(Also known as: acephate-metabolite; SRA 5172; BAY 71628)
SUMMARY
Methamidophos is an insecticide for the control of sucking and chewing pests. It is highly soluble in water and many organic solvents, and is volatile. It would not normally be expected to be persistent in soil or water systems. Methamidophos is highly toxic to mammals, and is a cholinesterase inhibitor and neurotoxin. It is highly toxic to birds and honeybees, and moderately toxic to most aquatic species 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: Drainflow: Very mobile
Ecotoxicity High alert: Birds acute ecotoxicity: High; Bees acute contact ecotoxicity: High; Bees acute oral ecotoxicity: High
Human health High alert: Mammals acute toxicity: High; Genotoxic; Acetyl cholinesterase inhibitor; Neurotoxicant
GENERAL INFORMATION
Description
An insecticide and acaricide used to control chewing and sucking pests. Also a pesticide transformation product
Broccoli; Brussel sprouts; Cauliflower; Celery; Cotton; Beets; Potatoes; Hops, Vegetables; Corn; Tomatoes; Fruit including pome, stone and citrus fruits
Efficacy & activity
-
Availability status
Current
Introduction & key dates
circa 1972, introduced
GB regulatory status
GB COPR regulatory status
Not approved
Date COPR inclusion expires
Expired
GB LERAP status
No UK approval for use as a pesticide
EC Regulation 1107/2009 (repealing 91/414)
EC Regulation 1107/2009 status
Not approved
Dossier rapporteur/co-rapporteur
Italy
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
A molecule with one chiral centre existing as the D-(+) and L-(-) isomers
Example manufacturers & suppliers of products using this active now or historically
Bayer CropScience
AgroCare
United Phosphorus
Chevron
Mobay
Example products using this active
Tahmabon
Patrole
Pillaron
Monitor
Formulation and application details
Usually supplied as a soluble concentrate
ENVIRONMENTAL FATE
Property
Value
Source; quality score; and other information
Interpretation
Solubility - In water at 20 °C (mg l⁻¹)
200000
K4 K = Research datasets (e.g. Pandora, Demetra; these datasets no longer available). Norman Ecotoxicology database. (click here ) 4 = Verified data
High
Solubility - In organic solvents at 20 °C (mg l⁻¹)
200000
C4 C = AGRITOX dataset. Dataset is no longer available. 4 = Verified data
Acetone
-
1000
C4 C = AGRITOX dataset. Dataset is no longer available. 4 = Verified data
Hexane
-
3500
C4 C = AGRITOX dataset. Dataset is no longer available. 4 = Verified data
Toluene
-
200000
C4 C = AGRITOX dataset. Dataset is no longer available. 4 = Verified data
Dichloromethane
-
Melting point (°C)
45
L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source
-
Boiling point (°C)
Decomposes before boiling
L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source
-
Degradation point (°C)
160
L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source
-
Flashpoint (°C)
212
Q2 Q = Miscellaneous data from online sources 2 = Unverified data of unknown source
-
Octanol-water partition coefficient at pH 7, 20 °C
P
1.62 X 10-01
Calculated
-
Log P
-0.79
H4 H = The US ARS pesticide properties database. Dataset is no longer available. 4 = Verified data
Low
Fat solubility of residues
Solubility
-
-
-
Data type
-
-
-
Density (g ml⁻¹)
1.27
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)
2.3
L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source
Low volatility. If applied directly to plants or soil, drift is a concern & mitigation is advisable
Henry's law constant at 25 °C (Pa m³ mol⁻¹)
1.60 X 10-06
L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source
Non-volatile
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)
3.5
K4 K = Research datasets (e.g. Pandora, Demetra; these datasets no longer available). Norman Ecotoxicology database. (click here ) 4 = Verified data
Non-persistent
DT₅₀ (lab at 20 °C)
4
Y4 Y = Germany's Federal Environment Agency (UBA) (click here ) 4 = Verified data
Non-persistent
DT₅₀ (field)
4
H4 H = The US ARS pesticide properties database. Dataset is no longer available. 4 = Verified data
Non-persistent
DT₉₀ (lab at 20 °C)
-
-
-
DT₉₀ (field)
-
-
-
DT₅₀ modelling endpoint
-
-
-
Note
Other sources: DT₅₀ 6 days (DW4); 1.9 days (F3)
Dissipation rate RL₅₀ (days) on plant matrix
Value
2.8
R4 R = Peer reviewed scientific publications 4 = Verified data
-
Note
Published literature RL₅₀ range 0.8-4.7 days, 4 field & undercover grown crops, various matrices, n=4
Dissipation rate RL₅₀ (days) on and in plant matrix
Value
5.9
R4 R = Peer reviewed scientific publications 4 = Verified data
-
Note
Published literature RL₅₀ range 0.9-15.2 days, 13 field & undercover grown crops, various matrices, n=25
Aqueous photolysis DT₅₀ (days) at pH 7
Value
90
C4 C = AGRITOX dataset. Dataset is no longer available. 4 = Verified data
Stable
Note
Insignificant degradation route
Aqueous hydrolysis DT₅₀ (days) at 20 °C and pH 7
Value
5
C4 C = AGRITOX dataset. Dataset is no longer available. 4 = Verified data
Non-persistent
Note
-
Water-sediment DT₅₀ (days)
23.5
K3 K = Research datasets (e.g. Pandora, Demetra; these datasets no longer available). Norman Ecotoxicology database. (click here ) 3 = Unverified data of known source
Fast
Water phase only DT₅₀ (days)
16
K3 K = Research datasets (e.g. Pandora, Demetra; these datasets no longer available). Norman Ecotoxicology database. (click here ) 3 = Unverified data of known source
Slow
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)
-
H3 H = The US ARS pesticide properties database. Dataset is no longer available. 3 = Unverified data of known source
L2 L = Pesticide manuals and hard copy reference books / other sources 2 = Unverified data of unknown source
Rat 2 yr
High
(ppm diet)
-
-
Mammals - Chronic 21d NOAEL (mg kg⁻¹ bw d⁻¹)
-
-
-
Birds - Acute LD₅₀ (mg kg⁻¹)
10
G4 G = Extension Toxicology network database EXTOXNET. Available online but no longer updated. (click here ) 4 = Verified data
Colinus virginianus
High
Birds - Short term dietary (LC₅₀/LD₅₀)
-
-
-
Birds - Chronic 21d NOEL (mg kg⁻¹ bw d⁻¹)
-
-
-
Earthworms - Acute 14 day LC₅₀ (mg kg⁻¹)
34
L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source
Eisenia foetida
Moderate
Earthworms - Chronic NOEC, reproduction (mg kg⁻¹)
-
-
-
Soil micro-organisms
-
-
-
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)
0.97
K3 K = Research datasets (e.g. Pandora, Demetra; these datasets no longer available). Norman Ecotoxicology database. (click here ) 3 = Unverified data of known source
Apis mellifera
High
Oral acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)
> 0.22
K3 K = Research datasets (e.g. Pandora, Demetra; these datasets no longer available). Norman Ecotoxicology database. (click here ) 3 = Unverified data of known source
Apis mellifera
High
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)
0.066
R4 R = Peer reviewed scientific publications 4 = Verified data
Melipona quadrifasciata
High
Mode of exposure
Oral
Other bee species (2)
Acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg insect⁻¹)
96.1
R4 R = Peer reviewed scientific publications 4 = Verified data
Melipona quadrifasciata
Moderate
Mode of exposure
Contact
Beneficial insects (Ladybirds) as Mortality LC₅₀ mg l⁻¹
F3 F = U.S. EPA ECOTOX database / U.S. EPA pesticide fate database / Miscellaneous WHO documents / FAO data, IPCS INCHEM data (US EPA Databases Related to Pesticide Risk Assessment ) 3 = Unverified data of known source
L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source
Rabbit
-
Mammals - Inhalation LC₅₀ (mg l⁻¹)
0.213
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)
0.001
A5 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 ) 5 = Verified data used for regulatory purposes
-
ARfD - Acute Reference Dose (mg kg⁻¹ bw day⁻¹)
0.003
A5 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 ) 5 = Verified data used for regulatory purposes
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
Environmental fate
