The evaluations contained in this publication were prepared by the
    Joint FAO/WHO Expert Committee on Food Additives which met in Rome,
    4-13 June 19741

    World Health Organization     Geneva     1975


    1  Eighteenth Report of the Joint FAO/WHO Expert Committee on
    Food Additives, Wld Hlth Org. techn. Rep. Ser., 1974, No. 557.
    FAO Nutrition Meetings Report Series, 1974, No. 54.

    MICROBIAL RENNET* (Mucor miehei)


         This enzyme preparation has been evaluated for acceptable daily
    intake by the Joint FAO/WHO Expert Committee on Food Additives (see
    Annex 1, Ref. No. 27) in 1971.

         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.



         No information available.


    Special studies on teratogenicity


         Groups of 19 or 20 pregnant rats received either 74, 148 or
    276 mg/kg agent by gavage from day 6 to 15 of pregnancy. Animals were
    sacrificed on day 20. No adverse effects were seen in pregnant dams.
    Litter parameters were unaffected except for mean pups weight which
    was slightly increased at the highest dose-level.

         The fetal anomalies observed were unrelated to administration of
    the test compound. No skeletal abnormalities were seen (Palmer &
    Lovell, 1970).

    Acute toxicity

         None available.


    *    This enzyme preparation is prepared from the species Mucor

    Short-term studies


         Four groups of 25 male and 25 female rats received in their diet
    0, 0.1, 0.5 and 2.5% of microbial rennet (equivalent to 0, 100, 500
    and 2500 units/kg/day) for one year. Appearance and behaviour
    was normal throughout the experiment. Survival was comparable
    in all groups and the few deaths observed were unrelated to the
    administration of the test substance. Mean body weight and food
    consumption were similar to controls. Haematology, blood chemistry and
    urinalysis showed nothing significant compared with controls. Relative
    organ weights, gross and histopathology showed nothing of note
    (Gesler, 1970).

         In another experiment groups of 20 male and 20 female rats
    received in their diet 0, 0.5, 1.5 and 5% of microbial rennet for one
    year. At the highest level of administration there was a small dose-
    related reduction in body weight gain in the males and in the females
    a slight reduction at the 1.5% level. No effect on food intake or
    conversion. At the 1.5% level there was very slight reduction in food
    intake of males only. Behaviour, appearance, urinalysis, haematology,
    gross and micropathology were normal (Wheldon et al., 1970).


         Four groups of five male and five female beagles received
    by daily gavage six times a week for one year either 0, 500 or
    2500 units/kg bw. Apart from some vomiting early in the study and
    occasional vomiting in the highest test group there was no further
    difficulty in administration. Behaviour, appearance, food consumption
    and mean body weight did not differ from controls. Haematology, blood
    chemistry, blood coagulation studies and urinalysis revealed no
    changes due to the administration of the test substance. Mean relative
    organ weights, gross and histopathology revealed no changes different
    from controls (Gesler, 1970a).

         Four groups of four male and four female beagles received 0,
    5000, 15 000 or 50 000 ppm of rennet in their diet for one year. No
    adverse effects due to the test compound were quoted as regards
    mortality, appearance, body weight, ophthalmoscopy, clinical
    biochemistry, haematology, and urinalysis, gross and micropathology
    revealed nothing abnormal (Noel et al., 1970).

    Long-term studies


         Groups of 20 males and 20 females received orally 100 mg/kg bw of
    active material for 24 months. No contemporary controls were used but
    reliance was placed on the known history of the colony. Conditions

    were not SPF and animals also received other agents and pesticides.
    Body weight gain was normal, six animals dying during the 24 months.
    Among 17 male survivors six had chronic bronchopneumonia, two had
    fatty liver, two had testicular atrophy and none had any tumours.
    Among 17 female survivors one benign fibroadenoma of the breast and
    one pulmonary tumour were seen. Three animals had chronic
    bronchopneumonia. There were other scattered lesions unrelated to
    treatment. One male and five females were mated and produced a normal
    litter of which five males and five females were treated with the
    agent for seven months and mated again to produce a second generation.
    No obvious gross abnormalities were seen (Mosinger, 1972).


         The available studies in two species including the long-term
    study in the rat reveal no adverse effects at 2.5% in the rat on
    100 mg/kg bw. The levels used would have revealed any deleterious
    effects due to mycotoxins. This meets with the requirements laid down
    by the Committee.


         Acceptable daily intake not specified.*


    Gesler, R. M. (1970) Unpublished report submitted by Travenol
         Laboratories Inc.

    Gesler, R. M. (1970a) Unpublished report submitted by Travenol
         Laboratories Inc.

    Mosinger, M. (1972) Report No. 730J02 to Novo Laboratories

    Noel, P. R. B. et al. (1970) Report 3530/70/342 by HRC dated
         20.10.1970 submitted to Novo Laboratories


    *  The statement "ADI not specified" means that, on the basis of the
    available data (toxicological, biochemical, and other), the total
    daily intake of the substance, arising from its use or uses at the
    levels necessary to achieve the desired effect and from its acceptable
    background in food, does not, in the opinion of the Committee,
    represent a hazard to health. For this reason, and for the reasons
    stated in individual evaluations, the establishment of an acceptable
    daily intake (ADI) in mg per kg of body weight is not deemed

    Palmer, A. K. & Lovell, M. R. (1970) Report 3578/70/390 by HRC dated
         6.10.70 submitted to Novo Laboratories

    Wheldon, G. H. et al. (1970) Report by HRC dated 22 October 1970
         submitted to Novo Laboratories

    See Also:
       Toxicological Abbreviations