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    FAO Nutrition Meetings
    Report Series No. 40A,B,C
    WHO/Food Add./67.29




    TOXICOLOGICAL EVALUATION OF SOME
    ANTIMICROBIALS, ANTIOXIDANTS, EMULSIFIERS,
    STABILIZERS, FLOUR-TREATMENT AGENTS, ACIDS AND BASES





    The content of this document is the result of the deliberations of the
    Joint FAO/WHO Expert Committee on Food Additives which met at Rome,
    13-20 December, 19651 Geneva, 11-18 October, 19662




                   

    1 Ninth Report of the Joint FAO/WHO Expert Committee on Food
    Additives, FAO Nutrition Meetings Report Series, 1966 No. 40; 
    Wld Hlth Org. techn. Rep. Ser., 1966, 339

    2 Tenth Report of the Joint FAO/WHO Expert Committee on Food
    Additives, FAO Nutrition Meetings Report Series, 1967, in press; 


    Food and Agriculture Organization of the United Nations
    World Health Organization
    1967


    METHYLETHYLCELLULOSE

    Synonym                      MEC

    Chemical name                Methyl ethyl ethers of cellulose

    Molecular formula

           [C6H7O2(OH) x (OCH3)y(OC2H5)z]n

    Structural formula

    MOLECULAR STRUCTURE 16

    Molecular weight             Unsubstituted structural unit:  162.14

                                 Structural unit with a total degree of
                                 substitution of 0.77 : 181

                                 Structural unit with a total degree of
                                 substitution of 1.2 : 190

                                 Low polymers (n about 200) : 40 000

                                 High polymers (data to be supplied by
                                 the manufacturer)

    Definition                   Methylethylcellulose contains between
                                 3.5 and 6.5 per cent. of methoxyl groups
                                 and 14.5 and 19.0 per cent. ethoxyl
                                 groups. Alkoxyl content expressed as
                                 methoxyl is 13.2 to 19.6 per cent.

    Description                  Methylethylcellulose is hygroscopic,
                                 slightly yellowish, odourless and
                                 tasteless fibre or powder.

    Uses                         As thickening agent, stabilizer and
                                 foaming agent.

    Biological Data

    Biochemical aspects

         A variety of water soluble cellulose derivatives, collectively
    known as cellulose ethers, have been used for many years in food
    technology. Some members, i.e. methyl cellulose and sodium
    carboxymethylcellulose, have been evaluated previously (FAO/WHO,
    1964). Methylethylcellulose is similarly regarded as metabolically
    inert and is not absorbed from the gastrointestinal tract of mammals
    and man.

         After feeding a single dose of 0.6 g of methylethylcellulose in
    the diet of rats some 90 per cent. 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).

    Acute toxicity

         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).

    Long-term studies

         Mouse. Groups of 50 males and 50 female mice ware fed 0, 0.1
    and 1 per cent. of methylethylcellulose for 2 years. Body-weight was
    slightly reduced in both sexes at the 1 per cent. 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).

         Rat. Groups of 50 male and 50 female rats were fed 0, 0.1 and 1
    per cent. of methylethylcellulose for 2 years. Body-weight was reduced
    in males at the 1 per cent. 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).

    Comments

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

    Evaluation

    Level causing no toxicological effect

         Rat. 10 000 ppm in the diet, equivalent to 500 mg/kg
    body-weight/day

    Estimate of acceptable daily intake for man

                                     mg/kg body-weight

       Unconditional acceptance           0-301

       Conditional acceptance :      Higher levels may be used for
                                     dietetic or calorie control purposes


    REFERENCES

    FAO/WHO (1964) FAO Nutrition Meetings Report Series No. 35; 
    Wld Hlth Org. techn. Rep. Ser., 281

    Gage, J. C. (1962) Unpublished report to WHO

    Imperial Chemical Industries (1966) Unpublished report to WHO

                   

    1 As sum of total cellulose derivatives.

    


    See Also:
       Toxicological Abbreviations