Pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate)

Endpoint summary

Description of key information

Adequate repeated-dose toxicity studies predating GLP but performed similar to OECD guidelines 409 and 453 are available. A 3-month feeding study in beagle dogs revealed no relevant toxicological effects and a NOEL of 10000 ppm was derived. In a chronic feeding study in rats a NOEL of 3000 ppm was derived based on an intermittent reduction in body weight gain at the high dose level. Since the toxicological relevance of this finding is doubtful the NOAEL can be set at 10000 ppm.

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records

Reference

Endpoint:

chronic toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1975

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Remarks:

Feed analysis was performed, but no details for accuracy of preparation, homogeneity and stability were reported. Limited biochemical parameters measured. Non-GLP. Histopathological examinations as described in the summary were performed 10 years after the finalisation of the study. Lymphoid aggregates in the lungs reported in the first histopathology report were no longer reported in the second report.

Reason / purpose for cross-reference:

reference to same study

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 453 (Combined Chronic Toxicity / Carcinogenicity Studies)

Deviations:

yes

Remarks:

Urinalysis: missing volume and density. Blood chemistry: missing total protein; albumin, glutamic oxalacetic transaminase, g-glutamyl transpeptidase, and ornithine decarbossilase. Pathology: missing salivary glands, oesophagus, peripheral nerve, and stern

GLP compliance:

no

Limit test:

no

Species:

rat

Strain:

other: CFY, a hysterectomy-derived from Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Carworth Europe, England
- Weight at study initiation: 100 - 150 g (male); 73 - 132 g (female)
- Housing: 5 in suspended metal cages fitted with wire-mesh floors
- Diet (e.g. ad libitum): Ad libitum, Spratt's Laboratory Animals Diet No. 2.
- Water (e.g. ad libitum): Ad libitum
- Acclimation period: 7 d

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21 ± 2
- Humidity (%): 55 ± 5
- Photoperiod (hrs dark / hrs light): 12/12

Route of administration:

oral: feed

Vehicle:

unchanged (no vehicle)

Details on oral exposure:

PREPARATION OF DOSING SOLUTIONS:
A premix containing 60000 ppm test material was prepared each week, and from this the different dietary concentrations were obtained by direct dilution with further quantities of diet. Homogeneity was achieved by mixing for 10 m in a rotary double-cone blender; all diets were stored until use in heat-sealed opaque polythene bags.

DIET PREPARATION
- Rate of preparation of diet (frequency): Weekly
- Mixing appropriate amounts with (Type of food): Powdered Spratt's Laboratory Animals Diet No. 2
- Storage temperature of food: Room temperature

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Samples of the diet fed to the rats have been analysed for their content of test substance by a thin layer chromatographic method. The estimated relative reproducibility of this method is ± 10 % or better. 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:

2 years

Frequency of treatment:

Continuous

Dose / conc.:

1 000 ppm

Remarks:

corresponding to 45-55 mg/kg bw

Dose / conc.:

3 000 ppm

Remarks:

corresponding to 135-166 mg/kg bw

Dose / conc.:

10 000 ppm

Remarks:

corresponding to 446-547 mg/kg bw

No. of animals per sex per dose:

50

Control animals:

yes, plain diet

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: Daily
- Cage side observations checked: Mortality and all signs of ill-health and toxicity, and behavioural changes

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: All signs of ill-health and toxicity, together with any behavioural changes; skin lesions; cataracts or palpable growths; together with the progression or regression of such lesions. Any rat showing signs of severe debility or intoxication was isolated.

BODY WEIGHT: Yes
- Time schedule for examinations: Weekly for the first 12 weeks and at 4-week intervals thereafter

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study): Weekly
-The quantity of food consumed by each cage of rats was recorded and the mean weekly intake calculated

FOOD EFFICIENCY:
- Calculation of mean food conversion ratios (FCR values) during the period of fastest growth, a s weight of food consumed per unit gain in bodyweight.

OPHTHALMOSCOPIC EXAMINATION: Yes
- Time schedule for examinations: Before treatment commenced, and after 13, 26, 52, 75, and 102 w
- Dose groups that were examined: Groups 1 (Control) and 4 (I0000 ppm)

HAEMATOLOGY: Yes
- Time schedule for collection of blood: After 13, 26, 52, 78, and 103 w
- Anaesthetic used for blood collection: No data
- Animals fasted: No data
- How many animals: 10 males and 10 females from Groups 1 (Control) and 4 (I0000 ppm)
- Parameters checked: Packed cell volume (PCV); Haemoglobin (Hb); Red cell count (RBC); Mean corpuscular haemoglobin concentration (MCHC) and mean cell volume (MCV); Total white cell count (WBC); Differential count (Neutrophils, Lymphocytes, Eosinophils, Basophils, and Monocytes)

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: After 13, 26, 52, 78, and 103 w
- Animals fasted: Yes, overnight
- How many animals: 10 males and 10 females from Groups 1 (Control) and 4 (I0000 ppm)
- Parameters checked: Plasma Urea nitrogen; Plasma Glucose; Serum alkaline phosphatase (SAP); Serum glutamic-pyruvic transaminase (SGPT)

URINALYSIS: Yes
- Time schedule for collection of urine: After 13, 26, 52, 78, and 103 w
- Metabolism cages used for collection of urine: No data
- Animals fasted: No data
- Parameters checked: pH; Specific gravity (SG); Protein; Reducing substances; Glucose; Ketones; Bile pigments; Urobilin; Blood pigments; Microscopy of spun deposit

OTHER: On completion of the treatment period, all surviving rats were killed by carbon dioxide euthanasia and subjected to autopsy

Sacrifice and pathology:

GROSS PATHOLOGY: Yes (see below)
HISTOPATHOLOGY: Yes (see below)

Statistics:

Student's 't' test was employed to assess significance of intergroup differences where the data suggested a treatment-related response.
Differences in tumour incidence were compared by a 2 x 2 contingency test used as a one-tailed test, computing the exact probability of the observed tumour distribution occurring or one which is more extreme.

Clinical signs:

no effects observed

Description (incidence and severity):

There were no overt signs of reaction to treatment.

Mortality:

mortality observed, non-treatment-related

Description (incidence):

The survival rates among treated rats were comparable with those of the controls.
Mortality and time to death: 31/50, 26/50, 28/50 and 24/50 for males and 29/50, 30/50, 33/50 and 30/50 for females at 0, 1000, 3000 and 10000 ppm, respectively. No relationship between dose and time of death.

Body weight and weight changes:

effects observed, non-treatment-related

Description (incidence and severity):

During the first 24 weeks of treatment, bodyweight gain of treated rats was comparable with that of the controls. Between weeks 24 and 52, bodyweight gain of males receiving test material at 10000 ppm was significantly lower than that of the controls (P<0.05), although subsequent performance was comparable with that of the controls. Between weeks 80 and 104, bodyweight gain of males receiving 1000 ppm was significantly higher than that of the controls, although since this finding was not dose related in degree it is of doubtful biological significance. Bodyweight gains among other treated groups were not disturbed by dietary administration.

Food consumption and compound intake (if feeding study):

effects observed, non-treatment-related

Description (incidence and severity):

With the exception of a small decrease in the total mean food Intake among all treated rats between weeks 53 and 80, food Intake was not disturbed by treatment.

Food efficiency:

no effects observed

Description (incidence and severity):

No treatment-related change in the efficiency of food utilization was recorded during the period of fastest growth i.e. the first 24 weeks of treatment.

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

not examined

Ophthalmological findings:

no effects observed

Description (incidence and severity):

No changes attributable to treatment were observed

Haematological findings:

effects observed, non-treatment-related

Description (incidence and severity):

Although a small number of differences between controls and rats receiving 10000 ppm attained a level of statistical significance during the course of the study, all values obtained were within normal limits for the strain of rat employed. Therefore, it was concluded that treatment with the test item had no effect on the hematological parameters measured.

Clinical biochemistry findings:

effects observed, non-treatment-related

Description (incidence and severity):

At week 13, a decrease in the mean urea nitrogen level and an increase in the mean glucose level were recorded in male rats receiving the test item at 10000 ppm, although values for these parameters in females receiving a similar dosage level were comparable with those of the control females. However, the Individual values in treated male rats were within the 'normal' range for the age and strain of rat employed and the differences were not considered to be of biological significance. No intergroup differences, attributable to treatment, were recorded at week 26.
The marginal Increase in SAP and SGPT values at week 52 for female rats receiving 10000 ppm; the marginal Increase in the SGPT values In treated males at week 78, and the marginal decrease In the SAP values In treated males at week 103, although attaining a level of statistical significance were considered to be of no biological significance. It was concluded that treatment with the test item was without effect on the blood chemistry parameters measured.

Urinalysis findings:

effects observed, non-treatment-related

Description (incidence and severity):

No evidence of treatment-related change was seen in investigations made at weeks 13 and 26. Urinalysis carried out after 52 and 78 weeks of treatment revealed a small increase In the alkalinity of the urine excreted by male rats receiving the test item at 10000 ppm, although the values obtained were within the 'normal' range for the strain of rat employed. Values among female rats receiving 10000 ppm were comparable with those of the controls. No evidence of treatment-related change was seen in the Investigations made at week 103.

Behaviour (functional findings):

not examined

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

effects observed, non-treatment-related

Description (incidence and severity):

Organ weight analysis performed on rats killed after 104 weeks of treatment revealed no evidence of a treatment-related effect on organ weight. Although differences from control values in adrenal, thyroid and kidney weights attained levels of statistical significance, the differences were related to the intergroup disparity in bodyweight and were not dose related in degree. It was, therefore, concluded that the differences were of no toxicological significance and probably arose fortuitously.

Gross pathological findings:

no effects observed

Description (incidence and severity):

The prime cause of death among rats dying during the course of the study showed no relation to treatment. Macroscopic examination of decedents and rats killed after 104 weeks of treatment showed pathology which was common to animals from control and treated groups.

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

effects observed, non-treatment-related

Description (incidence and severity):

GENERAL HISTOPATHOLOGY OF DECEDENTS
- Lung
chronic respiratory disease, characterized by congestion, peribronchiolar and perivascular lymphoid aggregates or hyperplasia, and aggregates of alveolar macrophages, was common to a number of rats from control and treated groups. Bronchopneumonia was observed In rat 50♂ (Control) and interstitial pneumonitis In rats 11♂ (Control) and 131♂ 3000 ppm).

- Liver
Changes in the liver common to some rats from control and treated groups consisted of varying degrees of hepatocytlc vacuolation, occasional aggregates of chronic Inflammatory cells, focal areas of necrosis, minimal bile duct hyperplasia and minimal periportal fibrosis. A hyperplastic nodule was observed in rat 199♂ (10000 ppm).

- Kidney
Varying degrees of progressive glomerulonephrosis, characterised by cystically dilated nephrons, Interstitial fibrosis, lymphocytic infiltration and associated glomerular changes, were seen in the kidneys of the majority of rats from control and treated groups. A haematoma was observed in the kidney of rat 488♀ (3000ppm).

- Urinary bladder
Eosinophilic cases were observed in the urinary bladder of rats 25♂ (Control) and 82♂ (1000 ppm) and slight hyperplasia of the transitional epithelium of rat 135♂ (3000ppm).

- Cardiovascular svstem
A minor degree of myocarditis and myocardial fibrosis was seen in rats 4♂ and 385♀ (Control), 115♂ (3000ppm) and 173♂ (10000ppm), myocardial mineralization in rat 56♂ (1000ppm) and mineralization of the coronary arteries in rat 115♂ (3000ppm), an auricular thrombus in rat 438♀ (1000ppm), mineralization of the aortic media in rats 4♂, 18♂ (Control), 79♂ (1000ppm), 155♂ and 513♀ (1000ppm). Aneurysms with or without thrombus formation were observed in the blood vessels of rats 68♂, 70♂, 419♀ and 432♀ (1000ppm), 116♂ (3000ppm) and 186♂ (1000ppm) and an aneurysm with perl-arteritic change In rat 545♀ (1000ppm).

- Reproductive system
Atrophic changes in the testes were common to the occasional male rat from both control and treated groups and an area of haemorrhage was observed in the testis of rat 164♂ (10000ppm). Distended or enlarged seminal vesicles were observed in rats 11♂ and 36♂ (Control), prostatitis andminimal squamous metaplasia in rat 79♂ (1000ppm) and cellular Infiltration of the prostate of rat 32♂ (Control). Cysts were observed in the ovaries of a proportion of rats from control and treated groups. Endometritis in rats 420♀ (1000ppm), 517♀ and 540♀ (10000ppm); pyometritis in rat 417♀ (1000ppm); uterine congestion in rat 428♀ (1000ppm) and endometrial polyps In rats 417♀, 420♀, 423♀ and 427♀ (1000ppm), 459♀ and 473♀ (3000ppm).

- Adrenal
Vacuolation of zona fasciculata cells and moderate to severe cystic degeneration of cortical cells and haemorrhage were common to a number of rats from both control and treated groups. Minimal cortical hyperplasia In rat 432♀ (1000ppm), a hyperplastic nodule in the zona fasciculata 417♀ (1000ppm) and focal hyperplasia in rat 482♀ (3000ppm). The above changes are commonly found in the laboratory rat and were considered to be without toxicological significance.


GENERAL HISTOPATHOLOGY OF RATS KILLED AFTER 104 WEEKS OF TREATMENT

- Trachea
A proportion of animals from both the control and treated groups had small aggregations of chronic Inflammatory cells beneath the respiratory epithelium.

- Lung
The majority of animals from both treated and control groups showed evidence of minimal chronic respiratory disease. The morphological changes encountered Included the following:
A minimal degree of peribronchiolar and perivascular lymphoid hyperplasia, and occasional parenchymal collections of alveolar macrophages. Rat 15♂ (Control) had small areas of chronic Interstitial pneumonitis and rat 157♂ (10000ppm) had a moderately large area of bronchopneumonia. These changes are commonly encountered In the laboratory rat and were considered to be of no toxicological significance.

- Liver
No significant group related changes were Identified. Many animals from both the control and treated groups showed varying degrees of hepatocytic vacuolation. In addition, a proportion of animals from both groups showed minimal bile duct hyperplasia, minimal periportal fibrosis and occasional small parenchymal aggregations of chronic Inflammatory cells. Rats 174♂, 176♂ (10000ppm) had occasional small groups of hepatocytes with altered cytoplasmic staining and rat 165♂ (10000ppm) contained numerous small aggregations of hyperplastic hepatocytes. These findings are not uncommon in the aged laboratory rat and were considered to be without toxicological significance.

- Kidney
Varying degrees of progressive glomerulonephrosis were seen in the kidneys of the majority of rats from both control and treated groups. These changes consisted mainly of cystically dilated nephrons with interstitial fibrosis, moderate lymphocytic infiltrations, and occasional glomerular changes. These findings are an age-related change in the laboratory rat and were therefore considered to be of no toxicological significance. Rat 15♂ (Control) contained moderately large cystic structures in its kidneys. This change in a single control animal was without significance.

- Cardiovasular system
A minor degree of myocarditis and myocardial fibrosis was seen in the ventricles of a small proportion of animals from both the control and treated groups. In rat 28♂ (Control) dystrophic mineralization was noted in the media of the aorta and in the blood vessels surrounding the sciatic nerves, and minimal hyaline degeneration was seen In the testicular arteries. In rat 158♂ (10000ppm) the pancreatic blood vessels were dilated and contained organised thrombi and the testicular blood vessels showed minimal perlarterltlc change. These changes in the vascular system are age-related changes commonly found in the laboratory rat, and were therefore considered to be of no toxicological significance.

- Pancreas
A few animals from both groups showed changes which Included minimal atrophy and loss of zymogen granules in the exocrine portion and minimal fibroblastic reaction in and around occasional islets of Langerhans. Rats 176♂ and 505♀ (10000ppm) each had a small nodule of hyperplastic exocrine tissue. These changes are commonly encountered in old rats and were considered to be without toxicological significance.

- Reproductive system
The following changes were seen and were considered to be of no toxicological significance: Testicular atrophy in rats 26♂ (Control), 160♂ and I76♂ (10000ppm); degenerative changes in the tubular epithelium of the epididymis in rat 26♂ (Control). Prostatitis in rats 2♂, 24♂ (Control), 158♂, 161♂, 174♂, (10000ppm); ovarian follicular cysts iIn rats 351♀ (Control), 509♀ (10000ppm); Uterine polyps in rats 351♀, 362♀, 365♀ (Control); endometritis in rats 511♀, 512♀ (10000ppm); galactoceles In the mammary tissue of rat 359♀ (Control).

- Adrenals
Changes, which consisted of vacuolation of zona fasciculata cells and moderate to severe cystic degeneration of cortical cells with haemorrhage were encountered in a proportion of animals from both treated and control groups. Rat 157♂ (10000ppm) contained a small area of cortical hyperplasia, and rat 504♀ (10000ppm) had a small cyst-like structure with a fibrous capsule attached to one adrenal. These changes are commonly found in the old laboratory rat and were considered to be without significance.

Other morphological abnormalities which were seen but not considered to be of toxicological importance included: small areas of necrosis or haemorrhage In the brains of rats 2♂, lO♂, 23♂ (Control); minimal degenerative changes In the pituitary of rats 157♂, 158♂ (10000ppm) and a small cyst In the pars Intermedia of rat 167♂ (10000ppm); minimal hyperplasia of the parathyroids of rats 2♂, 23♂, 28♂ (Control); small aggregations of chronic Inflammatory cells In the skeletal muscle of rat 368♀ (Control); aggregations of inflammatory cells in the submucosa of the stomachs of rats 2♂ and 362♀ (Control); aggregations of acute and chronic Inflammatory cells In the submucosa of the small intestine of rat 23♂ (Control); small vacuoles with minimal myellnophage activity In the spinal cord or cauda equina of rats l0♂, 351♀, 354♀, 360♀, 362♀, 373♀ (Control), 162♂, 507♀, 508♀, 509♀, 516♀ (10000ppm); minimal perivascular gliosis In the spinal cord of rat 2♂' (Control) and occasional haemorrhages In the spinal cord of rat 15♂ (Control); an epidermoid cyst In the subcutaneous tissues of rat 172♂ (10000ppm) and collagen masses with chronic granulation tissue In the subcutaneous tissues of rat 15♂ (Control); marked demyelinization of the sciatic nerve of rat 15♂ (Control); minimal extramedullary haemopoiesis in the spleens of rats 363♀, 365♀ and 373♀ (Control), 505♀, 508♀, 512♀, 516♀, 520♀ (10000ppm); minimal keratitis In the eyes of rats 28♂, 368♀ (Control), and retinal degeneration In rat 507♀ (10000ppm); a reduction In cellularity and evidence of myelofibrosis in rat 28♂ (Control) and 520♀ (10000ppm); cystic degeneration In a lymph node In rat 158♂ (10000ppm) and numerous pigment-laden macrophages in a thoracic lymph node of rat 161♂ (10000ppm).

CONCLUSION
No morphological abnormality or variation from normal was seen in any of the tissues examined which was considered to be due to the administration of the test item.

Histopathological findings: neoplastic:

effects observed, non-treatment-related

Description (incidence and severity):

- Lymphoreticular svstem
The low Incidence of tumours of the lymphoreticular system showed no evidence to suggest a treatment-related disturbance.

- Lung
The lung tumour incidence was well within the spontaneous incidence for rats of the strain employed. One lung tumour (Grade 2) was recorded in rat 181♂ (10000ppm) and metastatic deposits of squamous cell carcinoma, probably originating from a subcutaneous tumour in the lungs of rat 60♂ (10000ppm). No tumours were seen in female rats.

- Liver
One liver cell tumour was observed in this study, in rat 6♂ (Control), clearly indicating that the test item was not hepatocarcinogenic to rats.

- Kidney
A renal adenoma was observed in rat 186♂ (10000ppm), a squamous cell carcinoma In the kidney of rat 517♀ (10000ppm) and an adenocarcinoma In rat 365♀ (Control). These incidences are well within the normal spontaneous incidence for CFY rats and, therefore, show no evidence of treatment-related nephrocarclnogenicity.

- Reproductive system
There was no evidence of a tumorigenic effect on the reproductive system. One Interstitial cell adenoma was observed in the testes of rat 40♂ (Control). A liposarcoma of the adipose tissue adjacent to the ovary was observed in rat 365♀ (Control). A deciduoma was observed in the uterus of rat 508♀ (10000ppm), a fibrosarcoma in rat 420♀ (1000ppm) and a lipoma in rat 462♀ (3000ppm). Neither the incidence nor the multiplicity of mammary tissue tumours, consisting of fibro-adenomas, adenomas and adenocarcinomas showed any evidence of a treatment-related increase.

- Endocrine glands
The control incidence of pancreatic tumours was higher than previously recorded in CFY rats although the increased incidence of tumours in rats treated with 10000ppm was not statistically different from the control Incidence. Following an extensive literature search, Roe and Roberts, 1973, concluded that with three possible exceptions, i.e. ionizing radiation, an alkaloid of the pyrrollzidine group and streptozotocin with nicotinamide, there was no Information on how tumours of the pancreas may be induced by chemical means. As these tumour types occur in old rats, the incidence recorded in the present study was considered to have arisen by chance. The distribution of tumours of the other endocrine glands showed no treatment-related disturbance.

- Subcutaneous tissues
There was no evidence of a treatment-related effect on the incidence of connective tissue tumours found in subcutaneous locations.

- Miscellaneous tumours
The Individual tumour types and number of tumours recorded fall within the spontaneous range for the strain of rat employed.

- Total tumour incidence
There were significantly fewer tumour-bearing rats among males that had received 1000ppm and were killed at termination (P = 0,0033),
The Incidence of tumour-bearing rats in other treated groups was not significantly different from the control incidence

CONCLUSION
The administration of the test compound was not associated with any evidence of an effect on the spontaneous tumour incidence of the CFY rat.

Dose descriptor:

NOAEL

Effect level:

10 000 ppm

Sex:

male/female

Basis for effect level:

body weight and weight gain

Remarks on result:

other: corresponding to 446 mg/kg (m) and 547 mg/kg (f)

Critical effects observed:

not specified

MINIMUM ACHIEVED DOSAGE (Table 1)

The mean intake of test substance (mg/kg body weight/day) during the 104 week treatment period

Group and dose		♂	♀
2. 1000 ppm		45	55
3. 3000 ppm		135	166
4. 10000 ppm		446	547

During the complete histopathological investigation performed in 1985 (see above), the following additional observations were reported:

NEOPLASTIC FINDINGS

The incidence of pancreatic islet cell adenomas, in male rats from the 10,000 ppm dosage group was slightly above that of the control

group (Table 1 ). However, the increase was not statistically significant (Appendix 2) and considered unlikely to be of biological importance. No effect was seen in female rats. The incidence and distribution of other neoplasms in this study were within the normal tumour profile for laboratory maintained rats of this strain. Briefly: mammary tumours were common in females; pituitary tumours in both sexes; with a lower incidence of subcutaneous tumours predominantly in males.

NON-NEOPLASTIC FINDINGS:

No treatment-related changes were detected. Spontaneous changes were recorded for many organs and were within the normal background range for rats of this strain, in this laboratory. Among the more common lesions were: renal progressive glomerulo-nephrosis with parathyroid hyperplasia and associated metastatic mineralisation in the aorta, heart and stomach; and occasional osteodystrophia fibrosa of the sternum; myocardial fibrosis-predominantly in males; foci of altered hepatocytes; periportal hepatocyte vacuolation - predominantly in females; vacuolation of the adrenal cortex; cystic degeneration and haemorrhage of the adrenal cortex - predominantly in females; extra-medullary haemopoiesis in the spleen - mainly in females; and mammary secretory activity/galactoceles - also predominantly in females.

FACTORS CONTRIBUTORY TO DEATH

For animals dying, or killed in a moribund condition during the course of the study, the pathologist attempted to ascertain the major factor(s) responsible for each individual rat. None of these factors were considered to be treatment-related. Common factors were pituitary and mammary tumour - especially in females, subcutaneous tumours in males, and renal disease - especially in males.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

NOAEL

446 mg/kg bw/day

Study duration:

chronic

Species:

rat

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

Commercial samples of the test item were investigated for repeated dose toxicity in feeding studies performed with rats and dogs. The chronic feeding study in rats is valid with the following restrictions: Feed analysis was performed, but no details for accuracy of preparation, homogeneity and stability were reported. Not all biochemical parameters as required by OECD testing guideline 453 were measured. Some of the histopathological examinations were performed 10 years after the finalization of the study. The study was performed prior to GLP requirements. Overall, it is considered suitable to serve as key study.

Groups of 50 male and 50 female CFY rats, a hysterectomy-derived strain of Sprague-Dawley origin, were fed the test substance admixed in the diet at concentrations of 1000, 3000 or 10000 ppm for 104 weeks. A control group received plain diet. All rats were examined daily for signs of ill-health and toxicity. All rats found dead, or killed for humane reasons, were subjected to detailed macroscopic examination. The weight of each rat was recorded at weekly intervals for the first twelve weeks and at four-weekly intervals thereafter. The quantity of food consumed by each cage of rats was recorded and the mean weekly intake calculated. Ophthalmoscopy, urinalysis, hematology and blood chemistry were investigated after 13, 26, 52, 78 and 103 weeks. On completion of the treatment period, all surviving rats were killed by carbon dioxide euthanasia and subjected to autopsy procedures following histopathological investigations.

There were no overt signs of reaction to treatment and the survival rates among treated rats were comparable with those of the controls. Between weeks 24 and 52, bodyweight gain of males receiving 10000 ppm was significantly lower than that of the controls (P<0.05), although subsequent performance was comparable with that of the controls. Between weeks 80 and 104, bodyweight gain of males receiving 1000 ppm was significantly higher than that of the controls, although since this finding was not dose related in degree it is of doubtful biological significance. With the exception of a small decrease in the total mean food intake among all treated rats between weeks 53 and 80, food intake was not disturbed by treatment. Some minor statistically relevant changes were seen during urinalysis, hematology and blood chemistry, however these changes occurred only occasionally, and all values obtained were within normal limits for the strain of rat employed and therefore considered of no toxicological relevance. Macroscopic examination of decedents and rats killed after 104 weeks of treatment showed pathology which was common to animals from control and treated groups. Although differences from control values in adrenal, thyroid and kidney weights attained levels of statistical significance, the differences were related to the intergroup disparity in bodyweight and were not dose related in degree. It was, therefore, concluded that the differences were of no toxicological significance and probably arose fortuitously. During microscopic analysis, no morphological abnormality or variation from normal was seen in any of the tissues examined which was considered to be due to the administration. The NOEL was set at 3000 ppm, corresponding to 135 mg/kg for females and 166 mg/kg for males. Since the findings reported for the high dose are of no toxicological relevance, a NOAEL of 10000 ppm can be derived, corresponding to 446 mg/kg body weight for males and 547 mg/kg body weight for females.

For subchronic exposure, three studies are available. Two of them were performed at a laboratory that is known to have falsified study reports (Industrial Bio-Test lab, 1966a+b). These reports are excluded from the hazard assessment, noting that the results are consistent with the findings of the valid studies. The feeding study with beagle dogs is sufficiently well performed and reported to serve as key study. It was performed under a quality assurance program. The following deviations to OECD testing guideline 409 were noted: Homogeneity of the test substance formulation was not determined and not all required organ weights were determined. Parasitic infection was reported throughout the population. The test item caused no adverse effects at any test dose level; the NOEL is determined to be ≥ 10000 ppm (302 mg/kg body weight for males and 343 mg/kg body weight for females).

The overall low toxicity is supported by the absence of findings in the carcinogenicity study in mice.

Justification for classification or non-classification

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

The available experimental test data are reliable and suitable for classification purposes under Regulation 1272/2008. As a result the substance is not considered to be classified for repeated dose toxicity under Regulation (EC) No. 1272/2008.