Bentazone

Bentazone	Last updated: 01/01/2021
(Also known as: bendioxide; bentazon)

SUMMARY

Bentazone is a herbicide approved for use in the EU. It is highly soluble in water, volatile and, as it is mobile, may present a risk of leaching to groundwater. It is not likely tyo be persistent in soil systems but may be persistent in water under certain conditions. It is moderately toxic to humans and a recognised skin and eye irritant. Bentazone is also moderately toxic to birds, fish, aquatic invertebrates and earthworms.

GENERAL INFORMATION

Description

A post-emergence contact diazinone herbicide used to control annual weeds in a variety of crops

Example pests controlled

Black bindweed; Nightshade; Fat hen; Hedge mustard; Shepherd's purse; Wild radish; Wild turnip; Bellvine; Starburr; Anoda weed

Example applications

Corn; Rice; Alfalfa; Sorghum; Linseed; Peanuts; Beans; Peas; Clover; Chives; Garlic; Ornamentals e.g. begonia; Soybeans; Turf

Efficacy & activity

Availability status

Current

Introduction & key dates

1972, first introduced

UK regulatory status

UK COPR regulatory status

Approved

Date COPR inclusion expires

31/05/2025

UK LERAP status

None

EC Regulation 1107/2009 (repealing 91/414)

EC Regulation 1107/2009 status

Approved

Dossier rapporteur/co-rapporteur

Netherlands/Germany

Date EC 1107/2009 inclusion expires

31/05/2025

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

Australia

Chemical structure

Isomerism

Chemical formula

C₁₀H₁₂N₂O₃S

Canonical SMILES

CC(C)N1C(=O)C2=CC=CC=C2NS1(=O)=O

Isomeric SMILES

No data

International Chemical Identifier key (InChIKey)

ZOMSMJKLGFBRBS-UHFFFAOYSA-N

International Chemical Identifier (InChI)

InChI=1S/C17H21NO4S4/c1-18(2)15(13-23-25(19,20)16-9-5-3-6-10-16)14-24-26(21,22)17-11-7-4-8-12-17/h3-12,15H,13-14H2,1-2H3

2D structure diagram/image available?

Yes

General status

Pesticide type

Herbicide

Substance group

Benzothiazinone

Minimum active substance purity

960 g kg⁻¹

Known relevant impurities

EU dossier: 1,2-dichloroethane <3.0 mg kg⁻¹

Substance origin

Synthetic

Mode of action

Selective action, absorbed by foliage with very little translocation. Inhibits photosynthesis (photosystem II).

CAS RN

25057-89-0

EC number

246-585-8

CIPAC number

366

US EPA chemical code

275200

PubChem CID

2328

Molecular mass

240.3

PIN (Preferred Identification Name)

3-(propan-2-yl)-1H-2?6,1,3-benzothiadiazine-2,2,4(3H)-trione

IUPAC name

3-isopropyl-1H-2,1,3-benzothiadiazin-4(3H)-one 2,2-dioxide

CAS name

3-(1-methylethyl)-1H-2,1,3-benzothiadiazin-4(3H)-one 2,2-dioxide

Other status information

Potential groundwater contaminant

Relevant Environmental Water Quality Standards

UK Environment Agency statutory standard for the protection of surface water quality and aquatic life: annual mean classification of inland waters, coastal waters & relevant territorial waters: 500 µg l⁻¹

Herbicide Resistance Classification (HRAC)

Herbicide Resistance Classification (WSSA)

Insecticide Resistance Classification (IRAC)

Not applicable

Fungicide Resistance Classification (FRAC)

Not applicable

Examples of recorded resistance

Physical state

White to yellow coloured crystals depending upon purity

Related substances & organisms

MCPA

MCPB

Formulations

Property

Value

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

Basagran
Zone 48
Troy 480
Herbatox
Leader
Laddox

Example products using this active

AgriGuard
BASF
Goldengrass

Formulation and application details

Usually formulated as a soluble concentrate or granules, 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)

7112

High

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

18.0

n-Heptane

21000

Toluene

388000

Ethyl acetate

556000

Methanol

Melting point (°C)

139

Boiling point (°C)

Decomposes before boiling

Degradation point (°C)

210

Flashpoint (°C)

Not expected to self ignite; Not highly flammable

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

3.47 X 10^-01

Calculated

Log P

-0.46

Low

Bulk density (g ml⁻¹)

1.41

Dissociation constant pKa) at 25 °C

3.51

Weak acid; pKa(2)=2.50

Vapour pressure at 20 °C (mPa)

0.17

Low volatility

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

7.20 X 10^-05

Non-volatile

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

pH 4.4: 225nm=30854; 335nm=2987.8

Surface tension (mN m⁻¹)

Degradation

Property

Value

Source; quality score; and other information

Interpretation

General biodegradability

Soil degradation (days) (aerobic)

DT₅₀ (typical)

Non-persistent

DT₅₀ (lab at 20 °C)

Non-persistent

DT₅₀ (field)

7.5

Non-persistent

DT₉₀ (lab at 20 °C)

91.2

Moderately persistent

DT₉₀ (field)

31.9

DT₅₀ modelling endpoint

Note

EU dossier Lab studies DT₅₀ range 8-35.0 days, DT₉₀ range 32-149.8 days, Soils=12; field study DT₅₀ range 3.0-31.3 days, DT₉₀ range 12.9-87.7 days, Soils=8

Dissipation rate RL₅₀ on plant matrix

Value

Note

Dissipation rate RL₅₀ on and in plant matrix

Value

1.5

Note

Wheat, whole plant, n=1

Aqueous photolysis DT₅₀ (days) at pH 7

Value

Moderately fast

Note

DT₅₀ 122 hours at pH 5, 14 hours at pH 9

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

Value

Stable

Note

Stable pH 5 to pH 9

Water-sediment DT₅₀ (days)

716

Stable

Water phase only DT₅₀ (days)

Stable

Soil adsorption and mobility

Property

Value

Source; quality score; and other information

Interpretation

Linear

K_d

0.72

Mobile

K_oc

55.3

Notes and range

EU dossier K_d range 0.22-2.99 mL g⁻¹; K_oc range 13-176 mL g⁻¹, Soils=7

Freundlich

K_f

0.97

Mobile

K_foc

59.6

¹/_n

0.93

Notes and range

EU 2015 dossier K_f range 0.02-3.06 mL g⁻¹, K_foc range 3.0-158.0 mL g⁻¹, ¹/_n range 0.7-1.03, Soils=25; Literature data: K_f range 1.2-1.9 mL g⁻¹, kfoc range 37-238 mL g⁻¹, ¹/_n range 1.00-1.01, Soils = 13

pH sensitivity

Fate indices

Property

Value

Source; quality score; and other information

Interpretation

GUS leaching potential index

1.95

Calculated

Transition state

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

Value

1.74 X 10^-02

Calculated

Note

Potential for particle bound transport index

Low

Calculated

Potential for loss via drain flow

Mobile

Calculated

Key metabolites

Metabolite

Formation medium

Estimated maximum occurrence fraction

1107/2009 relevancy

2-amino-N-isopropylbenzamide

Soil

Minor fraction, Not relevant

N-methyl bentazone

Soil

0.057

Minor fraction, Relevant

Other known metabolites

Metabolite name and reference

Aliases

Formation medium / Rate

Estimated maximum occurrence fraction

Metabolising enzymes

3-isopropyl-4,5-dioxo-1,3,4,5,6,7-hexahydrocyclopenta[c][1,2,6]thiadiazine-6-carboxylic acid 2,2-dioxide, salts (Ref: M351H023)

Peak-B

Surface water

[2-(isopropylcarbamoyl)phenyl]sulfamic acid, salts (Ref: M351H024)

Peak-C

Surface water

8-hydroxy-bentazone

Plant; Animal

6-hydroxy bentazone

Plant; Animal

ECOTOXICOLOGY

Property

Value

Source; quality score; and other information

Interpretation

Bio-concentration factor

BCF (l kg⁻¹)

Low potential

CT₅₀ (days)

Not available

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

1400

Rat

Moderate

Mammals - Short term dietary NOEL

(mg kg⁻¹)

Rat

High

(ppm diet)

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

164.3

Rat Reproductive NOAEL

Moderate

Birds - Acute LD₅₀ (mg kg⁻¹)

1140

Colinus virginianus

Moderate

Birds - Short term dietary (LC₅₀/LD₅₀)

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

Anas platyrhynchos

Moderate

Fish - Acute 96 hour LC₅₀ (mg l⁻¹)

> 100

Oncorhynchus mykiss

Low

Fish - Chronic 21 day NOEC (mg l⁻¹)

Oncorhynchus mykiss

Low

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

> 100

Daphnia magna

Low

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

> 101

Daphnia magna

Low

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

132.5

Americamysis bahia

Low

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)

5.4

Lemna gibba

Moderate

Non-target plants

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

10.1

Anabaena flos-aquae 120 hour

Low

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

25.7

Unknown species

Low

Honeybees (Apis spp.)

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

> 200

Apis mellifera

Low

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

> 200

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)

> 1000

Eisenia foetida

Low

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

% Effect

Parasitism [Dose: 2.63 kg ha⁻¹]
Trichogramma cacoeciae adult

Other arthropod (2)

LR₅₀ g ha⁻¹

% Effect

Mortality [Dose: 1.92 Kg ha⁻¹]
Typhlodromus pyri protonymph

Soil micro-organisms

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

Dose: 9.6 kg ha⁻¹

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)

1400

Rat

Moderate

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

5000

Rat

Mammals - Inhalation LC₅₀ (mg l⁻¹)

> 5.1

Rat 4 hr (head-nose only)

Other Mammal toxicity endpoints

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

0.1

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

0.25

Rat 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)

0.13

Dog 1 year SF=100

Dermal penetration studies (%)

0.2-0.9

concentration dependent

Dangerous Substances Directive 76/464

List II

Exposure Routes

Public

Minimal risk of dietary exposure
No unacceptable risks to bystanders identified

Occupational

Risk of exposure acceptable under label recommendations for use for personal protection clothing and equipment

MRLs

European

EU MRL pesticide database

Notes

Drinking Water Standards

Drinking Water MAC (μg l⁻¹)

Health issues

Specific human health issues

Carcinogen

Genotoxic

Endocrine disruptor

; ; ; ;

Reproduction / development effects

Acetyl cholinesterase inhibitor

Neurotoxicant

Respiratory tract irritant

Skin irritant

Skin sensitiser

Eye irritant

Phototoxicant

General human health issues

Possible blood, liver, kidney toxicant

Handling issues

Property

Value and interpretation

General

Not oxidising or explosive

CLP classification 2013

Health: H302, H317, H319
Environment: H412

EC Risk Classification

Xn - Harmful: R22, R43
Xi - Irritant: R36
N - Dangerous for the environment: R52, R53

EC Safety Classification

S2, S24, S37, S61

WHO Classification

II (Moderately hazardous)

UN Number

Usually 2588

Waste disposal & packaging

Packaging Group III (minor danger)

TRANSLATIONS

Language

Name

English

bentazone

French

bentazone

German

Bentazon

Danish

bentazon

Italian

bentazone

Spanish

bentazona

Greek

bentazone

Polish

bentazon

Swedish

bentazon

Hungarian

bentazone

Dutch

bentazon

Record last updated:	01/01/2021
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