Safety evaluation of certain food additives - ipcs inchem

192 STEVIOL GLYCOSIDES (addendum)
weeks 8 and 12, although no dose–response relationship or histopathological
changes in muscle or nervous system were found. This was attributed by the
authors to the slightly smaller size of the animals in the group and was not
considered to be treatment related. In the high-dose group, females showed
statistically significantly reduced cage floor activity scores in week 8 only. Rearing
activity was lower in females in week 8 of treatment, but no differences between
test and control groups were seen in week 12. There was a dose-related decrease
in body weight gains, which was significantly different from control at all doses in
the males and at 25 000 and 50 000 mg/kg in the females. Terminal body weights
did not differ significantly from controls in either sex. After day 4, no differences
were seen in food consumption between test and control animals in all groups.
Haemoglobin concentrations and reticulocyte counts were found to be statistically
significantly lower in the 50 000 mg/kg diet group compared with controls on days
46 and 89. No dose–response was observed. Compared with controls, females
receiving 25 000 mg/kg or above showed significantly elevated prothrombin times.
This was not considered to be treatment related. Plasma urea concentrations
were significantly elevated in both sexes in the high-dose group compared with
controls. Non-significant elevations were seen in the two lowest dose groups, and
there was no apparent dose–response relationship. Absolute epididymal weights
for males, ovary weights for females and heart and kidney weights for both sexes
in the high-dose group were statistically significantly reduced compared with
controls. Macropathology and histopathology revealed no apparent treatmentrelated
effects. The authors considered that the decreased body weight gain was
due to taste aversion and decreased caloric density of the diet (Stamp, 2006b; Curry
& Roberts, 2008). The NOEL in this study was 50 000 mg rebaudioside A/kg in the
feed or 1370 mg/kg bw per day in males and 1530 mg/kg bw per day in females
when expressed as steviol.
In another study conducted to OECD guidelines in accordance with GLP,
rebaudioside A (purity 99.5%) was fed in the diet to groups of 20 male and 20 female
Sprague-Dawley rats to produce target doses of 500, 1000 or 2000 mg/kg bw per
day for 13 weeks. Dietary concentrations covered the ranges of 5000–10 000,
10 000–19 000 and 19 000–36 000 mg/kg, respectively, and were adjusted weekly
to achieve the target dose. Body weights and food consumption were recorded
weekly, a functional observational battery and locomotor activity data were recorded
during week 12 and blood samples were collected for haematology and
serum chemistry during weeks 2 and 5. At termination, samples were taken for
haematology, serum chemistry and urinalysis. Complete necropsies were performed,
selected organs were weighed and selected tissues were examined
microscopically from all animals in the control and high-dose groups. Decreased
body weight gain was noted in males at the top dose of 2000 mg/kg bw per day,
which the authors concluded was due to the lower caloric value of the diet. There
were no other treatment-related observations. The NOEL was 2000 mg/kg bw per
day (Nikiforov & Eapen, 2008).
A number of other studies were available on steviol-related material of
unspecified composition, for which the administered dose of steviol could not be
identified (Lee et al., 1979; Toskulkao et al., 1994a; Wood et al., 1996).