Fluroxypyr-meptyl

Fluroxypyr-meptyl	Last updated: 26/05/2025
(Also known as: fluroxypyr-MHE)

SUMMARY

Data alerts

The following alerts are based on the data in the tables below. An absence of an alert does not imply the substance has no implications for human health, biodiversity or the environment but just that we do not have the data to form a judgement.

Environmental fate	Ecotoxicity	Human health
Environmental fate Moderate alert: Potential for particle bound transport: Medium	Ecotoxicity Moderate alert: Fish acute ecotoxicity: Moderate; Fish chronic ecotoxicity: Moderate; Daphnia acute ecotoxicity: Moderate; Daphnia chronic ecotoxicity: Moderate; Earthworms acute ecotoxicity: Moderate; Earthworms chronic ecotoxicity: Moderate	Human health High alert: Reproduction/development effects

GENERAL INFORMATION

Description

A post-emergence herbicide used to control economically important broadleaved weeds

Example pests controlled

Annual and perennial broadleaved weeds including kochia, lespedeza and dogfennel; Woody brush

Example applications

Rangeland; Permanent pasture; Non-crop areas; Cereals including wheat, corn

Efficacy & activity

Availability status

Current

Introduction & key dates

2004, first registration USA; 2011. evaluation EU

GB regulatory status

GB COPR regulatory status

Approved

Date COPR inclusion expires

31/12/2029

GB LERAP status

Check label - may vary with formulation

EC Regulation 1107/2009 (repealing 91/414)

EC Regulation 1107/2009 status

Approved

Dossier rapporteur/co-rapporteur

Sweden/Slovenia

Date EC 1107/2009 inclusion expires

15/02/2027

EU Candidate for substitution (CfS)

Listed in EU database

Yes

Approved for use (✓) under EC 1107/2009 in the following EU Member States

ATAustria	BEBelgium	BGBulgaria	CYCyprus	CZCzech Republic	DEGermany	DKDenmark	EEEstonia	ELGreece
✓	✓	✓	✓	✓	✓	✓	✓	✓
ESSpain	FIFinland	FRFrance	HRCroatia	HUHungary	IEIreland	ITItaly	LTLithuania	LULuxembourg
✓	✓	✓	✓	✓	✓		✓	✓
LVLatvia	MTMalta	NLNetherlands	PLPoland	PTPortugal	RORomania	SESweden	SISlovenia	SKSlovakia
✓	✓	✓	✓	✓	✓	✓	✓	✓

Approved for use (✓) under EC 1107/2009 by Mutual Recognition of Authorisation and/or national regulations in the following EEA countries

ISIceland	NONorway
	✓

Additional information

Also used in

Australia

Chemical structure

Isomerism

Fluroxypyr is not itself isomeric but the meptyl ester has a pair of enantiomers.

Chemical formula

C₁₅H₂₁Cl₂FN₂O₃

Canonical SMILES

CCCCCCC(C)OC(=O)COC1=NC(=C(C(=C1Cl)N)Cl)F

Isomeric SMILES

No data

International Chemical Identifier key (InChIKey)

OLZQTUCTGLHFTQ-UHFFFAOYSA-N

International Chemical Identifier (InChI)

InChI=1S/C15H21Cl2FN2O3/c1-3-4-5-6-7-9(2)23-10(21)8-22-15-12(17)13(19)11(16)14(18)20-15/h9H,3-8H2,1-2H3,(H2,19,20)

2D structure diagram/image available?

Yes

Cambridge Crystallographic Data Centre diagrams

Common Name	Relationship	Link
fluroxypyr	Parent

General status

Pesticide type

Herbicide

Substance groups

Pyridine herbicide

Minimum active substance purity

950 g kg⁻¹

Known relevant impurities

EU dossier - None declared

Substance origin

Synthetic

Mode of action

Selective, foliar uptake causing auxin-type response

CAS RN

81406-37-3

EC number

279-752-9

CIPAC number

431

US EPA chemical code

128968

PubChem CID

54745

CLP index number

607-272-00-5

Molecular mass

367.24

PIN (Preferred Identification Name)

rac-(2R)-octan-2-yl [(4-amino-3,5-dichloro-6-fluoropyridin-2-yl)oxy]acetate

IUPAC name

(RS)-1-methylheptyl 4-amino-3,5-dichloro-6-fluoro-2-pyridyloxyacetate

CAS name

1-methylheptyl ((4-amino-3,5-dichloro-6-fluoro-2-pyridinyl)oxy)acetate

Other status information

Relevant Environmental Water Quality Standards

Herbicide Resistance Class (HRAC MoA class)

Herbicide Resistance Class (WSSA MoA class)

Insecticide Resistance Class (IRAC MoA class)

Not applicable

Fungicide Resistance Class (FRAC MOA class)

Not applicable

Examples of recorded resistance

Cabbage family; other dicotyldons such as bugloss, comon poppy, corn marigold

Physical state

White crystalline solid

Related substances & organisms

fluroxypyr

Formulations

Property

Value

Example manufacturers & suppliers of products using this active now or historically

Barclay Chemicals
Dow AgroSciences
Agrotech
AgriGuard

Example products using this active

Agrostar
Bofix FFC
Awac
Cabadex
Cascade
Ariane S

Formulation and application details

Often supplied as an emulsifiable concentrate that is mixed with water and applied as a spray

ENVIRONMENTAL FATE

Property

Value

Source; quality score; and other information

Interpretation

Solubility - In water at 20 °C (mg l⁻¹)

0.136

Low

Solubility - In organic solvents at 20 °C (mg l⁻¹)

62300

n-Heptane

3770000

Methanol

3300000

Acetone

2500000

Ethyl acetate

Melting point (°C)

57.5

Boiling point (°C)

Decomposes before boiling

Degradation point (°C)

312

Flashpoint (°C)

Octanol-water partition coefficient at pH 7, 20 °C

1.10 X 10⁰⁵

Calculated

Log P

5.04

High

Fat solubility of residues

Solubility

Soluble

Data type

Regulatory data

Density (g ml⁻¹)

1.322

Dissociation constant pKa) at 25 °C

Not applicable

No dissociation

Vapour pressure at 20 °C (mPa)

0.01

Low volatility

Henry's law constant at 25 °C (Pa m³ mol⁻¹)

2.7 X 10^-02

Non-volatile

Volatilisation as max % of applied dose lost

From plant surface

From soil surface

Maximum UV-vis absorption L mol⁻¹ cm⁻¹

290nm=10.01, no maxama 290-900nm

Surface tension (mN m⁻¹)

Degradation

Property

Value

Source; quality score; and other information

Interpretation

General biodegradability

Soil degradation (days) (aerobic)

DT₅₀ (typical)

1.0

Non-persistent

DT₅₀ (lab at 20 °C)

1.0

Non-persistent

DT₅₀ (field)

Non-persistent

DT₉₀ (lab at 20 °C)

2.4

Non-persistent

DT₉₀ (field)

DT₅₀ modelling endpoint

Note

EU dossier lab studies DT₅₀ range 0.5-1.8 days (normalised); DT₉₀ range 1.0-6.0 days; Other studies: DT₅₀ 3-55 days (lab), 34-70 (field)

Dissipation rate RL₅₀ (days) on plant matrix

Value

Note

Dissipation rate RL₅₀ (days) on and in plant matrix

Value

2.69

Note

Rice, whole plant, n=1

Aqueous photolysis DT₅₀ (days) at pH 7

Value

Stable

Note

Aqueous hydrolysis DT₅₀ (days) at 20 °C and pH 7

Value

Stable

Note

At pH 5 stable; At pH 9 DT₅₀ = 3.2 days

Water-sediment DT₅₀ (days)

34.7

Moderately fast

Water phase only DT₅₀ (days)

Sediment phase only DT₅₀ (days)

Air degradation

As this parameter is not normally measured directly, a surrogate measure is used: ‘Photochemical oxidative DT₅₀’. Where data is available, this can be found in the Fate Indices section below.

Decay in stored produce DT₅₀

Soil adsorption and mobility

Property

Value

Source; quality score; and other information

Interpretation

Linear

K_d (mL g⁻¹)

188.75

Non-mobile

K_oc (mL g⁻¹)

19550

Notes and range

EU dossier (2011) K_d range 95-260 mL g⁻¹, K_oc range 6200-43000 ml/g, soils =4

Freundlich

K_f (mL g⁻¹)

K_foc (mL g⁻¹)

¹/_n

Notes and range

pH sensitivity

Fate indices

Property

Value

Source; quality score; and other information

Interpretation

GUS leaching potential index

-0.14

Calculated

Low leachability

SCI-GROW groundwater index (μg l⁻¹) for a 1 kg ha⁻¹ or 1 l ha⁻¹ application rate

Value

5.35 X 10^-03

Calculated

Note

Estimated concentrations of chemicals with Koc values greater than 9995 ml g⁻¹ are beyond the scope of the regression data used in SCI-GROW development. If there are concerns for such chemicals, a higher tier groundwater exposure assessment should be considered, regardless of the concentration returned by SCI-GROW

Potential for particle bound transport index

Medium

Calculated

Potential for loss via drain flow

Non-mobile

Calculated

Photochemical oxidative DT₅₀ (hrs) as indicator of long-range air transport risk

9.82

Calculated using the Atkinson method. Assumed 0.5E+06 OH/cm³, 24 hr

Below the level of concern for long-range air transport

Bio-concentration factor

BCF (l kg⁻¹)

CT₅₀ (days)

Known soil metabolites

Metabolite

Major/Minor fraction

$Click here for further information on Major/Minor fraction$

Estimated maximum occurrence fraction

Notes

4-amino-3,5-dichloro-6-fluoro-2-pyridinol

Major fraction

0.239

4-amino-3,5-dichloro-6-fluoro-2-pirydynil-2-methoxypyridine

Major fraction

0.382

fluroxypyr (Ref: DOW 43304-H)

Major fraction

Known groundwater metabolites

Metabolite

EC SANCO/221/2000 relevancy

ADI (mg kg⁻¹ bodyweight day⁻¹)

WHO drinking water guidance value (μg L⁻¹ day⁻¹)

4-amino-3,5-dichloro-6-fluoro-2-pyridinol

Relevancy unknown

4-amino-3,5-dichloro-6-fluoro-2-pirydynil-2-methoxypyridine

Relevancy unknown

Other known metabolites

None

ECOTOXICOLOGY

Terrestrial ecotoxicology

Property

Value

Source; quality score; and other information

Interpretation

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

> 2000

Rat

Low

Mammals - Short term dietary NOEL

(mg kg⁻¹)

(ppm diet)

Mammals - Chronic 21d NOAEL (mg kg⁻¹ bw d⁻¹)

Birds - Acute LD₅₀ (mg kg⁻¹)

> 2000

Colinus virginianus

Low

Birds - Short term dietary (LC₅₀/LD₅₀)

> 5000 mg kg feed⁻¹

Colinus virginianus

Birds - Chronic 21d NOEL (mg kg⁻¹ bw d⁻¹)

Earthworms - Acute 14 day LC₅₀ (mg kg⁻¹)

> 500

Eisenia foetida corr

Moderate

Earthworms - Chronic NOEC, reproduction (mg kg⁻¹)

1.96

Eisenia foetida corr

Moderate

Soil micro-organisms

Nitrogen mineralisation: No significant adverse effect
Carbon mineralisation: No significant adverse effect

Dose: 2 kg ha⁻¹

Collembola

Acute LC₅₀ (mg kg⁻¹)

Chronic NOEC (mg kg⁻¹)

Non-target plants

Honeybees (Apis spp.)

Contact acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)

> 100

Low

Oral acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)

> 100

Low

Unknown mode acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)

Chronic

Notes

Bumblebees (Bombus spp.)

Contact acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)

Oral acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)

Mason bees (Osmia spp.)

Contact acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)

Oral acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)

Other bee species (1)

Acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg insect⁻¹)

Mode of exposure

Other bee species (2)

Acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg insect⁻¹)

Mode of exposure

Beneficial insects (Ladybirds)

Beneficial insects (Lacewings)

Beneficial insects (Parasitic wasps) as Mortality LR₅₀ g ha⁻¹

234.18

Aphidius rhopalosiphi as the meptyl ester

Beneficial insects (Predatory mites) as Mortality LR₅₀ g ha⁻¹

> 396

Typhlodromus pyri Adult as the meptyl ester

Beneficial insects (Ground beetles)

Aquatic ecotoxicology

Property

Value

Source; quality score; and other information

Interpretation

Temperate Freshwater Fish - Acute 96 hour LC₅₀ (mg l⁻¹)

> 0.225

Oncorhynchus mykiss

Moderate

Temperate Freshwater Fish - Chronic 21 day NOEC (mg l⁻¹)

0.2

Oncorhynchus mykiss

Moderate

Tropical Freshwater Fish - Acute 96 hour LC₅₀ (mg l⁻¹)

Temperate Freshwater Aquatic invertebrates - Acute 48 hour EC₅₀ (mg l⁻¹)

> 0.183

Daphnia magna

Moderate

Temperate Freshwater Aquatic invertebrates - Chronic 21 day NOEC (mg l⁻¹)

0.06

Daphnia magna

Moderate

Tropical Freshwater Aquatic invertebrates - Acute 48 hour EC₅₀ (mg l⁻¹)

Aquatic crustaceans - Acute 96 hour LC₅₀ (mg l⁻¹)

Sediment dwelling organisms - Acute 96 hour LC₅₀ (mg l⁻¹)

Sediment dwelling organisms - Chronic 28 day NOEC, static, water (mg l⁻¹)

0.13

Chironomus riparius

Moderate

Sediment dwelling organisms - Chronic 28 day NOEC, sediment (mg kg⁻¹)

Aquatic plants (free-floating, growth) - Acute 7 day EC₅₀, biomass (mg l⁻¹)

> 2.31

Lemna gibba

Moderate

Aquatic plants (rooted, growth) - Acute 14 day EC₅₀, biomass (mg l⁻¹)

Algae - Acute 72 hour EC₅₀, growth (mg l⁻¹)

> 0.5

Scenedesmus subspicatus

Moderate

Algae - Chronic 96 hour NOEC, growth (mg l⁻¹)

Mesocosm study data

NOEAEC mg l⁻¹

Marine bivalves

HUMAN HEALTH AND PROTECTION

General

Property

Value

Source; quality score; and other information

Interpretation

Threshold of Toxicological Concern (Cramer Class)

High (class III)

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

> 2000

Rat

Low

Mammals - Dermal LD₅₀ (mg kg⁻¹ body weight)

2000

Rat

Mammals - Inhalation LC₅₀ (mg l⁻¹)

> 1.0

Rat 4 hr

Other Mammal toxicity endpoints

ADI - Acceptable Daily Intake (mg kg⁻¹ bw day⁻¹)

0.8

as fluroxypyr

ARfD - Acute Reference Dose (mg kg⁻¹ bw day⁻¹)

None allocated

AAOEL - Acute Acceptable Operator Exposure Level (mg kg⁻¹ bw day⁻¹)

AOEL - Acceptable Operator Exposure Level - Systemic (mg kg⁻¹ bw day⁻¹)

0.8

as fluroxypyr

Dermal penetration studies (%)

4-22

concentration dependent

Dangerous Substances Directive 76/464

List II

Exposure Routes

Public

Occupational

MRLs

European

EU MRL pesticide database

Great Britain

GB MRL Register

Notes

Drinking Water Standards

Drinking Water MAC (μg l⁻¹)

Mammalian dose elimination route and rate

Health issues

Specific human health issues

Carcinogen

Genotoxic

Endocrine disruptor

; ; ; ;

Reproduction / development effects

Acetyl cholinesterase inhibitor

Neurotoxicant

Respiratory tract irritant

Skin irritant

Skin sensitiser

No dta

Eye irritant

Phototoxicant

No data found

General human health issues

Possible kidney toxicant

Handling issues

Property

Value and interpretation

General

Prevent generation of mists
Not explosive or oxidising
Not expected to auto-ignite; Not highly flammable
IMDG Transport Hazard Class 9

CLP classification 2013

Environment: H400, H410

WHO Classification

U (Unlikely to present an acute hazard)

UN Number

UN3082

Waste disposal & packaging

Packaging Group III (minor danger)

Shelf-life, storage, stability and reactivity

TRANSLATIONS

Language

Name

English

fluroxypyr-meptyl

French

fluoroxypyr-meptyl

German

Danish

Italian

Spanish

fluroxipir meptil

Greek

Polish

fluroksypyr meptylu

Swedish

fluroxipyr-1-metylheptylester

Hungarian

Dutch

Norwegian

fluroksypyr-meptyl

Record last updated:	26/05/2025
Contact:	aeru@herts.ac.uk
Please cite as:	Lewis, K.A., Tzilivakis, J., Warner, D. and Green, A. (2016) An international database for pesticide risk assessments and management. Human and Ecological Risk Assessment: An International Journal, 22(4), 1050-1064. DOI: 10.1080/10807039.2015.1133242