PROCESSED EUCHEUMA SEAWEED

    First draft prepared by
    Ms E. Vavasour
    Toxicological Evaluation Division
    Bureau of Chemical Safety, Food Directorate
    Health and Welfare Canada
    Ottawa, Ontario, Canada

    1.  EXPLANATION

         Processed  Eucheuma seaweed (PES) was previously considered by
    the Committee at its thirtieth and thirty-ninth meetings (Annex 1,
    references 73 and 101) but it could not be evaluated for use in
    foods because no relevant toxicological data were available.  At its
    present meeting the Committee reviewed a 90-day feeding study in
    rats on a processed  Eucheuma seaweed from  E. cottonii and a
    series of genotoxicity studies on a processed  Eucheuma seaweed
    from  E. cottonii were available.  Complete details of the 90-day
    study were not provided.

    2.  BIOLOGICAL DATA

    2.1  Biochemical Aspects

         No information available.

    2.2  Toxicological Studies

    2.2.1  Acute toxicity studies

         No new information available

    2.2.2  Short-term toxicity studies

         Groups of 10 male and 10 female Sprague-Dawley rats, 6 weeks
    old, were fed diets which contained 0, 0.5, 1.5 or 5.0% PES, or 5.0%
    refined carrageenan derived from  Eucheuma cottoni for 3 months. 
    The rats were observed twice daily and the gross appearance of the
    stools was checked in the morning.  Individual body weights and food
    consumption were measured weekly throughout the study.  Standard
    haematological and clinical chemistry parameters were measured in
    blood samples taken from all animals at sacrifice.  Urinalysis was
    also conducted on fresh urine and 24-hour urine samples at week 13
    of the study.  Faecal samples were analyzed for gross appearance and
    occult blood.  Necropsy was performed on all animals at sacrifice,
    selected organs weighed (brain, pituitary gland, submandibular
    glands, thymus, lungs, thyroid, heart, liver, caecum, spleen,
    kidneys, adrenal glands, testes, epididymides, prostate, ovaries and
    uterus) and 40 tissues and organs preserved for histopathological
    examination.  No individual data were provided.

         No deaths were observed during the study.  The average daily
    intakes for each of the dose levels of PES were 382, 1140 and
    3887 mg/kg bw/day for males, and 410, 1292 and 4170 mg/kg bw/day for
    females.  A dose-related trend in the incidence of altered stool
    quality was noted, in particular soft, big-size and fragmented
    stool.  This effect was most apparent (earlier onset, higher
    frequency of occurrence and larger number of animals affected) in
    the groups receiving 5% PES or refined carrageenan, especially the
    latter.  Faecal occult blood was not noted in any of the groups.  In
    addition, a higher urine volume and lower urine specific gravity was
    observed in the 5% PES groups.  Toluidine blue staining of the
    liver, spleen, mesenteric lymph nodes and gastrointestinal tract did
    not reveal deposition of metachromatic material at microscopic
    examination.  It was concluded that absorption of carrageenan did
    not occur.  No other effects attributable to treatment were evident
    from the summary of the histopathological results (Philippine Bureau
    of Food and Drugs 1992).

    2.2.3  Long-term/carcinogenicity studies

         No new information available

    2.2.4  Reproduction studies

         No new information available

    2.2.5  Special studies on genotoxicity

         The results of genotoxicity assays on PES are summarized in
    Table 1.

    2.3  Observations in humans

         No information was available.


    
    Table 1. Results of genotoxicity assays on PES

                                                                                                        

    Test System      Test Object             Concentration of      Results     Reference
                                             Test Material

                                                                                                        

    Rec assay        B. subtilis             25-100 mg/ml          Negative    Sylianco  et al. 1992

    Ames test1,2     S. typhimurium TA100    25-100 mg/ml          Negative    Sylianco  et al. 1992

    Host-mediated    Swiss Webster mice/     625-2 500 mg/kg bw    Negative    Sylianco  et al. 1992
    assay            S. typhimurium

    Micronucleus     Swiss Webster mice      625-2 500 mg/kg bw    Negative    Sylianco  et al. 1992
    test
                                                                                                        

    1 Without S9 metabolic activation.
    2 Only one strain of  S. typhimurium was used for the Ames assay, though it is standard
      practice to use 4 strains.
    

    3.  COMMENTS

         Analytical data provided on the commercial product and on the
    material used in the toxicity studies were reported to conform to
    the specifications that were prepared at the present meeting.  The
    viscosity specification indicated that the carrageenan component was
    not degraded.  Analytical data showed that the relative molecular
    mass of processed  E. cottonii was well above that of degraded
    carrageenan and similar to that of traditionally refined
    carrageenan, and that the acid-insoluble component of PES was
    similar to cellulose.  The crude protein content of the commercial
    batches ranged from 0.1 to 1.5%, with a mean value of 1%.  The
    product did not contain heavy metals at levels of toxicological
    concern.

         In the 90-day feeding study in rats PES was administered at
    0.5%, 1.5%, and 5% in the diet, in addition a comparison group was
    fed traditionally-refined carrageenan at a level of 5%.  The most
    notable effect from this study was an alteration of stool
    characteristics in both the groups fed PES and those fed
    traditionally-refined carrageenan at the 5% level, which was more
    pronounced in the group receiving traditionally-refined carrageenan. 
    This effect is to be expected from this kind of poorly absorbed
    material and was not considered to be of toxicological significance. 
    No deposits of metachromatic material were observed in the livers of
    these rats, and no traces of blood were detected in the faeces as
    would have been expected if the PES had been degraded.  No effects
    of toxicological significance were observed.

         No genotoxic effects were observed in  in vitro bacterial
    assays or in an  in vivo mammalian assay.

    4.  EVALUATION

         The Committee allocated a temporary ADI of 0-20 mg/kg bw to
    processed  Eucheuma seaweed, based on the application of a 200-fold
    safety factor to the intake associated with the 5% dose level
    (equivalent to 3890 mg/kg bw/day) in the 90-day study in rats.  The
    ADI was made temporary, pending submission of the complete details
    from this study, including histopathological data for individual
    animals.  The Committee was informed that additional
    characterization data on processed  Eucheuma seaweed existed, and
    requested that that these data and the individual data from the
    90-day rat study should be submitted for review by 1995.

    5.  REFERENCES

    PHILIPPINE BUREAU OF FOOD AND DRUGS.  1992. Three months subchronic
    oral toxicity test of dietary Philippine Natural Grade carrageenan
    in rats.  Interim report.  BFAD protocol no. 91-5.  Unpublished
    report submitted to WHO by the Government of the Philippines.

    SYLIANCO, C.Y.L., BALBOA, J., SERRAME, E. AND GUANTES, E.  1992. 
    Mutagenicity, clastogenicity and antimutagenicity potential of
    carrageenan.  Unpublished report submitted to WHO by the Government
    of the Philippines.

    See Also:
       Toxicological Abbreviations
       Processed Eucheuma seaweed (WHO Food Additives Series 42)
       PROCESSED EUCHEUMA SEAWEED (JECFA Evaluation)