1,1-dimethoxy-2-phenylethane

Endpoint summary

Description of key information

Oral (OECD 422), rat: NOAEL ≥ 600 mg/kg bw/day

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records

Reference

Endpoint:

short-term repeated dose toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

22 Sep 2016 - 26 Jan 2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

OECD Guideline 422 (Combined Repeated Dose Toxicity Study with the Reproduction / Developmental Toxicity Screening Test)

Version / remarks:

adopted 28 Jul 2015

Deviations:

no

GLP compliance:

yes

Limit test:

no

Species:

rat

Strain:

Sprague-Dawley

Remarks:

Crl:CD(SD), SPF

Details on species / strain selection:

Sprague-Dawley rats are commonly used in both the general systemic toxicity and reproductive and developmental toxicity studies with a large historical control data base. In addition, the rat is a required species in the regulatory guidelines.

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Age at study initiation: 11 weeks (males) and 12 weeks (females)
- Weight at study initiation: 375.8 - 443.3 g (males) and 215.8 - 271.2 g
- Housing: Acclimation, pre-mating and dosing period: 1 animal per cage; Mating: 1:1; Lactation: neonates were kept with the dam; animals were kept in stainless wire mesh cages (260W x 350D x 210H mm) and in polycarbonate cages (260W x 420D x 180H mm)
- Diet: Teklad Certified Irradiated Global 18% Protein Rodent Diet 2918C (Envigo RMS, Inc., USA), ad libitum
- Water: public tap water filtered and irradiated by ultraviolet light, ad libitum
- Acclimation period: 7 or 9 days

DETAILS OF FOOD AND WATER QUALITY: The certificate of feed analysis was provided by the manufacturer. Samples of drinking water are analyzed for specified microorganisms once a month and all environmental contaminants once a year.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20.2 - 23.8
- Humidity (%): 45.3 - 64.7
- Air changes (per hr): 10 - 15
- Photoperiod (hrs dark / hrs light): 12 / 12

Route of administration:

oral: gavage

Vehicle:

corn oil

Details on oral exposure:

PREPARATION OF DOSING SOLUTIONS:
The test substance was mixed with a small amount of vehicle to dissolve using a magnetic stirrer and then, the vehicle was gradually added to yield the desired concentration. The dosing formulations were stored in a refrigerator (4.3 - 5.9 °C). These dosing formulations were used within 7 days.

VEHICLE
- Justification for use and choice of vehicle: Through the preliminary solubility test to determine the solubility and dispersion characteristics of the test substance, corn oil was selected as the vehicle because the test substance was well dissolved in it.
- Amount of vehicle: 5 mL/kg
- Lot/batch no.: MKBV2080V, MKBW9504V

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Analyses of the dosing formulations were conducted using gas chromatography and samples were taken three times from the middle of each dosing formulation prior to dosing and analyzed for verification of dose level concentration. The results of dose concentration analyses were determined to be 98.75 - 102.1%. These results were within the acceptable limits (± 15% of nominal values). As a result of homogeneity and stability analyses conducted the 0.2 and 200 mg/mL dosing solutions were confirmed to be homogenous and stable for 4 h at room temperature and for 7 days under refrigeration.

Duration of treatment / exposure:

Main groups:
males: for 50 days, starting 2 weeks before mating, during mating and 22 days after mating
females: for 2 weeks prior to mating, throughout gestation and for 13 days after delivery up to the day before the scheduled terminal necropsy

Recovery groups:
Males and females of recovery groups were dosed once daily for 50 days. Animals were not mated and were assigned to 2 weeks of recovery period after the completion of administration.

Frequency of treatment:

once daily, 7 days/week

Dose / conc.:

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

Dose / conc.:

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

Dose / conc.:

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

No. of animals per sex per dose:

12 (main groups)
6 (recovery groups; for control and high dose groups)

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: In a previously conducted 2-week repeated oral dose range-finding study, salivation or soiled perineal region was observed in one male and/or one female at 800 mg/kg bw/day. And increases of the absolute and relative liver weights were noted in both sexes at 800 mg/kg bw/day. Therefore, the high dose level was selected at 600 mg/kg bw/day. Then, the mid and low dose levels were selected at 200 and 60 mg/kg bw/day, respectively.

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice daily mortality/viability
- Cage side observations included: All animals were observed for general condition and clinical signs at least once daily throughout the study. Females were also observed for signs of abortion and pre-mature birth.

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: once before the test and once a week throughout the dosing and recovery periods
- Detailed clinical signs included: detailed physical examinations (skin, fur, eyes, mucous membranes, occurrence of secretion and excretion), central and autonomic nervous system effects (lacrimation, piloerection, pupil size, unusual respiratory pattern, etc.), motor activity (Changes in gait, posture and response to handling, and the presence of clonic or tonic movements) and behavior (stereotypies or bizarre behavior)

BODY WEIGHT: Yes
- Time schedule for examinations: Body weights of males of the main groups and animals of both sexes of the recovery groups were recorded just prior to dosing on Day 1, once a week throughout the dosing and recovery periods, the day prior to necropsy and on the day of necropsy (fasted body weights). Body weights of females of the main groups were recorded just prior to dosing on Day 1 (the first day of dosing), once a week throughout the dosing period, on Gestation Days 0, 7, 14 and 20, on Day 0, 4 and 13 postpartum and on the day of necropsy (fasted body weights). Fasted body weights recorded on the day of necropsy were presented, but were not included in the statistical analysis.

FOOD CONSUMPTION:
- Food consumption of males of the main groups and animals of both sexes of the recovery groups was recorded just prior to dosing on Day 0 (one day before first dosing), once a week during the dosing and recovery periods (except during mating) and the day prior to necropsy. Food consumption of females of the main groups was recorded just prior to dosing on Day 0 (one day before first dosing), once a week throughout the dosing period (except during mating), on Days 0, 6, 13 and 19 of gestation, on Days 0, 3 and 12 postpartum and the day prior to necropsy. Residual feed was recorded on the next day. Food consumption was not recorded during mating.

FOOD EFFICIENCY: No

WATER CONSUMPTION: No

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: Yes
- Time schedule for collection of blood: on the day of scheduled necropsy
- Anaesthetic used for blood collection: Yes (isoflurane)
- Animals fasted: Yes
- How many animals: 6 randomly selected males and females from the main groups and all animals from the recovery groups
- Parameters examined: erythrocyte count (RBC), hemoglobin (HGB), hematocrit (HCT), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), platelets (PLT), leukocyte count (WBC), neutrophils (NEU), lymphocytes (LYM), monocytes (MONO), eosinophils (EOS), basophils (BASO), reticulocytes (Reti), prothrombin time (PT), activated partial thromboplastin time (APTT)

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: on the day of scheduled necropsy
- Animals fasted: Yes
- How many animals: 6 randomly selected males and females from the main groups and all animals of the recovery groups
- Parameters examined: alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), blood urea nitrogen (BUN), creatinine (Crea), total bilirubin (T-Bili), total protein (TP), albumin (Alb), globulin (Glo), A/G ratio, glucose (Glu), total cholesterol (T-Chol), triglycerides (TG), glucose (Glu), calcium (Ca), potassium (K), sodium (Na), chloride (Cl)

URINALYSIS: Yes
- Time schedule for collection of urine: 6 males were randomly selected from the main groups in addition to all recovery animals for urinalysis two days before necropsy. Fresh, 3-hour and 24-hour urine samples were collected from the selected animals and analyzed.
- Metabolism cages used for collection of urine: Not specified
- Animals fasted: Animals were fasted during the fresh urine collection, but were allowed free access to drinking water.
- Parameters examined: in fresh urine samples: pH, protein, glucose, bilirubin, occult blood, color and turbidity, sediment; in 24-hour urine samples: urine volume, specific gravity

NEUROBEHAVIOURAL EXAMINATION: Yes
- Time schedule for examinations: The selected animals were examined a few days before necropsy.
- Dose groups that were examined: 6 randomly selected males and females from the main groups and all animals of the recovery groups
- Battery of functions tested: pinna reflex, auditory (sound) reflex, corneal reflex, pupillary reflex, grip strength test, motor activity test

IMMUNOLOGY: No

OTHER:
- Thyroid hormone analysis: Serum samples from all adult males of the main group were taken at termination and analyzed for total thyroxine (T4). Animals were fasted for more than 18 hours before necropsy and anesthetized with isoflurane. Blood samples were collected from abdominal aorta in a vacutainer.

Sacrifice and pathology:

GROSS PATHOLOGY: Yes
All males of the main group were sacrificed on Day 51 and females of the main group were sacrificed on Day 14 postpartum. All animals of the recovery group were sacrificed 2 weeks after final dosing. Complete gross postmortem examinations were conducted on all animals including the external and internal surfaces. All grossly visible abnormalities were recorded.

ORGAN WEIGHTS: Yes
Paired organs were weighed together. Animals were fasted overnight prior to necropsy and body weights were recorded on the day of necropsy. Organs were weighed and organ-to-body weight ratios were calculated. The testes and epididymides of all adult males were weighed. 6 males and 6 females were randomly selected from the main study animals in addition to all recovery animals for necropsy. Following organs were weighed: brain, heart, liver, thymus, spleen, thyroid (weight after fixation), kidneys, adrenals, ovaries, uterus

HISTOPATHOLOGY: Yes
Tissue preservation and slide preservation
6 males and 6 females were randomly selected from the main groups in addition to all recovery animals for tissue preparation. The testes, epididymides and eyes with optic nerves were fixed in Davidson´s fixative. All other tissues were preserved in 10% neutral buffered formalin.

For histopathological examination, the preparation of specimens of the following organs and tissues was carried out (remaining organs and tissues were preserved in 10% neutral buffered formalin): brain, pituitary, thymus, lung with bronchi, trachea, thyroid, esophagus, heart, liver, spleen, kidneys, adrenals, stomach, duodenum, jejunum, ileum, cecum, colon, rectum, testes, epididymides, prostate, seminal vesicles with coagulatins glands, ovaries, uterus and cervix, vagina, submandibular lymph node, mesenteric lymph node, bone marrow (femur and sternum), spinal cord, sciatic nerve, eyes and optic nerves, urinary bladder, organs with gross lesions

Besides, from all animals except for six females and males in the main group, the following organs and tissues were harvested and preserved: brain, pituitary, heart, thymus, thyroid, liver, spleen, kidneys, adrenals, prostate, testes, epididymides, ovaries, uterus and cervix, vagina

Histopathological examinations were conducted as follows:
- 6 males and females from the control, low, mid and high dose group (especially, focused on spermatogenesis and interstitial testicular cell structure)
- All tissues from animals found dead or killed in a moribund condition
- All gross, macroscopic lesions
- Target organs noted at the high dose were examined for the recovery group (liver and stomach)

Statistics:

The statistical analysis of this study was conducted using the SAS program (SAS® 9.3, SAS Institute Inc., U.S.A.). For the data including body weights, food consumption, estrous cycle, mating period, gestation period, urine volume, hematology and clinical chemistry parameters, organ weights, sensory function and motor activity, the Bartlett test was conducted to test for homogeneity of variance (significance level: 0.05). One-way analysis of variance (ANOVA) test was employed on homogeneous data, then if significant (significance level: 0.05), followed by Dunnett’s test for multiple comparisons (significance levels: 0.05 and 0.01, two-tailed). Kruskal-Wallis test was employed on heterogeneous data, then if significant (significance level: 0.05), Steel’s test was performed for multiple comparisons (significance levels: 0.05 and 0.01, two-tailed). The data of mating index, fertility index and other data associated with gestation were analyzed utilizing Fisher’s exact test (significance levels: 0.05 and 0.01).
For the data of recovery groups, Folded-F test was employed to test homogeneity of variance (significance level: 0.05, two-tailed). Student t-test was employed for homogeneity, but if overruled, Aspin-Welch t-test was applied (significance levels: 0.05 and 0.01, two-tailed).

Clinical signs:

effects observed, non-treatment-related

Description (incidence and severity):

In animals of the main groups at 600 mg/kg bw/day, salivation was observed in 3 males from Day 21 and in 2 females from Day 3 - 20 of gestation. However, salivation was considered to have little toxicological significance since it was caused by physicochemical characteristics.
In the main group, two dams of the 60 mg/kg bw/day group were found in a moribund state on Day 7 postpartum after soiled perineal region, reddish tear and inanimation were observed. However, these moribund dams were considered to be incidental because there was no dose-dependency.
At Week 6 (after parturition), one female showed a reduced grooming. This animal was found in a moribund state a few days after the examination.
In the recovery groups, no clinical signs were observed in males and females.

Mortality:

mortality observed, non-treatment-related

Description (incidence):

A total of 2 females in the 60 mg/kg bw/day group were sacrificed in a moribund state on Day 7 postpartum. In the main and recovery groups, all other animals survived the duration of the study.

Body weight and weight changes:

no effects observed

Description (incidence and severity):

No test substance-related effects on the body weight changes were noted in both sexes at 60, 200 and 600 mg/kg bw/day in the main and recovery groups.

Food consumption and compound intake (if feeding study):

effects observed, non-treatment-related

Description (incidence and severity):

A statistically significant increase in food consumption was noted in females at 200 mg/kg bw/day in the main group on Day 13 postpartum. However, this statistical significance was not considered to be a test substance-related change since it was not related to the body weight changes.
Two moribund dams showed very low food consumption after parturition.

Food efficiency:

not examined

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

not examined

Ophthalmological findings:

not examined

Haematological findings:

no effects observed

Description (incidence and severity):

No adverse effects were observed in any animal in the main and recovery groups. Other statistical significances were considered not to be test substance-related changes because they were small magnitude and the values were within the range of historical reference data.

Clinical biochemistry findings:

no effects observed

Description (incidence and severity):

No adverse effects were observed in any animal in the main and recovery groups. Other statistical significances were considered not to be test substance-related changes because they were small magnitude and the values were within the range of historical reference data.

Urinalysis findings:

no effects observed

Description (incidence and severity):

In males of the main and recovery groups, no effects were noted in the test substance dose groups.

Behaviour (functional findings):

not examined

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

In the main group, the absolute organ weight of the testis was significantly decreased in males at 600 mg/kg bw/day. The absolute and/or relative organ weights of the liver were significantly increased in males at 600 mg/kg bw/day and in females at 200 and 600 mg/kg bw/day. Other statistical significances in the absolute and/or relative organ weights were considered not to be test substance-related effects because they were small magnitude and/or the values were within the range of historical reference data.

Gross pathological findings:

effects observed, non-treatment-related

Description (incidence and severity):

Macroscopic examination at necropsy of the two dams sacrificed in a moribund state revealed irregular surface of the kidney in one dam and dark-brown discoloration of the kidney in the other dam. Small spleen and thymus were also observed in all moribund dams.
Macroscopic examination at necropsy of surviving animals did not reveal treatment-related changes. The other macroscopic findings were considered to be incidental and not related to the test substance since the findings were observed a single case or did not show a dose-response relationship.

Neuropathological findings:

effects observed, non-treatment-related

Description (incidence and severity):

No test substance-related effects on auditory reflex, pinna reflex, pupillary reflex and corneal reflex were observed in animals of both sexes in the main and recovery groups when compared to the control group.
In the main groups, there were no test substance-related effects in the grip strength test on both sexes when compared to the control group. In spontaneous motor activity, a statistically significant decrease in vertical count was noted in males at 60 and 200 mg/kg bw/day. However, this statistical significance was not considered to be a test substance-related change because it was small magnitude and there was no dose dependency.
In the recovery groups, there were no test substance-related effects in the grip strength test on both sexes when compared to the control group. In spontaneous motor activity, a statistically significant decreased in ambulatory count was noted in males at 600 mg/kg bw/day. However, this change had little toxicological meaning because the total count did not show a significant change.

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

In one moribund dam in the 60 mg/kg bw/day group, the irregular surface of the kidney corresponded to microscopically observed tubular degeneration at moderate severity. The dark-brown discoloration of the kidney in the other dam corresponded to orange-colored cast at moderate severity in the tubular lumen and tubular degeneration at severe severity. Small spleen and thymus were in concordance with atrophy at moderate/severe severity.
Orange-colored cast in the renal tubules is generally indicative of hemoglobin cast. This finding might imply hemolysis along with increased pigmentation in the spleen. The renal findings including tubular degeneration could affect the moribund state of the dams.
However, the administration of the test substance was not considered to contribute to the moribund condition since the renal findings were observed in the 60 mg/kg bw/day group only. As the dams showed poor condition/stress-related observations (correlated with microscopically observed adrenal cortical hypertrophy, lymphoid atrophy in the spleen, thymus and lymph nodes) after delivery, exacerbated condition with the renal findings in dams could be attributed to uncertain complications of labor/delivery. All microscopic findings seen in other organs and tissues were considered to be incidental and of no toxicological significance
In surviving animals the liver showed a centrilobular hypertrophy of hepatocytes in both sexes at 200 and 600 mg/kg bw/day. All animals of the 600 mg/kg bw/day group recovered at the end of the 2-week recovery period. Centrilobular hepatocellular hypertrophy was regarded as adaptive response to the test substance and it was considered not to be harmful to the animals since it was not accompanied with inflammation, degeneration or necrosis. All other microscopic findings seen in various organs and tissues were considered to be spontaneous or incidental, and to be unrelated to the test substance.

Histopathological findings: neoplastic:

no effects observed

Other effects:

no effects observed

Description (incidence and severity):

- Thyroid hormone analysis:
There were no adverse effects in total thyroxine (T4) level in males of main group at 60, 200 and 600 mg/kg bw/day.

Dose descriptor:

NOAEL

Effect level:

>= 600 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: no systemic adverse effects up to and including the highest dose tested

Critical effects observed:

no

Table 1. Absolute and relative liver weights. (n=6)

	Dose level (mg(kg bw)
Liver weight	0		60		200		600
	Male	Female	Male	Female	Male	Female	Male	Female
Absolute (g)	14.32 ± 1.12	9.37 ± 0.51	14.03 ± 1.19	9.42 ± 0.49	14.63 ± 1.62	10.91 ± 0.95**	15.81 ± 2.29	11.50 ± 0.77**
Relative (g/100 g bw)	2.57 ± 0.09	3.28 ± 0.19	2.65 ± 0.19	3.30 ± 0.20	2.70 ± 0.28	3.63 ± 0.06#	2.97 ± 0.33*	4.00 ± 0.05#

Significantly different from control group: *p<0.05, **p<0.01(by Dunnett's test); #p<0.05 (by Steel´s test)

Table 2. Incidence of treatment-related microscopic findings

	Dose level (mg/kg bw/day)
	0		60		200		600
	Male	Female	Male	Female	Male	Female	Male	Female
Liver
Hypertrophy, hepatocellular, centrilobular (minimal)	0/6	0/6	0/6	0/6	1/6	2/6	3/6	4/6

 

Conclusions:

Based on the results of this study, the NOAEL for systemic toxicity was ≥ 600 mg/kg bw/day for males and females.

Executive summary:

The test substance was tested in a combined repeated dose oral toxicity study with the reproduction/developmental toxicity screening study according to OECD Guideline 422 and in compliance with GLP (2015). Twelve Sprague Dawley rats per sex and dose were treated via gavage with test substance at doses of 60, 200 and 600 mg/kg bw/day, respectively. The control group received the vehicle corn oil. Additionally, a recovery group of 6 rats per sex was allocated to the control and high dose group. Males were treated for 50 days starting 2 weeks before the mating period, during 2-week mating period and 22 days after mating. Females were treated for 2 weeks prior to mating, throughout gestation and for 13 days after delivery up to the day before the scheduled terminal necropsy. The doses were selected on the basis of a 2-week repeated oral dose range-finding toxicity study in which salivation and soiled perineal region in one male and one female and increases of absolute and relative liver weights of both sexes were observed at 800 mg/kg bw/day. No test substance-related effects were observed in animals at 600 mg/kg bw/day.

In the main study, two females (dams) of the 60 mg/kg bw/day group were sacrificed in a moribund state on Day 7 postpartum. However, these moribund animals were considered to be incidentalsince there was no dose-dependency regarding these findings which were observed solely at the lowest dose level of 60 mg/kg bw/day. All males of the main groups and all animals of both sexes in the recovery groups survived the duration of the study. Salivation was observed in three males and two females at 600 mg/kg bw/day, but was not considered to have toxicological significance. In the moribund dams, tubular degeneration and orange-colored cast in the renal tubules were observed. However, these were not considered to be test substance-related effects since the lesions were observed only at 60 mg/kg bw/day. No test substance-related adverse effects were noted with regard to body weights, food consumption, sensory function, motor activity, urinalysis, hematology, blood chemistry and thyroid hormone analysis.

In the main group, the absolute organ weight of the testis was significantly decreased in males at 600 mg/kg bw/day. However, it was considered to have little toxicological significance since there were no test substance-related histopathological changes in the testis and epididymis.

The absolute and/or relative organ weights of the liver were significantly increased in males at 600 mg/kg bw/day and in females at 200 and 600 mg/kg bw/day. Hepatocellular hypertrophy was observed in surviving animals of both sexes at 200 and 600 mg/kg bw/day. Centrilobular hepatocellular hypertrophy was regarded as adaptive response to the test substance and it was considered not to be harmful to the animals since it was not accompanied with inflammation, degeneration or necrosis.

Based on these results, the NOAEL for the test substance for systemic toxicity was considered to be≥600 mg/kg bw/day.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

600 mg/kg bw/day

Study duration:

subacute

Species:

rat

Quality of whole database:

The available information comprises an adequate and reliable study (Klimisch score 1), and is thus sufficient to fulfil the standard information requirements set out in Annex VIII, 8.6, of Regulation (EC) No 1907/2006.

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

The test substance was tested in a combined repeated dose oral toxicity study with the reproduction/developmental toxicity screening study according to OECD Guideline 422 and in compliance with GLP (2015). Twelve Sprague Dawley rats per sex and dose were treated via gavage with test substance at doses of 60, 200 and 600 mg/kg bw/day, respectively. The control group received the vehicle corn oil. Additionally, a recovery group of 6 rats per sex was allocated to the control and high dose group. Males were treated for 50 days starting 2 weeks before the mating period, during 2-week mating period and 22 days after mating. Females were treated for 2 weeks prior to mating, throughout gestation and for 13 days after delivery up to the day before the scheduled terminal necropsy. The doses were selected on the basis of a 2-week repeated oral dose range-finding toxicity study in which salivation and soiled perineal region in one male and one female and increases of absolute and relative liver weights of both sexes were observed at 800 mg/kg bw/day. No test substance-related effects were observed in animals at 600 mg/kg bw/day.

In the main study, two females (dams) of the 60 mg/kg bw/day group were sacrificed in a moribund state on Day 7 postpartum. However, these moribund animals were considered to be incidental since there was no dose-dependency regarding these findings which were observed solely at the lowest dose level of 60 mg/kg bw/day. All males of the main groups and all animals of both sexes in the recovery groups survived the duration of the study. Salivation was observed in three males and two females at 600 mg/kg bw/day, but was not considered to have toxicological significance. In the moribund dams, tubular degeneration and orange-colored cast in the renal tubules were observed. However, these were not considered to be test substance-related effects since the lesions were observed only at 60 mg/kg bw/day. No test substance-related adverse effects were noted with regard to body weights, food consumption, sensory function, motor activity, urinalysis, hematology, blood chemistry and thyroid hormone analysis.

In the main group, the absolute organ weight of the testis was significantly decreased in males at 600 mg/kg bw/day. However, it was considered to have little toxicological significance since there were no test substance-related histopathological changes in the testis and epididymis.

The absolute and/or relative organ weights of the liver were significantly increased in males at 600 mg/kg bw/day and in females at 200 and 600 mg/kg bw/day. Hepatocellular hypertrophy was observed in surviving animals of both sexes at 200 and 600 mg/kg bw/day. Centrilobular hepatocellular hypertrophy was regarded as adaptive response to the test substance and it was considered not to be harmful to the animals since it was not accompanied with inflammation, degeneration or necrosis.

Based on these results, the NOAEL for the test substance for systemic toxicity was considered to be ≥ 600 mg/kg bw/day.

Justification for classification or non-classification

The available data on repeated oral dose toxicity of the test substance do not meet the criteria for classification according to Regulation (EC) 1272/2008, and are therefore conclusive but not sufficient for classification.