Dichlorvos (DDVP, Vapona) - Chemical Profile 3/88
CHEMICAL name: 2,2-Dichlorovinyl dimethyl phosphate (56)
DEC INGRED. CODE:
TRADE name(S): Vapona, Vaponite (56)
FORMULATION(S): Emulsifiable concentrates, soluble concentrate,
wettable powder, ready-to-use sprays, aerosols, space sprays, resin
strips (Mafu Strip, No-Pest Strip Insecticide), flea collars, baits.
Concentrates sold under the name of Vaponite are for professional pest
control use only. Formulated as an antihelmintic for swine (Atgard),
horses (Equigard), and dogs (Task, Canogard) (56).
TYPE: Organophosphate insecticide
BASIC PRODUCER(S): Shell Chemical Company (now owned by Dupont)
A Division of Shell Oil
P. O. Box 3871
Houston, TX 77001
STATUS: Restricted use.
A Special Review for dichlorvos was issued during
the week of February 24, 1988 by EPA. The Special
Review is based on risks of cancer and adverse liver
effects, and cholinesterase inhibition. The agency
also noted restrictions on use imposed by the
PRINCIPAL USES: A contact and stomach poison, it also acts as a
fumigant. Controls household and public health pests, stored product
insects, horn flies, house flies, face flies, stable flies, gnats,
and mosquitoes on lactating dairy animals and beef cattle. Control of
mushroom flies; also aphids, spider mites, caterpillars, thrips, white
flies in glasshouse crops, and outdoor fruit and vegetables (56).
Important Pests Controlled: Ants, aphids, mites, mealybugs, ticks,
Drosophila, centipedes, moths, cockroaches, crickets, fleas, flies,
gnats, mosquitoes, sowbugs, spiders, wasps and many others (8a).
Extremely fast knock-down effects. Residual control of 2-3 weeks
may be obtained (8a).
II. PHYSICAL PROPERTIES
MOLECULAR FORMULA: C4 H7 Cl2 O4 P (62)
MOLECULAR WEIGHT: 221.0 (62)
PHYSICAL STATE: Colorless to amber liquid (pure compound) (62)
ODOR: Aromatic odor (pure compound) (62)
BOILING POINT: 35 C/0.05 mmHg (pure compound) (62)
VAPOR PRESSURE: 1.6 Pa at 20 C (pure compound) (62)
SOLUBILITY: c.10 g/l water at 20 C (pure compound) (62)
III. HEALTH HAZARD INFORMATION
OSHA STANDARD: 1 mg/m3 averaged over an 8-hr work shift (14)
NIOSH RECOMMENDED LIMIT: None established
ACGIH RECOMMENDED LIMIT: TWA (Time Weighted Average) = 0.1 ppm, 1
mg/m3; STEL (Short Term Exposure Limit) = 0.3
ppm (deleted), 3 mg/m3 (deleted); skin notation
A. ACUTE TOXICITY
DERMAL: LD50 = 75 mg/kg (rat); 107 mg/kg (rabbit) (56).
LD50 = 75-210 mg/kg (rat) (62)
ORAL: LD50 = 56-108 mg/kg (rat) (62)
LD50 = 56-80 mg/kg (rat) (56)
INHALATION: LC50 (4-hr): 13.2 mg/m3 (mouse); 14.8 mg/m3 (rat)
EYES: Not known to be an eye irritant (14)
B. SUBACUTE AND CHRONIC TOXICITY:
Daily exposure to concentrations which are insufficient to produce
symptoms following a single exposure may result in the onset of
symptoms. Continued daily exposure may be followed by increasingly
In a study of 13 workers exposed for 12 months to an average
concentration of 0.7 mg/m3, the erythrocyte cholinesterase activity
was reduced by approximately 35%, and the serum cholinesterase activity
was reduced by 60%; the results of other tests and of thorough
medical examinations conducted at regular intervals were entirely
In 90-day feeding trials rats receiving 1000 mg/kg diet showed no
IV. ENVIRONMENTAL CONSIDERATIONS
Little or no hazard to birds, fish, and beneficial insects.
Hazardous to honey bees. Biological magnification unknown. Nonphytotoxic
when used as directed (1).
LC50 (24-hr) for bluegill is 1 mg/l. It is highly toxic to
honeybees and toxic to birds (62).
Approximate Residual Period: Only 1-2 days on plant surfaces; much
longer life when impregnated into resin strips or similar carriers (1).
V. EMERGENCY AND FIRST AID PROCEDURES
The chemical information provided below has been condensed
from original source documents, primarily from "Recognition and
Management of Pesticide Poisonings", 3rd ed. by Donald P. Morgan,
which have been footnoted. This information has been provided in
this form for your convenience and general guidance only. In
specific cases, further consultation and reference may be required
and is recommended. This information is not intended as a sub-
stitute for a more exhaustive review of the literature nor for the
judgement of a physician or other trained professional.
If poisoning is suspected, do not wait for symptoms to develop.
Contact a physician, the nearest hospital, or the nearest Poison
FREQUENT SYMPTOMS AND SIGNS OF POISONING BY ORGANOPHOSPHATE PESTICIDES
Symptoms of acute poisoning develop during exposure or within 12
hours (usually within four hours) of contact. headACHE, DIZZINESS,
WEAKNESS, INCOORDINATION, MUSCLE TWITCHING, TREMOR, NAUSEA, ABDOMINAL
CRAMPS, DIARRHEA, and SWEATING are common early symptoms. Blurred or
dark vision, confusion, tightness in the chest, wheezing, productive
cough, and PULMONARY EDEMA may occur. Incontinence, unconsciousness
and convulsions indicate very severe poisoning. SLOW HEARTBEAT,
salivation, and tearing are common. TOXIC PSYCHOSIS, with manic or
bizarre behavior, has led to misdiagnosis of acute alcoholism. Slowing
of the heartbeat may rarely progress to complete sinus arrest.
RESPIRATORY DEPRESSION may be fatal. Continuing daily absorption of
organophosphate at intermediate dosage may cause an INFLUENZA-LIKE
ILLNESS characterized by weakness, anorexia, and malaise (25).
SKIN CONTACT: Immediately wash the contaminated skin using soap or
mild detergent and water. Get medical attention immediately (14).
INGESTION: If the person is conscious, give large quantities of
water immediately. Try to get the person to vomit by having him touch
the back of his throat with his finger. Do not make an unconscious
person vomit. Get medical attention immediately (14).
INHALATION: Move the exposed person to fresh air at once. If
breathing has stopped, perform artificial respiration. Keep the affected
person warm and at rest. Get medical attention as soon as possible (14).
EYE CONTACT: Wash eyes immediately with large amounts of water,
lifting the lower and upper lids occasionally. Get medical attention
immediately. Contact lenses should not be worn when working with this
NOTES TO PHYSICIAN:
Administer ATROPINE SULFATE intravenously, or intramuscularly, if IV
injection is not possible.
In MODERATELY SEVERE poisoning: Adult dosage: 0.4-2.0 mg repeated
every 15 minutes until atropinization is achieved: tachycardia (pulse
of 140 per minute), flushing, dry mouth, dilated pupils. Maintain
atropinization by repeated doses for 2-12 hours or longer depending on
severity of poisoning.
Dosage for children under 12 years: 0.05 mg/kg body weight, repeated
every 15 minutes until atropinization is achieved. Maintain
atropinization with repeated dosage of 0.02-0.05 mg/kg.
SEVERELY POISONED individual may exhibit remarkable tolerance to
atropine; two or more times the dosages suggested above may be needed.
Administer PRALIDOXIME (Protopam (TM)-Ayerst, 2-PAM) in cases of severe
poisoning in which respiratory depression, muscle weakness and
twitchings are severe.
Adult dosage: 1.0 gm intravenously at no more than 0.5 gm per minute.
Child's dose (under 12 years): 20-50 mg/kg (depending on severity of
poisoning) intravenously, injecting no more than half the total dose
Dosage of pralidoxime may be repeated in 1-2 hours, then at 10-12 hour
intervals if needed. In very severe poisonings, dosage rates may be
VI. FIRE AND EXPLOSION INFORMATION
Toxic gases and vapors (such as hydrogen chloride gas, phosphoric
acid mist, and carbon monoxide) may be released in a fire involving
Breaks down in water dilutions. Check label for compatibility of
given formulation (1). Do not combine with alkaline compounds or with
Morestan or Euparen. Compatible with other compounds (8a).
VIII. PROTECTIVE MEASURES
STORAGE AND HANDLING: Poisonous if swallowed, inhaled, or absorbed
through skin. Do not contaminate feed or foodstuffs. Do not drink
any alcoholic beverages before or during spraying since alcohol promotes
absorption of organic phosphates. No shelf-life problems with unopened
package (No-Pest Strip Insecticide) (56).
PROTECTIVE CLOTHING: To prevent repeated or prolonged skin contact
with dichlorvos: use impervious clothing, gloves, face shields (eight-
inch minimum), and other appropriate protective clothing (14).
PROTECTIVE EQUIPMENT: When engineering controls are inadequate, or not
technically feasible, respirators may be used to control exposure.
The only ones permitted are those that have been approved by the Mine
Safety and Health Administration or by the National Institute for
Occupational Safety and Health (14).
IX. PROCEDURES FOR SPILLS AND LEAKS
IN CASE OF EMERGENCY, CALL, DAY OR NIGHT
PESTICIDE TEAM SAFETY NETWORK/CHEMTREC
Persons not wearing protective equipment and clothing should be
restricted from areas of spills or leaks until cleanup has been
If dichlorvos is spilled or leaked, the following steps should be
1. Ventilate area of spill or leak.
2. Collect for reclamation or absorb in vermiculite, dry sand,
earth, or a similar material.
Waste disposal method:
Dichlorvos may be disposed of by absorbing it in vermiculite, dry
sand, earth or a similar material and disposing in a secured sanitary
X. LITERATURE CITED
1. Harding, W.C. 1979. Pesticide profiles, part one: insecticides
and miticides. Univ. Maryland, Coop. Ext. Serv. Bull. 267.
8a. Thomson, W. T. 1976. Agricultural chemicals - book 1:
insecticides, acaricides, and ovicides. Revised ed. Thomson
Publ., Indianapolis, IN. 232 pp.
14. U. S. Department of Health and Human Services, National Institute
for Occuptational Safety and Health. 1981. Occupational
health guidelines for chemical hazards. F. W. Mackinson, R.
S. Stricoff, L. J. Partridge, Jr., and A. D. Little, Inc.,
eds. DHHS (NIOSH) Publ. No. 81-123. Washington, DC.
15c. American Conference of Governmental Industrial Hygienists. 1984.
TLVs: threshold limit values for chemical substances and
physical agents in the work environment and biological exposure
indices with intended changes for 1984-85. Cincinnati, OH.
25. Morgan, D.P. 1982. Recognition and management of pesticide
poisonings, 3rd ed. U.S. Environmental Protection Agency,
Washington, DC. 120 pp.
56. Farm Chemicals Handbook, 70th ed. 1984. R. T. Meister, G. L.
Berg, C. Sine, S. Meister, and J. Poplyk, eds. Meister
Publishing Co., Willoughby, OH.
62. The Pesticide Manual: A World Compendium, 7th ed. 1983. C.R.
Worthing, ed. The British Crop Protection Council, Croydon,
England. 695 pp.