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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/80.46

                                                      ORIGINAL: ENGLISH






    DATA SHEETS ON PESTICIDES No. 46

    PHOSPHINE






         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: Insecticidal fumigant

                                  Secondary use: Rodenticide

                                  Chemical group:  Phosphide

                                  Date issued:

    1.  GENERAL INFORMATION

    1.1  COMMON NAME:

    Phosphide

    1.1.1  Identity:

    Hydrogen phosphide, PH3

    1.1.2  Synonyms:

    Phosphorus trihydride
    Phosphoretted hydrogen

    Local synonyms: Phosphine for use in pest control is usually
    generated from phosphide salts. One synonym for this is
    Phostoxin(R).

    1.2  SYNOPSIS:

    A gas of very high mammalian toxicity which affects the
    gastrointestinal tract and central nervous system, without
    cumulative effect. It is used for the fumigation of insect pests of
    stored grains and is released by exposure of phosphide tablets to
    moist atmosphere.

    1.3  SELECTED PROPERTIES

    1.3.1  Physical characteristics

    A colourless, inflammable gas with carbide or fish-like odour, B.p.
    87.4°C, f.p. 132.5°C.

    1.3.2  Solubility

    Slightly soluble in water: 228 ml gaseous phosphine/l at 17°C.

    1.3.3  Stability

    Spontaneously flammable in air with a lower explosion limit of 26.15
    to 27.06 g/m2.

    1.3.4  Vapour pressure

    Not applicable. Phosphine odour (decaying fish) is detectable at
    1.5-3 ml/m3 of air.

    1.4  AGRICULTURE, HORTICULTURE AND FORESTRY:

    No specific use except for the fumigation of stored products to
    which the paragraphs below apply.

    1.4.1  Common formulations

    As aluminium phosphide or other salts in tablets, pellets, and
    powder in bags. These are usually used in phosphine generators in
    which the salts are exposed to moisture.

    1.4.2  Susceptible pests

    All insects and their developmental stages: mites and rodents.

    1.4.3  Use pattern

    For fumigation of stored food products in gas tight areas: sacked
    goods 0.75-1.5 g/m3 of piles, grain in silos 1-3 g/tonne.

    1.4.4   Unintended effects

    No information.

    1.5  PUBLIC HEALTH PROGRAMMES

    No recommended use.

    1.6  HOUSEHOLD USE

    No recommended use.

    2.  TOXICOLOGY AND RISKS

    2.1  TOXICOLOGY - MAMMALS

    2.1.1  Absorption route

    Absorbed by inhalation of gas and from the gastrointestinal tract
    after ingestion of a salt (as aluminium calcium or zinc phosphide). 
    It is not absorbed percutaneously.

    2.1.2  Mode of action

    Not clear: possibly phosphorylation of enzymes.

    2.1.3  Excretion products

    See also data sheet No. 24, zinc phosphide. Phosphine is easily
    oxidized; it is excreted in urine either as a hypophosphite or as
    dissolved phosphine. Other metabolites include phosphoric acid and
    phosphate; it can also be exhaled from the lungs.

    2.1.4  Toxicity, single dose

    Oral: Not applicable in gaseous form: as zinc phosphide, rat:
    41 mg/kg.
    Inhalation of phosphine gas.
    Rat: LC50 0.68 g/m3 - 65-75 minutes exposure.
              1.47 g/m3 35-50 minutes exposure.

    Cat: LC50 25 ppm - 2-4 hours daily during three days.

    2.1.5  Toxicity; repeated doses:

    Inhalation: Cats, guinea pigs and rats were exposed to 1.4 or
    3.5 mg phosphine/m3 for more than 800 hours. No haemolysis or
    formation of methemoglobin was observed in the erythrocytes or
    haemoglobin. There was no evidence of cumulative poisoning. It has
    been suggested that, at these levels, an equilibrium is attained
    between the intake of phosphine and the detoxification and excretion
    and cell repair. The threshold for behavioural changes and
    alterations in blood parameters and liver function was 7 mg/m3 in
    air.

    Cumulation of compound: Phosphine is not cumulative in body
    tissues.

    Cumulation of effect: See 2.1.5.

    2.1.6  Dietary studies

    Short-term: Rats fed with grain which had been fumigated at
    excessive dosages, showed no ill effects, even when the grain was
    not cleaned before consumption.

    Long-term: Rats were fed for two years a diet exposed to high
    concentrations of phosphine released from aluminium phosphide
    pellets. Behaviour, general appearance, survival, body weight, food
    consumption, haematology, blood chemistry, urine analyses and bone
    marrow data, as well as gross and microscopic findings and rate of
    tumour development did nor reveal any toxic effects.

    Supplementary studies of toxicity

    Carcinogenicity: see 2.1.6.

    Teratogenicity: No information.

    2.1.8  Modification of toxicity.

    No information.

    2.2  TOXICOLOGY - MAN

    2.2.1  Absorption

    Inhalation of phosphine gas or ingestion of phosphide formulations
    are main routes of absorption.

    2.2.2  Dangerous doses

    Single: 9.8 mg phosphine/m3 air gives rise to grave symptoms
    after several hours. 14 1 280 mg/m3 are tolerated for 60 minutes.
    560 mg/m3 is lethal in 60 minutes - 2.8 g phosphine/m3 is lethal
    in a short time.

    Repeated: A review of 59 poisonings suggests that the minimum
    lethal concentration in air is 7-14 mg/m3 inhaled for two or four
    hours for several days.

    2.2.3  Observations of occupationally exposed workers

    Although phosphine is highly toxic, cases of poisoning are rare and
    generally due to careless handling.

    2.2.4  Observations on exposure of the general population

    With good practice in stored food fumigation the general population
    will not be exposed to phosphine.

    2.2.5  Observations of volunteers

    None.

    2.2.6  Reported-mishaps

    One fatal and three non-fatal accidental cases of phosphine
    poisoning are reported due to an unprofessionally performed
    fumigation of stored grain on a tug boat using aluminium phosphide
    tablets. Six hundred and seventy-five tablets (675 g of PH3) were
    used for the fumigation of 500 t of oats.

    Two families with four children who were moved before the fumigation
    returned to the area 72 hours afterwards. The onset of the poisoning
    signs occurred 24 hours afterwards and the next day one child aged
    six, died while being transported to the hospital.

    2.3  TOXICITY TO NON-MAMMALIAN SPECIES

    2.3.1  Fish

    No data available but solubility in water slight.

    2.3.2  Birds

    No data available.

    2.3.3  Other species

    Frog LC50: 0.56 mg/l for 30 minutes
               0.84 mg/l for 15 minutes.

    3.  FOR REGULATORY AUTHORITIES - RECOMMENDATIONS ON REGULATION OF
        COMPOUND

    Phosphine is not used as such, but is generated by action of moist
    air on aluminium phosphide and other salts.

    3.1  RECOMMENDED RESTRICTIONS ON AVAILABILITY

    (For definition of categories, see introduction).

    All formulations, Category 2

    3.2  TRANSPORTATION AND STORAGE

    All formulations - Should be transported and stored in clearly
    labelled, hermetically sealed containers; away from sunlight,
    oxidizing agents, acids; away from living quarters, under lock and
    key, and secure from access by unauthorized persons and children.
    They must not be stored in damp condition or allowed to become damp. 
    No food or drink should be stored in the same compartment.

    3.3  HANDLING

    All formulations - Full respirator protection should be used by
    all those handling this compound. Adequate washing facilities should
    be available at all times during handling and should be close to the
    site of handling. Eating, drinking and smoking should be prohibited
    during handling and before washing after handling. Keep well away
    from naked lights.

    3.4  DISPOSAL AND/OR DECONTAMINATION OF CONTAINER

    Containers must be either burned or crushed and buried below
    topsoil. Decontamination of containers in order to use them for
    other purposes should not be permitted.

    3.5  SELECTION, TRAINING AND MEDICAL SUPERVISION OF WORKERS

    All formulations - Pre-employment and routine medical examination
    of workers desirable. Workers suffering from active hepatic renal or
    haematological disease should be excluded from contact. Special
    account should be taken of workers' mental ability to comprehend and
    follow instructions. Training of workers in respiratory protection
    is essential.

    3.6  ADDITIONAL REGULATIONS RECOMMENDED IF DISTRIBUTED BY AIRCRAFT

    All formulations - Not applicable.

    3.7  LABELLING

    All formulations - Minimum cautionary statement - "POISON" (skull
    and cross-bones insignia). Aluminium phosphide is a very toxic
    substance. Do not inhale dust or fumes. Keep this material out of
    reach of children and domestic animals and well away from
    foodstuffs, animals feed and their containers. Keep dry; away from
    sunlight and acids of all kinds. Open only in open air and keep away
    from naked lights. No smoking allowed in vicinity.

    3.8  RESIDUES IN FOOD

    Preparations of aluminium phosphide which evolve hydrogen phosphide
    by reaction with moisture in the surrounding atmosphere are used for
    the post-harvest fumigation of a wide range of produce including
    processed foods. The powder remaining after the use of the fumigant
    preparation is mainly aluminium hyroxide, but may contain a small
    amount (up to 5%) of the original content of aluminium phosphide.
    The normal cleaning of cereals before milling is effective in
    eliminating almost all of this powder. For other foods which cannot
    be so cleaned before processing, good practice requires that the
    fumigant preparation residues does not come into contact with the
    food.

    3.8.1  Maximum residue levels

    Maximum residue levels have been recommended 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

    Aluminium phosphide decomposes on exposure to humidity to liberate
    phosphine gas which is highly hazardous. It is readily absorbed from
    the gastrointestinal tract and dust may be absorbed by inhalation. 
    It is not readily absorbed through the intact skin.

    4.1.2  Manufacture and formulation

    T.L.V.: 0.3 mg/m3 (USSR) 0.1 mg/m3 (ACGIH). Closed systems and
    forced ventilation are required to reduce as much as possible the
    exposure of workers to the chemical.

    4.1.3  Applicators

    Particularly when opening the container, boots, clean overalls,
    gloves and respirator must be worn. All protective clothing should
    be washed immediately after use and respirator filtres must be
    regularly renewed. Before eating, drinking or smoking, hands and
    other exposed skin should be washed.

    4.1.4  Other associated workers including flagmen in aerial
           operations)

    Not applicable.

    4.1.5  Other populations likely to be affected

    With good practice, the general population will not be exposed to
    phosphine after the use of the fumigant preparation.

    4.2  ENTRY OF PERSONS INTO TREATED AREAS

    After adequate ventilation after use, treated areas should be
    checked for residual gas concentrations before any unprotected
    persons enter these areas.

    4.3  DECONTAMINATION OF SPILLAGE AND CONTAINERS

    Residues in containers should be buried in a deep well away from any
    habitation and taking care to avoid contamination of ground waters.
    Decontamination of containers in order to use them for other
    purposes should not be permitted. Spillage shot d be removed as much
    as possible into a deep dry pit as above and the remainder washed
    away with large quantities of water. It should be borne in mind that

    during these operations and in the presence of water, phosphine gas
    will be liberated and therefore a respirator must be worn, and the
    whole area of spillage thoroughly aerated until checked for zero gas
    concentration.

    4.4  EMERGENCY AID

    4.4.1  Early symptoms of poisoning

    Earliest symptoms are usually nausea, abdominal pain, vomiting and
    diarrhoea, dyspnoea, chilliness, thirst, headache which may be
    followed by convulsions or coma.

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

    The person should stop work and move away from the area of treatment
    into fresh air. If swallowed, vomiting should be induced if the
    person is conscious. The person should be kept at complete rest
    until the physician arrives.

    5.  FOR MEDICAL AND LABORATORY PERSONNEL

    5.1  MEDICAL DIAGNOSIS AND TREATMENT IN CASES OF
    POISONING

    5.1.1  General information

    Upon exposure to moisture, aluminium phosphide liberates phosphine,
    a gas of very high toxicity which affects the gastrointestinal tract
    and central nervous system. It is readily absorbed by inhalation and
    from the gastrointestinal tract, but not through the skin.

    5.1.2  Symptoms and signs

    Earliest symptoms are usually restlessness and fatigue, disturbances
    of speech, vision and gait, nausea, abdominal pain, vomiting and
    diarrhoea, headache, thirst, chilliness. Respiratory symptoms
    include dyspnoea, tightness of the chest and pulmonary oedema. These
    may be followed by convulsions and coma. Death may occur from heart
    failure within four days or be delayed one to two weeks. Chronic
    inhalation of subtoxic doses has been said to lead to toothache,
    swollen jaw and mandibular necrosis. Other symptoms are anorexia and
    weight loss, anaemia and a tendency to spontaneous bone fracture.
    The patient's breath may smell of phosphine (fish-like odour) and
    there may be coughing with green, fluorescent sputum.

    5.1.3  Laboratory

    No specific test is known to confirm exposure.

    5.1.4  Treatment

    Treatment is mainly symptomatic. If ingested, vomiting should be
    induced immediately followed by gastric lavage with two to four
    litres of water. Acute pulmonary oedema should be treated by oxygen
    inhalation and prophylactic penicillin. The patient should be kept
    at rest.

    5.1.5  Prognosis

    If the patient survives for four days the prognosis is good.
    However, recovery is slow and there may be irreversible lesions of
    the kidneys and liver.

    5.1.6  References of previously reported cases

    Cases of poisoning are documented in: Harper, R. N. & Spolyar, L. W.
    (1958) Archs. Industr. Hlth, 18, 497. Sovljanski, R. et al. (1969)
    Arhiv. Big. Rada Toksi. 20 (2), 209. Van Oettingen, E. W. The
    toxicity and potential dangers of zinc phosphide and of hydrogen
    phosphide, Public Health Report, 203.1, 1947.

    5.2  SURVEILLANCE TESTS

    There are no readily available surveillance procedures to determine
    the degree of absorption prior to the appearance of symptoms.

    5.3  LABORATORY METHODS

    References only are given.

    5.3.1  Detection and assay of compound

    For the estimation of phosphine in air, aspirate through mercurous
    chloride solution and note the change of pH: Taylor (1968). Very low
    concentrations of phosphine in air can also be detected by gas
    chromatography: see Dumas (1969) and Berck (1970).

    5.3.2  Other tests in cases of poisoning

    Estimation of methaemoglobin.

                                    = = =


    See Also:
       Toxicological Abbreviations
       Phosphine (HSG 28, 1989)
       Phosphine (ICSC)
       Phosphine (PIM 865)