Clorpyrifos-methyl is a chemical compound, a synthetic inhibitor of organophosphate acetylcholinesterase.

It occurs as a white crystalline powder and has an ammonia-like odour.

What it is used for and where

Chemical pesticide that attacks insect larvae. It is quite volatile and attaches best to the soil where it performs its function while resisting water well.

Insecticide and acaricide, used against :

• Beetles
• Diptera
• Cereal Lepidoptera
• Homoptera
• Anopheles Gambiae (The mosquito that carries malaria)
• Muscidae (a family of flies)

It is used to protect crops of :

• cotton
• strawberry
• cane fruit
• apple
• pepper
• pear tree
• peach tree
• tomato
• rice
• tea
• vegetables
• grapevines

Safety

In 2020, the European Union banned the use of Chlorpyrifos and revoked the marketing authorisations due to risks associated with human health such as neurotoxicity, especially to children, and the environment.

Italy. In 2020, the Italian Ministry of Health authorised the use of Chlorpyrifos in grape cultivations for 120 days as a maximum period due to the invasion of the Asian fruit bug and the leafhopper (Scaphoideus titanus) also known as 'flavescence dorée' present in grapevines and apple orchards especially in Veneto (Valdobbiadene and Valpolicella). In 2023, however, it appears that, at least in limited quantities, Chlorpyrifos will be sprayed to prevent crop damage.

Canada. A ban on the use of Chlorpyrifos for most agricultural uses, with the exception of mosquito control, came into effect in 2020.

Brazil. Ban on the use of Clorpyrifos in most agricultural crops.

Clorpyrifos-methyl studies

Typical commercial product characteristics Chlorpyrifos-methyl

Appearance	White powder
Boiling Point	347.3±52.0°C at 760 mmHg
Melting Point	45.5-46.5°C
Flash Point	163.8±30.7°C
Density	1.6±0.1 g/cm3
Content	≥95.0%
Moisture	≤0.2%
Acidity	≤0.2%
PSA	82.48000
LogP	3.71
Refractive index	1.582
Vapor Pressure	0.0±0.7 mmHg at 25°C
Safety

• Molecular Formula C₇H₇CL₃NO₃PS
• Molecular Weight 322,53
• Exact Mass   320.894989
• CAS : 5598-13-0
• UNII    O49S38267J
• EC Number   227-011-5
• DSSTox Substance ID  DTXSID6032352
• IUPAC  dimethoxy-sulfanylidene-(3,5,6-trichloropyridin-2-yl)oxy-λ⁵-phosphane
• InChI=1S/C7H7Cl3NO3PS/c1-12-15(16,13-2)14-7-5(9)3-4(8)6(10)11-7/h3H,1-2H3 
• InChl Key    HRBKVYFZANMGRE-UHFFFAOYSA-N  
• SMILES   COP(=S)(OC)OC1=NC(=C(C=C1Cl)Cl)Cl
• MDL number  MFCD00055310
• PubChem Substance ID    329756700
• ChEBI  34632
• Beilstein     1541078
• NACRES NA.24  
• RTECS   TG0700000
• UN   3077    2783
• NCI   C163642

Synonyms

• Chlorpyriphos-methyl
• Trichlormethylfos
• Phosphorothioic acid, O,O-dimethyl O-(3,5,6-trichloro-2-pyridinyl) ester
• Chloropyriphos-methyl
• Caswell No. 179AA
• Methyl chlorpyrifos
• Chlorpyrifos O,O-dimethyl analog
• Reldan™
• Methyl chlorpyriphos