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Toxicological information

Carcinogenicity

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Description of key information

Oral NOAEL: 542 mg/kg bw/day (chronic; rat)

Dermal application: no reasons of concern about the carcinogenicity potential.

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:
From November 1973 to November 1975.
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Test procedures are well documented and scientifically acceptable.
Reason / purpose for cross-reference:
reference to same study
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 453 (Combined Chronic Toxicity / Carcinogenicity Studies)
GLP compliance:
no
Remarks:
pre-GLP study
Species:
rat
Strain:
Wistar
Sex:
male/female
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Source: Winkelmann, Borchen.
- Age at study initiation: 28 to 32 days.
- Weight at study initiation: males: 53 g and females: 54 g (mean).
- Housing: conventionally in cages type II.
- Diet: ad libitum, Altromin R-Pulverfutter ( Altromin GmbH, Lage).
- Water: ad libitum, tap water.

ENVIRONMENTAL CONDITIONS
- Temperature: 23 ± 3 °C.
Route of administration:
oral: feed
Vehicle:
unchanged (no vehicle)
Duration of treatment / exposure:
24 month
Frequency of treatment:
Continously in food.
Remarks:
Doses / Concentrations:
0 (control), 100, 1000 and 10000 ppm
Basis:
nominal in diet
Remarks:
Doses / Concentrations:
0, 4.93, 51.35 and 523.88 mg/kg bw/day male
Basis:
actual ingested
Remarks:
Doses / Concentrations:
0, 7.48, 77.48 and 790.59 mg/kg bw/day female
Basis:
actual ingested
No. of animals per sex per dose:
50 males and 50 females x dose.
Control animals:
yes, plain diet
Observations and examinations performed and frequency:
The experimental animals were inspected and occurring changes and symptoms logged daily.

BODY WEIGHT
Time schedule for examinations: weekly until study week 27 and after 14th days thereafter.

FOOD CONSUMPTION AND COMPOUND INTAKE
Compound intake calculated as time-weighted averages from the consumption and body weight gain data.

CAGE SIDE OBSERVATIONS: Yes
Time schedule: daily

HAEMATOLOGY
- Time schedule for collection of blood: after 1, 3, 6, 12 and 24 month.
- N. of animals: 5 male and 5 female rats after 1, 3, 6 and 12 month and from 10 male and 10 female rats after 24 month.
- Parameters examined: erythrocyte count, hemoglobin, leukocyte count, reticulocyte count, thrombocyte count, differential counts, hematocrit.

CLINICAL CHEMISTRY
- Time schedule for collection of blood: after 1, 3, 6, 12 and 24 month.
- N. of animals: 5 male and 5 female rats after 1, 3, 6 and 12 month and from 10 male and 10 female rats after 24 month.
- Parameters examined: Alkaline Phosphatase, Total Protein, Albumin, Glucose, Urea, Creatinine, Bilirubin, total Cholesterol, Aspartate aminotransferase, Alanine aminotransferase.

URINALYSIS: Yes
- Time schedule for collection of urine: after 1, 3, 6, 12 and 24 month.
- Metabolism cages used for collection of urine: yes.
- Parameters examined (semiquantitative): glucose, blood, total protein, pH, bilirubin, urobilirubin, sedime.
Sacrifice and pathology:
GROSS PATHOLOGY:
Yes, necropsies were performed on all animals.

HISTOPATHOLOGY:
Yes; adrenals, aorta, brain, epididymides, eyes, femur, heart, ichiatic nerve, intestine, kidneys, liver, lung, lymph nodes, muscle, esophagus, ovaries, pancreas, pituitary gland, prostate seminal vesicle, salivary gland, spleen, sternum, stomach, testes, trachea, thyroids, urinary bladder, uterus, as well as all gross pathological lesion were sampled and subjected to histopathological examination.
Other examinations:
The organ weights of adrenals, heart, kidneys, liver, lung, ovaries, spleen, testes and thyroid gland were recorded.
Statistics:
Mann-Whitney and Wilcoxon test.
Clinical signs:
effects observed, treatment-related
Description (incidence and severity):
treatment did not affect mortality
Mortality:
mortality observed, treatment-related
Description (incidence):
treatment did not affect mortality
Body weight and weight changes:
no effects observed
Food consumption and compound intake (if feeding study):
no effects observed
Haematological findings:
no effects observed
Description (incidence and severity):
not treatment related effects
Clinical biochemistry findings:
no effects observed
Description (incidence and severity):
not treatment related effects
Urinalysis findings:
no effects observed
Organ weight findings including organ / body weight ratios:
no effects observed
Gross pathological findings:
no effects observed
Histopathological findings: non-neoplastic:
no effects observed
Description (incidence and severity):
not treatment related effects
Details on results:
CLINICAL SIGNS AND MORTALITY
Treatment did not affect mortality.
First year: at 0 ppm 1 female died (2 %). At 1000 ppm 1 male died (2 %).
Second year: at 0 ppm 10 male and 10 female died (20%). At 100 ppm 9 male and 6 female died (18 and 12%); at 1000 ppm 8 male and 10 female died (16 and 22%); at 10000 ppm 11 male and 11 female died (22%).

FOOD CONSUMPTION AND COMPOUND INTAKE
Food consumption of treated animals were similar to those of the control group. The food consumption of rats which received the highest active dose in the feed was comparable with that of animals in the control.

BODY WEIGHT AND WEIGHT GAIN
Body weight development of treated animals were similar to those of the control group.

HAEMATOLOGY
The assessment of hematological data did not indicate any adverse effects in treated animals.
The significantly and dose dependently increased number of thrombocytes in female rats after one month in all dose groups, was not considered adverse because there was no confirmation of these findings in the further course of the study and all values were within historical control ranges of this Wistar rat strain.
The not dose-dependent but statistically significant decrease in the number of reticulocytes in males after 3 months was also considered not to be toxicologically relevant because of the same reasons.
All the other parameters were not affected after 3, 6, 12 and 24 months duration of the experiment significantly by the treatment. Also on the basis of the investigation of complete blood count, no treatment-related changes in the leukocyte blood count were observed at the dose levels to 10000 ppm.
The blood sugar or cholesterol levels were determined not in the pathological range at the dose groups up to 10000 ppm.

CLINICAL CHEMISTRY
The assessment of clinical biochemical data did not indicate treatment related disturbances.
Slightly and not dose-dependently but statistically significant increased ALAT (GPT) activities were observed in males after 24 months at the end of the study in all dose groups.
Slightly and not dose-dependently but statistically significant increased protein concentrations in blood serum were observed after 6 months in both sexes and all dose groups as well as after 24 months in males in all dose groups. These effects on ALAT and serum protein were considered not to be toxicologically relevant, but due to relative low control values as compared with normal historical data in this Wistar rat strain.

URINALYSIS
The assessment or urine analysis data did not indicate treatment related disturbances.
The findings of the urinalysis after 1, 3, 6, 12 and 24-month test period revealed no differences between control animals and treated rats up to the test group of 10000 ppm. In none of the investigated rats glucose, ketone bodies or bilirubin were found in the urine. Protein and blood-positive urine findings were present in all groups at approximately the same frequency. Urobilinogen content and pH-value of the treated animals did not differ significantly from that of control animals. The examination of the sediment revealed no treatment-related effect. The protein contents of the urine were pathologically increased in any group.

ORGAN WEIGHTS
In comparison to the values ​​of the control group were significantly decreased the lung weights of the male and the thyroid, and heart weights of female rats, on the other hand a significant increase in liver and kidney weights of male rats as well as the ovarian weights of female rats respectively after 10000 ppm. The lung weights of the female animals of the treatment groups were dose dependent with the control group; however, the significantly difference (P <0.05) is only in the 1000 ppm dose group.
Other organ weight differences are distributed low and independent of dose.

GROSS PATHOLOGY
During the experiment: all deaths during the experiment rats were dissected. No pathological changes which could be attributed to treatment were found in groups treated.

At the end of the experiment: the section of all deaths rats at end of test revealed no evidence of specific injury in the experimental groups to 10000 ppm

HISTOPATHOLOGY: NON-NEOPLASTIC
In summary, it was found that all the examined organs (aorta, eyes, intestine (duodenum, jejunum, ileum, colon), femur, brain, bladder, heart, testis, pituitary gland, liver, lung, stomach, spleen, epididymis, adrenal glands, kidneys, esophagus, parotid gland, ovary, pancreas, prostate, seminal vesicles, thyroid, skeletal muscle, sternum, trachea, and uterus) showed no treatment effects attributable to the histomorphological alterations.

HISTOPATHOLOGY: NEOPLASTIC
A number of benign and malignant neoplasms, including thyroid interstitial cell neoplasia, pituitary neoplasia, endometrial neoplasia, phaeochromocytoma, and testicular interstitial cell neoplasia, were noted in all dose groups including controls. However, statistical analysis of tumor incidences revealed no significant differences between control and treated groups. In addition, the tumor incidences were not organ or neoplastic class specific and therefore were regarded not to be biologically significant.
Relevance of carcinogenic effects / potential:
Not carcinogenic.
Dose descriptor:
NOAEL
Effect level:
524 mg/kg bw/day (nominal)
Based on:
test mat.
Sex:
female
Basis for effect level:
other: highest dose tested
Remarks on result:
other: Effect type: carcinogenicity (migrated information)
Dose descriptor:
NOAEL
Effect level:
791 mg/kg bw/day (nominal)
Based on:
test mat.
Sex:
male
Basis for effect level:
other: highest dose tested
Remarks on result:
other: Effect type: carcinogenicity (migrated information)

MORTALITY

Doses
ppm
N. of dead / N. test animals N. of dead / N. test animals
Male Female

1th year

0 0/50 0 1/50 2
100 0/50 0 0/50 0
1000 1/50 2 0/50 0
10000 0/50 0 0/50 0

2th year

0 10/50 20 10/50 20
100 9/50 18 6/50 12
1000 8/50 16 10/50 20
10000 11/50 22 11/50 22
Conclusions:
Doses up to 10000 ppm (included; corresponding tho 523.88 mg/kg bw/day male and 790.59 mg/kg bw/day female) were thus tolerated without any damage in rats.
Executive summary:

Method

Male and female rats received test substance in concentrations of 0, 100, 1000 and 10000 ppm administered for 2 years with the feed.

Results

The treated animals showed no treatment-related symptoms during the entire experimental period in any dose group.

Growth, feed intake and mortality were unaffected. The hematological investigation activities carried out during and at the end of the experiments did not revealed injuries.

Despite one month after the blood test revealed dose-dependent lyand significantly elevated(P<0.05) plate let levels in females, this was not considered compound-related toxic effect, since the investigation at all remaining time points did not confirm these findings and all values ​​are within the norm.

At all the doses tested the clinical chemistry analysis, sections and histopathological studies revealed no evidence of treatment-related damage to the liver.

One month after the start of the experiment in male rats of the dose group 10000 ppm significantly increased GPT activity was measured; it was not considered as sign of damage, since all values ​​are in the range of physiological variation and the investigation into the later trial dates did not report corresponding findings.

Urinalysis, urea and creatinine concentrations inserum as well as macroscopic, gravimetric and histopathological findings did not indicate kidney injuries. No reference to a specific damage that might be caused by the drug was revealed by the gross pathology analysis. Significant differences found in organ weights are considered to be due to chance or due to differences in animal weights, because the haematological, clinical chemical and histopathol analysis revealed no effects correlated.

Histopathological examination of the brain, pituitary, eyes, lymph nodes, salivary glands, thyroid, aorta, heart, lung, spleen, pancreas, esophagus, stomach, Dermal, adrenal glands,bladder, testes, epididymides, prostate, seminal vesicle, uterus, ovaries, skeletal muscle and bone showed the usual age-related, spontaneous alterations. Changes which might be associated with the drug administration, were not revealed.

From the nature, site and frequency of observed benign and malignant tumors, a carcinogenic effect of substance was excluded.

Conclusion
Doses up to 10000 ppm (included) were thus tolerated without any damage.

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed
Dose descriptor:
NOAEL
523.9 mg/kg bw/day
Study duration:
chronic
Species:
rat

Carcinogenicity: via inhalation route

Endpoint conclusion
Endpoint conclusion:
no study available

Carcinogenicity: via dermal route

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed

Justification for classification or non-classification

According to the CLP Regulation (EC 1272/2008), 3.6 Carcinogenicity section,carcinogen means a substance which induce cancer or increase its incidence. Substances which have induced benign and malignant tumours in well performed experimental studies on animals are considered also to be presumed or suspected human carcinogens unless there is strong evidence that the mechanism of tumour formation is not relevant for humans. For the purpose of the classification for carcinogenicity, substances are allocated to one of two categories (known or presumed human carcinogens and Suspected human carcinogens) based on strength of evidence and additional considerations (weight of evidence). In certain instances, route-specific classification may be warranted, if it can be conclusively proved that no other route of exposure exhibits the hazard

In conclusion, the available experimental data are adequate for classification and labelling and the substance is not classified for carcinogenicity according to the CLP Regulation (EC 1272/2008).

Additional information

In a combined chronic / carcinogenicity studies the test substances (CAS 16090-02-1) was administered to 50 Wistar rats/sex/dose in diet at dose levels of 0, 100, 1000, 10000 ppm for 24 months. There were no compound related effects in mortality, clinical signs, body weight, food consumption, haematology, clinical chemistry, urinalysis, organ weights, or gross and histologic pathology. The NOAEL is for females and males 10000 ppm/day. The various statistically significant differences observed with CAS 16090 -02 -1 (increase/decrease) in organ weights (absolute in males), number of reticulocytes/trombocytes, and ALAT (GPT) activities and serum protein were considered to be of no toxicological relevance and did therefore not provide any evidence of toxicity of the test substance at any of the dose levels tested. At the doses tested, there were in tested substances not a treatment related increase in tumour incidence when compared to controls (Bayer AG 1978).

Further studies were done in order to investigate whether the test substance has a carcinogenic effect onto skin under light exposure: they investigating the increase or the appearance of skin tumours after several ultraviolet light exposures after dermal exposure to the substance. The experiments conducted did not evidence any reason of concern about the carcinogenicity potential.

Justification for selection of carcinogenicity via oral route endpoint:

Test procedures are well documented and scientifically acceptable.

Justification for selection of carcinogenicity via dermal route endpoint:

No reliable key study can be identified, because of major deficiencies in all of them, neverheless all studies give a clear indication of no dermal cancerogenicity potentiality via dermal route