Parathion methyl, or methyl parathion, is an

organophosphate In organic chemistry, organophosphates (also known as phosphate esters, or OPEs) are a class of organophosphorus compounds with the general structure , a central phosphate molecule with alkyl or aromatic substituents. They can be considered a ...

insecticide Insecticides are substances used to kill insects. They include ovicides and larvicides used against insect eggs and larvae, respectively. Insecticides are used in agriculture, medicine, industry and by consumers. Insecticides are claimed to b ...

, possessing an organothiophosphate group. It is structurally very similar to

parathion-ethyl Parathion, also called parathion-ethyl or diethyl parathion and locally known as "Folidol", is an organophosphate insecticide and acaricide. It was originally developed by IG Farben in the 1940s. It is highly toxic to non-target organisms, includ ...

. It is not allowed for sale and import in nearly all countries around the world, while a few allow it under subject to specified conditions only.

Applications

Parathion methyl is used as an insecticide on crops, including cotton.

Trade Names

Penncap-M, Metacide

Safety

People can be exposed to parathion methyl in the workplace by breathing it in, getting it on their skin, swallowing it, or getting it in their eyes. Since it is an acetylcholinesterase inhibitor, symptoms of exposure to parathion methyl include irritated eyes and skin, nausea and vomiting, abdominal pain, diarrhea, salivation, feeling weak and tired, headache, runny nose, tightness in the chest, blurry vision,

pupil constriction Pupillary reflex refers to one of the reflexes associated with pupillary function. These include the pupillary light reflex and accommodation reflex. Although the pupillary response, in which the pupil dilates or constricts due to light is not usu ...

irregular heartbeat Arrhythmias, also known as cardiac arrhythmias, heart arrhythmias, or dysrhythmias, are irregularities in the heartbeat, including when it is too fast or too slow. A resting heart rate that is too fast – above 100 beats per minute in adults ...

, muscle twitches (fasciculation), and

difficulty breathing Shortness of breath (SOB), also medically known as dyspnea (in AmE) or dyspnoea (in BrE), is an uncomfortable feeling of not being able to breathe well enough. The American Thoracic Society defines it as "a subjective experience of breathing disc ...

. In the United States, the Occupational Safety and Health Administration (OSHA) has not set a legal limit ( permissible exposure limit) for parathion methyl exposure in the workplace. The National Institute for Occupational Safety and Health (NIOSH) has set a recommended exposure limit (REL) of 0.2 mg/m³ over an 8-hour workday.

Classifications and restrictions

Parathion methyl has been restricted for many years. It is classified as Extremely Hazardous (Ia) by the World Health Organization and it is classified as Severely Hazardous by the Rotterdam Convention. It is not allowed for sale and import in nearly all countries around the world, while a few allow it under subject to specified conditions only.Annex III Chemicals
Methyl-parathion (Emulsifiable concentrates (EC) at or above 19.5% active ingredient and dusts at or above 1.5% active ingredient)
Rotterdam Convention

References

{{Authority control Acetylcholinesterase inhibitors Organophosphate insecticides Methyl esters Organothiophosphate esters