Diutan gum

Endpoint summary

Description of key information

A 4-week oral toxicity study of Diutan found no evidence of toxicity at the maximum tested dosage of 1000 mg/kg/day.
The closely similar chemical analogue gellan gum has shown similarly low toxicity in a variety of repeat-dose studies, performed in different species.  In a 13-week rat study, administration of gellan gum at up to 6% in the diet found no evidence of toxicity: the NOAEL of 6% in diet equated to achieved test substance intake s of 6.99-2.95 g/kg/day (males), 7.26-3.76 g/kg/day (females).  In a 96-98 week mouse carcinogenicity study, feeding gellan gum at up to 3% in diet (overall achieved intakes 4.9 g/kg/day (males), 6.2 g/kg/day (females)) produced no overt signs of toxicity and no adverse histopathology findings.  To support the use of gellan gum as a food additive, it has also been investigated using less commonly  performed repeat-dose test protocols.  Toxicology Monograph 724 (Food Additive Series 28, 1990) of the Joint FAO/WHO Expert Committee on Food Additives describes:
- a carcinogenicity study using rats exposed to gellan gum in utero then fed for 2 further years at up to 5% in the diet, which found no neoplastic or non-neoplastic changes associated with test exposure
- a 52-week beagle dog study using levels up to 6% in the diet which found no effect of treatment
- a 28-day rhesus monkey study giving oral doses up to 3 g/kg/day which found no overt signs of toxicity.
It is reasonable to predict that Diutan would show a similar pattern of low  toxicity in subchronic and chronic toxicity studies.

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Endpoint conclusion

Dose descriptor:

NOAEL

4 900 mg/kg bw/day

Study duration:

subchronic

Species:

rat

Additional information

The cited subchronic NOAEL value cited is selected as key for chemical safety assessment because this is both:

- the lower of the two overall mean achieved dosages (for male and females) corresponding to the mouse 96 -98 week carcinogenicity study NOAEL, and

- the lower of the two mean achieved dosages (for male and females) in the 13 -week rat toxicity study (calculated as simple means of the week 1 and week 13 intakes: mean (males) = 4.97 g/kg/day).

Justification for classification or non-classification

Based on the demonstrated low toxicity of both Diutan and its close analogue gellan gum, no classification in respect of repeated dose toxicity is appropriate.