## 1 OFFICE OF PREVENTION, PESTICIDES AND TOXIC SUBSTANCES 

### UNITED ST **AT ES ENVIRONMENT**  **AL PROTECTION A**  **GENCY**

**WA SHINGTON D.C., 20460** 



## PC Code: 060101 Chemical: Thiabendazole DP Barcode: D 410805

DATE: February 24 , 2014 MEMORANDUM SUBJECT: Thiabendazole: Drinking Water Assessment for P roposed N ew U ses of the

fungicide Mertect ® 

## 340
- F (EPA Reg. No. 100
- 889 ) as a seed treatment
. TO: Tony

Kish, PM 22 (7505P) Rosemary

Kearns Reviewer (7505P) Registration Division, Fungicide Branch Bonnie Cropp
- Kohlligian Elis sa Reaves, Branch Chief Registration Action Branch 4 Health Effects Division (7509P) FROM: James K. Wolf, Environmental Scientist

Environmental Risk Branch 3 James A. Hetrick, Ph.D. Senior Scientist Rosanna Louie
- Juzwiak , RAPL Environmental Risk Branch 3 Environmental Fate and Effects Division (7507C) Dana Spatz, Branch Chief Environmental Risk Branch 3 Environmental Fate and Effects Division (7507C)
S yn genta Crop P rotection has submitted an application to amend the Mertect ® 

## 340
- F (EPA Registration No. 100
- 889 ) label with the add ition of seed treatment uses on vegetables and small grains crops 1 

## and amend the label to add a higher rate on so ybeans. A Tier 1 drinking water

1 V egetable, root (except sugarbeet); Subgroup 1B, Onion, bulb, Subgroup 3
- 07A; Brassica, h ead and stem, Subgroup 5
- A; Vegetable, Cucurbit Group 9; Alfalfa; Spinach (including baby); and small grain cereals (wheat, barley, oats, rye, and triticale).

## 2

assessment was conducted for thiabendazole in surface water using the FIRST mod el and Tier 1 ground w ater using PRZM
- GW for t he proposed new seed treatment uses and soy bean rate increase
. The Estimated Drinking Water Concentrations ( EDWC ) for the proposed new uses and the application rate increase for so ybeans are based on the maximum s eed treatment use rate of 0.15 lb a.i./ A planted to a depth of 1 inch
. For this assessment EFED also assumed that there was onl y 1 crop ping season per y ear. These proposed rates are lower than the currently registered wheat seed treatment rate of 0.20 lb a.i./A , which results in the highest EDWCs
. The highest EDWCs in surface water for t hiabendazole were previously prepared for the 2002 Reregistration Eligibility Document (RED) 2 

## , using the Tier 1 GENEEC model (which has since been replaced b y the FIRST model 3 

## ) and the SCI
- GROW model (which has been replaced with PRZM
- GW 4 

## ) for groundwater
. Input parameters used b y the models also follow ed current model input guidance
. The surface water and groundwater EDWCs for the proposed new uses and reevaluated here for the wheat seed treatment rate are presented in this document ( **Table 1** ). Based on the proposed new uses of thiabendazole, t he Tier 1 peak (acute) and annual average (chronic and cancer ) EDWCs in surface s ource drinking water are 2.85 and 0.35 μg/ L, respectivel y . For the wheat seed treatment , the reassessed surface water concentrations are 3.80 and 0.47 μg/L for peak (acute) and annual average (chronic and cancer ) , respectivel y. T he peak concentrations are higher than previously determined for the RED primarily due to changes in the conceptual model (GENEEC vs
. FI RST) (e.g., differences of field size and shape and the implementation of the I ndex Reservoir) and difference in fate input values for modeling
. The chronic EDWCs are lower than before due the inclusion of the I ndex Reservoir (e.g., size and flow through the reservoir). For ground water as a source drinking water, the PRZM
- GW model
- estimated peak concentration s are 0.46 μg /L and 0.61 μg/L for 100 y ear simulation , respectivel y , for the propos ed new uses and the wheat seed treatment use . Breakthrough average concentrations o f thiaben da zole in groundwater could not be estimated because no b reakthrough of thiaben da zole into groundwater was predicted. **EFED recommends that 3.80 μg/L**  **(peak) and 0.47 μg/L**  **( annual average**  **) concentrations**  **be used in the human health dietary risk assessment.** 

2 http://www.epa.gov/oppsrrd1/REDs/thiabendazole_red.pdf , page 33. 3 http://www.epa.gov/oppefed1/models/water/ 4 

### http://www.epa.gov/oppefed1/models/water/index.htm#przm_gw

## 3

**Table 1. Summary of Tier 1 Estimated Drinking Water Concentrations in Surface and Ground Water for the**  **New Uses and Previously Assessed Wheat Use.**

New Use s and Reassessment **Thiabendazole Peak Concentration**  **Annual Average** Surface Water Crop (app rate lb a.i./A) Model **μg/L**

New Uses (0.15) FIRST 2.85 0.35 Wheat (0.20) FIRST 3.80 0.47

From RED Peak Concentration 56
- day Average Wheat (0.20) GENEEC 2.40 a 

### 1.55 a 

### Groundwater Highest Daily Concentration Average

Concentration after Breakthrough New Uses (0.15) PRZM
- GW 0.46
- Wheat (0.20) PRZM
- GW 0.62
- a EDWCs reported in the 2002 RED. 

## USE CHARACTERIZATION The seed treatment rates for the proposed new uses of thiabendazole are summarized in **Table 2** 
. Mertect 340
- F is applied to seeds as a water - based slurry using standard seed treatment equipment. Treated seeds may be planted at any

time of the year. While it is assumed that o nly one applica tion ( i.e. , one planting of treated seed) may be made per ye ar , in some regions, more than one crop cy cle may

occur per y ear. M aximum seed treatment rates as defined by the label are given in **Table 2** 
. The proposed use rate for seed treatments are expressed as mg (milligram s ) of active ingredient (a.i
. ) per seed with the per seed rate s rang ing from 0.00 2 to 0.10 mg a.i. per seed or as fluid ounces (fl oz) of product per 100 pounds of seed (or 100 cwt) with rates ranging from 2.6 to 5.8 fl (fl oz) p er 100 cwt ( **Table 2**  )
. **Table 2**  **. Maximum Application Rates for Proposed New Seed Treatment Uses of Thiabendazole**  **a** 

### Crop or Crop Group **Crop Group ID Max. Seed Treatment Rate**  **mg a.i./seed fl oz product per** 

**100 lb seed lb a.i. per** 

**100 lb seed** Alfalfa NA 0.004 5.8 0.18578 Cereals, Small Grain b 

### Barley NA 0.03 2.6 0.08328 Oat NA 0.03 3.4 0.10891 Ry e NA 0.03 3.2 0.1025 Triticale NA 0.03 2.6 0.08328 Wheat NA 0.03 3.1 0.09930 Brassica, head and stem Subgroup 5A 0.002

- - Cucurbit Group 9 0.1

- - Onion, bulb Subgroup 3
- 07A 0.002

- - Root vegetables (except sugar beet) Subgroup 1B 0.002

- -

## 4

**Table 2**  **. Maximum Application Rates for Proposed New Seed Treatment Uses of Thiabendazole**  **a** 

### Crop or Crop Group **Crop Group ID Max. Seed Treatment Rate**  **mg a.i./seed fl oz product per** 

**100 lb seed lb a.i. per** 

**100 lb seed** Spinach NA 0.006

- - Soy beans (rate increase) NA 0.0302

- 0.020
a M ertect 340
- F 889 MAS 0510 AMEND 0313 H i L ite
- dt/df 3/15/13; 000100
- 00889.20130318 M ertect _340
- F
- A mend
- 0313
- H i L ite .PDF


### . b “Small grains” is not designated as an EPA crop group


### . 

## The proposed new use rates, on a per acre basis, vary depending on the crop, the size of seed, seed treatment rate (mg a.i. per seed), and the seeding rate per acre. To determine the potential thiabendazole loading within a given acre, upper bound seeding rates for the available crops were used using information from a report prepared b y t he Biological and Economic Analy sis Division (BEAD) f or some of the proposed crops (Becker and Ratnay ake, 2011 5 

## ) . Based on the proposed wheat use, the maximum seed treatment rate on a pound of active ingredient per acre (lb a.i./A) basis would be 0.15 lb a.i./A. The seeding rates for the relevant crops are summarized in **Table 3** 
. In correspondence from the registrant, S yn genta 6 

## , it was indicated that the following would be added to the label “regardless of ty pe of application (seed treatment, soil, or foliar **),** do not appl y more than 0.15 lb a.i./ A (68 g a.i. /A) per y ear. ”
**Table 3**  **. Proposed use rates for thiabendazole seed treatment for the new uses. Mertect**  **® 340**  **- F**  **EPA Reg. No. 100 -**  **889 [ e**  **- subm**  **ission #4085; see Table 2**  **] Crop Group**  **Representative Crop**  **s Seed Treatment Rate**  **Range of Seeding**  **Rates (**  **# seeds/**  **A )**  **b Ma**  **x. Appl. Rate**  **( lb a.i./**  **A )**  **c fl. oz.**  **product/100 lb seed**  **a mg** 

**a.i./seed a**  Al falfa 5.8 0.004 3,405,000 0.030

Cereals (small grains) Barley 2. 6 0.03 1,222,000 to 1,300,000 0.081 to 0.086 Oats 3.4 0.03 1,305,000 0.0863 Ry e 3.2 0.03 1,962,000 0.130 Triticale 2.6 0.03 1,744,00 0 0.115 Wheat Wheat, winter Wheat, forage 3.1 0.03 2,250,000 d 600,000 to 1,350,000 1,740,000 **0.149**

0.040 to 0.089 0.115 Brassica , head and stem Broccoli 0.002 8,297 to 210,845 0.00004 to 0.0009 Cabbage 0.002 7,260 to 98,010 0.00003 to 0.00043 Bulb Vegetables Onion 0.002 87,120 to 1,254,528 0.00038 to 0.0055 Cucurbit Vegetables Cucumber Muskmelon Squash, summer Squash, winter 0.1 4,840 to 139,392 2,420 to 34,848 1,452 to 15,374 2,723 to 7,260 0.0011 to 0.031 0.00053 to 0.0077 0.00032 to 0.0034 0.00060 to 0.0016 Spinach
- 0.006 196,020 to 653,400 0.0026 to 0.0086 Root Vegetables Beet, garden 0.002 261,360 to 2,090,880 0.0012 to 0.0092

5 Becker, Jonat

han and Ratnayake, Sunil. 2011 **.** Acres Planted per Day and Seeding Rates of Crops Grown in the United States. Biological and Economic Analysis Division (BEAD), Office of Pesticide Programs, United States Environmental Protection Agency. 6 E
- Mail from P. McC ain (Syngenta) to T. Kish (USEPA). (Dated 05/31/13).

## 5

**Table 3**  **. Proposed use rates for thiabendazole seed treatment for the new uses. Mertect**  **® 340**  **- F**  **EPA Reg. No. 100 -**  **889 [ e**  **- subm**  **ission #4085; see Table 2**  **] Crop Group**  **Representative Crop**  **s Seed Treatment Rate**  **Range of Seeding**  **Rates (**  **# seeds/**  **A )**  **b Ma**  **x. Appl. Rate**  **( lb a.i./**  **A )**  **c fl. oz.**  **product/100 lb seed**  **a mg** 

**a.i./seed a**  (except sugarbeet) Carrot Horseradish Radish Parsley Parsnip 104,544 to 2,090,880 9,680 to 10,249 418,176 to 1,045,440 52,272 to 1,568,160 87,120 to 435,600 0.00046 to 0.0092 0.00004 to 0.00005 0.0018 to 0.0046 0.00023 to 0.0069 0.00038 to 0.0019 Soybeans
- 0.0302 50,000 to 250,000 0.0033 to 0.017

a Proposed label MERTEC 340
- F 889 MAS 0313 HILITE

– dt/df 3/15/13 (Density = 4.1 lb a.i./gallon of product; 42.3 % active ingredient (a.i.).[e
submission #4085; MRI D 4907800] b Becker and Ratnayake. 2011. c mg a.i./seed * seeds/ A * (1 lb/453.59 g) * 1 g/1000 mg = lb a.i./ A
. d Conservative maximum seeding rate proposed by Syngenta. e Current label EPA Reg. No. 100
- 889 April 5, 2013. Maximum rate of soybeans is 0.16 fl oz. per 100 lb of seed = 0.00512 lb a.i./100 lb of seed
. 

## ESTIMATED DRINKING WATER **CONCENTRATIONS Previous Drinking Water Assessments**  A s part of the Thiabendazole RED 7 

## , a drinking water assessment was conducted to predict th iabendazole EDWC from seed treatment for dry peas, chickpeas, lentils, wheat, and corn. The Tier 1 EDWCs from GENEEC were 2.4 μg/L and 1.55 μg/L for the peak and average 56
- day concentration, respectively , for the maximum wheat seed treatment of 0.20 lb a.i./ A [or 3.6 fl oz a.i. per 100 pounds of seed and 90 lb of seed per acre]
. The Tier 1 SCI
- GROW model EDWC w as less than 0.01 μg/L. Section 18 s for Brussels sprout, cabbage, and cauliflower in California (D326593) and Washington (D327512) assumed the same drinking water exposure concentrations as the RED. For a new use assessment for seed treatment on dry peas @ 1 inch planting depth (D315436), the Tier 1 drinking water concentrations using FIRST , which was developed to replace GENEEC for drinking water assessment, was 2.0 μg/L for acute and 0.5 μg/L for chronic exposure. For a new use on seed treatment on corn at an application rate of 0.0055 lb ai/A and 2 inch seed planting depth (D363978) , t he highest Tier 2 PRZM/EXAMS for thiabendazole were 0.0 18 μg/L, 0.00 48 μg/L, and 0.00 34 μg /L , for the peak, annual average and 30 y ear average concentrations, respectivel y . **ENVIRONMENTAL FATE SUMMARY** There ha ve been no additional environmental fate data submitted since the previous assessments. Pertinent phy sico
- chemical and environmental fate and transport properties of thiabendazole are summarized in **Table 4** 

7 http://www.epa.gov/oppsrrd1/REDs/thiabendazole_red.pdf , page 33.

## 6

Environmental fate studies show that thiabendazole is persistent and immobile ( **Table 4**  )
. Thiabendazole is stable to hy drol ys is and soil photoly sis and degrades slowly in aerobic (half

- life ~ 700 day s) and anaerobic soil environments (>200 day s) . Aquatic ph otol ysis, with a half life of 1.2 day s in clear water, appears to be the onl y significant degradation pathway
. Under anaerobic aquatic conditions thiabendazole showed no evidence of abiotic or biotic degradation but moved rapidly from water phase to the se diment phase. Thiabendazole binds tightly to soil due to its high soil/water partitioning coefficients (K oc 

## s > 1,000 mL /g oc 

## ), thus limiting the amount available for leaching into ground water and for solution phase runoff into surface water. With the high sorption capacit y, thiabendazole w ould be transported on eroded sediment. Sorption was weakl y correlated to organic carbon. Terrestrial field dissipation studies showed thiabendazole to be extremely persistent with no observable leaching. Vapor pressure an d Henry ’s Constant indicate that thiabendazole has a low potential to volatiliz e from soil and water. **Table 4**  **. Physical/**  **Chemical Properties ,**  **Environmental Fate Param eters**  **and Fish Bioconcentration of**  **Thiabendazole .** 

**Parameter Value**  **Description Source**  **(MRID #) Selected Physical/Chemical Parameters**  Molecular mass 201.1 g/mol
-- (Calculated) Molecular formula C 10 H 7 N 3 S
-- Vapor pressure (25°C) 3.45 x 10 - 9 mm Hg 4.0 x 10 - 9 mm Hg -- 48354601 Thiabendazole RED (2002) Henry’s Law Constant (25°C) 3.26 x10 - 11 atm - m 3 /m ol
-- (Calculated) Dissociation Constants pK a1 = 4.5 pK a2 = 12.01 -- 48354604 40947302 Aqueous solubility Buffered solution (25  C) at pH 5: 30 mg/L pH 7: 28 mg/L pH 9: 28 mg/L Water: 22.74 mg/L Buffer solution (20  C) at: pH4: 79.82 mg/L pH7: 22.77 mg/L pH10: 23.75 mg/L -- 40947301

48354601 48354604
Log octanol
- to - water partition coefficient (log K OW ) 1.61 @ Room temperature = 16.6°C 48254601 48354604 **Persistence** Hy drolysis half

- life (22  C) Stable @ pHs 5, 7, 9 Rates a of transformation were extrapolated resulting in t 1⁄2 ( 198 days @pH 7 ) far beyond the length of the study (30 days) 41265301 (D245780; 02/04/99) Aqueous photolysis half

- life (22.5 to 23.2  C) 1.2 days 96 hour study @ pH5 43328305 Soil photolysis half

- life (25  C) Stable
-- 41297301 41397302 Aerobic soil metabolism half
- life (25°C) 688 days Registration Document D245780 One soil. 41791201

## 7

**Table 4**  **. Physical/**  **Chemical Properties ,**  **Environmental Fate Param eters**  **and Fish Bioconcentration of**  **Thiabendazole .** 

**Parameter Value**  **Description Source**  **(MRID #)** Anaerobic soil metabolism half
- life (25°C) 211 day Only degradate detected was benzimidazole in a 90 day study. (max 13.7 % AR;). 41559601 Anaerobic aquatic metabolism half
- life No evidence of biotic or abiotic degradation. Rapidly moved from water phase to the sediment phase. 00 122888 00 070753 Aerobic aquatic metabolism half
- life [dissipation half

- life ] (25  C) -- Study requirement waived (D169687; 12/30/92) 41559601 **Mobility** Freundlich soil
- water partition coefficients (K F ); organic carbon
normalized Freundlich coefficients (K FOC ) K F ( m L/g) / K F oc ( m

L/g oc ): (soil textural class) 2.49 / 1,104: (sand) 15.97/3,992: (sandy loam) 21.75/1,812: (silt loam) 269.6/22,467: (clay) 

### Mean = 7,343 mL/g oc



### Median = 2,902 mL/g oc 41170102

**Field Dissipation** Terrestrial field dissipation half
- life in upper 6 inch soil layer; (max. depth of observed leaching) t 1⁄2 = 1100 days; (6 inches). t 1⁄2 = 990 and 1444 days; (12 inches) t 1⁄2 = 833 and 1093 days: (6 inches). Winter wheat/loamy sand/WA Soybean and bare ground/sandy loam/IL Soybean and bare ground/sandy loam/GA 43187201 43187202 43187201
Octanol/Water Partition Coefficient (logP ow ) 1.61
-- 48354604 **Fish Bioconcentration** Fish bioconcentration factors (steady
state); depuration rate 86.5 (whole); 19.7 (edible), 747 (viscera), 3
- day depuration: 96% in viscera and 50% in edible tissue. Low bioconcentration potential in edible tissue, some potential to bioaccumulate in viscera but with rapid depuration 41631801 42022701

a Transformation rates of thi a bendazole: pH 5 (
- 0.0019 days - 1 ); pH 7 (
- 0.0035 days - 1 ); pH 9 (
- 0.0026 days - 1 ) 

## Transformation Products Three degradates were identified in the aqueous photoly sis study (benzimidazole
- 2
- carboxamide as a major degradate; benzimidazole and benzimidazole
- 2
- carbox yl ic acid as minor degradates), two minor degradates were identified in the aerobic soil metabolism study (benzimidazole and 5
- hy drox yt hiabendazole (maximum observed 0.33%) ), and one major degradate was identified in the anaerobic soil metabolism study ( benzimidazole ) ( **Appendix 1 Table 1** ). The metabolite 5
- hy drox yt hiabendazle and benzimidazole are included in the tolerance dietary exposure for food (40 CFR 180.242 8 

## ) , but not in cluded in drinking water. T he common name, chemical names, CAS No., molecular formula and mass, chemical structure, and maximum and final percent of applied radioactivity

(AR) of the major degradates are summarized in **Appendix 2**  **Table 1**
. The only degradate that was anal yzed for in the terrestrial field dissipation studies (TFD) is benzimidazole, since it is a major metabolite in a soil study (anaerobic soil metabolism). R esults TFD stu dies showed that benzimidazole was not detected in any soil lay ers. No data were available for the other three degradates to verify their presence in the field. However, since they comprised a

8 http://www.gpo.gov/fdsys/pkg/CFR
- 2005
- title40
- vol23/xml/CFR
- 2005
- title40
- vol23
- sec180
- 242.xml

## 8

relativel y small fraction (less than 10%) of the total applied radioactivit y in the laboratory studies, EFED believes that an y t ransformation to these degradates in the fields will also be negligible. While photodegradation is a route of degradation, the dissipation of thiabendazole is expected to be dependent on wa ter condition s ( e.g ., sediment loading, depth, etc.) a ffecting sunlight penetration. For example, thiabendazole should not persist in clear shallow water bodies, but will be more persistent in turbid and/or deeper waters, particularl y those with long h ydro logical residence times. Due the low vapor pressure and burial of treated seeds when planted, volatilization is not expected to be an important route of dissipation. Spray drift, foliar dissipation, and wash
- off are also not expected to be important for s eed treatment s. It is also assumed that the intent is to bury all seed, which would reduce the presence of a.i. at the surface and keep losses due to runoff at minimum. **Monitoring Data** There are no detections of thiabendazole reported in the California Department of Pesticide Regulation (CDPR) Surface Water 9 

## Monitoring D ata base available and it is not include d in CDPR Groundwater Protection List 10



## . Thiabendazole is not include d in the surface water database collected in the USGS National Water Quality Assessment (NAWQA) 11 

## Program. There were no detections of thiabendazole reported in groundwater (49 samples from CA, DE, FL,MD, NJ) in USGS NAWQA 12 

## data warehouse with limits of dete ction <0.06 μg/L
. **Simulation Modeling Surface Water**  This Tier I drinking water assessment utilizes the Tier I FQPA Index Reservoir Screening Tool (FIRST, Version 1.1.1, released 03/ 26 / 08) to assess surface water. Exposure was estimated for a seed tr eatment application at 0.15 lb a
. i
. /A, which is to be the maximum annual application rate allowed on the Mertect ® 

## 340
- F label , and 0.20 lb a.i./ A for the wheat seed
- treatment use. Description of the FIRST model c an be found on the EPA’s website at: http://www.epa.gov/pesticides/science/models_pg.htm
. Model Inputs The fate data used in modeling ha ve been selected ( **Table 5**  ) according to current modeling guidance 13 

## . Using current guidance for preparing the environmental fate data for input into the EFED water models result s in slightly different values from the previous assessments. Previous drinking water assessments used the single aerobic soil metabolism half
- life value of 688 d ay s and the median K oc 

## of 2,903 mL /g oc 

## which does not agree with current model input guidance (see Table 4). While inputs ( average vs. median K oc 

## and aerobic soil metabolism half
- life) may have

9 http://www.cdpr.ca.gov/docs/emon/surfwtr/index.htm ; searched January 27, 2014. 10 http://www.cdpr.ca.gov/docs/legbills/calcode/040101.htm#a6800 ; searched Janua ry 27, 2014. 11 http://infotrek.er.usgs.gov/nawqa_queries/jsp/swmaster.jsp ; searched January 27, 2014. 12 http://infotrek.er.usgs.gov/nawqa_queries/jsp/gwmaster.jsp ; search January 27, 2014. 13 http://www.epa.gov/oppefed1/models/water/input_parameter_guidance.htm

## 9

changed due to update d guidelines, the conclusions concern ing the fate of thiabendazole does not change. For PRZM
- GW the application date ( i.e., planting date) is assumed to occur 7 day s before the emergence date as specified in each scenario. The assessment assumes that 100 percent of the a.i. comes off the seed a nd is available for runoff or leaching (EFED, 1999 14 

## ). Thus, the runoff prediction of thiabendazole is expected to be conservative.
**Table 5**  **. Summary of environmental fate param eters for thiabendazole and**  **other values used for m**  **odeling FIRST**  **, PRZ M**  **- GW, and**  **SCI -**  **GROW .** 



### Parameter **Value or Range Value Used**  **Source** Solubility (water) a 28 mg/L 28 mg/L MRID 40947301 Hy drolysis t 1/2 stable at pH 7 0 day a

- surface water 198 days b

- groundwater MRID 41265301 Aquatic Photolysis a t 1/2 29 hours 1.2 days b MRID 43328305 Aerobic Soil Metabolism t 1/2 688 days (single value) 2,064 (3 x 688) 2064 days a,b MRID 41791201 (DER 2) Aerobic Aquatic Metabolism a t 1/2 Stable (0 day) b No data available K oc See Table 3 Mean = 7,343 mL/g oc a, b Median = 2,902 mL/ g oc c MRID 41170102 Application Method Granular D Model option Application Rate New uses Wheat rate (RED) 0.15 lb a.i./A

0.20 lb a.i./A Max rate Number of Applications per Year
- 1
- Watered In
- No
- DEPI (depth of soil incorporation ) 1 to 2 inches 1 and 2 inch b Beale, 2007 Percent Crop Area (PCA) d All agriculture (0.91) 0. 91 b EFED, 2011 d
a Input for FIRST b Input for PRZM
- GW c Median K

oc value used for SCI
- GROW (earlier assessments used median K oc of 2903 mL/g oc ). d http://www.epa.gov/oppefed1/models/water/pca_adjustment_dwa.html 

## The Tier 1 surface water EDWCs for thiabendazole are summarized in **Table 6** 
. Maximum values are shown in bold in **Table 6** 
. Output from FIRST for the two planting depths are located in **Appendix 3** 
. A percent crop area (PCA) 15 

## of 0.91 was used.

14 EFED, 1999. Standard Method of Determining the Leachability of pesticides from treated seeds. July 30, 1999, USEPA, OPP, EFED, Ar lington, VA. 15 http://www.epa.gov/oppefed1/models /water/pca_adjustment_dwa.html

## 10

**New Uses** F or the proposed new seed treatment rate of 0.15 lb a.i./A **,** t he EDWCs for thiabendazole in surface water source of drinking water are 2.85 and 0.35 μg/L , for the peak and annual average concentrations, respectively
. **Updated Drinking Water Concentrations for Wheat**  **Use Rate**  F or the wheat seed treatment ra te of 0.20 lb a.i./A **,** t he EDWCs for thiabendazole in surface water source of drinking water are 3.80 and 0.47 μg/L , for the peak and annual average concentrations, respectivel y. Table 6. FIRST Model Estimated drinking water concentrations (EDWCs) of thiabendazole for proposed maximum annual application rate of 0.15 lb a.i./A and two seeding depths and for the Maximum Wheat Rate Assessed in the RED (0.20 lb a.i./A). **Crop Scenario**  **E DW**  **Cs (μg a.i./L)**  **a** 

### Peak **Annual Average** All New Uses 0.15 lb a.i./A Generic granular/seed treatment scenario

with 1
- inch soil incorporation **2.85 0.35**  Generic granular/seed treatment scenario with 2
- inch soil incorporation 1.42 0.18 Wheat Rate 0.20 lb a.i./A Generic granular/seed treatment scenario

with 1
- inch soil incorporation 3.80 0.47 Generic granular/seed treatment scenario with 2
- inch soil incorporation 1.90 0.23

a All agriculture PCA = 0.91


## Ground Water The Tier 1 drinking water assessment use d the PRZM
- GW and SCI
- GROW models for predicting thiabendazole concentrations in groundwater source drinking water. PRZM
- GW The six standard PRZM
- GW scenarios 16 

## used in the groundwater simulations were developed to be representative of known vulnerabl e sites

— shallow, unconfined aquifers under an agricultural field with leaching prone soil and adequate precipitation and/or irrigation . O utput values represent pesticide concentrations that may be observed in private drinking water wells resulting from th e use of groundwater vulnerable to pesticide c ontamination. The results are expected to represent the upper bound values on the concentrations of thiabendazole that might be found in drinking water supplied by vulnerable groundwater sources. The selection and procedures for selecting model input parameters followed EFED model input guidance
.

16 Florida Citrus, Florida Potato, Wisconsin Corn, Georgia Peanuts, North Carolina Cotton, and Delmarva Sweet Corn

## 11

Ground w ater Concentrations PRZM
- GW is a graphical user interface (GUI) for running the P esticide R oot Z one M odel ( PRZM) to estimate exposure in a shallow, unconfined, aquifer following pesticide application to an agricultural field
. PRZM was developed b y the U.S. EPA to simulate the vertical movement of pesticides in the unsaturated soil, within and below the plant root zone, and extending to the water table using generally

available input data (Carsel et al., 1984 17 

## ). PRZM is also currentl y used b y EFED in combination with EXAMS 18 

## to estimate pesticide concentrations in surface water. Groundwater EDWCs with PRZM
- GW are simulated for 30 ( and 100 ) ye ars as done with PRZM/EXAMS for surface water. Unlike SCI
- GROW, estimated groundwater concentrations using PRZM
- GW are influenced b y both the soil and hydrology of the specific scenario. The input s for PRZM
- GW are summarized in **Table 5**
. In the previous drinking water exposure assessment, a single aerobic soil metabolism half
- life value of 688 day s ha d been used. EFED model input guidance recommends multiply ing a single half
- life value times 3 (2064 day s) to account for variabilit y of half
- lives among different s oils. Also f ollowing current model input guidance, the mean K oc 

## (7,343 mL /g oc 

## ) is used with the PRZM
- GW
. In contrast, the median Koc is used in SCI
- GROW. The highest daily concentration of thiabendazole in predicted b y PRZM
GW as groundwater source drinki ng water is 0.46 and 0.62 μg/L for the proposed new uses and the existing wheat use rate, respectivel y ( **Table 7** ). Complete breakthrough was not achieved for any of the scenarios with both 30 and 100 y ears of simulation. Therefore, the average concentration after breakthrough was not determined. This modeling shows that the leaching of thiabendazole to groundwater is not expected to be a significant dissipation pathway as concentrations estimates ranged from essentiall y 0 to less than 1 μg/L , with a 100 y ear of simulation. Representative output from PRZM
- GW is presented in **Appendix 3**
. **Table 7. Thiabendazole EDWC PRZM -**  **GW (version 1.03) and updated scenarios.**  **Scenario Length of** 

**Simulation (years)**  **High Daily**

**Value a**  

### (μg/L) **Avg BT**

**(μg/L) a**  

### Avg BT tim **e**

**(days)** Application Rate 0.15 lb a.i./A Delmarva 30 <10 - 8



### - b



### - b



### “ 100 0.0038
- - FL citrus 30 0.0029
- -
“ 100 **0.46**
- - FL potato 30 <10 - 10



### - -
“ 100 2.1x10 - 5



### - - GA C oast P l 30 <10 - 16



### - -

17 Carsel, R.F.; Smith, C.N.; Mulkey, L.A.; Dean, J.D; Jowise, P. Users Manual for the P esticide R oot Z one M odel (PRZM) Release 1. December 1984. EPA
- 600/3
- 84
- 109. Environmental Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Athens, GA, 227 pp. 18 B urns, L. A. 2002. EXAMS ( Ex posure A nalysis M odeling S ystem) V ersion 2.98.04.06. Environmental Research Laboratory. U. S. Environmental Protection Agency. Athens, GA.

## 12

**Table 7. Thiabendazole EDWC PRZM -**  **GW (version 1.03) and updated scenarios.**  **Scenario Length of** 

**Simulation (years)**  **High Daily**

**Value a**  

### (μg/L) **Avg BT**

**(μg/L) a**  

### Avg BT tim **e**

**(days)**

“ 100 <9.0x10 - 7



### - - NC C oast P l 30 <6 x 10 - 7



### - -
“ 100 0.028
- - WI C entral S ands 30 3.2 x 10 - 14



### - -
“ 100 0.00015
- -

Application Rate 0.20 lb a.i./A FL citrus 100 0.62
- - a Hy drolysis half

- life @ pH7 = 198 days for all runs. b Breakthrough not achieved during simulation s (30 and 100 years)
. 

## SCI
- GROW A SCI
- GROW estimate of the thiabendazole concentration in groundwater is also provided as required b y the implementation of the PRZM
- GW model. SCI
- GROW (SG23.exe, version 2.3, dated 09/10/08) is a Tier I, regression
- based model that provides a groundwater screening exposure value to be used in determining the potential risk to human health from drinking water contaminated with the pesticide. SCI
- GROW does not consider multiple y ears of use. The SCI
- GROW estimate considers the highest rate as a single appl ication, 0. 1 5 and 0.20 lb a
. i
. per acre for thiabendazole
. The environmental fate values used are listed in Table 5. The thiabendazole concentration s w ere estimated to be 9.43 x 10 - 3 

## μg/L and 1.26 x 10 - 2 

## μ g/ L , the proposed maximum new use rate and the current wheat seed treatment rate, respectivel y , ( **Table 8**  ). SCI
- GROW output is given in **Appendix 3.**

**Table 8**  **. SCI -**  **GROW estimated ground water concentration for thiabendazole**  **at the ma**  **ximu m proposed rate**  **new use rate and the m aximum wheat use rate**  **.** Concentration ( app rate 0.15 lb a.i./A) 9.43 x 10 - 3 

### μg/L Concentration ( app. rate 0.20 lb a.i./A) 1.26 x 10 - 2 

### μg/L

## 13

**Appendix 1 .** 

**Appendix 1 .**  **Table 1 . Thiabendazole degradates identified in Environmental Fate Studies.**  **Degradates Hydrolysis**  **Photolysis (water)**  **Photolysis**

**(soil) Aerobic** 

**Soil Anaerobic** 

**Soil Terrestri** 

**al Field** Benzimidazole X X X a 

### 5
- hydroxythiabendazole X Benzimidazole
- 2
- carboxamide X a 

### Benzimidazole
- 2
- carboxylic acid X Unidentified [ 14 

### C] X X Unknown 1 X 14 

### CO 2 

### X a

- major degradates (>10%)

## 14 **Appendix 2**  **. Appendix**  **2. Table**  **1 . Thiabendazole and Its Environmental**  **Degradates**
**Nam e**  **Chemical Name CAS No.**  **Form ula**  **Molecular Mass Chemical Structure**  **Study Type Maximum %AR**  **(day) Final %AR** 

**(study length) PARENT**  Thiabendazole 2
- (4
- thiazolyl )
- 1H
benzimidazole 

### CAS No.: 148
- 79
- 8 Formula: C 10 H 7 N 3 S MW **:** 201.25 g/mol Aerobic Soil Metabolism Anaerobic Soil Metabolism 56.8% 78% (@ day 90)



### TRANSFORMATION PRODUCTS Thiabendazole
- 5
- hydroxy 5
- hydroxythiabendazole; 2
- (4
- Thiazolyl)
- 5
- benzimidazolol CAS No.: 948
- 71
- 0
Formula: C 10 H 7 N 3 S MW: 217.25g/mol Aerobic Soil Metabolism 0.33% max observed through study

Benzimidazole 1H
- Benzimidazole CAS No.: 962
- 28
- 7 Formula: C 7 H 6 N 2 MW: 118.05 g/mol Aq
. Photoly s is (m inor) Aerobic Soil Metabolism Anaerobic Soil Metabolism Terrestrial F ield Dissipation - 2.2% 13.7%

- 6.49% (avg.)

0.17% 5. 5 % (@ day 90

-

## 15 **Nam e**  **Chemical Name CAS No.**  **Form ula**  **Molecular Mass Chemical Structure**  **Study Type Maximum %AR**  **(day) Final %AR** 

**(study length)** Benzimidazole carboxylic

acid 1H
- Benzimidazole
- 2
-

carboxylic acid CAS No.: Formula: C 8 H 6 N 2 O 2 MW: 162.15 g/mol Aq. Photolysis (m inor) 9.98% @ 96 hrs

Benzimidazole
- 2
- carboxamide 1H
- Benzimidazole
- 2
- carboxamide CAS NO. 5805
- 52
- 7 Formula: C8H7N3O MW: 161.16 g/mol Aq. Photol ysis (m ajor) 10.2% @ 96 hrs

## 16

**Appendix 3. Representative Model Output FIRST OUTPUT**  **Proposed New Use Maximum Rate of 0.15 lb a.i./A** 

RUN No. 1 FOR thiabendazole ON seed treat * INPUT VALUES *

-------------------------------------------------------------------- RATE (#/AC) No.APPS & SOIL SOLUBIL APPL TYPE %CROPPED INCORP ON E(MULT) INTERVAL Koc (PPM ) (%DRIFT) AREA (IN)

-------------------------------------------------------------------- .150( .150) 1 1 7343.0 28.0 GRANUL( .0) 91.0 1.0

FIELD AND RESERVOIR HALFLIFE VALUES (DAYS)

-------------------------------------------------------------------- METABOLIC DAYS UNTIL HYDROLYSIS PHOTOLYSIS METABOLIC COMBINED (FIELD) RAIN/RUNOFF (RESERVOIR) (RES.

- EFF) (RESER.) (RESER.)

-------------------------------------- ------------------------------ 2064.00 2 N/A 1.20

- 148.80 .00 148.80 UNTREATED WATER CONC (MICROGRAMS/LITER (PPB)) Ver 1.1.0 JAN 1, 2007

--------------------------------------------------------------------

PEAK DAY (ACUTE) ANNUAL AVERAGE (CHRONIC) CONCENTRATION CONCENTRATION

-------------------------------------------------------------------- 2.846 .349

RUN No. 2 FOR thiabendazole ON seed treat * INPUT VALUES *

-------------------------------------------------------------------- RATE (#/AC) No.APPS & SOIL SOLUBIL APPL TYPE %CROPPED INCORP ONE(MULT) INTERVAL Koc (PP M ) (%DRIFT) AREA (IN)

-------------------------------------------------------------------- .150( .150) 1 1 7343.0 28.0 GRANUL( .0) 91.0 2.0

FIELD AND RESERVOIR HALFLIFE VALUES (DAYS)

------------------------------- ------------------------------------- METABOLIC DAYS UNTIL HYDROLYSIS PHOTOLYSIS METABOLIC COMBINED (FIELD) RAIN/RUNOFF (RESERVOIR) (RES.

- EFF) (RESER.) (RESER.)

-------------------------------------------------------------------- 2064.00 2 N/A 1.20

- 148.80 .00 148.80 UNTREATED WATER CONC (MICROGRAMS/LITER (PPB)) Ver 1.1.0 JAN 1, 2007

--------------------------------------------------------------------

PEAK DAY (ACUTE) ANNUAL AV ERAGE (CHRONIC) CONCENTRATION CONCENTRATION

-------------------------------------------------------------------- 1.423 .175



### ReRun EDWCs for Wheat Seed Treatment at 0.20 lb **a.i./A**
RUN No. 1 FOR Thiabendazole ON Seed Treat * INPUT VALUES *

-------------------------------------------------------------------- RATE (#/AC) No.APPS & SOIL SOLUBIL APPL TYPE %CROPPED INCORP ONE(MULT) INTERVAL K oc (PPM ) (%DRIFT) AREA (IN)

-------------------------------------------------------------------- .200( .200) 1 1 7343.0 28.0 GRANUL( .0) 91.0 1.0

## 17 FIELD AND RESERVOIR HALFLIFE VALUES (DAYS)

----------------------- --------------------------------------------- METABOLIC DAYS UNTIL HYDROLYSIS PHOTOLYSIS METABOLIC COMBINED (FIELD) RAIN/RUNOFF (RESERVOIR) (RES.

- EFF) (RESER.) (RESER.)

-------------------------------------------------------------- ------ 2064.00 2 N/A 1.20

- 148.80 .00 148.80 UNTREATED WATER CONC (MICROGRAMS/LITER (PPB)) Ver 1.1.0 JAN 1, 2007

--------------------------------------------------------------------

PEAK DAY (ACUTE) A NNUAL AVERAGE (CHRONIC) CONCENTRATION CONCENTRATION

-------------------------------------------------------------------- 3.795 .466

RUN No. 2 FOR Thiabendazole ON seed treat * INPUT VALUES *

-------------------------------------------------------------------- RATE (#/AC) No.APPS & SOIL SOLUBIL APPL TYPE %CROPPED INCORP ONE(MULT) INTERVAL Koc (PP M ) (%DRIFT) AREA (IN)

-------------------------------------------------------------------- .200( .200) 1 1 7343.0 28.0 GRANUL( .0) 91.0 2.0

FIELD AND RESERVOIR HALFLIFE VALUES (DAYS)

------------------------------- ------------------------------------- METABOLIC DAYS UNTIL HYDROLYSIS PHOTOLYSIS METABOLIC COMBINED (FIELD) RAIN/RUNOFF (RESERVOIR) (RES.

- EFF) (RESER.) (RESER.)

-------------------------------------------------------------------- 2064.00 2 N/A 1.20

- 148.80 .00 148.80 UNTREATED WATER CONC (MICROGRAMS/LITER (PPB)) Ver 1.1.0 JAN 1, 2007

--------------------------------------------------------------------

PEAK DAY (ACUTE) ANNUAL AV ERAGE (CHRONIC) CONCENTRATION CONCENTRATION

-------------------------------------------------------------------- 1.897 .233

## 18

**PRZM -**  **GW** 1/28/2014 7:52:43 AM; thiabendazole hyd up b HL ave koc; Florida Citrus
- FL Central Ridge, Polk County
- (Tampa) Met File (12842.dvf)
- Astatula sand, hrgb A User Interface Version: PRZM
- GW (Version 1.03) ***Record 3 0.78 0 0 33 1 1 ***Record 6

0 ***Reco rd 8

1 ***Record 9

1 0.25 200 60 1 10 10 10 0 100 ***Record 10 99 ***Record 11 0101 1 0102 1 3112 1 1 0101 2 0102 2 3112 2 1 0101 3 0102 3 3112 3 1 0101 4 0102 4 3112 4 1 0101 5 0102 5 3112 5 1 0101 6 0102 6 3112 6 1 0101 7 0102 7 3112 7 1 0101 8 0102 8 3112 8 1 0101 9 0102 9 3112 9 1 010110 010210 311210 1 010111 010211 311211 1 010112 010212 3 11212 1 010113 010213 311213 1 010114 010214 311214 1 010115 010215 311215 1 010116 010216 311216 1 010117 010217 311217 1 010118 010218 311218 1 010119 010219 311219 1 010120 010220 311220 1 010121 010221 311221 1 010122 010222 311222 1 010123 010223 311223 1 010124 010224 311224 1 010125 010225 311225 1 010126 010226 311226 1 010127 010227 311227 1 010128 010228 311228 1 010129 010229 311229 1 010130 010230 311230 1 010131 010231 311231 1 010132 010232 311232 1 010133 010233 311233 1 010134 010234 311234 1 010135 010235 311235 1 010136 010236 311236 1 010137 010237 311237 1 010138 010238 311238 1 010139 010239 311239 1 010140 010240 311240 1 010141 010241 311241 1 010142 010242 311242 1 010143 010243 311243 1 010144 010244 311244 1 010145 010245 311245 1 010146 010246 311246 1

## 19

010147 010247 311247 1 010148 010248 311248 1 010149 010249 311249 1 010150 010250 311250 1 010151 010251 311251 1 010152 010252 311252 1 010153 010253 311253 1 010154 010254 311254 1 010155 010255 311255 1 010156 010256 311256 1 010157 010257 311257 1 010158 010258 311258 1 010159 010259 311259 1 010160 010260 311260 1 010161 010261 311261 1 010162 010262 311262 1 010163 010263 311263 1 010164 010264 311264 1 010165 010265 311265 1 010166 010266 311266 1 010167 010267 311267 1 010168 010268 311268 1 010169 010269 311269 1 010170 010270 311270 1 010171 010271 311271 1 010172 010272 311272 1 010173 010273 311273 1 010174 010274 311274 1 010175 010275 311275 1 010176 010276 311276 1 010177 010277 311277 1 010178 010278 311278 1 010179 010279 311279 1 010180 010280 311280 1 010181 010281 311281 1 010182 010282 311282 1 010183 010283 311283 1 010184 010284 311284 1 010185 010285 311285 1 010186 010286 311286 1 010187 010287 311287 1 010188 010288 311288 1 010189 010289 311289 1 010190 010290 311290 1 010191 010291 311291 1 010192 010292 311292 1 010193 010293 311293 1 010194 010294 311294 1 010195 010295 311295 1 010196 010296 311296 1 010197 010297 311297 1 010198 010298 311298 1 010199 010299 311299 1 ***Record 12 Place Holder ***Record 13 99 1 0 0 ***Record 15 Place Holder ***Record 16 2512 1 0 5 1 0.168 1 0 2512 2 0 5 1 0.168 1 0 2512 3 0 5 1 0.168 1 0

## 20

2512 4 0 5 1 0.168 1 0 2512 5 0 5 1 0.168 1 0 2512 6 0 5 1 0.168 1 0 2512 7 0 5 1 0.168 1 0 2512 8 0 5 1 0.168 1 0 2512 9 0 5 1 0.168 1 0 251210 0 5 1 0.168 1 0 251211 0 5 1 0.168 1 0 251212 0 5 1 0.168 1 0 251213 0 5 1 0.168 1 0 251214 0 5 1 0.168 1 0 251215 0 5 1 0.168 1 0 251216 0 5 1 0.1 68 1 0 251217 0 5 1 0.168 1 0 251218 0 5 1 0.168 1 0 251219 0 5 1 0.168 1 0 251220 0 5 1 0.168 1 0 251221 0 5 1 0.168 1 0 251222 0 5 1 0.168 1 0 251223 0 5 1 0.168 1 0 251224 0 5 1 0.168 1 0 251225 0 5 1 0.168 1 0 251226 0 5 1 0.168 1 0 251227 0 5 1 0.168 1 0 251228 0 5 1 0.168 1 0 251229 0 5 1 0.168 1 0 251230 0 5 1 0.168 1 0 251231 0 5 1 0.168 1 0 251232 0 5 1 0.168 1 0 251233 0 5 1 0.168 1 0 251234 0 5 1 0.168 1 0 251235 0 5 1 0.168 1 0 251236 0 5 1 0.168 1 0 251237 0 5 1 0.1 68 1 0 251238 0 5 1 0.168 1 0 251239 0 5 1 0.168 1 0 251240 0 5 1 0.168 1 0 251241 0 5 1 0.168 1 0 251242 0 5 1 0.168 1 0 251243 0 5 1 0.168 1 0 251244 0 5 1 0.168 1 0 251245 0 5 1 0.168 1 0 251246 0 5 1 0.168 1 0 251247 0 5 1 0.168 1 0 251248 0 5 1 0.168 1 0 251249 0 5 1 0.168 1 0 251250 0 5 1 0.168 1 0 251251 0 5 1 0.168 1 0 251252 0 5 1 0.168 1 0 251253 0 5 1 0.168 1 0 251254 0 5 1 0.168 1 0 251255 0 5 1 0.168 1 0 251256 0 5 1 0.168 1 0 251257 0 5 1 0.168 1 0 251258 0 5 1 0.168 1 0 251259 0 5 1 0.168 1 0 251260 0 5 1 0.168 1 0 251261 0 5 1 0.168 1 0 251262 0 5 1 0.168 1 0 251263 0 5 1 0.168 1 0 251264 0 5 1 0.168 1 0 251265 0 5 1 0.168 1 0 251266 0 5 1 0.1 68 1 0

## 21

251267 0 5 1 0.168 1 0 251268 0 5 1 0.168 1 0 251269 0 5 1 0.168 1 0 251270 0 5 1 0.168 1 0 251271 0 5 1 0.168 1 0 251272 0 5 1 0.168 1 0 251273 0 5 1 0.168 1 0 251274 0 5 1 0.168 1 0 251275 0 5 1 0.168 1 0 251276 0 5 1 0.168 1 0 251277 0 5 1 0.168 1 0 251278 0 5 1 0.168 1 0 251279 0 5 1 0.168 1 0 251280 0 5 1 0.168 1 0 251281 0 5 1 0.168 1 0 251282 0 5 1 0.168 1 0 251283 0 5 1 0.168 1 0 251284 0 5 1 0.168 1 0 251285 0 5 1 0.168 1 0 251286 0 5 1 0.168 1 0 251287 0 5 1 0.168 1 0 251288 0 5 1 0.168 1 0 251289 0 5 1 0.168 1 0 251290 0 5 1 0.168 1 0 251291 0 5 1 0.168 1 0 251292 0 5 1 0.168 1 0 251293 0 5 1 0.168 1 0 251294 0 5 1 0.168 1 0 251295 0 5 1 0.1 68 1 0 251296 0 5 1 0.168 1 0 251297 0 5 1 0.168 1 0 251298 0 5 1 0.168 1 0 251299 0 5 1 0.168 1 0 ***Record 17

0 3 0 ***Record 19 Place Holder ***Record 20 400 0 0 0 0 0 2 1 1 0 ***Record 26 0.0 0.0 0.0 ***Record 27

4 0.1 0.90 7.0 ***Record 31 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.97 10.0 ***Record 32 21 21 21 21 21 21 21 21 21 21 21 21 ***Record 32A 2.00 25.0 ***Record 33

8 *** Record 34,36,37 Horizon 1

1 10 1.35 0.3 0 0 0 0.00350.000336 0 1 0.3 0.014 0.14410.5 7392 21 96 2.4 0 0 *** Record 34,36,37 Horizon 2

2 10 1.58 0.25 0 0 0 0.00350.000317 0 5 0.25 0.016 0.14410.57392 21 95 2.8 0 0 *** Record 34,36,37 Horizon 3

3 20 1.58 0.25 0 0 0

## 22 0.00350.000261 0 20 0.25 0.016 1.44105.7392 21 95 2.8 0 0 *** Record 34,36,37 Horizon 4

4 20 1.45 0.33 0 0 0 0.00350.000187 0 20 0.33 0.015 0.14410.57392 21 95 2.8 0 0 *** Record 34,36,37 Horizon 5

5 20 1.5 0.27 0 0 0 0.00350.000112 0 20 0.27 0.015 0.14410.57392 21 95 2.8 0 0 *** Record 34,36,37 Horizon 6

6 20 1.5 0.34 0 0 0 0.00353.73E
- 05 0 20 0.34 0.015 0.14410.57392 21 95 2.8 0 0 *** Record 34,36,37 Horizon 7

7 200 1.59 0.25 0 0 0 0.0035 0 0 50 0.25 0.014 0.14410.57392 21 96 2.8 0 0 *** Record 34,36,37 Horizon 8

8 100 1.58 0.3997 0 0 0 0.0035 0 0 50 0.3997 0.001 0.14410.57392 21 87 11 0 0 *** Record 40

0 *** Record 42

YEAR 10 YEAR 10 YEAR 10 0 *** Record 45

5 YEAR *** Record 46 DCON1 TAVE 21 22 1.0E3 INFL TCUM 21 210.000121 IRRG TSER VFLX TSER FPVL TSER

Highest Daily Value(ppb) = 0.461 μg/L Average Breakthrough Time(days)

– Incomplete Post - Breakthrough Average (ppb)

– Incomplete Throughputs
- 0.487 Simulation Period 100 years Application rate 0.15 lb a.i./A Application Date (
- 7 days) since emergence Hydrolysis half
- life

– 198 days

## 23

Surface Soil Half
- life

– 2064 days Sorption Coefficient

– Koc 7343 (average Koc)

## 24 SCIGROW VERSION 2.3 ENVIRONMENTAL FATE AND EFFECTS DIVISION

OFFICE OF PESTICIDE PROGRAMS U.S. ENVIRONMENTAL PROTECTION AGENCY

SCREENING MODEL FOR AQUATIC PESTICIDE EXPOSURE SciGrow version 2.3 chemical:thiabendazole time is 1/23/2014 13:26: 4

------------------------------------------------------------------------ Application Number of Total Use Koc Soil Aerobic rate (lb/acre) applications (lb/acre/yr) (ml/g) me tabolism (days)

------------------------------------------------------------------------ 0.150 1.0 0.150 2.90E+03 2064.0

------------------------------------------------------------------------ groundwater screening cond (ppb) = 9.43E
- 03 ************************************************************************
SciGrow version 2.3 chemical:thiabendazole time is 2/24/2014 8: 0:23

------------------------------------------------------------------------ Application Number of Total Use Koc Soil Aerobic rate (lb/acre) applications (lb/acre/yr) (ml/g) metabolism (days)

------------------------------------- ----------------------------------- 0.200 1.0 0.200 2.90E+03 2064.0

------------------------------------------------------------------------ groundwater screening cond (ppb) = 1.26E
- 02 ****************************** ******************************************