### UNITED STATES ENV I RONMENTAL PROTECT I ON AGENC Y WAS H ING T ON

. D.C

. 20460

OFFICE OF CHEMICAL SAFETY A N D POLLUTION P REVE N TION



### MEMORANDUM March 18, 2014 PC Code: 0601 01 and 0601 02 DP Barcode: 415548

SUBJECT:



### FROM: Problem Formulation for the Ecological Risk and Drinking Water E xposure Assessments to be Conducted in Support of the Registration Review of Thiabendazole and its Hypophosphite Salt 11 11 , 

# ....J--11--**~ry~** Nicholas Mastrota, Ph.D., W i' ldlife Biologist James K

. Wolf

, Ph

. D., Environmental Scientist Environmental Risk Branch 3 E nvironmental Fate and Effects Division (7507P)

# ~LJrl

Srinivas Gowda, Microbiologist 

### S 

# -n**~** V 

### D)>

,

## ~ William Erickson, Ph.D

. , Biologist

## h)~ Najm Shamim, Ph.D., Chemist**;1~ a•** **'"""** 

### Risk Assessment and Science Support Branch (RASSB) Antimicrobials Division (751 OP)



### REVIEWED Rosanna Louie-Juzwiak, Risk Assessment Process Leader

# ~--T-- BY : Melissa Panger, Ph

. D.

, Senior Biologist James Hetrick

, Ph.D., Senior Advisor E nvironmental Risk Branch 3 Environmental Fate and Effects Division (7507P)



### THROUGH : Dana Spatz, Branch

# Chie~ 

# <:::::::::::: 

# h 3.-1

# ~ "' I '-/ 

### ·Environmental Risk

# Bran~h**~~** E nvironmental F ate and E ffects Division (7507P)

Steven Weiss, Branch Chief

# ~**{JI~,** Risk Assessment and Science Support Branch (RASSB) Antimicrobials Division (7 51 OP)



### TO: Neil Anderson

, Branch Chief Ricardo J ones, Chemical Review Manager Risk Management and Implementation Branch I Pesticide Re-Evaluation Division (7508P)

1

### 2 1. Executive summary

The Environmental Fate and Effects Division (E FED) and Antimicrobials Division (AD) have completed the preliminary problem formulation for the ecological ris k, environmental fate, endangered species, and drinking water assessments to be conducted as pa rt of the registration review of the systemic fungicide thiabend azole (PC code: 060101) and the related salt, thiabendazole hypophosphite (060102), hereon refe rred to as thiabendazole. The problem formulation describes the methods planned to be used during the completion of drinking water and ecological risk assessments in support of re gistration review, and pr ovides an overview of the environmental fate, ecological effects, and potential risks associat ed with the use of thiabendazole. Uncertainties unique to the risk assessment of thiabendazo le are also discussed. Although no data have been submitted for thiabendazole hypophosphite, this assessment considers that the salt will dissociate ra pidly to form thiabendazole in water.

The following additional information is needed to better understand the e nvironmental fate of thiabendazole:

 Metabolism rates, iden tification of degradation products, and sorption/desorption in spent mushroom compost before and after pasteurization.

 Additional information concerning the fate of the spent mushroom compost such as residue concentrations, amount s produced, and rates applied as a soil amendment.

 Information estimating of the amount of th iabendazole released in the wastewater effluent from the manufacturing plants during the manufacturi ng process would be beneficial to refine the risk assessment. A ready biodegradab ility study is also anticipated to be required (835.3110). If the r eady biodegradability st udy indicates that thiabendazole is not biodegradable, then one of three biodegradation in active sludge simulation tests is anticipated to be required, being either GLN 835.3220, 835.3240, or 835.3280.

The following additional data are needed for conducting the ecological risk assessment:

 Acute oral toxicity to a passerine bird (GLN 850.2100)

 Toxicity to a freshwater and saltwater diatom (GLN 850.4500)

 Toxicity to cyanobacteria (GLN 850.4550)

 The Environmental Chemistry Methods (ECM ) and Independent Laboratory Validation (ILV) are needed for water (GLN 850.6100).

 An Activated Sludge, Respira tion Inhibition Test (ASRI) is needed to determine the effects of thiabendazole on wastewater treatment plant organisms (GLN 850.3300).

 A leaching study from treated textiles is needed to assess the textile uses.

While a life-cycle study with the saltwater my sid (GLN 850.1350) would reduce uncertainty in the risk assessment, EPA intends on estimating toxicity using the acute-to-chronic ratio method.

### 3 2. Introduction

EPA evaluated the most recent ecological risk asse ssments for thiabendazole in association with the updated toxicity, exposure, and usage informati on to determine if suffici ent data are available and if further updates are needed to support regi stration review. Recent c onventional uses risk assessments include assessments for a seed-treat ment use on corn (field corn, sweet corn, and popcorn) (USEPA, 2010; DP barcode: D363978); a s eed-treatment use on dry peas (dry peas, lentils, and chickpeas) (USEPA, 2006; DP barcodes: D315436, D322581); and an assessment conducted for the re-registration evaluation d ecision (RED) of thiabendazole (USEPA, 1999); see Use Characterization section for additiona l uses of thiabendazole. In addition, EPA considered the latest science policie s and risk assessment methodologies.

The structures of thiabendazole and thia bendazole hypophosphite are given in Figure 1. Chemical names and other identifie rs of thiabendazole and degradat es can be found in Table 5.

a. Thiabendazole Structure

b. Thiabendazole hypophosphite

Figure 1. Thiabendazole (a.) and thiabendazole hypophosphite (b.)

Mechanism of Action

Thiabendazole is a systemic fungicide. The mode of action of thiabendazole inhibits the mitosis of plant pathogenic fungi speci es by preventing the polymeriza tion of beta-tubulins. Because dimers of beta-tubulin and alpha-tubulin polymeri ze to form microtubule st ructures inside the cells, thiabendazole acts as an inhibitor of microtubuline polymerization, terminating cell division.

### 4 3. Use Characterization

Conventional Uses : Thiabendazole is registered for use as a seed treatment on seeds of corn (field corn, sweet corn, and popcorn), soybean, dry peas, chickpeas, lentils, and wheat; a treatment of seed pieces of potatoes and sweet potatoes; and as a postharvest application to a variety of terrestrial food and non-food crops (e.g., potatoes, citrus, pome fruit, ornamentals, turf, and tobacco). Thiabendazole is also registered fo r use in mushroom culture for control of fungal diseases. It is applied to seeds and seed pieces as a ready-mix or as a slurry mix. It is sprayed onto mushrooms as a flowable concentrate. Thiabendazole hypophosphite, a salt of thiabendazole, is used as a tree-injec tion fungicide in ornamental trees.

Application rates for seed treatments are given in terms of weight of thiabendazole applied to weight of seed. Application rates range fr om 0.000055 to 0.0028 pound active ingredient (a.i.) per pound of seed. EFED estimates upper bound applic ation rates in terms of pounds a.i. per acre treated by multiplying these pounds-per-seed rates by maximum expected seed planting rates (seeds per acre), which is specific for each crop. Use information provided on the labels for thiabendazole seed treatment is given in Table 1.

Table 1. Application Information for Seed Treatment Uses of Thiabendazole

Seed Type Maximum AI Application Rate (lb a.i./100 lb seed) Maximum Seeding Rate (lb seed/Acre) Max Application Rate (lb a.i./A)
Clover 0.283 30.0 0.0849 Corn, field 0.0200 29.6 0.00593 Corn, pop 0.042 22.0 0.00974 Corn, sweet 0.0355 33.2 0.0118 Garbanzos (including chickpea) 0.0663 217.8 0.0144
Lentil 0.0341 163.4 0.0558 Peas, garden 0.0332 411.0 0.136 Peas, dry 0.0332 217.8 0.0722 Pea, pigeon 0.0332 43.6 0.0145 Potato seed-pieces 0.000672 2 6969.6 3 0.0468 Soybean 0.00548 166.7 0.00913 Sweet potato seed pieces ND 1 Wheat (spring and winter) 0.131 156.0 0.20

1 Product labels do not provide enough information to cal culate the application rate for sweet potato seed pieces.
2 0.42 fl oz. product/2000 pounds potatoes

3 4900-6969 lb potato seed pieces/A; The maximum seed ing rate was developed ba sed on data provided by

BEAD—J. Becker; S. Ratnayake. Acres Planted per Da y and Seeding Rates of Crops Grown in the United States, March 24, 2011


### Thiabendazole may be applied to mushrooms at the casing, fuzzing, pinning stages, and between harvests of mushroom breaks. It may be applied to mushrooms to a maximum rate of 0.641 lb a.i./1000 ft 2 

### (20 fl oz Mertect® 340-F [EPA Reg. No 100-889] per 1000 ft 2 

### ) per crop cycle. The first application may be ma de up to 0.256 lb a.i./1000 ft 2 

### (8 fl oz Mertect® 340-F per 1000 ft 2 

### ), and subsequent applications may be made up to 0.128 lb a.i./1000 ft 2 

### (4 fl oz Mertect 340-F per 1000 ft 2 

### ). Although application of thiabendazole in mushroom culture takes place indoors, after

### 5 the mushrooms are harvested, the spent compost on which thiabendazole was sprayed may be disposed of outdoors, or used as a mulch or so il amendment. This outdoo r application of spent mushroom compost could result in release of thiabendazole residues in to the environment.

Thiabendazole may be applied to mushrooms at any time during cultivation from spawning through 12 hours prior to mushroom harvest. Since mushroom s are grown indoors with closed irrigation systems, no appreciable exposure to the outdoor environment is expected during the time of culture. However, after a cycle of mush room harvest is complete, the spent mushroom compost (SMC) is commonly collected and sold to distributers for use as a landscape and horticulture product. The SMC may then be applie d to the surface of soil as a mulch, or mixed into farm or garden soil as a soil amendment. 1 

### Residues of thiabendazole that accumulated during mushroom cultivation potentially could remain in the SMC and be released into the environment at this time. Grogan and Jukes (2003) found that thiabendazole is highly persistent in mushroom casing soil, and thus some thiabendazo le residues are expected to persist in SMC.

Thiabendazole hypophosphite, a salt of thiabendazole , is used as a tree-injection fungicide for control of certain funga l diseases in elms, London plane, oak, and sycamore trees. Products containing thiabendazole hypophosphite are formulated as a soluble concentrate or a ready-touse solution. They are applied by injection into sapwood of root fl ares of the tree. The maximum application rate for large trees is approximately 94 g (0.21 lb) of ac tive ingredient per 5 inches of trunk diameter. For trees less than 30 inches in diameter, the maximum application rate is approximately 63 g (0.14 lb) of active ingredient per 5 inch of trunk diameter. The rates in terms of thiabendazole equivalence are 71 g (0.16 lb) thiabendazole per 5 inches of diameter for large trees and 47 g (0.10 lb) thiabendazo le per 5 inches of diameter . Trees may be retreated once every three years.

Antimicrobials Uses : Thiabendazole is registered for us e as a material preservative and antifungal agent to inhibit the gr owth of mold and mildew associated with odors, staining, discoloration, and general biodeteri oration on adhesive films, wallp aper adhesives, interior and exterior latex or solvent/oil ba sed paint films, stains, paper products, heating and cooling system filters and/or room air cleaners/purifiers, wallboar d, sealants, grout, ceiling tiles, plastics, plastic intermediates, canvas textiles, and carpet b acking, and natural a nd synthetic fibers.

4. Conclusions from Previous Risk Assessments
a. Ecological Risk Assessment

Ecological risk assessments have been conducted for seed treatment uses of thiabendazole, but not for the mushroom use, nor for the tr ee-injection use of thiabendazole hypophosphite. Ecological risk assessments have also not been conducted for the antimicrobial uses (paints/stains, textiles). The eco logical risk assessment conducted in the RED for seed treatment uses concluded that there were minimal potentia l risks from thiabendazo le to terrestrial or aquatic animals (USEPA, 1999). Plants were not assessed in the RED; however, risk was not expected based on the low expos ure potential for the uses re gistered at the time of the

1 http://extension.oregonstate.edu/gardening/what-mushroom-compost

### 6 assessment. In the ecological risk assessmen t conducted for thiabendazole use as a seed treatment on dry peas, no risks to terrestrial or aq uatic animals were expected (USEPA, 2006). Although there were no effects noted at the highest concentrations tested in the available avian reproduction studies, there was some uncertainty related to chronic risk for birds from the chickpea use because the estimated environmental concentrations were higher than the highest concentration tested. Additionally, risks to aquati c and terrestrial plants could not be assessed due to a lack of data.

The most recent, comprehensive assessment c onducted for thiabendazole is the assessment conducted for the new use of corn seed treatment (USEPA, 2010) and the new use on dry peas (USEPA, 2006). The risk assessment for seed treatment of corn with a maximum seasonal application rate of 0.005 lb a.i. /A concluded that acute and ch ronic risks were less than the EPA’s levels of concern (LOC) for fish, aquatic invertebrates, birds, and mammals. The risk assessment for seed treatment of dry peas with a maximum seasonal appl ication rate of 0.09 lb a.i./A concluded that acute and chronic risks were less than th e EPA’s LOCs for fish, aquatic invertebrates, and mammals. For birds, acute risk was less than the LOC whereas chronic risk was above the LOC. Potential chronic risk for birds was concluded, but uncertainties in this conclusion were noted due to limitations with the available avian repr oduction data and the conservative nature of the chronic risk assessmen t. In both assessments, risks to aquatic plants, terrestrial plants, and terrestria l arthropods could not be assessed because toxicity data were lacking for these groups of organisms.

As noted above, previous risk assessments have not included evaluation of the use of thiabendazole on mushrooms or tree-injection us es of thiabendazole hypophosphite. Therefore, the potential risks from these uses are unknown. EFED expects that the tree -injection uses result in limited ecological risks because this use w ould mainly expose terrestrial animals, and thiabendazole has relatively little toxicity to terrestrial animals. However, there is uncertainty regarding risk from use in mush room culture, and exposures from application of spent mushroom compost, could potentially be much greater than that for seed tr eatment uses. When considering the application rate expressed in terms of pounds a.i./acre, expos ure would be at least 10 times greater than those for seed treatments, and the high persistence of thiabendazole which suggest that it would likely accumulate and pe rsist in the mushroom compost.

The major ecological concerns based on prev ious risk assessment are summarized in Table 2 

### :

Table 2. Summary of Risk Concerns Identifie d for Thiabendazole in Previous Assessments

Birds Mammals Terr. Plants Terr. Inverts Fish BCF Aquatic Inverts Aquatic Plants Groundwater Contamination Persistence Degradates of Concern Yes a No b No c No c ? b No ? b No c No Yes No

a Potential chronic risk to birds was identified for some seed treatment uses. Potential acute risks to passerine species is uncertain due to a lack of data. Also, potential risk from use of spent mushroom compost contaminated with thiabendazole is unknown.
b Previous assessments have shown that risk from seed treatment uses are low; however, risk from mushroom uses are have not been assessed and potentially could be a concern.

c Previous assessments did not assess risk to this taxa because of the lack of toxicity data; however, newly submitted toxicity data suggest that risks are low. Yes = at least one LOC has been exceeded in previous asse ssments or risks could not be assessed based on the available information; “No“ = LOCs have not been excee ded in previous assessments, or LOC exceedances are not expected. “?”= Risks are unknown until exposu res from mushroom compost is assessed.

### 7 b. Drinking Water Assessments

The most recent drinking water exposure assessment for the seed treatment use on field corn, sweet corn, and pop corn was conducted for thiabendazole in 2009 (USEPA, 2009 2 

### ). The highest Tier 2 EDWCs for the surface water drinking wa ter exposure concentrations for the proposed corn seed treatment for thiabendazole were 0.018, 0.0048, and 0.0034 μ g/L, for the peak, annual mean, and overall mean concentrations, respec tively. Earlier drinking water assessments for thiabendazole as a seed treatment was consid ered for dry peas (D315436), for Section 18 use (time limited tolerance petition) on Brussels sp rout, cabbage, and cauliflower in California (D326593, D326597, D326600), Washington (D327512, D327516, D327517), and wheat (D245780 ) 

### . For the Thiabendazole Reregistration E ligibility Document (RED) (D245780), the Tier 1 GENEEC drinking water EDWCs were 2 .4 μg/L and 1.55 μg/L for the peak and average 56 day concentration, respectivel y, for the maximum wheat seed treatment (0.20 lb a.i./acre). Previously, drinking water expos ure from the mushroom use wa s not considered because the mushrooms are grown indoors. The potential exposure to drinking water from disposal of spent mushroom compost (casing and compos t materials) was not considered.

c. Clean Water Act Programs

Thiabendazole is not identified as a cause of impa irment for any water bodies listed as impaired under section 303(d) of the Clean Water Act 3 

### . In addition, no Total Maximum Daily Loads (TMDL) have been developed for thiabendazole 4 

### . More information on impaired water bodies and TMDLs can be found at the Agency’s website 5 

### . The Agency invites submission of water quality data for this pesticide. To the extent possible, data should conform to the quality standards in Appendix A of the OPP Standard Operating Procedur e: Inclusion of Impaired Water Body and Other Water Quality Data in OPP’s Regist ration Review Risk Assessment and Management Process 6 

### in order to ensure they can be us ed quantitatively or qualitatively in pesticide risk assessments. Aquatic benchmarks 7 

### have not been establis hed for thiabendazole. Any data submitted or otherwise located as part of the registration review process may be used to update aquatic life benchmar ks, if applicable.

5. Environmental Fate and Transport

Environmental fate studies show th at thiabendazole is persistent and immobile (Table 3). It is stable to hydrolysis and soil photolysis and degr ades slowly in aerobic (half-life ~ 700 days) and anaerobic soil environments. Aqua tic photolysis, with a half life of 1.2 days in clear water, appears to be the only significant degradati on pathway. Under anaer obic aquatic conditions thiabendazole showed no evidence of abiotic or biotic degradation but moved rapidly from the

2 Wolf, J.K. 2009. Drinking Water Assessme nt for Maxim ® Quattro fungicide (EPA Reg. No. 100-RGLE)) a new fungicide for

field corn, sweet corn, and pop corn . DP Barcode 363978, October 13, 2009.
3 http://iaspub.epa.gov/tm dl_waters10/attains_nation_cy.ca use_detail_303d?p_cause_group_id=885
4 http://iaspub.epa.gov/tmdl_waters10/attain s_nation.tmdl_pollutant_detail ?p_pollutant_group_id=885&p_ pollutant_group_name=PESTIC IDES 5 http://www.epa.gov/owow/tmdl/
6 http://www.epa.gov/oppsrrd1/registra tion_review/water_quality_sop.htm
7 http://www.epa.gov/oppefed1/ecoris k_ders/aquatic_life_benchmark.htm

### 8 water phase to the sediment 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 capacity, thiabendazole could be transported on eroded sediment. Terrestri al field dissipation studies showed thiabendazole to be extremel y persistent with no observed leaching. Vapor pressure and Henry’s Constant i ndicate that thiabendazole poses a low concern for volatilization from soil and water. These studies are discussed in more detail in the ecological assessment in support of the RED (DP Barcode D245780). Pertinent physico-chemical and environmental fate and transport properties of thiabenda zole are summarized in Table 3.

Table 3. Chemical Properties and Environm ental Fate Parameters 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 /mol -- (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 Hydrolysis half-life (22  C) Stable @ pHs 5, 7, 9 Rates a of transformation were extrapolated resulting in t 1⁄2 s (200 days) far beyond the length of the study (30 days) 41265301 (D245780; 02/04/99)

Aqueous photolysis half-life (22.5 to 23.2  C) t 1⁄2 = 1.2 days 96 hour study @ pH5 43328305

Soil photolysis half-life (25  C) Stable -- 41297301 41397302

Aerobic soil metabolism half-life (25°C) t 1⁄2 = 688 days -- 41791201 EFED Registration Document D245780

Anaerobic soil metabolism half-life (25°C) t 1⁄2 = 211 day Only degradate detected was benzimidazole in a 90 day study. (max 13.7 % AR;). 41559601

### 9 Parameter Value Description Source (MRID #) Anaerobic aquatic metabolism half-life No evidence of biotic or abiotic degradation. Rapidly moved from water phase to the sediment phase. 00122888 00070753 Aerobic aquatic metabolism half-life [dissipation half-life A ] (25  C) -- Study requirement waived 41559601 (D169687; 12/30/92) Mobility Freundlich soil-water partition coefficients (K F ); organic carbonnormalized Freundlich coefficients (K FOC ) K F (mL/g) / K 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 laye r; (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 BioconcentrationFish bioconcentration factors (steadystate); 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 thiobendazole: pH 5 (-0.0019 days -1 ); pH 7 (-0.0035 days -1 ); pH 9 (-0.0026 days -1 )



### a. Transformation Products

Three degradates were identified in the aque ous photolysis study (benzimidazole-2-carboxamide as a major degradate; benzimidazole and benzimidazole-2-carboxylic acid as minor degradates), two minor degradates were identified in the ae robic soil metabolism study (benzimidazole and 5- hydroxythiabendazole), and one major degradate wa s identified in the anaerobic soil metabolism study (benzimidazole) (see below) (

Table 4). The common name, chemical names, CA S No., molecular formula and mass, chemical structure, and maximum and final percent of applied radioactivity (AR) of the major degradates are summarized in Table 5. The proposed degradati on pathway in soil is given in Figure 2. The only degradate that was analyzed for in the terr estrial dissipation studies is benzimidazole. Test results showed that benzimidazole was not detected in any soil layers. No data were available for the other three degradates to veri fy their presence in the field. However, since they comprised a relatively small fraction (less than 10%) of the total applied radioactivity in the laboratory studies, EFED believes that their concentrations in the fields will also be negligible.

### 10 Table 4. Thiabendazole degradates identif ied in Environmental Fate Studies.
Degradates Hydrolysis Photolysis (water) Photolysis (soil) Aerobic Soil Anaerobic Soil Terrestrial Field
Benzimidazole X X X a

5-hydroxy thiabendazole 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%)

### 11 Figure 2. Proposed degradation path way of thiabendazole in soil.12Table 5. Thiabendazoleand Its Environmental DegradatesNameChemical Name CAS No.FormulaMolecular MassChemical StructureStudy TypeMaximum (%AR)Final %AR (studylength)PARENTThiabendazole 2-(4-thiazolyl)-1H-benzimidazoleCAS No.: 148-79-8Formula: C10H7N3SMW:201.25 g/molAerobic SoilMetabolismAnaerobic SoilMetabolism-a56.8%78% (@ day 90)TRANSFORMATION PRODUCTSThiabendazole-5-hydroxy5-hydroxythiabendazole;2-(4-Thiazolyl)-5-benzimidazololCAS No.: 948-71-0Formula: C10H7N3SMW: 217.25g/molAerobic SoilMetabolism-Benzimidazole 1H-BenzimidazoleCAS No.: 962-28-7Formula:C7H6N2MW: 118.05 g/molAq. Photolysis (minor)Aerobic SoilMetabolismAnaerobic SoilMetabolismTerrestrial FieldDissipation-2.2%13.7%-6.49% (avg.)0.17%5.5% (@ day 90-13NameChemical Name CAS No.FormulaMolecular MassChemical StructureStudy TypeMaximum (%AR)Final %AR (studylength)Benzimidazole carboxylicacid1H-Benzimidazole-2-carboxylicacidCAS No.:Formula:C8H6N2O2MW: 162.15 g/molAq. Photolysis (minor) - 9.98% @ 96 hrsBenzimidazole-2-carboxamide1H-Benzimidazole-2-carboxamideCAS NO. 5805-52-7Formula: C8H7N3OMW: 161.16 g/molAq. Photolysis (major) - 10.2% @ 96 hrsaIncreasing with time.

### 14 6. Receptors
a. Effects to Aquatic Organisms

Table 6 provides a summary of toxicity endpoi nts that characterize the acute and chronic toxicity of thiabendazole to aquatic organisms. Based on th e available ecotoxicity data, thiabendazole is classified as highly toxic to fish and aquatic invertebrates on an acute basis. Chronic toxicity testing is available w ith freshwater fish and invertebrates. Chronic toxic effects were observed in the rainbow trout at concentrations as low as 0.23 mg a.i./L, with a NOAEC established at 0.11 mg a.i./L. Chronic toxic effects were observed in the water flea at concentrations as lo w as 0.087 mg a.i./L, with a NOAEC established at 0.042 mg a.i./L.

No data are available on the chronic toxicity of thiabendazole to saltwater fish or invertebrates. Chronic toxicity to saltwater invertebrates therefore will be estimated based on the acute-to-chronic ratio (ACR) for freshwat er species (the water flea) and the acute toxicity value for the mysid. The ACR (EC 50 

### /NOAEC) for freshwater invertebrates is 7.38. The chronic toxicity for saltwater inve rtebrates is estimated by dividing the acute EC 50 

### for the mysid (0.34 mg a.i./L) divided by the ACR. This estimated chronic NOAEC value is 0.046 mg a.i./L.

An aquatic plant toxicity test determined the EC 50 

### for duckweed to be 0.56 mg a.i./L, indicating that vascular aquatic plants are also sensitive to thiabendazole. Limited data are available on the toxicity of thia bendazole to algae and cyanobacteria.

Table 6. Summary of the Most Sensitive Endpoi nts from Aquatic To xicity Studies for Thiabendazole.

Taxonomic Group Study Type Surrogate Species Toxicity Value (in terms of active ingredient) Acute Toxicity Classification Source (Study Classification)

Freshwater fish 1

Acute Rainbow Trout ( Oncorhynchus mykiss ) 96-hr LC 50 = 0.56 mg/L Highly toxic 41025005 (Acceptable)

Chronic (EarlyLifeStage) Rainbow Trout NOAEC = 0.11 mg/L LOAEC = 0.23 mg/L Endpoint: Reduced weight -- 42508901 (Acceptable)

Freshwater invertebrates Acute Water Flea ( Daphnia magna ) 48-hr EC 50 = 0.31 mg/L 2 Highly toxic 00123326 (Acceptable)

Chronic Water Flea NOAEC = 0.042 mg/L LOAEC = 0.087 mg/L Endpoint: survival, offspring production -- 00094645 (Acceptable)

### 15 Taxonomic Group Study Type Surrogate Species Toxicity Value (in terms of active ingredient) Acute Toxicity Classification Source (Study Classification)

Estuarine/marine fish Acute Sheepshead Minnow ( Cyprinodon variegatus ) LC 50 > 10 mg/L 3 Slightly toxic 41192003 (Supplemental)

Estuarine/marine invertebrates

Acute Mysid ( Americamysis bahia ) 96-hr LC 50 = 0.34 mg/L Highly toxic 41192002 (Acceptable)

Eastern Oyster ( Crassostrea virginica ) IC 50 > 0.26 mg/L (22% inhibition at 0.26 mg/L) Endpoint: shell growth Not determined 41192004 (Supplemental)

Aquatic plants and algae Vascular Duckweed ( Lemna gibba ) 7-day EC 50 = 2.32 mg/L NOAEC = 0.26 mg/L Not defined 48996308 (Supplemental)

Nonvascular Freshwater Green Algae ( Pseudokirchneriella subcapitata ) 96-hr EC 50 = 3.06 mg/L NOAEC = 0.532 mg/L Not defined 49146601 (Supplemental)

1 Freshwater fish may be surrogate s for aquatic-phase amphibians.
2 A second acute toxicity study with Daphnia magna determined the 48-hr EC50 of thiabendazole to be 0.85 mg a.i./L (MRID 41709401). EPA’s policy is to use the lowest valid toxicity endpoint for a species when more than one is available.
3 30% mortality was observed at 10 mg a.i./L , the highest test concentration. Therefore, 10 mg a.i./L will be used as a conservative estimate of the LC 50 for conducting a preliminary risk assessment.



### b. Effects to Terrestrial Organisms

Table 7 provides a summary of toxicity endpoi nts that characterize the acute and chronic toxicity of thiabendazole to terrestrial organisms. Based on the available ecotoxicity data, thiabendazole is classified as practically nontoxic to birds (Bobwhite quail and mallard) and mammals on an acute basis. A waiver was submitted for the conduct of an acute toxicity study on passerines; however, it was de nied. Chronic toxicity testing is available with birds and mammals. In birds, no chroni c toxic effects were observed in the bobwhite and the mallard when tested with dietary con centrations as high as 400 mg a.i./kg-diet. Therefore, the NOAEC was established at 400 mg a.i./kg for both species. For mammals, acute oral toxicity classifies thiabendazole as practically nontoxic on an acute basis. For chronic toxicity to mammals, a two-gene ration rat reproductive study established the NOAEL at 10 mg a.i./kg/day based on reduction in body weight gain and food consumption at the next higher concentr ation of 30 mg a.i./kg/day (MRID 43190301). This NOAEL is equivalent to a dietary concentration of approxima tely 600 mg a.i./kgfood. Previous ecological risk assessments used a higher NOAEC of 1800 mg ai/kg-diet, but that was based only on the lack of re productive effects observe d in this study. Other studies also have noted sublet hal toxic effects at dietary exposures at or near 600 mg a.i./kg-diet, including liver hypertrophy (MRID 43593201) and histopathological changes in bone marrow, liver, and thyroid (MRI D 42942802). In a developmental rat study, a

### 16 growth effect was also observed in developing young (decreased fetal body weight) at the slightly higher dietary concentration of 800 mg a. i./kg-diet (MRID 42942803).

Phytotoxicity testing thiabendazole determin ed that the most sensitive species were ryegrass and cucumber. The IC 25 

### was 0.23 lb a.i./A for effects on seedling emergence, and ≥ 0.23 lb/A for effects on vegetative vigor . The NOAEC was less than 0.23 lb a.i./A for both the seedling emergence and vegetative vigor studies.

Table 7. Summary of the Most Sensitive Endpoint s from Terrestrial Toxicity Studies for Thiabendazole

Taxonomic

Group Study Type Surrogate Species Toxicity Value (all units in terms of active ingredient) Acute Toxicity Classification Source

Birds 1 Acute Bobwhite quail ( Colinus virginianus ) LD 50 > 2,250 mg a.i./kg-bw Practically non-toxic 41025002 (Acceptable)

Passerine species No data available

Sub-acute dietary Bobwhite quail and mallard ( Anas platyrhynchos ) LC 50 > 5,620 mg a.i./kg-diet Practically nontoxic 41025003 & 41025004 (Acceptable)

Chronic Bobwhite quail and mallard NOAEC = 400 mg a.i./kg-diet LOAEC > 400 mg a.i./kg-diet -- 00123327 & 00123328 (Acceptable)

Mammals Acute Oral Laboratory rat ( Rattus norvegicus ) LD 50 = 5070 mg/kg-bw (M) 4734 mg/kg-bw (F) Practically nontoxic 41258201

Acute Inhalation Laboratory rat LC 50 > 6.84 mg/L Toxicity Category III 00100706

Chronic (2-generation reproduction) Laboratory rat NOAEL = 10 mg/kg/day LOAEL = 30 mg/kg/day Endpoint: reduced body weight gain and food consumption -- 43190301

Terrestrial invertebrates Acute
contact Honey bee ( Apis mellifera ) LD 50 > 34 μg/bee (No toxic effects) Practically nontoxic 48996305 (Acceptable)

Acute oral Honey bee LD 50 > 4 μg/bee -- 48996305

### 17 Taxonomic

Group Study Type Surrogate Species Toxicity Value (all units in terms of active ingredient) Acute Toxicity Classification Source

Terrestrial plants Seedling Emergence Monocot – Ryegrass NOAEC < 0.23 lb/A EC 25 > 0.023 lb/A Endpoint: shoot length -- 48996306 (Acceptable, except Supplemental for bean and soybean) Dicot* NOAEC = 0.23 lb/A EC 25 > 0.23 lb/A

Vegetative Vigor Monocot* NOAEC = 0.23 lb/A EC 25 > 0.23 lb/A

-- 48996307 (Acceptable) Dicot – cucumber NOAEC < 0.23 lb/A EC 25 ≥ 0.23 lb/A Endpoint: emergence and survival * Because no significant inhibition was observed in any test species, the most sensitive species was not determined in this study.



### c. Ecological Incidents

The ecological incident information system (EIIS) is an OPP database that houses ecological incidents that have been reporte d to the Agency. When available, EIIS includes date and location of an incident, t ype and magnitude of effects observed in various species, use(s) of pesticides known or suspected of contri buting to the incident, and results of any chemical residue analysis or other analyses conducted during incident investigation. EIIS incidents ar e categorized according to the certainty that the incident resulted from pesticide exposure. The Avia n Monitoring System (AIMS) is a database administered by the American Bird Conservanc y that contains publicly available data on reported avian incidents involving pesticides. Many of the incide nts listed in this database are also in the EIIS.

In a search conducted on November 19, 2013, EIIS returned two incidents involving thiabendazole. One incident (I015152-001) invo lved damage to a soybean crop in 2004 as a result of an accidental misuse. In this incident, tebuconazole was accidently added to a lot of the fungicide Rival (which containe d the fungicides quintozene, thiabendazole, and captan) by a formulator. In another incident that occu rred in 2012 (I023976-001), several bee hives were affected. Thiabendazole was one of several pesticides applied near the incident ( i.e., fludioxonil, azoxystrobin, clothian idin, metalaxyl, and thiamethoxam). This incident is classified as “unlikely” for thiabendazole since thiabendazole has low toxicity to bees, whereas severa l of the other pesticides associated with the incident are known to be toxic to bees. No incidents have been reported in EIIS for thiabendazole hypophosphite.

### 18 As of November, 2013, there were no avian incidents reported in AIMS and no aggregated ecological incidents involving thiabendazole reported by the registrant.

7. Exposure Pathways of Concern

Direct outdoor uses of thiabe ndazole are limited to seed treatments and preplant treatment of bulbs and tubers. Therefore, spray drift a nd atmospheric transport are not expected to be relevant routes of exposure to plants a nd animals. As thiabendazole is moderately soluble, residues potentially could wash off or dissolve from the surface of treated seeds, bulbs, and tuber during rain events or ir rigation, and transport through runoff could contaminate surface water. This route of exposure is expected to be limited because the high potential for thiabendazole to bind to soil particles gives it very little mobility in soil. Sorbed thiabendazole woul d be transported on eroded soil.

Residues of thiabendazole that dissolve in soil pore water potentially could leach and contaminate ground water. Contamination from l eaching, however, is expected to be very limited because of the low mobility of thiabendazole.

Since mushrooms are grown indoors, use of thiabendazole during the cultivation of mushrooms is not expected to result in any significant environmental exposure during cultivation. However, after the mushroom s have been harvested, disposal of thiabendazole-contaminated growth medium (c asing or compost), or use of the growth medium for mulch or compost, could pot entially contaminate surface water and groundwater. A preliminary evaluation indicate th at this route could be significant since the use rate on mushroom compost is much greater than that associated with seed treatment uses, and the high persistence of thiabendazole makes it likely that residues will persist in spent mushroom compost when it is di sposed of or applied to soil. These routes of exposure therefore will be evaluated when assessing ecological ri sks associated with use of thiabendazole on mushrooms.

For tree-injection uses of thiabendazo le hypophosphite, a limited amount of water contamination may occur from residues that leach out of shed leaves and fallen trunks and branches. This route of exposure is expe cted to be minor since release of residues through these routes would be slow, and becau se of the high cost and labor of tree injection, only a small fraction of trees in a watershed are expected to be treated with thiabendazole.

For terrestrial wildlife, direct consumption of seeds by granivorous animals is a primary route of exposure. Animals may be exposed to treated seeds through feeding on shallowly sown seeds in fields and on spilt seeds. P uddles and pooling of water on fields planted with treated seeds, bulbs, or tubers may also result in exposure of wildlife through consumption of drinking water. EPA’s Screening Imbibition Model 8 

### (SIP) was used to

8 

### Further information on the SIP model is available at: http://www.epa.gov/oppefed1/ models/terrestrial/index.htm

.

### 19 screen for the potential for risk from drinki ng water. This model indicated that exposure from drinking water is not a significant conc ern for mammals, but c ould potentially be a concern for birds due to the potential for chr onic effects. Because thiabendazole is not applied as a spray for outdoor uses, inhalation is not expected to be a significant route of exposure. Because many treated seeds, bulbs, and tubers would be planted underground, exposure through dermal absorption is also not expected to be a significant exposure
route.

Since thiabendazole is a system ic fungicide and is stable (e xcept for aquatic photolysis), seed treatment may result in some of the activ e ingredient being abso rbed by the roots of growing crops and translocate into the tissue and nectar of the crops. Therefore, the potential exists for some exposure to wildlif e that feed on the foliage of crops grown from treated seeds, and to pollinator insect s and birds which may feed on nectar from flowers of treated crops. However, this r oute of exposure is expected to be minor compared to direct consumption of treated seed s. Therefore, risk from this exposure route is assumed to be negligible.

For tree-injection uses of thiabendazole hypophosphite, the pr imary route of terrestrial exposure would be through consumption of edible parts of treated trees. Birds and mammals would be exposed primarily through c onsumption of fruit and seeds of treated trees. Terrestrial insects ma y also be exposed through consumption of leaves, wood, nectar, or pollen of treated trees.

For the materials preservative uses, thiabend azole poses potential risks to organisms in the aquatic environment if material leaches from treated exterior surfaces and the active ingredient is transporte d to impounded water bodies ( e.g. , ponds, lakes) or flowing waterways ( e.g. , streams, rivers). Thiabendazole also may reach the aquatic environment via down-the-drain discharge from use on te xtiles. Aquatic organisms likely to be exposed include fish, invertebrates, and aqua tic plants. For aquatic animals, the major route of exposure is considered to be upt ake via the respiratory surface (gills) or the integument from surface water residues. For aquatic plants, the major route of exposure is considered to be uptake from surface water.

Thiabendazole has a low log k ow 

### (1.61) and the low bioconcentr ation factors in fish (19.7 to 747). Therefore, bioaccumulation and bi oconcentration of residues in fish and terrestrial wildlife is not expected to be significant.

8. Analysis Plan

a. Stressors of Concern

The stressor of ecological a nd drinking water concerns is only the parent compound, thiabendazole. Thiabendazole is stable in th e environment, and therefore formation of degradation products will be very slow. In the field dissipation studies, no degradation products of thiabendazole were detected (

### 20 Table 4). Therefore, exposure to degradati on products is expected to be minimal. Thiabendazole hypophosphite salt completely dissociates in water. Therefore, thiabendazole is also the ecological stressor for tree injection uses of thiabendazole hypophosphite.

b. Measures of Exposure

i. Exposure Modeling

Drinking Water and Aquatic Exposure Modeling

EPA will prepare updated drinking water and ecological aquatic exposure assessments for thiabendazole using st andard available models 9 

### to evaluate potential exposure to pesticides in surface water (PRZM and EXAMS) and groundwater (PRZM-GW) sources as described at http://www.epa.gov/pesticides/science/models_db.htm

. To estimate exposure to thiabendazole in water, all exposure modeling will be made based on maximum application rates.

Although a drinking water expos ure assessment would not per se be conducted for the use of thiabendazole on mushrooms, drinking water and aquatic exposure will be considered for residues in spent mushroom compost used as a soil amendment. For the mushroom compost disposal, application rates will be estimated from compost concentrations and rate of applications of the compost as a soil amendment. The maximum application rate for thiabendazole will be used in the PRZM/EXAMS and PRZM-GW modeling. Previous drinking wate r assessments did not consider the mushroom uses of thiabendazole where residues may remain on casing and in spent compost material that is used as a soil amendment. For further information on these EFED models see, http://www.epa.gov/oppefed1/models/water/index.htm. 

### AD will also conduct an aquatic exposure assessment for textile leaching and for wastewater discharge during manufacturing processes using the down-the-drain module of the EFAST Model. This assessment was not included in previous assessments.

For antimicrobial applications of paints /stains to exterior surfaces, estimated environmental concentrations (EECs) will be modeled to provide estimates of acute and chronic exposure in the aquatic environmen t. The EECs are determined for a 1-ha, 1-m deep farm pond, based on the amount of thia bendazole leached from treated surfaces and the number and size of treated structures per un it of area. For tex tile use, determination of surface water concentrations will be done using the down-the-drain module of the EFAST Model.

9 PRZM and EXAMS are Tier I and II models used to estimate environmental exposure concentrations in

surface water. A description of these models and th e guidelines for selecting input parameters can be found at http://www.epa.gov/oppefed1/models/water/

### 21 Terrestrial Exposure Modeling

Exposure to terrestrial animals is estimated using the Terrestrial Residue Exposure (TREX) model. Exposure to terrestrial plants is estimated using the TerrPlant model. For terrestrial plants, exposure is based on the calculated maximum application rates with assumed exposure from runoff, but not spra y drift. These models are described at http://www.epa.gov/pesticides/science/models_db.htm

. For terrestrial animals exposed to treated see d, the maximum application rate will be used to estimate the LD 50 

### -per-square-foot risk index. In addition, risk quotients will be calculated based on dietary exposure for animals that feed directly on treated seeds. This exposure is calculated by multiplying the amount of a.i. expected to be on a treated seed by the number of seeds an animal would need to consume in one day to meet its daily average food intake. Finally, risk is further characterized by calc ulating the number of treated seeds animals need to consume to reach a dose equal to the acute LD 50 

### and chronic NOAEL.

ii. Available Monitoring Data

EPA is aware of monitoring conducted by federal ( e.g ., USGS NAWQA) and states ( e.g., CDPR monitoring database) agencies. Availa ble monitoring data wi ll be evaluated and considered in an assessment conducted for Registration Review.

iii. Approach to Estimating Exposure from Non-Seed Treatment Uses

Mushroom Use

Thiabendazole may be applied to mushr ooms at any time during cultivation from spawning through 12 hours prior to mushroom harvest. Since mushrooms are grown indoors with closed irrigation systems, no appreciable exposure to the outdoor environment is expected during the time of culture. However, after a cycle of mushroom harvest is complete, the spent mushroom compost (SMC) is commonly applied to the surface of soil as a mulch, or mixed into fa rm or garden soil as a soil amendment. 10


### Residues of thiabendazole that accumulated during mushroom cultivation potentially could remain in the SMC and be released into the environment at this time.

The crop cycle of mushrooms t ypically involves several cycl es of harvesting mushrooms ( i.e. , mushroom breaks) which form from the same body of mycelium growing in mushroom compost and overlaying casing. Th e label allows up to 27.9 lb a.i./A of thiabendazole to be applied throughout this crop cycle. The estimated residues in the

10 http://extension.oregonstate.edu/gardening/what-mushroom-compost

### 22 SMC will be based on one application at 11.2 lb a.i./A, followed by three subsequent applications at 5.6 lb a.i./A each, with 6 days between each application, and the last application to the mushrooms made 12 hours prio r to the final harvest. The application of the SMC as a soil amendment will be assumed to take place 7 days after harvest. The rate of dissipation of thiabendazole residues in SMC is unknown; based on available data from field dissipation studies, thiabendazole appe ars to dissipate very slowly in soil (half lives 833-1444 days, MRID 43187201 and 43187202).

Based on information on use of SMC provided by the Oregon State University Extension Service 11 

### and the American Mushroom Institute, 12 

### it is estimated that 2 to 3 inches of SMC will be applied to soil. The depth of co mpost (with casing) in mushroom houses is estimated to be approximately half this depth. When conducting the exposure modeling for application to outdoor soil, it will be a ssumed that a square-foot of compost in a mushroom house would be spread over approxim ately 2 square feet of soil; therefore, the application rates will be multiplied by 0.5 to account for this factor.

Several other factors potentially could affect the amount of th iabendazole that is released from SMC into the environment:

 Pasteurization of SMC prior to collection and distribution could potentially break down thiabendazole residues or could re tard degradation by reducing microbial degradation.

 SMC removed from the mushroom house may be stored outdoors for several months (for logistic reasons , or to be “weathered”), a nd significant dissipation of thiabendazole residues could occur during this time.

 The high temperature and high microbial activity which occur in compost piles may accelerate degradation.

 The very high in organic matter cont ent of SMC may increase the binding capacity of amended soils and could result in different environmental fate activity than is observed in laboratory studies us ing mineral soil types (Grogan and Jukes, 2003).

The EPA would welcome any information that c ould be provided to better understand the fate of thiabendazole residues in SMC and to reduce the uncertainties of our exposure
assessment.

Leachate from piles of SMC stored outside and exposed to precipitation can contaminate ground and surface water (Chorover et al ., 2001). Leachate from piles of thiabendazoletreated SMC potentially could be a source of thiabendazole cont amination to nearby aquatic habitats and dr inking water sources.

11 Oregon State University Extension Service, 2003. “What is Mushroom Compost” http://extension.oregonstate.edu/gardening/what-mushroom-compost
12 http://www.mushroomcompost.org/Corn.pdf

### 23 Tree-Injection Use (Thiabendazole Hypophosphite)

Thiabendazole hypophosphite is used in tree-inje ction products that are injected into the trunks or root flares of elms, oaks, sycam ore, and London plane. Exposure for this use pattern stems from translocation of the fungicide into parts of treated trees that are used as food items for animals, such as fruits a nd nuts. Information on the translocation and partitioning of thiabendazole into specific tissu es of the tree is not available. Since the fungicide products are injected into the xylem, it is expected to be transported up the sapwood and into the upper portions of the tree. Therefore, the EPA will assume that the thiabendazole injected into the tree will be distributed evenly throughout the foliage component of the tree. The typical foliage bi omass of trees may be calculated using the equations presented in Te r-Mikaelian and Korzukhin (1997). The predicted foliar concentration will be used as the assume th iabendazole concentration in all parts of treated trees that terrestrial animals would lik ely consume (leaves, fruits, nuts, twigs, and buds).

For aquatic exposure, a screen ing-level assessment will be done based on thiabendazole being released from fallen leaves. Trees that are treated with thiabendazole hypophosphite will assume to surround a standard one-acre pond. Standard tree densities will be used to estimate the maximum number of trees that could grow on the perimeter of the pond. For a conservative screening-le vel assumption, all of the thiabendazole hypophosphite injected into the tr ees will be assumed to be translocated into the leaves, and released into the pond water when the leaves fall and decay. This amount will be divided by the volume of water in the pond to derive a conservative aquatic EEC for this

use.

Materials Preservatives Use

An aquatic plant and animal risk assessment will be conducted for the materials preservatives uses for textiles and paints/stains. Data will be needed to determine the amount of thiabendazole which will leach from textiles. Determina tion of surface water concentrations of thiabendazole will be done using the down-the-drain module of the EFAST Model for textile leaching and for the amount of thiabendazole in the wastewater effluent during the manufacturing pro cess at the manufacturing plant.

### 24 c. Measures of Effect

Toxicity data presented in Section 3 of this problem formulation are us ed to calculate risk quotients. Any additional information submitted by the registrant or found in the open literature prior to conduct of a risk assessment will also be considered. The open literature studies are identified using EPA’s ECOTOXicology database (ECOTOX) (USEPA, 2007), which employs a literature sear ch engine for locating chemical toxicity data for aquatic life, terrestrial plants, and w ildlife. The evaluation of both sources of data can also provide insight into the direct and indirect effects of pesticides on biotic communities from loss of species that are sens itive to the chemicals and from changes in structure and functional characteris tics of the affected communities.

d. Estimation of Risk

The exposure and toxicity data are integrated in order to evaluate the potential risks of adverse ecological effects on non-ta rget species. The risk quotient (RQ) method is used to compare exposure and toxicity values. EECs are divided by acute a nd chronic toxicity values. The resulting RQs are then compared to the Agency’s levels of concern (LOCs). Risk presumptions, along with the correspond ing RQs and LOCs for terrestrial animals are summarized in Table 8.

### 25 Table 8. Risk Presumptions and Levels of Concern Risk Presumption RQ LOC

Birds 1

Acute Risk EEC/LC 50 or LD 50 /sqft or LD 50 /day 0.5

Acute Restricted Use EEC/LC 50 or LD 50 /sqft or LD 50 /day 0.2

Acute Endangered Species EEC/LC 50 or LD 50 /sqft or LD 50 /day 0.1

Chronic Risk EEC/NOEC 1

Mammals 1

Acute Risk EEC/LC 50 or LD 50 /sqft or LD 50 /day 0.5

Acute Restricted Use EEC/LC 50 or LD 50 /sqft or LD 50 /day 0.2

Acute Endangered Species EEC/LC 50 or LD 50 /sqft or LD 50 /day 0.1

Chronic Risk EEC/NOEC 1

1 LD 50 /sqft = (mg/sq ft) / (LD 50 * wt. of animal) LD 50 /day = (mg of toxicant consumed/day) / (LD 50 * wt. of animal)



### e. Endangered Species Assessments

Consistent with the Agency’s responsibility under the Endangered Species Act (ESA), the Agency will evaluate risks to federally li sted threatened and/or endangered (listed) species from registered uses of pesticid es in registration review. The process for evaluating potential risks to listed species is further described at: http://www.epa.gov/oppfead1/enda nger/litstatus/riskasses.htm

.

f. Endocrine Disruptor Screening Program

Thiabendazole was not included in the first group of 67 chemicals issued an order to conduct Tier 1 EDSP testing, or in the revise d second list of 134 chemicals issued June 14, 2013. For additional information the EDSP program, visit http://www.epa.gov/endo/

.

### 26 9. Preliminary Identification of Data Gaps

a. Environmental Fate

Table 9 identifies environmental fate studies for thiabendazole by MRID that offer data for each guideline requirement, as well as study classifications and whether or not further data are needed in order to support risk assessment.

Upon review of the data availa ble it appears that several st udies are either not submitted or previously waived by the Agency. The Environmental Chemistry Methods (ECM) and Independent Laboratory Validation (ILV) have been submitted for soils, but not for water. The aerobic aquatic metabolis m (OCSPP 835.4300; old Guideline 162-4) guideline study was previously waived (D 16987, 12/30/1992) following the conventions at that time because there were no dir ect aquatic uses. Although the estimated environmental concentrations are expected to be low (bas ed solely on the low proposed application rate), there would be uncertainty related to risk s, most notably for aquatic organisms. This data would be useful if drinking water or aquatic exposure concentrations require refinements. A dditional issues are noted in Table 9.

Additional information concerning the fate of the spent mushroom casing and compost such as residue concentrations, amounts pr oduced, rates applied as a soil amendment would be useful. Based upon the data available thiabendazole will be persistent but not very mobile in the environment. Thiabendazo le is resistant to de gradation by microbial metabolism as indicated by th e slow degradation rates ( i.e. , long half-lives ). It appears that the standard practice prio r to disposing of the spent mu shroom compost it to sterilize (or pasteurize) via heating. Therefore, an understanding of the degradation/metabolism rates, identification of degr adation products, and sorption/de sorption in spent mushroom compost before and after pasteurization is needed to understand the potential exposure from this use of thiabendazole.

The existing fate and transport data ade quately addresses most of the AD uses for thiabendazole. However, a number of AD us e scenarios will trigger Down-the Drain estimation. In addition, for use of thiabendazole in natural and synthetic fibers, a leaching study is needed to estimate the exposure concerns due to the likely presence of thiabendazole in waste water stream e ffluents from manufacturing plants. A nonguideline leaching study will be needed for the treated fibers use.

Table 9. Submitted Environmental Fate Data for Thiabendazole and Data Gaps

OCSPP GUIDELINE MRID STUDY TITLE ISSUES Are Additional Data Needed?

835.1230 41170102 Adsorption/desorption Data/Leaching - N

835.2120 41265301 Hydrolysis - N
835.2240 43328305 Photodegradation in water - N

### 27 OCSPP GUIDELINE MRID STUDY TITLE ISSUES Are Additional Data Needed?

835.2410 41397301 41397302 Photodegradation in Soil - N

835.3110 835.3220 835.3280 835.3240 - Ready biodegradability test or one of three biodegradation in activated sludge simulation tests Transport to wastewater treatment plant and aquatic environment Y

835.4100 41791201 Aerobic Soil Metabolism - N
835.4200 41559601 Anaerobic Soil Metabolism - N

835.4300 - Aerobic Aquatic Metabolism Requirement was waived because of no direct aquatic uses. N 1

835.4400 41559601 Acc# 244423 Anaerobic Aquatic Metabolism waived 2 N

835.6100 43187201 43187202 43187203 Terrestrial Field Dissipation - N

850.1730 41631801 Bioconcentration in fish - N

850.6100 43187201 43187203 Environmental Chemistry Methods (ECM) and Independent Laboratory Validation (ILV) Soil Water (no study) N (soil) Y (water )

Nonguideline

study - Leaching from treated textiles Provide estimate of the total thiabendazole discharged into the wastewater through the manufacturing processes Y

1 While data are not being requested at this time, th e lack of available aerobic aquatic metabolism data

would preclude any refinements, if needed.
2 Waived 162-3, 162-4, 164-2, 165-3(12/20/1992; D169687, D170813)



### b. Ecological Effects

Table 10 identifies submitted ecological eff ects studies for aquatic species, and the current status of those guideline requirements.

### 28 Table 11 does the same for terrestrial specie s. The following ecological effects data are needed for conventional uses ecological risk assessment:

 A study of avian acute oral toxicity (GLN 850.2100) with a passerine bird.

 Studies algal toxicity (GLN 850.4500) with a freshwater and a saltwater diatom specie.

 Studies algal toxicity (G LN 850.4550) with cyanobacter ia (blue-green algae).

The following ecotoxicity data are needed to support the antimicrobial uses ecological risk assessment:

 An Activated Sludge Respirati on Inhibition test (GLN 850.3300).

. Table 10. Submitted Aquatic Ecological Effects Data for Thiabendazole

OCSPP Guideline Data Requirement Submitted Studies (MRID) Test Species Study Classifications Are data needed to conduct risk assessment? Justification and Assumptions EPA will

Make in Absence of Data

850.1010 Freshwater invertebrate acute toxicity 41709401 Water flea Acceptable No -- 00123326 Water flea Acceptable

850.1035 850.1045 Saltwater
crustacean acute toxicity 41192002 Mysid Acceptable No --

850.1025 850.1055 Saltwater bivalve acute toxicity 41192003 Eastern oyster Supplemental No

850.1075 Freshwater fish acute toxicity 42477701 Bluegill sunfish Acceptable No --

41025005 Rain bow trout Acceptable 41025006 Bluegill sunfish Supplemental

00123311 Rain bow trout Acceptable 00122906 Bluegill sunfish Acceptable

850.1075 Saltwater fish acute toxicity 41192003 Sheepshead minnow Supplemental No

850.1300 Freshwater invertebrate life cycle 00094645 Water flea Acceptable No --

### 29 OCSPP Guideline Data Requirement Submitted Studies (MRID) Test Species Study Classifications Are data needed to conduct risk assessment? Justification and Assumptions EPA will

Make in Absence of Data

850.1350 Saltwater invertebrates life cycle (None) (N/A) (N/A) No EPA will estimate the NOAEC using the acute-to-chronic ratio method, based on the available acute toxicity data for the mysid and acute and chronic toxicity data for the water flea. Comparison of the acute mysid endpoint (0.34 mg a.i./L) with the acute daphnid endpoint (0.31 mg a.i./L) indicates that these species have similar sensitivity to thiabendazole. Therefore, one would expect that the chronic toxicity value for the mysid also would be similar to that for the daphnid, and therefore obtaining a chronic toxicity value for the mysid is not expected to change the risk assessment conclusions for potential chronic risk to aquatic invertebrates.

850.1400 Freshwater fish early-life stage 42508901 Fathead minnow Acceptable No --

00094644 Fathead minnow Acceptable for formulated product 1

00097969 Rain bow trout Acceptable for formulated product 1

850.1400 Saltwater fish early-life stage (None) (N/A) No --

850.1500 Fish life cycle (None) (N/A) No -- 850.4400 Aquatic plant Toxicity Test using Lemna
spp. 48996308 Duckweed Supplementa l No The supplemental study provides adequate information on toxicity to vascular aquatic plants for assessing ecological risk.

### 30 OCSPP Guideline Data Requirement Submitted Studies (MRID) Test Species Study Classifications Are data needed to conduct risk assessment? Justification and Assumptions EPA will

Make in Absence of Data 850.4500 Algal toxicity 49146601 Supplemental Yes The supplemental study provides adequate information on the toxicity to green algae, but toxicity data are anticipated to be needed for freshwater and saltwater diatoms. 850.4550 Cyanobacteria (None) Yes No toxicity data has been submitted to assess risk to cyanobacteria, and are anticipated to be needed.

850.3300 ASRI (None) Yes No toxicity data has been submitted to assess risk to waste water treatment plant organisms. These data are anticipated to be needed. 1. This study was conducted with the formulated product Mertect® 340-F, which contains 42.28% thiabendazole.

### 31 Table 11. Submitted Terrestrial Ecologi cal Effects Data for Thiabendazole

OCSPP Guideline Data Requirement Submitted Studies (MRID) Test Species Study Classifications Are data needed for risk assessment? Current Additional Data Need

850.2100 Avian oral toxicity 41025002 Bobwh ite Acceptable Yes To better assess the risk of thiabendazole to all species of birds, including passerines, an acute oral toxicity study with a passerine species is anticipated to be needed. 00123313 Bobwh ite Acceptable

00137948 Mallard Acceptable

850.2200 Avian dietary toxicity 41025003 Bobwh ite Acceptable No --

41025004 Mallard Acceptable

00123314 Bobwh ite Acceptable

850.2300 Avian reproduction 00123327 Bobw hite Acceptable No --

00123328 Mallard Acceptable

Nonguideline Avian inhalation (None) (N/A)

850.3020 Honey bee
acute contact toxicity 48996305 Honey bee Acceptable No --

850.3030 Honey bee residue on foliage (None) (N/A) No --

850.3040 Field testing for pollinators (None) (N/A) No --

850.4100 Seedling Emergence and Seedling Growth 48996306 10 species Supplemental for common bean and soybean, Acceptable for other 8 species No Data for common bean and soybean are supplemental, but are nevertheless adequate to show low risk for the current seed
treatment uses. 850.4150 Vegetative Vigor 48996307 10 species Acceptable No --

### 32 

# References

Grogan, H M and A A Jukes. 2003. Persiste nce of the fungicides thiabendazole, carbendazim and prochloraz-Mn in mushroom casing soil. Pest Manage. Sci. 59:1225-1231.

Guo, M, J Chorover, R Rosario, and R H Fox. 2001. Leachate chemistry of fieldweathered spent mushroom substrate. J. Environ. Qual. 30(5):1699-1709.

Ter-Mikaelian, M. T. and M. D. Korzukhin. 199 7. Biomass equations for sixty-five North American tree species. For. Ecol. and Manage . 97(1):1-24

USEPA, 1999. EFED Reregistration Document for Thiabendazole. Environmental Fate and Effects Division, Office of Pesticide Programs, United States Environmental Protection Agency. Washington, DC. February 4, 1999. DP barcode: D245780.

USEPA, 2006. Review of New Use for Th iabendazole (Mertect 340-F) as a seed treatment on dry peas. Environmental Fate and Effects Division, Office of Pesticide Programs, United States Environmental Protection Agency. Washington, DC. April 13, 2006; DP barcodes: D315436, D322581.

USEPA, 2007. ECOTOX user guide: ECOTOXic ology database system, v. 4.0

. Washington, DC: US Environmental Protection Agency. Available at: http:/www.epa.gov/ecotox/

USEPA, 2009. Drinking Water Assessment fo r Maxim® Quatro Fungicide (EPA Reg. No. 100-RGLE, a new fungicide for fi eld corn, sweet corn, and popcorn. Environmental Fate and Effects Divisi on, Office of Pesticide Programs, United States Environmental Protection Agen cy. Washington, DC. October 13, 209. DP barcode D363978.

USEPA, 2010. Environmental Fate and Ecological Risk Assessment for the Proposed Section 3 New Use of Thiabendazole on Field corn, Sweet corn, and Popcorn

. Environmental Fate and Effects Divisi on, Office of Pesticide Programs, United States Environmental Protection Agency. Washington, DC. January 6, 2010. DP barcode D363978.

### 33 

## Appendix A
OPPIN Bibliography
Ecotoxicity
060101 Thiabendazole Eco Effects Bibliography 03/13/12

Note: Some MRIDs also show up for 060102 Thiabendazole hypophosphate



## 71-1 Avian Si ngle-Dose Oral Toxicity

MRID Citation Reference

123313 Fink, R.; Beavers, J.; Brown, R. (1977) Acute Oral LD50--Bobwhite Quail: Thiabendazole: Project No. 105-119. Final rept. (Unpublished study received Dec 5, 1977 unde r 618-88; prepared by Wildlife International Ltd. and Washington College, submitted by Merck & Co., Inc., Rahway, NJ; CDL:232421-G)
137948 Fink, R.; Beavers, J.; Brown, R. (1977) Acute Oral LD50--Mallard Duck: Thiabendazole: Project No. 105-118. Final report. (Unpublished study received Dec 5, 1977 unde r 618-88; prepared by Wildlife International Ltd. and Washington College, submitted by Merck & Co., Inc., Rahway, NJ; CDL:232421-H)
41025002 Grimes, J.; Jaber, M. (1989) Technical Thiabendazole: An Acute Oral Toxicity Study with the Bobwhite: Final Rpt. Proj. No. 105-138. Unpublished study prepared by Wildlife International Ltd. 26 p.
92183004 Wislocki, P. (1990) Merck & Co. Inc. Phase 3 Summary of MRID 41025002. Technical Thiabendazole: An Acute Oral Toxicity Study with the Bobwhite: Project No. 105-138. Prepared by WILDLIFE INTERNATIONAL. 9 p.
122900 Fink, R.; Beavers, J.; Brown, R. (1978) Acute Oral LD50--Mallard Duck: Mertect LSP: Project No. 105-126. Final rpt. (Unpublished study received May 24, 1978 under 618 -84; prepared by Wildlife International Ltd. and Washington College, submitted by Merck & Co., Inc., Rahway, NJ; CDL:234030-A)
122901 Fink, R.; Beavers, J.; Brown, R. (1978) Acute Oral LD50--Bobwhite Quail: Mertect LSP: Project No. 105-125. Final rpt. (Unpublished study received May 24, 1978 under 618 -84; prepared by Wildlife International Ltd. and Washington College, submitted by Merck & Co., Inc., Rahway, NJ; CDL:234030-B)



## 71-2 Av ian Dietary Toxicity

MRID Citation Reference

### 34 47899 or 117805 Knott, W.B.; Johnston, C.D. (1968) Thiabendazole: Safety Evaluation on Bobwhite Quail. (Unpublished study received Aug 7, 1974 under 5F1537; prepared by Woodard Research Corp., submitted by Merck & Co., Inc., Rahway, N.J.; CDL:094556-G) CDL:091522-F)

47900 or 107425 or 122827 Fink, R. (1973) Final Report: Eight-Day Dietary LC50--Mallard Ducks: Project No. 105-101. (Unpublished study received Aug 7, 1974 under 5F1537; prepared by Truslow Farms, Inc., submitted by Merck & Co., Inc., Rahway, N.J.; CDL:094556-H)
122902 Fink, R.; Beavers, J.; Brown, R. (1978) - Eight day Dietary LC50-- Bobwhite Quail: Mertect LSP: Project No. 105-123. Final rpt. (Unpublished study received May 24, 1978 under 618-84; prepared by Wildlife International Ltd. and Wash ington College, submitted by Merck & Co., Inc., Rahway, NJ; CDL:234030-C)
122903 Fink, R.; Beavers, J.; Brown, R. (1978) Eight-day Dietary LC50-- Mallard Duck: Mertect LSP: Pr oject No. 105-124. Final rpt. (Unpublished study received May 24, 1978 under 618-84; prepared by Wildlife International Ltd. and Wash ington College, submitted by Merck & Co., Inc., Rahway, NJ; CDL:234030-D)
123314 Fink, R.; Beavers, J.; Brown, R. (1977) Eight-day Dietary LC50-- Bobwhite Quail: Thiabendazole: Project No. 105-117. Final rpt. (Unpublished study received Dec 5, 1977 under 618-88; prepared by Wildlife International Ltd. and Wash ington College, submitted by Merck & Co., Inc., Rahway, NJ; CDL:232421-I)
41025003 Grimes, J.; Jaber, M. (1989) Technical Thiabendazole: A Dietary LC50 Study with the Bobwhite: Proj. No. 105-136. Unpublished study prepared by Wildlife International Ltd. 29 p.
41025004 Grimes, J.; Jaber, M. (1989) Technical Thiabendazole: A Dietary LC50 Study with the Mallard: Proj. No. 105-137. Unpublished study prepared by Wildlife International Ltd. 28 p.
92183005 Wislocki, P. (1990) Merck & Co. Inc.. Phase 3 Summary of MRID 41025003. Technical Thiabendazole, A Dietary LC50 Study with the Bobwhite: Project No. 105-136. Prepared by WILDLIFE INTERNATIONAL. 9 p.
92183006 Wislocki, P. (1990) Merck & Co. Inc.. Phase 3 Summary of MRID 41025004. Technical Thiabendazole, A Dietary LC50 Study with the Mallard: Project No. 105-137. Prepared by WILDLIFE INTERNATIONAL. 9 p.



## 71-4 Avian Reproduction

MRID Citation Reference

123327 ACC 235974 Fink, R.; Beavers, J.; Brown, R. (1978) One-generation Reproduction Study--Bobwhite Quail: Thiabendazole 98.5% Technical: Project No. 105-120. Final rept. (Unpublished study received Nov 21, 1978 under 618-75; prepared by Wildlife In ternational Ltd. and Washington College, submitted by Merck & Co., Inc., Rahway, NJ; CDL:235974-A)

### 35 123328 Fink, R.; Beavers, J.; Brown, R. (1978) One-generation Reproduction Study--Mallard Duck: Thiabendazole 98.5% Technical: Project No. 105-121. Final rept. (Unpublished study received Nov 21, 1978 under 618-75; prepared by Wildlife In ternational Ltd. and Washington College, submitted by Merck & Co., Inc., Rahway, NJ; CDL:235974-B)



## 72-1 Acute Toxicity to Freshwater Fish

MRID Citation Reference

47897 Knott, W.B.; Johnston, C.D. (1968) Thiabendazole: Safety Evaluation on Bluegill Sunfish. (U npublished study received Aug 7, 1974 under 5F1537; prepared by Woodard Research Corp., submitted by Merck & Co., Inc., Rahway, N.J.; CDL:094556-E)

117804 or 123304? Knott, W.; Johnston, C. (1968) Thia bendazole: Safety Evaluation on Bluegill Sunfish. (Unpublished study received Apr 21, 1970 under 0F0881; prepared by Woodard Research Corp., submitted by Merck & Co., Inc., Rahway, NJ; CDL:091522-E)

123304 ACC 100340 Knott, W.; Johnston, C. (1968) Thiabendazole Safety Evaluation on Bluegill Sunfish. (Unpublished study received Nov 27, 1968 under 618-66; prepared by Woodard Resear ch Corp., submitted by Merck & Co., Inc., Rahway, NJ; CDL:100340-B)

47898 ACC 094556 Knott, W.B.; Johnston, C.D. (1968) Thiabendazole: Safety Evaluation on Rainbow Trout. (Unpublished study received Aug 7, 1974 under 5F1537; prepared by Woodard Research Corp., submitted by Merck & Co., Inc., Rahway, N.J.; CDL:094556-F)
117803 Knott, W.; Johnston, C. (1968) Thiabendazol e: Safety Evaluation on Rainbow Trout. (Unpublished study received Apr 21, 1970 under 0F0881; prepared by Woodard Research Corp., submitted by Merck & Co., Inc., Rahway, NJ; CDL:091522-D)
122905 Vilkas, A. (1977) The Acute Toxicity of Mertect LSP to the Rainbow Trout, Salmo gairdneri Richardson: UCES Proj. # 11506-42-05. (Unpublished study received May 24, 1978 under 618-84; prepared by Union Carbide Corp., submitted by Merck & Co., Inc., Rahway, NJ; CDL:234030-F)
122906 Vilkas, A. (1977) The Acute Toxicity of Mertect LSP to the Bluegill Sunfish, Lepomis macrochirus Rafinesque: UCES Proj. #11506-42- 04. (Unpublished study received May 24, 1978 under 618-84; prepared by Union Carbide Corp., submitted by Merck & Co., Inc., Rahway, NJ; CDL:234030-G)

123311 or 122822 in PC 060102 Knott, W.; Johnston, C. (1971) Me tasol TK-100, 20% Solution and 2- (4'Thiazolyl) Benzimidazole Safety Tests in Rainbow Trout. (Unpublished study received Dec 5, 1977 under 619-88; prepared by Woodard Research Corp., submitted by Merck & Co., Inc., Rahway, NJ; CDL:232418-D)

126631 same as 123311 also in PC 060102 Knott, W.; Johnson, C. (1971) Me tasol TK-100, 20% Solution and 2- (4'Thiazolyl)benzimidazole Safety Tests in Rainbow Trout. (Unpublished study received Ma r 11, 1983 under 10445-31; pre-

### 36 pared by Woodard Research Corp., submitted by Calgon Corp., Pittsburgh, PA; CDL:249806-G)

41025005 Beglinger, J.; O'Boyle, R. ( 1989) Acute Aquatic Effects of Thiabendazole on the Rainbow Trout, Salmo gairdneri : Study No. EN-412-GWN001-2. Unpublished study prepared by Eastman Kodak Co. 58 p.
41025006 Beglinger, J.; O'Boyle, R. (1989) Acute Aquatic Effects of Thiabendazole on the Bluegill Sunfish, Lepomis macrochirus : Study No. EN-413-GWN001-2. Unpublished study prepared by Eastman Kodak Co. 55 p.
42477701 Holmes, C.; Swigert, J.; Smith, G. (1992) Thiabendazole: A 90-hour Static Acute Toxicity Test with the Bluegill ( Lepomis Macrochirus ): Lab Project Number: 105A-118A. Unpublished study prepared by Wildlife Intl. Ltd. 42 p.
92183007 Wislocki, P. (1990) Merck & Co. Inc.. Phase 3 Summary of MRID 41025006. Acute Aquatic Effects of Thiabendazole (Sponsor Product No. 47982) on the Bluegill Sunfish ( Lepomis macrochirus ): Study No. EN-413-GWN001-2. Prepared by EASTMAN KODAK, Health and Environmental Laboratories. 12 p. 92183009 Wislocki, P. (1990) Merck & Co. Inc.. Phase 3 Summary of MRID 41025005. Acute Aquatic Effects of Thiabendazole (Sponsor Product No. 47982) on the Rainbow Trout, Salmo gairdneri : Study No. EN-412-GWN001-2. Prepared by Eastman Kodak Co. Health and Environmental Lab. 9 p.


## 72-2 Acute Toxicity to Freshwater Invertebrates

MRID Citation Reference

122904 Vilkas, A. (1978) The Acute Toxicity of Mertect LSP to the Water Flea-- Daphnia magna Straus: UCES Project # 11506-42-06. (Unpublished study received May 24, 1978 under 618-84; prepared by Union Carbide Corp., submitted by Merck & Co., Inc., Rahway, NJ; CDL:234030-E)
123326 Vilkas, A. (1977) The Acute Toxicity of Thiabendazole Technical to the Water Flea ( Daphnia magna Straus): UCES Proj. # 11506- 42- 02. (Unpublished study received Jul 5, 1978 under 618-75; prepared by Union Carbide Corp., submitted by Merck & Co., Inc., Rahway, NJ; CDL:235634-D)
41709401 Holmes, C.; Bellantoni, D.; Peters, G. (1990) Thiabendazole: A 48-Hour Flow-through Acute Toxicity Test with Cladoceran ( Daphnia magna ): Final Report: Lab Project Number: 105A-101. Unpublished study prepared by Wildlife International Ltd. 129 p.

### 37 

## 72-3 Acute Toxicity to Estuarine/Marine Organisms

MRID Citation Reference

41192002 Surprenant, D. (1989) Acute Toxicity of Thiabendazole to Mysid Shrimp ( Mysidopsis bahia ) Under Flow-through Conditions: SLS Study No. 359.0888.6105.515: Report No. 89/1/2955. Unpublished study prepared by Springborn Life Sciences, Inc. 45 p.
41192003 Surprenant, D. (1989) Acut e Toxicity of Thiabendazole to Sheepshead Minnow ( Cyprinodon variegatus ) under Flow-through Conditions: SLS Study No. 359. 0888.6106.505: Report No. 89-3- 2957. Unpublished study prepared by Springborn Life Sciences, Inc. 40 p.
41192004 Surprenant, D. (1989) Acute To xicity of Thiabendazole to Eastern Oysters ( Crassostrea virginica ) Under Flow-Through Conditions: SLS Study No. 359.0888.6107.504: Report No. 89-5-2986. Unpublished study prepared by Springborn Life Sciences, Inc. 51 p.
92183008 Wislocki, P. (1990) Merck & Co. Inc.. Phase 3 Summary of MRID 41192003. Acute Toxicity of Thiabendazole to Sheepshead Minnow ( Cyprinodon variegatus ) under Flow-through Conditions: Study No. 359.0888. 6106.505. Pr epared by EASTMAN KODAK, HEALTH AND ENVIRONMENTA L LABORATORIES. 12 p.
92183010 Wislocki, P. (1990) Merck & Co. Inc.. Phase 3 Summary of MRID 41192004. Acute Toxicity of Thi abendazole to Eastern Oysters ( Crassostrea virginica ) under Flow-through Conditions: Study #359-888.6107.504. Prepared by SPRINGBORN LIFE SCIENCES, INC. 12 p.
92183011 Wislocki, P. (1990) Merck & Co. Inc.. Phase 3 Summary of MRID 41192002. Acute Toxicity of Thiabendazole to Mysid Shrimp ( Mysidopsis bahia ) under Flow-through Conditions: Study No. 359.0888.6105.515. Prepared by SPRINGBORN LIFE SCIENCES, INC. 12 p.


## 72-4 Fish Early Life Stag e/Aquatic Invertebrate Life Cycle Study

MRID Citation Reference

94644 LeBlanc, G.A.; Mastone, J.D.; Wilson, B.F. (1981) The Toxicity of Mertect Fungicide to Fathead Minnow ( Pimephales promelas ) Embryos and Larvae: Report #B W-81-5-890. (Unpublished study received Jan 19, 1982 under 618-75; prepared by EG & G Bionomics, submitted by Merck & Co., Inc., Rahway, N.J.; CDL: 246711-A)

94645 LeBlanc, G.A.; Mastone, J.D.; Suprenant, D.C.; et al. (1981) The Chronic Toxicity of Mertect Fungicide to the Water Flea ( Daphnia magna ): Report #BW-81-6-900. (Unpublished study received Jan

### 38 19, 1982 under 618-75; prepared by EG & G Bionomics, submitted by Merck & Co., Inc., Rahway, N.J.; CDL: 246711-B)
97969 LeBlanc, G.A.; Mastone, J.D.; Wilson, B.F. (1982) The Toxicity of Mertect Fungicide to Rainbow Trout ( Salmo gairdneri ) Embryos and Larvae: Report #BW-82-1-1099. (Unpublished study received Mar 25, 1982 under 618-75; prepared by EG & G, Bionomics, sub- mitted by Merck & Co., Inc., Rahway, N.J.; CDL:247102-A)

42508901 Holmes, C.; Swigert, J. (1992) Thiabendazole: An Early LifeStage Toxicity Test with the Fathead Minnow ( Pimephales promelas ): Lab Project Number: 105A-111. Unpublished study prepared by Wildlife International Ltd. 58 p.
40789802 LeBlanc, G.; Mastone, J.; Surprenant, D. (1981) The Chronic Toxicity of Mertect Fungicide to the Water Flea ( Daphnia magna ): Supplement to MRID 94645: Project ID. BW-81-6-900. Unpublished study prepared by EG & G Bionomics. 6 p.



## 171-4A2 Nature of the Residue in Plants

MRID Citation Reference

5001172 Verma, R.K.; Vyas, S.C. (1976) Uptake, translocation and persistence of five systemic fungicides in gram seedlings. Pesticides 10(12):21-24.

5002793 Bolkan, H.A.; Milne, K.S. ( 1975) Systemic uptake of four fungicides by potato plants. Plant Disease Reporter 59(3):214- 218.



## Environmental Fate
060101 Thiabendazole Fate Chemistry Bibliography

161-1 Hydrolysis

MRID Citation Reference

122852 Wolf, F. (1972) Letter sent to Buck dated Aug 29, 1972: TBZ sugar beets pesticide: Project No. 5734 0360. (Unpublished study received Jan 28, 1972 under 2F1237; submitted by Merck & Co., Inc., Rahway, NJ; CDL:094101-D)

123315 WARF Institute, Inc. (1976) En vironmental Chemistry: Hydrolysisof Radiolabelled Thiabendazole in Aqueous Solutions. (Unpublished study received Aug 4, 1977 under 618-75; submitted by Merck & Co., Inc., Rahway, NJ; CDL:232424-C)

### 39 146781 Warf Institute, Inc. (1976) En vironmental Chemistry Hydrolysis ofRadiolabelled Thiabendazole in Aqueous Solutions: Report a. Unpublished report. 128 p.
41265301 Kabler, K.; Dykes, J. (1989) Hydrolysis as a Function of pH at 25 Degrees C of Carbon-14-Thiabendazole: ABC Final Report #37636. Unpublished study prepared by Analytical Bio-Chemistry Laboratories, Inc. 309 p. 92183026 Van den Heuvel, W. (1990) Merck & Co. Inc.. Phase 3 Summary of MRID 41265301. Hydrolysis a Func tion of pH at 25 [degrees] of [Carbon-14]- pH at 25 [degrees] of [Carbon-14]- Thiabendazole: Project 37636. Prepared by AN ALYTICAL BIO-CHEMISTRY LABORATORIES INC. 10 p.


## 161-2 Photodegradation -- Water

MRID Citation Reference

146780 Warf Institute, Inc. (1976) Environmental Chemistry Photochemical Degradation of Thiabendazole: Report b. Unpublished report. 74 p.

123316 WARF Institute, Inc. (1976) Environmental Chemistry: Photochemical Degradation of Thiabendazole. (Unpublished study received Aug 4, 1977 under 618-75; submitted by Merck & Co., Inc., Rahway, NJ; CDL:232424-D)

41258203 See 41265101 Kabler, K.; Dykes, J. (1989) Dete rmination of the Photolysis Rate of [Carbon - 14]-Thiabendazole in pH 5 Buffered Solution at 25 degree C: Project ID 37637. U npublished study prepared by Analytical Bio-Chemistry Laboratories, Inc. 743 p.
41265101 Kabler, K.; Dykes, J. (1989) De termination of the Photolysis Rate of (Carbon - 14)-Thiabendazole in pH 5 Buffered Solution at 25 [Degree] C.: ABC Final Report #37637. Unpublished study prepared by Analytical Bio-Chem istry Laboratories, Inc. 576 p.
43328305 Flynn, J. (1994) Determinati on of the Aqueous Photolysis Rate of (carbon 14)-Thiabendazole: Final Report: Lab Project Number: 41285. Unpublished study prepared by ABC Labs, Inc. 82 p.
92183027 Van den Heuvel, W. (1990) Merck & Co. Inc.. Phase 3 Summary of MRID 41265101. Determination of the Photolysis Rate of [Carbon-14]- Thiabendazole in pH 5 Buffered Solution at 25 [degrees]: [Carbon-14]- Thiabendazole Project 37637. Prepared by ANALYTICAL BIO-CHEMISTRY LABORATORIES. 11 p.


## 161-3 Photodegradation -- Soil

MRID Citation Reference

70750 Chib, J.S.; North, S.P.; Harri son, S.L. (1980) Chloramben (3-

### 40 Amino- 2,5-dichlorobenzoic Acid) Hydrolytic Degradation Studies: Project No. 00010121/780A. (Unpublished study received Feb 18, 1981 under 264-138; submitted by Union Carbide Agricultural Produc ts Co., Inc., Ambler, Pa.; CDL:244443-C)
120017 Merck, Sharp & Dohme (1971) Results of Tests on the Amount of Residue Remaining; Including a Description of Analytical Methods: (Thiabendazole). (Compilation; unpublished study received Aug 13, 1972 under 2F1237; CDL:091094-A)
123324 Schroeder, C. (1978) Photodegradation of Thiabendazole in Soil. (Unpublished study received Jul 5, 1978 under 618-75; prepared by WARF Institute, In c., submitted by Merck & Co., Inc., Rahway, NJ; CDL:235632-B)
41397301 Dykes, J.; Kabler, K. (1990) Determination of the Photolysis Rate of [Carbon 14]-Thiabendazole on the Surface of Soil: (Revised Final Report): Lab Project Number: 37638. Unpublished study prepared by Analytical Bio-Chemistry Laboratories, Inc. 602 p.
41397302 Dykes, J. (1990) Determinat ion of the Photolysis Rate of [Carbon 14] Thiabendazole on the Surface of Soil Supplemental Data: Lab Project Number: 376381. Unpublished study prepared by Analytical Bio-Chemistry Laboratories, Inc. 32 p.
92183037 Van den Heuvel, W. (1990) Merck & Co. Inc.. Phase 3 Summary of MRID 41397301 and Related MRIDs 41397302. Determination of the Photolysis Rate of [Carbon 14]- Thiabendazole on the Surface of Soil: Project 37638. Prepared by Analytical Bio-Chem istry Laboratories, Inc. 11 p.



## 162-1 Aerobic Soil Metabolism

MRID Citation Reference

123321 WARF Institute, Inc. (1976) Environmental Chemistry: Metabolic Fate of Radiolabelled Thiabendazole in Soil: (Soil Metabolism): Report d. (Unpublished study received Aug 4, 1977 under 618-75; submitted by Merck & Co., Inc., Rahway, NJ; CDL:232423-A)

146782 Warf Institute, Inc. (1976) Metabolic Fate of Radiolabelled Thia-endazole in Soil (Soil Metabolism): Report d. Unpublished report. 145 p.

41791201 Daly, D.; Williams, M. (1991) Aerobic Soil Metabolism of [Carbon 14] Thiabendazole: Final Rept: Lab Project Number: 37639. Unpublished study prepared by Analytical Bio-Chemistry Laboratories, Inc. 1876 p.



## 162-2 Anaerobic Soil Metabolism

### 41 MRID Citation Reference

146782 Warf Institute, Inc. (1976) Metabolic Fate of Radiolabelled Thiabendazole in Soil (Soil Metabolism): Report d. Unpublished report. 145 p.

41559601 Daly, D.; Williams, M. (1990) Anaerobic Soil Metabolism of [Carbon 14] Thiabendazole: ABC final Report 37640. Unpublished study prepared by Analytical Bio-Chemistry Laboratories, Inc. 1062 p.



## 162-3 Anaerobic Aquatic Metabolism

MRID Citation Reference

122888 Steele, J.; Lechnir, R. (1979) Environmental Chemistry: Thiabendazole--Anaerobic Aquatic Metabolism. Interim rept. C. (Unpublished study received Jul 31, 1979 under 618-75; prepared by Raltech Scientific Services, Inc., submitted by Merck & Co., Inc., Rahway, NJ; CDL:098855-A)
ACC244423 Thiabendazole Anaerobic Aquat ic Metabolism, report (final), Jan. 14, 1981, by Raltech Sci entific Services for Merck and Co., Rathway, NJ, Accession No. 244423.


## 163-1 Leaching , Adsorption/Desorption

MRID Citation Reference

70748 Chib, J.S.; North, S.P.; Harri son, S.L. (1980) Chloramben (3- Amino- 2,5-dichlorobenzoic Acid) Adsorption and Desorption Studies: Project No. 10121/1080. (Unpublished study received Feb 18, 1981 under 264-138; prepared in cooperation with A & L Agric. Lab., Inc., submitted by Union Carbide Agricultural Produc ts Co., Inc., Ambler, Pa.; CDL:244443-A)

70749 Chib, J.S.; North, S.P.; Harrison, S.L. (1980) Chloramben (2,5-Di- chloro-3-aminobenzoic Acid) Leaching Studies: Project No. 00010121/780B. (Unpublished study received Feb 18, 1981 un- der 264-138; prepared in cooperation with A & L Agricultural Laboratories, Inc., submitted by Union Carbide Agricultural Products Co., Inc., Ambler, Pa.; CDL:244443-B)

117800 Lauber, J. (1970) Letter sent to B. Greenwald dated Jan 20, 1970: Soil study with thiabendazole--review of Erwin and Borum study. (Unpublished study received Apr 21, 1970 under 0F0881; sub- mitted by Merck & Co., Inc., Rahway, NJ; CDL:091522-A)

120631 Aharonson, N.; Kafkafi, U. (1975) Adsorption, mobility, and per- sistence of thiabendazole and methyl 2-

### 42 benzimidazolecarbamate in soils. J. Agric. Food Chem. 23(4):720-724. (Also In unpub- lished submission received Sep 27, 1979 under 4581-340; sub- mitted by Agchem Div., Pennwalt Corp., Philadelphia, PA; CDL: 099006-L)
121795 Erwin, D.; Borum, D. (1970) Persistence of Thiabendazole in Soil. (Unpublished study received 1970 under 0F0881; prepared by Univ. of Californi a--Riverside, Dept. of Plant Pathology, submitted by Merck & Co., Inc., Rahway, NJ; CDL:093178-B)
123300 Steele, J. (1979) Environment al Chemistry: Partition of Thiabendazole between Water and Soils. (Unpublished study received Jul 31, 1979 under 618 -75; prepared by Raltech Scientific Services, Inc., submitted by Merck & Co., Inc., Rahway, NJ; CDL: 098856-A)
Not Given Mobility of Thiabendazole Aerobically Aged in Soil and Photodegraded Thiabendazole Collin Schroeder and John Steele, WARF Institute, Inc .
123317 WARF Institute, Inc. (1976) Environmental Chemistry: Soil Leaching Study: Column Method Radiolabelled Thiabendazole. (Unpublished study received Aug 4, 1977 under 618-75; submitted by Merck & Co., Inc., Rahway, NJ; CDL:232424-E)
146783 Warf Institute, Inc. (1976) Soil Leaching Study: Column Method Radiolabelled Thiabendazole: Report c. Unpublished report. 90 p.
Not provided Thiabendazole Aerobically Aged in soil and Photodegraded Thiabendazole.

123323 Schroeder, C. (1978) Soil Mobility of Thiabendazole Aerobically Aged in Soil and Photodegraded Thiabendazole. (Unpublished study received Jul 5, 1978 under 618-75; prepared by WARF Institute, In c., submitted by Merck & Co., Inc., Rahway, NJ; CDL: 235632-A)

41170102 Dykes, J. (1989) "Soil Adsorption/Desorption with Thiabendazole": Project ID: Final Report No. 37635. Unpublished study prepared by Analytical Bio-Chemistry Laboratories, Inc. 339 p.

92183038 Van den Heuvel, W. (1990) Merck & Co. Inc.. Phase 3 Summary of MRID 41170102. Soil Adsorption/Desorption withThiabendazole: Project 37635. Prepared by Analytical BioChemistry Labs. 12 p.



## 164-1 Terrestrial Field Dissipation

MRID Citation Reference

98889 Chevron Chemical Company (1979) ?Residue Data from Soil in Which Potato Tubers Were Grown from Seed Pieces

### 43 Treated with Ortho- cide-mertect 10-0.5 Seed Protectant|. (Compilation; unpublished study received Sep 18, 1979 under 239-2474; CDL:241044-A)
123322 WARF Institute, Inc. (1976) Environmental Chemistry: Field Dissipation Studies: Thiabendazole: Report e. (Unpublished study received Aug 4, 1977 under 618-75; submitted by Merck & Co., Inc., Rahway, NJ ; CDL:232423-B; 235632)
Not provided Supplement to Thiabendazole Field Dissipation Studies Collin Schroeder and John Steele WARF Institute. Inc.

43187201 Jacobson, B. (1994) Terrestrial Field Dissipation for Thiabendazole in Wheat: Lab Project Number: 618-360- 92530: 37853-3. Unpublished study prepared by Qualls Agricultural Labs. and ABC Labs., Inc. 178 p.

43187202 Jacobson, B. (1994) Terrestrial Field Dissipation for Thiabendazole in Soybeans: Lab Project Number: 618-360- 92516: 38043. Unpublished study prepared by Agri-Growth Research, Inc. and ABC Labs., Inc. 187 p.

43187203 Jacobson, B. (1994) Terrestrial Field Dissipation for Thiabendazole in Soybeans: Lab Project Number: 618-360- 92678: 38042. Unpublished study prepared by Research Options, Inc. and ABC Labs., Inc. 177 p.



## 164-2 Aquatic Field Dissipation

MRID Citation Reference

122856 Interregional Research Project No. 4 (1974) Environmental Study on Thiabendazole|. (Unpublished study received 1974 under 4E1478; CDL:095866-A)

123301 Steele, J. (1979) Thiabendazole: Combined Field Dissipation and Water Dispersal from Rice Paddies. (Unpublished study received Jul 31, 1979 under 618 -75; prepared by Raltech Scientific Services, Inc., submitted by Merck & Co., Inc., Rahway, NJ; CDL: 098857-A)


## 164-5 Long-term Soil Dissipation

MRID Citation Reference

146784 Warf Institute, Inc. (1976) Field Dissipation Studies: Thiabendazole: Report e. Unpublished report. 337 p.

146785 Steele, J.; Schroeder, C.; Morton, S. (1977) Supplement to Thiabendazole Field Dissipation Studies: Report e:Mertect 340-F. Unpublished report prepar ed by Warf Institute, Inc. 241 p.

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## 165-4 Bioaccumulation in Fish

MRID Citation Reference

41631801 Hirsch, M. (1990) Bioconcentration of Thiabendazole(2-(4- Thiozolyl) -1H-Benzimidaz ole) in Bluegill Sunfish, Lepomis macrochirus : Final Report: Lab Project Number: EN-456- GWN004-1. Unpublished Study prepared by Eastman Kodak Co., Health and Envir. Laboratories. 235 p.

42022701 Hirsch, M. (1991) Bioconcentration of Thiabendazole (2-(4- thiazo- lyl)-1H-Benzimidaz ole) in Bluegill Sunfish, Lepomis macrochirus : Lab Project Number: GWN009: 90-0313. Unpublished study prepared by Eastman Kodak Co. 267 p.

123320 WARF Institute, Inc. (1976) Environmental Chemistry: Accumulation and Dissipation of Thiabendazole in Catfish. (Unpublished study received Aug 4, 1977 under 618-75; submitted by Merck & Co., Inc ., Rahway, NJ; CDL:232425-C)


## Non-Guideline Study

MRID Citation Reference

97322 Hine, R.B.; Johnson, D.L. ; Wenger, C.J. (1969) The persistency of two benzimidazol e fungicides in soil and their fungistatic activity against phymatotrichum omnivorum

. Phytopathology 59(Jun):798-801. (Also in unpublished submission received Dec 29, 1969 under 0F0936; submitted by E.I. du Pont de Nemours & Co., Inc., Wilmington, Del.; CDL:093241-C)

121796 Lauber, J. (1970) Letter sent to B. Greenwald dated Jan 16, 1970: Soil study with thiabendazole--review of articles by Hine et al. (Unpublished study received 1970 under 0F0881; submitted by Merck & Co., Inc ., Rahway, NJ; CDL:093178-C)

123319 WARF Institute, Inc. (1974) Envi ronmental Chemistry: Effect of Thiabendazole on Soil Microorganisms. (Unpublished study received Aug 4, 1977 under 618-75; submitted by Merck & Co., Inc., Rahway, NJ; CDL:232425-B)

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## Appendix B
SIP Model Output

Table 1. Inputs Parameter Value Chemical name Thiabendazole Solubility (in water at 25 o C; mg/L) 50

Mammalian LD 50 (mg/kg-bw) 4734 Mammalian test species laboratory rat Body weight (g) of "other" mammalian species

Mammalian NOAEL (mg/kg-bw) 40 Mammalian test species laboratory rat Body weight (g) of "other" mammalian species

Avian LD 50 (mg/kg-bw) 2250 Avian test species northern bobwhite quail Body weight (g) of "other" avian species Mineau scaling factor 1.15

Mallard NOAEC (mg/kg-diet) 400 Bobwhite quail NOAEC (mg/kg-diet) 400 NOAEC (mg/kg-diet) for other bird species Body weight (g) of other avian species NOAEC (mg/kg-diet) for 2nd other bird species Body weight (g) of 2nd other avian species

Table 2. Mammalian Results Parameter Acute Chronic Upper bound exposure (mg/kg-bw) 8.6000 8.6000 Adjusted toxicity value (mg/kg-bw) 3641.2061 30.7664 Ratio of exposure to toxicity 0.0024 0.2795

Conclusion* Drinking water exposure alone is NOT a potential

concern for mammals Drinking water exposure alone is NOT a potential

concern for mammals

### 46 Table 3. Avian Results Parameter Acute Chronic Upper bound exposure (mg/kg-bw) 40.5000 40.5000 Adjusted toxicity value (mg/kg-bw) 1620.9664 19.8450 Ratio of exposure to acute toxicity 0.0250 2.0408

Conclusion* Drinking water exposure alone is NOT a potential concern for birds Exposure through drinking water alone is a potential concern for birds

*Conclusion is for drinking water exposure alone. This does not combine all routes of exposure. Therefore, when aggregated with other routes ( i.e ., diet, inhalation, dermal), pesticide exposure through drinking water may contribute to a total exposure that has potential for effects to non-target animals.