Thiabendazole Summary of Analytical Chemistry and Residue Data DP#: 363974

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C. 20460

OFFICE OF PREVENTION, PESTICIDE

AND TOXIC SUBSTANCES

MEMORANDUM

Date: February 25, 2014

SUBJECT: Thiabendazole. PP# 3F8166. New Seed Treatment Uses on Assorted Vegetables 

and Small Grains (vegetable, root (except sugar beet); subgroup1B, onion, bulb, 

subgroup 3-07A; Brassica, head and stem, subgroup 5A; vegetable, cucurbit 

group 9; alfalfa; spinach (including baby); and small grains (wheat, barley, oats, 

rye, and triticale). Amendment to Increase Rate on Soybean. Summary of 

Analytical Chemistry and Residue Data. Multiresidue Method Data.

PC Code: 060101 DP Barcode: D410807, D410833, D313507

Decision No.: 476711, 476712 Registration No.: 100-889, 100-963

Petition No.: 3F8166 Regulatory Action: Section 3 Registration

Risk Assessment Type: Res Chem Case No.: 2760

TXR No.: NA CAS No.: 148-79-8

MRID No.: See MRID Summary Table 40 CFR: 180.242

Ver.Apr.08

FROM: Susan V. Hummel, Senior Chemist

Risk Assessment Branch 4

Health Effects Division (7509P)

THROUGH: Thurston G. Morton, Senior Chemist

Risk Assessment Branch 4

Health Effects Division (7509P)

TO: Rosemary Kearns/Tony Kish, PM 22

Fungicide Branch, Registration Division (7505P)

MRID Summary Table

MRID No. Study Type Comments

48996701 860.1500 Alfalfa New DER; 48996701.der.doc

48996702 860.1500 Barley New DER; 48996702.der.doc

48996703 860.1500 Wheat

860-1520 Wheat Processing

New DER; 48996703.der1.doc

New DER; 48996703.der2.doc

48996704 860.1500 Carrot, Radish New DER: 48996704.der.doc

48996705 860.1500 Cantaloupe, Cucumber, Summer 

Squash

New DER; 48996705.der.doc

48996706 860.1500 Broccoli, Cabbage New DER; 48996706.der.doc

48996707 860.1500 Spinach New DER; 48996707.der.doc
Thiabendazole Summary of Analytical Chemistry and Residue Data DP#: 363974

MRID Summary Table

MRID No. Study Type Comments

48996708 860.1900 Field Accumulation in Rotational 

Crops

New DER; 48996708.der.doc

48996709 860.1500 Soybean

860.1520 Soybean processing

New DER; 48996709.der1.doc

New DER; 48996709.der2.doc

48996710 860.1500 Dry bulb onion New DER; 48996710.der.doc

48996711 860.1340 Analytical Method in Crops New DER; 48996711.der.doc

48996712 860.1380 Storage Stability – Crops New DER: 48996712-13.der.doc

48996713 860.1380 Storage Stability – Processed 

Comodities

46469301 860.1360 Multiresidue Method Reviewed herein

Executive Summary

Thiabendazole [2-(4-thiazolyl)benzimidazole] is a benzimidazole fungicide currently registered 

for use as a seed or seed piece treatment to dry pea, potato, sweet potato, soybean, and wheat. It 

is also registered for use on mushrooms and is mostly used post-harvest as a dip or spray on 

citrus fruits, apples, pears, bananas, mangos, papaya, plantain, carrots, and potatoes. The 

Thiabendazole Reregistration Eligibility Decision (RED) was issued October 2002. A human 

health risk assessment was completed in June 2001 for the RED. 

Tolerances for plant commodities are established under 40 CFR §180.242(a) and are expressed 

in terms of combined residues of thiabendazole and its metabolite benzimidazole (free and 

conjugated); tolerances range from 0.1 ppm for dry bean seed and soybean to 40.0 ppm for 

mushroom. Tolerances for livestock commodities are established under 40 CFR §180.242(b) 

and are expressed in terms of combined residues of thiabendazole, 5-hydroxythiabendazole (free 

and conjugated), and benzimidazole. 

Syngenta Crop Protection is requesting registration of new seed treatments uses on assorted 

vegetables and small grains (vegetable, root (except sugar beet); subgroup1B, onion, bulb, 

subgroup 3-07A; Brassica, head and stem, subgroup 5A; vegetable, cucurbit group 9; alfalfa; 

spinach (including baby); and small grains (wheat, barley, oats, rye, and triticale). Tolerances 

already exist for wheat grain and wheat processed commodities. The product to be used is 

Mertect 34F, a 42.3% (4.1 lb ai/gal) flowable concentrate formulation (EPA Reg. No. 100-889). 

The uses are to be added to the Thiabendazole Technical label, as well (EPA Reg. No. 100-963). 

The 4.1 lb ai/gal Flowable Concentrate formulation is proposed for seed treatment use at 0.0 02 –

0.1 mg ai/seed, depending on the commodity. 

Syngenta is also requesting an amendment to the registration for Mertect 34F, a 42.3% (4.1 lb 

ai/gal) flowable concentrate formulation (EPA Reg. No. 100-889), to increase the application 

rate for soybean seed treatment. This amendment is not a part of the petition; no increased 

tolerance is requested.

Under the current action, Syngenta has submitted a petition for tolerances associated with the 

proposed use, PP# 3F8166. Tolerances at the total limit of quantitation of 0.02 ppm were 

proposed for residues of thiabendazole and its metabolite benzimidazole on vegetable, root 

(except sugar beet); subgroup1B, onion, bulb, subgroup 3-07A; Brassica, head and stem, 

subgroup 5A; vegetable, cucurbit group 9; alfalfa seed, forage, and hay; and spinach (including 
Thiabendazole Summary of Analytical Chemistry and Residue Data DP#: 363974

baby); and at 0.05 ppm on barley, oats, rye, and triticale grains; 0.15 ppm on barley hay and 

straw and rye straw; 0.2 ppm on wheat, oats, rye, and triticale forage; and 0.09 ppm on wheat 

hay and oats and triticale hay and straw. Syngenta submitted residue data to support the 

proposed uses. Syngenta also has included field trial and processing studies on soybean, and 

storage stability data, both of which were required under the Reregistration Eligibility Document 

(RED). The field trial data submitted for wheat may fulfill the RED data requirement for data 

for wheat, and constitute a full set of residue data, so these data may be used to reevaluate the 

existing wheat tolerances.

The nature of the residue in plants is understood based on acceptable plant metabolism studies 

conducted in wheat, soybean, and sugar beet. The residues of concern in crops for purposes of 

tolerance enforcement and risk assessment are thiabendazole and its metabolite benzimidazole 

(free and conjugated). The nature of the residue in livestock is understood based on acceptable 

hen and goat metabolism studies. The residues of concern in livestock commodities are 

thiabendazole, 5-hydroxy-thiabendazole (free and conjugated), and benzimidazole. Based on the 

available confined rotational crop study, the residues of concern in rotated crops are the same as 

those in primary crops. 

Acceptable enforcement analytical methods are available for thiabendazole and benzimidazole in 

plant commodities. Four spectrophotofluorometric methods for the determination of 

thiabendazole are published in the Pesticide Analytical Manual (PAM) Vol. II, and a high 

performance liquid chromatography (HPLC) method with fluorescence detection (FLD) for the 

determination of benzimidazole (free and conjugated) is identified in the U.S. EPA Index of 

Residue Analytical Methods under thiabendazole as Study No. 93020. The validated limits of 

detection (LODs) for the thiabendazole methods range from 0.05-0.1 ppm, and the validated 

limit of quantitation (LOQ) for the benzimidazole method is 0.1 ppm. 

Samples from the submitted crop field trial and processing studies were analyzed for residues of 

thiabendazole and benzimidazole using a high performance liquid chromatography/tandem mass 

spectrometry (LC/MS/MS) method, GRM040.01A. The method LOQ was 0.01 ppm, and the 

stated LOD was 0.004 ppm; LODs of 0.005 and 0.003 ppm were reported in the crop field trial 

and processing study submissions. Adequate method validation data were submitted for the 

method, and the method was adequately validated concurrently with the submitted field trial and 

processing studies, including validation at the LOD (0.003 ppm) in the Canadian crop field trials. 

HED concludes that the method is sufficiently sensitive and has been adequately validated for 

the purposes of making a Threshold of Regulation determination.

Adequate crop field trial data from the U.S. have been submitted to support the proposed seed 

treatment uses on vegetable, root (except sugar beet); subgroup1B, onion, bulb, subgroup 3-07A; 

Brassica, head and stem, subgroup 5A; vegetable, cucurbit group 9; alfalfa; spinach (including 

baby); and small grains (wheat, barley, oats, rye, and triticale). Residues of thiabendazole and 

benzimidazole were each below the method LOQ of 0.01 ppm (total LOQ of 0.02 ppm) in all 

samples of vegetable, root (except sugar beet); subgroup1B, onion, bulb, subgroup 3-07A; 

Brassica, head and stem, subgroup 5A; vegetable, cucurbit group 9; alfalfa; and spinach. Finite 

residues were reported in some samples of barley and wheat grain, forage, hay and straw. 

Additionally, field trial data were submitted for soybeans, in response to a RED data 

requirement. The wheat and soybean field trial data submitted with this petition satisfy the RED 

data requirement for additional field trial data for wheat and soybeans.
Thiabendazole Summary of Analytical Chemistry and Residue Data DP#: 363974

Adequate wheat and soybean processing studies were submitted, both reflecting a 5x application 

rate. The soybean processing study was submitted in response to a RED data requirement. The 

wheat samples treated at a 5x application rate were processed into bran, flour, middlings, shorts 

and germ using simulated commercial procedures. Residues of thiabendazole were 

nonquantifiable in wheat grain and all wheat processed commodities. The soybean samples 

treated at a 5x application rate were processed into meal, hulls, refined oil, flour, milk, tofu, soy

sauce, miso, pollard and crude oil using simulated commercial procedures. Residues of 

thiabendazole were nonquantifiable in soybeans and all soybean processed commodities. 

Therefore, HED concludes that residues of thiabendazole or its regulated metabolite, 

benzimidazole, are not likely to concentrate in the processed commodities of wheat and 

soybeans.

A limited field rotational crop study was required in the RED and was included in the current 

submission. In 13 rotational crop trials, after application to the soil at a rate typical of seed 

treatment application rates, residues of thiabendazole and benzimidazole were nonquantifiable

(<0.02 ppm total) in samples of lettuce, radish, and wheat commodities planted 30, 60, and 270 

days after treatment. This study satisfies the RED data requirement for rotational crop studies.

Regulatory Recommendations and Residue Chemistry Deficiencies

Based on residue chemistry considerations only, HED concludes that tolerances can be 

supported for residues of thiabendazole and its regulated metabolite benzimidazole in vegetable, 

root (except sugar beet); subgroup1B, onion, bulb, subgroup 3-07A; Brassica, head and stem, 

subgroup 5A; vegetable, cucurbit group 9; alfalfa; spinach (including baby); or small grain

(wheat, barley, oats, rye, and triticale) commodities grown from treated seed; in the processed 

commodities of wheat; and in rotational crops as a result of seed treatment use proposed in this 

petition. The recommended tolerances may be found in Table 7 of this document.

The current tolerance expression is not in accord with our current guidance. See 

recommendation in Section 860.1550 Proposed Tolerances. Updating the tolerance expression 

will be accomplished during registration review.

International Harmonization. Neither CODEX, nor Canada have established MRLs for 

thiabendazole on the proposed commodities. There is no issue with International Harmonization

for the current petition. 

Provided that the use directions are revised as requested, analytical standards are submitted as 

requested, and the storage stability studies reported here as an interim report, are completed and 

submitted as final reports, HED concludes that, based on the available residue data, the requested 

use of thiabendazole as a seed treatment for vegetable, root (except sugar beet); subgroup1B, 

onion, bulb, subgroup 3-07A; Brassica, head and stem, subgroup 5A; vegetable, cucurbit group 

9; alfalfa; spinach (including baby); and small grains (wheat, barley, oats, rye, and triticale) may

be registered once tolerances are established as recommended in Section 860.1550 Proposed 

Tolerances.

A human health risk assessment for thiabendazole will be conducted in connection with this 

action. 
Thiabendazole Summary of Analytical Chemistry and Residue Data DP#: 363974

860.1200 Directions for Use

 The registrant should revise the label to include the use rates in terms of weight of 

product per weight of seed (e.g. g/100 kg seed).

860.1380 Storage Stability

 The storage stability studies currently in progress (reported in an interim report) must be 

completed to fully support the field trial and processing studies for the current petition. 



860.1650 Submittal of Analytical Reference Standards

 For benzimidazole, a new standard must be submitted. For 5-hydroxy-thiabendazole, the 

registrant must either recertify the lot in the repository and send in an updated certificate 

of analysis (COA), or submit new standards (different lot #) if the previous lots will not 

be recertified. 

Background

The chemical structure and nomenclature of thiabendazole and its regulated metabolites are 

presented in Table 1, and the physicochemical properties of the technical grade of thiabendazole 

are presented in Table 2. 

Table 1. Test Compound Nomenclature.

Compound

Common name Thiabendazole

Company experimental name None

IUPAC name 2-(thiazol-4-yl)benzimidazole

CAS name 2-(4-thiazolyl)-1H-benzimidazole

CAS registry number 148-79-8

End-use product (EP) 4.1 lb ai/gal FlC formulation (Mertect 34F; EPA Reg. No 100-889)

Compound

Common name Benzimidazole

Chemical name 1H-benzimidazole

CAS registry number 51-17-2

Compound

Common name 5-hydroxy-thiabendazole

N

H

N

S

N

N

H

N

N

H

N

S

HO N
Thiabendazole Summary of Analytical Chemistry and Residue Data DP#: 363974

Table 1. Test Compound Nomenclature.

Chemical name 2-(1,3-thiazol-4-yl)-1H-benzimidazol-5-ol)

Table 2. Physicochemical Properties of the Technical Grade Test Compound: Thiabendazole. 

Parameter Value Reference

Melting point/range 304-305 °C Thiabendazole RED 10/02

pH 5.16-5.97 Thiabendazole RED 10/02

Density 25-30 cc (tapped) Thiabendazole RED 10/02

Water solubility 0.028-0.030 mg/mL at 25 °C Thiabendazole RED 10/02

Solvent solubility

acetone

benzene

chloroform

dimethylformamide

dimethyl sulfoxide

ethanol 

ethyl acetate

methanol

25 oC

4.2 g/L

230 mg/L

80 mg/L

39 g/L

80 g/L

7.9 g/L

2.1 g/L (R.T.)

9.3 g/L

The Pesticide Manual, 8th edition

Vapor pressure 4 x 10 -9 mm Hg at 25 °C Thiabendazole RED 10/02

Dissociation constant, pKa Pka1 = 4.73; Pka2 = 12.00 Thiabendazole RED 10/02

Octanol/water partition coefficient Log(KOW) = 240-285 at pH 7 Thiabendazole RED 10/02

UV/visible absorption spectrum Neutral solution

32,170 L/mol*cm3at 205.5 nm

Acidic solution

41,520 L/mol*cm3at 303.5 nm

Neutral solution

40,553 L/mol*cm3at 215.5 nm

MRID 462868011

1 Data were referenced in MRID 47705121. 

860.1200 Directions for Use

Syngenta has submitted a draft label (dated 10/23/2013) and a description of the proposed use for 

the 4.1 lb ai/gal FlC formulation (Mertect 34F Fungicide; EPA Reg No. 100-889). 

The proposed use directions for corn are summarized in Table 3.

Table 3. Summary of Directions for Use of Thiabendazole.

Applic. Timing, Type, 

and Equip.

Formulation

[EPA Reg.

No.]

Applic. Rate 

Max. No. 

Applic. 

per 

Season

PHI

(days) Use Directions and Limitations

Alfalfa

Seed treatment,

Seed treatment 

application equipment

4.1 lb ai/gal F

[100-889]

0.004 mg 

ai/seed or 5.8 fl 

oz/100 lb seed

1 N/A Assumes an average seed size of

210,000 seeds/lb

Cereal Grains – Barley, Oats, Rye, Triticale, Wheat
Thiabendazole Summary of Analytical Chemistry and Residue Data DP#: 363974

Table 3. Summary of Directions for Use of Thiabendazole.

Applic. Timing, Type, 

and Equip.

Formulation

[EPA Reg.

No.]

Applic. Rate 

Max. No. 

Applic. 

per 

Season

PHI

(days) Use Directions and Limitations

Seed treatment,

Seed treatment 

application equipment

4.1 lb ai/gal F

[100-889]

0.03 mg ai/seed 

Barley 2.6 fl 

oz/100 lb seed

Oats 3.4 fl 

oz/100 lb seed

Rye 3.2 fl 

oz/100 lb seed

Triticale 2.6 fl 

oz/100 lb seed

Wheat 3.1 fl 

oz/100 lb seed

1 N/A

Barley- assumes an average seed 

size of 12,500 seeds/lb

Oats- assumes an average seed 

size of 12,500 seeds/lb

Rye - assumes an average seed 

size of 15,600 seeds/lb

Triticale - assumes an average 

seed size of 12,750 seeds/lb

Wheat - assumes an average seed 

size of 15,000 seeds/lb

Brassica Head & Stem subgroup; Bulb Vegetables; Vegetables, Root subgroup (except sugar beets)

Seed treatment,

Seed treatment 

application equipment

4.1 lb ai/gal F

[100-889]

0.002 mg 

ai/seed 

1 N/A

Cucurbit Vegetables

Seed treatment,

Seed treatment 

application equipment

4.1 lb ai/gal F

[100-889]

0.1 mg ai/seed 1 N/A

Spinach

Seed treatment,

Seed treatment 

application equipment

4.1 lb ai/gal F

[100-889]

0.006 mg 

ai/seed

1 N/A

Soybeans

Seed treatment,

Seed treatment 

application equipment

4.1 lb ai/gal F

[100-889]

0.03 mg ai/seed 1 N/A

No specific tank mix partners are identified; the label states, “This product must not be tank 

mixed with any pesticide unless physical compatibility and phytotoxicity tests have been 

completed and proved to be satisfactory.”

The label also notes that Federal law requires that bags containing treated seed shall be labeled 

with the following information: “This seed has been treated with thiabendazole fungicide. Do 

not use for feed, food, or oil purposes. Store away from feeds and foodstuffs. Do not allow 

children, pets or livestock to have access to treated seeds.” The label also states, “ Wear long 

pants, long-sleeved shirt and protective gloves when handling treated seed. Use an EPAapproved dye or colorant that imparts an unnatural color to the seed as required in 40 CFR 

153.155 (c). Do not feed vines or hay grown from treated seed to livestock. Do not plant any

crop, other than soybeans, dry peas, barley, wheat, oats, rye, and triticale, brassica head and stem 

subgroup 5A, cucurbit vegetable crop group 9, root vegetables (except sugar beets) subgroup 1B, 

bulb vegetables subgroup 3-07A, spinach and alfalfa, within 30 days to fields in which treated 

seeds were planted.” 

Conclusions. The proposed use directions are adequate to allow evaluation of the residue data 

presented herein. The submitted corn field trials were conducted according to the proposed use 
Thiabendazole Summary of Analytical Chemistry and Residue Data DP#: 363974

pattern, and the pre-grazing interval specified for corn forage is supported by the available data. 

Rates must also be stated in terms of lb ai (or product)/A.

860.1300 Nature of the Residue - Plants

47705109.der.doc

Revised Residue Chemistry Chapter of the Thiabendazole RED DP# 267871, 9/7/00, T. Morton

The qualitative nature of the residue in plants is adequately understood based on soybean, sugar 

beet, and wheat metabolism studies. The residues of concern in plants include thiabendazole and 

benzimidazole, free and conjugated. 

In support of the registered seed treatment use on corn, Syngenta Crop Protection submitted a 

study investigating the metabolism of [phenyl-U14C]thiabendazole in seed-treated corn. The 

test substance, formulated as a suspension concentrate (SC) formulation, was applied as a seed 

dressing to corn seed at 1.8x the proposed seed treatment rate for corn. Immature corn forage 

was collected at the final vegetative stage (V12), 81 days after planting (DAP); sweet corn cobs, 

kernels, and foliage (forage) were collected at the dough stage (R4), 101 DAP; and mature corn 

cobs, kernels, and foliage (stover) were collected at the R6 stage, 116 DAP.

TRR were 0.014 ppm in immature corn forage harvested at the V12 stage; 0.005 ppm in sweet 

corn forage harvested at the dough stage; and 0.002 ppm in mature corn stover harvested at the 

R6 stage. TRR were nondetectable in sweet corn kernels and cobs and mature corn kernels and 

cobs.

Only immature corn forage was extracted; all other corn matrices had TRR <0.01 ppm. 

Approximately 43% of the radioactivity was extracted from immature forage with ACN/water. 

The extract was separated into organic (13% TRR) and aqueous (16% TRR) phases; a 32% loss 

occurred with concentration for phase separation. Nonextractable residues accounted for ~56% 

TRR (0.008 ppm). Accountability was 98%.

Although the extractable radioactivity was low (0.006 ppm) in immature forage, the organic and 

aqueous phases were analyzed using normal and reverse phase TLC. Using normal phase TLC, 

radioactivity in the aqueous fraction was immobile; radioactivity in the organic phase moved 

from the origin, but distinct components were not resolved. With reverse phase TLC, 

radioactivity in both the aqueous and organic phases was diffused up the plate. Radioactivity

was observed at the origin, near the origin, and up most of the plate, indicative of varying 

polarity. Using normal and reverse phase TLC, no distinct component could be resolved which 

corresponded to thiabendazole. 

The study results demonstrate that metabolism of thiabendazole in corn at early growth stages 

(immature forge) results in multiple minor components of greater polarity than the parent. With 

plant growth, the TRR in foliage decreases, either by release as CO2 or dilution with increasing 

biomass. There was no evidence of translocation of residues into the reproductive parts of the 

plant including kernels and cobs.
Thiabendazole Summary of Analytical Chemistry and Residue Data DP#: 363974

860.1300 Nature of the Residue - Livestock

Revised Residue Chemistry Chapter of the Thiabendazole RED DP# 267871, 9/7/00, T. Morton

The qualitative nature of the residues in livestock is adequately understood based upon 

acceptable ruminant and poultry metabolism studies. The residues of concern in livestock 

commodities include thiabendazole, 5-hydroxy-thiabendazole (free and conjugated), and 

benzimidazole.

860.1340 Residue Analytical Methods

48996711 860.1340 Analytical Method in Crops

Revised Residue Chemistry Chapter of the Thiabendazole RED DP# 267871, 9/7/00, T. Morton

Residue Chemistry Memo DP#s 207850, etc., 1/8/99, S. Mason

Plant commodities

Enforcement analytical method: Adequate analytical methodology is available for data 

collection and enforcing tolerances of residues of thiabendazole per se. PAM Vol. II lists four 

spectrophotofluorometric methods (Methods I, A, B, and C) for determining residues of 

thiabendazole per se in or on plant commodities. In all of the methods, residues are extracted 

with ethyl acetate, and the extracts are purified by washing with dilute NaOH and/or HCl. The 

LODs range from 0.05-0.1 ppm.

In addition, an HPLC method with fluorescence detection (FLD) is available for the enforcement 

of tolerances for residues of free and conjugated benzimidazole. This method is listed in the 

U.S. EPA Index of Residue Analytical Methods under thiabendazole as Study No. 93020 (MRID 

43328302). The metabolite benzimidazole (and benzimidazole-related compounds) are extracted 

from plant commodities with methanol and refluxing with 3 N KOH-rnethanol. The KOH is 

precipitated with concentrated hydrochloric acid. The enzyme β-glucosidase is used to free 

benzimidazole from benzimidazole-related compounds. The residues are acidified with HCI and 

the aqueous portion is separated and cleaned up with ethyl acetate, pH adjusted to 9-12, extracted 

with ethyl acetate. The residue is reconstituted with 1% ammonium acetate in water and 

analyzed for benzimidazole by reverse phase HPLC using a Supelco LC-8-DB, column (or 

equivalent) with a mobile phase of 750 mL water:250 mL methanol:1 g ammonium acetate and 

fluorescence detection. The reported LOQ is 0.1 ppm, and the LOD is 0.05 ppm in wheat grain, 

straw, and processed wheat commodities. 

Data collection methods: Syngenta Crop Protection, Inc. has submitted an LC/MS/MS method, 

GRM040.01A, for the determination of residues of thiabendazole and benzimidazole in crop 

matrices. The method was used for data collection in the submitted U.S. and Canadian corn field 

trials and the corn processing study.

Syngenta noted that the extraction procedures for Method GRM040.01A were adapted from 

Merck Methods M-041 and M-056 (reviewed under DP#s 207850, etc.) but that clean-up steps 

were removed, and MS/MS detection was used instead of FLD.

Briefly, homogenized crop samples are extracted with 0.025 M KH2PO4 (pH 6):ethyl acetate 

(25:10, v:v) and centrifuged. The ethyl acetate phase is collected, and the resulting aqueous 

phase is partitioned twice more with ethyl acetate followed by centrifugation. The ethyl acetate 

phases are combined with the original ethyl acetate phase, and the aqueous phase is subjected to 
Thiabendazole Summary of Analytical Chemistry and Residue Data DP#: 363974

evaporation at 40 °C to remove ethyl acetate, and acidified to pH 5.3-5.5 with concentrated 

H3PO4. The acidified extract is subjected to enzyme hydrolysis with β-glucosidase (for 2 hours 

at 38 °C) to remove conjugates, after which the hydrolysate is adjusted to pH 6.0-6.2 with 1 M 

NaOH and partitioned with ethyl acetate (three times). The resulting ethyl acetate phases are 

combined with the ethyl acetate phases that were previously collected, adjusted to volume as 

necessary with ethyl acetate, and redissolved in methanol for LC/MS/MS analysis. The method 

monitors a single ion transition for each analyte. The method LOQ is 0.01 ppm, and the LOD is 

0.004 ppm. The registrant adequately explained how the LOQ and LOD were determined.

The method was adequately validated using samples of field corn forage, grain, and stover, and 

sweet corn forage and K+CWHR fortified with each analyte at 0.01, 0.05, and 0.1 ppm. Overall 

recoveries were 81-118% (average of 104% and standard deviation of 7.4%) for thiabendazole 

and 71-119% (average of 95% and standard deviation of 12%) for benzimidazole.

Acceptable concurrent recovery data for the method were also submitted with the submitted U.S. 

and Canadian field trials and the field corn processing study. Concurrent recoveries were 

generally in the acceptable range of 70-120% for all raw agricultural and processed corn 

commodities. We note that fortification levels in the concurrent method validation conducted 

with analysis in the Canadian field trials included the stated LOD of 0.003 ppm.

No confirmatory procedures, independent laboratory validation (ILV), or radiovalidation data 

were included in the method submission. Because the method is not intended as an enforcement 

method, confirmatory procedures and ILV are not required. No radiovalidation data are required 

for the method because the extraction procedures are similar to those used in the plant 

metabolism studies for thiabendazole (refer to DP# 165718, 3/11/92, L. Cheng).

Samples from the banana and citrus storage stability study submitted under DP# 363974 were 

analyzed for residues of benzimidazole using Merck Methods M-057 and M-058, respectively. 

The HPLC/FLD methods are essentially identical, except that they are written for the specific 

crop. The reported method LOQ was 0.07 ppm for benzimidazole.

Briefly, homogenized samples were mixed with pH 8.0 buffer (adjusted as necessary with 0.2 N 

NaOH for citrus samples), extracted with ethyl acetate (2-3x), and centrifuged. The ethyl acetate 

extracts were applied to a cation exchange solid phase extraction column, and residues of 

benzimidazole were eluted with acetonitrile (ACN):water (30:70, v:v) containing 0.1 M KH2PO4. 

The eluate was adjusted to volume with ACN/water for analysis by cation exchange HPLC/FLD.

The methods were adequate for data collection based on acceptable concurrent method 

recoveries; recoveries were within the acceptable range of 70-120% for banana and orange 

samples fortified with benzimidazole at 0.10 ppm. 

Conclusions. The residue analytical methods data are adequate for data collection and 

enforcement.
Thiabendazole Summary of Analytical Chemistry and Residue Data DP#: 363974

860.1360 Multiresidue Methods

Revised Residue Chemistry Chapter of the Thiabendazole RED DP# 267871, 9/7/00, T. Morton

MRID 46469301

The FDA PESTDATA database (June 2005) indicates that thiabendazole is completely

recovered using FDA Multiresidue methods 302 and 404, and is not recovered through method 

303. Thiabendazole was not tested through method 304. Data on the recovery of the metabolites 

5-hydroxy-thiabendazole and benzimidazole through FDA Multiresidue Protocols were 

submitted in response to the Thiabendazole RED (MRID 46469301).

5-Hydroxy-thiabendazole was found to be amenable to GC, but was not recovered through

Section 302 Multiresidue Method. 5-Hydroxy-thiabendazole was also tested through Protocol A 

because it is a naturally fluorescent compound, but it did not chromatograph well on the LC 

system. Testing for 5-hydroxy-thiabendazole was terminated according to the Pesticide 

Analytical Manual, Vol. I (PAM 1)1, Decision Tree. No Multiresidue Method will be suitable for 

analysis of 5-Hydroxy-thiabendazole.

Benzimidazole (CGA-18306) was amenable to GC, but was not recovered through Section 302 

Multiresidue Method. Benzimidazole was also tested through Protocol A because it is a naturally

fluorescent compound, but did not produce adequate responses on the LC system. Testing for 

benzimidazole was terminated according to PAM I Decision Tree. No Multiresidue Method will 

be suitable for analysis of CGA-l 8306.

Conclusions. The data required in the Thiabendazole RED reflecting recovery of residues of 

benzimidazole through the FDA multiresidue methods have been provided.

Thiabendazole is completely recovered using FDA Multiresidue methods 302 and 404, and is not 

recovered through method 303. Benzimidazole and 5-hydroxy-thiabendazole are not recovered 

by the FDA multiresidue methods.

860.1380 Storage Stability

48996712 860.1380 Storage Stability – Crops

48996713 860.1380 Storage Stability – Processed Comodities

Residue Chemistry Memo DP# 270154, 2/22/01, T. Morton

Revised Residue Chemistry Chapter of the Thiabendazole RED DP# 267871, 9/7/00, T. Morton

Residue Chemistry Memo DP# 196149, 4/14/94, F. Suhre

Residue Chemistry Memo DP# 186592, 7/30/93, J. Abbotts

Storage stability data reviewed prior to the Thiabendazole RED (summarized in DP# 267871) 

indicated that residues of thiabendazole and benzimidazole are stable for up to 28 months in 

mushrooms stored at -23 °C; for up to 27 months in whole potatoes and wet peel stored at ≤0 °C; 

for up to 23 months in wheat grain and straw at ≤-15 °C; and for up to 18 months in wheat bran 

and flour stored at ≤-15 °C. In addition, storage stability data were reviewed prior to the RED 

indicating that residues of thiabendazole are stable for up to 9 months in apples, apple juice, and 

dried pomace store at -15 °C; for up to 3 months in whole bananas and banana pulp stored at -20 

°C; and for up to 9 months in citrus fruit, oil, molasses, and pulp stored at -26 °C.

Additional storage stability data for soybean are available (D267871) indicating that residues of 

thiabendazole are stable in soybean forage hay and seed stored at ~-20 °C for up to 1 year. Data 
Thiabendazole Summary of Analytical Chemistry and Residue Data DP#: 363974

demonstrate that residues of benzimidazole are relatively stable in banana stored frozen for up to 

3 months and in orange stored frozen for up to 6 months. 

In the current submission, Syngenta Crop Protection, LLC has submitted the results of storage 

stability studies with thiabendazole and metabolite benzimidazole in representative raw 

agricultural commodities (RACs; MRID 48996712), including dry navy bean, soybean seed (oil 

seed), spinach leaves (leafy vegetable), barley grain (non-oily grain), and orange (whole fruit; 

acidic fruit), and processed commodities (MRID 48996713) soybean oil and tomato puree. 

Samples in the study were stored at -20C. The RAC study is an interim report reflecting storage 

intervals of ~0, 3, and 9 months; the submission indicates that the study will be conducted 

through 24 months. The processed commodity study reflects storage intervals of ~0, 3, 6, 9 and 

12 months. For both studies, samples of untreated commodities were fortified with 

thiabendazole or benzimidazole at 0.1 ppm for each analyte and stored at ~-20 °C. Both studies 

were conducted by Morse Laboratories (Sacramento, CA).

The study indicates that residues of thiabendazole and metabolite benzimidazole are stable in dry

navy bean, soybean seed, spinach leaves, barley grain and orange stored frozen (-20 ± 5 °C) for 

up to 8.9-9.9 months (271-300 days; the length of the study), and that residues of these analytes 

are stable in soybean oil and tomato puree stored frozen (-20 to -10 °C) for up to 12.0-12.1

months (365-367 days; the length of the study). Storage stability of benzimidazole in spinach 

was low at the 9 month sampling interval.

The storage durations and conditions of samples from the submitted seed treatment field trials

and processing study are presented in Table 4. 

Table 4. Summary of Storage Conditions and Durations of Samples from the Corn Crop Field Trial

and Processing Studies. 

Matrix Storage 

Temperature

(°C)

Actual Storage Duration Interval of Demonstrated Storage 

Stability

Alfalfa forage ≤-10 40-366 days (1.3-12.0 months) Thiabendazole is reasonably stable under 

frozen storage conditions in/on wheat 

grain and straw for up to 23 months and 

in/on soybean forage, hay, and seed for up 

to 1 year. 

Acceptable storage stability data have 

been submitted demonstrating that

residues of thiabendazole and 

benzimidazole in/on representative raw 

agricultural commodities are stable during 

frozen storage for up to ~10 months. 

Alfalfa hay 40-426 days (1.3-14.0 months)

Alfalfa seed 40-89 days (1.3-2.9 months)

Barley Grain -10 at prep 

facility

-25 at 

analytical 

laboratory

87-388 days (2.9-12.8 months)

Barley Hay 69-354 days (2.3-11.6 months)

Barley Straw 90-392 days (3.0-12.9 months)

Wheat Grain 59-359 days (1.9-11.8 months)

Wheat Forage 61-353 days (2.0-11.6 months)

Wheat Hay 81-361 days (2.7-11.9 months)

Wheat Straw 58-323 days (1.9-10.6 months)

Carrot -10 at prep 

facility

-25 - -20 at 

analytical 

laboratory

90-257 days (3.0-8.5 months) Acceptable storage stability data have been 

submitted demonstrating that residues of 

thiabendazole and benzimidazole in/on 

representative raw agricultural commodities 

are stable during frozen storage for up ~10 

months. 

Radish 157-290 days (5.2-9.5 months)

Cantaloupe 51-396 days (1.7-13.0 months)

Cucumber 176-311 days (5.8-10.3 months)

Summer Squash 197-330 days (6.5-10.9 months)

Broccoli -10 at prep 

facility

-20 at 

93-308 days (3.1-10.1 months) Acceptable storage stability data have 

been submitted demonstrating that 

residues of thiabendazole and 

Cabbage 124-300 days (4.1-9.9 months)

Spinach 43-248 days (1.4-8.2 months)
Thiabendazole Summary of Analytical Chemistry and Residue Data DP#: 363974

Table 4. Summary of Storage Conditions and Durations of Samples from the Corn Crop Field Trial

and Processing Studies. 

Matrix Storage 

Temperature

(°C)

Actual Storage Duration Interval of Demonstrated Storage 

Stability

Dry Bulb Onion analytical 

laboratory

73-140 days (2.4-4.6 months) benzimidazole in/on representative raw 

agricultural commodities are stable during 

frozen storage for up to ~10 months. 

Residues of benzimidazole may decline 

slightly in/on spinach during frozen 

storage (corrected recovery of ~66% at 9 

months).

Rotational Lettuce -10 70-167 days (2.3-5.5 months)

Rotational Radish 30-211 days (1.0-6.9 months)

Rotational Wheat 71-348 days (2.3-11.4 months)

Soybean forage -10 at prep 

facility; -20

at analytical 

laboratory

221-273 days (7.3-9.0 months) Acceptable storage stability data have 

been submitted demonstrating that 

residues of thiabendazole and 

benzimidazole in/on representative raw 

agricultural commodities are stable during 

frozen storage for up to ~10 months

Soybean hay 22-274 days (7.3-9.0 months)

Soybean seed 181-224 days (6.0-7.4 months)

Processing study (samples analyzed for thiabendazole only)

Wheat Grain ≤-10 129-414 days (4.2-13.6 months) Thiabendazole is relatively stable in 

various crops, including wheat grain for 

up to 23 months of frozen storage and 22 

months in/on soybean grain.

Soybean Grain 109-125 days (3.6-4.1 months)

Wheat Bran 75-96 days (2.5-3.2 months) Thiabendazole is relatively stable in 

various processed commodities, including 

citrus oil for 9 months, and wheat bran 

and flour for up to 18 months of frozen 

storage, and 12 months in soybean oil

Wheat Flour 47-68 days (1.5-2.2 months)

Wheat Middlings 39-60 days (1.3-2.0 months)

Wheat Shorts 46-67 days (1.5-2.2 months)

Wheat Germ 43-63 days (1.4-2.1 months)

Soybean Processed

commodities

33-94 days (1.1–3.1 months)

Conclusions. The available and submitted storage stability data are not adequate to support the 

storage durations and conditions of samples from the corn crop field trial and processing studies. 

The storage stability studies currently in progress (reported in an interim report) must be 

completed to adequately support the field trial and processing studies for the current petition. 

860.1400 Water, Fish, and Irrigated Crops

The proposed use is not relevant to this guideline topic.

860.1460 Food Handling

This topic is not relevant to the proposed use.

860.1480 Meat, Milk, Poultry, and Eggs

Although there are livestock feed stuffs associated with the proposed use on corn, because 

residues were nonquantifiable in all field trial samples, the dietary burdens to livestock will not 

be affected. Therefore, data requirements pertaining to meat, milk, poultry, and eggs are not 

relevant to this action. 
Thiabendazole Summary of Analytical Chemistry and Residue Data DP#: 363974

860.1500 Crop Field Trials

48996701 860.1500 Alfalfa

48996702 860.1500 Barley

48996703 860.1500 Wheat

48996704 860.1500 Carrot, Radish

48996705 860.1500 Cantaloupe, Cucumber, Summer Squash

48996706 860.1500 Broccoli, Cabbage

48996707 860.1500 Spinach

48996708 860.1900 Field Accumulation in Rotational Crops

48996709 860.1500 Soybean

48996710 860.1500 Dry bulb onion

Alfalfa. Twelve alfalfa forage and hay field trials were conducted in the United States during the 

2011-2012 growing seasons in the North American Free Trade Agreement (NAFTA) Growing 

Zones 1 (PA; 1 trial); 2 (GA; 1 trial), 5 (MN, IA, ND, NE, WI; 6 trials), 7 (NE; 1 trial), 9 (UT; 1 

trial), 10 (CA; 1 trial), and 11 (ID; 1 trial). Two additional trials were conducted for collection 

of alfalfa seed only in NAFTA Growing Zones 9 (ID; 1 trial) and 10 (CA; 1 trial).

A flowable concentrate (water-dispersible suspension) for seed treatment (FS) formulation 

(Mertect® 340-F) containing 4.1 lb ai/gal thiabendazole was applied to alfalfa seeds before 

planting. The seeds were treated at the Syngenta Seeds facility (Stanton, MN) using commercial 

seed treatment procedures. The test substance was applied to the seeds using a CC20 or R12 

seed treater. Application rates for thiabendazole were 0.003-0.05 lb ai/A (3.4-56 g ai/ha). 

Application rates in lb ai/A were calculated by the petitioner from approximate seeding rate 

(387,659 seed/A to 5,140,777 seed/A) and actual application rate (0.003-0.004 mg ai/seed). The 

nominal application rate was 0.004 mg ai/seed. Composite seed samples from two trials were 

shipped to SGS NAM GLP Laboratory (Brookings, SD) to confirm treatment rates. Actual 

treatment rates were 85-100% of the target rate. For each trial site, samples of treated seeds were 

planted within 8-138 days of treatment (forage and hay field trials) and 207-347 days of 

treatment (seed field trials). First, second, and third cuttings of alfalfa forage and hay were 

harvested from twelve trials at 45-253, 70-292, and 110-323 days after planting (DAP), 

respectively. Hay samples were not dried prior to collection. Seed samples were collected from 

two trials 185-374 DAP.

 

Samples were analyzed for residues of thiabendazole and benzimidazole using a liquid 

chromatography method with tandem mass spectrometry detection (LC/MS/MS), Method 

GRM040.01A. This method was previously reviewed by the Agency and was found to be 

acceptable for data collection (refer to 47705110.DER1, DP# 363974, 11/30/09, S. Hummel). 

The limit of quantitation (LOQ; determined as the lowest level of method validation, LLMV) 

was 0.01 ppm for each analyte in each alfalfa matrix, for a combined LOQ of 0.02 ppm. The 

method was adequate for data collection based on acceptable concurrent recovery data. The 

fortification levels used in concurrent method recovery were adequate to bracket expected 

residue levels. Concurrent recoveries were corrected for apparent residues in controls; residues 

in the treated samples were not corrected for apparent residues in controls. The method does not 

provide for conversion of residues of benzimidazole to parent equivalents.

 

Samples of alfalfa were stored frozen (frozen at the field sites, <-10 °C at the preparation facility, 

-25 to -10 °C at the analytical laboratory) from collection to analysis for 40-366 days (1.3-12.0

months) for forage, 40-426 days (1.3-14.0 months) for hay, and 40-89 days (1.3-2.9 months) for 
Thiabendazole Summary of Analytical Chemistry and Residue Data DP#: 363974

seed. Samples were analyzed within 1-12 days of extraction. Acceptable storage stability data 

have been submitted demonstrating that residues of thiabendazole and benzimidazole in/on 

representative raw agricultural commodities are stable during frozen storage for up to ~10

months (refer to 48996712.der, interim report). In addition, storage stability data are available 

indicating that residues of both analytes are stable during frozen storage for up to 23 months 

in/on wheat grain and straw (refer to the Residue Chemistry Chapter of the Thiabendazole RED; 

DP# 267871, 9/7/00, T. Morton) and for up to 22 months in/on soybean forage, hay, and seed 

(DP# 280701, 12/9/10, T. Morton). These data are adequate to support the sample storage 

conditions and durations for the submitted study.

In crops grown from seed treated with the 4.1 lb ai/gal FS formulation of thiabendazole at 0.02-

0.05 lb ai/A (22-56 g ai/ha), residues of thiabendazole and benzimidazole were each below the 

LOQ (<0.01 ppm) in/on all samples of alfalfa forage and hay harvested 45-253 (first cutting), 70-

292 (second cutting), and 110-323 DAP (third cutting); combined residues were <0.02 ppm in/on 

all samples. In crops grown from seed treated with the 4.1 lb ai/gal FS formulation of 

thiabendazole at 0.003-0.04 lb ai/A (3.4-45 g ai/ha), residues of thiabendazole and benzimidazole

were each below the LOQ (<0.01 ppm) in/on all samples of alfalfa seed harvested 185-374 DAP; 

combined residues were <0.02 ppm in/on all samples.

Residue decline data were not submitted; however none are required because the pesticide is 

applied before the edible portion of the crop has formed.

Barley. Twelve field trials were conducted in the United States during the 2011 growing season

in the North American Free Trade Agreement (NAFTA) Growing Zones 2 (VA; 1 trial), 5 (MN, 

IA, ND; 3 trials), 7 (ND and NE; 4 trials), 9 (CO; 1 trial), 10 (CA; 1 trial), and 11 (ID and OR; 2 

trials). 

A flowable concentrate (water-dispersible suspension) for seed treatment (FS) formulation 

(Mertect® 340-F) containing 4.1 lb ai/gal thiabendazole was applied to barley seed before 

planting. The seed was treated at the SGS North America, Inc. facility (Brookings, SD) using 

commercial seed treatment procedures. The test substance was applied to the seed using a Hege 

Treater. Application rates for thiabendazole were 0.03-0.20 lb ai/A (34-224 g ai/ha). 

Application rates in lb ai/A were calculated by the petitioner from approximate seeding rates

(550,349-3,085,519 seed/A) and actual seed treatment rates (0.028-0.030 mg ai/seed). The 

nominal seed treatment rate was 0.03 mg ai/seed. Composite seed samples were shipped to SGS 

NAM GLP Laboratory (Brookings, SD) to confirm treatment rates. Actual seed treatment rates 

were 92.1-101% of the target rate. The petitioner noted that the application rate at the CA site 

(0.20 lb ai/A) was high due to the use of a higher than normal seeding rate. For each trial site, 

treated seed was planted within 6-69 days of treatment. Samples of barley hay and grain and 

straw, respectively, were harvested from all trials 52-242 and 83-256 days after planting (DAP). 

Hay samples were not dried prior to collection. 

Samples were analyzed for residues of thiabendazole and benzimidazole using a liquid 

chromatography method with tandem mass spectrometry detection (LC/MS/MS), Method 

GRM040.01A. This method was previously reviewed by the Agency and was found to be 

acceptable for data collection (refer to 47705110.DER1, DP# 363974, 11/30/09, S. Hummel). 

The limit of quantitation (LOQ; determined as the lowest level of method validation, LLMV) 

was 0.01 ppm for each analyte in each barley matrix, for a combined LOQ of 0.02 ppm. The 

method was adequate for data collection based on acceptable concurrent recovery data. The 
Thiabendazole Summary of Analytical Chemistry and Residue Data DP#: 363974

fortification levels used in concurrent method recovery were adequate to bracket expected 

residue levels. Concurrent recoveries were corrected for apparent residues in controls; residues 

in the treated samples were not corrected for apparent residues in controls. The method does not 

provide for conversion of residues of benzimidazole to parent equivalents.

 

Samples of barley were stored frozen (frozen at the field sites, <-10 °C at the preparation facility, 

~-25 °C at the analytical laboratory) from collection to analysis for 69-354 days (2.3-11.6

months) for hay, 87-388 days (2.9-12.8 months) for grain, and 90-392 days (3.0-12.9 months) for 

straw. Samples were generally analyzed within 0-21 days of extraction; one straw sample was 

re-analyzed within 76 days of extraction. Acceptable storage stability data have been submitted 

demonstrating that residues of thiabendazole and benzimidazole in/on representative raw 

agricultural commodities are stable during frozen storage for up to ~10 months (refer to 

48996712.der, interim report). In addition, storage stability data are available indicating that 

residues of both analytes are stable during frozen storage for up to 23 months in/on wheat grain 

and straw (refer to the Residue Chemistry Chapter of the Thiabendazole RED; DP# 267871, 

9/7/00, T. Morton) and for up to 22 months in/on soybean forage, hay, and seed (DP# 280701, 

12/9/10, T. Morton). These data are adequate to support the sample storage conditions and 

durations for the submitted study.

In barley grown from seed treated with the 4.1 lb ai/gal FS formulation of thiabendazole at 0.03-

0.20 lb ai/A (34-224 g ai/ha), residues of benzimidazole were below the LOQ (<0.01 ppm) in/on 

all samples of barley hay and grain and straw harvested 52-242 and 83-256 DAP, respectively. 

Residues (and per trial averages) of thiabendazole and combined residues of thiabendazole and 

benzimidazole, respectively, were: <0.01-0.12 (<0.01-0.12) and <0.02-<0.13 (<0.02-<0.13) ppm 

in/on hay; <0.01-0.031 (<0.01-0.029) and <0.02-<0.041 (<0.02-<0.039) ppm in/on grain; and 

<0.01-0.085 (<0.01-0.082) and <0.02-<0.095 (<0.02-<0.092) ppm in/on straw. There did not 

appear to be a correlation between the length of the treatment-to-planting interval and residue 

levels in this study. Quantifiable residues of thiabendazole were observed in samples grown 

from seed planted 6, 15, 36, and 69 days after treatment. 

NOTE: The barley field trials reflect a shorter interval between treatment and planting than 

some of the other crop field trial studies submitted for thiabendazole.

Residue decline data were not submitted; however none are required because the pesticide is 

applied before the edible portion of the crop has formed.

Wheat. Nineteen field trials were conducted in the United States during the 2011 growing 

season in the North American Free Trade Agreement (NAFTA) Growing Zones 2 (VA; 1 trial), 4 

(MO; 1 trial), 5 (ND, MO, IA, and MN; 5 trials), 6 (TX; 1 trial), 7 (ND and NE; 4 trials), 8 (KS, 

TX, OK; 6 trials), and 11 (OR; 1 trial). HED has determined that two trials (TK0050924-11 and 

TK0050924-12) should be considered replicates; the above field trial distribution incorporates 

this conclusion.

A flowable concentrate (water-dispersible suspension) for seed treatment (FS) formulation 

(Mertect® 340-F) containing 4.1 lb ai/gal thiabendazole was applied to wheat seed before 

planting. The seed was treated at the SGS North America, Inc. facility (Brookings, SD) using 

commercial seed treatment procedures. The test substance was applied to the seed using a Hege 

treater. Application rates for thiabendazole were 0.08-0.14 lb ai/A (90-157 g ai/ha). Application 

rates in lb ai/A were calculated by the petitioner from approximate seeding rate (seed/A) and 
Thiabendazole Summary of Analytical Chemistry and Residue Data DP#: 363974

actual seed treatment rate (mg ai/seed). The nominal seed treatment rate was 0.03 mg ai/seed. 

The seeding rate ranged from ~1,111,360-2,156,713 seed/A. Composite seed samples from eight 

trials were shipped to SGS NAM GLP Laboratory (Brookings, SD) to confirm treatment rates. 

Actual treatment rates were 94.9-107% of the target rate. For each trial site, treated seed was

planted within 4-96 days of treatment. Samples of wheat forage, hay, and grain and straw, 

respectively, were harvested from all trials 39-236, 51-265, and 84-304 days after planting 

(DAP). Hay samples were not dried prior to collection. 

 

Samples were analyzed for residues of thiabendazole and benzimidazole using a liquid 

chromatography method with tandem mass spectrometry detection (LC/MS/MS), Method 

GRM040.01A. This method was previously reviewed by the Agency and was found to be 

acceptable for data collection (refer to 47705110.DER1, DP# 363974, 11/30/09, S. Hummel). 

The limit of quantitation (LOQ; determined as the lowest level of method validation, LLMV) 

was 0.01 ppm for each analyte in each wheat matrix, for a combined LOQ of 0.02 ppm. The 

method was adequate for data collection based on acceptable concurrent recovery data. The 

fortification levels used in concurrent method recovery were adequate to bracket expected 

residue levels. Concurrent recoveries were corrected for apparent residues in controls; residues 

in the treated samples were not corrected for apparent residues in controls. The method does not 

provide for conversion of residues of benzimidazole to parent equivalents.

 

Wheat samples were stored frozen (frozen at the field sites, <-10 °C at the preparation facility, -

25 to -10 °C at the analytical laboratory) from collection to analysis for 61-353 days (2.0-11.6

months) for forage, 81-361 days (2.7-11.9 months) for hay, 59-359 days (1.9-11.8 months) for 

grain, and 58-323 days (1.9-10.6 months) for straw. Samples were analyzed within 0-6 days of 

extraction. Acceptable storage stability data have been submitted demonstrating that residues of 

thiabendazole and benzimidazole in/on representative raw agricultural commodities are stable 

during frozen storage for up to ~10 months (refer to 48996712.der, interim report). In addition, 

storage stability data are available indicating that residues of both analytes are stable during 

frozen storage for up to 23 months in/on wheat grain and straw (refer to the Residue Chemistry

Chapter of the Thiabendazole RED; DP# 267871, 9/7/00, T. Morton) and for up to 22 months 

in/on soybean forage, hay, and seed (DP# 280701, 12/9/10, T. Morton). These data are adequate 

to support the sample storage conditions and durations for the submitted study.

In wheat grown from seed treated with the 4.1 lb ai/gal FS formulation of thiabendazole at 0.08-

0.14 lb ai/A (90-157 g ai/ha), residues of thiabendazole and benzimidazole were each below the 

LOQ (<0.01 ppm) in/on wheat grain harvested 84-304 DAP; combined residues were <0.02 ppm 

in/on all samples of wheat grain. Residues of benzimidazole were also below the LOQ in/on all 

samples of wheat forage, hay, and straw harvested 39-236, 51-265, and 84-304 DAP, 

respectively. Residues (and per trial averages) of thiabendazole and combined residues of 

thiabendazole and benzimidazole, respectively, were: <0.01-0.21 (<0.01-0.20) and <0.02-<0.22 

(<0.02-<0.21) ppm in/on forage; <0.01-0.066 (<0.01-0.062) and <0.02-<0.076 (<0.02-<0.072) 

ppm in/on hay; and <0.01-0.078 (<0.01-0.073) and <0.02-<0.088 (<0.02-<0.083) ppm in/on 

straw, respectively. There did not appear to be a correlation between the length of the treatmentto-planting interval and residue levels in this study. Quantifiable residues of thiabendazole were 

observed in samples grown from seed planted 4 and 96 days after treatment as well as from seed 

planted at treatment-to-planting interval intervals of 14, 20-22, 43, 50-52, and 76 days. 

NOTE: The wheat field trials reflect a shorter interval between treatment and planting than some 

of the other crop field trial studies submitted for thiabendazole.
Thiabendazole Summary of Analytical Chemistry and Residue Data DP#: 363974

Residue decline data were not submitted; however none are required because the pesticide is 

applied before the edible portion of the crop has formed.

Root Vegetables (except sugar beet), subgroup 1B. Field trials were conducted on carrot and 

radish. Both radish roots and tops were analyzed. Thirteen field trials were conducted in the 

United States during the 2011 growing season. Eight carrot root trials were conducted in the 

North American Free Trade Agreement (NAFTA) Growing Zones 3 (FL; 1 trial), 5 (WI; 1 trial),

6 (TX; 1 trial), 10 (CA; 4 trials), and 11 (ID; 1 trial) and 5 radish root and tops trials were 

conducted in NAFTA Growing Zones 1 (NY; 1 trial), 3 (FL; 2 trials), 5 (IL; 1 trial), and 10 (CA; 

1 trial). 

Each trial consisted of one untreated plot and one treated plot. For the treated plot, a flowable 

concentrate (water-dispersible suspension) for seed treatment (FS) formulation (Mertect® 340-F)

containing 4.1 lb ai/gal thiabendazole was applied to carrot and radish seeds before planting. 

The seeds were treated at the Syngenta Seeds facility (Stanton, MN) using commercial seed 

treatment procedures (slurry). The test substance was applied to the seeds using a R6 or R12 

treater. Application rates for thiabendazole were 0.0003-0.007 lb ai/A (0.34-7.8 g ai/ha). 

Application rates in lb ai/A were calculated by the petitioner from the approximate seeding rate 

(69,504-1,238,193 seed/A) and the actual seed treatment rate (0.0019-0.0024 mg ai/seed). The 

nominal seed treatment rate was 0.002 mg ai/seed. Composite control and treated seed samples 

were shipped to SGS NAM GLP Laboratory (Brookings, SD) to confirm treatment rates. Actual 

treatment rates were 96-120% of the target rate. Samples of treated seed were planted within 5-

148 days after treatment. Single control and duplicate treated samples of carrot roots and radish 

roots and tops were collected at normal commercial harvest 79-134 and 26-60 days after planting 

(DAP), respectively.

Carrot root and radish root and top samples were analyzed for residues of thiabendazole and its 

metabolite using high performance liquid chromatography with tandem mass spectrometry

detection (LC/MS/MS); Syngenta Method GRM040.01A. This method was previously reviewed 

by the Agency and was found to be acceptable for data collection (refer to 47705110.DER1, DP# 

363974, 11/30/09, S. Hummel). The limit of quantitation (LOQ; determined as the lowest limit 

of method validation, LLMV) was 0.01 ppm for each analyte in each matrix, for a combined 

LOQ of 0.02 ppm. The method was adequate for data collection based on acceptable concurrent 

recovery data. The fortification levels used in concurrent method recovery were adequate to 

bracket expected residue levels. Concurrent recoveries were corrected for apparent residues in 

controls; residues in the treated samples were not corrected for apparent residues in controls. 

The method does not provide for conversion of residues of benzimidazole to parent equivalents.

Samples were stored frozen (frozen at the field sites, <-10 °C at the preparation facility, and

< -20 °C at the analytical laboratory) from collection to analysis for 90-257 days (3.0-8.5

months) for carrot roots and 157-290 days (5.2-9.5 months) for radish roots and tops. All 

samples were analyzed within 2-4 days of extraction. Acceptable storage stability data have 

been submitted demonstrating that residues of thiabendazole and benzimidazole in/on 

representative raw agricultural commodities are stable during frozen storage for up to ~10

months (refer to 48996712.der, interim report). These data are adequate to support the sample 

storage conditions and durations for the submitted study. 
Thiabendazole Summary of Analytical Chemistry and Residue Data DP#: 363974

In crops grown from seed treated with the 4.1 lb ai/gal FS formulation of thiabendazole at 

0.0003-0.007 lb ai/A (0.34-7.8 g ai/ha), residues of thiabendazole and benzimidazole were each 

below the LOQ (<0.01) ppm in/on all samples of carrot roots and radish roots and tops harvested 

at 79-134 and 26-60 DAP, respectively; combined residues were <0.02 ppm in/on all samples.

Residue decline data were not submitted; however none are required because the pesticide is 

applied before the edible portion of the crop has formed.

Brassica Head and Stem Vegetables, subgroup 5A. Twelve field trials were conducted in the 

United States during the 2010 growing season. Six cabbage trials were conducted in the North 

American Free Trade Agreement (NAFTA) Growing Zones 1 (NY; 1 trial), 2 (NC; 1 trial), 3 

(FL; 1 trial), 5 (ND; 1 trial), 6 (TX; 1 trial), and 10 (CA; 1 trial), and six broccoli field trials were 

conducted in NAFTA Growing Zones 6 (TX; 1 trial), 10 (CA; 4 trials), and 12 (OR; 1 trial).

A flowable concentrate (water-dispersible suspension) for seed treatment (FS) formulation 

(Mertect® 340-F) containing 4.1 lb ai/gal thiabendazole was applied to cabbage and broccoli 

seed before planting. The seed was treated at the Syngenta Seeds facility (Stanton, MN) using 

commercial seed treatment procedures. The test substance was applied to the seed using a Roto 

Stat R-12. Application rates for thiabendazole were 0.00019-0.0008 lb ai/A (0.21-0.90 g ai/ha). 

Application rates in lb ai/A were calculated by the petitioner from approximate seeding rate 

(seed/A) and actual seed treatment rate (mg ai/seed). The nominal seed treatment rate was 0.002 

mg ai/seed. The seeding rate ranged from ~11,600 seed/A to 217,800 seed/A. In two field trials 

(NY and ND), the seed verification samples were lost in transit, and the actual seed treatment 

rates were not reported. For these trials the petitioner reported the nominal application rates 

(0.004-0.008 lb ai/A; 0.11-0.90 g ai/ha). Composite seed samples were shipped to SGS NAM 

GLP Laboratory (Brookings, SD) to confirm treatment rates. Actual treatment rates were 70-

130% of the target rate. For each trial site, treated seed was planted within 1-163 days of 

treatment. Samples of cabbage heads with wrapper leaves and broccoli head and stem were 

harvested from all trials 73-190 days after planting (DAP).

Samples were analyzed for residues of thiabendazole and benzimidazole using a liquid 

chromatography method with tandem mass spectrometry detection (LC/MS/MS), Method 

GRM040.01A. This method was previously reviewed by the Agency and was found to be 

acceptable for data collection (refer to 47705110.DER1, DP# 363974, 11/30/09, S. Hummel). 

The limit of quantitation (LOQ; determined as the lowest level of method validation, LLMV) 

was 0.01 ppm for each analyte, for a combined LOQ of 0.02 ppm. The method was adequate for 

data collection based on acceptable concurrent recovery data. The fortification levels used in 

concurrent method recovery were adequate to bracket expected residue levels. Concurrent 

recoveries were corrected for apparent residues in controls; residues in the treated samples were 

not corrected for apparent residues in controls. The method does not provide for conversion of 

residues of benzimidazole to parent equivalents.

 

Samples were stored frozen (frozen at the field sites, <-10 °C at the preparation facility, ~ -20 °C 

at the analytical laboratory) from collection to analysis for 124-300 days (4.1-9.9 months) for 

cabbage and 93-308 days (3.1-10.1 months) for broccoli. Samples were analyzed within 1-4

days of extraction. Acceptable storage stability data have been submitted demonstrating that 

residues of thiabendazole and benzimidazole in/on representative raw agricultural commodities 

are stable during frozen storage for up to ~10 months (refer to 48996712.der, interim report). In 

addition, storage stability data are available indicating that residues of both analytes are stable 

during frozen storage for up to 28 months in/on whole potato and wet peel (refer to the Residue 
Thiabendazole Summary of Analytical Chemistry and Residue Data DP#: 363974

Chemistry Chapter of the Thiabendazole RED; DP# 267871, 9/7/00, T. Morton) and for up to 22 

months in/on soybean forage, hay, and seed (DP# 280701, 12/9/10, T. Morton). These data are 

adequate to support the sample storage conditions and durations for the submitted study.

In cabbage and broccoli grown from seed treated with the 4.1 lb ai/gal FS formulation of 

thiabendazole at 0.00019-0.0008 lb ai/A (0.21-0.90 g ai/ha), residues of thiabendazole and 

benzimidazole were each below the LOQ (<0.01 ppm) in/on all samples harvested 73-190 DAP; 

combined residues were <0.02 ppm in/on all samples.

Residue decline data were not submitted; however none are required because the pesticide is 

applied before the edible portion of the crop has formed.

Spinach. Eight field trials were conducted in the United States during the 2010-2011 growing 

seasons in the North American Free Trade Agreement (NAFTA) Growing Zones 1 (NJ; 1 trial), 

2 (GA; 2 trials), 6 (TX; 2 trials), 8 (CO; 1 trial), and 10 (CA; 2 trials).

A flowable concentrate (water-dispersible suspension) for seed treatment (FS) formulation 

(Mertect® 340-F) containing 4.1 lb ai/gal thiabendazole was applied to spinach seeds before 

planting. The seeds were treated at the Syngenta Seeds facility (Stanton, MN) using commercial 

seed treatment procedures. The test substance was applied to the seeds using a Roto Stat R-12. 

Application rates for thiabendazole were 0.001-0.014 lb ai/A (0.8-15.7 g ai/ha). Application 

rates in lb ai/A were calculated by the petitioner from the approximate seeding rate (52,272-

1,045,440 seed/A) and actual seed treatment rates (0.006-0.007 mg ai/seed). The nominal seed 

treatment rate was 0.006 mg ai/seed. Composite seed samples were shipped to SGS NAM GLP 

Laboratory (Brookings, SD) to confirm treatment rates. Actual treatment rates were 100-117% 

of the target rate. For each trial site, samples of treated seeds were planted within 48-237 days of 

treatment. Samples of spinach leaves were harvested from all trials at 47- to 89-days after 

planting (DAP). Additionally, samples of immature (baby) spinach leaves were harvested from 

two sites at 43-54 DAP.

 

Samples were analyzed for residues of thiabendazole and benzimidazole using a liquid 

chromatography method with tandem mass spectrometry detection (LC/MS/MS), Method 

GRM040.01A. This method was previously reviewed by the Agency and was found to be 

acceptable for data collection (refer to 47705110.DER1, DP# 363974, 11/30/09, S. Hummel). 

The limit of quantitation (LOQ; determined as the lowest level of method validation, LLMV) 

was 0.01 ppm for each analyte, for a combined LOQ of 0.02 ppm. The method was adequate for 

data collection based on acceptable concurrent recovery data. The fortification levels used in 

concurrent method recovery were adequate to bracket expected residue levels. Concurrent 

recoveries were corrected for apparent residues in controls; residues in the treated samples were 

not corrected for apparent residues in controls. The method does not provide for conversion of 

residues of benzimidazole to parent equivalents.

 

Samples were stored frozen (frozen at the field sites, <-10 °C at the preparation facility, ~ -20 °C 

at the analytical laboratory) from collection to analysis for 43-248 days (1.4-8.2 months). All 

samples were analyzed within 2-3 days of extraction. Acceptable storage stability data have 

been submitted demonstrating that residues of thiabendazole and benzimidazole in/on 

representative raw agricultural commodities are stable during frozen storage for up ~10 months 

(refer to 48996712.der, interim report). These data are considered adequate to support the 

sample storage durations for the submitted study. We note that the study indicated that residues 
Thiabendazole Summary of Analytical Chemistry and Residue Data DP#: 363974

of benzimidazole may decline slightly in/on spinach during frozen storage (corrected recovery of 

~66% at 9 months). HED does not believe this potential loss on storage would have any

appreciable effect on the residue results. 

In crops grown from seed treated with the 4.1 lb ai/gal FS formulation of thiabendazole at 0.001-

0.014 lb ai/A (1.3-15.7 g ai/ha), residues of thiabendazole and benzimidazole were each below 

the LOQ (<0.01 ppm) in/on all samples of mature and immature spinach leaves harvested 43-89 

DAP; combined residues were <0.02 ppm in/on all samples.

Residue decline data were not submitted; however none are required because the pesticide is 

applied before the edible portion of the crop has formed.

Soybeans. Additional data were required for thiabendazole in the RED. Additionally, Syngenta 

Crop Protection, LLC has requested an amendment to the registration for Mertect® 340-F, 

containing 4.1 lb ai/gal thiabendazole to increase the application rate for soybean seed treatment. 

Syngenta Crop Protection, LLC has submitted field trial data for thiabendazole on soybean. 

Nineteen field trials were conducted in the United States during the 2010 growing season in the 

North American Free Trade Agreement (NAFTA) Growing Zones 2 (SC and NC; 2 trials), 4 

(LA; 3 trials), and 5 (ND, SD, IA, OH, MO, WI, NE, and MN; 14 trials). HED has determined 

that two trials (C01-0599 and C01-0607) should be considered replicates; the above field trial 

distribution incorporates this conclusion.

A flowable concentrate (water-dispersible suspension) for seed treatment (FS) formulation 

(Mertect® 340-F) containing 4.1 lb ai/gal thiabendazole was applied to wheat seeds before 

planting. The seeds were treated at the SGS North America, Inc. facility (Brookings, SD) using 

commercial seed treatment procedures. The test substance was applied to the seeds using a Hege 

treater. Application rates for thiabendazole were 0.012-0.024 lb ai/A (13.5-26.9 g ai/ha). 

Application rates in lb ai/A were calculated by the petitioner from approximate seeding rates

(78,400-169,061 seed/A) and actual seed treatment rates (0.052-0.069 mg ai/seed), equivalent to 

2x the requested amended applicatioin rate. The nominal seed treatment rate, calculated by the 

study reviewer, was 0.06 mg ai/seed, based on a treatment rate of 40 g ai/100 kg seed and 3,000 

seeds/lb. Composite seed samples were shipped to SGS NAM GLP Laboratory (Brookings, SD) 

to confirm treatment rates. Actual treatment rates were 91-106% of the target rate. For each trial 

site, samples of treated seeds were planted within 3-30 days of treatment. Samples of soybean 

forage and hay were harvested from all trials 46-94 days after planting (DAP); seed was 

harvested 109-153 DAP. Hay samples were dried to approximately 10-20% moisture content; 

drying intervals were not reported.

Samples were analyzed for residues of thiabendazole and benzimidazole using a liquid 

chromatography method with tandem mass spectrometry detection (LC/MS/MS), Method 

GRM040.01A. This method was previously reviewed by the Agency and was found to be 

acceptable for data collection (refer to 47705110.DER1, DP# 363974, 11/30/09, S. Hummel). 

The limit of quantitation (LOQ; determined as the lowest level of method validation, LLMV) 

was 0.01 ppm for each analyte in each soybean matrix, for a combined LOQ of 0.02 ppm. The 

method was adequate for data collection based on acceptable concurrent recovery data. The 

fortification levels used in concurrent method recovery were adequate to bracket expected 

residue levels. Concurrent recoveries were corrected for apparent residues in controls; residues 

in the treated samples were not corrected for apparent residues in controls. The method does not 

provide for conversion of residues of benzimidazole to parent equivalents.
Thiabendazole Summary of Analytical Chemistry and Residue Data DP#: 363974

 

Samples of soybean were stored frozen (frozen at the field sites, <-10 °C at the preparation 

facility, ~ -20 °C at the analytical laboratory) from collection to analysis for 221-273 days (7.3-

9.0 months) for forage, 222-274 days (7.3-9.0 months) for hay, and 181-224 days (6.0-7.4 

months) for seed. Samples were analyzed within 1-7 days of extraction. Acceptable storage 

stability data are available indicating that residues of both analytes are stable during frozen 

storage for up to 22 months in/on soybean forage, hay, and seed (DP# 280701, 12/9/10, T. 

Morton). These data are adequate to support the sample storage conditions and durations for the 

submitted study.

In crops grown from seed treated with the 4.1 lb ai/gal FS formulation of thiabendazole at 0.012-

0.024 lb ai/A (13.5-26.9 g ai/ha), residues of thiabendazole and benzimidazole were each below 

the LOQ (<0.01 ppm) in/on all samples of soybean forage and hay harvested 46-94 DAP and 

soybean seed harvested 109-153 DAP; combined residues were <0.02 ppm in/on all samples.

Residue decline data were not submitted; however none are required because the pesticide is 

applied before the edible portion of the crop has formed.

Dry Bulb Onions. Eight field trials were conducted in the United States during the 2010-2011 

growing seasons in the North American Free Trade Agreement (NAFTA) Growing Zones 1

(NY; 1 trial), 5 (IA; 1 trial), 6 (TX; 1 trial), 8 (TX; 1 trial), 10 (CA; 2 trials), 11 (ID; 1 trial), and 

12 (OR; 1 trial). 

A flowable concentrate (water-dispersible suspension) for seed treatment (FS) formulation 

(Mertect® 340-F) containing 4.1 lb ai/gal thiabendazole was applied to dry bulb onion seeds

before planting. The seeds were treated at the Syngenta Seeds facility (Stanton, MN) using 

commercial seed treatment procedures. The test substance was applied to the seeds using a Roto 

Stat R-12. Application rates for thiabendazole were 0.001-0.003 lb ai/A (1.1-3.4 g ai/ha). 

Application rates in lb ai/A were calculated by the petitioner from the approximate seeding rate 

(52,800-620,000 seed/A) and actual seed treatment rates (0.002-0.005 mg ai/seed). The nominal 

seed treatment rate was 0.002 mg ai/seed. Composite seed samples were shipped to SGS NAM 

GLP Laboratory (Brookings, SD) to confirm treatment rates. Actual treatment rates were 105-

250% of the target rate. For each trial site, samples of treated seeds were planted within 8-323 

days of treatment. Samples of dry bulb onions were harvested from all trials 113-252 days after 

planting (DAP).

 

Samples were analyzed for residues of thiabendazole and benzimidazole using a liquid 

chromatography method with tandem mass spectrometry detection (LC/MS/MS), Method 

GRM040.01A. This method was previously reviewed by the Agency and was found to be 

acceptable for data collection (refer to 47705110.DER1, DP# 363974, 11/30/09, S. Hummel). 

The limit of quantitation (LOQ; determined as the lowest level of method validation, LLMV) 

was 0.01 ppm for each analyte, for a combined LOQ of 0.02 ppm. The method was adequate for 

data collection based on acceptable concurrent recovery data. The fortification levels used in 

concurrent method recovery were adequate to bracket expected residue levels. Concurrent 

recoveries were corrected for apparent residues in controls; residues in the treated samples were 

not corrected for apparent residues in controls. The method does not provide for conversion of 

residues of benzimidazole to parent equivalents.

 

Samples were stored frozen (frozen at the field sites, <-10 °C at the preparation facility, ~ -20 °C 
Thiabendazole Summary of Analytical Chemistry and Residue Data DP#: 363974

at the analytical laboratory) from collection to analysis for 73-140 days (2.4-4.6 months). All 

samples were analyzed within 1-2 days of extraction. Acceptable storage stability data have 

been submitted demonstrating that residues of thiabendazole and benzimidazole in/on 

representative raw agricultural commodities are stable during frozen storage for up to ~10

months (refer to 48996712.der, interim report). These data are considered adequate to support 

the sample storage durations for the submitted study. 

In crops grown from seed treated with the 4.1 lb ai/gal FS formulation of thiabendazole at 0.001-

0.003 lb ai/A (1.1-3.4 g ai/ha), residues of thiabendazole and benzimidazole were each below the 

LOQ (<0.01 ppm) in/on all samples of dry bulb onion harvested 113-252 DAP; combined 

residues were <0.02 ppm in/on all samples.

Residue decline data were not submitted; however none are required because the pesticide is 

applied before the edible portion of the crop has formed.

TABLE 5. Summary of Residue Data with Thiabendazole.

Commodity Analyte Total Rate

lb ai/A

(g ai/ha)

DAP

(days)

Residue Levels (ppm)1

n Sample 

Min.

Sample 

Max.

LAFT

2 HAFT2 Median Mean Std. 

Dev.

Alfalfa Forage -

1

st Cutting

Thiabendazole 0.02-0.05

(22-56)

45-253 12 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

Benzimidazole 12 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

Combined 

Residues3

12 <0.02 <0.02 <0.02 <0.02 0.02 0.02 N/A

Alfalfa Forage –

2

nd Cutting

Thiabendazole 0.02-0.05

(22-56)

70-292 12 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

Benzimidazole 12 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

Combined 

Residues3

12 <0.02 <0.02 <0.02 <0.02 0.02 0.02 N/A

Alfalfa Forage –

3

rd Cutting

Thiabendazole 0.02-0.05

(22-56)

110-323 10 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

Benzimidazole 10 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

Combined 

Residues3

10 <0.02 <0.02 <0.02 <0.02 0.02 0.02 N/A

Alfalfa Hay – 1

st

Cutting

Thiabendazole 0.02-0.05

(22-56)

42-253 12 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

Benzimidazole 12 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

Combined 

Residues3

12 <0.02 <0.02 <0.02 <0.02 0.02 0.02 N/A

Alfalfa Hay – 2

nd

Cutting

Thiabendazole 0.02-0.05

(22-56)

70-292 12 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

Benzimidazole 12 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

Combined 

Residues3

12 <0.02 <0.02 <0.02 <0.02 0.02 0.02 N/A

Alfalfa Hay – 3

rd

Cutting

Thiabendazole 0.02-0.05

(22-56)

110-323 10 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

Benzimidazole 10 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

Combined 

Residues3

10 <0.02 <0.02 <0.02 <0.02 0.02 0.02 N/A

Alfalfa Seed Thiabendazole 0.003-0.04 

(3.4-45)

185-374 2 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

Benzimidazole 2 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

Combined 

Residues3

2 <0.02 <0.02 <0.02 <0.02 0.02 0.02 N/A

Barley Hay Thiabendazole 0.03-0.20 52-242 12 <0.01 0.12 <0.01 0.12 0.010 0.023 0.032

Benzimidazole 12 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A
Thiabendazole Summary of Analytical Chemistry and Residue Data DP#: 363974

TABLE 5. Summary of Residue Data with Thiabendazole.

Commodity Analyte Total Rate

lb ai/A

(g ai/ha)

DAP

(days)

Residue Levels (ppm)1

n Sample 

Min.

Sample 

Max.

LAFT

2 HAFT2 Median Mean Std. 

Dev.

Combined 

Residues3

12 <0.02 <0.13 <0.02 <0.13 0.020 0.033 0.032

Barley Grain Thiabendazole 0.03-0.20 83-256 12 <0.01 0.031 <0.01 0.029 0.010 0.012 0.005

Benzimidazole 12 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

Combined 

Residues3

12 <0.02 <0.041 <0.02 <0.039 0.020 0.022 0.005

Barley Straw Thiabendazole 0.03-0.20 83-256 12 <0.01 0.085 <0.01 0.082 0.010 0.024 0.024

Benzimidazole 12 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

Combined 

Residues3

12 <0.02 <0.095 <0.02 <0.092 0.020 0.034 0.024

Wheat Forage Thiabendazole 0.08-0.14

(90-157)

39-236 19 <0.01 0.21 <0.01 0.20 0.010 0.025 0.044

Benzimidazole 19 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

Combined 

Residues3

19 <0.02 <0.22 <0.02 <0.21 0.020 0.035 0.044

Wheat Hay Thiabendazole 0.08-0.14

(90-157)

51-265 19 <0.01 0.066 <0.01 0.062 0.010 0.015 0.015

Benzimidazole 19 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

Combined 

Residues3

19 <0.02 <0.076 <0.02 <0.072 0.020 0.025 0.015

Wheat Grain Thiabendazole 0.08-0.14

(90-157)

84-304 19 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

Benzimidazole 19 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

Combined 

Residues3

19 <0.02 <0.02 <0.02 <0.02 0.02 0.02 N/A

Wheat Straw Thiabendazole 0.08-0.14

(90-157)

84-304 19 <0.01 0.078 <0.01 0.073 0.010 0.014 0.015

Benzimidazole 19 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

Combined 

Residues3

19 <0.02 <0.088 <0.02 <0.083 0.020 0.024 0.015
Thiabendazole Summary of Analytical Chemistry and Residue Data DP#: 363974

TABLE 5. Summary of Residue Data with Thiabendazole.

Commodity Analyte Total Rate

lb ai/A

(g ai/ha)

DAP

(days)

Residue Levels (ppm)1

n Sample 

Min.

Sample 

Max.

LAFT

2 HAFT2 Median Mean Std. 

Dev.

Carrot roots Thiabendazole 0.0003-0.007

(0.34-7.8)

79-134 8 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

Benzimidazole 8 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

Combined 

Residues3

8 <0.02 <0.02 <0.02 <0.02 0.02 0.02 N/A

Radish roots Thiabendazole 0.002-0.004

(2.2-4.5)

26-60 5 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

Benzimidazole 5 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

Combined 

Residues3

5 <0.02 <0.02 <0.02 <0.02 0.02 0.02 N/A

Radish tops Thiabendazole 0.002-0.004

(2.2-4.5)

26-60 5 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

Benzimidazole 5 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

Combined 

Residues3

5 <0.02 <0.02 <0.02 <0.02 0.02 0.02 N/A

Cantaloupe Thiabendazole 0.002-0.008

(2.2-9.0)

62-119 6 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

Benzimidazole 6 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

Combined 

Residues3

6 <0.02 <0.02 <0.02 <0.02 0.02 0.02 N/A

Cucumber Thiabendazole 0.005-0.012

(5.6-13.4)

49-81 6 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

Benzimidazole 6 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

Combined 

Residues3

6 <0.02 <0.02 <0.02 <0.02 0.02 0.02 N/A
Thiabendazole Summary of Analytical Chemistry and Residue Data DP#: 363974

TABLE 5. Summary of Residue Data with Thiabendazole.

Commodity Analyte Total Rate

lb ai/A

(g ai/ha)

DAP

(days)

Residue Levels (ppm)1

n Sample 

Min.

Sample 

Max.

LAFT

2 HAFT2 Median Mean Std. 

Dev.

Summer

Squash

Thiabendazole 0.001-0.007

(1.1-7.8)

33-62 5 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

Benzimidazole 5 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

Combined 

Residues3

5 <0.02 <0.02 <0.02 <0.02 0.02 0.02 N/A

Cabbage heads 

w/wrapper leaves

Thiabendazole 0.00025-

0.00077

(0.28-0.86)

4

84-190 6 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

Benzimidazole 6 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

Combined 

Residues3

6 <0.02 <0.02 <0.02 <0.02 0.02 0.02 N/A

Broccoli head 

and stem

Thiabendazole 0.00019-0.0008 

(0.21-0.90)

73-137 6 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

Benzimidazole 6 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

Combined 

Residues3

6 <0.02 <0.02 <0.02 <0.02 0.02 0.02 N/A

Spinach Leaves Thiabendazole 0.001-0.014

(0.8-15.7)

47-89 8 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

Benzimidazole 8 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

Combined 

Residues3

8 <0.02 <0.02 <0.02 <0.02 0.02 0.02 N/A

Immature (Baby) 

Spinach Leaves

Thiabendazole 0.001-0.014

(0.8-15.7)

43-54 2 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

Benzimidazole 2 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

Combined 

Residues3

2 <0.02 <0.02 <0.02 <0.02 0.02 0.02 N/A

Soybean Forage Thiabendazole 0.012-0.024

(13.5-26.9)

46-94 19 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

Benzimidazole 19 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

Combined 

Residues3

19 <0.02 <0.02 <0.02 <0.02 0.02 0.02 N/A

Soybean Hay Thiabendazole 0.012-0.024

(13.5-26.9)

46-94 19 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

Benzimidazole 19 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

Combined 

Residues3

19 <0.02 <0.02 <0.02 <0.02 0.02 0.02 N/A

Soybean Seed Thiabendazole 0.012-0.024

(13.5-26.9)

109-153 19 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

Benzimidazole 19 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

Combined 

Residues3

19 <0.02 <0.02 <0.02 <0.02 0.02 0.02 N/A

Dry Bulb Onion Thiabendazole 0.001-0.003

(1.1-3.4)

113-252 8 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

Benzimidazole 8 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

Combined 

Residues3

8 <0.02 <0.02 <0.02 <0.02 0.02 0.02 N/A

1

 Except for sample min/max, values reflect per trial averages; n = no. of field trials. N/A = Not Applicable

2

 LAFT = lowest average field trial; HAFT = highest average field trial.

3 Combined residues of thiabendazole and benzimidazole. Residues of benzimidazole were not converted to parent equivalents.

Conclusions. The submitted field trial data are adequate to support the tolerance request and 
Thiabendazole Summary of Analytical Chemistry and Residue Data DP#: 363974

amended registration request. Acceptable methods were used for residue quantitation, and the 

study is supported by adequate storage stability data.

860.1520 Processed Food and Feed

48996703 Wheat Processing

48996709 Soybean processing

Wheat Processing. Syngenta Crop Potection, LLC has submitted a processing study for 

thiabendazole and benzimidazole in/on wheat grain. In one trial conducted in Campbell, MN, 

and one trial conducted in Hinton, OK, a flowable concentrate (water-dispersible suspension) for 

seed treatment (FS) formulation (Mertect® 340-F) containing 4.1 lb /gal thiabendazole was 

applied to wheat seeds before planting. The seeds were treated at SGS North America, Inc. 

(Brookings, SD) using commercial seed treatment procedures. A Hege seed treater was used to 

apply an exaggerated rate (5x field rate) of 0.47-0.71 lb ai/A (529-791 g ai/ha). Application rates 

in lb ai/A were calculated by the petitioner from approximate seeding rate (1,530,350 –

2,065,631 seed/A) and actual seed treatment rate (0.14-0.16 mg ai/seed); 5x the nominal seed 

treatment rate of 0.03 mg ai/seed.. The nominal application rate was 0.15 mg ai/seed. 

Composite seed samples were shipped to SGS NAM GLP Laboratory (Brookings, SD) to 

confirm treatment rates. Actual treatment rates for wheat seeds associated with the processing 

study (exaggerated application rate) were 95.5-103% of the target rate. Treated wheat seeds 

were planted with 8-43 days of treatment. At the end of the growing season, wheat grain was 

harvested at crop maturity 98-216 days after planting (DAP) and processed into bran, flour, 

middlings, shorts and germ using simulated commercial procedures. Processing was conducted 

by GLP Technologies (Navasota, TX). Adequate descriptions of the processing procedures were 

provided, including material balance summaries.

Samples were analyzed for residues of thiabendazole and metabolite benzimidazole using a 

liquid chromatography method with tandem mass spectrometric detection (LC/MS/MS), Method 

GRM040.01A. This method was previously reviewed by the Agency and was found to be 

acceptable for data collection (refer to 47705110.DER1, DP# 363974, 11/30/09, S. Hummel). 

The limit of quantitation (LOQ; determined as the lowest level of method validation, LLMV)

was 0.01 ppm for each analyte, for an LOQ of 0.02 ppm for combined residues. The method was 

adequate for data collection based on acceptable concurrent recovery data. The fortification 

levels used in concurrent method recovery were adequate to bracket expected residue levels. 

Concurrent recoveries were corrected for apparent residues in controls; residues in the treated 

samples were not corrected for apparent residues in controls. The method does not provide for 

conversion of residues of benzimidazole to parent equivalents. 

Samples were stored under ambient conditions (field sites) and frozen (generally <-10 °C at the 

processing facility, preparation facility, and analytical laboratory) from harvest/processing to 

analysis. Processing took place within 71-378 days of harvest. Sample analyses were completed 

within 129-414 days (4.2-13.6 months) of harvest for grain (RAC) and within 39-96 days (1.3-

3.2 months) of processing for the processed commodities. All samples were analyzed within 2-5 

days of extraction. Acceptable storage stability data have been submitted demonstrating that 

residues of thiabendazole and benzimidazole in/on representative raw agricultural commodities 

are stable during frozen storage for up to ~10 months (refer to 48996712.der, interim results). In 

addition, storage stability data are available indicating that residues of both analytes are stable 

during frozen storage for up to 23 months in/on wheat grain and for up to 18 months in wheat 
Thiabendazole Summary of Analytical Chemistry and Residue Data DP#: 363974

bran, and flour (refer to DP# 267871, 9/7/00, T. Morton). These data are adequate to support the 

sample storage conditions and durations for the submitted study.

In crops grown from seed treated with the 4.1 lb ai/gal FS formulation of thiabendazole at 0.47-

0.71 lb ai/A (529-791 g ai/ha), residues of thiabendazole and benzimidazole were below the 

LOQ (<0.01 ppm for each analyte, <0.02 ppm for combined residues) in/on all samples of wheat 

grain (RAC) and processed commodities (bran, flour, middlings, shorts, and germ); therefore, 

processing factors were not calculated. 

The maximum theoretical concentration factor for wheat is 8x for wheat (OCSPP 860.1520, 

Table 1). Theoretical concentration factors are 7.7x for bran, 1.4x for flour, and 8.3x for shorts 

(based on separation into components; OCSPP 860.1520, Table 3).

Soybean Processing. Syngenta Crop Potection, LLC has submitted a processing study for 

thiabendazole and benzimidazole in/on soybean seeds. In one trial conducted in Richland, IA, 

and one trial conducted in Marysville, OH, a flowable concentrate (water-dispersible suspension) 

for seed treatment (FS) formulation (Mertect® 340-F) containing 4.1 lb thiabendazole/gal was 

applied to soybean seeds before planting. The seeds were treated at SGS North America, Inc. 

(Brookings, SD) using commercial seed treatment procedures. A Hege seed treater was used to 

apply the test substance at an exaggerated rate (5x field rate of the concurrent field trial study) of 

0.09 lb ai/A (100.9 g ai/ha). Application rates in lb ai/A were calculated by the petitioner from

the approximate seeding rates (138,000 - 148,459 seed/A) and the actual seed treatment rate 

(0.29 mg ai/seed). The nominal seed treatment rate was 0.31 mg ai/seed, based on a treatment 

rate of 200 g ai/100 kg seed and 3,000 seeds/lb. Composite seed samples were shipped to SGS 

NAM GLP Laboratory (Brookings, SD) to confirm treatment rates. The actual seed treatment 

rate was 104% of the target rate. Treated soybean seeds were planted with 8-20 days of 

treatment. At the end of the growing season, soybean seeds were harvested at crop maturity 126-

130 days after planting (DAP) and processed into meal, hulls, refined oil, flour, milk, tofu, soy

sauce, miso, pollard and crude oil using simulated commercial procedures. Processing was 

conducted by GLP Technologies (Navasota, TX). Adequate descriptions of the processing 

procedures were provided, including material balance summaries.

Samples were analyzed for residues of thiabendazole and metabolite benzimidazole using a 

liquid chromatography method with tandem mass spectrometric detection (LC/MS/MS), Method 

GRM040.01A. This method was previously reviewed by the Agency and was found to be 

acceptable for data collection (refer to 47705110.DER1, DP# 363974, 11/30/09, S. Hummel). 

The limit of quantitation (LOQ; determined as the lowest level of method validation, LLMV)

was 0.01 ppm for each analyte, for an LOQ of 0.02 ppm for combined residues. The method was 

adequate for data collection based on acceptable concurrent recovery data. The fortification 

levels used in concurrent method recovery were adequate to bracket expected residue levels. 

Concurrent recoveries were corrected for apparent residues in controls; residues in the treated 

samples were not corrected for apparent residues in controls. The method does not provide for 

conversion of residues of benzimidazole to parent equivalents. 

Samples of soybean seeds were shipped directly from each field site to the processing facility

under ambient or frozen conditions within 0-5 days of harvest. Samples were stored frozen at 

the processing and preparation facilities (<-10 °C) and at the analytical laboratory (~-20 °C). 

Processing was completed within 14-41 days of harvest for all commodities, except for soy sauce 

and miso which was completed within 248-264 days of harvest due to a ~6 month processing 
Thiabendazole Summary of Analytical Chemistry and Residue Data DP#: 363974

time. Sample analyses were completed within 109-125 days (3.6-4.1 months) of harvest for seed 

(RAC) and within 33-94 days (1.1-3.1 months) of processing for the processed commodities. All 

samples were analyzed within 1-7 days of extraction. Adequate storage stability data are 

available indicating that residues of both analytes are stable during frozen storage for up to 22 

months in/on soybean forage, hay, and seed (DP# 280701, 12/9/10, T. Morton). In addition, 

storage stability data are available indicating that residues of both analytes are stable during 

frozen storage for up to 12 months in soybean oil (refer to 48996712.der, interim results) and for 

up to 18 months in wheat bran and flour (refer to the Residue Chemistry Chapter of the 

Thiabendazole RED; DP# 267871, 9/7/00, T. Morton). These data are adequate to support the 

sample storage conditions and durations for the submitted study.

In crops grown from seed treated with the 4.1 lb ai/gal FS formulation of thiabendazole at 0.09 lb 

ai/A (100.9 g ai/ha), residues of thiabendazole and benzimidazole were below the LOQ (<0.01 

ppm for each analyte, <0.02 ppm for combined residues) in/on all samples of soybean seed 

(RAC) and processed commodities (meal, hulls, refined oil, flour, milk, tofu, soy sauce, miso, 

pollard and crude oil); therefore, processing factors were not calculated. 

The maximum theoretical concentration factor for soybean is 12x (OCSPP 860.1520, Table 1). 

Theoretical concentration factors are 11.3x for hulls, 2.2x for meal and 12.0x for oil (based on 

separation into components; OCSPP 860.1520, Table 3).

TABLE 6. Residue Data from Wheat Processing Studies with Thiabendazole and Benzimidazole.

RAC Processed 

Commodity

Total 

Rate1

lb ai/A

(g ai/ha)

DAP2 Residues (ppm), [Average]3Processing Factor4

Thiabendazole Benzimidazole Combined5 ThiabendazoleBenzimidazoleCombined5

Campbell, MN; 2011 (TK0050924-19)

Wheat Preprocessed 

Grain

(RAC)

0.47 

(529)

98 <0.01, <0.01, 

<0.01 [<0.01]

<0.01, <0.01, 

<0.01 [<0.01]

<0.02, <0.02, 

<0.02 [<0.02]

-- -- --

Bran <0.01, <0.01 

[<0.01]

<0.01, <0.01 

[<0.01]

<0.02, <0.02 

[<0.02]

NC NC NC

Flour <0.01, <0.01 

[<0.01]

<0.01, <0.01 

[<0.01]

<0.02, <0.02 

[<0.02]

NC NC NC

Middlings <0.01, <0.01 

[<0.01]

<0.01, <0.01 

[<0.01]

<0.02, <0.02 

[<0.02]

NC NC NC

Shorts <0.01, <0.01 

[<0.01]

<0.01, <0.01 

[<0.01]

<0.02, <0.02 

[<0.02]

NC NC NC

Germ <0.01, <0.01 

[<0.01]

<0.01, <0.01 

[<0.01]

<0.02, <0.02 

[<0.02]

NC NC NC

Hinton, OK; 2011 (TK0050924-20)

Wheat Preprocessed 

Grain

(RAC)

0.71 

(791)

216 <0.01, <0.01, 

<0.01 [<0.01]

<0.01, <0.01, 

<0.01 [<0.01]

<0.02, <0.02, 

<0.02 [<0.02]

-- -- --
Thiabendazole Summary of Analytical Chemistry and Residue Data DP#: 363974

TABLE 6. Residue Data from Wheat Processing Studies with Thiabendazole and Benzimidazole.

RAC Processed 

Commodity

Total 

Rate1

lb ai/A

(g ai/ha)

DAP2 Residues (ppm), [Average]3Processing Factor4

Thiabendazole Benzimidazole Combined5 ThiabendazoleBenzimidazoleCombined5

Bran <0.01, <0.01 

[<0.01]

<0.01, <0.01 

[<0.01]

<0.02, <0.02 

[<0.02]

NC NC NC

Flour <0.01, <0.01 

[<0.01]

<0.01, <0.01 

[<0.01]

<0.02, <0.02 

[<0.02]

NC NC NC

Middlings <0.01, <0.01 

[<0.01]

<0.01, <0.01 

[<0.01]

<0.02, <0.02 

[<0.02]

NC NC NC

Shorts <0.01, <0.01 

[<0.01]

<0.01, <0.01 

[<0.01]

<0.02, <0.02 

[<0.02]

NC NC NC

Germ <0.01, <0.01 

[<0.01]

<0.01, <0.01 

[<0.01]

<0.02, <0.02 

[<0.02]

NC NC NC

Richland, IA; 2011 (TK0014192-21)

Soybean Preprocessed 

Seed

(RAC)

0.09 

(100.9) 

126 <0.01, <0.01, 

<0.01 [<0.01]

<0.01, <0.01, 

<0.01 [<0.01]

<0.02, <0.02, 

<0.02 [<0.02]

-- -- --

Meal <0.01, <0.01 

[<0.01]

<0.01, <0.01 

[<0.01]

<0.02, <0.02 

[<0.02]

NC NC NC

Hulls <0.01, <0.01 

[<0.01]

<0.01, <0.01 

[<0.01]

<0.02, <0.02 

[<0.02]

NC NC NC

Refined oil <0.01, <0.01 

[<0.01]

<0.01, <0.01 

[<0.01]

<0.02, <0.02 

[<0.02]

NC NC NC

Flour <0.01, <0.01 

[<0.01]

<0.01, <0.01 

[<0.01]

<0.02, <0.02 

[<0.02]

NC NC NC

Soy milk <0.01, <0.01 

[<0.01]

<0.01, <0.01 

[<0.01]

<0.02, <0.02 

[<0.02]

NC NC NC

Tofu <0.01, <0.01 

[<0.01]

<0.01, <0.01 

[<0.01]

<0.02, <0.02 

[<0.02]

NC NC NC

Soy sauce <0.01 [<0.01] <0.01[<0.01] <0.02 [<0.02] NC NC NC

Miso <0.01, <0.01 

[<0.01]

<0.01, <0.01 

[<0.01]

<0.02, <0.02 

[<0.02]

NC NC NC

Pollard <0.01, <0.01

[<0.01]

<0.01, <0.01 

[<0.01]

<0.02, <0.02 

[<0.02]

NC NC NC

Crude oil <0.01, <0.01 

[<0.01]

<0.01, <0.01 

[<0.01]

<0.02, <0.02 

[<0.02]

NC NC NC

Marysville, OH; 2011 (TK0014192-22)

Soybean Preprocessed 

Seed

(RAC)

0.09 

(100.9) 

130 <0.01, <0.01, 

<0.01 [<0.01]

<0.01, <0.01, 

<0.01 [<0.01]

<0.02, <0.02, 

<0.02 [<0.02]

-- -- --

Meal <0.01, <0.01 

[<0.01]

<0.01, <0.01 

[<0.01]

<0.02, <0.02 

[<0.02]

NC NC NC

Hulls <0.01, <0.01 

[<0.01]

<0.01, <0.01 

[<0.01]

<0.02, <0.02 

[<0.02]

NC NC NC

Refined oil <0.01, <0.01 

[<0.01]

<0.01, <0.01 

[<0.01]

<0.02, <0.02 

[<0.02]

NC NC NC
Thiabendazole Summary of Analytical Chemistry and Residue Data DP#: 363974

TABLE 6. Residue Data from Wheat Processing Studies with Thiabendazole and Benzimidazole.

RAC Processed 

Commodity

Total 

Rate1

lb ai/A

(g ai/ha)

DAP2 Residues (ppm), [Average]3Processing Factor4

Thiabendazole Benzimidazole Combined5 ThiabendazoleBenzimidazoleCombined5

Flour <0.01, <0.01 

[<0.01]

<0.01, <0.01 

[<0.01]

<0.02, <0.02 

[<0.02]

NC NC NC

Soy milk <0.01, <0.01 

[<0.01]

<0.01, <0.01 

[<0.01]

<0.02, <0.02 

[<0.02]

NC NC NC

Tofu <0.01, <0.01 

[<0.01]

<0.01, <0.01 

[<0.01]

<0.02, <0.02 

[<0.02]

NC NC NC

Soy sauce <0.01 [<0.01] <0.01[<0.01] <0.02 [<0.02] NC NC NC

Miso <0.01, <0.01 

[<0.01]

<0.01, <0.01 

[<0.01]

<0.02, <0.02 

[<0.02]

NC NC NC

Pollard <0.01, <0.01 

[<0.01]

<0.01, <0.01 

[<0.01]

<0.02, <0.02 

[<0.02]

NC NC NC

Crude oil <0.01, <0.01 

[<0.01]

<0.01, <0.01 

[<0.01]

<0.02, <0.02 

[<0.02]

NC NC NC

1 Application rates in lb ai/A were calculated by the study reviewer from the approximate seeding rate (seed/A) and the actual 

seed treatment rate (mg ai/seed). NOTE: Application rates in lb ai/A reported by the petitioner appear to have been calculated 

using the nominal seed treatment rate in mg ai/seed (0.15 mg ai/seed) instead of the actual seed treatment rates in mg ai/seed 

(0.14 and 0.155 mg ai/seed). 

2 DAP = Days After Planting. Seeds were planted within 8-43 days of treatment. 

3 The LOQ was 0.01 ppm for each analyte in all matrices; the combined LOQ was <0.02 ppm. Per trial averages were calculated 

by the study reviewer using the LOQ for values reported as <LOQ.

4

Processing Factor = [Measured residue for analyte in the processed fraction] / [Measured residue for analyte in the RAC]. 

Processing factors for this study were not calculated (NC) because residues were below the LOQ (<0.01 ppm for both analytes) 

in the RAC and processed fraction.

5 Combined residues of thiabendazole and benzimidazole. Residues of benzimidazole were not converted to parent equivalents..

860.1650 Submittal of Analytical Reference Standards

Analytical standards are currently available for thiabendazole (expiration 3/31/2017) and 5-

hydroxy-thiabendazole (expiration 2/28/2014) in the EPA National Pesticide Standards 

Repository (email from Theresa Cole, ACB, 2/25/2014); a standard is not available for 

benzimidazole.

For benzimidazole, a new standard must be submitted. For 5-hydroxy-thiabendazole, the 

registrant must either recertify the lot in the repository and send in an updated certificate of 

analysis (COA), or submit new standards (different lot #) if the previous lots will not be 

recertified. If a new COA is being submitted, it should be faxed to the repository at 410-305-

2999. Reference standards should be sent to the Analytical Chemistry Lab, which is located at 

Fort Meade, to the attention of either Theresa Cole or Thuy Ngygen at the following address:

USEPA

National Pesticide Standards Repository/Analytical Chemistry Branch/OPP

701 Mapes Road

Fort George G. Meade, MD 20755-5350

(Note that the mail will be returned if the extended zip code is not used.)
Thiabendazole Summary of Analytical Chemistry and Residue Data DP#: 363974

860.1850 and 860.1900 Confined and Field Accumulation in Rotational Crops

Revised Residue Chemistry Chapter of the Thiabendazole RED DP# 267871, 9/7/00, T. Morton

The available confined rotational crop data, discussed in the RED, are adequate, pending 

submission of information on sample storage intervals and supporting storage stability data for 

the metabolites benzimidazole and 5-hydroxy-thiabendazole that were required in the RED. 

Based on the available data, the residues of concern are the same in rotated crops as in primary

crops. 

A limited field rotational crop study was required in the RED, and was included in the 

submission of the current petition.

Syngenta Crop Protection, LLC has submitted the results of a limited field rotational crop study 

on a leafy vegetable (lettuce), root and tuber vegetable (radish), and cereal grain (wheat) from 13

trials conducted in the United States during the 2010 growing season. The trials were conducted 

in the North American Free Trade Agreement (NAFTA) Growing Zones 1 (NY; 1 trial with 

lettuce and radish), 2 (GA; 1 trial with radish), 4 (LA; 2 trials, one each with lettuce and radish), 

5 (IA, OH, ND; 5 trials with wheat), 6 (TX; 2 trials, one with lettuce and radish and one with 

lettuce), 10 (CA; 1 trial with lettuce), and 11 (OR; 1 trial with lettuce and radish). Together the 

submitted data reflect three trials for each crop at representative plantback intervals (PBIs) of 30, 

90, and 270 days.

At each test location, one control plot and one treated plot were established, with separate treated 

subplots as needed for each commodity and PBI. At each treated plot, a single bare-ground 

incorporated application of a flowable concentrate (water-dispersible suspension) for seed 

treatment (FS) formulation (Mertect® 340-F) containing 4.1 lb ai/gal thiabendazole was applied 

to the soil at a target rate of 0.0275 lb ai/A; actual application rates were 0.0258-0.0291 lb ai/A. 

Applications were made in spray volumes of ~15-30 gal/A using ground equipment. No 

adjuvants were included in the spray mixtures. Rotational crops of lettuce, radish, and/or wheat 

were planted at target PBIs of 30, 90, and 270 days after application; actual PBIs were 26-32, 58-

90, and 242-295 days. 

Samples of lettuce leaves, radish roots and tops, and wheat grain and straw were collected at 

normal crop maturity. Samples intended to be representative of fall and spring wheat forage 

were collected ~60 days after planting for fall forage and at the 6- to 8-inch stem elongation 

stage (approximately 25% dry matter) for spring forage. Wheat hay was collected at early flower 

(boot) to soft dough stage. Hay was dried in the field to 10-20% moisture content; drying 

intervals were not reported.

Samples were analyzed for residues of thiabendazole and benzimidazole using a liquid 

chromatography method with tandem mass spectrometry detection (LC/MS/MS), Method 

GRM040.01A. This method was previously reviewed by the Agency and was found to be 

acceptable for data collection (refer to 47705110.DER1, DP# 363974, 11/30/09, S. Hummel). 

The limit of quantitation (LOQ; determined as the lowest level of method validation, LLMV) 

was 0.01 ppm for each analyte, for a combined LOQ of 0.02 ppm. The method was adequate for 

data collection based on acceptable concurrent recovery data. The fortification levels used in 

concurrent method recovery were adequate to bracket expected residue levels. Concurrent 

recoveries were corrected for apparent residues in controls; residues in the treated samples were 
Thiabendazole Summary of Analytical Chemistry and Residue Data DP#: 363974

not corrected for apparent residues in controls. The method does not provide for conversion of 

residues of benzimidazole to parent equivalents.

Samples were stored frozen from harvest to analysis for 70-167 days (2.3-5.5 months) for lettuce 

leaves, 30-211 days (1.0-6.9 months) for radish roots and tops, 71-348 days (2.3-11.4 months) 

for wheat forage, 71-104 days (2.3-3.4 months) for wheat hay, 102-137 days (3.4-4.5 months) 

for wheat straw, and 74-115 days (2.4-3.8 months) for wheat grain. All samples were analyzed 

within 0-16 days of extraction. Acceptable storage stability data have been submitted 

demonstrating that residues of thiabendazole and benzimidazole in/on representative raw 

agricultural commodities are stable during frozen storage for up to ~10 months (refer to 

48996712.der, interim report). In addition, storage stability data are available indicating that 

residues of both analytes are stable during frozen storage for up to 28 months in/on whole potato 

and wet peel, for up to 23 months in/on wheat grain and straw (refer to the Residue Chemistry

Chapter of the Thiabendazole RED; DP# 267871, 9/7/00, T. Morton), and for up to 22 months 

in/on soybean forage, hay, and seed (DP# 280701, 12/9/10, T. Morton). These data are adequate 

to support the sample storage conditions and durations for the submitted study.

Following a single bare-ground incorporated application of the 4.1 lb ai/gal FS formulation of 

thiabendazole to the soil at a rate of 0.0258-0.0291 lb ai/A, residues of thiabendazole and 

benzimidazole were each below the LOQ (<0.01 ppm) in/on all samples of rotational crop 

commodities of lettuce, radish, and wheat at PBIs of 26-32, 58-90, and 242-295 days; combined 

residues were <0.02 ppm.

TABLE 7. Summary of Residue Data in Rotational Crops Following Primary Treatment with 

Thiabendazole.

Commodity Total Rate

(lb ai/A)

PBI 

(days)

Residue Levels (ppm)1

n Sample 

Min.

Sample 

Max.

LAFT2 HAFT2 Median Mean Std. 

Dev.

Thiabendazole, Benzimizole, Combined Residues

Lettuce, leaves 0.0258-0.0280 27-28 3 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

0.0271-0.0282 87-89 3 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

0.0270-0.0279 242-295 3 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

Radish, root 0.0275-0.0278 28-30 3 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

0.0273-0.0277 88-90 3 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

0.0270-0.0276 242-295 3 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

Radish, tops 0.0275-0.0278 28-30 3 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

0.0273-0.0277 88-90 3 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

0.0270-0.0276 242-295 3 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

Wheat, forage 0.0281-0.0291 26-32 3 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

0.0274-0.0280 58-88 3 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

0.0271-0.0281 266-273 3 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

Wheat, hay 0.0281-0.0291 26-32 3 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

0.0274-0.0280 58-88 3 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

0.0271-0.0281 266-273 3 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

Wheat, grain 0.0281-0.0291 26-32 3 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

0.0274-0.0280 58-88 3 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A
Thiabendazole Summary of Analytical Chemistry and Residue Data DP#: 363974

TABLE 7. Summary of Residue Data in Rotational Crops Following Primary Treatment with 

Thiabendazole.

Commodity Total Rate

(lb ai/A)

PBI 

(days)

Residue Levels (ppm)1

n Sample 

Min.

Sample 

Max.

LAFT2 HAFT2 Median Mean Std. 

Dev.

0.0271-0.0281 266-273 3 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

Wheat, straw 0.0281-0.0291 26-32 3 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

0.0274-0.0280 58-88 3 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

0.0271-0.0281 266-273 3 <0.01 <0.01 <0.01 <0.01 0.01 0.01 N/A

Conclusions. The submitted rotational crop study is adequate. Following a single bare-ground 

incorporated application of the 4.1 lb ai/gal FS formulation of thiabendazole to the soil at a rate 

of 0.0258-0.0291 lb ai/A, residues of thiabendazole and benzimidazole were each below the 

LOQ (<0.01 ppm) in/on all samples of rotational crop commodities of lettuce, radish, and wheat 

at PBIs of 26-32, 58-90, and 242-295 days; combined residues were <0.02 ppm.

An acceptable method was used for the determination of thiabendazole and benzimidazole in 

rotational crop commodities, and the study is supported by acceptable storage stability data

860.1550 Proposed Tolerances

The current tolerance expression for thiabendazole is:

“(1) Tolerances are established for the combined residues of the fungicide thiabendazole (2-(4-

thiazolyl)benzimidazole) and its metabolite benzimidazole (free and conjugated) in or on the 

following food commodities:” for plant commodities.

And 

“(2) Tolerances are established for the combined residues of thiabendazole (2-(4-

thiazolyl)benzimidazole) and its metabolites 5-hydroxythiabendazole (free and conjugated) and 

benzimidazole in or on the following food commodities:” for livestock commodities.

The tolerance expressions need to be updated as follows to reflect our current guidance. This 

will be accomplished during Registration Review.

Existing tolerance for residues of thiabendazole and metabolite on wheat grain and straw. The 

currently established tolerance for wheat grain is 1.0 ppm based on the originally submitted data 

set, showing interferences in the analytical method. Although the residues were all nonquantifiable, the tolerance was set at 1.0 ppm because of the interference. In the RED, the 

tolerance for residues in wheat grain was proposed to be reduced to 0.2 ppm, and in wheat straw 

to 0.5 ppm; these tolerances were based on foliar applications of thiabendazole to wheat. 

However, in connection with the current petition, a full new data set was submitted for all wheat 

commodities at the currently registered use pattern. The residues of thiabendazole and 

benzimidazole on wheat grain were all <LOQ (<0.01 ppm each, or <0.02 ppm total residues). 

Thus, we conclude that the current tolerance for residues of thiabendazole and benzimidazole on 

wheat grain may be reduced to 0.05 ppm. 
Thiabendazole Summary of Analytical Chemistry and Residue Data DP#: 363974

International Harmonization. There is no issue with International Harmonization. CODEX has 

not established any established maximum residue limits (MRLs) for thiabendazole on the 

requested commodities. Canada has not established maximum residue limits (MRLs) for 

thiabendazole on the requested commodities. We note that the U.S. tolerance expression is not 

harmonized with Canada, nor CODEX. An International Residue Limit Status Sheet is attached 

in Appendix I.

Table 8. Tolerance Summary for Thiabendazole. § 180.242

Commodity

Current/Proposed 

Tolerance (ppm)

Recommended 

Tolerance 

(ppm)

Comments; Correct Commodity 

Definition

alfalfa, forage 0.02 0.02 Alfalfa, forage

alfalfa, hay 0.02 0.02 Alfalfa, hay

alfalfa, seed 0.02 - Tolerances are not normally set 

for alfalfa seed

barley, grain 0.05 0.05 Barley, grain

barley, hay 0.15 0.3 Barley, hay

Revised level based on OECD 

tolerance calculation procedures, 

and to be consistent across all 

hays and straws.

barley, straw 0.15 0.3 Barley, straw

Revised level based on OECD 

tolerance calculation procedures, 

and to be consistent across all 

hays and straws.

Brassica, Head and 

Stem, subgroup 5-A

0.02 0.02

oats, forage 0.2 0.3 Oats, forage

Revised level based on OECD 

tolerance calculation procedures, 

and to be consistent across all 

cereal grain forages.

oats, grain 0.05 0.05 Oats, grain

oats, hay 0.09 0.3 Oats, hay

Revised level based on OECD 

tolerance calculation procedures, 

and to be consistent across all 

hays and straws.
Thiabendazole Summary of Analytical Chemistry and Residue Data DP#: 363974

Table 8. Tolerance Summary for Thiabendazole. § 180.242

Commodity

Current/Proposed 

Tolerance (ppm)

Recommended 

Tolerance 

(ppm)

Comments; Correct Commodity 

Definition

oats, straw 0.09 0.3 Oats, straw

Revised level based on OECD 

tolerance calculation procedures, 

and to be consistent across all 

hays and straws.

Onion, bulb, 

Subgroup 3-07A

0.02 0.02

radish, tops 0.02 0.02 Radish, tops

rye, forage 0.2 0.2 Rye, forage

rye, grain 0.05 0.05 Rye, grain

rye, straw 0.15 0.3 Rye, straw

Revised level based on OECD 

tolerance calculation procedures, 

and to be consistent across all 

hays and straws.

spinach 0.02 0.02 Spinach

triticale, forage 0.2 0.23 Triticale, forage

Revised level based on OECD 

tolerance calculation procedures, 

and to be consistent across all 

cereal grain forages.

triticale, grain 0.05 0.05 Triticale, grain

triticale, hay 0.09 0.15 Triticale, hay

Revised level based on OECD 

tolerance calculation procedures, 

and to be consistent across all 

hays and straws.

triticale, straw 0.09 0.15 Triticale, straw

Revised level based on OECD 

tolerance calculation procedures, 

and to be consistent across all 

hays and straws.

Vegetable, Cucurbit 

group 9

0.02 0.02 Vegetable, Cucurbit, group 9

Vegetable, root 

(except sugarbeet), 

subgroup 1B

0.02 0.02 Revised level based on OECD 

tolerance calculation procedures. 
Thiabendazole Summary of Analytical Chemistry and Residue Data DP#: 363974

Table 8. Tolerance Summary for Thiabendazole. § 180.242

Commodity

Current/Proposed 

Tolerance (ppm)

Recommended 

Tolerance 

(ppm)

Comments; Correct Commodity 

Definition

Wheat, grain 1.0 0.05 Current tolerance for wheat grain 

is 1.0 ppm, tolerance 

recommended in RED was 0.2 

ppm. Current recommendation is 

based on full new data set showing 

all non-quantifiable residues.

wheat, forage 0.2 0.3 Wheat, forage

Revised level based on OECD 

tolerance calculation procedures, 

and to be consistent across all 

cereal grain forages.

wheat, hay 0.09 0.3 Wheat, hay

Revised level based on OECD 

tolerance calculation procedures, 

and to be consistent across all 

hays and straws.

Wheat, straw 1.0 0.3 RED recommended lowering 

tolerance. Current 

recommendation is to be 

consistent across all hays and 

straws.

References

DP#: 165718

Subject: ID# 060101-618. Thiabendazole Phase V Review. Metabolism Studies: Wheat, 

Soybean and Sugar Beet.

From: L. Cheng

To: F. RubisDated: 3/11/92

MRIDs: 41872901, 41872902 and 41872903

DP#s: 207850, 218096, 245782, 245785, and 245787

Subject: Thiabendazole Reregistration. 860.1500 and 860.1340-Response to Agency 

Reviews for Magnitude of the Residue in Apples, Citrus, and Wheat; Analytical 

Method in Wheat and ILV, Magnitude of the Residue in Citrus and Banana 

Following Post-harvest Dip Application.

From: S. Mason

To: W. Sproat

Dated: 1/8/99

MRIDs: 43328301-43328303, 43328306, 43328307 and 43721901-43721904
Thiabendazole Summary of Analytical Chemistry and Residue Data DP#: 363974

DP#: None

Subject: Classification of Seed Treatments as Food or Nonfood Uses.

From: Chemistry Science Advisory Council

To: HED Chemistry Interest Group

Dated: 10/28/99

MRID: None

DP#: 267871

Subject: Thiabendazole (060101) Reregistration Case No. 2760. Revised Product and 

Residue Chemistry Chapters for the Thiabendazole Reregistration Eligibility 

Decision (RED).

From: T. Morton

To: B. Edwards/S. Lewis

Dated: 9/7/00

MRIDs: None

DP#: 270154

Subject: Thiabendazole (Chemical No. 060101). Reregistration Case No. 2670. Nature of 

the Residue in Soybeans Grown form Seeds Treated with Thiabendazole (GLN 

860.1300) and Magnitude of the Residues of Thiabendazole in/on Soybeans 

Grown from Seed Treated with Thiabendazole (GLN 860.1500).

From: T. Morton

To: B. Edwards/S. Lewis

Dated: 2/22/01

MRID: 45200301

DP#: 343139

Subject: Thiabendazole: Final Threshold of Regulation Decision to Support Proposed New 

Use as a Seed Treatment for Dry Pea. Petition No: PP#6E6323.

From: D. Davis

To: S. Stanton and B. Madden

Dated: 8/29/07

MRID: None

RDI:SHummel:01/14/2014

PP#: none

DP Barcode: D410807, D410833, D313507

PC Code: 060101

Template Version September 2005
Thiabendazole Summary of Analytical Chemistry and Residue Data DP#: 363974

Appendix I - International Residue Status Sheet

International Residue Limits 

Thiabendazole (PC Code 060101; Date of Request 12/12/13)

Summary of US and International Tolerances and Maximum Residue Limits 

Residue Definition:

US Canada Mexico1 Codex2

40 CFR 180.242

Plants: 2-(4-thiazolyl)benzimidazole) 

and its metabolite benzimidazole (free 

and conjugated)

2-(4-

thiazolyl)benzimidazole

Plants: thiabendazole

Commodity Tolerance (ppm) /Maximum Residue Limit (mg/kg)

US Canada Mexico1 Codex2

Vegetable, root (except sugar 

beet); subgroup1B

0.02

Onion, bulb, subgroup 3-07A 0.02

Brassica, head and stem, 

subgroup 5A

0.02

Vegetable, cucurbit group 9 0.02

Alfalfa 0.02

Spinach 0.02

Small grains (barley, oats, rye, 

and triticale)

0.02

Wheat grain 1.0

Completed: M. Negussie; 12/12/2013

1 Mexico adopts US tolerances and/or Codex MRLs for its export purposes.

2

* = absent at the limit of quantitation; Po = postharvest treatment, such as treatment of stored grains. PoP = 

processed postharvest treated commodity, such as processing of treated stored wheat. (fat) = to be measured on the 

fat portion of the sample. MRLs indicated as proposed have not been finalized by the CCPR and the CAC.
Thiabendazole Summary of Analytical Chemistry and Residue Data DP#: 363974

Appendix II - OECD Calculator

Compound Thiabendazole Thiabendazole Thiabendazole

Crop Wheat Forage Wheat Hay Wheat Straw

Region / Country US US US

GAP 0.11 lb ai/A 0.11 lb ai/A 0.11 lb ai/A

Total number of data (n) 19 19 19

Percentage of censored data 53% 79% 89%

Number of non-censored data 9 4 2

Lowest residue 0.020 0.020 0.020

Highest residue 0.210 0.072 0.083

Median residue 0.020 0.020 0.020

Mean 0.035 0.025 0.024

Standard deviation (SD) 0.044 0.015 0.015

Correction factor for 

censoring (CF) 0.649 0.474 0.404

Proposed MRL estimate

- Highest residue 0.210 0.072 0.083

- Mean + 4 SD 0.211 0.086 0.082

- CF x 3 Mean 0.068 0.036 0.029

Unrounded MRL 0.211 0.086 0.083

Rounded MRL 0.3 0.09 0.09

High uncertainty of 

MRL estimate due to 

high level of 

censoring.

Residues (mg/kg) Residues (mg/kg) Residues (mg/kg)

0.020 * 0.020 * 0.020 *

0.023 0.021 0.020 *

0.020 * 0.021 0.020 *

0.020 * 0.020 * 0.020 *

0.020 * 0.020 * 0.020 *

0.020 * 0.020 * 0.020 *

0.021 0.020 * 0.020 *

0.029 0.020 * 0.020 *

0.020 * 0.020 * 0.020 *

0.025 0.020 * 0.020 *

0.020 * 0.020 * 0.020 *
Thiabendazole Summary of Analytical Chemistry and Residue Data DP#: 363974

0.020 * 0.020 * 0.020 *

0.037 0.020 * 0.023 *

0.071 0.020 * 0.020 *

0.020 * 0.020 * 0.020 *

0.210 0.072 0.032

0.027 0.065 0.083

0.020 * 0.020 * 0.020 *

0.024 0.020 * 0.020 *
Thiabendazole Summary of Analytical Chemistry and Residue Data DP#: 363974

Compound Thiabendazole Thiabendazole

Crop Barley Hay Barley Straw

Region / Country US US

GAP 0.11 lb ai/A 0.11 lb ai/A

Total number of data (n) 12 12

Percentage of censored data 58% 67%

Number of non-censored data 5 4

Lowest residue 0.020 0.020

Highest residue 0.200 0.092

Median residue 0.022 0.020

Mean 0.048 0.034

Standard deviation (SD) 0.057 0.024

Correction factor for censoring 

(CF) 0.611 0.556

Proposed MRL estimate

- Highest residue 0.200 0.092

- Mean + 4 SD 0.277 0.130

- CF x 3 Mean 0.088 0.056

Unrounded MRL 0.277 0.130

Rounded MRL 0.3 0.15

High uncertainty 

of MRL estimate 

due to high level 

of censoring.

High uncertainty 

of MRL estimate 

due to high level 

of censoring.

Residues (mg/kg) Residues (mg/kg)

0.020 * 0.020 *

0.028 0.038

0.020 * 0.020 *

0.020 * 0.020 *

0.020 * 0.020 *

0.020 * 0.020 *

0.020 * 0.020 *

0.130 0.092

0.052 0.072

0.023 0.020 *

0.026 0.040

0.200 * 0.020 *