FAO Nutrition Meetings 
    Report Series No. 48A 
    WHO/FOOD ADD/70.39


    The content of this document is the 
    result of the deliberations of the Joint 
    FAO/WHO Expert Committee on Food Additives 
    which met in Geneva, 24 June  -2 July 19701

    Food and Agriculture Organization of the United Nations
    World Health Organization


    1 Fourteenth report of the Joint FAO/WHO Expert Committee on Food
    Additives, FAO Nutrition Meetings Report Series in press; Wld Hlth
    Org. techn. Rep. Ser., in press.


    Biological data

    Biochemical aspects

    Probably between 71-76% of inhaled trilene is rapidly absorbed through
    the lungs. In man most absorption occurs within the first few minutes
    of exposure and then decreases to an equilibrium between air/blood
    concentrations. Moderate absorption can occur through intact skin and
    from the gastrointestinal mucus after ingestion (von Oettingen, 1955).

         In the rat, rabbit and dog absorbed trilene is distributed among
    all organs and tissues but concentrates mostly in fat and brain and
    least in skeletal muscle; lung and liver also retain low levels
    (Barrett et al., 1939; Clayton & Parkhouse, 1962; von Oettingen,
    1955). Similar organ concentrations are found in guinea-pigs but high
    levels were also found in ovaries and adrenals (Fabre & Truhaut,
    1952). In the rat trilene and trichloroacetic acid may be selectively
    bound to erythrocytes hence giving high spleen levels (Fabre &
    Truhaut, 1952) but plasma proteins may also be involved (Soucek &
    Vlachová 1960). In man trilene is detectable in the blood within 30
    minutes of inhalation (Stewart et al., 1962).

         Trilene is metabolized slowly to chloralhydrate (via an epoxide)
    and then rapidly to 2,2,2-trichloroacetic acid (CCl3 CHOOH) and
    2,2,2-trichlorethanol (CCl3CH2OH), which latter two metabolites are
    excreted as urinary glucuronides (e.g. trichlorethanol glucusiduronic
    acid) very little unchanged trilene appearing in the urine (Powell,
    1945; Butler, 1949; Uhl & Haag, 1958; Williams, 1959; Smith, 1966).
    Dogs excrete 5-8% of absorbed trilene as trichloroacetic acid and
    15-20% as trichlorethanol up to 4 days after exposure (Barrett et al.,
    1939; Barrett & Johnston, 1939; von Oettingen, 1955). The lung and
    spleen, less so the liver are probably the main sites of metabolism
    (Fabre & Truhaut, 1952; Defalgue, 1961). Rats excrete about 4% of
    inhaled trilene as trichloroacetic acid, the lung and spleen being the
    main sites of metabolism in vitro and in vivo, the liver being
    less important (Fabre & Truhaut, 1952). Rats given oral trilene
    excrete 3% as trichloroacetic acid and 15% as trichlorethanol (Daniel,
    1957a) trichlorethanol excretion being the better guide to extent of
    exposure (Daniel, 1957b). 36Cl labelled trilene was given to rats by
    gavage. 10-20% was excreted in the urine as trichloroacetic acid
    (1-5%) and trichlorethanol (10-15%), 0-0.5% in the faeces and 72-85%
    probably as trilene in the expired air. The metabolites were formed by
    intra-molecular rearrangement. Radioactivity was excreted for up to 18
    days after single dosing (Daniel, 1963). In vitro studies on rat
    liver microsomes showed conversion of trilene to chloral (Byington &
    Leibman, 1965). Rabbits excrete 0.5% of absorbed trilene as
    trichloroacetic acid (Fabre & Truhaut, 1952; Defalgue, 1961) and after
    oral dosing by gavage no significant effects were seen on urobilin,
    blood, glucose level or serum cholesterol (Dervilleé et al., 1938).
    Guinea-pigs show presence of trichloroacetic acid in their urine after

    inhalation (Fabre & Truhaut, 1952). Calves similarly metabolize orally
    administered trilene to trichloroacetic acid (1%) and trichlorethanol
    (13-25%) appearing in their urine together with a trace of trilene.
    The balance is probably exhaled or excreted in the faeces (Seto &
    Schultze, 1955).

         Man excretes 6-16% of inhaled trilene as trichloroacetic acid
    (Ahlmark & Forssman, 1951); others found 7-27% of retained trilene
    being excreted as trichloroacetic acid (Powell, 1945; Soucek et al.,
    1952) as well as trichlorethanol, monochloracetic acid and chloroform
    (Soucek et al., 1952; Defalgue, 1961). Small amounts of
    trichloroacetic acid may continue to be excreted in the urine for up
    to 12 days after single exposure (von Oettingen, 1955). Five human
    subjects exposed for 5 hours to trilene excreted 4% of the retained
    dose as monochloracetic acid, 19%. as trichloroacetic acid and 50% as
    trichlorethanol over the next 14 day. (Soucek & Vlachová, 1960;
    Defalgue, 1961). In another experiment 8 subjects inhaled trilene for
    5 hours. 51-64% of the inhaled trilene was retained the rest exhaled
    unchanged. Of the retained trilene 38-50% was excreted as urinary
    trichlorethanol and 27-36% as urinary trichloroacetic acid. 8.4% of
    trichloroacetic acid and trichlorethanol was excreted in the faeces.
    Sweat and saliva contained also both metabolites (Bartonicek, 1962).
    In all species most of the trichloroacetic and trichlorethanol is
    excreted in the first 2 days after exposure but excretion may go on up
    to 53 day. Some 2-4 hours elapse after single exposure before
    trichloroacetic acid appears in the blood reaching a maximum in 20-50
    hours (Ahlmark & Forssman, 1951; Defalgue, 1961). Trichlorethanol
    appears to be the main metabolite and is much more toxic (Bartonicek &
    Teisinger, 1962). Disulfiram decreases the excretion of
    trichloroacetic acid and trichlorethanol by acting either on
    converting enzymes or on trilene release from fat depot. (Bartonicek &
    Teisinger, 1962) while glucose and insulin increase production (Soucek
    & Vlachová, 1960).

         Chronic exposure may cause disturbance of protein metabolism by
    an increase in the ß-globulin to 16-21% (normal 10-14%) and in fat
    metabolism by an increase in unsaturated fatty acids (Guyot-Jeannin &
    Van Steenkiste, 1958). Repeated inhalation or oral ingestion by rats
    causes transitory elevation of SGOT levels for 24 hours after the last
    exposure, the SGPT levels remaining normal. SGOT levels return to
    normal within 9 days after exposure. No such transitory effects are
    seen in rabbits (Tolot et al,, 1966; Viallier & Casanova, 1965).
    Previous ingestion of ethanol potentiates trilene toxicity in rats as
    shown by a rise in SGOT, SGPT and SICD) (isocitric dehydrogenase) and
    wide-spread degenerative lipid infiltration as well as early
    centrilobular necrosis of the liver (Cornish & Adefuin, 1966).

         Single exposure of mice to the inhalation LD50 of trilene showed
    some hepatotoxicity as evidenced by a rise in SGPT (Gehring, 1968).

         Trilene passes readily through the placenta and occurs in foetal
    blood in higher concentrations (Helliwell & Hutten, 1950). Orally
    administered trilene has no effect on rat liver glutathione levels
    (Johnson, 1965).

         Trilene exerts a variety of pharmacological effects. It depresses
    the CNS with predominant narcotic action but needs relatively high
    dosage (Defalgue, 1961). In the CNS there is a variable effect on
    blood pressure. Cardiac arrhythmias are frequent with anaesthetic use
    (Defalgue, 1961) and bradycardia, ectopic beats and other arrhythmias
    have been seen in dogs and rabbits. Possible some vasoconstriction in
    the capillary bed may occur (von Oettingen, 1955). In the R.S. the
    most common reaction is tachypnoea, especially in young children
    (Defalgue, 1961). Little effects occur in the G.I. tract (Defalgue,
    1961) nor were any effects seen on basal metabolic rate, liver or
    kidney function (von Oettingen, 1955). Trilene absorbed through the
    skin appears in the alveolar air (Stewart & Dodd, 1961).

    Acute toxicity


    Animal        Route            LD50           LD100                   Reference

    Mouse         inhalation       -              7 900 ppm (2 hrs)       von Oettingen, 1955
                  s.c.             11.0           -                       Plaa et al., 1958
                  i.p.             2.2            -                       Klaassen & Plaa, 1966
    Rat           oral             4.92           -                       Smyth et al., 1969
                  inhalation       -              20 000 ppm              Adams et al., 1951
    guinea-pig    inhalation       -              37 000 ppm (40 min)     von Oettingen, 1955
    Rabbit        s.c.             -              1 800 mg/kg             Barsoum & Saad, 1934
                  inhalation       -              11 000 ppm              Bernardi et al., 1956
                  percutaneous     >20            -                       Smyth et al., 1969
    Dog           i.v.             -              150 mg/kg               Barsoum & Saad, 1934
                  i.p.             1.9            -                       Klaassen & Plaa, 1967
         Mice, rats, guinea-pigs and rabbits dying acutely from
    inhalation, show no toxic effects on the tissues, liver or kidney nor
    after s.c. or i.v. administration (Browning, 1965). I.p. injection of
    2.5 1/kg trilene into mice had no effect on PSP excretion and produced
    no proteinuria or glycosuria, nor histological renal changes (Plaa &
    Larson, 1965). Oral doses of 3-4 m/kg bodyweight were fatal to rats,
    mice and guinea-pigs with signs of gastro-intestinal irritation (von
    Oettingen, 1955). Chronic oral poisoning has caused some liver and
    renal damage in dogs and rabbits (von Oettingen, 1955).

         Trilene is a local irritant on the skin, causing blisters and
    necrosis in man and desquamation with ulceration in rabbits (von
    Oettingen, 1955).

    Short-term studies

    None available.

    Long-term studies

    None available.

    Special studies

         Observations in animals exposed for varying periods up to 10
    months show disturbed co-ordination and hyperexcitability but no
    effects on liver or kidney or blood chemistry. Only the CNS showed
    some oedema and ganglion cell degeneration (Browning, 1965). Rats,
    guinea-pigs, squirrel monkeys, rabbits and dogs were exposed to 3825
    mg/m3 for 6 weeks without significant adverse effects. Exposure to
    189 mg/m3 for 90 days also revealed no significant pathological
    changes (Prendergast et al., 1967). Groups of 20 mice were exposed for
    1-8 weeks to 200 or 1600 ppm daily for 4 hours. Only slight transient
    fatty hepatic degeneration and no renal effects were seen (Kylin et
    al., 1965).

         Guinea-pigs were exposed to vapour of trilene for 2-1/2 to 4
    months without adverse effects on bodyweight, haematological findings
    or urinalysis results but there was slight evidence of hepatic
    parenchymal degeneration and renal glomerular and tubular degeneration
    (Lande et al., 1939). Rabbits given for 1-5 months 0.074 g/kg trilene
    showed little adverse effect on bodyweight, haematological finding,
    urinary analysis but some hepatic and renal lesions were seen (Lande
    et al., 1939). Dogs were exposed to 150-750 ppm daily for 2-8 weeks.
    Hepatic injury as evidence by BSP excretion, glycogen depletion and
    parenchymal degeneration as well as weight loss, lethargy and
    diarrhoea occurred but cleared on stopping exposure (Seifter, 1944).

         Soyabean meal extracted with trilene but not with hexane or
    carbon tetrachloride has caused fatal refractory haemorrhagic aplastic
    anaemia in cattle (Stockman, 1916; Picken et al., 1955). The toxic
    factor was shown to be associated with the protein fraction (Picken &
    Biester, 1957; Seto et al., 1958). Similar effects were produced by
    trilene-extracted meat scrap (Rehfeld et al., 1958). However, chicks
    fed trilene-extracted meat scraps showed improved growth (Balloun et
    al., 1955). The toxic factor has been identified as
    S-trans-(dichlorovinyl)-L-cysteine, a reaction product of trilene and
    protein which becomes freed on protein hydrolysis (McKinney et al.,
    1957). Using radio labelled trilene it has been shown that this
    reaction is unlikely to occur when extracting coffee (Brandenberger et
    al., 1969).

         Groups of 20 male and female rats were fed instant decaffeinated
    coffee solid extracted with trilene for 2 years at 0% or 5% of their
    diet (equivalent to a residue of 0.5 ppm trilene) without deleterious
    effects on survival, behaviour, growth, food consumption, urinalysis,
    haematology, organ weights and histopathological findings (Zeitlin,

         Eight males and 16 female rats were fed on a diet containing 0%
    or 5% of instant decaffeinated coffee solids extracted with trilene
    (equivalent to a residue of 0.5 ppm trilene). Two generations were
    studied as regards paternal and filial mortality, conception rate,
    resorption, litter size, growth and survival of litter. Organ weights,
    blood chemistry, urinalysis and histopathology of the F2 generation
    were normal (Zeitlin, 1967).

         A teratogenicity study in rats fed 5% of trilene extracted
    instant decaffeinated coffee solids (equivalent to 0.5 ppm trilene)
    was done for 2 weeks before mating until the 20th day of the 2nd
    pregnancy. Foetuses were examined and resorption sites counted. No
    significant deformities were noted in the test groups nor was there
    any excessive resorption. Alizarin staining revealed no foetal
    skeletal abnormalities (Zeitlin, 1966).

    Observations in man

         There is much experience from safe use of trilene as an
    anaesthetic for man and from various other analgesic inhalation
    treatments now abandoned e.g. trigeminal neuralgia, migraine, angina
    (von Oettingen, 1955). Some authorities recognize a syndrome of
    chronic intoxication (Moeschlin, 1956) others admit only to a
    transient neurasthenic symptom complex (Anderssen, 1957). Fumes or the
    liquid can cause skin burns. No evidence exists of serious
    haematological effects. Neurological disturbances are similar to
    neurasthenic conditions with rarely apparent cardiac disturbances.
    Trigeminal palsies and optic nerve involvement may have been due to
    impurities but have not been seen with pure material. Irritation of
    the lungs and gastro intestinal symptoms have been reported after
    industrial over-exposure.  Addiction has been reported (Bardodej &
    Vyskocil, 1956; Browning, 1965; Patty, 1958; Defalgue, 1961; Milby,
    1968; Mitchell & Parsons-Smith, 1969). Psychomotor performance is not
    affected by exposure to 100 ppm but there is a decline in performance
    at higher inhalation levels (Stops & McLaughlin, 1967).

         Eight males were exposed to 0, 100, 300 or 1000 ppm in air for 2
    hours. At 1000 ppm visual perception and motor skills were adversely
    affected (Vernon & Ferguson, 1969). In another experiment leucocyte
    alkaline phosphatase levels in peripheral leucocytes were elevated
    after prolonged exposure. This effect is reversible (Friborská, 1969).

         Acute human poisoning cases have recovered without hepatic or
    renal sequelae. After ingestion there is some burning of the oral
    mucosa, later nausea and vomiting with vertigo, ataxia, somnolence,
    confusion, delirium and coma (Browning, 1965). Excessive inhalation

    has been blamed for hepato-nephritis but the incidence is very low and
    it is possible that liver and renal involvement are the result of
    underlying previous disease (Roche et al., 1958). Untoward effects on
    the circulation, cardiac irregularities and excessive capillary oozing
    with tachypnoea but no adverse hepatic effects have been reported
    after anaesthetic use (von Oettingen, 1955). Ingestion of 60 ml
    appears to be fatal in man (Pebay-Peyroula et al., 1966). At elevated
    temperatures trilene reacts with soda lime to form dichloracetylene
    and this reacts further to generate phosgene carbonylchloride And
    various acids which are all toxic (Defalgue, 1961). The TLV is 100
    ppm, (Amer. Conf. Gov. Ind. Hyg. 1969).


         Ingestion or inhalation of 1,1,2-trichlorethylene produced
    metabolites which are more toxic than the parent compound. The use of
    1,1,2-trichlorethylene as a solvent is liable to cause formation of
    the toxic S-(transdichlorovinyl)-L-cysteine from sulfur-containing
    amino acids. There is a large amount of human experience from the use
    of 1,1,2-trichlorethylene as an anaesthetic. No formal long-term
    studies are available on the solvent per se but 2 year rat feeding
    studies, multigeneration studies and teratology studies have been
    performed using 1,1,2-trichlorethylene-extracted decaffeinated instant
    coffee solids.

    Tentative evaluation1

         There is a need for care in the choice of food types subjected to
    extraction by 1,1,2-trichlorethylene in view of its reactivity with
    -SH groups. It should not be used for extracting of protein materials
    contributing significantly to the diet.  In foods such as coffee
    suitable for 1,1,2-trichlorethylene extraction, the use of the solvent
    should be restricted to that determined by good manufacturing
    practice, which is expected to result in minimal residues unlikely to
    have any toxicological significance.


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    1 For all foods other than coffee for the extraction of caffeine.

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    See Also:
       Toxicological Abbreviations