- Methyl mercaptophos
- Demeton Methyl
- Phosphorothioic acid o-(2-(ethylthio)ethyl) O,O-dimethyl ester (O compound) mixed with s-(2-(ethylthio)-Ethyl) O,O-dimethyl phosphorothioate (S compound)
Oily colorless to pale yellow liquid with an unpleasant odor.
This material is used as an insecticide, acaricide.
Registry Numbers and Inventories.
Agricultural Chemical and Pesticide; Reproductive Effector
Boiling point, °C
89 (0.15 torr)
Vapor pressure, mmHg
1.20 g/cm3 (20 C)
Solubility in water
1.5063 (20 C)
Hazards and Protection.
Keep in well ventilated area
All chemicals should be considered hazardous. Avoid direct physical contact. Use appropriate, approved safety equipment. Untrained individuals should not handle this chemical or its container. Handling should occur in a chemical fume hood.
Protective clothing and gloves. Face shield or eye proteciton in combination with breathing protection.
Wear positive pressure self-contained breathing apparatus (SCBA).
If you should spill this chemical, use absorbent paper to pick up all liquid spill material. Seal the absorbent paper, as well as any of your clothing which may be contaminated, in a vapor-tight plastic bag for eventual disposal. Wash any surfaces you may have contaminated with a soap and water solution. Do not reenter the contaminated area until the Safety Officer (or other responsible person) has verified that the area has been properly cleaned.
Fires involving this material can be controlled with a dry chemical, carbon dioxide or Halon extinguisher.
This material is probably combustible.
Containers may explode when heated.
Fire may produce irritating, corrosive and/or toxic gases.
TLV: ppm; 0.5 mg/m3 (skin) (ACGIH 1989-1990). NIOSH REL: TWA 0.5 mg/m3 skin
Abdominal cramps, diarrhea, vomiting. See Inhalation.
Acute effects - convulsion, dizziness, labored breathing, nausea, pupillary constriction, muscle cramps, excessive salibation, sweating, unconsciousness. May cause effects on the central nervous system. Cholinesterase inhibitor. Effects may be delayed.
See inhalation. May be absorbed through the skin.
Pupillary constriction, blurred vision.
CHOLINESTERASE INHIBITORS ARE EXTREMELY TOXIC AND FAST-ACTING POISONS. IMMEDIATELY call a hospital of poison control center and transport the victim to a hospital. Atropine is an antidote for cholinesterase inhibitors but should only be administered by properly trained personnel. In the absence of this option and if the victim is conscious and not convulsing, it may be worth considering the risk of inducing vomiting, even though the induction of vomiting is not usually recommended outside of a physician's care. Ipecac syrup or salt water may be used to induce vomiting in such an emergency. If the victim is convulsing or unconscious, do not give anything by mouth, assure that the victim's airway is open and lay the victim on his/her side with the head lower than the body. DO NOT INDUCE VOMITING. IMMEDIATELY transport the victim to a hospital.
IMMEDIATELY leave the contaminated area; take deep breaths of fresh air. IMMEDIATELY call a physician and be prepared to transport the victim to a hospital even if no symptoms (such as wheezing, coughing, shortness of breath, or burning in the mouth, throat, or chest) develop. Provide proper respiratory protection to rescuers entering an unknown atmosphere. Whenever possible, Self-Contained Breathing Apparatus (SCBA) should be used.
IMMEDIATELY flood affected skin with water while removing and isolating all contaminated clothing. Gently wash all affected skin areas thoroughly with soap and water. IMMEDIATELY call a hospital or poison control center even if no symptoms (such as redness or irritation) develop. IMMEDIATELY transport the victim to a hospital for treatment after washing the affected areas.
First check the victim for contact lenses and remove if present. Flush victim's eyes with water or normal saline solution for 20 to 30 minutes while simultaneously calling a hospital or poison control center. Do not put any ointments, oils, or medication in the victim's eyes without specific instructions from a physician. IMMEDIATELY transport the victim after flushing eyes to a hospital even if no symptoms (such as redness or irritation) develop.
I; II; III