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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.

                                  THALLIUM SULFATE

    Part 1 - General information         


           Primary use: rodenticide
           Secondary uses: insecticide 
           Chemical group: heavy metal salt 
           Data sheet No. 10 
           Date issued: June 1975 

    1.1   COMMON NAME: as the chemical name is short, no common name has
          been established.

          Identity: thallium sulfate

                    Tl2 SO4

          Synonyms                                  Local synonyms 
          thallous sulfate

    1.2   SYNOPSIS: a heavy metal salt of high mammalian toxicity which is 
    used mainly as rodenticide.  Its main hazard is as a chronic poison due 
    to its cumulation especially in liver, brain and skeletal muscle.  It 
    is readily absorbed from the gastrointestinal tract and is also 
    absorbed through the intact skin. 


    1.3.1 Physical characteristics: a colourless crystalline solid or 
    white powder m.p. 362°C.  It is odourless. 

    1.3.2 Solubility: water at 20°C, 4.87%.

    1.3.3 Stability: highly stable in solution under all conditions of 
          temperature and pH. Corrosive to zinc.

    1.3.4 Vapour pressure (volatility) very low.


    1.4.1 Common formulations

    The technical material is incorporated into solid or liquid baits, 
    usually at concentrations of about 1% or less.  Grain baits for rodent 
    control may contain up to 2%. 

    1.4.2 Susceptible pests

    Main use is against rats.  Also used to control mice, squirrels,
    prairie dogs, moles and water voles.  Its main insecticidal use is to 
    control ants and it is also used against cockroaches. 

    1.4.3 Use pattern

    For rodent control baits are usually laid and removed after 24 hours.  
    In the United States of America regular "bait stations" are maintained 
    where rodents feed: they do not become bait-shy.  Grain baits have been 
    distributed by aircraft for squirrel control.  Ants are controlled in 
    the United States of America by sweet baits containing 0.5% thallium.  
    Thallium sulfate is normally used only by pest control operators or 
    other trained personnel and in many countries its sale and use are 
    legally restricted. 

    1.4.4 Unintended effects

    Livestock, domestic animals and wildlife have been poisoned. 
    Carnivorous mammals and predatory and scavenger birds (especially 
    eagles) have been killed by secondary poisoning, sheep by eating bait, 
    and grain-eating birds and mammals by eating thallium-treated grain 
    used for squirrel control. 

    Thallium sulfate is a cumulative soil sterilant.  It is extremely
    phytotoxic and inhibits germination of seeds.


    Has been used for commensal rodent control but is considered too
    toxic for use where non-target animals or man may come in contact.

    1.6    HOUSEHOLD USE

    The chronic hazard and very dangerous properties of thallium sulfate 
    make it unsafe for household use except by professional pest control 
    operators in special circumstances.  In many countries, strict control 
    of the sale and use of the compound prevent its application in any 
    other way. 
                                  THALLIUM SULFATE

    Part 2 - Toxicology and risks        

             Common name:  thallium sulfate
             Data sheet No. 10
             Date issued:  June 1975

    2.1.1 Absorption route: the oral route is the most important in cases
    of poisoning; however, dermal absorption may occur.  Solutions of
    thallium salts in water are tasteless, hence the opportunities for
    accident or misuse. 

    2.1.2 Mode of action: unknown, although there is some suggestion that
    it may interfere with the metabolism of potassium inside cells.

    2.1.3 Excretion products: excreted as thallium salts mainly by the
    kidney, but also to some extent into the intestine.

    2.1.4 Toxicity, single dose

          Oral: LD50 rat (M): 10.6 mg/kg

          Dermal: LD50 rat (M)14 hours: > 1000 mg/kg.  
          7 days:  500 mg/kg

          Inhalation: not known

          Most susceptible species: not known

    2.1.5 Toxicity, repeated doses

          Oral: Rat: the daily oral administration of thallium acetate to
          rats at less than 1/50 of the single LD50 caused depilation in 
          six weeks and death within four months. 

          Dermal: no information.

          Inhalation: no information.

          Cumulation of compound: thallium is cumulative in all tissues 
          of the body, especially in liver, brain and skeletal muscle. 
          About 70% of a given dose is excreted in one month. 

          Cumulation of effect: the chronic toxicity of thallium is due 
          to the cumulation of the element in the body. 

    2.1.6 Dietary studies

          Short-term: no information.

          Long-term: no information.

    2.1.7 Supplementary studies of toxicity: no information.

    2.1.8 Modifications of toxicity: no information.

    2.2   TOXICOLOGY - MAN

    2.2.1 Dangerous doses

          Single: the fatal dose is reported to be < 500 mg. 

    2.2.2 Observations of occupationally exposed workers: no information.
    2.2.3 Observations on exposure of the general population: no 

    2.2.4 Observations of volunteers: no information.

    2.2.5 Reported mishaps

    Of 778 cases of thallium poisoning reported, 6% were fatal.  Thallium 
    acetate was formerly used as a depilatory in children at a single oral 
    dose of 8 mg/kg.  Serious poisoning including six deaths was found in 
    5.5% of 8006 cases. 

    By repeated testing of the urine of 193 patients with accelerated 
    hair loss, 43 cases of mild chronic thallotoxocosis were found.  The 
    apparent sources were the home use of thallium by professional 
    exterminators and patients and by the ingestion of contaminated foods. 


    The entries in these sections are intended to draw attention to 
    special risks and to give warnings of any needs for special 

    2.3.1 Fish

          Moderately toxic to some species.

    2.3.2 Birds

    Poisonous to birds. Direct poisoning of grain-eating birds by treated 
    grain used for squirrel control has occurred. Predatory and scavenger 
    birds can be killed by secondary poisoning. 

    2.3.3 Other species

    Data on other non-mammalian species are lacking.  There should be no 
    hazard in practice owing to the very restricted conditions of 
    recommended use. 

                                  THALLIUM SULFATE

    Part 3 - For regulatory authorities  

         Common name: thallium sulfate
         Data sheet No. 10
         Date issued:  June 1975


          (For definition of categories see introduction.)  

          All formulations: category 2. 


          All formulations

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

    3.3   HANDLING

          All formulations

    Full protective clothing (see Part 4) should be provided for all
    handling of the compound.  Adequate washing facilities should be 
    available at all times during handling and should be close to the site 
    of handling and before washing after handling.  Baits of thallium 
    sulfate should be removed and the area thoroughly cleaned up after the 
    necessary purpose has been fulfilled. 


          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

    Factory workers and formulations: pre-employment medical examination 
    of workers necessary.  Regular periodic special medical examinations 
    advisable.  Special account should be taken of the workers' mental 
    ability to comprehend and follow instructions. Training of workers in
    techniques to avoid contact essential. 

    Field workers: regular special medical examination advisable but 
    often not practical as a routine.  Training of workers in techniques to 
    avoid contact essential. 


          Not applicable.

    3.7   LABELLING

          All formulations

          Minimum cautionary statement:

                          (Skull and crossbones insignia)

          "Thallium sulfate is a highly toxic heavy metal salt which is 
          cumulative in body tissues.  It is poisonous if swallowed and may 
          be absorbed through the skin.  Avoid skin contact; wear 
          protective gloves and clean protective clothing when handling 
          this material. Bathe immediately after work. 

          Ensure that containers are stored under lock and key.  Empty
          containers must be disposed of in such a way as to prevent all 
          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."


    Levels have not been recommended by the Joint FAO/WHO meeting on 
    Pesticide Residues. If used correctly as a bait, residues of thallium 
    will not appear in human food. 

                                  THALLIUM SULFATE

    Part 4 - Prevention of poisoning in man and emergency aid

             Common name: thallium sulfate
             Data sheet No. 10
             Date issued: June 1975                         


    4.1.1 General

    Thallium sulfate is a heavy metal salt of high toxicity which is
    cumulative in body tissues.  Most formulations should be handled by 
    trained personnel wearing protective clothing. 

    4.1.2 Manufacture and formulation 


          ACGIH 0.1 mg/m3; USSR 0.01 mg/m3 (bromide or iodide only

    Closed systems and forced ventilation may be required to reduce as 
    much as possible the exposure of workers to the chemical.  All 
    formulations should be coloured with a warning dye. 

    4.1.3 Mixers and applicators

    When opening the container and when mixing, protective impermeable 
    boots, clean overalls, gloves and a face mask should be worn.  Mixing, 
    if not mechanical, should always be carried out with a paddle of 
    appropriate length.  The applicator should avoid inhaling dust 
    particles and avoid contact with the mouth.  Particular care is needed 
    when the equipment is being washed after use.  All protective clothing 
    should be washed immediately after use including the insides of 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. 

    Thallium sulfate should not be used in dwelling houses.  Baits should 
    not be used where there is risk of contaminating food, animal feeding 
    stuffs or drinking or washing water.  Exposed baits should be laid in 
    containers clearly marked "Poison".  Baits should not be laid unless 
    all access by children and animals other than rats and mice can be 
    prevented.  Except in locked unoccupied premises baits should not 
    remain down for more than 24 hours.  All exposed baits and their 
    containers should be removed after treatment and burned.  Rodent bodies 
    should be searched for and destroyed by burning. 

    4.1.4 Other associated workers (including flagmen in aerial operations)

          Not applicable.

    4.1.5 Other populations likely to be affected

    With correct use as described under mixers and applicators (4.1.3 
    above) other populations should not be exposed to hazardous amounts of 
    thallium sulfate. 


        Adults may enter premises where baits have been laid provided 
        sufficient warning has been given and all exposed baits are marked 


    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 should be removed as much as 
    possible into a deep dry pit and the remainder washed away with large 
    quantities of water. 


    4.4.1 Early symptoms of poisoning

    Signs and symptoms of acute thallium poisoning are referrable mainly 
    to the gastrointestinal tract and nervous system.  After large doses, 
    gastroenteritis is evident in about 12-14 hours while neurological 
    symptoms may be delayed two to five days. Gastrointestinal 
    manifestations include severe paroxysmal abdominal pain, vomiting, 
    diarrhoea, anorexia, stomatitis, salivation and weight loss.  
    Neurological manifestations during the first days of illness may 
    include paresthesias, headache, cranial nerve damage, convulsions, 
    delirium and coma. 

    In chronic poisoning symptoms can be non-specific except for loss of 
    hair which occurs, and which is very specific for thallium 

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

    Due to the delayed appearance of symptoms it is unlikely that 
    specific symptoms will be seen directly following exposure.  If 
    swallowed vomiting should be induced if the person is conscious. 

                                  THALLIUM SULFATE

    Part 5 - For medical and laboratory personnel  

              Common name: thallium sulfate
              Data sheet No. 10
              Date issued:  June 1975


    5.1.1 General information

    A heavy metal salt of high toxicity which is especially hazardous 
    because of its cumulative properties.  The element tends to concentrate 
    in liver, brain and skeletal muscle.  It is readily absorbed from the 
    gastrointestinal tract and may also be absorbed through the intact 

    5.1.2 Symptoms and signs

    Signs and symptoms are referable mainly to the gastrointestinal tract 
    and nervous system.  After large doses, gastroenteritis is evident in 
    about 12 to 14 hours, while neurological symptoms may be delayed two to 
    five days.  Gastrointestinal manifestations include severe paroxysmal 
    abdominal pain, vomiting, diarrhoea, anorexia, stomatitis, salivation, 
    and weight loss.  Neurological manifestations during the first days of 
    illness may include paresthesias, headache, cranial nerve damage, 
    convulsions, delirium and coma.  Vascular collapse and death may occur 
    in 24 to 48 hours, but the course is usually more prolonged.  Death may 
    be caused by respiratory paralysis, pneumonia, or circulatory 
    disturbances.  Peripheral neuropathy, particularly in the legs, is 
    common with severe pain, paresthesias, muscle weakness, and atrophy.  
    Loss of hair begins after one to two weeks have elapsed.  In the more 
    protracted cases, ataxia, choreiform movements, dementia, depression, 
    and psychosis may be prominent.  A blue gingival line and 
    dermatological abnormalities, including white bands in the nails may 
    appear.  Neurologic damage may be permanent.  Liver damage occurs but 
    is not prominent clincally.  Kidney damage is manifested by 
    proteinuria, cylindruria, and sometimes oliguria and haematuria. 

    With the continued administration of smaller doses, symptoms may 
    first be apparent in a week with progression for several more weeks. In 
    chronic poisoning, symptoms can be nonspecific and thallium 
    intoxication may not be suspected unless depilation occurs.  Although 
    characteristic of thallium toxicity, hair loss also can result from 
    poisoning with other metals and certain drugs. 

    5.1.3 Laboratory

    Diagnosis can be confirmed by analysis for thallium in urine, blood, or 
    hair.  Thallium does not occur normally in body fluids or tissue; 
    however, its presence in urine does not necessarily mean intoxication.  
    In fatal, acute and subacute cases, the concentration of thallium in 
    tissue ranges from five to 100 ppm.  Thallium can be found in the urine 
    for as lone as two months after intoxication.  Other laboratory 
    determinations are not specific.  The blood picture and the 
    cerebrospinal fluid are usually normal.  Tests of liver function have 
    been abnormal in a few instances. 

    5.1.4 Treatment

    If an acute dose of thallium sulfate has been ingested, gastric lavage 
    should be done with 2-4 l of water.  Activated charcoal and potassium 
    iodide should be given orally to reduce thallium absorption.  Sodum 
    thiosulfate may be given intravenously to inactivate any thallium in 
    the blood but its usefulness has not been proved.  The value of 
    chelating agents is questionable.   It is generally felt that EDTA or 
    BAL are not useful in treatment of thallium intoxication.   However, 
    dithizon (diphenylthiocarbazone) 10 mg/kg twice a day for four days or 
    longer has   been effective.  Other recommended forms of treatment 
    include haemodialysis and forced diuresis and administration of 
    Prussian Blue. 

    5.1.5 Prognosis

    Prognosis depends largely upon the severity of the intoxication and 
    also the nature.  If the effects of an acute dose are overcome, the 
    chances of complete recovery are good.  However, neurological damage 
    may be permanent in severe cases. 

    5.1.6 References of previously reported cases
    The following references give methods of treatment used in cases of 

    Hayes, W. J., jr (1963) Clinical handbook on economic poisons, U.S.
          Publ.  Hlth Ser. Publn., No. 476, p. 84 

    Mathews, J. & Anzarat, A. (1968) Canad. Med. Ass. J., 99, 72-75

    Piazolo, H. E. et al. (1971) Deutsche Medizinische Wochenschrift 96, 
          1217, Van der Merwč, C. F. (1972) Sth Afr. med. J., 46, 960


    Urinary levels of thallium in the range of 0.5-7.5 ppm have been
    reported as being indicative of poisoning.


          References only are given.

    5.3.1 Detection and analysis

     A number of simple methods are briefly outlined by Anderson (1953). 

    A colorimetric method for determining thallium in urine is described 
    by Ariel & Bach (1963) and a rapid spectrographic determination by 
    Farhan et al. (1969). 

    A very sensitive method enabling the determination of 3 µg of 
    thallium in 50-100 µl of urine is given by Curry et al. (1969). 

    5.3.2 Other tests in cases of poisoning


    Anderson, J. R. A. (1953) Detection and determination of thallium, 
          Analyt.  Chem., 25, 108 

    Ariel, M. & Bach, D. (1963) The determination of thallium in urine, 
          Analyst, 88, 30

    Farhan, F. M., Eyvani, J. & Atabakhsh, J. (1969) Direct spectrographic 
          determination of traces of thallium in urine, Toxicol. Appl. 
          Pharmacol., 15, 493 

    Curry, A. S., Read, J. F. & Knott, A. R. (1969) Determination of 
          thallium in biological material by flame spectrophotometry and 
          atomic absorption, Analyst, 94, 744