zinc, 5,5'-azobis-2,4,6(1H,3H,5H)-pyrimidinetrione complexes and melamine

Endpoint summary

Description of key information

In a subacute oral toxicity study in male and female rats with doses up to and including 1000 mg/kg bw/day no adverse effects were observed. Thus, the NOAEL is 1000 mg/kg bw/day.

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records

Reference

Endpoint:

short-term repeated dose toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline study under GLP condition

Qualifier:

according to guideline

Guideline:

OECD Guideline 407 (Repeated Dose 28-Day Oral Toxicity Study in Rodents)

Deviations:

yes

Remarks:

additional control rats and additional rats dosed with 1000 mg/kg bw/day serving as recovery group because they were maintained after termination of treatment for 14 days

GLP compliance:

yes

Species:

rat

Strain:

Crj: CD(SD)

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Age at study initiation: 5 week
- Weight at study initiation:
males: 115.0 - 128.9 g
females: 85.6 - 109.8 g
- Fasting period before study:
- Housing: individually
- Diet ad libitum
- Water ad libitum
- Acclimation period:

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22
- Humidity (%): 50
- Air changes (per hr): 10 - 15
- Photoperiod (hrs dark / hrs light): 12 / 12

Route of administration:

oral: gavage

Vehicle:

other: 0.5 % carboxymethylcellulose

Details on oral exposure:

Azo zinc complex pigment melamine compound was given to male and fenale rats by gavage in doses. of 0, 100, 330, or 1000 mf/kg bw/day suspended in 0.5 % carboxymethylcellulose over a period of 28 days. For the vehicle control as well as for the high dose group extra 5 aminmals per sex were used as recovery group.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

The stability and homogenicity of prepared test suspensions were confirmed by the concentration analysis validation and stability test;
tge suspension is stable for 7 days in the refrigerator and of good homogenicity.

Duration of treatment / exposure:

28 days

Frequency of treatment:

daily

Remarks:

Doses / Concentrations:
0, 100, 330, 1000 mg/kg bw/day
Basis:

No. of animals per sex per dose:

5

Control animals:

yes, concurrent vehicle

Details on study design:

Azo zinc complex pigment melamine compound was given to male and fenale rats by gavage in doses. of 0, 100, 330, or 1000 mf/kg bw/day suspended in 0.5 % carboxymethylcellulose over a period of 28 days. For the vehicle control as well as for the high dose group extra 5 aminmals per sex were used as recovery group.
--Clinical signs were reported once a day
--Body weight, food consumption, detailed clinical observations, observations of open field were recorded weekly
--urine analysis, ophthalmology, sensory reactivity, grip strength and motor activity were examined in the last week, i.e. week 4, of administration period
--Hematology and blood biochemistry was evaluated at the end of the administration period
Recovery group:
--Motor activity, hematology, blood biochemistry at the end of recovery period

--Gross necropsy, organ weight, and histopathology was evaluated at the end of the administration period
Recovery group
--necdropy , organ weight were also examined at the end of recovery period

Positive control:

no

Observations and examinations performed and frequency:

--Clinical signs were reported once a day
--Body weight, food consumption, detailed clinical observations, observations of open field were recorded weekly
--urine analysis, ophthalmology, sensory reactivity, grip strength and motor activity were examined in the last week, i.e. week 4, of administrationperiod
--Hematology and blood biochemistra was evaluated at the end of the administration period
Recovery group:
--Motor activity, hematologym blood biochemistry at the end of recovery period

Sacrifice and pathology:

--Gross necropsy, organ weight, and histopathology was evaluated at the end of the administration period
Recovery group
--necdropy , organ weight were also examined at the end of recovery period

Statistics:

Levene's test, One Way ANOVA analysis, Scheffe's multiple comparison test, Dunnett's T3 test, F test, Student t-test, Mann.whitney test

Details on results:

No compound related adverse effects were observed on
-- mortality and clinical signs
Evidence of coompound colored feces was noted for all dosaage group animals during the administeration period indicating that the test substance is excreted directly via feces without relevant systemic absorption. Referring to recovery group: this finding disappeared and rats recovered to normal within the 14 day period Therefore this finding is regarded to be test substance related but not as an adverse effect

No compound related adverse effects were observed on
--detailed clinical observations: behavior
--sensory reactivity assessment and grip strength
--.motor activity
Statistically significant decrease (p<0.01) was observed at the time of 50-60 min in all males of the administration group
In females of the recovery group statistically significant increase (p<0.05) was observed at the times of 10-20 and 20-30 min
These sporadic statistically significant observations at a few time intervals were not dose related and/or not consistent over time and , consequently,
not considered to be compound related

No compound related adverse effects were observed on
--body weight
--food consumption
--urine analysis
--ophthalmology
--hematological analysis
in the test animals no statistically significant difference to the control group
recovery group:
males: Platelet count (PLT) was statistically significant decreased (p<0.05) and protrombin time (PT) increased (p<0.05)
females: Monocytes percentage was statisticlaly increased (p<0.05)
As these observations were seen only in the recovery animals these observations were not regarded to be compound related
--blood biochemical analysis
in test males dosed with 1000 mg/kg bw aspartate aminotransferases (AST) was statistically significant decreased (p<0.05)
These observations were not considerd to be compound related because the observations were not dose related an/or different in different genders and not in recovery males.

No compound related adverse effects were observed at necropsy
--gross pathological evaluation
--organ weights:
-absolute organ weights
in test groups there were no adverse findings
recovery group, males thyroid gland significantly decreased (p<0.01); females no findings
-relative organ weights
in test groups no adverse findings
recovery group, males, kidneys significantly increased (p<0.05) , thyroid gland significantly decreased (p<0.01)
Since these observations were not dose dependent and/or not consistent over gender and/or only observed in recovery group they were not considered to be compound related
--no test substance related histopatholoical lesions were observed in the high dose group

Dose descriptor:

NOAEL

Effect level:

1 000 mg/kg bw/day (actual dose received)

Sex:

male/female

Basis for effect level:

other: treatment related adverse effects were not observed

Critical effects observed:

not specified

Executive summary:

This study was performed to investigate the systemic toxicity on male and female rats followed 28 consecutive days repeated oral dosing of Azo zinc complex pigment - melamine compound via gavage at dose levels of 0, 100, 330, and 1000 mg/kg bw/day suspended in 0.5% carboxy methylcellulose. The study was conducted in compliance wtih OECD TG 407 under GLP conditions. In addition recovery groups (0 and 1000 mg/kg bw/day) were maintained without dosing for a further 14 days after administration period to evaluate the reversibility of any potential effects.

No animal died during the treatment period and in the recovery period thereafter. Azo zinc complex pigment - melamine compound was well tolerated. The evidence of compound colored feces was noted in all dosage groups during administration period but disappeared during recovery period. This observation indicated that absorption of Azo zinc complex pigment - melamine compound is limited. No

treatment related adverse effects could be determined during hematological and blood biochemical analysis or gross and histopathological examinations. Therefore, the NOAEL of Azo zinc complex pigment - Melamine compound is considered to be 1000 mg/kg bw/day

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

1 000 mg/kg bw/day

Study duration:

subacute

Species:

rat

Quality of whole database:

This is the only subacute study in rats which is performed according to OECD TG 407 under GLP conditions. Additionally a recovery group was added to determine the reversibility of possible effects

Additional information

This study was performed to investigate the systemic toxicity on male and female rats followed 28 consecutive days repeated oral dosing of Azo zinc complexpigment - melamine compound via gavage at dose levels of 0, 100, 330, and 1000 mg/kg bw/day suspended in 0.5% carboxy methylcellulose. Recovery groups (0 and 1000 mg/kg bw/day) were maintained without dosing for a further 14 days after administration period to evaluate the reversibility of any potential effects. The study was conducted in compliance with OECD TG 407 under GLP conditions.

No animal died during the treatment period and in the recovery period thereafter. Azo zinc complexpigment - melamine compound was well tolerated. The evidence of compound colored feces was noted in all dosage groups during administration period but disappeared during recovery period. This observation indicated that absorption of Azo zinc complexpigment - melamine compound is limited. No

treatment related adverse effects could be determined during hematological and blood biochemical analysis or gross and histopathological examinations. Therefore, the NOAEL of Azo zinc complex pigment - Melamine compound is considered to be 1000 mg/kg bw/day.

Justification for selection of repeated dose toxicity via oral route - systemic effects endpoint:
This is the only subacute study in rats which is performed according to OECD TG 407 under GLP conditions. Additionally a recovery group was added to determine the reversibility of possible effects. Therefore this study was evaluated with Klimisch score 1

Justification for classification or non-classification

Based on the available results from the sub-acute oral study in rats, no classification or labelling is required.