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    INTERNATIONAL PROGRAMME ON CHEMICAL SAFETY

    WORLD HEALTH ORGANIZATION



    TOXICOLOGICAL EVALUATION OF SOME
    FOOD COLOURS, EMULSIFIERS, STABILIZERS,
    ANTI-CAKING AGENTS AND CERTAIN
    OTHER SUBSTANCES



    FAO Nutrition Meetings Report Series 
    No. 46A WHO/FOOD ADD/70.36




    The content of this document is the result of the deliberations of the
    Joint FAO/WHO Expert Committee on Food Additives which met in Rome,
    27 May - 4 June 19691





    Food and Agriculture Organization of the United Nations

    World Health Organization



                   
    1 Thirteenth 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.


    DIMETHYLPOLYSILOXANE

    Some silicone fluids may contain five per cent. of silica.

    Biological Data

    Biochemical aspects

    No data available.

    Acute toxicity

                                                                     

    Animal    Route          LD100          Reference
                        mg/kg body-weight
                                                                     

    Rat       s.c.           > 5 000        Frazer et al., 1959
    "                        > 5 000             "
              i.m.           > 5 000             "
    "         i.p.           > 5 000             "
    Rabbit    s.c.           > 5 000             "
    "         i.m.           > 5 000             "
    "         i.p.           > 5 000             "
                                                                     

    Parentedal administration produced no significant gross or
    histopathological abnormalities nor was any silicate found in the
    urine of rats or rabbits (Frazer, 1959). Transient conjunctival
    irritation has been noted both in rabbits and man for 24-48 hours
    after contact (Child et al., 1951).

    The data on acute toxicity vary with the viscosity and are generally
    i.p. rat > 10 ml/kg body-weight (Rowe et al., 1948). Only
    hexamethyldisiloxane and dodecamethylpentasiloxane appeared to be
    toxic in acute tests and irritant on intradermal or subcutaneous
    application to rabbits. Twenty percutaneous applications of all
    silicone fluids for one month produced no adverse effects. (Rowe et
    al., 1948).

    Short-term studies

    Rat. Four groups of five female rats each were fed diets containing
    0 per cent, 0.1 per cent. silicone for three months. No adverse
    effects were noted on general condition, body-weight, growth rate,
    blood urea levels and organ weights. The histopathology of major
    organs was normal (Child et al., 1951).

    Groups of five female adult rats received 20 doses of 0, 1.0, 2.0,
    5.0, 10.0 and 20.0 g/kg body-weight of silicone fluid (350 cSt) over
    28 days without deleterious effects on growth, haematology, organ
    weights and histopathology (Rowe et al., 1948). Silicone fluids of
    viscosity 50, 350, 1000, 10 000, 60 000 cSt were fed for 90 days to
    five groups of 10 male and 10 female rats at a level of one per cent.
    in their diet. Twenty males and 20 females were controls. No
    significant adverse effects were noted on mortality and food
    consumption, body-weight, haematological indices, organ weights and
    histopathology (MacDonald et al., 1960).

    Groups of five male and five females rats were fed a diet containing
    one per cent. silicone fluids of viscosity 50 and 350 cSt for one
    year. Controls consisted of 10 male and 10 female rats. No adverse
    effects were noted upon body-weight, haematology blood urea, nitrogen,
    SGPT, cholesterol, serum alkaline phosphatase, urinalysis, organ
    weights. Histological findings in major organs were normal (Carson et
    al., 1966).

    A group of 10 rats (five male and five female) was fed a mixture (96
    per cent. liquid dimethylpolysiloxane and four per cent. silica
    aerogel) in the diet at a level of one per cent. for one year. Ten
    male and 10 female rats served as control. No significant differences
    were found between the test and the control animals in growth,
    body-weight, haematology, blond urea, urine analysis, serum glutamic
    pyruvic transaminase activity, organ weight (10 organs) and
    histopathology (13 organs) (Carson et al., 1961).

    Three groups of five males and five female rats were maintained for
    approximately 260 days on diets containing 0.0 per cent., 0.5 per
    cent., and two per cent. of a silicone emulsion consisting of 50 per
    cent Antifoam A (silicon with silica) with two per cent.
    pentaerythritol distearate as the emulsifying agent. No adverse
    effects were noted on body-weight and organ weights. Blood remained
    normal and no abnormal amounts of protein were seen in the urine.
    Histology of major organs was normal. No effects were seen on
    reproduction as measured by mating to produce and wean single sets of
    offspring in each group (Frodsham, 1956).

    Rabbit. In a similar experiment (see Carson, S., 1968) the same
    mixture was fed to a group of six rabbits (three male and three
    female) at a level of one per cent. in the diet for eight months. Six
    male and six female rabbits served as control. No significant
    differences were found between the test and the control animals in any
    of the parameters listed in the rat study (Carson, 1968).

    Groups of three male and three female rabbits were fed diets
    containing one per cent. silicone fluids of viscosity 50 and 350 cSt
    for eight months, Controls consisted of six male and six female
    rabbits. No adverse effects were noted upon body-weight, haematology,
    blood urea nitrogen, SGPT, cholesterol, serum alkaline phosphatase,
    urinalysis, organ weights. Histological findings on major organs were
    normal (Carson et al., 1966).

    Dog. Groups of two adult dogs each were fed doses of 0, 300, 1000 or
    3000 mg/kg body-weight silicone fluid five days each week for six
    months. Apart from moist and frequent loose stools in test dogs no
    abnormal effect on body-weight was noted. Small amounts of silicone
    could be recovered from the faeces of the group fed 3000 mg/kg
    body-weight. Haematology and urinalysis gave no abnormal findings.
    Gross and histopathology revealed nothing abnormal. The liver of all
    dogs fed silicone fluid but not of controls presented brown/black
    deposits of iron-free bile in the Kupffer cells and parenchyma, the
    quantities being directly related to the silicone dose administered,
    similar deposits were also found in the interlobular bile ducts of
    dogs fed the highest dose. The significance of these observations
    remains unexplained (Child et al., 1951).

    Long-term studies

    Rat. Groups of 25 male and 25 female rats were kept on a diet
    containing 0 per cent. or 0.3 per cent. silicone fluid for two years.
    There was no difference between tests and controls regarding
    appearance, growth, survival or morbidity, haematology blood urea,
    liver lipids, organ weights, macroscopic and microscopic pathology
    (Rowe, et al., 1950). In another study three groups of 30 female and
    10 male rats were fed a diet containing 0 per cent., 0.01 per cent.
    and 0.1 per cent. silicone fluid and observed for two years. Two
    further generations were reared and fed the same diets. The F1
    generation was autopsied at 28 weeks, the F2 generation at 25 weeks.
    There were no consistent adverse effects as regards body-weights,
    fertility rates, mean litter size, survival, organ weights, gross and
    histopathology. The consistent slight weight increase of the small gut
    was not statistically significant. No silica was found in the gut wall
    or any undue rise in other organs. Tumoric incidence was not abnormal.
    Liver function tests, urinalysis, fat absorption, renal function tests
    and haematology were not remarkable for F1 and F2 tests and
    controls (Frazer, 1959).

    Two groups of 10 weanling rats were kept on a diet containing 0 per
    cent. and 0.1 per cent. silicone fluid for two years, There was no
    consistent adverse effects as regards body-weight, behaviour, and
    histopathology (Gloxhubor u. Hecht, 1955).

    Comments

    Studies have been carried out on silicone fluids with and without the
    addition of silica. The presence of silica did not raise any
    toxicological problems nor did it affect the results of the
    experiments in a significant way. No bio-chemical studies are
    available. Short-term studies have been carried out in several
    species, including one study on an emulsion of dimethylpolysiloxane,
    but only one adequate long-term study of dimethylpolysiloxane fluid
    has been carried out in the rat. None of them has revealed any
    significant toxicity.

    EVALUATION

    Dimethylpolysiloxane fluid with or without silicon dioxide

    Level causing no significant toxicological effect in the rat

    0.1 per cent. (= 1 000 ppm) in the diet equivalent to 50 mg/kg body
    weight/day

    Estimate of acceptable daily intake for man

                                            mg/kg body-weight

    Temporary acceptance                         0 - 0.25

    Further work required by June 1974

    Metabolic studies in several species

    REFERENCES

    Carson, S., Weinberg, M. S. & Oser, B. L. (1966) Proceedings of the
    Scientific Section of the Toilet Goods Association, No. 45, 8-19

    Child, G. P., Paquin, H. O., jr & Deichmann, W. B. (1951) Arch.
    industr. Hyg., 3, 479

    Frazer, A. C. (1959) Unpublished report dated November

    Frodsham, J. (1956) Unpublished report No. 1HR/63, Imperial Chemical
    Industries Ltd., Industrial Hygiene Research Laboratories

    Gloxhuber, C. & Hecht, G. (1955) Arzneimittel, Forsch,  5, 10

    MacDonald, W. E., Lainer, G. E. & Deichmann, W. B. (1960) Arch.
    industr. Hyg., 21, 514

    Rowe, V. K., Spencer, H. C. & Bass, S. L. (1948) J. industr. Hyg.,
    30, 332

    Rowe, V. K. Spencer, H. C. & Bass, S. L. (1950) Arch. industr.
    Hyg., 1, 539
    


    See Also:
       Toxicological Abbreviations
       Dimethylpolysiloxane (WHO Food Additives Series 6)