Oryzalin (Ref: EL 119)

Oryzalin (Ref: EL 119)	Last updated: 09/04/2025
(Also known as: dinitrodipropylsulfanilamide; dirimal; surflan)

SUMMARY

Oryzalin is a pre-emergence surface-applied herbicide. It has a low aqueous solubility, is not volatile and, based on its chemical properties, is not expected to leach to groundwater. However, groundwater monitoring programmes have identified it as a pollutant. It generally tends not to be persistent in soil or water systems. It has a low mammalian toxicity and is a potential carcinogen. 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 Moderate alert: Moderately persistent; GUS: Transition state; Drainflow: Slightly mobile; Potential for particle bound transport: Medium	Ecotoxicity Moderate alert: Birds acute ecotoxicity: Moderate; Fish acute ecotoxicity: Moderate; Fish chronic ecotoxicity: Moderate; Daphnia acute ecotoxicity: Moderate; Daphnia chronic ecotoxicity: Moderate; Bees acute contact ecotoxicity: Moderate; Bees acute oral ecotoxicity: Moderate; Earthworms acute ecotoxicity: Moderate; Earthworms chronic ecotoxicity: Moderate	Human health High alert: Genotoxic

GENERAL INFORMATION

Description

A pre-emergence surface-applied herbicide used for control of annual grasses and broadleaved weeds in fruit trees and around ornamentals

Example pests controlled

Annual grass weeds including Barnyardgrass; Pigeon grass; Crabgrass; Guinea grass; Broadleaved weeds including Deadnettle, Fathen; Pigweeds; Nightshade

Example applications

Fruit including citrus, stone fruit, apples, pears and berries; Nuts; Vines; Christmas trees; Ornamental trees; Nursery stock

Efficacy & activity

Availability status

Current

Introduction & key dates

1973, introduced

GB regulatory status

GB COPR regulatory status

Not approved

Date COPR inclusion expires

Withdrawn

GB LERAP status

No data

EC Regulation 1107/2009 (repealing 91/414)

EC Regulation 1107/2009 status

Not approved

Dossier rapporteur/co-rapporteur

Netherlands/France

Date EC 1107/2009 inclusion expires

Expired

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; USA

Chemical structure

Isomerism

None

Chemical formula

C₁₂H₁₈N₄O₆S

Canonical SMILES

CCCN(CCC)C1=C(C=C(C=C1[N+](=O)[O-])S(=O)(=O)N)[N+](=O)[O-]

Isomeric SMILES

No data

International Chemical Identifier key (InChIKey)

UNAHYJYOSSSJHH-UHFFFAOYSA-N

International Chemical Identifier (InChI)

InChI=1S/C12H18N4O6S/c1-3-5-14(6-4-2)12-10(15(17)18)7-9(23(13,21)22)8-11(12)16(19)20/h7-8H,3-6H2,1-2H3,(H2,13,21,22)

2D structure diagram/image available?

Yes

Cambridge Crystallographic Data Centre diagrams

Common Name	Relationship	Link
oryzalin	-

General status

Pesticide type

Herbicide

Substance groups

Dinitroaniline herbicide; Sulfonamide herbicide

Minimum active substance purity

960 g kg⁻¹

Known relevant impurities

EU dossier - N-nitrosodipropylamine 0.1 mg kg⁻¹; toluene 4g kg⁻¹

Substance origin

Synthetic

Mode of action

Selective affecting physiological growth process. Microtubule assembly inhibition.

CAS RN

19044-88-3

EC number

242-777-0

CIPAC number

537

US EPA chemical code

104201

PubChem CID

29393

CLP index number

No data found

Molecular mass

346.4

PIN (Preferred Identification Name)

IUPAC name

3,5-dinitro-N4,N4-dipropylsulfanilamide

CAS name

4-(dipropylamino)-3,5-dinitrobenzenesulfonamide

Other status information

Potential groundwater contaminant

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

Orange crystalline powder

Formulations

Property

Value

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

Dow AgroSciences
Elanco

Example products using this active

Surflan
Dirimal
Ryzelan

Formulation and application details

Usually supplied as an aqueous suspension or wettable powder

ENVIRONMENTAL FATE

Property

Value

Source; quality score; and other information

Interpretation

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

1.13

Low

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

250000

Acetone

91900

Methanol

0.709

n-Heptane

1570

Xylene

Melting point (°C)

139.7

Boiling point (°C)

Decomposes before boiling

Degradation point (°C)

213

Flashpoint (°C)

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

5.62 X 10⁰³

Calculated

Log P

3.75

High

Fat solubility of residues

Solubility

Soluble

Data type

Regulatory data - observed in metabolism and farm animal feeding studies

Density (g ml⁻¹)

1.2

Dissociation constant pKa) at 25 °C

9.4

Very weak acid

Vapour pressure at 20 °C (mPa)

1.1 X 10^-07

Low volatility

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

3.37 X 10^-08

Non-volatile

Volatilisation as max % of applied dose lost

From plant surface

24 hr

Volatilisation is not considered critical for air pollution

From soil surface

11.5

24 hr

Volatilisation is not considered critical for air pollution

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

Neutral solution: 208nm = 17200, 282nm = 97600, 380nm = 2690
Acidic solution: 206nm = 17500, 282nm = 380nm = 2740
Basic solution: 218nm = 14600, 273nm = 10100, 393nm = 2020

Surface tension (mN m⁻¹)

63.5

Degradation

Property

Value

Source; quality score; and other information

Interpretation

General biodegradability

Soil degradation (days) (aerobic)

DT₅₀ (typical)

44.8

Moderately persistent

DT₅₀ (lab at 20 °C)

Moderately persistent

DT₅₀ (field)

98.2

Moderately persistent

DT₉₀ (lab at 20 °C)

559

Very persistent

DT₉₀ (field)

184.9

DT₅₀ modelling endpoint

Note

EU dossier lab studies DT₅₀ range 32-456 days, DT₉₀ range 100-1553 days, field studies DT₅₀ range 10.9-113.2 days, DT₉₀ range 66-376 days ; Other sources: DT₅₀ 20 days (DW4)

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

0.08

Fast

Note

DT₅₀ 1.4 hours sterile water, 1.6 hours river water

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

Value

Stable

Note

Stable pH 3 to pH 9 at 25 °C

Water-sediment DT₅₀ (days)

32.7

Moderately fast

Water phase only DT₅₀ (days)

5.9

Moderately fast

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)

13.0

Slightly mobile

K_oc (mL g⁻¹)

949

Notes and range

EU dossier K_d range 5.23-25.21 mL g⁻¹, K_oc range 441-1596 mL g⁻¹, Soils=12

Freundlich

K_f (mL g⁻¹)

4.93

Slightly mobile

K_foc (mL g⁻¹)

724

¹/_n

0.943

Notes and range

EU dossier K_f range 4.83-5.04, K_foc range 439-1008, ¹/_n = 0.926-0.943

pH sensitivity

Fate indices

Property

Value

Source; quality score; and other information

Interpretation

GUS leaching potential index

2.27

Calculated

Transition state

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

Value

1.19 X 10^-01

Calculated

Note

Potential for particle bound transport index

Medium

Calculated

Potential for loss via drain flow

Slightly mobile

Calculated

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

5.37

Calculated using the Atkinson method. Assumed 1.5E+06 OH/cm³, 12 hr

Below the level of concern for long-range air transport

Bio-concentration factor

BCF (l kg⁻¹)

66.1

Whole fish

Low potential

CT₅₀ (days)

0.6

Known soil and groundwater metabolites

None

Other known metabolites

Metabolite name and reference

Aliases

Formation medium / Rate

Estimated maximum occurrence fraction

2-ethyl-7-nitro-1-propyl-5-sulfonylamino-benzimidazole-3-oxide

OR-13

Water (Photolysis)

3,4-diamino-5-nitrobenzensulfonamide

OR-6

Water (Photolysis)

2-ethyl-7-nitro-1hydroxy-benzimidazole-5-sulfonamide

OR-15-OH

Water (Photolysis)

2-ethyl-7-nitro-1H-benzimidazole-5-sulfonamide

OR-15

Water (Photolysis)

N-nitroso-N-propylpropan-1-amine

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)

Rat 2 yr

(ppm diet)

> 300

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

Birds - Acute LD₅₀ (mg kg⁻¹)

427

Anas platyrhynchos

Moderate

Birds - Short term dietary (LC₅₀/LD₅₀)

> 1351 mg kg bw⁻¹ day⁻¹

Anas platyrhynchos

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)

34.3

Eisenia foetida

Moderate

Soil micro-organisms

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

Dose: 25.6 mg kg⁻¹ soil 28 Day

Collembola

Acute LC₅₀ (mg kg⁻¹)

Chronic NOEC (mg kg⁻¹)

2.66

Folsomia candida

Non-target plants

26.0

Ryegrass
Seedling emergence, ER₅₀
as g ha⁻¹

53.9

Lettuce
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)

40.8

Apis mellifera

Moderate

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

Apis mellifera

Moderate

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)

3.5% Mortality at dose 3852 g ha⁻¹

Chrysoperla carnea

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

> 3852

Aphidius rhopalosiphi

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

> 3852

Typhlodromus pyri

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)

2.86

Oncorhynchus mykiss

Moderate

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

0.46

Oncorhynchus mykiss

Moderate

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

4.06

Danio rerio EC₅₀ Embryo

Moderate

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

1.02

Daphnia magna

Moderate

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

0.36

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)

1.0

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)

0.0154

Lemna gibba

Moderate

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

0.155

Myriophyllum spicatum

Moderate

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

18.1

Anabaena flos-aquae

Low

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)

> 5000

Rat

Low

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

2000

Rabbit

Mammals - Inhalation LC₅₀ (mg l⁻¹)

> 4.79

Rat 4 hr (nose only)

Other Mammal toxicity endpoints

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

0.05

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)

0.05

Dermal penetration studies (%)

2.5-2.8

concentration dependent

Dangerous Substances Directive 76/464

Exposure Routes

Public

Very small risk of exposure of bystanders via drift

Occupational

No unacceptable risks to operators or other workers identified

MRLs

European

EU MRL pesticide database

Great Britain

GB MRL Register

Notes

Drinking Water Standards

Drinking Water MAC (μg l⁻¹)

0.1

EU Dir 89/778/EC limit; Calc MAC=50 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

Eye irritant

Phototoxicant

No data found

General human health issues

Bioaccumulates
Potential liver, kidney & spleen toxicant
US EPA - likely to be human carcinogen

Handling issues

Property

Value and interpretation

General

Not oxidising
Classified as explosive category E
Not expected to auto-ignite; Not highly flammable
IMDG Transport Hazard Class 9

CLP classification 2013

Health: H317
Environment: H400, H410, H411, H413

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

TRANSLATIONS

Language

Name

English

oryzalin

French

oryzalin

German

Oryzalin

Danish

oryzalin

Italian

oryzalin

Spanish

orizalina

Greek

Polish

oryzalina

Swedish

Hungarian

Dutch

Norwegian

Record last updated:	09/04/2025
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