Toxicological evaluation of some food
    additives including anticaking agents,
    antimicrobials, antioxidants, emulsifiers
    and thickening agents



    WHO FOOD ADDITIVES SERIES NO. 5







    The evaluations contained in this publication
    were prepared by the Joint FAO/WHO Expert
    Committee on Food Additives which met in Geneva,
    25 June - 4 July 19731

    World Health Organization
    Geneva
    1974

              

    1    Seventeenth Report of the Joint FAO/WHO Expert Committee on
    Food Additives, Wld Hlth Org. techn. Rep. Ser., 1974, No. 539;
    FAO Nutrition Meetings Report Series, 1974, No. 53.

    TRAGACANTH GUM

    Explanation

         This substance has been evaluated for acceptable daily intake by
    the Joint FAO/WHO Expert Committee on Food Additives (see Annex 1,
    Ref. No. 19) in 1969.

         Since the previous evaluation, additional data have become
    available and are summarized and discussed in the following monograph.
    The previously published monograph has been expanded and is reproduced
    in its entirety below.

    BIOLOGICAL DATA

    BIOCHEMICAL ASPECTS

         In a comparative study of the hypocholesterolemic activity of
    various mucilaginous polysaccharides tragacanth gum fed at a level of
    3% along with 3% cholesterol in the diet of cockerels, inhibited the
    development of hypercholesterolemia (Riccardi & Fahrenback, 1965).
    Tragacanth gum administered intraperitoneally, subcutaneously or
    per os 24 hours before hexobarbital has no effect on the
    hexobarbital sleeping time of mice. The effect of phenobarbital and
    urethan pre-treatment to induce a shortening of hexobarbital sleeping
    is blocked by intraperitoneal injections of tragacanth gum, thus
    suggesting the presence of a hepatic effect of tragacanth gum
    (Fujimoto, 1965).

    TOXICOLOGICAL STUDIES

    Special studies on sensitization

         Although there are only few reports of sensitization to
    tragacanth, the available information indicates tragacanth is a
    powerful allergen capable of causing extremely severe reactions
    (Gelfand, 1943). Allergic response may occur as a result of inhalation
    or oral ingestion (Gelfand, 1949).

    Special studies on teratogenicity

    Mouse

         Intraperitoneal injection of 1 ml 1% aqueous mucilage of Persian
    tragacanth (single dose or five doses of 0.2 ml) into mice between
    days 11 and 15 of gestion caused the death of all fetuses. Oralor s.c.
    administration had no effect. All samples were found to be
    contaminated with enterobacter spp. and the embryotoxic effects were
    attributed to bacterial metabolites (Frohberg et al., 1969).

    Acute toxicity

         None available.

    Short-term studies

         None available.

    Long-term studies

         None available.

    Comments:

         Little toxicological information is available despite the
    traditional use of this substance in pharmaceutical preparations. The
    metabolic fate of this gum should be studied in several species,
    preferably including man. Ninety-day studies in several species are
    also required. The teratogenicity study points to the need for careful
    attention to the microbiological contamination of these natural gums.

    EVALUATION

         Not possible on the data available.

    REFERENCES

    Frohberg, H., Oettel, H. & Zeller, H. (1969) Arch. Toxikol., 25, 268

    Fujimoto, J. M. (1965) Toxicol. appl. Pharmacol., 7, 287-290

    Gelfand, H. H. (1943) J. Aller., 14, 203

    Gelfand, H. H. (1949) J. Aller., 20, 311

    Riccardi, B. A. & Fahrenbach, M. J. (1965) Fed. Proc., 24, 263

    See Also:
       Toxicological Abbreviations
       Tragacanth gum  (FAO Nutrition Meetings Report Series 46a)
       Tragacanth Gum (WHO Food Additives Series 20)
       TRAGACANTH GUM (JECFA Evaluation)