### UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON D.C. , 20460
PC Co de: 02900 I DP Barcode: 416850


### MEMORANDUM February 20, 2014 Subject: EFED Response to Comments Subm itted 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: Eliza beth Riley, Biologist 

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# /14 Andrew Shelby, Environmental

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### Environmenta l Risk Branch 6

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## d Environmenta l Fate and Effects Divi s ion (7507P) 

### Through: Mark Corbin, M.S., Branch Chief

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Envirorunental Risk Branch 6 Environmental Fate and Effects Divi s ion (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 EF ED response s are detailed below:

1. 

### Reference: Page 4, 1st bullet point Aerobic Soil Meta bolism 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 est imates vary greatly, 14 days and 45 days. This results in a high 90th percentile average of94 days, t he 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 AgroScien ces (1-4) and other researchers (5-6). These studies indicate that the degradation of 1,3 -D in s oi l is due to both biotic and abiotic mechanisms. As well as to the two studies referenced in EPA-H Q-OPP-2013-0154, two additional GLP st udie s (3-4) provide degradation half-lives for 1,3 -D on 6 soils. Examinat ion 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 pres ents 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 soi ls is approximately 7 days and Jess than 20 days in sandy so il s . Other researchers (7-13) have also reported laboratory aerobic half lives within the ranges outlined below.• EPA R esponse: EPA will consider all GL P ae ro bic so il metabolism data on l ,3-d s ubmitted and requests the two aerobic soi l 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 r eference to 3-chloroally alcohol and 3-chloroacrylic acid, document states: There is uncertainty relati ng 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 aero bic so il stu dy 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 flo o ded with water and was pre-incubated under anaerobic conditions for approx 3 months. 2. The s ample containers were closed to the atmosphere. The design of the system for studying the an aerobic me tabolism of I ,3-D and its. alcohol and acid metabolites (1) in fact mimics a groundw ater 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 hal f-lives are s ummari zed in the table below. • EPA Response: EPA appreciates the comments submitted by Dow AgroSciences on the subject of so il 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 submitt ed but not at the maximum rate. Due t o the high maximum application rate and the multi

pathway dissipation of 1,3-D, it is 

### important t o fully characterize each use pattern that can result in significa ntly different dissipation and volatility behavior.

• Comment: EPA anticipates additional d ata needs for another field volatility study , yet a significant b ody of research on I ,3

-D emissions is available from the reg ist rant and from studies published in peer-reviewed journals

. The list of available 1 ,3-D flux studie s has been provided previously. A total of II studies were c onducted prior to the last re-registration of I,3-D ("Pre2000"). Numerous additional studies hav e been conducted by academia and government agencies (e.g
. USDA-ARS) since 2000, primarily for the purpose of testing fumigant emission reduction s trategies in light of the phase-out of methy l 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, an d for both drip applied and shank applied products at the maximum use rate. Table 1 shows a su mmary of the maximum allowed broadcast application rates according to DAS labels , and Tabl e 2 shows the tarp flux studies that have b een 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 Ra te x% I ,3-D in Product). Telone II an d Telone C-17 are rarely applied under tarp howe ver, so the majority of tarped field volatility stud ies have been conducted using Telone EC or InLine® wh ich are applied through a drip irrigati o n 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 Tel one 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 lab e ls. The three tarped field volatility studies using InLine that DAS has submitted to the EPA were conducted at 1, 3-D app lication rates of I5.9 gpa (Study#98 0 070), 16 gpa (Study# GH-C 5081 , and 22
. 7 gpa (Study #110708). Although non e of these stu dies were conducted at the maximu m label application rate, the study a p plication rate ' s were chosen to represent the 'high end' of what growe rs typically use, and represents well over 95% of appli cati ons made by growers. T he hi gh app li cation rates l isted on all 1,3-D labels are des ignated for use in nurseries on l y, r esu lt ing in a mi nimal number of acres treate d a nnuall y as c ompa r ed with f u migant use in crop produ ction . Expected e miss ion s fro m 1,3-D applications ma de at higher app li cation rates than were used in the submitted studies can be determined by extrapo lating the measured emissions from a giv e n study by the ratio of the maximum 1,3-D applicati o n 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 depende nt on the starting so i l concentration for the range of soil concentrations expected under typical a p plication rates i n the fie l d (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 emiss i o n s. Furthermore, DAS w ill submit a fi e l d vo lati li ty study using drip app li ed Te1one EC at 40 gp a under LOPE tarp (A j wa, 2009) that h as not yet been submitted to the EPA, an d wou ld meet th e requirement of a tarped fie ld vo lati li ty s tu dy at the maximum app licat io n rate. That st

u dy was i n fact conducted at an application rate greater than the max imum label rate for Tel one EC and for InLine , the two DAS 1,3-D products that are app lied under tarp. Add i tio na ll y a fie ld volatility study that measured 1,3-D emiss ions from broadcast shank-applied PicC ior 60 (at 29.8 gpa) under TIF (Tota ll y Impermeable Film) tarp (Ajwa, 2012) will be available for submission to the EPA, as will a field volatility st udy us ing dri p -applied PicClor 60 EC (at 48.9 gpa) on TIF tarped beds ( Ajwa et al. , Study #2013HAI, exp ected completion January 2014). The P icCior 60 EC drip st udy will be co nducted o n tarped beds (30 inch beds on 48 i nch centers) and w ill include estimates of flux from both tarpe d an d untarped s urfaces, in tr eated beds and in furrows. P i cClor 60 an d PicClor 60 EC ar e form ul ations containing no minally 57% w/w c hl oropicrin and 37% w/w 1,3-dichl oropropene. G i ven th e robust datas et of GLP fie ld vo lati li ty stu di es where 1,3

-D was either d r ip or s hank app l ied under tarp (with o ne stu dy exceedi n g the max. label rate), as well as numerous publi s hed s tu dies, the dissipation of 1 ,3 -D in both bro adcast and bedded tarped scenarios is well characterized. DAS contends th at little additional know ledge or un derstand i ng of the fate and diss ipation of 1 , 3-D will be obtained by conducting an other volati li ty stu dy u nder tarp. • EPA Response: EPA agrees that volatility is s ufficiently c haracterized by prev i ously submi tted data and the final work p lan will be ame nded to remove the requirement for a field vo la ti lity study. 

### 4. Reference: Page 4,**4t~~** 

### bullet po i nt
. Environmental Chemistry Methods/Independent Laboratory Vali dation (OCSPP Guideline 850.6 1 00)
. Document s tates: A study has been submitted th at will fu lfill this data requ irement if found to be acceptable. Pending R eview of the study, the data gap remains.

• Comment: The s tatu s often a nalytical method re ports for 1,3-D, 3-Chloroallyl Alcohol, and 3- Chloroacrylic Acid, respectively, are identified as " i n review"; however, on l y the methods for 3- Chl oroallyl Alcohol, and 3-Chlo roacrylic Acid , are liste d as "Anticipated Data Needed " in the P re lim i n ary Work Plan EPA

- HQ

-OPP-2013-0 154-0007 d ocument. What is t he t ime line for the ag ency to fin is h reviewing the d a ta already s ub mitte d ? • EPA Re s po nse: Data evaluation reviews for curr e ntly submitted Environmental Chemistry Methods/Independe nt Lab oratory Validation stud ies w ill be completed pri o r to the registration review risk assessment. However , an initial revi ew of study abstracts shows that all stud i es have recoveries w ithin 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 Wa ter, it is s tated that "1 ,3-D is not likely to be found in groundwater and surface water due to rap id 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 exp osure 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. • E PA 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 F ood Safety Authority (EFSA) references a chronic freshwater fish endpoint for the fathead minnow of 0.032 ppm (EFSA 2009); however, this data would n eed 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 E FED 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 whe n 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 s urface water due to rapid degradation and volatility.' In addition, applications by soil injection w ill minimize the potential for run-off from soi l. This has been studied in a GLP runoff study under extremely vulnerable conditions fo r runoff (Heim et al., 2002 and GH-C 5026). Therefore, DAS believes chronic exposure is unlike ly, 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 accepta ble chronic data for the freshwater fish (discussed in previous response) it will not be po ssible to calculate an acute to chronic ratio. In addition, EPA was not aware of the Heim et al. (2002) s tudy will continue i ts 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. T herefore, 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 pro t ocol should be submitted to the Agency for approval prior to initiating the study.

• Comment: For the inhalation screening risk asse s sment (using STIR), EFED have estimated exposure to 1,3-D based on the calcula ted 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. Meas ured 1 ,3 -D air concentration values at the 15 em height above soil, are available from at least 1 1 field volatility studies conducted by DAS as well as numerou s other s tudies 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 cal culated saturated vapor concentration value even at 15 em above the treated field surface. Therefore, the decision on whether an inhalation study w ith birds is necessary should only be concluded following a refined risk asses sment with measured air concentra tions 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 ofthe STIR model. Given that the primary route of exposure for fumigants to no n-target wildlife is via inhalation, this study is necessary to accurately characterize risks. As discussed in the problem formulation, the risk assessment will u se Tier II estimates of exposure usin g 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 req u ired acute hon ey 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 so il surface and that the surro unding 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 soi l. 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 concentra ti ons. 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, expos ure of n on-target plants will be low, and transient.• EPA Response: As discussed in the prob lem formulation, th e risk assessment will use Tier II 

### est ima tes 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 cou l d potentially limit options 

### in the ecolog ical and endangered spec ies risk assessment and lead to the need for mitigation, EFED continues to request this data. 

### 11. Reference : Page 6, Major uncertainties, P a ragraph 1. 

### Document states: The largest uncertainty
...on the likelihood of telone to ru noff the field and the concentration of telone in the runoff

.

• Comment: As commented above, Telone® i s 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 al ong with the appropriate modifier to indicate the specific p roduct 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, P a ragraph 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 can not 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 c oncern regarding the potential for enhanced 1,3-D runoff from tarped scenarios, as expresse d on pg. 6 of the EFED memo under the heading "Major U ncertainties" (excerpt shown above), however, the data collected in the six comp leted GLP field volatility studies conducted for bedded tarped applications (drip and shank), as well as additional studies r eported in the literature (Ashworth et al.,20 1 0; Gao et al., 2008 ; Qin et al., 2008, P ap iernik**~ta l.,**  2004, Gan et al., 2000), is adequate to fully characterize the fate and behavior of I ,3-D applied in bedded tarped situation s . Furthermore, the EPA's perceived uncertainty relating to the impact of rainfall occurring close t o the time of application has been addressed in a runoff study (Heim et al., 2002 and GH-C 502 6) 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. I n 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). T hese measurements cons istently indicate that tarps, especially h ig h 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 cas es, the overall emissions are much less than if lower barrier tarps (eg., LOPE, HOPE) were u sed (Ashworth et al.,2010; Papiernik, 2004). Qin et al. (2008) showed< 0.2% of total emission s 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 f rom the furrow for an application made under HOPE tarp. van Wesenbeeck et al. (2007) studied I ,3-D and chloropicrin emiss ion s from an lnLine application made under LDPE tarp and foundno measureable emissions of 1,3 -D from the furrow while 2.2% oftotal chloropicrin emissions came from the furrow. The low measured em issi o ns of 1,3-D from the furrow are further corroborated by the low concentrations of 

### 1 ,3- 0 in the furrow soil compared to t he soil 

### in the treated bed. A field vo lati l ity study in which l nL i ne was drip applied und er tarped beds showed the peak soil co ncentration of 1,3-D in the furrow at the 6 inch depth was more than 1 Ox lower than the concentration at the 6 inc h depth in the bed, while the concentration of chloropicrin was over SOx lower in the bed than in the furrow (van Wese nb eeck 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 fo r interaction with rainfall and potential runoff(Ahuja , 1990). The co ncentration of 1,3-D in shallow furrow soil can then 

### be compared to the 1 ,3- D concentration i n shallow s oil 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 genera ted using a l- in-50 ye ar simu lated 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 s tudy by van Wesenbeeck et al. (2007) is significantly less than the 1 ,3-D concentration in so il gas from th e top 2 em of soil from the runoff study by Heim et al. (2002), suggesting that significantly le ss 1 ,3-D is available for run off from a bedded tarped application than from a broadcast shank study. The maximum concentration of 1,3-D in shallow soil i n 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 run off study was 17.2 ppb. Since s urface water runoff can potentially extract 1,3- D entrai ned in shall ow soil, then a 20x reduction in the concentration of 1 ,3 -D in shallow soil wou ld translate to an approximately 20% reduction in runoff water concentration, or < 1 ppb in this case. The examp l e described above demon st rates that the potential concentration's of 1,3-D in ru noff water from a drip-applied, tarped, bedded application, can be easily evalu ated using readily available data, in a realistic yet s ill protective manner. Furthermore , the assumptions made in this examp l e can be verified by a new field vo latility study u sing PicCior 60 EC ap p lied by drip applicatio n 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 reaso ning presented for arguing aquatic exposure from tarped applications is s ignificantly less th an aquatic exposure from untarped applications. However, the conclusions that quantify aquatic exposure rely heavil y upon Heim, 

### et al., 2002 which is purported to be a GLP study but has not been submitted to or reviewed by the Agency. Wi thout Agency review of this study and further character ization of aquatic exposure, the quantification of aquatic exposure remains an un c ertainty. 

### 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 liqu i d and emu lsifiable co ncentrate formulat i o n s. • EPA Re spon se: EPA appreciates the clarificatio n and will make the necessary c hanges in the planned ri sk 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 fi elds. Besides the current post-plant use in vineyards for which 1;3-D is registered, Interregional R esearch 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 cla rification and will make the necessary changes in the planned risk assessment 

### 15. Reference: Page 8, Use characterization, P aragraph 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 rat e 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 clarific ation 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 i s submitting with the comprehensive listing of application rates by crop should be the Agency 's most reliab le 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 (go lf 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 spec ified on all labels. • EPA Response: EPA appreciates the cla r ification and will make the necessary changes in the planned risk assessment 

### 16. Reference: Page 13, Paragraph 1. Docum e nt states: Though the RED provides the most recent, comprehensive assessment, maximum rates a s sessed do not reflect the current maximum rates for 1,3 -D used today.

• Comment: Within these comments, DA S is s ubmitting a comprehensive listing (spreadsheet) of the maximum annual application rate s and the number of applications per year by crop use and by product. This should be the Agency's mo st reliable reference with regard to current uses and use rates. • EPA Response: EPA appreciates the cl arification 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 add ition, 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 dis s ipati o n half-life of 1,3-D. However, a b ird reproduction s tudy, 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 requ est. Temple , D.L., M artin, K.H., Beavers, J.B. and Jaber, M. (2006) 1,3 Dichloropropene: A reprodu ction study w ith the northern bobwhite. Wildlife International Ltd Study 379- 163. Dow AgroScienc es Report 040491. 23 January 2006 • EPA Response: T he Agency will review any data submitted; however , this study does not represent the relevant exposure route for 1,3-D an d 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 cons idered 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 lab oratory conditions. Do w 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 shou ld 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 s h owed 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 s tudy 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). Thi s GLP study corroborated the conclusions of state and federal agency monitoring programs evaluated by the EPA which ind icate that neither 1,3

-D nor its metabolites pose a significant threat to groundwater in areas where Te1one is heavi l y 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 an d 3-chloroacryllic acid, are residues of concern and have potential to be present in groundwater or s u rface water.


### • Comment: DAS respectfully disagrees with the a ssertion that 3-chloroallyl alcohol and 3- chloroacryllic pose significant risks to groundwater or surface water based on the actualmonitoring that has been conducted in h igh use areas with vulnerable soils. The rationale for this position is developed more comp letel y in other sections of these comments. • EPA Response: The significa nce of risk from 3

-chloroallyl alcohol and 3-chloroacryllic will be characterized in the drinking water asse s sment. Albeit infrequent ly, these d egradates 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 to xi c than parent 1,3-D to mammals, aquatic plants and freshwater fish.

• Co mment: T h e freshwater fish LC50 for 1 ,3

- D is given as 1.08 mg/L (Table 7), and for 3- ch loroallyl alcohol is given as 0.986 mg/L (Table 8). From an ecotoxico log ical perspective this difference is not meaningfully different and so it wou ld be more accurate to state 'Available data on the major degradate, 3-chloroa ll y l alc ohol, suggest that it has similar toxicity to I ,3-D in freshwater fish. ' • EPA Response: EPA concurs and will m ake the necessary changes in the planned risk assessment. 

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

• Comment: The following add i tional stu d ies conducted with Telone II are avai lab le and can be

_ p rovided upon request. o Marino, T.A., McClymont, E.L. & Yaroch , A.M. (200 1) : Telone II: An acute toxicity study with the rainbow trout, O n corhynchus mykiss Walbaum

.. Dow AgroSc iences, unpublished report No
. 011153 ,23 October 2001. o Marino, T.A. , McC l ymont, 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 stu d ies 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 M innow, Pimephales promelas. Dow AgroSciences, unpubli shed report No. 07 1099
. The test was conducted according to OECD Guideline 210, fish early life stage toxic ity test and USEPA OPPTS 850.1400 (Draft 1996)
. o Marino, T.A., Currie, R.J., Carr, M.S., Yaroch, A.M. (2007). 3

-ch loroacrylic acid (1: 1 cis/trans): A 21 day chronic toxicity study w ith the daphnid Daphnia magna. Dow AgroSciences, unpub li shed rep ort 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 Terrestr ia l Organisms.

• Comment: The following additional stu dies conducted with the metabolites of I ,3 -D are available and can be provided upon request: o Gallagher, S.P., Gr imes, J. & B e avers, J.B. (1999): Te lone II: A dietary LC50 study w ith the Northern bobwhite. Dow AgroSciences, unpublished re port No. 103-432, 26 August 1999. o Gallagher, S.P., Grimes, J. & B e avers, J
. B
. (1999): Telone II: A dietary LC50 st udy with the Mallard. Dow AgroSciences, unpublished report No
. 103-433, 26 A ugust 1 999. • EPA Response: EPA requests the referenced studies be submi tted for review.

### 24. Reference: Page 25, Table 10.

• Comment: It appears that the endpoint for the ra t acute inhalation study differs from the endpoint and stu dy 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 correc tion a nd 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 degradate s 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 (female s) 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 v alues 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 tox icity 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 t reated irrigation water and also contact with the foliage of terrestrial plants, which could expose ter restrial animals via drinking water and onfield plant food resources.

• Comment: 1,3 -D is applied preplant, an d 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 fu migation with CordonTM for use in established vineyards us ing drip irriga tio n systems that are trellis mou nted or located on the soil surface, or buried

. Label precautions state that vineyard berms must be free of excessive weed growth and undec omposed 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 restrict ions mitigate 1,3 -D exposure to terrestrial plants and animals via soil fumigation with Cordon TM an d 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 s imilar order of mammalian acute toxicity. The acute oral toxicity of 1,3-D to rats rangesfrom 150 mglkg/day (combined males and females) in one st udy to 224 mg/kg/day (females) in another study. The acute oral toxicity of the degradates is s imil ar 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 o f these values fall in toxicity category II so th e chemicals are by defi nition similar in their acute toxicity. 1,3-D is more irritatin g than the degradates and also demonstrates sensitization potential in guinea pigs whereas the degradates are non-sensitizin g. • EPA Response: EPA agrees th at 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. Docum ent States: Additionally, acute oral and acute inhalation toxicity data are available for the la boratory rat (MRIDs 40220901 and 40220903, respectively)

. The data indicate that for mam mals, 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 scop in g document. The relevant MRID is 40220903. • E PA Response: EPA will review the conversion for accuracy and re- evaluate the toxicity discussion. 

### 29. Reference: Page 28, Paragraph 3
. Docume nt 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. Estimat ion of air concentrations using STIR are exaggerated

. Consequentl y, the conclusion that poten t ial 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 con servat ive nature of STIR and will use the PERFUM Model to estimat e exposure in the risk as sessment. The Agency will also make the necessary changes in the planned risk assessment to more accurate ly 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 w ith 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 meta bolites 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 asse s sment. 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-chlor oacryUic 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 Stat es: For detailed descriptions of the field volatility studies reviewed for chloropicrin, see Appendix C. Field Volatility Study Summaries

.

• Comment: Reference to chloropicrin here is like l y unintended. As developed in other sections of these comments, numerous field vo latility studies for 1,3 -D have been condu cted. • EPA Response: EPA w ill correct the mistake.


### 33. Reference: Page 43, Study T itle : 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 applica t ion methods. · • EPA Response: As discussed previously, the rati o nale for requesting the acute avian inhalation data is based on available flux data fo r 1 ,3-D, w h ich represent measured air concentration s associated with the recommended 1,3-D application methods. 

### 34
. Reference : Page 44
. Study Title: Acute Honey Bee Vapor Expos u re 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 ad ult and larval honey bees.

• Comment: An acute honey bee vapor exposure s tu dy with 1, 3

-D has been conducted for the European auth orities 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 thi s data upon s ubmission. 

### 35
. Reference: Page 56. Appendix B

- SIP and STIR Outputs

• Comment: For the inhalation screening risk asse s sment (using STIR), EFED have estima ted exposure to 1,3-D based on the calcula ted 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 ofthe 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. Additionall y , 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 airsaturation value, even at 15 em above th e trea ted field s urface. Therefore, measured air 

### conc entrations, associated with the recommended 1 ,3-D 

### application methods , should be used in the refined assessments for birds and ma mmals. • 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 previou s ly, EPA will us e the Tier II PERFUM Model to estimate exposure f rom 1 ,3-D use in the r is k assessment. EPA agrees that, for the purposes of the fumigant 1,3-D, the STIR and SIP models are not r epresentative. 

### 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 cons istent with th e HED memo and previous RED. • EPA Res ponse: EPA appreciates the correction and will make the necessa ry changes in the pl anned risk assessment.