Safety evaluation of certain food additives - ipcs inchem

ALKOXY-SUBSTITUTED ALLYLBENZENES 401
(ii) Rat
As early as 1965, long-term studies in laboratory rodents indicated that
alkoxy-substituted allylbenzenes were hepatocarcinogenic when administered in
the diet, often at levels that caused liver and gastric damage. Groups (10 per sex
per dose) of male and female Osborne-Mendel rats were maintained on diets
containing 0 (control), 1000, 2500 or 5000 (25 male and 25 females) mg safrole/kg
daily for 2 years or 10 000 mg/kg for 62 weeks. The levels are calculated to provide
an average daily intake of approximately 0, 50, 125, 250 or 500 mg/kg bw,
respectively. Diets were prepared fresh weekly. Measurement of body weight
and food intake and observation of general condition were made weekly.
Haematological examinations were performed by 3, 6, 12 and 22 months and at
termination of the study. At the highest dietary level, all rats were dead at 62 weeks.
Measurement of body weight and food intake showed reduced body weight gain at
the three highest dose levels in males and females and in females provided the
50 mg/kg bw per day diet.
At the highest dose, livers were enlarged with mottling and irregular single
and multiple tumour masses. Microscopic examination revealed hepatocyte
enlargement and steatosis, nodules showing cystic necrosis, cirrhosis,
adenomatoid hyperplasia and hepatocellular adenomas and carcinomas. Other
findings included atrophy and atypical regeneration of the mucosal glands of the
stomach with associated fibrosis and hyalinization of the surrounding stroma.
Atrophy of the testes was also reported. At 250 mg/kg bw per day, there was
increased mortality in males. Liver changes were of the same type and severity as
in the 500 mg/kg bw per day group. A statistically significant increase in malignant
primary hepatic tumours was reported. Other effects included a slight increase in
chronic nephritis in females and mild hyperplasia of the thyroid in both sexes. At
125 mg/kg bw per day, moderate liver damage was reported without cirrhosis or
tumours. A moderate increase in the incidence of nephritis was reported. At the
50 mg/kg bw per day level, liver damage was slight. No malignant tumours or
cirrhosis was observed (Hagan et al., 1967).
In a related study, groups of 25 male and 25 female Osborne-Mendel rats
were maintained on diets containing safrole at concentrations of 0 (control), 100,
500, 1000 or 5000 mg/kg for 2 years. The levels were calculated to provide an
average daily intake of approximately 0, 5, 25, 50 or 100 mg/kg bw per day,
respectively. At the highest dose, reduced body weight gain was reported in both
sexes. Haematological examinations revealed mild anaemia and leukocytosis. At
dietary levels of 100 mg/kg bw per day (approximately equivalent to a lifetime body
burden of 70 000 mg/kg bw, i.e. 100 mg/kg bw × 700 days), there was a statistically
significant increase in benign and malignant neoplasms of the liver. At the 50 mg/
kg bw day level, there was slight to moderate liver damage, but no evidence of
malignant liver neoplasms or cirrhosis. At 5 and 25 mg/kg bw per day, there was no
evidence of malignant hepatocellular carcinomas or cirrhosis after 2 years (Long
et al., 1963).