Methamidophos

Methamidophos is a highly toxic, highly regulated systemic and residual organophosphate, insecticide, acaracide and avicide. Its health effects are consistent with all organophosphates, and result in the inhibition of the enzyme cholinesterase which disrupts normal transmission of nerve impulses. Because of its toxicity, it is highly regulated throughout the world.

Just the facts

Physical Information

Name: Methamidophos

Chemical Name: OS-dimethyl phosphoramidothioate

Chemical Formula: C 2 H 8 N0 2 PS

Trade Names: Monitor, Tamaron, Filitox, Tamanox, Tarn, Patrole, Metamidofos Estrella; Methamidophos 60 WSC: Methedrin 60; Morithion

Synthetic Chemistry

Vapor Pressure: 4.7 mPa (25°C)

Melting Point: 44.5 °C (pure), 37-39 °C (technical)

Recommended daily intake: none

Absorption: dermal, inhalation, ingestion

Sensitive individuals: workers

Toxicity/symptoms: highly toxic

Chemical Description

It is a yellow-ish to colorless crystalline solid at room temperature with a melting point of 44.5 degrees Celsius. Technical methamidophos (about 73%) is in the form of yellowish to colourless crystals with melting point below 40 °C and methamidophos decomposes on heating without boiling and is used only as a spray.

Uses

Methamidophos is a residual and systemic organophosphate insecticide with both contact and ingestion properties to control insects such as aphids, flea beetles, worms, whiteflies, thrips, cabbage loopers, Colorado potato beetles, potato tubeworms, armyworms, mites, leafhoppers, and many others. The crops that methamidophos are use don crops suck as broccoli, Brussel sprouts, cauliflower, grapes, celery, sugar beets, cotton, tobacco, and potatoes. It is used abroad for many vegetables, hops, corn, peaches, and others.

Health Effects

Methamidophos is highly toxic via all routes of exposure. It has been found to have negative effects on reproductive effects including one study found decreased sperm levels in men who were exposed to Tamaran in China. It is not thought to be carcinogenic.

Environmental Effects

Methamidophos is very toxic to birds, aquatic organisms, and bees.

Its half life in soil is relatively short, about 1.9 days in silt, 4.8 days in loam, 6.1 days in sand, and 10-12 days in sandy loam and the population is not generally exposed to methamidophos in the soil or water.

Precautions

Only registered and supervised applicators should apply methamidophos and they need to follow all guidelines. All applicators should wear protective clothing and a respirator if spraying taller crops and if a worker is suspected of being exposed to methamidophos then the worker should be kept under supervision for up to 48 hours.

Regulation

Methamidophos is a US EPA registered, Class I compound which must bear the words "Danger-Poison" n commercial products and is banned, restricted or canceled in 13 countries and not legal for import in 44 countries.

External Links

• PANA on Methamidophos.