Zeta-Cypermethrin Summary of Analytical Chemistry and Residue Data OP Barcode 042280 I 

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON, DC 20460 

MEMORANDUM 

DATE: 20 February 2015 

OFFICE OF CHEMICAL SAFETY AND 

POLLUTION PREVENTION 

SUBJECT: Zeta-Cypermethrin. Petition to Amend (Increase) the Established Tolerances 

for the Insecticide in Field Corn and Popcorn Stover, and in Field Corn Forage. 

Summary of Analytical Chemistry and Residue Data. 

PC Code: 129064 

Decision Number: 492384 

Petition: 4F8290 

DP Barcode: D42280 I 

Registration Numbers: 279-3125, 279-3126, 279-3426 

Regulatory Action: Section 3 

Risk Assessment Type: NA 

TXR Number: NA 

Case Number: 2130 

CAS Number: 52315-07-8 

MRID Number: 4941220 I 40 CFR: §180.418 

FROM: 

THRU: 

TO: 

Risk 

William 

Ass

T. 

ess

Dr

me

ew, 

nt Branch 

Chemist 

II (RAB2) 

~ 

Dennis McNeilly, Chemist ~........--- fr'1 l..- JV/. 

Health Effects Division (HED), 7509P ~ 

RAB2/HED, 7509P ,_,. 

Kable Davis and Julie Chao, RM Team 3 

Invertebrate and Vertebrate Branch 1 (IVB l) 

Registration Division (RD), 7505P 

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Zeta-Cypermethrin Summary of Analytical Chemistry and Residue Data DP Barcode D42280 I 

Table of Contents 

l .O Executive Summary ........................ ............................... .... .... .......................................... ..... 4 

2.0 Regulatory Recommendations .............................................................................................. 6 

2.1 Data Deficiencies/Data Needs .......................................................................................... 6 

2.2 Tolerance Considerations .................................................................................................. 6 

2.2. 1 Enforcement Analytical Method/Multiresidue Methods .......................................... 6 

2.2.2 Recommended Tolerances ..................... ............... .... ................................... ... .......... 7 

2.2.3 Revisions to Petitioned-For Tolerances .... ....... ........ ............................ ... .... ....... ....... 7 

2.2.4 International Harmonization ........................................................... ......................... . 7 

2.3 Label Reco1nmendations .................................................................................................. 7 

2.4 Submittal of Analytical Reference Standards (860.1650) ............................................... 7 

3.0 Chemical Identity ...................................................... ........................................................... 8 

3.1 Nomenclature ................................................... ........ .... ...................................... .............. 8 

3.2 Physicochemical Characteristics ......... .................... .... ................................................. .... 9 

3.3 Pesticide Use Pattern/Directions for Use (860.1200) ........... .............. ............................ . 9 

4.0 Metabolite/Degradate Residue Profile ............................................................................... I 0 

4.1 Nature of the Residue .................................................... ................................................. 10 

4.1.1 Summary of Plant and/or Livestock Metabolism (860.1300) ................................. I 0 

4.1.2 Summary of Confined Rotational Crops (860.1850) .................................... .... ....... 11 

4.1.3 Summary of Rat Metabolism ................. ............................. ......................... ....... .... 11 

4.1.4 Summary of Environmental Degradation ..... .............................................. ............ 12 

5.0 Residue Profile ............................ .... .... ........ ....................................................................... 12 

5.1 Residue Analytical Methods (860. 1340) ...................................................................... 12 

5.1.1 Data Collection Methods ........................................................................................ 12 

5.1.2 Multi-Residue Methods (860.1360) ........... ............................................................. 14 

5.1.3 Tolerance Enforcement Methods ...................... .... .............................................. .... 15 

5.2 Storage Stability (860.1380) .... .... ............ .... .... .... ........................................... ... ............ 15 

5.3 Residue Data ................................................... .... ........................................... ................ 16 

5.3.1 Crop Fie ld Trials (860.1500) .................................................................................. 16 

5.3.2 Field Rotational Crops (860.1900) ......................................................................... 17 

5.3.3 Processed Food and Feed (860. 1520) ......... ........ .... ................................................ 17 

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5.3.4 Meat, Milk, Poultry and Eggs (860.1480) .............................................................. 18

5.3.5. Food Handling (860.1460)...................................................................................... 18

5.3.6 Water, Fish and Irrigated Crops (860.1400)........................................................... 18

5.4 Food Residue Profile...................................................................................................... 18

6.0 Tolerance Derivation ......................................................................................................... 19

References..................................................................................................................................... 19

Attachment 1: International Residue Limit Status....................................................................... 21

Attachment 2: OECD Tolerance Assessment Calculations......................................................... 22
Zeta-Cypermethrin Summary of Analytical Chemistry and Residue Data DP Barcode D422801

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1.0 Executive Summary

Zeta-cypermethrin (with CAS name (S)-cyano(3-phenoxyphenyl)methyl-3-(2,2-

dichloroethenyl)-2,2-dimethylcyclopropanecarboxylate, and CAS number 52315-07-8) is a 

broad-spectrum, pyrethroid insecticide containing the same eight stereoisomers that are present 

in cypermethrin. However, zeta-cypermethrin is enriched in the four insecticidally active S

isomers, and contains ≤1% each of the inactive R isomers. Permanent tolerances for residues of 

zeta-cypermethrin, including its inactive R isomers, have been established in or on plant and 

animal commodities at levels ranging from 0.05-40 ppm (40CFR §180.418[a][2]). The most 

recent previous residue chemistry summary document for zeta-cypermethrin was completed in 

conjunction with a petition to increase use rates on alfalfa grown for forage and hay (D416982; 

W.T. Drew; 31 October 2014). 

Zeta-cypermethrin is currently registered to FMC Corporation for use on a wide variety of food 

and feed crops, primarily as repeated foliar broadcast applications. In the current petition

(4F8290), FMC is proposing label amendments specifying decreased pre-harvest intervals (PHIs) 

for field corn and popcorn, from the current 30 days for grain and stover, and 60 days for forage, 

to 7 days for all of these commodities. FMC is also proposing to amend (by increasing) the 

currently established tolerances for zeta-cypermethrin residues in field corn forage of 0.20 ppm, 

and in field corn and popcorn stover of 3.00 ppm. The label amendments would apply to three 

end-use products (EPs). These EPs are Fury 1.5 EC Insecticide (EPA Registration #279-3125), 

an emulsifiable concentrate (EC) formulation containing 1.5 pounds of active ingredient per 

gallon (lb ai/gal); Fury 1.5 EW (formerly Mustang) Insecticide (EPA Registration #279-3126), 

an emulsifiable water-based concentrate (EW) formulation containing 1.5 lb ai/gal; and F9114 

EC Insecticide (EPA Registration #279-3426), an EC formulation containing 0.8 lb ai/gal. 

In conjunction with the requested decrease in PHIs for field corn and popcorn, FMC has 

proposed the amendment of the existing permanent tolerances for residues of zeta-cypermethrin

in/on the following raw agricultural commodities (RACs), to the tolerance levels listed below. 

Corn, field, forage ............................................................................ 9.0 ppm

Corn, field, stover .......................................................................... 30.0 ppm

Corn, pop, stover............................................................................ 30.0 ppm

The recommended amended tolerances were derived by entering the submitted corn field trial 

data into the Organization for Economic Development and Cooperation’s (OECD’s) tolerance 

calculation procedure. FMC has not proposed to amend the current tolerances in field corn grain 

or popcorn grain, as the field trial residue data submitted with the petition support the current 

tolerances on these commodities. 

This summary document addresses the data submitted in support of increasing the established

tolerances for residues of zeta-cypermethrin in field corn forage, and in field corn and popcorn 

stover listed in 40CFR §180.418[a][2]. 
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Crop Field Trials: To support the requested increased use rates, 15 field trials with zetacypermethrin were conducted on field corn to determine the resulting residues in grain, forage 

and stover. 

Two trial sites consisted of an untreated plot which produced single composite samples, and one 

treated plot which yielded duplicate composite samples of grain, forage and stover. Each treated 

plot received 1 in-furrow application at a rate of 0.05 pounds of active ingredient per acre (lb 

ai/A), followed by either 2 broadcast foliar applications (forage) or three applications (grain and 

stover), each at 0.05 lb ai/A, for total application rates of 0.15 lb ai/A to corn forage, and 0.20 lb 

ai/A to corn grain and stover. The zeta-cypermethrin applied at the trials was formulated as 

either Fury 1.5 EC Insecticide or Fury 1.5 EW Insecticide. Because the forage samples from 

these trials were treated at the rate of only 0.15 lb ai/A, the forage results were not included in 

the current review. 

Thirteen trial sites included an untreated plot which produced single composite samples, and 2

treated plots, one of which provided duplicate composite samples of forage, and the other for

duplicate composite samples of grain and stover. Each treated plot received 4 foliar broadcast 

applications of zeta-cypermethrin at a target rate of 0.05 lb ai/A per application, for a total 

application rate of 0.20 lb ai/A. The zeta-cypermethrin applied at the trials was formulated as 

either Fury 1.5 EC Insecticide or Fury 1.5 EW Insecticide. 

These adequate field corn field trial data support a tolerance of 9.0 ppm in field corn forage, and 

tolerances of 30 ppm in field corn and popcorn stover. 

Residue Analytical Methods: Adequate tolerance enforcement methods are available for 

determining residues of cypermethrin, alpha-cypermethrin and zeta-cypermethrin in or on plant 

(Method I) and livestock (Method II) commodities. Both methods are gas chromatographic 

methods with electron capture detection (GC/ECD), and have undergone successful Agency 

method validations. Method I has a limit of detection (LOD) of 0.01 ppm, and Method II has 

LODs of 0.005 ppm in milk and 0.01 ppm in livestock tissues. These methods are not 

stereospecific; thus no distinction is made between residues of cypermethrin (all 8 

stereoisomers), zeta-cypermethrin (enriched in 4 isomers) and alpha-cypermethrin (enriched in 2 

isomers). 

The January 1994 Food and Drug Administration (FDA) PESTDATA database (PAM Volume I) 

indicates that residues of cypermethrin are completely recovered (>80%) using multiresidue 

method Sections 302 (Luke), 303 (Mills, Onley, and Gaither) and 304 (Mills fatty food). 

Storage Stability: Adequate storage stability data are available to support the storage durations 

and conditions of samples from the submitted corn field trial studies. 
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Meat, Milk, Poultry and Eggs: The existing tolerances for zeta-cypermethrin of 40 ppm in 

trefoil and lespedeza hays are protective of the proposed upward revision of the tolerances in 

field corn forage to 9.0 ppm, and field corn and popcorn stover to 30 ppm. Therefore, the

proposed decreased PHIs for field corn and popcorn will not result in the need to increase the 

tolerances in livestock commodities. 

MRL Harmonization: There are no Codex maximum residue limits (MRLs) for cypermethrin, 

which includes both alpha- and zeta-cypermethrin, established in corn forage or stover. 

Canada’s Pest Management Regulatory Agency (PMRA) does not establish MRLs in livestock 

feedstuffs. 

2.0 Regulatory Recommendations

HED has examined the residue chemistry database for zeta-cypermethrin. Pending submission 

of a revised Section F (to propose tolerances in accordance with those recommended by HED), 

there are no residue chemistry issues that would preclude increasing the currently established 

tolerances for zeta-cypermethrin residues of 0.20 and 3.00 ppm in field corn forage, and field 

corn and popcorn stover, respectively, to 9.0 and 30 ppm. The recommended tolerances are 

listed in Table 2.2.2, below. 

2.1 Data Deficiencies/Data Needs

None. 

2.2 Tolerance Considerations

2.2.1 Enforcement Analytical Method/Multiresidue Methods

Adequate tolerance enforcement methods are available for determining residues of cypermethrin, 

alpha-cypermethrin and zeta-cypermethrin in or on plant (Method I) and livestock (Method II) 

commodities. Both methods utilize GC/ECD, and have undergone successful Agency method 

validations. Method I has an LOD of 0.01 ppm, and Method II has LODs of 0.005 ppm in milk 

and 0.01 ppm in livestock tissues. These methods are not stereospecific; thus no distinction is 

made between residues of cypermethrin (all 8 stereoisomers), zeta-cypermethrin (enriched in 4 

isomers) and alpha-cypermethrin (enriched in 2 isomers). 
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2.2.2 Recommended Tolerances

TABLE 2.2.2 Tolerance Summary for Zeta-Cypermethrin.

Commodity Proposed 

Tolerance (ppm)

Recommended 

Tolerance (ppm)

Comments; Correct Commodity 

Definition

Corn, field, forage 9.0 9.0

Corn, field, stover 30.0 30

Corn, pop, stover 30.0 30

2.2.3 Revisions to Petitioned-For Tolerances

The current tolerance expression for zeta-cypermethrin (40CFR §180.418[a][2]) is adequate, and 

includes both coverage and compliance statements for enforcement purposes. 

Instead of the proposed tolerances in field corn and popcorn stover (30.0 ppm), HED 

recommends establishing the tolerances at 30 ppm. The Agency establishes tolerances using 

whole numbers for tolerances of 10 ppm or more, per the OECD’s User Guide

ENV/JM/MONO(2011)2 for the OECD tolerance calculation procedure. 

2.2.4 International Harmonization

There are no Codex MRLs for cypermethrin, which includes both alpha- and zeta-cypermethrin, 

established in corn forage or stover. Canada’s PMRA does not establish MRLs in livestock 

feedstuffs, including corn forage or stover. 

2.3 Label Recommendations

None.

2.4 Submittal of Analytical Reference Standards (860.1650)

The analytical reference standard for zeta-cypermethrin, with an expiration date of 31 January

2020, is currently available in the EPA’s National Pesticide Standards Repository (NPSR), per

Email communication with Theresa Cole of the Biological and Economic Analysis Division’s 

(BEAD’s) Analytical Chemistry Branch (ACB) on 18 March 2015. The registrant is required to 

maintain reasonable amounts of the analytical reference standard for zeta-cypermethrin in the 

NPSR as long as tolerances remain published in 40CFR §180.418[a][2]. When necessary, a new 

reference standard, or updated certificate of analysis (COA), should be sent to the ACB, which is 

located at Fort Meade, MD. It should be sent to the attention of either Theresa Cole or Thuy 

Nguyen at the address listed below, along with a letter of transmittal. Please note that the full 

9-digit ZIP Code is required, or the mail will be returned to the registrant. 
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USEPA

National Pesticide Standards Repository

Analytical Chemistry Branch/BEAD/OPP

701 Mapes Road

Fort George G. Meade, MD 20755-5350

The letter of transmittal should include the assay of the standard, name of the analytical method 

used, a statement of principal impurities, purification procedures employed, storage 

requirements, and special precautions for safe handling. Replacement of standards may be 

required periodically if supplies are exhausted, if the standards expire, or if decomposition 

occurs during storage. Material Safety Data Sheets (MSDSs) must accompany all analytical 

standards as specified by the Occupational Safety and Health Administration (OSHA) in 29CFR

§1910.1200. 

3.0 Chemical Identity

Cypermethrin is a broad spectrum, pyrethroid insecticide, consisting of eight stereoisomers, each 

present at generally the same concentration (11-14%). Zeta-cypermethrin is enriched in the four 

insecticidally active S isomers, and contains ≤1% each of the inactive R isomers. Alphacypermethrin consists of the two most insecticidally active of the four cis-isomers of 

cypermethrin. They are contact insecticides that also work via ingestion. Zeta-cypermethrin is 

used to control a number of insects, such as beetles, aphids and numerous Lepidoptera. The 

mode of action of zeta-cypermethrin in the target organism is via modulation of the nervous 

system’s sodium channels, resulting in death. The chemical structure and nomenclature of zetacypermethrin are listed in Table 3.1, and its physicochemical properties are presented in Table 

3.2 (below). 

3.1 Nomenclature

TABLE 3.1 Zeta-Cypermethrin Nomenclature.

Compound

Common name Zeta-cypermethrin

Company experimental name FMC 56701

Molecular formula C22H19Cl2NO3

Molecular weight 416.3
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TABLE 3.1 Zeta-Cypermethrin Nomenclature.

IUPAC name (S)-α-cyano-3-phenoxybenzyl (1RS,3RS;1RS,3SR)-3-(2,2-dichlorovinyl)-2,2-

dimethylcyclopropanecarboxylate

CAS name (S)-cyano(3-phenoxyphenyl)methyl-3-(2,2-dichloroethenyl)-2,2-

dimethylcyclopropanecarboxylate

CAS registry number 52315-07-8

End-use products (EPs) Fury 1.5 EC Insecticide (EPA Registration #279-3125)

Mustang Insecticide (EPA Registration #279-3126)

F9114 EC Insecticide (EPA Registration #279-3426)

3.2 Physicochemical Characteristics

TABLE 3.2 Physicochemical Properties of Zeta-Cypermethrin.

Parameter Value Reference

Melting point/range (oC) 53.2-56.3 FAO Monograph

pH (1% aqueous suspension) 4.5 MRID #46971402

Density (g/mL at 25oC) 1.219

Water solubility (ppb at 25oC) 45

Solvent solubility Miscible in acetone, acetonitrile, 

methylene chloride, and toluene

Vapor pressure (mm Hg at 25oC) 1.9 x 10-9

Dissociation constant, pKa Not available

Octanol/water partition coefficient (Log [KOW]) >6

UV/visible absorption spectrum Not available

Zeta-cypermethrin is a solid under ambient conditions, and has very low volatility. The 

compound has a very low solubility in water, and is miscible in many organic solvents. Its 

octanol/water partition coefficient suggests that accumulation of zeta-cypermethrin in fatty 

tissues is possible. 

3.3 Pesticide Use Pattern/Directions for Use (860.1200)

FMC is proposing label amendments specifying decreased PHIs for field corn and popcorn, from 

the current 30 days for grain and stover, and 60 days for forage, to 7 days for all of these 

commodities. FMC is also proposing to amend (by increasing) the currently established 

tolerances for zeta-cypermethrin residues in field corn forage of 0.20 ppm, and in field corn and 

popcorn stover of 3.00 ppm. The label amendments would apply to three EPs. These EPs are 

Fury 1.5 EC Insecticide (EPA Registration #279-3125), an EC formulation containing 1.5 

pounds of active ingredient per gallon (lb ai/gal); Fury 1.5 EW Insecticide (EPA Registration 

#279-3126), an EW formulation containing 1.5 lb ai/gal; and F9114 EC Insecticide (EPA 

Registration #279-3426), an EC formulation containing 0.8 lb ai/gal. 

Because F9114 EC contains zeta-cypermethrin with a higher cis/trans ratio, it is applied at rates 

which are only half those of the Fury 1.5 EC and Fury 1.5 EW formulations. The proposed 

revised use directions are summarized in Table 3.3, below. 
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TABLE 3.3 Summary of Proposed Use Directions for Zeta-Cypermethrin on Field Corn and Popcorn. 

Application Type; 

Equipment1

Single Use 

Rate (lb 

ai/A)

Max. 

Uses Per 

Season

Max. 

Seasonal Use 

Rate (lb ai/A)

PHI2

(Days)

Use Directions, Application 

Timing, and Limitations3

Fury 1.5 EC and Fury 1.5 EW End-use Products

Foliar; ground, aerial or 

chemigation equipment.

0.016-0.05 NS4 0.2 7 Minimum RTI5 of 3 days. May 

be applied via chemigation. 

F9114 EC End-use Product

Foliar; ground, aerial or 

chemigation equipment.

0.008-0.025 NS 0.1 7 Minimum RTI of 3 days. May 

be applied via chemigation. 

1. For ground application, apply in a minimum of 10 gallons of water per acre (GPA). Do not apply through any 

ultra-low volume (ULV) spray system. For aerial application, apply in a minimum of 2 GPA. For 

chemigation, use only through sprinkler systems, including center pivot, lateral move, end tow, side 

(wheel) roll, traveler, big gun, solid set, or hand move irrigation systems. Do not apply through any other 

type of irrigation system. 

2. PHI = Pre-Harvest Interval. 

3. Begin applications when insect pest populations reach economic threshold levels. 

4. NS = Not Specified. 

5. RTI = Re-Treatment Interval. 

Conclusions: The proposed use directions for application on field corn and popcorn are 

sufficient to allow for evaluation of the submitted residue data relative to the proposed use 

patterns. 

4.0 Metabolite/Degradate Residue Profile

4.1 Nature of the Residue

HED MARC Determination of Residues of Concern (D269584; Y. Donovan; 3 November 2000)

The nature of the residue in plants and animals is adequately understood. HED’s Metabolism 

Assessment Review Committee (MARC) concluded that, in the case of cypermethrin and zetacypermethrin, the parent compound is the only residue of concern (ROC) to be included in the 

tolerance expression and used for dietary risk assessment, including drinking water. The MARC

also concluded that the metabolite DCVA (1-(RS)-cis-trans-3-(2,2-dichlorovinyl)-2,2-

dimethylcyclopropanecarboxylic acid) need not be included in the risk assessment and, therefore, 

can be waived in future cypermethrin, alpha-cypermethrin and zeta-cypermethrin residue studies. 

This decision regarding DCVA does not extend to other pyrethroids which generate this 

metabolite. Each such insecticide needs to be examined individually with respect to DCVA. 

4.1.1 Summary of Plant and/or Livestock Metabolism (860.1300)

Data have been submitted and reviewed depicting the metabolism/degradation of zetacypermethrin in numerous crops and the environment. HED has determined the plant and 
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livestock ROCs for purposes of tolerance enforcement and risk assessment; see Table 4.1.1

(below). 

Table 4.1.1 Summary of Zeta-Cypermethrin Residue Definitions for Use in Risk Assessment and the 

Tolerance Expression.

Matrix Residues Included in Risk 

Assessment

Residues Included in Tolerance 

Expression

Plants Primary crops Zeta-cypermethrin Zeta-cypermethrin

Rotational crops Zeta-cypermethrin* Zeta-cypermethrin*

Livestock Ruminants Zeta-cypermethrin Zeta-cypermethrin

Poultry Zeta-cypermethrin Zeta-cypermethrin

Drinking water Zeta-cypermethrin Not applicable

* At this time, there are no tolerances established in rotational crops; however, HED has determined that, should 

such a tolerance become necessary in the future, the ROC would be the parent compound only. 

Conclusions: The nature of the residue in plants and animals has been adequately delineated. 

4.1.2 Summary of Confined Rotational Crops (860.l850)

Residue Chemistry Summary Document D379486; E. Holman; 20 September 2012

The HED Chemistry Chapter of the Cypermethrin reregistration eligibility decision (RED)

document reported that adequate confined and limited field rotational crop studies are available 

for cypermethrin (D289422; W. Donovan; 25 September 2003). The results of the limited field 

rotational crop study indicate that residues of cypermethrin and its metabolites were 

nondetectable (<0.01 ppm) in/on the rotational crop commodities of leafy vegetables, root and 

tuber vegetables, and cereal grain crops that were planted 30 days after the soil plots were treated 

with cypermethrin at 0.5 lb ai/A (1.7X the maximum seasonal rate). The study supports the 

labeled plant-back interval (PBI) of 30 days, and no additional rotational crop data are required 

for cypermethrin. This conclusion also applies to zeta-cypermethrin. 

4.1.3 Summary of Rat Metabolism

Risk Assessment Document D378897, D385242, D397298; E. Holman; 12 October 2012 (0E7717, 

0E7804)

Major biotransformation products from single- and repeated-dose rat metabolism studies 

included oxidation of the methyl group on the acid moiety, hydroxylation at the 4’-position of 

the alcohol moiety, cleavage of the ester linkage, and conjugation with sulfuric and glucuronic 

acid. However, in the case of cypermethrin, radiolabeled residues in the feces are largely 

unmetabolized parent (>90% parent). 

The metabolites identified in the plant metabolism studies are either found as metabolites in the 

animal studies, or are intermediaries in the metabolic pathways elucidated in animals; therefore, 

there are no ROCs in plant studies, nor are there any unique metabolic pathways in the plant, that 

are not represented in the rat metabolism study. 
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4.1.4 Summary of Environmental Degradation

EFED Memo D378901, D385246; I. Maher; 22 February 2011

Based on similarities in the chemical properties and toxicological endpoints, environmental fate 

and ecotoxicity data are bridged between racemic cypermethrin, and the enriched isomeric 

mixtures (alpha-cypermethrin and zeta-cypermethrin). There is a complete environmental fate 

database for zeta-cypermethrin. 

Zeta-cypermethrin is expected to have little mobility in soil surfaces (Koc ≥ 20,800 L/kg), and 

leaching into groundwater is not expected to be an important transport process. Volatilization is 

not expected to be an important transport process either, since zeta-cypermethrin has a relatively 

low vapor pressure and Henry’s Law constant. Zeta-cypermethrin is moderately persistent in the 

environment, and degrades through a combination of biotic and abiotic mechanisms. Zetacypermethrin is relatively stable to hydrolysis at acidic and neutral pH levels, but degrades in a 

few days under alkaline conditions (pH 9, half-life of ~2 days). Zeta-cypermethrin is relatively 

light stable, but still undergoes photolysis in water, with half-lives of about a month or more in 

distilled water. The rate of photolysis appears to be enhanced in natural waters (which contain 

photosensitizing agents like humic and fulvic acids), where the accelerated degradation results in 

half-lives of a few days. Zeta-cypermethrin photo-degrades on soil with dark control corrected 

half-lives of ~128 days. Under both aerobic and anaerobic soil conditions, zeta-cypermethrin 

biodegrades relatively slowly in soils, with half-lives on the order of about 2 months. In 

contrast, under aerobic and anaerobic aquatic metabolism conditions, the degradation rate is 

enhanced, with half-lives of around 9 to 17 days. If released to water, zeta-cypermethrin 

partitions to sediment and may degrade slowly. Major degradates observed in laboratory studies 

result from cleavage at the ester moiety of zeta-cypermethrin, which formed 3-(2,2-dichloroethenyl)-2,2-dimethylcyclopropanecarboxylic acid (DCVA) and 3-phenoxybenzaldehyde. The 

latter is further oxidized to 3-phenoxybenzoic acid (3-PBA). Another product observed in the 

soil photolysis study only was cyperamide. 

5.0 Residue Profile

5.1 Residue Analytical Methods (860.1340)

5.1.1 Data Collection Methods

MRIDs #47440501 and 49412201

MRID #47440501: Residues of zeta-cypermethrin in treated and control samples of field corn 

grain and stover were determined using an analytical method that was similar to the method 

reported in FMC report P-3441, Magnitude of the Residues of zetaCypermethrin in/on Dried 

Shelled Pea, Succulent Pea, and Edible-Podded Pea Treated with Fury 1.5 EW or Fury 1.5 EC 

Insecticide. Briefly, the samples were prepared by chopping and homogenizing the entire field 
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sample, then removing a subsample for analysis. Subsamples were maintained frozen from 

receipt at the analytical facility until extraction for analysis. The method involved solvent

extraction (twice) with acetone/water (7:3, v:v), after which the supernatant was decanted and 

combined. An aliquot was partitioned with hexane, followed by concentration of the hexane 

phase. This was cleaned up with a silica gel cartridge, and analyzed via GC/ECD. The method 

limit of quantitation (LOQ) was validated at 0.05 ppm in field corn grain, and at 0.10 ppm in

field corn stover. The LOD varied from 0.01 to 0.04 ppm during the study, based upon the 

specific linear calibration equations for a given set. 

A Hewlett Packard (HP) HP-6890 GC/ECD in splitless injection mode, equipped with an HP7673A autosampler and a J&W Scientific DB-5 (5% phenyl-methylpolysiloxane) capillary 

column, was used for the determination of zeta-cypermethrin. The carrier gas was helium. An 

HP-5890 GC in splitless injection mode, equipped with an HP-7673A autosampler and a J&W 

Scientific DB-35MS (5% phenyl-methylpolysiloxane) capillary column coupled to a mass 

selective detector operating in selected ion monitoring mode was used for the confirmation of 

zeta-cypermethrin residues. The carrier gas was helium. 

TABLE 5.1.1.1 Summary of Concurrent Recoveries of Zeta-Cypermethrin from Field Corn Grain and 

Stover (MRID #47440501). 

Matrix Spike Level (ppm) Sample Size (n) Range of Recoveries (%) Mean ± Std. Dev. (%)

Field corn grain 0.050 3 67, 88, 78 78 ± 11

Field corn 

stover

0.100 1 86 83 ± 11

0.400 1 92

2.00 1 71

MRID #49412201: Residues of zeta-cypermethrin in treated and control samples of field corn 

grain, forage and stover were determined using an unidentified method. Briefly, the

homogenized sample was extracted using acetonitrile (ACN), and a wrist-action shaker. The 

extract was centrifuged, and the supernatant was filtered through glass wool. The extraction was 

repeated twice more, and the three extracts were combined. The final volume was adjusted with 

ACN, and the diluted sample was then analyzed via liquid chromatography with tandem mass 

spectrometric detection (LC/MS/MS). The validated LOQ of 0.05 ppm was established in all 

three matrices. The LOD was reported as 0.01 ppm. 

The analyses for zeta-cypermethrin were conducted using an Applied Biosystems API 4000 

LC/MS/MS equipped with a Phenomenex Synergi Fusion RP (reverse phase) column, employing 

gradient elution using two mobile phases (methanol containing 4 mM ammonium formate, and 

water containing 4 mM ammonium formate). 
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TABLE 5.1.1.2 Summary of Method Validation and Concurrent Recoveries of Zeta-Cypermethrin from 

Field Corn Grain, Forage and Stover (MRID #49412201). 

Matrix Spike Level (ppm) Sample Size (n) Range of Recoveries (%) Mean ± Std. Dev. (%)

Method Validation Recoveries

Field corn

grain

0.050 3 83, 89, 88 86 ± 3

0.500 3 84, 85, 83 84 ± 1

Field corn 

forage

0.050 3 81, 76, 80 79 ± 3

0.500 3 71, 77, 72 73 ± 3

Field corn

stover

0.050 3 92, 90, 86 89 ± 3

0.500 3 80, 90, 94 88 ± 7

Concurrent Recoveries

Field corn

grain

0.050 14 103, 72, 74, 77, 74, 84, 111, 75, 

111, 89, 96, 81, 111, 68

88 ± 16

5.00 14 84, 114, 98, 93, 92, 98, 104, 81, 

104, 100, 85, 98, 104, 98

97 ± 9

Field corn 

forage

0.050 11 88, 91, 71, 88, 104, 88, 78, 73, 

98, 88, 69

85 ± 11

5.00 11 96, 86, 88, 109, 94, 109, 95, 91, 

96, 109, 123

100 ± 11

Field corn

stover

0.050 14 94, 82, 78, 73, 95, 82, 71, 80, 84, 

90, 84, 80, 71, 80

82 ± 8

5.00 14 94, 94, 92, 88, 124, 128, 81, 110, 

83, 83, 83, 110, 81, 100

96 ± 16

25.0 2 83, 83 83*

* Standard deviation is not calculated for sample sets where n < 3. 

Based on recoveries of zeta-cypermethrin from method validation and/or laboratory-fortified 

control samples, the analytical methods demonstrated acceptable accuracy and precision for the 

matrices analyzed (see Tables 5.1.1.1 and 5.1.1.2, above). The recoveries were all within the 

generally recognized acceptable range of 70-120%, except for two from grain at 67 and 68%, 

one from forage at 123%, and two from stover at 124 and 128%. 

Conclusions: Adequate method validation data have been submitted on the GC/ECD and 

LC/MS/MS methods used for the determination of zeta-cypermethrin residues in field corn 

matrices from the field trial studies. No additional data are required in support of these data 

collection methods. 

5.1.2 Multi-Residue Methods (860.1360)

Residue Chemistry Summary Document D379486; E. Holman; 20 September 2012

The January 1994 Food and Drug Administration (FDA) PESTDATA database (PAM Volume I) 

indicates that residues of cypermethrin are completely recovered (>80%) using multiresidue 

method Sections 302 (Luke), 303 (Mills, Onley, and Gaither) and 304 (Mills fatty food). 
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5.1.3 Tolerance Enforcement Methods

Residue Chemistry Summary Document D379486; E. Holman; 20 September 2012

Adequate tolerance enforcement methods are available for determining residues of cypermethrin 

and zeta-cypermethrin in or on plant (Method I) and livestock (Method II) commodities. Both 

methods are GC/ECD methods, and have undergone successful Agency method validations. 

Method I has an LOD of 0.01 ppm, and Method II has LODs of 0.005 ppm in milk and 0.01 ppm 

in livestock tissues. These methods are not stereospecific; thus no distinction is made between 

residues of cypermethrin (all 8 stereoisomers), zeta-cypermethrin (enriched in 4 isomers) and 

alpha-cypermethrin (enriched in 2 isomers). The methods can be obtained from the Analytical 

Chemistry Branch of the Biological and Economic Analysis Division (ACB/BEAD). 

5.2 Storage Stability (860.1380)

MRIDs #47440501 and 49412201

The field corn grain, forage and stover samples from these studies were stored for durations of 

2.9 to 11 months, from the date of sampling to analysis. A previous frozen storage stability 

study conducted with cypermethrin sorghum grain, hay and green chop (MRID #43464001)

indicated that cypermethrin was stable for intervals of up to 36 months under frozen storage 

conditions. Thus, it can be concluded that zeta-cypermethrin was stable in field corn grain, 

forage and stover for the durations that the samples were held in frozen storage during these 

studies. 

TABLE 5.2 Summary of Storage Conditions. 

Matrix Storage Temperature

(°C)

Actual Storage 

Duration (Months)

1

Interval of Demonstrated 

Storage Stability (Months)

MRID #47440501

Field corn grain -18 10 362

Field corn forage 11

Field corn stover 10

MRID #49412201

Field corn grain -10 2.9 362

Field corn forage 3.6

Field corn stover 2.9

1. Storage duration between harvest and analysis. 

2. Storage stability data for sorghum grain, hay and green chop (MRID #43464001). 

Conclusions: There are no storage stability issues associated with the field corn field trial 

studies. Therefore, no corrections for potential decline during storage are needed in reviewing 

the residue studies submitted for zeta-cypermethrin in field corn grain, forage and stover. 
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5.3 Residue Data

5.3.1 Crop Field Trials (860.1500)

MRIDs #47440501 and 49412201

FMC has submitted data for 15 field trials with zeta-cypermethrin on field corn to determine the 

resulting residues in field corn grain, forage and stover. Two field trial studies were conducted, 

with one comprised of 2 trial sites, and the other comprised of 13 trial sites. The results of the 

studies are summarized below, and a summary of the residue data is presented in Table 5.3.1 

(below). 

MRID #47440501: Supervised field trials were conducted in 2002 at two locations in North 

American Free Trade Agreement (NAFTA) Growing Zone 5, with one trial in Illinois and the 

other in Nebraska. Fury 1.5 EC was applied at the IL trial, and Fury 1.5 EW was applied at the

NE trial. The trial sites consisted of an untreated plot which produced single composite samples, 

and one treated plot which yielded duplicate composite samples of grain, forage and stover. 

Each treated plot received 1 in-furrow application at a target rate of 0.05 lb ai/A, followed by 

either 2 broadcast foliar applications (forage) or three applications (grain and stover), each at 

0.05 lb ai/A, for total application rates of 0.15 lb ai/A to corn forage, and 0.20 lb ai/A to corn 

grain and stover. Applications were made in spray volumes of 2.4 to 10.9 gallons per acre 

(GPA), with no adjuvant. Samples were collected at a PHI of approximately 7 days. Because 

the forage samples from these trials were treated at the rate of only 0.15 lb ai/A, the forage 

results were not included in the current review. 

No residues of zeta-cypermethrin were detected in the control grain, forage or stover samples 

collected from the untreated plots, with the exception of several corn forage samples, with 

residues observed at 0.02 ppm (the LOD in corn forage ranged from 0.01 to 0.02 ppm). 

Residues of zeta-cypermethrin in field corn stover samples ranged from 0.42 to 0.92 ppm in 

samples collected 7 days after the last application. No residues were detected in grain samples 

from the study. 

MRID #49412201: Supervised field trials were conducted in 2013 at 13 locations in NAFTA 

Zones 1, 2, 5 and 6, representing major commercial field corn growing regions in the USA. At

7 of the trials, the treated plots received applications of Fury 1.5 EC, and at six of the trials, the 

treated plots received applications of Fury 1.5 EW. The trial sites consisted of an untreated plot 

which produced single composite samples, and 2 treated plots, one of which provided duplicate 

composite samples of forage, and the other for duplicate composite samples of grain and stover. 

Each treated plot received 4 foliar broadcast applications of zeta-cypermethrin at a target rate of 

0.05 lb ai/A per application, for a total application rate of 0.20 lb ai/A. Applications were made 

in spray volumes of 10.8 to 23.1 GPA, with no adjuvant. Samples were collected at a PHI of 

approximately 7 days. 
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No residues of zeta-cypermethrin were detected in the control grain, forage or stover samples 

collected from the untreated plots, with the exception of 2 samples having residues observed at 

non-quantifiable levels (<0.05 ppm) just above the LOD of 0.01 ppm. 

Residues of zeta-cypermethrin in field corn forage samples ranged from 0.683 to 7.09 ppm in 

samples collected 6-8 days after the last application. Residues of zeta-cypermethrin in field corn 

stover samples ranged from 0.215 to 17.6 ppm in samples collected 6-8 days after the last 

application. No residues were detected in grain samples from the study, with 5 exceptions not 

exceeding the LOQ (<0.05 ppm). 

TABLE 5.3.1 Summary of Residue Data from Field Corn Field Trials with Zeta-Cypermethrin (MRIDs

#47440501 and 49412201). 

Commodity Total Use Rate 

(lb ai/A)1

PHI 

(Days)

Residue Levels (ppm)

n

2 Min. Max. HAFT3 Median Mean Std. Dev.

Field corn grain 0.20 6-8 15 <0.05 <0.05 <0.05 0.05 0.05 0

Field corn forage 0.20 6-8 13 0.683 7.09 6.30 2.54 2.59 1.61

Field corn stover 0.20 6-8 15 0.215 17.6 15.9 3.61 4.76 4.39

1. Target application rate (4 x 0.05 lb ai/A). 

2. Except for sample min/max, values reflect per trial averages; n = number of field trials. For calculation of 

median, mean and standard deviation, the LOQ (0.05 ppm) was used for any results reported as <LOQ. 

3. HAFT = Highest Average Field Trial. 

Conclusions: The submitted field corn field trial data are adequate, and support an increase of

the established tolerance in field corn forage from 0.20 to 9.0 ppm, and an increase of the 

tolerances in field corn and popcorn stover from 3.00 to 30 ppm. 

5.3.2 Field Rotational Crops (860.1900)

Residue Chemistry Summary Document D379486; E. Holman; 20 September 2012

The HED Chemistry Chapter of the Cypermethrin RED (D289422; W. Donovan; 25 September 

2003) reported that adequate confined and limited field rotational crop studies are available for 

cypermethrin. The results of the limited field rotational crop study indicate that residues of 

cypermethrin and its metabolites were nondetectable (<0.01 ppm) in/on the rotational crop 

commodities of leafy vegetables, root and tuber vegetables, and cereal grain crops that were 

planted 30 days after the soil plots were treated with cypermethrin at 0.5 lb ai/A (1.7X the 

maximum seasonal rate). This study supports the labeled PBI of 30 days, and no additional 

rotational crop data are required for cypermethrin. This conclusion also applies to zetacypermethrin. 

5.3.3 Processed Food and Feed (860.1520)

Because there are no processed commodities associated with corn forage or stover, processing 

studies are not required for the current petition. 
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5.3.4 Meat, Milk, Poultry and Eggs (860.1480)

Residue Chemistry Summary Document D379486; E. Holman; 20 September 2012

OCSPP Residue Chemistry Test Guideline 860.1000, Table 1 Feedstuffs; ChemSAC; 30 June 2008

The increased tolerances in field corn forage, and field corn and popcorn stover, will not have an 

impact on the existing livestock commodity tolerances. These livestock commodity tolerances 

were established at levels determined largely due to the potential for residues in other 

commodities (trefoil hay and lespedeza hay) with higher tolerances, and which also constitute a 

greater percentage of the estimated livestock diet, based on the most recent EPA guidance on 

dietary feedstuffs (revised OCSPP Residue Chemistry Test Guideline 860.1000, Table 1 

Feedstuffs; ChemSAC; 30 June 2008). 

Conclusion: No changes to the existing tolerances in livestock commodities are required for the 

current petition.

5.3.5 Food Handling (860.1460)

There are no proposed uses that are relevant to this guideline topic.

5.3.6 Water, Fish and Irrigated Crops (860.1400)

There are no proposed uses that are relevant to this guideline topic

5.4 Food Residue Profile

The data submitted in support of the current action (PP#4F8290) along with previously reviewed 

data, are adequate for purposes of risk assessment and tolerance assessment for the proposed 

amended uses under review. Maximum residues of zeta-cypermethrin are expected to occur at 

moderate levels (up to 9.0 ppm in field corn forage, and up to 30 ppm in field corn and popcorn 

stover) from the shorter PHIs on field corn and popcorn proposed in the current petition. 

Zeta-cypermethrin residues (when above the LOQ) generally tend to decline or remain stable 

with increasing PHI, and do not increase to any significant degree. Following foliar applications, 

zeta-cypermethrin is present primarily as surface residues; translocation does not appear to be 

extensive. In general, zeta-cypermethrin residues do not tend to concentrate in processed 

fractions, other than via dehydration or from surface residues. 

Residues of zeta-cypermethrin are not expected to accumulate above the LOQ in rotational crops

planted at PBIs of 7 days following application of zeta-cypermethrin to primary crops.
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6.0 Tolerance Derivation

The recommended amended tolerances were derived by entering the submitted field corn field 

trial data into OECD’s tolerance calculation procedure. The rationale for the proposed 

amendment of the established tolerances in field corn forage, and field corn and popcorn stover,

is listed in Table 6.0, below. 

Instead of the proposed tolerances in field corn and popcorn stover (30.0 ppm), HED 

recommends establishing the tolerances at 30 ppm. The Agency establishes tolerances using 

whole numbers for tolerances of 10 ppm or more, per the OECD’s User Guide

ENV/JM/MONO(2011)2 for the OECD tolerance calculation procedure. 

Codex has not established MRLs in corn forage or stover. Codex MRLs are established for 

cypermethrin, which includes both alpha- and zeta-cypermethrin. Although the US and Codex 

residue definitions differ formally, they are effectively harmonized, since the toleranceenforcement methods are not stereo-specific, and thus do not distinguish between residues of 

cypermethrin, zeta-cypermethrin and alpha-cypermethrin. For enforcement purposes, the same 

moiety is being regulated. 

Canada’s PMRA does not establish MRLs in livestock feedstuffs, such as corn forage and stover. 

An International Residue Limit Status sheet is appended as Attachment 1. 

TABLE 6.0 Tolerance Recommendations for Zeta-Cypermethrin. 

Commodity Existing 

Tolerance (ppm)

Proposed Tolerance 

(ppm)

Recommended 

Tolerance (ppm)

Comments; Correct 

Commodity Definition

40CFR §180.418[a][2]

Corn, field, forage 0.20 9.0 9.0 Based on the submitted 

Corn, field, stover 3.00 30.0 30 field corn field trial data. 

Corn, pop, stover 3.00 30.0 30

References

Zeta-Cypermethrin. Petition to Amend (Increase) the Established Tolerances for the Insecticide 

in Alfalfa Hay and Forage. Summary of Analytical Chemistry and Residue Data.; D416982; 

W.T. Drew; 31 October 2014

Zeta-Cypermethrin. Petitions for Use on Tropical Fruit, Artichoke, Barley, Oat, Rye, 

Buckwheat, and Pistachio. Summary of Analytical Chemistry and Residue Data. Petition 

Numbers OE7717 and OE7804.; D379486; E. Holman; 20 September 2012. 
Zeta-Cypermethrin Summary of Analytical Chemistry and Residue Data DP Barcode D422801

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OECD MRL Calculator: User Guide; ENV/JM/MONO(2011)2; Organisation for Economic Cooperation and Development, Environment Directorate Joint Meeting of the Chemicals 

Committee and the Working Party on Chemicals, Pesticides and Biotechnology; 1 March 2011. 

Cypermethrin and Zeta-Cypermethrin -- Conclusions of the Meeting of Metabolism Assessment 

Review Committee (10/10/00).; D269584; Y. Donovan; 3 November 2000. 

Zeta-Cypermethrin - Human Health Risk Assessment for New Poultry House Use and 

Agricultural Uses on Tropical Fruit, Artichoke, Barley, Oat, Rye, Buckwheat, and Pistachio; 

D378897, D385242, D397298; E. Holman; 12 October 2012. 

Drinking Water Assessment for Zeta-Cypermethrin for New Food Use on Globe Artichoke, 

Barley, Buckwheat, Oats, Rye, Pistachio, Avocado, Papaya, Star Apple, Black Sapote, Mango, 

Sapodilla, Canistel, and Mamey Sapote. (Petition # 0E7717 and 0E7804); D378901, D385246; I. 

Maher; 22 February 2011. 

PP#9F6037. Request for the use of Zeta-cypermethrin on Sugar Beets, Sugarcane, Corn (Field , 

Seed, Pop), Green Onions. Cypermethrin Storage Stability and Residue Decline on Alfalfa (PP# 

4F4399). Metabolism of Cypermethrin in Sugar Beet. Evaluation of Analytical Chemistry and 

Residue Data.; D257955, D260798, D265459; W.D. Cutchin; 22 May 2001. 

Cypermethrin (PC Code 109702) HED Chemistry Chapter of the Reregistration Eligibility 

Decision (RED): Summary of Product and Residue Chemistry Residue Data. Reregistration 

Case 2130.; D289422; W. Donovan; 25 September 2003. 

Revisions of Feedstuffs in Table 1 of OPPTS Test Guideline 860.1000 and Guidance on 

Constructing Maximum Reasonably Balanced Diets (MRBD); ChemSAC; 30 June 2008. 

Attachments

Attachment 1: International Residue Limit Status sheet. 

Attachment 2: OECD Tolerance Assessment Calculations
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Attachment 1: International Residue Limit Status. 

Zeta-cypermethrin (PC Code 129064)

Summary of US Tolerances and International Maximum Residue Limits.

Residue Definitions

US (40CFR §180.418[a][2]) Canada Codex

Plants/livestock: Zeta-cypermethrin 

(S-cyano(3-phenoxyphenyl) methyl(±

cis-trans)-3-(2,2-dichloroethenyl)-2,2-

dimethylcyclopropanecarboxylate). 

(Canada does not establish MRLs in 

livestock feedstuffs.) 

Cypermethrin (sum of isomers). 

Commodity2 Tolerance 

(ppm)3

Commodity MRL 

(mg/kg)

Commodity MRL

(mg/kg)

Corn, field, forage 9.0

Corn, field, stover 30

Corn, pop, stover 30

Completed: W.T. Drew; 1 February 2015. 

1. Mexico adopts US tolerances, and/or Codex MRLs, for its export purposes. 

2. Includes only commodities of interest for this action. 

3. Tolerance values are those recommended by HED, not those proposed by the petitioner. 
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Attachment 2: OECD Tolerance Assessment Calculations

Field Corn Forage

0.829

4.320

4.605

2.570

2.590

2.535

6.295

1.240

2.725

1.290

1.950

1.725

0.967

Zeta-cypermethrin

Field Corn Forage

USA

0.20 lb ai/A, 7-day PHI

Total number of data (n) 13

Percentage of censored data 0%

Number of non-censored data 13

Lowest residue 0.829

Highest residue 6.295

Median residue 2.535

Mean 2.588

Standard deviation (SD) 1.613

Correction factor for censoring (CF) 1.000

Proposed MRL estimate

- Highest residue 6.295

- Mean + 4 SD 9.038

- CF x 3 Mean 7.763

Unrounded MRL 9.038

Rounded MRL 9
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Field Corn Stover

11.775

8.755

15.900

3.305

2.215

4.045

1.530

3.610

5.020

0.319

3.190

4.150

6.440

0.730

0.480

Zeta-cypermethrin

Field Corn Stover

USA

0.20 lb ai/A, 7-day PHI

Total number of data (n) 15

Percentage of censored data 0%

Number of non-censored data 15

Lowest residue 0.319

Highest residue 15.900

Median residue 3.610

Mean 4.764

Standard deviation (SD) 4.393

Correction factor for censoring (CF) 1.000

Proposed MRL estimate

- Highest residue 15.900

- Mean + 4 SD 22.335

- CF x 3 Mean 14.293

Unrounded MRL 22.335

Rounded MRL 30