FAO Nutrition Meetings
    Report Series No. 40A,B,C
    WHO/Food Add./67.29


    The content of this document is the result of the deliberations of the
    Joint FAO/WHO Expert Committee on Food Additives which met at Rome,
    13-20 December, 19651 Geneva, 11-18 October, 19662


    1 Ninth Report of the Joint FAO/WHO Expert Committee on Food
    Additives, FAO Nutrition Meetings Report Series, 1966 No. 40; 
    Wld Hlth Org. techn. Rep. Ser., 1966, 339

    2 Tenth Report of the Joint FAO/WHO Expert Committee on Food
    Additives, FAO Nutrition Meetings Report Series, 1967, in press; 

    Food and Agriculture Organization of the United Nations
    World Health Organization


    Chemical name           Hydrochloric acid

    Empirical formula       HCl

    Molecular weight        36.46

    Definition              Hydrochloric acid contains not less than the
                            minimum amount of hydrogen chloride specified.

                            NOTE - Hydrochloric acid produced during the
                            manufacture of chlorinated hydrocarbon
                            insecticides is not considered to be of food
                            grade quality and is not suitable for use in
                            food processing.

    Description             Hydrochloric acid is a colourless liquid; it
                            has a pungent odour if the concentration is
                            about 25 per cent. When well diluted with
                            water it has an acid taste.

    Use                     As an acidulant.

    Biological Data

    Biochemical aspects

         The constituent ions of hydrochloric acid are normal participants
    in animal and human metabolism and, per se, of no toxicological
    significance. Toxicological considerations are involved either in the
    purely local action of the corrosive acid or in the effects of the
    addition of large quantities of either hydrogen or chloride ions to
    the electrolyte pool of the body. The hydrolytic action of
    hydrochloric acid on food substances is similar, in principle, to that
    of the acid occurring in normal gastric juice. In addition,
    hydrochloric acid regulates the pepsin activity of gastric juice
    (LeVeen, 1947). Physiological investigations also ascribe to
    hydrochloric acid a role in controlling the tone of the pylorus, and
    thus the rate of gastric emptying, as well as the amount of acid
    secretion in the stomach.

    Acute toxicity


    Animal    Route           LD50            References
    Rabbit    Intragastric    900               Loewy & Munzer, 1923

         No formal acute toxicity tests are available.  Oxygen consumption
    and carbon dioxide production in rabbits given half the LD100 showed a
    variable but definite reduction for at least 24 hours, considerably
    beyond the probable period necessary for recovery from the acidotic
    effect of the acid ingestion, thus pointing to a systemic metabolic
    effect in corrosive acid poisoning (Loewy & Munzer, 1923)

         The effect in man of accidental or suicidal intake of
    concentrated 35-40 per cent. hydrochloric acid are well known and
    there are numerous reports in the medical literature. Intakes of 300
    ml concentrated hydrochloric acid appear to be fatal (Kremser, 1957)
    but persons having swallowed 20-100 ml have been reported to recover
    (Franzen, 1957; Hangleiter, 1939; Koberg, 1954; Kremser, 1957;
    Stratford, 1920; Tucker & Gerrish, 1960). Similar recoveries after
    taking large quantities of dilute acid (120 and 180 ml) have been
    reported (Marks et al., 1963).

    Short-term studies

         Rat. Groups of 10-60 rats were fed for 16 days on basal diets
    and drinking water containing 0.3 per cent. acid, 0.3 per cent. acid
    plus 20 per cent. pepsin, and 20 per cent. inactivated pepsin plus 0.1
    per cent. acid. One set of groups was fasted for 48 hours before,
    being allowed access to food and fluid on the third day and this cycle
    was repeated 5 times. All groups receiving acid in their drinking
    water developed peptic ulcer-like lesions if subjected to fasting, but
    no lesions were seen in the non-fasting group on 0.3 per cent. acid
    and the control groups. Histologically there was focal gastric
    submucosal oedema with extension to the epithelium and muscle layer
    with inflammatory cellular infiltration and ulceration (Matzner &
    Windwer, 1937).

    Observations in man

         Prolonged exposure to low concentrations of gaseous hydrochloric
    acid leads to erosion of teeth; exposure to acid mist produces
    bleeding nose and gums with ulceration of oral and nasal mucosa and
    tender facial skin (Patty, 1962).


         In concentrations approaching the physiological pH of gastric
    juice hydrochloric acid is probably of no toxicological significance.


         There appears to be no need to limit on toxicological grounds the
    use of hydrochloric acid in accordance with good manufacturing


    Franzen, J. (1957) Med. Klin., 19, 816

    Hangleiter, H. (1939) Sammlg von Vergiftungsfallen, 10, 195

    Koberg, H. (1954) Fortsch. Rontpr., 80, 784

    Kremser, K. (1957) Zentralbl. Chir., 34, 1435

    LeVeen, H. H. (1947) Gastroent., 8, 648

    Loewy, A. & Munzer, E. (1923) Bioch Z., 134, 437

    Marks, I. N., Bank, S., Werbeloff, L., Farman, J. & Louw, J. H. (1963)
    Amer. J. Dig. Dis., New Series, 8. 509

    Matzner, M. J. & Windwer, C. (1937) Amer. J. Dig. Dis., 4, 180

    Patty, F. A. (ed.) (1962) Industrial Hygiene and Toxicology, 2,

    Stratford, H. (1920) Brit. Med. J., ii, 164

    Tucker, A. S. & Gerrish, E. W. (1960) J. Amer. Med. Ass., 174, 890

    See Also:
       Toxicological Abbreviations
       Hydrochloric Acid (IARC Summary & Evaluation, Volume 54, 1992)