Registration Dossier

Administrative data

Description of key information

NOAEL (rat, 28d, OECD 407) = 205 mg/kg bw/day, males
NOAEL (rat, 28d, OECD 407) = 1373 mg/kg bw/day, females

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Endpoint conclusion
Dose descriptor:
205 mg/kg bw/day
Study duration:

Additional information

An oral repeated dose toxicity study was performed with ethyl 3,5-dichloro-4- hexadecyloxycarbonyloxybenzoate (AF-366) according to OECD guideline 407, adopted in 1981 (Jonker and Lina, 1989). Rats (5/sex/dose) were administered 250, 1750 and 12250 ppm of the test substance daily by gavage for 28 days. This is equivalent to 31, 205 and 1419 mg/kg bw/day for males and 28, 199 and 1373 mg/kg bw/day for females, respectively.

There was no mortality during the study period. 2/5 males in the high-dose group had convulsions that lasted around 1 minute on 2 and 4 occasions during the study period, respectively. No clinical signs were observed in the females.

The body weight of males in the high-dose group was statistically significantly reduced (by approximately 10%) on Day 21 and 28, compared to the male control group on the same days, respectively. The two rats suffering from convulsions had a lower weight gain, compared with the rest of the animals in the group. The food consumption and food efficiency was comparable between the control and treatment groups during the study period.

In both male and female high-dose groups, a statistically significant decrease (approximately 25%) in the level of thrombocytes was observed, compared to the control group. As the reduction was notable and observed in both sexes, it is considered to be treatment-related. The mean corpuscular volume in males administered the highest dose were statistically significantly decreased. A statistically significant increase in neutrophil level (absolute and percentage) in high-dose males was also noted. The toxicological relevance of these effects is not clear. A statistically significant decrease in the hemoglobin value was noted in the high-dose group for both sexes, while the mean corpuscular haemoglobin value was reduced in the male high-dose group. However, the levels were within the historical data range and therefore not considered to be of toxicological significance (Technical Bulletin, Spring 1998. Charles River Laboratories, Wilmington, USA). Although the reticulocyte level in high-dose females was statistically significantly increased, the control level was very low compared to the treated groups, probably leading to an erroneous indication of a relevant increase. Also, no effect on the reticulocytes was seen in the males.

The levels of alkaline phosphatase were statistically significantly decreased in males and females in the mid- and high-dose groups in a dose-related manner. The effect is considered to be treatment-related, with toxicological significance only in the high-dose groups, as no other histopathological or clinical chemistry effects were observed at the mid-dose level. In females administered the highest dose, aspartate aminotransferase concentrations were decreased. The result was within the historical data range (Technical Bulletin, Spring 1998. Charles River Laboratories, Wilmington, USA), indicating the effects are not of toxicological relevance.

The relative liver weight of males and females in the high-dose group was statistically significantly increased. For the males, the effect is considered to be treatment-related and toxicologically relevant, considering the observed histopathological effects.

No other treatment-related effects were observed during necropsy and gross pathology. The microscopic examination showed an increased mitotic activity in the hepatocytes of 3/5 males in the high-dose group, while an increased focal accumulation of hepatic Kupffer cells in the sinusoids was noted in 4/5 high-dose males (statistically significant).

Based on the observed haematological and hepatic effects in males, the NOAEL for AF-366 is considered to be 1750 ppm, equivalent to 205 mg/kg bw/day, for male rats.

In females, the effects noted do not lead to the conclusion that AF-366 caused treatment-related adverse effects. The NOAEL is therefore considered to be 12250 ppm, equivalent to 1373 mg/kg bw/day, for female rats.

Repeated dose toxicity: via oral route - systemic effects (target organ) digestive: liver

Justification for classification or non-classification

The available data on repeated dose toxicity of the test substance do not meet the criteria for classification according to Regulation (EC) 1272/2008 or Directive 67/548/EEC, and are therefore conclusive but not sufficient for classification.