is a nonsystemic organophosphate insecticide developed in 1952, used
to control cockroaches, silverfish, ants, and fleas in residential,
non-food buildings. It is used on home gardens and farms to control
a wide variety of sucking and leaf eating insects. It is used on rice,
fruit trees, sugarcane, corn, tobacco, potatoes and on horticultural
plants. It is also an ingredient in pest strips. Diazinon has veterinary
uses against fleas and ticks. It is available in dust, granules, seed
dressings, wettable powder, and emulsifiable solution formulations.
Toxic effects of diazinon are due to the inhibition
of acetylcholinesterase, an enzyme needed for proper nervous system
function. The range of doses that results in toxic effects varies widely
with formulation and with the individual species being exposed. The
toxicity of encapsulated formulations is relatively low because diazinon
is not released readily while in the digestive tract. Some formulations
of the compound can be degraded to more toxic forms. This transformation
may occur in air, particularly in the presence of moisture, and by ultraviolet
radiation. Most modern diazinon formulations in the U.K. are stable
and do not degrade easily. The symptoms associated with diazinon poisoning
in humans include weakness, headaches, tightness in the chest, blurred
vision, nonreactive pinpoint pupils, salivation, sweating, nausea, vomiting,
diarrhea, abdominal cramps, and slurred speech. Death has occurred in
some instances from both dermal and oral exposures at very high levels.
O,O-diethyl O-2-isopropyl-6-methylpyrimidin-4-yl phosphorothioate
Chemical Formula: C12H21N2O3PS
The LD50 is 300 to 400mg/kg for technical
grade diazinon in rats. The inhalation LC50 (4-hour) in rats is 3.5
mg/L In rabbits, the dermal LD50 is 3600 mg/kg.
Wildlife: Birds are quite susceptible
to diazinon poisoning. The use of diazinon in open areas poses a "widespread
and continuous hazard" to birds. Birds are significantly more susceptible
to diazinon than other wildlife. LD50 values for birds range from 2.75
mg/kg to 40.8 mg/kg. Diazinon is highly toxic to fish. In rainbow trout,
the diazinon LC50 is 2.6 to 3.2 mg/L. There is some evidence that saltwater
fish are more susceptible than freshwater fish. Studies show that diazinon
does not bioconcentrate significantly in fish.
is highly toxic to bees***.
Breakdown in soil and
groundwater: Diazinon has a low
persistence in soil. The half-life is 2 to 4 weeks. Bacterial enzymes
can speed the breakdown of diazinon and have been used in treating emergency
situations such as spills. Diazinon seldom migrates below the top half
inch in soil, but in some instances it may contaminate groundwater.
The pesticide was detected in 54 wells in California and in tap water
in Ottawa, Canada, and in Japan.
in water: The breakdown rate is dependent on
the acidity of water. At highly acidic levels, one half of the compound
disappeared within 12 hours while in a neutral solution, the pesticide
took 6 months to degrade to one half of the original concentration.
in vegetation: In plants, a low temperature
and a high oil content tend to increase the persistence of diazinon.
Generally the half-life is rapid in leafy vegetables, forage crops and
grass. The range is from 2 to 14 days. In treated rice plants only 10%
of the residue was present after 9 days. Diazinon is absorbed by plant
roots when applied to the soil and translocated to other parts of the
Diazinon is a colorless to dark brown liquid. It has a flashpoint
of 180 F.
- Chemical Name: O,O-diethyl
- CAS Number: 333-41-5
- Molecular Weight:
- Water Solubility: 40 mg/L
@ 20 C
- Solubility in Other Solvents:
petroleum ether v.s.; alcohol v.s.; benzene v.s.
- Melting Point: Decomposes
@ >120 C
- Vapor Pressure:
0.097 mPa @ 20 C
- Partition Coefficient:
- Adsorption Coefficient:
Health Organisation and Oregon State University.