an organophosphate compound used to control household, public health, and
stored product insects. It is effective against mushroom flies, aphids,
spider mites, caterpillars, thrips, and white flies in greenhouse, outdoor
fruit, and vegetable crops. Dichlorvos is used to treat a variety of parasitic
worm infections in dogs, livestock, and humans. Dichlorvos can be fed to
livestock to control botfly larvae in the manure. It acts against insects
as both a contact and a stomach poison. It has been used to make pet collars
and pest strips. It is available as an aerosol and soluble concentrate.
2,2-dichlorovinyl dimethyl phosphate
The oral LD50 for dichlorvos is 61 to 175 mg/kg in mice, 100 to 1090 mg/kg
in dogs, 15 mg/kg in chickens, 25 to 80 mg/kg in rats, 157 mg/kg in pigs,
and 11 to 12.5 mg/kg in rabbits. The dermal LD50 for dichlorvos is 70.4
to 250 mg/kg in rats, 206 mg/kg in mice, and 107 mg/kg in rabbits. The 4-hour
LC50 for dichlorvos is greater than 0.2 mg/L in rats.
Dichlorvos is highly toxic by inhalation, dermal absorption,
and ingestion. Because dichlorvos is volatile, inhalation is the most common
route of exposure. As with all organophosphates, dichlorvos is readily absorbed
through the skin. Acute illness from dichlorvos is limited to the effects
of cholinesterase inhibition. Compared to poisoning by other organophosphates,
dichlorvos causes a more rapid onset of symptoms, which is often followed
by a similarly rapid recovery. This occurs because dichlorvos is rapidly
metabolized and eliminated from the body. Persons with reduced lung function,
convulsive disorders, liver disorders, or recent exposure to cholinesterase
inhibitors will be at increased risk from exposure to dichlorvos. Alcoholic
beverages may enhance the toxic effects of dichlorvos. High environmental
temperatures or exposure of dichlorvos to light may enhance its toxicity.
Dichlorvos is mildly irritating to skin. Concentrates of dichlorvos may
cause burning sensations, or actual burns.
Symptoms of acute exposure to organophosphate or cholinesterase-inhibiting
compounds may include the following: numbness, tingling sensations, incoordination,
headache, dizziness, tremor, nausea, abdominal cramps, sweating, blurred
vision, difficulty breathing or respiratory depression, slow heartbeat.
Very high doses may result in unconsciousness, incontinence, and convulsions
or fatality. Some organophosphates may cause delayed symptoms beginning
1 to 4 weeks after an acute exposure that may or may not have produced immediate
symptoms. In such cases, numbness, tingling, weakness, and cramping may
appear in the lower limbs and progress to incoordination and paralysis.
Improvement may occur over months or years, but some residual impairment
soil and groundwater: Dichlorvos has low persistence
in soil. Half-lives of 7 days were measured on clay, sandy clay, and loose
sandy soil. In soil, dichlorvos is subject to hydrolysis and biodegradation.
Volatilization from moist soils is expected to be slow. The pH of the media
determines the rate of breakdown. Breakdown is rapid in alkaline soils and
water, but it is slow in acidic media. For instance, at pH 9.1 the half-life
of dichlorvos is about 4.5 hours. At pH 1 (very acidic), the half-life is
50 hours. Dichlorvos does not adsorb to soil particles and it is likely
to contaminate groundwater. When spilled on soil, dichlorvos leached into
the ground with 18 to 20% penetrating to a depth of 12 inches within 5 days.
water: In water, dichlorvos remains in solution
and does not adsorb to sediments. It degrades primarily by hydrolysis, with
a half-life of approximately 4 days in lakes and rivers. This half-life
will vary from 20 to 80 hours between pH 4 and pH 9. Hydrolysis is slow
at pH 4 and rapid at pH 9. Biodegradation may occur under acidic conditions,
which slow hydrolysis, or where populations of acclimated microorganisms
exist, as in polluted waters. Volatilization from water is slow. It has
been estimated at 57 days from river water and over 400 days from ponds.
vegetation: Except for cucumbers, roses, and some
chrysanthemums, plants tolerate dichlorvos very well.
Dichlorvos is a colorless to amber liquid with a mild chemical odor .
- Chemical Name:
2,2-dichlorovinyl dimethyl phosphate 
- CAS Number:
- Molecular Weight:
- Water Solubility: 10,000 mg/L
- Solubility in Other Solvents:
dichloromethane, v.s.; 2-propanol, v.s.; toluene v.s.; ethanol s.;
chloroform s.; acetone s.; kerosene s. 
- Melting Point:
- Vapor Pressure:
290 mPa @ 20 C 
- Partition Coefficient:
- Adsorption Coefficient:
30 (estimated)