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: July 30, 2014 - Draft Internal Deliberative

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. Addendum.

PC Code: 060101 DP Barcode: D410807 addendum

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

Registration Division (7505P)

This memo serves to update the tolerance expression for thiabendazole and the tolerance 

recommendations.

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

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. 

(1) Tolerances are established for residues of thiabendazole, including its metabolites and 

degradates, in or on the commodities in the table below. Compliance with the tolerance levels 

specified below is to be determined by measuring only the sum of thiabendazole (2-(4-

thiazolyl)benzimidazole) and its metabolite benzimidazole (free and conjugated), calculated as 

the stoichiometric equivalent of thiabendazole, in or on the commodity.

(2) Tolerances are established for residues of thiabendazole, including its metabolites and 

degradates, in or on the commodities in the table below. Compliance with the tolerance levels 

specified below is to be determined by measuring only the sum of thiabendazole (2-(4-

thiazolyl)benzimidazole) and its metabolites 5-hydroxythiabendazole (free and conjugated) and 

benzimidazole (free and conjugated), calculated as the stoichiometric equivalent of 

thiabendazole, in or on the commodity.

International Harmonization. There is no issue with International Harmonization for the current 

petition. 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, or CODEX. This will be examined further during 

registration review.

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.
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

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.

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 0.3 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
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

triticale, forage 0.2 0.3 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 0.3 Triticale, hay

Revised level based on OECD 

tolerance calculation procedures, 

and to be consistent across all

hays and straws.

triticale, straw 0.09 0.3 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 sugar beet), 

subgroup 1B

0.02 0.02 Revised level based on OECD 

tolerance calculation procedures. 

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.
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, straw 1.0 0.3 RED recommended lowering 

tolerance. Current 

recommendation is to be 

consistent across all hays and 

straws.