Dimethoate - Chemical Profile 4/85
CHEMICAL NAME: O,O-Dimethyl S-(N-methylcarbamoylmethyl)
DEC INGRED. CODE:
TRADE NAME(S): Cygon, Rebelate (56)
FORMULATION(S): Emulsifiable concentrate, wettable powder, dust (56)
TYPE: Organophosphate insecticide - miticide
BASIC PRODUCER(S): American Cyanamid Co. BASF Wyandotte Corp.
Agr. Res. Div. Agr. Chem. Div.
P.O. Box 400 P.O. Box 181
Princeton, NJ 08540 Parsippany, NJ 07054
STATUS: General use
PRINCIPAL USES: Used as a residual wall spray in farm buildings for
controlling house flies, and to control a wide range of insects and
mites on ornamental plants, many vegetables, cotton, sorghum, alfalfa,
watermelons, apples, pears, pecans, safflower, wheat, lemons, oranges,
grapefruit, tangerines, melons, tobacco, grapes, tomatoes, corn,
soybeans (56). As systemic on plants for sucking insects and mites (1).
Important Pests Controlled: Aphids, mites, codling moths, grasshoppers,
plum curculio, pear psylla, scale, leafhoppers, thrips, loopers,
Drosophila, lygus bugs, leafminers, flies, olive flies, whiteflies,
Hassids, houseflies and many others (8a).
Effective against many insect larvae. Moves throughout the plant
rapidly. Relatively slow acting against houseflies but with up to 8
weeks residual control. Used to control fly maggots in manure piles
It is effective against houseflies and Diptera of medical importance
II. PHYSICAL PROPERTIES
MOLECULAR FORMULA: C5 H12 N O3 P S2 (62)
MOLECULAR WEIGHT: 229.2 (62)
PHYSICAL STATE: Colorless crystals (pure compound); white to grayish
crystals (technical grade, 96% pure) (62).
MELTING POINT: 51-52 C (pure compound); 45-47 C (technical grade)
VAPOR PRESSURE: 1.1 mPa at 25 C (pure compound) (62)
SOLUBILITY: 25 g/l water at 21 C (62)
III. HEALTH HAZARD INFORMATION
OSHA STANDARD: None established
NIOSH RECOMMENDED LIMIT: None established
ACGIH RECOMMENDED LIMIT: None established
A. ACUTE TOXICITY
DERMAL: LD50 = >1000 mg/kg (guinea pig, 50% a.i. solution) (56)
LD50 = >800 mg/kg (rat); no irritation developed after
the application of 130 mg a.i. (as e.c.)/20 cm2 to
shaved skin of rabbits (62).
ORAL: LD50 (rat) = 500-600 mg a.i./kg (male), 570-680 mg/kg
(female); 180-325 mg tech./kg (male), 240-336 mg/kg
LD50= 215 mg/kg (male albino rat) (56).
B. SUBACUTE AND CHRONIC TOXICITY:
In feeding trials (90-day to 1-yr) NEL in rats for cholinesterase
inhibition was 1.0-32 mg/kg diet. Human volunteers in trials up to 57
days showed NEL for cholinesterase inhibition at 15 mg daily (62).
IV. ENVIRONMENTAL CONSIDERATIONS
Some hazard to birds and fish. Hazardous to honey bees.
Biological magnification unlikely. Injurious to certain varieties of
walnuts, pines, tomatoes, and beans. Russeting appears on red and Golden
Delicious apples (1).
Acute oral LD50: for male pheasants 15 mg/kg; for female ducks 40
mg/kg. LC50 (96-hr) for mosquito fish is 40-60 mg/l. LD50 for honeybees
is 0.9 ug/bee (62).
Approximate Residual Period: 1-3 weeks on plant surfaces; very short
life in soil and water. Several weeks residual control of house flies
in barns (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: Bathe and shampoo victim with soap and water if
there is any chance that skin and hair are contaminated (25).
INGESTION: If victim is alert and respiration is not depressed,
give Syrup of Ipecac, followed by 1-2 glasses of water to induce
vomiting. Adults (12 years and over): 30 ml; children 15 ml (25).
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 individuals 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 poisoning, dosage rates may be
VI. FIRE AND EXPLOSION INFORMATION
To be developed.
Compatible with insecticides and fungicides that are not alkaline
in reaction (8a).
VIII. PROTECTIVE MEASURES
STORAGE AND HANDLING: Harmful or fatal if swallowed, inhaled, or
absorbed through skin. Do not get in eyes, on skin, on clothing. Do
not breathe dust, keep container closed. Use with adequate
ventilation. Wash thoroughly after handling. Do not contaminate food
or feed products. Liquid formulations must be stored above 45 F.
The biological activity remains practically unvaried for 2 years under
environmental conditions, provided stored in unopened and undamaged
original containers, in shaded and possibly well-aired places (56).
PROTECTIVE CLOTHING: See product label. Generally, impervious gloves,
boots, body-covering clothing, wide brimmed hat, and respirator (56).
IX. PROCEDURES FOR SPILLS AND LEAKS
IN CASE OF EMERGENCY, CALL, DAY OR NIGHT
PESTICIDE TEAM SAFETY NETWORK/CHEMTREC
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.
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.