Abamectin (Ref: MK 936)

Abamectin (Ref: MK 936)	Last updated: 14/11/2024
(Also known as: avermectin; abermectine; L676; A121151; AVM; C-076; MK-936)

SUMMARY

Abamectin is a bacterium-derived pesticide that is approved for use in many countries. It has a low aqueous solubility and is not volatile. It does not tend to be persistent in the environment. It has a highly oral toxicity to mammals and there is some evidence that it may induce negative reproduction effects at high doses. It exhibits high or medium toxicity to most fauna and flora.

GENERAL INFORMATION

Description

A macrocyclic lactone anthelmintic drug often formulated with derquantel

Availability status

Current

Introduction & key dates

1967, avermectins discovered; 1985, first introduced by American Cyanamid, Shell

Examples of veterinary uses

Used to treat certain internal parasites. Effective against a broad spectrum of adult and laval stages of nematode and arthropod parasites

Examples of species treated

Sheep; Cattle; Horses

Approval status

VMR 2013/2033 approval status (GB/UK)

Approved

EU Regulatory approval status

Approved

Chemical structure

Isomerism

A chiral molecule - abamectin is a mixture containing ~80% avermectin B1a and ~20% avermectin B1b.

Chemical formula

C₄₈H₇₂O₁₄ + C₄₇H₇₀O₁₄

Canonical SMILES

CCC(C)C1C(C=CC2(O1)CC3CC(O2)CC=C(C(C(C=CC=C4COC5C4(C(C=C(C5O)C)C(=O)O3)O)C)OC6CC(C(C(O6)C)OC7CC(C(C(O7)C)O)OC)OC)C)C.CC1C=CC=C2COC3C2(C(C=C(C3O)C)C(=O)OC4CC(CC=C(C1OC5CC(C(C(O5)C)OC6CC(C(C(O6)C)O)OC)OC)C)OC7(C4)C=CC(C(O7)C(C)C)C)O

Isomeric SMILES

CCC(C)[C@@H]1[C@H](C=C[C@@]2(O1)C[C@@H]3C[C@H](O2)C/C=C(/[C@H]([C@H](/C=C/C=C/4\CO[C@H]5[C@@]4([C@@H](C=C([C@H]5O)C)C(=O)O3)O)C)O[C@H]6C[C@@H]([C@H]([C@@H](O6)C)O[C@H]7C[C@@H]([C@H]([C@@H](O7)C)O)OC)OC)\C)C.C[C@H]1/C=C/C=C/2\CO[C@H]3[C@@]2([C@@H](C=C([C@H]3O)C)C(=O)O[C@H]4C[C@@H](C/C=C(/[C@H]1O[C@H]5C[C@@H]([C@H]([C@@H](O5)C)O[C@H]6C[C@@H]([C@H]([C@@H](O6)C)O)OC)OC)\C)O[C@]7(C4)C=C[C@@H]([C@H](O7)C(C)C)C)O

International Chemical Identifier key (InChIKey)

IBSREHMXUMOFBB-MVGRHBATSA-N

International Chemical Identifier (InChI)

InChI=1S/C48H72O14.C47H70O14/c1-11-25(2)43-28(5)17-18-47(62-43)23-34-20-33(61-47)16-15-27(4)42(26(3)13-12-14-32-24-55-45-40(49)29(6)19-35(46(51)58-34)48(32,45)52)59-39-22-37(54-10)44(31(8)57-39)60-38-21-36(53-9)41(50)30(7)56-38;1-24(2)41-27(5)16-17-46(61-41)22-33-19-32(60-46)15-14-26(4)42(25(3)12-11-13-31-23-54-44-39(48)28(6)18-34(45(50)57-33)47(31,44)51)58-38-21-36(53-10)43(30(8)56-38)59-37-20-35(52-9)40(49)29(7)55-37/h12-15,17-19,25-26,28,30-31,33-45,49-50,52H,11,16,20-24H2,1-10H3;11-14,16-18,24-25,27,29-30,32-44,48-49,51H,15,19-23H2,1-10H3/b13-12+,27-15+,32-14+;12-11+,26-14+,31-13+/t25-,26+,28+,30+,31+,33-,34+,35+,36+,37+,38+,39+,40-,41+,42+,43-,44+,45-,47-,48-;25-,27-,29-,30-,32+,33-,34-,35-,36-,37-,38-,39+,40-,41+,42-,43-,44+,46+,47+/m10/s1

2D structure diagram/image available?

Yes

General status

Veterinary substance type

Antiparasitic, Anthelmintic

Substance groups

Micro-organism derived insecticide; Micro-organism derived acaricide; Micro-organism derived nematicide; Avermectin insecticide; Avermectin nematicide; Avermectin acaricide

Minimum active substance purity

850 abamectin; 800 B1a; 200 B1b as g/Kg

Known relevant impurities

EU dossier - none declared

Substance origin

Natural

Mode of action

Contact and stomach action with limited systemic activity, blocks electrical activity in nerves and muscles of pest. Glutamate-gated chloride channel (GluCl) allosteric modulator.

Molecular targets

[Glycine receptor subunit alpha-3, Agonist], [Gamma-aminobutyric-acid (GABA) receptor subunit beta-3, Agonist]

CAS RN

71751-41-2

Alternative/old CAS RN

65195-55-3 (B1a); 65195-56-4 (B1b)

EC number

265-610-3 / 265-611-9

CIPAC number

495

US EPA chemical code

122804

PubChem CID

6435890

Therapeutic Class

Antiparasitic products, insecticides & repellents: Avermectins

ATCvet Code

QP54AA02

Controlled Drug?

Regulation 37/2010 MRL Classification

Allowed substance (Table 1: Bovine, Ovine)

Molecular mass

866.6

PIN (Preferred Identification Name)

IUPAC name

(1'R,2R,3S,4'S,6S,8'R,10'E,12'S,13'S,14'E,16'E,20'R,21'R,24'S)-2-butan-2-yl-21',24'-dihydroxy-12'-[(2R,4S,5S,6S)-5-[(2S,4S,5S,6S)-5-hydroxy-4-methoxy-6-methyloxan-2-yl]oxy-4-methoxy-6-methyloxan-2-yl]oxy-3,11',13',22'-tetramethylspiro[2,3-dihydropyran-6,6'-3,7,19-trioxatetracyclo[15.6.1.14,8.020,24]pentacosa-10,14,16,22-tetraene]-2'-one;(1'R,2R,3S,4'S,6S,8'R,10'E,12'S,13'S,14'E,16'E,20'R,21'R,24'S)-21',24'-dihydroxy-12'-[(2R,4S,5S,6S)-5-[(2S,4S,5S,6S)-5-hydroxy-4-methoxy-6-methyloxan-2-yl]oxy-4-methoxy-6-methyloxan-2-yl]oxy-3,11',13',22'-tetramethyl-2-propan-2-ylspiro[2,3-dihydropyran-6,6'-3,7,19-trioxatetracyclo[15.6.1.14,8.020,24]pentacosa-10,14,16,22-tetraene]-2'-one

CAS name

avermectin B1

Other status information

Relevant Environmental Water Quality Standards

UK Environment Agency non-statutory guideline EQS: Freshwater annual average 0.01 µg l⁻¹, maximum acceptable conc 0.03 µg l⁻¹. Saltwater annual average 0.003 µg l⁻¹, maximum acceptable conc 0.01 µg l⁻¹

Physical state

Fine white powder

Related substances & organisms

derquantel

Formulations

Property

Product

Manufacturer

Authorisation Route

Legal Class (GB/UK)

Example products (past and present) using this active

Startect Dual Active Oral Solution for Sheep

Zoetis UK Limited

GB National authorisation

Prescription only medicine to be authorised by a registered, qualified person (POM-VPS)

Formulation and application details

Usually supplied as a solution for oral administration

ENVIRONMENTAL FATE

Property

Value

Source; quality score; and other information

Interpretation

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

0.020

Low

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

23000

Toluene

72000

Acetone

160000

Ethyl acetate

83000

Octanol

Melting point (°C)

161.8

Boiling point (°C)

Decomposes before boiling

Degradation point (°C)

Decomposes during melting

Flashpoint (°C)

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

2.51 X 10⁰⁴

Calculated

Log P

4.4

High

Fat solubility of residues

Solubility

Soluble

Data type

Regulatory data

Density (g ml⁻¹)

1.18

Dissociation constant pKa) at 25 °C

Not applicable

No dissociation

Vapour pressure at 20 °C (mPa)

0.0037

Low volatility

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

2.70 X 10^-03

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 soln: 245nm=32549, 255nm=18983
Acidic soln: 245nm=34515, 255nm=20977
Basic soln: 245nm=29551

Surface tension (mN m⁻¹)

52.4

at 20 °C 96.7%

Refractive Index

Environmental release

Degradation

Property

Value

Source; quality score; and other information

Interpretation

Soil degradation (days) (aerobic)

DT₅₀ (typical)

25.3

Non-persistent

DT₅₀ (lab at 20 °C)

25.3

Non-persistent

DT₅₀ (field)

1.0

Non-persistent

DT₉₀ (lab at 20 °C)

52.7

Moderately persistent

DT₉₀ (field)

1.0

Note

EU 2019 dossier lab studies DT₅₀ (normalised) range 15.9-57.6 days, DT₉₀ (measured) range 52.7-191 days, Soils=11; field studies (2016) DT₅₀ range 1-1.8 days; Other lab studies DT₅₀ range 20-40 days for avermectin B1a

Manure DT₅₀ (days)

sheep faeces

Aqueous photolysis DT₅₀ (days) at pH 7

Value

1.5

Moderately fast

Note

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

Value

Stable

Note

Stable at pH 4 to pH 7

Water-sediment DT₅₀ (days)

Moderately fast

Water phase only DT₅₀ (days)

2.4

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)

K_oc (mL g⁻¹)

Notes and range

Freundlich

K_f (mL g⁻¹)

151

Non-mobile

K_foc (mL g⁻¹)

6631

¹/_n

0.971

Notes and range

EU 2019 dossier K_f range 76.8-334 mL g⁻¹, K_foc range 5701-7893 mL g⁻¹, ¹/_n range 0.950-1.013, Soils=5

pH sensitivity

Fate indices

Property

Value

Source; quality score; and other information

Interpretation

GUS leaching potential index

0.00

Calculated

Low leachability

Bio-concentration factor

BCF (l kg⁻¹)

Whole fish

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

4-oxo-avermectin B1a (Ref: NOA 426289)

Major fraction

0.120

8-carboxy-4-hydroxy avermectin B1a

Minor fraction

0.09

8a-hydroxyavermectin B1a (Ref: NOA 448112)

Major fraction

0.220

8a-oxo-avermectin B1a (Ref: NOA 448111)

Major fraction

0.170

4,8a-dihydroxy-avermectin B1a (Ref: NOA 457464)

Minor fraction

0.099

8a-oxo-4-hydroxy-avermectin B1a (Ref: NOA 457465)

Minor fraction

0.099

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)

8a-hydroxyavermectin B1a (Ref: NOA 448112)

8a-oxo-avermectin B1a (Ref: NOA 448111)

4-oxo-avermectin B1a (Ref: NOA 426289)

4,8a-dihydroxy-avermectin B1a (Ref: NOA 457464)

8-carboxy-4-hydroxy avermectin B1a

Other known metabolites

Metabolite name and reference

Aliases

Formation medium / Rate

Estimated maximum occurrence fraction

3"-desmethyl-avermectin B1a

Rat (Liver)

[8,9-Z]-avermnectin B1a (Ref: NOA427011)

Aqueous photolysis

0.082

24-hydroxymethyl-avermectin B1a

Rat (Liver)

ECOTOXICOLOGY

Terrestrial ecotoxicology

Property

Value

Source; quality score; and other information

Interpretation

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

8.7

Rat

High

Mammals - Short term dietary NOEL

(mg kg⁻¹)

4.5

Rat

High

(ppm diet)

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

0.4

Rat Reproductive NOAEL

High

Birds - Acute LD₅₀ (mg kg⁻¹)

Anas platyrhynchos

High

Birds - Short term dietary (LC₅₀/LD₅₀)

48.6 mg kg bw⁻¹ day⁻¹

Anas platyrhynchos

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

0.7

Colinus virginianus NOED

High

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

Eisenia foetida

Moderate

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

0.72

Eisenia foetida 10% OM

Moderate

Soil micro-organisms

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

Dose: 0.347 mg kg⁻¹ 28 Day

Collembola

Acute LC₅₀ (mg kg⁻¹)

Chronic NOEC (mg kg⁻¹)

Non-target plants

Honeybees (Apis spp.)

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

0.001

Apis mellifera

High

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

> 0.004

Apis mellifera 24 hr

High

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

0.00184

Apis mellifera

Notes

[The residual time to 25% mortality (RT25) value for honeybees is 7.96 hrs (ranging 4-60 hrs depending on crop amd application rate) - USEPA data]

Bumblebees (Bombus spp.)

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

0.14

Bombus terrestris 72 hr

High

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

0.07

Bombus terrestris 72 hr

High

Mason bees (Osmia spp.)

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

0.033

Osmia lignaria

High

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

> 0.0003

Osmia excavata

High

Other bee species (1)

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

3.6

Melipona quadrifasciata

Moderate

Mode of exposure

Contact

Other bee species (2)

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

0.015

Melipona quadrifasciata

High

Mode of exposure

Oral

Beneficial insects (Ladybirds)

Beneficial insects (Lacewings)

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

> 42.0

Aphidius rhopalosiphi

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

0.09

Typhlodromus pyri

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

> 91.1

Poecilus cupreus

Aquatic ecotoxicology

Property

Value

Source; quality score; and other information

Interpretation

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

0.0087

Oncorhynchus mykiss

High

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

0.52

Oncorhynchus mykiss

Moderate

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

0.106

Danio rerio

Moderate

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

0.00056

Daphnia pulex

High

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

0.00001

Daphnia magna

High

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)

0.0027

Chironomus xanthus

High

Sediment dwelling organisms - Chronic 28 day NOEC, static, water (mg l⁻¹)

0.000081

Chironomus riparius

High

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

0.0033

Chironomus riparius

High

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

3.9

Lemna gibba

Moderate

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

> 1.59

Pseudokirchneriella subcapitata

Moderate

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

21.3

Unknown species 72 hr EC₅₀

Low

Mesocosm study data

NOEAEC mg l⁻¹

0.0018

single application

NOEAEC mg l⁻¹

Marine bivalves – Acute LC₅₀, sperm motility (mg l⁻¹)

1.017

Crassostrea gigas

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)

8.7

Rat

High

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

1914

Rat

Mammals - Inhalation LC₅₀ (mg l⁻¹)

> 0.021

Rat 4 hr (nose only)

Other Mammal toxicity endpoints

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

0.0012

Dog SF=100

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

0.0012

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

0.0012

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

0.0012

Dog SF=100

Dermal penetration studies (%)

3-4

concentration dependent

Dangerous Substances Directive 76/464

Exposure Routes

Public

Bystander risk acceptable for proposed uses Source EU dossier Unlikely via dermal contact
Source: US EPA

Occupational

Possible dermal exposure and absorption
Source: US EPA

Mammalian dose elimination route and rate

Eliminated mainly as the unchanged drug in the faeces

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

Evidence of teratogenicity
Potential reproduction effects at high doses
May cause tremors, ataxia and mydriasis, liver, absent or decreased pupil reflex

Handling issues

Property

Value and interpretation

General

Not expected to auto-ignite; Not highly flammable
Fight fires using dry chemicals, foam or carbon dioxide
IMDG Transport Hazard Class 6.1
Not explosive or oxidising

CLP classification 2013

Health: H300, H330, H361d, H372
Environment: H400, H410

WHO Classification

Ib (Highly hazardous)

UN Number

UN2811

Waste disposal & packaging

Packaging Group II (moderate danger)

Shelf-life, storage, stability and reactivity

Limited shelf-life. Store at -20 DegC

TRANSLATIONS

Language

Name

English

abamectin

French

abamectine

German

Abamectin

Danish

abamectin

Italian

abamectina

Spanish

abamectina

Greek

Polish

abamektyna

Swedish

abamectin

Hungarian

abamectin

Dutch

abamectin

Norwegian

Record last updated:	14/11/2024
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