INTERNATIONAL PROGRAMME ON CHEMICAL SAFETY
WORLD HEALTH ORGANIZATION
SAFETY EVALUATION OF CERTAIN
FOOD ADDITIVES
WHO FOOD ADDITIVES SERIES: 42
Prepared by the Fifty-first meeting of the Joint FAO/WHO
Expert Committee on Food Additives (JECFA)
World Health Organization, Geneva, 1999
IPCS - International Programme on Chemical Safety
PROCESSED EUCHEUMA SEAWEED (addendum)
First draft prepared by
Dr J.B. Greig
Department of Health, Skipton House, London, United Kingdom
Explanation
Biological data
Toxicological studies
Short-term studies of toxicity
Genotoxicity
Comments
Evaluation
References
1. EXPLANATION
Processed Eucheuma seaweed was previously considered by the
Committee at its thirtieth, thirty-ninth, forty-first, and
forty-fourth meetings (Annex 1, references 73, 101, 107, and 116). At
the thirtieth and thirty-ninth meetings, the Committee was unable to
evaluate its use in food because no relevant toxicological data were
available. At its forty-first meeting, the Committee considered a
90-day feeding study in rats, for which complete details were not
available, and some studies of genotoxicity. The Committee allocated a
temporary ADI of 0-20 mg/kg bw to processed Eucheuma seaweed from
E. cottonii pending submission of the data on individual animals in
the 90-day study. At its forty-fourth meeting, the Committee reviewed
those data and the results of new assays for genotoxicity and
cytotoxicity. Because of the chemical relationship between processed
Eucheuma seaweed and traditionally refined carrageenan, the
Committee considered that toxicological data on the latter were
relevant to the safety assessment of the carrageenan polysaccharide
constituents of processed Eucheuma seaweed, but could not replace
adequate toxicological studies on processed Eucheuma seaweed itself.
Although the data for individual animals in the 90-day feeding study
in rats confirmed the accuracy of the summary data and the conclusions
derived from them, the Committee expressed reservations about the
design, conduct, and documentation of the study. Additionally, none of
the available studies of genotoxicity was considered to be adequate,
because of deficiencies in their conduct or reporting. The Committee
therefore extended the temporary ADI, pending submission of the
results of a new 90-day study of toxicity in rats and of an
appropriate battery of genotoxicity studies on processed seaweed from
E. cottonii, all meeting present-day standards.
In addition, in response to a request that the specifications
include E. spinosum as a source of processed Eucheuma seaweed, the
Committee determined at the forty- fourth meeting that the results of
a separate 90-day feeding study in rodents and of a separate battery
of genotoxicity assays were required for that inclusion, as
iota-carrageenan, the major component of E. spinosum, caused
ulcerative lesions in the caecum of guinea-pigs. The Committee also
requested the results of a separate battery of assays of genotoxicity.
Additionally, the Committee concluded that a complete review of all
data on carrageenan should be undertaken in 1998 (vide supra).
At the present meeting, the Committee reviewed the results of a
new 90-day study in rats.
2. BIOLOGICAL DATA
2.1 Toxicological studies
2.1.1 Short-term studies of toxicity
Processed Eucheuma seaweed derived from two sources,
E. cottonii or E. spinosum, was fed to groups of 20 male and 20
female Sprague-Dawley rats at concentrations of 0.5, 1.5, or 5% in the
diet for at least 90 days. Groups of 30 male and 30 female rats fed
basal diet for the same period were used as controls. Positive control
groups of 10 male and 10 female Sprague-Dawley rats were fed diets
containing 5% conventionally processed carrageenans derived from the
same seaweeds over the same period. Additional groups of 10 male and
10 female rats were fed the 5% processed Eucheuma seaweed and
conventionally processed carrageenan diets for 90 days and then basal
diet for 28 days. The study was carried out to present-day standards;
the only deviation was a slight inhomogeneity of mixing outside the
defined range. Ophthalmological examinations of controls and rats fed
5% test diets were carried out before the start of the study and again
one week before they were killed. All animals were observed daily, and
body weights and food intake were measured twice weekly. Urine samples
were collected on the day before necropsy. The animals were killed by
exsanguination, and haematological and clinical chemical parameters in
blood, plasma, and serum were measured. The weights of 10 major organs
or tissues from each animal were recorded, and a comprehensive set of
tissues were fixed. Tissues from controls, rats fed 5% processed
Eucheuma seaweed derived from E. cotonii or E. spinosum, and all
animals that died or were killed during the study were examined by
light microscopy. The lungs of all animals were examined.
No ophthalmological abnormalities were found, and the alterations
in general condition during the study, usually consisting of red
staining on the face, were considered by the authors not to be due to
treatment. Statistically significant reductions in body weight of
about 5% below control values at more than half of the measurement
times were seen in males fed the 5% Eucheuma seaweed from both
sources; these changes did not persist in the corresponding groups
that were allowed to recover. Males fed 5% conventionally processed
carrageenans derived from E. spinosum had statistically
significantly reduced body weights throughout the study, which were
10% lower than those of controls at the end of the study. These
changes persisted during the recovery phase. Of the females, only
those fed 5% conventionally processed carragee-nans derived from
E. spinosum had statistically significant reductions in body weight
at more than half of the measurement times during the treatment and
recovery phases. The food intakes of treated animals showed no
consistent changes that could be related to the body-weight changes.
No dose-related functional changes were recorded during week 12
in a subset of 10 animals from each group. Similarly, urinalysis
provided no evidence of any biologically significant effect.
Occasional statistically significant alterations in haematological
parameters were reported, but the decreases in erythrocyte, leukocyte,
and lymphocyte counts, haemoglobin concentration, and haematocrit were
related to dose only in females fed 1.5 or 5% processed Eucheuma
seaweed derived from E. cotonii. Similar changes were not observed
in rats allowed to recover. Serum analysis revealed no dose-related
response, except an increase of about 7% in the albumin:globulin ratio
in male rats fed 5% processed Eucheuma seaweed derived from
E. spinosum.
At necropsy, the weight of the full caecum relative to body
weight was statistically significantly higher in rats fed 5% processed
Eucheuma seaweed from either source. The weight of the empty caecum
was increased only in males. No significant change was seen in rats
allowed to recover.
Isolated histopathological findings in males fed 5% processed
Eucheuma from either source were of no obvious toxicological
significance. Significantly increased incidences of perivascular
cuffing, haemorrhage, interstitial pneumonitis, and foci of foamy
macrophages were seen in the lungs of some control and treated groups,
with no indication of a dose-response relationship. The lesions were
attributed by the study authors to mild infection. Hydrometria of the
cervix and uterus were seen commonly in females and were considered
not to be relevant. Observations of follicular hyperplasia of lymphoid
tissue were attributed to infection (Robbins, 1997a,b).
2.1.2 Genotoxicity
The results of assays for genotoxicity were reviewed at the
forty-fourth meeting of the Committee and were considered to be
inadequate (Sylianco et al., 1993).
Assays for reverse mutation in Salmonella typhimurium strains
TA98, TA100, TA102, TA1535, and TA1537 both with and without an
Aroclor 1254-induced rat liver microsome fraction (Ames test) were
conducted with processed Eucheuma seaweed derived from E. cotonii
or E. spinosum, each at 10 concentrations in the range of 0-10
mg/plate. The results were negative (Jackson, 1997).
3. COMMENTS
The Committee reviewed the results of a new 90-day study in rats
fed processed Eucheuma seaweed from two sources, E. cottonii and
E. spinosum, at concentrations of 0, 0.5, 1.5, or 5% in the diet, as
well as conventionally processed carrageenan from these two sources at
5% in the diet. At the highest concentrations in the diet, the intakes
of the seaweeds were equal to 4300 and 5000 mg/kg bw per day,
respectively, for male and female rats fed the material from
E. cottonii and to 4500 and 5100 mg/kg bw per day, respectively, for
male and female rats fed the material from E. spinosum. No adverse
effects were noted in the study. The changes observed during the
course of feeding the highest concentration of processed Eucheuma
seaweed from these two sources, most notably an increase in the
relative weights of the full and empty caecum, were considered to be
the consequence of accumulation of poorly absorbed material in the
caecum and to be of no toxicological significance. There was no
indication that the effects of the processed Eucheuma seaweeds
differ from those of conventionally prepared carrageenans from the
same seaweed species.
Processed Eucheuma seaweed derived from either E. cottonii or
E. spinosum was not mutagenic in well-conducted assays for reverse
mutation in Salmonella typhimurium strains. The Committee considered
that no further studies of genotoxicity were required.
4. EVALUATION
In view of the lack of toxicity of processed Eucheuma seaweeds
derived from E. cottonii or E. spinosum, the Committee determined
that both species could be included in the specifications for
processed Eucheuma seaweeds. Additionally, because of the
similarities between processed Eucheuma seaweeds and conventionally
processed carrageenans and in the effects they caused in the recent
90-day study of toxicity, the Committee included carrageenans and
processed Eucheuma seaweed in a temporary group ADI 'not specified'
to be reviewed in 2001 (see monograph on carageenans).
5. REFERENCES
Jackson, L.I. (1997) Salmonella mutation test (Ames test) with a
semi-refined carrageenan from two sources. Unpublished BIBRA Report
No. 3160/2/1/97 from BIBRA International, Carshalton, Surrey, United
Kingdom. Submitted to WHO by Dr H.J. Bixler, Seaweed Industry
Association of the Philippines, Searsport, Maine, United States.
Robbins, M. (1997a) Validation of the determination of carrageenan in
diet mixtures. Unpublished BIBRA Report No. 3160/3/1/97 from BIBRA
International, Carshalton, Surrey, United Kingdom. Submitted to WHO by
Dr H.J. Bixler, Seaweed Industry Association of the Philippines,
Searsport, Maine, United States.
Robbins, M.C. (1997b) A 90-day feeding study in the rat with
semi-refined carrageenan from two sources, including a recovery phase.
Unpublished report of Project No. 3160/1/2/97 from BIBRA
International, Carshalton, Surrey, United Kingdom. Submitted to WHO by
Dr H.J. Bixler, Seaweed Industry Association of the Philippines,
Searsport, Maine, United States.
Sylianco, C.Y.L., Balboa, J., Serrame, E., & Guantes, E. (1993)
Non-genotoxic and antigenotoxic activity of PNG carrageenan.
Philipp. J. Sci., 122, 139-153.
See Also:
Toxicological Abbreviations
Processed Eucheuma seaweed (WHO Food Additives Series 32)
PROCESSED EUCHEUMA SEAWEED (JECFA Evaluation)