Hymexazol (Ref: F 319)

Hymexazol (Ref: F 319)	Last updated: 12/01/2021
(Also known as: hydroxyisoxazole; SF 6505)

GENERAL INFORMATION

Description

A systemic fungicide used to control soil-borne diseases caused by Fusaruim, Aphanomyces and Pythium spp.

Example pests controlled

Fusarium crown rot; Root rot; Stem rot

Example applications

Rice; Sugarbeet; Fodder beet; Vegetables; Tomatoes; Ornamentals

Efficacy & activity

Availability status

Current

Introduction & key dates

1966, first reported; 1969, Introduced Japan

UK regulatory status

UK COPR regulatory status

Approved

Date COPR inclusion expires

31/05/2024

UK LERAP status

None

EC Regulation 1107/2009 (repealing 91/414)

EC Regulation 1107/2009 status

Approved

Dossier rapporteur/co-rapporteur

Austria/Sweden

Date EC 1107/2009 inclusion expires

31/05/2021

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
		✓	✓		✓	✓

Also used in

Chemical structure

Isomerism

None

Chemical formula

C₄H₅NO₂

Canonical SMILES

CC1=CC(=O)NO1

Isomeric SMILES

No data

International Chemical Identifier key (InChIKey)

KGVPNLBXJKTABS-UHFFFAOYSA-N

International Chemical Identifier (InChI)

InChI=1S/C4H5NO2/c1-3-2-4(6)5-7-3/h2H,1H3,(H,5,6)

2D structure diagram/image available?

Yes

Cambridge Crystallographic Data Centre diagrams

Common Name	Relationship	Link
hymexazol	-

General status

Pesticide type

Fungicide

Substance group

Oxazole

Minimum active substance purity

985 g kg⁻¹

Known relevant impurities

EU dossier - None declared

Substance origin

Synthetic

Mode of action

Systemic, inhibits fungal growth by inhibiting nucleic acid synthesis (DNA / RNA synthesis).

CAS RN

10004-44-1

EC number

233-000-6

CIPAC number

528

US EPA chemical code

PubChem CID

24781

Molecular mass

99.15

PIN (Preferred Identification Name)

IUPAC name

5-methylisoxazol-3-ol

CAS name

5-methyl-3(2H)-isoxazolone

Other status information

Relevant Environmental Water Quality Standards

Herbicide Resistance Classification (HRAC)

Not applicable

Herbicide Resistance Classification (WSSA)

Not applicable

Insecticide Resistance Classification (IRAC)

Not applicable

Fungicide Resistance Classification (FRAC)

Examples of recorded resistance

Physical state

Colourless to pale yellow coloured crystals

Related substances & organisms

pencycuron

Formulations

Property

Value

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

Tachigaren WP
Terrazol
Hymexate
Sound

Example products using this active

Bayer CropScience
Summit Agro
AgroCare
Sanko

Formulation and application details

Often supplied as a wettable powder, dusts , emulsifiable concentrates and seed treatments

ENVIRONMENTAL FATE

Property

Value

Source; quality score; and other information

Interpretation

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

65100

High

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

730000

Acetone

200000

Benzene

12200

Hexane

968000

Methanol

Melting point (°C)

83.9

Boiling point (°C)

Decomposes before boiling

Degradation point (°C)

180

Flashpoint (°C)

203

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

2.00 X 10⁰⁰

Calculated

Log P

0.3

Low

Bulk density (g ml⁻¹)

0.55

Dissociation constant pKa) at 25 °C

5.92

Weak acid

Vapour pressure at 20 °C (mPa)

182

Highly volatile

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

1.40 X 10^-04

Non-volatile

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

Neutral solution: 205.6nm = 6796.4
Acidic solution: 201.9nm = 10344
Basic solution: 212.9nm = 5077

Surface tension (mN m⁻¹)

72.1

at 20°C

Degradation

Property

Value

Source; quality score; and other information

Interpretation

General biodegradability

Soil degradation (days) (aerobic)

DT₅₀ (typical)

Moderately persistent

DT₅₀ (lab at 20 °C)

17.8

Non-persistent

DT₅₀ (field)

6.8

Non-persistent

DT₉₀ (lab at 20 °C)

Moderately persistent

DT₉₀ (field)

22.7

DT₅₀ modelling endpoint

Note

EU dossier lab studies DT₅₀ range 13.7-32 days, DT₉₀ range 45-105 days; Field studies (DAR) DT₅₀ range 3.5-26 days; DT₉₀ range 12-87 days

Dissipation rate RL₅₀ on plant matrix

Value

Note

Dissipation rate RL₅₀ on and in plant matrix

Value

3.1

Note

Published literature RL₅₀ range 2.9-3.3 days, 3 field crops, various matrices, n=8

Aqueous photolysis DT₅₀ (days) at pH 7

Value

Stable

Note

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

Value

Stable

Note

Stable pH 5 to 9 at 20 °C

Water-sediment DT₅₀ (days)

5.9

Fast

Water phase only DT₅₀ (days)

5.8

Moderately fast

Soil adsorption and mobility

Property

Value

Source; quality score; and other information

Interpretation

Linear

K_d

K_oc

Notes and range

Freundlich

K_f

1.14

Mobile

K_foc

56.5

¹/_n

0.816

Notes and range

EU dossier K_f range 0.15-3.09, K_foc range 12-124 mL g⁻¹, ¹/_n range 0.74-0.93, Soils=5

pH sensitivity

Yes. Adsorption weaker on alkalaine soils.

Fate indices

Property

Value

Source; quality score; and other information

Interpretation

GUS leaching potential index

1.87

Calculated

Transition state

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

Value

1.13 X 10^-02

Calculated

Note

Potential for particle bound transport index

Low

Calculated

Potential for loss via drain flow

Mobile

Calculated

Other known metabolites

Metabolite name and reference

Aliases

Formation medium / Rate

Estimated maximum occurrence fraction

Metabolising enzymes

acetoacetic acid

Water

5-methyl-2(3H)-oxazolone (Ref: RMH-1915)

Water

0.172

acetoacetimide

Soil (anaerobic)

crotonic acid

Soil (anaerobic)

hymexanil-O-glucoside

Plant

hymexazol-O-diglucoside

Plant

hymexazol-N-monoglucoside

Plant

ECOTOXICOLOGY

Property

Value

Source; quality score; and other information

Interpretation

Bio-concentration factor

BCF (l kg⁻¹)

0.49

Estimated

Low potential

CT₅₀ (days)

Not available

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

1600

Rat

Moderate

Mammals - Short term dietary NOEL

(mg kg⁻¹)

Rat 2 year

High

(ppm diet)

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

Rat Reproductive NOEL

Moderate

Birds - Acute LD₅₀ (mg kg⁻¹)

> 1085

Coturnix japonica

Moderate

Birds - Short term dietary (LC₅₀/LD₅₀)

> 5200 mg kg feed⁻¹

Coturnix japonica

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

86.5

Colinius virginianus NOEL

Moderate

Fish - Acute 96 hour LC₅₀ (mg l⁻¹)

> 100

Oncorhynchus mykiss

Low

Fish - Chronic 21 day NOEC (mg l⁻¹)

> 100

Oncorhynchus mykiss

Low

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

Daphnia magna

Moderate

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

0.8

Daphnia magna

Moderate

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)

1.6

Chironomus riparius

Moderate

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

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

8.8

Lemna gibba

Moderate

Non-target plants

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

Pseudokirchneriella subcapitata 5 day

Low

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

Honeybees (Apis spp.)

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

> 100

Apis mellifera

Low

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

> 100

Apis mellifera

Low

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

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 pollinators (1)

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

Mode of exposure

Other pollinators (2)

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

Mode of exposure

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

281.9

Eisenia foetida

Moderate

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

Other soil macro-organisms

Acute LC₅₀ (mg kg⁻¹)

Chronic NOEC (mg kg⁻¹)

Other arthropod (1)

LR₅₀ g ha⁻¹

1426

Aphidius rhopalosiphi

% Effect

Other arthropod (2)

LR₅₀ g ha⁻¹

1107

Typhlodromus pyri

% Effect

Soil micro-organisms

Mesocosm study data

NOEAEC mg l⁻¹

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)

1600

Rat

Moderate

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

2000

Rabbit

Mammals - Inhalation LC₅₀ (mg l⁻¹)

> 0.65

Rat 4 hr

Other Mammal toxicity endpoints

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

0.17

Rat SF=100

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

0.5

Rabbit SF=100

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

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

0.17

Dog SF=100

Dermal penetration studies (%)

100

default

Dangerous Substances Directive 76/464

Exposure Routes

Public

Occupational

PPE/PPC advised

European MRLs

EU MRL pesticide database

Drinking Water Standards

Drinking Water MAC (μg l⁻¹)

Health issues

Specific human health issues

Carcinogen

Genotoxic

Endocrine disruptor

; ; ; ;

No data found

Reproduction / development effects

Acetyl cholinesterase inhibitor

Neurotoxicant

Respiratory tract irritant

Skin irritant

Skin sensitiser

No data found

Eye irritant

Phototoxicant

No data found

General human health issues

Highly toxic
Risk of serious damage to eyes
Liver, thyroid and kidney toxicant

Handling issues

Property

Value and interpretation

General

Not explosive or oxidising
IMDG Transport Code is usually 3

CLP classification 2013

Health: H302, H318
Environment: H412

EC Risk Classification

Xn - Harmful: R22, R41
N - Dangerous for the environment: R52, R53

EC Safety Classification

S2, S26, S39, S61

WHO Classification

III (Slightly hazardous)

UN Number

Usually 1325

Waste disposal & packaging

Packaging Group III (minor danger)

TRANSLATIONS

Language

Name

English

hymexazol

French

hymexazol

German

Hymexazol

Danish

hymexazol

Italian

hymexazol

Spanish

hymexazol

Greek

Polish

hymeksazol

Swedish

hymexazol

Hungarian

himexazol

Dutch

Record last updated:	12/01/2021
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