4,6-bis(octylthiomethyl)-o-cresol

Endpoint summary

Description of key information

In a repeated dose 90-day oral toxicity study in rats conducted according to the OECD Guideline 408, administration by gavage at a dose level up to 1000 mg/kg caused slight adaptive effects on liver. The NOEL was 10 mg/kg bw. In a 90-day oral gavage toxicity study conducted in dogs according to the OECD Guideline 409, a dose level up to 1000 mg/kg caused weak effects on liver enzymes and biliary cell proliferation possibly indicating adverse effects on liver. No effects were observed at 10 mg/kg bw.

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records

Reference

Endpoint:

sub-chronic toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

GLP compliance:

yes

Limit test:

no

Species:

dog

Strain:

Beagle

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Marshall Farms (North Rose, New York 14516, U.S.A.)
- Age at study initiation: 5 months
- Weight at study initiation: 7.8+/-0.5 kg for the males and to 7.4+/-0.7 kg for the females
- Housing: in individual stainless steel cages (0.75 x 1.00 x 0.82 m)
- Diet (ca. 300 g/d, 2 hrs after treatment): standard dry diet A SQC (Special Diets Services Ltd, Witham, Essex, U.K.)
- Water (ad libitum): tap water
- Acclimation period: one month

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19+/-3
- Humidity (%): 50+/-30
- Air changes (per hr): 10-15
- Photoperiod (hrs dark / hrs light): 12/12

Route of administration:

oral: gavage

Vehicle:

other: 0.3% carboxymethylcellulose and 0.1% Tween 80 in water

Details on oral exposure:

PREPARATION OF DOSING SOLUTIONS: The test substance was diluted in the vehicle and homogenized by a
magnetic stirrer.

DIET PREPARATION
- Rate of preparation of diet (frequency): the preparations were performed for 3, 4 or 5 days of treatment in accordance with the stability.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Infrared spectrophotometry

Duration of treatment / exposure:

91-93 d

Frequency of treatment:

daily

Dose / conc.:

10 mg/kg bw/day (actual dose received)

Dose / conc.:

100 mg/kg bw/day (actual dose received)

Dose / conc.:

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

No. of animals per sex per dose:

control and high dose treatment: 6
low and mid dose treatment: 4

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: the doses were based on the results of a range-finding toxicity study where no systemic adverse effect was observed at 2000 mg/kg/day during 14 days. The dose of 1000 mg/kg/day corresponded with the requirement of the OECD Guideline 409. The doses of 10 and 100 mg/kg/day were the same as those used in a 3-month rodent study.
- Post-exposure recovery period in satellite groups: 4 weeks, only control and high dose treatment

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS/ DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: all clinical signs were recorded once daily for each animal at approximately the same time. All animals were checked each day at approximately 8.00 a.m. and 4.00 p.m. for ill, moribund and dead animals. During weekends and Public Holidays, the final check was carried out at approximately midday.

BODY WEIGHT: Yes
- Time schedule for examinations: the weight of each animal was recorded a week before the beginning of treatment, on the first day of treatment, and once weekly during treatment and recovery periods.

FOOD CONSUMPTION:
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes

OPHTHALMOSCOPIC EXAMINATION: Yes
- Time schedule for examinations: before the beginning of treatment, and on week 13, 2 to 4 hours following drug administration, with an indirect ophthalmoscope; all animals

HAEMATOLOGY: Yes
- Time schedule for collection of blood: weeks 4, 8, 13 and at the end of the recovery period (week 17)
- Anaesthetic used for blood collection: No
- Animals fasted: Yes
- How many animals: all
- Parameters checked:
Erythrocytes (RBC)
Haemoglobin (HB)
Mean Cell Volume (MCV)
Packed Cell Volvune (PCV)
Mean Cell Haemoglobin Concentration (MCHC)
Mean Cell Haemoglobin (MCH)
Leucocytes (WBC)
Thrombocytes (PLAT)
Differential White Cell Count: neutrophils (N), eosinophils (E), basophils (B), lymphocytes (L), monocytes (M)
Quick time (QT)
Activated Partial Thromboplastin Time (APTT)
Fibrinogen (FIBRIN)

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: weeks 4, 8, 13 and at the end of the recovery period (week 17)
- Animals fasted: No
- How many animals: all
- Parameters checked: Sodium (Na+)
Potassium (K+)
Chloride (Cl-)
Calcium (Ca++)
Inorganic Phosphorus (I.PHOS)
Glucose (GLUC)
Urea (UREA)
Creatinine (CREAT)
Total bilirubin (TOT.BIL)
Total proteins (PROT)
Cholesterol (CHOL)
Triglycerides (TRIG)
Alkaline phosphatise (ALP)
Aspartate aminotransferase (ASAT)
Alanine aminotransferase (ALAT)
Creatine kinase (CK)
Gamma Glutamyltransferase (GGT)
Protein electrophoresis: albumin (ALB), alpha-1 globulins, alpha-2 globulins, beta-globulins, gamma-globulins, albumin/globulins ratio

URINALYSIS: Yes
- Time schedule for collection of urine: before the beginning of treatment, on week 13 and at the end of the recovery period (week 17).
- Metabolism cages used for collection of urine: Yes
- Animals fasted: Yes
- Parameters checked: . volume (VOLUME), appearance (APP), pH (PH), specific gravity (SP.GRAV), urobilinogen (UROB), proteins (PROT), glucose (GLUC), ketones (CETO), bilirubin (BILI), blood (BLOOD), nitrites (NITR) microscopy of deposit after centrifugation: investigation for leucocytes (WBC), erythrocytes (RBC), hyaline (HYAL) and granular (GRAN) cylinders, magnesium ammonium phosphate (MAM.PH.), calcium phosphate (CAL.PH) and calcium oxalate (CAL.OX) crystals, epithelial (EPITH.), bladder (BLAD) and kidney (KIDN) cells.

Sacrifice and pathology:

GROSS PATHOLOGY: Yes
Organ weights
For all animals, the following organs were weighed wet as soon as possible after dissection: adrenals, brain, heart, kidneys, liver, ovaries, spleen, testes, thyroids and parathyroids. The animals were weighed before necropsy. Paired organs were weighed separately.

Macroscopic examination
For all animals, samples of the macroscopic lesions and the following tissues were preserved in 10% buffered formalin, except the eyes and pituitary gland which were fixed in formol-sublimate, for the animals sacrificed at the end of treatment and recovery periods (the tissues marked by (1) were kept in a fixative in case of a possible microscopic examination): aorta, caecum, brain including medulla/pons, cerebellar and cerebral cortex, heart, colon, duodenum, stomach, femoral bone with articulation (1), liver, mammary glands, salivary glands (parotid and mandibular), pituitary gland, ileum, jejunum, spinal cord, cervical, thoracic and lumbar, skeletal muscle, sciatic nerve, lymph nodes, mandibular and mesenteric, esophagus, ovaries, pancreas, skin, lungs, prostate, spleen, rectum, adrenals, sternum (with bone marrow), testes, epididymides, thymus, thyroids with parathyroids, trachea, uterus with horns and cervix, vagina, gall bladder, urinary bladder, eyes, kidneys

HISTOPATHOLOGY: Yes
All the tissues required for the microscopic examination were embedded in paraplast, sectioned at approximately 4 microns in thickness and stained with hemalum-eosin. Microscopic examination was performed on all macroscopic lesions and tissues as listed above for all animals.

Statistics:

The following sequence was used for the statistical tests of the body weight, food consumption, haematological and biochemical parameters and organ weights: The normality of the distribution of the values in each group was checked by Kolmogorov-Smirnov's test (1948). If the distribution is normal, the homogeneity of variances between the groups was assessed by Bartiett's test (1937) (more than 2 groups) or Fisher's test (1934) (2 groups). If no significant heterogeneity of the variances is established the comparison between treated and control groups was performed by Dunnett's test (1955). If the variances are heterogeneous, the comparison between treated and control groups was performed by Dunn's test (1964) (more than 2 groups) or by Mann Whitney's test (1947) (2 groups). If the distribution of values in the groups is not normal, the analysis was repeated after logarithmic transformation of the values, except for the organ weights. If this logarithmic transformation fails to normalise the distribution of the values, comparison of treated and control groups was performed by Dunn's test (1964) using original values.

Clinical signs:

no effects observed

Description (incidence and severity):

Vomiting and liquid feces were sporadically observed in some treated animals. These symptoms were rare and had no relationship with the dose; moreover, they are commonly and spontaneously observed in dogs. Consequently, their absence in controls they were not considered as treatment-related.

Mortality:

no mortality observed

Description (incidence):

No deaths occurred throughout the study.

Body weight and weight changes:

no effects observed

Description (incidence and severity):

Slight decrease in body weight (up to 11%) was observed in one male of the 1000 mg/kg/day group from week 1 to week 5. Thereafter, the body weight gain was normal for this animal. One male and one female of the 1000 mg/kg/day group showed a slight decrease in body weight from week 6 or 7 to week 10 (around 17 and 10%). Thereafter, their body weight was stable until the end of the recovery period. A relationship with the treatment cannot be ruled out. The body weight difference between the control and high dose group males, kept for the recovery period, is explained by a higher body weight of the control males throughout the study.

Food consumption and compound intake (if feeding study):

no effects observed

Description (incidence and severity):

The food consumption was normal and similar in treated and control animals throughout the study.

Food efficiency:

no effects observed

Ophthalmological findings:

no effects observed

Description (incidence and severity):

A few animals showed a hypopigmentation of the fundus. These variations from normal are commonly observed in dogs (Bellhorn, 1981; Rubin, 1974), and were not related to the treatment since they were, moreover, observed at predose and without change on week 13.

Haematological findings:

effects observed, treatment-related

Description (incidence and severity):

A slight increase in mean total white cell count was observed on weeks 4, 8 and 13 in the animals of both sexes of the 1000 mg/kg/day group. This increase was due to a moderate increase in neutrophils in a few individuals. This phenomenon was more prominent on week 4. Evidence of reversibility was found after the 4-week recovery period. Although this parameter showed a great variability, an increase in neutrophils was noted only in the animals of the high dose group; therefore the relationship to the treatment of this change cannot be ruled out. A slight decrease in Quick time was observed on week 13 in the animals of both sexes of the high dose group. The relationship of this phenomenon to the treatment with the test substance was considered unlikely, since the decrease was minor when compared with the lower limit of our background data (males: 5-9 s, females: 5-7 s).

Clinical biochemistry findings:

effects observed, treatment-related

Description (incidence and severity):

At 100 and 1000 mg/kg/day, a slight to moderate increase in aminotransferases (ASAT and/or ALAT) and/or alkaline phosphatase activities was observed in a few individuals on weeks 4, 8 or 13. These increases were more prominent at 1000 mg/kg/day, especially on week 13 for one female which showed a marked increase in ALP (factor of 3). Evidence of reversibility was found after 4 weeks of recovery. Although, in most cases, these increases had not progressed with time, they were considered to be related to the treatment with the test substance. The slight variations observed in the other biochemical parameters (glucose, cholesterol, triglycerides, alpha-2 globulins, creatine kinase) were considered to be of no toxicological significance, since they were minor and the individual values were within the normal range of our background data.

Urinalysis findings:

no effects observed

Description (incidence and severity):

No abnormalities that could be related to the treatment were noted.

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):

At the end of the treatment period, the analysis of organ weights revealed:
- a slight increase in the absolute and relative weights of the liver in the females of the 1000 mg/kg/day (+22%) and a slight decrease in relative liver weight (-24%) in the males of the 10 mg/kg/day. The contradictory variations, with respect to the liver weights as well as the absence of any changes in the liver weights of the males of the high dose group, did not suggest a treatment-relationship.
- a slight to moderate decrease in absolute and relative weights of the testes in the males of all treated groups and the ovaries in the females of the 100 and 1000 mg/kg/day groups. The variations in the testes weight were not dose-related and were without any corresponding histopathological changes. The decrease in the ovarian weights corresponded to the absence of sexual maturation in almost all animals except for 2 control females and one from the 10 mg/kg/day group which reached sexual maturity. Accordingly, thee above-mentioned variations in the weights of the gonads were considered to be of no toxicological significance.
In addition, slight increases were found in the absolute and/or relative weights of the spleen and thyroid gland in the females and slight decreases in relative weights of the spleen and adrenal glands in the males. These variations in organ weights were not considered to be treatment related since they were minor, not dose-related and without any corresponding histopathological changes. At the end of the recovery period, the minor to slight variations found in the organ weights were considered to be of no toxicological significance and there was no corresponding histopathological changes in these organs.

Gross pathological findings:

effects observed, non-treatment-related

Description (incidence and severity):

Colored areas or nodules (blackish, brownish, reddish, purplish and/or yellowish) sometimes together with granular consistency were found in the lungs of 1/4 males and 3/4 females of the 1000 mg/kg/day group at the end of the treatment period. Furthermore, similar changes (colored areas and foci) were found in the lung at the end of the recovery period in 1/2 males of the control group and 1/2 males and 1/2 females of the 1000 mg/kg/day group. The other macroscopic findings are commonly recorded in laboratory dogs. Furthermore, they were of similar incidence and morphological characters in control and treated animals. Therefore they were considered to be of no toxicological significance.

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

A slight to moderate biliary cell proliferation was found in the liver of 3/4 males and 3/4 females of the 100 mg/kg/day group and 3/4 males and 2/4 females of the 1000 mg/kg/day group sacrificed at the end of the treatment period. The severity of this change was not dose-related, however it was considered to be treatment-related effect. No evidence of reversibility was found since the same was found in 1/2 males and 2/2 females of the 1000 mg/kg/day group sacrificed at the end of the recovery period. Some pulmonary changes were found in the lungs of some control and treated animals. These included acute bronchopneumonia, histiocytosis and some other minor findings. These microscopic findings were in line with the macroscopic changes found at the macroscopic examination of the lungs. These pulmonary changes can be found spontaneously in untreated dogs. Furthermore, similar changes were found at the end of the recovery period in 1/2 males of the control group and 1/2 males and 1/2 females of the 1000 mg/kg/day group. Therefore they were not considered to be toxicologically meaningful.
The other microscopic changes are commonly recorded in laboratory dogs. Furthermore, their incidence, severity and morphological characters were comparable in control and treated animals. Therefore they were considered as not toxicologically significant.

Dose descriptor:

NOEL

Effect level:

10 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: slight to moderate biliary cell proliferation without evidence of dose-relationship or reversibility were observed at 100 and 1000 mg/kg bw. Slight increase of ALP

Critical effects observed:

not specified

Conclusions:

The administration of the test item by oral route (gavage) to Beagle dogs for a period of 13 weeks at the dose levels of 10, 100 and 1000 mg/kg/day, was clinically well-tolerated. At the two higher dose groups, observed effects were mostly not dose related and so weak that it is difficult to assess whether they are incidental or actually treatment-related. A slight decrease in body weight was noted at 1000 mg/kg/day. A moderate increase in neutrophils at the dose level of 1000 mg/kg/day At 100 and 1000 mg/kg/day, a slight to moderate increase in aminotransferases (ASAT and/or ALAT) and/or alkaline phosphatase activities was observed in a few individuals on weeks 4, 8 or 13. These increases were more prominent at 1000 mg/kg/day, especially on week 13 for one female which showed a marked increase in ALP (factor of 3). Evidence of reversibility was found after 4 weeks of recovery. In most cases, these increases had not progressed with time.
The histopathological examination showed a slight to moderate biliary cell proliferation in the 100 and 1000 mg/kg/day groups, without evidence of of dose-relationship or reversibility. Biliary cell proliferation reverses slowly and full reversibility could not be expected within four weeks. The proliferation is an adaptive rather than an adverse response. From the above data, the liver was considered as the target organ. Based on the liver enzyme activities, effects at 1000 mg/kg bw may be considered adverse, whereas those at 100 m/kg are difficult to judge. A clear no-observed effect level is identified at 10 mg/kg/day.

Executive summary:

In a subchronic toxicity study forty Beagle dogs (20 males and 20 females) were allocated into one control and one high dose group of 6 males and 6 females each, and 2 other treated groups of 4 males and 4 females each. The test substance was administered daily by oral route at the dose levels of 10, 100 and 1000 mg/kg/day in a total volume of 2 ml/kg. Two males and 2 females of the control and high dose groups were kept for a 4-week recovery period after the termination of the treatment. Examinations were performed daily and included observation of clinical signs and mortality, and estimation of food consumption. Body weight was recorded before the beginning of treatment and once a week during the study. Ophthalmological examinations were performed during the predosing period and on week 13. Haematological and blood biochemical examinations were performed during the predosing period on weeks 4, 8 and 13, and at the end of the recovery period. Urinalysis was performed during the predosing period, on week 13, and at the end of the recovery period. At the end of the treatment and recovery periods, the animals were sacrificed. Organ weights were recorded. The organs were subjected to a full macroscopic examination and tissue specimens were examined microscopically. No clinical signs related to the treatment were observed. and no deaths occurred throughout the study. Slight decreases in body weight were observed in 2 males and one female of the 1000 mg/kg/day group, from week 1 to week 5 for one male and from week 6 or 7 to week 10 for the other animals. The food consumption of the animals was normal. The ophthalmological examinations showed no abnormalities related to the treatment. A moderate increase in neutrophils was observed in a few males and females of the 1000 mg/kg/day on weeks 4, 8 and 13. Evidence of reversibility was found after the 4-week recovery period. A slight to moderate increase in aminotransferases and/or alkaline phosphatase activities was observed in a few males and females from the 100 and 1000 mg/kg/day groups on weeks 4, 8 and 13- These changes were dose-related and evidence of reversibility was found after the 4-week recovery period. No abnormalities related to the treatment were observed regarding the oragan weights. Moacroscopically, no abnormalities of toxicological significance were found. Microscopic examination revealed a slight to moderate biliary cell proliferation in 3 males and 3 females of the 100 mg/kg/day group and in 3 males and 2 females of the 1000 mg/kg/day group. This abnormality could probably be related to the increase in aminotransferases and alkaline phosphatase activities. No evidence of reversibility was found since the same abnormality was observed in 1/2 males and 2/2 females of the 1000 mg/kg/day group, sacrificed following the 4-week recovery period.

In conclusion, the administration of the test substance by oral route (gavage) to Beagle dogs for a period of 13 weeks at the dose levels of 10, 100 and 1000 mg/kg/day, was clinically well-tolerated. A slight decrease in body weight was noted at 1000 mg/kg/day. A moderate increase in neutrophils at the dose level of 1000 mg/kg/day, and a slight to moderate increase in aminotransferases and/or alkaline

phosphatase activities at the dose levels of 100 and 1000 mg/kg/day. were observed. Evidence of reversibility was found after the 4-week recovery period. The histopathological examination showed a slight to moderate biliary cell proliferation in the 100 and 1000 mg/kg/day groups, without evidence of reversibility. Consequently, the liver was considered as the target organ. In conclusion, the dose level of 10 mg/kg/day could be considered as the No Observable Effect Level under the conditions of the study.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

NOAEL

10 mg/kg bw/day

Study duration:

subchronic

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

Oral Route of Exposure

1) Rat study:

In a subchronic toxicity study following OECD Guideline 408 three groups of Sprague-Dawley rats received the test substance by gavage at 10, 100 and 1000 mg/kg/day dose levels. The vehicle was a solution of water for injectable preparations with 0.5% carboxymethylcellulose and 0.1% Tween 80. Each group contained 10 males and 10 females except the 0 (vehicle only and acted as control) and 1000 mg/kg/day groups which contained each 20 males and 20 females. After a 91-days treatment period, the first 10 males and females of the control and high dose level groups were kept for a 28-day recovery period. The other animals were sacrificed after a 92 or 93-day treatment period for necropsy. The dose selection was based on the results of 28-days OECD Guideline 407 study in rats (Ciba Geigy, 1988), where treatment with the test item at 10, 50, 250 and 1000 mg/kg/day dose levels resulted in functional adaptations, including slightly increased liver weights in males treated at 250 and 1000 mg/kg and in females treated at 1000 mg/kg correlated with minimally increased activity of alkaline phosphatase (with no histopathological changes). The results of the 90-days study can be summarized as follows:

- Hyper-salivation after treatment observed in 6/20 males and 6/20 females of the 1000 mg/kg/day group. This clinical sign was considered treatment related.

- Mortality was detected in 1/20 males (5%) in the control group and 1/10 males (10%) and 1/10 females (10%) in the 100 mg/kg/day group. But, in the absence of dose-relationship, the mortality rate is not considered to be of toxicological significance.

- While the bodyweight gain in all treated females and in males of the 10 and 100 mg/kg/day groups was similar to that of the control animals, a very slight increase in the bodyweight gain (related to an increase of the same intensity in the food consumption) was noted in the males of the 1000 mg/kg/day group. Throughout the recovery period, the reversibility of the increase in food consumption was assessed but the difference in bodyweight was still observed. Although these changes were very slight, the relationship to the treatment cannot be ruled out.

- No drug-related abnormality was detected in ophthalmological examinations, and no change of toxicological significance was observed in the hematological and blood biochemical parameters, as well as at the urinalysis.

- A slight increase in the net and/or relative liver weight was found in the females of the 100 mg/kg/day group and in the animals of the 1000 mg/kg/ day group. But in the absence of abnormalities at the macroscopic and microscopic examinations, this change was considered to be of no toxicological significance.

- No changes of a toxicological significance were observed at the macroscopic and microscopic examinations.

In conclusion, the administration of the test substance by gavage to the rat for a 90-day period, at the dose levels of 10, 100 and 1000 mg/kg/day induced hyper-salivation in some animals of the high dose level and a very slight increase in the bodyweight gain related to an increase of the same intensity in the food consumption. Throughout the recovery period, the reversibility of the increase in food consumption was assessed but the difference in bodyweight was still noted. No other change with a toxicological significance was observed. The NOEL is 10 mg/kg bw,

 

2) Beagle dog study:

In a subchronic repeated dose toxicity study conducted according to the OECD Guideline 409, groups of 6 (high dose group) and 4 (low and mid dose treatment) male and female Beagle dogs received the test substance by oral administration (gavage) at dosages of 10, 100, or 1000 mg/kg daily in a total volume of 2 ml/kg over a period of 13 weeks followed by a 4 week recovery period. The dose selection was based on the results of a 14-days range-finding toxicity study (CIT, 1989) where no systemic adverse effect was observed at 2000 mg/kg/day during. A control group of further 6 dogs received the vehicle (0.3% carboxymethylcellulose and 0.1% Tween 80 in water). Two males and 2 females of the control and high dose groups were kept for a 4-week recovery period after the termination of the treatment. At the end of the treatment and recovery periods, the animals were sacrificed and the results of the study can be summarized as follows:

- There were no clinical signs which might be related to the treatment with the test substance and no deaths occurred throughout the study.

- At the dose level of 1000 mg/kg/day slight decreases in body weight were observed in 2 males and one female, from week 1 to week 5 for one male and from week 6 or 7 to week 10 for the other animals. 

- A moderate increase in neutrophils was observed in a few males and females of the 1000 mg/kg/day on weeks 4, 8 and 13. Evidence of reversibility was found after the 4-week recovery period.

- A slight to moderate increase in aminotransferase and/or alkaline phosphatase activities was observed in a few males and females from the 100 and 1000 mg/kg/day groups on weeks 4, 8 and 13. These changes were dose-related and evidence of reversibility was found after the 4-week recovery period.

- No abnormalities in organ weights related to the treatment were observed. No macroscopic abnormalities of toxicological significance were found.

- A slight to moderate biliary cell proliferation was found in 3 males and 3 females of the 100 mg/kg/day group and in 3 males and 2 females of the 1000 mg/kg/day group. Biliary cell proliferation is generally a process that reverses slowly, and accordingly, it was present at the end of the 4 -week recovery period.

The liver was considered as the target organ in beagle dogs, and the dose level of 10 mg/kg/day as the No Observable Effect Level (NOEL) under the conditions of the study.

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 the purpose of classification under Regulation (EC) No.1272/2008. Based on the data, classification for repeated dose toxicity is not warranted under Regulation (EC) No.1272/2008.