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Azamethiphos (Ref: GCA 18809)
Last updated: 27/04/2021
(Also known as: OMS 1825)

SUMMARY
Azamethiphos is an organophosphate used as an insecticide and as an antiparasitic agent for veterinary use. It does not have EU approval for use. It is highly soluble in water, volatile and not expected to leach to groundwater. Not a great deal is known about its environmental persistence. It is modertaley toxic to mammals and not expected to bioaccumulate. It is a mutagen, neurotoxicant and an acetyl cholinesterase inhibitor. Azamethiphos is highly toxic to birds and aquatic invertebrates and moderately toxic to fish.
GENERAL INFORMATION
Description
Used in fish farming to control external parasites on Atlantic Salmon and for parasite control on other animals
Availability status
Current
Introduction & key dates
1970
Examples of species treated
Salmon; Dogs; cats
Chemical structure
Isomerism
-
Chemical formula
C₉H₁₀ClN₂O₅PS
Canonical SMILES
COP(=O)(OC)SCN1C2=NC=C(C=C2OC1=O)Cl
Isomeric SMILES
No data
International Chemical Identifier key (InChIKey)
VNKBTWQZTQIWDV-UHFFFAOYSA-N
International Chemical Identifier (InChI)
InChI=1S/C9H10ClN2O5PS/c1-15-18(14,16-2)19-5-12-8-7(17-9(12)13)3-6(10)4-11-8/h3-4H,5H2,1-2H3
2D structure diagram/image available?
Yes
General status
Veterinary substance type
Antiparasitic
Substance group
Organophosphate
Minimum active substance purity
>95%
Known relevant impurities
-
Substance origin
Synthetic
Mode of action
Contact and stomach action, rapid knockdown. Acetylcholinesterase (AChE) inhibitor.
Molecular targets
[Cholinesterase, inhibitor]
CAS RN
35575-96-3
EC number
252-626-0
CIPAC number
8022
US EPA chemical code
129101
PubChem CID
71482
ATCvet Code
QP53AF17
Therapeutic Class
Antiparasitic products, insecticides & repellents: Ecoparasiticides, insecticides & repellents
Controlled Drug?
No
Regulation 37/2010 MRL Classification
Allowed substance (Table 1: Salmonidae)
Molecular mass
324.68
PIN (Preferred Identification Name)
S-[(6-chloro-2-oxo-1,3-oxazolo[4,5-b]pyridin-3(2H)-yl)methyl] O,O-dimethyl phosphorothioate
IUPAC name
S-6-chloro-2,3-dihydro-2-oxo-1,3-oxazolo[4,5-b]pyridin-3-ylmethyl O,O-dimethyl phosphorothioate
CAS name
S-[(6-chloro-2-oxooxazolo[4,5-b]pyridin-3(2H)-yl)methyl] O,O-dimethyl phosphorothioate
Other status information
PAN Bad Actor
Relevant Environmental Water Quality Standards
UK non-statutory standard for protection of freshwater and saltwater aquatic life 0.02 µg l⁻¹ as annual average, 0.05 as max acceptable conc.
Physical state
Colourless to grey cystalline solid
Formulations
Property
Product
Manufacturer
Authorisation Route
UK Legal Class
Example products using this active
Salmosan Powder for Suspension for Fish Treatment Fish Vet Group UK National authorisation Prescription only medicine to be authorised by a veterinarian (POM-V)
Formulation and application details
Often supplied as a wettable powders, direct use bait formulations and as bath additives
ENVIRONMENTAL FATE
Property
Value
Source; quality score; and other information
Interpretation
Solubility - In water at 20 °C (mg l⁻¹)
1100
E3 E = Manufacturers safety data sheets
3 = Unverified data of known source
High
Solubility - In organic solvents at 20 °C (mg l⁻¹)
610000
L3 L = Pesticide manuals and hard copy reference books / other sources
3 = Unverified data of known source
Dichloromethane
-
130000
L3 L = Pesticide manuals and hard copy reference books / other sources
3 = Unverified data of known source
Benzene
-
100000
L3 L = Pesticide manuals and hard copy reference books / other sources
3 = Unverified data of known source
Methanol
-
5800
L3 L = Pesticide manuals and hard copy reference books / other sources
3 = Unverified data of known source
n-Octanol
-
Melting point (°C)
89
L3 L = Pesticide manuals and hard copy reference books / other sources
3 = Unverified data of known source
-
Boiling point (°C)
Decomposes before boiling
Q3 Q = Miscellaneous internet resources
3 = Unverified data of known source
-
Degradation point (°C)
- - -
Flashpoint (°C)
150
L3 L = Pesticide manuals and hard copy reference books / other sources
3 = Unverified data of known source
-
Octanol-water partition coefficient at pH 7, 20 °C
P
1.12 X 1001 Calculated -
Log P
1.05
L3 L = Pesticide manuals and hard copy reference books / other sources
3 = Unverified data of known source
Low
Bulk density (g ml⁻¹)
1.6
L3 L = Pesticide manuals and hard copy reference books / other sources
3 = Unverified data of known source
-
Dissociation constant pKa) at 25 °C
- - -
-
Vapour pressure at 20 °C (mPa)
0.0049
E3 E = Manufacturers safety data sheets
3 = Unverified data of known source
Low volatility
Henry's law constant at 25 °C (Pa m³ mol⁻¹)
1.45 X 10-06
L3 L = Pesticide manuals and hard copy reference books / other sources
3 = Unverified data of known source
Non-volatile
Maximum UV-vis absorption L mol⁻¹ cm⁻¹
- - -
Surface tension (mN m⁻¹)
- - -
Refractive Index
- - -
Degradation
Property
Value
Source; quality score; and other information
Interpretation
Soil degradation (days) (aerobic)
DT₅₀ (typical)
0.25
L3 L = Pesticide manuals and hard copy reference books / other sources
3 = Unverified data of known source
Non-persistent
DT₅₀ (lab at 20 °C)
- - -
DT₅₀ (field)
- - -
DT₉₀ (lab at 20 °C)
- - -
DT₉₀ (field)
- - -
Note
Best available data, Industry data DT₅₀ in loamy sand circa 6 hours (E3)
Manure DT₅₀ (days)
- - -
Aqueous photolysis DT₅₀ (days) at pH 7
Value
- - -
Note
-
Aqueous hydrolysis DT₅₀ (days) at 20 °C and pH 7
Value
11
L3 L = Pesticide manuals and hard copy reference books / other sources
3 = Unverified data of known source
Non-persistent
Note
pH sensitive ranging from 33 days at pH 5 to 4.3 hrs at pH 9
Water-sediment DT₅₀ (days)
- - -
Water phase only DT₅₀ (days)
- - -
Soil adsorption and mobility
Property
Value
Source; quality score; and other information
Interpretation
Linear
Kd
-
S1 S = Expert judgement
1 = Estimated data with little or no verification
Mobile
Koc
25
Notes and range
Estimated
Freundlich
Kf
- - -
Kfoc
-
1/n
-
Notes and range
-
pH sensitivity
-
Fate indices
Property
Value
Source; quality score; and other information
Interpretation
GUS leaching potential index
-1.57 Calculated Low leachability
ECOTOXICOLOGY
Property
Value
Source; quality score; and other information
Interpretation
Bio-concentration factor
BCF (l kg⁻¹)
1.56
Q2 Q = Miscellaneous internet resources
2 = Unverified data of unknown source
Estimated
Low potential
CT₅₀ (days)
Not available -
Mammals - Acute oral LD₅₀ (mg kg⁻¹)
1180
L3 L = Pesticide manuals and hard copy reference books / other sources
3 = Unverified data of known source
Rat
Moderate
Mammals - Short term dietary NOEL
(mg kg⁻¹)
2
L3 L = Pesticide manuals and hard copy reference books / other sources
3 = Unverified data of known source
Rat
High
(ppm diet)
20 -
Mammals - Chronic 21d NOAEL (mg kg⁻¹ bw d⁻¹)
- - -
Birds - Acute LD₅₀ (mg kg⁻¹)
> 30.2
L3 L = Pesticide manuals and hard copy reference books / other sources
3 = Unverified data of known source
Colinus virginianus
High
Birds - Short term dietary (LC₅₀/LD₅₀)
- - -
Birds - Chronic 21d NOEL (mg kg⁻¹ bw d⁻¹)
- - -
Fish - Acute 96 hour LC₅₀ (mg l⁻¹)
> 0.115
L3 L = Pesticide manuals and hard copy reference books / other sources
3 = Unverified data of known source
Oncorhynchus mykiss
Moderate
Fish - Chronic 21 day NOEC (mg l⁻¹)
- - -
Aquatic invertebrates - Acute 48 hour EC₅₀ (mg l⁻¹)
0.00067
L3 L = Pesticide manuals and hard copy reference books / other sources
3 = Unverified data of known source
Daphnia magna
High
Aquatic invertebrates - Chronic 21 day NOEC (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)
- - -
Non-target plants
- - -
- - -
Algae - Acute 72 hour EC₅₀, growth (mg l⁻¹)
- - -
Algae - Chronic 96 hour NOEC, growth (mg l⁻¹)
- - -
Honeybees (Apis spp.)
Contact acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)
> 0.10
L3 L = Pesticide manuals and hard copy reference books / other sources
3 = Unverified data of known source
High
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)
- - -
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)
- - -
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
- - -
Other arthropod (2)
LR₅₀ g ha⁻¹
- - -
% Effect
- - -
Soil micro-organisms
- - -
Mesocosm study data
NOEAEC mg l⁻¹
- - -
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)
1180
L3 L = Pesticide manuals and hard copy reference books / other sources
3 = Unverified data of known source
Rat
Moderate
Mammals - Dermal LD₅₀ (mg kg⁻¹ body weight)
2150
L3 L = Pesticide manuals and hard copy reference books / other sources
3 = Unverified data of known source
Rat
-
Mammals - Inhalation LC₅₀ (mg l⁻¹)
> 0.56
L3 L = Pesticide manuals and hard copy reference books / other sources
3 = Unverified data of known source
Rat
-
Other Mammal toxicity endpoints
- - -
ADI - Acceptable Daily Intake (mg kg⁻¹ bw day⁻¹)
0.003
B5 B = UK CRD and ACP evaluation documents / and other Defra (UK) documents (click here )
5 = Verified data used for regulatory purposes
UK ACP 2001
-
ARfD - Acute Reference Dose (mg kg⁻¹ bw day⁻¹)
0.01
B5 B = UK CRD and ACP evaluation documents / and other Defra (UK) documents (click here )
5 = Verified data used for regulatory purposes
UK ACP 2001
-
AAOEL - Acute Acceptable Operator Exposure Level (mg kg⁻¹ bw day⁻¹)
- - -
AOEL - Acceptable Operator Exposure Level - Systemic (mg kg⁻¹ bw day⁻¹)
0.1
B5 B = UK CRD and ACP evaluation documents / and other Defra (UK) documents (click here )
5 = Verified data used for regulatory purposes
UK ACP 2001 ST
-
Dermal penetration studies (%)
- - -
Dangerous Substances Directive 76/464
List I; List II - -
Exposure Routes
Public
-
Occupational
-
Elimination route and rate
For rats azamethiphos is excreted via faeces, urine & in expelled air. For fish adsorption after topical application is slow and low. Excretion is rapid in all species.
A4 A = EU regulatory and evaluation data as published by EC, EFSA (RAR, DAR & Conclusion dossiers), EMA (e.g. EU Annex III PIC DGD) (EU - Pesticides database; EFSA Scientific Publications )
4 = Verified data
-
Health issues
Specific human health issues
Carcinogen
Genotoxic
Endocrine disruptor
No data found
A3 A = Chromosome aberration (EFSA database)
3 = Negative
;
B3 B = DNA damage/repair (EFSA database)
3 = Negative
;
C3 C = Gene mutation (EFSA database)
3 = Negative
;
D0 D = Genome mutation (EFSA database)
0 = No data
;
E1 E = Unspecified genotoxicity type (miscellaneous data source)
1 = Positive
XNo, known not to cause a problem
Reproduction / development effects Acetyl cholinesterase inhibitor Neurotoxicant
No data found
Yes, known to cause a problem
Yes, known to cause a problem
Respiratory tract irritant Skin irritant Skin sensitiser
No data found
XNo, known not to cause a problem
?Possibly, status not identified
Eye irritant Phototoxicant  
Yes, known to cause a problem
No data found  
General human health issues
Mutagenic potential
Handling issues
Property
Value and interpretation
General
IMDG Transport Code is 6.1
CLP classification 2013
Health: H302, H317, H332
Environment: H400, H410
EC Risk Classification
Xn - Harmful: R22
Xi - Irritant: R36
EC Safety Classification
S26
WHO Classification
II (Moderately hazardous)
UN Number
2783
Waste disposal & packaging
-
TRANSLATIONS
Language
Name
English
azamethiphos
French
azametiphos
German
Azamethiphos
Danish
azamethiphos
Italian
azametifos
Spanish
azametifos
Greek
-
Polish
azametifos
Swedish
azametifos
Hungarian
-
Dutch
azamethifos

Record last updated: 27/04/2021
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