Lenacil (Ref: DPX B634)

Lenacil (Ref: DPX B634)	Last updated: 17/07/2024
(Also known as: lenacile)

SUMMARY

Lenacil is an uracil herbicide for selective weed control. It has a low solubility in water, has a high risk of leaching to groundwater based on its chemical properties and is semi-volatile. It is moderately persistent in soil and will persist in aquatic systems. It is not greatly toxic to mammals and is a known irritant, but no other significant human health issues have been identified. It is moderately toxic to birds, most aquatic organisms, honeybees and earthworms.

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: Birds chronic ecotoxicity: Moderate; Fish acute ecotoxicity: Moderate; Fish chronic ecotoxicity: Moderate; Daphnia acute ecotoxicity: Moderate; Daphnia chronic ecotoxicity: Moderate	Human health Moderate alert: Possible Carcinogen; Reproduction/development effects

GENERAL INFORMATION

Description

A soil-acting herbicide for the control of weeds in beet and other crops

Example pests controlled

Annual grasses; Broad-leaved weeds

Example applications

Sugarbeet; Red beet; Fodder beet; Mangels; Sugarcane; Ornamentals; Currants; Gooseberries; Spinach; Turnips

Efficacy & activity

Efficacy demonstrated via long term use and via the EU's Uniform Principles approach

Availability status

Current

Introduction & key dates

circa 1965, introduced

GB regulatory status

GB COPR regulatory status

Approved

Date COPR inclusion expires

31/12/2027

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

Belgium/Austria

Date EC 1107/2009 inclusion expires

15/08/2025

EU Candidate for substitution (CfS)

Yes - two 'Persistent-Bioaccumulative-Toxic' criteria

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

Morocco

Chemical structure

Isomerism

None

Chemical formula

C₁₃H₁₈N₂O₂

Canonical SMILES

C1CCC(CC1)N2C(=O)C3=C(CCC3)NC2=O

Isomeric SMILES

No data

International Chemical Identifier key (InChIKey)

ZTMKADLOSYKWCA-UHFFFAOYSA-N

International Chemical Identifier (InChI)

InChI=1S/C13H18N2O2/c16-12-10-7-4-8-11(10)14-13(17)15(12)9-5-2-1-3-6-9/h9H,1-8H2,(H,14,17)

2D structure diagram/image available?

Yes

General status

Pesticide type

Herbicide

Substance groups

Uracil herbicide

Minimum active substance purity

975 g kg⁻¹

Known relevant impurities

EU dossier - None declared

Substance origin

Synthetic

Mode of action

Selective, systemic absorbed by roots and having residual effect. Inhibits photosynthesis (photosystem II).

CAS RN

2164-08-1

EC number

218-499-0

CIPAC number

163

US EPA chemical code

525200

PubChem CID

16559

CLP index number

613-320-00-6

Molecular mass

234.29

PIN (Preferred Identification Name)

IUPAC name

3-cyclohexyl-1,5,6,7-tetrahydrocyclopentapyrimidine-2,4(3H)-dione

CAS name

3-cyclohexyl-6,7-dihydro-1H-cyclopentapyrimidine-2,4(3H,5H)-dione

Other status information

PAN listed Highly Hazardous Chemical

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 to tan coloured crystals

Formulations

Property

Value

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

AgriGuard
Clayton
DuPont
Fahlberg-List

Example products using this active

Safari Lite
Venzar Flowable
Lenazar Flo
Elbatan

Formulation and application details

Often supplied as soluble concentrate or wettable powder

ENVIRONMENTAL FATE

Property

Value

Source; quality score; and other information

Interpretation

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

2.9

Low

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

690

Acetone

Toluene

1.3

Hexane

500

Ethyl acetate

Melting point (°C)

Decomposes before melting

Boiling point (°C)

Decomposes before boiling

Degradation point (°C)

270

Flashpoint (°C)

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

4.90 X 10⁰¹

Calculated

Log P

1.69

Low

Fat solubility of residues

Solubility

Data type

Density (g ml⁻¹)

1.32

Dissociation constant pKa) at 25 °C

10.7

Very weak acid

Vapour pressure at 20 °C (mPa)

1.7 X 10^-06

Low volatility

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

1.3 X 10^-07

Non-volatile

Volatilisation as max % of applied dose lost

From plant surface

From soil surface

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

Neutral solution: 271nm = 7880, 290nm = 1760
Acidic solution: 271nm = 7990, 290nm = 1760
Basic solution, 227nm = 7220, 291nm = 1760

Surface tension (mN m⁻¹)

62.5

at 24°C

Degradation

Property

Value

Source; quality score; and other information

Interpretation

General biodegradability

Soil degradation (days) (aerobic)

DT₅₀ (typical)

49.7

Moderately persistent

DT₅₀ (lab at 20 °C)

49.7

Moderately persistent

DT₅₀ (field)

39.8

Moderately persistent

DT₉₀ (lab at 20 °C)

53.2

Moderately persistent

DT₉₀ (field)

131.8

DT₅₀ modelling endpoint

10.5

geometric mean

Note

EU dossier 2019 lab studies DT₅₀ (normalised) range 20.5-96.1 days, Soils=8, DT₉₀ (2013 measured data) range 37-83 days, 2013 field studies DT₅₀ (normalised) range 18-88 days, DT₉₀ (measured) range 61-291 days; Other sources: DT₅₀ range 35-200 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

Stable

Note

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

Value

Stable

Note

Stable pH 5 to pH 9 for over 1 year

Water-sediment DT₅₀ (days)

112

Slow

Water phase only DT₅₀ (days)

Stable

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)

165

Notes and range

Literature range 75-254 mL g⁻¹

Freundlich

K_f (mL g⁻¹)

2.39

Moderately mobile

K_foc (mL g⁻¹)

130

¹/_n

0.89

Notes and range

EU 2019 dossier kf range 0.35-7.87, K_foc range 75-254 mL g⁻¹, ¹/_n range 0.86-0.94, Soils=7

pH sensitivity

Fate indices

Property

Value

Source; quality score; and other information

Interpretation

GUS leaching potential index

3.02

Calculated

High leachability

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

Value

2.94 X 10^-01

Calculated

Note

Potential for particle bound transport index

Low

Calculated

Potential for loss via drain flow

Moderately mobile

Calculated

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

Bio-concentration factor

BCF (l kg⁻¹)

Estimated

Low potential

CT₅₀ (days)

Not available

Known soil metabolites

Metabolite

Major/Minor fraction

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

Estimated maximum occurrence fraction

Notes

3-cyclohexyl-6,7-dihydro-7-1H-cyclopentapyrimidine-2,4,5-(3H)trione (Ref: IN KE121)

Major fraction

0.139

3-cyclohexyl-6,7-dihydroxy-7-1H-cyclopentapyrimidine-2,4,5(3H)trione (Ref: IN KF313)

Major fraction

0.217

7-hydroxy lenacil (Ref: IN-KC943)

Minor fraction

3-cyclohexyl-5,6-dihydro-1H-cyclopentapyrimidine-2,4,7-(3H)trione (Ref: IN-KD302)

Minor 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)

3-cyclohexyl-6,7-dihydro-7-1H-cyclopentapyrimidine-2,4,5-(3H)trione (Ref: IN KE121)

Not relevant

3-cyclohexyl-6,7-dihydroxy-7-1H-cyclopentapyrimidine-2,4,5(3H)trione (Ref: IN KF313)

Not relevant

Other known metabolites

Metabolite name and reference

Aliases

Formation medium / Rate

Estimated maximum occurrence fraction

Ref: IN-KQ961

Water (Photolysis)

Ref: IN-KC943

7-hydroxy lenacil

Plant

ECOTOXICOLOGY

Terrestrial ecotoxicology

Property

Value

Source; quality score; and other information

Interpretation

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

> 5000

Rat

Low

Mammals - Short term dietary NOEL

(mg kg⁻¹)

(ppm diet)

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

4279

Rat Reproductive NOAEL

Low

Birds - Acute LD₅₀ (mg kg⁻¹)

> 2000

Anas platyrhynchos

Low

Birds - Short term dietary (LC₅₀/LD₅₀)

> 1088 mg kg bw⁻¹ day⁻¹

Colinus virginianus

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

100.4

Colinus virginianus NOEL

Moderate

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

> 1000

Eisenia foetida

Low

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

1000

Eisenia foetida

Low

Soil micro-organisms

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

Dose: 5.0 kg ha⁻¹; 28 Day

Collembola

Acute LC₅₀ (mg kg⁻¹)

Chronic NOEC (mg kg⁻¹)

Non-target plants

427

Lycopersicon esculentum
Vegetative vigour, ER₅₀
as g ha⁻¹

177.2

Brassica napus
Seedling emergence, ER₅₀
as g ha⁻¹

Honeybees (Apis spp.)

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

> 227.2

Apis mellifera

Low

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

> 206.2

Apis mellifera

Low

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

Chronic as 10-day LDD₅₀ µg bee⁻¹ day⁻¹

> 142.3

Apis mellifera

Bumblebees (Bombus spp.)

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

> 200.0

Bombus terrestris

Low

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

> 195.4

Bombus terrestris

Low

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

> 1900

Aphidius rhopalosiphi

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

> 1900

Typhlodromus pyri

Beneficial insects (Ground beetles) as Mortality LR₅₀ g ha⁻¹

> 1700

Poecilus cupreus

Aquatic ecotoxicology

Property

Value

Source; quality score; and other information

Interpretation

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

> 2.0

Oncorhynchus mykiss

Moderate

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

2.3

Oncorhynchus mykiss

Moderate

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

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

> 8.4

Daphnia magna

Moderate

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

0.48

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)

0.019

Lemna gibba

Moderate

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

0.0077

Pseudokirchneriella subcapitata

High

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

0.01

Unknown species

Moderate

Mesocosm study data

NOEAEC mg l⁻¹

0.0221

Macrophytes zooplankton and phytoplankton

NOEAEC mg l⁻¹

Marine bivalves – Acute EC₅₀ development (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)

> 5000

Rat

Low

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

2000

Rat

Mammals - Inhalation LC₅₀ (mg l⁻¹)

> 5.12

Rat 4 hr (nose only aerosol)

Other Mammal toxicity endpoints

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

0.12

Rat SF=100

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

None allocated

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

3.0

Rat SF=100

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

0.4

Rat SF=100

Dermal penetration studies (%)

25-75%

concentration dependent; default values

Dangerous Substances Directive 76/464

Exposure Routes

Public

Negligible risk for bystanders

Occupational

Potential risk of exposure to operators - PPE/PPC required

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

Excreted mainly via the urine within 12-24 hrs

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 liver, spleen or thyroid toxicant
CLP data - suspected carcingen

Handling issues

Property

Value and interpretation

General

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

CLP classification 2013

Health: H351
Environment: H400, H410

WHO Classification

U (Unlikely to present an acute hazard)

UN Number

UN3077

Waste disposal & packaging

Packaging Group III (minor danger)

Shelf-life, storage, stability and reactivity

Chemically stable under standard ambient conditions

TRANSLATIONS

Language

Name

English

lenacil

French

lenacile

German

Lenacil

Danish

lenacil

Italian

lenacil

Spanish

lenacilo

Greek

Polish

lenacyl

Swedish

Hungarian

lenacil

Dutch

lenacil

Norwegian

Record last updated:	17/07/2024
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