9

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON D.C., 20460

OFFICE OF 

PREVENTION, PESTICIDES AND 

TOXIC SUBSTANCES

Date: JULY-13-2005

MEMORANDUM

SUBJECT: Pinoxaden: Human Health Risk Assessment for New Active Ingredient; First

Uses Proposed on Wheat and Barley. PC Code:147500. DP#310864,

DP#311624. PP# 4F6817.

Regulatory Action: Section 3/New Active Ingredient

Risk Assessment Type: Single Chemical Aggregate

FROM: Mary Clock-Rust, Biologist, Risk Assessor

Mark I. Dow, Ph.D., Biologist

William Greear, Toxicologist

Mohsen Sahafeyan, Chemist

Registration Action Branch 1 (RAB1)/Health Effects Division (HED)

THROUGH: PV Shah, Ph.D., Branch Senior Scientist

RAB1/HED

TO: Hope Johnson, PM Team Reviewer

Herbicide Branch (HB)/Registration Division (RD)

Syngenta has submitted a petition for the establishment of permanent tolerances for residues of

pinoxaden and its metabolites, NOA 407854 (M2), SYN 505164 (M4), SYN 502836 (M6) in/on

wheat and barley.

The HED of the Office of Pesticide Programs (OPP) is charged with estimating the risk to

human health from exposure to pesticides. The RD of OPP has requested that HED evaluate

hazard and exposure data and conduct dietary, occupational, residential and aggregate exposure

assessments, as needed, to estimate the risk to human health that will result from the proposed

uses of pinoxaden on wheat and barley.

A summary of the findings and an assessment of human risk resulting from the proposed uses of

pinoxaden is provided in this document. The risk assessment was provided by Mary Clock-Rust

(RAB1), the residue chemistry review and dietary exposure assessment were provided by
2

Mohsen Sahafeyan (RAB1), the hazard characterization was provided by William Greear

(RAB1), the occupational/residential exposure assessment was provided by Mark Dow (RAB1),

and the drinking water assessment was provided by Ibrahim Abdel-Saheb of the Environmental

Fate and Effects Division (EFED).
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Table of Contents

1.0 Executive Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

2.0 Ingredient Profile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

2.1 Summary of Registered/Proposed Uses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

2.2 Structure and Nomenclature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

2.3 Physical and Chemical Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

3.0 Metabolism Assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

3.1 Comparative Metabolic Profile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

3.2 Nature of the Residue in Foods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

3.2.1. Description of Primary Crop Metabolism . . . . . . . . . . . . . . . . . . . . . . . . 14

3.2.2 Description of Livestock Metabolism . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

3.2.3 Description of Rotational Crop Metabolism, including identification of

major metabolites and specific routes of biotransformation . . . . . . . . . . 15

3.3 Environmental Degradation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

3.4 Summary of Major Residues in Metabolism Studies for Pinoxaden . . . . . . . . . . 16

3.5 Toxicity Profile of Major Metabolites and Degradates . . . . . . . . . . . . . . . . . . . . 17

3.6 Summary of Residues for Tolerance Expression and Risk Assessment . . . . . . . 20

3.6.1 Tabular Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

3.6.2 Rationale for Inclusion of Metabolites and Degradates . . . . . . . . . . . . . . 20

4.0 Hazard Characterization/Assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

4.1 Hazard Characterization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

4.2 FQPA Hazard Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

4.2.1 Adequacy of the Toxicity Data Base . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

4.2.2 Evidence of Neurotoxicity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

4.2.3 Developmental Toxicity Studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

4.2.4 Reproductive Toxicity Study . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

4.2.5 Additional Information from Literature Sources . . . . . . . . . . . . . . . . . . . 37

4.2.6 Pre-and/or Postnatal Toxicity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

4.2.6.1 Determination of Susceptibility . . . . . . . . . . . . . . . . . . . . . . . . . . 37

4.2.6.2 Degree of Concern Analysis and Residual Uncertainties for Pre

and/or Post-natal Susceptibility . . . . . . . . . . . . . . . . . . . . . . . . . . 37

4.3 Recommendation for a Developmental Neurotoxicity Study . . . . . . . . . . . . . . . 37

4.4 Hazard Identification and Toxicity Endpoint Selection . . . . . . . . . . . . . . . . . . . 38

4.4.1 Acute Reference Dose (aRfD) - Females age 13-49 . . . . . . . . . . . . . . . . . 38

4.4.2 Acute Reference Dose (aRfD) - General Population . . . . . . . . . . . . . . . . 38

4.4.3 Chronic Reference Dose (cRfD) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

4.4.4 Incidental Oral Exposure (Short and Intermediate Term) . . . . . . . . . . . . 39

4.4.5 Dermal Absorption . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

4.4.6 Dermal Exposure (Short, Intermediate and Long Term) . . . . . . . . . . . . . 40

4.4.7 Inhalation Exposure (Short, Intermediate and Long Term) . . . . . . . . . . . 40

4.4.8 Margins of Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

4.4.9 Recommendation for Aggregate Exposure Risk Assessments . . . . . . . . 41

4.4.10 Classification of Carcinogenic Potential . . . . . . . . . . . . . . . . . . . . . . . . . 41
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4.5 Special FQPA Safety Factor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

4.6 Endocrine Disruption . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

5.0 Public Health Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

6.0 Exposure Characterization/Assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

6.1 Dietary Exposure/Risk Pathway . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

6.1.1 Residue Profile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

6.1.2 Acute and Chronic Dietary Exposure and Risk . . . . . . . . . . . . . . . . . . . . 47

6.2 Water Exposure/Risk Pathway . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

6.3 Residential (Non-Occupational) Exposure/Risk Pathway . . . . . . . . . . . . . . . . . . 50

6.3.1 Spray Drift . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

7.0 Aggregate Risk Assessments and Risk Characterization . . . . . . . . . . . . . . . . . . . . . . . . 50

7.1 Acute Aggregate Risk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

7.2 Short-Term Aggregate Risk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

7.3 Intermediate-Term Aggregate Risk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

7.4 Long-Term (Chronic) Aggregate Risk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

7.5 Aggregate Cancer Risk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

8.0 Cumulative Risk Characterization/Assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

9.0 Occupational Exposure/Risk Pathway . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

9.1 Short-/Intermediate-/Long-Term Handler Risk . . . . . . . . . . . . . . . . . . . . . . . . . . 52

9.2 Short/Intermediate/Long-Term Postapplication Risk . . . . . . . . . . . . . . . . . . . . . 54

9.3 Occupational Handler and Postapplication Cancer Risk . . . . . . . . . . . . . . . . . . . 55

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

Appendix 1. Toxicological Data Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

Appendix 2. Non-Critical Toxicology Studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

Appendix 3. Metabolism Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93

Appendix 4. Dissenting Opinion of the Hazard Assessment . . . . . . . . . . . . . . . . . . . . . . . . . . 128
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1.0 Executive Summary

Background

Pinoxaden is a new post-emergence herbicide for control of grass weeds in wheat (including durum)

and barley. The proposed product is NOA 407855 100 emulsifiable concentrate (EC). The

proposed use of pinoxaden is one application per crop season at a rate of 0.036 -0.062 lb active

ingredient (a.i.)/acre with a pre-harvest interval (PHI) of 60 days and restricted-entry interval

(REI) of 48 hours. The petitioner proposes a zero-day plant back interval (PBI) for wheat and

barley and 30-day PBI for other crops. A 30-day pre-grazing interval is also included on the

label.

Pinoxaden (NOA 407855) is a representative of the new phenylpyrazolin class of chemicals. 

The mode of action is the inhibition of the enzyme, acetyl-coenzyme A carboxylase (ACCase).

ACCase activity in plants can be attributed to two isoenzymes located in different compartments

of the plant cell, the chloroplast and the cytosol. The chloroplastic enzyme is responsible for the

de novo biosynthesis of all fatty acids in the cell. The malonyl-coenzyme A produced by the

cytosolic ACCase is required for fatty acid elongation to form very long-chain fatty acids, and

for the biosynthesis of flavonoids and malonylated metabolites. Pinoxaden has been found to

inhibit both the chloroplastic and the cytosolic ACCase enzyme in gramineae. 

This risk assessment is a joint review with the Pesticide Management Regulatory Agency

(PMRA) of Health Canada and HED.

 

There are no existing tolerances, registered uses (including agricultural or residential uses) or

exemptions for pinoxaden.

Hazard Characterization

Pinoxaden has a low order of acute toxicity by the oral, dermal and inhalation routes (Toxicity

Categories III or IV). Pinoxaden is irritating to the eye, but is not irritating to the skin. 

Pinoxaden is not a skin sensitizer. In the subchronic and chronic toxicity study in rats, mice and

dogs, food consumption (or food efficiency-mice), body weight and body weight gain were the

parameters that were most often affected. In addition, rats and mice often showed kidney effects

such as renal tubular basophilia and alterations in urinalysis parameters. In the subchronic rat

studies, increased water consumption, increased urine volume and kidney effects were observed. 

In the subchronic mouse study, one also observed piloerection. In the subchronic dog study,

there was fluid feces, vomit, pale and thin appearance, decreased activity, dehydration, cold to

touch, and regurgitation, in addition to the decreases in body weight, body weight gain and food

consumption. In the chronic toxicity study in dogs, no systemic toxicity was observed at the

highest dose tested (HDT; 125 mg/kg/day). 

Carcinogenicity was not observed in the rat chronic toxicity/carcinogenicity study. The two

carcinogenicity studies in mice (1 via gavage; 1 dietary) were considered to be inadequate for

evaluating carcinogenic potential of pinoxaden in mice. The increased mortality resulting from

gavage error together with lung involvement confounded the results of the gavage

carcinogenicity study in mice. The dosing in the dietary study in mice was considered to be

inadequate due to the lack of toxicity in animals at the highest dose tested. HED concluded that

a new cancer study is not needed. 
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The critical adverse-effect for the overall risk assessment is based on the effects seen in the

rabbit developmental toxicity study. Effects observed included morbid condition in one rabbit

(mortality), early resorptions, postimplantation loss, abortion, decreased body weights, body

weight gains and food consumption. The rabbit is the most sensitive species. 

Pinoxaden was not neurotoxic in the acute or the subchronic rat neurotoxicity studies. No

quantitative or qualitative evidence of increased susceptibility was seen following in utero

exposure to rats or rabbits in developmental studies or in the reproduction study. Pinoxaden was 

mutagenic in two in vitro mammalian cytogenetic tests using V79 Chinese Hamster lung

fibroblasts cells, but negative in an in vivo mammalian cytogenetics (micronucleus) test. 

Pinoxaden was negative in bacterial and mammalian gene mutation tests and in two unscheduled

DNA synthesis (UDS) assays. Pinoxaden was considered to be non-mutagenic based on the

overall weight-of-evidence. One metabolite, M3, produced decreases in body weight, body

weight gain and food consumption in a 90-day feeding study in rats. It was also hepatotoxic in

both sexes and nephrotoxic in males. No evidence of mutagenicity was observed with M3 when

tested in an in vitro bacterial gene mutation assay, in an in vitro mammalian gene mutation

assay, in an in vivo (micronucleus) mammalian cytogenetics assay or in an unscheduled DNA

synthesis (UDS) assay. However, M3 was positive in an in vitro human lymphocyte

cytogenetics assay with and without S9-metabolic activation. In a 90-day feeding study in rats,

metabolite M6 produced no toxic effects at the highest dose tested of 978 and 1035 mg/kg/day

(limit dose) in male and female rats, respectively. No evidence of mutagenicity was observed

with M6 when tested in an in vitro bacterial gene mutation assay, in an in vitro mammalian gene

mutation assay or in an in vitro mammalian cytogenetics assay. No evidence of mutagenicity

was observed with M10 when tested in an in vitro bacterial gene mutation assay, in an in vitro

mammalian gene mutation assay, in both in vitro and in vivo (micronucleus) mammalian

cytogenetics assays or in an unscheduled DNA synthesis (UDS) assay. An impurity in

pinoxaden (SYN519312), did not produce a mutagenic effect when tested in a bacterial gene

mutation assay. There was no indication of endocrine disruption.

More than 90% of the orally gavaged dose was absorbed from the gastrointestinal tract. 

Approximately, 90% of the absorbed dose was excreted in the urine and feces in 72 hours and

excretion was nearly complete in 7 days. Excretion in the urine ranged from 59-78% and in

feces 20-25%. Tissue distribution data indicated no significant accumulation in the body. A

billiary excretion study did not indicate enterohepatic circulation. No parent compound was

detected in the urine, feces or bile. The major metabolite in the urine and feces was the

hydrolysis product M2. Major metabolites in the urine were M2 (65%-85%) and M4 (5-13%)

and in the feces were M2 (50%-70%) and M4 (25%-35%) depending upon the dose. There were

no sex-related differences in the absorption, distribution, excretion or qualitative profile of the

metabolites. 

Dose Response Assessment and Food Quality Protection Act (FQPA) Decision 

The critical effect for the overall risk assessment is based on the effects seen in the rabbit

developmental toxicity study. Effects observed included morbid condition in one rabbit

(mortality), early resorptions, postimplantation loss, abortion, decreased body weights, body

weight gains and food consumption. The rabbit is the most sensitive species. 
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The developmental toxicity study in rabbits was chosen for the acute and chronic reference doses

(aRfD and cRfD, respectively) as well as for all other exposure routes and durations. For the

population females 13-49 years old, the aRfD was calculated using the developmental noobserved adverse-effect level (NOAEL) of 30 mg/kg/day. The lowest-observed adverse-effects

level (LOAEL) of 100 mg/kg/day was based on increased incidence of complete early litter

resorption. This study provides the lowest dose attributable to a single-dose developmental

effect (increased incidence of early resorptions) applicable to the female 13-49 years of age. An

aRfD for the general population was not identified since an endpoint of concern attributable to a

single dose effect was not identified in the hazard database. The cRfD (0.3 mg/kg/day) and the

risk assessments for all other exposure scenarios were calculated based on the maternal NOAEL

of 30 mg/kg/day. The LOAEL of 100 mg/kg/day is based on morbid condition in one rabbit

(mortality), clinical signs of toxicity in a morbid rabbit, abortion, decreased body weights, body

weight gains and food consumption. 

The dermal-absorption is estimated to be 40% based on the results of the in vivo dermal

penetration study in rats using the EC 100 formulation. The dermal-absorption rate is used for

all dermal risk assessments since the NOAEL used for assessment is based on an oral study. 

HED assumes 100% inhalation absorption.

The CARC concluded that data are inadequate for an assessment of human carcinogenic

potential due to the absence of an acceptable mouse carcinogenicity study. Based on the weight

of the evidence, HED believes that pinoxaden is not likely to pose a cancer risk. Therefore, an

aggregate cancer risk assessment was not performed.

Based on toxicological considerations, and the assumptions used in the exposure assessments,

the pinoxaden risk assessment team determined that a 1x special FQPA safety factor (SF) was

appropriate. The uncertainty factors (UF) used in determining the RfDs were 100 (10x for

intraspecies variation and 10x for interspecies extrapolation). Therefore, the acute and chronic

population-adjusted doses (aPAD and cPAD) are equal to the aRfD and cRfD, respectively

(PAD=RfD/FQPA SF). The level of concern for all non-dietary exposure durations (short-,

intermediate- and long-term) is 100. 

Dietary Exposure Assessment

The residues of concern (for tolerance setting and risk assessment) in wheat and barley are

pinoxaden, M2, M4 (free and conjugated) and M6. In rotational crops, the residues of concern

are pinoxaden, M2, M3 (free and conjugated), M10 and M11. In ruminant livestock, pinoxaden,

M2 and M4 (free and conjugated) are the residues of concern. In poultry livestock, pinoxaden,

M2, M4 (free and conjugated) and M6 are the residues of concern. In drinking water, the

residues of concern are pinoxaden, M2 and M3.

Tolerance-level residues and 100% crop treated were assumed for the dietary risk assessment. 

As tolerances are based on maximum residues from field trials conducted under highest

application rates and the shortest PHI, the dietary risk estimates are considered conservative. 

The Tier 1 acute dietary risk assessment (including drinking water) indicates that for all included

commodities, the acute dietary risk estimate is below HED’s level of concern (<100% of the

aPAD). The resulting risk estimate for females 13-49 years old is 1.5 % of the aPAD at the 95th
8

percentile. 

The Tier 1 chronic dietary risk assessment (including water) indicates that for all included

commodities, the chronic dietary risk estimates are below HED’s level of concern for the general

U.S. population and all population subgroups (<100% of the cPAD). The chronic dietary

exposure estimate for the general population is 0.9% of the cPAD. The estimate for the highest

exposed population subgroup (children 1-2 years old) is 2.1% of the cPAD. 

Aggregate Risk

No residential uses are proposed for pinoxaden at this time. Therefore, aggregate risk consists of

exposure from food and drinking water sources only. Acute and chronic aggregate risks were

assessed by incorporating the drinking water estimates directly into the dietary exposure

assessment. Aggregate risk estimates are reported above under Dietary Exposure Assessment. 

Acute and chronic aggregate risks do not exceed HED’s level of concern. 

Occupational Risk

Based upon the proposed use pattern, HED believes the most highly-exposed occupational

pesticide handlers (i.e., mixers, loaders, applicators) are:

1) Mixer/loader using open-pour loading of liquids in support of aerial operations

2) Applicator using open-cab ground-boom equipment

3) Aerial applicator (pilot).

Short- (1-30 days) and intermediate-term (1-6 months) exposures were assessed. Although the

proposed labeling directs users not to apply more than one application per year, commercial

applicators may experience intermediate-term exposures since they may treat a number of farms

sequentially. 

No chemical-specific data were available with which to assess potential exposure to pesticide

handlers. The estimates of exposure to pesticide handlers are based upon surrogate study data

available in Pesticide Handlers Exposure Database (PHED; v. 1.1, 1998). It is HED policy to

assess handler exposure and risk using “baseline” personal protective equipment (PPE) which is

comprised of long-sleeved shirt, long pants, and shoes plus socks. If necessary, HED assesses

risk using “baseline” plus the use of protective gloves or other PPE as might be necessary or

appropriate. The proposed label directs applicators and other handlers to wear a long-sleeved

shirt and long pants, shoes plus socks and chemical resistant gloves. 

Short- and intermediate-term handler risks were estimated for handlers and postapplication

workers. A dermal-absorption factor of 40% was used to calculate occupational risks. HED

assumed 100% inhalation absorption.

Provided that mixer/loaders use protective gloves as specified on the proposed label, all margins

of exposure (MOEs) are $100 and therefore do not exceed HED’s level of concern (MOE of at

least 100).

There is a potential for agricultural workers to have post-application exposure to pesticides

during the course of typical agricultural activities. Based upon the proposed use pattern (early

post-emergence), the most conservative transfer coefficient (TC) applicable to pinoxaden is for
9

scouting at 100 cm2/hr. Short-term exposures are expected. Post-application worker exposure is

estimated using the highest proposed application rate and a TC of 100 cm2/hr. This TC was

obtained from an interim TC policy developed by HED’s Science Advisory Council for

Exposure (ExpoSAC) using proprietary data from the Agricultural Re-Entry Task Force (ARTF)

database (SOP # 3.1). 

Lacking compound-specific dislodgeable foliar residue (DFR) data, HED assumes 20% of the

application rate is available as DFR on day zero after application, adapted from the ExpoSAC 

SOP No. 003 (7 May 1998 - Revised 7 August 2000). The estimated MOE for postapplication

workers is 65,000 and does not exceed HED’s level of concern (MOE of at least 100). 

HED Recommendations

Provided a revised Section F is submitted, and the Agency validations of the proposed analytical

enforcement methods are successful, HED concludes there are no residue chemistry data

requirements that would preclude the establishment of a conditional registration and the

following permanent tolerances:

1) For the combined residues of pinoxaden

(8-(2,6-diethyl-4-methylphenyl)-1,2,4,5-tetrahydro-7-oxo-7H-pyrazolo[1,2-d][1,4,5]

oxadiazepin-9-yl 2,2-dimethylpropanoate), and its metabolites

8-(2,6-diethyl-4-methyl-phenyl)-tetrahydro-pyrazolo[1,2-d][1,4,5]oxadiazepine-7,9-dione (M2),

and free and conjugated forms of

8-(2,6-diethyl-4-hydroxymethyl-phenyl)-tetrahydro-pyrazolo[1,2-d][1,4,5]

oxadiazepine-7,9-dione (M4), and 4-(7,9-dioxo-hexahydro-pyrazolo[1,2-d]

[1,4,5]oxadiazepin-8-yl)-3,5-diethyl-benzoic acid (M6), calculated as pinoxaden, in/on the

following commodities:

Wheat, grain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.3 ppm

Wheat, forage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.5 ppm

Wheat, bran . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.0 ppm

Barley, grain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.9 ppm

Barley, hay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.5 ppm

Barley, straw . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.0 ppm

Barley, bran . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.6 ppm

Egg . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.06 ppm

Poultry, fat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.06 ppm

Poultry, meat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.06 ppm

Poultry, meat byproduct .................................................. 0.06 ppm
10

HED recommends that conversion of conditional registration to unconditional registration may

be considered upon submission of the following residue chemistry data:

C Additional storage stability data for wheat and barley processed fractions. 

C Additional validation data for pinoxaden and M2 residues in livestock commodities

(ruminant and poultry)
11

2.0 Ingredient Profile

2.1 Summary of Registered/Proposed Uses

Table 2.1 Summary of Directions for Use of Pinoxaden

Applic. Timing,

Type, and Equip.

Formulation

[EPA Reg.

No.]

Applic.

Rate 

(lb ai/A)

Max.

No.

Applic.

per

Season

Max.

Seasonal

Applic. Rate

(lb ai/A)

PHI

(days)

Use Directions and Limitations

Wheat (including durum) and Barley

Ground and aerial

applications.

Foliar spray. 

Ground: Water

volume of 5-10

gals./A.Aerial:

Water volume of

minimum of 3-5

gals./A.

NOA

407855 100

EC

0.036 -0.062 1 0.062 60 - Pre-grazing Interval of 30 days

-Timing: From the 2-leaf stage to

pre-boot stage of wheat and

barley.

Label Recommendations:- Do not

treat spring wheat, durum wheat

or barley underseeded to forages.

Tank mixing is not recommended

with any chemical additives,

pesticides, or fertilizers that are

not recommended on this label.

Rotational Crop Restrictions:

Wheat (including durum) and

barley: 0 days

All other crops: 30 days

PHI = pre-harvest interval
12

2.2 Structure and Nomenclature

Table 2.2 Pinoxaden Nomenclature

Compound

N

N

O

O

O

O

Common name pinoxaden

Company experimental name NOA 407855 or M1

IUPAC name 8-(2,6-diethyl-p-tolyl)-1,2,4,5-tetrahydro-7-oxo-7H-pyrazolo[1,2-d][1,4,5]oxadiazepin-9

-yl 2,2-dimethylpropionate

CAS name 8-(2,6-diethyl-4-methylphenyl)-1,2,4,5-tetrahydro-7-oxo-7H-pyrazolo[1,2-d][1,4,5]

oxadiazepin-9-yl 2,2-dimethylpropanoate

CAS # 243973-20-8, 99607-70-2

End-use product/EP NOA 407855 100 EC

Known Impurities of Concern None
13

2.3 Physical and Chemical Properties

Table 2.3 Physicochemical Properties of Pinoxaden

Parameter Value

Melting point/range 120.5 - 121.6 /C

pH 4.9 at 25 /C

Density (20/C) 1.16 x 103 kg/m3 at 24 /C

Water solubility (20/C) 200 mg/L

Solvent solubility (g/100 mL at 20/C) acetone 250

dichloromethane >500

ethyl acetate 130

hexane 1.0

methanol 260

octanol 140

toluene 130

Vapor pressure at 20/C and 25/C 2.0 x 10-7 Pa at 20/C4.6 x 10-7 Pa at 25/C

Octanol/water partition coefficient Log(KOW) at 20/C 3.2 at 25/C

UV/visible absorption spectrum Conditions 8, nm

neutral solution 210, 258

acidic solution 210, 254

basic solution 220, 252

No absorption maximum between 350 and 750 was observed in

any of the three solutions.

All data came from PMRA Lab Services.

3.0 Metabolism Assessment

See Appendix 3 (Table A-3.1b) for metabolite structures.

3.1 Comparative Metabolic Profile

In both plant and livestock, pinoxaden undergoes hydrolysis of the ester moiety, hydroxylation

and conjugation with sugars. For the most part (in most of the metabolites identified), it appears

that the three-ring backbone of pinoxaden is conserved in plants and livestock metabolites. 

In plants, pinoxaden is rapidly metabolized to its ester hydrolysis product, M2, which

subsequently, at a lower rate, is metabolized to M4 which has an additional hydroxyl group on

the phenyl side chain. The free and conjugated form of M4 was identified as the predominate

metabolite in all wheat commodities. M6 is also one of the major metabolites in wheat grain. 

In confined rotational crops, no substantive variation in the metabolic degradation of pinoxaden

was observed. Pinoxaden was hydrolyzed rapidly (disappeared by day 3) in soil, yielding M2. 

M2 was further hydroxylated forming M3, the predominant metabolite observed in soil. M3

could thus be taken up from the soil by rotated crops. Metabolism of pinoxaden in rotational

crops occurred mainly by hydroxylation processes. Other major metabolites were M10 and

M11. No quantifiable residues of pinoxaden and/or its metabolites were found in all rotational

crops at various PHIs (lettuce, mustard leaves, radish and turnip), except wheat forage and

fodder.
14

In livestock, goats and hens were fed either pinoxaden and/or M4 separately. The major

metabolites were M2 and intact M4, with M6 is also seen in hens. 

The metabolism of pinoxaden in rats primarily involves the initial hydrolysis of the ester moiety

to form metabolite M2 (NOA 407854), which is then extensively excreted in the urine and feces. 

To a minor extent, metabolite M2 is also further metabolized via hydroxylation, dealkylation,

ring cleavage, ring formation, and conjugation into a wide variety of minor metabolites. The

proposed pathway is also supported by the appended in vitro study, which indicates that

pinoxaden is rapidly hydrolyzed to M2 in rat plasma (T1⁄2 = -0.1 min) at concentrations up to

100 μM (-40 ppm).

Overall, it can be said that residues of pinoxaden and M4 (and by inference all metabolites

sharing a similar structure), have a very low transfer into the edible tissues and milk of lactating

goats. 

3.2 Nature of the Residue in Foods

3.2.1. Description of Primary Crop Metabolism

The metabolism of pinoxaden proceeded predominantly by hydrolysis of the ester moiety of the

parent molecule to give M2, which was subsequently hydroxylated either at the 4-methyl group

of the phenyl moiety yielding M4, or at position 3 of the pyrazol moiety yielding M3. M3 was

further hydroxylated to M10. M4 and M10 were conjugated with glucose leading to M5 and

M8. M7 and M9 resulted, respectively, from the malonylation of M5 and M8. Another

metabolic pathway resulted from the oxidation of the methyl-hydroxy function of M4 and M10

to the corresponding carboxylic acids M6 and M11. A minor metabolic pathway resulted from

the oxidation of the ethyl side chain of M10 followed by cyclisation to M32.

3.2.2 Description of Livestock Metabolism

Transfer of radioactive residues to edible tissues and milk is minimal. In goats administered the

predominant plant metabolite M4, transfer of total radioactive residues to milk and edible tissues

was very low. The highest concentrations of total radioactive residues in both studies were in

the liver and kidney, which is to be expected considering the rapid metabolism and excretion of

pinoxaden and its metabolites. These results indicate that residues of pinoxaden and M4 (and by

inference all metabolites sharing a similar structure), have a very low transfer into the edible

tissues and milk of lactating goats. Overall, it can be concluded that pinoxaden is rapidly

metabolized in all lactating goat matrices.

[Phenyl-14C]-pinoxaden was rapidly and completely metabolized in all goat matrices. The parent

metabolite was not detected in milk, feces, urine or any of the tissues analyzed. The

predominant metabolite identified in all goat matrices was M2, which is formed by the

hydrolysis of the ester moiety on the parent molecule. In the [7-14C] M4 metabolism study, the

predominant metabolite identified in all goat matrices was unchanged M4. Hydroxylation of M4

to M10 did occur in all matrices characterized, but this represented only a minor fraction (<

10%) of the TRRs. Of note, the metabolite M10 was not detected in any of the matrices of goats

administered [phenyl-14C]-pinoxaden.
15

3.2.3 Description of Rotational Crop Metabolism, including identification of major

metabolites and specific routes of biotransformation

In confined rotational crops, no substantive variation in the metabolic degradation of pinoxaden

was observed. Pinoxaden was hydrolyzed rapidly (disappeared by day 3) in soil yielding M2. 

M2 was further hydroxylated forming M3 the predominant metabolite observed in soil. M3

could thus be taken up from the soil by the rotated crops. Metabolism of pinoxaden in rotational

crops occurred mainly by hydroxylation processes. Other major metabolites were M10 and

M11. No quantifiable residues of pinoxaden and/or its metabolites were found in all rotational

crops (lettuce, mustard leaves, radish and turnip) except wheat forage and fodder.

3.3 Environmental Degradation

Hydrolysis of pinoxaden is pH dependent and occurs faster under basic conditions. Aqueous

photolysis of pinoxaden is not a major dissipation route when exposed to sunlight. In soil,

photolysis is also not a significant pathway for degradation for pinoxaden without hydrolytic

degradation.

Acceptable laboratory studies showed that pinoxaden degrades rapidly under aerobic soil

metabolism conditions with half-lives ranging from 2 to 3 days, forming the major degradate

M2, which degrades further to form the degradate M3.

Under aerobic aquatic conditions, pinoxaden degrades rapidly to M2 (half-life < 1 day) to the

major transformation product, M2, with maximums of 96.6%, 16.7% and 103.5% of the applied

in water layer, sediment and total system, respectively. M2 was the major product detected in

the treated water-sediment systems under both anaerobic and aerobic conditions. The minor

transformation product M3 was identified with maximums of 0.3%, 0.1% and 0.4% in water,

sediment and total system, respectively. Under aerobic aquatic conditions, more than 86% of

applied activity remains (in total system) in form of the major degradate M2.

Volatility is not a significant route of dissipation. The major degradates of pinoxaden (M2 and

M3) are considered to be mobile based on Freundlich Kads values ranging from 0.06-128 ml/g,

and 0856-0.28 ml/g, respectively, in three test soils (loamy sand, loam, silty clay loam textures).
16

3.4 Summary of Major Residues in Metabolism Studies for Pinoxaden

Table 3.4 Summary of Major Residues in Metabolism Studies for Pinoxaden

Matrix Labeled Ring(s) PHI Range (days) Application Rate 

(lb ai/A)

Residues with

>10% TRR and

>0.01 ppm4

Wheat Grain2 Phenyl and/or

Oxidiazepin

55-67 0.059 Conjugated M4

(0.127 ppm),

conjugated M6

(0.022 ppm)

Wheat Forage2 Phenyl and/or

Pyrazol and/or

Oxidiazepin

14-28 0.059 Conjugated M4

(0.97 ppm)

Wheat Forage, tops,

ears2

Phenyl and/or

Pyrazol and/or

Oxidiazepin

28-42 0.059 Conjugated M4

(2.11 ppm), M9

(0.0165 ppm), 

Goat (12.1 ppm of

pinoxaden in diet)

Phenyl NA NA M2 (2.7 ppm,

kidney)

Goat (10 ppm of M4

in diet)

Phenyl NA NA M4 (0.032 ppm,

kidney)

Poultry (97 ppm of

pinoxaden in diet)

Phenyl NA NA M2 (0.041 ppm,

liver), M4 (0.11

ppm, liver), M6

(0.28 ppm , liver)

Rotational Crops1

(spring wheat

forage)

Phenyl PBI=29 DAT

Harvest=70 DAT

~0.06 to soil M3 (0.0237 ppm)

Rotational Crops1

(spring wheat

fodder)

Phenyl and/or

Oxadiazepin

PBI=15 DAT

Harvest=89 DAP

~0.06 to soil M3 (0.011 ppm),

M10 (~0.01 ppm),

M11 (0.024 ppm)

(DAT = day(s) after treatment), DAP = days after planting

1)Other rotational crop studies on lettuce head, mustard leaves, radishes, and turnips at 30-day PBI (which is on the

label for other crops than wheat and barley) resulted in each metabolite residue <0.01 ppm. 

2) PBI for wheat and barley is 0-day

3) A 30-day after harvest restriction (for any crop part) for feeding livestock is stated on the proposed label.
17

3.5 Toxicity Profile of Major Metabolites and Degradates

In a 90-day feeding study in rats, metabolite M3 produced decreases in body weight, body

weight gain and food efficiency in both males and females. M3 also caused treatment-related

hepatotoxicity in both sexes and nephrotoxicity in males. No evidence of mutagenicity was

observed with M3 when tested in an in vitro bacterial gene mutation assay, in an in vitro

mammalian gene mutation assay, in both in vitro and in vivo (micronucleus) mammalian

cytogenetics assays or in an unscheduled DNA synthesis (UDS) assay. However, M3 was

positive in an in vitro human lymphocyte cytogenetics assay with and without S9-metabolic

activation. In a 90-day feeding study in rats, metabolite M6 produced no toxic effects at the

highest dose tested of 978 and 1035 mg/kg/day (limit dose) in male and female rats, respectively. 

 No evidence of mutagenicity was observed with M6 when tested in an in vitro bacterial gene

mutation assay, in an in vitro mammalian gene mutation assay or in an in vitro mammalian

cytogenetics assay. No evidence of mutagenicity was observed with M10 when tested in an in

vitro bacterial gene mutation assay, in an in vitro mammalian gene mutation assay, in both in

vitro and in vivo (micronucleus) mammalian cytogenetics assays or in an unscheduled DNA

synthesis (UDS) assay. An impurity in pinoxaden (SYN519312) , did not produce a mutagenic

effect when tested in a bacterial gene mutation assay.

Table 3.5a Toxicity Profile for Pinoxaden Metabolite M3

Guideline No./

Study Type

MRID No. (year)/

Classification /Doses

Results

870.3100

90-day

rats - diet

46203240, 46203231,

46203233 (2003)

Acceptable/Guideline

0/0, 15.0/15.2, 99.2/98.8 or

600.6/645.4 mg/kg/day 

NOAEL = 99.2/98.8 mg/kg/day (M/F) 

LOAEL = 600.6/645.4 mg/kg/day based on decreased body

weight and body weight gain and food efficiency in both

sexes, and evidence of hepatotoxicity in both sexes and

nephrotoxicity in males (M/F).

870.5100

In Vitro

bacterial gene

mutation S.

typhimurium/E.

coli

46203315 (2003)

Acceptable/Guideline

100, 200, 500, 1000, 2500 or

5000 μg /plate (+/- activation) 

No evidence of mutagenicity in Salmonella strains TA98,

TA100, TA1535, and TA1537 and Escherichia coli strain

WP2uvrA.

[negative]

870.5300

In Vitro

mammalian

gene mutation 

(L5178YTK+/-)

46203319 (2003)

Acceptable/Guideline

0, 125, 250, 500, 1000, 1500

or 2000 μg/mL (+/-

activation)

No reproducible significant (p#0.05) and/or concentrationdependent increases in mutant frequency were observed at

any dose level in the presence or absence of S9. 

[negative]

870.5375

In vitro

mammalian

cytogenetics

human 

lymphocytes 

46203323 (2003)

Acceptable/Guideline

0, 50, 100, 250, 500, 750,

1000, 1500, 2000, 2500, 3000,

and 3324 :g/mL (+/-

activation)

At 1500 :g/mL, NOA 447204 induced increased (p#0.05)

aberration frequencies (excluding gaps) in the presence of S9

in Trials 1 and 2 (4.5-8.67% treated vs 1.0% solvent control),

and in the absence of S9 in Trial 1 (6.5% treated vs 2.0%

solvent control) after a 3 hour treatment period and a 17 hour

recovery period. The significant increases observed equaled

or exceeded the upper limit of the historical control ranges. 

[positive]
Guideline No./

Study Type

MRID No. (year)/

Classification /Doses

Results

18

870.5395

In Vivo

mammalian

cytogenetics 

micronucleus

mice

46203328 (20030

Acceptable/Guideline

0, 200, 400 or 800 mg/kg 

No significant increase in micronucleated polychromatic

erythrocytes (MPCEs) was observed in any dose at either 24

or 48 hours post-dosing. The positive control induced the

appropriate response.

[negative]

870.5550

UDS in

mammalian

cells

46203326 (2003)

Acceptable/Guideline

0, 625 or 1250 mg/kg 

There were no marked increases observed in mean net nuclear

grains (NNG) or percent cells in repair (NNG $5) at 2 or 16

hours post-dosing compared to controls. The positive control

induced the appropriate response. 

[negative]

Table 3.5b Toxicity Profile for Pinoxaden Metabolite M6

Guideline No./

Study Type

MRID No. (year)/

Classification /Doses

Results

870.3100

90-day

rats - diet

46203238, 46203232 (2003)

Acceptable/Guideline

0/0, 23.9/26.8, 246.8/266.4 or

977.5/1034.9 mg/kg/day

NOAEL = 977.5/1034.9 mg/kg/day (M/F) 

LOAEL was not observed

870.5100

In Vitro

bacterial gene

mutation S.

typhimurium/E.

coli

46203316 (2003)

Acceptable/Guideline

100, 200, 500, 1000, 2500 or

5000 μg /plate (-/+ activation) 

No evidence of mutagenicity in Salmonella strains TA98,

TA100, TA1535, and TA1537 and Escherichia coli strain

WP2uvrA.

[negative]

870.5300

In Vitro

mammalian

gene mutation 

(L5178YTK+/-)

46203320 (2003)

Acceptable/Guideline

0, 125, 250, 500, 1000, 1500

or 2000 μg/mL (-/+

activation)

No reproducible significant (p#0.05) and/or concentrationdependent increases in mutant frequency were observed at

any dose level in the presence or absence of S9. 

[negative]

870.5375

In vitro

mammalian

cytogenetics

human 

lymphocytes 

46203324 (2003)

Acceptable/Guideline

50, 100, 200, 500, 1000, 1500

or2000 μg/mL (-/+ activation)

There was no evidence of chromosome aberrations induced

over background in the presence or absence of S9-activation.

[negative]
19

Table 3.5c Toxicity Profile for Pinoxaden Metabolite M10

Guideline No./

Study Type

MRID No. (year)/

Classification /Doses

Results

870.5100

In Vitro

bacterial gene

mutation S.

typhimurium/E.

coli

46224810 (2003)

Acceptable/Guideline

100, 200, 500, 1000, 2500 or

5000 μg /plate (-/+ activation) 

No evidence of mutagenicity in Salmonella strains TA98,

TA100, TA1535, and TA1537 and Escherichia coli strain

WP2uvrA.

[negative]

870.5300

In Vitro

mammalian

gene mutation 

(L5178YTK+/-)

46224811 (2003)

Acceptable/Guideline

0, 125, 250, 500, 1000, 2000

or 3484 μg/mL (-/+

activation)

No reproducible significant (p#0.05) increases in mutant

frequency were observed at any dose level in the presence or

absence of S9. 

[negative]

870.5375

In vitro

mammalian

cytogenetics

human 

lymphocytes 

46224812 (2003)

Acceptable/Guideline

10, 50, 100, 250, 500, 750,

1000, 1500, 2500 or 3484

μg/mL (-/+ activation)

There was no evidence of chromosome aberrations induced

over background in the presence or absence of S9-activation.

[negative]

870.5395

In Vivo

mammalian

cytogenetics 

micronucleus

mice

46224813 (2004)

Acceptable/Guideline

0 or 2000 mg/kg

No significant increase in micronucleated polychromatic

erythrocytes (MPCEs) was observed in any dose at either 24

or 48 hours post-dosing. The positive control induced the

appropriate response.

[negative]

870.5550

UDS in

mammalian

cells

46224814 (2004)

Acceptable/Guideline

2000 mg/kg

There were no marked increases observed in mean net nuclear

grains (NNG) or percent cells in repair (NNG $5) at 2 or 16

hours post-dosing compared to controls. The positive control

induced the appropriate response. 

[negative]

Table 3.5d Toxicity Profile for Pinoxaden Impurity SYN519312 

Guideline No./

Study Type

MRID No. (year)/

Classification /Doses

Results

870.5100

In Vitro

bacterial gene

mutation S.

typhimurium/E.

coli

46203317 (2003)

Acceptable/Guideline

100, 200, 500, 1000, 2500 or

5000 μg /plate (-/+ activation) 

No evidence of mutagenicity in Salmonella strains TA98,

TA100, TA1535, and TA1537 and Escherichia coli strain

WP2uvrA.

[negative]
20

3.6 Summary of Residues for Tolerance Expression and Risk Assessment

3.6.1 Tabular Summary

Table 3.6.1 Summary of Metabolites and Degradates to be included in the Risk

Assessment and Tolerance Expression

Matrix

Residues included in Risk

Assessment

Residues included in

Tolerance Expression

Plants Wheat+Barley Pinoxaden, M2, M4 (free &

conjugated), M6

Pinoxaden, M2, M4 (free &

conjugated), M6

Rotational Crops Pinoxaden, M2, M3 (free &

conjugated), M10, M11

No tolerance required.

Livestock Ruminant Pinoxaden, M2, M4 (free &

conjugated)

Pinoxaden, M2, M4 (free &

conjugated)

Poultry Pinoxaden, M2, M4 (free &

conjugated), M6

Pinoxaden, M2, M4 (free &

conjugated), M6

Drinking Water Pinoxaden, M2 and M3 NA

3.6.2 Rationale for Inclusion of Metabolites and Degradates

Plants

The metabolites with >10%TRR and >0.01 ppm in studies with the same or similar proposed use

pattern (rate, PHI, ground) were chosen as metabolites of concern since it was determined that

all the metabolites of pinoxaden are expected to have similar toxicity level as of the parent. 

From wheat grain metabolism studies (14C-Phenyl and 14C-oxadiazepin study, PHI: 55-67 days,

rate: 66 g ai/ha), the metabolites of concern were M4 (free and conjugated) and M6. Thus, the

residues of concern for wheat grain, besides parent and M2 (since parent is rapidly transformed

to M2) were determined to be M4 (free and conjugated), and M6. Likewise for wheat forage

(from studies with 14-day and 28-day PHIs, 66 g a.i./ha), the metabolites of concern besides

parent and M2 were M4 (free and conjugated) and M6. The metabolite M9 was not included

since it was detected in only one study.

Livestock

From livestock metabolism studies, the residues with concentrations >10% TRR were chosen as

residues of concern for livestock. Therefore, besides the parent compound, M2 and M4 (free and

conjugated) for ruminants and M2, M4 (free and conjugated), and M6 for poultry were

determined to be residues of concern. M4 is the major metabolite in the livestock. [14Cphenyl]-pinoxaden and [14C-phenyl]-M4 were the only compounds that were fed to ruminants in

two separate studies. HED concluded that since in the livestock metabolism studies it was

shown that the backbone of pinoxaden which is comprised of 3 rings remains intact in all the

metabolites and M4 is the major metabolite, additional studies are not required. The same

conclusion was drawn for poultry metabolism study.

Rotational Crops
21

From rotational crop studies in which ~ 0.06 lb ai/A [14C-phenyl]- or [14C-oxadiazepin]-

pinoxaden was applied to soil, with eliminating the residues <0.01 ppm the other observed

metabolites, i.e., M2, M3, M10, and M11 (beside the parent) were determined to be residues of

concern based on 15 DAT and 30 DAT PBI in rotated spring wheat forage and fodder with

restriction of no more than 0.06 lb ai/A use rate on primary crops. No metabolites with

concentrations above 0.01 ppm were found in rotated head lettuce, radish (tops and roots),

mustard leaves, turnip, and cereal grains at 30 or 15 DAT PBI.

The proposed label specifies a 0-day PBI for cereal grains and a 30-day PBI for other crops;

therefore a revision is required. The recommended PBIs are:

0-day PBI for wheat and barley,

30-day PBI for leafy and root crops

120-day PBI for other cereal grains and all other crops.

Drinking Water

In laboratory studies under aerobic soil metabolism conditions or aerobic aquatic conditions, it

has been shown that pinoxaden rapidly degrades to M2 and then M3 (half-life of 2-3 days for the

parent); therefore, the residues of concern for drinking water are the parent, and metabolites M2

and M3.

4.0 Hazard Characterization/Assessment

The toxicological database for pinoxaden is considered adequate for hazard characterization. 

Normally, a 28-day inhalation toxicity study would be required. However, based on the low

volatility and low inhalation toxicity (Category IV) of pinoxaden and inhalation margins of

exposure (MOEs) >1000 for the proposed uses in this risk assessment, pinoxaden qualifies for a

waiver of the 28-day inhalation toxicity study for the proposed uses [HED Standard Operating

Procedure (SOP) 2002.01: Guidance: Waiver Criteria for Multiple-Exposure Inhalation Toxicity

Studies, 08/15/02]. The requirement for the 28-day inhalation toxicity study is waived for

this action only. If in the future, requests for new uses or formulations are submitted that may

result in a significant change in either the toxicity profile or exposure scenarios, HED will

reconsider this data requirement. 

The two mouse carcinogenicity studies (1 via gavage; 1 dietary feeding) were considered to be

inadequate for evaluating carcinogenic potential. Nonetheless, based on the following weightof-evidence, a repeat carcinogenicity study in mice is not required at this time and it is not

expected to provide additional useful information for the risk assessment.

• No evidence of carcinogenicity was observed in an acceptable/guideline carcinogenicity

study in rats

• The gavage carcinogenicity study in mice was conducted at doses as high as 750

mg/kg/day. No tumors were observed in other organs except adenomas/carcinomas in

the lungs. However, the interpretation of the adenomas/carcinomas in the lungs was

confounded by the gavage errors that may have introduced the dosing solution in to the

trachea and lungs, and perhaps leading to lung tumors and excessive mortality. 

• No tumors were seen in the mouse dietary carcinogenicity study, however, the dosing 

was considered to be inadequate due to the lack of significant systemic toxicity at doses
22

up to 181.2 mg/kg/day (the study, performed under OECD and EPA guidelines, was

terminated early for humanitarian reasons due to excessive decreases in body weight

gain in the high dose animals) 

• In the 90-day feeding study in mice, pinoxaden was tested up to 7000 ppm (1311

mg/kg/day; Limit Dose), and did not produce any tumors or severe toxicity.

• Pinoxaden was considered to be non-mutagenic.

This evidence convinces EPA that repeating the dietary mouse cancer study is unlikely to

provide additional useful information for the risk assessment, and that pinoxaden is not likely to

pose a cancer risk.

4.1 Hazard Characterization

Pinoxaden has a low order of acute toxicity by the oral, dermal and inhalation routes (Toxicity

Categories III or IV). Pinoxaden is severely irritating to the eye, but is not irritating to the skin. 

Pinoxaden is not a skin sensitizer. In the subchronic and chronic toxicity study in rats, mice and

dogs, food consumption (or food efficiency-mice), body weight and body weight gain were the

parameters that were most often affected. In addition, rats and mice often showed kidney effects

such as renal tubular basophilia and alterations in urinalysis parameters. In the subchronic rat

studies, increased water consumption, increased urine volume and kidney effects were observed. 

In the subchronic mouse study, one also observed piloerection. In the subchronic dog study,

fluid feces, vomit, pale and thin appearance, decreased activity, dehydration, cold to touch, and

regurgitation were observed, in addition to the decreases in body weight, body weight gain and

food consumption. In the chronic toxicity study in dogs, no systemic toxicity was observed at

the highest dose tested (HDT; 125 mg/kg/day). Carcinogenicity was not observed in the rat

chronic toxicity/carcinogenicity study. The two carcinogenicity studies in mice (1 via gavage; 1

dietary) were considered to be inadequate for evaluating the carcinogenic potential of pinoxaden

in mice. The increased mortality resulting from gavage error together with lung involvement

confounded the results of the gavage carcinogenicity study in mice. The dosing in the dietary

study in mice was considered to be inadequate due to the lack of toxicity in animals at the

highest dose tested. 

The critical adverse-effect for the overall risk assessment is based on the effects seen in the

rabbit developmental toxicity study. Effects observed included morbid condition in one rabbit

(mortality), early resorptions, postimplantation loss, abortion, decreased body weights, body

weight gains and food consumption. The rabbit is the most sensitive species. 

Pinoxaden was not neurotoxic in the acute or the subchronic rat neurotoxicity studies. No

quantitative or qualitative evidence of increased susceptibility was seen following in utero

exposure to rats or rabbits in developmental studies or in the reproduction study. Pinoxaden was 

mutagenic in two in vitro mammalian cytogenetic tests using V79 Chinese Hamster lung

fibroblasts cells, but negative in an in vivo mammalian cytogenetics (micronucleus) test. 

Pinoxaden was negative in bacterial and mammalian gene mutation tests and in two unscheduled

DNA synthesis (UDS) assays. Pinoxaden was considered to be non-mutagenic based on the

overall weight-of -evidence. One metabolite, M3, produced decreases in body weight, body

weight gain and food consumption in a 90-day feeding study in rats. It was also hepatotoxic in

both sexes and nephrotoxic in males. No evidence of mutagenicity was observed with M3 when
23

tested in an in vitro bacterial gene mutation assay, in an in vitro mammalian gene mutation

assay, in an in vivo (micronucleus) mammalian cytogenetics assay or in an unscheduled DNA

synthesis (UDS) assay. However, M3 was positive in an in vitro human lymphocyte

cytogenetics assay with and without S9-metabolic activation. In a 90-day feeding study in rats,

metabolite M6 produced no toxic effects at the highest dose tested of 978 and 1035 mg/kg/day

(limit dose) in male and female rats, respectively. No evidence of mutagenicity was observed

with M6 when tested in an in vitro bacterial gene mutation assay, in an in vitro mammalian gene

mutation assay or in an in vitro mammalian cytogenetics assay. No evidence of mutagenicity

was observed with M10 when tested in an in vitro bacterial gene mutation assay, in an in vitro

mammalian gene mutation assay, in both in vitro and in vivo (micronucleus) mammalian

cytogenetics assays or in an unscheduled DNA synthesis (UDS) assay. An impurity in

pinoxaden (SYN519312), did not produce a mutagenic effect when tested in a bacterial gene

mutation assay. There was no indication of endocrine disruption.

More than 90% of the orally gavaged dose was absorbed from the gastrointestinal tract. 

Approximately, 90% of the absorbed dose was excreted in the urine and feces in 72 hours and

excretion was nearly complete in 7 days. Excretion in the urine ranged from 59-78% and in

feces 20-25%. Tissue distribution data indicated no significant accumulation in the body. 

Billiary excretion study did not indicate enterohepatic circulation. No parent compound was

detected in the urine, feces or bile. Major metabolite in the urine and feces was the hydrolysis

product M2. Major metabolites in the urine were M2 (65%-85%) and M4 (5-13%) and in the

feces 50%-70%) and M4 (25%-35%) depending up on the dose. There were no sex related

differences in the absorption, distribution, excretion or qualitative profile of the metabolites. 

Toxicology data generated on several metabolites and one contaminant of pinoxaden are

summarized in Table 3.5 a-d.

Table 4.1a: Acute Toxicity Profile - Pinoxaden

Guideline No. Study Type MRIDs # Results

Toxicity

Category

81-1 Acute Oral 46203214 LD50 >5000 mg/kg IV

81-2 Acute Dermal 46203219 LD50 > 2,000 mg/kg 

(limit dose) 

III

81-3 Acute Inhalation 46203221 LC50 = 5.22 mg/L IV

81-4 Primary Eye Irritation 46203223 Severe eye irritant I

81-5 Primary Skin Irritation 46203225 Non-irritating IV

81-6 Dermal Sensitization 46203227 Non sensitizer n/a

Table 4.1b Subchronic, Chronic and Other Toxicity Profile - Pinoxaden
24

Guideline No./

Study Type

MRID No. (year)/

Classification /Doses

Results

870.3100

90-Day rats -

gavage

46203239 (2003)

Acceptable/Guideline

0, 3, 10, 30, 100, or 300 

mg/kg/day

NOAEL = 300/100 mg/kg/day (M/F)

LOAEL was not observed in males; = 300 mg/kg/day in

females, based on increased water consumption and urinary

volume

870.3100

90-Day

rats - diet

46203235, 46203237 (2003)

Acceptable/Guideline

0, 150, 1000, 5000, or 10000

ppm ( 0/0, 15/16, 98/110,

466/527 or 900/965mg/kg/day

in males/females)

NOAEL = 466/537 mg/kg/day (M/F) 

LOAEL = 900/965 mg/kg/day based on decreased body

weight and body weight gain and increased incidence of renal

lesions in both sexes; decreased food consumption and

increased water consumption in males; and increased urine

volume in females

870.3100

13-Week oral

mice - gavage

46203241 (2002)

Acceptable/Guideline

0, 10, 100, 400, 700 or 1000

mg/kg/day (limit dose)

NOAEL = 700 mg/kg/day 

LOAEL = 1000 mg/kg/day based on increased incidence of

piloerection and decreased body weight gain in both sexes,

and increased incidence of renal tubular basophilia in males

870.3100

90-Day oral

mice - diet

46203236, 46224805 (2003)

Acceptable/Guideline

0, 1000, 2500, 5000 or 7000

ppm (0/0, 140.9/165.9,

365.0/436.7, 708.2/900.6 or

992.3/1311.7 mg/kg/day in

males/females)

NOAEL was not observed in females, but was 365.0 mg/kg

bw/day in males

LOAEL =165.9 mg/kg bw/day in females, based on decreased

body weight and body weight gain and 708.2 mg/kg bw/day

in males, based on decreased food efficiency 

870.3150

90-Day

dogs - capsule

46203242 (2003)

Acceptable/Guideline

0, 25, 100, 250 or 500

mg/kg/day

NOAEL = 100 mg/kg/day 

LOAEL = 250 mg/kg/day based on clinical signs of toxicity

fluid feces, vomit, pale and thin appearance, decreased

activity, dehydration, cold to touch, and regurgitation in both

sexes, and mucus in feces in the males) and decreased body

weights, body weight gains, and food consumption in both

sexes

870.3200

28-Day dermal

toxicity - rat

46203243 (2001)

Acceptable/Guideline

0, 10, 100, or 1000 mg/kg/day

LOAEL was not observed

NOAEL = 1000 mg/kg bw/day (the limit dose)

870.3700

Prenatal

developmental

toxicity - rabbit

46203303 (2003)

Acceptable/Guideline

0, 3, 10, 30, or 100 mg/kg/day

Maternal NOAEL = 30 mg/kg/day

Maternal LOAEL = 100 mg/kg/day, based on increased

mortality, abortion, and decreased body weights, body weight

gains and food consumption

Developmental NOAEL = 30 mg/kg/day

Developmental LOAEL = 100 mg/kg day, based on increased

incidence of complete early litter resorption

870.3700

Prenatal

developmental

toxicity - rat

46203305 (2003)

Acceptable/Guideline

0, 3, 30, 30, 300 or 800

mg/kg/day

Maternal NOAEL = 30 mg/kg/day 

Maternal LOAEL = 300 mg/kg bw/day, based on decreased

body weight gains and food consumption

Developmental NOAEL = 30 mg/kg/day Developmental

LOAEL = 300 mg/kg/day, based on delays in skeletal

ossification in the skull and hind digits
Guideline No./

Study Type

MRID No. (year)/

Classification /Doses

Results

25

870.3800

Reproduction

and fertility

effects - rat

46203308 (2003)

Acceptable/Guideline

0, 10, 50, 250 and 500

mg/kg/day

Parental NOAEL = 250 mg/kg/day

Parental LOAEL = 500 mg/kg/day, based on increased water

consumption, renal tubular atrophy, and chronic nephropathy

in both sexes, and increased incidence of renal pelvic

dilatation in the males

Offspring NOAEL = 250 mg/kg/dy

Offspring LOAEL = 500 mg/kg bw/day, based on decreased

body weights and body weight gains in the F1 pups, and

decreased body weights in the F2 males

Reproductive NOAEL = 500 mg/kg/day

Reproductive LOAEL was not observed

870.4100

Chronic

toxicity

dogs - capsule

46203309 (2003)

Acceptable/Guideline

0, 5, 25 or 125 mg/kg/day 

NOAEL = 125 mg/kg/day 

LOAEL was not observed

870.4200

Carcinogenicity

mice - diet

46448801 (2004)

Unacceptable/Guideline

0, 10, 150, 500, 1500 or 4000

ppm (0/0, 16.3/20.2,

60.7/75.7, 181.2/216.5 and

573.7/706.4 mg/kg/day in

males/females)

[4000 ppm dose discontinued

at Week 40]

NOAEL = 216.5/181.2 mg/kg/day (M/F)

LOAEL was not determined

870.4200

Carcinogenicity

mice- gavage

46224808 (2003)

Unacceptable/Guideline

0, 5, 40, 300 or 750 mg/kg

NOAEL/LOAEL could not be determined. The study could

not be interpreted due to gavage errors and lung involvement.

870.4300

Chronic

toxicity/carcino

genicity

rats - gavage

46224809 (2003)

Acceptable/Guideline

0, 1, 10, 100 250 or 500

mg/kg/day

NOAEL = 100 mg/kg/day

LOAEL = 250 mg/kg/day, based on mortality, clinical signs,

and increased serum urea and creatinine in males, and

decreased body weights and body weight gains, increased

water consumption and incidence of urinalysis findings,

kidney surface granulation, and microscopic renal lesions in

both sexes

870.5100

In Vitro

bacterial gene

mutation S.

typhimurium/E.

coli

46203314 (2001)

Acceptable/Guideline

 33, 100, 333, 1000, 2500, or

5000 μg/plate w/wo activation

(cytotoxicity was observed at

$1000 :g/plate) 

No marked increases in the number of revertants were

observed at any concentration in any strain in either trial. 

[negative]

870.5300

In Vitro

mammalian

gene mutation 

(L5178YTK+/-)

46203318 (2003)

Acceptable/Guideline

6.3, 12.5, 254200 :g/mL (-S9)

and 3.1, 6.3, 12.5, 25, 50, 100

or 150 :g/mL (+S9) 

No reproducible substantial ($2x solvent controls) and/or

concentration-dependent increases in mutant colonies per 106

cells were observed at any dose level in the presence or

absence of S9. 

[negative]
Guideline No./

Study Type

MRID No. (year)/

Classification /Doses

Results

26

870.5375

In vitro

mammalian

cytogenetics in

V79 Chinese

Hamster Lung

Fibroblasts

46203321(2001)

Acceptable/Guideline

 6.3, 10, 12.5, 20, 25, 40, 50,

60, 75, 80 or 100 μg/mL 10,

20, 40, 60, 80, or 100 :g/mL

(-S9); 10, 12.5, 20, 25, 30,

40, 50, 60, 70, 75, 80, 100 or

120 :g/mL (+S9) 

Although there was not a clear dose-response and several of

the increases in percent aberrant cells were within the

historical control range (0.0-4.0%), there was sufficient

reproducible evidence of a positive mutagenic effect in the

presence and absence of S9. 

[positive]

870.5375

In vitro

mammalian

cytogenetics in

V79 Chinese

Hamster Lung

Fibroblasts

46203322 (2002)

Acceptable/Guideline 

10, 15, 20, 30, 40, 45, 60, 75,

80, 90 and 100 μg/mL (-S9);

3.8, 7.5, 15, 30, 45, 60 and 90

:g/mL (+S9)

There was an increase in the percent aberrant cells that

exceeded the historical control range with/without S9

metabolic activation.

[positive]

870.5395

In Vivo

mammalian

cytogenetics 

micronucleus

mice

46203325 (2002)

Acceptable/Guideline

2000 mg/kg (bone marrow

toxicity was not induced)

There were no marked increases observed in mean net nuclear

grains (NNG) or percent cells in repair (NNG $5) at 2 or 16

hours post-dosing compared to controls. 

[negative]

870.5550

UDS in

mammalian

cells 

46203329 (2001)

Acceptable/Guideline

 0, 1.17, 2.34, 4.69, 9.38,

18.75, 37.5, 75, 150, 300, or

600 :g/mL (cytotoxic levels

$300 μg/mL) 

There were no marked increases observed in the mean grains

per nucleus or mean NNG in either trial. Negative for

increased UDS up to limit dose. 

[negative]

870.5550

UDS in

mammalian

cells 

46203325 (2002)

Acceptable/Guideline 

2000 mg/kg

There were no marked increases observed in mean net nuclear

grains (NNG) or percent cells in repair (NNG $5) at 2 or 16

hours post-dosing compared to controls.

[negative]

870.6200

Acute

neurotoxicity

rats - gavage

46203331, 46203330 (2003)

Acceptable/Guideline

0, 100, 500 or 2000 mg/kg

NOAEL = 2000 mg/kg (for neurotoxicity)

LOAEL was not determined.

870.6200

Subchronic

neurotoxicity

rats -gavage

46203332 (2003)

Acceptable/Guideline

0, 10, 100 or 500 mg/kg/day

NOAEL = 500 mg/kg/day (for neurotoxicity) 

LOAEL was not determined
Guideline No./

Study Type

MRID No. (year)/

Classification /Doses

Results

27

870.7485

MetabolismRat

46203333-46203336 (2001)

Acceptable/Guideline

0.5 or 300 mg/kg

Approximately 90% of the orally gavaged dose was absorbed

from the gastrointestinal tract. Approximately, 90% of the

absorbed dose was excreted in the urine and feces in 72 hours

and excretion was nearly complete in 7 days. Excretion in the

urine ranged from 59-78% and in feces 20-25%. Tissue

distribution data indicated no significant accumulation in the

body. Billiary excretion study did not indicate enterohepatic

circulation. No parent compound was detected in the urine,

feces or bile. Major metabolite in the urine and feces was the

hydrolysis product M2. Major metabolites in the urine were

M2 (65%-85%) and M4 (5-13%) and in the feces 50%-70%)

and M4 (25%-35%) depending up on the dose. There were

no sex related differences in the absorption, distribution,

excretion or qualitative profile of the metabolites.

870.7600

In Vivo Dermal

penetration- Rat

46203342 (2003)

Acceptable/Guideline

0.05, 0.25 or 4.0 mg/rat (EC

100 formulation)

Low dose= 4%, 14%, 18% at 4, 10, 24 hours

Mid dose= 1%, 2%, 4% at 4, 10, 24 hours

High dose= 17%, 30%, 36% at 4, 10, 24 hours

4.2 FQPA Hazard Considerations

4.2.1 Adequacy of the Toxicity Data Base

The toxicology database for pinoxaden is complete. The following acceptable studies are

available:

< Developmental toxicity studies in rats and rabbits

< 2-Generation reproductive toxicity studies in rats

< Acute and Subchronic neurotoxicity studies in rats

4.2.2 Evidence of Neurotoxicity

There is no concern for neurotoxicity resulting from exposure to pinoxaden. Clinical signs

(hunched postured, piloerection, decreased activity and/or cold to touch) were sometimes

observed in a few rats, mice and dogs at high dose levels. These signs are non-specific in

nature, and are sometimes exhibited in compromised animals. Other signs indicative of

neurotoxicity [i.e. ataxia, tremors, tilting head, convulsions or altered gait (staggered gait or

circling)] were not observed in these or in other studies with pinoxaden.

• In the chronic toxicity/carcinogenicity study in rats (MRID 4624809), an increased

incidence of hunched posture was observed in the $250 mg/kg/day males (31-38%

treated vs 18% controls) and 500 mg/kg/day females (28% treated vs 19% controls). 

Piloerection was increased in the $250 mg/kg/day males (30-41% treated vs 18%

controls). The incidences of these signs were significant (p#0.05) only in the 250

mg/kg/day males. The petitioner stated that these findings in the males usually occurred

in the same week as the animals were found dead or sacrificed in extremis. The earliest

occurrences of hunched posture were as follows: males at 250 (week 32) and 500 (week
28

31) mg/kg/day and females at 500 (week 11) mg/kg/day. Piloerection was first observed

in the 250 mg/kg/day males at week 64 and in the 500 mg/kg/day males at week 31. 

There were no other increases in clinical signs of toxicity.

• In the 90-day dog study (MRID 46203242), males and females in the 250 mg/kg/day

group had decreased activity and were cold to the touch.

• In the 13-week study in mice (MRID 446203241), at 1000 mg/kg/day piloerection (neck

fur raised) was observed at the cageside in both sexes (50-80% treated vs 0-10%

controls) and during the functional observation battery(FOB; n=10) at an increased

incidence in 2-5 males on weeks 1 and 3-6, and 4 females on week 3 and 1 female on

weeks 4 and 9. 

1) Rat Acute Neurotoxicity Study (MRID 46203331)

Executive Summary: In an acute oral neurotoxicity study (MRIDs 46203331 and 46203330),

pinoxaden (97.2% a.i., Batch # EZ005006) in 0.5% carboxymethylcellulose/0.1% Tween 80 in

distilled water was administered in a single-dose by gavage (10 mL/kg) to non-fasted Wistar rats

(10/sex/dose) at doses of 0, 100, 500, or 2000 mg/kg (limit dose). All animals were observed for

up to 14 days post-dosing. FOB and motor activity were evaluated pretreatment and on days 1

(at approximately 2-3 hours post-dosing), 8, and 15. At termination, 5 rats/sex/group were

perfused in situ for neurohistological examination. Positive control data were not provided.

No compound-related effects on mortality, clinical signs, body-weight, body-weight gain, food

consumption, FOB, motor activity, or gross and histopathology were observed at any dose in

either sex.

The LOAEL was not observed. The NOAEL is 2000 mg/kg (limit dose).

No evidence of neurotoxicity was observed.

The study is classified as Acceptable/Guideline and satisfies the Guideline requirement (OPPTS

870.6200a; OECD 424) for an acute neurotoxicity screening battery in rats. 

2) Rat Subchronic Neurotoxicity Study (MRID 446203332)

Executive Summary: In a subchronic neurotoxicity study (MRID 46203332), pinoxaden

(97.2% a.i., Batch # EZ005006) in 0.5% carboxymethylcellulose/0.1% (w/w) Tween 80 in

distilled water was administered to 12 Wistar rats/sex/dose via gavage at doses of 0, 10, 100, or

500 mg/kg bw/day for up to 90 days. All animals were evaluated for FOB and motor activity at

weeks -1, 2, 5, 9, and 14. At study termination, 5 animals/sex/group were perfused in situ, and

tissues from the control and 500 mg/kg bw/day groups were examined microscopically. Positive

control data were not provided.

Mortality, body-weight, body-weight gain, food consumption and utilization, ophthalmoscopic

evaluations, FOB, motor activity, organ weights, gross necropsy, and neuropathology were

unaffected by treatment.
29

Treatment-related effects were limited to salivation and signs of salivation in the $100 mg/kg

bw/day animals. Salivation was predominantly recorded at clinical examination immediately

prior to dosing, and was absent during the FOB (recorded earlier that day). The petitioner stated

that these findings were due to a behavioral ‘anticipatory’ response to the dosing procedure

rather than a pharmacological or toxicological response to the test material. The reviewers agree

that these findings are likely not toxicologically important; however, the ‘anticipatory’ response

is unlikely due to the dosing procedure itself, otherwise the control and 10 mg/kg bw/day

animals would also show evidence of salivation prior to dosing.

The LOAEL was not observed. The NOAEL is 500 mg/kg bw/day.

There was no evidence of neurotoxicity at any dose tested.

The study is classified as Acceptable/Guideline and satisfies the Guideline requirement (OPPTS

870.6200b) for a subchronic neurotoxicity study in rats. 

4.2.3 Developmental Toxicity Studies

Developmental Toxicity Study in Rats (MRID 46203305)

Executive Summary: In a developmental toxicity study (MRIDs 46203305 and 46203304),

pinoxaden (Batch # EZ005006; 97.2% a.i.) in 0.5% (w/w) carboxymethylcellulose + 0.1% (w/w)

aqueous Tween 80 was administered daily by oral gavage at a dose volume of 10 mL/kg bw to

24 female Wistar (Hanlbm:WIST [SPF]) rats/group at dose levels of 0, 3, 30, 300, or 800

mg/kg/day on gestation days (GD) 6 through 20. All dams were killed on GD 21; their fetuses

were removed by cesarean section and examined.

There were no effects of treatment on gross pathology.

At 300 mg/kg/day, decreases (p#0.05) in body-weight gains were observed on GD 6-20

(decreased 12%). Food consumption was also decreased (p#0.01) on GD 6-11 and 16-21

(decreased 10%).

At 800 mg/kg/day, 1 dam was killed in extremis on GD 17. Prior to death, this animal exhibited

respiratory sounds, dyspnea, hunched posture, reduced activity, and piloerection. The death of

the dam on GD 17 may be considered as due to treatment. Additionally at this dose, piloerection

was observed on GD 15-21 in 2-18/24 rats. Body-weights were decreased (p#0.05) on GD 19-

21 (decreased 6-10%), and body-weight gains were decreased (p#0.01) during treatment (GD 6-

21) both uncorrected (decreased 33%) and corrected (decreased 103%) for gravid uterus weight. 

Gravid uterus weights were also decreased (decreased 12%; p#0.05). Food consumption was

decreased (p#0.01) throughout treatment (GD 6-21; decreased 20-28%).

The maternal LOAEL is 300 mg/kg bw/day, based on decreased body-weight gains and

food consumption. The maternal NOAEL is 30 mg/kg bw/day.

There were no abortions, premature deliveries, or dead fetuses. No effects of treatment were

noted on numbers of litters, live fetuses, resorptions (early, late, or complete litter), or on sex
30

ratio or post-implantation losses. There were no treatment-related external, visceral, or skeletal

malformations or variations.

Incomplete ossification of the interparietal bone and metatarsal 1 was observed in the 300 and

800 mg/kg/day groups compared to concurrent and historical controls. Additionally, at 800

mg/kg/day, increased (p#0.05) incidence of incomplete ossification of the occipital, parietal, and

frontal bones, and unossified hind limb calcaneus, metatarsal 1, and the distal phalanx of

posterior digits 2, 3, and 4 were observed compared to concurrent and historical controls. 

Decreases (p#0.01) were also observed in fetal body-weights in both sexes (decreased 6-8%).

The developmental LOAEL is 300 mg/kg bw/day, based on delays in skeletal ossification in

the skull and hind digits. The developmental NOAEL is 30 mg/kg bw/day.

This study is classified acceptable/guideline (OPPTS 870.3700a) and satisfies the guideline

requirements for a developmental toxicity study in the rat.

Developmental Toxicity Study in Rabbits (MRID 46203303)

Executive Summary: The petitioner has submitted 5 studies (MRIDs 46203303, 46203245,

46203246, 46203301, and 46203302) evaluating the effects of pinoxaden on developing rabbits. 

In the initial guideline developmental toxicity study (MRID 46203246), a dose of 100 mg/kg

bw/day of pinoxaden administered by oral gavage was maternally toxic, and single fetal

incidences (in separate litters) of defects of the diaphragm were observed. However, semen from

a single buck had been used to inseminate all the dams whose offspring presented with these

defects. Further, familial relationships of dams and bucks used in the study were not fully

known. Therefore, two investigative non-guideline studies (MRIDs 46203301 and 46203302)

were performed to investigate a possible parental etiology for the findings and to study the

reproducibility of the outcome. Finally, a full repeat of the initial guideline study was performed

using the whole range of original dose levels tested. This repeat study (MRID 46203303) is

considered the definitive study and is presented in this risk assessment. All other supporting

studies are summarized as Appendices at the end of this document.

In a developmental toxicity study (MRIDs 46203303, 46203245, 46203246, 46203301,

46203302, and 46203306), pinoxaden (97.2% a.i.; Batch # EZ005006) in 0.5% (w/w)

carboxymethylcellulose + 0.1% (w/w) aqueous Tween 80 was administered daily by oral gavage

at a dose volume of 4 mL/kg bw to 24 female Russian (Chbb:HM) rabbits/group at dose levels of

0, 3, 10, 30, or 100 mg/kg bw/day on gestation days (GD) 7 through 28. All does were killed on

GD 29; their fetuses were removed by cesarean section and examined.

There were no effects of treatment on gross pathology.

Maternal toxicity was observed at 100 mg/kg/day. One doe was killed in extremis on GD 26

after exhibiting severe body-weight loss, recumbent position, and reduced activity during the 2

previous days. Additionally, 2 does were killed on GD 27 after showing signs of abortion.

At 100 mg/kg/day, when considering only females with viable fetuses, body-weight gains were

decreased (p#0.05) by 55% overall (GD 0-29) when uncorrected for gravid uterus weight. 
31

Additionally, uncorrected body-weight gains were decreased (not significant by 63% during

treatment (GD 7-29). Gravid uterus weights were similar to controls. Food consumption was

decreased (p#0.01) by 47% during GD 7-12. When considering all pregnant females, bodyweight gains were decreased (p#0.01) by 84% during treatment and by 65% overall. Food

consumption was decreased (p#0.05) by 33-60% during GD 7-20.

The maternal LOAEL is 100 mg/kg bw/day, based on morbid condition in one rabbit

(mortality), clinical signs of toxicity in a morbid rabbit, abortion, decreased body weights,

body weight gains and food consumption. The maternal NOAEL is 30 mg/kg bw/day.

There were no treatment-related external, visceral, or skeletal malformations or variations. Fetal

growth was unaffected by treatment.

At 100 mg/kg/day, 2 does were killed on GD 27 after showing signs of abortion, and 3 dead

fetuses were observed. There were no premature deliveries. When considering all pregnant

females, an increased (p#0.05) number of does had complete early litter resorptions (7/24),

causing increased (p#0.01) total and early resorptions per doe and post-implantation loss, and

decreased (p#0.01) live litter size per doe. No effects of treatment were noted on live fetuses,

late resorptions, or sex ratio. Therefore, the data were analyzed excluding these 7 does. When

considering only females with viable fetuses, no effects of treatment were noted on numbers of

litters, live fetuses, resorptions (early, late, or complete litter), sex ratio, or post-implantation

losses.

The developmental LOAEL is 100 mg/kg bw/day, based on increased incidence of complete

early litter resorption. The developmental NOAEL is 30 mg/kg bw/day.

This study is classified acceptable/guideline (OPPTS 870.3700b) and satisfies the Guideline

requirements for a developmental study in the rabbit.

Developmental Toxicity Study in Rabbits (MRID 46203303)

Original developmental toxicity study

This developmental toxicity study was intended to be the definitive study on the effects of NOA

407855 on development in the rabbit; however, interpretation of the data were problematic. 

Therefore, additional studies were planned. This study served as the range-finding study for the

definitive developmental toxicity study (MRID 46203303). Only a summary is provided as

requested by the Agency.

In a developmental toxicity study (MRID 46203246), NOA 407855 (Pinoxaden; 97.2% a.i.;

Batch # EZ005006) in 0.5% (w/w) carboxymethylcellulose + 0.1% (w/w) aqueous Tween 80

was administered daily by oral gavage at a dose volume of 4 mL/kg bw to 24 female Russian

(Chbb:HM) rabbits/group at dose levels of 0, 3, 10, 30, or 100 mg/kg bw/day on gestation days

(GD) 7 through 28. All does were killed on GD 29; their fetuses were removed by cesarean

section and examined.

No effects of treatment were noted on survival, clinical signs, or gross pathology.
32

At 100 mg/kg bw/day, maternal body weights were decreased (p#0.05) by 3-4% on GD 18-25. 

Body weight gains were decreased during treatment (GD 7-29) both uncorrected (968%; not

significant [NS]) and corrected (971%; p#0.01) for gravid uterus weight. Additionally, overall

(GD 0-29) body weight gains were decreased by 63% (NS), and food consumption was

decreased (p#0.05) by 19-51% during treatment. Gravid uterus weights were similar to controls.

The maternal LOAEL is 100 mg/kg bw/day, based on decreased body weights, body weight

gains, and food consumption. The maternal NOAEL is 30 mg/kg bw/day.

At 100 mg/kg bw/day, decreases (p#0.05) were observed in fetal body weights for males

(912%), females (913%), and both sexes (911%).

There were no abortions, premature deliveries, or complete litter losses. One dead fetus was

observed in each of the 10 and 100 mg/kg bw/day groups. No effects of treatment were noted on

numbers of litters, live fetuses, resorptions (early or late), or on sex ratio or post-implantation

losses. No treatment-related external or skeletal findings were observed.

Diaphragmatic hernia, a malformation, was observed in the 30 (0.6% fetuses; 4.8% litters) and

100 (1.06% fetuses; 10.0% litters) mg/kg bw/day groups compared to 0 concurrent controls. The

100 mg/kg bw/day group was above the range of historical controls (0.0-0.9% fetuses; 0.0-5.9%

litters). Fissure of the diaphragm, an anomaly, was also observed in one 100 mg/kg bw/day fetus

(1.00% fetuses; 5.0% litters) compared to 0 concurrent and historical controls. Although these

defects occurred in fetuses from different litters, it was observed that the affected does were

artificially inseminated with semen from a single male rabbit. Therefore, an additional series of

studies (MRIDs 46203301, 46203302, and 46203303) were planned to determine if the visceral

defects were a result of treatment or associated with the parent animals.

The developmental LOAEL is 100 mg/kg bw/day based on decreased fetal body weights,

and increased incidence of diaphragmatic hernia and fissure. The developmental NOAEL

is 30 mg/kg bw/day.

This developmental toxicity study is classified as acceptable/guideline, and satisfies the

Guideline requirements for a developmental toxicity study in the rabbit.

Developmental Toxicity Study in Rabbits (MRID 46203303)

Range-finding study for a developmental toxicity study

This range-finding study was performed to establish the dose levels used in the developmental

toxicity study (MRID 46203246) summarized in Appendix 1. Only a summary is provided as

requested by the Agency.

In a range-finding developmental toxicity study (MRID 46203245), NOA 407855 (Pinoxaden;

97.2% a.i.; Batch # EZ005006) in 0.5% (w/w) carboxymethylcellulose + 0.1% (w/w) aqueous

Tween 80 was administered by oral gavage at a dose volume of 4 mL/kg to 8 female Russian

(Chbb:HM) rabbits/group at nominal dose levels of 0, 30, 150, 300, 700, or 1000 mg/kg bw/day
33

on gestation days (GD) 7-28. All does were killed on GD 29; their fetuses were removed by

cesarean section and examined.

No effects of treatment were noted on gross pathology. Gravid uterus weights were comparable

to controls.

At$300 mg/kg bw/day, mortality and clinical signs of toxicity were observed. One 300 mg/kg

bw/day female was found dead on GD 18, three 700 mg/kg bw/day females were found dead on

GD 11-12, and two 1000 mg/kg bw/day females were found dead on GD 8-9. Hunched posture,

reduced activity, and severe body weight loss were also observed. Therefore, surviving animals

in these groups were killed for humane reasons prior to scheduled termination.

At 30 mg/kg bw/day, maternal body weight gains were decreased (not significant [NS]) by 21%

during treatment (GD 7-29) and by 9% overall (GD 0-29). Food consumption was also

decreased (NS) by 2-19% on GD 7-29.

At 150 mg/kg bw/day on GD 15, one doe was found in moribund condition and was killed for

humane reasons, and one doe exhibited hunched posture and reduced activity. Body weights

were generally decreased (p#0.05) by 5-6% on GD 23-29. Body weight gains were decreased

(p#0.01) by 87% during treatment and by 68% overall. Food consumption was decreased (not

significant [NS]) by 20-62% on GD 7-24 (p#0.01 on GD 7-12).

The maternal LOAEL is 30 mg/kg bw/day, based on decreased body weight gains and food

consumption. The maternal NOAEL was not observed.

At 150 mg/kg bw/day, decreases (NS) were observed in fetal body weights for males (912%),

females (99%), and both sexes (912%). Additionally, 4/8 does had complete litter resorptions. 

Increased (p#0.05) early resorptions per doe (4.9 treated vs 0.3 controls) and increased (NS)

post-implantation loss (62.0% treated vs 7.3% controls) were observed.

There were no abortions or premature deliveries. One dead fetus was observed in the controls. 

No effects of treatment were noted on numbers of litters, live fetuses, late resorptions, or on sex

ratio. No treatment-related external or visceral findings were observed.

The developmental LOAEL is 150 mg/kg bw/day based on decreased fetal body weights

and increased early and complete litter resorptions. The developmental NOAEL is 30

mg/kg bw/day.

This range-finding developmental toxicity study is classified as acceptable/non-guideline.

Developmental Toxicity Study in Rabbits (MRID 46203303)

Non-standard developmental toxicity study using one male control

This developmental toxicity study was performed to clarify the potential association of a single

buck in the occurrence of diaphragmatic defects observed in the fetuses of the initial

developmental study (MRID 46203246) discussed in Appendix 1. Only a summary is provided

as requested by the Agency.
34

In a non-guideline developmental toxicity study (MRID 46203302), NOA 407855 (Pinoxaden;

97.2% a.i.; Batch # EZ005006) in 0.5% (w/w) carboxymethylcellulose + 0.1% (w/w) aqueous

Tween 80 was administered daily by oral gavage at a dose volume of 4 mL/kg bw to 24 female

Russian (Chbb:HM) rabbits/group at dose levels of 0 or 100 mg/kg bw/day on gestation days

(GD) 7 through 28. All does were killed on GD 29; their fetuses were removed by cesarean

section and examined. All does were artificially inseminated with diluted semen from a single

male. This male previously sired fetuses having defects of the diaphragm; however, since these

fetuses were exposed to NOA 407855, it was unclear whether the defects were genetic in origin

or treatment-related.

No effects of treatment were noted on survival or gross pathology.

At 100 mg/kg bw/day, piloerection was observed in one female beginning on GD 24. This

animal was killed on GD 26 following abortion. Also, when considering only females with

viable fetuses, maternal body weights were decreased (p#0.05) by 5% on GD 21 and 24-29. 

Body weight gains were decreased (p#0.01) during treatment (GD 7-29) both uncorrected

(944%) and corrected (9342%) for gravid uterus weight. Additionally, overall (GD 0-29) body

weight gains were decreased (p#0.01) by 34%, and food consumption was decreased (p#0.05)

by 17-32% during GD 7-20. Gravid uterus weights were similar to controls. Similar results

were observed when calculations were performed on all pregnant females.

The maternal LOAEL is 100 mg/kg bw/day, based on decreased body weights, body weight

gains, and food consumption. The maternal NOAEL was not observed.

There were no premature deliveries. At 100 mg/kg bw/day, 1 doe aborted on GD 26, and 2 dead

fetus were observed. No effects of treatment were noted on numbers of litters, live fetuses,

resorptions (early, late, or complete litter), or on sex ratio or post-implantation losses.

No treatment-related external or skeletal findings were observed. Spina bifida, a malformation,

was observed in one 100 mg/kg bw/day fetus (1.47% fetuses; 5.9% litters) compared to 0

concurrent and historical controls. However, historical data provided by the breeder showed this

defect does spontaneously occur in this breed of rabbit. Also at 100 mg/kg bw/day, enlarged gall

bladder, a variation, was noted (13.65% fetuses; 29.4% litters) vs concurrent controls (2.46%

fetuses; 15.8% litters), and enlarged stomach, a variation, was observed (0.84% fetuses; 5.9%

litters) vs 0 concurrent controls. These findings were considered incidental. The occurrence of

diaphragmatic hernia previously observed was not reproducible.

The developmental LOAEL was not observed. The developmental NOAEL is 100 mg/kg

bw/day.

This developmental toxicity study is classified as acceptable/non-guideline.

Developmental Toxicity Study in Rabbits (MRID 46203303)

Non-standard developmental toxicity study using one male control

This developmental toxicity study was performed to clarify the potential association of a single

buck in the occurrence of diaphragmatic defects observed in the fetuses of the initial
35

developmental study (MRID 46203246) discussed in Appendix 1. Only a summary is provided

as requested by the Agency.

In a non-guideline developmental toxicity study (MRID 46203301), NOA 407855 (Pinoxaden;

97.2% a.i.; Batch # EZ005006) in 0.5% (w/w) carboxymethylcellulose + 0.1% (w/w) aqueous

Tween 80 was administered daily by oral gavage at a dose volume of 4 mL/kg bw to 24 female

Russian (Chbb:HM) rabbits/group at dose levels of 0 or 100 mg/kg bw/day on gestation days

(GD) 7 through 28. All does were killed on GD 29; their fetuses were removed by cesarean

section and examined. All does were artificially inseminated with diluted semen from a total of

12 males; the male that previously sired fetuses having defects of the diaphragm was not used in

this study.

No effects of treatment were noted on clinical signs or gross pathology.

At 100 mg/kg bw/day, 1 female was found dead on GD 23, and another was killed on GD 27

because of abortion. Also, when considering only females with viable fetuses, maternal body

weights were decreased (p#0.05) by 5% on GD 22-23, and 29. Body weight gains were

decreased (p#0.05) during treatment (GD 7-29) both uncorrected (935%) and corrected (9171%)

for gravid uterus weight. Additionally, overall (GD 0-29) body weight gains were decreased

(p#0.05) by 21%, and food consumption was decreased (p#0.01) by 30% during GD 7-12. 

Gravid uterus weights were similar to controls. Similar results were observed when calculations

were performed on all pregnant females.

The maternal LOAEL is 100 mg/kg bw/day, based on mortality, decreased body weights,

body weight gains, and food consumption. The maternal NOAEL was not observed.

There were no premature deliveries or dead fetuses. At 100 mg/kg bw/day, 1 doe was killed on

GD 27 following abortion, and 1 female was determined to have aborted at cesarean section. 

Additionally, when considering all pregnant females, 2 females had complete litter resorptions,

and 19 early resorptions were observed, causing increased (p#0.05) post-implantation losses

(25.7% treated vs 3.4% controls). An increase (p#0.05) in males per litter was noted (64.3%)

compared to controls (40.9%). No effects of treatment were noted on numbers of litters, live

fetuses, or late resorptions. When cesarean section data were examined for only females with

viable fetuses, only the increased percentage of males per litter were observed.

No treatment-related external or skeletal findings were observed. At 100 mg/kg bw/day, a

hindlimb position anomaly, a variation, was noted (2.27% fetuses; 9.1% litters), and enlarged

gall bladder, a variation, was observed (1.52% fetuses; 9.1% litters), both vs 0 concurrent

controls. Since each of these abnormalities were noted in single fetuses, these findings were

considered incidental. The occurrence of diaphragmatic hernia previously observed was not

reproducible.

The developmental LOAEL was not observed. The developmental NOAEL is 100 mg/kg

bw/day.

This developmental toxicity study is classified as acceptable/non-guideline.
36

4.2.4 Reproductive Toxicity Study

Rat 2-Generation Reproduction Study (MRID 46203308) 

Executive Summary: In a two-generation reproduction toxicity study (MRIDs 46203308 and

46203307), pinoxaden technical (97.2% a.i.; Batch # EZ005006) was administered daily by oral

gavage in 0.5% (w/v) carboxymethylcellulose in 0.1% (w/v) aqueous polysorbate 80 at a dose

volume of 10 mL/kg to Wistar (HanIbm: WIST) rats (30 animals/sex/dose) at dose levels of 0,

10, 50, 250 and 500 mg/kg bw/day. The P and F1 parents were dosed for 10 weeks before they

were mated to produce the F1 and F2 litters. The F1 pups were weaned on postnatal day (PND)

22, and 30 pups/sex/group (1 pup/sex/litter as nearly as possible) were randomly selected as

parents of the F2 generation.

In the parental animals, no treatment-related effects were observed on survival, clinical signs,

body-weight, overall body-weight gains, food consumption, estrous cycle length or periodicity,

sperm measurements, numbers of ovarian follicles or corpora lutea, pre-coital interval, duration

of gestation, or on mating, fertility, gestation, or parturition indices.

At 500 mg/kg bw/day, water consumption was increased (p<0.05) throughout the study in the P

and F1 males (incr. 23-82%), and during pre-mating in the females (incr. 16-67%). Increases

(p<0.01) were observed in absolute and relative (to body) kidney weights in the P (incr. 13-21%)

and F1 (incr. 10-16%) males. Increased incidences of the following were observed compared to

controls: I) renal pelvic dilatation at necropsy in the P males; ii) slight to marked dilatation of

the renal pelvis during microscopic pathology in the P males; iii) minimal to moderate renal

tubular atrophy in the P and F1 males; iv) chronic nephropathy in the P and F1 males; v) minimal

to moderate renal tubular atrophy in the P females; and vi) minimal to moderate chronic

nephropathy in the P and F1 females.

The LOAEL for parental toxicity is 500 mg/kg bw/day, based on increased water

consumption, renal tubular atrophy, and chronic nephropathy in both sexes, and increased

incidence of renal pelvic dilatation in the males. The NOAEL is 250 mg/kg bw/day.

In the offspring, no treatment-related effects were observed on post-implantation survival, live

birth, viability, or lactation indices, on the sex ratio, clinical signs, sexual maturation, organ

weights, gross pathology, or microscopic pathology.

At 500 mg/kg bw/day, in the F1 pups, body-weights were decreased (p<0.05) on PND 7-21 in the

males (decreased 7-10%), and on PND 4-21 in the females (decreased 7-11%). Overall (PND 0-

21) body-weight gains were also decreased (p<0.01) in both sexes (decreased 7-8%). In the F2

males, body-weights were decreased (p<0.05) on PND 7-14 (decreased 6-7%).

The LOAEL for offspring toxicity is 500 mg/kg bw/day, based on decreased body-weights

and body-weight gains in the F1 pups, and decreased body-weights in the F2 males. The

NOAEL is 250 mg/kg bw/day.

The LOAEL for reproductive performance was not observed. The NOAEL for

reproductive performance is 500 mg/kg bw/day.
37

This study is classified as Acceptable/Guideline and satisfies the Guideline requirements

(OPPTS 870.3800; OECD 416) for a two-generation reproduction study in the rat.

4.2.5 Additional Information from Literature Sources

There is no additional information on the toxicity of pinoxaden that is currently available in the

literature as demonstrated by a TOXNET search of 3/24/2005.

4.2.6 Pre-and/or Postnatal Toxicity

4.2.6.1 Determination of Susceptibility

There is no evidence of qualitative and/or qualitative evidence of increased susceptibility of rat

and rabbit fetuses to in utero exposure to pinoxaden. There is no evidence of increased

qualitative and/or quantitative evidence of increased susceptibility to pinoxaden following prenatal exposure in a 2-generation reproduction study in rats. 

4.2.6.2 Degree of Concern Analysis and Residual Uncertainties for Pre and/or Post-natal

Susceptibility

No evidence of increased susceptibility to pinoxaden following pre-natal exposure in a 2-

generation reproduction study in rats. There are no concerns or residual uncertainties for pre-

/post-natal toxicity. 

4.3 Recommendation for a Developmental Neurotoxicity Study

There is no concern for neurotoxicity resulting from exposure to pinoxaden. The clinical signs

(hunched postured, piloerection, decreased activity, cold to touch) observed in rats and dogs

were at very high dose levels and are sometimes exhibited in compromised animals. Other signs

indicative of neurotoxicity, i.e. ataxia, tremors, tilting head, convulsions or altered gait (i.e.,

staggered gait or circling) were not observed in these or in other studies with pinoxaden. 

Neurotoxicity was not observed in the acute (MRID 46203331) and subchronic (MRID

46203332) rat neurotoxicity studies. No indication of abnormalities in the development of the

fetal nervous system was observed in the prenatal developmental toxicity studies in either rats or

rabbits at dose levels up to 800 and 100 mg/kg/day, respectively. No evidence of

neuropathology was observed in the database.

Therefore, a developmental neurotoxicity study in rats is not required.

4.4 Hazard Identification and Toxicity Endpoint Selection

4.4.1 Acute Reference Dose (aRfD) - Females age 13-49

Study Selected: Developmental Toxicity - Rabbit § OPPTS 870.3700
38

MRID No.: 46203303

Executive Summary: See Section 4.2.3 (second study).

Dose and Endpoint for Establishing an aRfD: Developmental NOAEL = 30 mg/kg/day,

based on increased incidence of complete early litter resorption at the LOAEL of 100 mg/kg/day.

UF: 100 (10x for interspecies extrapolation and 10x for intraspecies variations)

Comments about Study/Endpoint and Uncertainty Factor: This study provides the lowest

dose attributable to a single-dose developmental effect (increased incidence of early resorptions)

applicable to the female 13-49 years of age. 

4.4.2 Acute Reference Dose (aRfD) - General Population

An endpoint of concern attributable to a single dose effect was not identified in the database. 

Decreased body weights and body weight gains were seen during gestation days 7-12 in the

developmental toxicity study in rabbits; these effects were considered marginal. Therefore, this

study and endpoint were not used for this risk assessment. Quantification of acute risk to general

population including infants and children is not required.

4.4.3 Chronic Reference Dose (cRfD)

Study Selected: Developmental Toxicity - Rabbit § OPPTS 870.3700

MRID No.: 46203303

Executive Summary: See Section 4.2.3 (second study)

Dose and Endpoint for Establishing a cRfD: Maternal NOAEL = 30 mg/kg/day, based on

morbid condition in one rabbit (mortality), abortion, decreased body weights, body weight gains

and food consumption seen at the LOAEL of 100 mg/kg/day. 

UF: 100 (10x for interspecies extrapolation and 10x for intraspecies variations)

Comments about Study/Endpoint and Uncertainty Factor: This study provides the lowest

NOAEL in the database for chronic effects such as decreases in body weights and body weight

gains. 

Acute RfD = 30 mg/kg (NOAEL) = 0.3 mg/kg/day

 100 (UF)
39

4.4.4 Incidental Oral Exposure (Short and Intermediate Term)

Study Selected: Developmental Toxicity - Rabbit § OPPTS 870.3700

MRID No.: 46203303

Executive Summary: See Section 4.2.3 (second study) 

Dose and Endpoint: Maternal NOAEL = 30 mg/kg/day, based on morbid condition in one

rabbit (mortality), abortion, decreased body weights, body weight gains and food consumption

seen at the LOAEL of 100 mg/kg/day. 

Comments about Study/Endpoint: This endpoint would be appropriate for the route, duration

of exposure (1-30 days; 1 - 6 months) and population of concern (infants and children), if

residential uses were added to the use pattern. This study provides lowest NOAEL in the

database. 

4.4.5 Dermal Absorption

Dermal Absorption Factor: 40%

Dermal absorption is estimated to be 40% based on the results of the in vivo/in vitro dermal

penetration study in rats using the EC 100 formulation. (The emulsifiable concentrate (EC)

formulation will be used in the field and is believed to be much more absorbable than technical

pinoxaden without the emulsifiers.) In this study with the EC formulation, 36% of the dose

applied to the skin of rats in an in vivo study was absorbed over the following day (24 hours

post-exposure). Absorption of the EC formulation from excised rat skin in an in vitro study was

65.5% of the applied dose after 24 hours post-exposure. For excised human skin, absorption of

radioactivity was minimal regardless of the dosing vehicle and dose level in an in vitro study. 

Absorption accounted 0.36-1.84% of the applied dose after a 24-hour exposure at doses from 5-

400 :g/cm2

. Thus, in the in vitro studies, absorption was considerably higher in rat skin than in

human skin. Additionally, absorption of the test substance in the in vivo rat study was

comparable to the absorption in the in vitro study with rat skin. Therefore, the data suggest that

in vivo absorption in humans would be considerably lower than in the rat. 

4.4.6 Dermal Exposure (Short, Intermediate and Long Term)

Study Selected: Developmental Toxicity - Rabbit § OPPTS 870.3700

MRID No.: 46203303

Chronic RfD = 30 mg/kg (NOAEL) = 0.3 mg/kg/day

 100 (UF)
40

Executive Summary: See Section 4.2.3 (second study)

Dose and Endpoint: Maternal NOAEL = 30 mg/kg/day, based on morbid condition in one

rabbit (mortality), abortion, decreased body weights, body weight gains and food consumption

seen at the LOAEL of 100 mg/kg/day. 

UF: 100 (10x for interspecies extrapolation and 10x for intraspecies variations)

Comments about Study/Endpoint: No toxicity was seen in a 28-day dermal toxicity study in

rats, however, this study was not selected because this study does not measure skeletal variations

seen in the developmental study that occurred at lower doses when using a 40% dermalabsorption factor.

4.4.7 Inhalation Exposure (Short, Intermediate and Long Term)

Study Selected: Developmental Toxicity - Rabbit § OPPTS 870.3700

MRID No.: 46203303

Executive Summary: See Section 4.2.3 (second study) 

Dose and Endpoint: Maternal NOAEL = 30 mg/kg/day, based on morbid condition in one

rabbit (mortality), abortion, decreased body weights, body weight gains and food consumption

seen at the LOAEL of 100 mg/kg/day. 

Comments about Study/Endpoint: This study provides lowest NOAEL in the database. No

inhalation study is available in the database.

4.4.8 Margins of Exposure

The target Margins of Exposure (MOEs) for occupational exposure risk assessments are as

follows:
41

Route

 

 Duration

Short-Term

(1-30 days)

Intermediate-Term

(1 - 6 Months)

 Long-Term

(> 6 Months)

Occupational (Worker) Exposure

Dermal 100 100 100

Inhalation 100 100 100

Residential (Non-Dietary) Exposure

Oral

N/A

Dermal

Inhalation

For Occupational exposure: This is based on the conventional uncertainty factor of 100X

(10X for intraspecies variation and 10X for interspecies extrapolation).

For Residential exposure: Not applicable, since there are no residential uses.

4.4.9 Recommendation for Aggregate Exposure Risk Assessments

No residential uses are proposed for pinoxaden at this time. Therefore, aggregate risk consists of

exposure from food and drinking water sources only. Acute and chronic aggregate risks were

assessed. 

To better evaluate aggregate risk associated with exposure through food and drinking water, OPP

is no longer comparing Estimated Drinking Water Concentration (EDWCs) generated by water

quality models with Drinking Water Levels of Comparison (DWLOC) . Instead, OPP is now

directly incorporating the actual water quality model output concentrations into the risk

assessment. This method of incorporating water concentrations into our aggregate assessments

relies on actual CSFII-reported drinking water consumptions and more appropriately reflects the

full distribution of drinking water concentrations. 

4.4.10 Classification of Carcinogenic Potential

The Cancer Assessment Review Committee (CARC) concluded that the submitted studies are

inadequate to evaluate carcinogenic potential of pinoxaden due to the absence of an acceptable

mouse carcinogenicity study. In accordance with the EPA Guidelines for Carcinogen Risk

Assessment (March, 2005), the Committee classified pinoxaden into the category “Data Are

Inadequate for An Assessment of Human Carcinogenic Potential”.
42

Table 4.4 Summary of Toxicological Doses and Endpoints for Pinoxaden for Use in

Human Risk Assessments

Exposure

Scenario

Dose Used in

Risk

Assessment, UF 

Special FQPA

SF* and Level of

Concern for Risk

Assessment

Study and Toxicological

Effects

Acute Dietary

(females 13-49)

NOAEL = 30

mg/kg/day

UF = 100

Acute RfD = 0.30

mg/kg

FQPA SF - 1X

aPAD = 0.30 mg/kg

Developmental toxicity - rabbit

LOAEL = 100 mg/kg/day based on

increased incidence of complete early

litter resorption

Acute Dietary

(general

population)

N/A N/A An endpoint of concern attributable to

a single dose effect was not identified

in the database. Quantification of

acute risk to general population

including infants and children is not

required.

Chronic Dietary

(all populations)

NOAEL = 30

mg/kg/day

UF = 100

Chronic RfD = 0.30

mg/kg/day

FQPA SF - 1X

cPAD = 0.30

mg/kg/day

Developmental toxicity - rabbit

LOAEL = 100 mg/kg/day based on

morbid condition in one rabbit

(mortality), clinical signs of toxicity in

a morbid rabbit, abortion, decreased

body weights, body weight gains and

food consumption.

Incidental Oral

Short-Term

(1 - 30 days)

NOAEL = 30

mg/kg/day

LOC = MOE - 100

(residential includes

the FQPA SF)

Developmental toxicity - rabbit

LOAEL = 100 mg/kg/day based on

morbid condition in one rabbit

(mortality), clinical signs of toxicity in

a morbid rabbit, abortion, decreased

body weights, body weight gains and

food consumption.

Incidental Oral

Intermediate-Term

(1 - 6 months)

NOAEL = 30

mg/kg/day

LOC = MOE=100

(residential includes

the FQPA SF)

Developmental toxicity - rabbit

LOAEL = 100 mg/kg/day based on

morbid condition in one rabbit

(mortality), clinical signs of toxicity in

a morbid rabbit, abortion, decreased

body weights, body weight gains and

food consumption.

Dermal 

Short-Term

(1 - 30 days)

NOAEL = 30

mg/kg/day

LOC = MOE=100

(residential includes

the FQPA SF)

LOC for occupational

=100

Dermal-absorption

rate=40%

Developmental toxicity - rabbit

LOAEL = 100 mg/kg/day based on

morbid condition in one rabbit

(mortality), clinical signs of toxicity in

a morbid rabbit, abortion, decreased

body weights, body weight gains and

food consumption.

Dermal 

Intermediate-Term

(1 - 6 months)

NOAEL = 30

mg/kg/day

LOC = MOE=100

(residential includes

the FQPA SF)

LOC = MOE=100

(Occupational)

Dermal-absorption

rate=40%

Developmental toxicity - rabbit

LOAEL = 100 mg/kg/day based on

morbid condition in one rabbit

(mortality), clinical signs of toxicity in

a morbid rabbit, abortion, decreased

body weights, body weight gains and

food consumption.
Exposure

Scenario

Dose Used in

Risk

Assessment, UF 

Special FQPA

SF* and Level of

Concern for Risk

Assessment

Study and Toxicological

Effects

43

Dermal 

Long-Term

(> 6 months)

NOAEL = 30

mg/kg/day

LOC = MOE=100

(residential includes

the FQPA SF)

LOC = MOE=100

(Occupational)

Dermal-absorption

rate=40%

Developmental toxicity - rabbit

LOAEL = 100 mg/kg/day based on

morbid condition in one rabbit

(mortality), clinical signs of toxicity in

a morbid rabbit, abortion, decreased

body weights, body weight gains and

food consumption.

Inhalation 

Short-Term

(1 - 30 days)

NOAEL = 30

mg/kg/day

LOC = MOE=100

(residential includes

the FQPA SF)

LOC = MOE=100

(Occupational)

Inhalation-absorption

rate=100%

Developmental toxicity - rabbit

LOAEL = 100 mg/kg/day based on

morbid condition in one rabbit

(mortality), clinical signs of toxicity in

a morbid rabbit, abortion, decreased

body weights, body weight gains and

food consumption.

Inhalation 

Intermediate-Term

(1 - 6 months)

NOAEL = 30

mg/kg/day

LOC = MOE=100

(residential includes

the FQPA SF)

LOC = MOE=100

(Occupational)

Inhalation-absorption

rate=100%

Developmental toxicity - rabbit

LOAEL = 100 mg/kg/day based on

morbid condition in one rabbit

(mortality), clinical signs of toxicity in

a morbid rabbit, abortion, decreased

body weights, body weight gains and

food consumption.

Inhalation 

Long-Term

(> 6 months)

NOAEL = 30

mg/kg/day

LOC = MOE=100

(residential includes

the FQPA SF)

LOC = MOE=100

(Occupational)

Inhalation-absorption

rate=100%

Developmental toxicity - rabbit

LOAEL = 100 mg/kg/day based on

morbid condition in one rabbit

(mortality), clinical signs of toxicity in

a morbid rabbit, abortion, decreased

body weights, body weight gains and

food consumption.

Cancer (oral,

dermal, inhalation)

Classification: Data Are Inadequate for An Assessment of Human Carcinogenic

Potential

UF = uncertainty factor, FQPA SF = Special FQPA safety factor, NOAEL = no observed adverse-effect level,

LOAEL = lowest observed adverse-effect level, PAD = population adjusted dose (a = acute, c = chronic) RfD =

reference dose, MOE = margin of exposure, LOC = level of concern, NA = Not Applicable

* Refer to Section 4.5
44

4.5 Special FQPA Safety Factor

Based on the hazard characterization data, the pinoxaden risk assessment team recommended the

special FQPA SF be reduced to 1x because there are no concerns and no residual uncertainties

with regard to pre- and/or postnatal toxicity. The pinoxaden risk assessment team evaluated the

quality of the exposure data and based on these data, recommended that the special FQPA SF be

reduced to 1x. This recommendation is based on the following:

• The dietary exposure assessment utilizes proposed tolerance level residues and 100%

crop treated information for all commodities. By using these screening-level

assessments, chronic exposures/risks will not be underestimated.

• The dietary drinking water assessment utilizes values generated by model and associated

modeling parameters which are designed to provide conservative, health protective, highend estimates of water concentrations.

• There are no residential uses proposed for pinoxaden at this time.

4.6 Endocrine Disruption

EPA is required under the FFDCA, as amended by FQPA, to develop a screening program to

determine whether certain substances (including all pesticide active and other ingredients) “may

have an effect in humans that is similar to an effect produced by a naturally occurring estrogen,

or other such endocrine effects as the Administrator may designate.” Following

recommendations of its Endocrine Disruptor and Testing Advisory Committee (EDSTAC), EPA

determined that there was a scientific basis for including, as part of the program, the androgen

and thyroid hormone systems, in addition to the estrogen hormone system. EPA also adopted

EDSTAC’s recommendation that the Program include evaluations of potential effects in wildlife. 

For pesticide chemicals, EPA will use FIFRA and, to the extent that effects in wildlife may help

determine whether a substance may have an effect in humans, FFDCA authority to require the

wildlife evaluations. As the science develops and resources allow, screening of additional

hormone systems may be added to the Endocrine Disruptor Screening Program (EDSP).

In the available toxicity studies on pinoxaden, there was no estrogen, androgen, and/or thyroid

mediated toxicity.

When additional appropriate screening and/or testing protocols being considered under the

Agency’s EDSP have been developed, pinoxaden may be subjected to further screening and/or

testing to better characterize effects related to endocrine disruption.

5.0 Public Health Data

Pinoxaden is a new active ingredient. Therefore, public health information is not available.

6.0 Exposure Characterization/Assessment

6.1 Dietary Exposure/Risk Pathway
45

6.1.1 Residue Profile

The nature of the residue in wheat and livestock is adequately understood for the petitioned use

based on acceptable metabolism studies conducted on wheat, lactating goats, and laying hens. In

both wheat and livestock, pinoxaden undergoes hydrolysis of the ester moiety, hydroxylation and

conjugation with sugars. In most of the metabolites identified, the three-ring backbone of

pinoxaden remains intact. However, some of the metabolites identified in wheat are different

than those in livestock metabolism studies. The residues of concern for the purpose of tolerance

enforcement and risk assessment for wheat, barley and poultry are pinoxaden and its metabolites

M2, M4 (free and conjugated), and M6; and for ruminants are pinoxaden and its metabolites M2

and M4 (free and conjugated). The residues of concern for rotational crops are pinoxaden, M2,

M3 (free and conjugate), M10, and M11.

Combined residues of pinoxaden and M2 (as M2), and residues of M4 and M6 were quantitated

by adequately-validated high-performance liquid chromatography (HPLC)/tandem mass

spectrometry (MS/MS). The proposed enforcement methodology for plants needs to pass a

petition method validation (PMV) by the Analytical Chemistry Laboratory/Biological and

Economics Analysis Division (ACL/BEAD) before the method can be deemed adequate for

tolerance enforcement. The proposed enforcement methodology for livestock is not currently

adequate because it was not validated for residues of pinoxaden and M2. Based on its

similarities to the plant enforcement method, HED expects that the proposed livestock method

will be adequate for quantification of pinoxaden and M2. Submission of the validation data

for pinoxaden and M2 may thus be a condition of registration.

The petitioner submitted magnitude of the residue data for wheat and barley. The field trial

studies were conducted using the proposed application scenarios and in the regions suggested in

OPPTS 860.1500 for establishment of a tolerance in/on the crops requested. The petitioner also

submitted the required processing studies for the proposed crops. The field trial and processing

residue data were generated using adequately-validated analytical methods (storage intervals

have also been validated). Based on the field trial and processing studies, HED concludes that

the tolerances listed in the recommendation section are appropriate. A revised Section F is

requested; no additional field trial or processing data are necessary.

The petitioner submitted feeding studies on ruminant and poultry. Although the residues were

<LOQ, tolerances are still required since the studies were not conducted at >10X. Since the

livestock tissues were not analyzed for pinoxaden and M2, those residues were conservatively

estimated to be at LOQ (based on plant and livestock metabolism studies) in calculation of

maximum combined residues for tolerance setting. 

The submitted storage stability studies support the storage intervals and conditions of M4 and

M6 in livestock commodities and that of M2, M4, and M6 in whole wheat, straw and grain. 

Although, pinoxaden and M2 were not included in livestock storage stability study, since the

levels of those analytes in the ruminant tissues are not expected to exceed LOQ (based on plant

and livestock metabolism studies), and that the M4 is the major residue in feed items, no further

storage stability data are required for livestock samples. However, a study demonstrating the

storage stability of M2, M4 and M6 in wheat-processed fractions (aspirated grain fractions

(AGF), bran, flour, middling, shorts and germ) for a minimum duration of 6 month is required.
46

The petitioner submitted confined rotational crop studies for spring and winter wheat, head

lettuce, mustard greens, radish and turnip under various plant-back intervals (PBIs). M3, M10,

and M11 were >0.01 ppm in rotated spring wheat forage and fodder with 15-day and/or 30-day

PBIs; thus, M3, M10, and M11 (in addition to the parent and M2) were determined to be

residues of concern. At the 29- or 30-day PBI, none of the metabolites identified (M2, M3, M8,

M9, M10, M11 & M32) were quantitated at levels greater that 0.01 ppm, except M3 in spring

wheat forage; at the 120-day PBI, all the identified metabolites were quantitated at levels lower

than 0.01 ppm in spring wheat forage. Therefore, the proposed PBIs should be amended to

limit the 30-day PBI to leafy and root crops only and also to add a 120-day PBI for other

cereal grains (besides wheat and barley) and all other crops (besides leafy and root crops). 

Pinoxaden was not detected in any rotated crop matrices at any PBIs (from 15 to 365 days) since

it was hydrolyzed rapidly (disappeared by day 3) in soil yielding M2. M2 was further

hydroxylated forming M3 which was taken up from the soil by the rotated crops. 

Provided a revised Section F is submitted, and the Agency validations of the proposed analytical

enforcement methods are successful, HED concludes there are no residue chemistry toxicology

or occupational/residential exposure data requirements that would preclude the establishment of

a conditional registration and the following permanent tolerances:

1) For the combined residues of pinoxaden, and its metabolites M2, free and conjugated forms

of M4, and M6, calculated as pinoxaden, in/on the following commodities:

Wheat, bran . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.0 ppm

Barley, grain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.9 ppm

Barley, hay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.5 ppm

Barley, straw . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.0 ppm

Barley, bran . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.6 ppm

Egg . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.06 ppm

Poultry, fat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.06 ppm

Poultry, meat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.06 ppm

Poultry, meat byproduct .................................................. 0.06 ppm
47

HED recommends that conversion of conditional registration to unconditional registration may

be considered upon submission of the following residue chemistry data:

C Additional storage stability data for wheat and barley processed fractions. 

C Additional validation data for pinoxaden and M2 residues in livestock commodities

(ruminant and poultry).

6.1.2 Acute and Chronic Dietary Exposure and Risk

Residues of Concern:

The residues of concern for the purpose of tolerance enforcement and risk assessment for wheat

and barley and poultry are pinoxaden and its metabolites M2, M4 (free and conjugated), and M6;

and for ruminants are pinoxaden and its metabolites M2 and M4 (free and conjugated). The

residues of concern for rotational crops are pinoxaden, M2, M3 (free and conjugate), M10, and

M11.

Acute and chronic dietary risk assessments were conducted using the Dietary Exposure

Evaluation Model (DEEM-FCIDTM, Version 2.0) which uses food consumption data from the

USDA’s Continuing Surveys of Food Intakes by Individuals (CSFII) from 1994-1996 and 1998. 

Drinking water was directly incorporated into the dietary analyses. 

Acute Dietary Exposure Results and Characterization

The Tier 1 acute analysis for females 13-49 years old assumed 100% crop treated, DEEM 7.81

default processing factors and tolerance-level residues. Drinking water was incorporated

directly into the dietary assessment using the annual peak concentration for surface water

generated by the PRZM -EXAMS model as a high-end estimate (0.00076 ppm; 90th percentile

annual daily maximum). 

The resulting risk estimates for females 13-49 years old is 1.5% of the aPAD at the 95th

percentile. 

Since drinking water was included directly into the acute dietary analysis, the risk estimate

represents acute aggregate risk from pinoxaden.

Chronic Dietary Exposure Results and Characterization

The Tier 1 chronic analysis assumed 100% crop treated, DEEM 7.81 default processing factors

and tolerance-level residues. Drinking water was incorporated directly into the dietary

assessment using the annual mean concentration for surface water generated by the PRZMEXAMS model as a high-end estimate (0.000473 ppm; 90th percentile annual mean). 

The chronic dietary exposure estimate for the general population is 0.9% of the cPAD. The

estimate for the highest exposed population subgroup (children 1-2 years old) is 2.1% of the

cPAD. 
48

Since drinking water was included directly into the chronic dietary analysis, the risk

estimate represents chronic aggregate risk from pinoxaden.

A cancer dietary risk assessment was not performed since CARC concluded that “Data Are

Inadequate for An Assessment of Human Carcinogenic Potential.”

Table 6.1.2. Summary of Dietary Exposure and Risk for Pinoxaden Including Drinking

Water

Population 

Subgroup

Acute Dietary 1 Chronic Dietary 

Dietary

Exposure

(mg/kg/day)

% aPAD

Dietary

Exposure

(mg/kg/day)

% cPAD

U.S. Population (total)

N/A

0.0026 0.9

All Infants 

(< 1 year old) 0.0014 0.5

Females 13-49 years

old 0.0046 1.5 0.002 0.7

Children 1-2 years old

N/A

0.0063 2.1

Children 3-5 years old 0.0061 2.0

Children 6-12 years old 0.0042 1.4

Youth 13-19 years old 0.0025 0.8

Adults 20-49 years old 0.0021 0.7

Adults 50+ years old 0.00059 0.2

1. Acute dietary exposure is from 95th percentile of exposure distribution.

These acute and chronic dietary exposure and risk estimates are conservative since they assumed

100% crop treated, DEEM 7.81 default processing factors and tolerance-level residues and were

based on screening-level estimates of drinking water concentrations generated by the PRZMEXAMS models. They could be further refined through the use of anticipated residues,

empirical processing factors and percent crop treated data, as well as refined drinking water

estimates.

6.2 Water Exposure/Risk Pathway

Hydrolysis of pinoxaden is pH dependent and faster under basic conditions. Aqueous photolysis

of pinoxaden is not a major dissipation route when exposed to sunlight. In soil, photolysis is

also not a significant pathway for degradation for pinoxaden without hydrolytic degradation.
49

Acceptable laboratory studies showed that pinoxaden degrades rapidly under aerobic soil

metabolism conditions with half-lives ranges from 2-3 days forming the major degradate M2,

which degrades further to form the degradate M3.

Volatility is not a significant route of dissipation. The major degradates (M2 and M3) are

considered to be mobile based on Freundlich Kads values ranging from 0.06-128 ml/g, and 0856-

0.28 ml/g, respectively, in three test soils (loamy sand, loam, silty clay loam textures).

EFED currently has no monitoring data for pinoxaden in surface or groundwater.

Surface Water

EFED has conducted a Tier II drinking water assessment for pinoxaden and its major

transformation products, M2 and M3, using the Tier II screening models PRZM1 and EXAMS2

with the Index Reservoir and Percent Crop Area adjustment (IR-PCA PRZM/EXAMS). The

surface water concentrations of pinoxaden were modeled based on its use on wheat in North

Dakota (aerial application) at the maximum application rate of 0.0624 lb ai/acre. According to

U.S.D.A., in 2004, North Dakota’s wheat production is ranked second in the Nation, behind

Kansas. The half-lives were calculated based on the summation of toxic pinoxaden residues.

The Index Reservoir represents a potentially vulnerable drinking water source based on the

geometry of an actual reservoir and its watershed in a specific area (Illinois), using regional 

specific cropping patterns, weather, soils, and other factors. 

The PCA is a generic watershed-based adjustment factor which represents the portion of a

watershed planted to a crop or crops. The PCA will be applied to pesticide concentrations

estimated for the surface water component of the drinking water exposure assessment using

PRZM/EXAMS with the Index Reservoir scenario.

The IR-PCA PRZM/EXAMS modeling results indicate that pinoxaden has the potential to

contaminate surface waters by spray drift, and runoff in areas with large amounts of annual

rainfall. 

Groundwater

No monitoring data are available with which to estimate concentrations of pinoxaden in

groundwater at the present time. Therefore, the SCI-GROW model was used to estimate

potential groundwater concentrations of pinoxaden and its degradates M2 and M3.

Groundwater EECs predicted using the SCI-GROW screening model are substantially less (0.13

ppb) than those estimated for surface water using PRZM and EXAMS. However, the major

degradate M2 should persist longer in groundwater than in surface water. 
50

Table 6.2 Estimated environmental concentrations in surface and groundwater for

pinoxaden and its major degradates, M2 and M3 from use on wheat.

model EDWCs (μg/L)

Aerial Application

Surface water/ peak (90th percentile annual daily max.) 0.76

Surface water/ 90th percentile annual mean) 0.47

Surface water/ 36-year overall mean 0.32

Groundwater 0.13

a

 From the Tier II PRZM-EXAMS - Index Reservoir model. Input parameters are based on applying a percent crop

area Adjustment to Tier 2 Surface Water Model Estimates for Pesticide Drinking Water Exposure Assessments. 12-

07-99; maximum application rate of 0.0624 lb ai/A, mean Kads = 4.2 mL/g, aerobic soil metabolism half-life of 29.4

days.

b

 From the SCI-GROW model assuming a maximum seasonal use rate of 0.0624 lb ai/A, a median Koc of 4.2, and a

aerobic soil metabolism half-life of 29.4 days.

6.3 Residential (Non-Occupational) Exposure/Risk Pathway

There are no proposed or existing residential uses of pinoxaden.

6.3.1 Spray Drift

Spray drift is always a potential source of exposure to residents nearby to spraying operations. 

This is particularly the case with aerial application, but, to a lesser extent, could also be a

potential source of exposure from the ground application method employed for pinoxaden. HED

has been working with the Spray Drift Task Force, EPA Regional Offices and State Lead

Agencies for pesticide regulation and other parties to develop the best spray drift management

practices. On a chemical by chemical basis, HED is now requiring interim mitigation measures

for aerial applications that must be placed on product labels/labeling. HED has completed its

evaluation of the new data base submitted by the Spray Drift Task Force, a membership of U.S.

pesticide registrants, and is developing a policy on how to appropriately apply the data and the

AgDRIFT computer model to its risk assessments for pesticides applied by air, orchard airblast

and ground hydraulic methods. After the policy is in place, HED may impose further

refinements in spray drift management practices to reduce off-target drift with specific products

with significant risks associated with drift.

7.0 Aggregate Risk Assessments and Risk Characterization

In accordance with the FQPA, HED must consider and aggregate (add) pesticide exposures and

risks from three major sources: food, drinking water, and residential exposures. In an aggregate

assessment, exposures from relevant sources are added together and compared to quantitative

estimates of hazard (e.g., a NOAEL or PAD), or the risks themselves can be aggregated. When

aggregating exposures and risks from various sources, HED considers both the route and

duration of exposure.
51

For pinoxaden, no residential uses are proposed. Therefore, aggregate risk will consist of

exposure from food and drinking water sources. Acute and chronic aggregate risks were

calculated. 

To better evaluate aggregate risk associated with exposure through food and drinking water, OPP

is no longer comparing Estimated Drinking Water Concentration (EDWCs) generated by water

quality models with Drinking Water Levels of Comparison (DWLOC) . Instead, OPP is now

directly incorporating the actual water quality model output concentrations into the risk

assessment. This method of incorporating water concentrations into our aggregate assessments

relies on actual CSFII-reported drinking water consumptions and more appropriately reflects the

full distribution of drinking water concentrations. 

7.1 Acute Aggregate Risk

To assess acute aggregate risk, HED incorporated drinking water estimates directly into the

dietary analysis. Results are reported in Table 6.1.2.

An endpoint of concern attributable to a single dose effect was not identified in the database for

the general population. Quantification of acute risk to general population including infants and

children is not required.

The Tier 1 acute analysis for females 13-49 years old assumed 100% crop treated, DEEM 7.81

default processing factors (when empirical data were not available) and tolerance-level residues. 

Drinking water was incorporated directly into the dietary assessment using the annual peak

concentration for surface water generated by the PRZM -EXAMS model as a high-end estimate

(0.00076 ppm; 90th percentile annual daily maximum). 

The resulting acute dietary risk estimate for females 13-49 years old is 1.5 % of the aPAD at the

95th percentile. 

7.2 Short-Term Aggregate Risk

Since there are no existing or proposed residential uses for pinoxaden, short-term aggregate risk

was not calculated. 

7.3 Intermediate-Term Aggregate Risk

Since there are no existing or proposed residential uses for pinoxaden, intermediate-term

aggregate risk was not calculated. 

7.4 Long-Term (Chronic) Aggregate Risk

To assess chronic aggregate risk, HED incorporated drinking water estimates directly into the

dietary analysis. Results are reported in Table 6.1.2.
52

The Tier 1 chronic analysis assumed 100% crop treated, DEEM 7.81 default processing factors

(when empirical data were not available) and tolerance-level residues. Drinking water was

incorporated directly into the dietary assessment using the annual mean concentration for surface

water generated by the PRZM-EXAMS model as a high-end estimate (0.000473 ppm; 90th

percentile annual mean). 

The chronic dietary exposure estimate for the general population is 0.9% of the cPAD. The

estimate for the highest exposed population subgroup (children 1-2 years old) is 2.1% of the

cPAD. 

7.5 Aggregate Cancer Risk

The CARC concluded that data are inadequate for an assessment of human carcinogenic

potential due to the absence of an acceptable mouse carcinogenicity study. Based on the weight

of the evidence, HED believes that pinoxaden is not likely to pose a cancer risk. Therefore, an

aggregate cancer risk assessment was not performed.

8.0 Cumulative Risk Characterization/Assessment

Unlike other pesticides for which EPA has followed a cumulative risk approach based on a

common mechanism of toxicity, EPA has not made a common mechanism of toxicity finding for

pinoxaden and any other substances, and pinoxaden does not appear to produce a toxic

metabolite produced by other substances. For the purposes of this tolerance action, therefore,

EPA has not assumed that pinoxaden has a common mechanism of toxicity with other

substances. For information regarding EPA’s efforts to determine which chemicals have a

common mechanism of toxicity and to evaluate the cumulative effects of such chemicals, see the

policy statements released by EPA’s OPP concerning common mechanism determinations and

procedures for cumulating effects from substances found to have a common mechanism on

EPA’s website at http://www.epa.gov/pesticides/cumulative/.

9.0 Occupational Exposure/Risk Pathway

9.1 Short-/Intermediate-/Long-Term Handler Risk

Based upon the proposed use pattern, HED believes the most highly-exposed occupational

pesticide handlers (i.e., mixers, loaders, applicators) are:

1) Mixer/loader using open-pour loading of liquids in support of aerial operations

2) Applicator using open-cab ground-boom equipment

3) Aerial applicator (pilot)

Applicators using open-cab ground equipment typically experience greater exposures than aerial

applicators however the estimated exposure for an aerial applicator is presented. HED expects

that most occupational handler exposures will be short-term in duration (1 - 30 days). The

ExpoSAC maintains that it is possible for a commercial applicator to be exposed to intermediateterm exposures (1 - 6 months) by treating farm after farm for the same pest complex, however,

HED believes that the probability for intermediate-term exposures is very low. Since the doses
53

and endpoints for short- and intermediate-term risk assessment are the same, risks calculated

below represent both exposure durations.

It is expected that some private (i.e., grower) applicators may perform all tasks, that is, mix, load

and apply the material. However, HED ExpoSAC draft Standard Operating Procedure (SOP)

(29 March 2000) directs that although the same individual may perform all tasks, in some cases

they shall be assessed separately. 

The available exposure data for combined mixer/loader/applicator scenarios are limited in

comparison to the monitoring of these two activities separately. These exposure scenarios are

outlined in the PHED Surrogate Exposure Guide (August 1998). HED has adopted a

methodology to present the exposure and risk estimates separately for the job functions in some

scenarios and to present them as combined in other cases. Most exposure scenarios for handheld equipment (such as hand wands, backpack sprayers, and push-type granular spreaders) are

assessed as a combined job function. With these types of hand-held operations, all handling

activities are assumed to be conducted by the same individual. The available monitoring data

support this and HED presents them in this way. Conversely, for equipment types such as fixedwing aircraft, groundboom tractors, or air-blast sprayers, the applicator exposures are assessed

and presented separately from those of the mixers and loaders. By separating the two job

functions, HED determines the most appropriate levels of PPE for each aspect of the job without

requiring an applicator to wear unnecessary PPE that might be required for a mixer/loader (e.g.,

chemical resistant gloves may only be necessary during the pouring of a liquid formulation). 

No chemical-specific data were available with which to assess potential exposure to pesticide

handlers. The estimates of exposure to pesticide handlers are based upon surrogate study data

available in PHED (v. 1.1, 1998). For pesticide handlers, it is HED standard practice to present

estimates of dermal exposure for “baseline” that is, for workers wearing a single layer of work

clothing consisting of a long-sleeved shirt, long pants, shoes plus socks and no protective gloves

as well as with a single layer of work clothing and the use of protective gloves or other PPE as

might be necessary. 

Short- and intermediate-term handler risks were estimated. A dermal-absorption factor of 40%

was use to calculate occupational risks. HED assumed 100% inhalation absorption. The level of

concern for occupational pesticide handlers and agricultural workers is a MOE of at least 100. 
54

Table 9.1 Estimated Handler Exposure and Risk from the Use of Pinoxaden on Wheat

and Barley

Unit Exposure1

mg a.i./lb handled

Applic.

Rate2

Units

Treated3

Per Day

Average Daily

Dose4

mg a.i./kg bw/day

NOAEL5

mg a.i./kg

bw/day

MOE6

Mixer/Loader -Liquid - Open-pour - Supporting Aerial Operations

Dermal:

No Gloves 2.9 HC

With Gloves 0.023 HC

Inhal. 0.0012 MC

0.062 lb

a.i./A 1200 A

Dermal:

No Gloves 1.2

With Gloves 0.0098

Inhal 0.0013

30 No Gloves 24

With Gloves 2,700

Applicator - Ground-boom - Open Cab

Dermal:

No Gloves 0.014 HC

With Gloves 0.014 MC

Inhal 0.00074 HC

0.062 lb

a.i./A 200 A

Dermal:

No Gloves 0.001

With Gloves 0.001

Inhal 0.00013

30 No Gloves 27,000

With Gloves 27,000

Aerial Applicator (pilots not required to wear gloves)

Dermal:

No Gloves 0.0022 MC

Inhal. 0.000068 MC

0. 0623 lb

a.i./A 1200 A

Dermal:

No Gloves 0.00094

Inhal 0.000073

30

No Gloves 30,000

1. Unit Exposures are taken from “PHED Surrogate Exposure Guide”, Estimates of Worker Exposure from PHED, v. 1.1, August, 1998. Dermal

= Single Layer Work Clothing No Gloves; Single Layer Work Clothing With Gloves; Inhal. = Inhalation. Units = mg a.i./pound of active

ingredient handled. Data Confidence: LC = Low Confidence, MC = Medium Confidence, HC = High Confidence.

2. Applic. Rate. = Taken from proposed label.

3. Units Treated are taken from “Standard Values for Daily Acres Treated in Agriculture”; SOP No. 9.1. Science Advisory Council for

Exposure; Revised 5 July 2000; 

4. Average Daily Dose = Unit Exposure * Applic. Rate * Units Treated * absorption factor (40 % dermal; 100 % inhalation ÷ Body-weight (70

kg since NOAELs are identified from a developmental study with maternal effects). 

5. NOAEL = 30 mg a.i./kg bw/day

6. MOE = NOAEL ÷ ADD. Short-term dermal and short-term inhalation exposures are summed and divided into the NOAEL. The dermal and

inhalation endpoints are the same, are identified from the same study and have the same NOAELs for all exposure durations. 

Provided that mixer/loaders use protective gloves as specified on the proposed label, all MOEs

are greater than 100 and therefore do not exceed HED’s level of concern.

9.2 Short/Intermediate/Long-Term Postapplication Risk

There is a potential for post-application exposure of agricultural workers to pesticides during the

course of typical agricultural activities. HED in conjunction with the ARTF has identified a

number of post-application agricultural activities that may occur. HED has also identified TCs 

(cm2/hr) relative to the various activities which expresses the amount of foliar contact over time,

during each of the activities. The highest (i.e., most conservative) TC relative to the early, postemergence treatment of wheat is for scouting with a TC of 100 cm2/hr. Post-application

exposure is herein assessed using the highest proposed rate of application and a TC of 100

cm2/hr. 

The TCs used in this assessment are from an interim TC SOP developed by the ExpoSAC using

proprietary data from the ARTF database (SOP # 3.1). It is the intention of the ExpoSAC that

this SOP will be periodically updated to incorporate additional information about agricultural
55

practices in crops and new data on TCs. Much of this information will originate from exposure

studies currently being conducted by the ARTF, from further analysis of studies already

submitted to HED, and from studies in the published scientific literature.

Lacking compound-specific DFR data, HED assumes 20% of the application rate is available as

DFR on day zero after application. This is adapted from the ExpoSAC SOP No. 003 (7 May

1998 - Revised 7 August 2000). 

The following convention may be used to estimate post-application exposure. 

Average Daily Dose (ADD) (mg a.i./kg bw/day) = DFR μg/cm2

 * TC cm2/hr * hr/day * 0.001

mg/μg * 1/70 kg bw 

 and where:

Surrogate Dislodgeable Foliar Residue (DFR) = application rate * 20% available as dislodgeable

residue * (1-D)t

 * 4.54 x 108 μg/lb * 2.47 x 10-8 A/cm2 . 

TC =100 cm2/hr

ˆ DFR = 0.062 lb a.i./A * 0.20 * (1-0)0 * 4.54E8 μg a.i./lb * 2.47E-8A/cm2 = 0.14 μg/cm2

PDR = 0.14 μg/cm2 * 0.001 mg/μg * 100 cm2/hr * 8 hr/day = 0.112 mg a.i./day * 0.40 (dermalabsorption rate) ÷ 70 kg bw = 0.00064 mg a.i./kg bw/day

MOE = NOAEL ÷ PDR 

ˆ 30 mg a.i./kg bw/day ÷ 0.00064 mg a.i./kg bw/day = 47,000 

This estimate is considered to be a screening-level estimate (i.e., conservative, protective). 

HED’s level of concern for occupational risk is a MOE of at least 100. In this case, the MOE is

greater than 100. Therefore, short-term, intermediate-term or long-term duration postapplication dermal risks are not of concern for agricultural workers. Post-application inhalation

exposure is expected to be negligible.

9.3 Occupational Handler and Postapplication Cancer Risk

The CARC concluded that data are inadequate for an assessment of human carcinogenic

potential due to the absence of an acceptable mouse carcinogenicity study. Based on the weight

of the evidence, HED believes that pinoxaden is not likely to pose a cancer risk. Therefore, an

aggregate cancer risk assessment was not performed.

Restricted-Entry Level (REI)

The proposed label lists a 48 hour REI. Pinoxaden is classified in Acute Toxicity Category III

for acute dermal toxicity. It is classified in Category IV for acute inhalation toxicity and primary

skin irritation. It is not a dermal sensitizer. It is classified in Acute Toxicity Category I for

primary eye irritation. Therefore, the proposed REI is in compliance with the interim worker
56

protection standard (WPS) restricted entry interval and should be protective of agricultural

workers re-entering treated crop sites.

10.0 Data Needs and Label Requirements

Toxicology - none.

Occupational Exposure - none.

Residue Chemistry

860.1200 Proposed Use 

860.1340 Residue Analytical Methods

Plant Commodity Method

The proposed plant enforcement methods need to pass a PMV by Agency chemists at

ACL/BEAD before the method can be deemed adequate for tolerance enforcement. Method

117-01 has been forwarded to ACL/BEAD for the PMV (DP# 313799, M. Sahafeyan, 3/10/05).

Livestock Commodity Methods

The proposed enforcement method for livestock commodities (Method T001530-03) is

inadequate since it only analyzes for M4 and M6 metabolites and does not analyze for all the

metabolites of concern in ruminants (pinoxaden as M2, M2, and M4) and poultry (pinoxaden as

M2, M2, M4, and M6). Additional validation data for pinoxaden and M2 residues in livestock

commodities (ruminant and poultry) should be submitted.

860.1380 Storage Stability

The freezer storage stability of the metabolites M2, M4 and M6 was not demonstrated in barley

and wheat processed fractions. A study demonstrating the storage stability of M2, M4 and M6 in

barley processed fractions (bran, flour and pearled barley) for a minimum duration of 15 month

is requested. A study demonstrating the storage stability of M2, M4 and M6 in wheat processed

fractions (AGF, bran, flour, middling, shorts and germ) for a minimum duration of 6 month is

requested.

860.1550 Proposed Tolerances

The petitioner is requested to submit a revised Section F as specified in the recommendation

section.
57

Note to RD: The preferred chemical name for pinoxaden is “8-(2,6-diethyl-4-methylphenyl)-

1,2,4,5-tetrahydro-7-oxo-7H-pyrazolo[1,2-d][1,4,5] oxadiazepin-9-yl 2,2-dimethylpropanoate.” 

Tolerances are also required on meat, milk, poultry and egg (MMPE) .

References

CARC Report: Pinoxaden: Report of the Cancer Assessment Review Committee. PC Code

147500. TXR No. 0053391. J. Kidwell. 5/18/05.

Residue Chemistry 

Summary: Pinoxaden in/on Wheat and Barley. PP# 4F6817. Summary of Analytical

Chemistry and Residue Data. M. Sahafeyan. 7/7/2005. 

Dietary Analysis: Pinoxaden- Dietary Exposure Assessment for the Section 3 Registration

Action. M. Sahafeyan. D313800. 7/7/2005.

Occupational 

Assessment: PINOXADEN - Exposure/Risk Assessment for Pesticide Handlers

Applying Pinoxaden to Barley and Wheat. M. Dow. D315788. 4/13/2005.

Drinking Water 

Assessment: Drinking Water Assessment for pinoxaden use on wheat and barley. I.

Abdel-Saheb. D299583. 1/28/05.
58

Appendix 1. Toxicological Data Requirements

The requirements (40 CFR 158.340) for Food Use for pinoxaden are presented below. Use of

the new guideline numbers does not imply that the new (1998) guideline protocols were used.

Test Technical

Required Satisfied

870.1100 Acute Oral Toxicity ...........................

870.1200 Acute Dermal Toxicity ........................

870.1300 Acute Inhalation Toxicity ......................

870.2400 Primary Eye Irritation .........................

870.2500 Primary Dermal Irritation ......................

870.2600 Dermal Sensitization ..........................

yes

yes

yes

yes

yes

yes

yes

yes

yes

yes

yes

yes

870.3100 Oral Subchronic (rodent) .......................

870.3150 Oral Subchronic (nonrodent) ....................

870.3200 21-Day Dermal ..............................

870.3250 90-Day Dermal ..............................

870.3465 90-Day Inhalation ............................

yes

yes

yes

no

no

yes

yes

yes

-

-

870.3700a Developmental Toxicity (rodent) .................

870.3700b Developmental Toxicity (nonrodent) ..............

870.3800 Reproduction ................................

yes

yes

yes

yes

yes

yes

870.4100a Chronic Toxicity (rodent) ......................

870.4100b Chronic Toxicity (nonrodent) ...................

870.4200a Oncogenicity (rat) ............................

870.4200b Oncogenicity (mouse) .........................

870.4300 Chronic/Oncogenicity .........................

yes

yes

yes

yes

yes

yes

yes

yes

yes

yes

870.5100 Mutagenicity—Gene Mutation - bacterial ..........

870.5300 Mutagenicity—Gene Mutation - mammalian .......

870.5xxx Mutagenicity—Structural Chromosomal Aberrations

870.5xxx Mutagenicity—Other Genotoxic Effects ...........

yes

yes

yes

yes

yes

yes

yes

yes

870.6100a Acute Delayed Neurotox. (hen) ..................

870.6100b 90-Day Neurotoxicity (hen) .....................

870.6200a Acute Neurotox. Screening Battery (rat) ...........

870.6200b 90 Day Neuro. Screening Battery (rat) ............

870.6300 Develop. Neuro ..............................

no

no

yes

yes

no

-

-

yes

yes

-

870.7485 General Metabolism ..........................

870.7600 Dermal Penetration ...........................

yes

yes

yes

yes

Special Studies for Ocular Effects

Acute Oral (rat) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Subchronic Oral (rat) . . . . . . . . . . . . . . . . . . . . . . . . . .

Six-month Oral (dog) ..........................

no

no

no

-

-

-
59

Appendix 2. Non-Critical Toxicology Studies

MRID No. Citation

46203214. Sommer, E.. (2000) Acute Oral Toxicity Study in the Rat (Limit Test). 

Laboratory Study Identification: 20001076. Unpublished study prepared by

Toxicology Novartis Crop Protection AG. August 10, 2000.

Executive Summary: In an acute oral toxicity study (MRID 46203214), 5/sex/dose Wistar rats

(Age: 8 weeks, Weight: 185.9-199.4 g males, 162.6-176.8 g females; Source: RCC Ltd.,

Fullinsdorf, Switzerland) were given a single oral dose of pinoxaden technical(Propanoic acid:

97.2%; Batch #: EZ005006; beige solid) or a control dose of 0.5% w/v carboxymethylcellulose

in 0.1% w/v polysorbate 80 by oral gavage. The study was performed at a limit dose of either

5,000 mg/kg or 0 mg/kg (control). Individual animal body-weights were recorded prior to

dosing, and again on days 7 and 14. Clinical signs of toxicity were made several times postdosing on the initial study day and daily thereafter for 14 days. All animals were necropsied on

study day 14 or immediately after death. 

Oral LD50 Males > 5,000 mg/kg

 Females > 5,000 mg/kg

 Combined > 5,000 mg/kg

Based on the LD50 in rats, pinoxaden technical is classified as EPA Toxicity Category IV.

All control animals survived, gained weight and appeared healthy during the study. No gross

internal findings were observed at necropsy.

For those animals dosed at 5,000 mg/kg clinical signs of toxicity noted included slight soft feces

and hunched posture, but animals recovered from these symptoms by day 1 of the study. One

male was found dead on day 5 post-dosing. Gross necropsy of this animal revealed reddish

small and large intestines and a reddish caecum. The surviving animals all gained weight during

the study and had no gross internal findings at necropsy.

This acute oral study is classified as acceptable. It does satisfy the guideline requirement for an

acute oral study (OPPTS 870.1100; OECD 401) in the rat. The report states that the animals

were housed 5/sex/cage. According to OPPTS Guidelines 870.1100, the animals should be

housed individually. These deviations did not affect the overall acceptability of the study.

46203219 Sommer. E. (2000) Acute Dermal Toxicity Study in the Rat. Laboratory Study

Identification: 20001077. Unpublished study prepared by Toxicology Novartis

Crop Protection AG. August 10, 2000..

Executive Summary: In an acute dermal toxicity study (MRID 46203219), 5/sex/dose Wistar

rats (Age: 8-12 weeks; Weight: 216.4-246.5 g males, 207.1-220.8 g females; Source: RCC Ltd.,

Fullinsdorf, Switzerland), were dermally exposed to either a single application of pinoxaden

technical(Propanoic acid: 97.2%; Batch #: EZ005006; beige solid) at 2,000 mg/kg or a control
60

dose of 0.5% w/v carboxymethylcellulose in 0.1% w/v polysorbate 80. The test material was

evenly applied to the skin, distributed to be sure to cover at least 10% of the animal’s BSA, by

means of a semi-occlusive dressing around the trunk for 24 hours. Individual body-weights were

recorded prior to testing and weekly thereafter Clinical checks for toxicity and dermal irritation

were made several times post-dosing on the initial study day, and at least daily thereafter for 14

days. Checks for mortality were made twice daily. All animals were necropsied on study day

14. 

Dermal LD50 Males > 2,000 mg/kg 

 Females > 2,000 mg/kg 

 Combined > 2,000 mg/kg 

Based on the lack of mortality at 2,000 mg/kg, pinoxaden technicalis classified as EPA Toxicity

Category III.

All animals survived and appeared healthy during the study. All control animals gained weight

and had no gross necropsy findings at study termination. For those animals dosed at 2,000

mg/kg, slight weight loss was noted in 3 females during the first week, but all animals exceeded

their initial body-weight by the end of the study period. At necropsy a slightly granulated kidney

was noted in one male while a dilated left renal pelvis was noted in one female. No gross

internal findings were observed at necropsy for the other animals. 

This acute dermal study is classified acceptable. It does satisfy the guideline requirement for an

acute dermal study (OPPTS 870.1200; OECD 402) in the rat. 

46203221 Decker, U. (2001) NOA 407855 tech.: 4-Hour Acute Inhalation Toxicity Study in

Rats. Laboratory Study Identification: 780816. Unpublished study prepared by

Toxicology Division RCC Ltd. July 5, 2001.

Executive Summary: In an acute inhalation toxicity study (MRID 46203221), 15/sex//dose

Wistar rats (Age: 8-11 weeks; Weight: 237.8-260.3 g males; 190.4-220.9 g females; Source:

RCC Ltd., Fullinsdorf, Switzerland) were exposed via nose-only, flow-past inhalation to

pinoxaden technical(Propanoic acid: 97.2%; Batch #: EZ005006; solid) for 4 hours at

analytically determined concentrations of either 2.249, 3.793 or 5.454 mg/L. The test was

initiated at a concentration of 5.454 mg/L, but due to death in 50% of test animals, the dose was

lowered to 2.249 mg/L. Based on the lack of deaths at this concentration the dose was raised to

3.793 mg/L in order to measure the LC50. Individual body-weights were recorded prior to testing

and on days 4, 8 and 15. The animals were observed for clinical signs of toxicity and mortality

once per hour during the aerosol exposure period, after exposure and at least once a day

thereafter for 15 days or until death. A gross necropsy examination was performed on all the

animals on day 15 or when found dead.

LC50 Males = 4.63 mg/L (80% Confidence Limits: 3.35 – 20.68 mg/l air)

LC50 Females = 6.24 mg/L (No Confidence Limits calculated)

LC50 Combined = 5.22 mg/L (95% Confidence Limits: 4.07 -18.00 mg/l air)
61

Based on the LC50 of 4.63 mg/L for males, pinoxaden technicalis classified as EPA Toxicity

Category IV.

For those animals dosed at 2.249 mg/L, all survived the study. Clinical signs of toxicity noted

during and/or after exposure included laboured respiration, rales (breath sounds), salivation,

ruffled fur, hunched posture and red secretion from the nose (in one animal). Symptoms of

toxicity persisted until day 7 after exposure. The mean body-weight of the animals decreased

during the first 4 days of the study but increased thereafter, exceeding their initial body-weight

by the end of the study. Red discolouration of the lymph nodes was observed in two test animals

at necropsy. No gross necropsy findings were found for the other test animals.

For those animals dosed at 3.793 mg/L, all survived the exposure period. 3/10 animals were

found dead 2 days after the exposure period. Clinical signs of toxicity noted during and/or after

exposure included tachypnea, laboured respiration, rales (breath sounds), salivation, ruffled fur,

hunched posture, restlessness and decreased activity. In one female a swollen abdomen was also

observed. Symptoms of toxicity persisted until day 7 after exposure. The mean body-weight of

the surviving animals decreased during the first 4 days of the study but increased thereafter,

exceeding their initial body-weight by the end of the study. Red discolouration of the lungs was

observed at necropsy in 2/3 of the test animals that died during the study. No gross necropsy

findings were found for the other test animals.

For those animals dosed at 5.454 mg/L, all survived the exposure period. 4/10 animals were

found dead the day after the exposure period. A fifth animal was found dead 3 days after the

exposure period. Clinical signs of toxicity noted during and/or after exposure included

bradypnea, laboured respiration, rales (breath sounds), salivation, ruffled fur, hunched posture,

restlessness and decreased activity. Symptoms of toxicity persisted up to day 7 after exposure. 

The mean body-weight of the surviving animals decreased during the first 4 days of the study but

increased thereafter. Males exceeded their initial body-weight by the end of the study while

females exceeded their initial body-weight. Red discolouration of the lungs was observed at

necropsy in 4/5 of the test animals that died during the study. The other test animal that died had

several dark red foci in the thymus at necropsy. One surviving animal had incompletely

collapsed lungs at necropsy. No gross necropsy findings were found for the other test animals.

This acute inhalation study is classified as acceptable. It does satisfy the guideline requirement

for an acute inhalation study (OPPTS 870.1300; OECD 403) in the rat. 

46203223 Arcelin, G. (2000) NOA 407855 tech.: Primary Eye Irritation Study in Rabbits.

Laboratory Study Identification: 780794. Unpublished study prepared by

Toxicology Division RCC Ltd. December 7, 2000.

Executive Summary: In a primary eye irritation study (MRID 46203223), 1.0 g of pinoxaden

technical(Propanoic acid: 97.2%; Batch #: EZ005006; solid) was instilled into the conjunctival

sac of the left eye of 3 young adult New Zealand albino rabbits (Source: Elevage Scientifique

des Dombes, Chatillon sur Chalaronne, France). The test substance was applied as received

from the sponsor. The untreated right eye served as a control. Animals were then observed at 1,

24, 48, 72 hours and 7, 10, 14, 17 and 21 days post-instillation. Additional observations at 24
62

and 28 days were made for 2 of the animals. Irritation was scored according to Draize. 

Observations for clinical signs of toxicity and mortality occurred daily. 

In this study, the formulation is irritating to the eye. Pinoxaden technicalis classified as EPA

Toxicity Category I. 

One hour after instillation all 3 eyes exhibited corneal opacity (score 1). This irritation persisted

in one animal to 72 hours and in a second to 7 days. In the third animal the opacity increased in

severity (score 2) at day 7 and increased further (score 3) at 17 days. This irritation persisted

through 24 days. One hour after instillation all 3 eyes also exhibited conjunctivitis scores of 1

for redness and 2-3 for chemosis. “Assessment of the sclera could not be performed on a number

of occasions due to swelling of the conjunctivae and/or the production of mucus.” This irritation

persisted up through 21 days in one animal. Discharge was noted 1 hour after instillation and

persisted up to 17 days after treatment in one female. “Yellow and beige remnants of the test

item were evident in the eye or conjuctival sac in all animals at the 1-hour reading. This

persisted in one animal up to 48 hours after treatment.” All animals were free from ocular

irritation by 28 days. No corrosion, iritis or signs of toxicity were noted during the study. 

This study is classified as acceptable. It does satisfy the guideline requirement for a primary eye

irritation study (OPPTS 870.2400; OECD 405) in the rabbit. 

46203225 Arcelin, G. (2000) NOA 407855 tech.: Primary Skin Irritation Study in Rabbits.

Laboratory Study Identification: 780783. Unpublished study prepared by

Toxicology Division RCC Ltd.. October 5, 2000.

Executive Summary: In a primary dermal irritation study (MRID 46203225), 3 young adult

New Zealand albino rabbits (1 male, 2 females; Source: Elevage Scientifique des Dombes,

Chatillon sur Chalaronne, France) were dermally exposed to 0.5 g of pinoxaden

technical(Propanoic acid: 97.2%; Batch #: EZ005006; solid). The test substance was moistened

with 0.1 mL if bi-distilled water, placed on a 6 cm2

 area of a gauze pad, applied to the left flank

on each animal and secured with a semi-occlusive wrap for 4 hours. Animals were then

observed for 72 hours. Dermal irritation was scored according to the Draize system at 1, 24, 48

and 72 hours post-patch removal. Observations for clinical signs of toxicity and mortality

occurred daily.

In this study, the formulation is non-irritating to the skin. Pinoxaden technicalis classified as

EPA Toxicity Category IV. 

No erythema or edema were noted at any point during the study. PII is 0.

This study is classified as acceptable. It does satisfy the guideline requirement for a primary

dermal irritation study (OPPTS 870.2500; OECD 404) in the rabbit. 

46203227 Arcelin, G. (2000) NOA 407855 tech.: Contact Hypersensitivity in Albino

Guinea Pigs, Maximization-Test. Laboratory Study Identification: 780805. 

Unpublished study prepared by Toxicology Division RCC Ltd. November 30,

2000. MRID.
63

Executive Summary: In a dermal sensitization study (MRID 46203227) with pinoxaden

technical(Propanoic acid: 97.2%; Batch #: EZ005006; solid), 15/sex (5/sex for control and

10/sex for test) Himalayan spotted guinea pigs (Weight: 309-376 g males, 298-403 g females

Source: RCC Ltd., Fullinsdorf, Switzerland) were tested using the Magnusson-Kligman Design

method.

During the preliminary testing phase, appropriate concentrations of the test substance to be used

were determined for the intradermal induction (test substance at 5% in vehicle (0.5% CMC +

0.1% Tween 80 in bi-distilled water)), topical induction (test substance at 50 % in vehicle), and

topical challenge (test substance at 50 % in vehicle).

The first induction phase involved 3, 0.1 mL intradermal paired injections into 20 guinea pigs of

the test substance (test substance at 5% in vehicle), test substance and Freund’s Adjuvant, and

Adjuvant alone. Paired injections were also administered to 10 control guinea pigs of the

vehicle, vehicle with Freund’s Adjuvant, and Adjuvant alone. 

One week later, a second induction phase was conducted consisting of a 0.3 mL topical

application of the test substance at 50 % in vehicle applied to a patch of filter paper and placed

on the dose site of the test animals, which was then covered for 48 hours. Twenty-four and 48

hours after patch removal the animals were scored for erythema. The control group was treated

in the same manor with vehicle only. Twenty-three hours prior to this phase the animals were

treated with 0.5 mL of 10% SLS to provoke a mild inflammatory reaction.

Two weeks after the topical application of the induction phase the challenge phase was

conducted by applying 0.2 g of a topical application of the test substance at 50 % in vehicle on

the left flank, and 0.2 mL of vehicle only on the right flank, to both the test and control guinea

pigs for 24 hours. Twenty-four and 48 hours after patch removal the animals were scored for

erythema.

Observations for clinical signs of toxicity and mortality occurred daily.

The procedures were validated using 2-Mercaptobenzothiazole as the positive control substance. 

Based on this study, pinoxaden technicalis not a dermal sensitizer and does not have to be

labelled as such.

During the induction phase, observations at all dose sites for test animals treated with the test

substance during the topical application phases revealed discrete/patchy erythema (score 1) at 24

hours and in 18/19 animals at 48 hours. This reaction was also noted in the control animals at 24

and 48 hours after treatment with vehicle only. One test male died on test day 10 after removal

of the dressing in the topical induction phase. Gross necropsy of this animal revealed no internal

findings. At challenge no skin reactions were noted for either the test or the control animals.

This study is classified as acceptable. It does satisfy the guideline requirement for a primary

dermal sensitization study (OPPTS 870.2600; OECD 406) in the Guinea pig.
64

46203235 Twomey, K. (2003) NOA 407855: 90 Day Dietary Toxicity Study in the Rat with

a 28 Day Interim Kill: Final Report. Project Number: PR1254,

CTL/PR1254/REG/REPT. Unpublished study prepared by Central Toxicology

Lab (Syngenta). 1569 p.

Executive Summary - In this subchronic oral toxicity study (MRIDs 46203235 and 46203237),

12 Alpk:APfSD rats/sex/dose were exposed to pinoxaden (97.2% a.i.; Batch #: EZ005006) in the

diet at concentrations of 0, 150, 1000, 5000, or 10,000 ppm nominally (equivalent to 0/0, 15/16,

98/110, 466/527, and 900/965 mg/kg/day in males/females) for up to 90 days. An additional 5

rats/sex/dose were treated similarly and sacrificed at day 28 (interim study).

There were no treatment-related effects on mortality, clinical signs, functional observational

battery, motor activity, food efficiency, ophthalmoscopic examination, hematology, clinical

chemistry, organ weights, or gross pathology. 

At 10,000 ppm (n=12) in the main study, body-weights were decreased (p#0.05) throughout the

study in both sexes (decreased 4-19%), and overall (weeks 1-14) body-weight gains were

decreased (decreased 9-16%). Food consumption was decreased (p#0.05) in males during the

first week (excluding day 6) by 16-72% and during weeks 2, 3, 8, and 11-13 by 6-10%. 

Increased (p#0.05) water consumption was observed in the males during the first 7 weeks

(excluding week 4) by 13-46%. Urine volume was increased (p#0.01) by 54% in the females. 

Renal lesions were observed (minimal to slight # affected/12 treated vs 0/12 controls) as follows:

(I) cyst(s) in both sexes (7-10); (ii) cortical tubular basophilia/dilatation/atrophy in both sexes (6-

8); (iii) ectasia pelvis in males (2); and (iv) transitional cell hyperplasia in males (2). 

In the interim study, cortical tubular basophilia/dilatation/atrophy was observed in 2/4 males and

1/5 females at 10,000 ppm vs 0/5 controls. Cholesterol was decreased (p#0.05) in the 10,000

ppm group by 19-20%. Generally similar effects were observed on body-weight, body-weight

gain, and food consumption in the interim study compared to the main study.

The LOAEL was 10,000 ppm (equivalent to 900/965 mg/kg/day in males/females), based on

decreased body-weight and body-weight gain and increased incidence of renal lesions in

both sexes; decreased food consumption and increased water consumption in males; and

increased urine volume in females. The NOAEL is 5000 ppm (equivalent to 466/527

mg/kg/day in males/females).

This study is classified as acceptable/guideline and satisfies the guideline requirements (OPPTS

870.3100a; OECD 408) for a subchronic oral toxicity study in the rat. 

46203239 Twomey, K. (2003) 90-Day Oral Toxicity Study in Rats (Gavage) (Includes

Report Amendments 1 and 2): NOA 407855 Technical: Final Report. Project

Number: 991092, 1313/99, 761253. Unpublished study prepared by Syngenta

Crop Protection, Novartis Crop Protection and Preclinical Safety Consultants Ltd.

711 p.

Executive Summary - In this subchronic oral toxicity study (MRIDs 46203239, 46203229, and

46203234), pinoxaden (95.7% a.i.; Batch #: 1192-PH-10) in 0.5% carboxymethylcellulose, 0.1
65

% Tween 80 in distilled water was administered by daily gavage at a dose volume of 10 mL/kg

bw to 10 HanIbm:WIST rats/sex/group at doses of 0, 3, 10, 30, 100, or 300 mg/kg/day) for 3

months. Additionally, 10 rats/sex were treated similarly at 0, 100, or 300 mg/kg/day for 3

months and allowed to recover for 4 weeks without treatment.

There were no treatment-related effects observed on mortality, clinical signs, body-weight, bodyweight gain, food consumption and efficiency, ophthalmology, hematology, organ weights, or

gross and histologic pathology. 

In the $100 mg/kg/day females, increases (p#0.05) were observed in serum potassium (incr 7-

12%) and inorganic phosphate (incr 20-25%) levels. 

In the 300 mg/kg/day males, glucose was decreased (p#0.01) by 16%, and increased (p#0.05)

water consumption was observed during weeks 3-5 and 8-9 (incr 18-27%). An increased

frequency of renal corticomedullary mineralization was observed in males (5/10 treated vs 2/10

controls); however, severity was decreased (minimal at 300 mg/kg/day vs slight in the controls

for all affected rats). Additionally, in the 300 mg/kg/day females, increased (p#0.05) water

consumption was observed (incr 14-29%) throughout most of the study, and urinary volume was

increased (p#0.01) by 53%. Creatinine was increased (p#0.01) by 18% in the 300 mg/kg/day

females. Nephrotoxicity was indicated in females by increased water consumption, urinary

volume and increased creatinine.

The LOAEL was not observed in males; however, the LOAEL was 300 mg/kg bw/day in

females based on increases in water consumption, urinary volume and creatinine

(indicators of nephrotoxicity) in females. The NOAEL is 300 mg/kg bw/day in males and

100 mg/kg bw/day in females.

This study is classified as Acceptable/guideline and does satisfy the guideline requirements

(OPPTS 870.3100a; OECD 408) for a subchronic oral toxicity study in the rat. A LOAEL was

not observed in males; however, the Sponsor submitted an acceptable/guideline 90-day dietary

study (MRID 46203235).

46203241 Bachmann, M. (2002) 90-Day Rangefinding Toxicity Study in Mice (Gavage):

NOA 407855: Final Report. Project Number: 20001128, 785305. Unpublished

study prepared by RCC Ltd. and RCC Umweltchemie Ag. 418 p.

Executive Summary - In this subchronic oral toxicity study (MRID 46203241), pinoxaden

(97.2% a.i.; Batch #: EZ005006) in 0.5% carboxymethylcellulose, 0.1 % Tween 80 in distilled

water was administered for 3 months by daily gavage at a dose volume of 10 mL/kg bw to

Crl:CD®-1(ICR)BR mice (10/sex/group) at doses of 0, 10, 100, 400, 700, or 1000 mg/kg bw/day. 

A functional observational battery was also conducted where the animals were evaluated in the

home cage, open field, and during handling.

No treatment-related effect was observed on mortality, food consumption, water consumption,

hematology, organ weight, or gross pathology. 

At 1000 mg/kg bw/day, piloerection (neck fur raised) was observed at the cageside in both sexes
66

(50-80% treated vs 0-10% controls) and during the FOB (n=10) at an increased incidence in 2-5

males on weeks 1 and 3-6, and 4 females on week 3 and 1 female on weeks 4 and 9. Although

there were no significant (p#0.05) decreases in body-weights or body-weight gains, overall (days

1-92) body-weight gain was decreased (not statistically significant) by 60-67% in the 1000

mg/kg bw/day group. Renal tubular basophilia was increased in incidence in the males (4/10

treated vs 1/10 controls) and also in severity (minimal to marked in treated vs slight in controls). 

The LOAEL is 1000 mg/kg bw/day, based on increased incidence of piloerection and

decreased body-weight gain in both sexes, and increased incidence of renal tubular

basophilia in males. The NOAEL is 700 mg/kg bw/day.

This study is classified as acceptable/guideline and satisfies the guideline requirements (OPPTS

870.3100a; OECD 408) for a subchronic oral toxicity study in the mouse.

46203242 Lees, D. (2003) NOA 407855 Tech.: 90 day oral toxicity in dogs. Central

Toxicology Laboratory, Alderley Park, Macclesfield, Cheshire, UK. Laboratory

Study Identification: CTL Study Number PD1225, July 24, 2003. Unpublished.

Executive Summary - In a subchronic oral study (MRIDs 46203242 and 46203230), pinoxaden

technical (97.2% a.i., Batch #: EZ005006) was administered neat in gelatin capsules to 4 beagle

dogs/sex/dose at doses of 0, 25, 100, 250, or 500 mg/kg bw/day for up to 14 weeks.

There were no treatment-related effects on survival, ophthalmoscopic examinations, hematology,

clinical chemistry, urinalysis, organ weights, or gross pathology.

At 500 mg/kg bw/day, all 4 females were killed for humane reasons in week 5, and 1 male

displaying clinical signs of toxicity, body-weight loss, and decreased food consumption was

killed prior to scheduled sacrifice during week 13. All other animals survived to scheduled

sacrifice.

At $250 mg/kg bw/day, increased incidences of fluid feces, vomit, pale and thin appearance,

decreased activity, dehydration, cold to touch, and regurgitation were observed in both sexes. 

Mucus in feces was observed in the males. At 250 mg/kg bw/day, veterinary examinations

performed at week 13 revealed 1 male to have a slow pulse rate; another male was described as

appearing depressed and thin. One female was examined several times and had findings that

included thin appearance, cold to touch, dehydrated, mucus membranes pale, extremities cold to

touch, and a quiet and slow heart beat.

Body-weights (decreased 1-12%; not significant) and food consumption (decreased 1-52%; NS)

were generally decreased in the 250 mg/kg bw/day and above groups throughout treatment. 

Overall (weeks 1-14) body-weight gains (calculated by reviewers) were decreased by 32-75% in

the 250 mg/kg bw/day group. In the 500 mg/kg bw/day females, body-weights were decreased

(p#0.01) by 12% on week 5, and food consumption was decreased (p#0.05) by 24-52% during

weeks 4-5.

The LOAEL for this study is 250 mg/kg bw/day based on clinical signs of toxicity (fluid

feces, vomit, pale and thin appearance, decreased activity, dehydration, cold to touch, and
67

regurgitation in both sexes, and mucus in feces in the males) and decreased body-weights,

body-weight gains, and food consumption in both sexes. The NOAEL is 100 mg/kg bw/day.

This study is classified acceptable/guideline and satisfies the guideline requirement (OPPTS

870.3150; OECD 409) for a 90-day oral toxicity study in the dog.

46203243 Sommer, E.W. (2001) 28-day repeated dose dermal toxicity study in rats. 

Syngenta Crop Protection, AG, Stein, Switzerland. Laboratory Study Id.: RCC

No. 20001186, December 20, 2001. Unpublished.

Executive Summary: In a 28-day dermal toxicity study (MRID 46203243), Pinoxaden technical

(97.2% a.i.; Batch # EZ005006) in aqueous 1% carboxymethyl-cellulose/0.1% Tween 80 was

applied to the shaved intact skin of 10 HanBrl:WIST rats/sex/dose at dose levels of 0, 10, 100, or

1000 mg/kg bw/day. The rats were treated daily during a 28-day period (except the weekends

for the first 3 weeks) for 6 hours/day. 

No treatment-related effects were observed in mortality, clinical signs, neurological evaluations,

dermal irritation, body-weight, body-weight gain, food consumption and efficiency, water

consumption, ophthalmoscopic examination, hematology, clinical chemistry, urinalysis, organ

weights, or macroscopic or histological pathology at any dose in either sex.

The LOAEL was not observed. The NOAEL is 1000 mg/kg bw/day (the limit dose).

This study is classified as acceptable/guideline and satisfies the guideline requirements (OPPTS

870.3200; OECD 410) for a 28-day dermal toxicity study in rats. The LOAEL was not

observed; however, the compound was tested to the limit dose.

46203309 Lees, D. (2003) NOA 407855 Tech.: 1 year oral toxicity study in dogs. Central

Toxicology Laboratory, Alderley Park, Macclesfield, Cheshire, UK. Laboratory

Study ID.: CTL Number PD1226, October 13, 2003. Unpublished.

Executive Summary - In a chronic oral toxicity study (MRID 46203309), Pinoxaden (Batch #:

EZ005006; 97.2% a.i.) was administered neat in gelatin capsules to 4 beagle dogs/sex/dose at

nominal doses of 0, 5, 25, or 125 mg/kg bw/day for up to 53 weeks.

There were no effects of treatment on mortality, clinical signs, body-weight or body-weight

gains, food consumption, ophthalmoscopic examination, hematology, urinalysis, organ weights,

gross pathology, or histopathology.

At 25 mg/kg bw/day, increased incidence of fluid feces was noted in the males and salivation at

dosing was observed in the females. At 125 mg/kg bw/day, increased incidence of fluid feces,

salivation at dosing, vomit, and mucus in the feces were observed in both sexes. However, in the

absence of corroborating findings, these observations were not considered to be of toxicological

significance.

Alkaline phosphatase was increased in the 125 mg/kg bw/day males at week 52 (875%; p#0.05),

in the 25 mg/kg bw/day females at week 13 (826%; p#0.05), and in the 125 mg/kg bw/day
68

females at weeks 13, 26, and 52 (855-112%; p#0.01). However, this finding was considered

equivocal, as no corroborating alterations in organ weight or pathology were observed.

The LOAEL was not observed. The NOAEL is 125 mg/kg bw/day.

This study is classified as acceptable/guideline and satisfies the guideline requirement (OPPTS

870.4100b, OECD 452) for a chronic oral toxicity study in dogs. A LOAEL was not observed,

and animals were not dosed to the limit dose (1000 mg/kg bw/day). However, a LOAEL of 250

mg/kg bw/day was observed in the subchronic study, and the stated dose rationale, while overly

cautious, was reasonable. Therefore, this study is considered acceptable.

46203311 Lees, D. (2004) NOA 407855: Study to investigate the effects of direct

administration of compound to mouse lung parenchyma (Revision - 001). Central

Toxicology Laboratory, Alderley Park, Macclesfield, Cheshire, UK. Laboratory

Study Identification: CTL Number XM7083, January 19, 2004. Unpublished.

Executive Summary: In the first of 2 non-guideline studies (MRID 46203311), the lung

parenchyma of male mice (strain and source not provided) was: I) exposed to Pinoxaden (97.2%

a.i.; Lot/Batch #: EZ005006) in 0.5% (w/v) carboxymethylcellulose in 0.1% (w/v) aqueous

Tween 80 vehicle; ii) exposed to the vehicle alone; or iii) left untreated. Groups of 2 mice were

killed and their lungs removed. The lungs were then directly dosed via a syringe with 250 :L of

either a 75 mg/mL formulation (approximately equivalent to a whole animal dose of 750

mg/kg/day) or vehicle. Lungs from 2 untreated mice served as an additional control group. One

pair of lungs from each group was then fixed after 1 minute of exposure; the other pair was fixed

after 10 minutes of exposure. Lung sections from all animals were examined microscopically. 

The objective of this study was to investigate the histopathological effects of direct

administration of Pinoxaden in vehicle on the lung parenchyma of male mice.

It was stated that it was physically easier to instill vehicle into the lungs than the 75 mg/mL dose

formulation. The test substance was observed to block the lung passages, making introduction of

additional material difficult. Untreated lungs and lungs treated with vehicle only were similar in

appearance. Lungs that were dosed with 75 mg/mL Pinoxaden were observed to be pale and

were difficult to inflate with formol saline. Reduced eosinophilic staining of the alveolar walls

was observed in lungs dosed with 75 mg/mL Pinoxaden and vehicle only following 1 and 10

minute exposures. Lysis of intravascular red blood cells was noted in lungs dosed with 75

mg/mL Pinoxaden and vehicle after the 10 minute exposure.

In the second of 2 non-guideline studies (MRID 46224806), male CD-1® [Crl:CD-1®(ICR)BR]

mice (5/group) were dosed by oral gavage with 0.5% (w/v) carboxymethylcellulose in 0.1%

aqueous Tween 80 vehicle containing 1.0% (w/v) Evans Blue dye. The dosing catheters were

either normal (having an opening near the bottom to deliver the dose to the stomach), modified

so that the opening was higher on the catheter to deliver the dose to 1 of 2 locations in the

esophagus (low and high esophagus), or modified so that the opening was higher on the catheter

and the catheter was shorter in overall length (modified high esophagus). Mice were killed

approximately 0.5 hours after dosing, the thoracic cavity was opened, and the location of the dye

was recorded. The lungs and trachea were removed, observed for location and intensity of dye

appearance, photographed, and fixed. Sections were prepared from all lungs and examined
69

microscopically. Based on these results, on the following day (day 2 animals) additional groups

of 5 mice were dosed with the carboxymethylcellulose Tween 80 vehicle without dye using

either a normal or high esophagus catheter. High esophagus mice were killed at 1, 24, or 72

hours after dosing; normal catheter and untreated mice were killed at 72 hours after dosing. The

lungs and trachea were removed, observed, fixed, sectioned, and examined microscopically. The

objective of this study was to develop an experimental model to investigate the effects of

carboxymethylcellulose/Tween 80 vehicle on the lungs of male mice.

On day 1, vehicle was observed in the mouth of all group 3 (high esophagus) mice immediately

after dosing. One of these animals then died and was not replaced. Dye was observed in the

airways of 1/5 group 2 (low esophagus), 4/5 group 3 (high esophagus), 1/5 group 4 (modified

high esophagus, 5 mL/kg dose volume), and 2/5 group 5 (modified high esophagus, 10 mL/kg

dose volume) mice. Microscopically, minimal to slight hemorrhage was observed in 1/5 group 1

(normal esophagus), 1/5 group 2, 2/5 group 3 and 1/5 group 5 mice, but the significance of this

finding was unclear. Also in these mice, minimal hyaline change was noted in 1/5 group 3 and

1/5 group 5 mice.

On day 2, vehicle was observed in the mouth of all group 3, 4, and 5 (high esophagus) mice

immediately after dosing. One group 5 (high esophagus, 72 hours post-dosing) mouse died

immediately after dosing and was replaced to maintain 5 mice/group. A second group 5 mouse

was found in moribund condition approximately 69.5 hours after dosing and died shortly

thereafter. This animal was examined by the same procedures as those killed on schedule. One

group 5 (high esophagus, 72 hours post-dosing) was noted to have areas of dark blue coloration

in all lung lobes. It was thought this finding was linked to the clinical condition of this animal

(found moribund and died prior to 72 hours). Microscopically, 1/5 group 3 mice had a small

focus of acute pneumonitis, consistent with aspiration of the vehicle. In group 4, 2/5 mice were

observed to have slight esophagitis, consistent with dosing trauma. In group 5, 2/5 mice died

prior to termination. One of these animals demonstrated slight hemorrhage with minimal hyaline

change. This animal was replaced. The second mouse was found to have severe pleuritis

consistent with esophageal rupture and application of the vehicle into the mediastinum.

Collectively, the data indicate that carboxymethylcellulose Tween-80 vehicle used during

oral gavage dosing may contribute to the pathological changes observed in the 80-week

carcinogenicity study (MRID 46224808).

The submitted studies are classified as unacceptable/non-guideline due to major technical

and scientific deficiencies.

46203314 Sokolowski, A. (2001) Salmonella Typhimurium and Escherichia coli Reverse

Mutation Assay with NOA 407855 Tech.: Final Report. Project Number: 672909,

784383, 20001072. Unpublished study prepared by RCC Umweltchemie Gmbh &

Co. Kg and RCC Umweltchemie Ag. 84 p.

Executive Summary - In two independent reverse gene mutation assays in bacteria (MRID

46203314), Salmonella typhimurium strains TA98, TA100, TA102, TA1535, and TA1537 and

Escherichia coli strain WP2uvrA were exposed to Pinoxaden technical (97.2% a.i., Batch #

EZ005006) in dimethylsulfoxide (DMSO) at concentrations of 33, 100, 333, 1000, 2500, or 5000
70

μg/plate in the presence and absence of mammalian metabolic activation (+/-S9). The standard

plate incorporation method was performed in Trial 1 (+/-S9), while a pre-incubation step was

added in Trial 2 (+/-S9). Standard strain-specific mutagens served as positive controls.

Pinoxaden technical was tested up to the limit dose (5000 :g/plate). In Trial 1, cytotoxicity (as

indicated by reduction in number of revertants) was observed at $1000 :g/plate (TA100 and

TA102, -S9) and at $2500 :g/plate (TA1535, -S9; and TA98, TA100, and TA102, +S9). In

Trial 2, cytotoxicity was observed at $1000 :g/plate (TA100 and TA102, -S9; and TA1537,

+S9), at $2500 :g/plate (TA1537, -S9; and TA100 and TA102, +S9), and at 5000 :g/plate

(TA98, +/-S9). Normal background lawn growth was observed at all concentrations in all strains

in both trials. No marked increases in the number of revertants were observed at any

concentration in any strain in either trial. The positive controls induced marked increases in

revertant colonies compared to controls in both trials. There was no evidence of induced

mutant colonies over background.

The study is classified as Acceptable/Guideline and satisfies the guideline requirements

(OPPTS 870.5100; OECD 471) for in vitro mutagenicity (bacterial reverse gene mutation) data.

46203318 Wollny, H. (2003) Cell Mutation Assay at the Thymidine Kinase Locus (TK+/-)

in Mouse Lymphoma L5178Y Cells with Pinoxaden Tech.: Final Report. Project

Number: 672905, 20001074, 781470. Unpublished study prepared by RCC

Umweltchemie Gmbh & Co. Kg, RCC Umweltchemie Ag and Novartis Crop

Protection. 125 p.

Executive Summary - In three independent trials of a mammalian cell gene mutation assay at

the TK+/- locus (MRID 46203318), L5178Y mouse lymphoma cells cultured in vitro were

exposed to Pinoxaden technical (97.2% a.i., Batch # EZ005006) in acetone for either 4 hours at

concentrations of 6.3, 12.5, 25, 50, 100, or 200 :g/mL (Trial 1 -S9) or 3.1, 6.3, 12.5, 25, 50, or

100 :g/mL (Trial 1 +S9); or for 24 hours at concentrations of 25, 50, 100, 200, 300, or 400

:g/mL (Trial 2 -S9). Due to insufficient cell growth in the negative and solvent control second

cultures in the second cultures of Trial 1 (+S9), a repeat trial was performed at 6.3, 12.5, 25, 50,

100, or 150 :g/mL (+S9) and was reported as Trial 1A. In Trial 2, the negative control of the

second culture exceeded the historical range and the positive control induced excessive

cytotoxicity; therefore, this part of the trial was repeated at the same doses and reported as Trial

2A. A third trial was performed at 3.1, 6.3, 12.5, 25, 50, or 100 :g/mL (+S9) to confirm the

results observed in Trials 1 and 1A in the presence of S9. Methylmethane sulfonate (MMS) and

3-Methylcholanthrene (3-MC) served as positive controls in the absence and presence of S9,

respectively.

Pinoxaden was tested up to cytotoxic concentrations ($50 :g/mL, +S9) and ($100 :g/mL,-S9). 

No reproducible substantial ($2x solvent controls) and/or concentration-dependent increases in

mutant colonies per 106

 cells were observed at any dose level in the presence or absence of S9. 

The positive controls induced the expected response. There was no evidence of induced

mutant colonies over background.

The study is classified as Acceptable/Guideline and satisfies the guideline requirements

(OPPTS 870.5300, OECD 476) for in vitro mutagenicity (mammalian forward gene mutation)
71

data.

46203321 Czich, A. (2001) In vitro Chromosome Aberration Test in Chinese Hamster V79

Cells with Pinoxaden Tech.: Final Report. Project Number: 672907, 20001073,

784258. Unpublished study prepared by RCC Umweltchemie Gmbh & Co. Kg,

RCC Umweltchemie Ag and Novartis Crop Protection AG. 98 p.

Executive Summary - In three independent trials of a mammalian cell cytogenetics assay

(chromosome aberration; MRID 46203321), Chinese hamster V79 cultures were exposed to

pinoxaden (97.2% a.i., Batch # EZ005006) in acetone at concentrations of 6.3, 12.5, 25, 50, 75,

or 100 μg/mL (Trial 1, 4 hr exposure and 14 hour recovery period prior to cell harvest); 10, 20,

40, 60, 80, or 100 :g/mL (Trial 2, 18 hr exposure); and 40, 60, 80, or 100 :g/mL (Trial 2, 28 hr

exposure) in the absence of S9. In the presence of S9, cultures were exposed for 4 hours at

concentrations of 10, 20, 40, 60, 80, or 100 :g/mL (Trial 1, 14 hour recovery period prior to cell

harvest) and 30, 40, 50, 60, 70, or 80 :g/mL (Trial 2, 24 hour recovery period prior to cell

harvest). Additionally, to clarify the results observed in Trials 1 and 2, a third trial was

performed at concentrations of 12.5, 25, 50, 75, 100, or 125 :g/mL (4 hr exposure with 18 hour

recovery and 18 hr exposure) in the absence of S9 and 20, 40, 60, 80, 100, or 120 :g/mL (4 hr

exposure with a 24 hour recovery period prior to cell harvest) in the presence of S9.

Pinoxaden was tested up to cytotoxic concentrations ($ :g/mL +S9; and $80 :g/mL -S9). In the

presence of S9, increases (p#001) in the percent aberrant cells (excluding gaps) were observed

after 4 hours treatment and 24 hours recovery in Trial 2 at $60 :g/mL (7.0-11.0% treated vs

1.0% solvent control) and in Trial 3 at 60 :g/mL (11.5% treated vs 0.5% solvent control). In the

absence of S9, increases (p#0.05) in the percent aberrant cells (excluding gaps) were observed

after 4 hours treatment and 14 hours recovery in Trial 1 at >=25 :g/mL (2.5-7.5% treated vs 0%

solvent control) and in Trial 3 at $75 :g/mL (2.5-3.5% treated vs 0% solvent control); and after

18 hours of continuous exposure in Trial 2 at $80 :g/mL (2.5-5.5% treated vs 0% control) and in

Trial 3 at $100 :g/mL (4.0-8.0% treated vs 0.5% control). Although there was not a clear doseresponse and several of the increases in percent aberrant cells were within the historical control

range (0.0-4.0%), there was sufficient reproducible evidence of a positive mutagenic effect in the

presence and absence of S9. No biologically relevant increases in the rate of polyploid

metaphases were observed at any concentration in any trial (+/-S9). The positive controls

induced the appropriate response. There was evidence that Pinoxaden induced a clastogenic

effect in the presence and absence of S9-activation.

This study is classified as Acceptable/Guideline and satisfies the Guideline requirement

(OPPTS 870.5375, OECD 473) for in vitro mutagenicity (chromosome aberration) data.

46203322 Schulz, M. (2002) In vitro Chromosome Aberration Test in Chinese Hamster V79

Cells with Pinoxaden: Final Report. Project Number: 702901, 20011070, 825017.

Unpublished study prepared by RCC Umweltchemie Gmbh & Co. Kg and RCC

Umweltchemie Ag. 99 p.

Executive Summary - In three independent trials of a mammalian cell cytogenetics assay

(chromosome aberration; MRID 46203322), Chinese hamster V79 cultures were exposed to

pinoxaden (99.5% a.i., Batch # AMS 1055/2) in acetone for 4 hours (with a 14 hr recovery
72

period prior to cell harvest) at concentrations of 15, 30, 45, 60, 75, and 90 μg/mL (Trials 1A and

1B, -S9); 3.8, 7.5, 15, 30, 45, and 60 :g/mL (Trial 1A, +S9); and 7.5, 15, 30, 45, 60, and 90

:g/mL (Trial 1B, +S9). Additionally, to clarify the results observed in Trials 1A and 1B, a third

trial was performed at concentrations of 10, 20, 40, 60, 80, or 100 :g/mL (18 hr continuous

exposure, -S9); 40, 60, 80, or 100 :g/mL (28 hr continuous exposure, -S9); and 7.5, 15, 30, 45,

60, and 90 :g/mL (4 hr exposure with a 24 hour recovery period prior to cell harvest, +S9).

Pinoxaden was tested up to cytotoxic concentrations ($45 :g/mL +S9; and $75 :g/mL -S9). In

the presence of S9, increases (p#0.001) in the percent aberrant cells (excluding gaps) that

exceeded the historical control range were observed after 4 hours treatment with 14 hours

recovery in Trial 1A at 60 :g/mL (9.0% treated vs 1.5% solvent control) and after 4 hours

treatment with 24 hours recovery in Trial 2 at 45 :g/mL (10.5% treated vs 0% solvent control). 

In the absence of S9, increases (p#0.01) in the percent aberrant cells (excluding gaps) that

exceeded the historical control range were observed after 4 hours treatment with 14 hours

recovery in Trial 1A at 90 :g/mL (12.0% treated vs 1.0% solvent control) and in Trial 1B at 90

:g/mL (11.5% treated vs 0.5% solvent control); and after 18 hours of continuous exposure in

Trial 2 at 100 :g/mL (8.0% treated vs 2.0% control). No biologically relevant increases in the

rate of polyploid metaphases were observed at any concentration in any trial (+/-S9). The

positive controls induced the appropriate response. There was evidence that Pinoxaden

induced a clastogenic effect in the presence and absence of S9-activation.

This study is classified as Acceptable/Guideline and satisfies the Guideline requirement

(OPPTS 870.5375, OECD 473) for in vitro mutagenicity (chromosome aberration) data.

46203324 Fox, V. (2003) SYN 502836 (Metabolite of Pinoxaden): In vitro Cytogenetic

Assay in Human Lymphocytes: Final Report. Project Number: SV1141.

Unpublished study prepared by Central Toxicology Lab. (Syngenta). 33 p.

Executive Summary - In two independent trials of a mammalian cell cytogenetics assay

(chromosome aberration; MRID 46203324), lymphocyte cultures were prepared from human

peripheral blood and exposed to SYN 502836 (a metabolite of Pinoxaden tech.; pinoxaden; 99%

a.i., Batch # KI 6513/3M) in dimethylsulfoxide (DMSO) at concentrations of 50, 100, 200, 500,

1000, 1500, 2000, and 2750 :g/mL for either 3 hours with a 17 hour recovery period (Trial 1, +/-

S9 and Trial 2, +S9) or 20 hours with no recovery period (Trial 2, -S9).

SYN 502836 was tested up to a maximum concentration of 2000 :g/mL (+/-S9), which was

limited by reductions in the pH of the treatment medium. Cytotoxicity (as evidenced by reduced

mitotic index) was noted at $1000 :g/mL in Trial 1 (+S9) and at 2000 :g/mL in Trial 2 (+/-S9). 

No significant increases in aberration frequencies (excluding gaps) were observed in the

presence or absence of S9 in either trial. The positive controls induced the appropriate response

in all assays. There was no evidence of chromosome aberrations induced over background

in the presence or absence of S9-activation.

This study is classified as Acceptable/Guideline and satisfies the Guideline requirement

(OPPTS 870.5375, OECD 473) for in vitro mutagenicity (chromosome aberration) data. 

46203325 Clay, P. (2002) NOA 407855: in vivo Rat Liver Unscheduled DNA Synthesis
73

Assay: Final Report. Project Number: SR1130. Unpublished study prepared by

Central Toxicology Lab. (Syngenta). 31 p.

Executive Summary - In an in vitro/in vivo unscheduled DNA synthesis assay (MRID

46203325), rat hepatocyte cultures were prepared from 3 male (Alpk:APfSD) rats/sacrifice time

that were treated orally (gavage, 10 mL/kg) once with pinoxaden (97.2% a.i., Batch #

EZ005006) in 0.5% aqueous carboxymethylcellulose at a dose of 2000 mg/kg (limit dose). 

Hepatocytes were harvested after 2 or 16 hours of exposure. Additionally, 2 rats/sacrifice time

were treated with the vehicle or positive control (1,2-dimethylhydrazine dihydrochloride).

pinoxaden was tested up to the limit dose (2000 mg/kg). There were no clinical signs of toxicity

in the treated animals or evidence of excessive cytotoxicity in any of the cultures. There were no

marked increases observed in mean net nuclear grains (NNG) or percent cells in repair (NNG

$5) at 2 or 16 hours post-dosing compared to controls. The positive control induced the

appropriate response. There was no evidence that unscheduled DNA synthesis, as

determined by radioactive tracer procedures (nuclear silver grain counts), was induced.

The study is classified as Acceptable/Guideline and satisfies the Guideline requirement (OPPTS

870.5550; OECD 486) for other genotoxic mutagenicity data. Although, the dosing formulation

was not analyzed for the amount of test substance, this is not considered to be a major deficiency

that would have altered the results of the study, since the limit dose was tested and the testing

laboratory adheres to GLP regulations, and has a QA unit.

46203327 Honarvar, N. (2001) Micronucleus Assay in Bone Marrow Cells of the Mouse

with Pinoxaden tech.: Final Report. Project Number: 672901, 20001070, 780671.

Unpublished study prepared by Cytotest Cell Research Gmbh and Co. and RCC

Umweltchemie Ag. 67 p.

Executive Summary - In a bone marrow micronucleus assay (MRID 46203327), 6 fasted NMRI

mice/sex/dose were treated once via gavage (10 mL/kg) with Pinoxaden (Pinoxaden; 97.2% a.i.,

Batch # EZ005006) dissolved in 40% ethanol in PEG 400 at doses of 0, 500, 1000, or 2000

mg/kg bw. Bone marrow cells were harvested from all animals and samples from 5

mice/sex/dose at 24 (all doses) or 48 hours (2000 mg/kg only) post-dosing were evaluated. 

Cyclophosphamide (40 mg/kg) served as the positive control.

Pinoxaden was tested up to the limit dose (2000 mg/kg); however, no evidence of bone marrow

toxicity (decreased PCE:NCE) was observed at the 24 or 48 hour sampling times at up to 2000

mg/kg. No significant increase in micronucleated polychromatic erythrocytes (MPCEs) was

observed in any dose at either 24 or 48 hours post-dosing. The positive control induced the

appropriate response. There was no significant increase in the frequency of micronucleated

polychromatic erythrocytes in bone marrow compared to controls.

The study is classified as Acceptable/Guideline and satisfies the guideline requirement (OPPTS

870.5395; OECD 474) for in vivo cytogenetic mutagenicity data.

46203329 Schultz, M. (2001) Unscheduled DNA synthesis in primary hepatocytes of male

rats in vitro with NOA 407855 technical RCC - Cytotest Cell Research GmbH,
74

Roßdorf, Germany. Laboratory Study ID: RCC-CCR Study Number 672903,

January 16, 2001. Unpublished.

Executive Summary - In two independent trials of an in vitro unscheduled DNA synthesis assay

(MRID 46203329), primary rat hepatocyte cultures were exposed to Pinoxaden (Pinoxaden;

97.2% a.i., Batch # EZ005006) in acetone at concentrations of 0, 1.17, 2.34, 4.69, 9.38, 18.75,

37.5, 75, 150, 300, or 600 :g/mL for 19 hours (Trial 1) or 20 hours (Trial 2). The compound, 2-

acetylaminofluorene, served as the positive control.

Pinoxaden was tested up to cytotoxic levels ($300 μg/mL in both trials, determined by neutral

red absorption). There were no marked increases observed in the mean grains per nucleus or

mean NNG in either trial. The positive controls induced marked increases in mean grains per

nucleus and mean NNG in both trials. There was no evidence that unscheduled DNA

synthesis, as determined by radioactive tracer procedures (nuclear silver grain counts),

was induced.

The study is classified as Acceptable/Guideline and satisfies the Guideline requirement (OPPTS

870.5550; OECD 482) for other genotoxic mutagenicity data.

46203335 Rumbeli, R. (2003) The Metabolism of (Phenyl-1-14C) NOA 407855 in the Rat:

Final Report. Project Number: 046AM03. Unpublished study prepared by

Syngenta Crop Protection, AG. 489 p.

Executive Summary: In a series of rat metabolism studies (MRIDs 46203333 through

46203336), [Phenyl-1-14C]-Pinoxaden (>96% radiochemical purity) was suspended in aqueous

0.5% carboxymethylcellulose with 0.7% Tween 80 and 0.1% acetic acid and administered to

Wistar rats by gavage. In the main mass balance studies (MRID 46203334), a single oral dose of

[

14C] Pinoxaden was administered to 4 Wistar rats/sex/dose at nominal doses of 0.5 or 300 mg/kg

bw. Urine, feces, and blood were collected over 7 days, and selected tissues were collected at

termination. A biliary excretion study was performed on 5 bile duct cannulated rats/sex

following a single oral low dose at 0.5 mg/kg bw. Urine, feces, and bile were collected over 48

hours, and the gastrointestinal tract (GIT) and carcass were analyzed for radioactive residues. 

Metabolites were determined in the urine, feces, and bile from rats in these studies (MRID

46203335). A tissue distribution time course study (MRID 46203336) was performed on the

tissues from 3 rats/sex/time interval at 4 intervals after a single-dose, with the first interval

corresponding to approximately Tmax of radioactivity in blood. In a repeat dose study (MRID

46203336), females rats were dosed daily with [14C] Pinoxaden at 0.5 mg/kg bw/day for up to 14

days. Urine, feces, and blood samples were collected throughout dosing, and subgroups of 4

rats/interval were sacrificed to examine levels of radioactivity in tissues 24 hours after 1, 7 and

14 days of dosing and at 72 hours after the final dose. The metabolite profile in excreta was also

examined qualitatively in selected urine and fecal samples.

Following administration of a single oral dose, radioactivity in blood increased rapidly in both

sexes at both dose levels. At the low dose, Cmax was reached within 1 hour (0.15-0.17 ppm

equiv.), and the initial half-life was approximately 1 hour in both sexes, and the terminal half-life

was 6 hours in females. At the high dose, levels of radioactivity in blood essentially plateaued

between 1-12 hours post-dose, with Cmax of 26 and 18 ppm equiv. for males and females,
75

respectively. The elimination half-life at the high dose was similar for both sexes (6–7 hours). 

Similar blood kinetics were also noted in the repeated low-dose group. Radioactivity levels in

blood increased rapidly, and concentrations in blood at 2 hours following each daily dose were

relatively constant over the entire dosing phase at 0.06-0.09 ppm equivalents. After the final 14th

dose, radioactivity in blood declined rapidly, reaching values below the LOQ within 50 hours.

The mean half-life in blood was calculated to be 7 hours in the repeated dose group. AUC

values were calculated to be approximately 0.32 :gAh/g for the single low dose group and 342-

456 :gAh/g for the single high dose group, with no apparent differences between the sexes. The

ratio of the area under the curve values in blood for the high and low dose level was in the range

of 1100 to 1500, whereas the dose level increased by a factor of 600, suggesting that some

enterohepatic recirculation may occur at the high dose level.

Based on the above blood data and the high degree of renal and biliary excretion, the

administered dose was rapidly and extensively absorbed by both sexes at both dose levels

following a single oral dose. Excretion of the absorbed dose was also rapid and virtually

complete, with >90% of the dose being excreted within 72 hours. Overall excretion accounted

for 90-105% dose at both dose levels, with urine accounting for 59-77% of the dose and feces

accounting for 25-28% of the dose. Excretion from bile-duct cannulated rats, confirmed that

renal excretion (-77% dose) was the primary route of elimination followed by biliary (10-12%

dose) and fecal (5-6% dose) excretion. Radioactivity remaining in the tissues and carcass at 7

days post-dose accounted for <2% dose, and expired air accounted for <0.01% dose. The total

recovery of the administered dose was 91-105% dose. 

Repeated dosing also had no affect on the route or rate of excretion. Throughout the 14-day

dosing period, urine accounted for 64-79% of the daily dose and feces accounted for 16-26% of

the daily dose. Over the entire study period, excreta accounted for >93% of the total dose (urine,

70% dose; feces, 22% dose), and residual radioactivity in tissues and carcass was <0.3% dose.

There was little or no apparent bioaccumulation of radioactivity following single or repeated

dosing, and the relative distribution of radioactivity among tissues/organs was not affected by

sex or dose level. Seven days following a single oral dose, concentrations of radioactivity in

tissues were <LOQ in all tissues from the low dose group and were <LOQ in tissues from the

high dose group, with the exceptions of liver and kidney (0.05-0.07 ppm) and blood and plasma

(0.01-0.03 ppm equiv.). Following the concentration of radioactivity in tissues from single low

and high dose rats beginning at -Tmax indicated that the relative distribution of radioactivity

among tissues was similar over time between the dose groups and sexes. With one minor

exception, radioactivity levels were highest in liver and kidneys for both dose levels at all time

points, and radioactivity in the remaining tissues were always below the levels observed in blood

and plasma. Radioactivity peaked in the liver and kidneys between 1-2 hours post-dose for the

low dose group (0.62-0.85 ppm equiv.) and at 8 hours post-dose for the high dose group (119-

248 ppm equiv.). Half-lives of radioactivity in tissues typically ranged from 2-5 hours for the

low dose group and 2-7 hours for the high dose group. The relative distribution of radioactivity

in tissues was also similar between the single and repeated dose groups. At 24 hours following

either 1, 7, or 14 days of dosing, radioactivity was highest in the liver and kidneys, followed by

plasma and blood. Levels in the remaining tissues were always below the levels in blood

(<0.003 ppm equiv.). After initially increasing, concentrations in blood and plasma were

relatively constant, and concentrations in liver and kidneys at 24 hours post-dose showed a low
76

but steady increase from day 1 (0.008-0.013 ppm equiv.) through day 14 (0.017-0.029 ppm

equiv.), but declined rapidly to <0.005 ppm equiv. within 3 days of the final dose.

The metabolite profile in excreta was similar regardless of dose level, sex, or duration of dosing. 

Following a single oral dose, the major metabolite identified in excreta was Metabolite M2

(62.6-91.0% dose). At both dose levels, Metabolite M2 was the major metabolite in both urine

(50-73% dose) and feces (12-18% dose ), and in bile-duct cannulated rats, its was also the major

metabolite in bile (8.5-9.6% dose). The only other substantial metabolite was M4, which

accounted for 5.0-15.6% of the dose in excreta. A total of 33 additional minor metabolites were

also identified in seven HPLC fractions isolated from urine and feces of high dose rats; however,

each of these fractions comprised #3.3% of the dose and included 2-7 metabolites. Parent test

material was not detected in urine, feces, or bile. Although detailed qualitative and quantitative

metabolite data were not provided for the repeated dose group, HPLC analyses of urine and fecal

extracts from samples collected after the 1st and 14th dose showed the same relative distribution

between Metabolites M2 and M4 as observed in the single-dose groups.

Based on the above profile, the metabolism of NOA 407855 in rats primarily involves the initial

hydrolysis of the ester moiety to form Metabolite M2 (NOA 407854), which is then extensively

excreted in the urine and feces. To a minor extent, Metabolite M2 is also further metabolized via

hydroxylation, dealkylation, ring cleavage, ring formation, and conjugation into a wide variety of

minor metabolites. The proposed pathway is also supported by the appended in vitro study,

which indicates that NOA 407855 is rapidly hydrolyzed to M2 in rat plasma (T1⁄2 = -0.1 min) at

concentrations up to 100 μM (-40 ppm).

This metabolism study in the rat is classified acceptable/guideline and satisfies the guideline

requirement for a Tier 1 metabolism study [OPPTS 870.7485, OPP 85-1] in rats.

46203337 Hassler, S. (2003) Absorption distribution and excretion of [Phenyl-1-14C] NOA

407855 in the rabbit after oral administration. Health Assessment/Animal

Metabolism, Syngenta Crop Protection AG, Basel, Switzerland. Laboratory

Study Id.: Basel No.: 046AM08, July 24, 2003. Unpublished

Executive Summary: In a non-guideline rabbit metabolism study (MRIDs 46203337 and

46203338), a single oral dose of [Phenyl-1-14C] NOA 407855 (Batch/lot # ILA-8.1B-5 and ILA8.1C-1B; radiochemical purity $98.9%) was administered in aqueous 0.5%

carboxymethylcellulose and 0.1% Tween 80 to female Chbb-HM rabbits (3/dose) via gavage at

nominal dose levels of 0.5 and 300 mg/kg. Urine, feces, and blood samples were collected up to

168 hours after dosing. Metabolites in urine and feces were quantified and identified by HPLC,

TLC, and LC/MS. Animals were sacrificed after 168 hours, and tissues were collected to

determine of residual radioactivity.

Absorption and elimination of [14C] NOA 407855 were rapid and essentially complete regardless

of dose level. Maximum concentrations (Cmax) in blood were attained within 0.5 hours at the low

dose and within -2 hours at the high dose. Half lives (t1⁄2) for radioactivity in the blood were 3

and 12 hours for the low and high dose groups, and radioactivity in blood was non-detectable by

48 and 96 hours for the low and high dose groups.
77

The total recovery of the radioactive dose averaged 94.7-100.1% at 168 hours post-dose. The

route of excretion was essentially independent of dose, although excretion was slightly retarded

at the high dose compared to the low dose. Approximately 90% of the dose was excreted in the

urine within 24 (low dose) or 48 (high dose) hours. An additional 4-7% dose was excreted in the

feces within 48 hours. For both dose groups, concentrations of radioactivity remaining in the

tissues were negligible by 168 hours post-dose and accounted for #0.1% of the dose. 

Quantifiable residues were detect in gall bladder and gastrointestinal (GI) tract for both the low

dose group (0.0020-0.0025 ppm Eq.) and high dose group (1.66-1.69 ppm Eq.), and in the

kidneys, liver, plasma, and blood (0.017-0.158 ppm) of the high dose group. However,

radioactivity in the remaining tissues was below the limit of quantitation (LOQ).

Essentially all of the metabolites excreted in the urine and feces were identified (92.8-97.7%

dose), and the metabolite profile was the same regardless of dose level. For both dose groups,

Metabolite M2 (NOA 407854) was identified as the major component in both urine (88.6-91.0%

dose) and feces (3.6-6.2% dose). Minor amounts of Metabolites M4 (0.4-0.6% dose), K4 (0.2%

dose), M12 (0.2% dose) and K3 (0.1% dose) were also identified in urine and/or feces. 

Unidentified metabolites accounted for #0.6% dose.

In rabbits, the metabolism of NOA 407885 proceeds predominantly by hydrolysis of the ester

linkage to form Metabolite M2 (NOA 407854), which is the major metabolite in urine and feces

(92-97% dose). Minor secondary reactions include either: hydroxylation at the 4-methyl group

of the phenyl moiety to yield M4 (excreted in urine and feces); or glucuronidation of M2 to form

metabolite M12. The metabolic pathway in the rabbit is essentially identical to the rat. 

This metabolism study in the rabbit is classified acceptable/non-guideline. 

46203339 Briswalter, C. (2003) The metabolism of [Pyrazol-35-14C] NOA 407855 in the

mouse: identification of metabolites in blood and excreta. RCC Ltd.,

Environmental Chemistry & Pharmanalytics, Itingen, Switzerland. Laboratory

Study Id.: RCC No.: 851355, Syngenta No.: 046AM11, December 1, 2003. 

Unpublished.

Executive Summary: In a non-guideline mouse metabolism study (MRIDs 46203339 and

46224815), [pyrazol-3,5-14C] NOA 407855 ($97.6% radiochemical purity; Lots ILA-76.3B ILA76.3C) was administered to 4 groups of male and female C57BL/10Jf

/CD-1 mice as follows: (I)

Group G1 was given either a single-dose or repeated daily dose of 1.4 mg/kg body-weight by

gavage; (ii) Group G2 was administered either a single-dose or repeated daily dose of 140 mg/kg

body-weight by gavage; (iii) Group G3 was fed at 10 ppm in the diet; and (iv) Group G4 was fed

a 1000 ppm diet. The maximum duration of dosing in each group was for 18 days. Terminal

blood samples were collected to determine a time course of the concentration of radioactivity in

whole blood, and urine and feces were collected over 24 hours after varying time periods of

dosing. The stated objectives of this study were to: (I) investigate the duration of dosing

required to reach steady-state kinetics; (ii) compare systemic exposure following gavage or

dietary dosing and determine any marked sex difference; (iii) compare blood and excreta

metabolite profiles after single and multiple dosing to male and female mice; and (iv) resolve

which metabolite should be analyzed during dietary studies.
78

Radioactivity levels in whole blood sampled at various post-dose intervals indicated that the

gavage dose was rapidly absorbed (Tmax = 0.5 hours) and eliminated regardless of the dose level

or the duration of dosing. Absorption was slower for the dietary dosing groups (Tmax = 8-12

hours), but elimination from the blood was rapid once mice were withdrawn from the treated

diet. Concentrations in blood at Tmax following 1, 7, 14, and 18 days of dietary dosing indicated

that a steady state in blood levels was achieved within 18 days.

Although urinary excretion was typically higher than fecal excretion, there was no clear pattern

in the distribution of excreted radioactivity between urine and feces based on sex, dosing group,

or duration of dosing. Radioactivity in urine (including cage wash) varied from 26-83% of the

excreted radioactivity and in feces from 17-74%.

Following oral administration of NOA 407855 to mice either by gavage or in the diet, the

metabolite profiles in blood, urine and feces were qualitatively and quantitatively independent of

sex, dose level, dosing method (gavage vs. dietary), dosing duration (single vs. multiple doses)

and time of collection, although some quantitative variations were observed in feces. 

Parent compound was not detected in blood, urine or feces. Metabolite M2 (NOA 407854) was

the major component identified in all three matrices, accounting for -67-93% of the extractable

blood radioactivity, 69-89% of the total radioactivity in urine, and 35-75% of the radioactivity

extractable from feces. Substantial amounts of Metabolite M4 were also detected in blood (2-

11% extractable blood radioactivity), urine (5-14% of total radioactivity), and feces (12-41% of

the extractable radioactivity). The remaining components detected in each matrix were minor

(<8% of the sample radioactivity) and included five components in blood extracts, eight

components in urine, and 8-11 components in fecal extracts.

The presence of Metabolites M2 and M4 in urine and feces were confirmed by LC/MS and

LC/NMR analyses of fractions isolated from composited samples. These analyses also identified

minor amounts (<3% sample radioactivity) of Metabolites M13, M21, M50, and M51 in urine

and Metabolites M13, M19, M20, M22, M49, and M50 in fecal extracts.

Based on the metabolites identified in blood, urine and feces and their relative abundance, the

metabolism of NOA 407855 in mice primarily involves hydrolysis of the ester moiety to form

Metabolite M2, which is the primary component excreted in urine and feces. To a minor extent,

Metabolite M2 may also undergo a number of secondary reactions to produce variety of minor

metabolites. These secondary reactions include: hydroxylation, oxidation, hydrolysis,

dealkylation, ring formation, and cleavage of the ether bond in the oxadiazepine moiety (See

proposed pathway in Figure 1). Based on the metabolites identified, the metabolism of NOA

407855 in the mouse proceeds by the same major pathways as in the rat. This metabolism study

in the mouse is classified acceptable/non-guideline.

46203340 Pinto, P.J. (2003) NOA 407855: Dietary toxicokinetic study in mice. Central

Toxicology Laboratory, Cheshire, UK. Laboratory Study No.: KM1506,

November 27, 2003. Unpublished

Executive Summary: In a non-guideline study designed to correlate the levels of Metabolite

M2 (NOA 407854) in the blood with the ingestion of NOA 407855 in the diet, four groups of
79

C57Bl/10JfCD-1 mice (24/sex/dose group) were fed diets containing NOA 407855 (97.2% ai,

Lot #EZ005006) for at least 39 consecutive days. Two groups were fed diets containing NOA

407855 at 1000 or 2500 ppm for the entire period; the third group was fed at 2500 ppm for 7

days, followed by 5000 ppm for at least 32 consecutive days; and the fourth group was fed at

2500 ppm for 7 days, followed by 5000 ppm for 14 days, and then 7000 ppm for at least 18 days. 

A fifth group of mice (3 or 4/sex) of the same source and strain served as controls for the

duration of the study. All animals continued to receive their respective test diet up until the time

of termination and blood sampling.

There were no effects of treatment on survival, clinical observations, or food consumption. At

$ 5000 ppm, adjusted body-weights were decreased (decreased 3-12%; p# 0.05) in the males

generally throughout treatment and in the females on days 2, 36 and 40. Overall body-weight

gains, calculated by the reviewers, were decreased (decreased 21-50%; statistics not performed)

in both sexes at this dose. Food utilization was decreased (p# 0.05) in the males for weeks 2-3

(decreased 64-65%) and in the females for the overall (weeks 1-5) study (decreased 39-68%).

Additionally at 7000 ppm, adjusted body-weights were decreased (decreased 7%; p# 0.05) in the

females on day 29. Food utilization was decreased (p <= 0.05) in the females for weeks 4-5

(decreased 104%) and in the males for the overall (weeks 1-5) study (decreased 50%).

Concentrations of M2 in blood on Study days 40 and 41 averaged 1.7-2.3 mg/kg at 1000 mg/kg,

4.6-7.4 mg/kg at 2500 ppm, 11.8-12.7 mg/kg at 5000 ppm, and 17.0-20.8 mg/kg at 7000 ppm. 

Linear regression showed a direct correlation between the concentration of M2 in the blood and

the concentration of the test material in the diet, with R2

 = 0.96 for females and 0.98 for males.

There were no apparent differences in M2 blood concentrations between sexes or time of blood

sampling at any dose. 

This mouse study is classified acceptable/non-guideline and is adequate for the purposes for

which it was intended.

46203342 Smith, A.D. (2003) NOA 407855: EC 100 formulation (A12303C): In Vivo

dermal penetration study of NOA 407855 in the rat (NAFTA). Central

Toxicology Laboratory, Alderley Park, Macclesfield, Cheshire, UK. Laboratory

Study Id.: CTL No. UR0777, October 31, 2003. Unpublished

Executive Summary: In an in vivo dermal penetration study (MRID 46203342), [pyrazole-3, 5-

14C] NOA407855 (>95% radiochemical purity, lot/batch #EZ005006) was suspended in an

emulsifiable concentrate (EC) formulation and applied neat or as aqueous dilutions to

approximate exposure to the undiluted commercial formulation and to the dilute aqueous spray

used in the field. The formulated test substance was administered to the shaved intact skin (10

cm2

) of 4 male Alpk:APfSD (Wistar-derived) rats/time point/dose at dose levels of 5 and 25

:g/cm2 for the aqueous dilutions (1/200 and 1/40) and 400 :g/cm2 for the neat EC formulation

for a 4- or 10-hour exposure period. At the end of the exposure period, the skin of each rat was

washed, and 4 rats/time point/dose were sacrificed for examination of dermal-absorption. A

further 4 rats/dose were exposed for 10 hours and then retained for 24 hours after the skin was

washed to determine further post-exposure absorption. In addition, in vitro studies were

conducted using excised rat skin (MRID 46200343) and human skin (MRID 46200344) mounted
80

in a static diffusion cell apparatus to compare dermal-absorption. The dosing regimen used in

the in vitro studies was the same as in the in vivo study, except that an additional dose level of

1000 :g/cm2 was employed for human skin using the neat EC formulation. Absorption from

excised skin samples was examined after 10- and 24-hour exposure durations, except at the 1000

μg/cm2 dose level which used only a 10-hour exposure.

For the in vivo rat study, total recovery of the applied dose ranged from 84-96% for all dose

groups.

For the neat EC formulation (400 :g/cm2

), 17% of the dose was absorbed after 4 hours and 30%

dose after 10 hours, increasing to 36% dose over the following day (24 hours post-exposure). 

Regardless of exposure duration, 7% dose remained available in or on the skin for potential

absorption, with 1.3-1.4% of the dose in the stratum corneum. At 24 hours post-exposure, the

potentially absorbable dose declined to 5.3% dose, with 1.4% of the dose in the stratum

corneum. Most of the absorbed radioactivity was excreted in the urine (including cage wash),

accounting for approximately 30% of the applied dose (83% of the absorbed dose), and 3.3%

dose was eliminated in the feces (9% of the absorbed dose). Excretion was virtually complete

within 24 hours, with only 1.5% of the dose being recovered in the GI tract and carcass.

For the 1/40 aqueous spray dilution (25 :g/cm2

), absorption was markedly lower than for the EC

formulation, with only 0.7 and 1.6% of the dose being absorbed by 4 and 10 hours, respectively.

After a 10-hour exposure and washing, there was an increase in absorption up to 3.8% dose by

24 hours post-dose. Potentially absorbable radioactivity in or on the skin following washing

accounted for 2.6-3.1% of the dose at all sampling intervals and was primarily associated with

the stratum corneum (2.0-2.3% dose). As with the high-dose group, most of the absorbed

radioactivity was excreted within 24 hours in the urine (66% of absorbed dose) and feces (11%

of absorbed dose).

For the 1/200 aqueous spray dilution (5 :g/cm2), absorption was lower than for the EC

formulation but greater than for the 25 :g/cm2 group. The absorbed dose accounted for 4% of

the dose after a 4-hour exposure and 14% dose after a 10-hour exposure, increasing to 17% dose

the day after the 10-hour exposure. Potentially absorbable radioactivity in or on the skin

following washing accounted for 11.3 and 13.7% of the dose following the 4- and 10-hour

exposures, respectively, and declined to 7.0% of the dose 24 hours following the 10-hour

exposure. At each sampling interval the majority of the potentially absorbable dose was

associated with the stratum corneum (4.8-7.8% dose) rather than the epidermis (2.2-5.9% dose).

Again, most of the absorbed radioactivity was excreted within 24 hours in the urine (62% of

absorbed dose) and feces (15% of absorbed dose).

For the in vitro studies using excised rat and human skin, total recovery of the applied dose

ranged from 94-104% for all dose groups at both exposure intervals.

As in the in vivo study, absorption from excised rat skin was higher for the neat EC formulation

(400 :g/cm2

) than for either of the 1/200 or 1/40 aqueous dilutions (5 and 25 :g/cm2,

respectively). Following a 10-hour exposure, 40.3% of the applied dose from the EC formulation

was absorbed compared to 34.1 and 25.0% of the applied dose from aqueous dilutions (5 and 25
81

:g/cm2). After 24 hours of exposure, absorption rose to 65.5% dose for the EC formulation and

49.0 and 44.7% dose for the aqueous dilutions. Regardless of exposure duration, potentially

absorbable radioactivity remaining on the skin accounted for 8.8-11.8% dose for the neat EC

formulation, 12.1-12.9% dose for the 1/40 aqueous dilution, and 18.5-20.6% dose for the 1/200

aqueous dilution.

For excised human skin, absorption of radioactivity was minimal regardless of the dosing

vehicle and dose level. Absorption accounted for 0.34-1.55% of the applied dose after a 10-hour

exposure at doses from 5-1000 :g/cm2 and 0.36-1.84% of the applied dose after a 24-hour

exposure at doses from 5-400 :g/cm2. Potentially absorbable radioactivity remaining in or on

the skin (stratum corneum and epidermis) accounted for 2.42-3.61% dose in the $25 :g/cm2

 dose

groups and 8.49-8.80% dose in the 5 :g/cm2 dose group. Thus, in the in vitro studies, absorption

was considerably higher in rat skin than in human skin. Additionally, absorption of the test

substance in the in vivo rat study was comparable to the absorption in the in vitro study with rat

skin. Therefore, the data may suggest that in vivo absorption in humans would be considerably

lower than in the rat.

This study is classified as acceptable/guideline and satisfies the guideline requirements (OPPTS

870.7600; OECD Draft Guidance Document for the Conduct of Skin Absorption Studies, No. 28,

Dec. 2000 & OECD Guidance for the Testing of Chemicals - Draft New Guideline 428: Skin

Absorption: In vitro Method, Dec. 2000 & OECD Guideline for the Testing of Chemicals - Draft

New Guideline 427: Skin Absorption: In vivo Method, Dec. 2000) for a dermal penetration study

in rats.

46224808 Gerspach, R. (2003) 18-month carcinogenicity study in mice (gavage) (includes

final report amendment no. 1 replaces EPA MRID 46203313). RCC Ltd.,

Toxicology, Stein, Switzerland. Laboratory Study No.: 20011039, December 12,

2003. Unpublished.

Executive Summary: In a carcinogenicity study (MRIDs 46224808, 46224807, and 46203310),

NOA- 407855 (Pinoxaden; 97.2% a.i.; Batch # EZ005006) in 0.5% (w/v)

carboxymethylcellulose, 0.1% (w/v) aqueous Tween 80 in distilled water was administered by

daily gavage at a dose volume of 10 mL/kg bw to Crl:CD-1(ICR)BR mice (70 /sex/dose) at

doses of 0, 5, 40, 300, or 750 mg/kg bw/day for up to 78 weeks.

No treatment-related effects were observed on food consumption.

Survival was decreased in males in the 40 (57%), 300 (47%) and 750 mg/kg/day (47%) when

compared to controls (83%) and the 5 mg/kg/day (79%) groups. 

At $300 mg/kg bw/day, body-weight in females decreased (p#0.05) by 6-23% (at weeks 77 and

78 at 300 mg/kg bw/day and generally during weeks 23-78 at 750 mg/kg bw/day). A decrease

(p#0.01) was also observed in overall (weeks 1-78) body-weight gain in the females (decreased

38-84%). Overall (weeks 1-77) food efficiency was decreased (p#0.05) in both sexes (0.5-0.9%

treated vs 1.1-1.5% controls; not reported for 750 mg/kg bw/day females). Relative to body liver

weight was increased (p#0.05) in both sexes (55.8-71.4% treated vs 49.0-50.1% controls). 

Minimal to marked glycogen deposition was observed (# affected/70) in the liver of the males
82

(46-51 treated vs 33 controls) and females (55-57 treated vs 50 controls), and severity increased

with dose. Moderate to marked glycogen deposition was observed in the liver of the males (4-8

treated vs 0 controls) and females (8-21 treated vs 1 control). 

At 750 mg/kg bw/day, the incidence of tonic convulsions in males, piloerection in both sexes,

and hunched posture in females were increased. In males, body-weight was decreased (p#0.05)

generally during week 35-78, and in body-weight gain at weeks 1-13, 1-27, 1-51, and 1-78, and

the decrease grew with time. Water consumption was increased (p#0.05) generally throughout

the study in the males and females. Absolute liver weight was increased (p#0.01) in both sexes. 

The relative to body kidney weight was increased (p#0.01) in the females, and minimal to

moderate tubular atrophy and casts were increased. Glycogen deposition was observed in the

liver of the $300 mg/kg bw/day males (minimal to marked in 46-51 treated mice vs minimal to

slight in 33 control mice) and the $300 mg/kg bw/day females (minimal to marked in 55-57

treated mice vs minimal to moderate in 50 control mice). In the kidney of the 750 mg/kg bw/day

females, the incidence of minimal to slight tubular atrophy was increased (19 treated vs 8

controls), as was minimal to moderate tubular casts (38 treated vs 25 controls). 

Minimal to marked congestion was observed in the liver, kidney, and lung in the $40 mg/kg

bw/day males (11-31 treated vs 2-7 controls) and $300 mg/kg bw/day females (8-15 treated vs 0-

4 controls). Slight to moderate congestion was also observed in the adrenal gland in the 750

mg/kg bw/day males (8 treated vs 0 controls). There was a dose-related increase in the incidence

of hyalinosis of the lung in males in the 40, 300 and 750 mg/kg/day groups (6, 11 and 29%,

respectively; control: 3%) and in females in the 750 mg/kg/day group (27%; control: 7%). In

addition, the severity of the hyalinosis increased with dose in males in the 40, 300 and 750

mg/kg/day groups and in females in the 300 and 750 mg/kg/day groups. There was also a doserelated increase in “pus” in the nose in males in the 300 and 750 mg/kg/day groups when

compared to controls (9, 11 and 0%, respectively). Females in the 300 and 750 mg/kg/day

groups had increase in an inflammatory response in the nose: pus (11 and 41%, respectively;

control 0%), inflammatory cell infiltration (39 and 53%, respectively; control: 10%) and purulent

infiltration (3 and 16%, respectively; controls: 0%). 

A NOAEL/LOAEL could not be determined. The study could not be interpreted due to

gavage errors and lung involvement.

At the doses tested, there were increases in the incidence of bronchiolo-alveolar carcinomas in

the 40 and 300 mg/kg bw/day males (11-13% treated vs 4% controls) and combined adenomas

and carcinomas in the 300 mg/kg bw/day males (26% treated vs 16% controls). In the 750

mg/kg bw/day males, positive trends (p#0.05) were observed in the incidence of adenomas (14%

treated vs 11% controls), carcinomas (7% treated vs 4% controls), and combined adenomas and

carcinomas (17% treated vs 16% controls). The incidences of bronchiolo-alveolar adenomas,

carcinomas, and combined adenomas and carcinomas at 750 mg/kg bw/day were within the

historical control range, and the incidence of carcinomas only slightly exceeded the historical

control range at 300 mg/kg bw/day (13% treated vs 2-12% historical controls). The incidence of

these lesions in the females was similar to controls tumor incidence when compared to controls. 

Dosing was considered adequate based on decreased survival in males, and decreased food

efficiency, body-weight and body-weight gain, and pathological effects in the lungs, liver and

kidneys in both sexes. 
83

It was the general consensus of the Cancer Peer Review Committee that the study was not

interpretable and not useful for risk assessment. There was increased mortality at 40, 300 and

750 mg/kg/day in males. The occurrence of gavage error together with lung involvement

confounded the results of the study.

This study is classified as Unacceptable/guideline and does not satisfy the guideline

requirements (OPPTS 870.4200b; OECD 451) for a carcinogenicity study in mice. The study

can not be upgraded.

46224809 Bachmann, M. (2003) 24-month carcinogenicity and chronic toxicity study in rats

(gavage) (includes final report amendments numbers 1 and 2 replaces EPA MRID

46203312). RCC Ltd. Toxicology, Stein, Switzerland. Laboratory Study Id.:

RCC No. 20001124, September 10, 2003. Unpublished.

Executive Summary - In this combined chronic toxicity/carcinogenicity study (MRID

46224809), NOA 407855 technical (Pinoxaden; 97.2% a.i.; Batch No.: EZ005006) in 0.5%

carboxymethylcellulose, 0.1 % Tween 80 in distilled water was administered for 24 months by

daily gavage to 80 HanIbm:WIST rats/sex/dose at doses of 0, 1, 10, 100, 250, or 500 mg/kg/day

in a volume of 10 mL/kg bw. Additionally, 10 rats/sex/dose were treated similarly and sacrificed

at 12 months. 

No treatment-related effects were observed on food consumption or ophthalmoscopic

examination. No treatment-related adverse-effects were observed on hematology.

Several indications of systemic toxicity were observed. At $250 mg/kg/day, survival was

decreased in males, and the incidences of hunched posture and piloerection were increased. In

the $250 mg/kg/day groups, body-weights and body-weight gains were decreased, and water

consumption was increased. The surviving 500 mg/kg/day males were terminated at week 61

due to continuously increasing spontaneous death. Nephrotoxicity was indicated by numerous

clinical and pathological parameters. Decreased in serum glucose was observed in both sexes at

doses 250 and 500 mg/kg/day. At $250 mg/kg/day, the following evidence supported

nephrotoxicity: (I) increased serum urea and creatinine in the males; (ii) increased urine volume

in both sexes generally throughout treatment; (iii) decreased relative (to body) kidney weights in

the females at week 105; (iv) increased incidence of surface granulation in the kidney at interim

(males only) and terminal sacrifices (both sexes); (v) increases in incidence and severity of

chronic nephropathy in males at week 105; and (vi) increases in incidence and severity of renal

pelvis dilatation in females at week 105. At 500 mg/kg/day, the following evidence supported

nephrotoxicity: (I) increased serum urea and creatinine in the females; (ii) increased urinary

ketones in the females; (iii) increased epithelial cells in the urine of both sexes; (iv) increased

urinary casts in the females; (v) increased absolute and relative kidney weights in males at week

53; (vi) increased incidence of surface granulation in the kidney of the females at week 53; and

(vii) increased incidences of chronic nephropathy, renal tubular vacuolation, and renal cysts in

the females at week 105. At week 105 in the 250 mg/kg/day males, increases were observed in

incidence and/or severity of fibrous osteodystrophy and parathyroid hyperplasia, accompanied

by increased relative thyroid and parathyroid weight. The Sponsor suggested that these were

secondary findings due to severe renal damage. 
84

Additional observations were made in the females at the terminal sacrifice. Grossly, an

increased incidence of thickened small intestine was observed at $250 mg/kg/day. Epithelial

thickening of the small intestine was observed microscopically at 500 mg/kg/day, as was

ulceration of the large intestine. A cortical fatty change was observed in the adrenal glands at

500 mg/kg/day, accompanied by an increased relative adrenal weight. Mast cell infiltration of

the mesenteric lymph node at > 250 mg/kg/day and white pulp atrophy in the spleen at 500

mg/kg/day were also observed. 

The LOAEL is 250 mg/kg bw/day, based on mortality, clinical signs, and increased serum

urea and creatinine in males, and decreased body-weights and body-weight gains,

increased water consumption and incidence of urinalysis findings, kidney surface

granulation, and microscopic renal lesions in both sexes. The NOAEL is 100 mg/kg

bw/day.

The incidence of leiomyosarcoma (2 in the stomach; 1 in the body cavity) was increased in the

250 mg/kg/day males (4%) compared to concurrent (0%) and historical (0-2%) controls. 

Leiomyosarcomas were also observed in the spleen of one male in each of the 1 and 10

mg/kg/day groups, in the stomach of one female in the 10 mg/kg/day group and in the uterus of

a female control rat. Additionally, a leiomyoma was observed in the small intestine of one male

in the 100 mg/kg/day group and in the uterus of a female control rat. The incidence of other

tumors occurred in only a single animal, was similar to concurrent controls, and/or was within

the historical control range. Dosing was considered adequate based on decreased survival, bodyweight and body-weight gain, and nephrotoxicity, as well as other indications of toxicity.

This study is classified as acceptable/guideline and satisfies the guideline requirements (OPPTS

870.4300; OECD 453) for a combined chronic toxicity/carcinogenicity study in rats.

46448801 Pinto, P. (2004) NOA 407855 Tech.; 80-week carcinogenicity study in mice

(includes final report amendment 1). Central Toxicology Laboratory, Alderly

Park, Macclesfield, Cheshire, UK. Laboratory Study No.: CTL Number PM1280,

December 22, 2004. Unpublished.

Executive Summary: In a carcinogenicity study (MRIDs 46448801), NOA- 407855

(Pinoxaden; 97.2% a.i.; Batch # EZ005006) was administered in the diet to C57BL/10Jf

CD-1

mice (50 /sex/dose) at doses of 0, 150, 500, 1500 or 4000 ppm (representing mean dosages of: 0,

16.3, 60.7, 181.2 and 573.7 mg/kg bw/day, respectively, in male mice; and 0, 20.2, 75.7, 216.5

and 706.4 mg/kg bw/day, respectively, in female mice for up to 80 weeks.

Animals in the 4000 ppm group were terminated at week 40 due to what the sponsor considered

to be excessive decreases in body-weight gain in males and females (31 and 33%, respectively). 

Food consumption was statistically significantly increased in males fed 4000 ppm in the diet

from weeks 11 to 16 and weeks 28-36, and in females in fed 4000 ppm in week 11. Food

utilization was significantly decreased in males and females fed 4000 ppm in the diet from

weeks 1-4 (14 and 23%, respectively), 9-13 (25 and 35%, respectively) and generally during the

whole time period of rapid growth (1-13 weeks/18 and 27%, respectively). 

The mean body-weights of males and females in the 1500 ppm group were statistically
85

significantly decreased beginning at week 2 when compared to controls. Males in the 1500 ppm

group reached a maximum decrease of 10% relative to controls at week 55 and 63. Whereas,

females reached their maximum decrease of 9% relative to controls at week 81. Mean bodyweight gain was similar across dose levels for males. Female body-weight gain was variable, but

was decreased 18% in females in the 1500 ppm group when compared to controls from weeks 1-

81. Food utilization was decreased in males between weeks 1-4 (10%) and weeks 1-13 (20%). 

There was a slight increase in the number of females in the 1500 ppm group (3/50) with pale

livers or pale spots/areas in the liver (1/50) compared to females in the 0 (1/50), 150 (1/50) and

500 (0/50) ppm groups. There was an increase in the incidence of mononuclear cell infiltration

in the pancreas of females in the 1500 ppm group (16/50; 32%) when compared to the control

(8/49; 16%), 50 ppm (8/48; 17%) and 500 ppm (9/48; 19%) groups. 

Females in the 500 ppm had a decrease of approximately 5% in body-weight when compared to

controls beginning at week 35. 

The LOAEL was not determined. The NOAEL is 1500 ppm (181.2 mg/kg/day and 216.5

mg/kg bw/day, respectively) in males and females. 

This study is classified as Unacceptable/guideline and does not satisfy the guideline

requirements (OPPTS 870.4200b; OECD 451) for a carcinogenicity study in mice. Dosing was

inadequate. The study can not be upgraded.

Metabolite SYN 502836 (M6)

46203238 Brammer, A. (2003) SYN 502836 (Metabolite of NOA 407855): 90 Day Dietary

Toxicity Study in Rats (Includes Report Amendment 001): Final Report. Project

Number: PR1258, TL/PR1258/REG/AM/002, CTL/PR1258/REG/REPT.

Unpublished study prepared by Central Toxicology Lab (Syngenta). 939 p.

Executive Summary - In this subchronic oral toxicity study (MRIDs 46203238 and 46203232),

12 Alpk:APfSD rats/sex/dose were exposed to SYN 502836 (metabolite of Pinoxaden; 99% a.i.;

Batch #: KI-6513/10 M) in the diet at concentrations of 0, 300, 3000, or 12,000 ppm nominally

(equivalent to 0/0, 23.9/26.8, 246.8/266.4, and 977.5/1034.9 mg/kg/day in males/females) for up

to 90 days. 

No treatment-related effects were observed on mortality, clinical signs, functional observational

battery, motor activity tests, body-weight, food consumption, food efficiency, ophthalmoscopic

examination, hematology, clinical chemistry, organ weights, or necropsy.

Severity of proteinuria increased in all treated males. The following microscopic lesions were

observed (minimal severity, # affected/12 treated vs #/12 controls) at 12,000 ppm: (I) hepatitis in

males (8 vs 4); (ii) renal tubular basophilia in females (6 vs 3); and (iii) interstitial mononuclear

cell infiltration in the kidney in females (4 vs 0). Toxicity was not corroborated in the liver or

kidney. The parent can cause hepatic and renal toxicity; therefore, effects in the liver and kidney

are considered equivocal.

The LOAEL was not observed. The NOAEL is 12,000 ppm (equivalent to 977.5/1034.9
86

mg/kg/day in males/females; approximately the limit dose).

This study is classified as acceptable/guideline and satisfies the guideline requirements (OPPTS

870.3100a; OECD 408) for a subchronic oral toxicity study in the rat. 

46203316 Callander, R. (2003) SYN 502836 (Metabolite of NOA 407855): Bacterial

Mutation Assay in S. typhimurium and E. coli: Final Report. Project Number:

YV6182. Unpublished study prepared by Central Toxicology Lab (Syngenta). 31

p.

Executive Summary - In two independent reverse gene mutation assays in bacteria (MRID

46203316), Salmonella typhimurium strains TA98, TA100, TA1535, and TA1537 and

Escherichia coli strains WP2 uvrA (pKM101) and WP2 (pKM101) were exposed to SYN

502836 (a metabolite of NOA 407855 tech.; Pinoxaden; 99% a.i., Batch # KI 6513/3M) in

dimethylsulfoxide (DMSO) at concentrations of 100, 200, 500, 1000, 2500, or 5000 μg/plate in

the presence and absence of mammalian metabolic activation (+/-S9). The standard plate

incorporation method was performed in Trial 1 (+/-S9) and Trial 2 (-S9), while a pre-incubation

step was added in Trial 2 (+S9). Standard strain-specific mutagens served as positive controls.

SYN 502836 was tested up to the limit dose (5000 :g/plate). Cytotoxicity (as indicated by

reduction in number of revertants) was limited to Trial 2 at 5000 :g/plate in strains TA100 (+/-

S9), TA1535 (-S9), TA1537 (-S9), and WP2 uvrA (pKM101, +/-S9); and at $2500 :g/plate in

strain WP2 (pKM101, -S9). No marked increases in the number of revertants were observed at

any concentration in any strain in either trial. The positive controls induced marked increases in

revertant colonies compared to controls in both trials. There was no evidence of induced

mutant colonies over background.

The study is classified as Acceptable/Guideline and satisfies the guideline requirements

(OPPTS 870.5100; OECD 471) for in vitro mutagenicity (bacterial reverse gene mutation) data. 

Metabolite SYN 505887 (M10)

46224810 Callander, R. (2003) SYN 505887 (Metabolite of NOA 407855): Bacterial

Mutation Assay in S. Typhimurium and E. Coli: Final Report. Project Number:

YV6549. Unpublished study prepared by Central Toxicology Lab. (Syngenta). 31

p.

Executive Summary - In two independent reverse gene mutation assays in bacteria (MRID

46224810), Salmonella typhimurium strains TA98, TA100, TA1535, and TA1537 and

Escherichia coli strains WP2 uvrA (pKM101) and WP2 (pKM101) were exposed to SYN

505887 (a metabolite of NOA 407855 tech.; [Pinoxaden]; 99% a.i., Batch # KI 6721/4) in

dimethylsulfoxide (DMSO) at concentrations of 100, 200, 500, 1000, 2500, or 5000 μg/plate in

the presence and absence of mammalian metabolic activation (+/-S9). The standard plate

incorporation method was performed in Trial 1 (+/-S9) and Trial 2 (-S9), while a pre-incubation

step was added in Trial 2 (+S9). To clarify the results obtained in Trials 1 and 2, a third plate

incorporation assay (+S9) was performed using S. typhimurium strain TA1535 only. Standard

strain-specific mutagens served as positive controls.
87

SYN 505887 was tested up to the limit dose (5000 :g/plate). Cytotoxicity (as indicated by

reduction in number of revertants) was limited to strain TA98 at $1000 :g/plate (+S9) in Trial 1. 

Increases ($2x the solvent control) in the number of revertants were observed in strain TA1535

at 100 and 2500 :g/plate in Trial 1 (+S9) and at 5000 :g/plate in Trial 3 (+S9), but were not

observed in Trial 2. These findings were not considered to be treatment-related, because they

were not reproducible. No marked increases in the number of revertants were observed in any

other strain under any test condition in either trial. The condition of the background lawn was

not reported for any trial. The positive controls induced marked increases in revertant colonies

compared to controls in all trials. There was no evidence of induced mutant colonies over

background.

The study is classified as Acceptable/Guideline and satisfies the guideline requirements

(OPPTS 870.5100; OECD 471) for in vitro mutagenicity (bacterial reverse gene mutation) data. 

46224812 Fox, V. (2003) SYN 505887 (Metabolite of NOA 407855): In vitro Cytogenetic

Assay in Human Lymphocytes: Final Report. Project Number: SV1214.

Unpublished study prepared by Central Toxicology Lab. (Syngenta). 31 p.

Executive Summary - In two independent trials of a mammalian cell cytogenetics assay

(chromosome aberration; MRID 46224812), lymphocyte cultures were prepared from human

peripheral blood and exposed to SYN 505887 (a metabolite of NOA 407855 tech.; Pinoxaden;

99% a.i., Batch # KI 6721/4) in dimethylsulfoxide (DMSO) at concentrations of 10, 50, 100,

250, 500, 750, 1000, 1500, 2500, and 3484 :g/mL for 3 hours with a 17 hour recovery period

(Trial 1, +/-S9); 100, 250, 500, 750, 1000, 1500, 2500, and 3484 :g/mL for 20 hours with no

recovery period (Trial 2, -S9); or 250, 1500, 2500, and 3484 :g/mL for 3 hours with a 17 hour

recovery period (Trial 2, +S9).

SYN 505887 was tested up to 3484 :g/mL (limit dose, 10 mM). Cytotoxicity (as evidenced by

reduced mitotic index) was noted in Trial 1 at 3484 :g/mL (-S9) and $1500 :g/mL (+S9), and in

Trial 2 at $750 :g/mL (-S9). There were no treatment-related increases in the percent aberrant

cells (excluding gaps) noted in either trial in the presence or absence of S9. The positive

controls induced the appropriate response in both trials in the presence and absence of S9. 

There was no evidence of chromosome aberrations induced over background in the

presence or absence of S9-activation.

This study is classified as Acceptable/Guideline and satisfies the Guideline requirement

(OPPTS 870.5375, OECD 473) for in vitro mutagenicity (chromosome aberration) data.

46224813 Fox, V. (2004) SYN 505887 (Metabolite of NOA 407855): Rat Bone Marrow

Micronucleus Test: Final Report. Project Number: SR1236. Unpublished study

prepared by Central Toxicology Lab. (Syngenta). 25 p.

Executive Summary - In a bone marrow micronucleus assay (MRID 46224813), 5 non-fasted

male Alpk APf

SD rats/dose/sacrifice time were treated once via gavage (20 mL/kg) with SYN

505887 (a metabolite of NOA 407855 [Pinoxaden]; 99% a.i., Batch # KI 6721/4) in 0.5% (w/v)

aqueous carboxymethylcellulose (CMC) at doses of 0 or 2000 mg/kg bw. Bone marrow cells
88

were harvested at 24 or 48 hours post-dosing. Cyclophosphamide (20 mg/kg) served as the

positive control.

SYN 505887 was tested up to the limit dose (2000 mg/kg); however, no evidence of bone

marrow toxicity (decreased % PCE) was observed at the 24 or 48 hour sampling times. No

clinical signs of toxicity were noted in any animal. No abnormalities were observed in the

internal organs of the treated animals. No significant increase in micronucleated polychromatic

erythrocytes (MPCEs) was observed at either 24 or 48 hours post-dosing. The positive control

induced the appropriate response. There was no significant increase in the frequency of

micronucleated polychromatic erythrocytes in bone marrow compared to controls.

The study is classified as Acceptable/Guideline and satisfies the guideline requirement (OPPTS

870.5395; OECD 474) for in vivo cytogenetic mutagenicity data. 

46224814 Clay, P. (2004) SYN 505887 (Metabolite of NOA 407855): in vivo Rat Liver

Unscheduled DNA Synthesis Assay: Final Report. Project Number: SR1212.

Unpublished study prepared by Central Toxicology Lab. (Syngenta). 27 p.

Executive Summary - In an in vitro/in vivo unscheduled DNA synthesis assay (MRID

46224814), rat hepatocyte cultures were prepared from 3 male (Alpk:APf

SD) rats/sacrifice time

that were treated orally (gavage, 20 mL/kg) once with SYN 505887 (a metabolite of NOA

407855 tech.[Pinoxaden]; 99% a.i., Batch # KI 6721/4) in 0.5% aqueous carboxymethylcellulose

at a dose of 2000 mg/kg (limit dose). Hepatocytes were harvested after 2 or 16 hours of

exposure. Additionally, 2 rats/sacrifice time were similarly treated with the vehicle or positive

control (–nitrosodimethylamine).

SYN 505887 was tested up to the limit dose (2000 mg/kg). There were no adverse clinical signs

of toxicity in the treated animals or evidence of excessive cytotoxicity in any of the cultures. 

There were no marked increases observed in mean net nuclear grains (NNG) or percent cells in

repair (NNG $5) at 2 or 16 hours post-dosing compared to controls. The positive control

induced the appropriate response. There was no evidence that unscheduled DNA synthesis,

as determined by radioactive tracer procedures (nuclear silver grain counts), was induced.

The study is classified as Acceptable/Guideline and satisfies the Guideline requirement (OPPTS

870.5550; OECD 486) for other genotoxic mutagenicity data Although, the dosing formulation

was not analyzed for the amount of test substance, this is not considered to be a major deficiency

that would have altered the results of the study, since the limit dose was tested and the testing

laboratory adheres to GLP regulations, and has a QA unit.

Metabolite 447204(M3)

46203240 Twomey, K. (2003) NOA 447204 (Metabolite of NOA 407855): 90 Day Dietary

Toxicity Study in Rats: Final Report. Project Number: PR1253,

CTL/PR1253/REG/REPT. Unpublished study prepared by Central Toxicology

Lab (Syngenta). 973 p.

Executive Summary - In this subchronic oral toxicity study (MRIDs 46203240, 46203231, and
89

46203233), 12 Alpk:APfSD rats/sex/dose were exposed to NOA 447204 (metabolite of

Pinoxaden; 99% a.i.; Batch #: KI 6385/17) in the diet for up to 90 days at concentrations of 0,

150, 1000, or 6000 ppm nominally (equivalent to 0/0, 15.0/15.2, 99.2/98.8, and 600.6/645.4

mg/kg bw/day in males/females). 

No treatment-related effects were observed on mortality, clinical signs, food consumption,

ophthalmoscopic examination, or hematology.

In the 6000 ppm group, body-weights were decreased throughout the study, except week 3

(males only). Decreased (p#0.05) body-weight was observed in males at days 2, 3, and 6

(decreased 2-3%) and in females at day 2 and weeks 3-14 (decreased 2-11%). Overall (weeks 1-

14) body-weight gains were decreased in both sexes (decreased 10-19%). Decreased (p#0.05)

food efficiency was observed in the males at weeks 1-4 (decreased 9%) and 5-8 (decreased

23%). Decreased (NS) food efficiency was observed throughout the study in the females. 

Decreased (p#0.05) overall (weeks 1-13) food efficiency was observed in males (decreased 9%)

and females (decreased 22%). Water consumption was decreased throughout the study in the

females and was statistically different (p#0.05) at weeks 3, 5, 12, and 13 (decreased 23-32%). 

At 6000 ppm, there were indications of hepatotoxicity. Increased (p#0.05) gamma-glutamyl

transferase was observed in males (incr 13%) and females (incr 53%). Decreased (p#0.01)

triglycerides were observed in males (decreased 27%). Increased (p#0.01) cholesterol was

observed in the females (incr 21%). Increased (p#0.05) absolute and adjusted (for terminal

body-weight) liver weights were observed in both sexes (incr 22-35%). Two males (n=12) had

enlarged livers (vs 0 in controls and other doses). Minimal to moderate panlobular reduced

glycogen/increased eosinophilia in the liver was observed (n=12) in the males (12 treated vs 0

controls) and in the females (11 treated vs 0 controls; slight severity). 

In the 6000 ppm males, there were indications of nephrotoxicity. Increased severity of

proteinuria and incidence and severity of ketonuria (9/12 treated vs 4/12 controls) were

observed. Increased (p#0.05) absolute and adjusted kidney weights were observed (incr 11-

17%). Additionally, minimal chronic progressive nephropathy was observed (6/12 treated vs

2/12 controls).

The LOAEL is 6000 ppm (equivalent to 600.6/645.4 mg/kg bw/day in males/females), based

on decreased body-weight and body-weight gain and food efficiency in both sexes, and

evidence of hepatotoxicity in both sexes and nephrotoxicity in males. The NOAEL is 1000

ppm (equivalent to 99.2/98.8 mg/kg bw/day in males/females).

This study is classified as acceptable/guideline and satisfies the guideline requirements (OPPTS

870.3100a; OECD 408) for a subchronic oral toxicity study in the rat. 

46203315 Callander, R. (2003) NOA 447204, Metabolite of Pinoxaden: Bacterial Mutation

Assay in S. Typhimurium and E. coli: Final Report. Project Number: YV6168.

Unpublished study prepared by Central Toxicology Lab (Syngenta). 32 p.

Executive Summary - In two independent reverse gene mutation assays in bacteria (MRID

46203315), Salmonella typhimurium strains TA98, TA100, TA1535, and TA1537 and
90

Escherichia coli strains WP2 uvrA (pKM101) and WP2 (pKM101) were exposed to NOA

447204 (a metabolite of Pinoxaden tech.; Pinoxaden; 99% a.i., Batch # KI 6385/17) in

dimethylsulfoxide (DMSO) at concentrations of 100, 200, 500, 1000, 2500, or 5000 μg/plate in

the presence and absence of mammalian metabolic activation (+/-S9). The standard plate

incorporation method was performed in Trial 1 (+/-S9) and Trial 2 (-S9), while a pre-incubation

step was added in Trial 2 (+S9). To clarify the results obtained in Trials 1 and 2, a third plate

incorporation assay (±S9) was performed using S. typhimurium strain TA1535 only. Standard

strain-specific mutagens served as positive controls.

NOA 447204 was tested up to the limit dose (5000 :g/plate). Cytotoxicity (as indicated by

reduction in number of revertants) was limited to strains TA98 and WP2 (pKM101) at >=2500

:g/plate (-S9) in Trial 1, and strain TA1535 at 5000 :g/plate (+S9) in the repeat trial. No

marked increases in the number of revertants were observed at any concentration in any strain in

any trial. The condition of the background lawn was not reported for any trial. The positive

controls induced marked increases in revertant colonies compared to controls in all trials. There

was no evidence of induced mutant colonies over background.

The study is classified as Acceptable/Guideline and satisfies the guideline requirements

(OPPTS 870.5100; OECD 471) for in vitro mutagenicity (bacterial reverse gene mutation) data. 

46203323 Fox, V. (2003) NOA 447204 (Metabolite of Pinoxaden): In vitro Cytogenetic

Assay in Human Lymphocytes: Final Report. Project Number: SV1135.

Unpublished study prepared by Central Toxicology Lab. (Syngenta). 32 p.

Executive Summary - In two independent trials of a mammalian cell cytogenetics assay

(chromosome aberration; MRID 46203323), lymphocyte cultures were prepared from human

peripheral blood and exposed to NOA 447204 (a metabolite of Pinoxaden tech.; Pinoxaden;

99±2% a.i.; Batch # KI 6385/17) in dimethylsulfoxide (DMSO) at concentrations of 50, 100,

250, 500, 750, 1000, 1500, 2000, 2500, 3000, and 3324 :g/mL for either 3 hours with a 17 hour

recovery period (Trial 1, +/-S9 and Trial 2, +S9) or 20 hours with no recovery period (Trial 2, -

S9).

NOA 447204 was tested up to cytotoxic concentrations (1500 :g/mL, +S9 and $500 :g/mL, -

S9). At 1500 :g/mL, NOA 447204 induced increased (p#0.05) aberration frequencies

(excluding gaps) in the presence of S9 in Trials 1 and 2 (4.5-8.67% treated vs 1.0% solvent

control), and in the absence of S9 in Trial 1 (6.5% treated vs 2.0% solvent control) after a 3 hour

treatment period and a 17 hour recovery period. The significant increases observed equaled or

exceeded the upper limit of the historical control ranges. The positive controls induced the

appropriate response in all assays. There was evidence of chromosome aberrations induced

over background in the presence and absence of S9-activation.

This study is classified as Acceptable/Guideline and not satisfies the Guideline requirement

(OPPTS 870.5375, OECD 473) for in vitro mutagenicity (chromosome aberration) data. 

46203326 Fox, V. (2003) NOA 447204 (Metabolite of Pinoxaden): in vivo Rat Liver

Unscheduled DNA Synthesis Assay: Final Report. Project Number: SR1189.

Unpublished study prepared by Central Toxicology Lab. (Syngenta). 26 p.
91

Executive Summary - In an in vitro/in vivo unscheduled DNA synthesis assay (MRID

46203326), rat hepatocyte cultures were prepared from 3 male (Alpk:APfSD) rats/dose/sacrifice

time that were treated orally (gavage, 10 mL/kg) once with NOA 447204 (a metabolite of

Pinoxaden tech.; Pinoxaden; 99% a.i.; Batch # KI 6385/17) in dried corn oil at concentrations of

625 or 1250 mg/kg. Hepatocytes were harvested after 2 or 16 hours of exposure. Additionally,

2 rats/sacrifice time were treated with the vehicle or positive control (–nitrosodimethylamine).

NOA 447204 was tested up to the maximum tolerated dose (MTD, 1250 mg/kg). There were no

clinical signs of toxicity in the treated animals or evidence of excessive cytotoxicity in any of the

cultures. There were no marked increases observed in mean net nuclear grains (NNG) or percent

cells in repair (NNG $5) at 2 or 16 hours post-dosing compared to controls. The positive control

induced the appropriate response. There was no evidence that unscheduled DNA synthesis,

as determined by radioactive tracer procedures (nuclear silver grain counts), was induced.

The study is classified as Acceptable/Guideline and satisfies the Guideline requirement (OPPTS

870.5550; OECD 486) for other genotoxic mutagenicity data. Although, the dosing formulations

were not analyzed for the amount of test substance, this is not considered to be a major

deficiency that would have altered the results of the study, since the test substance was tested at

the MTD the testing laboratory adheres to GLP regulations, and has a QA unit.

46203328 Fox, V. (2003) NOA 447204 (Metabolite of Pinoxaden): Mouse Bone Marrow

Micronucleus Test: Final Report. Project Number: SM1188. Unpublished study

prepared by Central Toxicology Lab. (Syngenta). 27 p.

Executive Summary - In a bone marrow micronucleus assay (MRID 46203328), 5 non-fasted

male CD-1 mice/dose/sacrifice time were treated once via gavage (10 mL/kg) with NOA 447204

(a metabolite of Pinoxaden [Pinoxaden]; 99% a.i., Batch # KI 6385/17) in dried corn oil at doses

of 0, 200, 400, or 800 mg/kg bw. Bone marrow cells were harvested at 24 (all doses) or 48 hours

(vehicle and 800 mg/kg only) post-dosing. Cyclophosphamide (65 mg/kg) served as the positive

control.

NOA 447204 was tested up to the limit toxicity (800 mg/kg). Clinical signs of toxicity

(decreased activity, hunched posture, pinched in sides, piloerection, and wet and dry urine

staining) were noted in all animals at 800 mg/kg; however, no evidence of bone marrow toxicity

(decreased % PCE) was observed at the 24 or 48 hour sampling times at up to 800 mg/kg. No

significant increase in micronucleated polychromatic erythrocytes (MPCEs) was observed in any

dose at either 24 or 48 hours post-dosing. The positive control induced the appropriate response. 

There was no significant increase in the frequency of micronucleated polychromatic

erythrocytes in bone marrow compared to controls.

The study is classified as Acceptable/Guideline and satisfies the guideline requirement (OPPTS

870.5395; OECD 474) for in vivo cytogenetic mutagenicity data. Although, the dosing

formulation was not analyzed for the amount of test substance, this is not considered to be a

major deficiency that would have altered the results of the study, since the test substance was

tested at a toxic dose level and the testing laboratory adheres to GLP regulations, and has a QA

unit.
92

Contaminant SYN 519312

46203317 Callander, R. (2003) SYN 519312: Bacterial Mutation Assay in S. typhimurium

and E. coli: Final Report. Project Number: YV6422. Unpublished study prepared

by Central Toxicology Lab (Syngenta). 30 p.

Executive Summary - In two independent reverse gene mutation assays in bacteria (MRID

46203317), Salmonella typhimurium strains TA98, TA100, TA1535, and TA1537 and

Escherichia coli strains WP2 uvrA (pKM101) and WP2 (pKM101) were exposed to SYN

519312 (an impurity of Pinoxaden tech.; Pinoxaden; 96% a.i., Batch # BPS 1177/1) in

dimethylsulfoxide (DMSO) at concentrations of 100, 200, 500, 1000, 2500, or 5000 μg/plate in

the presence and absence of mammalian metabolic activation (+/-S9). The standard plate

incorporation method was performed in Trial 1 (+/-S9) and Trial 2 (-S9), while a pre-incubation

step was added in Trial 2 (+S9). Standard strain-specific mutagens served as positive controls.

SYN 519312 was tested up to the limit dose (5000 :g/plate). Cytotoxicity (as indicated by

reduction in number of revertants) was observed in Trial 1 at 5000 :g/plate (+S9) in strains

TA98, TA100, TA1537, and WP2 (pKM101), and at $2500 :g/plate (+S9) in strain TA1535,

and in Trial 2 at 5000 :g/plate (-S9) in strains TA100 and WP2 (pKM101), and at $2500

:g/plate (+S9) in strain WP2 (pKM101). Precipitation of the test material was also observed at

the upper 1-3 concentrations in the presence and absence of S9 in both trials. No marked

increases in the number of revertants were observed at any concentration in any strain in either

trial. The positive controls induced marked increases in revertant colonies compared to controls

in both trials. There was no evidence of induced mutant colonies over background.

The study is classified as Acceptable/Guideline and satisfies the guideline requirements

(OPPTS 870.5100; OECD 471) for in vitro mutagenicity (bacterial reverse gene mutation) data. 
93

Appendix 3. Metabolism Considerations

A-3.0 Introduction

Pinoxaden is a new post-emergence herbicide for control of grass weeds in wheat (including durum)

and barley. The proposed use of pinoxaden is one application per crop season at a rate of 0.036 -

0.062 lb a.i./A at with a PHI of 60 days and REI of 48 hours. The proposed PBI for wheat and

barley is 0 day and for other crops is 30 days; however, HED has requested label amendment

such that to replace “other crops” with “leafy and root crops” and also to add 120-day PBI for

other cereal grains and other crops. A 30-day pre-grazing interval is also included on the label.

A-3.1 Description of Issues and Team Proposal

The registrant has not proposed tolerances for meat, milk, poultry and egg (MMPE) commodities

since feeding studies resulted in residues less than limit of quantitation (LOQ). However, HED

determined that tolerances are needed on MMPE since the feeding studies were not conducted at

>10X and that the livestock metabolism studies indicated that residues are concentrated in some

livestock tissues (liver and kidney).

The following Table summarizes the residues of concern for risk assessment and tolerance

expression. 

Table A-3.1.1: Summary of Metabolites and Degradates to be included in the Risk

Assessment and Tolerance Expression

Matrix Residues included in Risk

Assessment

Residues included in Tolerance

Expression

Plants Primary Crop Pinoxaden, M2, M4 (free &

conjugated), M6

Pinoxaden, M2, M4 (free &

conjugated), M6

Rotational Crop Pinoxaden, M2, M3 (free &

conjugate), M10, M11

No Tolerance Required

Livestock Ruminant Pinoxaden, M2, M4 (free &

conjugated)

Pinoxaden, M2, M4 (free &

conjugated)

Poultry Pinoxaden, M2, M4 (free &

conjugated), M6

Pinoxaden, M2, M4 (free &

conjugated), M6

Drinking Water Pinoxaden, M2, and M3 Not Applicable
94

Table A-3.1.2 Structure of Parent and Metabolites from Plant and Animal Metabolism

Studies.

Name Structure Matrix

M1

(NOA 407855)

(Pinoxaden)

Wheat, Goat, Hen

M2

(NOA 407854)

Wheat, Goat, Hen, Water

M3

(NOA 447204)

Wheat, Rotational Crop, goat, Hen,

Water

M4

(SYN 505164)

Wheat, Goat, Hen

M5 Wheat

M6

(SYN 502836)

Wheat, Goat, Hen
Name Structure Matrix

95

M7 Wheat

M8 Wheat, Rotational Crop

M9 Wheat

M10

(SYN 505887)

Wheat, Rotational Crop, Goat

M11

(SYN 504574)

Wheat, Rotation Crop

M12 Goat
Name Structure Matrix

96

M13 Goat

M14 Wheat

M19 Goat (feces)

M20 Goat (feces) 

M22 Goat (feces) 
Name Structure Matrix

97

M23 Goat (feces)

M24 Goat (feces)

M26 Goat (feces)

M31 Wheat, Hen

M32 Wheat
Name Structure Matrix

98

M33 Hen

M34 Hen

M35 Hen

A-3.2 Nature of the Residue Studies in Plants

Wheat: In order to adequately delineate the fate and disposition of 14C-pinoxaden (8-(2,6-diethylp-tolyl)-1,2,4,5-tetrahydro-7-oxo-7H-pyrazolo[1,2-d][1,4,5]oxadiazepin-9-yl 2,2-dimethylpropionate; also referred to as Pinoxaden or M1) in wheat, four wheat metabolism studies were

performed using either spring wheat or winter wheat with pinoxaden radiolabelled either in the

pyrazol, phenyl or oxadiazepine rings and treated at different timings of application (fall, early

spring & late spring) and at various growth stages (BBCH 13, BBCH 21, BBCH 37-39 & BBCH

49). Furthermore, wheat crop parts were sampled over a wide range of pre-harvest intervals

(PHIs) from immature forage and ears to mature grain, husk and straw.

Pinoxaden was applied as a foliar spray at a rate of either 68.5 g a.i./ha (or 0.0611 lb a.i./A; to

winter wheat as an autumn application at the three leaves unfolded growth stage) including the

safener but no adjuvant; or 64 or 318 g a.i./ha (or 0.057 or 0.283 lb a.i./A; to winter wheat as a

spring application at the first awns visible growth stage) including the safener and an adjuvant;

or 58.1 - 60.0 g a.i./ha (or 0.0518 or 0.0535 lb a.i./A; to spring wheat as an early season

application at the initial tillering growth stage) including the safener and an adjuvant; or 62.0 -

66.0 g a.i./ha (or 0.0553 or 0.0588 lb a.i./A; to spring wheat as a regular spring application at the

flag leaf just visible to flag leaf fully unrolled growth stage) including the safener and an

adjuvant.
99

Radioactivity was detected in all plant parts, and as would be expected, radioactive residues

were highest in immature forage and declined rapidly. The unchanged parent molecule was

detected only up to 14 DAT thus demonstrating rapid metabolization of pinoxaden. The

metabolic profile of pinoxaden in wheat was similar across the three radiolabels thus indicating

that there was minimal cleavage of the bonds between the rings. Throughout the four wheat

metabolism studies, no substantive variation in the metabolic degradation of pinoxaden was

observed. Spring wheat and winter wheat demonstrated similar metabolic profiles. The timing

of application and the growth stage of the wheat plants at application did not have a significant

impact on the qualitative nature of the resulting metabolic pattern, but revealed some quantitative

differences. The difference could be explained by the time interval that the degradation was

allowed to proceed. The longer the PHI and the more mature was the wheat plant at application,

the more extensive was the metabolism.
100

Table A-3.2.1: Summary of Distribution of the Parent and the Metabolites in Wheat Forage when Dosed with 

Following Different Treatment Regimes

Radiolabel Position

(Study No.)

Pyrazol

(99PSA55)

Phenyl

(00PSA58)

Phenyl

(01JS35)

Oxadiazepine

(01JS35)

Phenyl

(01MK16)

Oxadiazepin

(01MK16)

Growth Stage at Application

(Application Rate)

BBCH 13 

(68.5 g a.i./ha)

BBCH 49

(64 g a.i./ha)

BBCH 21

(60 g a.i./ha)

BBCH 21

(58.1 g a.i./ha)

BBCH 37-39

(62 g a.i./ha)

BBCH 37-3

(66 g a.i./ha

PHI 0 day 0 day (3 hours) 0 day (1 hour) 0 day (1 hour) 0 day (1 hour) 0 day (1 hou

Metabolite Fraction Whole tops

TRR = 6.731 ppm

Whole tops

TRR = 1.909 ppm

Whole tops

TRR = 4.420 ppm

Whole tops

TRR = 2.910 ppm

Whole tops

TRR = 3.447 ppm

Whole tops

TRR = 3.885 p

%TRR ppm %TRR ppm %TRR ppm %TRR ppm %TRR ppm %TRR pp

Extractable with 80% Acetonitrile 107.6 Not

given

105.3 Not

given

97.3 Not

given

96.1 Not

given

95.4 Not

given

99.3 No

giv

I1 -- -- -- -- -- -- -- -- -- -- -- -- 

I2 (M7) -- -- -- -- -- -- -- -- -- -- -- -- 

I2a -- -- -- -- -- -- -- -- -- -- -- -- 

I3 (M5) -- -- 0.5 0.009 -- -- -- -- -- -- -- -- 

I4 (M9) -- -- -- -- -- -- -- -- -- -- -- -- I4a (M14) -- -- -- -- -- -- -- -- -- -- -- -- 

I5 -- -- -- -- -- -- -- -- -- -- -- -- 

I6 -- -- -- -- -- -- -- -- -- -- -- -- I7 (M6) -- -- 0.3 0.005 -- -- 0.1 0.003 -- -- -- -- 

I8 -- -- 0.3 0.007 -- -- -- -- -- -- -- -- 

I8a -- -- -- -- -- -- -- -- 0.5 0.017 0.6 0.0I9 (M4) -- -- 64.2 1.225 1.4 0.062 1.0 0.028 9.6 0.331 8.6 0.3

I9a (M31) -- -- -- -- -- -- -- -- -- -- -- -- 

I10 -- -- -- -- -- -- -- -- -- -- -- -- 

I11 (M8) -- -- -- -- -- -- -- -- -- -- -- -- 

I12 -- -- -- -- -- -- -- -- -- -- -- -- 

I13 -- -- -- -- -- -- -- -- -- -- -- -- I14 (M11) -- -- 0.3 0.006 -- -- -- -- -- -- -- -- 

I15 (M2) 66.3 4.465 22.8 0.435 61.9 2.734 60.9 1.773 71.9 2.478 79.0 3.0

I15a (M10) -- -- -- -- -- -- -- -- -- -- -- -- 
Radiolabel Position

(Study No.)

Pyrazol

(99PSA55)

Phenyl

(00PSA58)

Phenyl

(01JS35)

Oxadiazepine

(01JS35)

Phenyl

(01MK16)

Oxadiazepin

(01MK16)

Growth Stage at Application

(Application Rate)

BBCH 13 

(68.5 g a.i./ha)

BBCH 49

(64 g a.i./ha)

BBCH 21

(60 g a.i./ha)

BBCH 21

(58.1 g a.i./ha)

BBCH 37-39

(62 g a.i./ha)

BBCH 37-3

(66 g a.i./ha

PHI 0 day 0 day (3 hours) 0 day (1 hour) 0 day (1 hour) 0 day (1 hour) 0 day (1 hou

Metabolite Fraction Whole tops

TRR = 6.731 ppm

Whole tops

TRR = 1.909 ppm

Whole tops

TRR = 4.420 ppm

Whole tops

TRR = 2.910 ppm

Whole tops

TRR = 3.447 ppm

Whole tops

TRR = 3.885 p

%TRR ppm %TRR ppm %TRR ppm %TRR ppm %TRR ppm %TRR pp

101

I15b -- -- 0.8 0.016 -- -- -- -- 1.8 0.062 2.7 0.1

I15c (M32) -- -- -- -- -- -- -- -- -- -- -- -- 

I16 (M1; pinoxaden) 36.2 2.435 9.8 0.188 30.3 1.339 27.0 0.786 7.3 0.252 5.4 0.2

I17 (M3) 1.9 0.128 1.1 0.022 1.3 0.057 4.7 0.137 1.0 0.034 1.2 0.0

I17a -- -- 2.6 0.050 -- -- -- -- -- -- -- -- 

I18 -- -- 0.4 0.008 -- -- 0.2 0.006 -- -- -- -- I18a 0.1 0.005 0.2 0.006 -- -- -- -- 

I19 -- -- -- -- -- -- -- -- -- -- -- -- 

Unresolved 3.2 0.215 2.1 0.041 2.3 0.103 2.1 0.062 3.2 0.110 1.8 0.0Non-extractable 1.0 0.067 2.2 0.042 0.6 0.027 0.7 0.020 1.4 0.047 0.8 0.0Total extractable 107.6 Not

given

105.3 Not

given

97.3 Not

given

96.1 Not

given

95.4 Not

given

99.3 No

giv

Total identified 104.4 7.028 99.0 1.890 94.9 4.192 93.7 2.727 89.8 3.095 94.2 3.6Total characterized 0.0 0.0 4.1 0.081 0.1 0.005 0.4 0.012 2.3 0.079 3.3 0.1

Total bound 1.0 0.067 2.2 0.042 0.6 0.027 0.7 0.020 1.4 0.047 0.8 0.0Accountability (extractable + bound)

108.6 % 107.5 % 97.9 % 96.8 % 96.8 % 100.1 % 

1- I13a, and I17a are other notations used for M3.2- I1, I9, I3 and M5 are conjugated forms of M4. 3- I7 is a conjugated form of M6.
102

Table A-3.2.2: Summary of Distribution of the Parent and the Metabolites in Wheat Forage when Dosed with 1

Following Different Treatment Regimes.

Radiolabel Position

(Study No.)

Pyrazol

(99PSA55)

Phenyl

(00PSA58)

Phenyl

(01JS35)

Oxadiazepine

(01JS35)

Phenyl

(01MK16)

Oxadiazepine

(01MK16)

Growth Stage at Application

(Application Rate)

BBCH 13

(68.5 g a.i./ha)

BBCH 49

(64 g a.i./ha)

BBCH 21

(60 g a.i./ha)

BBCH 21

(58.1 g a.i./ha)

BBCH 37-39

(62 g a.i./ha)

BBCH 37-39

(66 g a.i./ha)

PHI 14 days 14 days 14 days 14 days 14 days 14 days 

Metabolite Fraction Whole tops

TRR = 0.304

ppm

Whole tops

TRR = 1.434

ppm

Whole tops

TRR =0.834 ppm

Whole tops

TRR =0.635 ppm

Whole tops

TRR =1.021 ppm

Whole tops

TRR = 1.051ppm

%TRR ppm %TRR ppm %TRR ppm %TRR ppm %TRR ppm %TRR ppm 

Extractable with 80%Acetonitrile

94.4 Not

given

99.6 Not

given

91.8 Not

given

98.2 Not

given

95.3* Not

given

93.0* Not

given

I1 2.8 0.0085 0.6 0.009 0.6 0.005 0.7 0.004 2.3 0.023 1.9 0.020 

I2 (M7) 4.6 0.0140 1.0 0.014 3.0 0.025 1.5 0.009 2.8 0.029 4.4 0.046 

I2a -- -- 0.3 0.004 0.2 0.001 0.2 0.001 -- -- -- -- 

I3 (M5) 16.3 0.0496 29.1 0.418 48.9 0.408 35.8 0.228 38.3 0.391 36.3 0.382 

I4 (M9) 3.2 0.0098 0.5 0.008 1.4 0.012 2.5 0.016 0.3 0.003 1.9 0.020 I4a (M14) -- -- 0.6 0.009 -- -- -- -- 2.5 0.026 0.2 0.002 

I5 1.2 0.0036 2.0 0.029 1.5 0.012 2.7 0.017 1.1 0.011 0.7 0.007 

I6 1.2 0.0038 -- -- -- -- -- -- -- -- -- -- 

I7 (M6) 3.4 0.0105 9.8 0.141 7.8 0.065 7.4 0.047 8.2 0.084 7.0 0.074 

I7a -- -- 0.2 0.003 0.5 0.004 0.5 0.003 -- -- -- -- 

I7b -- -- 0.3 0.004 -- -- -- -- -- -- -- -- 

I7c -- -- -- -- -- -- -- -- -- -- -- -- I8 1.2 0.0037 1.9 0.027 1.0 0.008 1.2 0.007 1.2 0.012 0.6 0.006 

I9 (M4) 25.6 0.0779 39.2 0.562 13.7 0.114 22.8 0.145 30.5 0.311 31.0 0.326 

I10 0.4 0.0011 -- -- -- -- -- -- -- -- -- -- 

I11 (M8) 1.5 0.0045 1.2 0.018 1.6 0.014 3.5 0.022 1.4 0.014 1.7 0.018 

I11a -- -- -- -- -- -- -- -- -- -- -- -- 

I13 0.5 0.0016 0.3 0.004 -- -- -- -- -- -- -- -- 

I14 (M11) 0.9 0.0027 0.2 0.003 0.1 0.001 0.2 0.001 -- -- -- -- 
Radiolabel Position

(Study No.)

Pyrazol

(99PSA55)

Phenyl

(00PSA58)

Phenyl

(01JS35)

Oxadiazepine

(01JS35)

Phenyl

(01MK16)

Oxadiazepine

(01MK16)

Growth Stage at Application

(Application Rate)

BBCH 13

(68.5 g a.i./ha)

BBCH 49

(64 g a.i./ha)

BBCH 21

(60 g a.i./ha)

BBCH 21

(58.1 g a.i./ha)

BBCH 37-39

(62 g a.i./ha)

BBCH 37-39

(66 g a.i./ha)

PHI 14 days 14 days 14 days 14 days 14 days 14 days 

Metabolite Fraction Whole tops

TRR = 0.304

ppm

Whole tops

TRR = 1.434

ppm

Whole tops

TRR =0.834 ppm

Whole tops

TRR =0.635 ppm

Whole tops

TRR =1.021 ppm

Whole tops

TRR = 1.051ppm

%TRR ppm %TRR ppm %TRR ppm %TRR ppm %TRR ppm %TRR ppm 

103

I14a -- -- -- -- -- -- -- -- 2.4 0.025 0.6 0.006 

I15 (M2) 5.4 0.0165 1.4 0.020 -- -- -- -- 0.8 0.008 0.8 0.008 

I15a (M10) -- -- 0.6 0.009 0.2 0.002 0.5 0.003 -- -- -- -- 

I15d -- -- -- -- -- -- -- -- -- -- -- -- 

I16 (M1; pinoxaden) 4.0 0.0123 0.4 0.006 -- -- -- -- 0.4 0.004 0.7 0.007 

I17 (M3) 5.7 0.0173 1.2 0.017 0.9 0.007 1.7 0.011 1.7 0.017 0.8 0.008 I18 1.0 0.0032 0.2 0.003 -- -- -- -- -- -- -- -- 

I19 3.2 0.0099 0.7 0.010 -- -- -- -- -- -- -- -- 

Unresolved 12.0 0.0366 7.7 0.111 10.4 0.087 17.1 0.109 1.3 0.013 4.7 0.049 

Non-extractable 11.1 0.0337 6.0 0.086 5.7 0.048 4.8 0.030 5.9 0.061 5.3 0.055 Total extractable 94.4 Not

given

99.6 Not

given

91.8 Not

given

98.2 Not

given

95.3 Not

given

93.0 Not

given

Total identified 70.6 0.2151 85.2 1.225 77.6 0.648 75.9 0.482 86.9 0.887 84.8 0.891 Total characterized 11.5 0.0354 6.5 0.093 3.8 0.030 5.3 0.032 7.0 0.071 3.8 0.039 Total bound 11.1 0.0337 6.0 0.086 5.7 0.048 4.8 0.030 5.9 0.061 5.3 0.055 Accountability(extractable + bound)

105.5 % 105.6 % 97.5 % 103.0 % 101.2 % 98.3 % 

Value = predominant metabolites* In Study No. 01MK16, there was two extraction steps for all samples (except 0-DAT and 7-DAT forage samples): extraction with 80% acetonitrile 80% 1-propanol [phenyl: 86.6 + 8.7 = 95.3 and oxadiazepine: 85.7 + 7.3 = 93.0]
104

Table A-3.2.3: Summary of Distribution of the Parent and the Metabolites in Wheat Forage, Tops & Ears w

Pinoxaden Following Different Treatment Regimes.

Radiolabel Position

(Study No.)

Pyrazol

(99PSA55)

Pyrazol

(99PSA55)

Phenyl

(00PSA58)

Oxadiazepine

(01MK16)

Phenyl

(00PSA58)

Growth Stage at Application

(Application Rate)

BBCH 13

(68.5 g a.i./ha)

BBCH 13

(68.5 g a.i./ha)

BBCH 49

(64 g a.i./ha)

BBCH 37-39

(66 g a.i./ha)

BBCH 49

(64 g a.i./ha)

PHI 42 days 209 days 28 days 28 days 28 days 

Metabolite Fraction Whole tops

TRR = 0.109 ppm

Whole tops

TRR = 0.011 ppm

Tops

TRR = 2.396 ppm

Tops

TRR = 1.211 ppm

Ears

TRR = 0.743 ppm

%TRR ppm %TRR ppm %TRR ppm %TRR ppm %TRR ppm 

Extractable with 80%

Acetonitrile

93.8 Not

given

81.7 Not

given

89.3 Not

given

97.3* Not

given

95.9 Not

given

I1 5.4 0.0059 1.9 0.0002 3.4 0.081 5.0 0.061 4.8 0.035 

I2 (M7) 9.8 0.0107 -- -- 3.9 0.094 5.0 0.061 -- -- 

I2a -- -- -- -- 0.6 0.014 -- -- 0.6 0.005 

I3 (M5) 30.2 0.0330 -- -- 56.3 1.349 64.4 0.780 19.2 0.143 

I4 (M9) 15.1 0.0165 7.6 0.0008 0.5 0.012 2.4 0.029 0.4 0.003 

I4a (M14) -- -- -- -- -- -- 0.8 0.010 1.3 0.009 

I5 1.1 0.0012 -- -- 2.0 0.049 1.4 0.017 4.4 0.033 

I6 1.3 0.0014 1.4 0.0001 -- -- -- -- -- -- 

I7 (M6) 4.5 0.0049 -- -- 8.4 0.201 7.4 0.090 6.4 0.048 

I7a -- -- -- -- 0.4 0.009 -- -- -- -- 

I7b -- -- -- -- 0.5 0.011 -- -- 1.2 0.009 I8 1.1 0.0012 -- -- 1.4 0.035 -- -- 4.3 0.032 

I8a -- -- -- -- -- -- -- -- -- -- 

I9 (M4) 9.3 0.0101 1.4 0.0002 7.3 0.176 5.6 0.068 42.7 0.317 

I10 1.1 0.0012 2.1 0.0002 -- -- -- -- -- -- 

I11 (M8) 3.3 0.0036 10.8 0.0012 1.1 0.027 2.4 0.029 1.0 0.007 

I12 0.8 0.0008 1.8 0.0002 -- -- -- -- -- -- 

I13 0.4 0.0005 3.5 0.0004 0.1 0.003 -- -- -- -- I14 (M11) 0.5 0.0005 2.7 0.0003 -- -- -- -- -- -- 

I14a -- -- -- -- -- -- 0.6 0.007 -- -- 
Radiolabel Position

(Study No.)

Pyrazol

(99PSA55)

Pyrazol

(99PSA55)

Phenyl

(00PSA58)

Oxadiazepine

(01MK16)

Phenyl

(00PSA58)

Growth Stage at Application

(Application Rate)

BBCH 13

(68.5 g a.i./ha)

BBCH 13

(68.5 g a.i./ha)

BBCH 49

(64 g a.i./ha)

BBCH 37-39

(66 g a.i./ha)

BBCH 49

(64 g a.i./ha)

PHI 42 days 209 days 28 days 28 days 28 days 

Metabolite Fraction Whole tops

TRR = 0.109 ppm

Whole tops

TRR = 0.011 ppm

Tops

TRR = 2.396 ppm

Tops

TRR = 1.211 ppm

Ears

TRR = 0.743 ppm

%TRR ppm %TRR ppm %TRR ppm %TRR ppm %TRR ppm 

105

I15 (M2) 1.4 0.0015 -- -- -- -- -- - -- -- 

I15a (M10) -- -- 8.9 0.0010 0.4 0.010 -- -- 1.3 0.010 

I15b -- -- -- -- -- -- 0.6 0.007 -- -- 

I15c (M32) -- -- 2.9 0.0003 -- -- -- -- -- -- 

I15d -- -- -- -- -- -- -- -- -- -- 

I16 (M1; pinoxaden) -- -- -- -- -- -- -- -- -- -- 

I17 (M3) 3.0 0.0033 19.2 0.0021 0.2 0.005 0.7 0.008 -- -- I18 -- -- 2.7 0.0003 -- -- -- -- -- -- 

Unresolved 5.5 0.0060 14.9 0.0016 2.7 0.064 1.2 0.015 8.3 0.061 Non-extractable 12.8 0.0140 22.5 0.0025 7.1 0.170 5.2 0.063 8.8 0.065 

Total extractable 93.8 -- 81.7 -- 89.3 -- 97.3 -- 95.9 -- 

Total identified 77.1 0.0841 53.5 0.0059 78.1 1.874 88.7 1.075 72.3 0.537 

Total characterized 11.2 0.0122 13.4 0.0014 8.4 0.202 7.6 0.092 15.3 0.114 

Total bound 12.8 0.0140 22.5 0.0025 7.1 0.170 5.2 0.063 8.8 0.065 Accountability(extractable + bound)

106.6 % 104.2 % 96.4 % 102.5 % 104.7 % 

Value = predominant metabolites* In Study No. 01MK16, there was two extraction steps for all samples (except 0-DAT and 7-DAT forage samples): extraction with 80% acetonitrile 

80% 1-propanol [tops: 92.2 + 5.1 = 97.3 and ears: 86.6 + 9.6 = 96.2]
106

Table A.3.2.4: Summary of Distribution of the Parent and the Metabolites in Mature Wheat Grain when Dosed wFollowing Different Treatment Regimes.

Radiolabel Position

(Study No.)

Phenyl

(00PSA58)

Phenyl

(00PSA58)

Pyrazol

(99PSA55)

Phenyl

(01MK16)

Oxadia

(01M

Growth Stage at Application

(Application Rate)

BBCH 49

(64 g a.i./ha)

BBCH 49

(318 g a.i./ha)

BBCH 41

(Stem injection)

BBCH 37-39

(62 g a.i./ha)

BBCH 

(66 g a

PHI 55 days 55 days 56 days 67 days 67 d

Metabolite Fraction Grain

TRR = 0.246 ppm

Grain

TRR = 0.845 ppm

Grain

TRR = 1.520 ppm

Grain

TRR = 0.142 ppm

Gr

TRR = 0

%TRR ppm %TRR ppm %TRR ppm %TRR ppm %TRR 

Extractable with 80%Acetonitrile

59.8 Not

given

76.5 Not

given

72.9 Not

given

78.1* Not

given

79.1* 

I1 6.2 0.015 11.8 0.100 26.8 0.407 25.8 0.037 34.5 

I2 (M7) 4.3 0.011 10.5 0.089 21.8 0.331 3.6 0.005 6.7 

I3 (M5) 5.1 0.013 8.8 0.074 6.6 0.100 15.7 0.022 13.3 

I5 1.2 0.003 -- -- -- -- -- -- -- 

I7 (M6) 9.6 0.024 13.2 0.111 12.3 0.187 12.0 0.017 13.6 

I9 (M4) 19.7 0.048 18.2 0.154 1.7 0.026 9.4 0.013 7.7 

I11 (M8) -- -- 1.4 0.012 -- -- -- -- -- 

I14a -- -- -- -- -- -- 1.9 0.003 1.1 

I15a (M10) 0.7 0.002 0.7 0.006 -- -- -- -- -- 

I16 (M1;

pinoxaden)

-- -- -- -- -- -- -- -- -- 

Unresolved 13.0 0.032 12.0 0.101 3.7 0.057 9.7 0.014 2.1 Non-extractable 45.9 0.113 19.4 0.164 37.5 0.570 21.8 0.031 18.7 Total extractable 59.8 Not

given

76.5 Not

given

72.9 Not

given

78.1 Not

given

79.1 

Total identified 39.4 0.098 52.8 0.446 42.4 0.644 40.7 0.057 41.3 Total characterized 7.4 0.018 11.8 0.100 26.8 0.407 27.7 0.040 35.6 Total bound 45.9 0.113 19.4 0.164 37.5 0.570 21.8 0.031 18.7 
Radiolabel Position

(Study No.)

Phenyl

(00PSA58)

Phenyl

(00PSA58)

Pyrazol

(99PSA55)

Phenyl

(01MK16)

Oxadia

(01M

Growth Stage at Application

(Application Rate)

BBCH 49

(64 g a.i./ha)

BBCH 49

(318 g a.i./ha)

BBCH 41

(Stem injection)

BBCH 37-39

(62 g a.i./ha)

BBCH 

(66 g a

PHI 55 days 55 days 56 days 67 days 67 d

Metabolite Fraction Grain

TRR = 0.246 ppm

Grain

TRR = 0.845 ppm

Grain

TRR = 1.520 ppm

Grain

TRR = 0.142 ppm

Gr

TRR = 0

%TRR ppm %TRR ppm %TRR ppm %TRR ppm %TRR 

107

Accountability(extractable + bound)

105.7 % 95.9 % 110.4 % 99.9 % 97.8 

Value = predominant metabolites* In Study No. 01MK16, there was two extraction steps for all samples (except 0-DAT and 7-DAT forage samples): extraction with 80% acetonitrile 

80% 1-propanol [phenyl: 27.5 + 50.6 = 78.1 and oxadiazepine: 48.1 + 31.0 = 79.1]

A-3.3 Nature of the Residue in Livestock Ruminant Metabolism Study: Two livestock metabolism studies were performed to elucidate the fate and distribuand its metabolites in lactating goats. The first study (Study No. 046AM04, MRID No. 46203129) was carried omolecule (pinoxaden; Pinoxaden) radiolabelled in the phenyl ring. The second study (Study No. 751-02, MRID carried out with the metabolite M4 (SYN 505164), radiolabelled in the pyrazolo[1,2-d] [1,4,5] oxadiazepine ring

metabolism studies, M4 was identified as a predominant metabolite in all wheat matrices (forage, ears, grain, straHowever, M4 was not found to be a unique plant metabolite as it was also observed in animal matrices (goat, hen In Study No. 046AM04, two lactating goats were administered 120.6 ppm in their diet of [phenyl-1-14C] pinoxad

Pinoxaden or M1) for four consecutive days. The majority of the AD was eliminated over the course of the stud82.62% AD in excreta (feces, urine, gastrointestinal tract and rumen). Only minor fractions of the total administtransferred to milk (0.009% AD) and edible tissues (0.260% AD). The highest concentrations of 14C-residues we

(2.953 ppm) and liver (1.160 ppm). The predominant metabolite detected in all the goat matrices was M2, which product of the parent molecule pinoxaden. Multiple minor metabolites (M3, M4, M6, M22, M12, M13, M20, MM27 and M28), each representing less than 10% of the TRRs, were detected in feces, as well as in some tissues apinoxaden was not detected in any of the matrices studied, indicating its rapid and complete metabolism in the laIn Study No. 751-02, two lactating goats received four consecutive daily administrations of 10 ppm in their diet known as SYN 505164). At the time of sacrifice, the majority of the administered dose (AD) had been eliminatein excreta (feces, urine, gastrointestinal tract and rumen). Residues in milk, muscle, fat and blood were below th
108

milk and 0.011 ppm in tissues). Only minor fractions of the total administered dose were transferred to the rema%AD). The highest concentrations of 14C-residues in goat tissues were detected in liver and kidney (0.025 ppm respectively). The major metabolite, identified in all tissues containing detectable residues, was unchanged M4. metabolite identified was M10 (SYN 505887) which is the hydroxylation product of M4. M10 represented only the TRRs in liver and kidney and represented less than 10% of excreted TRRs in feces.Overall, it can be concluded that pinoxaden is rapidly metabolized in all lactating goat matrices. Transfer of radiedible tissues and milk is minimal. In goats administered the predominant plant metabolite M4, transfer of total to milk and edible tissues was also very low. The highest concentrations of total radioactive residues in both stuand kidney, which is to be expected considering the rapid metabolism and excretion of pinoxaden and its metabothese results indicate that residues of pinoxaden and a major plant metabolite M4 (and by inference all metabolitstructure), have a very low transfer into the edible tissues and milk of lactating goats.[Phenyl-14C] pinoxaden was rapidly and completely metabolized in all goat matrices. The parent metabolite was 

milk, feces, urine or any of the tissues analyzed. The predominant metabolite identified in all goat matrices was by the hydrolysis of the ester moiety on the parent molecule. In the [7-14C] M4 metabolism study, the predomina

identified in all goat matrices was unchanged M4. Hydroxylation of M4 to M10 did occur in all matrices characrepresented only a minor fraction (< 10%) of the TRRs. Of note, the metabolite M10 was not detected in any of administered [phenyl-14C] pinoxaden.
109

Table A-3.3.1: Summary of Distribution of the Parent and the Metabolites in Goat Matrices when Dosed with 

 [Phenyl-1-14C] Pinoxaden at 120.6 ppm in feed.

Metabolite Fraction Milk Muscle Fat Liver Kidney Feces Urine

%TRR ppm %TRR ppm %TRR ppm %TRR ppm %TRR ppm %TRR %TRR

Extractable with ACN and ACN:H2O (8:2, v:v)

Total Residues 98.4 n.p. 95.7 n.p. 92.8 n.p. 97 n.p. 99.2 n.p. 98.6 N/A

C-18 Solid Phase Extraction (SPE) Clean-up

Eluate 1 0.21 n.p. 0.24 n.p. 89 n.p.

Eluate 2 98 n.p. 95.5 n.p. 3.96 n.p. N/A - N/A - N/A N/A

Eluate 3 0.23 n.p. N/A - N/A -

Chromatography (HPLC)

Pinoxaden

(M1, NOA 407855)

---------- - -

M2 (NOA 407854) 87.8 0 89.8 0.1 78.6 0 85.9 1 90.4 2.67 90 94.9

M3 (NOA 447204) 0.4 0 - - - - - - 2.3 0.1 1.1 -

M4 1.7 0 0.7 0 1.1 0 1.6 0 0.5 0 2.5 0.5

M6 + M22 - - - - - - - - - - 0.9 -

M12 6.2 0 4.4 0 8.5 0 6.9 0.1 4.2 0.12 - 3.9

M13 + M207 - - - - - - - - 0.3 0 0.9 -

M19 + M23 - - - - - - - - - - 0.6 -

M24 + M26 + M28 - - - - - - - - - - 0.7 -

M27 - - - - - - - - - - 0.4 -

Total identified 96 0 94.9 0.1 88.2 0 94.4 1.1 97.7 2.89 97.2 99.3

Unidentified 2 0 0.6 0 0.7 0 2.6 0 1.5 0 1.4 0.8

Unresolved 0.4 0 0.2 0 3.9 0 - - - - - -

Total extractable 98.4 n.p. 95.7 n.p. 92.8 n.p. 97 n.p. 99.2 n.p. 98.6 N/A

Unextractable (PES)8 1.6 0 4.3 0 7.2 0 3 0 0.8 0 1.4 N/A

Accountability9 100% 100% 100% 100% 100% 100% N/A

N/A - not applicable

n.p. - not provided

“-“ - not detected

1

 Elution with H2O 2

 Elution with H2O:MeOH (5:5, v:v), followed by MeOH 3

 Elution with MeOH

4

 Elution with H2O, H2O:MeOH (70:30, v:v) and MeOH 5 Elution with H2O and H2O:MeOH (50:50, v:v) 6

 Elution with ACN and MeOH

7

 only M13 in kidney

8 Residues remaining after exhaustive extractions.

9 Accountability = (Total extractable + Total unextractable)/(TRRs from combustion analysis; see TABLE C.2.1) * 100.
110

Table A-3.3.2: Summary of Distribution of the Parent and the Metabolites in Goat Matrices when Dosed

with [7-14C-] SYN 505164 at 10 ppm in feed1

.

Metabolite Fraction Urine2

Goat #1012

Urine2

Goat #1013

Feces Kidney Liver

%TRR ppm %TRR ppm %TRR ppm %TRR ppm %TRR ppm

Acetonitrile (ACN):Water (8:2, v:v) Extraction

 Extractable Residues N/A N/A 103.43 13.748 91.6 0.04 87.9 0.022

C18 SPE clean-up

 ACN:H2O eluate N/A N/A N/A 89.3 0.039 93.1 0.023

HPLC applied 100 1.438 100 0.789 103.43 13.748 89.3 0.039 93.1 0.023

 SYN 505164 96.6 1.389 97.7 0.771 90.1 11.975 72.6 0.032 54.1 0.014

 SYN 505887 - - - - 3.5 0.467 - - - -

 Unidentified / Unknown 3.4 0.049 2.3 0.018 9.8 1.306 16.7 0.01 39 0.01

2d-TLC applied N/A N/A N/A 72.6 0.032 54.1 0.014

 SYN 505164 N/A N/A N/A 55 0.024 40.8 0.01

 SYN 505887 N/A N/A N/A 9.1 0 8.1 0

 Unidentified/Unknown N/A N/A N/A 8.4 0 5.3 0

Total Identified 96.6 1.389 97.7 0.771 93.6 n.p. 64.1 n.p. 48.9 n.p.

Unidentified 3.4 0.049 2.3 0.018 9.8 1.306 25.15 n.p. 44.35 n.p.

Total Extractable N/A - N/A - 103.43 13.748 91.6 0.04 87.9 0.022

Unextractable (PES)3 N/A - N/A - 0.26 0.034 1.5 <0.0015 6.5 0

Accountability4 100.0% 100.0% 103.7% 94.3% 96.0%

N/A - not applicable

n.p. - not provided

“-“ - not detected

1

 Milk and Fat were not extracted as the TRRs in these tissues were < LOQ (< 0.002 ppm in milk and < 0.011 ppm in tissues) 2

 48-72 hour fraction

3

Residues remaining after exhaustive extractions.

4 Accountability = (Total extractable + Total unextractable)/(TRRs from combustion analysis)* 100. 5

Unidentified residues in kidney and liver show in chromatograms as multiple peaks with low concentrations (in kidney, <5% of

the TRRs each peak and in liver, the highest peak at ~13.5% of the TRRs (0.003 ppm)).

Poultry Metabolism Study: A group of five laying hens received four consecutive daily

administrations of 12.5 mg [phenyl-1-14C] pinoxaden (NOA 407855, M1), equivalent to 96.7

ppm in their diet. The majority of the administered dose (70.89%) had been excreted by the time

of sacrifice. Only minor fractions of the total administered dose were transferred to eggs

(0.007%) and edible tissues (0.158%). The highest concentration of 14C-residues in tissues were

detected in kidney (1.782 ppm) and liver (0.617 ppm). The predominant metabolites detected

were M2 (NOA 407854), M4 (SYN 505164) and M6 (SYN 502836). M2 is the hydrolysis

product of the parent pinoxaden, while M4 is formed by the hydroxylation at the 4-methyl group

of the phenyl moiety of M2. M6 is formed by the oxidation of M4 (via the intermediate reaction

product M31). Several minor metabolites, corresponding to less than10% of the TRRs (M3

(NOA 447204), M31, M33, M34 and M35) were detected in excreta, eggs and some tissues. 

Unchanged parent pinoxaden was not detected in any of the hen matrices studied.

At the time of sacrifice, 70.89% of the administered dose (AD) had been excreted. An additional

10.05% AD was recovered in the gizzard. Egg and tissue residues accounted for only 0.007%
111

AD and 0.1587% AD, respectively. The highest concentration of residues (expressed as pinoxaden equivalents) and kidney (1.782 ppm and 0.617 ppm, respectively).The predominant reaction step in the proposed metabolic pathway for the metabolism of pinoxaden in laying hen the ester moiety of the parent molecule to yield the metabolite M2. Hydroxylation of M2, at the 4-methyl group leads to the formation of M4, which is further oxidized via the intermediate reaction product M31 to yield M6. Tidentified metabolites (M3, M33, M34 and M35) constitute only minor fractions of the TRRs (<10%).

Table A-3.3.3: Summary of Distribution of the Parent and the Metabolites in Hen Matrices when Dosed with [Phenyl-1-14C] Pin

ppm in their diet.

Metabolite Fraction Excreta Egg White Egg Yolk Lean Meat Fat and Skin 

%TRR % TRR ppm % TRR ppm % TRR ppm % TRR ppm 

ExtractionFraction 1 94.41 92.53 n.p. 60.13 n.p. 90.21 n.p. 85.53 n.p. Fraction 2 3.22 2.62 n.p. 7.12 n.p. 2.82 n.p. 7.02 n.p. Exhaustive Extraction of Solidsn-hexane

N/A N/A -

0.3 n.p.

N/A - N/A - 

MeOH : H2O : HCOOH (50 : 50 : 0.1) 1.2 n.p.

1 N HCl 11.7 n.p.Liquid - Liquid Partitionn-hexane phase N/A N/A - 2.3 n.p. N/A - 0.3 n.p. 

H2O phase 57.8 n.p. 85.2 n.p. 

RP18 Solid Phase ExtractionEluate 1

N/A N/A - 0.05 n.p. 0.05 n.p. N/A - 

Eluate 2 57.86 n.p. 90.26 n.p. Chromatography (HPLC)Pinoxaden(parent, M1)

---------

M2 (NOA 407854) 18.5 45.5 0.0059 1.7 0.0005 17 0.0102 8.6 0.0099 M3 (NOA 447204) 0.2 --------
112

M4 (SYN 505164) 43.2 27.3 0.0035 23.7 0.0073 44.3 0.0266 30.2 0.035 M6 (SYN 502836) 13.5 - - 13 0.004 13.9 0.0083 22.4 0.026 M31 1.8 - - - - - - 1.3 0.0015 M33 4.3 7 0.0009 3.7 0.0011 7.2 0.0043 8.6 0.0099 M34 3.1 1.1 0.0001 3.5 0.0011 3.8 0.0023 3.2 0.0037 M35 1.5 1.5 0.0002 1.7 0.0005 - - 2.7 0.0031 Unidentified 8.2 10.1 0.0013 10.4 0.0032 4 0.0024 8.4 0.0097 Total identified 86.2 82.4 0.0107 47.4 0.0147 86.2 0.0517 76.8 0.0891 Total characterized 8.2 10.1 0.0013 10.4 0.0032 4 0.0024 8.4 0.0097 Total extractable 97.6 95.1 n.p. 80.4 n.p. 93 n.p. 92.5 n.p. Unextractable (PES)8 2.4 4.9 0.0006 19.6 n.p. 6.9 0.0041 7.5 0.0087 

Accountability9 100% 100% 100% 99.9% 100% 

1Extracted with ACN, ACN : H2O (8 : 2) and MeOH : H2O (8 : 2)2Extracted with MeOH : H2O (8 : 2)3Extracted with ACN and ACN : H2O (8 : 2)4Extracted with MeOH and MeOH : H2O (8 : 2)5Eluted with 0.1% HCOOH, 0.1% HCOOH : MeOH (9 : 1), 0.1% HCOOH : MeOH (8: 2), 0.1% HCOOH : MeOH(5 : 5)6Eluted with MeOH7Eluted with 0.1% HCOOH8Residues remaining after exhaustive extractions9Accountability = (Total extractable + Total unextractable)/(TRRs from combustion analysis; see TABLE C.2.1) * 100“-“ - not detectedn.p. - not providedN/A - not applicable
113

A-3.4 Confined Rotational Crop Study

In order to determine the nature and the amount of pinoxaden (8-(2,6-diethyl-p-tolyl)-1,2,4,5-

tetrahydro-7-oxo-7H-pyrazolo[1,2-d][1,4,5]oxadiazepin-9-yl 2,2-dimethyl-propionate; also

referred to as NOA 407855 or M1) residue uptake in rotational crops, three confined crop

rotation trial studies were performed. The different studies were carried out with 14C-pinoxaden

radiolabelled either in the phenyl or the oxadiazepine ring. Depending on the study design,

diverse rotational crops were used: mustard leaves, lettuce, radish, turnip, spring or winter

wheat; and various plant-back intervals (PBIs) were tested: 15 days, 30 days, 120 days, 170

days, and 365 days. With the exception of the soil types (clay loams were used instead of the

requisite sandy loam) the three confined rotational crop studies are considered scientifically

acceptable. TRRs accumulated at levels greater than 0.01 ppm in mustard leaves, turnip tops,

wheat forage and wheat fodder planted 15 DAT with either [phenyl-1-14C]pinoxaden or

[oxadiazepin-3,6-14C1]pinoxaden applied outdoors to bare ground (silty clay loam) at a total rate

of 70 g a.i./ha (0.062 lb a.i./A). TRRs also exceeded 0.01 ppm in lettuce, radish tops, wheat

forage and wheat fodder planted 29-30 days after treatment and in wheat fodder planted 120 days

after treatment with either [phenyl-1-14C]pinoxaden (at a total rate of 60.3 g a.i./ha or 0.054 lb

a.i./A) or [oxadiazepin-3,6-14C1]pinoxaden (at a total rate of 65.5 g a.i./ha or 0.058 lb a.i./A).

At the 29-30 DAT PBI, none of the metabolites identified (M2, M3, M8, M9, M10, M11 &

M32) were quantitated at levels greater that 0.01 ppm, except M3 in spring wheat forage (0.024

ppm; oxadiazepine radiolabel study only). Wheat forage is considered a feed item.

At the 15 DAT PBI, none of the metabolites identified [M3, M8, M10, conjugates of M10 (ME2,

ME3 and ME5) & M11] were quantitated at levels greater that 0.01 ppm, except M3, M10 &

M11 in spring wheat fodder (both radiolabels). Wheat fodder is considered a feed item.

Pinoxaden was not detected in any rotated crop matrices at any PBIs (from 15 to 365 days). 

Throughout the three confined rotational crop studies, no substantive variation in the metabolic

degradation of pinoxaden was observed. Pinoxaden was hydrolyzed rapidly (disappeared by day

3) in soil yielding M2. M2 was further hydroxylated forming M3 the predominant metabolite

observed in soil. M3 could thus be taken up from the soil by the rotated crops.

Metabolism of pinoxaden in rotational crops occurred mainly by hydroxylation processes. Other

metabolic pathways consisted of oxidation and conjugation reaction. All the metabolites

identified retained the three-ring backbone intact thus indicating there was minimal cleavage of

the bonds that join the three rings.

The metabolic profile of 14C-pinoxaden in wheat (primary crop) was similar to the metabolic

profiles observed in the rotational studies for wheat, lettuce, mustard leaves, radish and turnip

(secondary crops).
114

Table A-3.4.1: Summary of Distribution of the Parent and the Metabolites in Rotational Lettuce, Radish and SMatrices when Dosed with [Phenyl-1-14C] Pinoxaden in Study No. 00PSA57.

Plant-back interval 30 DAT 30 DAT 30 DAT 30 DAT 

Harvest 84 DAT 84 DAT 84 DAT 141 DAT 

Metabolite Fraction Lettuce Heads

TRR = 0.011 ppm

Radish Tops

TRR = 0.014 ppm

Spring Wheat Forage

TRR = 0.024 ppm

Spring Wheat Fodder

TRR = 0.035 ppm

%TRR ppm %TRR ppm %TRR ppm %TRR ppm 

Extractable with 80% Acetonitrile 86.1 Not given 100.9 Not given 93.6 Not given 65.7 Not given 

I1 8.1 0.0009 6.9 0.0010 8.1 0.0019 6.7 0.0023 

I3 (M5) -- -- -- -- 2.7 0.0007 -- -- 

I4 (M9) 3.2 0.0003 11.5 0.0016 20.3 0.0049 3.9 0.0014 

I6 -- -- 4.0 0.0006 -- -- 3.6 0.003 

I7 (M6) -- -- 3.9 0.0005 -- -- -- -- 

I8 -- -- 4.4 0.0006 -- -- -- -- 

I9 (M4) 2.5 0.0003 2.5 0.0004 1.6 0.0004 1.5 0.0005 

I10 -- -- -- -- 3.0 0.0007 -- -- 

I11 (M8) 5.6 0.0006 20.6 0.0029 13.1 0.0031 3.3 0.0012 

I12 -- -- 3.5 0.0005 2.0 0.0005 -- -- 

I13 -- -- 4.1 0.0006 6.1 0.0015 2.1 0.0007 I13a 43.3 0.0048 -- -- -- -- -- -- 

I13b -- -- 3.6 0.0005 -- -- -- -- 

I14 (M11) -- -- 1.5 0.0002 -- -- 2.4 0.0008 

I14a -- -- 1.6 0.0002 -- -- -- -- 

I14b -- -- 1.3 0.0002 -- -- 0.8 0.0003 I15 (M2) 4.8 0.0005 -- -- -- -- -- -- 

I15a (M10) -- -- 1.5 0.0002 -- -- 5.8 0.002 

I15c (M32) -- -- 0.8 0.0001 -- -- 4.2 0.0015 I16 (M1) -- -- -- -- -- -- -- -- 

I17 (M3) 5.3 0.0006 6.3 0.0009 17.6 0.0042 9.0 0.0032 

I18 4.1 0.0004 1.8 0.0002 5.1 0.0012 4.1 0.0014 
Metabolite Fraction Lettuce Heads

TRR = 0.011 ppm

Radish Tops

TRR = 0.014 ppm

Spring Wheat Forage

TRR = 0.024 ppm

Spring Wheat Fodder

TRR = 0.035 ppm

%TRR ppm %TRR ppm %TRR ppm %TRR ppm 

115

Unresolved 9.3 0.001 21.0 0.0029 14.0 0.0034 18.3 0.0064 Non-extractable 17.1 0.0019 7.7 0.0011 14.4 0.0035 40.5 0.0142 Total identified 21.4 0.0023 48.6 0.0068 55.3 0.0133 30.1 0.0106 Total characterized 55.5 0.0061 31.2 0.0044 24.3 0.0058 17.3 0.006 Total extractable 86.1 Not given 100.9 Not given 93.6 Not given 65.7 Not given Total bound 17.1 0.0019 7.7 0.0011 14.4 0.0035 40.5 0.0142 Accountability(Extractable + Bound)

103.2 % 108.6 % 108.0 % 106.2 % 

Value = predominant metabolite

Table A-3.4.2: Distribution of the Parent and the Metabolites in Rotational Lettuce, Radish and Spring Wheat Dosed with [Oxadiazepin-3,6-14C] Pinoxaden in Study No. 01PSA59.

Plant-back interval 29 DAT 29 DAT 29 DAT 29 DAT 

Harvest 70 DAT 70 DAT 70 DAT 139 DAT 

Metabolite Fraction Lettuce Heads

TRR = 0.014 ppm

Radish Tops

TRR = 0.022 ppm

Spring Wheat Forage

TRR = 0.048 ppm

Spring Wheat Fodder

TRR = 0.077 ppm

%TRR ppm %TRR ppm %TRR ppm %TRR ppm 

Extractable with 80% Acetonitrile 99.1 Not given 97.7 Not given 91.8 Not given 63.8 Not given 

I1 4.4 0.0006 5.9 0.0013 6.3 0.003 9.9 0.0076 

I4 (M9) 2.5 0.0003 8.8 0.0019 8.0 0.0038 5.0 0.0038 

I6 -- -- 2.3 0.0005 0.6 0.0003 1.8 0.0014 

I7 (M6) -- -- 2.9 0.0006 -- -- -- -- 

I8 -- -- 2.3 0.0005 -- -- -- -- 

I9 (M4) 1.2 0.0002 2.2 0.0005 1.2 0.0006 1.4 0.0011 

I9a (M31) -- -- -- -- -- -- 2.1 0.0017 

I10 -- -- -- -- 0.9 0.0004 -- -- I11 (M8) 3.2 0.0005 25.6 0.0056 3.9 0.0019 5.2 0.004 
Metabolite Fraction Lettuce Heads

TRR = 0.014 ppm

Radish Tops

TRR = 0.022 ppm

Spring Wheat Forage

TRR = 0.048 ppm

Spring Wheat Fodder

TRR = 0.077 ppm

%TRR ppm %TRR ppm %TRR ppm %TRR ppm 

116

I12 -- -- 5.0 0.0011 1.4 0.0007 -- -- I13 -- -- 2.9 0.0014 3.4 0.0026 I13a 69.1 0.0097 -- -- -- -- -- -- 

I13b -- -- 2.5 0.0005 -- -- -- -- 

I14 (M11) -- -- 1.7 0.0004 -- -- 1.8 0.0014 

I14a -- -- 1.9 0.0004 -- -- -- -- 

I15 (M2) 4.1 0.0006 -- -- 1.2 0.0006 -- -- 

I15a (M10) -- -- 3.4 0.0008 -- -- 3.5 0.0027 

I15c (M32) -- -- 0.8 0.0002 -- -- 4.0 0.0031 I16 (M1) -- -- -- -- -- -- -- -- 

I17 (M3) 3.7 0.0005 7.3 0.0016 49.3 0.0237 9.9 0.0077 

I18 4.1 0.0006 2.0 0.0004 6.4 0.0031 5.0 0.0038 

Unresolved 6.8 0.001 23.2 0.0051 7.9 0.0038 10.8 0.0083 Non-extractable 6.0 0.0008 7.0 0.0015 8.7 0.0042 37.7 0.029 Total identified 14.7 0.0021 52.7 0.0116 63.6 0.0306 32.9 0.0255 Total characterized 77.6 0.0109 21.9 0.0047 20.4* 0.0098* 20.1 0.0154 Total extractable 99.1 Not given 97.7 Not given 91.8 Not given 63.8 Not given Total bound 6.0 0.0008 7.0 0.0015 8.7 0.0042 37.7 0.029 Accountability(Extractable + Bound)

105.1 % 104.7 % 100.5 % 101.5 % 

Value = predominant metabolite*Metabolite fraction I4a was quantitated in spring wheat forage at 1.9% TRR (0.9 ppb).

Table A-3.4.3: Distribution of the Parent and the Metabolites in Rotational Mustard Leaves, Turnip and Spring Whe

with [Phenyl-1-14C] Pinoxaden or [Oxadiazepin-3,6-14C] Pinoxaden in Study No. 174-01.

Radiolabel Phenyl Phenyl Phenyl Phenyl Phenyl Oxadiazepine 

Plant-back interval 15 DAT 15 DAT 15 DAT 15 DAT 15 DAT 15 DAT 
117

Harvest 61 DAP 89 DAP 26 DAP 50 DAP 89 DAP 26 DAP 

Metabolite Fraction Mustard

Leaves

TRR = 0.013 ppm

Turnip

Tops

TRR = 0.010 ppm

Spring Wheat

25% Mature

Forage

TRR = 0.022 ppm

Spring Wheat

50% Mature

Forage

TRR = 0.027 ppm

Spring Wheat

Fodder

TRR = 0.069 ppm

Spring Wheat

25% Mature

Forage

TRR = 0.023 ppm

%TRR ppm %TRR ppm %TRR ppm %TRR ppm %TRR ppm %TRR ppm 

Extractable with 90%Acetonitrile

83.1 0.011 81.4 0.008 91.1 0.020 80.3 0.022 65.7 0.045 82.4 0.019 

Aqueous Fraction 73.0 0.010 54.8 0.006 53.9 0.012 47.5 0.013 34.0 0.024 53.2 0.012 

M8 (I11) 45.7 0.006 54.8 0.006 23.7 0.005 30.6 0.008 -- -- 22.6 0.005 

ME2* 10.8 0.001 -- -- 5.7 0.001 6.9 0.002 -- -- 6.7 0.002 ME3* 2.8 <0.001 -- -- -- -- -- -- -- -- -- -- ME5* 13.6 0.002 -- -- 24.6 0.005 10.0 0.003 -- -- 23.9 0.006 

 ME7 [I14 (M11)] -- -- -- -- -- -- -- -- 34.0 0.024 -- -- 

Organic Fraction 21.1 0.003 20.4 0.002 28.9 0.006 26.3 0.007 27.2 0.019 25.4 0.006 

M3 (I17) 21.1 0.003 20.4 0.002 28.9 0.006 16.8 0.005 15.2 0.011 25.4 0.006 

M10 (I15a) -- -- -- -- -- -- 9.5 0.003 12.0 0.008 -- -- 

Unknown -- -- -- -- -- -- -- -- -- -- -- -- 

PES 9.8 0.001 13.1 0.001 14.6 0.003 21.4 0.006 32.8 0.023 15.0 0.004 

Refluxed withACN:Water (4:1) for 24 hrs.

Not applicable 9.9 0.007 Not appli

M6 (I7) 2.1 0.001 

M3 (I17) 1.7 0.001 

Non-extractable 24.8 0.017 Total identified 66.8 0.009 75.2 0.008 52.6 0.011 56.9 0.016 65.0 0.045 48.0 0.011 

Total characterized 27.2 0.004 -- -- 30.3 0.006 16.9 0.005 -- -- 30.6 0.008 Total extractable 83.1 0.011 81.4 0.008 91.1 0.020 80.3 0.022 75.6 0.052 82.4 0.019 

Total bound 9.8 0.001 13.1 0.001 14.6 0.003 21.4 0.006 24.8 0.017 15.0 0.004 

Accountability(Extractable + Bound)

92.9 % 94.5 % 105.7 % 101.7 % 100.4 % 97.4 % 
118

* Glucose-Conjugates of M10 (SYN-505887)A-3.5 Analytical MethodologyThree analytical methodologies (REM 199.02, REM 199.03 & 117-01) were proposed for the analysis of residue407855; as metabolite M2) and the metabolites M2 (NOA 407854), M4 (SYN 505164), M6 (SYN 502836) and MMethods REM 199.02 & 199.03 only) in cereal matrices. All three methods possessed the same extraction proceacid hydrolysis (1N HCl) by boiling under reflux for two hours, which is consistent with the methodology used dmetabolism studies. The analysis of the resulting extract was performed by reversed-phase high-performance liq(HPLC) using a column-switching system connected via a pneumatically and thermally assisted electrospray iontandem mass spectrometer (HPLC-MS/MS).All three methods have been shown to be highly specific to the target analytes through the use of tandem mass sp

(HPLC-MS/MS), therefore, neither a confirmatory method nor an interference study was required.Furthermore, based on the extraction efficiency data provided, both analytical methods REM 199.02 (or REM 19were successfully radio-validated in wheat matrices (grain, husk and straw) as they were capable of extracting bi

residues at levels in accordance with the expected amounts from the wheat metabolism study. Moreover, the meextract the four metabolites of interest (M2, M4, M6 & M10) and quantitate them within the expected ranges.Based on the submitted recovery data, on the ILV results and on the radio-validation results, analytical method 1quantitation of residues of M2, M4 and M6 is considered acceptable as the enforcement method in cereal matricemethod is validated by ACL.Method T001530-03 is proposed as both the data-gathering method and the enforcement method in livestock madetermination of the two major pinoxaden metabolites M4 and M6.The independent laboratory validation (ILV) of Method T001530-03 successfully demonstrated the reliability of analysis of residues of M4 and M6 in beef muscle, beef fat, milk and eggs on the first attempt. A scientifically a

was submitted by the registrant to waive the requirement of a radio-validation study for this method. Method T0considered acceptable as a data-gathering method for the determination of M4 and M6 in livestock matrices. Th

enforcement methodology for livestock is not currently adequate because it was not validated for residues of pin
119

Based on its similarities to the plant enforcement method, HED expects that the proposed

livestock method will be adequate for quantification of pinoxaden and M2. Submission of the

validation data for pinoxaden and M2 may thus be a condition of registration.
120

A-3.6 Summary of Magnitude of Residue (MOR) Studies

A-3.6.1 Plants

Table A-3.6.1.1: Summary of Residue Data from Crop Field Trials with Pinoxaden.

Commodity

(Country)

Total

Application

Rate

(g a.i./ha)

PHI

(days)

Residue Levels (ppm)

n Min. Max. HAFT* Median

(STMdR)

Mean

(STMR)

Std. Dev.

Combined Residues of pinoxaden, M2, M4 and M6

Barley Hay

(U.S.)

72.5

10 4 1.50 2.83 2.69 2.22 2.19 0.61

20 4 0.17 0.23 0.22 0.19 0.20 0.02

30 24 0.06 1.10 0.71 0.09 0.18 0.22

40 4 0.06 0.14 0.14 0.10 0.10 0.04

Barley Straw

(U.S.)

72.5

46 4 0.24 0.48 0.43 0.37 0.36 0.10

53 4 0.26 0.65 0.46 0.41 0.43 0.16

60 24 0.09 0.62 0.52 0.25 0.29 0.16

67 4 0.22 0.36 0.31 0.31 0.30 0.06

Barley Grain

(U.S.)

72.5

46 4 0.24 0.40 0.38 0.33 0.33 0.07

53 4 0.32 0.64 0.48 0.47 0.48 0.13

60 24 0.09 0.69 0.66 0.23 0.27 0.18

67 4 0.16 0.51 0.40 0.34 0.34 0.15

Barley Hay

(CDN)

70.0

15 1 0.589 0.589 -- -- --

22 2 0.13 0.17 0.17 0.15 0.15 --

26-36 30 0.06 0.77 0.74 0.17 0.24 0.20

42-49 23 0.06 0.12 0.12 0.08 0.08 0.02

Barley Straw

(CDN)

70.0

46 1 0.06 0.06 -- -- --

54-70 29 0.06 0.22 0.18 0.08 0.10 0.05

73-89 22 0.06 0.13 0.12 0.06 0.07 0.02

Barley Grain

(CDN)

70.0

46 1 0.03 0.03 -- -- --

54-70 29 0.03 0.16 0.15 0.06 0.07 0.04

73-89 22 0.03 0.07 0.07 0.04 0.04 0.01

*

 HAFT = Highest Average Field Trial.
121

Table A-3.6.1.2: Summary of Residue Data from Crop Field Trials with Pinoxaden.

Commodity

(Country)

Total

Application

Rate

(g a.i./ha)

PHI

(days)

Residue Levels (ppm)

n Min. Max. HAFT* Median

(STMdR)

Mean

(STMR)

Std. Dev.

Combined Residues of pinoxaden, M2, M4 and M6

Wheat Spring Forage

(U.S.)

72.5

10 6 0.96 3.58 2.84 1.16 1.66 1.03

20 6 0.14 0.85 0.83 0.68 0.56 0.33

30 42 0.06 0.95 0.94 0.14 0.24 0.22

40 6 0.07 0.20 0.18 0.08 0.11 0.06

Wheat Fall Forage

(U.S.)

72.5

10 2 2.53 3.46 3.00 -- 3.00 --

20 4 0.90 2.34 2.24 1.54 1.58 0.77

30 20 0.06 3.07 2.99 1.54 1.41 0.82

40 4 0.06 1.40 1.35 0.83 0.78 0.67

Wheat Hay

(U.S.)

72.5

10 4 2.24 3.56 3.33 2.86 2.88 0.58

20 6 0.14 2.64 2.44 1.65 1.43 1.06

30 42 0.06 1.71 1.31 0.28 0.49 0.43

40 6 0.09 0.51 0.47 0.15 0.24 0.18

Wheat Straw

(U.S.)

72.5

46 4 0.27 0.58 0.54 0.49 0.46 0.13

53 4 0.22 0.62 0.62 0.53 0.48 0.19

60 42 0.09 1.49 1.23 0.34 0.43 0.32

67 4 0.14 0.59 0.58 0.37 0.37 0.24

217.5 60 2 0.19 0.20 0.20 -- 0.20 --

362.5 60 2 0.91 0.98 0.95 -- 0.95 --

Wheat Grain

(U.S.)

72.5

46 4 0.14 0.77 0.52 0.24 0.35 0.30

53 4 0.23 0.53 0.38 0.36 0.37 0.13

60 42 0.05 0.72 0.61 0.18 0.22 0.15

67 4 0.45 0.65 0.55 0.49 0.52 0.09

217.5 60 2 0.07 0.08 0.08 -- 0.08 --

362.5 60 2 0.60 0.66 0.63 -- 0.63 --

Wheat Forage

(CDN)

70.0

4-5 12 1.57 3.02 2.86 2.28 2.25 0.48

6-8 31 0.66 3.75 3.21 1.50 1.53 0.60

10-17 7 0.13 0.54 0.39 0.24 0.25 0.14

22-25 6 0.06 0.27 0.27 0.08 0.11 0.08

29-31 2 0.06 0.14 0.14 0.10 0.10 --

Wheat Hay

(CDN)

70.0

22 1 0.87 0.87 -- -- --

28-36 34 0.06 0.92 0.78 0.12 0.17 0.18

37-49 20 0.06 0.14 0.14 0.09 0.09 0.02

50 5 0.06 0.08 -- 0.06 0.06 0.01

57 1 0.06 -- -- -- -- --
Commodity

(Country)

Total

Application

Rate

(g a.i./ha)

PHI

(days)

Residue Levels (ppm)

n Min. Max. HAFT* Median

(STMdR)

Mean

(STMR)

Std. Dev.

122

64 1 0.06 -- -- -- -- --

Wheat Straw

(CDN)

70.0

58-72 37 0.06 0.19 0.19 0.07 0.08 0.03

74-79 9 0.06 0.09 0.09 0.06 0.07 0.01

80-88 6 0.06 0.09 0.09 0.06 0.07 0.01

90-101 8 0.06 0.06 0.06 0.06 0.06 0

Wheat Grain

(CDN)

70.0

58-72 37 0.03 0.08 0.08 0.03 0.03 0.01

74-79 9 0.03 0.03 0.03 0.03 0.03 0

80-88 6 0.03 0.04 0.03 0.03 0.03 0

90-101 8 0.03 0.03 0.03 0.03 0.03 0

*

 HAFT = Highest Average Field Trial.

Table A-3.6.1.3: Summary of Residue Data from Barley Processing Study with

Pinoxaden.

RAC Processed

Commodity

Total Rate

(g a.i./ha)

PHI

(days)

Combined

Residues 

(M2 + M4 + M6)

(ppm)

Processing

Factor

Mean Processing

Factor

Barley Grain

Grain

70 60

0.28

0.42X for flour

0.99X for pearled

barley

(Due to the

discrepancy of the

two values in barley

bran, the

concentration factors

were not averaged.)

Flour 0.12 0.43X

Bran 0.68 2.43X

Pearled Barley 0.32 1.14X

Grain

365 60

1.66

Flour 0.67 0.40X

Bran 1.36 0.82X

Pearled Barley 1.4 0.84X
123

Table A-3.6.1.4: Summary of Residue Data from Wheat Processing Study with

Pinoxaden.

RAC Processed

Commodity

Total Rate

(g a.i./ha)

PHI

(days)

Combined

Residues 

(M2 + M4 + M6)

(ppm)

Processing

Factor

Mean Processing

Factor

Wheat Grain

Grain

70 60

0.449

0.2X for AGF

0.2X for flour

0.7X for middling

1X for shorts

0.7X for germ

(Due to the

discrepancy of the

two values in wheat

bran, the

concentration factors

were not averaged.)

AGF 0.068 0.15X

Bran 0.63 1.4X

Flour 0.089 0.2X

Middling 0.26 0.6X

Shorts 0.432 1X

Germ 0.273 0.6X

Grain

365 60

1.26

AGF 0.257 0.2X

Bran 5.81 4.6X

Flour 0.212 0.17X

Middling 0.875 0.7X

Shorts 1.26 1X

Germ 0.96 0.8X

A-3.6.2 Livestock 

Ruminants :M4 (also known as SYN 505164; 8-(2,6-diethyl-4-hydroxymethyl-phenyl)-

tetrahydro-pyrazolo [1,2-d][1,4,5]oxadiazepine-7,9-dione) was administered once daily in a

gelatin capsule via a balling gun to Holstein dairy cattle (Bos taurus) for 29 to 30 consecutive

days. In the wheat metabolism studies, M4 was identified as a predominant plant metabolite in

all wheat matrices following treatment with pinoxaden (NOA 407855). 

Nine cows were administered nominal daily doses of either 1 ppm, 3 ppm or 10 ppm of M4

throughout the study period. A fourth group consisting of a control cow and a back-up cow

received daily administrations of a placebo gelatin capsule. Animals were sacrificed 20 to 24

hours after the final dose.

Milk was collected twice daily and blood and tissue samples were collected at sacrifice. Liver,

kidney, muscle (round and tenderloin) and fat (omental and perirenal) samples were analyzed for
124

residues of M4 and M6 (also known as SYN 502836), using Method T001530-03. Briefly,

samples were refluxed with 1N HCl for two hours. An aliquot of the extract was subjected to

two sequential solid-phase extraction (SPE) clean-up steps (SCX(2) and C8 cartridges) and all

organic solvents were removed by evaporation. Samples were diluted to an appropriate volume

with 0.2% formic acid solution and an aliquot was injected directly onto a high performance

liquid chromatography - tandem mass spectrometry system (HPLC-MS/MS) for analysis. 

Concurrent recoveries for M4 and M6 were within the acceptable guideline range of 70% to

120%. The limit of quantitation (LOQ) for each analyte was reported as 0.01 ppm in milk and

0.02 ppm in tissues.

There were no quantifiable residues (< 0.02 ppm; combined LOQs) of M4 or M6 in milk

collected from animals treated at the highest dose (10 ppm), nor were any quantifiable residues 

(< 0.04 ppm; combined LOQs) of either metabolite detected in any of the tissues sampled. As

residue levels in samples taken from animals at the highest treatment dose were all below the

LOQ, no additional analysis of samples from the two lower treatment dose groups was done.

Samples were stored frozen for up to 71 days (-2.4 months) prior to analysis. A concurrent

freezer storage stability study demonstrated that residues of M4 and M6 were stable in animal

matrices that were stored frozen for up to 3 months. Therefore, there are no concerns with the

freezer storage stability of the residues throughout the duration of the feeding study.

The dairy cattle feeding study demonstrates that residues of M4 (measured as M4 and M6) were

not quantifiable in edible cow matrices when animals were administered M4 at doses up to 10

ppm in their diet.
125

Table A-3.6.2.1: Calculation of MTDBs of Pinoxaden to Livestock.

Feed Item % Diet1 Recommended

Tolerance

% Dry Matter % CT Theoretical

Contribution3

(ppm)

Beef Cattle2

Wheat Forage 25 3.5 25 100 3.5

MTDB 100 -- -- 100 3.5

Dairy Cattle2

Wheat Forage 60 3.5 25 100 8.4

MTDB 100 --- -- 100 8.4

Swine

Wheat Milled

Byproduct

50 3 88 100 1.5

MTDB 100 -- -- 100 1.5

Poultry

Wheat Milled

Byproduct

50 3 88 100 1.5

MTDB 100 – – 100 1.5

1. Table 1 (OPPTS Guideline 860.1000).

2. Wheat/barley hay and straw were not included since the diet should also include protein and carbohydrates. 

3. Contribution = [tolerance / % DM (cattle)] x % diet). Poultry and hog diets are not corrected for % dry matter.

Table A-3.6.2.2: Summary of Residue Data from Dairy Cattle Feeding Study with M4

(SYN 505164).

Matrix Feeding Level

Combined Residues of M4 and M6 (ppm)

n Min. Max. Median

(Stmdr)

Mean

(STMR)

Std.

Dev.

Milk 10 ppm 27 < 0.02 < 0.02 < 0.02 < 0.02 0

Liver 3 < 0.04 < 0.04 < 0.04 < 0.04 0

Kidney 3 < 0.04 < 0.04 < 0.04 < 0.04 0

Omental Fat 3 < 0.04 < 0.04 < 0.04 < 0.04 0

Perirenal Fat 3 < 0.04 < 0.04 < 0.04 < 0.04 0

Round Muscle 3 < 0.04 < 0.04 < 0.04 < 0.04 0

Tenderloin Muscle 3 < 0.04 < 0.04 < 0.04 < 0.04 0

Poultry: M4 (also known as SYN 505164; 8-(2,6-diethyl-4-hydroxymethyl-phenyl)-tetrahydropyrazolo [1,2-d][1,4,5]oxadiazepine-7,9-dione) was administered ad libitum to White Leghorn
126

hens (Gallus domesticus) in treated feed for 28 consecutive days. In the wheat metabolism

studies, M4 was identified as a predominant plant metabolite in all wheat matrices, following

treatment with pinoxaden (NOA 407855).

Groups of 15 hens were administered feed rations containing either 0 ppm (control), 0.5 ppm,

1.5 ppm or 5.0 ppm of M4 throughout the study period. Freshly treated feed was prepared

weekly and levels of feed were maintained to allow continuous feeding. Animals were sacrificed

within 20 to 24 hours of the removal of treated feed.

Eggs were collected daily and tissue samples were collected at sacrifice. Samples of skin with

attached fat, peritoneal fat, liver, breast muscle and thigh muscle were pooled within treatment

groups and analyzed for residues of M4 and M6 (also known as SYN 502836), using Method

T001530-03. Briefly, samples were refluxed with 1N HCl for two hours. An aliquot of extract

was subjected to two sequential solid-phase extraction (SPE) clean-up steps (SCX(2) and C8

cartridges) and all organic solvents were removed by evaporation. Samples were diluted to an

appropriate volume with 0.2% formic acid solution and an aliquot was injected directly onto a

high performance liquid chromatography - tandem mass spectrometry system (HPLC-MS/MS)

for analysis. Concurrent recoveries for M4 and M6 were within the acceptable guideline range

of 70% to 120%. The limit of quantitation (LOQ) for each analyte was 0.02 ppm in all matrices.

There were no quantifiable residues (< 0.04 ppm; combined LOQs) of M4 or M6 in eggs

collected from animals treated at the highest dose (5.0 ppm), nor were there any quantifiable

residues (< 0.04 ppm; combined LOQs) of either metabolite detected in any of the tissues

sampled from the same treatment group. As residue levels in samples taken from animals at the

highest treatment dose were all below the LOQ, no additional analysis of samples from the two

lower treatment dose groups was done.

Samples were stored frozen for up to 99 days (-3 months) prior to analysis. A concurrent

freezer storage stability study demonstrated that residues of M4 and M6 were stable in animal

matrices that were stored frozen for up to 3 months. Therefore, there are no concerns with the

freezer storage stability of the residues throughout the duration of the feeding study.

The laying hen feeding study demonstrated that residues of M4 and M6 were not quantifiable in

edible poultry matrices when animals were administered M4 at doses up to 5 ppm in their diet.

Table A-3.6.2.3: Summary of Residue Data from Laying Hen Feeding Study with M4

(SYN 505164).

Matrix Feeding Level Combined Residues of M4 and M6 (ppm)

n Min. Max. Median

(STMdR)

Mean

(STMR)

Std.

Dev.

Milk 5 ppm 30 < 0.04 < 0.04 < 0.04 < 0.04 0

Skin + Attached Fat 3 < 0.04 < 0.04 < 0.04 < 0.04 0

Liver 3 < 0.04 < 0.04 < 0.04 < 0.04 0
127

Peritoneal Fat 3 < 0.04 < 0.04 < 0.04 < 0.04 0

Breast + Thigh Muscle 3 < 0.04 < 0.04 < 0.04 < 0.04 0
128

Appendix 4. Dissenting Opinion of the Hazard Assessment

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C. 20460

OFFICE OF

PREVENTION, PESTICIDES AND

TOXIC SUBSTANCES

DATE: June 30, 2005

MEMORANDUM

SUBJECT: Pinoxaden: New Registration - Dissenting Opinion of the Hazard Assessment

FROM: William Greear, M.P.H., D.A.B.T., Toxicologist

Registration Action Branch 1 

Health Effects Division (7509C)

TO: Hope Johnson

PM

Registration Division (7505C)

DP Barcode: D310864, D311624. Petition No. PP# 4F6817

Chemical: Pinoxaden

PC Code: 147500

I have reviewed the latest draft of the hazard assessment concerned with the issue of

carcinogenicity, sent by Mary Clock-Rust on June 30, 2005. My conclusions are as follows:

There exits an adequate carcinogenicity study in one species, the rat. There exists no

adequate carcinogenicity study in a second species. HED’s Carcinogenicity Assessment Review

Committee (CARC) summarized the first study in mice, via gavage, in their final report:

“The CARC concluded that the gavage mouse carcinogenicity study was inadequate, not

interpretable, and not useful for risk assessment based on increased mortality at 40

mg/kg/day (40%), 300 mg/kg/day (41%) and 750 mg/kg/day (47%) in males, compared

to controls (16%).” 
129

The study was extremely flawed since mortality in male mice was not dose dependent. 

In addition, there was no comparable increase in mortality observed in female mice. In other

words, administration of pinoxaden at the highest dose level did not produce increased female

mortality when compared to controls. The non-dose dependent increase in mortality in males

simply can not be explained.

HED’s Carcinogenicity Assessment Review Committee (CARC) summarized the second

study in mice, via diet, in their final report: 

“At the doses tested, there were no treatment-related increases in tumor incidence when

compared to controls. Dosing was considered to be inadequate due to the lack of toxicity

in animals in the 1500 ppm group. [The testing laboratory terminated animals in 4000

ppm group (HDT) at week 40 due to what they considered to be excessive decreases in

body weight gain in males and females (31 and 33%, respectively).]”, and

“The subchronic study indicated that the animals could have tolerated higher doses. The

CARC concluded that the dose of 1500 ppm was not high enough to assess the

carcinogenicity of pinoxaden, and that the dose of 4000 ppm should have been

continued.”

 

The CARC’s overall assessment of the complete toxicology data base on pinoxaden

follows:

[In accordance with the EPA Draft Guidelines for Carcinogen Risk Assessment (July,

1999), the Committee classified Pinoxaden into the category “Data Are Inadequate for

An Assessment of Human Carcinogenic Potential”. ]

I am in complete agreement with the CARC’s weight-of-the evidence evaluation of the

potential carcinogenicity of pinoxaden. 

[It must also be emphasized this is a “new chemical” of a “new chemical” class of pesticides and 

that a cautious approach in regulating this new chemical is warranted. ]