

0.838709677419355 0.985 0.9401 0.7474 0.4218 0.2945 0.07309

0.870967741935484 0.985 0.938 0.7452 0.4216 0.2903 0.07182

0.903225806451613 0.985 0.9368 0.7392 0.4141 0.2867 0.07099

0.935483870967742 0.985 0.9361 0.7321 0.4114 0.2864 0.0708

0.967741935483871 0.985 0.9345 0.7213 0.3928 0.2693 0.06757

0.1 92.009 88.42 5 68.927 37.4661 25.847 6.4052

Average of yearly averages: 1.123826

Inputs generated by pe5.pl

- Novemeber 2006

Data used for this run:

Output File: HcyanamideMIcherries

Metfile: w14850.dvf

PRZM scenario: MICherriesSTD.txt

EXAMS environment file: po nd298.exv

Chemical Name: Hcyanamide

Description Variable Name Value Units Comments

Molecular weight mwt 42.04 g/mol

Henry's Law Const. henry 2.68E

- 10 atm

- m^3/mol

Vapor Pressure vapr 0.00375 torr

Solubility sol 7.8E5 mg/L

Kd Kd mg/L

Koc Koc 7.3 mg/L

Photol ysis half

- life kdp 29 days Half

- life

Aerobic Aquatic Metabolism kbacw 5.28 days Halfife

Anaerobic Aquatic Metabolism kbacs 70 days Halfife

Aerobic Soil Metabolism asm 1.5 days Halfife

Hydrolysis: pH 7 0 days Half

- life

Method: CAM 2 integer See PRZM manual

Incorporation Depth: DEPI 0 cm

Application Rate: TAPP 19.7 kg/ha

Application Efficiency: APPEFF 0.99 fraction

Spray Drift DRFT 0.001 fraction of application rate applied to pond- Page 91 of 115

- Application Date Date 24

- 03 dd/mm or dd/mmm or dd

- mm or dd

- mmm

Record 17: FILT RA

IPSCND 1

UPTKF

Record 18: PLVKRT

PLDKRT

FEXTRC 0.5

Flag for Index Res. Run IR EPA Pond

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

stored as HcyanamideCAgrapes.out

Chemical: Hcyanamide

PRZM environment: C Agrapes_WirrigSTD.txt modified Tueday, 29 May 2007 at 13:42:54

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

Metfile: w93193.dvf modified Wedday, 3 July 2002 at 09:04:24

Water segment concentrations (ppb)

Year Peak 96 hr 21 Day 60 Day 90 Day Yearly

1961 0.985 0.8962 0.6203 0.3202 0.2223 0.05527

1962 87.74 81.58 59.67 31.74 21.7 5.365

1963 46.28 41.39 27.35 13.65 9.42 2.333

1964 0.9851 0.9083 0.6592 0.3501 0.2413 0.05963

1965 42.66 38.17 24.93 11.59 7.898 1.971

1966 0.9852 0.9 077 0.6569 0.3315 0.2253 0.05581

1967 1.39 1.251 0.856 0.6516 0.5176 0.1299

1968 0.985 0.8822 0.5802 0.3877 0.2881 0.07148

1969 6.215 5.724 4.147 2.341 1.643 0.4069

1970 5.663 5.095 3.372 1.731 1.241 0.3077

1971 6.279 5.534 3.406 1.503 1.062 0.3048

1972 0. 985 0.8941 0.6137 0.2939 0.1993 0.06264

1973 30.36 27.56 18.92 9.818 6.748 1.668

1974 0.9851 0.904 0.6449 0.3672 0.2673 0.06639

1975 0.985 0.8999 0.632 0.3305 0.2292 0.05675

1976 215 197 139 72.18 49.77 12.28

1977 0.9858 0.8911 0.6186 0.4022 0.2822 0.07021

1978 166 156 107 51.25 34.83 8.605

1979 1.962 1.785 1.2 0.6977 0.4784 0.1183

1980 14.14 12.76 8.563 4.427 3.065 0.7567

1981 0.985 0.8947 0.6155 0.4445 0.3231 0.08017

1982 1.469 1.381 0.9802 0.6646 0.5002 0.1246

1983 1.455 1.299 0.847 0.5855 0.4114 0.102

1 984 3.006 2.735 1.895 0.9248 0.6287 0.1551

1985 0.985 0.8945 0.615 0.3164 0.2151 0.05314

1986 43.1 38.57 25.15 11.64 7.893 1.949

1987 3.128 2.831 1.922 1.005 0.683 0.1718

1988 2.939 2.552 1.87 1.133 1.004 0.2647

1989 1.375 1.216 0.766 0.658 0.4725 0.121

1990 1.809 1.535 0.8268 0.498 0.3983 0.1372

Sorted results

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

0.032258064516129 215 197 139 72.18 49.77 12.28- Page 92 of 115

- 0.0645161290322581 166 156 107 51.25 34.83 8.605

0.0967741935483871 87.74 81.58 59.67 31.74 21.7 5.365

0.129032258064516 46.28 41.39 27.35 13.65 9.42 2.333

0.161290322580645 43.1 38.57 25.15 11.64 7.898 1.971

0.193548387096774 42.66 38.17 24.93 11.59 7.893 1.949

0.225806451612903 30.36 27.56 18.92 9.818 6.748 1.668

0.258064516129032 14.14 12.76 8.563 4.427 3.065 0.7567

0.290322580645161 6.279 5.724 4.147 2.341 1.643 0.4069

0.32258064516129 6.215 5.534 3.406 1.731 1.241 0.3077

0.354838709677419 5.663 5.095 3.372 1.503 1.062 0.3048

0.387096774193548 3.128 2.831 1.922 1.133 1.004 0.2647

0.419354838709677 3.006 2.735 1.895 1.005 0.683 0.1718

0.451612903225806 2.939 2.552 1.87 0.9248 0.6287 0.1551

0.483870967741936 1.962 1.785 1.2 0.6977 0.5176 0.1372

0.516129032258065 1.809 1.535 0.9802 0.6646 0.5002 0.1299

0.548387096774194 1.469 1.381 0.856 0.658 0.4784 0.1246

0.580645161290323 1.455 1.299 0.847 0.6516 0.4725 0.121

0.612903225806452 1.39 1.251 0.8268 0.5855 0.4114 0.1183

0.645161290322581 1.375 1.216 0.766 0.498 0.3983 0.102

0.67741935483871 0.9858 0.9083 0.6592 0.4445 0.3231 0.08017

0.709677419354839 0.9852 0.9077 0.6569 0.4022 0.2881 0.07148

0.741935483870968 0.9851 0.904 0.6449 0.3877 0.2822 0.07021

0.774193548387097 0.9851 0.8999 0.632 0.3672 0.2673 0.06639

0.806451612903226 0.985 0.8962 0.6203 0.3501 0.2413 0.06264

0.838709677419355 0.985 0.8947 0.6186 0. 3315 0.2292 0.05963

0.870967741935484 0.985 0.8945 0.6155 0.3305 0.2253 0.05675

0.903225806451613 0.985 0.8941 0.615 0.3202 0.2223 0.05581

0.935483870967742 0.985 0.8911 0.6137 0.3164 0.2151 0.05527

0.967741935483871 0.985 0.8822 0.5802 0.2939 0.1993 0.053 14

0.1 83.594 77.561 56.438 29.931 20.472 5.0618

Average of yearly averages: 1.26343966666667

Inputs generated by pe5.pl

- Novemeber 2006

Data used for this run:

Output File: HcyanamideCAgrapes

Metfile: w93193.dvf

PRZM scenario: CAgrapes_WirrigSTD .txt

EXAMS environment file: pond298.exv

Chemical Name: Hcyanamide

Description Variable Name Value Units Comments

Molecular weight mwt 42.04 g/mol

Henry's Law Const. henry 2.68E

- 10 atm

- m^3/mol

Vapor Pressure vapr 0.00375 torr

Solubility sol 7.8E5 mg/L

Kd K d mg/L

Koc Koc 7.3 mg/L

Photolysis half

- life kdp 29 days Half

- life

Aerobic Aquatic Metabolism kbacw 5.28 days Halfife

Anaerobic Aquatic Metabolism kbacs 70 days Halfife

Aerobic Soil Metabolism asm 1.5 days Halfife

Hydrolysis: pH 7 0 days Half

- life

Method: CAM 2 integer See PRZM manual

Incorporation Depth: DEPI 0 cm

Application Rate: TAPP 19.7 kg/ha- Page 93 of 115

- Application Efficiency: APPEFF 0.99 fraction

Spray Drift DRFT 0.001 fraction of application rate applied to pond

Application Date Date 09

- 02 dd/mm or dd/mmm or dd

- mm or dd

- mmm

Record 17: FILTRA

IPSCND 1

UPTKF

Record 18: PLVKRT

PLDKRT

FEXTRC 0.5

Flag for Index Res. Run IR EPA Pond

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

stored as HcyanamideNYgrapes.out

Chemical: H cyanamide

PRZM environment: NYGrapesSTD.txt modified Tueday, 29 May 2007 at 13:59:44

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

Metfile: w14860.dvf modified Wedday, 3 July 2002 at 09:06:14

Water segment concentrations (ppb)

Year Peak 96 hr 21 Day 60 Day 90 Day Yearly

1961 1.751 1.639 1.257 0.7949 0.5575 0.1382

1962 0.985 0.9382 0.7224 0.3883 0.2643 0.06534

1963 2.941 2.775 2.1 1.149 0.7938 0.1964

1964 0.985 0.933 0.722 0.3883 0.2651 0.06538

1965 0.985 0.9401 0.7882 0.4664 0. 3198 0.07912

1966 1.371 1.273 1.009 0.6179 0.432 0.107

1967 0.985 0.9356 0.7147 0.394 0.2742 0.06784

1968 0.985 0.9307 0.7232 0.395 0.274 0.06766

1969 1.291 1.189 0.9583 0.5633 0.391 0.0969

1970 1.356 1.256 1.002 0.6024 0.416 0.103

1971 0.985 0.9402 0.7525 0.4469 0.3125 0.07745

1972 0.985 0.9401 0.7521 0.4436 0.3088 0.07645

1973 0.985 0.9194 0.7174 0.4079 0.2841 0.07035

1974 1.507 1.443 1.105 0.6384 0.4448 0.1103

1975 0.985 0.9402 0.7558 0.4433 0.3044 0.07528

1976 1.92 1.79 1.313 0.7922 0.5536 0.1368

1977 2 2.7 21.31 15.69 8.414 5.781 1.432

1978 2.587 2.469 2.081 1.22 0.8464 0.2098

1979 5.951 5.644 4.387 2.552 1.785 0.4428

1980 1.689 1.589 1.204 0.7395 0.5152 0.1275

1981 0.985 0.9377 0.7212 0.3935 0.2721 0.06733

1982 4.277 4.022 3.044 1.716 1.183 0.2929

1983 0.9851 0.9283 0.7075 0.3949 0.2733 0.06764

1984 0.985 0.9401 0.7256 0.3981 0.275 0.06784

1985 2.037 1.88 1.305 0.7197 0.4918 0.1217

1986 0.985 0.9273 0.6914 0.3653 0.2495 0.06168

1987 7.698 7.215 5.194 2.808 1.922 0.4749

1988 52.55 49.75 38.2 20.98 14.4 3.551

1989 25.83 24.73 20.07 11.65 8.071 1.998

1990 0.9855 0.9249 0.682 0.36 0.2474 0.06144

Sorted results

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

0.032258064516129 52.55 49.75 38.2 20.98 14.4 3.551- Page 94 of 115

- 0.0645161290322581 25.83 24.73 20.07 11.65 8.071 1 .998

0.0967741935483871 22.7 21.31 15.69 8.414 5.781 1.432

0.129032258064516 7.698 7.215 5.194 2.808 1.922 0.4749

0.161290322580645 5.951 5.644 4.387 2.552 1.785 0.4428

0.193548387096774 4.277 4.022 3.044 1.716 1.183 0.2929

0.225806451612903 2.941 2.775 2. 1 1.22 0.8464 0.2098

0.258064516129032 2.587 2.469 2.081 1.149 0.7938 0.1964

0.290322580645161 2.037 1.88 1.313 0.7949 0.5575 0.1382

0.32258064516129 1.92 1.79 1.305 0.7922 0.5536 0.1368

0.354838709677419 1.751 1.639 1.257 0.7395 0.5152 0.1275

0.3870967741 93548 1.689 1.589 1.204 0.7197 0.4918 0.1217

0.419354838709677 1.507 1.443 1.105 0.6384 0.4448 0.1103

0.451612903225806 1.371 1.273 1.009 0.6179 0.432 0.107

0.483870967741936 1.356 1.256 1.002 0.6024 0.416 0.103

0.516129032258065 1.291 1.189 0.9583 0.5633 0.391 0.0969

0.548387096774194 0.9855 0.9402 0.7882 0.4664 0.3198 0.07912

0.580645161290323 0.9851 0.9402 0.7558 0.4469 0.3125 0.07745

0.612903225806452 0.985 0.9401 0.7525 0.4436 0.3088 0.07645

0.645161290322581 0.985 0.9401 0.7521 0.4433 0.3044 0.07528

0.67741935483871 0.985 0.9401 0.7256 0.4079 0.2841 0.07035

0.709677419354839 0.985 0.9382 0.7232 0.3981 0.275 0.06784

0.741935483870968 0.985 0.9377 0.7224 0.395 0.2742 0.06784

0.774193548387097 0.985 0.9356 0.722 0.3949 0.274 0.06766

0.806451612903226 0.9 85 0.933 0.7212 0.394 0.2733 0.06764

0.838709677419355 0.985 0.9307 0.7174 0.3935 0.2721 0.06733

0.870967741935484 0.985 0.9283 0.7147 0.3883 0.2651 0.06538

0.903225806451613 0.985 0.9273 0.7075 0.3883 0.2643 0.06534

0.935483870967742 0.985 0.9249 0.6914 0 .3653 0.2495 0.06168

0.967741935483871 0.985 0.9194 0.682 0.36 0.2474 0.06144

0.1 21.1998 19.9005 14.6404 7.8534 5.3951 1.33629

Average of yearly averages: 0.350333333333333

Inputs generated by pe5.pl

- Novemeber 2006

Data used for this run:

Outpu t File: HcyanamideNYgrapes

Metfile: w14860.dvf

PRZM scenario: NYGrapesSTD.txt

EXAMS environment file: pond298.exv

Chemical Name: Hcyanamide

Description Variable Name Value Units Comments

Molecular weight mwt 42.04 g/mol

Henry's Law Const. henry 2.68E

- 10 at m

- m^3/mol

Vapor Pressure vapr 0.00375 torr

Solubility sol 7.8E5 mg/L

Kd Kd mg/L

Koc Koc 7.3 mg/L

Photolysis half

- life kdp 29 days Half

- life

Aerobic Aquatic Metabolism kbacw 5.28 days Halfife

Anaerobic Aquatic Metabolism kbacs 70 days Halfife

Aerobic Soil Metabolism asm 1.5 days Halfife

Hydrolysis: pH 7 0 days Half

- life

Method: CAM 2 integer See PRZM manual

Incorporation Depth: DEPI 0 cm

Application Rate: TAPP 19.7 kg/ha- Page 95 of 115

- Application Efficiency: APPEFF 0.99 fraction

Spray Drift DRFT 0.001 fraction of applica tion rate applied to pond

Application Date Date 25

- 03 dd/mm or dd/mmm or dd

- mm or dd

- mmm

Record 17: FILTRA

IPSCND 1

UPTKF

Record 18: PLVKRT

PLDKRT

FEXTRC 0.5

Flag for Index Res. Run IR EPA Pond

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

stored as HcyanamideCAkiwi.out

Chemical: Hcyanamide

PRZM environment: CAfruit_WirrigSTD.txt modified Tueday, 29 May 2007 at 13:42:32

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

Metfile: w93193.dvf modified Wedday, 3 July 2002 at 09:04:24

Water segment concentrations (ppb)

Year Peak 96 hr 21 Day 60 Day 90 Day Yearly

1961 0.985 0.8881 0.5954 0.2894 0.197 0.04868

1962 0.985 0.8937 0.6124 0.2999 0.2026 0.05002

1963 11.58 10.47 7.51 4.124 2.9 17 0.7237

1964 0.9851 0.8939 0.6129 0.3065 0.2084 0.05135

1965 119 107 69.67 32.35 21.85 5.4

1966 0.9854 0.8771 0.5627 0.2606 0.1752 0.04334

1967 10.75 9.674 6.572 3.674 2.58 0.6381

1968 0.985 0.88 0.5718 0.3638 0.2513 0.06195

1969 9.36 8.222 5.048 2.234 1 .637 0.4061

1970 126 113 74.16 35.9 24.33 6.007

1971 24.6 21.68 13.34 5.87 3.994 1.016

1972 1.103 0.8612 0.5205 0.234 0.1576 0.06091

1973 1.16 1.057 0.7236 0.5184 0.3542 0.08744

1974 2.027 1.811 1.202 0.6057 0.4109 0.1014

1975 0.985 0.8953 0.6248 0.3229 0. 2208 0.05453

1976 0.985 0.8922 0.608 0.3047 0.2071 0.05099

1977 0.985 0.8913 0.6278 0.3166 0.2142 0.0529

1978 25.6 22.44 13.68 6.371 4.322 1.067

1979 0.9853 0.8751 0.5572 0.2593 0.1747 0.04313

1980 9.138 8.22 5.466 2.654 1.802 0.4438

1981 1.197 1.075 0.705 8 0.5004 0.3453 0.08528

1982 7.945 7.516 5.382 2.71 1.874 0.4632

1983 80.64 71.96 46.58 22.35 15.15 3.74

1984 0.9851 0.8682 0.5387 0.2469 0.1662 0.04093

1985 0.985 0.8882 0.5958 0.2838 0.1908 0.04708

1986 17.43 15.29 10.31 4.687 3.178 0.7842

1987 5.667 5.065 3.471 1.759 1.23 0.3058

1988 25.11 21.79 15.05 6.434 4.401 1.099

1989 49.38 43.67 27.41 15.36 10.46 2.584

1990 6.26 5.215 2.375 1.715 1.177 0.329

Sorted results

Prob. Peak 96 hr 21 Day 60 Day 90 Day Yearly- Page 96 of 115

- 0.032258064516129 126 113 74.16 35.9 24.33 6.007

0.0645161290322581 119 107 69.67 32.35 21.85 5.4

0.0967741935483871 80.64 71.96 46.58 22.35 15.15 3.74

0.129032258064516 49.38 43.67 27.41 15.36 10.46 2.584

0.161290322580645 25.6 22.44 15.05 6.434 4.401 1.099

0.193548387096774 25.11 21.79 13.68 6.3 71 4.322 1.067

0.225806451612903 24.6 21.68 13.34 5.87 3.994 1.016

0.258064516129032 17.43 15.29 10.31 4.687 3.178 0.7842

0.290322580645161 11.58 10.47 7.51 4.124 2.917 0.7237

0.32258064516129 10.75 9.674 6.572 3.674 2.58 0.6381

0.354838709677419 9.36 8.22 2 5.466 2.71 1.874 0.4632

0.387096774193548 9.138 8.22 5.382 2.654 1.802 0.4438

0.419354838709677 7.945 7.516 5.048 2.234 1.637 0.4061

0.451612903225806 6.26 5.215 3.471 1.759 1.23 0.329

0.483870967741936 5.667 5.065 2.375 1.715 1.177 0.3058

0.516129032258 065 2.027 1.811 1.202 0.6057 0.4109 0.1014

0.548387096774194 1.197 1.075 0.7236 0.5184 0.3542 0.08744

0.580645161290323 1.16 1.057 0.7058 0.5004 0.3453 0.08528

0.612903225806452 1.103 0.8953 0.6278 0.3638 0.2513 0.06195

0.645161290322581 0.9854 0.8939 0.6248 0.3229 0.2208 0.06091

0.67741935483871 0.9853 0.8937 0.6129 0.3166 0.2142 0.05453

0.709677419354839 0.9851 0.8922 0.6124 0.3065 0.2084 0.0529

0.741935483870968 0.9851 0.8913 0.608 0.3047 0.2071 0.05135

0.774193548387097 0.985 0.8882 0.5958 0.2999 0. 2026 0.05099

0.806451612903226 0.985 0.8881 0.5954 0.2894 0.197 0.05002

0.838709677419355 0.985 0.88 0.5718 0.2838 0.1908 0.04868

0.870967741935484 0.985 0.8771 0.5627 0.2606 0.1752 0.04708

0.903225806451613 0.985 0.8751 0.5572 0.2593 0.1747 0.04334

0.9354 83870967742 0.985 0.8682 0.5387 0.2469 0.1662 0.04313

0.967741935483871 0.985 0.8612 0.5205 0.234 0.1576 0.04093

0.1 77.514 69.131 44.663 21.651 14.681 3.6244

Average of yearly averages: 0.862894333333334

Inputs generated by pe5.pl

- Novemeber 2006

Data used for this run:

Output File: HcyanamideCAkiwi

Metfile: w93193.dvf

PRZM scenario: CAfruit_WirrigSTD.txt

EXAMS environment file: pond298.exv

Chemical Name: Hcyanamide

Description Variable Name Value Units Comments

Molecular weight mwt 42.04 g/mol

H enry's Law Const. henry 2.68E

- 10 atm

- m^3/mol

Vapor Pressure vapr 0.00375 torr

Solubility sol 7.8E5 mg/L

Kd Kd mg/L

Koc Koc 7.3 mg/L

Photolysis half

- life kdp 29 days Half

- life

Aerobic Aquatic Metabolism kbacw 5.28 days Halfife

Anaerobic Aquatic Metabolism kbacs 70 days Halfife

Aerobic Soil Metabolism asm 1.5 days Halfife

Hydrolysis: pH 7 0 days Half

- life

Method: CAM 2 integer See PRZM manual

Incorporation Depth: DEPI 0 cm- Page 97 of 115

- Application Rate: TAPP 19.7 kg/ha

Application Efficiency: APPEFF 0.99 fraction

Spray D rift DRFT 0.001 fraction of application rate applied to pond

Application Date Date 01

- 03 dd/mm or dd/mmm or dd

- mm or dd

- mmm

Record 17: FILTRA

IPSCND 1

UPTKF

Record 18: PLVKRT

PLDKRT

FEXTRC 0.5

Flag for Index Res. Run IR EPA Pond

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

stored as HcyanamideGApeaches.out

Chemical: Hcyanamide

PRZM environment: GAPeachesSTD.txt modified Tueday, 29 May 2007 at 13:54:56

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

Metfile: w03813.dvf modified Wedday, 3 July 2002 at 09:04:32

Water segment concentrations (ppb)

Year Peak 96 hr 21 Day 60 Day 90 Day Yearly

1961 3.68 3.323 2.251 1.065 0.7249 0.1791

1962 0.488 0.4451 0.319 0.1633 0.1112 0.02744

1963 0.37 0.3435 0.2512 0.1189 0.08014 0.01978

1964 2.701 2.446 1.75 0.8607 0.5835 0.1436

1965 17.27 16.08 11.7 5.96 4.045 0.9984

1966 29.62 27.32 19.63 9.947 6.759 1.67

1967 0.3701 0.3421 0.247 0.1177 0.07929 0.01959

1968 0.37 0.3468 0.2649 0.1361 0.09239 0.02276

1 969 1.199 1.112 0.8191 0.4379 0.2984 0.07372

1970 0.37 0.3398 0.2416 0.1182 0.07984 0.01971

1971 0.37 0.3392 0.2401 0.1225 0.08327 0.02056

1972 1.672 1.538 1.091 0.5412 0.3669 0.09037

1973 39.33 36.37 26.18 12.19 8.239 2.034

1974 0.3778 0.3569 0.256 0.1185 0.07995 0.01974

1975 12.74 11.53 7.751 3.759 2.556 0.6311

1976 0.37 0.3318 0.2172 0.09997 0.06742 0.01661

1977 0.37 0.341 0.2689 0.1312 0.08851 0.02184

1978 0.37 0.3455 0.2598 0.1325 0.08981 0.02217

1979 0.8054 0.7477 0.5151 0.2758 0.1873 0.04625

1980 0.3 7 0.341 0.2476 0.1252 0.08506 0.02094

1981 7.757 7.026 4.723 2.267 1.533 0.3783

1982 19.45 17.61 11.77 5.444 3.686 0.91

1983 73.92 67.6 47.39 23.3 15.84 3.912

1984 0.3702 0.3365 0.2382 0.1183 0.0802 0.01978

1985 0.37 0.3394 0.2391 0.1139 0.07698 0.019

1986 0.37 0.334 0.2237 0.1068 0.07216 0.01781

1987 0.37 0.3396 0.2444 0.1209 0.08205 0.02025

1988 0.9054 0.8341 0.5892 0.307 0.2086 0.05139

1989 4.145 3.77 2.487 1.175 0.7996 0.1975

1990 8.269 7.361 4.692 2.16 1.461 0.3607- Page 98 of 115

- Sorted results

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

0.032258064516129 73.92 67.6 47.39 23.3 15.84 3.912

0.0645161290322581 39.33 36.37 26.18 12.19 8.239 2.034

0.0967741935483871 29.62 27.32 19.63 9.947 6.759 1.67

0.129032258064516 19.45 17.61 11.77 5.96 4.045 0.9984

0.16129032258064 5 17.27 16.08 11.7 5.444 3.686 0.91

0.193548387096774 12.74 11.53 7.751 3.759 2.556 0.6311

0.225806451612903 8.269 7.361 4.723 2.267 1.533 0.3783

0.258064516129032 7.757 7.026 4.692 2.16 1.461 0.3607

0.290322580645161 4.145 3.77 2.487 1.175 0.7996 0.1975

0 .32258064516129 3.68 3.323 2.251 1.065 0.7249 0.1791

0.354838709677419 2.701 2.446 1.75 0.8607 0.5835 0.1436

0.387096774193548 1.672 1.538 1.091 0.5412 0.3669 0.09037

0.419354838709677 1.199 1.112 0.8191 0.4379 0.2984 0.07372

0.451612903225806 0.9054 0.834 1 0.5892 0.307 0.2086 0.05139

0.483870967741936 0.8054 0.7477 0.5151 0.2758 0.1873 0.04625

0.516129032258065 0.488 0.4451 0.319 0.1633 0.1112 0.02744

0.548387096774194 0.3778 0.3569 0.2689 0.1361 0.09239 0.02276

0.580645161290323 0.3702 0.3468 0.2649 0.1325 0.08981 0.02217

0.612903225806452 0.3701 0.3455 0.2598 0.1312 0.08851 0.02184

0.645161290322581 0.37 0.3435 0.256 0.1252 0.08506 0.02094

0.67741935483871 0.37 0.3421 0.2512 0.1225 0.08327 0.02056

0.709677419354839 0.37 0.341 0.2476 0.1209 0.08205 0. 02025

0.741935483870968 0.37 0.341 0.247 0.1189 0.0802 0.01978

0.774193548387097 0.37 0.3398 0.2444 0.1185 0.08014 0.01978

0.806451612903226 0.37 0.3396 0.2416 0.1183 0.07995 0.01974

0.838709677419355 0.37 0.3394 0.2401 0.1182 0.07984 0.01971

0.87096774193 5484 0.37 0.3392 0.2391 0.1177 0.07929 0.01959

0.903225806451613 0.37 0.3365 0.2382 0.1139 0.07698 0.019

0.935483870967742 0.37 0.334 0.2237 0.1068 0.07216 0.01781

0.967741935483871 0.37 0.3318 0.2172 0.09997 0.06742 0.01661

0.1 28.603 26.349 18.844 9.54 83 6.4876 1.60284

Average of yearly averages: 0.399480333333333

Inputs generated by pe5.pl

- Novemeber 2006

Data used for this run:

Output File: HcyanamideGApeaches

Metfile: w03813.dvf

PRZM scenario: GAPeachesSTD.txt

EXAMS environment file: pond298. exv

Chemical Name: Hcyanamide

Description Variable Name Value Units Comments

Molecular weight mwt 42.04 g/mol

Henry's Law Const. henry 2.68E

- 10 atm

- m^3/mol

Vapor Pressure vapr 0.00375 torr

Solubility sol 7.8E5 mg/L

Kd Kd mg/L

Koc Koc 7.3 mg/L

Photolysis half

- life kdp 29 days Half

- life

Aerobic Aquatic Metabolism kbacw 5.28 days Halfife

Anaerobic Aquatic Metabolism kbacs 70 days Halfife

Aerobic Soil Metabolism asm 1.5 days Halfife

Hydrolysis: pH 7 0 days Half

- life- Page 99 of 115

- Method: CAM 2 integer See PRZM manual

Incor poration Depth: DEPI 0 cm

Application Rate: TAPP 7.4 kg/ha

Application Efficiency: APPEFF 0.99 fraction

Spray Drift DRFT 0.001 fraction of application rate applied to pond

Application Date Date 14

- 02 dd/mm or dd/mmm or dd

- mm or dd

- mmm

Record 17: FILTRA

I PSCND 1

UPTKF

Record 18: PLVKRT

PLDKRT

FEXTRC 0.5

Flag for Index Res. Run IR EPA Pond

Flag for runoff calc. RUNOFF none none, monthly or total(average of entire run)- Page 100 of 115

- 

### Appendix D. Example Terrestrial Exposure Model Inputs/Outputs

STIR



# Input

Application and Chemical Information

Enter Chemical Name Hydrogen

cyanamide

Enter Chemical Use

Is the Application a Spray? (enter y or n) y

If Spray What Type (enter ground or air) air

Enter Chemical Molecular Weight (g/mole) 42.04

Enter Chemical Vapor Pressure (mmHg) 3.75E

- 03

Enter Application Rate (lb a.i./acre) 17.6

Toxicity Properties

**Bird**

Enter Lowest Bird Oral LD 50 (mg/kg bw) 173

Enter Mineau Scaling Factor 1.15

Enter Tested Bird Weight (kg) 0.178

**Mammal**

Enter Lowest Rat Oral LD 50 (mg/kg bw) 300

Enter Lowest Rat Inhalation LC 50 (mg/L) 2.32

Duration of Rat Inhalation Study (hrs) 4

Enter Rat Weight (kg) 0.35



# Output

Results Avian (0.020 kg )

Maximum Vapor Concentration in Air at Saturation

(mg/m 3 ) 8.48E+00

Maximum 1

- hour Vapor Inhalation Dose (mg/kg) 1.07E+00

Adjusted Inhalation LD 50 7.46E+00

Ratio of Vapor Dose to Adjusted Inhalation LD 50 1.43E

- 01 Proceed to Refinements

Maximum Post

- treatment Spray Inhalation Dose (mg/kg) 1.69E+00

Ratio of Droplet Inhalation Dose to Adjusted Inhalation

LD 50 2.27E

- 01 Proceed to Refinements



### Results Mammalian (0.015 kg )

Maximum Vapor Concentration in Air at Saturation

(mg/m 3 ) 8.48E+00

Maximum 1

- hour Vapor Inhalation Dose (mg/kg) 1.34E+00

Adjusted Inhalation LD 50 1.38E+02

Ratio of Vapor Dose to Adjusted Inhalation LD 50 9.71E

- 03 Exposure not Likely Significant

Maximum Post

- treatment Spray Inhalation Dose (mg/kg) 2.13E+00

Ratio of Droplet Inhalation Dose to Adjusted Inhalation

LD 50 1.54E

- 02 Exposure not Likely Significant- Page 101 of 115

- 

### SIP

Table 1. Inputs

Parameter Value

Chemical name Hydrogen Cyanamide

Solubility (in water at 25 o C; mg/L) 78 0000

Mammalian LD 50 (mg/kg

- bw) 300

Mammalian test species laboratory rat

Body weight (g) of "other" mammalian

species

Mammalian NOAEL (mg/kg

- bw) 0.0625

Mammalian test species laboratory rat

Body weight (g) of "other" mammalian

species

Avian LD 50 (mg/kg

- bw) 173

Avian test species northern bobwhite quail

Body weight (g) of "other" avian species

Mineau scaling factor 1.15

Mallard NOAEC (mg/kg

- diet) 0

Bobwhite quail NOAEC (mg/kg

- diet) 153

NOAEC (mg/kg

- diet) for other bird species

Body weight (g) of other avian species

NOAEC (mg/kg

- diet) for 2nd other bird

species

Body weight (g) of 2nd other avian species

Table 2. Mammalian Results

Parameter Acute Chronic

Upper bound exposure (mg/kg

- bw) 96320.0000 96320.0000

Adjusted toxicity value (mg/kg

- bw) 230.7482 0.0481

Ratio of exposure to toxicity 417.4248 2003638.8571

Conclusion* Exposure through

drinking water alone is a

potential concern for

mammals Exposure through

drinking water alone is a

potential concern for

mammals

Table 3. Avian Results

Parameter Acute Chronic- Page 102 of 115

- Upper bound exposure (mg/kg

- bw) 453600.0000 453600.0000

Adjusted toxicity value (mg/kg

- bw) 124.6343 16.2636

Ratio of exposure to acute toxicity 3639.4474 27890.4301

Conclusion* Exposure through

drinking water alone is a

potential concern for

birds Exposure through

drinking water alone is a

potential concern for

birds

*Conclusion is for drinking water exposure alone. This does not combine all routes of exposure.

Therefore, when aggregated with other routes ( i.e ., diet, inhalation, dermal), pesticide exposure through

drinking water may contribute to a total exposure that has potential for effects to non

- target animals.- Page 103 of 115

- 

### T

- REX

Summary of Risk Quotient Calculations Based on Upper Bound Kenaga EECs

Tab le X. Upper Bound Kenaga, Acute Avian Dose

- Based Risk Quotients

Size

Class

(grams) Adjusted

LD50 EECs and RQs

Short Grass Tall Grass Broadleaf Plants Fruits/Pods/Seeds Arthropods Granivore

EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ

20 124.63 4810.71 38.60 2204.91 17.69 2706.03 21.71 300.67 2.41 1884.20 15.12 66.82 0.54

100 158.67 2743.27 17.29 1257.33 7.92 1543.09 9.73 171.45 1.08 1074.45 6.77 38.10 0.24

1000 224.12 1228.20 5.48 562.92 2.51 690.86 3.08 76.76 0.34 481.04 2.15 17.06 0.08

Tab le X. Upper Bound Kenaga, Subacute Avian Dietary Based Risk Quotients

LC50 EECs and RQs

Short Grass Tall Grass Broadleaf Plants Fruits/Pods/Seeds Arthropods

EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ

5000 4224.00 0.84 1936.00 0.39 2376.00 0.48 264.00 0.05 1654.40 0.33

Size class not used for dietary risk quotients

Tab le X. Upper Bound Kenaga, Chronic Avian Dietary Based Risk Quotients- Page 104 of 115

- NOAEC

(ppm) EECs and RQs

Short Grass Tall Grass Broadleaf Plants Fruits/Pods/Seeds Arthropods

EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ

153 4224.00 27.61 1936.00 12.65 2376.00 15.53 264.00 1.73 1654.40 10.81

Size class not used for dietary risk quotients

Tab le X. Upper Bound Kenaga, Acute Mammalian Dose

- Based Risk Quotients

Size

Class

(grams) Adjusted

LD50 EECs and RQs

Short Grass Tall Grass Broadleaf Plants Fruits/Pods/Seeds Arthropods Granivore

EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ

15 659.35 4027.26 6.11 1845.83 2.80 2265.33 3.44 251.70 0.38 1577.34 2.3923 55.934 0.0848

35 533.48 2783.38 5.22 1275.71 2.39 1565.65 2.93 173.96 0.33 1090.16 2.0435 38.658 0.0725

1000 230.75 645.34 2.80 295.78 1.28 363.00 1.57 40.33 0.17 252.756 1.0954 8.963 0.0388

Tab le X. Upper Bound Kenaga, Acute Mammalian Dietary Based Risk Quotients

LC50

(ppm) EECs and RQs

Short Grass Tall Grass Broadleaf Plants Fruits/Pods/Seeds Arthropods

EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ

0 4224.00 #DIV/0! 1936.00 #DIV/0! 2376.00 #DIV/0! 264.00 ##### 1654.40 #DIV/0!

Size class not used for dietary risk quotients- Page 105 of 115

- Table X. Upper Bound Kenaga, Chronic Mammalian Dietary Based Risk Quotients

NOAEC

(ppm) EECs and RQs

Short Grass Tall Grass Broadleaf Plants Fruits/Pods/Seeds/Large

Insects Arthropods

EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ

25 4224.00 168.96 1936.00 77.44 2376.00 95.04 264.00 10.56 1654.40 66.18

Size class not used for dietary risk quotients

Tab le X. Upper Bound Kenaga, Chronic Mammalian Dose

- Based Risk Quotients

Size

Class

(grams) Adjusted

NOAEL EECs and RQs

Short Grass Tall Grass Broadleaf Plants Fruits/Pods/Seeds Arthropods Granivore

EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ

15 2.75 4027.26 1465.90 1845.83 671.87 2265.33 824.57 251.70 91.62 1577.34 574.15 55.93 20.36

35 2.22 2783.38 1252.17 1275.71 573.91 1565.65 704.34 173.96 78.26 1090.16 490.43 38.66 17.39

1000 0.96 645.34 671.21 295.78 307.64 363.00 377.56 40.33 41.95 252.76 262.89 8.96 9.32- Page 106 of 115

- 

### TerrPlant

TerrPlant v. 1.2.2

Green values signify user inputs (Tables 1, 2 and 4).

Input and output guidance is in popups indicated by red arrows.

Table 1. Chemical Identity.

Chemical Name Hydrogen Cyanamide

PC code 14002

Use 6.8 lbs/A

Application Method Airblast

Application Form Spray

Solubility in Water

(ppm) 78 0000

Table 2. Input parameters used to derive EECs.

Input Parameter Symbol Value Units

Application Rate A 17.6 y

Incorporation I 1 none

Runoff Fraction R 0.05 none

Drift Fraction D 0.05 none

Table 3. EECs for Hydrogen Cyanamide. Units in y.

Description Equation EEC

Runoff to dry areas (A/I)*R 0.88

Runoff to semi

- aquatic areas (A/I)*R*10 8.8

Spray drift A*D 0.88

Total for dry areas ((A/I)*R)+(A*D) 1.76

Total for semi

- aquatic areas ((A/I)*R*10)+(A*D) 9.68

Table 4. Plant survival and growth data used for RQ derivation. Units are in y.

Seedling Emergence Vegetative Vigor

Plant type EC 25 NOAEC EC 25 NOAEC

Monocot 0.44 0.041 7.9 7.2

Dicot 0.056 0.89 0.096

Table 5. RQ values for plants in dry and semi

- aquatic areas exposed to Hydrogen Cyanamide

through runoff and/or spray drift.*

Plant Type Listed Status Dry Semi

- Aquatic Spray Drift

Monocot non

- listed 4.00 22.00 2.00

Monocot listed 42.93 236.10 21.46

Dicot non

- listed #DIV/0! #DIV/0! 0.99- Page 107 of 115

- Dicot listed 31.43 172.86 15.71

*If RQ > 1.0, the LOC is exceeded, resulting in potential for risk to that plant group.- Page 108 of 115

- 

### Appendix E. Reported Hydrogen Cyanamide Ecological Incident Summaries in the EIIS

Database

Table E

- 1. Hydrogen Cyanamide Incident Report Summaries

Incident # Organism(s)

Affected Certainty of

Involvement Legality of

Use Description

I000423

-

001 Grape Probable Misuse

(Accidental) Siemer & Associates reported

an incident of defoliation of

lemon trees in several groves in

the Coachella Valley (Riverside

County), California. The

damage to the lemon trees was

believed to be caused by the

use of Dormex (A.I.

Cyanamide) to a grape

vineyard. Dormex was

allegedely applied during

stormy weather using a high

pressure sprayer. The label

states to use a low pressure

sprayer and only when weather

conditions do not fav or drift.

I016036

-

022 Kiwifruits Possible Registered

Use The California Dept. of

Pesticide Regulations reported

an incident in which a total of

380 acres of kiwifruits were

damaged. One firm owns the

kiwifruits but they are located

in several areas and were not

all sprayed at the same time.

Dormex was applied during

January and February, 2004, as

was Valent Volck Supreme Oil

Spray more than three weeks

apart. A burning of buds was

observed on the kiwi vines

where both products were

applied. Damage amounted to

about a 20% loss of crop. A

label for Dormex use on

kiwifruit in Australia states

"dormant sprays containing oil

should not be made closer than

14 days before or after Dormex

application." This would

suggest that the combination of- Page 109 of 115

- 

### Table E

- 1. Hydrogen Cyanamide Incident Report Summaries

Incident # Organism(s)

Affected Certainty of

Involvement Legality of

Use Description

the two products is potentially

harmless.