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Methyl Parathion (Penncap-M) - Chemical Profile 4/85

                                 Methyl Parathion

      CHEMICAL name:      O,O-dimethyl-O-p-nitrophenyl phosphorothioate (56)


      TRADE name(S):      Penncap-M, Metacide (1)

      FORMULATION(S):     Emulsifiable concentrates, wettable powders, dusts
                          (56).  Special flowable microencapsulated formula-
                          tion (1).

      TYPE:               Organophosphate insecticide-miticide

      BASIC PRODUCER(S):  Monsanto Agr. Prod. Co.   Vertac Chemical Corp.
                          800 N. Lindbergh Blvd.    5100 Poplar
                          St. Louis, MO 63166       Memphis, TN 38137

      STATUS:             Restricted use

      PRINCIPAL USES:  Insects and mites on many crops.  Nonsystemic (1).
      Used for control of many insects of economic importance, being especially
      effective for boll weevil control (56).  Used on irrigated pastures as
      a mosquito larvicide.  Widely used in mosquito abatement programs (8a).

                                   I.  EFFICACY

      Important Pests Controlled:  Aphids, armyworms, flea beetles,
      leafhoppers, leafminers, scale, mealy bugs, mites, boll weevils, thrips
      and many others.  Especially effective on boll weevils (8a).
           Fast acting (8a).

                             II.  PHYSICAL PROPERTIES

      MOLECULAR FORMULA:  C8 H10 NO5 P S (62)

      MOLECULAR WEIGHT:   263.2 (62)

      PHYSICAL STATE:     Colorless crystals (pure compound); light to dark
                          tan-colored liquid (technical product, c. 80% pure)


      MELTING POINT:      35-36 C (pure compound) (62)

      VAPOR PRESSURE:     1.3 mPa at 20 C (pure compound) (62)

      SOLUBILITY:         55-60 mg/l water at 25 C (pure compound) (62)

                          III.  HEALTH HAZARD INFORMATION

      OSHA STANDARD:  None established

      NIOSH RECOMMENDED LIMIT:  None established

      ACGIH RECOMMENDED LIMIT:  TWA (Time Weighted Average) = 0.2 mg/m3;
                                STEL (Short Term Exposure Limit) = 0.6
                                mg/m3 (deleted); skin notation (15c).


           A.  ACUTE TOXICITY

               DERMAL:  LD50 = 300-400 mg/kg (rabbit) (56)
                        LD50 = 67 mg/kg (rat) (62)

               ORAL:    LD50 = approx. 9-25 mg/kg (rat) (56)
                        LD50 (rat) = 14 mg/kg (male); 24 mg/kg (female) (62).


           In 2-yr feeding trials NEL for rats was 2 mg/kg diet (62).

           Dogs fed methyl parathion for 12 weeks at a rate corresponding to
      approximately 7 mg/man/day showed no clinical effect and no significant
      change in cholinesterase activity.  Four times this dosage produced
      some inhibition of erythrocyte but not plasma cholinesterase.  A dosage
      corresponding to 70 mg/man/day inhibited both erythrocyte and plasma
      cholinesterase activity but did not produce illness.
           Groups of five men each were given methyl parathion for 30 days at
      rates of 7, 7.5, 8 and 9 mg/man/day.  Both the erythrocyte and plasma
      cholinesterase activity remained within 20 percent of control values

                         IV.  ENVIRONMENTAL  CONSIDERATIONS

           Moderately hazardous to birds, fish and beneficial insects.
      Hazardous to honey bees.  Biological magnification unlikely.  Some
      injury reported on alfalfa and sorghum (1).
           Toxic to bees.  Toxic to fish and wildlife so do not use where
      shrimp and crab are an important resource.  Doesn't persist in the soil.
      No harmful effects have been noted on soil microorganisms (8a).

           LC50 (96 hr) is: for rainbow trout 2.7 mg/l; for golden orfe 6.9

      mg/l (62).

      Approximate Residual Period:  1-2 weeks on plant surfaces;
      microencapsulation extends residual period 1 week; short residual in
      soil and water (1).


           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.


           Symptoms of acute poisoning develop during exposure or within 12
      hours (usually within four hours) of contact.  headACHE, DIZZINESS,
      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 under 12
      years: 15 ml (25).


      Adminster 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 mintues 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 pesticides except alkaline materials.
      Penncap-M is compatible with most wettable powders and some liquid
      fertilizers with pH below 7.0 (1).

                            VIII.  PROTECTIVE MEASURES

      STORAGE AND HANDLING:  Do not store near food or feed products.  Do not
      heat product above 131 F.  Store at temperatures above 65 F to avoid
      crystallization.  Avoid contact with eyes, skin, and mouth.  Keep out
      of reach of children (56).

      PROTECTIVE CLOTHING:  Rubber gloves, protective clothing, goggles, and
      respirator.  Wear mask or respirator approved by U.S. Bureau of Mines
      for methyl parathion protection (56).

                       IX.  PROCEDURES FOR SPILLS AND LEAKS

                                  (800) 424-9300

                               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.

      15b. American Conference of Governmental Industrial Hygienists.  1971.
               Documentation of the threshold limit values for substances in
               workroom air with supplements for those substances added or
               changed since 1971, 3rd ed., 4th printing (1977).  Cincinnati,
               OH.  484 pp.

      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.
               116 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.