Phenol, 2-[4-(4-ethoxyphenyl)-6-phenyl-1,3,5-triazin-2-yl]-

Endpoint summary

Description of key information

No adverse effects in subacute oral toxicity study up to highest dose tested.

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Endpoint conclusion

Dose descriptor:

NOAEL

1 000 mg/kg bw/day

Study duration:

subacute

Species:

rat

Additional information

The toxicity of Triazin UV-Absorber administered daily for at least 28 days by oral gavage to CRL:(WI)BR rats and the reversibility of any treatment-related changes was evaluated following a 14-day recovery period. In addition, the test item was evaluated for genotoxic effects by examiningthe induction ofmicronuclei in bone marrow erythrocytes of treated and control animals.

Triazin UV-Absorberor the vehicle/control only was administered to sixty Wistar rats (20 male and 20 female Main animals, and 10 male and 10 female Recovery animals)according to the following experimental design:

 

Group No.	Group Designation	Dose Level (mg/kg/day)	Conc. (mg/mL)	Dose volume (mL/kg)	Number of Animals
					Main		Recovery
					Male	Female	Male	Female
1	Control	0	0	4	5	5	5	5
2	Low Dose	62.5	15.6		5	5	-	-
3	Mid Dose	250	62.5		5	5	-	-
4	High Dose	1000	250		5	5	5	5
5	Positive Control^*	0	0	10	5	5	-	-

 

*MNT: 15 mg/kg bw/day Cyclophosphamide PO (10 mL/kg, 1.5 mg/mL) approximately 24 h prior to scheduled necropsy

 

Main animals underwent necropsy on Day 28 (start of treatment, Day 0), after 29 days of treatment. Recovery animals were treated for 28 consecutive days, they were euthanized and subjected to a necropsy examination following a 14-day recovery/observation period after the last dose. Control animals received the vehicle item solution only (PEG400), at the same volume as the high dose animals.

 

No correction for purity ofTriazin UV-Absorber was applied.

 

Ten additional Wistar rats (5 male and 5 female), Group 5, served as positive control group for the Mammalian Erythrocyte Micronucleus Test (MNT). They were treated with 15 mg/kg bw/day Cyclophosphamide by oral gavage (dose volume, 10 mL/kg, concentration, 1.5 mg/mL) on Day 27, approximately 24 h prior to scheduled necropsy on Day 28.

Parameters measured during the study includedinspection for signs of morbidity and mortality twice daily,observation of clinical signs, performed daily (general, cage side observations, after the dose administration), or weekly (detailed observations), as well as a modified Irwin test conducted on Day 26, weekly determination of body weight and body weight gain, and food consumption. Prior to necropsy, the oestrus cycle of all females was evaluated by examination of vaginal smears. In addition, blood was collected prior to terminal necropsy, for clinical pathology (haematology, coagulation and clinical chemistry) assessment. At termination, necropsy with macroscopic examination was performed. Weights of selected organs were recorded and representative tissues/organs were sampled and preserved in appropriate fixatives.  

Histopathology evaluation was conducted on tissues and organs retained in fixative and processed to slides from the control and high dose animals (1000 mg/kg bw/day), and on all organs with macroscopic findings from the low and mid dose groups (62.5 and 250 mg/kg bw/day, respectively).

 

Analysis of formulations (concentration, homogeneity) and assessment of test item stability in this vehicle in the conditions employed on the study was performed in the Analytical Laboratory of LAB Research Ltd. 

 

Stability tests (LAB study code 09/069-316AN) at concentrations from approximately 1 to 250 mg/mL in PEG 400 indicated an up to 24 hour stability at room temperature. In addition, under refrigerated conditions (5±3°C), the solutions were stable for up to 72 hours, with a recovery of 101% and 106%, at 1 and 250 mg/mL, respectively (acceptance range: 100 ± 10%). Concentration and homogeneity of formulations were evaluated by UV-HPLC method on duplicate samples collected from the top, middle and bottom of test item solutions, and one sample from the control, taken and analyzed fresh during the first and last weeks of treatment. Dose formulations were homogenous; the measured (actual) concentrations varied between 98% and 106% of the nominal concentrations.No test item was detected in the control solution samples.

These results were considered suitable for the study purposes.  

 

Triazin UV-Absorber caused neither test item related mortality, nor clinical changes following administration by oral gavage, daily for at least 28 days, at up to and including 1000 mg/kg bw/day in CRL:(WI)BR rats. All the animals were normal during the 14-day recovery period. One male at 1000 mg/kg bw/day died due to a dosing failure between Day 9 and Day 10. The behaviour and the general condition of the test animals were normal during the study. There was no treatment-related effect on motor activity or in the functional observation battery tests across groups of treated male or female animals and no findings indicative of neurotoxicity were observed. Evaluation of the vaginal smears prior to necropsy showed the expected distribution of the oestrus cycle phases within the normal population of female Wistar rats. There were no toxicologically significant changes in body weight, body weight gain or animal food consumption between the control and test item treated groups. 

 

Minor variations, on occasion attaining statistical significance, were noted in the clinical pathology parameters (haematology, coagulation, or clinical chemistry) in both main and recovery animals. However, no dose or gender-response was observed, and/or the results were within the historical range. These changes were neither considered toxicologically significant, nor indicated a Triazin UV-Absorber-related etiology.

 

There were no macroscopic or microscopic findings, or changes in the absolute or relative organ weights that could be ascribed to Triazin UV-Absorber-administration. No induction of micronuclei in bone marrow erythrocytes was observed, thus, there was no evidence of any genotoxic activity of the test item.

 

In conclusion, under the conditions of this study, the no observed effect level (NOEL) for Triazin UV-Absorber is considered to be 1000 mg/kg bw/day.

Justification for classification or non-classification

no classification necessary