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.



         These substances have been evaluated for acceptable daily intake
    by the Joint FAO/WHO Expert Committee on Food Additives (see Annex 1,
    Ref. No. 13) in 1966.

         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.



         The polyglycerol esters of fatty acids include a large group of
    closely related compounds of complex composition. However, the
    individual components are found as normal constituents of the human
    diet, i.e. glycerol, glycerol mono-, di- and tri-fatty acid esters and
    individual fatty acids, with the exceptions of the artificially
    produced polymers of glycerol, polymers of certain fatty acids and the
    actual separate esters between these polymers. These latter compounds
    represent the toxicologically important constituents.

         In vitro experiments on lipase digestion of polyglycerol esters
    showed a slower rate of digestion than that of olive oil and the ester
    did not affect the lipase digestion of olive oil (Unilever Research
    Laboratory, 1966).

         Digestibility or caloric utilization have been used to
    demonstrate metabolic conversion; 16 male and female rats were fed a
    diet containing 1% ground-nut oil and 9% polyglycerol ester or 10%
    groundnut oil (as control) for six and 12 weeks. Polyglycerol ester
    as an energy source was almost equivalent to ground-nut oil, as
    measured by growth rate. Digestibility was calculated as 92%. In
    another experiment rats were kept on a restricted food intake
    (18 calories/day) for 17 days. After realimentation With 9%
    polyglycerol ester and 1% ground-nut oil, no adverse effect was noted
    on the animals' ability to gain weight. Rats fed polyglycerol ester
    for 54 days as 9% of the diet showed no difference in composition of
    carcass fat, liver fat, liver free fatty acids and liver phosphorus
    when compared with groups fed 1% or 10% ground-nut oil in the diet.
    Liver vitamin A levels were unaffected. A polyglycerol ester was shown
    to be absorbed by intestinal lymphatics, and chylomicron counts showed
    normal lipaemia. Suspensions in water were more slowly absorbed and

    reduced the rate of gastric emptying compared with ground-nut oil. The
    serum cholesterol level of rats was unaffected by the presence of 10%
    polyglycerol ester in a 42% fat diet (Unilever Research Laboratory,

         Hydrolysis of the tri- and polyglycerol esters in vitro with
    fresh pancreatic juice plus bile showed that 89 to 98% of oleate
    esters were hydrolyzed. Eicosanoate compounds were hydrolyzed at a
    much slower rate than the oleate esters.

         The metabolic fate of polyglycerol esters in rat has been studied
    using fatty acid 14C-labelled (oleic acid and eicosanoic acid),
    tri- and polyglycerol esters. More than 90% of the 14C label of the
    triglycerol and approximately 40% of the polyglycerol was absorbed.
    Hydrolysis occurred mainly before absorption. 66 to 70% of the
    radioactivity from the oleic acid and 55% from the eicosanoic-labelled
    compounds appeared as respiratory CO2 during the test period
    (51 hours); most of the remaining activity being incorporated into the
    carcass. Rats fed polyglycerol esters labelled with 14C in the tri-
    or poly-glycerol moiety excreted the unchanged polymerized glycerol,
    primarily in the urine with less than 7% of the 14C label appearing
    in respiratory CO2 and the carcass (Michael & Coots, 1971).

         Weanling rats were fed each day a restricted 5 g basic diet
    supplemented with either 0, 0.5 or 1 g lard or 1 g polyglycerol ester
    of various molecular weights prepared from cotton-seed or peanut oil.
    After three weeks, the rats were placed on unrestricted diets
    containing polyglycerol or lard of 8% for a period of eight weeks.
    Weight gain of rats fed the polyglycerol ester was the same as those
    fed lard. Autopsy and histopathological examination of liver, kidneys
    and ileum showed no compound-related effects. No appreciable residues
    of polyglycerol esters were detected in the epididymal fat (Babayan et
    al., 1965).


    Acute toxicity


         Rats given single doses of 7, 14 and 29 g/kg bw of a polyglycerol
    ester by intubation showed no signs of any toxic effect. Repeated
    dosing with 10 g/kg bw daily over five days caused no deaths. Rats,
    injected i.p. with 1, 3 and 7 g/kg bw, showed no adverse effects;
    single doses of 10 g/kg bw caused some peritoneal reaction but no
    deaths (Unilever Research Laboratory, 1966).


         Rabbits dosed orally with 10-29 g/kg bw showed no toxic effects.

    Short-term studies


         Thirteen rats maintained on 9% polyglycerol ester and 1% ground-
    nut oil for 17 weeks showed normal kidney function (Unilever Research
    Laboratory, 1966). Rats kept 22 weeks on 9% PGE + 1% ground-nut oil
    showed no difference in weights of liver, kidney, adrenal, spleen and
    testes when compared with controls on 10% ground-nut oil. Gross
    autopsy and histological examination of liver revealed no
    abnormalities (Unilever Research Laboratory, 1966).

         Groups each of 100 rats equally divided by sex were maintained
    on diets containing 0, 2.5, 5.0 or 10.0% of polyglycerol ester
    (deca-glycerol deca-oleate) for 90 days. There were no adverse effects
    on survival, growth, organ weights, body weight ratios and hematologic
    parameters. Urinary nitrogen values for female rats in the 10% group
    was significantly higher than controls at weeks three and nine of the
    study. Autopsy and microscopic examination of tissues did not show any
    compound-related effects. The percentage of dietary fatty acids
    absorbed, as measured by faecal fatty acids decreased as the level of
    polyglycerol ester increased in the diet (King et al., 1971).

         Rats were fed polyglycerol ester with a high melting point for
    eight months. No residues were detected in depot fat, or in fat of
    muscle, liver, kidney or spleen. When the esters were injected
    subcutaneously or intravenously, polyglycerol esters were detected in
    fatty deposits near the site of injection (Ostertag & Wurziger, 1965).

         Eight rats were maintained on a nutritionally adequate biscuit
    diet containing 15% of polyglycerol ester of fatty acids (Palsgaard
    No. 1016) for five weeks. No abnormalities attributable to the
    additive were apparent at autopsy and on histological examinations,
    the findings being as in a control group fed 15% of a vegetable oil in
    the diet (Briski, 1970).

    Long-term studies


         Groups of 25 male and 25 female mice were fed for 80 weeks on
    either polyglycerol ester or ground-nut oil at 5% in their diet. No
    adverse effect on body weight, food consumption, peripheral blood
    picture and survival rate were noted. Carcass fat of the test group
    showed no polyglycerol residues. The levels of free fatty acids,
    unsaponifiable material, fatty acid composition of carcass fat and
    organ weights were the same in test and control groups, except for the
    liver and kidney weights of female mice which were significantly
    higher. Microscopic examination of all major organs showed nothing
    remarkable (Unilever Research Laboratory, 1966).


         A test group of 22 rats, with a control group of 28, were kept
    on a diet containing 1.5% of polyglycerol ester for three generations
    and maintained for over one year without significant variation in
    fertility and reproductive performance. Gross and histological
    examination of the third generation revealed no consistent abnormality
    related to the test substance (Unilever Research Laboratory, 1966).'

         In another experiment 28 male and 28 female rats were fed 5%
    polyglycerol ester or ground-nut oil in their diet for two years. No
    adverse effects on body weight, food consumption, peripheral blood
    picture, and survival rate were noted. Liver function tests and renal
    function tests at 59 and 104 weeks were comparable between groups. The
    carcass fat contained no polyglycerol and the levels of free fatty
    acid, unsaponifiable residue and fatty acid composition of carcass fat
    were no different from controls. Organ weights, tumour incidence and
    tumour distribution were similar in control and test groups. Complete
    histological examination of major organs showed nothing remarkable
    (Unilever Research Laboratory, 1966).

         Mice were maintained on a diet containing 1% of a polyglycerol
    ester emulsifier for a period of 15.5 months. There were no
    significant differences between growth rate and longevity of test and
    control animals, nor was there any indication of carcinogenic activity
    (Bickel et al., 1964).


         Thirty-seven volunteers, aged 19 to 24, were fed 2-20 g
    polyglycerol ester per day for three weeks in their diet. No
    abnormalities were detected in plasma proteins, serum amino-acids,
    thymol turbidity, serum bilirubin, total and free serum cholesterol,
    serum alkaline phosphatase, SGOT, SGPT, cholinesterase, cholesterol
    esterase, 24 hour urine volume, urinary creatinine, urea output, total
    and split faecal fat or total faecal nitrogen (Unilever Research
    Laboratory, 1966).


         The toxicological assessment of this group of diverse but related
    substances is based on an evaluation of satisfactory evidence for one
    member and assumes that alterations in the fatty acid distribution or
    polyglycerol content of individual members have no toxicological
    bearing and only affect the physical and emulsifying properties of
    each ester. The metabolic studies point to hydrolysis of these
    polyglycerol esters in the gastrointestinal tract and the utilization
    and digestibility studies justify the assumption that the fatty acid
    moiety is metabolized in the normal manner. Analytical studies have
    produced no evidence of cumulation of the polyglycerol moiety in body
    tissues. Human studies showed no adverse effects.

         It is desirable to have properly conducted biochemical studies on
    other members of this group, that do not conform to the specifications
    detailed above, particularly those containing short-chain fatty acids.


    Level causing no toxicological effect

         Rat: 50 000 ppm (5%) in the diet equivalent to 2500 mg/kg bw.

    Estimate of acceptable daily intake for man

         0.25 mg/kg bw.*


         Desirable: Properly conducted biochemical studies on other
    members of this group that do not conform to the specifications
    already established, particularly those containing short-chain fatty


    Babayan, V. K., Kaunitz, H. & Slanets, C. A. (1965) J. Amer. Oil Chem.
         Soc., 41, 434

    Bickel, J., Therkelsen, A. J. & Stenderup, A. (1964) Arzneimittel
         Forsch., 14, 238

    Briski, B. (1970) Unpublished report, Institute of Public Health of
         Croatia, Yugoslavia

    King, W. R., Michael, W. R. & Coots, R. H. (1971) Tox. Appl. Pharm.,
         20, 327

    Michael, W. R. & Coots, R. H. (1971) Tox. Appl. Pharm., 20, 334

    Ostertag, H. & Wurziger, J. (1965) Arzneimittel-Forsch., 15, 869

    Unilever Research Laboratory (1966) Unpublished report


    *    As polyglycerol esters of palmitic acid.

    See Also:
       Toxicological Abbreviations
       Polyglycerol esters of fatty acids (FAO Nutrition Meetings Report Series 40abc)