Safety evaluation of certain food additives

In a 13-week study of toxicity (certified for compliance with GLP and QA),
groups of five male and five female cats were given semi-refined cassia gum as part
of a canned food diet at a concentration of 0, 5000 or 25 000 mg/kg (equal to doses
of 0, 520 and 2410 mg/kg bw per day for males and 0, 530 and 2740 mg/kg bw per
day for females). The study was essentially performed according to OECD Test
Guideline 409, with some slight deviations. No adverse or treatment-related effects
on mortality, behaviour, clinical signs, body weight gain, food and water
consumption, haematology, clinical biochemistry, organ weights, macroscopy or
microscopy were observed. The no-observed-effect level (NOEL) was 25 000 mg/kg
feed, equal to 2410 mg/kg bw per day, the highest dose tested in this study
(Virat, 1984).
2.2.3 Long-term studies of toxicity and carcinogenicity
No information was available for cassia gum.
In a limited long-term study of toxicity with guar gum reviewed by the
Committee at its nineteenth meeting (Annex 1, reference 39), no adverse effects
were observed in rats administered guar gum at a dietary concentration of 5% for
24 months. In carcinogenicity studies reviewed by the Committee at its twenty-fifth
and thirtieth meetings (Annex 1, references 57 and 74), no significant adverse
effects were observed in rats and mice administered locust (carob) bean gum or
tara gum at dietary concentrations up to 5% for 103 weeks.
2.2.4 Genotoxicity
The results of five studies of genotoxicity in vitro with cassia gum and/or
semi-refined cassia gum (three bacterial reverse mutation assays, one
chromosomal aberration assay and one gene mutation assay) are summarized in
Table 1
. The first bacterial reverse mutation study (Verspeek-Rip, 1998a) was
conducted with semi-refined cassia gum, the second with purified semi-refined
cassia gum (8.6 mg total anthraquinones/kg; Meerts, 2003) and the third with cassia
gum (Weidu, 2006). The first two studies followed OECD Test Guideline 471
(Bacterial Reverse Mutation Test) and were certified for compliance with GLP and
QA. For the third, limitedly reported study, no statements regarding compliance with
GLP and QA were available. The positive results obtained for semi-refined cassia
gum in strain TA100 at precipitating concentrations in the first reverse mutation
study (Verspeek-Rip, 1998a) were not observed in the second reverse mutation
study. The chromosomal aberration assay (Bertens, 1998) was performed
according to OECD Test Guideline 473 (In Vitro Mammalian Chromosome
Aberration Test), and the gene mutation assay (Verspeek-Rip, 1998b) was
conducted according to OECD Test Guideline 476 (In Vitro Mammalian Cell Gene
Mutation Test). Both studies were certified for compliance with GLP and QA and
used semi-refined cassia gum.

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