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Pirimiphos-methyl — toxicity, side effects, diseases and environmental impacts

Thursday, November 23, 2017 by

Pirimiphos-methyl is an organophosphate. It is an active ingredient in some insecticides to control, thrips, psyllid and other pests. Pirimiphos-methyl is toxic to both people and the environment.

Insecticides on the market that are known to contain pirmiphos-methyl include Target, Silo 500EC, Silo Dust, Attack, Actellic 50 EC, and Actellic Dust. Pirimiphos-methyl is also called Actelic, Actellic, Actellifog, Aktelik, Aktellik, BLEX, C014153, CHEBI:38843, EINECS 249-528-5, Fosforan pirimidyny [Polish], Fosforan pirimidyny [Polish], Methylpirimiphos, Methylpyrimiphos, MFCD00055366, NCGC00163924-01, and NCGC00163924-02.

Pirimiphos-methyl is used on stored grain products like corn, rice, wheat, and grain sorghum intended for export only. It is an emulsifiable concentrate that is often used in sprays.

The physical state of pirimiphos-methyl is an amber-colored liquid. It has a typical putrid organophosphorothioate odor, but it is odorless when pure.

List of known side effects

Pirimiphos-methyl is harmful if swallowed, and it is very toxic to aquatic life. While it hasn’t been classified as a carcinogen, pirimiphos-methyl can cause various symptoms such as headache, nausea, vomiting, abdominal cramps, diarrhea, dizziness, sweating, extreme weakness, ataxia, miosis, blurred vision, twitching, tremor, slow heart beat, difficulty breathing, tightness in chest, and pulmonary edema.

Body systems affected by pirimiphos-methyl

In human exposure studies concerning pirimiphos-methyl, five healthy men (body weight: 59.5 to 73 kilograms [kg]; age: 25 to 45 years) were given pirimiphos-methyl (purity, 97.8 percent) at a dose of 0.25 mg/kg bw per day orally for 28 days. Blood samples to measure plasma and erythrocyte cholinesterase activity were taken on days -14, -7, 1, 3, 7, 14, 21 and 28.

One subject showed inhibition of plasma cholinesterase activity (21.5 percent) on day 28. Otherwise, changes in cholinesterase activity, both above and below values measured before dosing, were within 12 percent.

Four of five subjects had erythrocyte cholinesterase activity values that were slightly below the pre-exposure values during the last two weeks of the study. However, the group means for each time interval did not differ significantly and the variations noted were within the range of variations found by others for normal untreated subjects.

Pirimiphos-methyl can cause cholinesterase inhibition in humans, meaning it can overstimulate the nervous system causing nausea, dizziness, confusion. At very high exposures (e.g. accidents or major spills), pirimiphos-methyl can cause respiratory paralysis and even death.

Items that can contain pirimiphos-methyl

Pirimiphos-methyl is used to control a wide range of insects and mites such as grain weevils, common flour mites, warehouse moths, mill moths, flour beetles rust-red grain beetles, food mites, and stored grain pests.

Pirimiphos-methyl is applied on stored grains such as barley, wheat, oats and non-cropped areas such as animal houses, domestic, and industrial premises.

How to avoid pirimiphos-methyl

Be extremely careful when using pirimiphos-methyl to minimize exposure as much as possible. After using pirimiphos-methyl, wash your hands thoroughly with soap and water before eating, drinking, chewing gum, smoking, or using the toilet.

After using pirimiphos-methyl, remove the clothes you were working in, take a shower or bath with soap and water, shampoo your hair, and put on clean clothes. Wash your work clothes separately from other clothes before wearing them again.

Since pirimiphos-methyl is toxic, workers must wear the right safety gear to protect your health. These include full personal protective equipment (PPE) and respiratory protective equipment (RPE) that must be worn when mixing, loading, or applying pirimiphos-methyl.

Full PPE:

  • Chemical resistant coveralls
  • Chemical resistant gloves
  • Chemical resistant footwear plus socks
  • Protective eye-wear
  • Chemical resistant headgear

Where to learn more


Pirimiphos-methyl is an organophosphate.

Pirimiphos-methyl can overstimulate the nervous system and it can cause respiratory paralysis.

Pirimiphos-methyl is used to control a wide range of insects and mites.

Sources include:


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