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Toxicological information

Developmental toxicity / teratogenicity

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Administrative data

Endpoint:
developmental toxicity
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2016
Report Date:
2016

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 414 (Prenatal Developmental Toxicity Study)
Deviations:
no
Qualifier:
according to
Guideline:
EPA OPPTS 870.3700 (Prenatal Developmental Toxicity Study)
Deviations:
no
Qualifier:
according to
Guideline:
other: EC Methods for the Determination of Toxicity and Other Health Effects Directive 440/2008/EC Method B.31 (2008)
Deviations:
no
Qualifier:
according to
Guideline:
other: MAFF Japan Test Guidelines for Agricultural Chemicals 12-Nousan-8147 (2000)
Deviations:
no
GLP compliance:
yes
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: particulate/powder
Details on test material:
Purity: 91.7%

Test animals

Species:
rat
Strain:
other: Crl:CD(SD)
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River Laboratories International, Inc., Raleigh, NorthCarolina, U.S.A.
- Age at study initiation: Approximately 67 days
- Weight at study initiation: Approximately 202-225 grams
- Housing: Animals were housed in groups (whenever possible) in solid-bottom caging with bedding and Nestlets™ as enrichment
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: All animals were housed in quarantine for 1-5 days. All animals were acclimated to laboratory conditions for atleast 3 days prior to study start.

Environmental conditions:
-Temperature: 20-26ºC
-Humidity: 30-70%
-Photo period: 12 hour light/dark cycle
-Air changes: Not reported

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
other: 0.5% methylcellulose with 0.1% Tween® 80
Details on exposure:
PREPARATION OF DOSING SOLUTIONS:

VEHICLE
- Justification for use and choice of vehicle (if other than water): Not reported
- Concentration in vehicle: 0.5% methylcellulose with 0.1% Tween® 80
- Amount of vehicle (if gavage): 5 mL/kg
- Purity: Not reported
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
Samples were collected from the top, middle, and bottom of each concentration at the initial dose preparation and were analyzed to verify homogeneity and concentration (average of homogeneity samples) of test substance in the formulations. Toward the end of the study, samples were taken to verify concentration. A sample of control vehicle was analyzed together with each set of samples to verify the absence of test substance in the vehicle.

Data from the analysis of the formulation samples indicated that the test substance was homogeneously mixed (RSD's <2.8%) in the vehicle at the targeted concentrations (from 90.6% to 113% of nominal) in the vehicle under the conditions of the study. Test substance was not found in the 0 mg/kg/day sample (control).

Stability in concentration range 1 to 200 mg/mL had been established in previously conducted study.
Duration of treatment / exposure:
Gestation day (GD) 6 through GD 20
Frequency of treatment:
Daily
Duration of test:
15 days
Doses / concentrationsopen allclose all
Dose / conc.:
0 mg/kg bw/day
Dose / conc.:
20 mg/kg bw/day
Dose / conc.:
80 mg/kg bw/day
Dose / conc.:
320 mg/kg bw/day
No. of animals per sex per dose:
22 females
Control animals:
yes, concurrent vehicle
Details on study design:
- Dose selection rationale: Dose levels of the test substance have been selected based on results from a one generation reproductive toxicity study in rats, a 90-day oral gavage subchronic toxicity study in rats, and a 2-week dose range finding toxicity study by oral gavage in rats, and in consultation with the sponsor. Based on the adverse effects observed in the kidneys (adverse vacuolation of tubules) of parental females at 200 mg/kg/day and above in the one generation reproductive toxicity study in rats, dose levels selected for the current study were 0, 20, 80, and 320 mg/kg/day.

Examinations

Maternal examinations:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: Twice daily

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Twice daily on GD 6-20 (during weighing and atleast 2 hours post dosing)

BODY WEIGHT: Yes
- Time schedule for examinations: Daily on GD 6-21

FOOD CONSUMPTION AND COMPOUND INTAKE: Yes, GD 6, 8, 10, 12, 14, 16, 18, 20 and 21
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes
- Compound intake calculated as time-weighted averages from the consumption and body weight gain data: Yes

POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day # 21
- Organs weights: Liver and kidneys
Ovaries and uterine content:
The ovaries and uterine content was examined after termination: Yes
Examinations included:
- Gravid uterus weight: Yes
- Number of corpora lutea: Yes
- Number of implantations: Yes
- Number of early resorptions: Yes
- Number of late resorptions: Yes
- Other: For each female with visible implantation sites, the types of implantations (live and dead fetuses, early and late resorptions) and their relative positions in the uterus were recorded. The body weight of each live fetus was recorded.
Fetal examinations:
- External examinations: Yes [all per litter]
- Soft tissue examinations: Yes [half per litter]
- Skeletal examinations: Yes [all per litter]
- Head examinations: Yes for live fetuses with malformations visible at external exam
Statistics:
See any other information on materials and methods section

Results and discussion

Results: maternal animals

General toxicity (maternal animals)

Clinical signs:
effects observed, non-treatment-related
Description (incidence and severity):
There were no test substance-related clinical observations at any level tested; the observations that were recorded were unremarkable and occurred infrequently.
Mortality:
no mortality observed
Description (incidence):
There was no test substance-related mortality at any level tested; all animals on study survived until scheduled euthanasia
Body weight and weight changes:
effects observed, non-treatment-related
Description (incidence and severity):
There were no adverse test substance-related effects on maternal body weight parameters at any level tested. At 320 mg/kg/day, there was a treatment-related, statistically significant non-adverse reduction (49% lower than control values) in mean body weight gain that occurred after the first few days of dosing (days 6-8G). Additionally, there was a slight, statistically significant reduction (24% lower than control) in mean body weight gain at 320 mg/kg/day over days 20 to 21 of gestation. These changes were not considered adverse since there was no statistically significant impact on cumulative (absolute or adjusted) body weight gain at this level as compared to the control group. Mean overall (days 6-21) absolute/adjusted body weight gains were 2%/8% lower than control group at 320 mg/kg/day, respectively. These changes were of minimal magnitude and were not statistically significantly (p<0.05) different from control values.

Occasional instances of statistical significance observed during the course of the study that did not demonstrate a dose response or was not of significant magnitude to impact overall values was not considered treatment-related.
Food consumption and compound intake (if feeding study):
effects observed, non-treatment-related
Description (incidence and severity):
There were no adverse, test substance-related effects on maternal food consumption at any level tested. At 320 mg/kg/day, there were treatment-related non-adverse reductions in mean food consumption that corresponded with effects on body weight gains during the first few days of dosing (GD 6-10). Mean food consumption was 11% lower than control group from gestation days 6 to 10. Although considered treatment-related, these effects were not considered adverse since there was no impact on cumulative (GD 6-21) mean food consumption as compared to concurrent control values.

Occasional instances of statistical significance observed during the course of the study that did not demonstrate a dose response or was not of significant magnitude to impact overall values was not considered treatment-related.
Ophthalmological findings:
not examined
Haematological findings:
not examined
Clinical biochemistry findings:
not examined
Urinalysis findings:
not examined
Behaviour (functional findings):
not examined
Immunological findings:
not examined
Organ weight findings including organ / body weight ratios:
effects observed, non-treatment-related
Description (incidence and severity):
There were no test substance-related maternal organ weight effects at any level tested. The observations that were recorded were unremarkable and did not follow any treatment related pattern.
Gross pathological findings:
effects observed, non-treatment-related
Description (incidence and severity):
There were no test substance-related maternal gross postmortem observations at any level tested. The observations that were recorded were unremarkable and did not follow any treatment related pattern.
Histopathological findings: non-neoplastic:
not examined
Histopathological findings: neoplastic:
not examined

Maternal developmental toxicity

Number of abortions:
no effects observed
Pre- and post-implantation loss:
no effects observed
Total litter losses by resorption:
no effects observed
Early or late resorptions:
no effects observed
Dead fetuses:
no effects observed
Description (incidence and severity):
There were no fetuses classified as dead on this study.
Changes in pregnancy duration:
not specified
Description (incidence and severity):
Migrated Data from removed field(s)
Field "Effects on pregnancy duration" (Path: ENDPOINT_STUDY_RECORD.DevelopmentalToxicityTeratogenicity.ResultsAndDiscussion.ResultsMaternalAnimals.MaternalDevelopmentalToxicity.EffectsOnPregnancyDuration): not specified
Changes in number of pregnant:
not specified

Effect levels (maternal animals)

Key result
Dose descriptor:
NOAEL
Remarks:
Maternal toxicity
Effect level:
320 mg/kg bw/day
Based on:
test mat.
Basis for effect level:
other: There was no adverse maternal toxicity observed at any dose level tested.

Maternal abnormalities

Abnormalities:
no effects observed

Results (fetuses)

Fetal body weight changes:
not examined
Reduction in number of live offspring:
no effects observed
Changes in sex ratio:
no effects observed
External malformations:
effects observed, non-treatment-related
Description (incidence and severity):
There were no test substance-related fetal malformations or variations observed at any dose level tested.
Skeletal malformations:
effects observed, non-treatment-related
Visceral malformations:
effects observed, non-treatment-related
Details on embryotoxic / teratogenic effects:
Reproductive Outcome and Litter Data: There were no test substance-related effects on reproductive outcome and quantitative litter data. The mean number of corpora lutea, implantation sites, resorptions, live fetuses, as well as mean fetal weight and sex ratio were generally comparable across all groups tested. There was a statistically significant increase in mean number of corpora lutea and implantation sites observed at 80 mg/kg/day. This change was not considered treatment-related since there was no dose response observed for these parameters. Mean corpora lutea and implantation site numbers observed at 320 mg/kg/day were comparable to control group values.

Fetal Alterations:
Malformations and Variations: There were no test substance-related fetal malformations or variations observed at any dose level tested. The fetal malformations that were observed were unremarkable and either a)occurred with low frequency across the dose levels tested, b) were not observed in fetuses at the high dose level, or c) were not statistically significantly increased variations as compared to control group values. The fetal variations that were observed were unremarkable and occurred with low frequency across the dose levels tested.

Effect levels (fetuses)

Key result
Dose descriptor:
NOAEL
Remarks:
Developmental toxicity
Effect level:
320 mg/kg bw/day
Based on:
test mat.
Basis for effect level:
other: There was no adverse developmental toxicity observed at any dose level tested.

Fetal abnormalities

Abnormalities:
no effects observed

Overall developmental toxicity

Developmental effects observed:
no

Applicant's summary and conclusion

Conclusions:
Under the conditions of this study, there was no evidence of either maternal or developmental toxicity at doses up to 320 mg/kg/day. Therefore, the no-observed-effect level (NOAEL) for maternal and developmental toxicity was 320 mg/kg/day.
Executive summary:

The purpose of this study was to evaluate the potential maternal and developmental toxicity of the test substance in pregnant rats. The test substance was administered orally by gavage to time-mated animals daily beginning on gestation day (GD) 6 through GD 20. The dose levels used in the current study were 0, 20, 80, and 320 mg/kg/day; control group animals were administered the 0.5% methylcellulose with 0.1% Tween® 80. Samples of the dosing formulations were collected and analyzed near the beginning and end of the dosing period. The results of these analyses confirmed that the formulations were at targeted concentrations, uniformly mixed, and stable under the experimental conditions used during the study. During the in-life portion of the study, body weights, food consumption, and clinical observations before and after dosing were collected on a daily basis. All dams were euthanized on GD 21; the gross necropsy included an examination and description of uterine contents including counts of implantation sites, resorptions, and live and dead fetuses. Ovarian corpora lutea counts were recorded. The liver and kidneys from all females surviving to scheduled euthanasia were weighed and saved. All live fetuses were examined externally and euthanized; following euthanasia, fresh visceral and head examinations were performed on selected fetuses. The fetal carcasses were then processed and examined for skeletal alterations. There was no adverse test substance-related maternal or developmental toxicity observed on this study. There was no early mortality nor were there clinical signs of toxicity at any level tested. There were no treatment-related adverse effects on body weight or food parameters on this study. There were treatment-related, but non-adverse effects on body weight gain and food consumption parameters at 320 mg/kg/day. The effects observed occurred during the first few days of dosing and did not adversely impact overall cumulative (GD 6-21) body weight gain or food consumption parameters. Therefore, these treatment-related effects were considered non-adverse. The mean number of corpora lutea, implantation sites, resorptions, live fetuses, as well as mean fetal weight and sex ratio were generally comparable across all groups tested. There were no treatment-related fetal anomalies observed at any level tested. There were no treatment-related maternal gross or organ weight (liver and kidneys) effects observed on this study at any level tested. Under the conditions of this study, there was no evidence of either maternal or developmental toxicity at doses up to 320 mg/kg/day. Therefore, the no-observed-effect level (NOAEL) for maternal and developmental toxicity was 320 mg/kg/day.