Parathion-methyl (Ref: OMS 213)	Last updated: 15/02/2023
(Also known as: metaphos; meptox; thiophenit; quinophos; methyl-parathion)

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SUMMARY

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: Drainflow: Moderately mobile	Ecotoxicity High alert: Fish chronic ecotoxicity: High; Daphnia acute ecotoxicity: High; Daphnia chronic ecotoxicity: High	Human health High alert: Mammals acute toxicity: High; Acetyl cholinesterase inhibitor; Neurotoxicant

GENERAL INFORMATION

Description	An insecticide used to control sucking and chewing insects in a wide range of crops
Example pests controlled	Aphids; Boll weevils; Mealybugs; Scale; Armyworms
Example applications	Cereals; Cotton; Vegetables; Soybean; Fruit; Vines
Efficacy & activity	-
Availability status	Current
Introduction & key dates	circa 1950

UK regulatory status

UK COPR regulatory status	Not approved
Date COPR inclusion expires	Expired
UK LERAP status	No UK approval for use

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; by Mutual Recognition of Authorisation; and/or national regulations in the following EEA countries	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                   ISIceland NONorway

Additional information

Also used in	Australia, USA, Costa Rica

Chemical structure

Isomerism	None
Chemical formula	C₈H₁₀NO₅PS
Canonical SMILES	COP(=S)(OC)OC1=CC=C(C=C1)[N+](=O)[O-]
Isomeric SMILES	No data
International Chemical Identifier key (InChIKey)	RLBIQVVOMOPOHC-UHFFFAOYSA-N
International Chemical Identifier (InChI)	InChI=1S/C8H10NO5PS/c1-12-15(16,13-2)14-8-5-3-7(4-6-8)9(10)11/h3-6H,1-2H3
2D structure diagram/image available?	Yes

Cambridge Crystallographic Data Centre diagrams

Common Name	Relationship	Link
parathion-methyl	-

General status

Pesticide type	Insecticide
Substance groups	Organophosphate insecticide; Organophosphate acaricide; Organothiophosphate insecticide; Organothiophosphate acaricide
Minimum active substance purity	-
Known relevant impurities	-
Substance origin	Synthetic
Mode of action	Contact and stomach insecticide. Cholinesterase inhibitor.
CAS RN	298-00-0
EC number	206-050-1
CIPAC number	487
US EPA chemical code	053501
PubChem CID	4130
CLP index number	015-035-00-7
Molecular mass	263.21
PIN (Preferred Identification Name)	-
IUPAC name	O,O-dimethyl O-4-nitrophenyl phosphorothioate
CAS name	O,O-dimethyl O-(4-nitrophenyl) phosphorothioate
Other status information	Chemical subject to PIC regulations; Potential groundwater contaminant; Marine Pollutant; Subject to the provisions of the UK Poisons Act 1972
Relevant Environmental Water Quality Standards	-
Herbicide Resistance Classification (HRAC)	Not applicable
Herbicide Resistance Classification (WSSA)	Not applicable
Insecticide Resistance Classification (IRAC)	1B
Fungicide Resistance Classification (FRAC)	Not applicable
Examples of recorded resistance	Aedes melanimon, Aedes nigromaculis, Anopheles albimanus, Coleomegilla maculata, Culex pipiens pallens, many others
Physical state	Colourless crystals
Related substances & organisms	parathion-ethyl

Formulations

Property	Value
Example manufacturers & suppliers of products using this active now or historically	Bayer CropScience FCC Ltd Cheminova A/S Monsanto
Example products using this active	Sweeper Amithion Prompt Sabidol Wolfatox
Formulation and application details	Available in a wide variety of formulations including dustable powders, emulsifible concentrates, encapsulated suspensions, ULV liquid and wettable powders.

ENVIRONMENTAL FATE

Property		Value	Source; quality score; and other information	Interpretation
Solubility - In water at 20 °C (mg l⁻¹)		55	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source	Moderate
Solubility - In organic solvents at 20 °C (mg l⁻¹)		200000	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source Dichloromethane	-
		200000	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source Toluene	-
		15000	L2 L = Pesticide manuals and hard copy reference books / other sources 2 = Unverified data of unknown source Hexane	-
Melting point (°C)		35.5	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source	-
Boiling point (°C)		-	-	-
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	1.00 X 1003	Calculated	-
	Log P	3	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source	Moderate
Fat solubility of residues	Solubility	-	-	-
	Data type	-	-	-
Density (g ml⁻¹)		1.36	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)		0.2	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source	Low volatility
Henry's law constant at 25 °C (Pa m³ mol⁻¹)		8.57 X 10-03	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)		-	-	-

Degradation

Property		Value	Source; quality score; and other information	Interpretation
General biodegradability		-
Soil degradation (days) (aerobic)	DT₅₀ (typical)	12	Y4 Y = Germany's Federal Environment Agency (UBA) (click here ) 4 = Verified data	Non-persistent
	DT₅₀ (lab at 20 °C)	12	Y4 Y = Germany's Federal Environment Agency (UBA) (click here ) 4 = Verified data	Non-persistent
	DT₅₀ (field)	10	Y4 Y = Germany's Federal Environment Agency (UBA) (click here ) 4 = Verified data	Non-persistent
	DT₉₀ (lab at 20 °C)	-	-	-
	DT₉₀ (field)	-	-	-
	DT₅₀ modelling endpoint	-	-	-
	Note	PIC DGD states lab DT₅₀ range 1-18 days
Dissipation rate RL₅₀ on plant matrix	Value	3.6	R4 R = Peer reviewed scientific publications 4 = Verified data	-
	Note	Published literature RL₅₀ range 0.4-6.7 days, 6 field crops, various matrices, n=8
Dissipation rate RL₅₀ on and in plant matrix	Value	1.9	R4 R = Peer reviewed scientific publications 4 = Verified data	-
	Note	Published literature RL₅₀ range 0.7-6.6 days, 7 field crops, various matrices, n=12; Fruit in cold storage RL₅₀ range 63-65 days, n=2
Aqueous photolysis DT₅₀ (days) at pH 7	Value	9	Q2 Q = Miscellaneous data from online sources 2 = Unverified data of unknown source	Moderately fast
	Note	-
Aqueous hydrolysis DT₅₀ (days) at 20 °C and pH 7	Value	21	K4 K = Research datasets (e.g. Pandora, Demetra; these datasets no longer available). Norman Ecotoxicology database. (click here ) 4 = Verified data	Non-persistent
	Note	-
Water-sediment DT₅₀ (days)		5	Q2 Q = Miscellaneous data from online sources 2 = Unverified data of unknown source	Fast
Water phase only DT₅₀ (days)		15	Q2 Q = Miscellaneous data from online sources 2 = Unverified data of unknown source	Slow

Soil adsorption and mobility

Property		Value	Source; quality score; and other information	Interpretation
Linear	Kd	-	W3 W = French database provided by ARVALIS-Institut du Végétal. Dataset no longer available. 3 = Unverified data of known source	Moderately mobile
	Koc	240
	Notes and range	-
Freundlich	Kf	34.4	R4 R = Peer reviewed scientific publications 4 = Verified data	Moderately mobile
	Kfoc	442
	1/n	1.038
	Notes and range	Literature data: Kf range 8.0-37.8 (178 for peat) mL g⁻¹, Kfoc range 276-677 (276 for peat) mL g⁻¹, 1/n range 0.909-1.123, Soils=8
pH sensitivity		-

Fate indices

Property		Value	Source; quality score; and other information	Interpretation
GUS leaching potential index		1.35	Calculated	Low leachability
SCI-GROW groundwater index (μg l⁻¹) for a 1 kg ha⁻¹ or 1 l ha⁻¹ application rate	Value	1.93 X 10-02	Calculated	-
	Note	-
Potential for particle bound transport index		Low	Calculated	-
Potential for loss via drain flow		Moderately mobile	Calculated	-
Bio-concentration factor	BCF (l kg⁻¹)	71	J3 J = Pesticide Action Network database (click here ) 3 = Unverified data of known source Oncorhynchus mykiss	Low potential
	CT₅₀ (days)	Not available		-

Known metabolites

None

ECOTOXICOLOGY

Terrestrial ecotoxicology

Property		Value	Source; quality score; and other information	Interpretation
Mammals - Acute oral LD₅₀ (mg kg⁻¹)		3	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source Rat	High
Mammals - Short term dietary NOEL	(mg kg⁻¹)	-	L2 L = Pesticide manuals and hard copy reference books / other sources 2 = Unverified data of unknown source Rat 2 year	-
	(ppm diet)	2		-
Mammals - Chronic 21d NOAEL (mg kg⁻¹ bw d⁻¹)		-	-	-
Birds - Acute LD₅₀ (mg kg⁻¹)		> 1044	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source Anas platyrhynchos	Moderate
Birds - Short term dietary (LC₅₀/LD₅₀)		-	-	-
Birds - Chronic 21d NOEL (mg kg⁻¹ bw d⁻¹)		-	-	-
Earthworms - Acute 14 day LC₅₀ (mg kg⁻¹)		40	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)	19.5	F4 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 ) 4 = Verified data Apis mellifera	Moderate
	Oral acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)	750	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	Low
	Unknown mode acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)	-	-	-
	Chronic	-	-	-
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)	0.0157	R4 R = Peer reviewed scientific publications 4 = Verified data Megachile rotundata	High
	Mode of exposure	Contact
Other bee species (2)	Acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg insect⁻¹)	0.096	R4 R = Peer reviewed scientific publications 4 = Verified data Trigona spinipes	High
	Mode of exposure	Contact
Beneficial insects (Ladybirds)		-	-	-
Beneficial insects (Lacewings)		-	-	-
Beneficial insects (Parasitic wasps)		-	-	-
Beneficial insects (Predatory mites)		-	-	-
Beneficial insects (Ground beetles)		-	-	-

Aquatic ecotoxicology

Property		Value	Source; quality score; and other information	Interpretation
Fish - Acute 96 hour LC₅₀ (mg l⁻¹)		> 2.7	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)		0.0089	P3 P = Other non-EU, UK or US Governments and Regulators 3 = Unverified data of known source Cyprinodon variegatus	High
Aquatic invertebrates - Acute 48 hour EC₅₀ (mg l⁻¹)		> 0.0073	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)		0.00018	P3 P = Other non-EU, UK or US Governments and Regulators 3 = Unverified data of known source Daphnia magna	High
Aquatic crustaceans - Acute 96 hour LC₅₀ (mg l⁻¹)		0.00035	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 Americamysis bahia	High
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)		115	R3 R = Peer reviewed scientific publications 3 = Unverified data of known source Chironomus dilutus growth	Low
Aquatic plants - Acute 7 day EC₅₀, biomass (mg l⁻¹)		-	-	-
Algae - Acute 72 hour EC₅₀, growth (mg l⁻¹)		3	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source Scenedemus subspicatus	Moderate
Algae - Chronic 96 hour NOEC, growth (mg l⁻¹)		-	-	-
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)		3	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source Rat	High
Mammals - Dermal LD₅₀ (mg kg⁻¹ body weight)		45.0	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source Rat	-
Mammals - Inhalation LC₅₀ (mg l⁻¹)		0.17	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	F4 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 ) 4 = Verified data JMPR 1995	-
ARfD - Acute Reference Dose (mg kg⁻¹ bw day⁻¹)		0.03	B4 B = UK CRD and ACP Evaluation Documents / and other DEFRA (UK) documents; Also Chemicals Regulation Division, Health and Safety Executive (HSE), UK (click here ) 4 = Verified data UK ACP 1999	-
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		List I; List II	-	-
Exposure Routes	Public	-
	Occupational	Skin absorption, and to a lesser extent inhalation and ingestion
MRLs	European	EU MRL pesticide database
	Great Britain	GB MRL Register
	Notes	-
Drinking Water Standards		-	-	-
Drinking Water MAC (μg l⁻¹)		-	-	-
Mammalian dose elimination route and rate		Almost completely excreted by the kidneys (urine) within 24 hours as phenolic metabolites	G3 G = Extension Toxicology network database EXTOXNET. Available online but no longer updated. (click here ) 3 = Unverified data of known source	-

Health issues

Specific human health issues		Carcinogen Genotoxic Endocrine disruptor ?Possibly, status not identified A3 A = Chromosome aberration (EFSA database) 3 = Negative ; 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 ; E3 E = Unspecified genotoxicity type (miscellaneous data source) 3 = Negative ?Possibly, status not identified Reproduction / development effects Acetyl cholinesterase inhibitor Neurotoxicant ?Possibly, status not identified ✓Yes, known to cause a problem ✓Yes, known to cause a problem Respiratory tract irritant Skin irritant Skin sensitiser No data found No data found No data found Eye irritant Phototoxicant   No data found No data found
General human health issues		Extremely hazardous IARC Group 3 carcinogen; USEPA - not likely to be a human carcinogen

Handling issues

Property	Value and interpretation
General	Explosive on heating Flammable IMDG Transport Code is 6.1
CLP classification 2013	Handling: H226 Health: H300, H311, H330, H373 Environment: H400, H410
WHO Classification	Ia (Extremely hazardous)
UN Number	Active 2783, liquid products 3018
Waste disposal & packaging	-

TRANSLATIONS

Language	Name
English	parathion-methyl
French	parathion-methyl
German	Parathion-methyl
Danish	parathion-methyl
Italian	paration-metile
Spanish	paratión-metil
Greek	parathion-methyl
Polish	paration metylu
Swedish	-
Hungarian	-
Dutch	parathion-methyl
Norwegian	-

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Record last updated:	15/02/2023
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