evaluation of certain food additives - libdoc.who.int - World Health ...

Cassia gum is of low acute oral toxicity in rats and mice. It was also of low
oral toxicity in a 28-day study in rats, a 90-day study in dogs and a 90-day
study in cats. In these studies, administration of semi-refined cassia gum at
dietary concentrations up to 50 000 mg/kg in rats (equal to doses of 4960 mg/
kg bw per day for males and 4590 mg/kg bw per day for females), 25 000
mg/kg in dogs (equal to doses of 3290 mg/kg bw per day for males and 3890
mg/kg bw per day for females) and 25 000 mg/kg in cats (equal to doses of
2410 mg/kg bw per day for males and 2740 mg/kg bw per day for females)
did not result in adverse effects. The decrease in food consumption and accompanying
decrease in body weight gain noted in the 28-day rat study and
the increase in water consumption observed in the 90-day dog study were
considered to be related to the viscous nature of cassia gum and not considered
to be of toxicological relevance. Therefore, the NOAELs in rats and dogs
were 4590 and 3290 mg/kg bw per day, respectively, the highest doses tested.
The no-observed-effect level (NOEL) in cats was 2410 mg/kg bw per day,
the highest dose tested.
Cassia gum and/or semi-refined cassia gum were tested in reverse mutation
assays in bacteria and in a chromosomal aberration assay and a gene mutation
assay in mammalian cells. Cassia gum was also tested in an in vivo sperm
abnormality test and an in vivo micronucleus test in mice. From these studies,
the Committee concluded that cassia gum is not genotoxic. Cassia gum was
not tested in a carcinogenicity study, but, given the lack of genotoxicity and
the negative results obtained in assays of carcinogenicity of locust (carob)
bean gum and tara gum, the Committee did not consider a study of long-term
toxicity and/or carcinogenicity necessary for the safety evaluation of cassia
gum.
Semi-refined cassia gum was tested in reproductive toxicity studies in the rat
(two-generation study) at dietary concentrations up to 50 000 mg/kg (equal
to a dose of 5280 mg/kg bw per day for males and 6120 mg/kg bw per day
for females) and in the cat (one-generation study) at dietary concentrations
up to 25 000 mg/kg (equal to a dose of 2470 mg/kg bw per day in males and
2950 mg/kg bw per day in females). In the cat study, high mortality in the
control group resulted in a high litter loss, impairing appropriate comparison
between control and treatment groups. Therefore, this cat study was considered
not suitable for use in the evaluation. In the two-generation reproductive
toxicity study in rats, the only effects observed were a slightly reduced pregnancy
rate (which was not observed in a subsequent second mating resulting
in an F 1b generation) and a slight, but not significant, decrease in pup weights
of the F 1a and F 2 generations at the highest dose level. Therefore, 50 000 mg/
kg feed (equal to 5280 mg/kg bw per day), the highest dose tested, was taken
to be the NOEL.
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