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.


    HYDROXYPROPYL STARCH

    Modification is carried out by propylene oxide at levels up to 25 per
    cent. and the resultant starch is usually lightly oxidised, bleached
    or acid modified after etherification. Substitution may amount to a
    maximum of 4 ether linkages per 10 glucopyranose units if 25 per cent.
    propylene oxide is used and 4-6 ether linkages per 100 glucopyranose
    units if 5 per cent. propylene oxide is used.

    Biological Data

    Biochemical aspects

    In vitro digestibility by pancreatin was estimated by comparing the
    amount of reducing material liberated with that formed from native
    wheat starch. No significant difference could be detected between low
    (1 in 10) and high (4 in 10) substituted starches compared with
    unmodified starch (Kay & Calandra 1962). Caloric value could not be
    estimated because of diarrhoea.

    Acute toxicity

                                                                    

    Animal    Route          LD50           Reference
                        mg/kg body weight
                                                                    

    Rat       oral           >10 000        Hercules Powder Co.,
                                            1959a
                                                                    

    Application of powder or solutions produced mild irritation in
    rabbits' eyes (Pallotta, 1959). The Schwartz Prophetic Patch Test on
    210 human subjects using powdered high and low modified starch, as
    well as native starch as control, showed no difference after 72 hours
    initial exposure and no evidence of sensitization on 72 hour challenge
    after 2 weeks (Majors & Ruben Koenig, 1959). The Repeat Insult Patch
    Test in 23 human subjects showed no irritation after 9 twenty-four
    hour exposures and no evidence of sensitization on 24 hour challenge
    after 2 weeks (Ruben Koenig, 1959).

    Short-term studies

    Rat. Groups of 10 male and 10 female rats were fed for 90 days diets
    containing 0, 2 per cent., 5 per cent., 10 per cent. and 25 per cent.
    of highly modified starch (25% propylene oxide) and 25 per cent.
    unmodified wheat starch. No systemic toxicity was noted. There were no
    adverse effects regarding mortality, urinalysis or haematology at any
    level. There was slight reduction in growth rate at the highest
    dietary level with lower food utilization and without an equivalent
    increase in food consumption. Mild diarrhoea occurred at 25 per cent.

    dietary level. No adverse effects occurred at any other level. At
    autopsy there were no significant differences in the organ weight of
    liver, kidney, spleen, gonad, heart or brain. The observed increased
    ratios at 25 per cent. dietary level for liver/body weight and
    kidney/body weight were due to the relatively lower body weight. Gross
    and histological examination of all major tissues revealed no
    abnormalities due to the feeding of highly modified starch (Kay &
    Calandra, 1961). In another experiment groups of 10 male and 10 female
    rats were fed for 90 days on diets containing 0, 5 per cent., 15 per
    cent. and 45 per cent. of low modified starch (5 per cent, propylene
    oxide). Haematological findings at 12 weeks were comparable for all
    groups. Body weights did not differ significantly from controls but
    were consistently lower in male rats only. Feed efficiency was similar
    in all groups. Caecal enlargement was seen at the 15 per cent. and 45
    per cent. dietary levels. Diarrhoea occurred at the 45 per cent. level
    and very slightly at the 15 per cent. level. No histological
    abnormalities were detected in any major organs, which were due to the
    test substance. The enlarged caeca showed no evidence of inflammation
    or changes in the muscular coat (Feron at al., 1967).

    Long-term studies

    None available.
    

    See Also:
       Toxicological Abbreviations
       Hydroxypropyl starch (WHO Food Additives Series 1)
       Hydroxypropyl starch (WHO Food Additives Series 5)
       Hydroxypropyl starch (WHO Food Additives Series 17)
       HYDROXYPROPYL STARCH (JECFA Evaluation)