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methamidophos (Monitor) Chemical Profile 4/95

                                   methamidophos

      CHEMICAL NAME:      O,S-Dimethyl phosphoramidothioate (56)

      DEC INGRED. CODE:

      TRADE NAME(S):      Monitor (1)

      FORMULATION(S):     4 lb/gal liquid concentrate, emulsifiable
                          concentrate, wettable powder, granules (1).
                          Liquid concentrate; 40% and 60% w/v (56).

      TYPE:               Organophosphate insecticide

      BASIC PRODUCER(S):  Chevron Chemical Co.         Mobay Chemical Corp.
                          Ortho Agr. Chemicals Div.    Agr. Chemicals Div.
                          575 Market St.               P. O. Box 4913
                          P.O. Box 3744                Kansas City, MO 64120
                          San Francisco, CA 94105

      STATUS:             Restricted use

      PRINCIPAL USES:  Controls certain lepidopterous larvae on vegetables
      (especially crucifers) and field crops.  Some local foliar systemic
      action (1).
           Controls certain lepidopterous larvae (certain cutworms, loopers),
      aphids, mites, and whiteflies.  Tolerances granted on broccoli, Brussels
      sprouts, cabbage, cauliflower, lettuce, cotton seed, potatoes, tomatoes,
      cucumbers, eggplants, peppers, and melons. Also for control of aphids in
      potatoes and peaches (56).


                                   I.  EFFICACY

           Field trials have shown outstanding performance in controlling the
      insect pest complex (including the resistant cabbage looper
      (Trichoplusia ni)), infesting cole crops.  It is very effective against
      green peach aphid (Myzus persicae) and many other species of aphids.
      Monitor effectively controls the major pests of the potato including
      aphids, potato leafhopper, Colorado potato beetle, flea beetle, potato
      tuberworm and the cabbage looper (17c).

      Important Pests Controlled:  Aphids, flea beetles, worms, white flies,
      cabbage lopper, thrips, cutworms, Colorado potato beetle, potato
      tuberworms, armyworms, mites, leafhoppers and many others (8a).
           Besides being a contact and stomach poison it possesses systemic
      activity.  Good residual effectiveness (8a).


                             II.  PHYSICAL PROPERTIES

      MOLECULAR FORMULA:  C2 H8 NO2 P S (62)

      MOLECULAR WEIGHT:   141.1 (62)

      PHYSICAL STATE:     Solid (pure compound) (62)

      MELTING POINT:      44.5 C (pure compound) (62)

      VAPOR PRESSURE:     40 mPa at 30 C (pure compound) (62)

      SOLUBILITY:         >2 kg/l water at 20 C (pure compound) (62)


                          III.  HEALTH HAZARD INFORMATION

      OSHA STANDARD:  None established

      NIOSH RECOMMENDED LIMIT:  None established

      ACGIH RECOMMENDED LIMIT:  None established

      TOXICOLOGY

           A.  ACUTE TOXICITY

               DERMAL:  LD50 = 50-110 mg/kg (male rat) (62)
                        LD50 = 118 mg/kg (rabbit, 75% tech.) (56)

               ORAL:    LD50 = 30 mg/kg (rats and mice); 30-50 mg/kg (guinea-
                          pig); 10-30 mg/kg (rabbit); 25 mg/kg (hen) (62)
                        LD50 = 18-21 mg/kg (rat, 75% tech.) (56)

           B.  SUBACUTE AND CHRONIC TOXICITY:

           In 2-yr feeding trials:  dogs receiving 0.75 mg/kg daily showed
      no significant abnormalities; rats receiving 10 mg/kg diet showed no
      effect (62).


                        IV.  ENVIRONMENTAL  CONSIDERATIONS

           Moderately hazardous to birds, fish and beneficial insects.
      Hazardous to honey bees.  Biological magnification unlikely.  Some
      injury reported on apples (1).

           The acute oral LD50 for bobwhite quail is 57.5 mg/kg (62).

           The LC50 (96 hr.) is: for trout 51 mg/l; for guppies 46 mg/l (62).

      Approximate Residual Period:  1-2 weeks on plants.  Possibly longer as
      systemic (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
      Control Center.

      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, reproductive
      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 under 12 years: 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
      per minute.
      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
      doubled (25).


                        VI.  FIRE AND EXPLOSION INFORMATION

           To be developed.


                                VII.  COMPATIBILITY

           Compatible with most fungicides and insecticides (1).  Slightly
      corrosive to mild steel and copper alloys.  Do not mix with alkaline
      compounds (8a).


                            VIII.  PROTECTIVE MEASURES

      STORAGE AND HANDLING:  Fatal if swallowed, inhaled, or absorbed through
      skin.  Do not get in eyes, on skin, or clothing.  Do not breathe dust,
      keep container closed.  Use with adequate ventilation.  Wash thoroughly
      after handling.  Do not contaminate food or feed products.  Do not drink
      any alcoholic beverages before or during spraying since alcohol promotes
      absorption of organic phosphates (56).

      PROTECTIVE CLOTHING:  Personnel must wear full protective equipment at
      all times.  This includes:  Neoprene-coated gloves, rubber workshoes or
      over-shoes, respirator or mask approved for toxic dust and organic
      vapors, overalls or rubber suit (56).


                       IX.  PROCEDURES FOR SPILLS AND LEAKS

                     IN CASE OF EMERGENCY, CALL, DAY OR NIGHT
                                  (800) 424-9300
                      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.
               30 pp.

       8a. Thomson, W. T.  1976.  Agricultural chemicals - book 1:
               insecticides, acaricides, and ovicides.  Revised ed.  Thomson
               Publ., Indianapolis, IN.  232 pp.

      17c. Chevron Chemical Company, Ortho Division.  1973.  Experimental
               data sheet:  Monitor insecticide.  Moorestown, NJ.

      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.

      4/9/85