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    INTERNATIONAL PROGRAMME ON CHEMICAL SAFETY

    WORLD HEALTH ORGANIZATION



    SUMMARY OF TOXICOLOGICAL DATA OF CERTAIN FOOD ADDITIVES



    WHO FOOD ADDITIVES SERIES NO. 12






    The data contained in this document were examined by the
    Joint FAO/WHO Expert Committee on Food Additives*
    Geneva, 18-27 April 1977




    Food and Agriculture Organization of the United Nations
    World Health Organization



    * Twenty-first Report of the Joint FAO/WHO Expert Committee on Food
    Additives, Geneva, 1977, WHO Technical Report Series No. 617

    BROWN FK

    EVALUATION FOR ACCEPTABLE DAILY INTAKE

    BIOLOGICAL DATA

    BIOCHEMICAL ASPECTS

         After an intraperitoneal dose to a rat of 1.5 g/kg body weight
    the extremities become orange in 60 minutes, and the animal sluggish.
    The urine was normal. After 24 hours the animal was normal but urine
    was deep orange-yellow (Goldblatt and Frodsham, 1952).

         After an intraperitoneal dose to a rat of 1.5 g/kg bw the
    extremeties become orange in 60 minutes, and the animal sluggish. The
    urine was normal but urine was deep orange-yellow (Goldblatt and
    Frodsham, 1952).

         On incubation with the contents of rat ileum and caecum Brown FK
    and its components undergo azo-reductive fission with formation of
    sulfanilic acid, a phenazine-like material (P) and ill-defined
    products that can be separated chrometographically. Brown FK, in
    common with other brown azo coloutings, also undergoes azo-reductive
    fission when incubated with rat-liver homogenate, but P has not been
    detected among the products. Oral administration of Brown FK to rats,
    pigs, rabbits and guinea-pigs results in the excretion of sulfanilic
    acid in urine and faeces; P is detectable in trace/small amounts in
    faeces, but is mainly present in caecal contents, predominantly during
    the first six hours after dosing. A "blue material" is excreted in the
    urine. On intraperitoneal administration to rats, Brown FK initially
    gives rise to brown colouring in bile; later, sulfanilic acid and the
    "blue material" appear in the urine. P is not found in faeces or in
    caecal contents.

         As formed in vitro from Brown FK, P is a complex mixture
    comprising two main components P1 and P2. P1 has been identified as
    1,4,7-tri-aminophenazine and P2 is probably a methylhomologue of P1
    (Fore and Walker, 1967; Fore, Walker and Goldberg, 1967).

         The metabolism of Brown FK would be extremely difficult to study
    since the final metabolite mixture from the many components would be
    exceedingly complex. Investigations have therefore been carried out on
    the major components: 1,3-diamino-4-(p-sulfophenylazo)benzene
    ("azo-benzene" component) and 2,4-diamino-5-(p-sulfophenylazo)toluene
    ("azo-toluene" component). The metabolism of both components was
    qualitatively similar, a proportion being excreted unchanged but the
    bulk reductively cleaved to sulfanilic acid and the corresponding
    amine (the latter being acetylated before excretion). Although the
    metabolism of only these two components of Brown FK has been studied,

    CHEMICAL STRUCTURE 1

    there is no reason to suppose that the metabolism of the other Brown
    FK components should be fundamentally different. The primary metabolic
    reaction in each case would be expected to be cleavage of the azo
    linkages. A summary of the products of azo reduction of the six major
    components of Brown FK is shown below (Howes, 1969; Munday and Kirkby,
    1969).

    CHEMICAL STRUCTURE 2

    Metabolism of the "azotoluene" component of Brown FK in the rat

         Preliminary examnation of urine from rats fed the "azotoluene"
    component of Brown FK showed the presence of sulfanilic acid and small
    quantities of unchanged dye. Examination of an extract of this urine
    revealed the presence of 5-acetamido-2,4-diaminoteluene (the major
    metabolite), 2,5-diacetamido-4-aminotoluene, 2,4-diacetamido-5-amino-
    toluene and 4,5-diacetamido-2-aminotoluene.

         Unchanged dye was again identified in faecal extracts; no other
    dye-derived compounds were detected.

         The metabolism of the "azotoluene" component of Brown FK is
    summarized below: (Munday 1969).

    CHEMICAL STRUCTURE 3

         An attempt was made to determine whether the "azobenzene"
    component of Brown FK is reductively cleaved in humans, as in rats.
    Reduction of the closely-related compound, protosil rubrum (XIII) has
    been shown to take place in human subjects (Fuller, 1937).

    CHEMICAL STRUCTURE 4

         Administration of the "azobenzene" component of Brown FK to human
    subjects led to no detectable unchanged dye in the urine, and no
    appreciable urinary sulfanilic acid. It can be inferred from these
    results that the "azobenzene" component is not absorbed from the
    intestine as such, but they give no information on the possible
    reduction of this compound in vivo, since it was shown that orally
    administered sulfanilic acid was not absorbed in man. Sulfanilic acid,
    if formed from the dye, would therefore be excreted in the faeces; the
    experimental confirmation of this would be technically very difficult
    and these studies were not pursued further (Jenkins and Favell, 1971).

         1,2,4-triaminobenzene and 2,4,5-triaminotoluene have been shown
    to uncouple oxidative phosphorylation in vitro, interfering with ATP
    production in the muscle cell and to ionic imbalance with cell death
    (Munday, 1971).

    Acute toxicity

                                                                        

    Animal      Route   LD50 mg/kg body weight   Reference
                                                                        

    Mouse       oral    >2 000 (with salt)       Grasso et al., 1968
                oral    1 100-2 250 (with salt)  Edwards and Wilson, 1966
                oral    960-1 140 (no salt)      Edwards and Wilson, 1966
                i.p.    1 500-2 000 (with salt)  Grasso et al., 1968
                i.p.    960-1 720 (with salt)    Edwards and Wilson, 1966
                i.p.    840- 880 (no salt)       Edwards and Wilson, 1966

    Rat         oral    > 8 000 (with salt)      Grasso et al., 1968
                oral    900-1 910 (with salt)    Edwards and Wilson, 1966
                oral    780- 970 (no salt)       Edwards and Wilson, 1966
                i.p.    750-1 150 (with salt)    Grasso et al., 1968
                i.p.    1 100-2 250 (with salt)  Edwards and Wilson, 1966
                i.p.    960-1 150 (no salt)      Edwards and Wilson, 1966

    Guinea-pig  oral    3 000 (with salt)        Edwards and Wilson, 1966
                oral    2 610 (no salt)          Edwards and Wilson, 1966
                i.p.    900 (with salt)          Edwards and wilson, 1966
                i.p.    780 (no salt)            Edwards and Wilson, 1966

    Rabbit      oral    450- 680 (with salt)     Edwards and Wilson, 1966
                oral    390- 590 (no salt)       Edwards and Wilson, 1966

    Chicken     oral    > 10, 000 (with salt)    Edwards and Wilson, 1966
                oral    >8 700 (no salt)         Edwards and Wilson, 1966
                                                                        

         For all species, animals dying did so from within a few minutes
    to 96 hours. Many animals, after either oral or intraperitoneal
    treatment, showed lack of coordination, hypersensitivity and
    hyperactivity; convulsions usually preceded death (Edwards and Wilson,
    1966).

         Meningeal congestion or haemorrhage was seen at post-mortem
    examination in rats and mice which died following both oral and
    intraperitoneal treatment with 3.4 g/kg of Brown FK as a 10% solution.
    This was the highest dose administered and the condition may have been
    present to a lesser degree in animals treated with lower levels of
    Brown FK but postmortem identification of the lesion was made

    difficult by tissue coloration. The meningeal congestion/haemorrhage
    was probably caused by the sodium chloride in the dye solution since
    we have observed this lesion after administration of hypertonic
    solutions of sodium chloride to rats. In this instance, the lowest
    dose levels at which the meningeal lesion has been observed were
    6.0 g/kg of sodium chloride orally as a 10% solution and 4.0 g/kg
    intraperitoneally as a 5% solution (Edwards and Wilson, 1966).

         Following oral intubation, external tissue coloration was
    apparent after some hours in rats and guinea-pigs. No coloration of
    the tissues was seen in rabbits and chickens. After intraperitoneal
    injection, external tissue coloration was apparent and intense after a
    few minutes in the rats and guinea-pigs.

         Colour was seen in the faeces of rats, mice, rabbits and guinea-
    pigs up to 24 hours aŁter oral treatment; it was also excreted in the
    urine of rats, mice, guinea-pigs and rabbits within 15 minutes of
    either oral or intraperitoneal treatment (Edwards and Wilson, 1966).

         Hearts from some rats and mice surviving for 21 days after
    treatmant were examined histologically. A degenerative lesion was
    found in 15% of rats given orally 1-2.5 g/kg body weight but not with
    3.37 g/kg. The same lesions were found in mice in 50% given orally
    0.9 g/kg but not if given 0.6, 1.35 and 2.03 g/kg. If given
    intraperitoneal 25-60% of mice showed lesions at 0.75 and 1.03 g/kg
    body weight (Edwards and Wilson, 1966).

         Amines derived from Brown FK and from its two myotoxie
    components, 2,4-diamino-5-(p-sulfophenylazo)toluene and 1,3-diamino-4-
    (p-sulfo-phenylazo)benzene were injected intravenously into rats in
    single doses of 3.13-25 mg/kg. The mixture of amines from Brown FK was
    also injected into mice in the same range of doses. Cardiac and
    muscular lesions were produced by the amines in both species. These
    amines are biological degradation products in the intestine. The
    finding that orally administered Brown FK is myotoxic in rats but not
    in mice is probably due to differences in the intestinal flora in the
    two species (Walker, Grasso and Gaunt, 1970).

    Investigation of the pigment deposited

         After feeding Brown FK to rats and mice pigment is found in
    heart, skeletal muscle, tongue, diaphragm, thyroids, brain, liver,
    kidneys, spleen, lungs, pancreas, bladder, testes, ovary, uterus,
    skin, stomach, duodenum, ileum, brown fat and bone marrow. In
    addition, a pigment has been detected in the plasma of rats.

         Staining tests commonly used to identify lipofuscin were negative
    with the exception of the test for metachromasia with toluidine blue.
    The tests applied were as follows:

                                                                        

                           Usual response of   Response of Brown FK
                           known lipofuscin    induced pigment
                                                                        

    Test for iron          negative            negative

    Sudan fat stains       positive            negative

    Reduction of
    ferric salts           positive            negative

    Reduction of
    ammoniacal silver
    salts                  positive            negative

    Basophilic properties  positive            negative

    Periodic acid -
    schiff reaction        positive            negative

    Acid fastness          acid fast           negative

    Toluidine blue
    at pH 3                stains              greenish
                           metachromatically
                           green
                                                                        

         Two further histochemical tests clearly differentiate between
    lipo-fuscin and the Brown FK - induced pigment:

         - Potassium permanganate/oxalic acid bleached lipofuscin, but not
    the brown FK - induced pigment.

         - Sodium dithionite bleached both lipofusein and the Brown FK
    induced pigment. However, after rinsing and allowing to stand in air,
    the Brown FK - induced pigment reappeared; lipofusein was permanently
    bleached.

         The Brown FK - induced pigment does not fluoresce in ultra-violet
    light. All the samples of lipofuscin which we have examined were
    fluorescent. Pigment has been found in the thyroid, brown fat and bone
    marrow; these tissues have not been recorded as being sites for
    lipofuscin deposition. Furthermore, a coloured substance has been
    demonstrated in the plasma, never lipofuscin.

         The speed at which the Brown FK - induced pigment is deposited is
    uncharacteristic of lipofuscin information. In acute studies, pigment
    has been seen in the intestinal wall and villi within 24 hours of
    feeding the dye, and in the kidney after five days. Pigment masses
    produced in macrophages either in vivo after the intraperitoneal
    injection of Brown FK into mice, or in vitro, when Brown FK was
    incorporated in the macro-phage culture medium, appeared identical.
    Tests for lipofuscin proved negative; the pigment in the macrophages
    closely resembled that seen in macrophages in stained sections of
    tissues taken from rats and mice fed Brown FK.

         Electron microscope studies have identified differences in
    morphology between lipofuscin and the Brown FK - induced pigment. In
    aged rats and mice fed Brown FK, conjugate forms were observed in
    which induced pigment and control lysosomal material appeared in the
    same membrane limited body (Hope, 1971).

         It is likely that this compound oxidises within the cell to
    1,4,7-triaminophenazine

    CHEMICAL STRUCTURE 05

         This would also explain the behaviour of the pigment with
    sodium dithio-nite.  The latter reduces the phenazine ring to
    5,10-dihydroderivative which is probably colourless. After exposure to
    air reoxidation would occur. Thus the pigment may not represent
    evidence of sub-lethal cell damage, but is more an insoluble oxidation
    product of a dye metabolite.

         1,2,4-triaminobenzene was very rapidly oxidized to
    1,4,7-triamino-phenazine by a mitochondrial suspension; no
    phenazine derivatives were detected with triaminotoluene under
    the same circumstances (Kirby, 1968).

         1,4,7-triaminophenazine is a brown, water-insoluble material,
    which is very readily formed from 1,2,4-triaminobenzene (Muller,
    1889).

    Short-term studies

    Mouse

         Groups of 10 male and 10 female mice received the colour (both
    fresh and stored) at the level of 1 g/kg daily for three weeks. A
    significant reduction in weight gain was noted in the mice receiving
    the stored solution but not in those receiving fresh solution. One
    male and one female receiving the fresh solution showed cardiac
    lesions (BIBRA, 1964).

         Daily oral or intraperitoneal doses up to 2 g/kg or 1 g/kg
    respectively for 43 days to groups of 10 or 12 mice were well
    tolerated (Grasso et al., 1968).

         Groups of 10 male and 10 female mice (Colworth C57 B1 strain,
    initially six weeks old) were fed for 90 days on a synthetic diet
    containing 0, 0.05, 0.075, 0.10, 0.25, 0.50, 0.75, 1.0 and 2.0% of
    Brown FK (equivalent to 0, 0.025, 0.0375, 0.05, 0.125, 0.25, 0.375,
    0.50 and 1% Brown FK coloured components) composition 51% colour,
    47% salt. A further group of 20 mice were fed synthetic diet
    containing added 1.0% sodium chloride as a control for the additional
    dietary salt derived from the Brown FK. At the 0.125% dietary colour
    level pigment deposition occurred in tissues. At 0.25% and above there
    was splenic enlargement, at 0.5% liver and heart were also enlarged
    and at 1% there was reduced growth, poor food utilization, liver,
    spleen, heart and testicular enlargement and histological evidence of
    degenerative heart lesions. Thyroids, muscle, intestine and squamous
    part of stomach were pigmented (Ashmole et al., 1958).

    Rat

         Groups of animals received the colour at the level of 0.5 g
    Brown FK per kg body weight for three weeks, orally or
    intraperitoneally. When dosed orally, 20 rats were treated and six
    animals died between five and 11 doses. Post-mortem examination of
    rats dying during the test or killed at the end revealed general
    tissue staining in five rats. Of 18 hearts examined histologically,
    eight showed degenerative lesions and a brown pigment was observed in
    small amounts in nine hearts after three weeks.

         In the multiple dose intraperitoneal test, eight rats were
    treated and none died during the treatment period. General organ
    staining was observed in all animals at post-mortem examination.
    Hearts from seven rats were examined microscopically and degenerative
    lesions were found in one heart and small amounts of pigment in three
    hearts after three weeks (Kirkby, 1968).

         No ill-effects were seen in three weanling rats given a 0.1%
    solution for 28 days, the intake being 15 mg/day (Goldblatt and
    Frodsham, 1952).

         Administration of two or three oral doses of 1 g/Brown FK/kg bw
    to rats induced a myopathy in cardiac and skeletal muscles
    characterized by multiple vacuoles about 1-2 µ in diameters.
    Ultrastructurally, these were shown to consist of areas of
    fibrillolysis. Histochemically, the myopathy was accompanied by a
    moderate increase in acid-phosphatase activity and by a loss of
    phosphorylase activity. Subsequently complete lysis of the affected
    fibres ensued. In the heart, lysis was followed by macrophage invasion
    and fibroblastic proliferation, and in skeletal muscle by
    regeneration. The occurrence of lipofuscin in muscle fibres and in
    macrophages was scanty and erratic. When Brown FK was given in the
    diet at a level of 2%, fibrillolysis and an increase in the number and
    electron-density of lysosomes was observed ultrastructurally during
    week two to three of the test. These changes were accompanied by a
    marked elevation of histochemically demonstrable acid phosphatase.
    Progressive deposition of lipofuscin was the principal pathological
    feature during week three to 12 (Grasso et al, 1968).

         Daily oral doses up to 2 g/kg for 43 days to groups of 10 rats
    induced rapid loss of weight and death, with severe damage to cardiac
    and skeletal muscle, characterized by vacuolar myopathy and lipofuscin
    deposition. Of three pure components of Brown FK studied, one
    (2,4-diamino-5-(p-sulfophenylazo)toluene) and to a lesser extent
    another (1,3-diamino-4-(p-sulfophenylazo)benzene) produced similar,
    but not identical lesions to those induced by the parent colouring
    after repeated oral doses of 0.5 g/kg. Ultrastructural studies
    confirmed the extensive loss of myofibrillar elements and
    histochemical studies revealed a loss in the activity of mitochondrial
    enzymes. Similar intraperitoneal injections in doses up to 1.0 g/kg
    for 43 days to groups of 10 or 12 rats did not have any effect on the
    heart or skeletal muscle (Grasso et al., 1968).

         In a series of experiments using groups of 10-12 rats receiving
    the colour at levels of 1 and 0.1 g/kg orally and 1, 0.25 and 0.1 g/kg
    intraperitoneally daily up to a maximum of 43 doses the following
    observations were made. A specific cardiac lesion was identified at
    the oral dose of 1 g/kg. There were large areas of myocardial necrosis
    and replacement by large mononuclears, with involvement of the
    sub-pericardial region and endocardium. Some myocardial cells had lost
    their stainable cytoplasm and appeared only as empty sheaths.
    Intraperitoneally, the colour produced little or no cardiac damage at
    any dose tested. At these high doses of 1 g/kg, most animals showed
    congestion, fatty change or necrosis of the liver with hydropic
    degeneration of the kidney. There was no obvious splenomegaly. Daily
    doses of 100 mg/kg by stomach tube produced two pericardial and one
    sub-pericardial lesions. In addition, early hydropic degeneration of
    the kidney was seen in two rats with one of those animals also showing
    fatty change in the liver (BIBRA, 1964).

         Administration of Brown FK (purity 80.0%) at dietary levels of
    0, 0.001, 0.01, 0.1 and 1.0% for 150 days showed no adverse effects on
    growth, food consumption, haematological indices, liver and kidney
    function and organ weights. One male rat at the 1.0% level showed the
    typical myocardial changes, other rats showed deposits of lipofuscin
    especially in females. The no-effect level was 0.1% (Gaunt et al.,
    1968).

         Groups of 12 male and 12 female rats (Colworth Wistar strain,
    initially three to four weeks old) were fed for 112 days on a
    commercial stock diet, containing 0, 0.05, 0.1, 0.5, 1.0 and 2.0% of
    Brown FK (0, 0.025, 0.05, 0.25, 0.5 and 1% Brown FK coloured
    components) 51% dye component, 47% salt. A further group of 24 rats
    were fed the commercial stock containing an added 1% sodium chloride
    as a control for the additional dietary salt derived from the
    Brown FK.

         In addition, to eliminate damage to the heart from cardiac
    puncture in any rat kept to 16 weeks, groups of six male and six
    female rats were fed for six weeks on powdered stock diet containing
    0, 0.05, 0.5 and 2.0% of Brown FK (0, 0.025, 0.25 and 1.0% Brown FK
    coloured components). A group of 12 rats also received 1.0% sodium
    chloride added to the basic diet. All these rats were used for
    biochemical tests during weeks 0-6 after which they were killed. At
    the 0.25% level tissue pigmentation appeared, at 0.5% liver
    enlargement occurred and at the 1% level there was reduced growth,
    poor food utilization, enlargement of liver, testes and thyroid,
    histological evidence of degenerative heart lesions, increased urinary
    indican excretion and elevation of SGOT. The intestine and squamous
    portion of stomach as well as thyroid were stained. The no effect
    level was 0.05% (Ashmole et al., 1966).

    Pig

         Groups of female and male pigs were given doses of 0, 100, 250
    and 500 mg/kg/day for 24 weeks without adverse effects on growth, food
    consumption, haematological indices, liver and kidney function and
    organ weights. Lipofuscin was widely distributed in both sexes at all
    dose levels in one or more organs. It particularly affected the liver,
    where it was accompanied by increased lysosomal enzyme activity, more
    marked at the higher dose levels. It was also seen in the heart in
    males and here it was associated with an increased acid-phosphatase
    activity, and in the kidneys, at the highest dose level in females and
    at all levels in males. A no-effect level was not seen (Gaunt et al.,
    1968).

    Special studies on "azobenzene" and "azotoluene" components

    Mouse

         Groups of three male and three female mice (C57 B1) were fed 0,
    0.5 and 1.0% of components in a synthetic type diet for six weeks.
    With both compounds the thyroids were dark and intestine and squamous
    portion of stomach were stained salmon pink. Heart lesions were seen
    in all mice fed 1% azotoluene and not in those given azobenzene. More
    pigment was seen in mice fed azobenzene component, little in those fed
    azo-toluene component (Kirkby, 1968).

    Rat

         Groups of three male and three female Colworth Wistar rats were
    fed azobenzene and azotoluene component at dietary levels of 0, 0.5
    and 1% in commercial stock diet for six weeks. The thyroids of rats on
    "azo-benzene" were dark, heart, muscle and brain were stained but the
    intestine was stained only slightly. Pale hearts and meningeal
    haemorrhage were seen with "azotoluene", otherwise pigmentation was as
    with "azobenzene". One-sixth "azobenzene" and 4/5 "azotoluene" rats
    had heart lesion. Most pigment was seen histologically in "azobenzene"
    rats, least in "azo-toluene" rats (Kirkby, 1968).

         In another study 1,2,4-triaminobenzene was given to groups of six
    to seven rats orally five days per week for two weeks at 50, 60, 75
    and 100 mg/kg body weight/day. Six-sevenths receiving 100 mg/kg/day
    died after three doses with severe heart lesions, 7/11 on 75 mg/kg/day
    also died after three doses. Heart pigmentation occurred after five
    days treatment or longer. Animals on lower doses showed both extensive
    heart pigmentation and cardiac necrosis. 1,2,4,5-tetraaminobenzene was
    given to groups of six rats orally five days per week for two weeks at
    150 and 200 mg/kg body weight/day. 1,2,3,4-tetraaminobenzene was given
    to groups of six rats orally five days per week for two weeks at 125
    and 166 mg/kg body weight/day. No frank heart lesions and only
    instances of diffuse increase in interstitial cells in the heart were
    observed. No heart or thyroid pigment deposition was seen (Mulky et
    al., 1969).

    Long-term studies

    Mouse

         Groups of 40 male and 40 female Colworth C57 B1 mice were fed for
    80 weeks on a synthetic diet containing 0, 0.0125%, 0.0375%, 0.075%,
    0.125% and 0.625% Brown FK coloured components (Brown FK purchased
    contained 62.5% coloured components). Only at the 0.625% was there
    reduced growth and food utilization and higher mortality among
    females. There was increased liver, kidney, spleen, brain and testes

    weight, evidence of splenic haemopoiesis, increased myocardial
    fibrosis. Heart weight was increased at the 0.125% level. Increased
    hepatic nodules were seen as from 0.075% and pigment deposition as
    from 0.0375% level. At termination, after 80 weeks, the number of
    animals with nodules for the different dose levels was 26, 23, 27, 56,
    42 and 64 respectively. Increased hepatic nodules were observed at
    dose level 0.075% and higher. The number of mice with hepatocellular
    carcinoma were 3, 2, 0, 5, 6 and 2 respectively. Pigment deposition
    was observed at dose level 0.0375% and higher (Wilson et al., 1970).

    Rat

         Groups of 32 male and 36 female Colworth Wistar rats were fed for
    two years on a synthetic diet containing 0, 0.01%, 0.03%, 0.06%, 0.1%
    and 0.5% of Brown FK coloured components (Brown FK purchased contained
    54.2% coloured components). Only at the 0.5% level was there increased
    splenic weight and hepatic granulomata. Pigment deposition was seen as
    from 0.06%. The no-effect level for pigment deposition was 0.03% and
    0.06% when based on toxicity evidence (Wilson et al., 1971).

    Special studies on mutagenicity

         Brown FK and its constituents were assayed for mutagenicity in
    Salmonella typhimurium TA 1535, TA 1537 and TA 1538 when activated
    by a rat liver supernatant fraction. Mutagenicity was linearly dose-
    dependent in the range 0-3 mg/plate with activities ranging from 22 to
    50 times the spontaneous mutation frequency. One sample of Brown FK
    was mutagenic in the absence of metabolic activation producing a
    16-fold increase in mutation at 4 mg/plate. Two major constituents of
    Brown FK, 2,4-diamino-5-(p-sulfophenylazo)toluene (I) and 1,3-diamino-
    4-(p-sulfo-phenylazo)benzene (II) each present at about 18% in the
    complete colour, were mutagenic in TA 1538. Mutagenicity was
    linearly dose-related in the range 0-1 µmol/plate, with slopes of
    0.35 mutants/nmol for compound I and 1.5 mutants/nmol for compound II.
    This activity was dependent on metabolic activation. Four other major
    constituents were inactive, as was sulfanilic acid, the major
    excretion product. The mutagenicity of Brown FK could be largely
    accounted for by the combined effects of compound I and II (Venitt and
    Bushell, 1976).

    REFERENCES

    Ashmole, R. T., Campbell, P., Kirkby, W. W. and Wilson, R. (1966)
    Effects of feeding dietary Brown FK to rats for six and 16 weeks.
    Unpublished report from Unilever Research Laboratories, submitted to
    the World Health Organization by Unilever Ltd.

    Ashmole, R. T., Kirkby, W. W. and Wilson, R. (1958) Thirteen week
    mouse feeding trial. Unpublished report from Unilever Research
    Laboratories, submitted to the World Health Organization by Unilever
    Ltd.

    Edwards, K, B. and Wilson, R. (1966) Acute toxicity of Brown FK in
    rats, mice, guinea-pigs, rabbits and chickens. Unpublished report from
    Unilever Research Laboratories

    Fore, H. and Walker, R, (1967) Studies on Brown FK. I. Composition and
    synthesis of components, Fd. and Cosmet. Toxicol., 5, 1-9

    Fore, H., Walker, R. and Golberg (1967) Studies on Brown FK. II.
    Degradative changes undergone in vitro and in vivo, Fd. and
    Cosmet. Toxicol., 5, 459-473

    Fuller, A. T. (1937) Lancet, 194

    Gaunt, I. F., Hall, D. E., Grasso, P. and Golberg, L. (1968) Studies
    on Brown FK. V. Shortterm feeding studies in the rat and pig,
    Fd. and Cosmet. Toxicol., 6, 301-312

    Goldblatt and Frodsham (1952) Private communication from ICI
    (unpublished report)

    Grasso, P., Muir, A., Golberg, L. and Batstone, E. (1968) Cytopathic
    effects of Brown FK on cardiac and skeletal muscle in the rat,
    Fd. and Cosmet. Toxicol., 6, 13-24

    Grasso, P., Gaunt, I. F., Hall, D. E., Golherg, L. and Batstone, E.
    (1968) Studies on Brown FK. III. Administration of high doses to rats
    and mice, Fd. and Cosmet. Toxicol., 6, 1-11

    Hope, J. (1971) Ultrastructure of the pigment induced in various
    tissues of the rat by long-term feeding of the dye Brown FK.
    Unpublished report from Unilever Research Laboratories, submitted to
    the World Health Organization by Unilever Ltd.

    Howes, D. (1969) Metabolism of 14C labelled 1,3-diamino-4-
    (p-sulpho-phenylazo) benzene, a component of the dye Brown FK, in the
    rat, Unpublished report from Unilever Research Laboratories, submitted
    to the World Health Organization by Unilever Ltd.

    Jenkins, F. P. and Favell, D. J. (1971) Metabolism of the
    "monoazobenzene" component of Brown FK in human subjects. Unpublished
    report from Unilever Research Laboratories, submitted to the World
    Health Organization by Unilever Ltd.

    Kirkby, W. W. (1968) Effects of Brown FK and two of its constituents
    on pigment deposition and lesions in rats and mice. Unpublished report
    from Unilever Research Laboratories, submitted to the World Health
    Organization by Unilever Ltd.

    Kirkby, W. W. (1968) Nature of the pigment induced in tissues of rats
    and mice fed Brown FK. Unpublished report from Unilever Research
    Laboratories, submitted to the World Health Organization by Unilever
    Ltd.

    Mulky, M. J., Munday, R., Ashmole, R. T. and Kirkby, W. W. (1969)
    Evaluation of the terminal causative agent in Brown FK induced
    myopathy and pigment deposition. Unpublished report from Unilever
    Research Laboratories, submitted to the World Health Organization by
    Unilever Ltd.

    Muller, E. (1889) Chem. Ber., 22, 856

    Munday, R. (1969) Metabolism of 2,4-diamino-5-(p-sulphophenylazo)
    toluene. Unpublished report from Unilever Research Laboratories,
    submitted to the World Health Organization by Unilever Ltd.

    Munday, R. (1971) Uncoupling of oxidative phosphorylation by Brown FK
    metabolites. Unpublished report from Unilever Research Laboratories,
    submitted to the World Health Organization by Unilever Ltd.

    Munday, R. and Kirkby, W. W. (1969) Metabolism of 1,3-diamino-4-
    (p-sulpho-phenylazo) benzene. Unpublished report from Unilever
    Research Laboratories, submitted to the World Health Organization by
    Unilever Ltd.

    Venitt, S. and Bushell, 0. T. (1976) Mutagenicity of the food colour
    Brown FK and constituents in Salmonella typhimurium, Mutation
    Research, 40, 309-316

    Walker, R., Grasso, P. and Gaunt, I. F. (1970) Myotoxtcity of amine
    metabolites from Brown FK, Fd. and Cosmet Toxicol., 8, 539-542

    Wilson, R., Gellatly, J. B. M., Kirkby, W. W. and Ashmole, R. T.
    (1970) Biological evaluation of Brown FK: 80-week mouse feeding trial.
    Unpublished report from Unilever Research Laboratories, submitted to
    the World Health Organization by Unilever Ltd.

    Wilson, R., Gellatly, J. B. M., Kirkby, W. W. and Ashmole, R. T.
    (1971) Biological evaluation of Brown FK: 2-year rat feeding trial.
    Unpublished report from Unilever Research Laboratories, submitted to
    the World Health Organization by Unilever Ltd.


    See Also:
       Toxicological Abbreviations
       Brown FK (WHO Food Additives Series 20)
       BROWN FK (JECFA Evaluation)