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                                          ET L'AGRICULTURE

                                               ORIGINAL:  ENGLISH


   June 1975


         It must be noted that the issue of a Data Sheet for a
    particular pesticide does not imply endorsement of the pesticide by
    WHO or FAO for any particular use, or exclude its use for other
    purposes not stated. While the information provided is believed to
    be accurate according to data available at the time when the sheet
    was compiled, neither WHO nor FAO are responsible for any errors or
    omissions, or any consequences therefrom.

    The issue of this document does    Ce document ne constitue pas une
    not constitute formal              publication. Il ne doit faire
    publication. It should not be      l'objet d'aucun compte rendu ou
    reviewed, abstracted or quoted     résumé ni d'aucune citation sans
    without the agreement of the       l'autorisation de l'Organisation
    Food and Agriculture               des Nations Unies pour
    Organization of the United         l'Alimentation et l'Agriculture
    Nations or of the World Health     ou de l'Organisation Mondiale de
    Organization.                      la Santé.


    Part 1 - General information    


             Primary use:  insecticide
             Secondary uses: acaricide
             Chemical group: organophosphorus compound
             Data sheet No. 14
             Date issued: June 1975

    1.1   COMMON NAME:  Mevinphos (ISO)

          Identity: 2-methoxycarbonyl-1-methylvinyl dimethyl phosphate,
          the technical material contains at least 60% of the cis isomer.

          Structural Formula



    1.2   SYNOPSIS: an organophosphorus pesticide of very high mammalian
          toxicity.  It may be absorbed from the gastrointestinal tract, by
          inhalation and through the intact skin.


          1.3.1   Physical characteristics: the technical material is a
          pale yellow to orange liquid b.p. 99-103°C at 0.03 mm Hg.

          1.3.2   Solubility: highly soluble in water in all proportions,
          also alcohols, ketones, and chlorinated aromatic hydrocarbons.
          Practically insoluble in hexane.

          1.3.3   Stability: moderately stable in neutral solution which
          remains effective biologically after standing for seven days.
          The technical product is hydrolysed in aqueous solution with a
          half-life of 120 days at pH 6, 35 days at pH 7 and 1.4 hours at
          pH 11. Corrosive to brass, cast iron, mild and some stainless
          steels. Relatively non-corrosive to copper, monel, nickel and
          aluminium. Diffuses slowly through polythene.  Incompatible with
          alkaline pesticides and fertilizers.

          1.3.4   Vapour pressure (volatility): 2.9 x 10-3 mm Hg at


          1.4.1   Common formulations

          Water solution, 25%; emulsifiable concentrates, 10-50%; granules,
          1-5%; wettable powder, 10%; aerosols.

          There are draft FAO specifications for the technical material and
          emulsifiable concentrates.

          1.4.2   Susceptible pests

                  Highly effective against most insects and mites.
                  Although not persistent, the high initial kill gives
                  relatively long protection.  The cis-isomer is about
                  100 times as insecticidal as the trans-.

          1.4.3   Use pattern

                  Mevinphos has been used to control many pests on a wide
                  range of crops, but its main uses are against vegetable
                  pests and aphids, leaf rollers and mites in fruit.  Owing
                  to its rapid loss by volatilization and degradation from
                  treated plants, it is most used shortly before harvest.
                  In a number of countries, officially approved pre-harvest
                  intervals for outdoor application at rates up to 0.5
                  kg/ha are in the range of 1-4 days for many crops.

          1.4.4   Unintended effects

                  Toxic to most animal species but hazard from rec ended
                  use is slight owing to rapid breakdown.  Non-recommended
                  uses as an avicide are known to have killed domestic
                  animals and wildlife.  Does not accumulate in soil and no
                  ill effects on soil micro-organisms have been reported.
                  Not phytotoxic when used as recommended, although some
                  crops may be sensitive to solvents used in certain


          Not used in public health.

    1.6    HOUSEHOLD USE

          Mevinphos is too toxic for household use.


    Part 2 - Toxicology and risks     

              Common name:  mevinphos
              Data sheet No. 14
              Date issued:  June 1975


          2.1.1   Absorption route: absorbed by the skin as well as by
          inhalation and from the gastrointestinal tract, as well as by
          inhalation and through the intact skin.

          2.1.2   Mode of action: cholinesterase inhibition.

          2.1.3   Excretion products: excretion takes place rapidly as
          dimethylphosphoric acid in urine.

          2.1.4   Toxicity, single dose

          Oral: LD50 rat (M) 6.1 mg/kg
                             (F) 3.7 mg/kg

          Demal: LD50 rat (M) 4.7 mg/kg
                              (F) 4.2 mg/kg

          Dermal: LD50 rabbit 4.7-33.8 mg/kg

          Most susceptible species:  not known.

          2.1.5   Toxicity, repeated doses

          Oral: see dietary studies

          Dermal: no information

          Inhalation: no information

          Repeated administration by any route will result in progressive
          reduction of cholinesterase.

          Cumulation of compound

          Mevinphos does not accumulate in body tissues and is excreted
          rapidly in the urine as dimethyl-phosphoric acid. Only hydrolysis
          products were found in the milk of treated cows.

          Cumulation of effect

          Repeated exposure to sub-lethal amounts may reduce cholinesterase
          activity to hazard levels.

          2.1.6   Dietary studies

          Short-term: In rats which were fed 0.32, 0.8, 20 or 5.0 ppm
          (0.016, 0.04, 0.1 or 0.25 mg/kg/day) for up to 12 weeks the no-
          effect level with respect to erythrocyte cholinesterase activity
          was 0.8 ppm (0.04 mg/kg/day).  A concentration in the diet
          greater than 5 ppm (0.25 mg/kg/day) was required to cause a
          significant reduction in the cholinesterase activity of the
          plasma or brain.

          In dogs which were fed 0.3, 1.0, 2.5, 5.0, 75 or 200 ppm of
          mevinphos in their diet (0.0075, 0.025, 0.125, 1.875 or 5.0
          mg/kg/day), signs of intoxication were evident at 75 ppm (1.875
          mg/kg/day).  The no effect level with respect to erythrocyte
          cholinesterase was 1 ppm (0.025 mg/kg/day).

          2.1.7   Supplementary studies of toxicity

          No information.

          2.1.8   Modifications of toxicity

          No information.

    2.2   TOXICOLOGY - MAN

          2.2.1   Absorption

          See 2.1.1. The dermal route is an important route of absorption
          with mevinphos.

          2.2.2   Dangerous doses

          Single: The dangerous dose of mevinphos for man is unknown.
          However, animal experiments and poisoning cases arising from
          occupational exposure show that it is very small.

          Repeated: No information.

          2.2.3   Observations of occupationally exposed workers

          Most observed cases of poisoning have been isolated and have been
          occupational in origin.  In one year in one location in the
          Americas, of 287 cases of poisoning by organophosphorus
          pesticides, 34 were caused by mevinphos which was second only to
          parathion as the most common cause of poisoning by this class of

          2.2.4   Observations on exposure of the general population

          With correct use in agriculture, the general population will not
          be exposed to hazardous amounts of mevinphos.

          2.2.5   Observations of volunteers

          No information.

          2.2.6   Reported mishaps

          Six children in one location in the Americas were poisoned by
          wearing unwashed jeans that had been contaminated by mevinphos.
          Approximately 8 months previously the trousers had been
          transported on a truck loaded with mevinphos.  The insecticide
          had spilled fr= a punctured container.


          2.3.1   Fish

          Toxic to fish and crustaceans.

          2.3.2   Birds

          Highly toxic to birds.

          2.3.3   Other species

          Toxic to bees and other pollinators.  Toxic to wildlife
          generally.  Not harmful to soil micro-organisms.

    In all species, there is little hazard from recommended use owing to
    rapid decomposition.


    Part 3 - For regulatory authorities

             Common name:  mevinphos
             Data sheet No. 14
             Date issued:  June 1975


          (for definition of categories, see introduction)

          Liquid formulations over 20%, category 2; liquid formulations
          over 2%, category 3; all others, category 4.

          Solid formulations over 20%, category 3; all others, category 4.


          All formulations

          Should be transported and stored in clearly labelled impermeable
          containers under lock and key, secure from access by unauthorized
          persons and children. No food or drink should be stored in the
          same compartment.

    3.3   HANDLING

          All formulations

          Full protective clothing (see part 4) should be used by those
          handling the compound.  Adequate washing facilities should be
          available at all times during handing and should be close to site
          of handling.  Eating, drinking and smoking should be prohibited
          during handling and before washing after handling.


          All formulations

          Container must either be burned or crushed and buried below
          topsoil.  Care must be taken to avoid subsequent contamination of
          water sources. Decontamination of containers in order to use them
          for other purposes should not be permitted.


          All formulations

          Pre-employment medical examination of workers necessary.  Workers
          suffering from active hepatic or renal disease should be excluded
          from contract.  Pre-employment and periodic cholinesterase test
          for workers desirable.  Special account should be taken of the
          workers' mental ability to comprehend and follow instructions.
          Training of workers in techniques to avoid contact essential.


          All formulations

          Pilots and loaders should have special training in application
          methods and early symptoms of poisoning, and must wear a suitable
          respirator.  Use of flagmen not recommended.  Flagmen, if used,
          should wear protective clothing and be located well away from the
          dropping zone.

    3.7   LABELLING

          All formulations

                          (skull and cross bones insignia)

          "Mevinphos is an organophosphorus compound which inhibits
          cholinesterase.  It is a very toxic substance.  Contact with the
          skin, inhalation of dust or spray, or swallowing may be fatal.
          Wear protective gloves, clean protective clothing, and a
          respirator of the organic-vapour type when handling this
          material.  Bathe immediately after work.  Ensure that containers
          are stopped under lock and key.  Empty containers must be
          disposed of in such a way as to,prevent all possibility of
          accidental contact with them. Keep the material out of reach of
          children and well away from foodstuffs, animal feed and their

          "In case of contact, immediately remove contaminated clothing and
          wash the skin thoroughly with soap and water; for eyes, flush
          with water for 15 minutes.

          "If poisoning occurs, call a physician.  Atropine and pralidoxime
          are specific antidotes and repeated doses may be necessary.
          Artificial respiration may be needed."


        Maximum residue levels

        The Joint FAO/WHO Meeting on Pesticides Residues (1972) has
        recommended the following limits:

     Broccoli, Brussel sprouts, cabbage, cauliflower, collards...  1 ppm
     Cherries, strawberries......................................  1 ppm
     Apples, grapes, peaches, lettuce, spinach...................  0.5 ppm
     Cucumbers, tomatoes, apricots, citrus fruit, pears..........  0.2 ppm
     Carrots, beans, onions, pears, potatoes, turnips............  0.1 ppm
     Melons......................................................  0.05 ppm


    Part 4 - Prevention of poisoning in man and emergency aid

             Common name:  mevinphos
             Data sheet No. 14
             Date issued:  June 1975


    4.1.1 General

          Mevinphos is an organophosphorus pesticide of very high toxicity.
          It penetrates the intact skin and is also absorbed by inhalation
          and from the gastrointestinal tract. Most formulations should be
          handled by trained personnel wearing protective clothing.

    4.1.2 Manufacture and formulation


          (A.C.G.I.H.) 0.1 mg/m3;  (USSR)

          Formulation should not be attempted without advice from the

          Closed systems and forced ventilation may be required to reduce
          as much as possible the exposure of workers to the chemical.

    4.1.3 Mixers and applicators

          When opening the container and when mixing, protective
          impermeable boots, clean overalls, gloves and respirator should
          be worn.  Mixing, if not mechanical, should always be carried out
          with a paddle of appropriate length.  When spraying tall crops or
          during aerial application a respirator should be worn as well as
          an impermeable hood, clothing, boots and gloves.  The applicator
          should avoid working in spray mist and avoid contact with the
          mouth. Particular care is needed when equipment is being washed
          after use.  All protective clothing should be washed immediately
          after use, including the insides of the gloves. Splashes must be
          washed immediately from the skin or eyes with large quantities of
          water.  Before eating, drinking or smoking, hands and other
          exposed skin should be washed.

    4.1.4 Other associated workers (including flagmen in aerial operations)

          Persons exposed to mevinphos and associated with its application
          should wear protective clothing and observe the precautions
          described above in 4.1.3 under "mixers and applicators".

    4.1.5 Other populations likely to be affected

          With good agricultural practice subject to 4.2 below, other
          populations should not be exposed to hazardous amounts of


          Unprotected persons should be kept out of treated areas for at
          least one day.


          Residues in containers should be emptied in a diluted form into a
          deep pit taking care to avoid contamination of ground waters.
          Decontamination of containers in order to use them for other
          purposes should not be permitted.

          Spillage of mevinphos and its formulations should be removed by
          washing with 5% sodium hydroxide solution and then rinsing with
          large quantities of water.


    4.4.1 Early symptoms of poisoning

          Early symptoms of poisoning may include excessive sweating,
          headache, weakness, giddiness, nausea, vomiting, stomach pains,
          blurred vision, slurred speech, and muscle twitching.  Later
          there may be convulsions, coma, loss of reflexes and loss of
          sphincter control.

    4.4.2 Treatment before person is seen by a physician, if these symptoms
          appear following exposure

          The person should stop work immediately, remove contaminated
          clothing and wash the affected skin with water and soap, if
          available, and flush the area with large quantities of water.  If
          swallowed, vomiting should be induced if the person is conscious.
          In the event of collapse, artificial respiration should be given,
          bearing in mind that if mouth-to-mouth respiration is used, vomit
          may contain toxic amounts of mevinphos.


    Part 5 - For medical and laboratory personnel

             Common name:  mevinphos
             Date sheet No. 14
             Date issued:  June 1975


    5.1.1 General information

          An organophosphorus pesticide of very high acute toxicity which
          is easily absorbed through the intact skin as well as by
          inhalation and from the gastrointestinal tract.  It acts by
          inhibiting acetyl cholinesterase.  Continued exposure to low
          amounts may inhibit blood cholinesterases to dangerous levels.

    5.1.2 Symptoms and signs

          Initial symptoms of poisoning may include excessive sweating,
          headache, weakness, giddiness, nausea, vomiting, stomach pains,
          blurred vision, slurred speech and muscle twitching.  More
          advanced symptoms of poisoning may be convulsions, coma, loss of
          reflexes and loss of sphincter control.

    5.1.3 Laboratory

          The most important laboratory finding is reduction in activity of
          blood cholinesterases.  Urinary levels of organic phosphorus
          containing metabolites should also be able to be used as a
          measure for exposure.  Neither method is specific for mevinphos.

    5.1.4 Treatment

          If the pesticide has been ingested, unless the patient is
          vomiting, rapid gastric lavage should be performed using 5%
          sodium bicarbonate, if available.  For skin contact, the skin
          should be washed with soap and water.  If the compound has
          entered the eyes, they should be washed with isotonic saline.

          Persons without signs of respiratory inefficiency but with
          manifest peripheral symptoms should be treated with 2-4 mg of
          atropine sulfate and 1000-2000 mg of pralidoxime chloride or 250
          mg of toxogonin (adult dose) by slow intravenous injection.  More
          atropine may be given as needed.  Persons with severe
          intoxication with respiratory difficulties, convulsions and
          unconsciousness should immediately be given atropine and a
          reactivator.  In such severe cases 4-6 mg of atropine sulfate
          should be given initially followed by repeated doses of 2 mg at
          5-10 minute intervals.  The patient's condition, including
          respiration, blood pressure, pulse frequency, salivation and
          convulsions should be carefully observed as a guide to further
          administration of atropine. If the patient is cyanotic, 
          artificial respiration should be given first, then atropine
          sulfate.  The airways should be kept free and artificial
          respiration should be applied, if required, preferably by
          mechanical means.  If necessary intubation should be performed.

          Contraindications are morphine, barbituates, phenothiazine
          tranquillizers and central stimulants of all kinds.

    5.1.5 Prognosis

          If the acute toxic effect is survived and adequate artificial
          respiration has been given if needed, the chances of complete
          recovery are good.  However, in very severe cases, particularly
          if artificial respiration has been inadequate, prolonged anoxia
          may give rise to permanent brain damage.

    5.1.6 References of previously reported cases

          Case histories and general methods for treatment are given in:

          Hayes, W. J. Jr. Clinical Handbook and Economic Poisons, U.S.
              Public Health Ser.  No. 476, Revised 1963, pp 18-23, 38-39.

          See also Safe Use of Pesticides in Public Health (1967) Wld Hlth 
              Org. techn. Rep. Ser. No. 356, pp 58-59

          For reports of individual cases of poisoning see:

              Warren, M. C., Conrad, J. P., Bocian, J. J. and Hayes, M.
              (1963) J. Amer. Med, Assoc., 184, 266-268

              Bell, A., Barnes, R. and Simpson, G. R. (1968) Med, J. Aust.,
              1, 178-180


    Test                     Normal      Hazard      Symptomatic
                             level*    level*     level*

    Plasma cholinesterase        100%      50%         variable
    Erythrocyte cholinesterase   100%      70%         usually < 40%

          * expressed as percentage of pre-exposure activity

          Urinary levels of ether-extractable organic phosphorus should
          also be able to be used to determine the degree of exposure.


          References are given only.

    5.3.1 Detection and assay of compound

          It is unlikely that unchaged mevinphos will be detectable in
          human tissue after exposure.  Determination of levels of blood
          cholinesterase (see 5.3.2 below) should be used in cases of
          suspected poisoning.

          The multi-residue gas-chromatographic method of Abbott et al.
          (1970) is satisfactory for determining levels of mevinphos in
          foodstuffs.  Other methods have been reviewed by FAO/WHO (1973).

    5.3.2 Other tests in cases of poisoning

          Levels of cholinesterase in the blood, particularly plasma,
          provide the most useful diagnosis of poisoning.  See:

          Michel, N. O. (1949) J. Lab Clin. Med., 34, 1564-1568 Ellman,
          G. L., Courtney, K. D., Andres, V.-, Jr. and Featherstone, R. M.
              (1961) Biochem. Pharmacol., 7, 88-95

          Urinary levels of other extractable organic phosphorus (Mattson &
          Sledak, 1960) or dimethyl phosphate and phosphorothionate (Shafik
          & Enos, 1969) can also be used to determine exposure.


    Abbot, D. C., Crisp, S., Tarrant, K. R. & Tatton,  J. O'G., Pesticide
          Residues in the Total Diet in England and Wales, 1966-1967.  III.
          -Organophosphorus Pesticide Residues in the Total Diet, Pestic. 
          Sci., 1970, 1, 10

    FAO/WHO, 1973 Evaluation of some pesticide residues in food, FAO/AGP:
          1972/M/9/1;  WHO/1973, p. 413

    Mattson, A. M. & Sledak, V. A., Ether-extractable urinary phosphates in
          man and rats derived from malathion and similar compounds, J. 
          agr. Fd Chem., 1960, 8, 107

    Shafik, M. T. & Enos, H. F., Determination of Metabolic and Hydrolytic
          Products of Organophosphorus Pesticide Chemicals in Human Blood
          and Urine, J. agric. Fd Chem., 1969, 17, 1186

See Also:
        Mevinphos (PIM 348)