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    WORLD HEALTH ORGANIZATION             FOOD AND AGRICULTURE
                                          ORGANIZATION
    ORGANISATION MONDIALE DE LA SANTE     ORGANISATION POUR L'ALIMENTATION
                                          ET L'AGRICULTURE

                                                      VBC/DS/78.32

                                                      ORIGINAL: ENGLISH






    DATA SHEETS ON PESTICIDES No. 32

    CHLORPHOXIM






         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.

                             CLASSIFICATION:

                             Primary Use: Insecticide

                             Secondary Use:

                             Chemical Group: Organophosphorus compound

                             Date Issued:

    1.  GENERAL INFORMATION

    1.1  COMMON NAME

    Chlorphoxim

    1.1.1 Identity:

    2-chloro-alpha
    -[[(diethoxyphosphinothioyl)ox]imino]benzeneacetonitrile

    1.1.2  Synonyms:

    CHEMICAL STRUCTURE

    Baythion C
    BAY 78,182
    SRA 7747
    OMS 1197

    Local synonyms:

    1.2  SYNOPSIS

    Chlorphoxim is an organophosphorus insecticide of low acute oral and
    dermal toxicity effective against many pests.

    1.3  SELECTED PROPERTIES

    1.3.1  Physical characteristics

    When pure white crystalline solid melting point 66.5°C.

    1.3.2  Solubility

    Almost insoluble in water, 2 ppm. Readily soluble in cyclohexanone,
    toluene and methylene chloride and to a lesser extent in
    isopropanol.

    1.3.3  Stability

    Decomposes below boiling point at normal pressure. Badly stored
    formulations could develop a smell of cyanide. Hydrolysed in
    alkaline solution.

    1.3.4  Vapour pressure (volatility)

    No information.

    1.4  AGRICULTURE, HORTICULTURE AND FORESTRY

    Chlorphoxim has not yet been developed for use in agriculture,
    horticulture or forestry.

    1.5  PUBLIC HEALTH PROGRAMMES:

    Chlorphoxim is effective against many public health pests such as
    Aedes spp., Anopheles spp., Culex spp., and Simulium spp.

    Two formulations are available, 200 g/l emulsifiable concentrate for
    spraying (including ULV application) and a 50% wettable powder.
    Recommended rates are 500-1500 ml of ULV concentrate Der hectare and
    the 50% wettable powder as a surface deposit at 4 g formulation/m2
    (2 g/m2 active ingredient).

    1.6  HOUSEHOLD USE:

    Not recommended for household use.

    2.  TOXICOLOGY AND RISKS

    2.1  TOXICOLOGY - MAMMALS

    2.1.1  Absorption route

    Absorbed from gastrointestinal tract and more slowly through intact
    skin.

    2.1.2  Mode of action

    Cholinesterase inhibition after conversion to the oxygen analogue
    (P = 0 chlorphoxim).

    2.1.3  Excretion

    No information.

    2.1.4  Toxicity, single dose

    Oral: LD50   Rat (M,F) > 2500 mg/kg
                 Mouse (M) > 1500 mg/kg       )
                       (F) > 10 000 mg/kg     )
                 Guinea pig > 1000 mg/kg      )
                 Cat > 1000 mg/kg             )    maximum tested
                 Dog > 1000 mg/kg             )
                 Rabbit > 1000 mg/kg          )
                                              )
    Dermal: LD50 Rat > 500 mg/kg              )

    Most susceptible species - No information

    2.1.5  Toxicity, repeated doses

    Inhalation: LC50 rat determined in a dynamic inhalation
    apparatus, with 4-hour exposure, active ingredient in alcohol +
    Lutrol (1:1): > 300 mg/m3; 20% concentrate > 1303 mg
    formulation/m3.

    Cumulation of compound: Chlorphoxim is not cumulative.

    Cumulation of effect: Repeated high exposure may produce a
    cumulative inhibitory effect on cholinesterase.

    2.1.6  Dietary studies

    Short-term: Rats of both sexes were fed oral doses of 0, 5, 15, 50
    and 150 mg/kg in the diet for three months. There was no inhibition
    of cholinesterase at the 50 mg/kg dose level but 150 mg/kg dose
    inhibited cholinesterase activity in plasma and erythrocytes. There
    was an insignificant increase in kidney weight of females at
    150 mg/kg.

    Four male and four female Beagle dogs were fed 0, 1, 10, and
    100 mg/kg in the diet for three months. Plasma cholinesterase was
    depressed in the 10 mg/kg dose group but significant depression of
    erythrocyte cholinesterase was observed only in the 100 mg/kg dose
    group. The no-effect level was 1 mg/kg.

    2.1.7  Supplementary studies of toxicity

    Carcinogenicity: No information.

    Teratogenicity: Rats, 6-15 days pregnant, were given doses of 40,
    80 or 150 mg/kg of chlorphoxim. No embryotoxicity or teratogenicity
    was observed.

    Neurotoxicity: Hens were treated orally and intraperitoneally. No
    neurotoxic symptoms observed.

    Mutagenicity: In a dominant lethal test on male mice using a dose
    of 500 mg/kg there was no indication of mutagenic activity.

    2.1.8  Modifications of toxicity

    No information.

    2.2  TOXICOLOGY - MAN

    2.2.1  Absorption

    Ingestion is likely to be the significant route of absorption in
    man. However, dermal absorption from Liquid concentrates could be
    important.

    2.2.2  Dangerous doses

    Single: Not known

    Repeated: Not known

    2.2.3  Observations on occupationally exposed workers

    A village-scale trial was carried out in 1972. No complaints were
    received and no adverse effects could be detected among exposed
    baggers, spraymen or inhabitants. There was no depression of
    whole-blood cholinesterase in spraymen or exposed residents.

    2.2.4  Observations on exposure of the general population

    No information.

    2.2.5  Observations on volunteers

    No information.

    2.2.6  Reported mishaps

    No information.  Poisoning in humans by chlorphoxim has not been
    reported.

    2.3  TOXICITY TO NON-MAMMALIAN SPECIES

    2.3.1  Fish

    Toxic to fish.

    The LC50 (96-hour exposure)
         for goldfish     100-150 mg/l
         carp             100-150 mg/l
         golden orfe      ca 10 mg/l
         mosquito fish    ca 6 mg/l
         red feather      ca 0.5 mg/l
         (Scardinius
         erythrophthalmus)

    2.3.2  Birds

    Oral LD50 Japanese quail  50-100 mg/kg
              Canary    about    200 mg/kg

    2.3.3  Other species

    No information.

    3.  FOR REGULATORY AUTHORITIES - RECOMMENDATIONS ON REGULATIONS
        OF COMPOUND

    3.1  RECOMMENDED RESTRICTIONS ON AVAILABILITY

    (for definition of categories, see introduction).

    Liquid formulations 20% and over and solid formulations over 40%,
    Category 4.

    All other formulations, Category 5.

    3.2  TRANSPORTATION AND STORAGE

    All formulations - Should be transported or stored in clearly
    labelled leakproof containers out of reach of children, away from
    food or drink.

    3.3  HANDLING

    Formulations in Category 4 - Adequate washing facilities should be
    provided at all times during handling and should be close to the
    site of the handling. Eating, drinking and smoking should be
    prohibited during handling and before washing after handling.

    Formulation in Category 5 - No facilities other than those
    required for the handling of any chemical.

    3.4  DISPOSAL AND/OR DECONTAMINATION OF CONTAINER

    All formulations - Containers may be decontaminated (for method
    see paragraph 4.3 in Part 4). Decontaminated containers should not
    be used for food and drink. Containers that are not decontaminated
    should be burned or should be crushed and buried below topsoil. Care
    must be taken to avoid subsequent contamination of water sources.

    3.5  SELECTION, TRAINING AND MEDICAL SUPERVISION OF WORKERS

    Formulations in Category 4 - Pre-employment medical examination
    and periodic cholinesterase test for workers desirable. Warning of
    workers to avoid contact essential.

    3.6  ADDITIONAL REGULATIONS RECOMMENDED IF DISTRIBUTED BY AIRCRAFT

    No special regulation recommended.

    3.7  LABELLING

    Formulations in Category 4 - Minimum cautionary statement:
    "Chlorphoxim is an organophosphorus compound which inhibits
    cholinesterase. It is of low toxicity but may be poisonous if

    swallowed. Keep the material out of reach of children and well away
    from foodstuffs, animal feed and their containers. If poisoning
    occurs call a physician. Atropine and pralidoxime are specific
    antidotes and artificial respiration may be needed".

    3.8  RESIDUES IN FOOD

    Chlorphoxim has not yet been considered by the Joint FAO/WHO Meeting
    on Pesticide Residues.

    4.  PREVENTION OF POISONING IN MAN AND EMERGENCY AID

    4.1  PRECAUTIONS IN USE

    4.1.1  General

    Chlorphoxim is an organophosphorus insecticide of low mammalian
    toxicity. It can be absorbed by ingestion, by inhalation of dust and
    to some extent, through intact skin. Although dermal absorption from
    diluted spray is of little significance, Absorption from liquid
    formulations such as the 20% ULV concentrate may be important. In
    dilute liquid formulations the vehicle (solvent) may be more toxic
    than the insecticide.

    4.1.2  Manufacture and formulation

    Although volatility is low, vapour and dust should be controlled. 
    Protective equipment for skin and respiratory protection may be
    desirable.

    4.1.3  Mixers and applicators

    When opening the container and when mixing, care should be taken to
    avoid contact with the mouth and eyes. If necessary a facial visor
    and gloves should be worn. Mixing, if not mechanical, should always
    be carried out with a paddle of appropriate length. Splashes should
    be washed immediately from the skin of 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 chlorphoxim and associated with its application
    should observe the precautions described above in 4.1.3 under
    "Mixers and applicators".

    4.1.5  Other populations likely to be affected

    Populations are not likely to be exposed to hazardous amounts of
    phoxim during properly conducted public health spraying.

    4.2  ENTRY OF PERSONS INTO TREATED AREAS

    Persons may enter treated areas as soon as the spray has dried
    without being exposed to hazardous amounts of chlorphoxim.

    4.3  DECONTAMINATION OF SPILLAGE AND CONTAINERS

    Residues in containers should be emptied in a diluted form into a
    deep pit taking care to avoid ground waters. The empty container may
    be decontaminated by rinsing two or three times with water and
    scrubbing the sides. An additional rinse should be carried out with
    5% sodium hydroxide solution which should remain in the container
    overnight. Impermeable gauntlets should be worn during this work and
    a soakage pit should be provided for the rinsing. Decontaminated
    containers should not be used for food and drink. Spillage of
    chlorphoxim and its formulations should be removed by washing with
    5% sodium hydroxide solution and then rinsing with large quantities
    of water.

    4.4  EMERGENCY AID

    4.4.1  Early symptoms of poisoning

    Early symptoms of poisoning following the ingestion of chlorphoxim
    may include excessive sweating, headache, weakness, giddiness,
    nausea, vomiting, stomach pains, blurred vision, slurred speech, and
    muscle twitching. If a massive dose has been swallowed there may be
    convulsion, 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

    If swallowed, vomiting should be induced if the person is conscious.
    In the event of collapse, artificial respiration should be given.

    5.  FOR MEDICAL AND LABORATORY PERSONNEL

    5.1  MEDICAL DIAGNOSIS AND TREATMENT OF CASES OF POISONING

    5.1.1  General information

    An organophosphorus insecticide of low mammalian toxicity which can
    be absorbed by ingestion by inhalation and to some extent through
    intact skin. Although dermal absorption from diluted spray may not
    be significant absorption from high concentration liquid
    formulations may be important. In dilute formulations the vehicle
    (solvent) may be more toxic than the insecticide. Chlorphoxim itself
    is a weak inhibitor of acetyl cholinesterase but is metabolized to a
    more active inhibitor which is then quickly inactivated and the
    metabolites excreted in the urine. Poisoning in man has not yet been
    reported.

    5.1.2  Symptoms and signs

    Based upon studies and upon symptoms of poisoning from other
    organophosphorus pesticides, initial symptoms of poisoning may
    include excessive sweating, headache, weakness, giddiness, nausea,
    vomiting, stomach pains, blurred vision, slurred speech and muscle
    twitching. In the event of ingestion of an excessive dose more
    severe symptoms of poisoning may be convulsions, coma, loss of
    reflexes and loss of sphincter control.

    5.1.3  Laboratory

    The most important finding is reduction in activity of blood
    cholinesterase.

    5.1.4  Treatment

    If pesticide has been ingested, unless the patient is vomiting,
    rapid gastric lavage should be performed using 5% sodium
    bicarbonate, if available. In spite of the low dermal toxicity after
    skin contact, it is advisable to wash the skin with soap and water.
    If the compound has entered the eyes, they should be washed with
    plenty of water. Persons without signs of respiratory inefficiency
    but with manifest peripheral symptoms should be treated with 2-4 mg
    of atropine sulfate and 100-2000 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 at the same time as
    atropine sulfate.

    The airways should be kept free and artificial respiration if
    necessary should be applied, preferably by mechanical means. If
    necessary, intubation should be performed.

    Contraindicated are morphine, barbiturates, phenothiazine
    tranquillizers and central stimulants of all kinds.

    5.1.5  Prognosis

    As there have been no reports of poisoning of man with chlorphoxim
    the prognosis is not known. By analogy with moderately toxic
    organophosphorus compounds it may be assumed that if the acute toxic
    effect is survived the chances of complete recovery are good. In
    very severe cases following the ingestion of a massive dose of
    chlorphoxim it is possible that without adequate artificial
    respiration prolonged hypoxia could give rise to permanent brain
    damage.

    5.1.6  References of previously reported cases

    None

    5.2  SURVEILLANCE TESTS

    
    Test                         Normal level    Action level   Symptomatic level

    Plasma cholinesterase           100%1             50%           variable

    Erythrocyte cholinesterase      100%              70%         usually < 40%

    

              
    1Percentage of pre-exposure activity by any test.

    5.3  LABORATORY METHODS

    References are given only.

    5.3.1  Detection and assay of compound

    A GLC method for analysis of residues of phoxim in plants using a
    thermionic phosphorus detector is likely to be applicable to the
    analysis of chlorphoxim and is available from Bayer, Leverkusen.
    [Dräger, G. (1969) Pflantzenschutz Nachrichten 22, No. 3, 301]

    5.3.2  Other tests in cases of poisoning

    Levels of cholinesterase in blood 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., Andreas, V. Jr &
    Featherstone, R. M. (1961) Biochem., Pharmacol., 7, 88-95.


                                    * * *

See Also:
        Chlorphoxim (PIM 751)