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.


         Commercial "hexane" may contain up to 50% 2-methylpentane and
    3-methylpentane as well as n-hexane and small amounts of various
    pentanes, heptane, dimethyl butane, etc.

         Heptane is not a well defined and specified solvent. Various
    hydrocarbon mixtures are separated from crude oils into a number of
    solvents having specific boiling point ranges (SBP). They are natural
    products of variable composition depending on the crude oil from which
    they have been fractionated but having a given boiling point range
    (van Raalte, 1970).

         Heptane is more specifically a fraction boiling at 43-65C.
    Gasoline boils at 40-70C, pentane at 34-37C. Higher boiling
    fractions are hexane 65-69C, SBP 62/82 boiling at 64-72C, SBP 80/100
    boiling at 83-120C.

         Analysis of extracted oils and remaining cakes reveals only a few
    ppm of solvent, e.g. 0.3 ppm SBP 62/82 in cocoa butter.

    Biological Data

    Biochemical aspects

         This aliphatic hydrocarbon is considered to be as inert
    biochemically as it is chemically in parallel to other hydrocarbons
    (Williams, 1959). No information exists whether ingested hexane is
    metabolized but, of the little absorbed after inhalation most appears
    to be re-excreted unchanged via the lungs and perhaps a trace appears
    in the urine (Estler, 1939).

    Actute toxicity


    Animal   Compound    Route             LD 100         Reference

    Rat      Hexane      i.p.(at 8C)      4000           Keplinger et al., 1959
             "           i.p.(at 26C)     9100           Keplinger et al., 1959
             "           i.p.(at 36C)     530            Keplinger et al., 1959
             SBP         Oral              >20 ml/kg     Shell Research Ltd.,
                         (intragastric)                   1962
    0.2 ml hexane, when aspirated by the anaesthetized rat, produced
    convulsions and death within a few seconds. Cardiac arrest,
    respiratory paralysis and asphyxia occurred (Gerarde, 1963). Hexane is
    only a weak anaesthetic but paralyses the respiratory centre before
    the spinal reflexes are abolished. It is irritant to skin and mucosa
    (Estler, 1939).

         Many rats died with signs of pulmonary congestion due to asphyxia
    from inhaled droplets or vapour of SBP 62/82. No gross changes were
    seen at autopsy (Shell Research Ltd., 1962).

    Short-term studies

         Prolonged inhalation of hexane causes occasionally anaemia and
    nephropathy in animals. Injection of 0.5 - 1.0 cc/kg into animals also
    lowers the RBC and causes erythroblastosis (Estler, 1939).


         Three groups of 10 male and 10 female rats were given either
    water or 1 ml/kg or 5 ml/kg SBP three times per week for 90 days.
    Macroscopic examination revealed no lesions related to SBP
    administration (Shell Research Ltd., 1962).

         Three groups of 25 male and 25 female rats were given an emulsion
    of SBP 62/82, once a week for 6 months at 0, 0.5 ml/kg and 2.5 ml/kg
    bodyweight levels. Controls received the emulsion without SBP. Growth
    and bodyweight gain were similar to controls. Blood tests showed no
    deleterious effects on RBC, plasma urea or total plasma protein in the
    test animals. Nor was there any effect on SGOT. The high mortality was
    probably due to aspiration pneumonia. Male rats had lighter spleens at
    all levels tested. Females showed lighter livers at the high intake
    level and heavier spleens and lighter adrenals at the lower level. No
    histopathological evidence of liver, kidney or heart changes was
    detected (Shell Research Ltd., 1962).


         Five groups of male and three female dogs were given daily for 6
    months capsules containing SBP 62/82 at the following rates; 0.005
    ml/kg, 0.02 ml/kg, 0.10 ml/kg, 0.50 ml/kg and 0.50 ml/kg olive oil in
    capsules as control. Haematology and clinical chemistry of urine and
    blood as well as liver function tests at the highest dose level showed
    no significant differences from controls. Bodyweight and organ weights
    showed no abnormalities compared with controls. Gross and
    histopathology revealed no abnormalities due to the administration of
    SBP 62/82 (Shell Research Ltd., 1965).

    Long-term studies

    None available.

    Special studies

         Several studies have been undertaken to determine the amount of
    polycyclic aromatic hydrocarbons in hexane as some of these may have
    carcinogenic activity. Some samples contain less than 0.01 ppm (the
    limit of the sensitivity of the analytical method (Ryder & Sullivan,
    1962)) but traces have been found in hexane derived from cracking
    processes (Tye et al., 1966). Others have formed 0.023 ppm of
    3,4-Benzpyrene (Lijinsky & Raha, 1961). Polycyclic aromatic
    hydrocarbons have also been detected in such natural products as cold
    pressed olive oil at 0.01 -0.026 ppm (Jung & Morand, 1962) and in
    other crude untreated oils at 0.0022-0.011 ppm, (Grimmer &
    Hildebrandt, 1967).

    Observations in man

         Acute poisoning in man due to hexane leads to excitement,
    delirium  hallucinations, tremor, acrocyanosis and addiction (Estler,
    1939). Inhalation of 5000 ppm for 10 minutes caused dizziness and
    giddiness in man (Patty, 1958). The TVL for hexane, heptane and octane
    is 500 ppm. (Amer. Conf. Gov. Ind. Hyg., 1969).


         These solvents appear to be resistant to chemical or biochemical
    attack in the mammalian gastro-intestinal tract but data directed
    towards elucidating the effects of oral ingestion should be provided.
    Studies with hexane and with a specific product (SBP 62/82), both
    which may contain up to 50% of hexane as well as various amounts of
    heptane, showed no deleterious effects in short-term studies at levels
    up to 2.5 ml/kg bodyweight in the rat and 0.5 ml/kg bodyweight in the
    dog. No long-term studies are available on either hexane or heptane.
    Problems could arise from the transfer to food of less volatile
    impurities which would not be removed during solvent recovery.
    Adequate specifications are required with regard to aromatic and
    carcinogenic polycyclic hydrocarbons. It should be noted that trace
    amounts of polycyclic aromatic hydrocarbons occur naturally in edible

    Tentative Evaluation

         The use of hydrocarbon solvents should be restricted to that
    determined by good manufacturing practice, which is expected to result
    in minimal residues unlikely to have any significant toxicological

    Further work required

         Specific information on possible content of carcinogenic
    polynuclear aromatic hydrocarbons in petroleum hydrocarbon fractions
    used as solvents.


    Amer. Conf. Gov. Ind. Hyg. (1969) Threshold Limit Values for 1969

    Estler, W. (1939) VIII Intern. Kirg. Unfallmed. Berufsk., 2, 892

    Gerarde, H. W. (1963) Arch. Environ. Hlth., 6, 329

    Grimmer, G. & Hildebrandt, A. (1967) Chemistry and Industry, 2000

    Jung, L. & Morand, P. (1962) Acad. Sci. Seance 1/2/1962, 1489

    Keplinger, M. L., Lanier, G. E. & Deichmann, W. B. (1959)Toxicol.
    appl. Pharmacol.,1, 156

    Lijinsky, W. & Raha, C. R. (1961) Toxicol. appl. Pharmacol.  3 

    Patty, F. A. (1958) Industrial Hygiene & Toxicology, Interscience, New

    van Raalte, H. G. S. (1970) Unpublished report submitted to WHO

    Ryder, I. W. & Sullivan, G. P. (1962) J. Amer. Oil Chem. Soc., 39,

    Shell Research Ltd. (1962) Unpublished studies on SBP 62/82 submitted
    to WHO

    Shell Research Ltd. (1965) Unpublished studies on SBP 62/82 submitted
    to WHO

    Tye, R. et al. (1966) Arch. Environ. Hlth., 13, 202

    Williams, H. T. (1959) Detoxication Mechanisms, Chapman & Hall, London

    See Also:
       Toxicological Abbreviations