Nemadectin	Last updated: 23/02/2026
(Also known as: S541A; LL-F28249 aplha)

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Hazard alerts

The following Pesticide Hazard Tricolour (PHT) 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. The alerts for Highly Hazardous Pesticides (HHPs) are based on applying the FAO/WHO (Type 1) and the PAN (Type II) criteria to PPDB data. Further details on the HHP indicators are given in the tables below. Neither the PHT nor the HHP hazard alerts take account of usage patterns or exposure, thus they do not represent risk.

PHT: Environmental fate	PHT: Ecotoxicity	PHT: Human health	Highly Hazardous Pesticide

GENERAL INFORMATION

Description	A naturally occurring substance with broad-spectrum antiparasitic properties
Example pests controlled	Shown to be efficacy against the natural canine-infecting helminth parasitic worms and ivermectin-resistant barber's pole worm (Haemonchus contortus) in sheep
Example applications	Dogs; Sheep
Efficacy & activity	-
Appearance and life cycle	-
Taxonomic classification	-

GB regulatory status

GB COPR regulatory status	Not applicable
Date COPR inclusion expires	Not applicable
GB LERAP status	No UK approval for use as a plant protection agent

EC Regulation 1107/2009 (repealing 91/414)

EC Regulation 1107/2009 status	Not applicable
Dossier rapporteur/co-rapporteur	Not applicable
Date EC 1107/2009 inclusion expires	Not applicable
EU Candidate for substitution (CfS)	Not applicable
Listed in EU database	No
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	Japan

Chemical structure

Isomerism	Nemadectin exhibits extensive stereoisomerism, including both optical and geometrical isomerism, due to its large, complex ring system and multiple stereocentres.
Chemical formula	C₃₆H₅₂O₈
Canonical SMILES	CC1CC(=CCC2CC(CC3(O2)CC(C(C(O3)C(=CC(C)C)C)C)O)OC(=O)C4C=C(C(C5C4(C(=CC=C1)CO5)O)O)C)C
Isomeric SMILES	C[C@@H]\1C/C(=C/C[C@@H]2C[C@@H](C[C@@]3(O2)C[C@@H]([C@@H]([C@H](O3)/C(=C/C(C)C)/C)C)O)OC(=O)[C@@H]4C=C([C@H]([C@@H]5[C@]4(/C(=C/C=C1)/CO5)O)O)C)/C
International Chemical Identifier key (InChIKey)	YNFMRVVYUVPIAN-AQUURSMBSA-N
International Chemical Identifier (InChI)	InChI=1S/C36H52O8/c1-20(2)13-24(6)32-25(7)30(37)18-35(44-32)17-28-16-27(43-35)12-11-22(4)14-21(3)9-8-10-26-19-41-33-31(38)23(5)15-29(34(39)42-28)36(26,33)40/h8-11,13,15,20-21,25,27-33,37-38,40H,12,14,16-19H2,1-7H3/b9-8+,22-11+,24-13+,26-10+/t21-,25-,27+,28-,29-,30-,31+,32+,33+,35-,36+/m0/s1
2D structure diagram/image available?	Yes

Cambridge Crystallographic Data Centre diagrams

Common Name	Relationship	Link
nemadectin	-

General status

Biopesticide type		Nematicide; Insecticide; Antibiotic; Veterinary substance
Substance groups		Micro-organism derived substance
Minimum active substance purity		-
Known relevant impurities		-
Substance origin		Natural
Mode of action		-
Substance source		Nemadectin is a natural substance produced by Streptomyces microflavus and Streptomyces griseus
Uses		Pest management
Target pests		Shown to be efficacy against the natural canine-infecting helminth parasitic worms and ivermectin-resistant barber's pole worm (Haemonchus contortus) in sheep
Target host		Dogs; Sheep
Farming system suitability		-
CAS RN		102130-84-7
EC number		-
CIPAC number		-
US EPA chemical code		-
PubChem CID		-
Molecular mass		612.80
PIN (Preferred Identification Name)		-
IUPAC name		(1'R,2R,4S,4'S,5S,6S,8'R,10'E,13'R,14'E,16'E,20'R,21'R,24'S)-4,21',24'-trihydroxy-5,11',13',22'-tetramethyl-6-[(2E)-4-methyl-2-penten-2-yl]-3,4,5,6-tetrahydro-2'H-spiro[pyran-2,6'-[3,7,19]trioxatetracyclo[15.6.1.1~4,8~.0~20,24~]pentacosa[10,14,16,22]tetraen]-2'-one
CAS name		-
Global Governance status: Listed (✓) under		UK Poisons List Order 1972 Rotterdam Convention Montreal Protocol XNo The Poisons List Order 1972 XNo Rotterdam Convention XNo Montreal Protocol Stockholm Convention OSPAR EU Water Framework Directive XNo Stockholm Convention XNo OSPAR XNo EU Water Framework Directive
Relevant Environmental Water Quality Standards		-
Forever chemical		-
Highly Hazardous Pesticide (HHP)	Type I	-
	Type II	-
Other status information		-
Herbicide Resistance Class (HRAC MoA class)		Not applicable
Herbicide Resistance Class (WSSA MoA class)		Not applicable
Insecticide Resistance Class (IRAC MoA class)		-
Fungicide Resistance Class (FRAC MOA class)		Not applicable
Examples of recorded resistance		-
Physical state		White solid

Commercial

Property	Value
Availability status	Current
Introduction & key dates	1980s, first isolated; 1990s, use in research; 2013, not approved UK
Example manufacturers & suppliers of products using this active now or historically	American Cyanamid
Example products using this active	Never fully commercialised
Formulation and application details	Usually supplied in a solid formulation
Commercial production	Nemadectin is commercially produced through a fermentation process using Streptomyces cyaneogriseus subspecies noncyanogenus The production involves cultivating this microorganism under controlled conditions optimised for yield, including nutrient-rich media and precise temperature and pH settings. After fermentation, the compound is extracted and purified for use.
Impact on climate of production and use	As microbial-based products tend to use fermentation-based production processes rather than chemical synthesis, they typically have a lower fossil fuel input in formulation and active ingredient creation, and also have reduced downstream emissions due to biodegradability and minimal soil disruption, their life-cycle GHG emissions are expected to be low. Whilst hard and precise data is not available, broad estimates suggest that typically emissions are likely to be below 5 kg CO₂e/kg.

ENVIRONMENTAL FATE

Property		Value	Source; quality score; and other information	Interpretation
Solubility - In water at 20 °C at pH 7 (mg l⁻¹)		-	-	-
Solubility - In organic solvents at 20 °C (mg l⁻¹)		-	-	-
Melting point (°C)		-	-	-
Boiling point (°C)		-	-	-
Degradation point (°C)		-	-	-
Flashpoint (°C)		-	-	-
Octanol-water partition coefficient at pH 7, 20 °C	P	-	-	-
	Log P	-	-	-
Fat solubility of residues	Solubility	-	-	-
	Data type	-	-	-
Density (g ml⁻¹)		-	-	-
Dissociation constant pKa) at 25 °C		-	-	-
		-
Vapour pressure at 20 °C (mPa)		-	-	-
Henry's law constant at 25 °C (Pa m³ mol⁻¹)		-	-	-
Volatilisation as max % of applied dose lost	From plant surface	-	-	-
	From soil surface	-	-	-
Maximum UV-vis absorption L mol⁻¹ cm⁻¹		-	-	-
Surface tension (mN m⁻¹)		-	-	-

Degradation

Property		Value	Source; quality score; and other information	Interpretation
General biodegradability		-
Soil degradation (days) (aerobic)	DT₅₀ (typical)	-	-	-
	DT₅₀ (lab at 20 °C)	-	-	-
	DT₅₀ (field)	-	-	-
	DT₉₀ (lab at 20 °C)	-	-	-
	DT₉₀ (field)	-	-	-
	DT₅₀ modelling endpoint	-	-	-
	Note	-
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)		-	-	-
Water phase only DT₅₀ (days)		-	-	-
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	Kd (mL g⁻¹)	-	-	-
	Koc (mL g⁻¹)	-
	Notes and range	-
Freundlich	Kf (mL g⁻¹)	-	-	-
	Kfoc (mL g⁻¹)	-
	1/n	-
	Notes and range	-
pH sensitivity		-

Known metabolites

None

ECOTOXICOLOGY

Terrestrial ecotoxicology

Property		Value	Source; quality score; and other information	Interpretation
Mammals - Acute oral LD₅₀ (mg kg⁻¹)		-	-	-
Mammals - Short Term Oral NOAEL (mg kg⁻¹ bw d⁻¹)		-	-	-
Mammals - Long Term (Chronic) Oral NOAEL (mg kg⁻¹ bw d⁻¹)		-	-	-
Birds - Acute LD₅₀ (mg kg⁻¹)		-	-	-
Birds - Short term dietary LC₅₀ (mg kg⁻¹ bw d⁻¹)		-	-	-
Birds - Chronic 21d NOEL (mg kg⁻¹ bw d⁻¹)		-	-	-
Earthworms - Acute 14 day LC₅₀ (mg kg⁻¹ dw soil)		-	-	-
Earthworms - Chronic NOEC, reproduction (mg kg⁻¹ dw soil)		-	-	-
Soil micro-organisms		-	-	-
Collembola	Acute LC₅₀ (mg kg⁻¹)	-	-	-
	Chronic NOEC (mg kg⁻¹)	-	-	-
Non-target plants	Vegetative vigour ER₅₀ (g ha⁻¹)	-	-	-
	Seedling emergence ER₅₀ (g ha⁻¹)	-	-	-
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)		-	-	-
Beneficial insects (Butterflies)	Contact	-	-	-
	Notes	-
	Oral	-	-	-
	Notes	-

Aquatic ecotoxicology

Property		Value	Source; quality score; and other information	Interpretation
Temperate Freshwater Fish - Acute 96 hour LC₅₀ (mg l⁻¹)		-	-	-
Temperate Freshwater Fish - Chronic 21 day NOEC (mg l⁻¹)		-	-	-
Tropical Freshwater Fish - Acute 96 hour LC₅₀ (mg l⁻¹)		-	-	-
Temperate Freshwater Aquatic invertebrates - Acute 48 hour EC₅₀ (mg l⁻¹)		-	-	-
Temperate Freshwater Aquatic invertebrates - Chronic 21 day NOEC (mg l⁻¹)		-	-	-
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 (free-floating, fonds growth, fresh) - 7 day (mg l⁻¹)		-	-	-
Aquatic plants (rooted, growth rate, fresh) - 14 day (mg l⁻¹)		-	-	-
Algae - Acute (growth rate, fresh; mg l⁻¹)		-	-	-
Algae - Chronic (growth rate, fresh; mg l⁻¹)		-	-	-
Mesocosm study data	NOEAEC mg l⁻¹	-	-	-
	NOEAEC mg l⁻¹	-	-	-
Marine bivalves		-	-	-

Regulatory Threshold Levels (RTLs)

Note: These RTLs have been calculated using the regulatory approach used in the European Union and based on ecotoxocity values in the PPDB.

Species group	RTL	Notes
Mammals	No data	No data for acute and chronic mammals
Birds	No data	No data for acute and chronic birds
Soil organisms	No data	No data for acute and chronic earthworms
Terrestrial plants	No data	No data for non-target plants vegetative vigour and seedling emergence
Pollinators	No data	No data for contact and oral honeybees
Arthropods	No data	No data for parasitic wasps and predatory mites
Fish	No data	No data for temperate acute and chronic fish
Aquatic invertebrates	No data	No data for temperate acute and chronic aquatic invertebrates
Aquatic plants	No data	No data for free-floating plants, rooted plants, acute and chronic algae

HUMAN HEALTH AND PROTECTION

General

Property		Value	Source; quality score; and other information	Interpretation
Threshold of Toxicological Concern (Cramer Class)		-	-	-
Mammals - Acute oral LD₅₀ (mg kg⁻¹)		-	-	-
Mammals - Short Term Oral NOAEL (mg kg⁻¹ bw d⁻¹)		-	-	-
Mammals - Long Term (Chronic) Oral NOAEL (mg kg⁻¹ bw d⁻¹)		-	-	-
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	-
Mammalian dose elimination route and rate		Mainly excreted in the faeces	Q3 Q = Miscellaneous data from online sources 3 = Unverified data of known source	-

Health issues

Specific human health issues (hazard-based)		Carcinogen Genotoxic Endocrine disruptor No data found A0 A = Chromosome aberration (EFSA database) 0 = No data ; B0 B = DNA damage/repair (EFSA database) 0 = No data ; C0 C = Gene mutation (EFSA database) 0 = No data ; D0 D = Genome mutation (EFSA database) 0 = No data ; E0 E = Unspecified genotoxicity type (miscellaneous data source) 0 = No data No data found Reproduction / development effects Acetyl cholinesterase inhibitor Neurotoxicant No data found No data found No data found Respiratory tract irritant Skin irritant Skin sensitiser No data found No data found No data found Eye irritant Phototoxicant   ?Possibly, status not identified No data found
General human health issues		Possible liver toxicant at high doses

Handling issues

Property	Value and interpretation
General	IMDG Transport Hazard Class 6.1
CLP classification 2013	-
WHO Classification	Not listed (Not listed)
UN Number	UN2588
Waste disposal & packaging	Packaging Group III (minor danger)
Shelf-life, storage, stability and reactivity	-

TRANSLATIONS

Language	Name
English	nemadectin
French	nemadectin
German	-
Danish	-
Italian	-
Spanish	nemadectina
Greek	-
Polish	-
Swedish	-
Hungarian	-
Dutch	-
Norwegian	-

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Record last updated:	23/02/2026
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

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