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    TELLURIUM HEXAFLUORIDE




    WN Harrison PhD CChem MRSC
    SM Bradberry BSc MB MRCP
    S Meacham BSc
    JA Vale MD FRCP FRCPE FRCPG FFOM

    National Poisons Information Service
    (Birmingham Centre),
    West Midlands Poisons Unit,
    City Hospital NHS Trust,
    Dudley Road,
    Birmingham
    B18 7QH


    This monograph has been produced by staff of a National Poisons
    Information Service Centre in the United Kingdom.  The work was
    commissioned and funded by the UK Departments of Health, and was
    designed as a source of detailed information for use by poisons
    information centres.

    Peer review group: Directors of the UK National Poisons Information
    Service.


    TELLURIUM HEXAFLUORIDE

    Toxbase summary

    Type of product

    Tellurium hexafluoride is a gas at room temperature and is used as a
    chemical reagent.

    Toxicity

    Acute poisoning is rare. Due to its gaseous nature, inhalation and
    topical exposure are most likely. Ingestion has not been reported.

    Features

    Topical

         -    Irritant to skin and eyes.
         -    May cause dermal discolouration.

    Inhalation

          -   A garlic odour to the breath, sweat and urine is
              characteristic of tellurium exposure.
         -    A metallic taste, nausea, loss of appetite, tiredness,
              reduced sweating and unspecified ECG changes have been
              reported.
         -    May cause respiratory tract irritation, although reports of
              significant pulmonary toxicity are rare.

    Management

    Dermal

    1.   If possible the patient should remove soiled clothing and wash
         him/herself.
    2.   Wash contaminated hair and skin with soap and copious amounts of
         water.
    3.   Pay special attention to skin folds, fingernails and ears.

    Ocular

    1.   Immediately irrigate the affected eye thoroughly with tepid water
         or 0.9 per cent saline for at least 10-15 minutes.
    2.   Any particles lodged in the conjunctival recesses should be
         removed.
    3.   Continue irrigation with saline infusion using drip tubing.
    4.   Repeated instillation of local anaesthetic may reduce discomfort
         and help more thorough decontamination.
    5.   Corneal damage may be detected by instillation of fluorescein.

    6.   Patients with corneal damage and those whose symptoms do not
         resolve rapidly should be referred for ophthalmological
         assessment.

    Inhalation

    1.   Remove from exposure
    2.   Treat symptomatically and supportively.
    3.   If symptoms occur perform a chest X-ray, ECG, biochemical and
         haematological profiles.
    4.   Collect urine and blood for tellurium concentration measurements
         to confirm diagnosis although these assays are not widely
         available. Check with NPIS.
    5.   It has been suggested that ascorbic acid may reduce the garlic
         odour from tellurium intoxication (De Meio, 1947) but this has
         not been confirmed.
    6.   Dimercaprol increases tellurium toxicity and should not be used.

    References

    Blackadder ES, Manderson WG.
    Occupational absorption of tellurium: a report of two cases.
    Br J Ind Med 1975; 32: 59-61.

    De Meio RH.
    Tellurium. II. Effect of ascorbic acid on the tellurium breath.
    J Ind Hyg Toxicol 1947; 29: 393-5.

    Kron T, Hansen C, Werner E.
    Renal excretion of tellurium after peroral administration of tellurium
    in different forms to healthy human volunteers.
    J Trace Elem Electrolytes Health Dis 1991; 5: 239-44.

    Müller R, Zschiesche W, Steffen HM, Schaller KH.
    Tellurium-intoxication.
    Klin Wochenschr 1989; 67: 1152-5.

    Substance name

         Tellurium hexafluoride

    Origin of substance

         Prepared by direct fluorination of tellurium metal.
                                                 (MERCK, 1996)

    Synonyms

         Tellurium fluoride                      (NIOSH, 1997)

    Chemical group

         A compound of tellurium, a group VI A element.

    Reference numbers

         CAS            7783-80-4                (DOSE, 1994)
         RTECS          WY2800000                (RTECS, 1997)
         UN             2195                     (DOSE, 1994)
         HAZCHEM CODE   NIF

    Physicochemical properties

    Chemical structure
         TeF6                                    (DOSE, 1994)

    Molecular weight
         241.59                                  (DOSE, 1994)

    Physical state at room temperature
         Gas                                     (SAX'S, 1996)

    Colour
         Colourless                              (SAX'S, 1996)

    Odour
         Repulsive                               (SAX'S, 1996)

    Viscosity
         NIF

    pH
         NIF

    Solubility
         Slowly absorbed by water.               (MERCK, 1996)

    Autoignition temperature
         NIF

    Chemical interactions
         Corrodes mercury.
         Hydrolyzed by aqueous potassium hydroxide.
                                                 (MERCK, 1996)

    Major products of combustion
         Fumes of fluoride and tellurium.        (SAX'S, 1996)

    Explosive limits
         NA

    Flammability
         Nonflammable gas                        (NIOSH, 1997)

    Boiling point
         Sublimes at -38.9°C                     (SAX'S, 1996)

    Density
         4.006 at -191°C (solid); 2.499 at -10°C (liquid)
                                                 (SAX'S, 1996)
    Vapour pressure
         NIF

    Relative vapour density
         8.3 (Air = 1 at boiling point of tellurium hexafluoride)    
         (HSDB, 1997)

    Flash point
         NA

    Reactivity
         Hydrolyzed by water to telluric acid, H6TeO6.
                                                 (MERCK, 1996)

    Uses

         A chemical reagent.

    Hazard/risk classification

         NIF

    INTRODUCTION

    Tellurium hexafluoride is a hexavalent compound of tellurium. It is a
    gas at room temperature and so exposure is mainly dermal, ocular and
    via inhalation.

    Tellurium exposure is characterized by a distinctive garlic odour
    which is due to formation of the hepatic metabolite dimethyl
    telluride.

    EPIDEMIOLOGY

    Tellurium hexafluoride poisoning is rare. Only occupational exposure
    has been reported (Blackadder and Manderson, 1975).

    MECHANISMS OF TOXICITY

    There are few data on the mechanism of toxicity of tellurium or its
    compounds. Animal studies suggest tellurium may affect the conversion
    of squalene to cholesterol so interfering with neurotransmission via
    demyelination (Gerhardsson et al, 1986).

    Impaired secretory nerve neurotransmission is the proposed mechanism
    of impaired saliva and sweat secretion in humans and of reduced
    gastric acid secretion in animals poisoned with tellurium (Shie and
    Deeds, 1920).

    There is some evidence that the aroma of fresh garlic is caused by a
    high tellurium content. This may contribute to garlic's
    cholesterol-lowering properties (Larner, 1995).

     In vitro studies demonstrate that tellurite (Te4+) ions can
    penetrate the erythrocyte membrane and, in the presence of reduced
    glutathione, form telluride (Te2+) which causes irreversible membrane
    damage and hence haemolysis (De Meio and O'Leary, 1975; Kurantsin-
    Mills et al, 1988). Tellurate (Te6+) ions do not penetrate the
    erythrocyte membrane. Haemolysis has been observed in animals poisoned
    with tellurium (Shie and Deeds, 1920) but not as a feature of
    tellurium intoxication in man.

    TOXICOKINETICS

    Absorption

    Two male research chemists developed characteristic features of
    systemic tellurium intoxication from inhalation of tellurium
    hexafluoride gas (Blackadder and Manderson, 1975).

    Tellurium dusts and fumes can be absorbed via the lung. Workers
    exposed to tellurium concentrations up to 0.1 mg/m3 had urine
    tellurium concentrations up to 0.06 mg/L (Steinberg et al, 1942).

    The mean (± SD) gastrointestinal absorption in healthy volunteers
    ingesting between 15 and 57 µg has been estimated as ten per cent (± 4
    per cent) for elemental tellurium, 23 per cent (± 9 per cent) for
    tellurate and 21.5 per cent (no SD given) for tellurite (Kron et al,
    1991).

    Ingestion of 0.5 µg tellurium oxide produced a garlic breath odour
    within 75 minutes which lasted for 30 hours (Reisert, 1884).

    Organometallic complexes of tellurium and soluble tellurium salts can
    be absorbed through the skin (Blackadder and Manderson, 1975).

    Distribution

    Tellurium is distributed widely with high concentrations particularly
    in kidneys, liver, bone, brain and testes (Meditext, 1997).

    Excretion

    Excretion is mainly renal although small amounts of tellurium are
    exhaled as dimethyl telluride which has a distinctive garlic odour
    which may persist for many days; Reisert (1884) reported garlic breath
    odour for 237 days following ingestion of 15 mg tellurium oxide. The

    susceptibility to this effect varies considerably between individuals
    and is exacerbated by alcohol consumption (Cerwenka and Cooper, 1961).

    CLINICAL FEATURES: ACUTE EXPOSURE

    Dermal exposure

    Blue-black patches in the webs of the fingers and streaks on the neck
    were observed in two postgraduate chemists who handled volatile
    tellurium esters. The discolouration was believed to be due to
    deposition of elemental tellurium in the dermis and subcutaneous
    tissue (Blackadder and Manderson, 1975).

    Ocular exposure

    Some tellurium compounds are irritant although there are no reports of
    ocular exposure to tellurium or its compounds producing adverse
    effects.

    Exposure to either hydrogen telluride or to shampoo containing
    tellurium oxide has not caused eye problems (Grant and Schuman, 1993).

    Inhalation

    No pulmonary features were reported when two postgraduate chemists
    were exposed to some 50 g tellurium hexafluoride gas which leaked from
    a cylinder into a small laboratory. The first individual developed a
    metallic taste, anorexia and tiredness and, after two days, an
    erythematous papular vesicular rash on the hands, arms and neck. This
    was diagnosed as contact dermatitis, possibly from wearing rubber
    gloves, although the ability of tellurium to inhibit sweating may have
    contributed. The second person affected experienced only a metallic
    taste and somnolence. Both patients developed a garlic odour to the
    breath, sweat and urine which persisted for several weeks (Blackadder
    and Manderson, 1975). Haematological and biochemical profiles and
    chest X-ray were normal.

    CLINICAL FEATURES: CHRONIC EXPOSURE

    There are no reports regarding chronic exposure to tellurium
    hexafluoride though features similar to those observed for other
    tellurium compounds may be expected.

    Inhalation

    Thirteen individuals working near the blast furnaces in a lead
    refinery were examined for signs of tellurium exposure (Shie and
    Deeds, 1920). The workers were believed to have been exposed to
    hydrogen telluride though no exposure data were given. Seven had a
    garlic odour to the breath, sweat and urine, and dryness and a
    metallic taste in the mouth. Five had "considerable inhibition of the
    sweat function" and three developed dry and itchy skin, anorexia,
    nausea, vomiting, depression and somnolence.

    A survey of ninety-eight workers exposed to 0.01-0.1 mg/m3 tellurium
    for 22 months revealed similar effects. The most common findings were
    a garlic odour of the breath (84 individuals), dryness of the mouth
    (32), a metallic taste (27) and garlic odour of the sweat (20). Other
    symptoms included somnolence (16), loss of appetite (9) and nausea
    (3). No evidence of sweat suppression was found. Urinalysis revealed
    increased tellurium concentrations (0.01 to greater than 0.06 mg/L) in
    the exposed group compared to controls. Symptoms occurred even in
    those with urine tellurium concentrations less than 0.01 mg/L, though
    the frequency increased at higher tellurium concentrations with
    somnolence and a garlic sweat odour occurring only in workers with a
    urine tellurium concentration greater than 0.01 mg/L (Steinberg et al,
    1942).

    MANAGEMENT

    Dermal exposure

    If possible the patient should remove any contaminated clothing
    him/herself. Affected areas of skin should be washed with copious
    quantities of water.

    Ocular exposure

    Irrigate immediately with lukewarm water or preferably saline for at
    least 10-15 minutes. Specialist ophthalmological advice should be
    sought if any abnormality is detected or suspected on examination and
    in those whose symptoms do not resolve rapidly.

    Inhalation

    Immediate management involves removal from exposure, establishment of
    a clear airway and administration of supplemental oxygen if necessary.
    Other symptomatic and supportive measures should be dictated by the
    patients condition.

    Antidotes

    Animal studies

    Four guinea pigs were administered 5 mg intramuscular dimercaprol
    eight hours prior to the intramuscular injection of 75 mg tellurium
    oxide. A second group of four similarly poisoned guinea pigs received
    dimercaprol eight hours after tellurium oxide injection. Both groups
    then received dimercaprol 5 mg tds for 24 hours and 5 mg bd for a
    further 24 hours. There was 100 per cent mortality in the two
    dimercaprol administered groups (n=8) within 48 hours (and all animals
    showed pronounced haematuria) whereas the 48 hour survival rate in
    control animals (n=4) administered tellurium oxide alone was 75 per
    cent. A single guinea pig administered only intramuscular dimercaprol
    5 mg every eight hours for 24 hours remained healthy. The weights of
    the animals were not stated (Armdur, 1958).

    Clinical studies

    Three men exposed to tellurium fumes developed a strong garlic breath
    odour and were treated with 2.5 mg/kg dimercaprol intramuscularly
    every four hours for 24 hours, every six hours for a further 24 hours
    and then daily for six days. Each patient reported accentuation of the
    garlic odour following the injection and the odour disappeared one to
    four days after the cessation of treatment. There was no evidence of
    enhanced tellurium elimination with therapy (Amdur, 1947).

    Ascorbic acid

    Animal studies

    The reduction in garlic odour from rabbits and guinea pigs intoxicated
    with tellurium following administration of ascorbic acid (route not
    described) has been reported. The proposed mechanism is reduction of
    ionized to elemental tellurium with decreased dimethyl telluride
    formation (De Meio, 1947).

    Intramuscular ascorbic acid 25 mg tds for 24 hours then 25 mg bd for a
    further 24 hours did not increase the one week survival of guinea pigs
    injected intramuscularly with 75 mg tellurium oxide compared to
    controls (Amdur, 1958).

    Clinical studies

    Workers exposed to tellurium dust were treated with 8-10 mg/kg
    ascorbic acid (route not stated) one to three times daily. A reduction
    in garlic breath odour was noted which recurred on cessation of
    treatment (De Meio, 1947).

    A 37 year old woman who ingested an unknown amount of tellurium was
    treated with ascorbic acid 200 mg daily (route not stated). She
    recovered fully though a garlic odour of the breath persisted from
    some ten months (Müller et al, 1989).

    Antidotes: Conclusions and recommendations

    1.   Animal studies suggest dimercaprol increases tellurium toxicity
         and, as there is no evidence that it enhances tellurium
         elimination, it should not be employed.

    2.   Ascorbic acid may decrease the extent of garlic odour in persons
         with tellurium intoxication although this has not been confirmed
         in controlled studies.

    MEDICAL SURVEILLANCE

    The most obvious indication of tellurium exposure is a garlic odour to
    the breath, which occurs in association with urine tellurium
    concentrations greater than 1 µg/L (Gerhardsson et al, 1986). This
    clinical indication of tellurium exposure may be masked in those with

    badly smelling breath (i.e. bronchiectasis, grossly carious teeth,
    severe gingivitis) (Gerhardsson et al, 1986).

    Normal concentrations in biological fluids

    The "upper normal limits" for tellurium in non-occupationally exposed
    individuals have been reported as 1.0 µg/L in serum and 1.0 µg/L in
    urine (Müller et al, 1989).

    OCCUPATIONAL DATA

    Occupational exposure standard

    Tellurium and compounds, except hydrogen telluride. Long-term exposure
    limit 0.1 µg/m3 (as Te) (Health and Safety Executive, 1997).

    OTHER TOXICOLOGICAL DATA

    Carcinogenicity

    There are no data on the possible carcinogenic effects of tellurium
    hexafluoride in humans.

    Reprotoxicity

    Pregnant rats fed diets containing 500 to 3500 ppm tellurium gave
    birth to hydrocephalic (non-obstructive) offspring, the incidence of
    hydrocephalus being proportional to the tellurium dose (Duckett,
    1970). The mechanism of this effect is not known.

    There are no data on the possible reproductive effects of tellurium
    hexafluoride in humans.

    Genotoxicity

    An increase in the incidence of chromosome breakage was found when 
     in vitro human leukocytes were treated for 48 hours with 1.2 x 10-8
    mol/L sodium tellurite and 2.4 x 10-7 mol/L ammonium tellurite (Paton
    and Allison, 1972).

    Fish Toxicity

    NIF

    EC Directive on Drinking Water Quality 80/778/EEC

    NIF

    WHO Guidelines for Drinking Water Quality

    NIF

    AUTHORS

    WN Harrison PhD CChem MRSC
    SM Bradberry BSc MB MRCP
    S Meacham BSc
    JA Vale MD FRCP FRCPE FRCPG FFOM

    National Poisons Information Service (Birmingham Centre),
    West Midlands Poisons Unit,
    City Hospital NHS Trust,
    Dudley Road,
    Birmingham
    B18 7QH
    UK

    This monograph was produced by the staff of the Birmingham Centre of
    the National Poisons Information Service in the United Kingdom. The
    work was commissioned and funded by the UK Departments of Health, and
    was designed as a source of detailed information for use by poisons
    information centres.

    Date of last revision
    28/1/98

    REFERENCES

    Amdur ML.
    Tellurium. Accidental exposure and treatment with BAL in oil.
    Occup Med 1947; 3: 386-91.

    Amdur ML.
    Tellurium oxide: an animal study in acute toxicity.
    Arch Ind Health 1958; 17: 665-7.

    Blackadder ES, Manderson WG.
    Occupational absorption of tellurium: a report of two cases.
    Br J Ind Med 1975; 32: 59-61.

    Cerwenka EA, Cooper WC.
    Toxicology of selenium and tellurium and their compounds.
    Arch Environ Health 1961; 3: 189-200.

    De Meio RH.
    Tellurium. II. Effect of ascorbic acid on the tellurium breath.
    J Ind Hyg Toxicol 1947; 29: 393-5.

    De Meio RH, O'Leary DJ.
    Hemolysis by tellurium compounds: Telluride and tellurate, effect on
    reduced glutathione.
    J Am Osteopath Assoc 1975; 75: 430-1.

    DOSE/Dictionary of substances and their effects. Vol 7.
    Cambridge: Royal Society of Chemistry, 1994.

    Duckett S
    Fetal encephalopathy following ingestion of tellurium.
    Experientia 1970; 26: 1239-41.

    Gerhardsson L, Glover JR, Nordberg GF, Vouk V.
    Tellurium.
    In: Friberg L, Nordberg GF, Vouk VB, eds. Handbook on the toxicology
    of metals. Vol 2. 2nd ed.
    Amsterdam: Elsevier Science Publishers, 1986; 532-48.

    Grant WM, Schuman JS.
    Toxicology of the eye. 4th ed.
    Illinois: Charles C Thomas, 1993.

    Health and Safety Executive.
    EH40/97: Occupational exposure limits 1997.
    Sudbury: HSE Books, 1997.

    HSDB/Hazardous Substances Data Bank.
    In: Tomes plus. Environmental Health and Safety Series 1. Vol 32.
    National Library of Medicine, 1997.

    Kron T, Hansen C, Werner E.
    Renal excretion of tellurium after peroral administration of tellurium
    in different forms to healthy human volunteers.
    J Trace Elem Electrolytes Health Dis 1991; 5: 239-44.

    Kurantsin-Mills J, Klug RK, Lessin LS.
    Irreversible erythrocyte volume expansion induced by tellurite.
    Br J Haematol 1988; 70: 369-74.

    Larner AJ.
    How does garlic exert its hypocholesterolaemic action? The tellurium
    hypothesis.
    Med Hypotheses 1995; 44: 295-7.

    MEDITEXT.
    In: Tomes plus. Environmental Health and Safety Series 1. Vol 32.
    Colorado: Micromedex, Inc., 1997.

    MERCK/The Merck Index.
    Tellurium hexafluoride. In: Budavari S, ed. An encyclopedia of
    chemicals, drugs, and biologicals. 12th ed.
    New Jersey: Merck and Co., Inc., 1996; 1560.

    Müller R, Zschiesche W, Steffen HM, Schaller KH.
    Tellurium-intoxication.
    Klin Wochenschr 1989; 67: 1152-5.

    NIOSH/NIOSH Pocket Guide.
    In: Tomes plus. Environmental Health and Safety Series 1. Vol 32.
    National Institute for Occupational Safety and Health (NIOSH), 1997.

    Paton GR, Allison AC.
    Chromosome damage in human cell cultures induced by metal salts.
    Mutat Res 1972; 16: 332-6.

    Reisert W.
    The so-called bismuth breath.
    Am J Pharm 1884; 56: 177-80.

    RTECS/Registry of Toxic Effects of Chemical Substances.
    In: Tomes plus. Environmental Health and Safety Series 1. Vol 32.
    National Institute for Occupational Safety and Health (NIOSH), 1997.

    SAX'S/Lewis RJ.
    Sax's dangerous properties of industrial materials. 9th ed. Vol 3.
    New York: Van Nostrand Reinhold, 1996.

    Shie MD, Deeds FE.
    The importance of tellurium as a health hazard in industry - a
    preliminary report.
    Public Health Rep 1920; 35: 939-54.

    Steinberg HH, Massari SC, Miner AC, Rink R.
    Industrial exposure to tellurium: atmosphere studies and clinical
    evaluation.
    J Ind Hyg Toxicol 1942; 24: 183-92.