2,4-di-tert-butylphenyl 3,5-di-tert-butyl-4-hydroxybenzoate

Endpoint summary

Description of key information

In two subchronic feeding studies with rats and beagle dogs the test item showed no adverse effects. The NOAEL was 691 mg/kg bw/d (male) and 704 mg/kg bw/d (female) during the 90 day study with beagle dogs. In the subchronic study with rats the NOAEL was determined to be 1687 mg/kg bw/d (male/female).

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records

Reference

Reference 1

Endpoint:

sub-chronic toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 409 (Repeated Dose 90-Day Oral Toxicity Study in Non-Rodents)

Version / remarks:

1998

Deviations:

no

GLP compliance:

no

Limit test:

no

Species:

dog

Strain:

Beagle

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Olac (Western) Limited
- Age at study initiation: 30 weeks (mean)
- Weight at study initiation: 9805 g (mean)
- Housing: All dogs were housed singly in kennels at Alconbury.
- Diet: The dogs were fed throughout with a complete dry diet (Spratt's Dog Diet). The diet is normally obtained in expanded pellet form, but as the test compound had to be introduced into the diet, a finely ground form of meal was obtained, made to the same standard as the pelleted diet. Each dog was offered 400 grams daily. When new food was offered in the morning, the residue from the previous day was removed and weighed. From these residual weights food intake was calculated. It was, therefore, possible for each animal to consume a maximum of 2800 grams of dry diet per week. Supplements of milk (approximately 200 mL) were offered to each animal on weekdays only throughout the experiment.
- Water: Water was freely available in the kennels at all times

Route of administration:

oral: feed

Vehicle:

other: ground diet

Details on oral exposure:

PREPARATION OF DOSING SOLUTIONS: 920 grams of test material were weighed out weekly and thoroughly mixed with 3680 grams of powdered diet to give 4.6 kg of premix containing 200000 ppm. The diets for the three dosage groups were obtained by serial dilution of this premix with more ground diet.

DIET PREPARATION
- Mixing appropriate amounts with: Dry diet (Spratt's Dog Diet)

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Samples of the diets fed to the dogs have been analysed for their content of the test item by spectrophotometry. The relative reproducibility of the method is +/- 10%. Within the limits of error of the sampling technique and of the analytical method there was good correspondence between the concentrations found in the diets and the nominal values.

Duration of treatment / exposure:

13 weeks

Frequency of treatment:

Daily

Dose / conc.:

5 000 ppm

Remarks:

corresponding to 171 mg/kg and 187 mg/kg in males and fermales, respectively

Dose / conc.:

10 000 ppm

Remarks:

corresponding to 340 mg/kg and 399 mg/kg in males and fermales, respectively

Dose / conc.:

20 000 ppm

Remarks:

corresponding to 690 mg/kg and 704 mg/kg in males and fermales, respectively

No. of animals per sex per dose:

Group 4 (High dose level): 5 males and 5 females
Group 2+3 (Intermediate dose level): Each group 4 males and 4 females
Group 1 (Controls): 6 males and 6 females

Control animals:

yes, concurrent no treatment

Details on study design:

- Post-exposure recovery period: 4 weeks (1 male and 1 female - High dose level, 2 males and 2 females - Control)

Observations and examinations performed and frequency:

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Daily

BODY WEIGHT: Yes
- Time schedule for examinations: weekly

FOOD CONSUMPTION AND COMPOUND INTAKE :
- Food consumption for each animal determined and mean daily diet consumption in mg/kg/day: Yes

WATER CONSUMPTION AND COMPOUND INTAKE: Yes
- Time schedule for examinations: 5 days

OPHTHALMOSCOPIC EXAMINATION: Yes
- Time schedule for examinations: Once before dietary intake and after 4, 8 and 12 weeks of dietary intake

HAEMATOLOGY: Yes
- Time schedule for collection of blood: once before dietary intake commenced
after 4 weeks of dietary intake
after 8 weeks of dietary Intake
after 12 weeks of dietary intake
- Investigations were performed on all dogs. Samples of blood were obtained prior to feeding on the day of examination with the animals in a fasting
condition, food having been removed from the kennels approximately 16 hours previously.
- Following parameters were checked: Erythrocyte sedimentation rate, packed cell volume, haemoglobin, red cell count, reticulocyte count, Absolute indices: Mean corpuscular haemoglobin concentration, total white cell count, differential count, platelet count - direct visual count, prothrombin index

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: once before dietary intake commenced, after 4 weeks of dietary intake, after 8 weeks of dietary Intake, after 12 weeks of dietary intake
- Fasting: Yes: food have been removed from the kennels approximately 16 hours previously.
- The following parameters were checked: Plasma urea, plasma Glucose, Total serum proteins, serum protein electrophoresis and AG ratio, Serum alkaline phosphatase, Serum glutamic - pyruvic transaminase, serum glutamic oxaloacetic transaminase, Serum Bilirubin, Serum cholesterol, Electrolytes: Sodium and Potassium

URINALYSIS: Yes
The urine specimens collected for routine studies include an assessment of concentrating power of the kidneys. Since urine passed overnight is more consistent in its constitution, samples collected over this period are considered to be more indicative of basic renal function than specimens passed during the daytime. For this reason, therefore, the procedure adopted in collecting urine specimens was to withdraw the supply of drinking water for the animals at midday, but delay the collection of urine until about 5 p.m. All urine passed between 5 p.m. and 9 a.m. the following morning was collected in suitable containers and the whole specimen was analysed.

Sacrifice and pathology:

GROSS PATHOLOGY: Yes
HISTOPATHOLOGY: Yes

On completion of the dosing period or subsequent observation period each animal received on Intravenous injection of sodium pentobarbitone and, when deeply unconscious, was rapidly exsanguinated by incision of the carotid blood vessels. Immediately afterwards a full macroscopic examination of the tissues was performed during which the following organs were removed and weighed:

Brain
Pituitary
Heart
Lungs
Liver
Spleen
Pancreas
Thymus
Prostate/Uterus
Kidneys
Thyroids
Adrenals
Gonads (including epididymis)

Small portions of these tissues together with pieces of: aorta (arch and abdominal), trachea, lymph nodes (cervical and mesenteric), gall bladder, urinary bladder, salivary gland, tongue, oesophagus, stomach, ducxienum, jejunum, ileum, colon, skin, mammary gland, skeletal muscle, bone marrow, peripheral nerve, eye and optic nerve and spinal cord were then placed In fixative.

Statistics:

Whenever it was necessary to determine whether significant differences existed between mean values relating to test and control animals, the method used was analysis of variance followed by Student's ' t ' test, the results being expressed as the 'least significant difference' (LSD), that is, the least difference that had to exist between mean values for dosed and control animals for significance at specified levels of probability.
The only other statistical procedure adopted was that used to describe the range of results obtained during the pre-dosing investigation. These results have been described by the grand mean and the "95% range", the latter phrase being used to describe the mean - ('t' x standard deviation).

Clinical signs:

no effects observed

Description (incidence and severity):

One dog (20000 ppm) passed liquid faeces containing mucus, and possibly blood on day 29 of dietary Intake. However, a sample sent for examination gave a negative result to the test for occult blood (Modification of Ortho-toluidine technique). Another dog (20000 ppm) showed a sudden and complete loss of appetite on days 29 and 30 of dietary intake. Green, liquid faeces and vomitus were observed in the kennel on both days. On day 31 the animal passed red coloured urine and a slight purulent discharge from the vulva was noted. However, most of the food offered was consumed on this day. No other signs were observed during the dosing or observation periods.

Mortality:

no mortality observed

Body weight and weight changes:

no effects observed

Description (incidence and severity):

Most dogs were gaining weight satisfactorily before dosing commenced. One dog lost weight during the final pre-dosing week and showed erratic weight changes subsequently.
Inspection of the group mean bodyweight shows that weight gain was similar for all groups. It may be concluded therefore, that there was no adverse effect on bodyweight that could be related to administration of the test compound. Bodyweight remained satisfactory during the subsequent observation period for all dogs.

Food consumption and compound intake (if feeding study):

no effects observed

Description (incidence and severity):

With the onset of dietary Intake and throughout the dosing period food consumption remained satisfactory for all dogs (except for a short period with one dog). It may be concluded that dietary intake of the test substance up to a level of 20000 ppm had no effect on appetite. Appetite remained satisfactory for those dogs maintained for observation study.

Food efficiency:

not examined

Water consumption and compound intake (if drinking water study):

no effects observed

Description (incidence and severity):

During weeks 1-4 and 9-12 water consumption remained comparable for all groups, and it was concluded that dosage with the test compound produced no adverse effect on water consumption.

Ophthalmological findings:

no effects observed

Description (incidence and severity):

No abnormalities were detected that could be related to dietary intake of the test item.

Haematological findings:

no effects observed

Description (incidence and severity):

All finding were considered to be within normal limits.

Clinical biochemistry findings:

no effects observed

Description (incidence and severity):

One dogs of the high dose group and one dog of the intermediate dose group had plasma glucose levels which just exceeded or equalled our accepted upper limit of 110 mg%. All finding were considered to be within normal limits.

Urinalysis findings:

no effects observed

Description (incidence and severity):

All results were within normal limits and all dogs were showing satisfactory urinary concentration.

Behaviour (functional findings):

not examined

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Description (incidence and severity):

The uterus weights for 4 dogs (20000 ppm) were considered normal for dogs undergoing oestral changes.
When expressed either In grams or as a percentage of bodyweight and brain weight, it was possible to show that the mean spleen weights for dogs receiving 10000 ppm or 20000 ppm were significantly greater than the control value. However, the individual values for these groups were well within normal limits for animals of this age, whilst the control values tended to be lower than usual.
All other organ weights were considered to be within normal limits.

Gross pathological findings:

no effects observed

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

no effects observed

Description (incidence and severity):

No morphological change or variation from normal was seen In any of the tissues examined that was considered to be related to treatment.

Histopathological findings: neoplastic:

not examined

Other effects:

no effects observed

Key result

Dose descriptor:

NOAEL

Effect level:

690 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male

Basis for effect level:

other: No mortality or other symptoms occurred during the study.

Key result

Dose descriptor:

NOAEL

Effect level:

704 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

female

Basis for effect level:

other: No mortality or other symptoms occurred during the study.

Key result

Critical effects observed:

no

Reference 2

Endpoint:

sub-chronic toxicity: oral

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 408 (Repeated Dose 90-Day Oral Toxicity Study in Rodents)

Version / remarks:

1998

Deviations:

no

GLP compliance:

no

Limit test:

no

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Geigy pharmaceuticals, Stamford Lodge, England
- Weight at study initiation: Individual mean body weights of 94 g (Male) and 79 g (female)
- Housing: Caged in groups of 5
- Diet: Powdered diet was mixed with dry extract of malt (Diamalt C) in the ration of 85 % food to 15 % malt extract by weight.
- Water: Water was available at all times

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21 +/- 2
- Humidity (%): 50 (+/- 10)

Route of administration:

oral: feed

Vehicle:

other: Diet

Details on oral exposure:

PREPARATION OF DOSING SOLUTIONS:
A small premix consisting of powdered diet and compound at the appropriate levels was prepared for each dose level. The premix was then thoroughly mixed with the larger amount of powdered diet/malt extract to produce the correct dosage levels. 15% water was added and the mixture passed through a mincer. The pellets so produced were dried for approximately 12 hours at a temperature not exceeding 45°C.

DIET PREPARATION
- Rate of preparation of diet (frequency): weekly

CONTROLS
- Control animals received diet prepared in the same manner but without the addition of the test item.

Analytical verification of doses or concentrations:

no

Duration of treatment / exposure:

13 weeks

Frequency of treatment:

daily

Dose / conc.:

2 000 ppm

Remarks:

equivalent to 167.5 mg/kg bw/d

Dose / conc.:

6 000 ppm

Remarks:

equivalent to 493.5 mg/kg bw/d

Dose / conc.:

20 000 ppm

Remarks:

equivalent to 1687 mg/kg bw/d

No. of animals per sex per dose:

30 rats (15 femals and 15 males)

Control animals:

yes, plain diet

Positive control:

none

Observations and examinations performed and frequency:

BODY WEIGHT: Yes
- Time schedule for examinations: weekly

FOOD CONSUMPTION
- Time schedule for examinations: weekly

OPHTHALMOSCOPIC EXAMINATION: Yes
- Time schedule for examinations: weeks 5, 8 and 12 of the test.
- Dose groups that were examined: 20 rats (10 females and 10 males) in group 1 and 4 during weeks 5, 8 and 12 of the test.

HAEMATOLOGY: Yes
- Time schedule for collection of blood: week 5, 9 and 13
- Animals fasted: No
- How many animals: all animals
- Parameters checked: Haemoglobin, Erythrocytes, Packed cell volume, Neutrophils, Lymphocytes, Eosinophils, Basophils, Monocytes, Prothrombin time, Erythrocyte sedimentation rate

- CLINICAL CHEMISTRY: Yes
- Time schedule for examinations: weeks 5, 8 and 13
- Parameters checked: Glucose, Urea

URINALYSIS: Yes
- Time schedule for collection of urine: weeks 5, 9 and 13.
- In order to obtain fresh urine, rats were dosed with water at a rate of 25 mL/kg body weight prior to introduction into metabolism cages.

Sacrifice and pathology:

ORGAN WEIGHT: Yes
- After macroscopic examinations
- Organs: Brain, Gonads, Heart, Kidneys, Liver, Spleen

GROSS PATHOLOGY: Yes

HISTOPATHOLOGY: Yes
In groups 1 (control) and 4 (20,000 p.p.m.) the following organs were examined:
Adrenals, Brain, Heart, Liver, Muscle, Peripheral nerve, Small intestine, Testis/ovary, Urinary bladder, Aorta, Eye, Kidneys, Lungs, Pancreas, Pituitary, Spleen, Thumus, Bone marrow, Gross lesions, Large intestine, ,Lymph nodes (axillary & mesenteric), Prostate/uterus, Stomach, Thyroids
As no compound-induced lesions were seen in group 4, organs from groups 2 and 3 were not examined, apart from gross lesions. Brains and spinal cords were fixed in 10 per cent neutral formalin, bone marrow in Zenker formol and all other tissues in Bouin's fluid. Paraffin sections were cut at 5-7 p and stained with haematoxylin and eosin. In addition, thin blocks of liver were fixed in Rossman's fluid and stained by the PAS technique to show glycogen. Frozen sections of liver and kidney were stained with Sudan IU in propylene glycol to show fat. Sections were exained from Groups 1 and 4 only.

Other examinations:

Quality control: The following quality control systems were regularly used in the haematology and clinical chemistry laboratories. Hyland Q-Pak , Boehringer (Mannheim) Precinorm E, Burroughs Wellcome Horse Serum.Samples of diet/compound mixes were submitted for analysis to the laboratories of CIBA-GEIGY Basle, Switzerland, at monthly intervals.

Statistics:

Where relevant, data from haematology, clinical chemistry, body weight gains, food consumption and organ weights were evaluated statistically using the student t-test. A level of P < 0.05 was accepted as significant.

Clinical signs:

no effects observed

Description (incidence and severity):

No clinical symptoms were recorded.

Mortality:

no mortality observed

Body weight and weight changes:

no effects observed

Description (incidence and severity):

No significant differences between treated groups and controls occurred in respect of body weights. There was a statistically significant increase in food consumption in male animals in group 3 (P < 0.05). This increase was small and the total food consumed by this subgroup was within normal limits, therefore this finding was not considered to be of any practical importance.

Food consumption and compound intake (if feeding study):

no effects observed

Description (incidence and severity):

There was a statistically significant increase in food consumption in male animals in group 3 (P < 0.05). This increase was small and the total food consumed by this subgroup was within normal limits, therefore this finding was not considered to be of any practical importance.

Food efficiency:

not examined

Water consumption and compound intake (if drinking water study):

not examined

Ophthalmological findings:

no effects observed

Description (incidence and severity):

Eyes were of normal appearance on ophthalmic examination.

Haematological findings:

no effects observed

Clinical biochemistry findings:

no effects observed

Description (incidence and severity):

All haematology and clinical chemistry parameters were within normal limits and no significant differences between treated groups and controls were seen.

Urinalysis findings:

no effects observed

Description (incidence and severity):

Urine anlysis revealed no abnormalities.

Behaviour (functional findings):

not examined

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Description (incidence and severity):

Organ weights (both absolute and relative) were comparable in all groups.

Gross pathological findings:

no effects observed

Description (incidence and severity):

Neither at autopsy nor on histological examination were any lesions referable to the administration of the test item seen. Organ weights (both absolute and relative) were comparable in all groups.

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

no effects observed

Histopathological findings: neoplastic:

not examined

Other effects:

no effects observed

Key result

Dose descriptor:

NOAEL

Effect level:

1 687 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: No mortality or other symptoms occurred during the study.

Key result

Critical effects observed:

no

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

691 mg/kg bw/day

Study duration:

subchronic

Species:

dog

Quality of whole database:

Guideline study, no effect levels

Repeated dose toxicity: inhalation - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: inhalation - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: dermal - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: dermal - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

In a 13 week study the test item was administered in the diet to groups of pure-bred Beagle dogs. at dose levels of 5000, 10000 and 20000 ppm, corresponding to a calculated average substance intake of 171, 340 and 690 mg/kg body weight in males and 187, 399 and 704 mg/kg body weight in females. After completion of the treatment period, 2 males and 2 females from the control and 1 male and 1 female from the high dose group were maintained on untreated diet for a four week recovery period. No deaths were observed and no adverse effects were observed regarding bodyweight and food consumption. All hematological and clinical chemistry parameters were within normal limits and no significant differences between treated groups and controls were seen. Urine analysis revealed no abnormalities. Eyes were of normal appearance on ophthalmic examination. Neither at autopsy nor on histological examination were any lesions referable to the administration of test item seen. The NOAEL was determined at 20000 ppm, corresponding to 690 mg/kg in males and 704 mg/kg in females.

In a second subchronic feeding study the test item was administered to rats mixed in the diet at levels of 0, 2000, 6000 and 20000 ppm. These dose levels correspond to a calculated average substance intake of 165, 491 and 1683 mg/kg in females and 170, 796 and 1696 mg/kg for males. No deaths occurred during the test period. No clinical symptoms were recorded. No significant differences between treated groups and controls occurred in respect of body weights. There was a statistically significant increase in food consumption in male animals in group 3 (6000 ppm). This increase was small and the total food consumed by this subgroup was within normal limits, therefore this finding was not considered to be of any practical importance. All hematology and clinical chemistry parameters were within normal limits and no significant differences between treated groups and controls were seen. Urine analysis revealed no abnormalities. Eyes were of normal appearance on ophthalmic examination. Neither at autopsy nor on histological examination were any lesions referable to the administration of test item seen. Organ weights (both absolute and relative) were comparable in all groups. In the subchronic study with rats the NOAEL was determined to be 1687 mg/kg body weight (male/female average).

Furthermore, no signs of toxicological relevance were obtained in a range finding study in dogs and a subacute study in rats.

Justification for classification or non-classification

Classification, Labelling, and Packaging Regulation (EC) No 1272/2008

The available experimental test data are reliable and suitable for classification purposes under Regulation 1272/2008 (CLP). As a result the substance is not considered to be classified for repeated dose toxicity under Regulation (EC) No 1272/2008, as amended for the eighth time in Regulation (EU) No 2016/218.