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.

    ISOASCORBIC ACID AND ITS SODIUM SALT

    Explanation

         These compounds have been evaluated for acceptable daily intake
    by the Joint FAO/WHO Expert Committee on Food Additives (see Annex 1,
    Ref. No. 6) in 1961.

         The previously published monograph has been revised and is
    reproduced in its entirety below.

    BIOLOGICAL DATA

    BIOCHEMICAL ASPECTS

         Isoascorbic acid is readily absorbed and metabolized. Following
    an oral dose of 500 mg of isoascorbic acid to human subjects the blood
    level curves for ascorbic acid and isoascorbic acid showed a similar
    rise. In five human subjects, an oral dose of 300 mg was shown to have
    no effect on the urinary excretion of ascorbic acid (Kadin & Osadca,
    1959). Isoascorbic acid was found to have no antagonistic effect on
    the action of ascorbic acid (Gould, 1948).

    TOXICOLOGICAL STUDIES

    Acute toxicity

         No information available.

    Short-term studies

    Rat

         Groups of 10 male rats were fed for 36 weeks on diets containing
    1% of isoascorbic acid, and on diets without isoascorbic acid. There
    was no difference between the treated rats and the controls with
    respect to rate of growth and mortality. Gross post mortem examination
    and microscopic studies of various organs revealed no lesion
    attributable to isoascorbic acid (Fitzhugh & Nelson, 1946).

    Long-term studies

    Rat

         Groups of rats were fed on diets containing 1% of isoascorbic
    acid and diets without isoascorbic acid for two years. The growth
    rate, mortality, and histopathology were not affected by the treatment
    (Lehman et al., 1951).

    Comments:

         There are adequate short and long-term studies in the rat. The
    biochemical studies indicate that isoascorbic acid is readily
    metabolized and does not affect the urinary excretion of ascorbic
    acid.

    EVALUATION

    Level causing no toxicological effect

         Rat: 10 000 ppm (1%) in the diet equivalent to 500 mg/kg bw.

    Estimate of acceptable daily intake for man

         0-5 mg/kg bw.

    REFERENCES

    Fitzhugh, O. G. & Nelson, A. A. (1946) Proc. Soc. exp. Biol., 61, 195

    Gould, D. S. (1948) Arch. Biochem., 19, 1

    Kadin, H. & Osadca, M. (1959) J. Agric. Food Chem., 7, 358

    Lehman, A. J. et al. (1951) Advanc. Food Res., 3, 197

    See Also:
       Toxicological Abbreviations