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Toxicological information

Toxicity to reproduction

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Administrative data

Endpoint:
screening for reproductive / developmental toxicity
Type of information:
experimental study
Adequacy of study:
key study
Study period:
April 2008 - August 2010
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Cross-referenceopen allclose all
Reason / purpose:
reference to same study
Reference
Endpoint:
short-term repeated dose toxicity: oral
Type of information:
experimental study
Adequacy of study:
key study
Study period:
April 2008 - August 2010
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Reason / purpose:
reference to same study
Reason / purpose:
reference to same study
Qualifier:
according to
Guideline:
OECD Guideline 422 (Combined Repeated Dose Toxicity Study with the Reproduction / Developmental Toxicity Screening Test)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Limit test:
no
Species:
rat
Strain:
Sprague-Dawley
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Janvier, Le Genest-Saint-Isle, France
- Age at study initiation: 10 weeks old
- Weight at study initiation: 402 - 454 g (males) / 244 - 285 g (females)
- Fasting period before study: no
- Housing: individual (except during pairing), in wire-mesh cages (43 x 21.5 x 18 cm) or polycarbonate cages (43 x 21.5 x 20 cm) for females during lactation
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: 6 days

ENVIRONMENTAL CONDITIONS
- Temperature: 22 ± 2°C
- Humidity: 50 ± 20%
- Air changes: about 12 per hr
- Photoperiod: 12 hrs dark / 12 hrs light (7.00 am - 7.00 pm)

IN-LIFE DATES: From 14 May 2008 To 14 July 2008
Route of administration:
oral: gavage
Vehicle:
methylcellulose
Remarks:
0.5% solution
Details on oral exposure:
PREPARATION OF DOSING SOLUTIONS:
- Test item ground to fine powder using mortar and pestle, suspended in vehicle and homogenized by magnetic stirrer
- Dosing solutions prepared for use for up to 12 days and stored in brown flasks at +4°C, protected from light, prior to use

VEHICLE
- Justification for use and choice of vehicle (if other than water): appropriate for oral suspensions
- Concentration in vehicle: 30, 90 or 200 mg/mL
- Amount of vehicle (if gavage): 5 mL/kg
- Lot/batch no. (if required): Sigma batches 017K0052 and 066K0129 (methylcellulose)
- Concentration: 0.5% in water
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
During the pre-study period, the homogeneity, stability and concentration of two dosage forms prepared at low and high concentrations (33.6 and 230 mg/mL) were checked using ICP-OES (Inductively Coupled Plasma-Optical Emission Spectrometry) after validation of the analytical method. The results showed acceptable homogeneity and stability of both concentrations over 12 days of storage at +4°C protected from light.

During the study, the concentration of the test item (0, 33.6, 101.7 and 230 mg/mL in week 1 and 0, 30, 90 and 200 mg/mL in week 6) and homogeneity of the dosage forms were determined in samples of each control and test item dosage form prepared for use in weeks 1 and 6. The results showed acceptable homogeneity and concentration of all dosage forms analyzed. Precision (RSD ≤ 10%) and accuracy (100 ± 10%) of the method were found to be satisfactory. The homogeneity of the dosage form prepared for week 6 at 200 mg/mL was slightly outside the acceptance criteria with a RSD of 12.8% but this was considered to have no impact on the validity of the study.
Duration of treatment / exposure:
- Males: 15 days before mating, during mating (up to 3 weeks), until euthanasia (4 weeks total)
- Females: 15 days before mating, during mating (up to 3 weeks), during pregnancy, during lactation, until day 5 post partum inclusive
Frequency of treatment:
Once daily, 7 days a week
Dose / conc.:
0 mg/kg bw/day (nominal)
Dose / conc.:
168 mg/kg bw/day (nominal)
Remarks:
nominal up until day 3, due to an error of density measurement
Dose / conc.:
509 mg/kg bw/day (nominal)
Remarks:
nominal up until day 3, due to an error of density measurement
Dose / conc.:
1 150 mg/kg bw/day (nominal)
Remarks:
nominal up until day 3, due to an error of density measurement
Dose / conc.:
150 mg/kg bw/day (nominal)
Remarks:
nominal from day 4 up to the end of the study
Dose / conc.:
450 mg/kg bw/day (nominal)
Remarks:
nominal from day 4 up to the end of the study
Dose / conc.:
1 000 mg/kg bw/day (nominal)
Remarks:
nominal from day 4 up to the end of the study
No. of animals per sex per dose:
10
Control animals:
yes, concurrent vehicle
Details on study design:
- Dose selection rationale: on the basis of a previous 10-day dose-range finding study (CIT No. 33178 TSR) at the same dose levels which elicited no treatment-related effects
- Rationale for animal assignment (if not random): computerized stratification procedure so that the average body weight of each group was similar
Positive control:
Not included
Observations and examinations performed and frequency:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: at least twice daily (morbidity and mortality) or once daily (clinical signs)

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: once before beginning of treatment period and once weekly during treatment period
Observations included (but were not limited to) changes in the skin, fur, eyes, mucous membranes, occurrence of secretions and excretions and autonomic activity (e.g. lachrymation, piloerection, pupil size, unusual respiratory pattern). Changes in gait, posture and response to handling as well as the presence of clonic or tonic movements, stereotypes (e.g. excessive grooming, repetitive circling) or bizarre behavior (e.g. self-mutilation, walking backwards) were also recorded.

BODY WEIGHT: Yes
- Time schedule for examinations:
Males: on first day of treatment and then once weekly
Females: on first day of treatment and then once weekly until mated, and on days 0, 7, 14 and 20 post coitum and days 1 and 5 post partum

FOOD CONSUMPTION: Yes
- Time schedule for examinations:
Males: once weekly over 7-day periods from first day of dosing
Females: once weekly over 7-day periods from first day of dosing through gestation and lactation
Not recorded during pairing period

WATER CONSUMPTION: No

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: Yes
- Time schedule for collection of blood: just before necropsy
- Anaesthetic used for blood collection: Yes (isoflurane)
- Animals fasted: Yes (overnight for at least 14 hours)
- How many animals: first 5 males and 5 females to deliver in each group
- Parameters examined: erythrocytes, hemoglobin, mean cell volume, packed cell volume, mean cell hemoglobin concentration, mean cell hemoglobin, thrombocytes, leucocytes, differential white cell count with cell morphology, reticulocytes, prothrombin time, activated partial thromboplastin time, fibrinogen

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: just before necropsy
- Anaesthetic used for blood collection: Yes (isoflurane)
- Animals fasted: Yes (overnight for at least 14 hours)
- How many animals: first 5 males and 5 females to deliver in each group
- Parameters examined: sodium, potassium, chloride, calcium, inorganic phosphorus, glucose, urea, creatinine, total bilirubin, total proteins, albumin, albumin/globulin ratio, total cholesterol, triglycerides, alkaline phosphatase, aspartate aminotransferase, alanine aminotransferase, bile acid

URINALYSIS: No

NEUROBEHAVIOURAL EXAMINATION: Yes
- Time schedule for examinations: once at the end of treatment period (day 5 post partum for females)
- Dose groups that were examined: all groups (first 5 males and 5 females to deliver)
- Battery of functions tested: sensory activity / grip strength / motor activity / other: standard reflexes and responses, rectal temperature

Details:
The FOB included a detailed clinical examination, measurement of reactivity to manipulation or to different stimuli and motor activity. The animals were randomized in order to ensure "blind" evaluation. All animals were observed in the cage, in the hand and in the standard arena.
The following parameters were assessed and graded:
- "touch escape" or ease of removal from the cage,
- in the hand: fur appearance, salivation, lachrymation, piloerection, exophthalmos, reactivity to handling, pupil size (presence of myosis or mydriasis),
- in the standard arena (2-minute recording): grooming, palpebral closure, defecation, urination, tremors, twitches, tonic and clonic convulsions, gait, arousal (hypo- and hyper-activity), posture, stereotypy, behavior, breathing, ataxia and hypotonia.
Then, the following parameter measurements, reflexes and responses were recorded:
- touch response,
- forelimb grip strength,
- pupillary reflex,
- visual stimulus response,
- auditory startle reflex,
- tail pinch response,
- righting reflex,
- landing foot splay,
- at the end of observation: rectal temperature.
Finally, motor activity of all animals was measured once by automated infra-red sensor equipment over a 60-minute period.

OTHER: No other general toxicity parameter
Sacrifice and pathology:
GROSS PATHOLOGY: Yes
- Organ weights (F0 generation, see table below)
- Macroscopic post-mortem examination (F0 generation)

HISTOPATHOLOGY: Yes
On all tissues specified (see table below), macroscopic lesions and females sacrificed because of absence of delivery to investigate possible causes
Statistics:
- Comparison of mean values by one-way variance analysis and Dunnett's test
- Percentage values compared by Fisher's exact probability test
- Specific sequences of tests used for clinical chemistry and organ weight data
Clinical signs:
no effects observed
Description (incidence and severity):
Isolated and non-dose-related incidences of soft feces, loud breathing, chromorhinorrhea and reflux at dosing were observed in all groups treated with Cerium oxide. Generally only one animal was affected and the signs were short-lived. It was considered that none of these represented signs of toxicity of the test item.
In addition, hairloss and cutaneous lesions were observed in the control group and the groups treated at 150 or 450 mg/kg/day. These signs are commonly observed in laboratory rats of this strain and are considered not to be related to treatment with the test item.
Mortality:
no mortality observed
Description (incidence):
There were no unscheduled deaths during the study.
Body weight and weight changes:
no effects observed
Description (incidence and severity):
There were no effects of treatment with the test item on mean male or female body weight or body weight gains during the premating, gestation or lactation phases.
The female group treated at 450 mg/kg/day had a slightly lower mean body weight gain over the gestation period when compared with the controls but the difference was mainly due to one female with a low body weight gain which skewed the group mean.
Food consumption and compound intake (if feeding study):
no effects observed
Description (incidence and severity):
There were no effects of treatment with the test item on mean male or female food consumption.
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):
The males treated at 450 mg/kg/day showed increases when compared with the controls for red blood cell count, hemoglobin level and hematocrit. These differences were not statistically significant and were not observed at 150 or 1000 mg/kg/day. It was considered that the differences did not represent an effect of treatment with the test item.
The female group treated at 1000 mg/kg/day showed a statistically significant increase in hemoglobin concentration and monocyte count. Neither was observed in the males treated at the same dose-level and no related parameters were affected. It was considered that these differences were not treatment-related.
Clinical biochemistry findings:
no effects observed
Description (incidence and severity):
The male group treated at 1000 mg/kg/day had increased concentrations of creatinine and albumin (three or four of the males treated at 1000 mg/kg/day had values outside the control range). Related parameters (for example urea and total proteins) were not affected and the female group treated at the same dose-level did not show any differences to controls. It was considered that neither of these parameters had been affected by treatment with the test item.
Urinalysis findings:
not examined
Behaviour (functional findings):
no effects observed
Description (incidence and severity):
The first five males and the first five delivered females of each group treated with Cerium oxide were assessed for Functional Observation Battery. All groups achieved normal scores compared to the controls for touch escape, reactivity to handling, touch response, fur appearance, pupil size, grooming, palpebral closure, gait, posture, breathing, defecation, urination, visual stimulus response, pupillary reflex, auditory startle reflex, tail pinch response, forelimb grip strength, righting reflex, landing foot splay and rectal temperature.
All animals had absence of salivation, lacrimation, piloerection, exophthalmos, tremors, twitches, clonic or tonic convulsions, hyperactivity, hypoactivity, ataxia, hypotonia, stereotypy and abnormal behavior.
There were no marked differences in the mean number of movements made by the assessed males or females of all test item-treated groups when compared with the controls. No dose-relationship was observed and the small increases and decreases observed in all test item-treated groups were considered not to represent an effect of treatment with the test item.
Immunological findings:
not examined
Organ weight findings including organ / body weight ratios:
no effects observed
Description (incidence and severity):
Organ weight changes (principally of adrenals, spleen and thymus) were considered not to be related to the test item as they were small in amplitude, had no gross or microscopic correlates, were not dose-related in magnitude, and/or were not consistent for the sexes.
Gross pathological findings:
no effects observed
Description (incidence and severity):
In a few rats given the test item, intestinal distension with gas was described in the cecum (1/10 high-dose males), colon (2/10 high-dose and 1/10 low-dose males), and ileum (2/10 high-dose and 1/10 low-dose males). In the absence of microscopic correlates, this finding was considered not to be of to xicological significance.
In one high-dose female there was a dilatation of the cervix associated with serous contents in the uterine horns. These findings were explained at microscopic examination by the presence of a congenital anomaly involving the cervix and distal vagina.
The other macroscopic findings had no histologic correlates or correlated with common histologic findings in control rats, and were considered to be incidental. One mid-dose female showed a thymic mass which correlated with a chronic abscess at microscopic examination.
Neuropathological findings:
not examined
Histopathological findings: non-neoplastic:
no effects observed
Description (incidence and severity):
A detailed, stage-aware qualitative evaluation of the testes was conducted in control and high dose males.
There were no microscopic findings related to the test item administration.
In the few low-, mid-, and high-dose females which were sacrificed because of no delivery, no estrous cycle abnormalities were found at microscopic examination of the genital organs. However, in one high-dose female, a congenital anomaly involving the cervix and distal vagina explained the absence of mating/pregnancy. Both the cervix and the distal vagina were dilated with presence of a large mucosal protrusion in the cavity.
Histopathological findings: neoplastic:
no effects observed
Key result
Dose descriptor:
NOEL
Remarks:
parental toxicity
Effect level:
1 000 mg/kg bw/day (nominal)
Sex:
male/female
Basis for effect level:
other: No relevant effects up to highest dose tested
Critical effects observed:
not specified
Conclusions:
No significant systemic toxicity was observed up to the highest tested dose, i.e. 1000 mg/kg b.w./d. The NOEL for parental toxicity is 1000 mg/kg b.w./d.
Executive summary:

In an OECD TG 422-compliant study, the potential general and reproductive or developmental toxicity of Cerium Oxide were tested following daily oral administration by gavage to 10-week old Sprague-Dawley rats (10/sex) from 2 weeks before mating, through mating and, for the females, through gestation until day 5 post partum, at the dose levels of 0 (0.5% aqueous methylcellulose solution), 150, 450 or 1000 mg/kg (except for the first 3 days of dosing when an error in density measurements resulted in dose levels of slight overdosing at 168, 509 or 1150 mg/kg, respectively).

No unscheduled deaths or treatment-related clinical signs occurred during the study. There were no effects on body weight, body weight gain or food consumption at any dose level. The Functional Observational Battery assessment, hematology and blood chemistry parameters revealed no treatment-related effects. There were no relevant differences from controls for pairing, mating, fertility and delivery parameters. Pups showed no effects of treatment on survival or body weight performance. Macroscopic and microscopic examinations at necropsy did not reveal any treatment-related findings and there were no treatment-related changes in organ weights.

The NOELs for parental toxicity, for reproductive performance (mating and fertility) and for toxic effects on progeny were therefore all considered to be 1000 mg/kg.

No classification for repeat-dose toxicity or reproductive or developmental toxicity is warranted based on the absence of relevant effects in this study, according to the criteria of Annex VI Directive 67/548/EEC or UN/EU GHS.

This study is classified as acceptable. It satisfies the OECD 422 guideline requirements on repeated dose toxicity testing and reproduction/developmental toxicity screening.

Reason / purpose:
reference to same study
Reference
Endpoint:
developmental toxicity
Remarks:
screening for reproductive / developmental toxicity
Type of information:
experimental study
Adequacy of study:
key study
Study period:
April 2008 - August 2010
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Reason / purpose:
reference to same study
Reason / purpose:
reference to same study
Qualifier:
according to
Guideline:
other: OECD Guideline 422 (Combined Repeated Dose Toxicity Study with the Reproduction / Developmental Toxicity Screening Test)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Limit test:
no
Species:
rat
Strain:
Sprague-Dawley
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Janvier, Le Genest-Saint-Isle, France
- Age at study initiation: 10 weeks old
- Weight at study initiation: 402 - 454 g (males) / 244 - 285 g (females)
- Fasting period before study: no
- Housing: individual (except during pairing), in wire-mesh cages (43 x 21.5 x 18 cm) or polycarbonate
cages (43 x 21.5 x 20 cm) for females during lactation
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: 6 days

ENVIRONMENTAL CONDITIONS
- Temperature: 22 ± 2°C
- Humidity: 50 ± 20°C
- Air changes: about 12 per hr
- Photoperiod: 12 hrs dark / 12 hrs light (7.00 am - 7.00 pm)

IN-LIFE DATES: From 14 May 2008 To 14 July 2008
Route of administration:
oral: gavage
Details on exposure:
PREPARATION OF DOSING SOLUTIONS:
- Test item ground to fine powder using mortar and pestle, suspended in vehicle and homogenized by magnetic stirrer
- Dosing solutions prepared for use for up to 12 days and stored in brown flasks at +4°C, protected from light, prior to use

VEHICLE
- Justification for use and choice of vehicle (if other than water): appropriate for oral suspensions
- Concentration in vehicle: 30, 90 or 200 mg/mL
- Amount of vehicle (if gavage): 5 mL/kg
- Lot/batch no. (if required): Sigma batches 017K0052 and 066K0129 (methylcellulose)
- Purity: 0.5%
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
During the pre-study period, the homogeneity, stability and concentration of two dosage forms prepared at low and high concentrations (33.6 and 230 mg/mL) were checked using ICP-OES (Inductively Coupled Plasma-Optical Emission Spectrometry) after validation of the analytical method. The results showed acceptable homogeneity and stability of both concentrations over 12 days of storage at +4°C protected from light.

During the study, the concentration of the test item (0, 33.6, 101.7 and 230 mg/mL in week 1 and 0, 30, 90 and 200 mg/mL in week 6) and homogeneity of the dosage forms were determined in samples of each control and test item dosage form prepared for use in weeks 1 and 6. The results showed acceptable homogeneity and concentration of all dosage forms analyzed. Precision (RSD ≤ 10%) and accuracy (100 ± 10%) of the method were found to be satisfactory. The homogeneity of the dosage form prepared for week 6 at 200 mg/mL was slightly outside the acceptance criteria with a RSD of 12.8% but this was considered to have no impact on the validity of the study.
Details on mating procedure:
- Impregnation procedure: cohoused
- If cohoused:
- M/F ratio per cage: one female was placed with one male
- Length of cohabitation: each female was placed with the same male until mating occurs or 14 days had elapsed. .
- After 14 days of unsuccessful pairing replacement of first male by another male with proven fertility for 7 days.
- Further matings after two unsuccessful attempts: no
- Proof of pregnancy: vaginal plug or sperm in vaginal smear; confirmation of mating was made in the morning, every day up to proof of mating.
- After successful mating each pregnant female was caged (how): individually
- Any other deviations from standard protocol: no
Duration of treatment / exposure:
- Males: 15 days before mating, during mating (up to 3 weeks), until euthanasia (4 weeks total)
- Females: 15 days before mating, during mating (up to 3 weeks), during pregnancy, during lactation, until day 5 post partum inclusive
Frequency of treatment:
Once daily, 7 days a week
Dose / conc.:
0 mg/kg bw/day
Dose / conc.:
168 mg/kg bw/day (nominal)
Remarks:
Basis: nominal, up until day 3 due to an error of density measurement
Dose / conc.:
509 mg/kg bw/day (nominal)
Remarks:
Basis: nominal, up until day 3 due to an error of density measurement
Dose / conc.:
1 150 mg/kg bw/day (nominal)
Remarks:
Basis: nominal, up until day 3 due to an error of density measurement
Dose / conc.:
150 mg/kg bw/day (nominal)
Remarks:
Basis: nominal from day 4 on
Dose / conc.:
450 mg/kg bw/day (nominal)
Remarks:
Basis: nominal from day 4 on
Dose / conc.:
1 000 mg/kg bw/day (nominal)
Remarks:
Basis: nominal from day 4 on
No. of animals per sex per dose:
10
Control animals:
yes, concurrent vehicle
Details on study design:
- Dose selection rationale: on the basis of a previous 10-day dose-range finding study (CIT No. 33178 TSR) at the same dose levels
- Rationale for animal assignment (if not random): computerized stratification procedure so that the average body weight of each group was similar
Maternal examinations:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: at least twice daily (morbidity and mortality) or once daily (clinical signs)

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: once before beginning of treatment period and once weekly during treatment period
Observations included (but were not limited to) changes in the skin, fur, eyes, mucous membranes, occurrence of secretions and excretions and autonomic activity (e.g. lachrymation, piloerection, pupil size, unusual respiratory pattern). Changes in gait, posture and response to handling as well as the presence of clonic or tonic movements, stereotypes (e.g. excessive grooming, repetitive circling) or bizarre behavior (e.g. self-mutilation, walking backwards) were also recorded.

BODY WEIGHT: Yes
- Time schedule for examinations: on first day of treatment and then once weekly until mated, and on days 0, 7, 14 and 20 post-coitum and days 1 and 5 post partum

FOOD CONSUMPTION: Yes
- Time schedule for examinations: once weekly over 7-day periods from first day of dosing through gestation and lactation; not recorded during pairing period

WATER CONSUMPTION: No

POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on on day 6 post-partum
- Organs examined: all the tissues listed in the Table below for the first five females of the control and high-dose groups (groups 1 and 4) sacrificed as scheduled and all macroscopic lesions

OTHER:
HAEMATOLOGY: Yes
- Time schedule for collection of blood: just before necropsy
- Parameters examined: erythrocytes, hemoglobin, mean cell volume, packed cell volume, mean cell hemoglobin concentration, mean cell hemoglobin, thrombocytes, leucocytes, differential white cell count with cell morphology, reticulocytes, prothrombin time, activated partial thromboplastin time, fibrinogen

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: just before necropsy
- Parameters examined: sodium, potassium, chloride, calcium, inorganic phosphorus, glucose, urea, creatinine, total bilirubin, total proteins, albumin, albumin/globulin ratio, total cholesterol, triglycerides, alkaline phosphatase, aspartate aminotransferase, alanine aminotransferase, bile acid

NEUROBEHAVIOURAL EXAMINATION: Yes
- Time schedule for examinations: once at the end of treatment period (day 5 post partum for females)
- Battery of functions tested: sensory activity / grip strength / motor activity / other: standard reflexes and responses, rectal temperature
Ovaries and uterine content:
The ovaries and uterine content was examined after termination: Yes
Examinations included:
- Gravid uterus weight: No
- Number of corpora lutea: Yes
- Number of implantations: Yes
- Number of early resorptions: No
- Number of late resorptions: No
Fetal examinations:
- External examinations: Yes (gross external abnormalities and macroscopic examination)
- Soft tissue examinations: No
- Skeletal examinations: No
- Head examinations: No
Statistics:
- Comparison of mean values by one-way variance analysis and Dunnett's test
- Percentage values compared by Fisher's exact probability test
- Specific sequences of tests used for clinical chemistry and organ weight data
Indices:
Maternal indices
The following parameters were evaluated:
- Pre-implantation loss,
- Post-implantation loss,
- Mating index,
- Fertility index,
- Gestation index,
- Number of corpora lutea,
- Number of implantations,
- Number of pups delivered.

Offspring viability indices
The following parameters were evaluated:
- Live birth index,
- Viability index on day 4 post-partum,
- Mean litter size,
- Pup sex ratios.
Clinical signs:
no effects observed
Description (incidence and severity):
Isolated and non-dose-related incidences of soft feces, loud breathing, chromorhinorrhea and reflux at dosing were observed in all groups treated with Cerium oxide. Generally only one animal was affected and the signs were short-lived. It was considered that none of these represented signs of toxicity of the test item.
In addition, hairloss and cutaneous lesions were observed in the control group and the groups treated at 150 or 450 mg/kg/day. These signs are commonly observed in laboratory rats of this strain and are considered not to be related to treatment with the test item.
Mortality:
no mortality observed
Description (incidence):
There were no unscheduled deaths during the study.
Body weight and weight changes:
no effects observed
Description (incidence and severity):
There were no effects of treatment with the test item on mean female body weight or body weight gains during the premating, gestation or lactation phases.
The female group treated at 450 mg/kg/day had a slightly lower mean body weight gain over the gestation period when compared with the controls but the difference was mainly due to one female with a low body weight gain which skewed the group mean.
Food consumption and compound intake (if feeding study):
no effects observed
Description (incidence and severity):
There were no effects of treatment with the test item on mean female food consumption.
Organ weight findings including organ / body weight ratios:
no effects observed
Description (incidence and severity):
Organ weight changes (principally of adrenals, spleen and thymus) were considered not to be related to the test item as they were small in amplitude, had no gross or microscopic correlates, were not dose-related in magnitude, and/or were not consistent for the sexes.
Gross pathological findings:
no effects observed
Description (incidence and severity):
In high-dose female R24319 there was a dilatation of the cervix associated with serous contents in the uterine horns. These findings were explained at microscopic examination by the presence of a congenital anomaly involving the cervix and distal vagina.
The other macroscopic findings had no histologic correlates or correlated with common histologic findings in control rats, and were considered to be incidental. One mid-dose female showed a thymic mass which correlated with a chronic abscess at microscopic examination.
Histopathological findings: non-neoplastic:
no effects observed
Description (incidence and severity):
In the few low-, mid-, and high-dose females which were sacrificed because of no delivery, no estrous cycle abnormalities were found at microscopic examination of the genital organs. However, in high-dose female R24319, a congenital anomaly involving the cervix and distal vagina explained the absence of mating/pregnancy. Both the cervix and the distal vagina were dilated with presence of a large mucosal protrusion in the cavity.
Pre- and post-implantation loss:
effects observed, non-treatment-related
Description (incidence and severity):
There were no effects on the extent of post-implantation loss. The mean pre-implantation loss was higher in all groups treated with the test item when compared with the controls, however these variations were not dose-related nor statistically significant. It was therefore considered that this did not represent an effect of treatment with the test item.
Description (incidence and severity):
Migrated Data from removed field(s)
Field "Effects on pregnancy duration" (Path: ENDPOINT_STUDY_RECORD.DevelopmentalToxicityTeratogenicity.ResultsAndDiscussion.ResultsMaternalAnimals.MaternalDevelopmentalToxicity.EffectsOnPregnancyDuration): no effects observed
Field "Description (incidence and severity)" (Path: ENDPOINT_STUDY_RECORD.DevelopmentalToxicityTeratogenicity.ResultsAndDiscussion.ResultsMaternalAnimals.MaternalDevelopmentalToxicity.DescriptionIncidenceAndSeverityEffectsOnPregnancyDuration): There were no effects on the duration of gestation.
Description (incidence and severity):
There were no effects of treatment with the test item on mating; all females at all dose-levels mated.
The mean number of days of pairing before mating was within the normal range, although the groups treated at 150 or 450 mg/kg/day took longer to mate than the controls; up to 4 or 5 days of pairing before mating is considered to be normal based on a normal estrous cycle of 4 to 5 days.
Females R24297 (150 mg/kg/day) and R24303 (450 mg/kg/day) stayed for 1 week or more in diestrus before mating. Both females were not pregnant. Other than these two females, all estrous cycles were considered to be normal.
There were two, one and three non-pregnant females in the groups treated at 150, 450 or 1000 mg/kg/day, respectively. In the non-pregnant female R24319 (1000 mg/kg/day), a congenital anomaly involving the cervix and distal vagina explained the absence of mating/pregnancy. Females R24315 and R24316 (1000 mg/kg/day) were in pro-estrous on the day before mating and so should have been in estrous on the day of mating. Females R24303 (450 mg/kg/day) and R24297 (150 mg/kg/day) had been in diestrous for longer than normal before mating but this is not uncommon and pregnancy does occur after a prolonged period of di-estrous. Female R24291 (150 mg/kg/day) mated on the first day so the cycle stage was unknown. The last three females may have mated on an inappropriate day in the estrus cycle which could explain the lack of pregnancy. Although non-pregnancy was not observed in control females and no sound explanation was found for all non-pregnant females but one, the absence of pregnancy in females treated at 150, 450 or 1000 mg/kg/day was considered in cidental and not related to the test substance.
There were no effects on the mean numbers of corpora lutea, implantations or pups at any dose level, nor on the duration of gestation or the extent of post-implantation loss. The mean pre-implantation loss was higher in all groups treated with the test item when compared with the controls, however these variations were not dose-related nor statistically significant and there was no influence on the mean number of pups delivered betwwen control and treated groups. It was therefore considered that this did not represent an effect of treatment with the test item.
Key result
Dose descriptor:
NOEL
Effect level:
1 000 mg/kg bw/day (nominal)
Based on:
test mat.
Basis for effect level:
other: No relevant effects up to highest dose tested
Description (incidence and severity):
Migrated Data from removed field(s)
Field "Fetal/pup body weight changes" (Path: ENDPOINT_STUDY_RECORD.DevelopmentalToxicityTeratogenicity.ResultsAndDiscussion.ResultsFetuses.FetalPupBodyWeightChanges): no effects observed
Field "Description (incidence and severity)" (Path: ENDPOINT_STUDY_RECORD.DevelopmentalToxicityTeratogenicity.ResultsAndDiscussion.ResultsFetuses.DescriptionIncidenceAndSeverityFetalPupBodyWeightChanges): There were no effects of treatment with the test item; the mean body weights and mean body weight gain of the pups from the groups treated with test item were slightly higher than those of the controls on days 1 and day 5 post-partum.
Changes in sex ratio:
no effects observed
Description (incidence and severity):
The percentage of male pups was similar between all groups.
Changes in postnatal survival:
no effects observed
Description (incidence and severity):
Pup survival was similar between the control group and the groups treated with Cerium oxide.
External malformations:
no effects observed
Description (incidence and severity):
One pup from the group treated at 450 mg/kg/day had malpositioned right testis, small right epididym is and pale right kidney. As these were observed in only one pup out of 137 in this group and out of a total of 346 pups from the groups treated with test item, it was considered not to be related to treatment but to be a congenital malformation.
Other effects:
no effects observed
Description (incidence and severity):
Isolated clinical signs were observed in a few pups treated at 150 mg/kg/day, typically hematoma or scabbing. It was considered that there were no effects of treatment with the test item.
There were no effects of treatment on pup body weight with the test item; the mean body weights and mean body weight gain of the pups from the groups treated with test item were slightly higher than those of the controls on days 1 and day 5 post-partum.
Key result
Dose descriptor:
NOEL
Effect level:
1 000 mg/kg bw/day (nominal)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: No relevant effects up to highest dose tested
Key result
Developmental effects observed:
no
Conclusions:
No significant developmental toxicity was observed up to the highest tested dose, i.e. 1000 mg/kg.
Executive summary:

In an OECD TG 422-compliant study, the potential general and reproductive or developmental toxicity of Cerium Oxide were tested following daily oral administration by gavage to 10-week old Sprague-Dawley rats (10/sex) from 2 weeks before mating, through mating and, for the females, through gestation until day 5 post-partum, at the dose levels of 0 (0.5% aqueous methylcellulose solution), 150, 450 or 1000 mg/kg (except for the 3 days of dosing when an error in density measurements resulted in dose levels of slight overdosing at 168, 509 or 1150 mg/kg, respectively).

 

No unscheduled deaths or treatment-related clinical signs occurred during the study. There were no effects on body weight, body weight gain or food consumption at any dose level. The Functional Observational Battery assessment, hematology and blood chemistry parameters revealed no treatment-related effects. There were no relevant differences from controls for pairing, mating, fertility and delivery parameters. Pups showed no effects of treatment on survival or body weight performance. Macroscopic and microscopic examinations at necropsy did not reveal any treatment-related findings and there were no treatment-related changes in organ weights.

 

The NOELs for parental toxicity, for reproductive performance (mating and fertility) and for toxic effects on progeny were therefore all considered to be 1000 mg/kg.

 

No classification for repeat-dose toxicity or reproductive or developmental toxicity is warranted based on the absence of relevant effects in this study, according to the criteria of Annex VI Directive 67/548/

EEC or UN/EU GHS.

 

This study is classified as acceptable. It satisfies the OECD 422 guideline requirements on repeated dose toxicity testing and reproduction/developmental toxicity screening.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2010
Report Date:
2010

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 422 (Combined Repeated Dose Toxicity Study with the Reproduction / Developmental Toxicity Screening Test)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent

Test animals

Species:
rat
Strain:
Sprague-Dawley
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Janvier, Le Genest-Saint-Isle, France
- Age at study initiation: 10 weeks old
- Weight at study initiation: 402 - 454 g (males) / 244 - 285 g (females)
- Fasting period before study: no
- Housing: individual (except during pairing), in wire-mesh cages (43 x 21.5 x 18 cm) or polycarbonate cages (43 x 21.5 x 20 cm) for females during lactation
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: 6 days

ENVIRONMENTAL CONDITIONS
- Temperature: 22 ± 2°C
- Humidity: 50 ± 20°C
- Air changes: about 12 per hr
- Photoperiod: 12 hrs dark / 12 hrs light (7.00 am - 7.00 pm)

IN-LIFE DATES: From 14 May 2008 To 14 July 2008

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
other: 0.5% aqueous methylcellulose solution
Details on exposure:
PREPARATION OF DOSING SOLUTIONS:
- Test item ground to fine powder using mortar and pestle, suspended in vehicle and homogenized by magnetic stirrer
- Dosing solutions prepared for use for up to 12 days and stored in brown flasks at +4°C, protected from light, prior to use

VEHICLE
- Justification for use and choice of vehicle (if other than water): appropriate for oral suspensions
- Concentration in vehicle: 30, 90 or 200 mg/mL
- Amount of vehicle (if gavage): 5 mL/kg
- Lot/batch no. (if required): Sigma batches 017K0052 and 066K0129 (methylcellulose)
- Purity: 0.5%
Details on mating procedure:
- M/F ratio per cage: one female was placed with one male
- Length of cohabitation: Each female was placed with the same male until mating occurs or 14 days had elapsed. Any pairs with no evidence of mating after 14 days were separated and the female was placed for 7 days with a different male from the same dose level group who had already mated.
- Proof of pregnancy: Confirmation of mating was made in the morning, every day up to proof of mating, by checking for the presence of a vaginal plug or of sperm in a vaginal lavage.
- Further matings after two unsuccessful attempts: no
- After successful mating each pregnant female was caged (how): individually
- Any other deviations from standard protocol: no
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
During the pre-study period, the homogeneity, stability and concentration of two dosage forms prepared at low and high concentrations (33.6 and 230 mg/mL) were checked using ICP-OES (Inductively Coupled Plasma-Optical Emission Spectrometry) after validation of the analytical method. The results showed acceptable homogeneity and stability of both concentrations over 12 days of storage at +4°C protected from light.

During the study, the concentration of the test item (0, 33.6, 101.7 and 230 mg/mL in week 1 and 0, 30, 90 and 200 mg/mL in week 6) and homogeneity of the dosage forms were determined in samples of each control and test item dosage form prepared for use in weeks 1 and 6. The results showed acceptable homogeneity and concentration of all dosage forms analyzed. Precision (RSD ≤ 10%) and accuracy (100 ± 10%) of the method were found to be satisfactory. The homogeneity of the dosage form prepared for week 6 at 200 mg/mL was slightly outside the acceptance criteria with a RSD of 12.8% but this was considered to have no impact on the validity of the study.
Duration of treatment / exposure:
- Males: 15 days before mating, during mating (up to 3 weeks), until euthanasia (4 weeks total)
- Females: 15 days before mating, during mating (up to 3 weeks), during pregnancy, during lactation, until day 5 post partum inclusive
Frequency of treatment:
Once daily, 7 days a week
Details on study schedule:
Not appropriate
Doses / concentrationsopen allclose all
Dose / conc.:
0 mg/kg bw/day
Dose / conc.:
168 mg/kg bw/day (nominal)
Remarks:
Basis: nominal, up until day 3 due to an error of density measurement
Dose / conc.:
509 mg/kg bw/day (nominal)
Remarks:
Basis: nominal, up until day 3 due to an error of density measurement
Dose / conc.:
1 150 mg/kg bw/day (nominal)
Remarks:
Basis: nominal, up until day 3 due to an error of density measurement
Dose / conc.:
150 mg/kg bw/day (nominal)
Remarks:
Basis: nominal from day 4 on
Dose / conc.:
450 mg/kg bw/day (nominal)
Remarks:
Basis: nominal from day 4 on
Dose / conc.:
1 000 mg/kg bw/day (nominal)
Remarks:
Basis: nominal from day 4 on
No. of animals per sex per dose:
10
Control animals:
yes, concurrent vehicle
Details on study design:
- Dose selection rationale: on the basis of a previous 10-day dose-range finding study (CIT No. 33178 TSR) at the same dose levels
- Rationale for animal assignment (if not random): computerized stratification procedure so that the average body weight of each group was similar
Positive control:
Not included

Examinations

Parental animals: Observations and examinations:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: at least twice daily (morbidity and mortality) or once daily (clinical signs)

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: once before beginning of treatment period and once weekly during treatment period
Observations included (but were not limited to) changes in the skin, fur, eyes, mucous membranes, occurrence of secretions and excretions and autonomic activity (e.g. lachrymation, piloerection, pupil size, unusual respiratory pattern). Changes in gait, posture and response to handling as well as the presence of clonic or tonic movements, stereotypes (e.g. excessive grooming, repetitive circling) or bizarre behavior (e.g. self-mutilation, walking backwards) were also recorded.

BODY WEIGHT: Yes
- Time schedule for examinations:
Males: on first day of treatment and then once weekly
Females: on first day of treatment and then once weekly until mated, and on days 0, 7, 14 and 20 post coitum and days 1 and 5 post partum

FOOD CONSUMPTION: Yes
- Time schedule for examinations:
Males: once weekly over 7-day periods from first day of dosing
Females: once weekly over 7-day periods from first day of dosing through gestation and lactation
Not recorded during pairing period

WATER CONSUMPTION: No

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: Yes
- Time schedule for collection of blood: just before necropsy
- Anaesthetic used for blood collection: Yes (isoflurane)
- Animals fasted: Yes (overnight for at least 14 hours)
- How many animals: first 5 males and 5 females to deliver in each group
- Parameters examined: erythrocytes, hemoglobin, mean cell volume, packed cell volume, mean cell hemoglobin concentration, mean cell hemoglobin, thrombocytes, leucocytes, differential white cell count with cell morphology, reticulocytes, prothrombin time, activated partial thromboplastin time, fibrinogen

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: just before necropsy
- Anaesthetic used for blood collection: Yes (isoflurane)
- Animals fasted: Yes (overnight for at least 14 hours)
- How many animals: first 5 males and 5 females to deliver in each group
- Parameters examined: sodium, potassium, chloride, calcium, inorganic phosphorus, glucose, urea, creatinine, total bilirubin, total proteins, albumin, albumin/globulin ratio, total cholesterol, triglycerides, alkaline phosphatase, aspartate aminotransferase, alanine aminotransferase, bile acid

URINALYSIS: No

NEUROBEHAVIOURAL EXAMINATION: Yes
- Time schedule for examinations: once at the end of treatment period (day 5 post partum for females)
- Dose groups that were examined: all groups (first 5 males and 5 females to deliver)
- Battery of functions tested: sensory activity / grip strength / motor activity / other: standard reflexes and responses, rectal temperature

Details:
The FOB included a detailed clinical examination, measurement of reactivity to manipulation or to different stimuli and motor activity. The animals were randomized in order to ensure "blind" evaluation. All animals were observed in the cage, in the hand and in the standard arena.
The following parameters were assessed and graded:
- "touch escape" or ease of removal from the cage,
- in the hand: fur appearance, salivation, lachrymation, piloerection, exophthalmos, reactivity to handling, pupil size (presence of myosis or mydriasis),
- in the standard arena (2-minute recording): grooming, palpebral closure, defecation, urination, tremors, twitches, tonic and clonic convulsions, gait, arousal (hypo- and hyper-activity), posture, stereotypy, behavior, breathing, ataxia and hypotonia.
Then, the following parameter measurements, reflexes and responses were recorded:
- touch response,
- forelimb grip strength,
- pupillary reflex,
- visual stimulus response,
- auditory startle reflex,
- tail pinch response,
- righting reflex,
- landing foot splay,
- at the end of observation: rectal temperature.
Finally, motor activity of all animals was measured once by automated infra-red sensor equipment over a 60-minute period.

OTHER: No other general toxicity parameter
Oestrous cyclicity (parental animals):
Estrous cyclicity determined from a fresh vaginal lavage (stained with methylene blue) every morning during mating period until effective mating
Sperm parameters (parental animals):
Microscopic examination made special emphasis on stages of spermatogenesis in the male gonads and histopathology of interstitial testicular cell structure
Litter observations:
STANDARDISATION OF LITTERS
- Performed on day 4 postpartum: no

PARAMETERS EXAMINED
The following parameters were examined in offspring:
- Stillbirths, live births
- The total litter size and numbers of pups of each sex (sex ratio) was recorded as soon as possible after birth.
- Postnatal mortality: The litters were observed daily in order to note the number of live, dead and cannibalized pups.
- The pups were observed daily for clinical signs.
- Weight gain: The weight of each pup was recorded on days 1 and 5 post-partum.

GROSS EXAMINATION OF DEAD PUPS: yes (external abnormalities)
Postmortem examinations (parental animals):
SACRIFICE
After overnight fasting, at least 14 hours, all surviving F0 animals were deeply anesthetized by an intraperitoneal injection of sodium pentobarbital and sacrificed by exsanguination:
- males: after the end of the mating period (after at least 4 weeks of treatment),
- females: on day 6 post-partum,

GROSS NECROPSY
- A complete macroscopic post-mortem examination was performed on all animals. This included examination of the external surfaces, all orifices, the cranial cavity, the external surfaces of the brain, the thoracic, abdominal and pelvic cavities with their associated organs and tissues and the neck with its associated organs and tissues. Special attention was paid to the reproductive organs. The numbers of corpora lutea and implantation sites were also recorded.

HISTOPATHOLOGY / ORGAN WEIGHTS
A microscopic examination was performed on:
- all the tissues listed in the Table below for the first five males and females of the control and high-dose groups (groups 1 and 4) sacrificed as scheduled
- all macroscopic lesions
The microscopic examination made special emphasis on stages of spermatogenesis in the male gonads and histopathology of interstitial testicular cell structure.
Postmortem examinations (offspring):
Pups found dead, prematurely sacrificed and pups sacrificed on day 5 post-partum were carefully examined externally for gross external abnormalities and a macroscopic examination was performed. There was no preservation of tissues.
Statistics:
- Comparison of mean values by one-way variance analysis and Dunnett's test
- Percentage values compared by Fisher's exact probability test
- Specific sequences of tests used for clinical chemistry and organ weight data
Reproductive indices:
The following parameters were evaluated:
- Pre-implantation loss,
- Post-implantation loss,
- Mating index,
- Fertility index,
- Gestation index,
- Number of corpora lutea,
- Number of implantations,
- Number of pups delivered
Offspring viability indices:
The following parameters were evaluated:
- Live birth index,
- Viability index on day 4 post-partum,
- Mean litter size,
- Pup sex ratios

Results and discussion

Results: P0 (first parental generation)

General toxicity (P0)

Clinical signs:
no effects observed
Description (incidence and severity):
Isolated and non-dose-related incidences of soft feces, loud breathing, chromorhinorrhea and reflux at dosing were observed in all groups treated with Cerium oxide. Generally only one animal was affected and the signs were short-lived. It was considered that none of these represented signs of toxicity of the test item.
In addition, hairloss and cutaneous lesions were observed in the control group and the groups treated at 150 or 450 mg/kg/day. These signs are commonly observed in laboratory rats of this strain and are considered not to be related to treatment with the test item.
Mortality:
no mortality observed
Description (incidence):
There were no unscheduled deaths during the study.
Body weight and weight changes:
no effects observed
Description (incidence and severity):
There were no effects of treatment with the test item on mean male or female body weight or body weight gains during the premating, gestation or lactation phases.
The female group treated at 450 mg/kg/day had a slightly lower mean body weight gain over the gestation period when compared with the controls but the difference was mainly due to one female with a low body weight gain which skewed the group mean.
Food consumption and compound intake (if feeding study):
no effects observed
Description (incidence and severity):
There were no effects of treatment with the test item on mean male or female food consumption.
Organ weight findings including organ / body weight ratios:
no effects observed
Histopathological findings: non-neoplastic:
no effects observed
Description (incidence and severity):
A detailed, stage-aware qualitative evaluation of the testes was conducted in control and high dose males.
There were no microscopic findings related to the test item administration.
In the few low-, mid-, and high-dose females which were sacrificed because of no delivery, no estrous cycle abnormalities were found at microscopic examination of the genital organs. However, in high-dose female R24319, a congenital anomaly involving the cervix and distal vagina explained the absence of mating/pregnancy. Both the cervix and the distal vagina were dilated with presence of a large mucosal protrusion in the cavity.
Other effects:
not examined

Reproductive function / performance (P0)

Reproductive function: oestrous cycle:
no effects observed
Reproductive function: sperm measures:
not examined
Reproductive performance:
no effects observed
Description (incidence and severity):
There were no effects of treatment with the test item on mating; all females at all dose-levels mated and only one male treated at 150 mg/kg/day did not mate.
The mean number of days of pairing before mating was within the normal range, although the groups treated at 150 or 450 mg/kg/day took longer to mate than the controls; up to 4 or 5 days of pairing be fore mating is considered to be normal based on a normal estrous cycle of 4 to 5 days.
Females R24297 (150 mg/kg/day) and R24303 (450 mg/kg/day) stayed for 1 week or more in diestrus before mating. Both females were not pregnant. Other than these two females, all estrous cycles were considered to be normal.
There were two, one and three non-pregnant females in the groups treated at 150, 450 or 1000 mg/kg/day, respectively. In the non-pregnant female R24319 (1000 mg/kg/day), a congenital anomaly involving the cervix and distal vagina explained the absence of mating/pregnancy. Females R24315 and R24316 (1000 mg/kg/day) were in pro-estrous on the day before mating and so should have been in estrous on the day of mating. Females R24303 (450 mg/kg/day) and R24297 (150 mg/kg/day) had been in diestrous for longer than normal before mating but this is not uncommon and pregnancy does occur after a prolonged period of di-estrous. Female R24291 (150 mg/kg/day) mated on the first day so the cycle stage was unknown. The last three females may have mated on an inappropriate day in the estrus cycle which could explain the lack of pregnancy. Although non-pregnancy was not observed in control females and no sound explanation was found for all non-pregnant females but one, the absence of pregnancy in females treated at 150, 450 or 1000 mg/kg/day was considered in
cidental and not related to the test substance.
There were no effects on the mean numbers of corpora lutea, implantations or pups at any dose level, nor on the duration of gestation or the extent of post-implantation loss. The mean pre implantation loss was higher in all groups treated with the test item when compared with the controls, however these variations were not dose-related nor statistically significant and there was no influence on the mean number of pups delivered betwwen control and treated groups. It was therefore considered that this did not represent an effect of treatment with the test item.

Effect levels (P0)

Key result
Dose descriptor:
NOEL
Remarks:
mating and fertility
Effect level:
1 000 mg/kg bw/day (nominal)
Based on:
act. ingr.
Sex:
male/female
Basis for effect level:
other: no relevant effects up to highest dose tested

Results: F1 generation

General toxicity (F1)

Clinical signs:
no effects observed
Description (incidence and severity):
Isolated clinical signs were observed in a few pups treated at 150 mg/kg/day, typically hematoma or scabbing. It was considered that there were no effects of treatment with the test item.
Mortality / viability:
no mortality observed
Description (incidence and severity):
Pup survival was similar between the control group and the groups treated with Cerium oxide.
Body weight and weight changes:
no effects observed
Description (incidence and severity):
There were no effects of treatment with the test item; the mean body weights and mean body weight gain of the pups from the groups treated with test item were slightly higher than those of the controls on days 1 and day 5 post-partum.
Sexual maturation:
not examined
Organ weight findings including organ / body weight ratios:
not examined
Gross pathological findings:
no effects observed
Description (incidence and severity):
One pup from the group treated at 450 mg/kg/day had malpositioned right testis, small right epididymis and pale right kidney. As these were observed in only one pup out of 137 in this group and out of a total of 346 pups from the groups treated with test item, it was considered not to be related to treatment but to be a congenital malformation.
Histopathological findings:
not examined

Details on results (F1)

OTHER FINDINGS (OFFSPRING)
Sex ratio: the percentage of male pups was similar between all groups.

Effect levels (F1)

Key result
Dose descriptor:
NOEL
Remarks:
toxicity on progeny
Generation:
F1
Effect level:
1 000 mg/kg bw/day (nominal)
Based on:
act. ingr.
Sex:
male/female
Basis for effect level:
other: no relevant effects up to highest dose tested

Overall reproductive toxicity

Reproductive effects observed:
not specified

Any other information on results incl. tables

Table 2: summary table of reproductive data

Dose level (mg/kg/d)

 

0

150

450

1000

Paired males + females

n

10 + 10

10 + 10

10 + 10

10 + 10

Pairs mated

n

10

10

10

10

Mating index

%

100.0

100.0

100.0

100.0

Mean number of days of pairing before mating

n

2.7

3.6

3.4

2.1

Pregnant female partners

n

10

8

9

7

Fertility index

%

100.0

80.0

90.0

70.0

Females with live concepti

n

10

8

9

7

Gestation index

%

100.0

100.0

100.0

100.0

 

Table 3: summary table of delivery data

Dose level (mg/kg/d)

0

150

450

1000

Number of pregnant females surviving delivery

Mean duration of gestation (days)

Mean number of corpora lutea

Mean number of implantations

Mean pre-implantation loss (%)

Mean number of pups delivered

Mean post-implantation loss (%)

10

21.9

19.4

18.2

5.8

14.7

18.7

8

21.9

18.6

16.1

12.9

14.1

12.1

9

21.9

19.9

17.1

12.4

15.4

9.4

7

21.9

19.1

16.1

15.2

14.3

12.7

 

Table 4: summary table of reproductive and litter data

Dose level (mg/kg/d)

 

0

150

450

1000

Females on Study

N

10

10

10

10

Females Mated

Mating Index

N

%

10 f

100.0

10

100.0

10

100.0

10

100.0

Females Pregnant

Female Fertility Index

N

%

10 f

100.0

8

80.0

9

90.0

7

70.0

Females with Liveborn

Gestation Index

N

%

10 f

100.0

8

100.0

9

100.0

7

100.0

Females Surviving Delivery

 

Duration of gestation

 

 

With stillborn pups

 

 

With all stillborn

 

 

With entire liveborn litter dying and/or missing, cannibalized, culled

Days 0-4

 

 

Days 0-5

 

N

 

Mean

S.D.

 

N

%

 

N

%

 

  

N

%

 

N

%

10 f

 

21.9 d

0.3

 

0 f

0.0

 

0 f

0.0

 

  

 0 f

0.0

 

0 f

0.0

8

 

21.9

0.4

 

0

0.0

 

0

0.0

 

  

 0

0.0

 

0

0.0

9

 

21.9

0.3

 

0

0.0

 

0

0.0

 

  

 0

0.0

 

0

0.0

7

 

21.9

0.4

 

0

0.0

 

0

0.0

 

  

 0

0.0

 

0

0.0

Litters with liveborn pups

N

10

8

9

7

Pups Delivered (total)

 

 

 

Liveborn

Live birth index

 

Stillborn

 

        

Culled (total)

Cannibalized

Missing

Died

 

Liveborn, not culled prior to day 5

N

Mean

S.D.

 

N

%

 

N

%

 

N

N

N

N

 

N

147

14.7 d

1.6

 

147 f

100.0

 

0 f

0.0

 

0

1

0

2

 

147

113

14.1

2.3

 

113

100.0

 

0

0.0

 

0

1

0

1

 

113

139

15.4

2.2

 

139

100.0

 

0

0.0

 

0

0

0

2

 

139

100

14.3

4.0

 

100

100.0

 

0

0.0

 

0

0

0

2

 

100

Pups dying, missing, and/or cannibalized

Day 0

 

 

Days 1-4

 

 

Days 5-7

 

 

N

%

 

N

%

 

N

%

 

0 f

0.0 

 

3 f

2.0

 

0 f

0.0

 

0

0.0

 

2

1.8

 

0

0.0

 

0

0.0

 

2

1.4

 

0

0.0

 

0

0.0

 

2

2.0

 

0

0.0

Pups surviving 4 days

Viability index

N

%

144 f

98.0

111

98.2

137

98.6

98

98.0

Pups surviving 5 days

Lactation index

N

%

144 f

100.0

111

100.0

137

100.0

98

100.0

Implantation sites per litter

N

Mean

S.D.

182

18.2 d

2.1

129

16.1

2.5

154

17.1

2.1

113

16.1

2.5

Corpora lutea

Total

Mean

S.D.

194

19.4 d

2.3

149

18.6

2.2

179

19.9

3.9

134

19.1

2.0

Preimplantation loss

Mean %

S.D.

5.8 d

8.2

12.9

13.4

12.4

11.6

15.2

12.7

Live pups / litter

Day 1

 

Day 4

 

Day 5

 

 

Mean

S.D.

 

Mean

S.D.

 

Mean

S.D.

 

14.5 d

1.6

 

14.4 d

1.6

 

14.4 d

1.6

 

14.0

2.2

 

13.9

2.3

 

13.9

2.3

 

15.3

2.1

 

15.2

1.9

 

15.2

1.9

 

14.1

4.0

 

14.0

4.3

 

14.0

4.3

Pup weight / Litter (grams)

Day 1

 

Day 5

 

 

Mean

S.D.

 

Mean

S.D. 

 

7.4 d

0.6

 

11.3 d

0.7

 

7.7

0.6

 

12.1

1.5

 

7.6

0.7

 

11.7

1.5

 

7.5

0.5

 

12.2

1.9

Sex ratio – male pups: total pups

Day 0

 

 

Day 5

 

 

N

%

 

N

%

 

73 f

49.7

 

71 f

49.3

 

51

45.1

 

51

45.9

 

76

54.7

 

74

54.0

 

50

50.0

 

49

50.0

Statistical key: d = ANOVA + Dunnett-test; f = Fishers exact test; N = number of animals

 

Applicant's summary and conclusion

Conclusions:
No significant reproductive or developmental toxicity was observed up to the highest tested dose, i.e. 1000 mg/kg.
Executive summary:

In an OECD TG 422-compliant study, the potential general and reproductive or developmental toxicity of Cerium Oxide were tested following daily oral administration by gavage to 10-week old Sprague-Dawley rats (10/sex) from 2 weeks before mating, through mating and, for the females, through gestation until day 5 post partum, at the dose levels of 0 (0.5% aqueous methylcellulose solution), 150, 450 or 1000 mg/kg (except for the 3 days of dosing when an error in density measurements resulted in dose levels of slight overdosing at 168, 509 or 1150 mg/kg, respectively).

No unscheduled deaths or treatment-related clinical signs occurred during the study. There were no effects on body weight, body weight gain or food consumption at any dose level. The Functional Observational Battery assessment, hematology and blood chemistry parameters revealed no treatment-related effects. There were no relevant differences from controls for pairing, mating, fertility and delivery parameters. Pups showed no effects of treatment on survival or body weight performance. Macroscopic and microscopic examinations at necropsy did not reveal any treatment-related findings and there were no treatment-related changes in organ weights.

The NOELs for parental toxicity, for reproductive performance (mating and fertility) and for toxic effects on progeny were therefore all considered to be 1000 mg/kg.

No classification for repeat-dose toxicity or reproductive or developmental toxicity is warranted based on the absence of relevant effects in this study, according to the criteria of Annex VI Directive 67/548/EEC or UN/EU GHS.

This study is classified as acceptable. It satisfies the OECD 422 guideline requirements on repeated dose toxicity testing and reproduction/developmental toxicity screening.