Pyridafol (Ref: CL 9673)

Pyridafol (Ref: CL 9673)	Last updated: 18/07/2024
(Also known as: pyridate metabolite)

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 High alert: GUS: High leachability	Ecotoxicity Moderate alert: Fish acute ecotoxicity: Moderate; Daphnia acute ecotoxicity: Moderate; Daphnia chronic ecotoxicity: Moderate; Earthworms acute ecotoxicity: Moderate; Earthworms chronic ecotoxicity: Moderate	Human health Low alert Warning: Significant data are missing

GENERAL INFORMATION

Description

A herbicide and chemical transformation product

Example pests controlled

Broad-leaved weeds including nightshade, cleavers, nettles, chickweed;dead-nettle, fathen, ragweed; Grasses including barnyard grass, crabgrass, foxtail

Example applications

Cereals; Brassicas including cauliflowers, kohlrabi, broccoli, Brussels; Alliums including onions, shallots, chives, leek; Fodder beet; Lupins; Rape

Efficacy & activity

Availability status

Introduction & key dates

GB regulatory status

GB COPR regulatory status

Not approved

Date COPR inclusion expires

Not applicable

GB LERAP status

No UK approval for use as a pesticide

EC Regulation 1107/2009 (repealing 91/414)

EC Regulation 1107/2009 status

Not approved

Dossier rapporteur/co-rapporteur

Date EC 1107/2009 inclusion expires

Not applicable

EU Candidate for substitution (CfS)

Not applicable

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

Chemical structure

Isomerism

None

Chemical formula

C₁₀H₇ClN₂O

Canonical SMILES

C1=CC=C(C=C1)C2=NNC(=CC2=O)Cl

Isomeric SMILES

International Chemical Identifier key (InChIKey)

ZUSHSDOEVHPTCU-UHFFFAOYSA-N

International Chemical Identifier (InChI)

InChI=1S/C10H7ClN2O/c11-9-6-8(14)10(13-12-9)7-4-2-1-3-5-7/h1-6H,(H,12,14)

2D structure diagram/image available?

Yes

General status

Pesticide type

Herbicide, Metabolite

Metabolite Type

Soil, Surface water, Groundwater

Substance groups

Pyradazine herbicide

Minimum active substance purity

Known relevant impurities

Substance origin

Synthetic

Mode of action

Photosynthetic electron transport inhibitor at the photosystem II.

CAS RN

40020-01-7

EC number

254-752-1

CIPAC number

630

US EPA chemical code

Not applicable

PubChem CID

92316

CLP index number

No data found

Molecular mass

206.62

PIN (Preferred Identification Name)

6-chloro-3-phenylpyridazin-4-ol

IUPAC name

6-chloro-3-phenylpyridazin-4-ol

CAS name

6-chloro-3-phenyl-4-pyridazinol

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

Physical state

White powder

Related substances & organisms

pyridafol-O-methyl

Can be a metabolite of:

Parent

Formation medium

Estimated maximum occurrence fraction

1107/2009 relevancy

pyridafol-O-methyl

Soil

Major fraction

pyridate

Soil

0.907

Major fraction

Formulations

Property

Value

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

Example products using this active

Formulation and application details

ENVIRONMENTAL FATE

Property

Value

Source; quality score; and other information

Interpretation

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

23800

at pH 8.2

High

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

Melting point (°C)

Boiling point (°C)

408

Degradation point (°C)

Flashpoint (°C)

200.6

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

3.63 X 10⁰⁰

Calculated

Log P

0.56

Low

Fat solubility of residues

Solubility

Data type

Density (g ml⁻¹)

1.36

Dissociation constant pKa) at 25 °C

6.7

Vapour pressure at 20 °C (mPa)

1.94 X 10^-04

Low volatility

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

7.86 X 10^-07

at pH 5 20°C

Non-volatile

Volatilisation as max % of applied dose lost

From plant surface

From soil surface

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

pH 6.4: 201.5nm=27877.5, 223.5nm=16670.5, 257.5nm=10366.5, 301.5nm=10366.5
pH 1.94: 196nm=46229.1, 225nm=12467.8, 277.5nm=105.06.6
pH 11.6: 206nm=53723.8, 222.5nm=31614.4, 256.5nm=15703.9, 14739.6nm=14739.6

Surface tension (mN m⁻¹)

70.9

Degradation

Property

Value

Source; quality score; and other information

Interpretation

General biodegradability

Soil degradation (days) (aerobic)

DT₅₀ (typical)

2.2

Non-persistent

DT₅₀ (lab at 20 °C)

2.2

Non-persistent

DT₅₀ (field)

Moderately persistent

DT₉₀ (lab at 20 °C)

23.1

Non-persistent

DT₉₀ (field)

321

DT₅₀ modelling endpoint

Note

EU dossier lab studies DT₅₀ range 16.5-42.8 days, DT₉₀ range 54.9-155 days; Field studies DT₅₀ range 0.6-82.0 days, DT₉₀ range 17.8-321 days

Dissipation rate RL₅₀ (days) on plant matrix

Value

Note

Dissipation rate RL₅₀ (days) on and in plant matrix

Value

Note

Aqueous photolysis DT₅₀ (days) at pH 7

Value

Note

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

Value

Note

Water-sediment DT₅₀ (days)

286

Slow

Water phase only DT₅₀ (days)

131

Stable

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)

Moderately mobile

K_oc (mL g⁻¹)

104

Notes and range

EU dossier K_oc range 20-188 mL g⁻¹

Freundlich

K_f (mL g⁻¹)

1.707

Mobile

K_foc (mL g⁻¹)

41.5

¹/_n

0.77

Notes and range

EU dossier K_f range 0.11-10.2 mL g⁻¹, K_foc range 4-339 mL g⁻¹, ¹/_n range 0.66-0.89, soils=22

pH sensitivity

Adsoprtion increases with increasing OM and decreasing pH

Fate indices

Property

Value

Source; quality score; and other information

Interpretation

GUS leaching potential index

4.73

Calculated

High leachability

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

Value

3.19 X 10⁰⁰

Calculated

Note

Potential for particle bound transport index

Medium

Calculated

Potential for loss via drain flow

Moderately mobile

Calculated

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

55.2

Calculated using the Atkinson method

Substance of concern for long-range air transport

Bio-concentration factor

BCF (l kg⁻¹)

Low potential

CT₅₀ (days)

Not available

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)

Birds - Short term dietary (LC₅₀/LD₅₀)

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

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

> 348

Eisenia foetida

Moderate

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

3.25

Eisenia foetida

Moderate

Soil micro-organisms

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)

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

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)

Beneficial insects (Predatory mites)

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)

> 20.0

Oncorhynchus mykiss

Moderate

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

Oncorhynchus mykiss

Low

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

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

26.1

Daphnia magna

Moderate

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

5.0

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)

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

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

4.84

Lemna gibba

Moderate

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

4.93

Selenastrum capricornutum

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)

Mammals - Inhalation LC₅₀ (mg l⁻¹)

Other Mammal toxicity endpoints

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

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

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

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

Dermal penetration studies (%)

Dangerous Substances Directive 76/464

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

No data found

; ; ; ;

No data found

Reproduction / development effects

Acetyl cholinesterase inhibitor

Neurotoxicant

No data found

Respiratory tract irritant

Skin irritant

Skin sensitiser

No data found

Eye irritant

Phototoxicant

No data found

General human health issues

No further information available

Handling issues

Property

Value and interpretation

General

No information available

CLP classification 2013

Not classified

WHO Classification

Not listed (Not listed)

UN Number

Waste disposal & packaging

Shelf-life, storage, stability and reactivity

TRANSLATIONS

Language

Name

English

pyridafol

French

6-chloro-3-phénylpyridazine-4-ol

German

6-Chlor-3-phenylpyridazin-4-ol

Danish

Italian

Spanish

6-cloro-3-fenilpiridazin-4-ol

Greek

Polish

6-chloro-3-fenylopirydazyn-4-ol

Swedish

Hungarian

Dutch

Norwegian

Record last updated:	18/07/2024
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