Toxicological evaluation of some food
    additives including anticaking agents,
    antimicrobials, antioxidants, emulsifiers
    and thickening agents


    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


    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.


    (Includes; hydroxypropyl cellulose, hydroxypropyl methylcellulose,
    methylcellulose, methylethylcullulose, sodium carboxymethyl-cellulose)


         These substances have been evaluated for acceptable daily intake
    by the Joint FAO/WHO Expert Committee on Food Additives (see Annex 1,
    Refs Nos 7, 13 and 20) in 1963, 1966 and 1969.

         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.



    (a)  Hydroxypropyl cellulose

         14C-labelled hydroxypropyl cellulose was administered to four
    rats in a 5% aqueous solution. One male and one female rat received
    0.25 g/kg bw, the other two rats received 1 g/kg bw. Urine, faeces and
    expired air were collected over the next 120 hours. Then all organs
    were assayed for residual radioactivity. No activity (<0.01% of the
    administered dose) was detected in organs, urine and expired air due
    to administered material. Recoveries of activity in the faeces varies
    from 98.32 to 102.7%. Hence orally ingested material is not absorbed
    from the gastrointestinal tract of the rat and is excreted
    quantitatively in the faeces principally in the first 48 hours.

         To check on enterohepatic circulation two additional rats with
    ligated bile ducts were administered 1 g/kg of radio-labelled
    material. Bile was collected for 72 hours but no significant activity
    was found (Industrial Bio-Test Lab., 1964).

    (b)  Methylcellulose

         Methylcellulose is usually resistant to microbial attack (Bargen,
    1949). In rats it was not hydrolyzed to cellulose and methanol in the
    intestinal tract and it did not appear to be absorbed (Bauer & Lehman,

         Investigations on two male adults and one 10-year-old girl showed
    that methylcellulose passed through the digestive tract practically
    unaltered, when 5-10 g of methylcellulose were ingested the recovery
    of methoxyl groups from the faeces was almost quantitative. Methanol
    formation after the taking of methylcellulose was not significantly
    different from that under normal conditions (Machle et al., 1944).

         It has been stated that methylcellulose could be partly
    hydrolyzed in the digestive tract to units of lower molecular weight,
    as indicated by a decrease in viscosity. Such intermediate products
    obtained after acid hydrolysis were fed to mice at a dose of 1 g daily
    for 28 days without any demonstrable effect on growth rate (Letzig,

         There is some evidence for the excretion of methylcellulose into
    the milk of pregnant rats and this causes transient anaemia in
    suckling rats (Baldini, 1958).

    (c)  Methylethylcellulose

         After feeding a single dose of 0.6 g of methylethylcellulose in
    the diet of rats some 90% of the dose was recovered from the faeces by
    the end of the fourth day. Nearly all alkoxyl groups remained attached
    to the cellulose chain during passage through the gut (Gage, 1962).

    (d)  Sodium carboxymethylcellulose

         Sodium carboxymethylcellulose (CMC) is readily hydrolyzed by
    micro-organisms (Reese et al., 1950). Diastase and cellulases are
    stated to bring about the breakdown of this compound (Letzig, 1943).
    Pepsin and pancreatin, separately or in combination, do not attack the
    substance (Massatsch & Steudel, 1941).

         In five rats fed 5 g of CMC collectively, approximately 90% of
    the dose was recovered in the faeces (Shelanski & Clark, 1948).
    Experiments on six rats during four periods of 10 days each showed
    that CMC given in the diet at levels of 5%, 10% and 14% was reclaimed
    quantitatively in the faeces (Ziegelmayer et al., 1951).

         14C-tagged CMC, containing up to 0.34% radioactive sodium
    glycolate, was given orally to two groups of five male rats each in a
    dose of 400 mg. No detectable activity (less than 0.02% of the dose)
    was found in the livers and kidneys and about 0.14% of the
    administered radioactivity was found in the 48-hour urine samples.
    This amount, however, could be accounted for by the free radioactive
    glycolate present in the test compound (Wiebe et al., 1962).

         Only about 50% of the intake of CMC could be recovered from the
    faeces of two rabbits on diets containing 4.76% and 9% CMC.

         Two dogs received 10 g of CMC for one day and 20 g daily for the
    following five days. The total, doses were recovered quantitatively in
    the faeces (Ziegelmayer et al., 1951).

         Two human adults were given 30 g of CMC by mouth daily for four
    days and a third was given 20 g/day. About 90% of the compound was
    recovered from the faeces (Ziegelmayer et al., 1951).


    Special studies on carcinogenicity


         Subcutaneous implantation of 500 mg of methylcellulose as a
    powder in 25 rats failed to demonstrate carcinogenic properties
    (Hueper, 1959).

    Acute toxicity

    (a)  Hydroxypropyl cellulose

    Animal    Route    LD50 mg/kg bw     Reference

    Rat       Oral     10 200            Industrial Bio-Test Lab., 1962

    (b)  Hydroxypropyl methylcellulose (type B)

    Animal    Route    LD50 mg/kg bw     References

    Mouse     i.p.     5 000             Hodge et al., 1950

    Rat       i.p.     5 000             Hedge et al., 1950

    (c)  Methylcellulose

         LD50 values have not been found in the literature. In dogs,
    single intravenous injections of 40 ml of 0.7 to 2.8% solutions of
    methylcellulose in saline resulted, within 24 hours in a moderate
    anaemia and leucopenia and an increased sedimentation rate (Hueper,
    1944). In rabbits, intravenous injections of 10 mg/kg were followed by
    leucopenia. Injections of 10 to 100 mg/kg in a 1% solution had no
    effect on the blood pressure or respiration (Wiedersheim, 1953). In
    man, single oral doses of 5 g and 10 g were well tolerated (Maohle et
    al., 1944),

         Intravenous injection of a 1% solution in rabbits induced
    subintimal deposits of methylcellulose at arterial walls followed by
    extensive calcification, ossification, cartilage formation and lipid
    deposition (Stehbens & Silver, 1966).

    (d)  Methylethylcellulose

         No data are available but from short-term tests it can be
    inferred that 3 g daily in the diet had no effect in rats (Imperial
    Chemical Industries, 1966).

    (e)  Sodium carboxymethylcellulose

    Animal    Route    LD50 mg/kg bw     Reference

    Rat       oral     27 000            Shelanski & Clark, 1948

    Guinea-   oral     16 000            Shelanski & Clark, 1948

         Rats, guinea-pigs and rabbits showed no symptoms after
    administration by stomach tube of 3000 mg/kg in three divided doses
    (Rowe et al., 1944).

         Six rats given an intravenous injection of 40 ml of a 1.6%
    solution of CMC showed 48 hours later the presence of particles
    localized in cells of the reticulo-endothelial system (Jasmin & Bois,

         Four dogs given an intravenous injection of 40 ml of 0.25% CMC in
    1% sodium chloride solution reacted with a transitory leucopenia
    (Hueper, 1945).

    Short-term studies

    (a)  Hydroxypropyl cellulose


         Groups of five male and five female rats received in their diet
    0.2%, 1.0% and 5.0% of hydroxypropyl cellulose for 90 days. Controls
    received unmodified cellulose at the same levels. There were no
    differences observed between tests and controls as regards mortality,
    growth, food utilization, urinalysis, haemotological indices, organ
    weight, gross pathology and histopathology. At higher dietary levels
    there was increased food consumption and decreased food utilization
    consequential to the inertness of the material (Industrial Bio-Test
    Lab., 1963).

    (b)  Hydroxypropyl methylcellulose


         Groups of 10 male and 10 female weanling rats were fed diets
    containing 0, 2, 10 and 25% type B for 30 days. Only in the highest
    dose were interference with body weight gain and diarrhoea observed.
    There were no histological lesions nor were there abnormal findings in
    urine and blood (Hodge et al., 1950).

         Groups of 10 male and 10 female young rats were fed 0, 1, 3, 10
    and 30% of type A for 121 days. Body weight gain was markedly retarded
    at the 30% level, with 50% mortality attributed to under-nutrition.
    Only the male rats showed slight body weight gain retardation at the
    10% dietary level, while the weight gain was normal at the lower
    levels. Histological examination of internal organs revealed no
    abnormalities in any of the five groups (McCollister & Oyen, 1954).

         Groups of 10 male and 10 female young rats were fed diets
    containing 0, 0.3, 1, 10 and 20% of type C for 90 days. At the 20%
    level both sexes showed marked retardation of body weight gain, with
    30% mortality. At the 10% level male rats only showed slight but
    significant weight gain retardation. At the lower levels there were no
    adverse effects. The microscopic appearance of tissues was normal at
    all levels (McCollister et al., 1961).

         Groups of 10 male and 10 female young rats were fed 0, 0.3, 1, 3,
    10 and 20% of type D for 84 days. No adverse effects were noted with
    female rats at all levels. Male rats showed a definite retardation of
    body weight gain at the 20% level and a slight retardation at 10%.
    Organ weights and gross and microscopic examination revealed no
    adverse effects (McCollister et al., 1961).


         Groups of six rabbits were fed diets containing 0, 10 and 25%
    type B for 30 days. The group on the highest dose maintained, but did
    not increase, their body weight. Normal results were obtained from
    urine and blood analyses, comparison of organ weights and histological
    examination (Hodge et al., 1950).


         Groups of two dogs were fed for one year 0.1, 0.3, 1.0 and
    3.0 g/kg bw daily of type B without effect on body and organ weights,
    urine, blood and microscopic appearance of internal organs. One dog
    fed 25 g/kg bw daily for 30 days suffered no ill effects. Another dog
    fed 50 g/kg bw daily for 30 days exhibited some diarrhoea, slight
    weight loss and slight depression of red blood cell count without any
    histological changes (Hodge et al., 1950).

    (c)  Methylcellulose


         A group of 10 rats (five male and five female) was fed a diet
    containing 10% methylcellulose for 95 days. The male rats gained
    weight at the same rate as the controls. The females showed lower food
    intake and slight growth depression. No abnormalities were found at
    autopsy or on microscopic examination. Weights of heart, liver, spleen
    and kidney were normal. The stomachs were 15% heavier in the
    experimental group than in the controls (Tainter, 1943).

         Eighty rats received methylcellulose at the level of 0.8%
    in the diet and 1% in the drinking-water for eight months. This
    was equivalent to an average total daily intake of 436 mg of
    methylcellulose per animal. No effect on growth rate was observed in
    any of the animals. Water and food intake were normal. No gross or
    microscopic pathological changes were found post mortem (Deichmann &
    Witherup, 1943).

         Groups of five female rats were fed diets containing 1.66% and 5%
    methylcellulose for six months without any adverse effects (Bauer et
    al., 1944).

         Three groups of 10 rats (five male and five female) were given
    diets containing 0.17% (changed after six weeks to 0.5%) and 5%
    methylcellulose for eight months. No deleterious effect on growth
    was recorded, and macroscopic and microscopic examination of
    representative animals revealed essentially normal tissues. Deposition
    of abnormal material in the tissues was not observed. Reproduction was
    unimpaired through three generations. Second and third generation rats
    were fed a diet containing 5% methylcellulose for four months and
    responded normally (Bauer & Lehman, 1951).

         A modified paired feeding experiment was conducted on three
    groups of rats for 90 days: one group received a diet containing 50%
    methylcellulose, one a diet containing 50% cellulose powder, and one
    the basal diet. Growth depression was seen in the first two groups.
    Subsequent replacement of the methylcellulose or cellulose diet by the
    basal diet resulted in marked weight gain (Bauer & Lehman, 1951).

         In 28-day experiments with groups of 10 rats, some normal and
    others vitamin-depleted, the oral administration of 50 mg of
    methylcellulose did not affect the absorption of either 6 µg of
    thiamine or 3 units of vitamin A per day, as determined by weight gain
    (Ellingson & Massengale, 1952).

         Four intraperitoneal injections over 10 days of a maximal total
    dose of 160 mg of methylcellulose produced arterial hypertension and
    glomerulonephritis in rats given a 1% NaCl solution to drink.

         In a further experiment on rats methylcellulose was shown to
    deposit within the renal glomeruli leading to reduction of filtration
    and sodium accumulation if the latter is given as well. Hypertension
    and glomerular lesions developed (Hall & Hall, 1962a).

         Intravenous injections of 1% methylcellulose were made into rats
    at three-day intervals and produced splenic enlargement 21 days after
    the last injection. Survival time studies on red cells showed that the
    enlarged spleens destroyed red cells more quickly (Fitch et al.,
    1962). Intraperitoneal injections of 2.5% methylcellulose solution
    twice weekly into adult rats for one to 16 weeks reduced haematocrit
    and increased spleen weight in a dose-dependent manner. Foamy
    histiocytes accumulated in the spleen pulp and sinusoids. E.M.
    observations suggested lysosomal ingestion with phagolysosome
    formation (Lawson & Smith, 1968).


         Two dogs were fed doses of methylcellulose increasing from 2 g to
    100 g daily for one month without any noticeable effect (Bauer, 1945).

         Solutions containing 0.7 to 2.8% of methylcellulose of different
    molecular weights in 1% NaCl were administered by intravenous
    injection to 18 dogs in doses of 40 to 130 ml for five days a week.
    The maximum total dose of 5720 ml was injected within six months. Most
    of the animals died. Haematological reactions and the formation of
    foam cells were observed (Hueper, 1944).

    (d)  Methylethylcellulose

         None available.

    (e)  Sodium carboxymethylcellulose


         Ten rats received 300 to 500 mg of CMC daily for two months
    without any adverse effect (Werle, 1941).

         One group of rats (10 male and 15 female) was fed on a diet
    containing 5% CMC for 201 to 250 days. Judged by growth rate,
    mortality, organ weight and the results of histopathological
    examination of the liver, kidney, spleen, pancreas, adrenal gland,
    testis and gastrointestinal tract, there was no significant difference
    between the treated and the control group (Rowe et al., 1944).

         Another group of 10 rats received a diet containing 20% of CMC
    for 63 days. Slight growth retardation and a laxative effect were
    observed. Organ weights and both gross and microscopic pathological
    examination revealed no abnormalities (Rowe et al., 1944).

         Two groups of 100 rats received daily 500 and 1000 mg/kg bw of
    CMC mixed in their diets for six months. No adverse effects were
    observed in any of the experimental animals as determined by growth
    rate, fertility and examination of the blood, urine, and main tissues
    (Shelanski & Clark, 1948).

         Six rats were fed 14% of CMC in the diet for five weeks without
    demonstrable deleterious effect (Ziegelmayer et al., 1951).

         Ten rats given subcutaneous injections of CMC showed
    mast-cell-like elements within the adrenal medulla. Changes in the
    adrenocortical cells and the presence of granules in the adrenal-vein
    were noted occasionally (Selye, 1955).


         Two groups of 100 animals were fed CMC for six months at the
    levels of 500 and 1000 mg/kg bw daily mixed in the diet. No signs of
    toxicity were observed.

         Two groups of 20 guinea-pigs received CMC in their diet at rates
    of 500 and 1000 mg/kg bw daily for one year. As judged by weight gain,
    gross and histopathological examination, no adverse effects were noted
    (Shelanski & Clark, 1948).


         Three rabbits were fed CMC at levels of 4.8% and 9% in their diet
    for two periods of 15 days without any detectable toxic effects
    (Ziegelmayer et al., 1951).


         Two dogs were given daily doses of CMC (0.3-0.4 g/kg bw) in water
    by mouth for two months without adverse effects (Werle, 1941).

         Groups of 10 dogs were fed CMC daily in the diet at levels of 500
    and 1000 mg/kg bw for six months. Growth rate was the same in all
    groups. Six animals from each group were examined post mortem.
    Histologically the stomach, intestines, spleen, kidney, heart, lung
    and pancreas in the treated animals were no different from those of
    the controls (Shelanski & Clark, 1948).

         Five dogs received intravenous injections of 0.25% CMC in 1%
    sodium chloride solution in doses increasing from 40 ml to 150 ml for
    a maximum of three months. There were no gross pathological changes.
    Histopathological studies revealed uptake in the reticuloendothelial
    cells in the aorta (Hueper, 1945).


         Groups each of 20 one-day-old chicks were maintained on diets
    containing 0 or 2% sodium carboxymethylcellulose for 20 days. Addition
    of sodium carboxymethylcellulose to the diet resulted in decreased
    growth rate (Vohra et al., 1964).

    Long-term studies

    (a)  Hydroxypropyl cellulose

         None available.

    (b)  Hydroxypropyl methylcellulose


         Groups of 50 male and 50 female rats were fed for two years on
    diets containing 0, 1, 5 and 20% of type B. There was a slight
    retardation of body weight gain in the male group at the highest dose.
    Mortality ranged from 60 to 84% with no significant difference between
    the groups. Tumour incidence was the same in the experimental groups
    as in controls (Hodge et al., 1950).

    (c)  Methylcellulose

         None available.

    (d)  Methylethylcellulose


         Groups of 50 male and 50 female mice were fed 0, 0.1 and 1% of
    methylethylcellulose for two years. Body weight was slightly reduced
    in both sexes at the 1% level in the latter part of the test period.
    There was no difference between the groups in survival, tumour
    incidence, blood picture and gross and microscopic appearance of
    internal organs (Imperial Chemical Industries, 1966).


         Groups of 50 male and 50 female rats were fed 0, 0.1 and 1% of
    methylethylcellulose for two years. Body weight was reduced in males
    at the 1% level in the latter part of the test period. There was no
    difference between the groups in survival, tumour incidence, blood
    picture and gross and microscopic appearance of internal organs
    (Imperial Chemical Industries, 1966).

    (e)  Sodium carboxymethylcellulose


         Groups of 50 male and 50 female mice were maintained for up to
    100 weeks on ad lib. diets containing 0, 0.1 and 1% of sodium
    carboxymethylcellulose. There was no apparent difference in mortality
    and tumour incidence between the groups (Imperial Chemical Industries,


         Groups of 50 male and 50 female rats were maintained for up to
    two years on ad lib. diets containing 0, 0.1 and 1% of sodium
    carboxymethylcellulose. No difference in mortality and tumour
    incidence was apparent between the groups (McElligot & Hurst, 1968).

         Thirty rats were given weekly injections of 1 ml of a 2% aqueous
    solution of CMC subcutaneously. After 73 weeks, 43% of the animals
    showed tumours at the site of injection, characterized as
    fibrosarcomas of moderate malignancy by histological standards (Lusky
    & Nelson, 1957).

         Twenty rats were given subcutaneous injections once a week of 2%
    aqueous solution of CMC. In four animals tumours developed at the site
    of injection within 13 to 16 months. Two of the neoplasms were
    fibromas and two fibrosarcomas (Jasmin, 1961).

         Groups of 25 rats, divided about equally for sex, were placed for
    two years on diets containing CMC in concentrations providing 100, 500
    and 1000 mg/kg bw daily. Three generations of litters were produced
    and kept on the same diet as their parents. According to growth rates,
    monthly urine and blood examinations, fertility, and histopathological
    examination of the main organs, there were no differences between the
    test rats and the controls. No neoplasms were found in any of the
    experimental animals (Shelanski & Clark, 1948).


    (a)  Hydroxypropyl methylcellulose

         Twenty-five young human adults ingested doses ranging from 0.6 to
    8.9 g of type B on three separate occasions. Only a mild laxative or
    constipating effect was noted in several cases. About 97% of the dose,
    determined as methoxy groups, was recovered from faeces (Knight et
    al., 1952).

    (b)  Methylcellulose

         In three healthy adults 5 g of methylcellulose given twice a day
    for eight days approximately doubled the volume of the stools and
    increased their frequency slightly (Tainter, 1943).

         There was no evidences of toxicity when 1-6 g were taken daily
    as a laxative for four to 240 days (maximum 6 g for 240 days) by
    37 patients (Schweig, 1948), but doses of 2.5 to 5.25 g of
    methylcellulose taken orally as a gel in 250 ml of water were mildly
    constipating (Bauer, 1945).

         Patients have been given 2 g of methylcellulose before meals
    without toxic reactions (Bargen, 1949).

         Two patients given 60-90 ml of a methylcellulose preparation
    daily for five days developed generalized oedema, visual disturbances
    and neurological signs which disappeared within 72 hours of cessation
    of intake. Symptoms were paralleled by sodium and water retention,
    increased serum osmolality and reduced urinary aldosterone excretion
    (Crane et al., 1969).

    (c)  Sodium carboxymethylcellulose

         Daily oral doses of 20 to 30 g for seven days were well tolerated
    by three human subjects (Ziegelmayer et al., 1951).

         Eleven patients received 10 g daily for six months without
    complaint, but in seven further cases the dose had to be reduced owing
    to abdominal discomfort. No haematological changes were observed
    (Brick, 1952).

         Adult patients have been treated for more than a year with daily
    oral doses of 2-6 g of CMC as a laxative and there were no ill-effects
    (Brick, 1949; Fittipoldi & Davis, 1948; Schultz, 1949).

         Skin tests on 100 men and 100 women demonstrated that sodium
    carboxymethylcellulose is not a primary irritant, nor a sensitizer
    (Shelanski & Clark, 1948).


    (a)  Hydroxypropyl cellulose

         There is adequate evidence of the biochemical inertness of
    hydroxylpropyl cellulose and of the lack of absorption of the
    substance from the gastrointestinal tract. It resembles closely other
    modified celluloses.

    (b)  Hydroxypropyl methylcellulose

         No significant amounts appear to be absorbed from the digestive
    tract in man. A long-term study has been done on one particular type.
    Short-term studies have been done with four slightly different types,
    and gave consistent results.

    (c)  Methylcellulose

         The results of the short-term studies in rats, two of them for
    periods of eight months, are supported by evidence from the treatment
    of human patients demonstrating no adverse effects. As metabolic
    studies show no absorption from the intestinal tract, toxic reactions
    resulting from parenteral administration can be left out of

    (d)  Methylethylcellulose

         In view of the metabolic inertness and the virtual non-
    absorbability of this compound, evaluation is based on data provided
    for other members in addition to those referable to
    methylethylcellulose alone.

    (e)  Sodium carboxymethylcellulose

         Studies with radio-labelled CMC have shown that significant
    amounts of label are not absorbed from the digestive tract in man. The
    injurious properties that have been demonstrated in animals following
    parental administration can therefore be left out of consideration.


    Level causing no toxicological effect

         Rat: 50 000 ppm (0.005%) in the diet, equivalent to
    2500 mg/kg bw.

    Estimates of acceptable daily intake for man 

         0-25* mg/kg bw.**


    *    As sum of total modified celluloses.

    **   ADI may be exceeded for dietetic purposes. Dietetic in this
    context refers to a situation where use is primarily intended to take
    advantage of the non-caloric property of these additives.


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    See Also:
       Toxicological Abbreviations
       Modified celluloses (WHO Food Additives Series 26)