934. Carrageenan (WHO Food Additives Series 42)

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

CARRAGEENAN (addendum)

First draft prepared by
Dr J.B. Greig
Department of Health, Skipton House, London, United Kingdom

Explanation
Biological data
Biochemical aspects
Absorption, distribution, and excretion
Biotransformation
Degradation in the gastrointestinal tract
Fermentation in the large intestine
Toxicological studies
Acute toxicity
Short-term studies of toxicity
Long-term studies of toxicity and carcinogenicity
Genotoxicity
Reproductive and developmental toxicity
Special studies
Proliferation and tumour promotion
Gastrointestinal tract
Immune system
Nutrient absorption
Irritation and sensitization
Observations in humans
Comments
Evaluation
References

1. EXPLANATION

Carrageenan is a sulfated polygalactan with an average relative
molecular mass well above 100 kDa. It is derived from a number of
seaweeds of the class Rhodophyceae. It has no nutritive value and is
used in food preparation for its gelling, thickening, and emulsifying
properties. Three main types of carrageenan are used commercially,
which are known in the food industry as iota-, kappa-, and
lambda-carrageenan. These names do not reflect definitive chemical
structures but only general differences in the composition and degree
of sulfation at specific locations in the polymer.

Carrageenan was reviewed previously by the Committee at the
thirteenth, seventeenth, and twenty-eighth meetings (Annex 1,
references 19, 32, and 66). At the twenty-eighth meeting, an ADI 'not
specified' was allocated on the basis of the results of a number of
toxicological studies on carrageenans obtained from various seaweed
sources. The studies included a three-generation study of reproductive
toxicity, short-term and long-term studies of toxicity in rats at
dietary concentrations up to 5%, and short- and long-term studies of
toxicity in hamsters, guinea-pigs, and monkeys. In general, the only
effect observed was soft stools or diarrhoea at high doses, except in

two studies in which material identified as being iota-carrageenan
was administered at 1% in the drinking-water or 5% in the diet and
produced ulceration in the gastrointestinal tract of guinea-pigs.
Although degraded carrageenans can produce this effect, they are not
used as food additives. At the twenty-eighth meeting, the Committee
specifically pointed out that degraded carrageenans and 'semi-refined
carrageenan' (or 'processed Eucheuma seaweed') were not included in
the specifications of the food-grade material. At its forty-fourth
meeting, in reviewing the data on processed Eucheuma seaweed
obtained from E. cottonii, the Committee requested that all data on
carrageenan be reviewed in 1998, with particular attention to the
identity of the source materials and the specifications of the
products tested (Annex 1, reference 116).

At the present meeting, the Committee considered studies
published since the review at the twenty-eighth meeting and, for
earlier studies, indicated the identity of the seaweed source and the
type of carrageenan, when these could be identified.

2. BIOLOGICAL DATA

2.1 Biochemical aspects

2.1.1 Absorption, distribution, and excretion

Rats

As rats excrete dietary concentrations of 2-20% carrageenan
(kappa/lambda from Chondrus crispus) quantitatively in the faeces,
it has no direct nutritive value (Hawkins & Yaphe, 1965). In groups of
five rats that received 0.5% native carrageenan (iota-carrageenan
from E. spinosum) or 5% degraded carrageenan for 10 days, faecal
excretion and weight gain were similar with the two polymers (Dewar &
Maddy, 1970), and native carrageenan (kappa/lambda from
C. crispus), untreated or heat-sterilized in milk, was
quantitatively excreted in the faeces of rats (Tomarelli et al.,
1974). No carrageenan was found in the livers of rats fed 25% native
carrageenan (kappa/lambda from C. crispus or Iridaea crispata)
in the diet for one month (Chen et al., 1981), of rats fed diets
containing 1 or 5% carrageenan (kappa from Gigartina spp., iota
from E. spinosum) (Coulston et al., 1975), or of rats fed diets
containing 5% Chondrus crispus carrageenan (kappa/lambda) for 13
weeks (Pittman et al., 1976). No carrageenan was detected in the small
or large intestine of rats fed 5% native carrageenan (iota from
E. spinosum) (Grasso et al., 1973). Nicklin & Miller (1984) reported
that orally administered carrageenan (type unidentified) of high
relative molecular mass could penetrate the mucosal barrier of adult
animals via transport by macrophages in Peyer's patches. Carrageenan
did not affect the number or distribution of these cells; however,
when antigen was administered systematically to carrageenan-fed rats,
the antigen-specific antibody response was suppressed. This result

suggested that carrageenan interferes with antigen processing by
macrophages and thus mollifies normal immune function.

Analysis of liver samples from rats fed 25% native carrageenan
(kappa/lambda from C. crispus or C. iridaea) in the diet for one
month showed that only the second was stored in the liver in two
animals, as determined by the presence of gamma metachromatic
reaction sites in the Kupffer cells (Chen et al., 1981).

The results of an additional early study suggested that the
kappa/lambda form of carrageenan, prepared by a non-standard
procedure from either C. crispus or Gigartina stellata, is not
significantly absorbed from the intestine of Wistar rats (Carey,
1958).

Two new studies have been reported since the last review (Arakawa
et al., 1988; Nicklin et al., 1988); however, in neither report is the
identity given of the species from which the carrageenan originated,
and in the latter study the form of carrageenan that was used is
unclear (International Food Additives Council, 1997). In the first
study, rats quantitatively excreted the carrageenan (kappa form) in
the faeces, and it had the same gel filtration distribution pattern as
that of the material administered. In the latter study, in male PVG
strain rats given radiolabelled carrageenan (iota-form), there
appeared to have been some uptake into the intestinal wall, Peyer's
patches, mesenteric and caecal lymph nodes, and serum; however, the
method used to radiolabel the carrageenan with tritium is questionable
(International Food Additives Council, 1997).

Guinea-pigs

Feeding of guinea-pigs with native carrageenan (iota from
E. spinosum) at 5% in the diet for 21-45 days resulted in the
accumulation of 36-400 pg/g of caecal or colonic tissue. The
carrageenan was contained in macrophages (Grasso et al., 1973).

Food-grade carrageenan (kappa from C. crispus, lambda from
C. crispus, iota from E. spinosum) administered to guinea-pigs as
a 1% solution in drinking-water for two weeks was not retained in the
caecum (Engster & Abraham, 1976).

Rabbits

It was reported in an abstract that carrageenan (type and species
of origin unidentified) was present in the liver, stomach, and small
intestine of newborn rabbits given 40 mg native carrageenan orally.
Carrageenan was not detected in the cardiac or portal blood 4 h after
treatment (Udall et al., 1981).

Monkeys

Rhesus monkeys given 1% native carrageenan (kappa/lambda from
C. crispus) in drinking-water for 7-11 weeks, with a subsequent
11-week recovery period, showed no evidence of carrageenan storage
(Abraham et al., 1972). In another study on rhesus monkeys, no tissue
storage of carrageenan (kappa/lambda from C. crispus) was found
when the monkeys were given 1% native carrageenan in the
drinking-water for 10 weeks (Mankes & Abraham, 1975). Monkeys
receiving daily doses of 500 mg/kg bw native carrageenan
(kappa/lambda from C. crispus) for 15 months excreted 12 µg/ml
urine. The concentration was reported to be at the limit of detection
of the method (Pittman et al., 1976). Monkeys receiving 50, 200, or
500 mg/kg bw per day native carrageenan (kappa/lambda from
C. crispus) orally for 7.5 years showed no evidence of storage in
the liver or other organs (Abraham et al., 1983).

2.1.2 Biotransformation

2.1.2.1 Degradation in the gastrointestinal tract

Although native carrageenan may be degraded in the gut, this
possibility is probably of limited toxicological significance, since,
if native carrageenan were sufficiently degraded to cause ulceration
or tumour growth, this would have been detected in feeding studies.
Since food-grade carrageenan does not have the same effects as
degraded carrageenan, it is either not degraded, not degraded to the
same molecular mass, or not degraded in the same way. It would appear
that carrageenan is only partially degraded, that most of the
degradation takes place in the stomach, and that this limited
degradation has no effect on the wall of the stomach, where the pH is
very low and acid hydrolysis undoubtedly occurs. When a kappa/lambda
mixture (from an unidentified species) was incubated in simulated
gastric juice at pH 1.2 and 37°C, breakdown of glycosidic linkages was
less than 0.1% after 3 h (Stancioff & Renn, 1975).

Breakdown of kappa-carrageenan (from an unidentified species)
was about 15 times greater than that of the iota form; however, the
conditions of hydrolysis (6 h at pH 1.0) were more drastic than those
that occur normally in the stomach, and the pH would be expected to be
considerably higher in a full stomach (Ekstrom & Kuivinen, 1983).

There is no evidence that carrageenan is degraded on the lower
gut. Incubation of a carrageenan solution with the caecal contents of
rats for several hours at 37°C did not alter its viscosity, suggesting
that the microbial flora of the rat gut cannot break down carrageenan
(Grasso et al., 1973).

Degradation of carrageenan by a large number of intestinal
bacteria in vitro has been reported, but the carrageenan used (of an
unidentified form from an unidentified species) contained 20% reducing
sugar, which would give a positive result in the test method. Among

the bacteria claimed to break down carrageenan were Klebsiella
pneumonia and Escherichia coli; however, both these species can be
grown on carrageenan gel (Epifanio et al., 1981). If these bacteria
had been able to degrade carrageenan, they would have liquefied the
gel medium on which they were grown (Ochuba & von Riesen, 1980).

Breakdown of food-grade carrageenan (kappa-, lambda-, and
kappa/lambda-carrageenan from C. crispus and of iota-carrageenan
from E. spinosum) isolated from faeces of guinea-pigs, rats, and
monkeys has been reported, but the site of breakdown was not reported.
No intestinal lesions were associated with the breakdown. The
molecular mass attained (40-50 kDa) was not as low as that of degraded
carrageenan (10-20 kDa) (Pittman et al., 1976).

One new study has been reported. The degradation of food-grade
kappa- and iota-carrageenan was studied under physiologically
realistic conditions in an artificial stomach. kappa-Carrageenan was
not hydrolysed at pH 8 or under the severe conditions of pH 1.2 for 6
h, and the relative molecular mass remained at > 200 kDa, no more
than 20% having a molecular mass of < 100 kDa. It was confirmed that
iota-carrageenan is more resistant to degradation than the kappa
form (Capron et al., 1996). The originating species were E. cottonii
for kappa-carrageenan and E. spinosum for iota-carrageenan;
however, this is not stated in the paper (International Food Additives
Council, 1997). The greater stability of iota-carrageenan to
degradation may reflect the conformation of the macromolecule in the
medium used (Ekström et al. 1983; Ekström, 1985; International Food
Additives Council, 1997).

2.1.2.2 Fermentation in the large intestine

No evidence of fermentation was seen after incubation of rat
caecal contents with iota-carrageenan from E. spinosum (Grasso et
al., 1973).

A study in female Wistar rats fed carrageenan (type and origin
unidentified) as an inert polysaccharide does not provide quantitative
measures of its degradability (Elsenhans et al., 1981).

Feeding of three-week-old male Sprague-Dawley rats for four weeks
with a diet containing 5% iota-carrageenan originating from
E. spinosum (International Food Additives Council, 1997) resulted in
a significant reduction in the bacterial population of the caecum, as
assessed by bacterial counts and the activity of various caecal
microbial enzymes; however, the weights of the caecal contents and the
caecal wall were increased (Mallett et al., 1984). Similar effects
were seen in mice and hamsters fed dietary iota-carrageenan (origin
unidentified) (Mallett et al., 1985); however, in neither study was
the degradation of carrageenan measured.

On the basis of the rates of evolution of methane, hydrogen
sulfide, and carbon dioxide from a slurry of mixed human faecal
bacteria, carrageenan (origin and type unidentified) was ranked second
to fourth in ease of degradation among 15 laxative fibres (Gibson et
al., 1990).

In a study of 154 bacterial species commonly found in the human
colon, carrageenan (origin and type unidentified) was one of the
polysaccharides most resistant to fermentation (Salyers et al., 1977).

2.2 Toxicological studies

2.2.1 Acute toxicity

Not all the studies of acute toxicity summarized in earlier
reviews of the Committee are included here, as sufficient details on
dose, type of carrageenan, or seaweed source were not given.
Informative studies are summarized in Table 1. Additional unpublished
studies in which unspecified types of carrageenan derived from an
unknown seaweed species were fed to dogs and rhesus monkeys at doses
up to 3000 mg/kg bw per day for seven days were reviewed at the
twenty-eighth meeting. Gross and histopathological changes were seen
at the end of treatment, predominantly in the gastrointestinal tract
(Annex 1, reference 66).

2.2.2 Short-term studies of toxicity

Rats

Groups of two male albino rats fed 0, 5, 10, or 20%
kappa/lambda-carrageenan from C. crispus for 10 weeks grew well,
except that 50% of those at the highest dose died (Nilson & Schaller,
1941).

In groups of male and female rats fed 2, 5, 10, 15, or 20%
kappa/lambda-carrageenan from C. crispus for periods of 23-143
days, the only adverse effect was reduced growth rates at dietary
concentrations of 10-20% (Hawkins & Yaphe, 1965).

No effects on appearance or behaviour were observed in male and
female Osborne-Mendel or Sprague-Dawley rats fed 5% kappa/lambda-
carrageenan from C. crispus for nine months. Bile-duct proliferation
was seen in one male Osborne-Mendel rat, and reduction of the liver
lobes and crenation of the margins in three females (Coulston et al.,
1976).

Groups of 12 male and 25 female Sprague-Dawley rats were fed a
diet containing 4% processed, heat-sterilized kappa/lambda-
carrageenan for six months. There was no effect on growth rate, and
the caecum and colon were normal on gross and microscopic examination
(Tomarelli et al., 1974).

Table 1. Acute toxicity of carrageenan

Carrageenan Species Sex Route LD₅₀ Reference
(mg/kg bw)

Studies summarized at the seventeenth meeting of the Committee

kappa/lambda Mouse M/F Oral 9150 ± Food & Drug Research
from C. crispus 440 Laboratories (1971)
NR Rat NR Intravenous > 10 Morard et al. (1964)
kappa/lambda Rat M/F Oral 5400 ± Food & Drug Research
from C. crispus 260 Laboratories (1971)
kappa/lambda Hamster M/F Oral 6750 ± Food & Drug Research
from C. crispus 570 Laboratories (1971)
kappa/lambda Guinea-pig NR Intravenous > 10 Morard et al. (1964)
from C. crispus
lambda from Guinea-pig NR Intravenous < 1 Anderson & Soman
C. crispus or (1966)
G. pistallata
kappa/lambda Rabbit M/F Oral 2640 ± Food & Drug Research
from C. crispus 360 Laboratories (1971)
kappa or lambda Rabbit NR Intravenous 1-20 Duncan (1965)
from C. crispus (LD₁₀₀)
NR Rabbit NR Intravenous < 50 Morard et al. (1964)

New studies
iota^a Rat NR Oral > 5000 Weiner (1991)
iota^a Rat NR Inhalation > 930 ± Weiner (1991)
(4-h 74 mg/m³
LC₅₀)
iota^a Rabbit NR Dermal > 2000 Weiner (1991)

NR, not reported; M/F, male and female
^a Stated to be kappa/lambda- carrageenan from Gigartina radula (International Food Additives
Council, 1997)

Addition of 5% iota-carrageenan from E. spinosum to the diet
of 10 male Wistar rats for 56 days resulted in slight diarrhoea
(Grasso et al., 1973).

Guinea-pigs

Groups of 10 adult male albino guinea-pigs were given either
water or a 1% solution of undegraded iota-carrageenan from
E. spinosum. After 20 days, two of four treated animals had
ulcerative lesions in the caecum, and the remaining six animals had
lesions at 30 days. The control group remained healthy (Watt & Marcus,
1969). It was reported in a brief letter that 5% iota-carrageenan in
the diet had the same effect (Sharratt et al., 1970).

Administration of 5% iota-carrageenan from E. spinosum to
seven female guinea-pigs in the diet for 56 days resulted in the
formation of multiple pin-point caecal and colonic ulcerations (Grasso
et al., 1973).

Pigs

Groups of three male and three female Danish Landrace pigs were
fed 0, 50, 200, or 500 mg/kg bw per day of kappa-carrageenan from
C. crispus for 83 days. No compound-related deaths were seen, and
the behaviour, appearance, and feed intake of the animals remained
normal. There were no significant changes in haematological, clinical
chemical, or urinary parameters. Areas of infolding of the intact
epithelium with infiltration of the lamina propria of the colonic
mucosa by macrophages and lymphocytes were seen in one pig at 200
mg/kg bw per day and two at 500 mg/kg bw per day, but these effects
were considered to be reversible (Poulsen, 1973).

Monkeys

Male and female rhesus monkeys were given drinking-water
containing 1% kappa-carrageenan from C. crispus for 7-11 weeks.
The animals remained in good health, and there was no evidence of any
adverse effect. One female killed at seven weeks had a grossly normal
gastrointestinal tract, but some capillary hyperaemia and mucosal
oedema were observed microscopically. A male killed at 11 weeks had no
microscopic abnormalities. Two males and two females were allowed an
11-week recovery period and were then given carrageenan at escalating
oral doses of 50-1250 mg/kg bw per day for up to 12 weeks. No gross
adverse effects were observed, and the microscopic changes were not
attributed to carrageenan (Benitz et al., 1973).

Male and female infant baboons were reared from birth to 112 days
of age on infant formula containing 0, 1, or 5% kappa/lambda-
carrageenan derived from C. crispus. No effect was seen on organ or
body weights, characteristics of the urine and faeces, gross findings,
haematological or clinical chemical variables, or the gross or
microscopic appearance of the gastrointestinal tract (McGill et al.,
1977).

Groups of 10 male and 10 female Sprague-Dawley rats were fed 0 or
5% conventionally processed iota-carrageenan from E. spinosum and
kappa-carrageenan from E. cottonii in the diet for periods of over
90 days. An additional 10 rats of each sex were assigned to a 28-day
reversibility phase. The changes observed during the course of the
study were attributed by the authors to intake of a diet with a lower
nutritional value than the basal diet. The partial reversal of the
caecal weight changes during the 28-day reversibility phase and the
absence of histopathological changes would support this conclusion
(Robbins, 1997)

2.2.3 Long-term studies of toxicity and carcinogenicity

Mice

Lifetime administration of kappa/lambda-carrageenan from
C. crispus or G. mamillosa at concentrations of 0, 0.1, 5, 15, or
25% in the diet to groups of five male and five female mice of two
unidentified strains had no adverse effect (Nilson & Wagner, 1959).

Rats

Lifetime administration of kappa/lambda-carrageenan from
C. crispus or G. mamillosa at concentrations of 0, 0.1, 5, 15, or
25% in the diet to groups of five male and five female rats of two
unidentified strains resulted in evidence of hepatic cirrhosis, only
at the 25% concentration, with no effect on mortality (Nilson &
Wagner, 1959).

Groups of 30 male and 30 female MRC rats were fed 0.5, 2.5, or 5%
kappa-carrageenan from C. crispus in the diet for life; 100 males
and 100 females constituted the control group. Animals occasionally
developed soft stool consistency, particularly near the start of the
experiment. There was a statistically nonsignificant trend towards an
increased incidence of benign mammary tumours and testicular neoplasms
in the group fed 2.5% (Rustia et al., 1980).

Groups of 15 male and female Sprague-Dawley rats were given
extracts of kappa-carrageenan from Hypnea musciformis or
Irideae crispata at a concentration of 1 or 5% in the diet for one
year. Weight loss (p = 0.05) was observed in all treated rats as
compared with the control group, which received alphacel. The livers
of rats at 1% were normal on gross and microscopic examination. Gross
and microscopic examinations of the livers of rats given 5%
kappa-carrageenan from H. musciformis were normal, except for
nodules in two of 12 livers. Gross observation of the livers of rats
receiving 5% kappa-carrageenan from I. crispata showed decreased
size, rough surface, and vascularization in 10/13 rats, which was
probably related to treatment. Microscopically, these livers were
normal, except for focal necrosis in 1 of 10 livers. There was no
evidence of storage of carrageenan-like material (metachromatic) in
the liver cells of any of the treated rats, and no fibrillar material
was observed by electron microscopy. No changes were observed in the

stools of rats receiving 1% of either carrageenan, but female rats
given 5% kappa-carrageenan from I. crispata and males given either
carrageenan at the 5% concentration had loose stools. Blood was found
sporadically in the stools, but the frequency was not significant
(Coulston et al., 1975).

Monkeys

Nineteen male and 21 female rhesus monkeys were fed 0, 50, 200,
or 500 mg/kg bw kappa/lambda-carrageenan by gavage daily on six days
a week for five years and carrageenan incorporated into the diet for a
further 2.5 years. Loose stools, chronic intestinal disorders, poor
appetite, and emaciation were seen in an apparently random
distribution. Stool consistency was decreased in a dose-related trend
over the entire 7.5 years of the study, and findings of faecal occult
blood were increased in a similar fashion. Mean survival time was
similar in all groups, and no gross or microscopic changes were
detected in the tissues examined. Sporadic differences in body weight
from controls were seen randomly; females had significant body-weight
depression in the last 2.5 years of the study, which did not appear to
be dose-related. No consistent, statistically significant changes
occurred in haematological or clinical chemical values, absolute organ
weights, or organ-to-body weight ratios after 7.5 years of feeding
carrageenan. Cytochemical and ultrastructural observations revealed no
storage of carrageenan-like material in livers obtained at biopsy or
in other organs obtained at necropsy from monkeys given carrageenan,
and no dose-related gross or microscopic changes in other tissues
(Abraham et al., 1983).

No new information was available.

2.2.4 Genotoxicity

Assays for reverse mutation with kappa/lambda-carrageenan from
C. crispus in Salmonella typhimurium strains TA1535, TA1537, and
TA1538 and Saccharomyces cerevisiae strain D4 gave negative results
(Brusick, 1975).

The results of tests with kappa/lambda-carrageenan from
C. crispus for cytogenetic changes in a host-mediated assay (Litton
Bionetics, 1972) and for dominant lethal mutations in rats (Stanford
Research Institute, 1972) were stated to be negative, but neither
study would meet currently required standards. The reporting of an
additional early study of kappa/lambda-carrageenan from
C. crispusis inadequate (Mori et al., 1984), and some of the results
of the most recent study (on what can be deduced to be a processed
Eucheuma seaweed and its normally processed counterpart) are not
consistent with current experience (Sylianco et al., 1993).

2.2.5 Reproductive and developmental toxicity

Mice

Groups of 22-27 pregnant CD-1 mice were given either the sodium
(Food & Drug Research Labs., Inc., 1972a) or the calcium (Food & Drug
Research Labs., Inc., 1972b) salt of kappa/lambda-carrageenan from
C. crispus orally at doses of 0, 10, 45, 470, or 900 mg/kg bw per
day on days 6-15 of gestation. The number of fetal resorptions and/or
fetal deaths appeared to be increased, and there were dose-dependent
decreases in the number of live pups and in pup weight; skeletal
maturation was retarded (Food & Drug Research Labs., Inc., 1972a).

Rats

Groups of 21-27 pregnant rats were given either the sodium (Food
& Drug Research Labs., Inc., 1972a) or the calcium (Food & Drug
Research Labs., Inc., 1972b) salt of kappa/lambda-carrageenan from
C. crispus at 0, 40, 100, 240, or 600 mg/ kg bw per day on days 6-15
of gestation. There was an apparent increase in the number of fetal
resorptions, with no decrease in the number of live pups. At the
highest dose, pup weight was decreased. A dose-dependent increase in
the incidence of missing skeletal sternebrae was seen, with no other
compound-related abnormalities (Food & Drug Research Labs., Inc.,
1972a).

Four groups of 21-24 pregnant rats were fed 1 or 5% sodium or
calcium kappa/lambda-carrageenan from C. crispus on days 6-16 of
gestation. Concurrent groups also received the basal (control) diet,
and one group each received aspirin by stomach tube. All animals were
killed on day 20, the uterine contents were examined, and the numbers
of implants, resorptions, and live and dead fetuses and the average
weight of the live pups in each litter were recorded. All fetuses were
examined grossly for external abnormalities. There was no detectable
effect on maternal or fetal survival, the rate of nidation, or the
degree of maturation of fetuses, and neither material was teratogenic
(Food & Drug Research Labs., Inc., 1973).

In a three-generation study, groups of 40 male and 40 female
Osborne-Mendel rats were fed diets containing the calcium salt of
kappa/lambda-carrageenan at a concentration of 0.5, 1, 2.5, or 5%.
After weaning, all animals were fed carrageenan in their diets for
12 weeks before mating. There was no dose-related effect on maternal
weight gain. Carrageenan caused a significant, dose-related decrease
in the weights of offspring at weaning but had no effect on fertility,
average litter size, average number of liveborn animals, or the
viability or survival of offspring. Diarrhoea was marked in animals
fed the two highest doses. The average numbers of corpora lutea,
implantations, and early or late deaths and the average percent
resorptions per litter showed no dose-related change. Developmental
effects were studied in the F_2c and F_3c litters. No specific
external, skeletal, or soft-tissue anomaly could be correlated with
dosage (Collins et al., 1977a,b).

Sprague-Dawley rats were given a diet containing 0.45, 0.9, or
1.8% of the calcium salt of carrageenan for 14 days before mating, for
14 days during breeding, throughout gestation (22 days), lactation
(21 days) and post-weaning (69 days, i.e. from weaning at 21 days of
age until termination of the experiment at 90 days of age).
Inconsistent effects were seen on reproduction and on the physical and
behavioural development of the offspring, with no relationship to dose
(Vorhees et al., 1979).

Hamsters

Groups of 23-30 pregnant hamsters were given either the sodium
(Food & Drug Research Labs., Inc., 1972a) or the calcium (Food & Drug
Research Labs., Inc., 1972b) salt of kappa/lambda-carrageenan from
C. crispus at 0, 40, 100, 240, or 600 mg/ kg bw per day on days 6-10
of gestation. There was no significant effect on nidation or on
maternal or fetal survival but some evidence for a dose-dependent
delay in skeletal maturation (Food & Drug Research Labs., Inc.,
1972a).

Four groups of 21-26 pregnant hamsters were fed diets containing
1 or 5% sodium or calcium kappa/lambda-carrageenan from
C. crispuson days 6-11 of gestation. Concurrent groups also received
the basal diet, and one group of 25 animals received aspirin by
stomach tube. All animals were killed on day 14, the uterine contents
were examined, and the numbers of implants, resorptions, and live and
dead fetuses and the average weight of the live pups in each litter
were recorded. All fetuses were examined grossly for external
abnormalities. There was no detectable effect on either maternal or
fetal survival or on the degree of maturation of fetuses. The
pregnancy rate of females fed 5% of the calcium salt was marginally
but significantly reduced, but neither material was teratogenic (Food
& Drug Research Labs., Inc., 1973).

Randomly selected pregnant Syrian hamsters were intubated with
the sodium or calcium salt of native carrageenan or with degraded
carrageenan in distilled water at doses of 0, 10, 40, 100, or 200
mg/kg bw on days 6-10 of gestation. At least 21 pregnant females were
examined at each dose of native carrageenan, but only eight were
tested at each dose of degraded carrageenan as only a limited supply
of this compound was available. The highest concentration tested was
200 mg/kg bw per day because the gelling capacity of the compounds
precluded higher concentrations. The animals were killed on day 14. No
dose-related teratogenic or fetotoxic effects were seen (Collins et
al., 1979).

Rabbits

Groups of 12-13 pregnant rabbits were given either the sodium
(Food & Drug Research Labs., Inc., 1972a) or the calcium (Food & Drug
Research Labs., Inc., 1972b) salt of kappa/lambda-carrageenan from
C. crispus at 0, 40, 100, 240, or 600 mg/ kg bw per day on days 6-18
of gestation. There was no clearly discernible effect on nidation or

on maternal or fetal survival. The numbers of abnormalities of
skeletal or soft tissue development did not differ from those in
controls (Food & Drug Research Labs., Inc., 1972a).

Chick embryos

Before incubation, the yolk sacs of 240 chick eggs were injected
with 0.1 mg of a sterile suspension of 0.1% lambda-carrageenan in
0.9% sodium chloride, while 240 control eggs were injected with 0.1 ml
saline solution, and 240 eggs received no treatment. After mating, the
following parameters were determined: mortality rate of embryos in
which development was arrested, retardation of development based on
body weight and length of the third toe and beak, and incidence of
gross malformations. The mortality rate among embryos injected with
carrageenan was significantly higher than those in the two control
groups. Anomalies in the treated embryos were mainly located in the
cephalic end, e.g. exencephaly, abnormal beak, and anophthalmia. All
of the abnormal treated chicks showed two or more anomalies. The
growth of newborn chicks from treated eggs was significantly retarded
up to four days of age. Under these experimental conditions,
lambda-carrageenan had teratogenic and lethal effects on chick
embryos (Rovasio & Monis, 1980).

At the twenty-eighth meeting of the Committee, studies of the
effects of furcellaran, a product of Furcellaria species of seaweed,
on chick embryos were considered. The reports cited were unpublished
and are not currently available. Furcellaran was administered in water
into the air cell or yolk sac of eggs before incubation (0 h) and
after 96 h of incubation. Administration of furcelleran before
incubation resulted in a curve with a slope that was not significantly
different from zero, while administration at 96 h resulted in a line
with a negative slope. No LD₅₀ could be estimated from the regression
lines.

Furcellaran was injected in water into the albumen or the yolk
before incubation (0 h) and after 96 h of incubation. Albumen was
chosen instead of the usual air cell because the furcellaran solution
formed globular coagulates as soon as it was injected into the air
cell and could not be absorbed through the embryonic membrane.
Furcelleran was embryotoxic under all conditions of the test. Probit
analysis resulted in LD₅₀ values of 1.6 mg/egg before incubation, 1.4
mg/egg at 96 h when given via the albumen, and 1.1 mg/egg before
incubation; the slope of the curve was not significantly different
from zero when furcellaran was injected into the yolk. When
carrageenan was injected at a dose of 1 or 5 mg/egg into either the
albumen or the yolk before incubation, anomalies of the eye and
maxilla were seen which were nor observed in the solvent-treated
embryos (Hwang & Connors, 1974).

2.2.6 Special studies

2.2.6.1 Proliferation and tumour promotion

kappa/lambda-Carrageenan from Gigartina spp. administered at
5% in the diet to male Fischer 344 rats for four weeks increased the
activity of colonic thymidine kinase, a marker of proliferation. Diets
containing 5% guar gum or 10% wheat bran had no such effect (Calvert &
Reicks, 1988). A dose-response relationship was seen for thymidine
kinase activity, only the highest dose causing a statistically
significant increase, when the concentration of carrageenan was 0,
0.65, 1.3, or 2.6%, meant to simulate 25, 50, and 100 times the
maximal human intake. No histological abnormalities were seen at any
dose (Calvert & Satchithanandam, 1992).

A similar increase in colonic mucosal thymidine kinase activity
was observed in groups of four Fischer 344 rats fed 5%
iota-carrageenan for 28 or 91 days. When the animals were returned
to basal diet after 28 or 64 days, the number of proliferating cells
(identified by proliferating cell nuclear antigen
immunohistochemistry) returned to normal and they were found in
colonic crypts. No significant increase was seen in rats fed 0.5 or
1.5% iota-carrageenan (Wilcox et al., 1992).

No aberrant crypt foci were found in nine female Fischer 344 rats
fed a 10% gel of kappa-carrageenan instead of drinking-water for
eight days (Corpet et al., 1997).

Weanling female inbred Fischer 344 rats were fed semipurified
diets containing 0 or 15% undegraded kappa/lambda-carrageenan. At
seven weeks of age, all animals except controls were given
azoxymethane subcutaneously at a dose of 8 mg/kg bw per week for
10 weeks or N-methyl- N-nitrosourea intrarectally at a dose of 2 mg
per rat twice a week for three weeks. The rats given azoxymethane were
autopsied at 40 weeks, and those given N-methyl- N-nitrosourea at
30 weeks after the first injection. No tumours were induced in the
colon or in other organs of rats fed the control diet, but one
untreated rat fed the carrageenan diet had a colon adenoma. The
animals fed carrageenan and treated with azoxymethane or
N-methyl- N-nitrosourea had a higher incidence of colorectal
tumours (number of rats with colorectal tumours and number of tumours
per tumour-bearing rat) than those fed the control diet and treated
similarly. The undegraded carrageenan therefore enhanced the induced
colorectal carcinogenesis (Watanabe et al., 1978).

Seven-week-old male Fischer 344 rats were divided into two groups
of 20 rats and two of 15 rats. kappa-Carrageenan (from an
unspecified species) was administered to one group of 20 and one of
15 rats at 6% in the diet for 24 weeks. Both groups of 20 rats then
received weekly subcutaneous injections of 1,2-dimethylhydrazine at 20
mg/kg bw for 16 weeks. Rats receiving both 1,2-dimethylhydrazine and
carrageenan had a significantly greater number of colonic tumours per
rat than those receiving 1,2-dimethyl-hydrazine alone. Additionally,

the number of rats with tumours, the number of tumours in a more
proximal location on the colon, and the overall size of the tumours
were all increased (Arakawa et al., 1986). It was suggested that this
promoter function might result from enhanced excretion of lithocholic
acid (Arakawa et al., 1988). The ratio of N-acetylneuraminic acid to
N-glycolyl-neuraminic acid was higher in the colonic tumours than in
the surrounding tissue, but carrageenan had no effect on this ratio
(Arakawa et al., 1989).

Thirty five-week-old female Fischer 344 rats were injected
intraperito-neally with azoxy-methane at 20 mg/kg bw to initiate colon
cancer and were then divided into three groups. The controls were
given water to drink, and the other two groups were given either a
solution of 0.25% carrageenan (mainly kappa form) or a 2.5% gel.
Promotion was assessed as the multiplicity of aberrant crypt foci
after 100 days. This value was significantly increased in the group
receiving carrageenan (Corpet et al., 1997).

In a study described in an abstract, the promotion of
microadenomas of the colon was compared in conventional rats given
kappa-carrageenan from E. cottonii/G. radula as either 0.25% in
the drinking-water or 2.5% as a gel in place of the drinking-water and
in gnotobiotic rats that had been associated with intestinal
microflora from human donors who had been 'adapted' to carrageenan.
Azoxymethane-initiated microadenomas were promoted in the conventional
rats rats fed carrageenan but not in the rats with human intestinal
microflora (Millet et al., 1997).

2.2.6.2 Gastrointestinal tract

Four of the citations in the report of the 1973 meeting of the
Committee were unpublished and not available. One reference is to a
letter with inadequate details which refers to an untraced article 'in
press'. The report of Poulsen (1973) is mentioned above. In groups of
10 female Wistar rats fed 20% carrageenan (type and origin
unspecified) or basal diet for four weeks, no effect was seen on the
excretion of polyethylene glycol 4000, but the excretion of
polyethylene glycol 900 was decreased and the length of the small
intestinal was increased (Elsenhans & Caspary, 1989).

2.2.6.3 Immune system

In most of the early studies of this system, the type and origin
of the carrageenan was not specified in sufficient detail for it to be
identified.

Pretreatment of DA rat spleen cells with
kappa/lambda-carrageenan from C. crispus inhibited their
proliferative response to phytohaemagglutinin. Supernatants of
macrophages incubated with 1-10 µg/ml of carrageenan were also
inhibitory, whereas the same concentrations of carrageenan had no
effect. Active secretion of a soluble inibitor was suggested, and some

evidence that the mechanism might be prostaglandin-mediated was
obtained (Bash & Cochrane, 1980).

The effect of phytohaemagglutinin was tested in spleen and
lymph-node cells of Lewis rats that had received a single oral dose of
0.5-50 mg kappa/lambda-carrageenan from C. crispus three days
earlier. The proliferative responses were significantly suppressed at
low doses but not at high doses. A similar effect was seen in
offspring of DA rats that had been weaned onto 0, 0.1, or 1 mg/ml of
carrageenan in the drinking-water. It was hypothesized that low doses
of carrageenan in vivo and in vitro stimulate a population of
macrophages that secretes an inhibitor of T lymphocyte proliferation
(Bash & Vago, 1980).

Spleen cells from weanling male DA Ag-B4 rats given boiled
aqueous solutions of 5 or 50 mg/kg bw kappa/lambda-carrageenan from
C. crispus by gavage on five days per week for four weeks showed
long-lasting depression of mitogenesis stimulated by
phytohaemagglutinin or concanavalin A. The maximal effect occurred
with the low dose. There was also evidence of suppression of host
resistance to Listeria monocytogenes (Cochran & Baxter, 1984).

iota-Carrageenan from E. spinosum had a systemic adjuvant
action in Brown Norway rats after intraperitoneal injection of 1 mg
but not when given by gavage at 10 mg (Coste et al., 1989).

Two types of iota-carrageenan from E. spinosum and one of
kappa-carrageenan from C. crispus were fed at 5% in the diet to
male Sprague-Dawley rats for 30 days. Although the concentration of
immunoglobulin A antibodies in the bile was not significantly
affected, the binding specificity for caecal bacteria was
significantly enhanced by all three types of carrageenan (Mallett et
al., 1985).

Groups of 12 PVG male rats were given drinking-water containing
0.5% iota-carrageenan from E. spinosum, kappa-carrageenan from
E. cottonii/C. crispus, or lambda-carrageenan from G. radula.
Treatment did not alter local biliary or systemic antibody responses,
but the anti-sheep red blood cell haemagglutinating antibody response
was temporarily suppressed. kappa-Carrageenan was less effective
than the other types (Nicklin & Miller, 1984).

Groups of four male PVG rats were maintained on tap water
containing 0 or 0.25% iota-carrageenan from E. spinosum. After 184
days of treatment, they were challenged intraperitoneally with sheep
red blood cells, and their serum was analysed for antibody activity.
The treated group had a delayed and significantly reduced antibody
response (Nicklin et al., 1988).

2.2.6.4 Nutrient absorption

Feeding of Fischer 344 rats on diets containing 15%
kappa/lambda-carrageenan from G. radula had a cholesterol lowering
effect (Reddy et al., 1980), but feeding of 5% kappa/lambda-
carrageenan from C. crispus had no effect on growth rate or various
parameters of nutrient absorption in rats (Tomarelli et al., 1974).

Excretion of calcium, iron, zinc, copper, chromium, and cobalt
was measured in weanling male Sprague-Dawley rats during an eight-day
balance trial in which the animals were fed diets containing 0 or 10%
kappa/lambda-carrageenan from C. crispus. Carrageenan
significantly reduced the absorption of all minerals (Harmuth-Hoene &
Schelenz, 1980).

The extent of absorption of calcium by male Sprague-Dawley rats
from radiolabelled calcium triphosphate or calcium chloride was
unaffected by co-adminstration of 1% kappa/lambda-carrageenan from
C. crispus (Koo et al., 1993).

2.2.6.5 Irritation and sensitization

Food grade iota-carrageenan was not irritating to unwashed eyes
of rabbits and was minimally irritating to washed eyes. It was not
irritating to intact skin and was minimally irritating to abraded
skin. It was not sensitizing to the skin of guinea-pigs (Weiner,
1991).

2.3 Observations in humans

In none of the studies considered at the seventeenth meeting of
the Committee was identification provided of the seaweed from which
the carrageenan used in infant formulas originates. It has been
stated, however, to be kappa/lambda-carrageenan (International Food
Additives Council, 1997). Additionally, in none of the studies were
comparisons made with controls of the effects on infants of the
inclusion of carrageenan in infant formula.

Co-administration of 20 g carrageenan (type and seaweed of origin
unspecified) and 300 000 IU vitamin A to 11 women aged 19-22 years
resulted in increased absorption of vitamin A (Kasper et al., 1979).

Data from the United States National Maternal and Infant Health
Survey indicate that a slightly higher proportion of infants who were
fed liquid formula containing 0.03% kappa/lambda-carrageenan from an
unknown species were free of upper respiratory tract infection during
the first six months of life as compared with infants fed powdered,
carrageenan-free formula. The odds ratio for the risk of one or more
colds being reported during each month of the infant's first six
months of life is 0.94 (95% confidence interval, 0.90-0.99;
p = 0.015). The authors of the study concluded that carrageenan is
not immunosuppressive; however, the Committee noted deficiencies in
the study (Sherry et al., 1993).

3. COMMENTS

Most of the toxicological studies in which an identifiable type
of carrageenan and an identifiable seaweed species were used were
undertaken with kappa- or kappa/lambda-carrageenan from
C. crispus. The results of the few parallel studies suggest that
there are no large differences in the effects of the different forms
of carrageenan or in the effects of carrageenans prepared from
different species of seaweed.

The carrageenans are generally of high relative molecular mass
and are not broken down to very small molecules in the
gastrointestinal tract. At high levels of intake, these properties can
cause adverse effects through their physical action on the
gastrointestinal tract. Ulceration was observed previously in the
gastrointestinal tract of guinea-pigs given high concentrations of
iota-carrageenan. Similar findings were not reported in a recent
well-conducted 90-day study in which rats were fed diets containing 5%
conventionally processed iota-carrageenan from E. spinosum or
kappa-carrageenan from E. cottonii. The changes that occurred,
most notably an increase in the relative weight of the full and empty
caecum, were considered to be the consequence of the accumulation of
poorly absorbed material in the caecum and to be of no toxicological
significance. The partial reversal of the caecal weight changes during
the 28-day recovery phase of the study and the absence of
histopathological changes support this conclusion.

Studies of the carcinogenicity of carrageenan in rats have shown
no effect. In addition, the results of assays for the genotoxicity of
carrageenan have been negative. A proliferative response of the mucosa
of the gastrointestinal tract of rats fed two forms of carrageenan at
2.6 or 5% of the diet has been reported; the response was reversible
in the study in which 5% carrageenan was given. This response might
explain the promotion of the action of known experimental colon
carcinogens in rats given 2.5 or 6% of carrageenan. The Committee was
aware of an abstract of a conference report which indicated that
tumour promotion does not occur in rats in which the intestinal
microflora are derived from human donors who have been 'adapted' to
carrageenan. This would suggest that promotion of colon carcinogenesis
in the rat is dependent on the presence of the normal microflora of
the gastrointestinal tract.

Early reports that carrageenan is present in parenteral tissues
after dietary intake are probably unreliable. The presence of
carrageenans in the macrophages in the walls of the caecum and colon
may reflect the relative molecular mass distribution of the
preparation used in the study. Maintenance of a restriction on the
relative mass distribution in the specifications of carrageenan for
food use provides protection against the adverse effects of
carageenans of low relative molecular mass.

There was evidence that carrageenan can affect the immune
response of the gastrointestinal tract; however, no validated tests
for assessing the nature and potential consequences of such an effect
were available. A short communication relating to an epidemiological
study did not indicate that carrageenan was immunotoxic in neonates
receiving milk preparations containing carrageenan.

4. EVALUATION

The Committee reiterated its previous statement that the ADI
should not be considered applicable to neonates and young infants
below the age of 12 weeks.

The Committee extended the previous ADI 'not specified' to
include processed Eucheuma seaweed in a group ADI 'not specified'.
It expressed concern about the potential promotion of colon
carcinogenesis by carrageenans and processed Eucheuma seaweed and
therefore made the group ADI 'not specified' temporary, pending
clarification of the significance of the promotion of colon cancer
observed in experiments in rats. The Committee requires this
information for review in 2001.

5. REFERENCES

Abraham, R., Golberg, L. & Coulston, F. (1972) Uptake and storage of
degraded carrageenan in lysosomes of reticuloendothelial cells of the
rhesus monkey, Macaca mulatta. Exp. Mol. Pathol., 17, 77-93.

Abraham, R., Benitz, K.-F., Mankes, R.F., Rosenblum, I. & Ringwood, N.
(1983) Studies on rhesus monkeys (Macaca mulatta) receiving native
carrageenan (Chondrus crispus) orally for 7.5 years. Book 1.
Unpublished summary of final report from Institute of Experimental
Pathology and Toxicology, Albany Medical College. Submitted to WHO by
R.J.H. Gray, International Food Additives Council, Atlanta, Georgia,
USA and P. Couchoud, Marinalg, Paris, France.

Anderson, W. & Soman, P.D. (1966) The absorption of carrageenans.
J. Pharm. Pharmacol., 18, 825-827.

Anonymous (1976) Unpublished report submitted to WHO at the
twenty-eighth meeting of the Committee.

Arakawa, S., Okumura, M., Yamada, S., Ito, M. & Tejima, S. (1986)
Enhancing effect of carrageenan on the induction of rat colonic tumors
by 1,2-dimethylhydrazine and its relation to ß-glucuronidase
activities in feces and other tissues. J. Nutr. Sci. Vitaminol., 32,
481-485.

Arakawa, S., Ito, M. & Tejima, S. (1988) Promoter function of
carrageenan on development of colonic tumours induced by
1,2-dimethylhydrazine in rats. J. Nutr. Sci. Vitaminol., 34,
577-585.

Arakawa, S., Wakazono, H., Ishihara, H. & Tejima, S. (1989)
N-Acetylneuraminic acid and N-glycolylneuraminic acid in glycopeptides
of colonic tumor and mucosa in rats treated with carrageenan and
1,2-dimethylhydrazine. Biochem. Biophys. Res. Commun., 159, 452-456.

Bash, J.A. & Cochrane, F.R. (1980) Carrageenan-induced suppression of
T lymphocyte proliferation in the rat: In vitro production of a
suppressor factor by peritoneal macrophages. J. Reticuloendothel.
Soc., 28, 203-211.

Bash, J.A. & Vago, J.R. (1980) Carrageenan-induced suppression of T
lymphocyte proliferation in the rat: In vivo suppression induced by
oral administration. J. Reticuloendothel. Soc., 28, 213-221.

Benitz, K.-F., Golberg, L. & Coulston, F. (1973) Intestinal effects of
carrageenans in the rhesus monkey (Macaca mulatta). Food Cosmet.
Toxicol., 11, 565-575.

Brusick, D. (1975) Mutagenic evaluation of compound FDA 71-5.
977052-14-4 calcium carrageenan. Unpublished report from Litton
Bionetics, Inc., Kensington, Maryland, USA. Submitted to WHO by R.J.H.
Gray, International Food Additives Council, Atlanta, Georgia, USA, and
P. Couchoud, Marinalg, Paris, France.

Calvert, R.J. & Reicks, M. (1988) Alterations in the colonic thymidine
kinase enzyme activity induced by consumption of various dietary
fibers. Proc. Soc. Exp. Biol. Med., 189, 45-51.

Calvert, R.J. & Satchithanandam, S. (1992) Effects of graded levels of
high-molecular-weight carrageenan on colonic mucosal thymidine kinase
activity. Nutrition, 8, 252-257.

Capron, I., Yvon, M. & Muller, G. (1996) In-vivo gastric stability of
carrageenan. Food Hydrocolloids, 10, 239-244.

Carey, P.L. (1958) The digestibility of polysaccharides by rats.
Thesis, Purdue University. Submitted to WHO by R.J.H. Gray,
International Food Additives Council, Atlanta, Georgia, USA, and P.
Couchoud, Marinalg, Paris, France.

Chen, J., Appleby, D.W., Weber, P. & Abraham, R. (1981) Detection of a
carrageenan in rat liver homogenates after feeding in the diet
(Abstract). Toxicologist, 1, 133.

Cochran, F.R. & Baxter, C.S. (1984) Macrophage-mediated suppression of
T lymphocyte proliferation induced by oral carrageenan administration.
Immunology, 53, 291-297.

Collins, T.F.X., Black, T.N. & Prew, J.H. (1977a) Long-term effects of
calcium carrageenan in rats. I. Effects on reproduction. Food
Cosmet. Toxicol., 15, 533-538.

Collins, T.F.X., Black, T.N. & Prew, J.H. (1977b) Long-term effects of
calcium carrageenan in rats. II. Effects of foetal development.
Food Cosmet. Toxicol., 15, 539-545.

Collins, T.F.X., Black, T.N. & Prew, J.H. (1979) Effects of calcium
and sodium carrageenans and [iota]-carrageenan on hamster foetal
developmemnt. Food Addit. Contam., 17, 443-449.

Corpet, D.E., Taché, S. & Préclaire, M. (1997) Carrageenan given as a
jelly, does not initiate, but promotes the growth of aberrant crypt
foci in the rat colon. Cancer Lett., 114, 53-55.

Coste, M., Dubuquoy, C. & Tomé, D. (1989) Effect of systemic and
orally administered iota-carrageenan on ovalbumin-specific antibody
response in the rat. Int. Arch. Allergy Appl. Immunol., 88, 474-476.

Coulston, F., Golberg, L., Abraham, R., Benitz, K.-F. & Ford, W.
(1975) Carrageenans (Hercules Incorporated). Safety evaluation. Nine
month study. Unpublished interim progress report (March 1975) from
Institute of Comparative and Human Toxicology, Center of Experimental
Pathology and Toxicology, Albany Medical College, Albany, New York,
USA. Submitted to WHO by R.J.H. Gray, International Food Additives
Council, Atlanta, Georgia, USA, and P. Couchoud, Marinalg, Paris,
France.

Coulston, F., Abraham, R., Benitz, K.-F. & Ford, W. (1976) Response of
the livers of male and female rats (Osborn/Mendel and Sprague-Dawley)
to Alphacel and a carrageenan (HMR) for nine months using two
different basal diets. Nine month progress report (March 1976) from
Institute of Comparative and Human Toxicology, Center of Experimental
Pathology and Toxicology, Albany Medical College, Albany, New York,
USA. Submitted to WHO by R.J.H. Gray, International Food Additives
Council, Atlanta, Georgia, USA, and P. Couchoud, Marinalg, Paris,
France.

Dewar, E.T. & Maddy, M.L. (1970) Faecal excretion of degraded and
native carrageenan by the young rat. J. Pharm. Pharmacol., 22,
791-793.

Duncan, J.G.C. (1965) Thesis, University of Glasgow, Scotland, United
Kingdom

Ekström, L.G. (1985) Molecular-weight-distribution and the behaviour
of kappa-carrageenan on hydrolysis. Part II. Carbohydrate Res., 135,
283-289.

Ekström, L.G. & Kuivinen, J. (1983) Molecular weight distribution and
hydrolysis behaviour of carrageenans. Carbohydrate Res., 116, 89-94.

Ekström, L.G., Kuivinen, J. & Johansson, G. (1983) Molecular weight
distribution and hydrolysis behaviour of carrageenans. Carbohydrate
Res., 116, 89-94.

Elsenhans, B. & Caspary, W.F. (1989) Differential changes in the
urinary excretion of two orally administered polyethylene glycol
markers (PEG 900 and PEG 4000) in rats after feeding various
carbohydrate gelling agents. J. Nutr., 119, 380-387.

Elsenhans, B., Blume, R. & Caspary, W.F. (1981) Long-term feeding of
unavailable carbohydrate gelling agents. Influence of dietary
concentration and microbiological degradation on adaptive responses in
the rat. Am. J. Clin. Nutr., 34, 1837-1848.

Engster, M. & Abraham, R. (1976) Cecal response to different molecular
weights and types of carrageenan in the guinea pig. Toxicol. Appl.
Pharmacol., 38, 265-282.

Epifanio, E.C., Veroy, R.L., Uyenco, F., Cajipe, G.J.B. & Laserna,
E.C. (1981) Carageenan from Eucheuma spiratum in bacteriological
media. Appl. Environ. Microbiol., 41, 155-163.

Food and Drug Research Labs., Inc. (1971) Report on contract no. FDA
71-260 from Food and Drug Research Laboratories, Inc., Maspeth, New
York, USA. Submitted to WHO by R.J.H. Gray, International Food
Additives Council, Atlanta, Georgia, USA, and P. Couchoud, Marinalg,
Paris, France.

Food and Drug Research Labs., Inc. (1972a) Teratologic evaluation of
FDA 71-3 (sodium carragheenate) in mice, rats, hamsters and rabbits.
Report number PB-221 812 from Food and Drug Research Laboratories,
Inc., Maspeth, New York, USA. Submitted to WHO by R.J.H. Gray,
International Food Additives Council, Atlanta, Georgia, USA, and P.
Couchoud, Marinalg, Paris, France.

Food and Drug Research Labs., Inc. (1972b) Teratologic evaluation of
FDA 71-5 (calcium carragheenate) in mice, rats, hamsters and rabbits.
Report number PB-221 787 from Food and Drug Research Laboratories,
Inc., Maspeth, New York, USA. Submitted to WHO by R.J.H. Gray,
International Food Additives Council, Atlanta, Georgia, USA, and P.
Couchoud, Marinalg, Paris, France.

Food and Drug Research Labs., Inc. (1973) Teratologic evaluation of
carragheenan salts in rats and hamsters. Report from Food and Drug
Research Laboratories, Inc., Waverly, New York, USA. Submitted to WHO
by R.J.H. Gray, International Food Additives Council, Atlanta,
Georgia, USA, and P. Couchoud, Marinalg, Paris, France.

Gibson, G.R., Macfarlane, S. & Cummings, J.H. (1990) The
fermentability of polysaccharides by mixed human faecal bacteria in
relation to their suitability as bulk-forming laxatives. Lett. Appl.
Microbiol., 11, 251-254.

Grasso, P., Sharratt, M., Carpanini, F.M.B. & Gangolli, S.D. (1973)
Studies on carrageenan and large-bowel ulceration in mammals. Food
Cosmet. Toxicol., 11, 555-564.

Harmuth-Hoene, A.E. & Schelenz, R. (1980) Effect of dietary fiber on
mineral absorption in growing rats. J. Nutr., 110, 1774-1784.

Hawkins, W.W. & Yaphe, W. (1965) Carrageenan as a dietary constituent
for the rat: Faecal excretion, nitrogen absorption, and growth.
Can. J. Biochem., 43, 479-484.

Hwang, U.K. & Connors, N.A. (1974) Investigation of the toxic and
teratogenic effects of GRAS substances to the developing chicken
embryo. Unpublished report from St Louis University School of
Medicine, St Louis, Missouri, USA. Submitted to WHO by the US Food and
Drug Administration, USA.

International Food Additives Council (1997) Carrageenan. Unpublished
monograph prepared by the International Food Additives Council,
Washington DC. Submitted to WHO by R.J.H. Gray, International Food
Additives Council, Atlanta, Georgia, USA, and P. Couchoud, Marinalg,
Paris, France.

Kasper, H., Rabast, U., Fassl, H. & Fehle, F. (1979) The effect of
dietary fiber on the postprandial serum vitamin A concentration in
man. Am. J. Clin. Nutr., 32, 1847-1849.

Koo, J., Weaver, C.M. & Neylan, M.J. (1993) Solubility of calcium
salts and carrageenan used in infant formulas did not influence
calcium absorption in rats. J. Pediatr. Gastroenterol. Nutr., 17,
298-302.

Litton Bionetics, Inc. (1972) Mutagenic evaluation of compound FDA
71-3. Sodium carrageenan. Unpublished report from Litton Bionetics,
Inc., Kensington, Maryland, USA. Submitted to WHO by R.J.H. Gray,
International Food Additives Council, Atlanta, Georgia, USA, and P.
Couchoud, Marinalg, Paris, France.

Mallett, A.K., Wise, A. & Rowland, I.R. (1984) Hydrocolloid food
additives and rat caecal microbial enzyme activities. Food Chem.
Toxicol., 22, 415-418.

Mallett, A.K., Rowland, I.R., Bearne, C.A. & Nicklin, S. (1985)
Influence of dietary carrageenans on microbial biotransformation
activities in the cecum of rodents and on gastrointestinal immune
status in the rat. Toxicol. Appl. Pharmacol., 78, 377-385.

Mankes, R. & Abraham, R. (1975) Lysosomal dysfunction in colonic
submucosal macrophages of rhesus monkeys caused by degraded iota
carrageenan. Proc. Soc. Exp. Biol. Med., 150, 166-170.

McGill, H.C., Jr, McMahan, C.A., Wigodsky, H.S. & Sprinz, H. (1977)
Carrageenan in formula and infant baboon development.
Gastroenterology, 73, 512-517.

Millet, A.-S., Verhaege, E., Préclaire, M., Taché, S. & Corpet, D.
(1997) A food gelling agent, carrageenan K, promotes the growth of
microadenomas of the colon in conventional rats but not in gnotobiotic
rats with human flora (Abstract). In: Proceedings of the Fifth
Symposium, Toulouse, Munich, 30 April-4 May 1997, p. 67 (in French).

Morard, J.C., Fray, A., Abadie, A. & Robert, L. (1964) Nature of the
renal lesions induced by intravenous injection of carrageenan.
Nature, 202, 401-402.

Mori, H., Ohbayashi, F., Hirono, I., Shimada, T. & Williams, G.M.
(1984) Absence of genotoxicity of the carcinogenic sulfated
polysaccharides carrageenan and dextran sulfate in mammalian DNA
repair and bacterial mutagenicity assays. Nutr. Cancer, 6, 92-97.

Nicklin, S. & Miller, K. (1984) Effect of orally administered
food-grade carrageenans on antibody-mediated and cell-mediated
immunity in the inbred rat. Food Chem. Toxicol., 22, 615-621.

Nicklin, S., Baker, K. & Miller, K. (1988) Intestinal uptake of
carrageenan: Distribution and effects on humoral immune competence.
Adv. Exp. Med. Biol., 237, 813-820.

Nilson, H.W. & Schaller, J.W. (1941) Nutritive value of agar and Irish
moss. Food Res., 6, 461-469.

Nilson, H.W. & Wagner, J.A. (1959) Feeding test with carrageenin.
Food Res., 24, 235-239.

Ochuba, G.U. & von Riesen, V.L. (1980) Fermentation of polysaccharides
by Klebsiellae and other facultative bacteria. Appl. Environ.
Microbiol., 39, 988-992.

Pittman, K.A., Golberg, L. & Coulston, F. (1976) Carrageenan: The
effect of molecular weight and polymer type on its uptake, excretion
and degradation in animals. Food Cosmet. Toxicol., 14, 85-93.

Poulsen, E. (1973) Short-term peroral toxicity of undegraded
carrageenan in pigs. Food Cosmet. Toxicol., 11, 219-227.

Reddy, B.S., Watanabe, K. & Sheinfil, A. (1980) Effect of dietary
wheat bran, alfalfa, pectin, and carrageenan on plasma cholesterol and
fecal bile acid and neutral sterol excretion in rats. J. Nutr., 110,
1247-1254.

Robbins, M.C. (1997) 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, USA.

Rovasio, R.A. & Monis, B. (1980) Lethal and teratogenic effects of
lambda-carrageenan, a food additive, on the development of the chick
embryo. Toxicol. Pathol., 8, 14-19.

Rustia, M., Shubik, P. & Patil, K. (1980) Lifespan carcinogenicity
tests with native carrageenan in rats and hamsters. Cancer Lett.,
11, 1-10.

Salyers, A.A., West, S.E.H., Vercellotti, J.R. & Wilkins, T.D. (1977)
Fermentation of mucins and plant polysaccharides by anaerobic bacteria
from the human colon. Appl. Environ. Microbiol., 34, 529-533.

Sharratt, M., Grasso, P., Carpanini, F. & Gangolli, S.D. (1970)
Carrageenan ulceration as a model for human ulcerative colitis.
Lancet, ii, 932.

Sherry, B., Flewelling, A. & Smith, A.L. (1993) Carrageenan: An asset
or a detriment in infant formula? Am. J. Clin. Nutr., 58, 715.

Stancioff, D.J. & Renn, D.W. (1975) Physiological effects of
carrageenan. Am. Cancer Soc. Symp. Ser., 15, 1-12.

Stanford Research Institute (1972) Study of mutagenic effects of
calcium carrogeenan (FDA No. 71-5). Unpublished report from Stanford
Research Institute, Menlo Park, California, USA. Submitted to WHO by
R.J.H. Gray, International Food Additives Council, Atlanta, Georgia,
USA, and P. Couchoud, Marinalg, Paris, France.

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.

Tomarelli, R.M., Tucker, W.D., Jr, Bauman, L.M., Savini, S. & Weaber,
J.R. (1974) Nutritional qualities of processed milk containing
carrageenan. J. Agr. Food Chem., 22, 819-824.

Udall, J.N., Harmatz, P., Vachino, G., Galdabini, J. & Walker, W.A.
(1981) Intestinal transport and liver uptake of a food additive
present in infant formulas (Abstract). Pediatr. Res., 15, 549.

Vorhees, C.V., Butcher, R.E., Brunner, R.L. & Sobokta, T.J. (1979) A
developmental test battery for neurobehavioral toxicity in rats: A
preliminary analysis using monosodium glutamate, calcium carrageenan
and hydroxyurea. Toxicol. Appl. Pharmacol., 50, 267-282.

Watanabe, K., Reddy, B.S., Wong, C.Q. & Weisburger, J.H. (1978) Effect
of dietary undegraded carrageenan on colon carcinogenesis in F344 rats
treated with azoxymethane or methylnitrosourea. Cancer Res., 38,
4427-4430.

Watt, J. & Marcus, R. (1969) Ulcerative colitis in the guinea-pig
caused by seaweed extract. J. Pharm. Pharmacol., 21 (Suppl.),
187S-188S.

Weiner, M.L. (1991) Toxicological properties of carrageenan. Agents
Actions, 32, 46-51.

Wilcox, D.K., Higgins, J. & Bertram, T.A. (1992) Colonic epithelial
cell proliferation in a rat model of nongenotoxin-induced colonic
neoplasia. Lab. Invest., 67, 405-411.

    See Also:
       Toxicological Abbreviations
       CARRAGEENAN (JECFA Evaluation)
       Carrageenan (IARC Summary & Evaluation, Volume 31, 1983)