Paraquat Dichloride Summary of Analytical Chemistry and Residue Data Barcode: 381971



### 3 of 14 General tolerances have been established under 40CFR§180.205 (a), and range from 0.01 ppm for

egg and milk to 210 ppm for Animal feed, non grass, group 18, hay . Tolerances with regional

registration have been established under 40CFR§180.205 (c) at 0.05 ppm for cassava, pigeon pea

seed, tanier, tyfon, and true yam, and at 0.1 ppm for taro corm.

The qualitative nature o f paraquat residues in plant commodities is understood based upon

studies depicting the metabolism of paraquat in carrots and lettuce following preemergence

treatment and in potatoes and soybeans following desiccant treatment. The residue of concern in

pl ants is the parent, paraquat. The qualitative nature of residues in livestock is adequately

understood based on the combined results of studies conducted with ruminants (goats and cows),

swine, and poultry. The residue of concern in eggs, milk, and poult ry and livestock tissues is

also parent paraquat.

An adequate spectrophotometric method, Method I of the Pesticide Analytical Manual (PAM)

Vol. II, is available for enforcing tolerances for residues of paraquat in/on plant commodities.

For the method, sa mples are heated at reflux with 0.5 M sulfuric acid and then applied to a cation

exchange column . P araquat residues are eluted with saturated ammonium chloride solution.

Cotton seed samples are first subjected to Soxhlet extraction in hexane

, and the hex ane extract is

refluxed with sulfuric acid and then applied to the cation exchange column. An aliquot of the

column eluate is mixed with 0.2% (w/v) sodium hydrosulfite in 0.3 M sodium hydroxide, which

reduces paraquat to a free radical. Residues are dete rmined using a variable wavelength

spectrophotometer, measuring the light absorption of the paraquat free radical. The validated

limits of quantitation (LOQ) vary from 0.01 ppm up to 0.5 ppm.

PAM Vol. II lists a spectrophotometric method, designated as M ethod Ia (LOD = 0.005 ppm), as

available for the enforcement of tolerances for paraquat residues in animal commodities. In

addition, an adequate HPLC/UV method is available for the enforcement of tolerances for

paraquat residues in livestock tissues and e ggs (RAM 004/04, MRID 43226902; this method has

not yet been published in P AM Vol. II); the reported LOQ is 0.005 ppm for livestock tissues and

eggs.

Adequate storage stability data are available indicating that residues of paraquat are stable under

froz en storage conditions in/on representative examples of the following crop groups for at least

18 months: non

- oily grains , including corn grain; leafy vegetables , including corn forage, fodder,

and silage ; root crops ; and fruits or fruiting vegetables. In addition, residues of paraquat have

been found to be stable in/on cantaloupe stored frozen for up to 3.7 months, cucumber stored

frozen for up to 4.0 months, summer squash stored frozen for up to 2.6 months, ginger root

stored frozen for up to 2.4 months

, and okra pod stored frozen for up to 7.3 months. It was

previously concluded that storage stability data for corn grain may be translated to oilseeds.

T he available ruminant and poultry feeding study data indicate that the tolerance

recommendations of the RED Document (8/97) are appropriate

, and that increased tolerances for

livestock commodities are not needed to support the requested new uses.Paraquat Dichloride Summary of Analytical Chemistry and Residue Data Barcode: 381971



### 4 of 14 The r esidue c hemistry c hapter of the RED (D217262, D. Miller, 7/28/95) concluded that no

plantback restri ctions or field rotational crop studies are required for paraquat based on a n

acceptable confined rotational crop study

.

Regulatory Recommendations and Residue Chemistry Deficiencies

Pending the submission of a revised Section F, t here are no residue chemistry issues that would

preclude granting a registration for paraquat on perennial tropical and sub

- tropical fruit trees ; or

establishment of tolerances for residues of paraquat, as follows:

Tolerances to be established under 40 CFR § 180.205(a):

Atemoya

................................ ................................ ................................ ............................... 0.05 ppm

Biriba

................................ ................................ ................................ ................................ .... 0.05 ppm

Canistel

................................ ................................ ................................ ................................ . 0.05 ppm

Cherimoya

................................ ................................ ................................ ............................ 0.05 ppm

Custard Apple

................................ ................................ ................................ ....................... 0.05 ppm

Feijoa

................................ ................................ ................................ ................................ .... 0.05 ppm

Ilama

................................ ................................ ................................ ................................ ..... 0.05 ppm

Jaboticaba

................................ ................................ ................................ ............................. 0.05 ppm

Longan

................................ ................................ ................................ ................................ .. 0.05 ppm

Lychee

................................ ................................ ................................ ................................ .. 0.05 ppm

Mango

................................ ................................ ................................ ................................ .. 0.05 ppm

Pawpaw

................................ ................................ ................................ ................................ 0.05 ppm

Pomegranate

................................ ................................ ................................ ......................... 0.05 ppm

Pulasan

................................ ................................ ................................ ................................ . 0.0 5 ppm

Rambutan

................................ ................................ ................................ .............................. 0.05 ppm

Sapodilla

................................ ................................ ................................ ............................... 0.05 ppm

Sapote, black

................................ ................................ ................................ ........................ 0.05 ppm

Sapote, mamey

................................ ................................ ................................ ..................... 0.05 ppm

Sapote, white

................................ ................................ ................................ ........................ 0.05 ppm

Soursop

................................ ................................ ................................ ................................ . 0.05 ppm

Spanish lime

................................ ................................ ................................ ......................... 0.05 ppm

Star apple

................................ ................................ ................................ .............................. 0.05 ppm

Starfruit

................................ ................................ ................................ ................................ . 0.05 ppm

Sugar apple

................................ ................................ ................................ ........................... 0.05 ppm

Wax jambu

................................ ................................ ................................ ........................... 0.05 ppm



### 860.1550 Proposed Tolera nces

The proposed tolerances should be revised to reflect the correct commodity definitions as

specified in Table 11

.

860.1200 Directions for Use

The petitioner needs to propose maximum seasonal rates for perennial tropical and sub

tropical fruit trees. The proposed maximum seasonal rate must reflect the total of all

types of applications. The available data will support the following maximum seasonal

rates: 3.76 lb ai/A.Paraquat Dichloride Summary of Analytical Chemistry and Residue Data Barcode: 381971



### 5 of 14 Background

IR

- 4 has submitted a petit ion (PP# 0E7748 ) to support uses on pere nnial tropical and sub

- tropical

fruit trees. The PC Code, nomenclature, and chemical structure of paraquat are listed below in

Table 1. The physicochemical properties of paraquat are listed in Table 2.

Table 1. Nomenclature of Paraquat Dichloride

.

C ompound

Common name Paraquat dichloride

IUPAC name 1,1’

- dimethyl

- 4,4’

- bypyridinium dichloride

CAS name 1,1’

- dimethyl

- 4,4’

- bypyridinium dichloride

CAS registry number 1910

- 42

- 5

(4685

- 14

- 7 for the cation)

End

- use product (EP) 2.0 lb paraquat cation/ga l SC (Gramoxone Inteon; EPA Reg. No. 100

- 1217)

Table 2. Physicochemical Properties of Technical Grade Paraquat Dichloride.

Parameter Value Reference

Melting point/range decomposes at ca. 340 °C Product Chemistry Chapter

of the Paraquat Dichloride

Upda te, 10/10/91 pH 6.4 at 20 °C

Density 1.5 g/cm 3 at 25 °C

Water solubility (20 °C) freely soluble in water:

618

- 620 g/L at pH 5.2, 7.2, and 9.2

Solvent solubility (20 °C) <0.1 g/L in acetone, dichloromethane,

toluene, ethyl acetate, and hexane;

143 g /L in methanol

Vapor pressure <<10

- 8 kPa at 25 °C

Octanol/water partition coefficient,

Log(K OW ) log K OW =

- 4.5 at 20 °C

Dissociation constant, pK

a 0.95 (pure active ingredient) Product Chemistry Chapter

of the Paraquat

Reregistration Standard,

11/25/ 85

UV/visible absorption spectrum Not availableParaquat Dichloride Summary of Analytical Chemistry and Residue Data Barcode: 381971



### 6 of 14 860.1200 Directions for Use

IR

- 4 has submitted copies of the registered label for a 2.0 lb paraquat cation/gal soluble

concentrate (SC) formulation of paraquat dichloride (Gramoxone Inteon; EPA Reg. N o. 100

-

1217 )

. The product proposed for amended use i s presented in Table 3 below

, and the proposed

new use directions are presented in Table 4.

Table 3. Summary of Proposed End

- Use Product.

Trade Name Reg.

No. ai (% of

formulation) Formula

tion Type Target Crops Target Pests Label Date

Gramoxone

Inteon 100

-

1217 2 lb

paraquat

cation/gal SC A variety of

food/feed crops . A variety of small

annual weeds

(broadleaves and

grasses), and

perennial weeds; also

used as a harvest aid

and desiccant. Proposed

s upplemental label

+ registered label

Table 4. Summary of Proposed Directions for Use of Gramoxone Inteon (100

- 1217).

Application Timing Application

Rate

(lb ai/A) Max. No.

Applic.

per

Season RTI 1

(days) Max.

Seasonal

Applic. Rate

(lb ai/A) PHI

(days) U se Directions and other

Limitations

Perennial Tropical and Sub

- tropical Fruit Trees (atemoya, biriba, black sapote, canistel, cherimoya, custard apple,

feijoa, ilama, jaboticaba, longan, lychee, mamey sapote, mango, pawpaw, pomegranate, pulasan, rambutan,

sapodilla, soursop, Spanish lime, star apple, starfruit, sugar apple, wax jambu, white sapote)

Postemergence

directed spray 0. 63

- 0. 94 4 28 NS 14 Applications are to be

directed between rows

and made using ground

equipment in a minimum

of 10 gal/A. May be tank

mixed with other

postemergence directed

herbicides. Do not graze

treated area. Do not feed

cover crops grown in

treated areas to livestock.

1 RTI = Retreatment intervalParaquat Dichloride Summary of Analytical Chemistry and Residue Data Barcode: 381971



### 7 of 14 The supplemental label specifies that preemergence applications must be m ade prior to crop

emergence and that postemergence applications (other than harvest aid or defoliation

applications) should be made without contact to the crop. Intentional or accidental contact

(including drift) with the crop may result in severe damage or loss of the crop.

The current product label prohibits application through any type of irrigation system . Preplant

and postemergence applications are not to be made to soils lacking clay minerals ( i.e. , peat,

muck, pure sand, and artificial planting me dia), and applications should always be made with

either a nonionic surfactant or crop oil concentrate. The product may be tank mixed with

photosynthetic inhibitor (PSI) herbicides at the use rates, limitations, etc. specified on the

respective label s . A ll rotational crops may be planted immediately after the last application.

Conclusion s

. The proposed use directions are adequate to allow evaluation of the available

residue data relative to the proposed use.

860.1300 Nature of the Residue

- Plants

The r esidue c hemistry c hapter of the RED (D217262, D. Miller, 7/28/95) concluded that

, f or the

purposes of reregistration and risk assessment, the qualitative nature of the residue in plants is

adequately underst ood based on studies depicting the metabolism of paraquat in carrots and

lettuce following preemergence treatment and in potatoes and soybeans following desiccant

treatment. The residue of concern in plants is parent paraquat.

860.1300 Nature of the Resi due

- Livestock

The r esidue c hemistry c hapter of the RED (D217262, D. Miller, 7/28/95) concluded that f or

purposes of reregistration and risk assessment, the qualitative nature of the residue in animals is

adequately understood based on the combined results of studies conducted with ruminants (goats

and cows), swine, and poultry. The residue of concern in eggs, milk, and poultry and livestock

tissues is parent paraquat.

860.1340 Residue Analytical Methods

Plant commodity method

PA M Vol. II lists a spectrophotometric method, designated as Method I (LOD = 0.01

- 0.06 ppm),

as available for the enforcement of tolerances in plant commodities. Several modifications of

Method I have been developed for analysis of specific crops, and these modified methods have

been used for data collection.

The RED Document ( EPA 738

- F

- 96

- 018, 8/ 97) reported that radiovalidation data had been

provided for Method 1B of the enforcement method using radiolabeled samples. The Agency

tentatively concluded th at Method 1B adequately recovers paraquat cation residues from samples

of potat oes and soybeans treated with [ 14 

### C]paraquat. At the time of the RED document, t he

registrant ha d recently submitted representative spectra and other supporting raw data from th e

radiovalidation study (MRID 43954002). I t was concluded that

, upon the Agency’s review ofParaquat Dichloride Summary of Analytical Chemistry and Residue Data Barcode: 381971



### 8 of 14 this additional information, the requirements for residue analytical methods for plant

commodities would be considered fulfilled for reregistration purposes. HED has not conducted a

formal review of the data. A preliminary review has been conducted, however, and the data are

considered to be adequate for the purposes of these tolerance petitions.

Conclusions

. The existing spectrophotometric method (Method I of P AM Vol. II) is adequate for

collecting data on residues of paraquat in/on plant commodities. The method is adequate for

tolerance enforcement purposes for these commodities.

Animal commodity method

PAM Vol. II lists a spectrophotom etric method, designated as Method Ia (LOD = 0.005 ppm), as

being available for the enforcement of tolerances in animal commodities. The registrant has

submitted descriptions and adequate independent laboratory validation data for a high

performance liqui d chromatography method (HPLC; designated as Method 4B) to determine

paraquat residues in animal tissues and eggs. The method has been validated by the Analytical

Chemistry Branch (ACB) . T he registrant wa s reque ste d to make minor changes in the method

wr ite

- up. A revised version of the method has been submitted (RAM 004/04; MRID 43226902)

and is now available for enforcement purposes

. The reported LOQ is 0.005 ppm for livestock

tissues and eggs

.

860.1360 Multiresidue Methods

The FDA PESTDATA database (dated 11/01 ) does not have an entry for paraquat. The r esidue

c hemistry c hapter of the RED (D217262, D. Miller, 7/28/95) concluded that the existing FDA

multiresidue methods are not likely to recover residues of paraquat because of i ts ionic nature.

860.1380 Storage Stability

This guideline is not relevant to the current petition.

860.1400 Water, Fish, and Irrigated Crops

This guideline is not relevant to the current petition.

860.1460 Food Handling

This guideline is not relev ant to the current petition.

860.1480 Meat, Milk, Poultry, and Eggs

This guideline is not relevant to the current petition.Paraquat Dichloride Summary of Analytical Chemistry and Residue Data Barcode: 381971



### 9 of 14 860.1500 Crop Field Trials

No residue field trial data have been submitted for this petition.

The following was taken from the minutes of the 10/1/2008 ChemSAC meeting.

3. Paraquat on Tropical Fruits (IR

- 4 via M. Doherty):

IR

- 4 is requesting that EPA allow tolerances and registrations on all perennial tropical fruit crops

b ased on surrogate data and current registrations. Spec ifically, IR

- 4 requests 0.05 ppm tolerances

and registrations for the following perennial tropical and semi

- tropical fruit trees: sugar apple,

cherimoya, atemoya, custard apple, ilama, soursop, birba, lychee, longan, Spanish lime,

rambutan, pulasan, star a pple, black sapote, mango, sapodilla, canistel, mamey sapote, feijoa,

jaboticaba, wax jambu, starfruit (carambola), pawpaw, pomegranate, and white sapote.

The proposed use pattern for the perennial tropical fruit crops will be the same as for the

followi ng currently labeled perennial crops : avocado, acerola, banana, papaya, guava, coffee,

tree nuts, fig, citrus fruit, pome fruit, olive, persimmon, and stone fruit (Gramoxone label), which

all have a tolerance of 0.05 ppm.

Pa ssionfruit, a tropical fruit crop, is an exception with a tolerance of 0.2 ppm. Passionfruit

differs from the rest in that it is a vine which drops ripe fruit to the ground; much of the fruit is

harvested by picking it up off the ground.

The ChemSAC had no objection to the propos al.

860.1520 Processed Food and Feed

This guideline is not relevant to the current petition.Paraquat Dichloride Summary of Analytical Chemistry and Residue Data Barcode: 381971



### 10 of 14 860.1650 Submittal of Analytical Reference Standards

The registrant must submit paraquat dichloride a nalytical refe rence standards when required to :

Theresa M. Cole

US EPA National Pesticide Standard Repository

Environmental Science Center

701 Mapes Road

Fort Meade, MD 20755

- 5350

Cole.Theresa@epa.gov

(410) 305

- 2907

An analytical standard for paraquat dichloride is c urrently available in the National Pesticide

Standards Repository ( Charles Stafford , electronic communication

, 3 /2 2 / 20 11 ).

860.1850 /1900 Confined /Field Accumulation in Rotational Crops

This guideline is not relevant to the current petition.

860.1550 P roposed Tolerances

HED previously determined that the residue of concern for paraquat in/on plant and animal

commodities is paraquat per se (D217262, D. Miller, 7/28/95) . Because there are currently no

registered products containing paraquat dimethyl sulfate, the tolerance expression listed under 40

CFR § 180.205(a) and § 180.205(c) should be revised to remove reference to the bis(methyl

sulfate) salt of paraquat.

In 2009 HED issued guidance on tolerance expressions (S. Knizner, 2009 ). We now conclude

the tolerance expression should be as follows: Tolerances are established for residues of

paraquat, including its metabolites and degradates, in or on the commodities in the table below.

Compliance with the tolerance levels specified b elow is to be determined by measuring only

paraquat dichloride and calculated as the paraquat cation.

A summary of the recommended tolerances for the current petition is given in Table 6

.

The proposed tolerances should be revised to reflect the correct commodity definitions as

specified in Table 6

.Paraquat Dichloride Summary of Analytical Chemistry and Residue Data Barcode: 381971



### 11 of 14 Table 6

. Tolerance Summary for Paraquat Dichloride

Commodity Tolerance (ppm) Comments ( correct commodity

definition ) Established Proposed Recommended

Tolerances to be established under 40 CFR ' 180. 20 5 (a) :

Atemoya

-- 0.05 0.05

Biriba

-- 0.05 0.05

Black sapote

-- 0.05 0.05 Sapote, black

Canistel

-- 0.05 0.05

Cherimoya

-- 0.05 0.05

Custard apple

-- 0.05 0.05

Feijoa

-- 0.05 0.05

Ilama

-- 0.05 0.05

Jaboticaba

-- 0.05 0.05

Longan

-- 0.05 0.05

Lychee

-- 0.05 0.05

Mamey sapote

-- 0.05 0.05 Sapote, mamey

Mango

-- 0.05 0.05

Pawpaw

-- 0.05 0.05

Pomegranate

-- 0.05 0.05

Pulasan

-- 0.05 0.05

Rambutan

-- 0.05 0.05

Sapodilla

-- 0.05 0.05

Soursop

-- 0.05 0.05

Spanish lime

-- 0.05 0.05

Star apple

-- 0.05 0.05

Starfruit

-- 0.05 0.05

Sugar apple

-- 0.05 0.05

Wax jambu

-- 0.05 0.05

White sapote

-- 0.05 0.05 Sapote, white



### Codex/International MRL Harmonization

The Codex Alimentarius Commission has esta blished several maximum residue limits (MRLs)

for paraquat residues in various commodities. The Codex and U.S. tolerance s are in harmony

with respect to MRL/tolerance expression; both regulate the parent paraquat cation only. The

Agency cannot harmonize with the Codex MRL of 0.01 ppm since some commodities which the

proposed US tolerance is translated from contained residues of > 0.01 ppm. A comparison of the

Codex MRLs and the proposed U.S. tolerances is presented in the following table

. To the extent

possible, U.S. tolerances have been harmonized with Codex, Canadian, and Mexican MRLs.

No Canadian or Mexican MRLs have been established for paraquat. R egistered food/feed uses

of paraquat exist in Canada . T hese uses presumably fall under the PMRA Ge neral MRL of 0.1

mg/kg

. Regulation B.15.002(1) of the Canadian Food and Drugs Regulations (FDR) establishes

0.1 ppm as the General Maximum Residue Limit. This regulation states that a food is adulteratedParaquat Dichloride Summary of Analytical Chemistry and Residue Data Barcode: 381971



### 12 of 14 if it contains residues of a pesticide at a level greater than 0.1 ppm unless a specific MRL has

been established in Table II, Division 15 of the FDR.Paraquat Dichloride Summary of Analytical Chemistry and Residue Data Barcode: 381971



### 13 of 14 

## International Residue Limits

Paraquat Dichloride (060601; 3/9/2011)

Summary of US and International Tolerances and Maximum Residue Limits

Residue De

finition :

US Canada Mexico 2 Codex 3

40 CFR 180.205:

Plant: paraquat (1,1′

- dimethyl

- 4,4′

- bipyridinium

- ion) derived from application of

either the bis(methyl sulfate) or the dichloride

salt (both calculated as the cation) None Paraquat cation

Commodity 1 Tolerance (ppm) /Maximum Residue Limit (mg/kg)

US Canada Mexico 2 Codex

Atemoya 0.05 0.01 (*) Assorted tropical and

subtropical fruits

- inedible peel

(Includes all except

- Atemoya,

Biriba, Jaboticaba, Starfruit

and Wax Jambu).

Biriba 0.05

Black sap ote 0.05

Canistel 0.05

Cherimoya 0.05

Custard apple 0.05

Feijoa 0.05

Ilama 0.05

Jaboticaba 0.05

Longan 0.05

Lychee 0.05

Mamey sapote 0.05

Mango 0.05

Pawpaw 0.05

Pomegranate 0.05

Pula san 0.05

Rambutan 0.05

Sapodilla 0.05

Soursop 0.05

Spanish lime 0.05

Star apple 0.05

Starfruit 0.05

Sugar apple 0.05

Wax jambu 0.05

White sapote 0.05

Completed: M. Negussie; 3/10/2011

1 Includes only commodities of interest for this action. Tolerance values should be the HED recommendations and

not those proposed by the applicant.

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

3 * = absent at the limit of quantitation; Po = postharvest tr eatment, 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 beParaquat Dichloride Summary of Analytical Chemistry and Residue Data Barcode: 381971



### 14 of 14 References

Paraquat Dichloride. (061601) Product Chemistry Chapter and Residue Chemistry Chapter for

the Reregistration Eligibility Document: CBRS No. 15906; Rereg. Case No. 0262 , D217262,

D. Miller

, 7/2 8 /95