Safety evaluation of certain food additives - ipcs inchem

392 ALKOXY-SUBSTITUTED ALLYLBENZENES
2.2.3 Long-term studies of toxicity and carcinogenicity
The results of long-term studies of toxicity and carcinogenicity of methoxyand
methylenedioxy-substituted allylbenzenes are summarized in Table 3.
(a) Estragole (No. 1789)
(i) Mice
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 2300 or 4600 mg estragole/kg or 2500 mg 1hydroxyestragole/kg.
The authors estimated that the dietary levels corresponded to
average daily intakes of 150–300 and 300–600 mg/kg bw for animals on the 2300
and 4600 mg estragole/kg diet, respectively, and 180–360 mg/kg bw for animals on
the 1-hydroxyestragole diet. 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
estragole-fed (68–70%) animals compared with control animals (78%). The average
lifespan of mice given 1-hydroxyestragole was 13.6 months compared with 18
months in controls. 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 58% for animals on the 2300 mg estragole/kg diet, 71% for animals
on the 4600 mg estragole/kg diet, 56% for animals on the 2500 mg 1hydroxyestragole/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. Four mice fed 4600 mg
estragole/kg had hepatic angiosarcomas (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 estragole by gavage twice a week for 10 doses
beginning at 4 days of age. The mice were weaned at 35 days of age. Hepatomas
in estragole-treated mice were observed as early as 11 months. At 14 months, 73%
of the males (3.5 hepatomas per mouse) and 24% of control males (0.6 hepatomas
per mouse) exhibited hepatomas. The incidence of hepatomas in females for
estragole (9%, 0.1 hepatomas per mouse) was not statistically different from that in
control females (2%, 0.02 hepatomas per mouse) (Miller et al., 1983).
Sulfate-conjugated metabolites of 1-hydroxyestragole have been strongly
implicated as the major, ultimate electrophilic and carcinogenic metabolite of
estragole (section 2.1.2). Mice pretreated with pentachlorophenol, a potent SULT
inhibitor, were administered estragole or other allylbenzenes. Groups of 12-day-old
male B6C3F1 mice (18–59 animals per group) were divided into two separate
groups for each test compound. One group was given a single intraperitoneal
injection of the test compound. The other group was administered a single injection
of pentachlorophenol (0.04 mmol/kg bw) 45 min prior to administration of the test
compound. Separate groups of mice were injected with trioctanoin (vehicle) or
trioctanoin plus pentachlorophenol as controls. The first appearance of
hepatocellular carcinoma in the treated mice was at 9 months, and the experiment