UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON D.C., 20460 

PC Code: 02900 I 

DP Barcode: 416850 

MEMORANDUM February 20, 2014 

Subject: EFED Response to Comments Submitted to the Docket for 1 ,3-Dichloropropene 

(02900 1) Registration Review 

To: Margaret Hathaway, Chemical Review Manager 

Kevin Costello, Branch Chief 

Pesticide Re-Evaluation Division (7508P) 

From: Elizabeth Riley, Biologist 0 h.n ~ ~ 2/Z-'t /14 

Andrew Shelby, Environmental S'cie~~ ~ 2- 2 o. f 1.'( 

Environmental Risk Branch 6 - - d 

Environmental Fate and Effects Division (7507P) 

Through: Mark Corbin, M.S., Branch Chief ~ GQ 

Envirorunental Risk Branch 6 

Environmental Fate and Effects Division (7507P) 

The Pesticide Re-evaluation Division (PRD) received comments from Dow AgroSciences, a 

registrant of 1,3-Dichloropropene. PRD requested that EFED review and respond to the 

comments as appropriate. Specific comments and EFED responses are detailed below: 

1. Reference: Page 4, 1st bullet point Aerobic Soil Metabolism Study. Also Pages 34, 36, 37. 

Document states: Aerobic Soil Metabolism -An acceJ>table aerobic soil metabolism study has been 

previously submitted for two soils but the half-life estimates vary greatly, 14 days and 45 days. This 

results in a high 90th percentile average of94 days, the value used as a model input parameter. 

• Comment: Aerobic Soil Degradation of 1,3 D, 3-Chloroallyl Alcohol and 3-Chloroacylic Acid 

has been extensively studied by Dow AgroSciences (1-4) and other researchers (5-6). These 

studies indicate that the degradation of 1,3-D in soil is due to both biotic and abiotic mechanisms. 

As well as to the two studies referenced in EPA-HQ-OPP-2013-0154, two additional GLP studies 

(3-4) provide degradation half-lives for 1,3-D on 6 soils. Examination ofthe available literature 

supports Dow AgroSciences' position that the degradation of 1,3-D is rapid to moderately rapid 

in viable agricultural soils. The table below presents soil half-life data for 1,3-D which was 

generated using 3 1 different non-amended soils. The data shows that the degradation half life in 

loamy/clayey soils is approximately 7 days and Jess than 20 days in sandy soils. Other researchers 

(7 -13) have also reported laboratory aerobic half lives within the ranges outlined below. 
• EPA Response: EPA will consider all GLP aerobic soil metabolism data on l ,3-d submitted and 

requests the two aerobic soil metabolism studies performed on degradates conducted by Batzer, et 

a!. 

2. Reference: Page 4, 2nd bullet point, Anaerobic Aquatic Metabolism. Also Pages 36, 37. In 

reference to 3-chloroally alcohol and 3-chloroacrylic acid, document states: There is uncertainty 

relating to the anaerobic metabolism and the persistence or dissipation of this residue of concern 

depends on the characterization of this pathway. 

• Comment: A previously submitted aerobic soil study report (1) contained degradation rates of the 

3-chloroally alcohol and 3-chloroacrylic acid for one anaerobic soil. Based on experimental 

conditions, including I. The soil was flooded with water and was pre-incubated under anaerobic 

conditions for approx 3 months. 2. The sample containers were closed to the atmosphere. The 

design of the system for studying the anaerobic metabolism of I,3-D and its. alcohol and acid 

metabolites (1) in fact mimics a groundwater type situation since ground water is essentially 

saturated soil. Therefore the study results should be classified as anaerobic aquatic degradation 

rates and should fulfill the needs of the anaerobic aquatic study for the 3- chloroallyl alcohol and 

3-chloroacrylic acid metabolite. The half-lives are summarized in the table below. 

• EPA Response: EPA appreciates the comments submitted by Dow AgroSciences on the subject 

of soil degradation and looks forward to reviewing the cited study after its submission 

3. Reference: Page 4, 3rd bullet point. Document states: A field volatility study for a tarped 

application at maximum labeled rate is needed. Tarped field volatility studies have been previously 

submitted but not at the maximum rate. Due to the high maximum application rate and the multipathway dissipation of 1,3-D, it is important to fully characterize each use pattern that can result in 

significantly different dissipation and volatility behavior. 

• Comment: EPA anticipates additional data needs for another field volatility study, yet a 

significant body of research on I ,3-D emissions is available from the registrant and from studies 

published in peer-reviewed journals. The list of available 1 ,3-D flux studies has been provided 

previously. A total of II studies were conducted prior to the last re-registration of I,3-D ("Pre2000"). Numerous additional studies have been conducted by academia and government agencies 

(e.g. USDA-ARS) since 2000, primarily for the purpose of testing fumigant emission reduction 

strategies in light of the phase-out of methyl bromide under the Montreal Protocol. These studies 

add further to the body of research on 1 ,3-D emissions. Dow AgroSciences contends that 

sufficient field volatility data have been generated to characterize 1 ,3-D emissions for all bedded 

row and broadcast type applications, and for both drip applied and shank applied products at the 

maximum use rate. Table 1 shows a summary of the maximum allowed broadcast application 

rates according to DAS labels, and Table 2 shows the tarp flux studies that have been conducted 

or are in progress and can be submitted by early 20I4. The maximum broadcast application rates 

allowed for 1 ,3-D are for Telone II and Telone C-17 at 53.6 gpa 1,3-D (calculated as Product 

Rate x% I ,3-D in Product). Telone II and Telone C-17 are rarely applied under tarp however, so 

the majority of tarped field volatility studies have been conducted using Telone EC or InLine® 

which are applied through a drip irrigation system, although one study has been conducted on a 

tarped bedded field with shank applied Telone C-17 at I8 gpa 1,3-D (Study ENV94004). The 

maximum application rate for Telone EC is 24 gpa (22.5 gpa I ,3-D) and for InLine is 56 gpa (34 

gpa 1 ,3-D), according to the product labels. The three tarped field volatility studies using InLine 

that DAS has submitted to the EPA were conducted at 1,3-D application rates of I5.9 gpa (Study 
#980070), 16 gpa (Study# GH-C 5081, and 22.7 gpa (Study #110708). Although none of these 

studies were conducted at the maximum label application rate, the study application rate's were 

chosen to represent the 'high end' of what growers typically use, and represents well over 95% of 

applications made by growers. The high application rates listed on all 1,3-D labels are designated 

for use in nurseries only, resulting in a minimal number of acres treated annually as compared 

with fumigant use in crop production. Expected emissions from 1,3-D applications made at 

higher application rates than were used in the submitted studies can be determined by 

extrapolating the measured emissions from a given study by the ratio of the maximum 1,3-D 

application rate to the actual application rate used in the field study. Studies have shown that the 

rate of 1 ,3-D degradation in soil is not dependent on the starting soil concentration for the range 

of soil concentrations expected under typical application rates in the field (Ashworth et al., 2013; 

Ma et al., 200 1) and thus extrapolations to higher use rates are possible for I ,3-D by direct scaling 

of emissions. Furthermore, DAS will submit a field volatility study using drip applied Te1one EC 

at 40 gpa under LOPE tarp (Ajwa, 2009) that has not yet been submitted to the EPA, and would 

meet the requirement of a tarped field volatility study at the maximum application rate. That 

study was in fact conducted at an application rate greater than the maximum label rate for Telone 

EC and for InLine, the two DAS 1,3-D products that are applied under tarp. Additionally a field 

volatility study that measured 1,3-D emissions from broadcast shank-applied PicCior 60 (at 29.8 

gpa) under TIF (Totally Impermeable Film) tarp (Ajwa, 2012) will be available for submission to 

the EPA, as will a field volatility study using drip-applied PicClor 60 EC (at 48.9 gpa) on TIF 

tarped beds (Ajwa et al., Study #2013HAI, expected completion January 2014). The PicCior 60 

EC drip study will be conducted on tarped beds (30 inch beds on 48 inch centers) and will include 

estimates of flux from both tarped and untarped surfaces, in treated beds and in furrows. PicClor 

60 and PicClor 60 EC are formulations containing nominally 57% w/w chloropicrin and 37% 

w/w 1 ,3-dichloropropene. Given the robust dataset of GLP field volatility studies where 1 ,3-D 

was either drip or shank applied under tarp (with one study exceeding the max. label rate), as well 

as numerous published studies, the dissipation of 1,3-D in both broadcast and bedded tarped 

scenarios is well characterized. DAS contends that little additional knowledge or understanding 

of the fate and dissipation of 1 ,3-D will be obtained by conducting another volatility study under 

tarp. 

• EPA Response: EPA agrees that volatility is sufficiently characterized by previously submitted 

data and the final work plan will be amended to remove the requirement for a field volatility 

study. 

4. Reference: Page 4, 4t~~ bullet point. Environmental Chemistry Methods/Independent Laboratory 

Validation (OCSPP Guideline 850.6100). Document states: A study has been submitted that will 

fulfill this data requirement if found to be acceptable. Pending Review of the study, the data gap 

remains. 

• Comment: The status often analytical method reports for 1,3-D, 3-Chloroallyl Alcohol, and 3-

Chloroacrylic Acid, respectively, are identified as " in review"; however, only the methods for 3-

Chloroallyl Alcohol, and 3-Chloroacrylic Acid, are listed as "Anticipated Data Needed" in the 

Preliminary Work Plan EPA-HQ-OPP-2013-0 154-0007 document. What is the timeline for the 

agency to finish reviewing the data already submitted? 

• EPA Response: Data evaluation reviews for currently submitted Environmental Chemistry 

Methods/Independent Laboratory Validation studies will be completed prior to the registration 

review risk assessment. However, an initial review of study abstracts shows that all studies have 

recoveries within 70% to 120% and are therefore likely to be acceptable. 
5. Reference: Page 5, 1st bullet point. Document states: In the absence of data EPA will use an acute 

to chronic ratio (ACR) for the freshwater invertebrate to estimate a chronic endpoint for the 

estuarine/marine invertebrate. 

• Comment: In section 8.1.2 Drinking Water, it is stated that "1 ,3-D is not likely to be found in 

groundwater and surface water due to rapid degradation and volatility." In addition, applications 

by soil injection will minimize the potential for run-off from soil. This has been studied in a GLP 

runoff study under extremely vulnerable conditions for runoff (Heim et al., 2002 and GH-C 

5026). Therefore, we believe chronic exposure is unlikely, so for a screening assessment it would 

seem more pragmatic to use an acute to chronic ratio (ACR) for the freshwater invertebrate to 

estimate a chronic endpoint for the estuarine/marine invertebrate. 

• EPA Response: EPA will use the acute to chronic ratio to estimate chronic toxicity to 

estuarine/marine invertebrates. In addition, the Agency was not aware of the Heim eta! (2002) 

and will consider its relevance at the time of risk assessment. 

6. Reference: Page 5, 2nd bullet point. Document states: The European Food Safety Authority 

(EFSA) references a chronic freshwater fish endpoint for the fathead minnow of 0.032 ppm 

(EFSA 2009); however, this data would need to be submitted and reviewed by EPA to 

determine its suitability for use in risk assessment. 

• Comment: The study referred to by EFSA is MRID 451450-01. This study was reviewed by 

EFED in 2007 and was classified as 'invalid' (Memorandum dated March 13, 2007). While the 

limitations identified in the EFED review (low oxygen levels at the top test concentrations) are 

not in dispute, the EU reviewer did not consider this sufficient to prevent use of the study for risk 

assessment. Nevertheless, the European review used a more conservative interpretation of the 

data than the study authors or EFED when assigning the NOEC of32 ug a.i./L. 

• EPA Response: The Agency appreciates the clarification of this study. In the absence of an 

acceptable study, there is a data gap for a chronic freshwater fish study. 

7. Reference: Page 5, 3rd bullet point. Document states: If chronic data for a freshwater species 

become available EPA may be able to use an ACR to estimate a chronic endpoint for the 

estuarine/marine fish. 

• Comment: In section 8. 1.2 it is stated that ' 1 ,3-D is not likely to be found in groundwater and 

surface water due to rapid degradation and volatility.' In addition, applications by soil injection 

will minimize the potential for run-off from soil. This has been studied in a GLP runoff study 

under extremely vulnerable conditions for runoff (Heim et al., 2002 and GH-C 5026). Therefore, 

DAS believes chronic exposure is unlikely, so for a screening assessment it would seem more 

pragmatic to use an acute to chronic ratio (ACR) for the freshwater fish to estimate a chronic 

endpoint for the estuarine/marine fish. 

• EPA Response: In the absence of acceptable chronic data for the freshwater fish (discussed in 

previous response) it will not be possible to calculate an acute to chronic ratio. In addition, EPA 

was not aware of the Heim et al. (2002) study will continue its relevance at the time of risk 

assessment. 

8. Reference: Page 5, 4tb bullet point. Document states: Due to the fate properties of fumigants, in 

particular their high volatility, it is expected that birds will be exposed to fumigants in the vapor 

phase via inhalation. The standard toxicity studies with birds (i.e., acute oral and acute dietary) do 
not account for exposure to vapor phase pesticides. Therefore, to assess risks of 1,3-D to birds, 

EFED recommends that the Agency require a non-guideline avian inhalation study with the 

bobwhite quail (Colinus virginianus) for 1,3-D. A protocol should be submitted to the Agency for 

approval prior to initiating the study. 

• Comment: For the inhalation screening risk assessment (using STIR), EFED have estimated 

exposure to 1,3-D based on the calculated maximum vapor concentration in air at saturation (1.37 

x I Os mg/m3) following application of 1 ,3-D at 774.65 lb a.i./acre to the ground. This screening 

assessment is overly conservative as it assumes that 1,3-D is applied onto the soil surface and that 

the surrounding air will then become saturated. In fact, this is a physical, impossibility. Measured 

1 ,3-D air concentration values at the 15 em height above soil, are available from at least 11 field 

volatility studies conducted by DAS as well as numerous other studies conducted by other 

agencies. From these field studies, the highest measured air concentration is significantly (i.e. 3-4 

orders of magnitude) lower than the calculated saturated vapor concentration value even at 15 em 

above the treated field surface. Therefore, the decision on whether an inhalation study with birds 

is necessary should only be concluded following a refined risk assessment with measured air 

concentrations associated with the recommended 1 ,3-D application methods. 

• EPA Response: For the fumigant 1,3-D, a non-guideline avian inhalation study has been 

requested based on the available flux data and not on the results of the STIR model. Given that 

the primary route of exposure for fumigants to non-target wildlife is via inhalation, this study is 

necessary to accurately characterize risks. As discussed in the problem formulation, the risk 

assessment will use Tier II estimates of exposure using the PERFUM Model. 

9. Reference: Page 5, Sib bullet point. Document states: Therefore, to assess risks of 1,3-D to bees, 

EFED recommends that the Agency require a non-guideline acute honey bee vapor exposure study 

for 1,3-D, to be conducted in lieu of the normally required acute honey bee contact study. 

• Comment: As above, estimated exposure to 1,3-D based on the calculated maximum vapor 

concentration in air at saturation (1.37 x lOs mg/m3) is unrealistic and overly conservative as it 

assumes that 1,3-D is applied onto the soil surface and that the surrounding air will become 

saturated. Measured 1,3-D air concentration values are significantly lower than the calculated air 

saturation value, and so exposure of bees will be low, and transient especially considering that 

bees will not be foraging on treated fields since J ,3-D is applied to fallow soil. Furthermore, an 

acute honey bee vapor exposure study with I ,3-D has been conducted for the European 

authorities; this study demonstrated that 1,3-D will pose a low risk to bees exposed to realistic air 

concentrations. The study, referenced below, will be provided to EPA upon request. 

• EPA Response: EPA requests the referenced study be submitted for review. · 

10. Reference: Page 6, 1st bullet point. Document states: Therefore, to assess risks of 1,3-D to 

terrestrial plants, EFED recommends that the Agency require a non-guideline terrestrial plant 

vapor phase exposure study for 1,3-D, to be conducted in lieu of the normally required Tier ll 

vegetative vigor study that would fulfill guideline 850.4150. 

• Comment: As above, estimated exposure to 1,3-D based on the calculated maximum vapor 

concentration in air at saturation is extremely conservative as it assumes that 1,3-D is applied 

onto the soil surface and that the surrounding air will become saturated. Measured 1 ,3-D air 

concentration values are significantly lower than the calculated air saturation value, even at 15 em 

above the treated field surface. Therefore, exposure of non-target plants will be low, and 

transient. 
• EPA Response: As discussed in the problem formulation, the risk assessment will use Tier II 

estimates of exposure using the PERFUM Model. Without a terrestrial plant vapor phase 

exposure endpoint EPA will conservatively assume risk for terrestrial plants because of the 

herbicidal properties of 1,3-D .. Because that could potentially limit options in the ecological and 

endangered species risk assessment and lead to the need for mitigation, EFED continues to 

request this data. 

11. Reference: Page 6, Major uncertainties, Paragraph 1. Document states: The largest 

uncertainty ... on the likelihood of telone to runoff the field and the concentration of telone in the 

runoff. 

• Comment: As commented above, Telone®is a Trademark of The Dow Chemical Company 

("Dow") or an affiliated company of Dow. When Telone is used in the document, a reference to 

registered trademark should be made along with the appropriate modifier to indicate the specific 

product formulation referenced (i.e. Telone II, Telone EC, Telone C-17, or Telone C-35). 

• EPA Response: EPA will make the necessary changes in the planned risk assessment. 

12. Reference: Page 6, Major uncertainties, Paragraph 1. Document states: The largest uncertainty 

in quantifying aquatic exposure in this assessment will be the impact of tarps, especially bedded 

tarps, on the likelihood of telone to runoff the field and the concentration of telone in the runoff. 

Tarps and bedded tarps are thought to reduce or eliminate the potential for aquatic exposure but 

this is not demonstrated in field data and cannot be quantified. Another uncertainty is the impact of 

rainfall occurring close to the time of application on the runoff and volatilization rates of telone in 

the environment. 

• Comment: DAS understands the EPA's concern regarding the potential for enhanced 1,3-D 

runoff from tarped scenarios, as expressed on pg. 6 of the EFED memo under the heading "Major 

Uncertainties" (excerpt shown above), however, the data collected in the six completed GLP field 

volatility studies conducted for bedded tarped applications (drip and shank), as well as additional 

studies reported in the literature (Ashworth et al.,20 1 0; Gao et al., 2008; Qin et al., 2008, 

Papiernik ~tal., 2004, Gan et al., 2000), is adequate to fully characterize the fate and behavior of 

I ,3-D applied in bedded tarped situations. Furthermore, the EPA's perceived uncertainty relating 

to the impact of rainfall occurring close to the time of application has been addressed in a runoff 

study (Heim et al., 2002 and GH-C 5026) conducted under worst-case conditions for runoff, with 

heavy rainfall applied within 3 days of application, when peak 1 ,3-D emission from soil occurred. 

In addition to detailed measurements of 1,3-D concentrations in the soil gas in the bed and in the 

furrow, several studies include direct measurements of the 1,3-D flux from the tops and sides of 

the treated beds and in the furrows (van Wesenbeeck et al., 2007; Papiernik et al., 2004; Qin et 

al., 2008; Ashworth et al., 201 0). These measurements consistently indicate that tarps, especially 

high barrier tarps, can significantly decrease the flux of fumigants from the soil surface, and also 

that the majority of I ,3-D emission is from the bed, and not the furrow. The only exception to 

tarps resulting in higher emissions from the furrow can occur when high barrier tarps (eg. VIF, 

TIF) are used in raised beds, in which case the fumigant emissions from the furrow may exceed 

those from the bed, although in those cases, the overall emissions are much less than if lower 

barrier tarps (eg., LOPE, HOPE) were used (Ashworth et al.,2010; Papiernik, 2004). Qin et al. 

(2008) showed< 0.2% of total emissions came from the furrow from a drip application made 

under LOPE and VIF tarp, while Papiernik et al. (2004) showed 3.5% of total emissions came 

from the furrow for an application made under HOPE tarp. van Wesenbeeck et al. (2007) studied 

I ,3-D and chloropicrin emissions from an lnLine application made under LDPE tarp and found 
no measureable emissions of 1,3-D from the furrow while 2.2% oftotal chloropicrin emissions 

came from the furrow. The low measured emissions of 1,3-D from the furrow are further 

corroborated by the low concentrations of 1,3-0 in the furrow soil compared to the soil in the 

treated bed. A field volatility study in which lnLine was drip applied under tarped beds showed 

the peak soil concentration of 1 ,3-D in the furrow at the 6 inch depth was more than 1 Ox lower 

than the concentration at the 6 inch depth in the bed, while the concentration of chloropicrin was 

over SOx lower in the bed than in the furrow (van Wesenbeeck et al.,2007). Potential runoff from 

an application of I ,3-D under tarped beds can be conservatively estimated by assuming that the 

1,3-D present in shallow furrow soil (eg. top 2 em) is available for interaction with rainfall and 

potential runoff(Ahuja, 1990). The concentration of 1,3-D in shallow furrow soil can then be 

compared to the 1 ,3-D concentration in shallow soil from the runoff study which was conducted 

using 1,3-D shank applied 12 inches deep at 32.4 gpa, on a site with 5% slope, Hydrologic Group 

C soil, with runoff generated using a l- in-50 year simulated rainfall event at time of peak 1 ,3-D 

flux from soil (Heim et al., 2002). The concentration of 1,3-D in the soil in the furrow adjacent to 

a treated tarped bed in the study by van Wesenbeeck et al. (2007) is significantly less than the 

1 ,3-D concentration in soil gas from the top 2 em of soil from the runoff study by Heim et al. 

(2002), suggesting that significantly less 1 ,3-D is available for runoff from a bedded tarped 

application than from a broadcast shank study. The maximum concentration of 1,3-D in shallow 

soil in the runoff study was >20x higher than the maximum soil concentration in the furrows of 

the bedded tarped study. The maximum concentration of 1,3-D in the edge-of-field runoff water 

observed in the runoff study was 17.2 ppb. Since surface water runoff can potentially extract 1,3-

D entrained in shallow soil, then a 20x reduction in the concentration of 1 ,3-D in shallow soil 

would translate to an approximately 20% reduction in runoff water concentration, or <1 ppb in 

this case. The example described above demonstrates that the potential concentration's of 1,3-D 

in runoff water from a drip-applied, tarped, bedded application, can be easily evaluated using 

readily available data, in a realistic yet sill protective manner. Furthermore, the assumptions made 

in this example can be verified by a new field volatility study using PicCior 60 EC applied by 

drip application to beds covered in TIF tarp, that will be available in early 2014 (Ajwa et al., 

Study #2013HA1) and which will include measurements of soil gas in the beds and furrows. 

• EPA Response: EPA agrees with the line of reasoning presented for arguing aquatic exposure 

from tarped applications is significantly less than aquatic exposure from untarped applications. 

However, the conclusions that quantify aquatic exposure rely heavily upon Heim, et al., 2002 

which is purported to be a GLP study but has not been submitted to or reviewed by the Agency. 

Without Agency review of this study and further characterization of aquatic exposure, the 

quantification of aquatic exposure remains an uncertainty. 

13. Reference: Page 7, Paragraph 1. Document states: 1,3-D is commonly formulated as a 

pressurized gas, liquid ready to use, and emulsifiable and tlowable concentrate. 

• Comment: 1,3-D is a liquid at ambient temperatures. It is only formulated in ready-to-use liquid 

and emulsifiable concentrate formulations. 

• EPA Response: EPA appreciates the clarification and will make the necessary changes in the 

planned risk assessment. 

14. Reference: Page 7, Paragraph 2. Document states: 1,3-D has no residential uses but is registered 

for non-agricultural, preplant use on golf course turf, ornamental and/or shade trees, ornamental 

herbaceous and non-flowering plants, and ornamental woody shrubs and vines. The only post-plant 

use for which 1,3-D is registered is in vineyards. This post-plant use is classified as a food-use. 
• Comment: Preplant uses on golf course turf, ornamental and/or shade trees, ornamental 

herbaceous and non-flowering plants; and ornamental woody shrubs and vines are agricultural 

uses. 1,3-D uses in turf farm and field grown nursery plant material production are also preplant 

agricultural uses. Registered non-agricultural uses of 1 ,3-D are only for nematode control in 

established golf course turf and athletic fields. Besides the current post-plant use in vineyards for 

which 1;3-D is registered, Interregional Research Project Number 4 (IR-4) has requested 

establishment of a tolerance in 40 CFR part 180 for residues of 1 ,3-D including its metabolites for 

use on pineapple. Once approved, this would also be classified as a food use. 

• EPA Response: EPA appreciates the clarification and will make the necessary changes in the 

planned risk assessment 

15. Reference: Page 8, Use characterization, Paragraph 2. Document states: On many labels, 

neither maximum annual application rate nor maximum number of applications per year is 

specified .... Uses on corn, ornamentals, recreational lawns, and tree nuts have one or more labels 

with neither maximum annual application rate nor maximum number of applications per year and 

no characterization of use was provided from the registrant. For these use patterns, conservative 

assumptions will be made regarding number of applications per year. No more than two 

applications per year are expected but clarification from the registrant would reduce uncertainty. 

• Comment: In addition to these comments, DAS is also submitting a spreadsheet with a 

comprehensive listing ofthe maximum annual application rates and the number of applications 

per year by crop use and by product. There are numerous errors in the PRD Label Data Report 

and in Section 3,Table 1, page 9 of the EFED Memo which lists use sites and application 

information for 1,3-D. The spreadsheet that DAS is submitting with the comprehensive listing of 

application rates by crop should be the Agency's most reliable reference with regard to current 

uses and use rates. All 1,3-D labels state a maximum use rate. Corn is a field crop and a 

maximum use rates for field crops are present on all labels. Ornamentals are grown as nurseryproduced plant material and maximum rates for nursery use also appears on all labels. The 

maximum rate for recreational lawns (golf course and athletic fields) is listed on the Curfew® 

label. The maximum rate for tree nuts is specified under the fruit and nut crops category and a 

maximum rate is specified on all labels. 

• EPA Response: EPA appreciates the clarification and will make the necessary changes in the 

planned risk assessment 

16. Reference: Page 13, Paragraph 1. Document states: Though the RED provides the most recent, 

comprehensive assessment, maximum rates assessed do not reflect the current maximum rates for 

1,3-D used today. 

• Comment: Within these comments, DAS is submitting a comprehensive listing (spreadsheet) of 

the maximum annual application rates and the number of applications per year by crop use and by 

product. This should be the Agency's most reliable reference with regard to current uses and use 

rates. 

• EPA Response: EPA appreciates the clarification and will make the necessary changes in the 

planned risk assessment 

17. Reference: Page 13, Table 2 Footnote a. Document states: No inhalation data were available to 

allow for an inhalation risk assessment. In addition, no reproduction data were available to allow 

for a chronic risk assessment, though chronic risks are not anticipated given the relatively short 

field dissipation half-life of 1,3-D. 
• Comment It is agreed that chronic exposure and risk are not anticipated given the relatively short 

field dissipation half-life of 1,3-D. However, a bird reproduction study, via dietary exposure, has 

been conducted with 1,3-D and can be made available. The study, referenced below, will be 

provided to EPA upon request. Temple, D.L., Martin, K.H., Beavers, J.B. and Jaber, M. (2006) 

1,3 Dichloropropene: A reproduction study with the northern bobwhite. Wildlife International Ltd 

Study 379- 163. Dow AgroSciences Report 040491. 23 January 2006 

• EPA Response: The Agency will review any data submitted; however, this study does not 

represent the relevant exposure route for 1,3-D and may have limited utility in the risk 

assessment. 

18. Reference: Page 13, Table 2 Footnote c. Document states: Risk to terrestrial invertebrates has 

not been assessed. Vapor phase exposure was not considered as the corresponding toxicity data 

were not available. 

• Comment: An acute honey bee vapor exposure study has been conducted for 1,3-D and can be 

made available. The study, referenced below, will be provided to EPA upon request. Fussell, S. 

(2005) An inhalation toxicity test to determine the effect ofTelone II on adults of the honeybee, 

Apis mellifera, under laboratory conditions. Dow AgroSciences, unpublished report No. 050348. 

• EPA Response: EPA requests the referenced study be submitted for review. 

19. Reference: Page 14, Paragraph 2. Document states: The 2010 memorandum reports on 

extensive groundwater monitoring by USGS showing that 1,3-D is not among the man-made 

chemicals found in ground water in karst areas (i.e., vulnerable groundwater areas where limestone 

bedrock is dissolved by acids in rainwater). 

• Comment: DAS agrees with the Agency recommendation for the following reasons. We concur 

with the assessment that 1,3-D is not among the chemicals found in ground water. EPA should 

consider the 5-region tap water monitoring study conducted in the USA in 2000- 2001 that 

monitored for 1,3-D and the CAAL and CAAC metabolites in high Telone use areas that were 

vulnerable to ground water contamination (DAS Report #GH-C 5372- van Wesenbeeck et al., 

2002). That study showed that leaching of 1,3-D and its metabolites was very sporadic (<3% of 

wells showing detections and all detections <0 .2 ppb ). The EPA should also consider the results 

of a similar tap water monitoring study conducted in Europe which showed that from more than 

5,000 groundwater samples testing for 1,3-D, CAAC, and CAAL in Europe, there were two 

detections of 0.12 ppb and 0.4 ppb in the alluvial·gravels of the River Tietar in the Caceres region 

of Spain (Terry, et al. 2008). This GLP study corroborated the conclusions of state and federal 

agency monitoring programs evaluated by the EPA which indicate that neither 1,3-D nor its 

metabolites pose a significant threat to groundwater in areas where Te1one is heavily used. 

• EPA Response: EPA has taken the 5-region tap water monitoring study and the European tap 

water monitoring study into full consideration. 

20. Reference: Page 14, Paragraph 3. Document states: A drinking water assessment will be needed 

for registration review. Although surface water and groundwater concentrations of 1,3-D may be 

discountable, its degradates, 3-chloroallyl alcohol and 3-chloroacryllic acid, are residues of concern 

and have potential to be present in groundwater or surface water. 

• Comment: DAS respectfully disagrees with the assertion that 3-chloroallyl alcohol and 3-

chloroacryllic pose significant risks to groundwater or surface water based on the actual 
monitoring that has been conducted in high use areas with vulnerable soils. The rationale for this 

position is developed more completely in other sections of these comments. 

• EPA Response: The significance of risk from 3-chloroallyl alcohol and 3-chloroacryllic will be 

characterized in the drinking water assessment. Albeit infrequently, these degradates have been 

detected in groundwater. 

21. Reference: Page 22, Paragraph 1. Document states: Available data on the major degradate, 3-

chloroallyl alcohol, suggest that it is more toxic than parent 1,3-D to mammals, aquatic plants and 

freshwater fish. 

• Comment: The freshwater fish LC50 for 1 ,3-D is given as 1.08 mg/L (Table 7), and for 3-

chloroallyl alcohol is given as 0.986 mg/L (Table 8). From an ecotoxicological perspective this 

difference is not meaningfully different and so it would be more accurate to state 'Available data 

on the major degradate, 3-chloroallyl alcohol, suggest that it has similar toxicity to I ,3-D in 

freshwater fish. ' 

• EPA Response: EPA concurs and will make the necessary changes in the planned risk 

assessment. 

22. Reference: Page 22 and 23, Section 6.1 Effects to Aquatic Organisms. 

• Comment: The following additional studies conducted with Telone II are available and can be 

_provided upon request. 

o Marino, T.A., McClymont, E.L. & Yaroch, A.M. (2001): Telone II: An acute toxicity 

study with the rainbow trout, Oncorhynchus mykiss Walbaum .. Dow AgroSciences, 

unpublished report No. 011153,23 October 2001. 

o Marino, T.A., McClymont, E.L., Hales, C.A. & Yaroch, A.M. (2001). Telone II: An 

acute toxicity study with the daphnid, Daphnia magna, Straus. Dow AgroSciences, 

unpublished report No. 011154, 05 October 2001 . 

• Comment: The following additional studies conducted with the metabolites of 1 ,3-D are available 

and can be provided upon request. 

o Marino, T.A., Carr, M.S., Yaroch, A.M. (2007). 3-chloroacrylic acid: Toxicity to the 

early life stages of the Fathead Minnow, Pimephales promelas. Dow AgroSciences, 

unpublished report No. 071099. The test was conducted according to OECD Guideline 

210, fish early life stage toxicity test and USEPA OPPTS 850.1400 (Draft 1996). 

o Marino, T.A., Currie, R.J., Carr, M.S., Yaroch, A.M. (2007). 3-chloroacrylic acid (1: 1 

cis/trans): A 21 day chronic toxicity study with the daphnid Daphnia magna. Dow 

AgroSciences, unpublished report No. 071106. OECD Guideline 211; USEPA OPPTS 

850.1300. 

• EPA Response: EPA requests the referenced studies be submitted for review. 

23. Reference: Page 25, Section 6.2 Effects to Terrestrial Organisms. 

• Comment: The following additional studies conducted with the metabolites of I ,3-D are available 

and can be provided upon request: 

o Gallagher, S.P., Grimes, J. & Beavers, J.B. (1999): Telone II: A dietary LC50 study with 

the Northern bobwhite. Dow AgroSciences, unpublished report No. 103-432, 26 August 

1999. 

o Gallagher, S.P., Grimes, J. & Beavers, J.B. (1999): Telone II: A dietary LC50 study with 

the Mallard. Dow AgroSciences, unpublished report No. 103-433, 26 August 1999. 

• EPA Response: EPA requests the referenced studies be submitted for review. 
24. Reference: Page 25, Table 10. 

• Comment: It appears that the endpoint for the rat acute inhalation study differs from the endpoint 

and study from HED for 1,3-D (HED number is 3.88 mg/L MRID 40220903). The HED endpoint 

should be used as this is also consistent with the HED memo and previous RED. 

• EPA Response: EPA appreciates the correction and will make the necessary changes in the 

planned risk assessment. 

25. Reference: Page 26, Paragraph 4. Document States: Based on evidence that mammals are more 

sensitive to the degradates than the parent, it is likely that birds are also more sensitive to the acid 

and alcohol degradates than to the parent. 

• Comment: 1,3-Dichloropropene and its degradates 3-chloroallyl alcohol and 3-chloroacrylic acid 

have a similar order of mammalian acute toxicity. The acute oral toxicity of 1,3-D to rats ranges 

from 150 mg/kg/day (combined males and females) in one study to 224 mg/kg/day (females) in 

another study. The acute oral toxicity of the degradates is similar to that of 1 ,3- D: 141 mglkg 

(males) and 91 mglkg (females) for 3-chloroallyl-alcohol and 224 mglkg (males) and 91 mglkg 

(females) for 3-Chloroacrylic Acid. All of these values fall in toxicity category II so the 

chemicals are by definition similar in their acute toxicity. 1,3-D is more irritating versus the 

degradates and is also sensitizing whereas the degradates are not. Therefore, it can be concluded 

that it is likely that birds have similar sensitivity to the parent, acid and alcohol degradates. 

• EPA Response: EPA agrees that 1,3-D and the degradates have roughly equivalent toxicity values 

and will make the necessary changes in the planned risk assessment. 

26. Reference: Page 27, last Paragraph. Document States: Applications through aboveground 

irrigation lines may result in formation of puddles of treated irrigation water and also contact with 

the foliage of terrestrial plants, which could expose terrestrial animals via drinking water and onfield plant food resources. 

• Comment: 1,3-D is applied preplant, and so contact with on-field plant foliage will not occur 

since plants will not be on-field at the time of soil treatment. The one exception is soil fumigation 

with CordonTM for use in established vineyards using drip irrigation systems that are trellis 

mounted or located on the soil surface, or buried. Label precautions state that vineyard berms 

must be free of excessive weed growth and undecomposed plant material that could impair the 

contact of treated water with the soil surface and that the soil must be in good seed bed condition 

free of clods. Therefore, exposure of I ,3-D to terrestrial plants and animals via soil fumigation 

with Cordon is mitigated with label restrictions already in place. 

• EPA Response: EPA agrees that the label restrictions mitigate 1 ,3-D exposure to terrestrial plants 

and animals via soil fumigation with Cordon TM and will amake the necessary changes in the 

planned risk assessment. 

27. Reference: Page 28, Paragraph 3. Document States: Based on acute toxicity studies with the 

laboratory rat, the degradates, 3-chloroallyl alcohol and 3- chloroacrylic acid, are more toxic than 

the parent (LD50 of91 mg/kg-bw for the degradates versus 224 mglkg-bw for the parent). 

• Comment 1,3-Dichloropropene and its degradates 3-chloroallyl alcohol and 3-chloroacrylic acid 

have a similar order of mammalian acute toxicity. The acute oral toxicity of 1,3-D to rats ranges 
from 150 mglkg/day (combined males and females) in one study to 224 mg/kg/day (females) in 

another study. The acute oral toxicity of the degradates is similar to that of 1 ,3-D: I 41 mg/kg 

(males) and 91 mglkg (females) for 3-chloroallyl-alcohol and 224 mglkg (males) and 91 mg/kg 

(females) for 3-Chloroacrylic Acid. All of these values fall in toxicity category II so the 

chemicals are by definition similar in their acute toxicity. 1,3-D is more irritating than the 

degradates and also demonstrates sensitization potential in guinea pigs whereas the degradates are 

non-sensitizing. 

• EPA Response: EPA agrees that 1,3-D and the degradates have roughly equivalent toxicity values 

and will make the necessary changes in the planned risk assessment. 

28. Reference: Page 28, Paragraph 3. Document States: Additionally, acute oral and acute 

inhalation toxicity data are available for the laboratory rat (MRIDs 40220901 and 40220903, 

respectively). The data indicate that for mammals, 1,3-D is more toxic via inhalation exposure than 

via oral exposure (oral LD50 = 224 mglkg-bw, acute inhalation LD50 89.7 mg/kg-bw [converted in 

STIR from LC50 3.31 mg/L]) 

• Comment: 1,3-D is less toxic via inhalation exposure [EPA Cat. IV for inhalation vs Cat. II for 

oral; see Doc. D410115 Table A.2]. The model inputs used by EPA need to be reassessed. It's 

also noted that the correct inhalation LC50 value is 3.88 mg!L in agreement with the HED 

scoping document. The relevant MRID is 40220903. 

• EPA Response: EPA will review the conversion for accuracy and re-evaluate the toxicity 

discussion. 

29. Reference: Page 28, Paragraph 3. Document States: For birds, based on 1,3-D's vapor pressure 

and calculations using STIR, the maximum 1-hour vapor inhalation dose for birds is 17,300 mglkg. 

• Comment: See comments above. Estimation of air concentrations using STIR are exaggerated. 

Consequently, the conclusion that potential daily inhalation exposure is substantially greater than 

the potential daily drinking water exposure (which is also greatly exaggerated in SIP), may be 

incorrect. · 

• EPA Response: EPA recognizes the conservative nature of STIR and will use the PERFUM 

Model to estimate exposure in the risk assessment. The Agency will also make the necessary 

changes in the planned risk assessment to more accurately reflect the rationale for requesting 

vapor phase exposure studies for birds, terrestrial invertebrates, and terrestrial plants (i.e., existing 

flux data for 1 ,3-D). 

30. Reference: Page 29, Paragraph 2. Document States: 3~hloroallyl alcohol and 3- chloroacrylic 

acid, however, are more persistent, less volatile, and highly mobile. These chemical properties 

indicate substantial risk for drinking water exposure via groundwater. 

• Comment: DAS respectfully disagrees with the Agency assertion for the following reasons: The 

extensive Tap Water Monitoring studies in the USA and Europe (referenced above) demonstrate 

that neither the parent 1,3-D or the metabolites pose a risk to drinking water. 

• EPA Response: The significance of risk from 3-chloroallyl alcohol and 3-chloroacryllic will be 

characterized in the drinking water assessment. Albeit infrequently, these degradates have been 

detected in groundwater. 
31. Reference: Page 29, Paragraph 5. Document States: No domestic monitoring data is available 

for 1,3-D degradates, 3-chloroallyl alcohol, or 3-chloroacryUic acid. 

• Comment: The statement/entry should be corrected. Domestic monitoring data are available for 

1,3-D and metabolites and have been previously submitted. 

• EPA Response: EPA acknowledges this is inaccurate and will correct the mistake. 

32. Reference: Page 30, Paragraph 4. Document States: For detailed descriptions of the field 

volatility studies reviewed for chloropicrin, see Appendix C. Field Volatility Study Summaries. 

• Comment: Reference to chloropicrin here is likely unintended. As developed in other sections of 

these comments, numerous field volatility studies for 1,3-D have been conducted. 

• EPA Response: EPA will correct the mistake. 

33. Reference: Page 43, Study Title: Acute Avian Inhalation, Rationale for Requiring the Data. 

Document States: In order to determine toxicological responses associated with vapor exposure to 

1,3-D, an acute avian inhalation study is being requested. 

• Comment: The decision on whether an inhalation study with birds is necessary should only be 

concluded once a more realistic risk assessment is performed with the existing toxicity 

information assumptions, but using measured air concentrations associated with the 

recommended 1,3-D application methods. · 

• EPA Response: As discussed previously, the rationale for requesting the acute avian inhalation 

data is based on available flux data for 1 ,3-D, which represent measured air concentrations 

associated with the recommended 1,3-D application methods. 

34. Reference: Page 44. Study Title: Acute Honey Bee Vapor Exposure Study, Rationale for 

Requiring the Data. Document States: EFED recommends that the Agency require a nonguideline 

acute honey bee vapor exposure study for 1,3-D, to be conducted in lieu of the newly proposed 

requirements for oral toxicity tests including adult and larval honey bees. 

• Comment: An acute honey bee vapor exposure study with 1,3-D has been conducted for the 

European authorities and this study demonstrated that 1,3-D will pose a low risk to bees when 

exposed to realistic air concentrations. This study report is available and will be provided to the 

EPA upon request. 

• EPA Response: EPA will review this data upon submission. 

35. Reference: Page 56. Appendix B - SIP and STIR Outputs 

• Comment: For the inhalation screening risk assessment (using STIR), EFED have estimated 

exposure to 1,3-D based on the calculated maxirnum vapor concentration in air at saturation (1.37 

x 1 Os mg/m3) following application of 1 ,3-D at 774.65 lb a.i./acre to the ground. The application 

rate needs clarification; this rate does not appear in Table 1, Page 9 of the EFED Memo. 

Furthermore, this screening assessment assumes that 1,3-D is applied onto the soil surface as a 

broadcast application and that the surrounding air will become saturated. As described above this 

is a physical impossibility. Additionally, measured 1,3-D air concentration values are available 

from a numerous field volatility trials; from these field studies, the highest measured air 

concentration is significantly (i.e. 3-4 orders of magnitude) lower than the calculated air 
saturation value, even at 15 em above the treated field surface. Therefore, measured air 

concentrations, associated with the recommended 1,3-D application methods, should be used in 

the refined assessments for birds and mammals. 

• EPA Response: EPA appreciates the error noticed in Table 1 of the EFED Memo transmitting the 

Problem Formulation for 1,3-D. The 774.65 lb a.i./A use is for preplant nursery stock and 

ornamental woody vines and will be added to the table. As discussed previously, EPA will use 

the Tier II PERFUM Model to estimate exposure from 1 ,3-D use in the risk assessment. EPA 

agrees that, for the purposes of the fumigant 1,3-D, the STIR and SIP models are not 

representative. 

36. Reference: Page 56. Appendix B - SIP and STm Outputs 

• Comment: It appears that the endpoint for the rat acute inhalation study differs from the endpoint 

and study from HED (HED number is 3.88 mg/L MRID 40220903). The HED endpoint should 

be used as this is also consistent with the HED memo and previous RED. 

• EPA Response: EPA appreciates the correction and will make the necessary changes in the 

planned risk assessment.