Safety evaluation of certain food additives - ipcs inchem

400 ALKOXY-SUBSTITUTED ALLYLBENZENES
In a multipart study evaluating the carcinogenic potential of alkoxysubstituted
allylbenzenes, groups of 24–39 CD-1 female mice (mean weight 24 g)
were maintained on diets containing 2500 or 5000 mg safrole/kg. The authors
estimated that the dietary levels corresponded to average daily intakes of safrole of
150–300 and 300–600 mg/kg bw for animals on the 2500 and 5000 mg/kg diet,
respectively. To avoid intolerance, the dietary concentration was reduced by 75%
for the first 10 days and 50% for the next 10 days. The target diet was then
maintained for 12 months. Survival at 20 months was slightly lower for safrole-fed
(53%) animals compared with control animals (78%). Body weights measured at 1,
4 and 8 months were markedly reduced at 4 and 8 months compared with controls.
At 10 months, the incidence of hepatomas was 72% for animals on the 2500 mg
safrole/kg diet and 80% for animals on the 5000 mg safrole/kg diet, and 0% in
controls. Histopathological examinations revealed portal fibrosis, chronic
inflammation and bile duct proliferation in addition to the tumours. Varied numbers
of ceroid-laden histiocytes and focal areas of hyperplasia and megalocytosis were
also reported (Miller et al., 1983).
In another part of the study, male (55) and female (49) CD-1 mice were
administered 370 mg/kg bw of safrole by gavage twice a week for 10 doses
beginning at 4 days of age. The mice were weaned at 35 days of age. For safroletreated
mice, 62% of the males exhibited hepatomas (3.0 hepatomas per mouse).
The incidence of hepatomas in females for safrole (12%, 0.2 hepatoma per mouse)
was not statistically different from control females (2%, 0.02 hepatoma per
mouse) (Miller et al., 1983).
Groups of 36–40 male B6C3F1 mice were given single intraperitoneal
injections of 1-hydroxysafrole at 0.1 μmol/g (15 mg/kg bw) 12 days after birth.
Animals were sacrificed after 12 months, and incidences of hepatic tumours were
measured. A second group of males was given a lower dose of 0.01 μmol/g
(1.5 mg/kg bw). A statistically significant increase in the incidence of hepatomas per
mouse was observed at 0.1 μmol 1-hydroxysafrole/g, but no significant increase
was observed at the low dose of 0.01 μmol/g (Wiseman et al., 1987).
Groups of 50 male and 50 female CD-1 mice were injected intraperitoneally
with a total dose per mouse of 9.45 μmol of safrole or its related metabolites
1-hydroxysafrole, 1-hydroxysafrole-2,3-epoxide, safrole-2,3-oxide and 1acetoxysafrole-2,3-oxide
distributed in a ratio of 1:2:4:8 ml increasing doses with
age on postnatal days 1, 8, 15 and 22 of life, respectively. These doses correspond
to 0.63, 1.26, 2.52 and 5.04 μmol per mouse, respectively. The mice were weaned
at 22 days of age. A vehicle control group (trioctanoin) and an untreated group were
also included in the study. All mice were sacrificed at 12 months of age. Increased
incidences of hepatocellular carcinomas were observed for mice treated with
safrole (32/48, P < 0.001), safrole-2,3-epoxide (30/46, P < 0.001) and 1hydroxysafrole-2,3-epoxide
(28/51, P < 0.05), relative to the incidence for the
vehicle controls (11/42). The incidence of hepatocellular carcinomas for mice
treated with 1-hydroxysafrole was greater than that for safrole, suggesting that the
1-hydroxy metabolite is the proximate carcinogen (Miller et al., 1983).