This substance was evaluated for acceptable daily intake for man
    (ADI) by the Joint FAO/WHO Expert Committee on Food Additives in 1969
    and 1971 (see Annex I, Refs. 20 and 27). A toxicological monograph was
    issued in 1974 (see Annex I, Ref. 33).

         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.


         Modification is carried out by the use of 8% acetic anhydride and
    a maximum of 0.12% adipic acid, the latter acting as cross-linking
    agent. The maximum number of acetyl groups introduced is 2.5%. The
    number of adipic cross-links does not exceed more than 1 in about 1000
    glucopyranose units, or not more than 0.09% adipyl groups introduced
    in the starch.



         In vitro studies with pancreatin have shown that only the
    acetate ester bond splits easily while the adipic acid ester linkages
    are not attacked. No free adipic acid could be demonstrated in the
    hydrolysate (Morgareidge, 1959a). In vitro digestion with
    amyloglucosidase of acetylated distarch adipate showed a digestibility
    of 98.3% (Kruger, 1970). The metabolic fate of adipate-modified
    starches was investigated in male rats in vivo using adipic acid
    labelled at Cl and C6 with C14. The rate of appearance of 14CO2 was
    compared between labelled adipic acid and starch modified with 1,6-
    C14 adipic acid. Starch adipate is absorbed and/or metabolized more
    slowly than adipic acid, as evidenced by the delayed appearance of
    14CO2 in the respired air. 99.3% of the C14 activity of the free
    adipic acid was recovered in the respired air; 5.8% appeared in the
    urine while none was detected in the faeces in the gastrointestinal
    tract or in the carcass. 70.5% of the C14 activity of the esterified
    adipic acid appeared in the respired air and 7.2% in the urine; 24.5%
    was found in the faeces. No activity appeared in the carcass
    (Morgareidge, 1959b). The caloric equivalent of the modified starch
    was determined in groups of 10 male rats fed for 28 days on a basal
    diet containing either 1.5 or 3.0 g of starch supplements. The
    modified starch had been treated with 0.2% adipic anhydride and 5.5%
    acetic anhydride. Native starch was used as control. Caloric values
    were determined from a dose/response curve obtained by the use of 0,

    0.75, 1.5, 3.0 and 4.5 g of sucrose supplements equivalent to 0, 3, 6,
    12 and 18 calories per day. There was no difference in caloric value
    between the modified and unmodified starches (Oser, 1961).


    Special studies on kidney lesions associated with dietary
    modified starch


         Groups of 10 male and 10 female Syrian golden hamsters, weighing
    30-40 g, were fed a diet containing either 30% acetylated distarch
    adipate or 30% untreated starch for 30 days. Hamsters fed the test
    diet exhibited a reduction in average daily weight gain, compared to
    control animals, but the average daily test diet intake was also
    reduced. Comparison of feed consumption to corresponding weight gain
    did not indicate a significant difference in efficiency of utilization
    of the test and control diets. No treatment-related differences were
    noted in haematology, clinical chemistry or urinalysis data. No
    treatment-related lesions were evident in histological sections from
    liver and kidney (Newberne & Buttolph, 1977).

         Groups of 8 male and 12 female Syrian golden hamsters (weanlings)
    were fed a diet containing either 30% acetylated distarch adipate or
    30% untreated starch for periods of either 30 or 60 days. The diets
    contained Ca, 0.51%, P, 0.4% and Mg levels ranging from 0.017% to
    0.210% (0.6% is the normal requirement). Ten animals/group (6 female,
    4 male) were sacrificed at day 30 and the remaining animals at day 60.
    At autopsy, animals on test diet showed increased caecal weight. No
    weight difference was observed for liver and kidney. Haematological
    studies showed no compound-related effects. Histological sections from
    kidney demonstrated an increased incidence of lesions (cortical
    scarring and tubular dilatation) associated with consumption of the
    test diet for 30 or 60 days. These kidney lesions did not appear if
    the test diet was supplemented with magnesium. Kidneys from hamsters
    fed acetylated distarch adipate were analysed for calcium and
    magnesium content by neutron activation analysis. No correlation was
    evident between kidney magnesium levels and either dietary magnesium
    levels or severity of renal lesions. However, a suggestive correlation
    existed between kidney calcium levels and severity of lesions
    (Newberne & Buttolph, 1979a).


         Weanling Sprague-Dawley rats were distributed into groups of 6 or
    12 males or females and fed a test diet containing 30% acetylated
    distarch adipate + 10% unmodified starch or a control diet, consisting
    of 40% unmodified starch, for 30 days. The mineral mix in the diet was
    held constant, but Ca, P and Mg were varied according to design,

    which permitted manipulating the Ca/P content and ratios from
    1.5/1.36-0.5/0.56 to 0.1/0.76-1.6/0.26. The level of magnesium was
    0.06% (the required intake), but in 1 group with Ca/P Ca/P ratio of
    1.5/1.36 was lowered to 0.02% and in another group raised to 0.2%. One
    control group of Ca/P ratio of 0.5/0.56 had a magnesium level of
    0.04%. A total of 9 different groups were used in the study. Serum
    biochemistry and urinalysis were carried out on the test animals. At
    low dietary calcium/phosphate ratios, females on test diet experienced
    slightly elevated serum calcium. Serum magnesium tended to be
    depressed by low dietary calcium/phosphate ratios and by low dietary
    magnesium levels (0.02%), but was not affected by the test diet.
    Urinary magnesium levels tended to be increased in animals on the test
    diet. Fluctuations in other urinary electrolytes were affected by
    dietary calcium/phosphate ratios and magnesium content, but not by the
    test diet. Significant fluctuations occurred in urinary creatinine
    levels, but these fluctuations did not appear to be treatment related.
    At autopsy, organ weights showed no treatment-related effects except
    for the caecum, which was enlarged. Histopathological evaluation of
    kidney sections from control and test animals revealed a
    characteristic lesion consisting of mineral deposits in tubules at the
    corticomedullary junction. This lesion was not considered to be
    morphologically comparable to the "pelvic nephrocalcinosis" lesions
    previously reported in other laboratories. It was more common in
    females than in males. A high calcium/phosphorus ratio (5.8/1) and low
    phosphorus level (0.26%) in the diet prevented mineralization in
    kidneys of animals on test diet and significantly reduced this lesion
    in controls. There were no other compound-related effects.
    Histological examination of bone tissue and parathyroid glands showed
    no effect even with relatively severely imbalanced Ca/P ratios
    (Newberne & Buttloph, 1980).

         Groups of 25 female Sprague-Dawley rats were fed diets containing
    either 30% acetylated distarch phosphate or 30% unmodified starch
    (control) in a 1-year study with weanling rats (Experiment I) and a
    separate 9-month study utilizing 9-month-old rats (Experiment II). The
    calcium concentration in the diet was ca. 1%, phosphorus ca. 0.8% and
    magnesium ca. 0.15%. Urinary calcium concentration and total daily
    output were significantly increased in animals on the test diet
    (Experiments I and II), but only minor differences were seen in
    phosphorus, oxalate, magnesium and creatinine excretion. No
    significant effects were observed on body weight, food consumption,
    urine volume, urine pH and crystal content or faecal mineral content
    in animals on the test diet. At autopsy, caecal enlargement was
    present in treated animals, but no other treatment-related effects on
    relative organ weights were observed. No treatment-related
    histopathological effects were observed in the uterus or lower urinary
    tract, liver, parathyroid, caecum or ovaries in either experiment.
    Histological examination of kidney sections demonstrated the presence
    of treatment-related pelvic nephrocalcinosis. An apparent correlation

    was observed between the increased incidence of pelvic
    nephrocalcinosis, increased accumulation of calcium in the kidney, and
    increased urinary excretion of calcium. Residues of calcium in kidney
    tissue were significantly higher in test groups than in controls
    (Hodgkinson et al., 1981).

         Roe (1979) has conducted an extensive review of mineral
    deposition in the renal pelvis of rats and concluded that pelvic
    nephrocalcinosis, corticomedullary nephrocalcinosis, acute tubular
    nephropathy, and calculus formation are manifestations of mineral
    imbalance and are of relatively common occurrence in untreated
    laboratory rats (particularly older animals).

    Special studies on reproduction


         Groups of 10 male and 10 female rats, Sprague-Dawley-derived,
    were selected at random from a concurrent 2-year chronic toxicity
    study and, 6 weeks after weaning, mated to produce F1a and F1b
    litters. Test animals were maintained on a diet of 62% acetylated
    distarch adipate, while controls received 62% unmodified starch in
    their diet. After breeding was complete, parents were returned to the
    chronic study while 10 male and 10 female rats from the F1b litter
    were bred to produce F2a and F2b litters. A similar process was used
    to obtain F3a and F3b litters. In each generation, litters from the
    first mating were sacrificed at weaning and, from the second mating, 6
    weeks after weaning, except for the 10 males and 10 females selected
    for breeding. Pre-weaning deaths were significantly elevated in
    offspring from F2b litters for both control and test animals compared
    to the previous generation, but were within normal limits for the
    strain. The remaining test parameters (litter size, incidence of
    stillbirths, sex ratio at weaning and pre-weaning growth) were similar
    in treated and control animals. Histological sections taken from
    principal organs of F3b rats reportedly did not reveal evidence of
    anomalies. No detailed information from the histopathological
    examinations was provided (Truhaut et al., 1979).

    Short-term studies


         A 90-day feeding study was carried out in groups of 15 male and
    10 female rats at a dietary level of 50% modified or unmodified
    starch. The growth rate of males was significantly lower in the test
    group and the full and empty caecal weights of both sexes were
    significantly greater in rats fed the treated starch. All rats
    survived the test period and no differences were observed between the
    groups with respect to liver and kidney weights, haematology, blood

    chemistry, urinalysis, gross and histopathology. The modified starch
    used had been treated with 0.12% adipic acid and 10.5% acetic
    anhydride resulting in 3.1% of acetyl groups being present (Oser,

         Groups of 15 male and 15 female weanling albino rats, FDRL
    strain, were fed diets containing either 50% acetylated distarch
    adipate or, for control diet, 50% thin-boiling starch for 90 days.
    Treated males suffered a significantly reduced growth rate, which was
    paralleled by reductions in food intake and efficiency of utilization.
    Relative weights of caeca, empty or full, were higher in both sexes of
    the test group compared to control weights. No treatment-related
    changes were observed in relative weights of liver and kidneys, or in
    haematology or blood chemistry analyses. However, female rats on the
    test diet experienced alkaline urine relative to control at week 6 of
    the study. Histological sections of liver, spleen, stomach, small and
    large intestine, caecum, pancreas, kidneys, bladder, adrenals, gonads,
    thyroid, thymus, salivary gland, lymph nodes, heart, lungs, bone
    marrow and muscle were taken from 5 female and 5 male animals of
    control and test groups, and liver and kidney sections from all
    animals. No treatment-related adverse effects were observed, but 6
    control females and 3 test females had calcification at the
    corticomedullary junction (Oser, 1964).

    Long-term studies


         Rats, Sprague-Dawley derived, 4-5 weeks old, were distributed in
    groups of 30 males and 30 females and fed a cooked test diet
    containing 62% acetylated distarch adipate and a control diet of 62%
    unmodified starch for 2 years. Significant reductions in growth
    occurred in treated animals, particularly in females. These
    differences could not be attributed to reduced food intake, because
    consumption of modified starch and control diets was comparable. The
    2-year survival rate in treated animals (60%) was slightly higher than
    in control animals (52%). Haematology and serum clinical chemistry
    tests from treated and control animals were within normal range, with
    the exception of SGOT which was elevated in test animals. At autopsy,
    adipose deposits were much less extensive in treated rats than in
    controls, which could account for the reduced weights of the test
    animals. Skeletal growth, as demonstrated by femur measurements, was
    similar in test and control animals. Statistically significant
    treatment-related variations occurred in absolute organ weights
    relative to controls. However, relative to body weight, significant
    treatment-related differences in organ weights were rare. Because no
    treatment-related changes could be detected microscopically, the
    variations in organ weight were considered to be incidental.
    Histological examination of tissues from test and control animals
    showed no significant differences between the groups for either non-
    tumorous lesions or tumours. In the case of the kidney, hyperplasia of

    the kidney urothelium, sometimes accompanied by calcification, was
    observed in both control and test groups, but neither the incidence
    nor severity of these effects were considered by the authors to be
    treatment related. However, independent reviewers of the data
    concluded that in female rats, the incidence of epithelial hyperplasia
    was greater in the rats fed modified starch (Truhaut et al., 1979).


         A study of 14C-labelled starch adipate in the rat showed that
    the adipic acid moiety entered the metabolic pool more slowly but
    followed the normal pathways for free adipic acid. No retention of
    label was found in the carcass. The previous short-term feeding
    studies with rats at a high dietary level showed no significant
    pathological changes with the exception of measured caecal weight. The
    available evidence for modified starches as a group suggests that
    caecal enlargement without associated histopathological changes is
    without toxicological significance. The observed decrease in growth
    rate with a high dietary level was considered to be due to nutritional
    imbalance. However, recent studies with the rat and hamster have shown
    that high dietary levels (30%) of acetylated distarch adipate result
    in an increased incidence of renal lesions under various dietary
    conditions. The occurrence of renal mineralization has been the
    subject of special studies on the rate of mineral imbalance in the
    development of this lesion. These lesions were associated with the
    Ca/P ratio in the diet, as well as the presence of adequate magnesium.
    Changing the Ca/P ratio (particularly lowering the phosphate level),
    and raising the level of Mg in the diet resulted in a marked decrease
    or elimination of the lesion. A multigeneration reproduction study in
    the rat did not show any significant effect on reproductive
    performance. In the lifetime study in the rat, in which the diet
    contained 62% cooked acetylated distarch adipate, the only significant
    compound-related effects were a decrease in body weight and the
    occurrence of renal lesions (epithelial hyperplasia).


    Estimate of acceptable daily intake for man

    Not specified.*


    *    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/kg bw is not deemed


    Hodgkinson, A. et al. (1981) A comparison of the effects on mineral
         metabolism of diets containing waxy maize starch, either of two
         chemically-modified waxy maize starches, or lactose. Unpublished
         report from the General Infirmary, Leeds, and from the Medical
         School, University of Leeds

    Kruger, L. (1970) Unpublished reports Nos. 405 & 406, submitted by
         National Starch and Chemical Corporation

    Morgareidge, K. (1959a) Unpublished report No. 78522 of Food and Drug
         Research Laboratories, Inc., submitted by National Starch and
         Chemical Corporation

    Morgareidge, K. (1959b) Unpublished report No. 79408 of Food and Drug
         Research Laboratories, Inc., submitted by National Starch and
         Chemical Corporation

    Newberne, P. M. & Buttolph, M. L. (1977) A preliminary report of a
         thirty-day study in hamsters fed modified starch. Unpublished
         report from Massachusetts Institute of Technology, submitted to
         the World Health Organization by the US Food and Drug
         Administration, 1982

    Newberne, P. M. & Buttolph, M. L. (1979a) Final report. Review and
         conclusions of hamster studies with modified food starch. Study
         No. 78-4. Unpublished report from Massachusetts Institute of
         Technology, submitted to the World Health Organization by the US
         Food and Drug Administration, 1982

    Newberne, P. M. & Buttolph, M. L. (1979b, rev. 1980) Final report on
         study No. 79-2. Metabolism studies in rats fed modified food
         starch. Unpublished report from Massachusetts Institute of
         Technology, submitted to the World Health Organization by the US
         Food and Drug Administration, 1982

    Oser, M. (1961) Report No. 81776 of Food and Drug Research
         Laboratories, Inc., submitted by National Starch and Chemical

    Oser, B. L. (1964) Subacute (90-day) feeding studies with Amioca
         treated with adipic acid and acetic anhydride. Report No. 85555.
         Food & Drug Research Laboratories, Inc., Maspeth, NY, submitted
         to the World Health Organization by the US Food and Drug
         Administration, 1982

    Roe, F. J. C. (1979) Mineral deposition in the renal pelvis of rats:
         A brief review. Unpublished report submitted to the World Health

    Truhaut, R., Coquet, B., Fouillet, X., Galland, D., Guyot, D. & Long,
         D. (1979) Two-year oral toxicity and multigeneration studies in
         rats on two chemically modified maize starches, Fd. Cosmet.
         Toxicol., 17, 11-17

    See Also:
       Toxicological Abbreviations
       Acetylated distarch adipate  (FAO Nutrition Meetings Report Series 46a)
       Acetylated distarch adipate (WHO Food Additives Series 1)
       Acetylated distarch adipate (WHO Food Additives Series 5)