Registration Dossier

Administrative data

Description of key information

In a 2-year chronic toxicity/carcinogenicity in rats receiving the test substance in the diet at dose levels up to the maximum tolerable dose of 3000 ppm (107 (m) or 138 (f) mg/kg bw) no increase in tumour incidence was observed compared to concurrent controls. 

Key value for chemical safety assessment

Carcinogenicity: via oral route

Link to relevant study records
Reference
Endpoint:
carcinogenicity: oral
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1969
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Comparable to guideline study with acceptable restrictions
Reason / purpose:
reference to same study
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 453 (Combined Chronic Toxicity / Carcinogenicity Studies)
Deviations:
yes
Remarks:
limited clinical chemistry, no urinalysis, limited data on test substance purity and no report onm analylsis of the diets
GLP compliance:
no
Species:
rat
Strain:
Crj: CD(SD)
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River Breeding Lab. Inc. Brookline Mass.
- Age at study initiation: weanling rats
- Weight at study initiation: males 394 - 436 g (av 1. week), females 248 - 269 g (av. week 1)
- Fasting period before study: no
- Housing: 3 males or 4 females per cage
- Diet ad libitum
- Water ad libitum:
- Acclimation period: 2 weeks

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 76 +- 2 deg. F
- Humidity (%): not controlled
Route of administration:
oral: feed
Vehicle:
corn oil
Details on exposure:
PREPARATION OF DOSING SOLUTIONS:

DIET PREPARATION
- Rate of preparation of diet (frequency): 1 kg of corn oil was added to 19 kg of the base diet with or without the test substance. The mixture was stirred for 20 min in a Hobart mixerr (stainless steel). 5 diets with test item were prepared at a concentration of 15, 60, 100, 500, 3000 ppm. The diet was freshly perpared every week.
- Mixing appropriate amounts with (Type of food):special perparation of Rockland Mouse and Rat diet containing no more than 1% of fat. The diet was obtained fresh every month.
- Storage temperature of food: refigerator

VEHICLE
- Justification for use and choice of vehicle (if other than water): for dissolution of at least part of the substance is dissolved in cornoil (6% solubility) to ensure homogenous distribution
- Concentration in vehicle: 300, 1200, 2000, 10000, 60000 mg/kg corn oil
- Purity: Mazola Corn oil free of antioxidants
Analytical verification of doses or concentrations:
no
Duration of treatment / exposure:
104 weeks
Frequency of treatment:
continously in diet
Remarks:
Doses / Concentrations:
15, 60, 100, 500, 3000 ppm
Basis:
nominal in diet
No. of animals per sex per dose:
25, 50 controls, 4 males and 4 females were assigned to subgroups for interim kills after 13, 26, 52 and 78 weeks
Control animals:
yes, concurrent vehicle
Details on study design:
- Dose selection rationale: dose selection based on 90-day study
- Rationale for animal assignment (if not random): were randomly assigned
.
Observations and examinations performed and frequency:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: daily
- Cage side observations checked: general appearance and behaviour

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule:
weekly
BODY WEIGHT: Yes
- Time schedule for examinations: weekly

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study): weekly per cage
- Compound intake calculated as time-weighted averages from the consumption and body weight gain data: No data

FOOD EFFICIENCY:
- Body weight gain in kg/food consumption in kg per unit time X 100 calculated as time-weighted averages from the consumption and body weight gain data: No data

WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): No data


OPHTHALMOSCOPIC EXAMINATION: Yes
- Time schedule for examinations: weekly
- Dose groups that were examined: all for cataracts

HAEMATOLOGY: Yes
- Time schedule for collection of blood: 1 week before dosing, week 13, 26, 52, 78, 104
- Anaesthetic used for blood collection: No data
- Animals fasted: No
- How many animals:10 per dose
- Parameters examined: prothrombin time, hemoglobin, packed cell volume of erythrocytes, total and differential leukocytes

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: at scheduled sacrifice
- Animals fasted: No
- How many animals: all allocated to the respective groups
- Parameters examined: total lipids, cholesterol, alkaline phopsphatase

URINALYSIS: No

NEUROBEHAVIOURAL EXAMINATION: No
Sacrifice and pathology:
GROSS PATHOLOGY: Yes: liver, heart, lungs, kidneys, spleen, brain, gonads, pituitary, adrenals, thyroid
HISTOPATHOLOGY: Yes : Heart, Aorta, lungs, liver, spleen , kidney, stomach, duodenum, pylorus, small intestine (ileum), large intestine (colon), mesenteric lymph nodes, urinary bladder, prostate, testes, ovaries and uterus, pancreas, thyroids, thymus, adrenals, pituitary, brain, spinal cord, eye, bone marrow, bone, skeletal muscle, skin.
Statistics:
Performed, but no data on methods
Clinical signs:
no effects observed
Description (incidence and severity):
no test substance realted effects observed
Mortality:
no mortality observed
Description (incidence):
no test substance realted effects observed
Body weight and weight changes:
no effects observed
Description (incidence and severity):
no test substance realted effects observed
Food consumption and compound intake (if feeding study):
no effects observed
Description (incidence and severity):
no test substance realted effects observed
Food efficiency:
not examined
Water consumption and compound intake (if drinking water study):
not examined
Ophthalmological findings:
no effects observed
Haematological findings:
no effects observed
Description (incidence and severity):
no test substance realted effects observed
Clinical biochemistry findings:
no effects observed
Description (incidence and severity):
no test substance realted effects observed
Urinalysis findings:
not examined
Behaviour (functional findings):
not examined
Organ weight findings including organ / body weight ratios:
effects observed, treatment-related
Description (incidence and severity):
increase in liver weight at the highest dose tested
Gross pathological findings:
no effects observed
Description (incidence and severity):
no test substance realted effects observed
Histopathological findings: non-neoplastic:
effects observed, treatment-related
Description (incidence and severity):
liver increased fatty degenaration and bile duct proliferation at 3000 and 500 ppm, but similar lesions also in controls
Histopathological findings: neoplastic:
no effects observed
Description (incidence and severity):
no test substance realted effects observed
Details on results:
CLINICAL SIGNS AND MORTALITY
Throughout the study several rats had various infectious diseases and died in the course of the illness. The incidence and severity of these diseases were unrelated to the content of the test substance in the diets and occurred equally in the control rats. The mortality in the different groups was comparable to controls. (see Table 1). The only test substance related clinicall sign was a greenish-yellow discoloration of the fur of the high dose rats commencing after 6 motnhs and in rats receiving 500 ppm after one year. Occasional discoloration was seen some the rats receiving 100 ppm after 15 months.
BODY WEIGHT AND WEIGHT GAIN
No test substance realted changes in body weight or body weight gain were observed in the study. Variations in body weight and body weight gain of individual animals during the cours of the study were attributed to infectious diseases or spontaneous tumors that occurred at comparable incidence in the treated and control groups and were accompanied by respective changes in food consumption.
FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study)
Food consumption was comaprable between treated and control animals and only influenced by diseases as mentioned above. The average test substance intake during the study was calculated for males and females (see table 2).
FOOD EFFICIENCY
Food efficiency was reported to be comparable between treated and control animals.
OPHTHALMOSCOPIC EXAMINATION
No findings were reported from the ophthalmologic examinations
HAEMATOLOGY
Mild to moderate leukopenia was reported in some females at week 52 and 78, but not after 104 weeks of feeding. The incidence in treated and control animals was comparable. Single cases of some degree of anaemia or polychromasia wer occaisonally seen during week 78 and 104 in males and females of all groups including controls with no relationship to treatment. Prothrombin time was statisitcally significantly different from controls in males of the 15 and 500 ppm group in the week before treatment started, and in the 15, 100 and 3000 ppm groups at 13 weeks. In females statistically significant differences to controls were observed in the 60, 100, 500 and 3000 ppm groups one week before treatment started and in the 500 ppm group on week 26. No statistically significant differences to control values were observed at the 26, 52, 78 and 104 week observation times. As the finding was not dose related and did not persist throughout the course of the study, it was not considered treatment related. All other haematological parameters were comparable between treated and control animals.
CLINICAL CHEMISTRY
Alkaline phosphatase levels varied widely within the groups and the only statistically significant finding was an increased level in the high dose group males in week 104. Due to the major fluctuations in the measurements this finding was not considered treatment related by the authors. No consistent treatment related effect was observed on the serum cholesterol anmd total lipid levels
ORGAN WEIGHTS
All relative organ weightsand most absolute organ weights in the treated groups were comparable to the respective control values. Single rats receiving 3000 ppm of the test substance were reproted to have enlarged livers, but the group avaerages did not reach statisitcal significance, with the exeption of females killed aftter week 13 and males killed after week 78. In females fed for 104 weeks at 15 ppm a relative liver weight statistically significantly lower than control values was reported. This is an isolated finding and in the higher dose groups no significant changes in liver weight were observed. Therefore this finding is not considered treatment related by the authors.
GROSS PATHOLOGY
No test substance related macroscopic organ changes were observed in the study.
HISTOPATHOLOGY: NON-NEOPLASTIC
All animals (treatment and control) killed at 24 months had pneumonia or interstitial nephritis or both. A total of 183 rats died during the cours of the study. Fior 52 no postmortem pathology could be done due to autolysis. For 131 postmortem pathology revealed in most instances massive pulmonary infection as the cause of death. Liver lesions were the most prominent findings and consisted of fatty degeneration of the hepatic sells and a proliferation of the bile ducts. Fatty degeneration reached from small fat vacuoles to a fatty liver. There was no special localization of the degeneated cells in the liver lobe. The incidence and severity in the different groups is given below (table 3). Two types of proliferation of the bile ducts coudl be distinguished morphologically: 1. multiplication of the bile ducts with retainment of their normal stucture occurred in small clusters. 2. A dilatation and multiplication of the bile ducts with fibrotic walls without epithelium. In some of the dilated bile ducts mucous plaques were observed. No inflammatory reaction was present. Up to 3 months of feeding no alterations in the livers were observed. Both lesions invcreased in control and treated rats from 18 months of treatment. After 24 more severe lesions were observed in the 500 and 3000 ppm dose groups. Incidence and severity was more pronounced in males than in females.
HISTOPATHOLOGY: NEOPLASTIC (if applicable)
Neoplastic lesions observed in the study were subcutaneous or in females mammary gland adenofribroma, pituitary adenoma, one adenoma in the parathyroid, thyroid adenoma, adrenal adenoma, liver angioma that wer all benign tumors. Leukemia, Seminoma and ovary carcinoma were single findings in control animals only. No test substance related increased incidence of any tumour was observed and it can be concluded that the test substance did not induce neoplastic lesions under the conditions of this study. The findings are summarized in chapter 7.7.

The histopathology findings were confirmed in a second reading of the data with independent pathologists and reported in a supplementary report of the same laboratory dated July 9, 1971.
Relevance of carcinogenic effects / potential:
No carcinogenic effects observed.
Dose descriptor:
other: no carcinogenic effects observed for chronic toxicity see chapter 7.5
Effect level:
> 3 000 ppm (nominal)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: No test substance related increase in tumour incidence was observed
Remarks on result:
other: Effect type: carcinogenicity (migrated information)

For tables on repeated dose toxicity endpoints see chapter 7.5

Tumour incidences observed:

Tumor incidence

Type of neoplasm

Control m

Control f

15 ppm m

15 ppm f

60 ppm m

60n ppm f

100 ppm m

100 ppm f

500 ppm m

500 ppm f

3000 ppm m

3000 ppm f

Adenofibroma

8

12

0

4

4

15

2

13

4

7

3

3

Pituitary adenoma

7

15

5

7

3

6

1

4

2

8

2

6

Parathyroid adenoma

0

0

0

0

0

0

0

0

1

0

0

0

Thyroid adenoma

1

1

0

0

0

0

0

1

0

0

0

0

Adrenal adenoma

0

0

1

0

0

0

0

0

1

0

0

0

Liver angioma

1

0

0

0

0

0

0

0

1

0

2

0

Leukemia

1

0

0

0

0

0

0

0

0

0

0

0

Seminoma

1

-

0

-

0

-

0

-

0

-

0

-

Ovary carcinoma

-

1

-

0

-

0

-

0

-

0

-

0

 

Conclusions:
In a 2-year combined repeated dose-carcinogenicity dietary study in rats the test substance did not lead to an increased tumor incidence up to the highest dose level tested of 3000 mg/kg diet corresponding to appr. 107 mg/kg bw/day in males and 138 mg/kg bw/day in female rats. For other effects see section 7.5. of this IUCLID dossier.
Executive summary:

Groups of male and female CD-1 rats (25 per sex per dose, with 50 controls per sex) were fed diets containing 0 (control), 15, 60, 100, 500, and 3000 ppm (mg/Kg diet) of 4'4'-methylene bis(2,6 -di-tert. butylphenol) for a period of 2 years. This corresponded to approximate dose levels of 0, 0.55 (m)/0.67 (f); 2.14 (m)/2.63 (f), 3.56 (m)/ 4.35 (f), 18.1 (m)/22.2 (f); 107 (m) and 138 (f) mg/kg bw/day. Mortality was comparable to controls in all dose groups. No test substance related clinical signs, body weight changes, hematological or clinical chemical changes were observed during the study. A discoloration of the fur was observed among animals of the 500 and 3000 ppm dose group and single animals in the 100 ppm dose group. No clearly test substance related changes in organ weights and gross pathology were observed at all dose levels.

Test substance related effects were confined to histopathological findings of a dose related aggravation of liver lesions identified as fatty degeneration and bile duct multiplication that were also present to a lesser extend and severity in control animals. With regard to carcinogenicity it can be concluded that under the conditions of this study the test substance did not lead to an increased tumor incidence up to the highest dose level tested of 3000 mg/kg diet corresponding to appr. 107 mg/kg bw/day in males and 138 mg/kg bw/day in female rats. For other effects see section 7.5 repeated dose toxicity of this IUCLID dossier.

 

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed
Study duration:
chronic
Species:
rat
Quality of whole database:
A two year carcinogenicity study in rats is avaialble followng a previous test guideline from 1969. Although due to this fact some deficiencies are present, including infections in the test animals, the study is considered to provide sufficient evidence, in combination with other repeated dose and genotoxicity studies to conclude on this endpoint.

Carcinogenicity: via inhalation route

Endpoint conclusion
Endpoint conclusion:
no study available

Carcinogenicity: via dermal route

Endpoint conclusion
Endpoint conclusion:
no study available

Additional information

In a 2-year chronic toxicity/carcinogenicity in rats receiving the test substance in the diet at dose levels up to the maximum tolerable dose of 3000 ppm (107 (m) or 138 (f) mg/kg bw) no increase in tumour incidence was observed compared to concurrent controls. The results of this study are corroborated by other repeated dose toxicity studies (90 -day studies in rats and dogs, 2 year study in dogs) that also did not reveal any indications of neoplastic or pre-neoplastic lesions. Furthermore all avaialble genotoxicity studies gave consistent negative results. Therfore it can be concluded that based on the avaialble data the substance is considered to be not carcionogenic.


Justification for selection of carcinogenicity via oral route endpoint:
A two year chronic-carcinogenicity study in rats is available and chosen as the key study.

Justification for classification or non-classification

In a 2-year chronic toxicity/carcinogenicity in rats receiving the test substance in the diet at dose levels up to the maximum tolerable dose of 3000 ppm (107 (m) or 138 (f) mg/kg bw) no increase in tumour incidence was observed compared to concurrent controls. The results of this study are corroborated by other repeated dose toxicity studies (90 -day studies in rats and dogs, 2 year study in dogs) that also did not reveal any indications of neoplastic or pre-neoplastic lesions. Furthermore all avaialble genotoxicity studies gave consistent negative results. Therfore it can be concluded that based on the avaialble data the substance is considered to be not carcionogenic. Consequently no classification for carcinogenicity is warranted according to Regulation EC 1272/2008 and amendments.